A self-sustained loop of inflammation-driven inhibition of beige adipogenesis in obesity.

In obesity, inflammation of white adipose tissue (AT) is associated with diminished generation of beige adipocytes ('beige adipogenesis'), a thermogenic and energy-dissipating function mediated by beige adipocytes that express the uncoupling protein UCP1. Here we delineated an inflammation-driven inhibitory mechanism of beige adipogenesis in obesity that required direct adhesive interactions between macrophages and adipocytes mediated by the integrin α4 and its counter-receptor VCAM-1, respectively; expression of the latter was upregulated in obesity. This adhesive interaction reciprocally and concomitantly modulated inflammatory activation of macrophages and downregulation of UCP1 expression dependent on the kinase Erk in adipocytes. Genetic or pharmacological inactivation of the integrin α4 in mice resulted in elevated expression of UCP1 and beige adipogenesis of subcutaneous AT in obesity. Our findings, established in both mouse systems and human systems, reveal a self-sustained cycle of inflammation-driven impairment of beige adipogenesis in obesity.

Brain Endothelial- and Epithelial-Specific Interferon Receptor Chain 1 Drives Virus-Induced Sickness Behavior and Cognitive Impairment.

Sickness behavior and cognitive dysfunction occur frequently by unknown mechanisms in virus-infected individuals with malignancies treated with type I interferons (IFNs) and in patients with autoimmune disorders. We found that during sickness behavior, single-stranded RNA viruses, double-stranded RNA ligands, and IFNs shared pathways involving engagement of melanoma differentiation-associated protein 5 (MDA5), retinoic acid-inducible gene 1 (RIG-I), and mitochondrial antiviral signaling protein (MAVS), and subsequently induced IFN responses specifically in brain endothelia and epithelia of mice. Behavioral alterations were specifically dependent on brain endothelial and epithelial IFN receptor chain 1 (IFNAR). Using gene profiling, we identified that the endothelia-derived chemokine ligand CXCL10 mediated behavioral changes through impairment of synaptic plasticity. These results identified brain endothelial and epithelial cells as natural gatekeepers for virus-induced sickness behavior, demonstrated tissue specific IFNAR engagement, and established the CXCL10-CXCR3 axis as target for the treatment of behavioral changes during virus infection and type I IFN therapy.

The effect of plasma exchange on serum anti-JC virus antibodies.

OBJECTIVE: Natalizumab, a highly effective treatment for multiple sclerosis (MS) and Crohn's disease, is associated with progressive multifocal leukoencephalopathy (PML). Upon suspicion or diagnosis of PML, plasma exchange (PLEX) is performed to remove natalizumab from the circulation, allowing immune reconstitution of the central nervous system. Since PLEX may also remove other circulating antibodies, we examined the effects of PLEX on serum immunoglobulin (IgG) and anti-JC virus (JCV) antibody levels in MS patients with and without PML. METHODS: Serum samples from 12 natalizumab-treated patients without PML collected before, during and after PLEX were tested for IgG isotypes using a commercial assay, and for anti-JCV antibodies using a two-step enzyme-linked immunosorbent assay. Five natalizumab-treated PML patients who underwent PLEX were also tested for anti-JCV antibodies. RESULTS: PLEX produced a two- to three-fold reduction in all IgG isotypes. Among patients without PML, 42% (five of 12 patients) had detectable anti-JCV antibodies before PLEX; in these patients, anti-JCV antibodies were reduced approximately two- to five-fold, with levels returning to 50-100 percent of baseline two weeks after the final PLEX. The five PML patients, all of whom had detectable anti-JCV antibodies before PLEX, experienced similar reductions in anti-JCV antibody levels following PLEX. CONCLUSIONS: Our results indicate that PLEX effectively removes circulating antibodies; however, levels of endogenous anti-JCV antibody, unlike exogenously administered natalizumab, were replenished relatively quickly following PLEX. While interpretation of anti-JCV antibody levels during or within two weeks after PLEX may be problematic, humoral JCV immunity is not abolished by PLEX and antibody levels are rapidly restored.

Beta-interferon for multiple sclerosis.

Interferon beta is widely used as first-line treatment for relapsing remitting multiple sclerosis (RRMS). Several products are marketed world-wide, and biosimilar products are emerging. Interferon beta reduces relapse rates by about 1/3, and reduces the appearance of new MRI lesions by about 2/3, and some studies have shown reduced disability progression, and reduced rates of brain atrophy. The mechanism of action of interferon beta in MS is poorly understood, partly due to the complex nature of the biological response to interferon injections. This mini-review succinctly summarizes clinical effects, possible mechanism of action, physiochemical properties of the different interferon products, issues related to immunogenicity, and biomarkers of the interferon beta response, and proposes important unresolved issues for future research.

Anti-JC virus antibodies: implications for PML risk stratification.

OBJECTIVE: A study was undertaken to establish an enzyme-linked immunosorbent assay (ELISA) to detect JC virus (JCV)-specific antibodies in multiple sclerosis (MS) patients, and to evaluate its potential utility for identifying patients at higher or lower risk (ie, risk stratification) of developing progressive multifocal leukoencephalopathy (PML). METHODS: A 2-step assay for detecting and confirming the presence of anti-JCV antibodies in human serum and plasma was developed and demonstrated to be both sensitive and specific. ELISA cutpoints were statistically established using sera from >800 MS patients from natalizumab clinical studies. Subsequently, this assay was used to determine the presence of anti-JCV antibodies in natalizumab-treated PML patients where serum samples were collected 16-180 months prior to the diagnosis of PML. RESULTS: In our evaluation of natalizumab-treated MS patients, 53.6% tested positive for anti-JCV antibodies, with a 95% confidence interval of 49.9 to 57.3%. The false-negative rate of the ELISA was calculated to be approximately 2.5%, with an upper 1-sided confidence limit of 4.4%. Notably, we observed anti-JCV antibodies in all 17 available pre-PML sera samples, which was significantly different from the 53.6% seropositivity observed in the overall MS study population (p < 0.0001). INTERPRETATION: This 2-step assay provides a means to classify MS patients as having detectable or not detectable levels of anti-JCV antibodies. The finding that all 17 of the pre-PML samples that were available tested seropositive, and none tested seronegative, warrants further research on the clinical utility of the anti-JCV antibody assay as a potential tool for stratifying MS patients for higher or lower risk of developing PML.

Assessment of JC virus DNA in blood and urine from natalizumab-treated patients.

OBJECTIVE: Analyses were conducted to determine the clinical utility of measuring JC virus (JCV) DNA in blood or urine of natalizumab-treated multiple sclerosis (MS) patients to predict the risk of progressive multifocal leukoencephalopathy (PML). METHODS: A total of 12,850 blood and urine samples from nearly 1,400 patients participating in natalizumab clinical trials were tested for JCV DNA using a commercially available quantitative polymerase chain reaction (qPCR) assay. A subset of these samples was also tested using a more sensitive qPCR assay developed at the National Institutes of Health (NIH). RESULTS: At the time natalizumab dosing was suspended, JCV DNA was detected in plasma by the commercial assay in 4 of 1,397 (0.3%) patients; the NIH assay confirmed these positive samples and detected JCV DNA in an additional 2 of 205 (1%) patients who tested negative with the commercial assay. None of these 6 JCV DNA positive patients developed PML. In a 48-week study testing the safety of natalizumab redosing, JCV DNA was detected in plasma of 6 of 1,094 (0.3%) patients, none of whom developed PML. Urine at baseline and week 48 was assessed in 224 patients; 58 (26%) were positive at baseline, and 55 (25%) were positive after 48 weeks of natalizumab, treatment. JCV DNA was not detected in peripheral blood mononuclear cells from any of these 1,094 patients before or after natalizumab treatment. In 5 patients who developed PML, JCV DNA was not detected in blood at any time point before symptoms first occurred. INTERPRETATION: Measuring JCV DNA in blood or urine with currently available methods is unlikely to be useful for predicting PML risk in natalizumab-treated MS patients.

Identification of short-term pharmacodynamic effects of interferon-beta-1a in multiple sclerosis subjects with broad- based phenotypic profiling.

We applied broad-based phenotypic profiling to identify pharmacodynamic markers for interferon-beta in multiple sclerosis subjects. A strong pharmacodynamic effect was observed 1.5 (short-term) vs. 6 days post weekly injection. Hundreds of differences were observed at a p-value <0.001. Most major cell populations, including neutrophils, B cells, CD4 T cells and CD8 T cells, decreased in absolute counts at 1.5 days. The striking exception was monocytes, which increased substantially. Changes in multiple monocyte-associated cell surface molecules and monocyte related soluble factors were also observed, including: HLA class II, CCR5, CD38, CD40, CD54, CD64, CD69, CD86, CD101, TLR2, TLR4 and MCP2. These results demonstrate that new hypotheses can be generated from broad molecular and cellular profiling in a clinical setting and provide an approach to identify candidate pharmacodynamic markers to evaluate new drug formulations, dosing and bioequivalence.

JC Polyomavirus Abundance and Distribution in Progressive Multifocal Leukoencephalopathy (PML) Brain Tissue Implicates Myelin Sheath in Intracerebral Dissemination of Infection.

Over half of adults are seropositive for JC polyomavirus (JCV), but rare individuals develop progressive multifocal leukoencephalopathy (PML), a demyelinating JCV infection of the central nervous system. Previously, PML was primarily seen in immunosuppressed patients with AIDS or certain cancers, but it has recently emerged as a drug safety issue through its association with diverse immunomodulatory therapies. To better understand the relationship between the JCV life cycle and PML pathology, we studied autopsy brain tissue from a 70-year-old psoriasis patient on the integrin alpha-L inhibitor efalizumab following a ~2 month clinical course of PML. Sequence analysis of lesional brain tissue identified PML-associated viral mutations in regulatory (non-coding control region) DNA, capsid protein VP1, and the regulatory agnoprotein, as well as 9 novel mutations in capsid protein VP2, indicating rampant viral evolution. Nine samples, including three gross PML lesions and normal-appearing adjacent tissues, were characterized by histopathology and subject to quantitative genomic, proteomic, and molecular localization analyses. We observed a striking correlation between the spatial extent of demyelination, axonal destruction, and dispersion of JCV along white matter myelin sheath. Our observations in this case, as well as in a case of PML-like disease in an immunocompromised rhesus macaque, suggest that long-range spread of polyomavirus and axonal destruction in PML might involve extracellular association between virus and the white matter myelin sheath.