Regulatory and pro-inflammatory phenotypes of myelin basic protein-autoreactive T cells in multiple sclerosis

Forskolin improves experimental autoimmune encephalomyelitis in mice probably by inhibiting the calcium and the IL-17-STEAP4 signaling pathway

Multiple sclerosis (MS) is a chronic autoimmune disease in the central nervous system. Forskolin (FSK) is a plant-derived diterpene with excellent immunomodulatory properties and has not been systematically reported for treating MS. This study investigated the therapeutic effects of FSK on cellular and animal MS models and preliminarily explored related mechanisms. The results showed that FSK suppressed the inflammatory response, reduced the expression of STEAP4, and relieved iron deposition in BV-2 cells pretreated by LPS at the cellular level. Meanwhile, at the animal level, FSK treatment halted the progression of experimental autoimmune encephalomyelitis (EAE), alleviated the damage at the lesion sites, reduced the concentration of proinflammatory factors in peripheral blood, and inhibited the immune response of peripheral immune organs in EAE mice. Besides, FSK treatment decreased the expression of STEAP4 in the spinal cord and effectively restored the iron balance in the brain, spinal cord, and serum of EAE mice. Further investigation showed that FSK can reduce IL-17 expression, prevent the differentiation of TH17 cells, and inhibit the calcium signaling pathway. Thus, these results demonstrate that FSK may have the potential to treat MS clinically.

Stroke induces a rapid adaptive autoimmune response to novel neuronal antigens

Stroke affects millions of people worldwide every year. Despite this prevalence, mechanisms of long-term injury and repair within the ischemic brain are still understudied. Sterile inflammation occurs in the injured brain after stroke, with damaged tissue exposing central nervous system (CNS)-derived antigen that could initiate potential autoimmune responses. We used a standard immunology-based recall response assay for murine immune cells, isolated from the cervical lymph nodes and spleen after transient stroke, to determine if stroke induces autoreactivity to CNS target antigens. Our assays included novel neuronal peptides, in addition to myelin-, nuclear-, glial-, and endothelial-derived peptides. Autoimmune responses to an antigen were considered positive based on proliferation and activation over non-stimulated conditions. Stroke induced a significant increase in autoreactive CD4+ and CD8+ T cells, as well as autoreactive CD19+ B cells, as early as 4 days after stroke onset. Mice with large infarct volumes exhibited early T and B cell autoreactivity to NR2A, an NMDA receptor subunit, in cells isolated from lymph nodes but not spleen. Mice with small infarct volumes exhibited high autoreactivity to MAP2, a dendritic cytoskeletal protein, as well as myelin-derived peptides. This autoimmunity was maintained through 10 days post-stroke in both lymph nodes and spleen for all lymphocyte subsets. Sham surgery also induced early autoreactive B cell responses to MAP2 and myelin. Based on these observations, we hypothesize that stroke induces a secondary, complex, and dynamic autoimmune response to neuronal antigens with the potential to potentiate, or perhaps even ameliorate, long-term neuroinflammation.

Adipocytokine profile, cytokine levels and foxp3 expression in multiple sclerosis: a possible link to susceptibility and clinical course of disease

Background

Adipocytokines may be involved in multiple sclerosis (MS) as well as other autoimmune and inflammatory-related diseases. This study aims to compare levels of resistin, visfatin and leptin in three subgroups of MS patients with healthy subjects and also to study their relationship with Foxp3 expression and levels of several pro-inflammatory mediators such as interleukine-1 β(IL-1 β),tumor necrosis factor-α (TNF-α) and human sensitive C-reactive protein (hs-CRP).

Methods

A total of 391 subjects including 200 healthy controls and 191 MS patients were recruited for this case-control study. Circulating adipocytokines and inflammatory mediators were measured using immunoassay methods. Foxp3 gene expression in peripheral blood mononuclear cells (PBMC) was determined by quantitative real-time PCR. Fat tissue mass was evaluated by using dual energy X-ray absorptiometery (DEXA).

Results

A significant difference was observed in levels of inflammatory mediators, adipocytokines, Foxp3 gene expression and adipose tissue mass between MS patients and healthy controls. All adipocytokines were positively correlated with levels of inflammatory mediators and negatively correlated with Foxp3 expression in MS patients. In controls, there were positive correlations between circulating leptin and resistin with TNF-α and IL-1β in subgroup analysis, the highest levels of TNF-α, IL-1β, hs-CRP, resistin and leptin were observed in primary progressive-MS (PP-MS) patients. Also, expression of Foxp3 and levels of visfatin in relapsing remitting-MS(RR-MS) patients were higher compared with the other subgroups.

Conclusions

Our findings suggest the potential role of adipocytokines in pathogenesis and severity of MS. Notably, the relationship of adipocytokines levels with inflammatory cytokines as well as clinical features of MS could be considerable in translational medicine and biomarker studies.

Th17 cell, the new player of neuroinflammatory process in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease characterized by recurrent episodes of demyelination and axonal lesion mediated by CD4(+) T cells with a proinflammatory Th1 and Th17 phenotype, macrophages, and soluble inflammatory mediators. Identification of Th17 cells led to breaking the dichotomy of Th1/Th2 axis in immunopathogenesis of autoimmune diseases such as MS, and its experimental model, experimental autoimmune encephalomyelitis (EAE). Th17 cells are characterized by expression of retinoic acid-related orphan receptor (ROR)γt and signal transducer and activator of transcription 3 (STAT3) factors. Th17-produced cytokine profile including interleukin (IL)-17, IL-6, IL-21, IL-22, IL-23 and tumour necrosis factor (TNF)-α, which have proinflammatory functions, suggests it as an important factor in immunopathogenesis of MS, because the main feature of MS pathophysiology is the neuroinflammatory reaction. The blood brain barrier (BBB) disruption is an early and central event in MS pathogenesis. Autoreactive Th17 cells can migrate through the BBB by the production of cytokines such as IL-17 and IL-22, which disrupt tight junction proteins in the central nervous system (CNS) endothelial cells. Consistent with this observation and regarding the wide range production of proinflammatory cytokines and chemokines by Th17 cells, it is expected that Th17 cell to be as a potent pathogenic factor in disease immunopathophysiology. Th17-mediated inflammation is characterized by neutrophil recruitment into the CNS and neurons killing. However, the majority of our knowledge about the role of Th17 in MS pathogenesis is resulted in investigation into EAE animal models. In this review, we intend to focus on the newest information regarding the precise role of Th17 cells in immunopathogenesis of MS, and its animal model, EAE.

IL-21 and IL-21 receptor expression in lymphocytes and neurons in multiple sclerosis brain

IL-17–producing CD4⁺ T cells (Th-17) contribute to the pathogenesis of experimental autoimmune encephalomyelitis and are associated with active disease in multiple sclerosis (MS). In addition to IL-17, Th-17 cells can also express IL-21, IL-22, and IL-6 under Th-17–polarizing conditions (IL-6 and transforming growth factor-β). In this study we investigated IL-21 and IL-21 receptor (IL-21R) expression in MS lesions by in situ hybridization and immunohistochemistry. We detected strongly IL-21⁺ infiltrating cells predominantly in acute but also in chronic active white matter MS lesions in which IL-21 expression was restricted to CD4⁺ cells. In contrast, IL-21R was much more broadly distributed on CD4⁺, CD19⁺, and CD8⁺ lymphocytes but not major histocompatibility complex class-II⁺ macrophages/microglia. Interestingly, in cortical areas we detected both IL-21 and IL-21R expression by neurons. These findings suggest role(s) for IL-21 in both the acute and chronic stages of MS via direct effects on T and B lymphocytes and, demonstrated for the first time, also on neurons.