An immune-sympathetic neuron communication axis guides adipose tissue browning in cancer-associated cachexia

Cancer-associated cachexia (CAC) is a hypermetabolic syndrome characterized by unintended weight loss due to the atrophy of adipose tissue and skeletal muscle. A phenotypic switch from white to beige adipocytes, a phenomenon called browning, accelerates CAC by increasing the dissipation of energy as heat. Addressing the mechanisms of white adipose tissue (WAT) browning in CAC, we now show that cachexigenic tumors activate type 2 immunity in cachectic WAT, generating a neuroprotective environment that increases peripheral sympathetic activity. Increased sympathetic activation, in turn, results in increased neuronal catecholamine synthesis and secretion, β-adrenergic activation of adipocytes, and induction of WAT browning. Two genetic mouse models validated this progression of events. 1) Interleukin-4 receptor deficiency impeded the alternative activation of macrophages, reduced sympathetic activity, and restrained WAT browning, and 2) reduced catecholamine synthesis in peripheral dopamine β-hydroxylase (DBH)–deficient mice prevented cancer-induced WAT browning and adipose atrophy. Targeting the intraadipose macrophage-sympathetic neuron cross-talk represents a promising therapeutic approach to ameliorate cachexia in cancer patients.

Cancer-associated cachexia (CAC) is an energy balance disorder causing unintended loss of body weight due to depletion of white adipose tissue (WAT) and skeletal muscle. This multiorgan and multifactorial syndrome affects up to 80% of cancer patients and is responsible for more than 20% of cancer-associated deaths (1). CAC impedes the effectiveness of anticancer therapies and drastically lowers patients’ quality of life (2).A long list of tumor-borne, often proinflammatory factors, including interleukin-6 (IL-6) (3), parathyroid hormone–related protein (PTHrP) (4), leukemia inhibitory factor (LIF) (5), zinc α-glycoprotein (6), or growth differentiation factor-15 (GDF-15) (7), trigger CAC in mouse models. However, the signaling cascades and catabolic mechanisms that lead to adipose- and muscle tissue wasting remain insufficiently understood (8, 9). IL-6 and PTHrP are among the best studied of these “cachexokines.” Their presence or absence is decisive for the development of CAC in cancer patients and animal models (4, 10–13). Thus, treatment with neutralizing antibodies against IL-6, the IL-6 receptor, or PTHrP ameliorates CAC in various mouse models of CAC (3, 4, 14, 15).CAC-associated WAT atrophy results from a metabolic switch toward decreased lipid synthesis and excessive degradation of lipid stores via enhanced triglyceride degradation (lipolysis) (9, 16). Induced lipolysis is observed in both humans and mice with CAC (17, 18). The absence of metabolic lipases at least partially ameliorates cachexia in murine cancer models (19). The metabolic or catabolic fates of lipolytic products, namely fatty acids (FAs) and glycerol, have not been fully clarified. These may provide energy and/or biosynthetic substrates for cancer cells to promote tumor growth or can be reesterified in WAT, creating an adenosine-triphosphate (ATP)-consuming futile metabolic cycle. Both of these pathways would contribute to the eventual loss of WAT during CAC (20).Another important catabolic pathway in CAC involves the direct oxidation of FAs and glycerol in adipose tissue. This process is promoted by the conversion of white to beige adipocytes called “WAT browning.” During WAT browning, adipocytes adopt a multilocular lipid droplet morphology; express genes that are typical for brown adipocytes, such as uncoupling protein-1 (UCP-1); exhibit elevated substrate oxidation rates; and dissipate energy as heat (21). WAT browning occurs in carcinogen-induced cancer models and genetically engineered mouse models as well as syngeneic and xenogeneic transplant models of murine cancers (3, 4, 22) and depends on the presence of cachexokines. WAT browning also occurs in humans suffering CAC or severe burn trauma (3, 23–25), but the cellular and molecular mechanisms underlying catabolic WAT remodeling in CAC remain unclear.Here, we demonstrate that a macrophage-sympathetic neuron signaling axis generates a high β-adrenergic tone resulting in beige adipogenesis, increased lipid degradation, and WAT atrophy in murine models of CAC. This mechanism triggering hypermetabolism in CAC may offer targets for prevention or treatment of the disease.     

Torsion in patients with superior oblique palsies: dynamic torsion during saccades and changes in Listing’s plane

Background The purpose was to assess intra- and post-saccadic torsion in superior oblique palsy (SOP) patients and the effect of surgery on torsion. Methods Eleven patients with a presumed congenital SOP and five with acquired SOP performed 10° vertical saccades over a range of ±20°. Eye movements were recorded with dual search coils. Dynamic torsion was calculated by subtracting the expected change in torsion during the saccade (based upon static torsion before and after the saccade) from the maximum intrasaccadic torsion. Eight healthy subjects were controls. We also examined the effects of surgery on dynamic torsion and the orientation of Listing’s plane in patients with congenital SOP who were operated on either by weakening of the inferior oblique muscle on the affected eye (n = 5), by recession of the inferior rectus muscle on the normal eye (n = 4) or by both procedures (n = 2). Postoperative recordings were obtained at least 1 month after surgery. Results Patients with congenital and acquired SOP showed an increased dynamic extorsion, primarily during downward saccades. Following a recession of the inferior oblique muscle in congenital SOP patients, half showed significant decreases in extorsion (up to 1.0°) during downward saccades by the affected eye. Following surgery all showed a temporal rotation of Listing’s plane (up to 15° for primary position). Conclusion Patients with a SOP show a characteristic pattern of dynamic torsion during vertical saccades differing from normals. Recession of the inferior oblique muscle leads to rotation of Listing’s plane in all congenital SOP patients and causes large changes in dynamic torsion in a subgroup of them, perhaps reflecting the heterogeneity of congenital SOP. This study was supported by the Deutsche Forschungsgemeinschaft DFG 860/2-1, Bonn Germany, Grant EYO1489, from the National Institute of Health, Bethesda, Maryland, the Abe Pollin scholarship fund, Swiss National Science Foundation Grant 3200B0-105434 and the Betty and David Koetser Foundation for Brain Research, Zurich, Switzerland.     

Long-term results of surgery in childhood glaucoma

Purpose The aim of this study is to assess the functional results and morphological parameters in children surgically treated for glaucoma. Methods Data from 43 patients and 68 eyes who were operated in our department between 1990 and 2002 were collected. This retrospective trial included primary congenital glaucoma (n=36), and secondary glaucoma (n=7) in Rieger-Axenfeld syndrome and Sturge Weber syndrome. Intraocular pressure (IOP), axial length of the eyeball, visual acuity, refractive errors and orthoptic status were analysed. Results The age of patients at the first surgery was 6.0±5.3 months (range 0.7 to 28.0 months). The mean period of follow-up was 57.3±36.8 months (6.0–161.0).The mean number of surgical procedures performed on one eye was 2.5±2.4 procedures (1–11). The mean IOP before the first surgery was 31.0±7.9 mmHg (17.5–52.0), and was 15.0±3.9 mmHg (7.0–28.0) at the last visit. 49 eyes (72.1%) did not need any further medical treatment after the last surgical procedure. The IOP was 18 mmHg or lower without medication in 29 eyes (42.6%) after just one surgical procedure (21 trabeculotomy, 8 combined trabeculotomy/trabeculectomy with or without mitomycin-C). At the first examination, the mean axial length of the eyeball was 22.6±1.8 mm (the mean normal value at this age is 20.3±0.7 mm), and was 24.4±2.0 mm at the last visit (the mean normal value at this age is 22.2±0.6 mm). The best corrected visual acuity at the last visit was 0.25±4.6 lines; the normal range of visual acuity at this age is from 0.4±4.0 lines to 0.8±3.0 lines. Visual acuity was 0.32 or more in 53.0% of the eyes. Visual acuity was lower than 0.1 in only 15.2% of the eyes. Myopia was present in 57.4% of the eyes with a mean spherical equivalent of −6.1±3.9 dioptres. 15 patients (34.9%) developed strabismus. 22 patients (51.2%) were treated with part-time occlusion. Binocular function as assessed with the Lang-1 test was positive in 17 of 30 patients (56.7%). Conclusions Although a good long-term IOP-control can often be achieved in childhood glaucoma, the visual acuity remains below the normal range in most cases despite close orthoptic follow-up. Excerpts presented at the meeting of the German Society of Ophthalmology (DOG), Berlin, 2004.     

Differential protein kinase C ligand regulation detected in vivo by a phenotypic yeast assay

The molecular dissection of protein kinase C (PKC) action has been based in part on time-consuming functional assays such as the mouse skin model for testing the tumor promoter activity of phorbol esters and related PKC activators. To help overcome the limitations imposed by the complexity of such assays, we developed the yeast Saccharomyces cerevisiae as an alternative, rapid, and simple experimental system. This model has a specific phenotype, an increase in the cell doubling time, that is proportional to the level of enzymatic activity of expressed mammalian PKC isoforms. We used this phenotype to assay and compare the regulation of native bovine PKCα and mutants in the conserved regulatory region C1 in vivo by various activators: two diterpenes, the phorbol ester phorbol-12-myristate-13-acetate (PMA) and mezerein, and the indole alkaloid indolactam V. We found that PMA activated PKC mutants lacking either Cys-rich, zinc finger-like repeat of the conserved region C1 to comparably reduced levels, whereas indolactam V activated native PKCα but none of the mutants at normal doses. In contrast, mezerein activated native PKCα and a mutant lacking the second Cys repeat equally well but mutants lacking the first Cys repeat of C1 at a greatly reduced level. These differential rsponses were supported by the observed in vitro PKC catalytic activities. Therefore, PMA regulates PKCα activity comparably well via either Cys repeat, whereas mezerein regulation predominantly occurs via the first Cys repeat of C1. Indolactam V activation was less potent, it was greatly reduced in the absence of either Cys repeat, and displayed no preference. We introduce this phenotypic assay as a rapid and general screen for the PKC-activating or possibly inhibitory potential of drug candidates and to identify the PKC regulatory sites involved in these interactions. © 1995 Wiley-Liss Inc.     

Kjellin's syndrome: fundus autofluorescence,angiographic, and electrophysiologic findings

OBJECTIVE: Syndromes with genetically determined retinal diseases and concurrent multiple neurologic abnormalities are rare. Kjellin described an autosomal recessive entity with spastic paraplegia, mental retardation, amyotrophia, and macular dystrophy. We sought to further characterize the retinal phenotype and to contrast fundus changes and the genotype to Stargardt's disease in a young patient with progressive Kjellin's syndrome. DESIGN: Observational case report and family genetic study. PATIENTS: One affected and 11 unaffected members of a family with Kjellin's syndrome were investigated. METHODS: Complete ophthalmologic and neurologic examinations were performed, including electrophysiologic evaluation, color vision assessment, fundus autofluorescence, and fluorescence angiography. To investigate a possible role of the ABCA4 gene in the etiology of the macular changes, the entire 50 coding exons, including flanking intronic sequences of the patient, were analyzed by direct sequencing. MAIN OUTCOME MEASURES: The patient was evaluated for her symptoms, retinal function, fundus autofluorescence, angiography, and mutations in the ABCA4 gene. RESULTS: A 27-year-old female patient initially was seen with trembling of her right hand. Subsequently, progressive paraspasticity occurred, and a diagnostic workup revealed mild mental retardation. Biomicroscopy disclosed symmetric multiple round yellowish flecks at the level of the retinal pigment epithelium scattered at the posterior pole, which showed increased intrinsic fluorescence in the center, with a halo of reduced autofluorescence. Multifocal electroretinography elicited abnormal responses in the macular area in the presence of normal Ganzfeld electroretinography recordings. In gene mapping, several common variants were identified, although none seem to be associated with the disease features. CONCLUSIONS: Macular changes in Kjellin's syndrome share phenotypic characteristics with Stargardt's disease, although there are differences with regard to appearance, distribution, angiographic, and autofluorescence behavior of the retinal flecks. Ophthalmologic examination is prudent in patients with similar neurologic deficits, because it is essential for the diagnosis and because visual symptoms may be absent even in the presence of obvious and widespread retinal manifestations. The abnormal gene product in Kjellin's syndrome seems to cause progressive dysfunction in various neuronal tissues but seems to be distinct from the major defect underlying the Stargardt's disease phenotype.     

Circulating tuberculostearic acid in tuberculosis patients

Tuberculostearic acid (TBSA), a mycobacterial cell wall constituent, was measured in plasma samples using a highly sensitive high-performance liquid chromatography method. Plasma TBSA concentrations in patients with active tuberculosis (20 [0.5-347] nmol/l; n = 125) were higher than in patients with a variety of non-tuberculous pulmonary and extrapulmonary inflammatory conditions (0.1 [0-29] nmol/l; n = 116) and in healthy controls (0 [0-2] nmol/l; n = 102) (p = < 0.001). The calculated sensitivity, specificity, positive and negative predictive values for tuberculosis were 95.2%, 87.9%, 89.5% and 94.4%, respectively, indicating that assay of plasma TBSA might be a valuable complementary diagnostic tool.     

Epitope-specific antibody response to Mel-CAM induced by mimotope immunization

Peptide mimotopes of tumor antigen epitopes have been proposed as components of tumor vaccines. In this study, we determined the immunogenicity of melcam mim1 and melcam mim2, peptide mimics of an epitope of the melanoma cell-adhesion molecule (Mel-CAM). BALB/c mice were vaccinated either with mimotopes or mimotopes coupled to tetanus toxoid (TT). The antibody responses of mice to melcam mim1, melcam mim2, and recombinant Mel-CAM were analyzed by an ELISA and immunoblot analyses. TT-coupled mimotopes led to high titers of IgG mainly of the IgG2a subclass to melcam mim1 and melcam mim2. Immunization with each of the mimotope formulations induced antibodies that cross-reacted with recombinant Mel-CAM. Uncoupled mimotopes induced lymphocyte proliferation and cytokine production in spleen cell cultures indicating that both peptide mimotopes also contained T cell epitopes. TT-coupled mimotopes induced T helper (Th)1 (interleukin (IL)-2, interferon-gamma) and Th2 (IL-4, IL-5) cytokines, whereas uncoupled mimotopes induced a Th1-biased T cell response. Our results suggest that mimotopes potentially represent a novel vaccine approach to induce a tumor antigen-specific humoral and cellular response.