Kinesin-5 inhibition improves neural regeneration in experimental autoimmune neuritis.

BACKGROUND: Autoimmune neuropathies can result in long-term disability and incomplete recovery, despite adequate first-line therapy. Kinesin-5 inhibition was shown to accelerate neurite outgrowth in different preclinical studies. Here, we evaluated the potential neuro-regenerative effects of the small molecule kinesin-5 inhibitor monastrol in a rodent model of acute autoimmune neuropathies, experimental autoimmune neuritis. METHODS: Experimental autoimmune neuritis was induced in Lewis rats with the neurogenic P2-peptide. At the beginning of the recovery phase at day 18, the animals were treated with 1 mg/kg monastrol or sham and observed until day 30 post-immunisation. Electrophysiological and histological analysis for markers of inflammation and remyelination of the sciatic nerve were performed. Neuromuscular junctions of the tibialis anterior muscles were analysed for reinnervation. We further treated human induced pluripotent stem cells-derived secondary motor neurons with monastrol in different concentrations and performed a neurite outgrowth assay. RESULTS: Treatment with monastrol enhanced functional and histological recovery in experimental autoimmune neuritis. Motor nerve conduction velocity at day 30 in the treated animals was comparable to pre-neuritis values. Monastrol-treated animals showed partially reinnervated or intact neuromuscular junctions. A significant and dose-dependent accelerated neurite outgrowth was observed after kinesin-5 inhibition as a possible mode of action. CONCLUSION: Pharmacological kinesin-5 inhibition improves the functional outcome in experimental autoimmune neuritis through accelerated motor neurite outgrowth and histological recovery. This approach could be of interest to improve the outcome of autoimmune neuropathy patients.

[Expression of glycolytic genes in immune cells and changes of related immune cells in experimental autoimmune neuritis].

Objective: To investigate the expression of glycolytic genes in immune cells and the changes of related immune cells in experimental autoimmune neuritis (EAN), and deepen the understanding of pathogenesis of EAN. Methods: Twenty-four male C57BL/6 mice (6-8 weeks old, 18-20 g) were divided into four groups according to the random number table method: control group (P0180-199 was replaced by PBS during modeling and mice were sacrificed on the 16th day), EAN mice were sacrificed on the 8th day after the end of modeling (EAN 8 d), EAN mice were sacrificed on the 16th day after the end of modeling (EAN 16 d), and EAN mice received drug intervention and were sacrificed on the 16th day after the end of modeling (2-DG was intraperitoneally injected since the day of the first immunization, 550 mg/kg; EAN 16 d+2-DG), with 6 rats in each group. The clinical symptoms and clinical scores were observed and recorded daily. At the end of the experiment, the mice were sacrificed under chloral hydrate anesthesia, and the serum, spleen, sciatic nerve and other tissues of each group were collected. The degree of inflammatory cell infiltration and demyelination of sciatic nerve were observed by hematoxylin and eosin (HE) staining and luxol fast blue (LFB) staining. Flow cytometry was used to detect the proportion of M1 macrophages, Th17 cells and Tregs cells. The mRNA expression levels of glycolysis-related genes (mTORC1, HIF1α, GLUT1 and LDHA) were detected by RT-PCR. Western blotting was used to detect the level of pan-lysine lactate in macrophages and sciatic nerve tissue. Results: The expression of glycolysis-related genes (mTORC1, HIF1α, GLUT1 and LDHA) in spleen M1 macrophages and sciatic nerve was significantly up-regulated in EAN 16 d group, compared with control, EAN 8 d and EAN 16 d+2-DG groups (all P<0.05). The relative pan-lysine lactate (pankla) expression level of spleen M1 macrophages (1.25±0.02) and sciatic nerve tissue (1.23±0.26) significantly increased in EAN 16 d group, compared with control, EAN 8 d and EAN 16 d+2-DG groups (M1 macrophages: 0.12±0.10, 1.07±0.12 and 0.42±0.07; sciatic nerve: 0.10±0.12, 0.87±0.20 and 0.36±0.05) (all P<0.05). The expression of glycolytic genes in splenic CD4+T cells showed an increasing trend, but there were no statistically significant differences among the groups, and the expression of glycolytic genes did not decrease significantly after 2-DG treatment (all P>0.05). The proportion of spleen M1 macrophages in the control group, EAN 8 d group, EAN 16 d group and EAN 16 d+2-DG group was 4.28±0.13, 7.54±0.25, 13.16±0.33 and 4.13±0.38 respectively, which was significantly higher in the EAN 16 d group (all P<0.05). The proportion of spleen Th17 cells in the four groups was 3.78±0.03, 8.24±0.55, 12.30±1.34 and 4.83±0.01, respectively, which was significantly higher in the EAN 16 d group (all P<0.05). The proportion of spleen Tregs cells in the four groups was 10.01±1.05, 7.54±0.70, 3.82±0.47 and 8.22±1.21, respectively, which was significantly lower in the EAN 16 d group (all P<0.05). Conclusions: The expression of glycolytic genes in splenic macrophages significantly increases during EAN, but not in CD4+T cells. The proportion of M1 macrophages and Th17 cells in spleen gradually increases, while the proportion of Tregs cells gradually decreases.

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.

Nuclear factor kappa B inhibitor suppresses experimental autoimmune neuritis in mice via declining macrophages polarization to M1 type.

Guillain-Barré syndrome (GBS) is an acute inflammatory and immune-mediated demyelinating disease of the peripheral nervous system (PNS). Macrophages play a central role in its animal model, experimental autoimmune neuritis (EAN), which has been well accepted. Additionally, nuclear factor (NF)-κB inhibitors have been used to treat cancers and have shown beneficial effects. Here, we investigated the therapeutic effect of M2 macrophage and the NF-κB pathway's correlation with macrophage activation in EAN in C57BL/6 mice. We demonstrate that M2 macrophage transfusion could 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 proinflammatory 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.

Intrathecal triamcinolone acetonide exerts anti-inflammatory effects on Lewis rat experimental autoimmune neuritis and direct anti-oxidative effects on Schwann cells.

BACKGROUND: Corticosteroids dominate in the treatment of chronic autoimmune neuropathies although long-term use is characterized by devastating side effects. METHODS: We introduce the intrathecal application of the synthetic steroid triamcinolone (TRIAM) as a novel therapeutic option in experimental autoimmune neuritis in Lewis rats RESULTS: After immunization with neuritogenic P2 peptide, we show a dose-dependent therapeutic effect of one intrathecal injection of 0.3 or 0.6 mg/kg TRIAM on clinical and electrophysiological parameters of neuritis with a lower degree of inflammatory infiltrates (T cells and macrophages) and demyelination in the sciatic nerve. In vitro studies in Schwann cell cultures showed an increased expression of IL-1 receptor antagonist and reduced expression of Toll-like receptor 4 after incubation with TRIAM as well as a protective effect of TRIAM against oxidative stress after H2O2 exposure. CONCLUSION: Intrathecal TRIAM application could be a novel immunomodulatory and potentially neuroprotective option for autoimmune neuropathies with a direct effect on Schwann cells.

Enhanced glycolysis contributes to the pathogenesis of experimental autoimmune neuritis.

BACKGROUND: With the recognition of the key roles of cellular metabolism in immunity, targeting metabolic pathway becomes a new strategy for autoimmune disease treatment. Guillain-Barré syndrome (GBS) is an acute immune-mediated inflammatory demyelinating disease of the peripheral nervous system, characterized by inflammatory cell infiltration. These inflammatory cells, including activated macrophages, Th1 cells, and Th17 cells, generally undergo metabolic reprogramming and rely mainly on glycolysis to exert functions. This study aimed to explore whether enhanced glycolysis contributed to the pathogenesis of experimental autoimmune neuritis (EAN), a classic model of GBS. METHODS: Preventive and therapeutic treatments with glycolysis inhibitor, 2-deoxy-D-glucose (2-DG), were applied to EAN rats. The effects of treatments were determined by clinical scoring, weighting, and tissue examination. Flow cytometry and ELISA were used to evaluate T cell differentiation, autoantibody level, and macrophage functions in vivo and in vitro. RESULTS: Glycolysis inhibition with 2-DG not only inhibited the initiation, but also prevented the progression of EAN, evidenced by the improved clinical scores, weight loss, inflammatory cell infiltration, and demyelination of sciatic nerves. 2-DG inhibited the differentiation of Th1, Th17, and Tfh cells but enhanced Treg cell development, accompanied with reduced autoantibody secretion. Further experiments in vitro proved glycolysis inhibition decreased the nitric oxide production and phagocytosis of macrophages and suppressed the maturation of dendritic cells (DC). CONCLUSION: The effects of glycolysis inhibition on both innate and adaptive immune responses and the alleviation of animal clinical symptoms indicated that enhanced glycolysis contributed to the pathogenesis of EAN. Glycolysis inhibition may be a new therapy for GBS.

Class I PI3K inhibitor ZSTK474 attenuates experimental autoimmune neuritis by decreasing the frequency of Th1/Th17 cells and reducing the production of proinflammatory cytokines.

The Class I phosphatidylinositol 3-kinase inhibitor, 2-(2-difluoromethy lbenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine (ZSTK474), has anti-inflammatory and immunoregulatory properties. However, whether it can be used to treat Guillain-Barré syndrome (GBS)-a neuroinflammatory disorder-is unknown. We induced experimental autoimmune neuritis (EAN) in Lewis rats, an established model of GBS. Orally administered ZSTK474 decreased neurological deficits in the GBS model, as demonstrated by diminished inflammatory cell infiltration, and ameliorated demyelination of sciatic nerves. Additionally, ZSTK474 decreased the number of Th1/Th17 cells and levels of the proinflammatory cytokines interleukin (IL)-1α, IL-1ß, IL-17, IL-23, interferon-γ, and tumor necrosis factor-α. We propose that the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin complex 1 (PI3K/AKT/mTORC1) pathway likely contributed to the neuroprotective effect of ZSTK474. ZSTK474 effectively decreases the frequency of Th1/Th17 cells, thereby reducing the production of proinflammatory cytokines and successfully alleviating the symptoms of EAN. Thus, the neuroprotective effect of ZSTK474 indicates its potential utility as anti-inflammatory therapy for GBS.

PR-957, a selective inhibitor of immunoproteasome subunit low-MW polypeptide 7, attenuates experimental autoimmune neuritis by suppressing Th17-cell differentiation and regulating cytokine production.

Experimental autoimmune neuritis (EAN) is a CD4+ T-cell-mediated autoimmune inflammatory demyelinating disease of the peripheral nervous system. It has been replicated in an animal model of human inflammatory demyelinating polyradiculoneuropathy, Guillain-Barré syndrome. In this study, we evaluated the therapeutic efficacy of a selective inhibitor of the immunoproteasome subunit, low-MW polypeptide 7 (PR-957) in rats with EAN. Our results showed that PR-957 significantly delayed onset day, reduced severity and shortened duration of EAN, and alleviated demyelination and inflammatory infiltration in sciatic nerves. In addition to significantly regulating expression of the cytokine profile, PR-957 treatment down-regulated the proportion of proinflammatory T-helper (Th)17 cells in sciatic nerves and spleens of rats with EAN. Data presented show the role of PR-957 in the signal transducer and activator of transcription 3 (STAT3) pathway. PR-957 not only decreased expression of IL-6 and IL-23 but also led to down-regulation of STAT3 phosphorylation in CD4+ T cells. Regulation of the STAT3 pathway led to a reduction in retinoid-related orphan nuclear receptor γ t and IL-17 production. Furthermore, reduction of STAT3 phosphorylation may have directly suppressed Th17-cell differentiation. Therefore, our study demonstrates that PR-957 could potently alleviate inflammation in rats with EAN and that it may be a likely candidate for treating Guillain-Barré syndrome.-Liu, H., Wan, C., Ding, Y., Han, R., He, Y., Xiao, J., Hao, J. PR-957, a selective inhibitor of immunoproteasome subunit low-MW polypeptide 7, attenuates experimental autoimmune neuritis by suppressing Th17-cell differentiation and regulating cytokine production.

Resolvin D1 Programs Inflammation Resolution by Increasing TGF-ß Expression Induced by Dying Cell Clearance in Experimental Autoimmune Neuritis.

UNLABELLED: Experimental autoimmune neuritis (EAN) is the animal model of human acute inflammatory demyelinating polyradiculoneuropathies (AIDP), an auto-immune inflammatory demyelination disease of the peripheral nervous system (PNS) and the world's leading cause of acute autoimmune neuromuscular paralysis. EAN and AIDP are characterized by self-limitation with spontaneous recovery; however, endogenous pathways that regulate inflammation resolution in EAN and AIDP remain elusive. A pathway of endogenous mediators, especially resolvins and clearance of apoptotic cells, may be involved. Here, we determined that resolvin D1 (RvD1), its synthetic enzyme, and its receptor were greatly increased in PNS during the recovery stage of EAN. Both endogenous and exogenous RvD1 increased regulatory T (Treg) cell and anti-inflammatory macrophage counts in PNS, enhanced inflammation resolution, and promoted disease recovery in EAN rats. Moreover, RvD1 upregulated the transforming growth factor-ß (TGF-ß) level and pharmacologic inhibition of TGF-ß signaling suppressed RvD1-induced Treg cell counts, but not anti-inflammatory macrophage counts, and RvD1-improved inflammation resolution and disease recovery in EAN rats. Mechanistically, the RvD1-enhanced macrophage phagocytosis of apoptotic T cells leading to reduced apoptotic T-cell accumulation in PNS induced TGF-ß production and caused Treg cells to promote inflammation resolution and disease recovery in EAN. Therefore, these data highlight the crucial role of RvD1 as an important pro-resolving molecule in EAN and suggest its potential as a therapeutic target in human neuropathies. SIGNIFICANCE STATEMENT: Experimental autoimmune neuritis (EAN) is the animal model of human acute inflammatory demyelinating polyradiculoneuropathies, an auto-immune inflammatory demyelination disease of the peripheral nervous system (PNS) and the world's leading cause of acute autoimmune neuromuscular paralysis. Here, we demonstrated that resolvin D1 (RvD1) promoted macrophage phagocytosis of apoptotic T cells in PNS, thereby upregulating transforming growth factor-ß by macrophages, increased local Treg cell counts, and finally promoted inflammation resolution and disease recovery in EAN. These data highlight the crucial role of RvD1 as an important pro-resolving molecule in EAN and suggest that it has potential as a therapeutic target in human neuritis.

Schwann cell dedifferentiation-associated demyelination leads to exocytotic myelin clearance in inflammatory segmental demyelination.

Schwann cells (SCs), which form the peripheral myelin sheath, have the unique ability to dedifferentiate and to destroy the myelin sheath under various demyelination conditions. During SC dedifferentiation-associated demyelination (SAD) in Wallerian degeneration (WD) after axonal injury, SCs exhibit myelin and junctional instability, down-regulation of myelin gene expression and autophagic myelin breakdown. However, in inflammatory demyelinating neuropathy (IDN), it is still unclear how SCs react and contribute to segmental demyelination before myelin scavengers, macrophages, are activated for phagocytotic myelin digestion. Here, we compared the initial SC demyelination mechanism of IDN to that of WD using microarray and histochemical analyses and found that SCs in IDN exhibited several typical characteristics of SAD, including actin-associated E-cadherin destruction, without obvious axonal degeneration. However, autophagolysosome activation in SAD did not appear to be involved in direct myelin lipid digestion by SCs but was required for the separation of SC body from destabilized myelin sheath in IDN. Thus, lysosome inhibition in SCs suppressed segmental demyelination by preventing the exocytotic myelin clearance of SCs. In addition, we found that myelin rejection, which might also require the separation of SC cytoplasm from destabilized myelin sheath, was delayed in SC-specific Atg7 knockout mice in WD, suggesting that autophagolysosome-dependent exocytotic myelin clearance by SCs in IDN and WD is a shared mechanism. Finally, autophagolysosome activation in SAD was mechanistically dissociated with the junctional destruction in both IDN and WD. Thus, our findings indicate that SAD could be a common myelin clearance mechanism of SCs in various demyelinating conditions.

Attenuation of experimental autoimmune neuritis with locally administered lovastatin-encapsulating poly(lactic-co-glycolic) acid nanoparticles.

Acute inflammatory demyelinating polyneuropathy (AIDP) is an aggressive antibody- and T-cell-mediated variant of Guillain-Barré Syndrome (GBS), a prominent and debilitating autoimmune disorder of the peripheral nervous system. Despite advancements in clinical management, treatment of patients with AIDP/GBS and its chronic variant CIDP remains palliative and relies on the use of non-specific immunemodulating therapies. Our laboratory has previously reported that therapeutic administration of statins safely attenuates the clinical severity of experimental autoimmune neuritis (EAN), a well-characterized animal model of AIDP/GBS, by restricting the migration of autoreactive leukocytes across peripheral nerve microvascular endoneurial endothelial cells that form the blood-nerve barrier. Despite these advancements, the clinical application of systemically administered statins for the management of inflammatory disorders remains controversial as a result of disappointingly inconclusive phase trials. Here, poly(lactic-co-glycolic) acid (PLGA) nanoparticles were evaluated as an alternative strategy by which to locally administer statins for the management of EAN. When tested in vitro, lovastatin-encapsulating PLGA nanoparticles elicited a marked increase in RhoB mRNA content in peripheral nerve microvascular endoneurial endothelial cells, similar to cells treated with activated unencapsulated lovastatin. Unilateral peri-neural administration of lovastatin-encapsulating PLGA nanoparticles, but not empty nanoparticles, to naïve Lewis rats similarly enhanced RhoB mRNA content in adjacent nerve and muscle tissue. When administered in this manner, serum levels of lovastatin were below the level of detection. Bilateral peri-neural administration of lovastatin-encapsulating PLGA nanoparticles to EAN-induced Lewis rats significantly attenuated EAN clinical severity while protecting against EAN-induced peripheral nerve morphological and functional deficits. This study provides the first proof-of-concept approach for the application of a nanoparticle-based local drug delivery platform for the management of inflammatory demyelinating diseases, including AIDP/GBS.

Fingolimod attenuates experimental autoimmune neuritis and contributes to Schwann cell-mediated axonal protection.

BACKGROUND: Fingolimod, a sphingosine-1-phosphate receptor modulator with well-described immunomodulatory properties involving peripheral immune cell trafficking, was the first oral agent approved for the treatment of relapsing remitting multiple sclerosis. Analogous immunomodulatory treatment options for chronic peripheral autoimmune neuropathies are lacking. METHODS: We tested fingolimod in the animal model of experimental autoimmune neuritis in Lewis rat. Six to eight-week-old female rats were immunized with P2 peptide and from this day on treated with fingolimod. Histology of the sciatic nerve was done to analyze T cell and macrophage cell count, intercellular adhesion molecule (ICAM) and amyloid precursor protein (APP) expression, as well as apoptotic Schwann cell counts. RESULTS: Preventive oral treatment with 0.1 mg/kg up to 3 mg/kg fingolimod once daily dissolved in rapeseed oil completely ameliorated clinical neuritis signs. It reduced circulating peripheral blood T cells and infiltrating T cells and macrophages in the sciatic nerve, whereas at the same time, it preserved blood-nerve barrier impermeability. Most importantly, fingolimod showed beneficial properties on the pathogenic process as indicated by fewer apoptotic Schwann cells and a lower amount of amyloid precursor protein indicative of axonal damage at the peak of disease course. CONCLUSIONS: Taken together, orally administered low-dose fingolimod showed an impressive immunomodulatory effect in the rat model of experimental autoimmune neuritis. Our current observations introduce fingolimod as an attractive treatment option for neuritis patients.

Glatiramer acetate ameliorates experimental autoimmune neuritis.

Glatiramer acetate (GA) is one of the first-line disease-modifying medications that have been approved for the treatment of multiple sclerosis via immune modulatory mechanisms. However, it remains unclear whether the immunomodulation effect of GA is central nervous system (CNS) antigen specific. Here, we explored the mechanism of action of GA by subcutaneously injecting GA in experimental autoimmune neuritis (EAN) rats, an animal model for Guillain-Barré syndrome (GBS). Clinical, electrophysiological and histological findings showed that neurological deficits, demyelination and axonal injury of sciatic nerves were all significantly attenuated in Lewis rats when GA was administered before immunization with peripheral nervous system antigen P0. Our results further demonstrated that GA treatment inhibited either P0 or myelin basic protein (MBP) (CNS antigen)-stimulated auto-immune T-cell proliferation in vitro. GA administrated at 10 days after induction of EAN when neurological sign became apparent also ameliorated the severity of disease, inhibited T-cell response to P0 and MBP and induced shift of proinflammatory and immune modulatory cytokines. Collectively, our findings suggested that GA attenuated neurological deficits in EAN rats and that the immune modulatory mechanisms of GA were not CNS antigen specific.

Lithium alleviates paralysis in experimental autoimmune neuritis in Lewis rats by modulating glycogen synthase kinase-3ß activity.

IMPORTANCE: Guillain-Barré syndrome (GBS)-like neuropathy mimics the leading cause of sporadic acute nontraumatic limb paralysis in individuals from developed countries. Experimental autoimmune neuritis (EAN) is an animal model of GBS and of syndromes such as acute canine polyradiculoneuritis, seen in dogs and cats. OBJECTIVE: The involvement of glycogen synthase kinase (GSK)-3ß, a pro-inflammatory molecule, in rat EAN is not fully understood. This study evaluated the potential role of GSK-3ß in EAN through its inhibition by lithium. METHODS: Lewis rats were injected with SP26 antigen to induce EAN. Lithium was administered from 1 day before immunization to day 14 post-immunization (PI). Then the rats were euthanized and their neural tissues were prepared for histological and Western blotting analyses. RESULTS: Lithium, an inhibitor of GSK-3, significantly ameliorated EAN paralysis in rats, when administered from day 1 to day 14 PI. This corresponded with reduced inflammation in the sciatic nerves of EAN rats, where phosphorylation of GSK-3ß was also upregulated, indicating suppression of GSK-3. CONCLUSIONS AND RELEVANCE: These findings suggest that lithium, an inhibitor of GSK-3ß, plays a significant role in ameliorating rat EAN paralysis, by suppressing GSK-3ß and its related signals in EAN-affected sciatic nerves.

Antibiotics-Induced Intestinal Immunomodulation Attenuates Experimental Autoimmune Neuritis (EAN).

BACKGROUND: The composition of gut microbiota plays a pivotal role in priming the immune system and thus impacts autoimmune diseases. Data on the effects of gut bacteria eradication via systemic antibiotics on immune neuropathies are currently lacking. This study therefore assessed the effects of antibiotics-induced gut microbiota alterations on the severity of experimental autoimmune neuritis (EAN), a rat model of Guillain-Barré Syndrome (GBS). Myelin P0 peptide 180-199 (P0 180-199)-induced EAN severity was compared between adult Lewis rats (12 weeks old) that received drinking water with or without antibiotics (colistin, metronidazole, vancomycin) and healthy rats, beginning antibiotics treatment immediately after immunization (day 0), and continuing treatment for 14 consecutive days. Neuropathy severity was assessed via a modified clinical score, and then related to gut microbiota alterations observed after fecal 16S rRNA gene sequencing at baseline and after EAN induction. Effectors of gut mucosal and endoneurial immunity were assessed via immunostaining. EAN rats showed increased gut mucosal permeability alongside increased mucosal CD8+ T cells compared to healthy controls. Antibiotics treatment alleviated clinical EAN severity and reduced endoneurial T cell infiltration, decreased gut mucosal CD8+ T cells and increased gut bacteria that may be associated with anti-inflammatory mechanisms, like Lactobacillus or Parasutterella. Our findings point out a relation between gut mucosal immunity and the pathogenesis of EAN, and indicate that antibiotics-induced intestinal immunomodulation might be a therapeutic approach to alleviate autoimmunity in immune neuropathies. Further studies are warranted to evaluate the clinical transferability of these findings to patients with GBS.

VX-509 (Decernotinib)-modified tolerogenic dendritic cells alleviate experimental autoimmune neuritis by promoting Th17/Treg rebalance.

BACKGROUND: Guillain-Barré syndrome (GBS) is an auto-inflammatory peripheral nerve disease. Dendritic cell-mediated T cell polarization is of pivotal importance in demyelinating lesions of peripheral nerves and nerve roots. However, the regulatory function of VX-509 (Decernotinib)-modified tolerogenic dendritic cells (VX-509-tolDCs) during immune remodeling following GBS remains unclear. Here, we used experimental autoimmune neuritis (EAN) as a model to investigate these aspects of GBS. METHODS: DCs were treated with varying concentrations of VX-509 (0.25, 1, and 4 µM) or served as a control using 10-8 M 1,25-(OH)2D3. Flow cytometry was employed to assess the apoptosis, phenotype, and capacity to induce T cell responses of the treated DCs. In the in vivo experiments, EAN mice received administration of VX-509-tolDCs or 1,25-(OH)2D3-tolDCs via the tail vein at a dose of 1x106 cells/mouse on days 5, 9, 13, and 17. RESULTS: VX-509 inhibited the maturation of DCs and promoted the development of tolDCs. The function of antigen-specific CD4 + T cells ex vivo was influenced by VX-509-tolDCs. Furthermore, the adoptive transfer of VX-509-tolDCs effectively alleviated inflammatory demyelinating lesions in EAN by promoting Th17/Treg (T helper 17 and regulatory T cells) rebalance. CONCLUSION: The adoptive transfer of VX-509-tolDCs alleviated inflammatory demyelinating lesions in a mouse model of GBS, known as the EAN mouse, by partially restoring the balance between Treg and Th17 cells.

Beneficial effect of a multimerized immunoglobulin Fc in an animal model of inflammatory neuropathy (experimental autoimmune neuritis).

Intravenous immunoglobulin (IVIg) is one of the first-line therapies for inflammatory neuropathies. Clinical use of IVIg for these disorders is limited by expense and availability. Here, we investigated a synthetic product alternative to IVIg. The aim of this study was to test the therapeutic efficacy of a novel recombinant polyvalent murine IgG2a Fc compound (stradomer™) in experimental autoimmune neuritis (EAN). Seventy-four Lewis rats were immunized with myelin, randomized into three groups, and were treated with albumin, IVIg, or stradomer at 1% of IVIg dose. Rats were assessed clinically, electrophysiologically, and histologically. The clinical disease severity was evaluated by clinical grading and weight changes. The electrophysiological studies recorded motor conduction velocity (MCV), amplitudes, and latencies of the evoked compound muscle action potential (CMAP) and spinal somatosensory evoked potential. The treatment efficacy of the IVIg and stradomer groups was compared to the albumin (control) group. We demonstrate that stradomer has a similar therapeutic efficacy to human IVIg in EAN. Rats receiving stradomer or IVIg showed significantly lower clinical scores and less prominent weight loss compared with controls. A statistically significant improvement in both MCV and the amplitudes of distal and proximal evoked CMAP was observed in the stradomer and IVIg groups. Finally, treatment with both IVIg and stradomer resulted in statistically less inflammation and demyelinating changes in the sciatic nerve as evidenced by lower histological grade. These results reveal the potential of using fully recombinant multimerized immunoglobulin Fc instead of IVIg for treating inflammatory neuropathies.

Suppression of experimental autoimmune optic neuritis by the novel agent fingolimod.

PURPOSE: Fingolimod is an immunomodulating agent that has been approved for the treatment of multiple sclerosis. Fingolimod-phosphate is an antagonist of sphingosine-1-phosphate receptor and known to act by preventing infiltration of autoreactive lymphocytes into the central nervous system. In this study, we investigated whether fingolimod prevents experimental autoimmune optic neuritis (EAON). METHODS: EAON was induced by immunizing C57BL/6 mice with myelin oligodendrocyte glycoprotein-derived peptide 35-55 (MOG-p). After MOG-p immunization, fingolimod was administered intragastrically from day 1 (entire phase study) or from day 9 (effector phase study) until day 35. Visual acuity of the mice was measured using OptoMotry on days 7, 14, 21, 28, and 35 after immunization. On day 35 after immunization, the mice were killed and eyes and entire length of the optic nerves were submitted for histopathologic evaluation. RESULTS: In the positive control group, visual acuity decreased markedly from approximately day 14 after immunization, reaching a nadir on day 21. In the fingolimod-treated groups in both entire phase and effector phase studies, there was only minimal decline in visual acuity on day 14 after immunization, and mild deterioration on day 21, followed by recovery. Histopathologic study showed that fingolimod given throughout the entire phase or only from the effector phase suppressed murine EAON. Immunohistochemical study for neurofilament demonstrated no irregularity of the linear structure of the optic nerve in the fingolimod-treated mice compared with the positive control group. CONCLUSION: Fingolimod ameliorated EAON even when started after optic neuritis had developed. Further study is warranted to examine whether these findings are applicable to human disease.

2,4-Dinitrophenol does not exert neuro-regenerative potential in experimental autoimmune neuritis.

OBJECTIVE: We evaluated the potential neuro-regenerative effects of the mitochondrial uncoupler 2,4-Dinitrophenol in experimental autoimmune neuritis, an animal model for an acute autoimmune neuropathy. METHODS: Experimental autoimmune neuritis was induced in Lewis rats. Different concentrations of 2,4-Dinitrophenol (1 mg/kg, 0.1 mg/kg and 0.01 mg/kg) were applied during the recovery phase of the neuritis (at days 18, 22 and 26) and compared to the vehicle. Any effects were assessed through functional, electrophysiological, and morphological analysis via electron microscopy of all groups at day 30. Additional immune-histochemical analysis of inflammation markers and remyelination of the sciatic nerves were performed for the dosage of 1 mg/kg and control. RESULTS: No enhancement of functional or electrophysiological recovery was observed in all 2,4-Dinitrophenol-treated groups. Cellular inflammation markers of T cells (CD3+) were comparable to control, and an increase of macrophages (IbA1+) invasion in the sciatic nerves was observed. Treatment with 2,4-Dinitrophenol reduced axonal swelling in myelinated and unmyelinated fibers with an increased production of brain-derived neurotrophic factor. CONCLUSION: Our findings do not support the hypothesis that repurposing of the mitochondrial uncoupler 2,4-Dinitrophenol exerts functionally relevant neuro-regenerative effects in autoimmune neuritis.

Fingolimod ameliorates chronic experimental autoimmune neuritis by modulating inflammatory cytokines and Akt/mTOR/NF-κB signaling.

OBJECTIVE: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated disease that targets the myelin sheaths of the peripheral nerves. Fingolimod is a sphingosine 1 phosphate (S1P) receptor antagonist with a high affinity for S1P receptors through the Akt-mTOR pathway, and prior research has suggested that it might be helpful in autoimmune illnesses. METHODS: Chronic experimental autoimmune neuritis (c-EAN) was induced by immunizing Lewis rats with the S-palm P0(180-199) peptide, and then the treatment group was intraperitoneally injected with fingolimod (1 mg/kg) daily. Hematoxylin and eosin staining was used to assess the severity of nerve injury. Immunohistochemistry staining showed that fingolimod's anti-inflammatory effects on c-EAN rats might be realized through the NF-κB signaling pathway. Tumor necrosis factor-α (TNF-α), interferon-γ (INF-γ), interleukin-1beta (IL-1ß), interleukin 6 (IL-6), inducible nitric oxide synthase (iNOS), and intercellular adhesion molecule-1 (ICAM-1) were measured to evaluate the inflammation levels, and pAkt, p-S6, and p-p65 were used to measure the abundance of downstream activation markers to determine whether the Akt/mTOR/NF-κB signaling pathway was activated in the c-EAN model. RESULTS: Fingolimod treatment reduced the inflammatory reaction and the expression of NF-κB in sciatic nerves. It also decreased the mRNA levels of the proinflammatory cytokines TNF-α, IFN-γ, IL-1ß, IL-6, iNOS, and ICAM-1 and pAkt, p-S6, and p-p65, representing the Akt/mTOR/NF-κB signaling pathway. CONCLUSION: Our data showed that fingolimod could improve the disease course, alleviate the decrease in inflammation, and reduce proinflammatory cytokines through the Akt/mTOR/NF-κB axis in c-EAN rats, which could be beneficial for the development of CIDP-related research.