The polyphenol compound resveratrol is reported to have multiple functions, including neuroprotection, and no major adverse effects have been reported. Although the neuroprotective effects have been associated with sirtuin 1 activation by resveratrol, the mechanisms by which resveratrol exerts such functions are a matter of controversy. We examined whether resveratrol can be neuroprotective in two models of multiple sclerosis: experimental autoimmune encephalomyelitis (EAE) and Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD). EAE was induced in C57BL/6 mice, which were fed a control diet or a diet containing resveratrol during either the induction or effector phase or through the whole course of EAE. SJL/J mice were infected with TMEV and fed a control diet or a diet containing resveratrol during the chronic phase of TMEV-IDD. In EAE, all groups of mice treated with resveratrol had more severe clinical signs than the control group. In particular, resveratrol treatment during the induction phase resulted in the most severe EAE, both clinically and histologically. Similarly, in the viral model, the mice treated with resveratrol developed significantly more severe TMEV-IDD than the control group. Thus, surprisingly, the resveratrol treatment significantly exacerbated demyelination and inflammation without neuroprotection in the central nervous system in both models. Our findings indicate that caution should be exercised in potential therapeutic applications of resveratrol in human inflammatory demyelinating diseases, including multiple sclerosis.

In immune-mediated diseases, Treg and proinflammatory Th17 cells have been suggested to play either suppressor (beneficial) or effector (detrimental) roles, respectively. Tissue damage in viral infections can be caused by direct viral replication or immunopathology. Viral replication can be enhanced by anti-inflammatory responses and suppressed by proinflammatory responses. However, Tregs could suppress proinflammatory responses, reducing immunopathology, while Th17 cell-induced inflammation may enhance immunopathology. Here, the roles of Treg and Th17 cells depend on whether tissue damage is caused by direct virus replication or immunopathology, which differ depending on the virus, disease stage and host immune background. Although the precise mechanisms of tissue damage in multiple sclerosis and myocarditis are unclear, both viral replication and immune effector cells have been proposed to cause pathogenesis. Personalized medicine that alters the balance between Treg and Th17 cells may ameliorate viral ...

Alteration of microbiota has been associated with intestinal, inflammatory and neurological diseases. An abundance of “good bacteria,” such as Bifidobacterium, or their products has been generally believed to be beneficial for any diseases, whereas “bad bacteria,” such as pathogenic Helicobacter pylori, are assumed to be always detrimental for hosts. However, this is not the case when we compare and contrast the association of the gut microbiota with two neurological diseases, multiple sclerosis and Alzheimer's disease. After H. pylori infection, pro‐inflammatory T helper (Th)1 and Th17 immune responses are initially induced to eradicate bacteria. However, H. pylori evades the host immune response by inducing Th2 cells and regulatory T cells that produce anti‐inflammatory interleukin‐10. Suppression of anti‐bacterial Th1/Th17 cells by regulatory T cells might enhance gastric H. pylori propagation, followed by a cascade reaction involving vitamin B₁₂ and folic acid malabsorption, plasma homocysteine elevation, and reactive oxygen species induction. This can damage the blood‐brain barrier, leading to accumulation of amyloid‐β in the brain, a hallmark of Alzheimer's disease. In contrast, this suppression of pro‐inflammatory Th1/Th17 responses to H. pylori has protective effects on the hosts, as it prevents uncontrolled gastritis as well as suppresses the induction of encephalitogenic Th1/Th17 cells, which can mediate neuroinflammation in multiple sclerosis. The above scenario might explain why chronic H. pylori infection is positively associated with Alzheimer's disease, whereas it is negatively associated with multiple sclerosis. Finally, we list “10 pitfalls of microbiota studies,” which will be useful for evaluating and designing clinical and experimental microbiota studies.

T helper (Th)2 cells have been proposed to play a neuroprotective role in multiple sclerosis (MS). This is mainly based on “loss-of-function” studies in an animal model for MS, experimental autoimmune encephalomyelitis (EAE), using blocking antibodies against Th2 related cytokines, and knockout mice lacking Th2-related molecules. We tested whether an increase of Th2 responses (“gain-of-function” approach) could alter EAE, the approach of novel GATA binding protein 3 (GATA3)-transgenic (tg) mice that overexpress GATA3, a transcription factor required for Th2 differentiation. In EAE induced with myelin oligodendrocyte glycoprotein (MOG)₃₅₋₅₅ peptide, GATA3-tg mice had a significantly delayed onset of disease and a less severe maximum clinical score, compared with wild-type C57BL/6 mice. Histologically, GATA3-tg mice had decreased levels of meningitis and demyelination in the spinal cord, and anti-inflammatory cytokine profiles immunologically, however both groups developed similar levels of MOG-specific lymphoproliferative responses. During the early stage, we detected higher levels of interleukin (IL)-4 and IL-10, with MOG and mitogen stimulation of regional lymph node cells in GATA3-tg mice. During the late stage, only mitogen stimulation induced higher IL-4 and lower interferon-γ and IL-17 production in GATA3-tg mice. These results suggest that a preexisting bias toward a Th2 immune response may reduce the severity of inflammatory demyelinating diseases, including MS.

Background: Multiple sclerosis (MS) is associated with ectopic lymphoid follicle formation. Podoplanin⁺(lymphatic marker) T helper17 (Th17) cells and B cell aggregates have been implicated in the formation of tertiary lymphoid organs (TLOs) in MS and experimental autoimmune encephalitis (EAE). Since podoplanin expressed by Th17 cells in MS brains is also expressed by lymphatic endothelium, we investigated whether the pathophysiology of MS involves inductions of lymphatic proteins in the inflamed neurovasculature.Methods: We assessed the protein levels of lymphatic vessel endothelial hyaluronan receptor and podoplanin, which are specific to the lymphatic system and prospero-homeobox protein-1, angiopoietin-2, vascular endothelial growth factor-D, vascular endothelial growth factor receptor-3, which are expressed by both lymphatic endothelium and neurons. Levels of these proteins were measured in postmortem brains and sera from MS patients, in the myelin proteolipid protein (PLP)-induced EAE and Theiler’s murine encephalomyelitis virus (TMEV) induced demyelinating disease (TMEV-IDD) mouse models and in cell culture models of inflamed neurovasculature.Results and conclusions: Intense staining for LYVE-1 was found in neurons of a subset of MS patients using immunohistochemical approaches. The lymphatic protein, podoplanin, was highly expressed in perivascular inflammatory lesions indicating signaling cross-talks between inflamed brain vasculature and lymphatic proteins in MS. The profiles of these proteins in MS patient sera discriminated between relapsing remitting MS from secondary progressive MS and normal patients. Thein vivofindings were confirmed in thein vitrocell culture models of neuroinflammation.