IL28B alleles associated with poor hepatitis C virus (HCV) clearance protect against inflammation and fibrosis in patients infected with non-1 HCV genotypes

Genetic polymorphisms near IL28B are associated with spontaneous and treatment-induced clearance of hepatitis C virus (HCV), two processes that require the appropriate activation of the host immune responses. Intrahepatic inflammation is believed to mirror such activation, but its relationship with IL28B polymorphisms has yet to be fully appreciated. We analyzed the association of IL28B polymorphisms with histological and follow-up features in 2335 chronically HCV-infected Caucasian patients. Assessable phenotypes before any antiviral treatment included necroinflammatory activity (n = 1,098), fibrosis (n = 1,527), fibrosis progression rate (n = 1,312), and hepatocellular carcinoma development (n = 1,915). Associations of alleles with the phenotypes were evaluated by univariate analysis and multivariate logistic regression, accounting for all relevant covariates. The rare G allele at IL28B marker rs8099917-previously shown to be at risk of treatment failure-was associated with lower activity (P = 0.04), lower fibrosis (P = 0.02) with a trend toward lower fibrosis progression rate (P = 0.06). When stratified according to HCV genotype, most significant associations were observed in patients infected with non-1 genotypes (P = 0.003 for activity, P = 0.001 for fibrosis, and P = 0.02 for fibrosis progression rate), where the odds ratio of having necroinflammation or rapid fibrosis progression for patients with IL28B genotypes TG or GG versus TT were 0.48 (95% confidence intervals 0.30-0.78) and 0.56 (0.35-0.92), respectively. IL28B polymorphisms were not predictive of the development of hepatocellular carcinoma. CONCLUSION: In chronic hepatitis C, IL28B variants associated with poor response to interferon therapy may predict slower fibrosis progression, especially in patients infected with non-1 HCV genotypes.     

Modulation of regulatory T-cell activity in combination with interleukin-12 increases hepatic tolerogenicity in woodchucks with chronic hepatitis B

Regulatory T cells (Treg) play a critical role in the modulation of immune responses to viral antigens in chronic viral hepatitis. Woodchucks (Marmota monax) infected with the woodchuck hepatitis virus (WHV) represent the best animal model for chronic hepatitis B virus (HBV) infection. Examination of intrahepatic and peripheral Treg in uninfected and WHV chronically infected woodchucks showed a significant increase of intrahepatic Treg numbers in chronically infected animals, whereas no differences were found in peripheral blood. In agreement with these data, higher expression levels of Forkhead box P3 (Foxp3), interleukin (IL)-10, transforming growth factor beta (TGF-β) were detected in the liver of chronic WHV carriers in comparison to uninfected animals. Furthermore, treatment of WHV-infected animals with an adenovirus encoding IL-12 failed to reduce viral load, a finding that was associated with lymphocyte unresponsiveness to IL-12 stimulation in vitro. We observed that TGF-β and Treg play a major role in the lack of lymphocyte response to IL-12 stimulation, as TGF-β inhibition and Treg depletion allowed recovery of T-cell responsiveness to this cytokine. Based on these results, woodchucks were treated with IL-12 in combination with a TGF-β inhibitory peptide or Treg depletion. However, no antiviral effect was achieved and, instead, an enhancement of the intrahepatic tolerogenic environment was observed. CONCLUSION: Our data show that TGF-β inhibition or Treg depletion had no added benefit over IL-12 therapy in chronic WHV infection. IL-12 immunostimulation induces a strong immunosuppressive reaction in the liver of chronic WHV carriers that counteracts the antiviral effect of the treatment.     

Protection Against Type 1 Diabetes Upon Coxsackievirus B4 Infection and iNKT-Cell Stimulation: Role of Suppressive Macrophages

Invariant natural killer T (iNKT) cells belong to the innate immune system and exercise a dual role as potent regulators of autoimmunity and participate in responses against different pathogens. They have been shown to prevent type 1 diabetes development and to promote antiviral responses. Many studies in the implication of environmental factors on the etiology of type 1 diabetes have suggested a link between enteroviral infections and the development of this disease. This study of the pancreatropic enterovirus Coxsackievirus B4 (CVB4) shows that although infection accelerated type 1 diabetes development in a subset of proinsulin 2–deficient NOD mice, the activation of iNKT cells by a specific agonist, α-galactosylceramide, at the time of infection inhibited the disease. Diabetes development was associated with the infiltration of pancreatic islets by inflammatory macrophages, producing high levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α and activation of anti-islet T cells. On the contrary, macrophages infiltrating the islets after CVB4 infection and iNKT-cell stimulation expressed a number of suppressive enzymes, among which indoleamine 2,3-dioxygenase was sufficient to inhibit anti-islet T-cell response and to prevent diabetes. This study highlights the critical interaction between virus and the immune system in the acceleration or prevention of type 1 diabetes.Type 1 diabetes is characterized by the destruction of pancreatic islet β-cells by autoreactive CD4 and CD8 T cells, leading to low insulin production and incapacity to regulate blood glucose levels (1). Despite numerous studies, the etiology of type 1 diabetes remains elusive. Besides genetics (2–4), environmental factors such as viral infections have been suggested as triggers of type 1 diabetes (5–7). Most striking of these infections are the type B Coxsackieviruses belonging to the enterovirus genus whose genome and anti-Coxsackievirus antibodies were detected more frequently in the blood of recently diagnosed patients compared with healthy controls (8,9). Besides, enteroviral RNA or enteroviral particles were directly detected in the pancreas of type 1 diabetic patients, whereas they were undetectable in the pancreas of healthy donors (9,10). In a mouse model of type 1 diabetes, Serreze et al. (11) showed that diabetes can develop rapidly after Coxsackievirus B4 (CVB4) infection if mice had an advanced age and sufficient insulitis. Others have reported that inefficient islet β-cell response, viral dose, and replication rate as well as a lack of islet neogenesis could also promote accelerated diabetes development after CVB4 infection (12–14).Natural killer T (NKT) cells are CD1d-restricted, nonconventional T cells recognizing self and exogenous glycolipids. Most NKT cells express an invariant T-cell receptor α chain, Vα14-Jα18 (Vα14) in mice and Vα24-Jα18 in humans, and are named invariant NKT (iNKT) cells. They can promptly secrete copious amounts of interferon-γ (IFN-γ) and interleukin (IL)-4 and provide maturation signals to dendritic cells (DCs) and lymphocytes, thereby contributing to both innate and acquired immunity (15,16). iNKT cells are potent regulatory cells that can inhibit autoimmunity and promote immune responses against pathogens (1,17). Diabetes can be prevented in NOD mice by increasing iNKT cell numbers and by iNKT-cell stimulation with exogenous ligands such as α-galactosylceramide (αGalCer) (15,18,19). NOD mice protected from diabetes by iNKT cells have weak T helper 1 anti-islet β-cell responses (20). Indeed, iNKT cells can impair the differentiation of anti-islet CD4 and CD8 T cells, which become hyporesponsive or anergic (21). Contrary to their suppressive role in type 1 diabetes, iNKT cells can enhance immune responses to pathogens such as parasites, bacteria, and viruses (22,23).Our previous studies conducted in a murine model of type 1 diabetes with lymphocytic choriomeningitis virus infection revealed that iNKT cells could promote systemic antiviral CD8 T-cell responses while inhibiting deleterious anti-islet T-cell responses, thereby preventing type 1 diabetes (24,25). In the present study, we investigated the role of iNKT cells after CVB4 infection, revealing that diabetes development following CVB4 infection is associated with the infiltration of inflammatory macrophages into the pancreatic islets with subsequent activation of anti-islet T cells. However, the activation of iNKT cells during CVB4 infection results in the infiltration of suppressive macrophages into pancreatic islets. Indoleamine 2,3-dioxygenase (IDO) expressed by these macrophages was critical for the inhibition of diabetes development.     

Pioglitazone Acutely Reduces Energy Metabolism and Insulin Secretion in Rats

Our objective was to determine if the insulin-sensitizing drug pioglitazone acutely reduces insulin secretion and causes metabolic deceleration in vivo independently of change in insulin sensitivity. We assessed glucose homeostasis by hyperinsulinemic-euglycemic and hyperglycemic clamp studies and energy expenditure by indirect calorimetry and biotelemetry in male Wistar and obese hyperinsulinemic Zucker diabetic fatty (ZDF) rats 45 min after a single oral dose of pioglitazone (30 mg/kg). In vivo insulin secretion during clamped hyperglycemia was reduced in both Wistar and ZDF rats after pioglitazone administration. Insulin clearance was slightly increased in Wistar but not in ZDF rats. Insulin sensitivity in Wistar rats assessed by the hyperinsulinemic-euglycemic clamp was minimally affected by pioglitazone at this early time point. Pioglitazone also reduced energy expenditure in Wistar rats without altering respiratory exchange ratio or core body temperature. Glucose-induced insulin secretion (GIIS) and oxygen consumption were reduced by pioglitazone in isolated islets and INS832/13 cells. In conclusion, pioglitazone acutely induces whole-body metabolic slowing down and reduces GIIS, the latter being largely independent of the insulin-sensitizing action of the drug. The results suggest that pioglitazone has direct metabolic deceleration effects on the β-cell that may contribute to its capacity to lower insulinemia and antidiabetic action.Major drugs developed to treat type 2 diabetes aim at either increasing insulin secretion or reducing insulin resistance (1–4). Two classes of insulin-sensitizing agents are currently used, the biguanides (metformin) and the thiazolidinediones (TZDs), of which the only one still recommended for use in some countries is pioglitazone (5). TZDs are peroxisome proliferator–activated receptor-γ (PPARγ) agonists. They stimulate adipocyte differentiation, relieving other tissues from fat excess, thereby reducing their resistance to insulin (6,7). The beneficial effects of TZDs are not limited to increased insulin sensitivity and also include preservation of β-cell function (8). It is thought that the beneficial effect of TZDs on β-cell function in vivo is indirect and occurs via a relief of the need for insulin hypersecretion because of their insulin sensitizing action. We should, however, consider the possibility that the classical antidiabetic insulin sensitizers, pioglitazone and metformin, might also have beneficial effects on glucose homeostasis via direct reduction of insulin hypersecretion independently of insulin resistance.We previously demonstrated in vitro that pioglitazone acutely slows down glucose and lipid metabolism in the β cell and inhibits glucose-induced insulin secretion (GIIS) primarily at submaximal and much less at maximal glucose concentrations (right shift in the glucose dose response) via a PPARγ-independent mechanism (9). These acute effects of pioglitazone are likely attributable to complex I inhibition of the electron transport chain (10) and involve reduced glucose oxidation, decreased ATP levels, and increased AMPK activation (9). Interestingly, metformin causes similar effects (J.L. and M.P., unpublished data). Hence, we proposed the novel concept of “metabolic deceleration” as a mode of action of some antidiabetic drugs and suggested that the action of pioglitazone to reduce glucose metabolism and insulin secretion in the β-cell may partly explain its beneficial effects (9). The concept that metabolic deceleration protects the β-cell from both oxidative and endoplasmic reticulum stress has recently been reviewed (11,12).In the current study we performed in vivo experiments in normal Wistar and obese Zucker diabetic fatty (ZDF) rats to better understand how acute treatment with pioglitazone alters glucose homeostasis, with particular focus on how it reduces hyperinsulinemia. The following questions were asked: 1) Can we confirm in vivo our previous in vitro findings in isolated rat islet and β-cell line that pioglitazone acutely reduces insulin secretion? 2) Is this acute effect of pioglitazone on insulin secretion independent of its effects on insulin sensitivity? and 3) Does pioglitazone acutely slow down whole-body energy metabolism?     

Seasonal variations of systemic lupus erythematosus flares in southern France

ObjectiveExposure to sunlight is one of the environmental factors involved in the pathogenesis of systemic lupus erythematosus. We investigated whether there is seasonal variation in the incidence of cutaneous and noncutaneous severe lupus flares in southern France.MethodsWe retrospectively reviewed clinical and biological data from all SLE patients hospitalized for a flare of the disease during a two year period in our centre and collected corresponding meteorological data from the official website of MeteoFrance.ResultsForty one patients, mean age 36.7 ± 13.8 years, were included. Twenty-six patients (63.4%) had kidney biopsy performed, showing in all cases proliferative nephritis, associated with membranous nephritis in 9 (22%). We found a clear seasonal pattern for overall lupus flares with 39% of flares occurred in Spring. Among patients without any cutaneous involvement, this seasonal pattern was still observed (p = 0.024). Patients under antimalarials presented flares significantly later in the sunny season than those without (respectively median in July versus May, p = 0.044). There were strong positive correlations between occurrence of lupus flares and maximum temperature increase (ρ = 0.87, p < 0.001), minimum temperature increase (ρ = 0.87, p < 0.001), and duration of sunshine increase (ρ = 0.78, p = 0.003). These correlations were also observed in patients with renal flares.ConclusionWe confirmed a seasonal pattern for lupus flares among patients living in Southern France, with most flares in spring, in correlation with an increase in temperature and duration of sunshine. A similar seasonal pattern was observed in patients with no cutaneous involvement and with visceral involvement.     

Toward magnetic resonance-guided electroanatomical voltage mapping for catheter ablation of scar-related ventricular tachycardia: a comparison of registration methods

Toward MR‐Guided Electroanatomical Voltage Mapping for Catheter Ablation. Introduction: Integration of preprocedural delayed enhanced magnetic resonance imaging (DE‐MRI) with electroanatomical voltage mapping (EAVM) may provide additional high‐resolution substrate information for catheter ablation of scar‐related ventricular tachycardias (VT). Accurate and fast image integration of DE‐MRI with EAVM is desirable for MR‐guided ablation. Methods and Results: Twenty‐six VT patients with large transmural scar underwent catheter ablation and preprocedural DE‐MRI. With different registration models and EAVM input, 3 image integration methods were evaluated and compared to the commercial registration module CartoMerge. The performance was evaluated both in terms of distance measure that describes surface matching, and correlation measure that describes actual scar correspondence. Compared to CartoMerge, the method that uses the translation‐and‐rotation model and high‐density EAVM input resulted in a registration error of 4.32±0.69 mm as compared to 4.84 ± 1.07 (P <0.05); the method that uses the translation model and high‐density EAVM input resulted in a registration error of 4.60 ± 0.65 mm (P = NS); and the method that uses the translation model and a single anatomical landmark input resulted in a registration error of 6.58 ± 1.63 mm (P < 0.05). No significant difference in scar correlation was observed between all 3 methods and CartoMerge (P = NS). Conclusions: During VT ablation procedures, accurate integration of EAVM and DE‐MRI can be achieved using a translation registration model and a single anatomical landmark. This model allows for image integration in minimal mapping time and is likely to reduce fluoroscopy time and increase procedure efficacy. (J Cardiovasc Electrophysiol, Vol. 23, pp. 74‐80, January 2012)