Jeri-Anne Lyons

B cells are critical to induction of experimental allergic encephalomyelitis by protein but not by a short encephalitogenic peptide.

While the pathology of multiple sclerosis implicates a role for B cells and antibodies in the disease process, results from animal models have yielded conflicting results. To further characterize the role of B cells in experimental allergic encephalomyelitis (EAE), wild‐type and B cell‐deficient C57BL / 6 mice were immunized with either a recombinant form of myelin oligodendrocyte glycoprotein (MOG) or with the encephalitogenic MOG(35 – 55) peptide. B cell‐deficient mice did not develop EAE when immunized with MOG, although they were susceptible to MOG(35 – 55)‐induced disease. In contrast, wild‐type mice were fully susceptible to both MOG and MOG(35 – 55)‐induced EAE. B cell‐deficient mice immunized with MOG were primed to the encephalitogenic MOG(35 – 55) epitope, as their spleen cells responded with Th1 cytokine production in a fashion similar to WT cells when challenged in vitro with MOG protein or MOG(35 – 55) peptide. These results demonstrate that the form of inducing antigen (protein vs. peptide) plays a role in the pathogenesis of EAE and may be relevant when applying results from the EAE model to multiple sclerosis.

B cells and antibodies in CNS demyelinating disease

There is much evidence to implicate B cells, plasma cells, and their products in the pathogenesis of MS. Despite unequivocal evidence that the animal model for MS, EAE, is initiated by myelin-specific T cells, there is accumulating evidence of a role for B cells, plasma cells, and their products in EAE pathogenesis. The role(s) played by B cells, plasma cells, and antibodies in CNS inflammatory demyelinating diseases are likely to be multifactorial and complex, involving distinct and perhaps opposing roles for B cells versus antibody.

Critical role of antigen-specific antibody in experimental autoimmune encephalomyelitis induced by recombinant myelin oligodendrocyte glycoprotein.

The role of B cells and antibody in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) remains controversial. We previously demonstrated that B cells are required for EAE to be induced by the 120‐amino acid extracellular domain of myelin oligodendrocyte glycoprotein (MOG). In the present study, the role of B cells in MOG‐induced EAE was further characterized. Passive transfer of activated B cells or serum from MOG‐primed wild‐type (WT) mice was found to reconstitute the ability for clinical and histological EAE to be induced in MOG‐immunized B cell‐deficient mice. MOG‐induced EAE did not occur with transfer of B cells that had been nonspecifically activated by lipopolysaccharide or isolated from naïve or myelin basic protein (MBP)‐primed WT mice. Likewise, MOG‐primed serum, but not naive serum or serum from MBP‐, Hen egg lysozyme‐, or MOG35–55‐primed mice, led to EAE in B cell–/– animals. While both MOG‐primed B cells and serum reconstituted the ability for disease induction, MOG‐primed serum was much more efficient, leading to clinical and histological EAE similar to that seen in the WT. Injection of MOG serum into healthy B cell–/ mice 30 days after MOG immunization led to rapid appearance of clinical signs and CNS inflammation, indicating that an antigen‐specific factor is necessary for initiation of CNS inflammation,and not just demyelination. These data strongly suggest that MOG‐specific antibody is critical to the initiation of MOG‐induced murine EAE.

Rituximab add-on therapy for breakthrough relapsing multiple sclerosis: A 52-week phase II trial

Objective: B cells and the humoral immune system have been implicated in the pathogenesis of multiple sclerosis (MS). This study sought to evaluate the efficacy, safety, and tolerability of add-on therapy with rituximab, a monoclonal antibody that depletes circulating B cells, in subjects with relapsing MS with breakthrough disease defined by clinical and MRI activity (Class III evidence). Methods: Thirty subjects with a relapse within the past 18 months despite use of an injectable disease-modifying agent, and with at least 1 gadolinium-enhancing (GdE) lesion on any of 3 pretreatment MRIs, received rituximab administered at 375 mg/m2 weekly × 4 doses. Three monthly posttreatment brain MRI scans were obtained beginning 12 weeks after the first infusion. Multiple Sclerosis Functional Composite (MSFC) and Expanded Disability Status Scale (EDSS) were obtained at baseline and throughout the posttreatment follow-up. Results: GdE lesions were reduced after treatment with rituximab, with 74% of posttreatment MRI scans being free of GdE activity compared with 26% free of GdE activity at baseline (p < 0.0001). Median GdE lesions were reduced from 1.0 to 0, and mean number was reduced from 2.81 per month to 0.33 after treatment (88% reduction). MSFC improved as well (p = 0.02). EDSS remained stable. Conclusion: Rituximab add-on therapy was effective based upon blinded radiologic endpoints in this phase II study. In combination with standard injectable therapies, rituximab was well-tolerated with no serious adverse events. B-cell–modulating therapy remains a potential option for treatment of patients with relapsing MS with an inadequate response to standard injectable therapies. Classification of evidence: This study provides Class III evidence that add-on rituximab reduces gadolinium-enhancing brain lesions in multiple sclerosis.

Rituximab Therapy Reduces Organ-Specific T Cell Responses and Ameliorates Experimental Autoimmune Encephalomyelitis

Recent clinical trials have established B cell depletion by the anti-CD20 chimeric antibody Rituximab as a beneficial therapy for patients with relapsing-remitting multiple sclerosis (MS). The impact of Rituximab on T cell responses remains largely unexplored. In the experimental autoimmune encephalomyelitis (EAE) model of MS in mice that express human CD20, Rituximab administration rapidly depleted peripheral B cells and strongly reduced EAE severity. B cell depletion was also associated with diminished Delayed Type Hypersensitivity (DTH) and a reduction in T cell proliferation and IL-17 production during recall immune response experiments. While Rituximab is not considered a broad immunosuppressant, our results indicate a role for B cells as a therapeutic cellular target in regulating encephalitogenic T cell responses in specific tissues.

Amelioration of Experimental Autoimmune Encephalomyelitis in C57BL/6 Mice by Photobiomodulation Induced by 670 nm Light

Background The approved immunomodulatory agents for the treatment of multiple sclerosis (MS) are only partially effective. It is thought that the combination of immunomodulatory and neuroprotective strategies is necessary to prevent or reverse disease progression. Irradiation with far red/near infrared light, termed photobiomodulation, is a therapeutic approach for inflammatory and neurodegenerative diseases. Data suggests that near-infrared light functions through neuroprotective and anti-inflammatory mechanisms. We sought to investigate the clinical effect of photobiomodulation in the Experimental Autoimmune Encephalomyelitis (EAE) model of multiple sclerosis. Methodology/Principal Findings The clinical effect of photobiomodulation induced by 670 nm light was investigated in the C57BL/6 mouse model of EAE. Disease was induced with myelin oligodendrocyte glycoprotein (MOG) according to standard laboratory protocol. Mice received 670 nm light or no light treatment (sham) administered as suppression and treatment protocols. 670 nm light reduced disease severity with both protocols compared to sham treated mice. Disease amelioration was associated with down-regulation of proinflammatory cytokines (interferon-γ, tumor necrosis factor-α) and up-regulation of anti-inflammatory cytokines (IL-4, IL-10) in vitro and in vivo. Conclusion/Significance These studies document the therapeutic potential of photobiomodulation with 670 nm light in the EAE model, in part through modulation of the immune response.

The heat shock response reduces myelin oligodendrocyte glycoprotein‐induced experimental autoimmune encephalomyelitis in mice

The stress response (SR) can block inflammatory gene expression by preventing activation of transcription factor nuclear factor‐kappa B (NF‐κB). As inflammatory gene expression contributes to the pathogenesis of demyelinating diseases, we tested the effects of the SR on the progression of the demyelinating disease experimental autoimmune encephalomyelitis (EAE). EAE was actively induced in C57BL/6 mice using an encephalitogenic myelin oligodendrocyte glycoprotein (MOG35−55) peptide. Whole body hyperthermia was used to induce a heat shock response (HSR) in immunized mice 2 days after the booster MOG35−55 peptide injection. The HSR reduced the incidence of EAE by 70%, delayed disease onset by 6 days, and attenuated disease severity. The HSR attenuated leukocyte infiltration into CNS assessed by quantitation of perivascular infiltrates, and by reduced staining for CD4 and CD25 immunopositive T‐cells. T‐cell activation, assessed by the production of interferon γ (IFNγ) in response to MOG35−55, was also decreased by the HSR. The HSR reduced inflammatory gene expression in the brain that normally occurs during EAE, including the early increase in RANTES (regulated on activation of normal T‐cell expressed and secreted) expression, and the later expression of the inducible form of nitric oxide synthase. The early activation of transcription factor NF‐κB was also blocked by the HSR. The finding that the SR reduces inflammation in the brain and the clinical severity of EAE opens a novel therapeutic approach for prevention of autoimmune diseases.

Elevated Intrathecal Myelin Oligodendrocyte Glycoprotein Antibodies in Multiple Sclerosis

OBJECTIVE To evaluate antibodies to myelin oligodendrocyte glycoprotein (MOG) in the serum and cerebrospinal fluid (CSF) of patients with multiple sclerosis (MS) and control individuals. DESIGN Prospective case-control series. SETTING Academic referral center. PATIENTS Twenty-six controls with noninflammatory neurologic disease and 35 patients with MS donated serum and CSF for recombinant MOG (rMOG) antibody determination. MAIN OUTCOME MEASURES Serum and CSF rMOG antibody and albumin levels were used to calculate an rMOG index. Clinical disability, CSF markers, and magnetic resonance metrics were correlated with the rMOG index. RESULTS The rMOG index was elevated in MS patients compared with controls (P = .01). Patients with progressive MS exhibited elevated rMOG indexes compared with patients with relapsing-remitting MS (P = .04). The rMOG index was inferior to the IgG index in differentiating MS patients from controls. However, 7 of 16 patients with MS who had normal immunoglobulin G indexes had an elevated rMOG index. The rMOG index did not correlate with clinical disability, other CSF markers, or radiographic outcome measures. CONCLUSIONS The rMOG index, a marker of intrathecal MOG antibody production, may provide complementary information to routine CSF testing in the diagnosis of MS. Furthermore, intrathecal anti-MOG antibody production may be more pronounced in progressive than in relapsing forms of MS.

Myostatin Expression, Lymphocyte Population, and Potential Cytokine Production Correlate with Predisposition to High-Fat Diet Induced Obesity in Mice

A strong relationship exists between increased inflammatory cytokines and muscle insulin resistance in obesity. This study focused on identifying a relationship between metabolic propensity and myostatin expression in muscle and spleen cells in response to high-fat diet intake. Using a comparative approach, we analyzed the effects of high-fat diet intake on myostatin and follistatin expression, spleen cell composition, and potential cytokine expression in high-fat diet induced obesity (HFDIO) resistant (SWR/J) and susceptible (C57BL/6) mice models. Results demonstrated overall increased myostatin expression in muscle following high-fat diet intake in HFDIO-susceptible mice, while myostatin expression levels decreased initially in muscle from high-fat diet fed resistant mice. In HFDIO-resistant mice, myostatin expression decreased in spleen, while myostatin increased in spleen tissue from HFDIO-susceptible mice. Proinflammatory cytokine (IL-17, IL-1β, and IFNγ) potential increased in splenocytes from HFDIO-susceptible mice. In comparison, C57BL/6 mice fed a high-fat diet exhibited higher frequencies of CD4+/CD44hi and CD8+/CD44hi cells in the spleen compared to control fed mice. Together, these results suggest that susceptibility to high-fat diet induced obesity could be influenced by local myostatin activity in a tissue-specific manner and that splenocytes exhibit differential cytokine production in a strain-dependent manner. This study sets the stage for future investigations into the interactions between growth, inflammation, and metabolism.

B cells limit epitope spreading and reduce severity of EAE induced with PLP peptide in BALB/c mice

The role of B cells and antibody in experimental autoimmune encephalomyelitis (EAE) appears to differ based on the identity and state (protein vs. encephalitogenic peptide) of the inducing antigen and the strain of mouse utilized. The involvement of B cells in the induction of EAE by peptides of proteolipid protein (PLP) in BALB/c mice was investigated. Wild-type and B cell-deficient (B cell-/-) mice on the BALB/c background were immunized with overlapping PLP peptides, and the disease course was followed. Although incidence and onset of PLP(180-199)-induced EAE was similar in WT and B cell-/- mice, the clinical course was more severe in B cell-/- mice. During acute disease, proliferation and interferon-gamma production by lymphoid cells from both strains were similar and were elicited predominantly in response to the immunizing antigen. However, during chronic disease lymphoid cells isolated from B cell-/- mice proliferated to a greater extent and produced more interferon-gamma in response to the overlapping peptide PLP185-206 and to the smaller internal peptide PLP185-199 than did WT mice. These data suggest that B cells regulate PLP-induced EAE in BALB/c mice through control of epitope spreading.