Development Of Experimental Autoimmune Neuritis Research Articles

M1 Macrophage Derived Exosomes Aggravate Experimental Autoimmune Neuritis via Modulating Th1 Response

Guillain–Barré syndrome (GBS), an immune-mediated disorder affecting the peripheral nervous system, is the most common and severe acute paralytic neuropathy. GBS remains to be potentially life-threatening and disabling despite the increasing availability of current standard therapeutic regimens. Therefore, more targeted therapeutics are in urgent need. Macrophages have been implicated in both initiation and resolution of experimental autoimmune neuritis (EAN), the animal model of GBS, but the exact mechanisms remain to be elucidated. It has been increasingly appreciated that exosomes, a type of extracellular vesicles (EVs), are of importance for functions of macrophages. Nevertheless, the roles of macrophage derived exosomes in EAN/GBS remain unclear. Here we determined the effects of macrophage derived exosomes on the development of EAN in Lewis rats. M1 macrophage derived exosomes (M1 exosomes) were found to aggravate EAN via boosting Th1 and Th17 response, while M2 macrophage derived exosomes (M2 exosomes) showed potentials to mitigate disease severity via a mechanism bypassing Th1 and Th17 response. Besides, both M1 and M2 exosomes increased germinal center reactions in EAN. Further in vitro studies confirmed that M1 exosomes could directly promote IFN-γ production in T cells and M2 exosomes were not capable of inhibiting IFN-γ expression. Thus, our data identify a previously undescribed means that M1 macrophages amplify Th1 response via exosomes and provide novel insights into the crosstalk between macrophages and T cells as well.

Berberine Ameliorates Experimental Autoimmune Neuritis by Suppressing both Cellular and Humoral Immunity

Berberine (BBR), an isoquinoline derivative alkaloid, has been extensively used in traditional Chinese medicine for the treatment of diarrhoea, rheumatic diseases, diabetes, etc. Recent studies have demonstrated new biological properties of BBR and suggested the possibility of BBR to be a therapeutic agent for some autoimmune diseases. To explore the effect of BBR on the development of experimental autoimmune neuritis (EAN), BBR was administered intragastrically daily to Lewis rats immunized with P0 peptide 180-199 in Freund's complete adjuvant. We found BBR treatment resulted in amelioration of EAN, accompanied by suppressed lymphocyte (in particular CD4(+) T cell) proliferation, downregulated Th1 (TNF-α) and Th2 (IL-10) cytokines and reduced anti-P0 peptide 180-199 IgG1 and IgG2a. In brief, BBR played a role in ameliorating EAN by suppressing both cellular and humoral immunity. Thus, our study suggests that BBR may be a potential therapeutic agent for the autoimmune disease in the peripheral nervous system, such as Guillain-Barré syndrome.

Granulocyte–Colony‐Stimulating Factor Treatment Enhances Foxp3+ T Lymphocytes and Modifies the Proinflammatory Response in Experimental Autoimmune Neuritis

Despite the evolution of treatments in the past decade, acute inflammatory autoimmune diseases of the peripheral nervous system are still a concern due to their considerable morbidity and mortality [1]. Guillain-Barr e syndrome (GBS) is an acute inflammatory disorder. The study of experimental autoimmune neuritis (EAN), the experimental model of GBS, has provided most of the knowledge regarding GBS disease mechanisms. Inflammatory lesions are primarily located in the sciatic nerves and the cauda equina of EAN-affected Lewis rats [2]. Lesions are characterized by an accumulation of inflammatory cells, primarily T cells, and macrophages. The inflammatory response during EAN is characterized mainly by the migration of neuritogenic cells into the peripheral nerves and by the production and secretion of proinflammatory cytokines, such as IFNc, TNFa, IL-6, and IL-17 [3]. During the last years, hematopoietic factors, such as erythropoietin, granulocyte–macrophage colony-stimulating factor and granulocyte–colony-stimulating factor (G-CSF), have been successfully used to modify experimental autoimmune diseases [4,5]. Moreover, G-CSF has an important and strong tolerogenic function. This cytokine recruits immature dendritic cells (DCs), which induce tolerance through the enhancement of regulatory T cells [5]. In this study, we investigated the effects of short-term G-CSF treatment on the evolution of EAN. EAN was induced using the neuritogenic peptide P253-78 as previously described [6]. The clinical signs of EAN were significantly reduced by the in vivo administration of G-CSF in a short-term treatment regimen (Figure 1A). The development of EAN is characterized by the sensitization and activation of neuritogenic T cells in the peripheral immune organs. These cells migrate into peripheral nerves and release inflammatory mediators, which may contribute directly or indirectly to the destruction of the myelin sheath. We observed a significant reduction in the specific proliferative response of T cells from Lewis rats with EAN treated with G-CSF compared with the cells from the control animals (Figure 1B). Moreover, G-CSF treatment reduced the mononuclear cell infiltration into the sciatic nerve (Figure 1C). The EAN autoaggressive response is characterized by the expression and release of Th1 and/or Th17 cytokines. Therefore, we evaluated the expression, by real-time PCR (Figure S1), of Th1 and Th17 cytokines and transcription factors, in the lymph nodes 10 days after immunization, prior to the migration of the neuritogenic cells from the periphery to the target tissue. We observed a consistent downregulation in the expression of the Th1 (T-bet) and Th17 (RORa and RORct) transcription factors in the G-CSFtreated group compared with control group (Figure 1D). Corroborating the changes in the transcription factors expression profile, the expression of proinflammatory cytokines (IFNc, IL-17A, IL17E, and IL-6) was reduced in the G-CSF-treated group compared with the control group. G-CSF treatment also led to an increase in the expression of anti-inflammatory cytokines, such as IL-10 and

FTY720 ameliorates experimental autoimmune neuritis by inhibition of lymphocyte and monocyte infiltration into peripheral nerves

Experimental autoimmune neuritis (EAN) is a T cell-mediated autoimmune demyelinating inflammatory disease of the peripheral nervous system (PNS). T cells and macrophages are essential for the initiation and development of EAN. FTY720 acts as an agonist of sphingosine-1-phosphate receptors, resulting in inhibition of lymphocyte egress from secondary lymphoid tissues and thymocytes from thymus. This investigation describes the immunosuppressive effects of FTY720 in EAN, the animal model of autoimmune neuropathies. FTY720 (1 mg/kg body weight) completely suppressed paraparesis if administrated from the day of immunization. Furthermore, FTY720 greatly reduced the severity and duration of EAN even when administrated after the appearance of the first neurological sign. T cell, B cell, and macrophage infiltration and demyelination of sciatic nerves were significantly decreased in FTY720-treated EAN. Therefore, FTY720 might be a potential candidate for treatment of inflammatory neuropathies.

Soluble TNFR1 inhibits the development of experimental autoimmune neuritis by modulating blood–nerve-barrier permeability and inflammation

The role of TNFα/LTα during EAN induced by active immunization with peripheral nerve myelin was examined by administering a recombinant soluble chimeric form of human TNF receptor 1 (TNFR1-IgG). TNFα and LTα do not directly contribute to neurological deficit during EAN since treatment with TNFR1-IgG after onset failed to alter the course of disease. Prophylaxis with a single dose of TNFR1-IgG delayed the onset of EAN and was accompanied initially by inhibition of blood–nerve-barrier permeability and inflammation. Subsequently, the number of infiltrating macrophages and blood–nerve-barrier permeability increased but the disease symptoms remained mild for five days (on average a limp tail) after which severe EAN developed. The antibody titer to peripheral nerve myelin was unaltered by prophylaxis with TNFR1-IgG. The markedly altered tempo of disease onset after TNFR1-IgG prophylaxis indicates that TNFα and/or LTα have a key role in the development of blood–nerve-barrier permeability and the coupling of macrophage activation and recruitment to peripheral nerve pathology during EAN.

B cells play a cooperative role via CD40L–CD40 interaction in T cell-mediated experimental autoimmune neuritis in Lewis rats

The expression of co-stimulatory molecules CD40 and CD40L was examined over the course of experimental autoimmune neuritis (EAN) induced in Lewis rats by immunization with bovine peripheral nerve myelin. In draining lymph nodes, highest level of CD40L expression was seen on day 7 post immunization (p.i.), i.e. before onset of clinical signs of EAN, while CD40 expression was increased on day 14 p.i., i.e. at peak of clinical disease. In contrast, both CD40 and CD40L expressing cells in sciatic nerves, a target organ of EAN, peaked on day 14 p.i., large numbers of both expressing cells were mainly detected on day 14-21 p.i. After co-culture with EAN rat B cells bearing CD40, P0 peptide 180-199-specific T cell line cells exhibited a rapid down-regulation of CD40L expression. Furthermore, EAN rats had enhanced P0 peptide 180-199-specific antibody responses on day 14 p.i., which might have contributed to their aggravated EAN and further demonstrated the role of antibodies in EAN. The results indicate that CD40L-CD40 interactions are involved in the initiation of the antigen-specific T cell responses associated with the generation and development of EAN, and may mediate autoantibody production in EAN. Evidently, B cells play a cooperative role via CD40L-CD40 interaction in T cell-mediated EAN of Lewis rats.

Lovastatin attenuates nerve injury in an animal model of Guillain–Barré syndrome

Statins, widely used as clinically effective inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, exhibit anti-inflammatory properties that may be of therapeutic benefit for the management of some neurological disorders. In this study, a short-term course of lovastatin treatment is shown to markedly inhibit the development of experimental autoimmune neuritis (EAN) in the absence of hepatotoxic or myotoxic complications. Independent of cholesterol reduction, lovastatin treatment prevented EAN-induced peripheral nerve conduction deficits and morphologic nerve injury. Co-administration with mevalonate neutralized the prophylactic effects of lovastatin. When administered therapeutically, lovastatin significantly shortened the disease course. Autoreactive immunity, measured in vitro by myelin-stimulated proliferation of splenocytes, was significantly diminished by in vivo lovastatin treatment. Th1-dominant immune responses, measured by cytokine profiling, however, were not affected by lovastatin. Sciatic nerves of lovastatin-treated immunized rats showed markedly reduced levels of cellular infiltrates. Treating peripheral nerve endothelial monolayers with lovastatin significantly inhibited the in vitro migration of autoreactive splenocytes. Together, these data demonstrate that a short-term course of lovastatin attenuates the development and progression of EAN in Lewis rats by limiting the proliferation and migration of autoreactive leukocytes.

Exogenous soluble tumor necrosis factor receptor type I ameliorates murine experimental autoimmune neuritis

Tumor necrosis factor (TNF) and its receptor (TNFR) have been strongly implicated in the pathogenesis of autoimmune disease. Soluble cytokine receptors may be shed naturally from cell membranes to inhibit cytokine activity. Experimental autoimmune neuritis (EAN) is a CD4 Th1 cell-mediated animal model of Guillain–Barré syndrome (GBS) in humans. In the present study, we investigated the effects of soluble TNFR type I (sTNFR I) in EAN induced in mice by P0 peptide 180–199 and Freund’s complete adjuvant. Our data from two different therapeutic regimens indicate that the administration of sTNFR I effectively ameliorated the clinical and pathological signs of EAN, i.e., decreased its severity, shortened its duration, and reduced inflammatory cell infiltration into the peripheral nervous system. The suppression of clinical EAN was accompanied in vitro by a marked reduction in antigen-specific T-cell proliferation and IFN-γ synthesis by spleen cells from sTNFR I-treated mice, compared to control mice treated with PBS. These data directly demonstrate a pivotal role for TNF in the development of EAN and also suggest that sTNFR I may have therapeutic potential for alleviating GBS in humans.

Initiation and development of experimental autoimmune neuritis in Lewis rats is independent of the cytotoxic capacity of NKR-P1A+ cells.

Natural killer (NK) cells are implicated in T cell-mediated autoimmune diseases. Experimental autoimmune neuritis (EAN) is a CD4+ T cell-mediated animal model of the Guillain-Barré syndrome in human. The role of NK cells in the initiation and development of EAN remains unclear. In the present study, we demonstrate that anti-NKR-P1A monoclonal antibody (mAb) treatment in vivo did not affect the initiation and development of clinical EAN in Lewis rats induced by immunization with peripheral nerve myelin P0 protein peptide 180-199 and Freund's complete adjuvant, as well as the proportion of NKR-P1A+ cells (including NK cells and NKT cells) in the spleen. Furthermore, inflammatory cell infiltrations and demyelination in the peripheral nervous system (PNS) and in vitro P0 peptide 180-199-specific splenocyte proliferation were not different in anti-NKR-P1A mAb-treated rats compared to the control antibody-treated rats. The cytotoxic activity of NKR-P1A+ cells, determined by NK cell-sensitive K562 cells as target cells, decreased markedly in anti-NKR-P1A mAb-treated rats, suggesting that decrease of the cytotoxic activities of NKR-P1A+ cells is not sufficient to alter clinical EAN, although NKR-P1A+ cells may participate in the pathogenesis of T cell-mediated autoimmune diseases, such as EAN, by the mechanisms that involve the release of cytokines.

CD28–B7 costimulation: a critical role for initiation and development of experimental autoimmune neuritis in C57BL/6 mice

CD28 provides a critical costimulatory signal for antigen-specific T cell activation. Because CD28 is an important factor in the development of autoimmune diseases, we investigated its role in T cell-mediated experimental autoimmune neuritis (EAN), an animal model of Guillain-Barré syndrome in humans. CD28-deficient mutant (CD28 −/−) C57BL/6 mice and corresponding wild-type mice were immunized with P0 peptide 180–199, a purified component of peripheral nerve myelin, and Freund’s complete adjuvant. As a result, all wild-type mice developed severe EAN, in contrast, none of the CD28 −/− mice manifested clinical signs of disease. Additionally, CD28 −/− mice had fewer IL-12 producing cells in sciatic nerve sections and fewer IFN-γ secreting splenic cells than wild-type mice on day 24 post immunization, i.e., at the peak of clinical EAN. At that time point, CD28 −/− mice had milder infiltration of such inflammatory cells as macrophages, CD4 + T cells and monocytes into sciatic nerve tissues and less demyelination than wild-type mice. Moreover, the CD28-deficiency led to reduced production of specific anti-P0 peptide 180–199 antibodies compared with wild-type mice. Evidently, CD28 is required for interaction with B7 to regulate the activation of T and B cells that initiates development of EAN.

Suppression of experimental autoimmune neuritis by the oxygen radical scavengers superoxide dismutase and catalase.

Macrophages have been implicated in myelin damage in experimental autoimmune neuritis (EAN). We examined a possible pathogenetic role of toxic oxygen species elaborated by macrophages in EAN by administering oxygen radical scavengers. Early treatment of rats with either catalase or superoxide dismutase (10,000 U/kg/day) protected animals from the development of EAN. Treatment delayed until there was clinical manifestation of EAN (day 13) still markedly attenuated the severity of the disease, as evidenced by clinical assessment, electrophysiological studies, and morphological observation. In cell culture, macrophages from sham-treated controls generated heightened oxidative metabolic responses indicating in vivo macrophage activation. Addition of catalase or superoxide dismutase abrogated or diminished chemiluminescence and production of reactive oxygen intermediates by macrophages ex vivo. Our findings underscore the importance of macrophages in EAN and provide evidence that, in this model, macrophage-derived reactive oxygen intermediates contribute to damage of the myelin sheath.