LPA1 signaling drives Schwann cell dedifferentiation in experimental autoimmune neuritis

Background Lysophosphatidic acid (LPA) is a pleiotropic lipid messenger that addresses at least six specific G-protein coupled receptors. Accumulating evidence indicates a significant involvement of LPA in immune cell regulation as well as Schwann cell physiology, with potential relevance for the pathophysiology of peripheral neuroinflammation. However, the role of LPA signaling in inflammatory neuropathies has remained completely undefined. Given the broad expression of LPA receptors on both Schwann cells and cells of the innate and adaptive immune system, we hypothesized that inhibition of LPA signaling may ameliorate the course of disease in experimental autoimmune neuritis (EAN). Methods We induced active EAN by inoculation of myelin protein 2 peptide (P255–78) in female Lewis rats. Animals received the orally available LPA receptor antagonist AM095, specifically targeting the LPA1 receptor subtype. AM095 was administered daily via oral gavage in a therapeutic regimen from 10 until 28 days post-immunization (dpi). Analyses were based on clinical testing, hemogram profiles, immunohistochemistry and morphometric assessment of myelination. Results Lewis rats treated with AM095 displayed a significant improvement in clinical scores, most notably during the remission phase. Cellular infiltration of sciatic nerve was only discretely affected by AM095. Hemogram profiles indicated no impact on circulating leukocytes. However, sciatic nerve immunohistochemistry revealed a reduction in the number of Schwann cells expressing the dedifferentiation marker Sox2 paralleled by a corresponding increase in differentiating Sox10-positive Schwann cells. In line with this, morphometric analysis of sciatic nerve semi-thin sections identified a significant increase in large-caliber myelinated axons at 28 dpi. Myelin thickness was unaffected by AM095. Conclusion Thus, LPA1 signaling may present a novel therapeutic target for the treatment of inflammatory neuropathies, potentially affecting regenerative responses in the peripheral nerve by modulating Schwann cell differentiation.

Effect of 1.25(OH)2D3 on experimental autoimmune neuritis and its mechanism

Objective: To study the potential therapeutic effects of active vitamin D3 (1.25(OH)2D3) in the experimental autoimmune neuritis (EAN). Methods: The EAN model was established by actively immunizing Lewis rats with synthetic P0180–199 pepide and Freund’s complete adjuvant. 1.25(OH)2D3 treatment was given, weight change of rats and clinical score were analyzed. HE staining was used to detect the inflammatory cell infiltration of sciatic nerves and demyelination of sciatic nerves was observed by transmission electron microscope (TEM) at the same time. The expressions of inflammatory cytokines IL-17, IL-10, TGF-β, IFN-γ were detected by ELISA, and the expressions of Th17, Treg were examined by RT-PCR. Results: 1.25(OH)2D3 ameliorated body weight loss and myelin lesions. It decreased expressions of inflammatory cytokines IL-17, IFN-γ and RORrt while those of IL-10, TGF-β and FoxP3 were increased. Conclusions: 1.25(OH)2D3 can improve the clinical pathological changes of EAN rats, and the mechanism may be related to the changes of inflammatory cytokines. 1.25(OH)2D3 is expected to become a new strategy for the clinical treatment of GBS/EAN.

NF-κB inhibitor suppresses experimental autoimmune neuritis in mice via declining macrophages polarization to M1 type

Guillain–Barre’ syndrome (GBS) is an acute inflammatory and immune-mediated demyelinating disease of peripheral nervous system (PNS). Macrophages playing a central role in its animal model, experimental autoimmune neuritis (EAN) has been well-accepted. Additionally, NF-κB inhibitors has been used to treat cancers and showed beneficial effects. Here we investigated the therapeutic effect of M2 macrophage and NF-κB pathway is correlated with macrophages activation in experimental autoimmune neuritis (EAN) in C57BL/6 mice. We demonstrated that M2 macrophage transfusion can alleviate the clinical symptoms of EAN by reducing the proportion of M1 macrophage in the peak period, inhibiting the phosphorylation of NF-κB p65. The NF-κB inhibitor (BAY-11-7082) could alleviate the clinical symptoms of EAN and shorten the duration of symptoms by reducing the proportion of M1 macrophages and the expression of pro-inflammatory cytokines. Consequently, BAY-11-7082 exhibits strong potential as a therapeutic strategy for ameliorating EAN by influencing the balance of M1/M2 macrophages and inflammatory cytokines.

Celastrol ameliorates experimental autoimmune neuritis by shifting the polarization of M1/M2 macrophages via the hypoxic response pathway

BackgroundGBS is an autoimmune disease characterized by inflammatory infiltration and demyelination of peripheral nerves. Macrophage polarization is involved in different stages of GBS. Altering the polarization of macrophages may be an effective therapeutic strategy for GBS. Celastrol was previously shown to contribute to anti-neuroinflammation. However, the mechanism underlying the effect of celastrol in GBS animal model experimental autoimmune neuritis (EAN) is unclear. We hypothesized that celastrol may shift the polarization of macrophages through the NRF /HIF-1αpathway.MethodsClinical scores, weight and histological changes were assessed to investigate the effects of celastrol on EAN. To detect the polarization state of macrophages, flow cytometry and immunofluorescence staining were applied. Inflammation cytokines were evaluated by ELISA. The expression of NRF2 and HIF-1α were detected by western-blot and immunofluorescence staining.ResultsCelastrol treatment significantly ameliorates the severity and neuroinflammation of EAN. The polarization state of macrophages from M1 to M2 was observed upon celastrol application. Consistently, pro-inflammatory cytokines were decreased, whereas anti-inflammatory cytokines were increased upon celastrol treatment. Furthermore, we found that celastrol treatment may increase expression of Nrf2 and decrease the expression of HIF-1α. ConclusionTaken together, these data demonstrate that celastrol may ameliorate the severity and neuroinflammation of EAN via promoting the polarization state of macrophages into M2, likely by modulating the hypoxic response. Celastrol may therefore serve as a novel therapeutic agent for GBS.