Melanoma Screening by Means of Complete Skin Exams for All Patients in a Dermatology Practice Reduces the Thickness of Primary Melanomas at Diagnosis

Objective: Previous studies have shown that dermatologists detect thinner melanomas than both non-dermatologists and patients in high incidence areas. The authors report depths of melanomas in a central New York practice where the incidence is low, hypothesizing that incidental melanomas detected by a dermatologist will be thinner than melanomas that are part of the chief complaint. Design: A retrospective chart review examining melanoma depth to determine the importance of universal full skin exams. Setting: Private dermatology clinic in Auburn, New York, employing one board-certified dermatologist and two physician extenders. Participants: Men and women who attended the clinic between 2003 and 2013 who had 235 biopsy-proven melanomas. Total patient visits in this time period was 50,699. Measurements: Office notes were reviewed to determine the chief complaint, patient demographics, and depth of the tumor. The authors noted if the melanoma was discovered by the patient, a referring physician, dermatology physician extender, or the dermatologist. Results: More than 45 percent of melanomas were an incidental finding on full skin exam. The dermatologist detected statistically thinner melanomas than melanomas that presented as the chief complaint. The dermatologist tended to detect thinner melanomas than referring physicians and patients. Conclusion: A significant portion of melanomas are incidentally found on full skin exam, and thinner melanomas are detected by dermatologists. Universal skin cancer screening takes little additional time, and appropriate use of physician extenders can greatly increase access to dermatological care. Full skin exams increase melanoma detection, decreases overall thickness at diagnosis, and decreases patient morbidity and mortality.Melanoma is the most deadly type of skin cancer with limited treatment for deep tumors. The average age adjusted melanoma death was 2.73 per 100,000 in the United States between 2006 and 2010.1 Thus, early detection of melanoma offers the best hope for a cure. Cutaneous melanoma presents a unique opportunity for intervention compared to other malignancies, as screening is simple, noninvasive, and takes little time. Clinical full skin exams have been shown to decrease the number of deep melanomas,2 which is important because the depth of invasion for malignant melanoma is the most important prognostic factor. However, even with the availability of such an easy screening test, the guidelines of when and whom to screen are unclear.3 The effect of screening on patient mortality has not been studied in a randomized trial, and formal guidelines are lacking. Previous studies have attempted to determine who detects melanomas and how they present in their clinics.2,4–6 Several of these studies were performed in areas of higher incidence of melanoma, such as Australia2 and Florida.6 The aim of this study is to report the percentage of the authors’ patients incidentally found to have melanoma as part of a full skin exam and to compare the depth of invasion with patients whose melanoma was related to their chief complaint. The authors compare their data from a private practice near Syracuse, New York, which has a relatively low incidence of melanoma in the United States,1 to some of the previously reported studies and make recommendations for future screening.     

Actinic Keratosis: Update on Field Therapy

Actinic keratosis is widely considered a field disease that is rarely limited to a single clinically apparent lesion. Field-directed therapies, such as ingenol mebutate, imiquimod, and photodynamic therapy, aim to treat not only clinically visible lesions, but also subclinical disease that is thought to exist along the same continuum as actinic keratosis and squamous cell carcinoma. These field treatments have shown efficacy compared to placebo as well as in long-term follow-up studies when compared to lesion-directed cryotherapy alone. Field therapy in combination with lesion-directed treatment will allow the practitioner to further optimize efficacy as well as patient preference and convenience. As the incidence of nonmelanoma skin cancer continues to rise, these treatment modalities provide new options to halt the progression of actinic keratosis, and thereby reduce the incidence of nonmelanoma skin cancer and its burden on our healthcare system.Actinic keratoses (AKs) are common cutaneous lesions associated with chronic exposure to ultraviolet (UV) radiation. AK presents scaly, erythematous papule or plaque and is considered the earliest clinically recognizable manifestation of squamous cell carcinoma (SCC) that is capable of transforming into squamous cell carcinoma in situ and invasive squamous cell carcinoma.1-4 Fair skin, cumulative sun exposure, immunosuppression, and age increase the risk of AK.5,6 AK is the second most common diagnosis seen by dermatologists in the United States, with the direct cost of therapy estimated at more than $1 billion per year with indirect costs nearing $300 million.7 The prevalence of AK was reported at 11 to 25 percent in 20081 with 5.2 million patient visits occurring annually for AK during the period 2000 through 2003.8Historically, AK was considered a distinct, pre-malignant lesion. In recent years, however, more evidence is accumulating that AKs are part of a continuum of disease, on a spectrum between subclinical photodamaged skin and SCC.4 Indeed, molecular analyses have revealed that AK and SCC have a similar genetic profile, including alterations in p53, pl6INK4a, MYC, and epidermal growth factor receptor.2,4,9 The risk of progression of AK to SCC (invasive or in situ) is considered to be low, but highly variable.10 The risk of developing SCC increases with the number of AKs, with a relative risk of one percent in individuals with five or fewer AKs compared to 20 percent among patients with greater than 20 lesions.1,9,11 Additionally, 60 percent of SCCs were shown to arise from prior AKs, with other estimates ranging from 25 to 80 percent.Thus, a small proportion of AKs will progress to SCC, but currently it is not possible to predict which lesions will progress and which will not. There are no distinct clinical boundaries between AK and invasive SCC, and we know that there is high inter-observer variation among experienced dermatologists.1,11,12 SCC has a metastatic risk of two to five percent to regional lymph nodes or more distant sites.13,14 It is accepted that the presence of AK is a biomarker of risk for SCC, and while histologically there is usually clear differentiation, AK must be treated to avoid possible morbidity and mortality associated with SCC.1,3     

Cutaneous Collagenous Vasculopathy

Cutaneous collagenous vasculopathy is a rare microangiopathy of dermal blood vessels. Clinically indistinguishable from generalized essential telangiectasia, this condition is diagnosed by its unique histological appearance. In contrast to other primary telangiectatic processes, cutaneous collagenous vasculopathy has dilated vascular structures that contain deposits of eosinophilic hyaline material within the vessel walls. To date, cutaneous collagenous vasculopathy has been described in a total of 19 cases in the medical literature. The first several cases were described exclusively in middle-aged to elderly men. Though it has now been described in both men and women, cutaneous collagenous vasculopathy is still most often described in middle-aged to older adults. No particular disease or medication has been linked to the development of cutaneous collagenous vasculopathy, and the etiology remains unknown. In this case series, the authors present three additional patients diagnosed with cutaneous collagenous vasculopathy and discuss their clinical and histopathologic features.Cutaneous collagenous vasculopathy (CCV) is a rare, idiopathic microangiopathy first reported in 2000 by Salama and Rosenthal.1 CCV has characteristic microscopic findings, including dilated capillaries and post-capillary venules with marked collagen deposition,2 which are features essential to diagnosis. Clinically, CCV presents as blanchable, non-urticating macules that typically begin on the lower extremities and then spread to the trunk and upper extremities. 1,3-6 Due to its clinical similarity to generalized essential telangiectasia (GET), dermatologists may not biopsy these patients, potentially causing CCV to be underdiagnosed and under-reported. 4,5,7,8 To date, CCV has been described in approximately equal numbers in men and women of Caucasian race with patients ranging from 16 to 83 years of age.4,9 The majority of cases have been diagnosed in patients with other concomitant diseases, most commonly hypertension and cardiovascular disease,3,5,6,9,10 but also in patients with autoimmune conditions2,5,8,9 and diabetes mellitus.5,10 Additionally, in most described cases, patients were taking at least one medication on an intermittent or ongoing basis. 1,2,4-7,9,1° Despite this observation, specific medical conditions or medications are yet to be linked to the development of CCV. In this article, the authors present three female patients who have been diagnosed with CCV along with their clinical and histopathological features.     

Association of 18 Confirmed Susceptibility Loci for Type 2 Diabetes With Indices of Insulin Release, Proinsulin Conversion, and Insulin Sensitivity in 5,327 Nondiabetic Finnish Men

OBJECTIVE

We investigated the effects of 18 confirmed type 2 diabetes risk single nucleotide polymorphisms (SNPs) on insulin sensitivity, insulin secretion, and conversion of proinsulin to insulin.

RESEARCH DESIGN AND METHODS

A total of 5,327 nondiabetic men (age 58 ± 7 years, BMI 27.0 ± 3.8 kg/m²) from a large population-based cohort were included. Oral glucose tolerance tests and genotyping of SNPs in or near PPARG, KCNJ11, TCF7L2, SLC30A8, HHEX, LOC387761, CDKN2B, IGF2BP2, CDKAL1, HNF1B, WFS1, JAZF1, CDC123, TSPAN8, THADA, ADAMTS9, NOTCH2, KCNQ1, and MTNR1B were performed. HNF1B rs757210 was excluded because of failure to achieve Hardy-Weinberg equilibrium.

RESULTS

Six SNPs (TCF7L2, SLC30A8, HHEX, CDKN2B, CDKAL1, and MTNR1B) were significantly (P < 6.9 × 10⁻⁴) and two SNPs (KCNJ11 and IGF2BP2) were nominally (P < 0.05) associated with early-phase insulin release (InsAUC_0–30/GluAUC_0–30), adjusted for age, BMI, and insulin sensitivity (Matsuda ISI). Combined effects of these eight SNPs reached −32% reduction in InsAUC_0–30/GluAUC_0–30 in carriers of ≥11 vs. ≤3 weighted risk alleles. Four SNPs (SLC30A8, HHEX, CDKAL1, and TCF7L2) were significantly or nominally associated with indexes of proinsulin conversion. Three SNPs (KCNJ11, HHEX, and TSPAN8) were nominally associated with Matsuda ISI (adjusted for age and BMI). The effect of HHEX on Matsuda ISI became significant after additional adjustment for InsAUC_0–30/GluAUC_0–30. Nine SNPs did not show any associations with examined traits.

CONCLUSIONS

Eight type 2 diabetes–related loci were significantly or nominally associated with impaired early-phase insulin release. Effects of SLC30A8, HHEX, CDKAL1, and TCF7L2 on insulin release could be partially explained by impaired proinsulin conversion. HHEX might influence both insulin release and insulin sensitivity.Impaired insulin secretion and insulin resistance, two main pathophysiological mechanisms leading to type 2 diabetes, have a significant genetic component (1). Recent studies have confirmed 20 genetic loci reproducibly associated with type 2 diabetes (2–13). Three were previously known (PPARG, KCNJ11, and TCF7L2), whereas 17 loci were recently discovered either by genome-wide association studies (SLC30A8, HHEX-IDE, LOC387761, CDKN2A/2B, IGF2BP2, CDKAL1, FTO, JAZF1, CDC123/CAMK1D, TSPAN8/LGR5, THADA, ADAMTS9, NOTCH2, KCNQ1, and MTNR1B), or candidate gene approach (WFS1 and HNF1B). The mechanisms by which these genes contribute to the development of type 2 diabetes are not fully understood.PPARG is the only gene from the 20 confirmed loci previously associated with insulin sensitivity (14,15). Association with impaired β-cell function has been reported for 14 loci (KCNJ11, SLC30A8, HHEX-IDE, CDKN2A/2B, IGF2BP2, CDKAL1, TCF7L2, WFS1, HNF1B, JAZF1, CDC123/CAMK1D, TSPAN8/LGR5, KCNQ1, and MTNR1B) (6,12,13,16–38). Although associations of variants in HHEX (16–22), CDKAL1 (6,21–26), TCF7L2 (22,27–30), and MTNR1B (13,31,32) with impaired insulin secretion seem to be consistent across different studies, information concerning other genes is limited (12,18–25,27,33–38). The mechanisms by which variants in these genes affect insulin secretion are unknown. However, a few recent studies suggested that variants in TCF7L2 (22,39–42), SLC30A8 (22), CDKAL1 (22), and MTNR1B (31) might influence insulin secretion by affecting the conversion of proinsulin to insulin. Variants of FTO have been shown to confer risk for type 2 diabetes through their association with obesity (7,16) and therefore were not included in this study.Large population-based studies can help to elucidate the underlying mechanisms by which single nucleotide polymorphisms (SNPs) of different risk genes predispose to type 2 diabetes. Therefore, we investigated confirmed type 2 diabetes–related loci for their associations with insulin sensitivity, insulin secretion, and conversion of proinsulin to insulin in a population-based sample of 5,327 nondiabetic Finnish men.     

Kallikrein 5-Mediated Inflammation in Rosacea: Clinically Relevant Correlations with Acute and Chronic Manifestations in Rosacea and How Individual Treatments May Provide Therapeutic Benefit

Rosacea is a chronic inflammatory condition of facial skin estimated to affect more than 16 million Americans. Although the pathogenesis of rosacea is not fully understood, recent evidence in vitro as well as in vivo has supported the role of increased levels of the trypsin-like serine protease, kallikrein 5, in initiating an augmented inflammatory response in rosacea. The increase in the quantity and magnitude of biological activity of kallikrein 5 leads to production of greater quantities of cathelicidin (LL-37), an antimicrobial peptide associated with increases in innate cutaneous inflammation, vasodilation, and vascular proliferation, all of which are characteristic features of rosacea. In this article, the authors review the literature supporting the role of kallikrein 5 in the pathophysiology of rosacea, including how therapeutic interventions modulate the effects of kallikrein 5, thus providing further support for this pathophysiological model that at least partially explains many of the clinical features of cutaneous rosacea.Cutaneous rosacea (rosacea) is a chronic inflammatory facial skin disorder noted most commonly in individuals of northern European descent, although people of any ethnicity or skin color may be affected.1-4 The visible manifestations with central facial predominance are characteristic of rosacea, including erythema, papules, pustules, telangiectasias, and phymatous changes.1-4 However, persistent (nontransient) erythema involving the central face that intensifies during flares and the presence of telangiectasias, which are also accentuated mostly on the central face, are the core clinical features that support a diagnosis of rosacea.1-9 Papules and pustules are not consistently present in rosacea, characterizing only those individuals with rosacea who exhibit the papulopustular subtype of the disease.3-6 In fact, papulopustular lesions never emerge in many individuals affected by rosacesa, and phymatous changes affect only a relatively small number of the rosacea-affected population; however, central facial erythema is present to some extent in essentially all people with rosacea.1-8Why do some people get rosacea and others do not? Although the entire explanation that would fully answer this question remains elusive, current evidence suggests that individuals affected by rosacea exhibit rosacea-prone skin, which inherently displays dysregulation of two main systems present within skin—the neurovascular/neuroimmune system and the immune detection/response system (innate immunity).3,5-8,1–9 Both of these systems normally serve physiological functions related to how skin responds to exogenous changes or insults (i.e., changes in temperature, exposure to microbial pathogens). However, in rosacea, both the cutaneous neurovascular/neuroimmune system and the immune detection/response system are dysregulated, with both demonstrating augmented responses that correlate with clinical manifestations commonly seen in patients with cutaneous rosacea.Neurovascular/neuroimmune dysregulation, which includes both anatomic and physiochemical differences present in rosacea-prone skin as compared to healthy facial skin, appears to be a major contributor that exacerbates the vasodilation of facial skin vasculature with increased facial blood flow that occurs during a rosacea flare.3,5-7,17,18,20 This increased vasodilation in rosacea-affected skin, which can be acute or subacute in onset, is commonly referred to as flushing.1,3,4,6,7,17,20 Neurosensory symptoms (i.e., stinging, burning) are often associated with or exacerbated during a rosacea flare.1,3-8 Exogenous factors that are commonly recognized by patients as triggers, which seem to induce a flare, include increased ambient heat/warmth and certain spices (i.e., capsaicin), all of which can induce signaling of neurogenic inflammation via specific receptor channels (transient receptor potential vanilloid [TRPV] subfamily) shown to be increased in rosacea-prone skin.3,6,17,18 The immune detection/response dysregulation of rosacea is evidenced by the upregulation of the pattern recognition receptor, toll-like receptor 2 (TLR2) and the cathelicidin innate immunity pathway.3,5-17,19,21,22 Ultraviolet light (UV) exposure, another recognized trigger factor associated with flares of rosacea, produces changes that induce ligand-binding of TLR2, which signals innate inflammation.3,5-16,19,21 Lastly, upregulated production of several matrix metalloproteases (MMPs) has been demonstrated in rosacea, further contributing to cascades of inflammation and degradation of the dermal matrix.1,3,5-7,19 Accentuated immune detection/response as a major component of the pathophysiology of rosacea has been discussed extensively in the literature and is addressed in more detail as a major subject of this article.5-7,10-16,19,21,22Although the pathophysiology of rosacea is not completely understood, dysregulation of the innate immune detection/response system plays a significant role in the inflammatory and vascular responses seen in this condition.5-7,10-16,19,21,22 As a known inducer of innate and cellular inflammation, increased vascularity, and angiogenesis, cathelicidin (LL-37), an antimicrobial peptide that physiologically provides near-immediate innate defense against several microbial organisms, has been investigated to determine its potential role in the pathophysiology of rosacea.10,11,23,24 Results have shown that patients with rosacea express elevated levels of LL-37 in facial skin, with this increased expression attributed to abnormally high levels of the trypsin-like serine protease enzyme, kallikrein 5 (KLK5), which selectively cleaves an inactive precursor protein (hCAP18) to form the biologically active antimicrobial peptide (LL-37).10,22 Investigations of the mechanism of action of two agents proven to be effective in reducing papulopustular lesions and perilesional erythema in rosacea, topical azelaic acid (AzA) and oral doxycycline, demonstrated direct and indirect inhibition of KLK5, respectively.25-29 In one study with AzA 15% gel, the reduction in KLK5 activity correlated with clinical improvement of rosacea.29 In this review, the authors further describe the role of KLK5 in the pathophysiology of rosacea, including the inflammatory cascades that result from increased KLK5 expression, as well as a more detailed discussion of different therapies shown to inhibit the progression of this cascade.     

Glucagon-Like Peptide 1/Glucagon Receptor Dual Agonism Reverses Obesity in Mice

OBJECTIVE

Oxyntomodulin (OXM) is a glucagon-like peptide 1 (GLP-1) receptor (GLP1R)/glucagon receptor (GCGR) dual agonist peptide that reduces body weight in obese subjects through increased energy expenditure and decreased energy intake. The metabolic effects of OXM have been attributed primarily to GLP1R agonism. We examined whether a long acting GLP1R/GCGR dual agonist peptide exerts metabolic effects in diet-induced obese mice that are distinct from those obtained with a GLP1R-selective agonist.

RESEARCH DESIGN AND METHODS

We developed a protease-resistant dual GLP1R/GCGR agonist, DualAG, and a corresponding GLP1R-selective agonist, GLPAG, matched for GLP1R agonist potency and pharmacokinetics. The metabolic effects of these two peptides with respect to weight loss, caloric reduction, glucose control, and lipid lowering, were compared upon chronic dosing in diet-induced obese (DIO) mice. Acute studies in DIO mice revealed metabolic pathways that were modulated independent of weight loss. Studies in Glp1r^−/− and Gcgr^−/− mice enabled delineation of the contribution of GLP1R versus GCGR activation to the pharmacology of DualAG.

RESULTS

Peptide DualAG exhibits superior weight loss, lipid-lowering activity, and antihyperglycemic efficacy comparable to GLPAG. Improvements in plasma metabolic parameters including insulin, leptin, and adiponectin were more pronounced upon chronic treatment with DualAG than with GLPAG. Dual receptor agonism also increased fatty acid oxidation and reduced hepatic steatosis in DIO mice. The antiobesity effects of DualAG require activation of both GLP1R and GCGR.

CONCLUSIONS

Sustained GLP1R/GCGR dual agonism reverses obesity in DIO mice and is a novel therapeutic approach to the treatment of obesity.Obesity is an important risk factor for type 2 diabetes, and ∼90% of patients with type 2 diabetes are overweight or obese (1). Among new therapies for type 2 diabetes, peptidyl mimetics of the gut-derived incretin hormone glucagon-like peptide 1 (GLP-1) stimulate insulin biosynthesis and secretion in a glucose-dependent manner (2,3) and cause modest weight loss in type 2 diabetic patients. The glucose-lowering and antiobesity effects of incretin-based therapies for type 2 diabetes have prompted evaluation of the therapeutic potential of other glucagon-family peptides, in particular oxyntomodulin (OXM). The OXM peptide is generated by post-translational processing of preproglucagon in the gut and is secreted postprandially from l-cells of the jejuno-ileum together with other preproglucagon-derived peptides including GLP-1 (4,5). In rodents, OXM reduces food intake and body weight, increases energy expenditure, and improves glucose metabolism (6–8). A 4-week clinical study in obese subjects demonstrated that repeated subcutaneous administration of OXM was well tolerated and caused significant weight loss with a concomitant reduction in food intake (9). An increase in activity-related energy expenditure was also noted in a separate study involving short-term treatment with the peptide (10).OXM activates both, the GLP-1 receptor (GLP1R) and glucagon receptor (GCGR) in vitro, albeit with 10- to 100-fold reduced potency compared with the cognate ligands GLP-1 and glucagon, respectively (11–13). It has been proposed that OXM modulates glucose and energy homeostasis solely by GLP1R agonism, because its acute metabolic effects in rodents are abolished by coadministration of the GLP1R antagonist exendin(9–39) and are not observed in Glp1r^−/− mice (7,8,14,15). Other aspects of OXM pharmacology, however, such as protective effects on murine islets and inhibition of gastric acid secretion appear to be independent of GLP1R signaling (14). In addition, pharmacological activation of GCGR by glucagon, a master regulator of fasting metabolism (16), decreases food intake in rodents and humans (17–19), suggesting a potential role for GCGR signaling in the pharmacology of OXM. Because both OXM and GLP-1 are labile in vivo (T_1/2 ∼12 min and 2–3 min, respectively) (20,21) and are substrates for the cell surface protease dipeptidyl peptidase 4 (DPP-4) (22), we developed two long-acting DPP-4–resistant OXM analogs as pharmacological agents to better investigate the differential pharmacology and therapeutic potential of dual GLP1R/GCGR agonism versus GLP1R-selective agonism. Peptide DualAG exhibits in vitro GLP1R and GCGR agonist potency comparable to that of native OXM and is conjugated to cholesterol via a Cys sidechain at the C-terminus for improved pharmacokinetics. Peptide GLPAG differs from DualAG by only one residue (Gln³→Glu) and is an equipotent GLP1R agonist, but has no significant GCGR agonist or antagonist activity in vitro. The objective of this study was to leverage the matched GLP1R agonist potencies and pharmacokinetics of peptides DualAG and GLPAG in comparing the metabolic effects and therapeutic potential of a dual GLP1R/GCGR agonist with a GLP1R-selective agonist in a mouse model of obesity.     

The Use of Noninvasive Optical Coherence Tomography to Monitor the Treatment Progress of Vismodegib and Imiquimod 5% Cream in a Transplant Patient with Advanced Basal Cell Carcinoma of the Nose

Immunosuppressed transplant recipients have increased risk for the development of basal cell carcinoma skin cancers. While oral vismodegib therapy has been successful in treating locally advanced basal cell tumors, few studies document its use and efficacy in organ transplant patients. In this immunocompromised population, topical imiquimod 5% cream has been shown to be an effective and well-tolerated option for superficial and nodular basal cell carcinomas. To the authors’ knowledge, no data documents the use of optical coherence tomography, a noninvasive imaging technique, to monitor progress of such combined therapies on in vivo skin. The authors report the successful treatment of an extensive basal cell carcinoma on the nose of an immunosuppressed 54-year-old Caucasian man with a history of kidney and pancreas transplantations. By combining continuous noninvasive lesion monitoring with vismodegib 150mg/d therapy and adjuvant imiquimod 5% topical cream, the patient showed complete disease clearance on clinical, optical coherence tomography, and histological evaluation. This report supports the feasibility and efficacy of nonsurgical treatment of basal cell lesions in complicated transplant patients and the need for individualized treatment plans. A noninvasive follow-up tool, especially during nonsurgical therapy, is of critical value to ensure the best possible treatment outcome for the patient.Basal cell carcinoma (BCC) is the most common malignancy in individuals of mixed European descent, and accounts for approximately 80 percent of all skin malignancies.1-3 The risk for developing BCC is greatly increased in organ transplant recipients who use a combination of immunosuppressive drug therapies for prolonged periods of time.4-6 BCC is the second most frequent skin cancer assoiated with immunosuppression and more commonly metastasizes in this population than patients who have human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) or iatrogenic images of tissue micro-architecture down to a depth of immunodeficiency.4,6,7 The management of extensive BCC in immunosuppressed organ transplant recipients can be a challenge for dermatologists.The current gold standard of diagnosis and management of extensive and infiltrative BCC is clinical and histopathological evaluation followed by surgical excision.3. Such invasive procedures often lead to poor cosmetic outcomes and/or functional impairment8 and there has been increased focus on alternative nonsurgical diagnostic, follow-up and treatment modalities for these patients.Optical coherence tomography (OCT), a noninvasive maging technique, allows for real-time detection and assessment of skin lesions. OCT uses near-infrared light to generate high-resolution black and white cross-sectional 2mm.9-12 These images depict cellular components in the same plane as traditional histological cuts, and studies have established that they are sufficiently detailed for identification of morphological criteria for BCC and other nonmelanoma skin cancers (NMSC).8,9,11,13,15 The OCT diagnostic sensitivity and specificity for NMSC varies by study, but ranges from 79 to 94 percent and 85 to 96 percent, respectively, whereas the clinical diagnostic sensitivity and specificity for NMSC ranges from 56 to 90 percent and 75 to 90 percent, respectively.12,14,15 Regardless of the reported sensitivities and specificities, these studies have all shown OCT to improve diagnostic accuracy. More recently, the diagnostic value of OCT, specifically for BCC, was demonstrated in a population of clinically challenging lesions.15 OCT improved diagnostic certainty by a factor of four over clinical examination alone, and improved diagnostic accuracy by 50 percent.15 With OCT imaging, 48 percent more BCCs were detected than by clinical examination alone, and sensitivity in this population increased from 62.9 to 92.9 percent.15 As such, OCT offers a powerful diagnostic tool for NMSC and can be used to monitor lesion treatment progress.12Nonsurgical treatment options for locally advanced or metastatic BCCs include vismodegib (Erivedge, Genentech-Curis), the first and only available oral hedgehog pathway inhibitor drug.2,16-18 While this novel treatment is efficacious in treating metastasized, recurrent, and inoperable BCCs, adverse side effects such as nausea, vomiting, muscle cramps, decreased appetite, weight loss, and alopecia can preclude long-term use.16,18 Furthermore, efficacy of vismodegib treatment has not been determined in organ transplant recipients. More established topical field treatments, such as imiquimod 5% cream (Aldara, 3M Pharmaceuticals), have been shown to be effective treatments for superficial and nodular BCCs in the immunosuppressed population.20Herein, the authors present an immunocompromised transplant recipient monitored noninvasively with OCT imaging to assess tissue morphology throughout nonsurgical combination therapy with oral vismodegib and imiquimod cream. To their knowledge, there is limited literature on the use of vismodegib in transplant patients, and this is the first reported case of its combination with imiquimod cream for advanced BCC in an immunosuppressed transplant patient that shows complete lesion clearance.     

Successful Treatment of Extensive Vitiligo with Monobenzone

Vitiligo is one of the most common dermatological disorders, appearing as one or more white macules or patches and affecting up to two percent of the population worldwide. The undesirable aesthetic properties of vitiligo, especially facial, may result in significant negative psychosocial effects, particularly a rate of depression twice that of the general population. While there is no cure, there are several treatment options, notably depigmentation in severe cases. Monobenzone is the most potent depigmenting agent. However, its use is limited due to the permanent and potent nature of the drug. This case presents an example of when timely and aggressive treatment with monobenzone is warranted, demonstrating excellent clinical response, which resulted in a significant increase in the quality of life in a patient with severe vitiligo.Vitiligo is among one of the most common dermatological disorders, affecting up to two percent of the population worldwide.1,2 A chronic and usually progressive disorder, vitiligo presents discretely before 20 years of age, although first presentation in later life may occur as well.2 Clinically, it appears as one or more well-circumscribed, hypopigmented, white macules or patches. This is due to the acquired autoimmune destruction of melanocytes, most often in areas of greater pigmentation, such as the face and dorsum of the hands where they are most exposed to UV radiation.2 Apart from the cosmetic appearance, it is usually asymptomatic, although there is a greater tendency for sunburns and pruritis.2The undesirable aesthetic properties of vitiligo, especially facial, may result in significant negative psychosocial effects, notably a rate of depression twice that of the general population.3 In some cultures, vitiligo is not well understood. The depigmentation of vitiligo is thought to result from sexually transmitted infections, or of leprosy, and can have a damaging effect on educational, social, and employment opportunities.1,2,4 Patients may feel embarrassed or ashamed of such a visible disorder. Studies have shown that vitiligo is associated with a greater burden of disease to patients, especially those in populations with dark skin.1,2,4 Therefore, treatment, although not medically necessary, provides large psychosocial gains for the patient, increasing their quality of life.There is no cure for vitiligo. Current treatment for vitiligo attempts to either increase or decrease pigmentation in order to achieve cosmetically pleasing results and increase the patient''s self-esteem.5 Repigmentation tends to require a prolonged treatment course and yield minimal positive results.6 Strong topical steroids are generally the first line of treatment, with only a 50- to 75-percent repigmentation rate.5,6 Tactrolimus, an immunosuppressive, and calcipotriene, a vitamin D analogue, are alternative topical repigmenting agents, with a similar efficacy as the topical steroids.6 When such treatment fails, psoralen plus ultraviolet A radiation (PUVA) and narrow-band ultraviolet B radiation (NB-UVB) are effective alternatives.5,6 However, PUVA can be carcinogenic and NB-UVB has low efficacy; both require prolonged treatments.6,7 Alternative treatments exist, such as melanocyte transplantations. However, despite the type of treatment, repigmentation still remains difficult and time consuming, especially with advanced vitiligo.Due to the difficulties with repigmentation, it is often easier to achieve depigmentation, especially when vitiligo affects more than 50 percent of the body.5–7 It is, however, a more aggressive approach and its use is considered on an individual basis because of the irreversible changes and increased sensitivity to sunburn of the treated areas. Several treatment modalities exist. Phenols, lasers, cryotherapy, and depigmenting systemic agents, such as imatinib, imiquimod, and diphencyprone, are often considered.7 Monobenzone (monobenzyl ether of hydroquinone, MBEH) is usually the treatment of choice of depigmentation therapy for severe cases of vitiligo, and MBEH is usually used in concentrations of 20 to 40 percent to achieve the desired permanent depigmentation.5,7 It achieves its effects by inducing the necrotic death of melanocytes.7 Topical all-trans-retinoic acid (RA), a vitamin A derivative, causes mild depigmentation and when used in combination with MBEH, has synergistic effects, yielding depigmentation in a short amount of time.7 Nair et al8 have proposed that the RA enhances the absorption of monobenzone by melanocytes through the inactivation of their glutathione-dependent defense mechanisms.7,8 Side effects of MBEH include skin irritation, contact dermatitis, ocular side effects, exogenous ochronosis, and difficulties in predicting response.5,9–11 There can be repigmentation because of sun exposure or rarely as a reaction to the drug.5,7,10,11 Due to these side effects, MBEH treatment can be somewhat controversial, and its use has been limited in some countries, such as the Netherlands, which has restricted it since 1990.7 MBEH has been approved by the United States Food and Drug Administration since 1952 for permanent depigmentation of extensive vitiligo.     

In-office Painless Aminolevulinic Acid Photodynamic Therapy: A Proof of Concept Study and Clinical Experience in More Than 100 Patients

Objective: To evaluate the efficacy, safety, and pain of in-office “painless” aminolevulinic acid photodynamic therapy aimed at decreasing treatment-associated pain in patients undergoing removal of actinic keratoses. Design: Prospective split-face study comparing short aminolevulinic acid incubation times of 15 minutes followed by extended exposure (60 minutes) of continuous blue light versus conventional aminolevulinic acid photodynamic therapy. Prospective assessment of pain in patients undergoing in-office “painless” aminolevulinic acid photodynamic therapy. Setting: Clinical practice office. Participants: Three patients with actinic keratoses participated in the split-face study and 101 in the pain assessment study. Measurements: Evaluations in the split-face study included removal of actinic keratoses, skin temperature, and pain measured on a 10-point visual analog scale. Pain was assessed using the visual analog scale in the pain assessment study. Results: In the split-face study, in-office “painless” aminolevulinic acid photodynamic therapy resulted in a 52-percent reduction in lesions versus 44 percent for conventional aminolevulinic acid photodynamic therapy. Maximum pain scores of in-office “painless” aminolevulinic acid photodynamic therapy were all 0 at each time point, and the average score for conventional aminolevulinic acid photodynamic therapy was 7. Baseline skin temperatures increased from a baseline of 29 to 32°C to 34 to 35°C by minute 10 of blue light activation on both sides of the face. Results from the pain assessment study indicated no or minimal (scores 0-2) pain in nearly all patients who received in-office “painless” aminolevulinic acid photodynamic therapy as monotherapy or in combination with 5-fluoruacil or imiquimod used as pretreatments. Conclusions: In-office “painless” aminolevulinic acid photodynamic therapy appears to be effective for removing actinic keratoses and is associated with little or no pain in nearly all patients. This procedure should be evaluated in large-scale controlled trials.Actinic keratoses (AKs) are part of the spectrum between photodamaged skin and invasive squamous cell carcinoma (SCC).1-5 They are a major health care concern because of their increasing prevalence worldwide,6-10 economic impact,9-11 and decreased quality of life of affected individuals.10,12 Results from observational studies have indicated that AKs evolve into primary invasive SCC or in situ SCC at a rate ranging between 1/1,000 lesions per year13 to 0.60 percent at one year and 2.57 percent at four years.14 It is recommended that all AKs be treated because it is not currently possible to predict which will evolve into invasive SCC.15-17A variety of therapeutic modalities are used to treat AKs.1,18-20 Focally destructive therapies, such as cryotherapy,21 electrodessication and curettage,22 and shave excision23 are most often used to treat individual AKs. Large areas of actinically damaged skin require “field therapies” such as 5-fluoruacil (5-FU),24-26 imiquimod,26-30 diclofenac gel,31-33 ingenol mebutate,34,36 aminolevulinic acid photodynamic therapy (ALA PDT)35,37 and methyl-aminolevulinic acid PDT (MAL PDT),38,39 chemical peels,40 dermabrasion,41-43 and laser resurfacing.44,45PDT produces reactive oxygen species that result in tissue destruction46 and it destroys AKs because of the preferential accumulation of the photosensitizing molecule, protoporphyrin IX (PpIX) within AKs following topical application of pro-drugs ALA47 and MAL.48 PDT is safe and effective for treatment of large surface skin areas, provides good adherence because it is performed under supervision in a clinic setting, has minimal post-treatment downtime versus other AK field therapies, and produces good-to-excellent cosmetic outcomes with minimal potential for scarring.49,50 PDT also has several drawbacks, most notably pain during the first few minutes of light activation phase.51-53 Nearly two-thirds of patients undergoing ALA PDT report this pain as “moderate-severe” following 1, 2, or 3-hour ALA incubations.54 Pain with PDT has been related to cellular destruction and inflammation and possibly a direct effect of PDT on nerve fibers55-57; it has now become clear that PDT-related pain is associated with PpIX tissue accumulation based on fluorescence and the fluence rate of the activating light source.58 Topical anesthetics,55 cooling devices,59-61 nerve blockade,61,62 and treatment interruption63 have limited efficacy in managing PDT-related pain, which can lead to reluctance of patients to undergo future PDT treatments.A novel approach to minimizing discomfort during PDT, daylight-mediated PDT, uses a brief (30-minute) incubation period followed by 1.5 to 2.5 hours of daylight exposure.64-66 The shortened incubation period is designed to minimize PpIX build-up in the targeted tissue prior to daylight PpIX activation, and photobleaching prevents further buildup of PpIX and minimizes patient discomfort.67,68 Limitations to daylight-mediated PDT include dependence on favorable weather conditions and patient adherence to the treatment protocol outside the clinic.65Based on the efficacy and improved tolerability of daylight-mediated PDT, an in-office painless (IOP) ALA PDT protocol was developed. It involves applying ALA topically to actinically damaged skin, incubating without occlusion for 15 minutes, and then 60 minutes of continuous blue light activation. This report summarizes results from a split-face comparison of IOP ALA PDT and a standard short (75 minute) ALA incubation protocol followed by the standard 1,000 seconds of blue light activation carried out in three patients, and assessment of pain associated with this treatment in 101 patients undergoing 121 treatments over a two-year time period. In the latter study, IOP ALA PDT was employed as either a full-face monotherapy or in combination with one week of prior treatment with 5% and 0.5% 5-FU and 3.75% and 5% imiquimod.     

C-Peptide Activates AMPKα and Prevents ROS-Mediated Mitochondrial Fission and Endothelial Apoptosis in Diabetes

Vasculopathy is a major complication of diabetes; however, molecular mechanisms mediating the development of vasculopathy and potential strategies for prevention have not been identified. We have previously reported that C-peptide prevents diabetic vasculopathy by inhibiting reactive oxygen species (ROS)-mediated endothelial apoptosis. To gain further insight into ROS-dependent mechanism of diabetic vasculopathy and its prevention, we studied high glucose–induced cytosolic and mitochondrial ROS production and its effect on altered mitochondrial dynamics and apoptosis. For the therapeutic strategy, we investigated the vasoprotective mechanism of C-peptide against hyperglycemia-induced endothelial damage through the AMP-activated protein kinase α (AMPKα) pathway using human umbilical vein endothelial cells and aorta of diabetic mice. High glucose (33 mmol/L) increased intracellular ROS through a mechanism involving interregulation between cytosolic and mitochondrial ROS generation. C-peptide (1 nmol/L) activation of AMPKα inhibited high glucose–induced ROS generation, mitochondrial fission, mitochondrial membrane potential collapse, and endothelial cell apoptosis. Additionally, the AMPK activator 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside and the antihyperglycemic drug metformin mimicked protective effects of C-peptide. C-peptide replacement therapy normalized hyperglycemia-induced AMPKα dephosphorylation, ROS generation, and mitochondrial disorganization in aorta of diabetic mice. These findings highlight a novel mechanism by which C-peptide activates AMPKα and protects against hyperglycemia-induced vasculopathy.C-peptide and insulin are cosecreted in equimolar amounts into the circulation from the pancreatic β-cells of Langerhans (1). C-peptide deficiency is a prominent attribute of type 1 diabetes (1). Deficiencies of C-peptide and insulin may also occur in the late stages of type 2 diabetes as a result of progressive loss of β-cells (2–4). Recent evidence demonstrates a beneficial role for C-peptide in diabetic neuropathy (1,5,6), nephropathy (1,6,7), and vascular dysfunction (1,5) and inflammation (1). C-peptide protects against diabetic vascular damage by promoting nitric oxide (NO) release (8) and suppressing nuclear factor-κB (9), which suppresses leukocyte-endothelium interactions (8,9). C-peptide may prevent atherosclerosis by inhibiting vascular smooth muscle proliferation and migration (10) and reducing venous neointima formation (11). However, the molecular mechanism by which C-peptide prevents diabetes complications is not understood well enough to permit its clinical implementation.Generation of reactive oxygen species (ROS) in response to high glucose is the leading cause of endothelial damage and diabetic vasculopathy (12). Protein kinase C (PKC)-dependent NADPH oxidase is considered a major cytosolic mediator of ROS generation in endothelial cells (13,14) that play a central role in hyperglycemia-induced endothelial cell apoptosis and vascular complications (15–17). Overproduction of intracellular ROS by mitochondria also occurs during the development of hyperglycemia-induced vascular complications (12,18,19). Altered mitochondrial dynamics due to mitochondrial fission were recently linked with endothelial dysfunction in diabetes (20,21). However, the mechanisms regulating production of cytosolic and mitochondrial ROS and their individual functions in regulating mitochondrial dynamics and apoptosis remain to be elucidated.AMP-activated protein kinase (AMPK) is an intracellular energy and stress sensor (22) and is an emerging target for preventing diabetes complications (23), as exhibited by the most common antihyperglycemic drugs, rosiglitazone (24) and metformin (25). AMPK prevents apoptosis of endothelial cells (26–28) by inhibiting ROS generation by NADPH oxidase (24,29) and mitochondria (30). Additionally, AMPK dephosphorylation is associated with diabetes (22,31,32). It has been reported that C-peptide inhibits high glucose–induced mitochondrial superoxide generation in renal microvascular endothelial cells (7). We recently demonstrated a key role for C-peptide in preventing high glucose–induced ROS generation and apoptosis of endothelial cells through inhibition of transglutaminase (17). However, the mechanism underlying C-peptide–mediated inhibition of intracellular ROS production and subsequent apoptosis remains unclear. Thus, we hypothesized that the potential protective role of C-peptide could be attributed to activation of AMPK, which results in reduced hyperglycemia-induced production of intracellular ROS and altered mitochondrial dynamics that suppress apoptosis of endothelial cells.In this study, we sought to elucidate the mechanism by which C-peptide protects against hyperglycemia-induced ROS production and subsequent endothelial cell damage. We examined the beneficial effect of C-peptide through AMPKα activation and subsequent protection against hyperglycemia-induced production of intracellular ROS, dysregulation of mitochondrial dynamics, mitochondrial membrane potential (∆Ψ_m) collapse, and apoptosis of endothelial cells. These studies were confirmed in vivo in mice with streptozotocin-induced diabetes using C-peptide supplement therapy delivered through osmotic pumps. Thus, our study implicates C-peptide replacement therapy as a potentially significant approach for preventing diabetes complications.     

The C3a Anaphylatoxin Receptor Is a Key Mediator of Insulin Resistance and Functions by Modulating Adipose Tissue Macrophage Infiltration and Activation

OBJECTIVE

Significant new data suggest that metabolic disorders such as diabetes, obesity, and atherosclerosis all posses an important inflammatory component. Infiltrating macrophages contribute to both tissue-specific and systemic inflammation, which promotes insulin resistance. The complement cascade is involved in the inflammatory cascade initiated by the innate and adaptive immune response. A mouse genomic F2 cross biology was performed and identified several causal genes linked to type 2 diabetes, including the complement pathway.

RESEARCH DESIGN AND METHODS

We therefore sought to investigate the effect of a C3a receptor (C3aR) deletion on insulin resistance, obesity, and macrophage function utilizing both the normal-diet (ND) and a diet-induced obesity mouse model.

RESULTS

We demonstrate that high C3aR expression is found in white adipose tissue and increases upon high-fat diet (HFD) feeding. Both adipocytes and macrophages within the white adipose tissue express significant amounts of C3aR. C3aR^−/− mice on HFD are transiently resistant to diet-induced obesity during an 8-week period. Metabolic profiling suggests that they are also protected from HFD-induced insulin resistance and liver steatosis. C3aR^−/− mice had improved insulin sensitivity on both ND and HFD as seen by an insulin tolerance test and an oral glucose tolerance test. Adipose tissue analysis revealed a striking decrease in macrophage infiltration with a concomitant reduction in both tissue and plasma proinflammatory cytokine production. Furthermore, C3aR^−/− macrophages polarized to the M1 phenotype showed a considerable decrease in proinflammatory mediators.

CONCLUSIONS

Overall, our results suggest that the C3aR in macrophages, and potentially adipocytes, plays an important role in adipose tissue homeostasis and insulin resistance.The complement system is an integral part of both the innate and adaptive immune response involved in the defense against invading pathogens (1). Complement activation culminates in a massive amplification of the immune response leading to increased cell lysis, phagocytosis, and inflammation (1). C3 is the most abundant component of the complement cascade and the convergent point of all three major complement activation pathways. C3 is cleaved into C3a and C3b by the classical and lectin pathways, and iC3b is generated by the alternative pathway (2,3). C3a has potent anaphylatoxin activity, directly triggering degranulation of mast cells, inflammation, chemotaxis, activation of leukocytes, as well as increasing vascular permeability and smooth muscle contraction (3). C3a mediates its downstream signaling effects by binding to the C3a receptor (C3aR), a Gi-coupled G protein–coupled receptor. Several studies have demonstrated a role for C3a and C3aR in asthma, sepsis, liver regeneration, and autoimmune encephalomyelitis (1,3). Therefore, targeting C3aR may be an attractive therapeutic option for the treatment of several inflammatory diseases.Increasing literature suggests that metabolic disorders such as diabetes, obesity, and atherosclerosis also possess an important inflammatory component (4–7). Several seminal reports have demonstrated that resident macrophages can constitute as much as 40% of the cell population of adipose tissue (7–9) and can significantly affect insulin resistance (10–18). Several proinflammatory cytokines, growth factors, acute-phase proteins, and hormones are produced by the adipose tissue and implicated in insulin resistance and vascular homeostasis (4–7,19). An integrated genomics approach was performed with several mouse strains to infer causal relationships between gene expression and complex genetic diseases such as obesity/diabetes. This approach identified the C3aR gene as being causal for omental fat pad mass (20). The C3aR^−/− mice were shown to have decreased adiposity as compared with wild-type mice on a regular diet (20). Monocytes and macrophages express the C3aR (21–28). Increased C3a levels also correlate with obesity, diabetes, cholesterol, and lipid levels (29–34). We therefore sought to investigate the specific role of the C3aR in insulin resistance, obesity, and macrophage function utilizing both normal diet and the diet-induced obesity model.     

Autoimmune Polyendocrinopathy-Candidiasis-Ectodermal Dystrophy

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy is a rare autoimmune disorder. The clinical spectrum of symptoms is diverse; the diagnosis relying on the presence of at least two out of the three main conditions defining the syndrome: chronic mucocutaneous candidiasis, hypoparathyroidism, and Addison''s disease.Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), also called autoimmune polyendocrine syndrome type I (APS-1), is a rare organ-specific autosomal recessive disease (OMIM 240300).1–3 Although APECED may occur worldwide, it remains most common in Iranian Jews (1:9,000),4 Sardinians (1:14,500),5–12 Finns (1:25,000),13 Slovenians (1:43,000),14 Norwegians (1:80,000),15 Polish (1:1,29,000),16 and Japanese (1:10,000,000).17 Multiple organ failures in APECED are caused by a progressive loss of tolerance against self-antigens resulting in an immunological attack and secondary destruction of the adrenals, parathyroid glands, β cells of islet of Langerhans,18 stomach, and small intestine.13 Many of the auto-antigens have been identified and characterized.9,12,19     

Identification of Body Fat Mass as a Major Determinant of Metabolic Rate in Mice

OBJECTIVE

Analysis of energy expenditure (EE) in mice is essential to obesity research. Since EE varies with body mass, comparisons between lean and obese mice are confounded unless EE is normalized to account for body mass differences. We 1) assessed the validity of ratio-based EE normalization involving division of EE by either total body mass (TBM) or lean body mass (LBM), 2) compared the independent contributions of LBM and fat mass (FM) to EE, and 3) investigated whether leptin contributes to the link between FM and EE.

RESEARCH DESIGN AND METHODS

We used regression modeling of calorimetry and body composition data in 137 mice to estimate the independent contributions of LBM and FM to EE. Subcutaneous administration of leptin or vehicle to 28 obese ob/ob mice and 32 fasting wild-type mice was used to determine if FM affects EE via a leptin-dependent mechanism.

RESULTS

Division of EE by either TBM or LBM is confounded by body mass variation. The contribution of FM to EE is comparable to that of LBM in normal mice (expressed per gram of tissue) but is absent in leptin-deficient ob/ob mice. When leptin is administered at physiological doses, the plasma leptin concentration supplants FM as an independent determinant of EE in both ob/ob mice and normal mice rendered leptin-deficient by fasting.

CONCLUSIONS

The contribution of FM to EE is substantially greater than predicted from the metabolic cost of adipose tissue per se, and the mechanism underlying this effect is leptin dependent. Regression-based approaches that account for variation in both FM and LBM are recommended for normalization of EE in mice.The maintenance of stable body weight is achieved through a process termed “energy homeostasis” that matches energy intake to energy expenditure (EE) over long time intervals (1). Accordingly, when animals experience a sustained increase of energy intake (e.g., during consumption of an energy-rich highly palatable diet), an adaptive increase of metabolic rate can help to limit the associated weight gain (2). However, the ability to quantify adaptive changes of EE is confounded in that larger animals tend to have a higher metabolic rate than smaller ones. Therefore, to reliably detect changes in EE that are not due simply to differences in body size per se, EE must be normalized to body mass using a method that eliminates this confounding effect. To date, most rodent studies of obesity use ratio-based normalization methods whereby EE is divided by either total body mass (TBM) or lean body mass (LBM) (3–6). However, these two methods can give widely divergent results when applied to the same data (3,4,6,7).A recent Diabetes Perspectives article (7) cogently reviewed the confounding effect of normalizing EE via division by TBM in mice, particularly when groups being compared differ in fat mass (FM). Accompanying this caution was the recommendation that EE be normalized via division by LBM instead (7) on grounds that FM consumes much less energy than LBM. Despite its intuitive appeal, dividing EE by LBM is theoretically problematic as a means to remove the influence of body size variation from group comparisons. The linear relationship between EE and either TBM or LBM is typically characterized by a positive y (EE) intercept term (8–13) due to heterogeneity inherent in the EE of various tissues comprising LBM (14). Consequently, dividing resting or average EE by either TBM or LBM mathematically forces heavier individuals to have a lower normalized EE than smaller ones (8–13), a concept first articulated >60 years ago (8). One approach that has been forwarded to obviate this mathematical bias is to use allometric scaling (15) wherein a TBM scaling exponent b and scaling coefficient a must be identified based on the data (15,16) such that EE divided by TBM^b assumes the constant expected value a. This approach, however, is limited by interpretational and other difficulties (17), and the notion that a predetermined fixed TBM scaling exponent can be applied universally has been challenged (16,18).Normalizing EE in human studies is now accomplished using multiple regression methods that adjust group comparisons of EE for differences in body mass so as to eliminate the influence of body size variation per se from evaluations of key independent variables such as ethnicity, sex, genotype, or nutritional status (9,19–28). Although multiple regression has been used in animal studies (11,29–35), the relative importance of FM and LBM as determinants of metabolic rate in mice remains an open question. Indeed, both human and animal investigations suggest that the energy cost of FM in vivo is greater than expected on the basis of its intrinsic metabolic rate (20,28,31,36). This possibility is consistent with evidence that changes in FM can influence metabolic rate at least in part through homeostatic adjustments of EE that promote body weight stability (2,37–42). Testing this hypothesis, however, requires the application of valid strategies for normalizing EE to body size.In the current work, we demonstrate in a large sample of mice that ratio-based normalization of EE is problematic, even when LBM is used in lieu of TBM. Moreover, multiple regression analysis indicates that variation in FM makes a surprisingly large contribution to EE. These findings lead us to support recommendations for the broad use of regression-based approaches to normalizing EE in mice that take both FM and LBM into account (9–12,19,43,44). Based on the hypothesis that the effect of FM on EE reflects adaptive responses involving the adipocyte hormone leptin, we asked 1) whether the effect of FM on EE is absent in ob/ob mice that lack a leptin signal, 2) if the plasma leptin level supplants FM as an independent determinant of EE when leptin is administered to ob/ob mice at physiological doses, and 3) whether in wild-type (WT) mice rendered leptin-deficient by fasting, the plasma leptin level emerges as a determinant of EE when physiological replacement is achieved by exogenous leptin administration. Our results confirm each of these predictions and therefore implicate circulating leptin in the mechanism whereby FM variation affects EE.     

SH2B1 Enhances Insulin Sensitivity by Both Stimulating the Insulin Receptor and Inhibiting Tyrosine Dephosphorylation of Insulin Receptor Substrate Proteins

OBJECTIVE

SH2B1 is a SH2 domain-containing adaptor protein expressed in both the central nervous system and peripheral tissues. Neuronal SH2B1 controls body weight; however, the functions of peripheral SH2B1 remain unknown. Here, we studied peripheral SH2B1 regulation of insulin sensitivity and glucose metabolism.

RESEARCH DESIGN AND METHODS

We generated TgKO mice expressing SH2B1 in the brain but not peripheral tissues. Various metabolic parameters and insulin signaling were examined in TgKO mice fed a high-fat diet (HFD). The effect of SH2B1 on the insulin receptor catalytic activity and insulin receptor substrate (IRS)-1/IRS-2 dephosphorylation was examined using in vitro kinase assays and in vitro dephosphorylation assays, respectively. SH2B1 was coexpressed with PTP1B, and insulin receptor–mediated phosphorylation of IRS-1 was examined.

RESULTS

Deletion of peripheral SH2B1 markedly exacerbated HFD-induced hyperglycemia, hyperinsulinemia, and glucose intolerance in TgKO mice. Insulin signaling was dramatically impaired in muscle, liver, and adipose tissue in TgKO mice. Deletion of SH2B1 impaired insulin signaling in primary hepatocytes, whereas SH2B1 overexpression stimulated insulin receptor autophosphorylation and tyrosine phosphorylation of IRSs. Purified SH2B1 stimulated insulin receptor catalytic activity in vitro. The SH2 domain of SH2B1 was both required and sufficient to promote insulin receptor activation. Insulin stimulated the binding of SH2B1 to IRS-1 or IRS-2. This physical interaction inhibited tyrosine dephosphorylation of IRS-1 or IRS-2 and increased the ability of IRS proteins to activate the phosphatidylinositol 3-kinase pathway.

CONCLUSIONS

SH2B1 is an endogenous insulin sensitizer. It directly binds to insulin receptors, IRS-1 and IRS-2, and enhances insulin sensitivity by promoting insulin receptor catalytic activity and by inhibiting tyrosine dephosphorylation of IRS proteins.Insulin decreases blood glucose both by promoting glucose uptake into skeletal muscle and adipose tissue and by suppressing hepatic glucose production. In type 2 diabetes, the ability of insulin to reduce blood glucose is impaired (insulin resistance) because of a combination of genetic and environmental factors, resulting in hyperglycemia. Insulin resistance is not only the hallmark but also a determinant of type 2 diabetes.Insulin binds to and activates the insulin receptor. Insulin receptor tyrosyl phosphorylates insulin receptor substrates (IRS-1, -2, -3, and -4). IRS proteins, particularly IRS-1 and IRS-2, initiate and coordinate multiple downstream pathways, including the phosphatidylinositol 3-kinase/Akt pathway (1). Genetic deletion of IRS-1, IRS-2, or Akt2 causes insulin resistance in mice, indicating that the IRS protein/phosphatidylinositol 3-kinase/Akt2 pathway is required for regulation of glucose homeostasis by insulin (2–5). Insulin receptor and IRS proteins are negatively regulated by various intracellular molecules, including PTP1B, Grb10, Grb14, SOCS1, SOCS3, JNK, PKCθ, S6K, and IKKβ (6–23). The relative contribution of these negative regulators to the progression of insulin resistance has been extensively studied (6–24). However, insulin signaling is likely to also be modulated by positive regulators. In this study, we demonstrate that SH2B1 is a novel endogenous insulin sensitizer.SH2B1 is a member of the SH2B family of adapter proteins that also includes SH2B2 (APS) and SH2B3 (Lnk). SH2B1 and SH2B2 are expressed in multiple tissues, including insulin target tissues (e.g., skeletal muscle, adipose tissue, liver, and the brain); by contrast, SH2B3 expression is restricted to hematopoietic tissue (25,26). Structurally, SH2B family members have an NH₂-terminal dimerization domain, a central pleckstrin homology domain, and a COOH-terminal Src homology 2 (SH2) domain. The dimerization domain mediates homodimerization or heterodimerization between different SH2B proteins (27). SH2B1 and SH2B2 bind via their SH2 domains to a variety of tyrosine phosphorylated proteins, including JAK2 and insulin receptor, in cultured cells (28). Genetic deletion of SH2B1 results in marked leptin resistance, obesity, insulin resistance, and type 2 diabetes in mice, demonstrating that SH2B1 is required for the maintenance of normal body weight, insulin sensitivity, and glucose metabolism (29–32). Surprisingly, SH2B2-null mice have normal body weight and slightly improved insulin sensitivity (32,33), suggesting that SH2B1 and SH2B2 have distinct functions in vivo. However, it remains unclear whether SH2B1 cell autonomously regulates insulin sensitivity in peripheral insulin target tissues because systemic deletion of SH2B1 causes obesity, which may cause insulin resistance in SH2B1-null mice.We generated a mouse model in which recombinant SH2B1 is specifically expressed in the brain of SH2B1-null mice (TgKO) using transgenic approaches (31). Neuron-specific restoration of SH2B1 corrects both leptin resistance and obesity, suggesting that neuronal SH2B1 regulates energy balance and body weight by enhancing leptin sensitivity (31). Consistent with these conclusions, polymorphisms in the SH2B1 loci are linked to leptin resistance and obesity in humans (34–36). In this work, we demonstrate that deletion of SH2B1 in peripheral tissues impairs insulin sensitivity independent of obesity in TgKO mice. Moreover, we demonstrate that SH2B1 directly promotes insulin responses by stimulating insulin receptor catalytic activity and by protecting IRS proteins from tyrosine dephosphorylation.     

Renal Dendritic Cells Ameliorate Nephrotoxic Acute Kidney Injury

Inflammation contributes to the pathogenesis of acute kidney injury. Dendritic cells (DCs) are immune sentinels with the ability to induce immunity or tolerance, but whether they mediate acute kidney injury is unknown. Here, we studied the distribution of DCs within the kidney and the role of DCs in cisplatin-induced acute kidney injury using a mouse model in which DCs express both green fluorescence protein and the diphtheria toxin receptor. DCs were present throughout the tubulointerstitium but not in glomeruli. We used diphtheria toxin to deplete DCs to study their functional significance in cisplatin nephrotoxicity. Mice depleted of DCs before or coincident with cisplatin treatment but not at later stages experienced more severe renal dysfunction, tubular injury, neutrophil infiltration and greater mortality than nondepleted mice. We used bone marrow chimeric mice to confirm that the depletion of CD11c-expressing hematopoietic cells was responsible for the enhanced renal injury. Finally, mixed bone marrow chimeras demonstrated that the worsening of cisplatin nephrotoxicity in DC-depleted mice was not a result of the dying or dead DCs themselves. After cisplatin treatment, expression of MHC class II decreased and expression of inducible co-stimulator ligand increased on renal DCs. These data demonstrate that resident DCs reduce cisplatin nephrotoxicity and its associated inflammation.Innate immune responses are pathogenic in both ischemic and toxic acute renal failure. In response to renal injury, inflammatory chemokines and cytokines are produced both by renal parenchymal cells, such as proximal tubule epithelial cells, and resident or infiltrating leukocytes.^1–4 The elaborated chemokines and cytokines, including TNF-α, IL-18, keratinocyte-derived chemokine, and monocyte chemoattractant protein 1, subsequently recruit additional immune cells to the kidney, such as neutrophils, T cells, monocytes, and inflammatory dendritic cells (DCs), which may cause further injury through pathways that are not fully defined.^2,5–12 DCs are sentinels of the immune system and under steady-state conditions induce tolerance by various mechanisms, including production of TGF-β, IL-10, or indoleamine 2,3-dioxygenase^13–16; expression of PDL-1, PDL-2, or FcγR2B^17,18; clonal deletion of autoreactive T cells¹⁹; and induction of T regulatory cells via the inducible co-stimulator (ICOS) pathway.^20–23 In response to pathogens or products of tissue injury, DCs mature and initiate immunity or inflammatory diseases.^24,25 Monocytes recruited to inflamed tissue can also differentiate into inflammatory DCs and mediate defense against pathogens or contribute to inflammatory tissue responses.^12,26–28Although DCs represent a major population of immune cells in the kidney,²⁹ their role in renal disease is poorly defined. Liposomal clodronate has been used to study the pathophysiologic role of phagocytic cells, which include DCs and macrophages.^3,30–32 An alternative DC-specific approach uses expression of the simian diphtheria toxin receptor (DTR) driven by the CD11c promoter to target DCs for DT-mediated cell death.²⁴ This model has been used extensively to study the role of DCs in various physiologic and pathophysiologic contexts^32,33; however, its application in kidney disease has been limited to recent studies of immune complex–mediated glomerulonephritis.^12,23We have reported that inflammation plays an important role in the pathogenesis of cisplatin-induced acute kidney injury (AKI).^1,4,5,34 Given the dearth of information regarding the role of renal DCs in AKI, this study examined the renal DC population and the impact of its depletion on cisplatin nephrotoxicity. We show that DCs are the most abundant population of renal resident leukocytes and form a dense network throughout the tubulointerstitium. Renal DCs displayed surface markers that distinguished them from splenic DCs. Using a conditional DC depletion model, we determined that DC ablation markedly exacerbates cisplatin-induced renal dysfunction, structural injury, and infiltration of neutrophils.     

Distinct Effects of Leptin and a Melanocortin Receptor Agonist Injected Into Medial Hypothalamic Nuclei on Glucose Uptake in Peripheral Tissues

OBJECTIVE

The medial hypothalamus mediates leptin-induced glucose uptake in peripheral tissues, and brain melanocortin receptors (MCRs) mediate certain central effects of leptin. However, the contributions of the leptin receptor and MCRs in individual medial hypothalamic nuclei to regulation of peripheral glucose uptake have remained unclear. We examined the effects of an injection of leptin and the MCR agonist MT-II into medial hypothalamic nuclei on glucose uptake in peripheral tissues.

RESEARCH DESIGN AND METHODS

Leptin or MT-II was injected into the ventromedial (VMH), dorsomedial (DMH), arcuate nucleus (ARC), or paraventricular (PVH) hypothalamus or the lateral ventricle (intracerebroventricularly) in freely moving mice. The MCR antagonist SHU9119 was injected intracerebroventricularly. Glucose uptake was measured by the 2-[³H]deoxy-d-glucose method.

RESULTS

Leptin injection into the VMH increased glucose uptake in skeletal muscle, brown adipose tissue (BAT), and heart, whereas that into the ARC increased glucose uptake in BAT, and that into the DMH or PVH had no effect. SHU9119 abolished these effects of leptin injected into the VMH. Injection of MT-II either into the VMH or intracerebroventricularly increased glucose uptake in skeletal muscle, BAT, and heart, whereas that into the PVH increased glucose uptake in BAT, and that into the DMH or ARC had no effect.

CONCLUSIONS

The VMH mediates leptin- and MT-II–induced glucose uptake in skeletal muscle, BAT, and heart. These effects of leptin are dependent on MCR activation. The leptin receptor in the ARC and MCR in the PVH regulate glucose uptake in BAT. Medial hypothalamic nuclei thus play distinct roles in leptin- and MT-II–induced glucose uptake in peripheral tissues.Leptin is an adipocyte hormone that inhibits food intake and increases energy expenditure (1). The hypothalamus is a principal target of leptin in its regulation of energy metabolism (2–5). The arcuate nucleus (ARC) is the most well characterized of hypothalamic nuclei in terms of its role in the central effects of leptin (2–5). The ARC contains two populations of leptin-responsive neurons: pro-opiomelanocortin (POMC)-expressing neurons, which release the potent anorexic peptide α-melanocyte–stimulating hormone, and neurons that release two potent orexigenic peptides, agouti-related peptide (AgRP) and neuropeptide Y (NPY) (2–5). α-Melanocyte–stimulating hormone activates the melanocortin receptor (MCR), whereas AgRP competitively inhibits this receptor and NPY functionally antagonizes MCR signaling (6). Both sets of neurons project to second-order MCR-expressing neurons within the hypothalamus, including the paraventricular (PVH), ventromedial (VMH), dorsomedial (DMH), and lateral hypothalamus, as well as to other brain regions such as the brain stem (2,4,7,8). Leptin inhibits food intake through reciprocal regulation of POMC and AgRP/NPY neurons in the ARC and consequent activation of MCR in hypothalamic nuclei, including the PVH (5,6,7,9). Mice lacking the melanocortin 3 (MC3R) or 4 (MC4R) receptor show increased adiposity and feeding efficiency (4). Restoration of MC4R expression in certain sets of PVH neurons prevented hyperphagia and reduced body weight in MC4R-null mice (9). In addition to that in the ARC, the leptin receptor Ob-Rb in other hypothalamic nuclei has also been shown to regulate energy intake and adiposity. Neurons positive for steroidogenic factor 1 (SF1; also known as Ad4BP) (10,11) are largely restricted to the VMH in the adult brain. Leptin depolarizes these neurons, and specific ablation of the leptin receptor in SF1-positive cells induced obesity and increased susceptibility to a high-fat diet in mice (12).The leptin receptor in the brain also regulates glucose metabolism in certain peripheral tissues (13–17). Treatment with leptin ameliorates diabetes in lipodystrophic mice and humans (18,19). Intravenous or intracerebroventricular administration of leptin markedly increased whole-body glucose turnover and glucose uptake by certain tissues in mice without any substantial change in plasma insulin or glucose levels (13). We have also previously shown that microinjection of leptin into the medial hypothalamus, such as into the VMH, but not into the lateral hypothalamus, preferentially increased glucose uptake in skeletal muscle, heart, and brown adipose tissue (BAT) (14–16). Restoration of Ob-Rb expression in the ARC and the VMH of the Ob-Rb–mutated Koletsky rat by adenovirus- or adeno-associated virus–mediated gene transfer improved peripheral insulin sensitivity and reduced plasma glucose concentration (17,20). Ablation of suppressor of cytokine signaling 3 (SOCS3) in SF1-positive cells (10,11) improved glucose homeostasis in mice fed a high-fat diet (21). Furthermore, intracerebroventricular injection of the MCR agonist (MT-II) increased whole-body glucose turnover and expression of GLUT4 in skeletal muscle (22). Ob-Rb in the ARC and the VMH as well as the brain melanocortin pathway are thus implicated in the regulation of glucose uptake in peripheral tissues as well as in energy metabolism. However, little is known about the contributions of the leptin receptor and MCR in individual medial hypothalamic nuclei to regulation of glucose uptake in peripheral tissues, as opposed to their roles in the regulation of food intake and leanness.We have now examined the acute effects of microinjection of leptin and MT-II into the VMH, ARC, DMH, and PVH, all of which express Ob-Rb, MC3R, and MC4R at a high level (3–7,23–25), on glucose uptake in peripheral tissues of mice in vivo. Our results suggest that the VMH mediates stimulatory actions of leptin and MT-II on glucose uptake in skeletal muscle, heart, and BAT, whereas the leptin receptor in the ARC as well as MCRs in PVH regulate glucose uptake in BAT. The medial hypothalamic nuclei thus appear to play distinct roles in the regulation of glucose uptake in peripheral tissues by leptin and MT-II.     

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephelopathy is an autosomal dominant disease affecting small vessels and often resulting in subcortical infarcts. A skin biopsy may facilitate its diagnosis as the cutaneous surface is much easier to sample than the central nervous system’s tissue. Unfortunately, there is no effective treatment available today.Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominant, small-vessel disease characterized by multiple subcortical ischemic infarcts. These infarcts mainly involve the central nervous system and can lead to disability and dementia.1,2 Linkage studies identified a mutation in the NOTCH3 gene on chromosome 19 as the genetic defect in CADASIL.3 The prevalence of the NOTCH3 gene mutation is 4.14 per 100,000 adults as estimated in a registry for CADASIL in Scotland.4 CADASIL is caused by mutations in one of the exons (from 2 to 24 out of the 33 exons) of the NOTCH3 gene within the epidermal growth factor receptor (EGFR)-like repeats in the extracellular domain of the NOTCH3 protein.5–7 More than 150 mutations have been identified so far and clustering of mutations on exons 3,4,5,8, and 11 has been reported.8,9 The missense mutations lead to a cysteine substitution in the EGFR on the extracellular N-terminal domain.8 This is thought to cause a defect in transendothelial exchange. Besides familial occurrence, sporadic cases are known to occur, which are more likely to go undiagnosed or misdiagnosed.10 In 70 percent of families, the mutations are located on exons 3 and 4 that encode the first 5 EGF domains.8A skin biopsy from a normal appearing cutaneous area can be very helpful in diagnosing CADASIL as the vascular changes can be observed using electron microscopy.11,12 The knowledge of CADASIL among dermatopathologists is important as patients with CADASIL may be referred by neurologists to carry out and interpret skin biopsies, ultimately providing a key diagnostic input. Additionally, a skin biopsy also helps to detect a carrier status.     

Maternal Antioxidant Supplementation Prevents Adiposity in the Offspring of Western Diet�CFed Rats

OBJECTIVE

Obesity in pregnancy significantly increases the risk of the offspring developing obesity after birth. The aims of this study were to test the hypothesis that maternal obesity increases oxidative stress during fetal development, and to determine whether administration of an antioxidant supplement to pregnant Western diet-fed rats would prevent the development of adiposity in the offspring.

RESEARCH DESIGN AND METHODS

Female Sprague Dawley rats were started on the designated diet at 4 weeks of age. Four groups of animals were studied: control chow (control); control + antioxidants (control+Aox); Western diet (Western); and Western diet + antioxidants (Western+Aox). The rats were mated at 12 to 14 weeks of age, and all pups were weaned onto control diet.

RESULTS

Offspring from dams fed the Western diet had significantly increased adiposity as early as 2 weeks of age as well as impaired glucose tolerance compared with offspring of dams fed a control diet. Inflammation and oxidative stress were increased in preimplantation embryos, fetuses, and newborns of Western diet-fed rats. Gene expression of proadipogenic and lipogenic genes was altered in fat tissue of rats at 2 weeks and 2 months of age. The addition of an antioxidant supplement decreased adiposity and normalized glucose tolerance.

CONCLUSIONS

Inflammation and oxidative stress appear to play a key role in the development of increased adiposity in the offspring of Western diet-fed pregnant dams. Restoration of the antioxidant balance during pregnancy in the Western diet-fed dam is associated with decreased adiposity in offspring.Obesity is one of the most pervasive and burdensome public health problems in modern times. The steady increase in overweight reproductive-age women is correlated with increases in rates of childhood and infant obesity. A possible link between the abnormal intrauterine environment and abnormal growth and development of offspring must be considered (1). The period from conception to birth is a time of rapid growth, cellular replication and differentiation, and functional maturation of organ systems. These processes are very sensitive to alterations of the nutritional milieu, and the abnormal intrauterine metabolic milieu associated with obesity in pregnancy can have long lasting effects on the development of obesity and diabetes in offspring (2,3). Maternal obesity significantly increases fetal and neonatal adiposity in humans; thus, enhanced adipocyte development per se must play an important role in the genesis of obesity in the offspring (2).It has been shown that obesity in the nonpregnant and pregnant state is associated with inflammation and oxidative stress (2–15). Obese individuals have higher plasma levels of 8-epi-prostaglandin F2α (PGF2α), an index of lipid peroxidation, and acute-phase proteins and proinflammatory cytokines such as tumor necrosis factor TNF-α and interleukin IL-6 (13–15). Recently, Hauguel-de Mouzon and colleagues (9,10) reported that expression of cytokines, inflammation-related genes, and genes linked to oxidative stress are markedly elevated in placenta of obese women. These studies demonstrate that not only does adipose tissue release inflammatory molecules, but that the placenta also contributes to the inflammatory/oxidant state and the stimuli favoring fetal fat accretion derived from maternal or placental sources. Thus, maternal obesity in pregnancy creates a very abnormal milieu in which the embryo and fetus develop. Further, a normal redox state is critical for embryonic stem cell differentiation (16). However, it is not known whether the offspring of obese mothers have an increased oxidant load or whether increased oxidative stress is linked to the development of obesity. The hypothesis that oxidative stress is causally linked to the development of obesity in offspring can be tested by determining whether antioxidants prevent increased adiposity in the offspring of obese mothers.The beneficial effects of antioxidant vitamins supplementation are attributed to their ability to scavenge free radicals, control nitric oxide synthesis or release, inhibit reactive oxygen species generation, and upregulate antioxidant enzyme activities that metabolize these molecules (17). Vitamins A, C, and E are nonenzymatic antioxidants that have properties of free radical scavengers. Vitamin C administration has been shown to reduce the adiposity induced by the intake of a high-fat diet in rats (18,19). Vitamin E has a particularly important role in preventing the oxidation of LDLs and thus has been the recent subject of investigation for use in cardiovascular disease. The antioxidant properties of zinc and selenium have also been demonstrated. Zinc directly inhibits the formation of O²⁻ by inhibiting the NADPH oxidase complex that catalyzes its formation, and indirectly, by inducing the production of metallothionein, a free radical scavenger. Selenium, in the form of selenoproteins (most notably selenocysteine), directly catalyzes the reduction of H₂O₂ and various other peroxides.Studies performed to evaluate the effectiveness of antioxidant supplementation in obese human adults have had mixed results. Of the many studies, only two have shown any positive effects (20,21). However, since adiposity significantly increases early in life, it is likely that there is a critical window of vulnerability early in development such that interventions given at this stage may have greater success in preventing the development of obesity.Several investigators have used animal models of high-fat or Western style diet-induced obesity (a diet that has increased fat and carbohydrate content) and have shown that maternal over-nutrition induces increased adiposity and permanent changes in metabolism in offspring (20–33). The aims of this study were to test the hypothesis that a Western-style diet fed during pregnancy increases oxidative stress, thereby potentiating adipogenesis in the offspring, and to determine whether administration of an antioxidant supplement to pregnant Western diet-fed rats would prevent the development of increased adiposity in offspring.     

Insulin resistance, defective insulin-mediated fatty acid suppression, and coronary artery calcification in subjects with and without type 1 diabetes: The CACTI study

OBJECTIVE

To assess insulin action on peripheral glucose utilization and nonesterified fatty acid (NEFA) suppression as a predictor of coronary artery calcification (CAC) in patients with type 1 diabetes and nondiabetic controls.

RESEARCH DESIGN AND METHODS

Insulin action was measured by a three-stage hyperinsulinemic-euglycemic clamp (4, 8, and 40 mU/m²/min) in 87 subjects from the Coronary Artery Calcification in Type 1 Diabetes cohort (40 diabetic, 47 nondiabetic; mean age 45 ± 8 years; 55% female).

RESULTS

Peripheral glucose utilization was lower in subjects with type 1 diabetes compared with nondiabetic controls: glucose infusion rate (mg/kg FFM/min) = 6.19 ± 0.72 vs. 12.71 ± 0.66, mean ± SE, P < 0.0001, after adjustment for age, sex, BMI, fasting glucose, and final clamp glucose and insulin. Insulin-induced NEFA suppression was also lower in type 1 diabetic compared with nondiabetic subjects: NEFA levels (μM) during 8 mU/m²/min insulin infusion = 370 ± 27 vs. 185 ± 25, P < 0.0001, after adjustment for age, sex, BMI, fasting glucose, and time point insulin. Lower glucose utilization and higher NEFA levels, correlated with CAC volume (r = −0.42, P < 0.0001 and r = 0.41, P < 0.0001, respectively) and predicted the presence of CAC (odds ratio [OR] = 0.45, 95% CI = 0.22–0.93, P = 0.03; OR = 2.4, 95% CI = 1.08–5.32, P = 0.032, respectively). Insulin resistance did not correlate with GHb or continuous glucose monitoring parameters.

CONCLUSIONS

Type 1 diabetic patients are insulin resistant compared with nondiabetic subjects, and the degree of resistance is not related to current glycemic control. Insulin resistance predicts the extent of coronary artery calcification and may contribute to the increased risk of cardiovascular disease in patients with type 1 diabetes as well as subjects without diabetes.Cardiovascular disease (CVD) remains the leading cause of death in individuals with type 1 diabetes (1–4). Although hyperglycemia appears to be the primary mediator of microvascular disease (5,6), its role in macrovascular disease is less clear (4). Tight glycemic control improves, but does not normalize CVD risk, and correlation of GHb to CVD risk remains controversial (7–15). In addition, standard prediction rules for CVD risk do not accurately predict CVD in type 1 diabetic populations (16). Thus, the mechanism of accelerated atherosclerosis in type 1 diabetes is unclear and identification of those patients at highest risk and most in need of aggressive risk factor modification is inaccurate.In the general population, insulin resistance has been implicated as an important contributor to accelerated atherosclerosis (17–25). Although type 1 diabetes is primarily a disease of insulin deficiency, previous studies have demonstrated insulin resistance and suggested that CVD may also be linked to insulin resistance in type 1 diabetes (10,26–32). As early as 1968, Martin et al. (30) demonstrated an “impaired glucose assimilation index” and an inverse association between this index and prevalent macrovascular disease in type 1 diabetic subjects. More recently, the Pittsburgh Epidemiology of Diabetes Complications Study (10) found no correlation between GHb and coronary artery disease outcomes. However, in addition to other known CVD risk factors, estimated glucose disposal rate correlated inversely with these outcomes. Similar correlations of estimated insulin resistance or a surrogate of insulin resistance (waist-to-hip ratio) to coronary artery disease were also found in the Diabetes Control and Complications Trial (DCCT) and the EURODIAB study (33). These data suggest that an estimate of insulin resistance may add to CVD risk prediction in type 1 diabetes. In addition, elevated nonesterified fatty acid (NEFA) levels have been proposed to mediate the increased atherosclerotic risk associated with insulin resistance in the general population (18,34–37). It is not known whether the defects in insulin action in type 1 diabetes extend beyond glucose utilization to NEFA suppression.The Coronary Artery Calcification in Type 1 Diabetes (CACTI) study has followed a cohort of type 1 diabetic subjects and similar nondiabetic controls with electron beam computed tomography for measurement of coronary artery calcification (CAC) and CVD outcomes for 6 years (15,38). We hypothesized that type 1 diabetic subjects would be more insulin resistant than nondiabetic controls in terms of both glucose utilization and NEFA suppression, and that both measures of insulin resistance would correlate with CAC, a marker of the extent of coronary atherosclerosis.     

Recurrence of Lupus Nephritis after Kidney Transplantation

The frequency and outcome of recurrent lupus nephritis (RLN) among recipients of a kidney allograft vary among single-center reports. From the United Network for Organ Sharing files, we estimated the period prevalence and predictors of RLN in recipients who received a transplant between 1987 and 2006 and assessed the effects of RLN on allograft failure and recipients'' survival. Among 6850 recipients of a kidney allograft with systemic lupus erythematosus, 167 recipients had RLN, 1770 experienced rejection, and 4913 control subjects did not experience rejection. The period prevalence of RLN was 2.44%. Non-Hispanic black race, female gender, and age <33 years each independently increased the odds of RLN. Graft failure occurred in 156 (93%) of those with RLN, 1517 (86%) of those with rejection, and 923 (19%) of control subjects without rejection. Although recipients with RLN had a fourfold greater risk for graft failure compared with control subjects without rejection, only 7% of graft failure episodes were attributable to RLN compared and 43% to rejection. During follow-up, 867 (13%) recipients died: 27 (16%) in the RLN group, 313 (18%) in the rejection group, and 527 (11%) in the control group. In summary, severe RLN is uncommon in recipients of a kidney allograft, but black recipients, female recipient, and younger recipients are at increased risk. Although RLN significantly increases the risk for graft failure, it contributes far less than rejection to its overall incidence; therefore, these findings should not keep patients with lupus from seeking a kidney transplant.The frequency and clinical impact of recurrent lupus nephritis (RLN) in the kidney allograft of recipients with systemic lupus erythematosus (SLE) varies considerably in both prospective and retrospective studies.^1–25 In 1996, Mojcik and Klippel²⁶ pooled data from a total of 366 allografts transplanted in 338 recipients. In that review, histologic RLN was present in 3.8% of the grafts. Contrasting, in the studies by Goral et al.²⁷ and Nyberg et al.,¹⁰ RLN was reported in a much higher proportion: 30 and 44% of recipients, respectively.The clinical consequences of RLN on patient and allograft survival have ranged from no effect to a significant increase in the risk for graft loss and patient mortality.^24,27–31 In this case-control study, we estimated the period prevalence of RLN in kidney transplant recipients who had ESRD secondary to lupus nephritis and received a transplant between October 1987 and October 2006. We assessed the effects of RLN on graft failure and recipient survival and the risk factors leading to the development of RLN.