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IL-18 deficiency inhibits both Th1 and Th2 cytokine production but not the clinical symptoms in experimental autoimmune neuritis.

IL-18 deficient (IL-18-/-) mice were used to investigate the role of IL-18 in the pathogenesis of experimental autoimmune neuritis (EAN) which was induced by immunization of the mice with P0 protein peptide 180-199. The clinical course was not different between IL-18-/- and wild-type mice. The splenic mononuclear cell (MNC) proliferation was also similar in both animal groups. However, the percentages of IFN-gamma, IL-10 and IL-12 positive cells were decreased among infiltrating MNC of cauda equine in IL-18-/- mice. This indicates that IL-18 deficiency inhibits the production of both Th1 and Th2 cytokines in the target organ of mice with EAN.

Animals↗

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.

Acute Disease↗

[Apoptosis of CD4(+) T cells during experimental autoimmune neuritis in Wistar rats].

The present study describes apoptosis of T cells in the sciatic nerve in Wistar rats with experimental autoimmune neuritis(EAN). Morphological characterizations of apoptosis were found at the 18th day from onset, peaked at the 22nd day by immunocytochemical analysis. In situ end labeling(ISEL) techniques confirmed the presence of DNA fragmentation in CD4(+) T cells. It is suggested that apoptosis is an important clearance mechanism of infiltrated T cells in the peripheral nervous system(PNS) in EAN.

Animals↗

[Study on therapy of experimental autoimmune neuritis by bone marrow stromal cells].

AIM: To investigate the therapeutic effect of bone marrow stromal cells (BMSCs) transplantation on experimental autoimmune neuritis (EAN) and study the possible mechanism. METHODS: EAN model was established by immunizing Lewis rats with P(0)180-199 peptide and complete Freund's adjuvant (CFA). In the therapy group, BMSCs (2x10(6) cells/rat) were marked with fluorochrome PKH26 and injected into the rats' caudal vein 10 d after immunization. The therapeutic effect of BMSC transplantation on EAN rats was investigated by clinical assessment, immunohistochemical staining, and ELISA, respectively. RESULTS: The injected BMSCs could migrate to the demyelinated nerve tissues, and the demyelination and inflammatory infiltration was relieved. The infiltration of CD4(+) and CD8(+) T cells and the sera level of IFN-gamma and TNF-alpha were decreased significantly (P<0.05), whereas IL-4 level in the supernatant of cultured lymphocytes was increased (P<0.05). CONCLUSION: Certain therapeutic effect of BMSC transplantation on EAN was observed. BMSCs could reverse the disbalance of Th1/Th2 cells by regulating the cytokine expression and could inhibit the activation and proliferation of T cells.

Animals↗

Treatment and prevention of experimental autoimmune neuritis with superagonistic CD28-specific monoclonal antibodies.

Two distinct CD28-specific mAb were used in treatment of active or adoptive transfer (AT)-experimental autoimmune neuritis (EAN): "superagonistic" JJ316 activates T cells without T cell receptor (TCR) occupancy, and conventional JJ319 activates T cells only in the presence of TCR-stimulation. Treatment with JJ316 during induction phase of active and adoptive-transfer experimental autoimmune encephalomyelitis (AT-EAN) dramatically reduced disease severity and improved nerve function as revealed by electrophysiology. JJ316 given 1 week before immunization had a preventive effect. By immunohistology, JJ316 markedly reduced TC infiltration of the sciatic nerve in active and AT-EAN. JJ319 was less effective. Ex vivo, JJ316 therapy reduced P2-specific proliferation and interferon-gamma (IFN-gamma) production of lymph node cells. We demonstrate preventive and therapeutic effects of a "superagonistic" mAb-mediated, TCR-independent CD28 stimulation in EAN, possibly with implications for therapy of autoimmune-inflammatory disorders.

Adoptive Transfer↗

Changes in axonal morphology in experimental autoimmune neuritis as studied by high b-value q-space (1)H and (2)H DQF diffusion magnetic resonance spectroscopy.

Experimental autoimmune neuritis (EAN) has been studied in rat sciatic nerves by a combination of high b-value (1)H and (2)H double quantum filtered (DQF) diffusion MRS. The signal decays of water in the (1)H and (2)H DQF diffusion MRS were found to be not monoexponential and were analyzed using the q-space approach. The q-space analysis of the (1)H diffusion data detected two diffusing components, one having broad and the other having narrow displacement profiles. These components were shown to be very sensitive to the progression of EAN disease. The q-space parameters were found to be abnormal at day 9 postimmunization before the appearance of clinical signs. The assignment of the component with the narrow displacement profile to axonal water has been corroborated by the (2)H DQF diffusion MRS results. The displacement and the relative population of this slow and restricted diffusing component followed the processes of demyelination, axonal loss, and remyelination that occur in EAN. The displacements extracted from the slow-diffusing component with the narrow displacement correlated well with the average size of the axons as deduced from electron microscopy (EM). The component with the broad displacement showed significant changes which were attributed to the formation of endoneurial edema. This observation was also corroborated by the (2)H DQF diffusion MRS experiments. It seems, therefore, that q-space analysis of high b-values diffusion MRS is a promising new approach for early detection and better characterization of the different pathologies associated with EAN. This study demonstrates the utility of high-b-value q-space diffusion MRS for studying white matter-associated disorders in general.

Animals↗

Monocyte chemoattractant protein 1 and chemokine receptor CCR2 productions in Guillain-Barré syndrome and experimental autoimmune neuritis.

Infiltration of activated lymphocytes and monocytes is a key phenomenon in the pathogenesis of Guillain-Barré syndrome (GBS) and experimental autoimmune neuritis (EAN). To investigate the role of chemokines, we determined the blood and nerve tissue expression of monocyte chemoattractant protein 1 (MCP-1), a major chemoattractant of monocytes and activated lymphocytes, and its receptor CCR2 in GBS and EAN. MCP-1 circulating levels (ng/ml) in GBS were increased at the time of progression, peaked at the time of plateau and normalized with recovery. MCP-1 circulating levels were the highest in the most disabled patients. The number of circulating CCR2 positive cells was lower in patients with GBS than in healthy subjects (p<0.004). In GBS, MCP-1 expression was observed in epineurial and endoneurial vessels, on infiltrating cells, Schwann cells and in the endoneurial extracellular matrix. Some CCR2 positive cells were observed in nerve biopsies of GBS patients. In EAN, a slight positivity for MCP-1 was observed in the sciatic nerve. There was no circulating CCR2 positive cells. However, at the time of plateau, a conspicuous infiltration of CCR2 positive cells was observed in the sciatic nerve that was no longer observed at the time of recovery. These results suggest that MCP-1 and CCR2 may participate to the recruitment of circulating mononuclear cells in nerve tissue in EAN and GBS.

Animals↗

Transient cellular expression of gamma-interferon in myelin-induced and T-cell line-mediated experimental autoimmune neuritis.

This study reports the cellular localization of gamma-interferon (gamma-IFN) in nerve roots during the course of experimental autoimmune neuritis induced either by active immunization (EAN) or adoptive transfer of P2-specific T-cells (AT-EAN). One micrometre thick cryosections of ventral roots of EAN and AT-EAN animals were labelled with the monoclonal antibodies DB-1 and DB-12 recognizing different epitopes of rat gamma-IFN. In EAN numerous gamma-IFN-positive cells were present before overt clinical signs and demyelination (days 11-13 after immunization). Concomitantly, raised gamma-IFN levels were measured in the serum of these animals. However, systemically increased gamma-IFN serum levels were not specific for a neuritogenic T-cell response. At subsequent stages when many axons were demyelinated (day 16 and later) gamma-IFN-positive cells had disappeared and gamma-IFN serum levels returned to normal value. gamma-Interferon positive cells could be identified as W3/13 positive T-cells and polymorphonuclear leukocytes. Additionally, a considerable number of ED1-positive macrophages showed gamma-IFN immunoreactivity. The majority of macrophages and all Schwann cells were gamma-IFN negative. Similar results were obtained in AT-EAN 4 d and 6 d following cell transfer. After nerve transection no gamma-IFN-positive cells were found in the distal stumps. The localization of gamma-IFN in nerve roots indicates an important role of this lymphokine in acute immune-mediated demyelination. gamma-Interferon most likely locally affects macrophage functions such as migration, major histocompatibility complex (MHC) class II antigen (Ia) expression, and production of cytotoxic molecules in nerves, and thereby contributes to myelin damage.

Animals↗

Resistance and susceptibility to experimental autoimmune neuritis in Sprague-Dawley and Lewis rats correlate with different levels of autoreactive T and B cell responses to myelin antigens.

Experimental autoimmune neuritis (EAN) is a CD4+ T cell-mediated, inflammatory demyelinating disease of the peripheral nervous system (PNS) that serves as a model for Guillain-Barré syndrome (GBS) in humans. Various mouse and rat strains show different susceptibilities to EAN that can be induced by immunization with bovine PNS myelin (BPM) + Freund's complete adjuvant (FCA). We examined PNS-induced T and B cell responses and cytokine protein production as well as mRNA expression to study the mechanisms behind susceptibility to EAN in Lewis rats and resistance in Sprague-Dawley (SD) rats. Lewis rats with EAN have elevated PNS myelin-reactive interferon-gamma (IFN-gamma) production, TNF-alpha mRNA expression, and increased B cell responses to PNS myelin antigens, but low PNS myelin-reactive transforming growth factor-beta (TGF-beta) and interleukin (IL)-10 mRNA expression in lymph node mononuclear cells (MNC). In contrast, resistance to EAN in SD rats is associated with reduced BPM and P2 peptide-reactive IFN-gamma production, TNF-alpha mRNA expression, and suppressed B cell responses to PNS myelin antigens as well as up-regulation of TGF-beta and IL-10 mRNA expression. Resistance to EAN is also associated with low-grade inflammation or absence of histological evidence of EAN. These results suggest that differential autoreactive T and B cells responses to PNS myelin antigens are strain specific, and the susceptibility to EAN is related to quantitative rather than qualitative differences in distribution between proinflammatory and anti-inflammatory cytokines.

Animals↗

Axonal protection in experimental autoimmune neuritis by the sodium channel blocking agent flecainide.

Inflammatory demyelinating neuropathies such as Guillain-Barre syndrome (GBS) and its animal model, experimental autoimmune neuritis (EAN), are typically acute monophasic diseases of the PNS that can leave affected individuals with permanent disability due primarily to axonal degeneration. The mechanisms underlying the degeneration are not understood, but we have previously shown in vitro and in vivo that axons can degenerate when exposed to the inflammatory mediator nitric oxide, and that axons can be protected by application of the sodium channel-blocking agent, flecainide. Here we examine whether flecainide administration can similarly reduce axonal degeneration in the periphery in animals with EAN. EAN was induced in Lewis rats (n = 116, in three independent trials), and rats received either flecainide (Flec) (30 mg/kg/day) or vehicle (Veh) from the onset of disease expression. Flecainide administration significantly reduced the mean (SD) scores for neurological deficit at both the peak of disease (Flec: 5.7 (2.7), Veh: 8.0 (3.6), P < 0.001) and at the termination of the trials 25-29 days post-inoculation (Flec: 2.2 (2.4), Veh: 4.2 (4.2), P < 0.001). Histological examination of the tibial nerve of EAN animals revealed that flecainide provided significant protection against axonal degeneration so that 80.0% of the normal number of axons survived in flecainide-treated rats compared with 62.8% in vehicle-treated rats (P < 0.01). These findings may indicate a novel avenue for axonal protection in GBS and other inflammatory demyelinating neuropathies.

Animals↗

The effect of treatment with crotapotin on the evolution of experimental autoimmune neuritis induced in Lewis rats.

Biomedical research in which venom components are being investigated for their potential as novel therapeutic agents has emerged as an interesting option. Crotapotin, which is purified from the venom of the rattlesnake Crotalus durissus terrificus, has been described as an anti-inflammatory agent that acts on the innate arm of the immune response. Here we have demonstrated that intraperitoneal administration of crotapotin significantly reduces the severity of experimental autoimmune neuritis (EAN), an experimental model for Guillain-Barré syndrome. The reduction of the severity of the disease is associated with a reduction in the mononuclear cells infiltrating the sciatic nerve and a significant decrease in the lymphocyte proliferative response to neuritogenic peptide.

Animals↗

Efficacy of leukemia inhibitory factor in experimental autoimmune neuritis.

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine that exerts neurotrophic and myotrophic actions. We have investigated the effect of LIF in experimental autoimmune neuritis (EAN), an animal model of Guillain-Barré syndrome (GBS). Treatment with LIF at the onset of the disease showed a slight, but not significant, improvement in the clinical course but no effect on nerve histology.

Animals↗

Effects of ganglioside administration on experimental autoimmune neuritis induced by peripheral nerve myelin or P2-specific T cell lines.

We studied the effects of ganglioside administration in two animal models of inflammatory demyelinating polyneuropathy. We administered a mixture of bovine brain gangliosides intraperitoneally to Lewis rats with myelin-induced or T cell line-mediated experimental autoimmune neuritis (EAN). Under the experimental conditions we had chosen, we only detected marginal but not statistically significant effects on disease course and severity, as evidenced by motor function, electrophysiological findings, and morphological signs of inflammation and demyelination. There was no significant induction of antibody production against gangliosides, and we did not detect signs of increased cellular reactivity towards gangliosides. We conclude that the administration of gangliosides modulates EAN at best marginally, and does not induce a cellular or humoral immune reaction.

Animals↗

Immunohistochemical study of caveolin-1 in the sciatic nerves of Lewis rats with experimental autoimmune neuritis.

The expression of caveolin-1 and the related molecule endothelial nitric oxide synthase (eNOS) was analyzed in the sciatic nerves of Lewis rats with experimental autoimmune neuritis (EAN). Western blot analysis showed that caveolin-1 significantly increased in the sciatic nerves with EAN upon initiation of cell infiltration during the early and peak stages (days 10 and 14 post-immunization, p.i.) and declined thereafter. The pattern of eNOS expression over the course of EAN largely matched that of caveolin-1. Immunohistochemistry showed that in EAN lesions, intense caveolin-1 immunostaining occurred in ED1-positive macrophages as well as in vessels, while the caveolin-1 immunoreaction was reduced in Schwann cells in the inflammatory lesions. Consequently, we postulated that caveolin-1 expression increased in the sciatic nerves with EAN; this possibly mediated either molecular trafficking or nitric oxide generation partly through the activation of eNOS in vascular endothelial cells, as well as in inflammatory macrophages in EAN and/or cellular apoptosis of inflammatory cells.

Animals↗

Expression of constitutive endothelial and inducible nitric oxide synthase in the sciatic nerve of Lewis rats with experimental autoimmune neuritis.

This study examined the expression of constitutive endothelial nitric oxide synthase (eNOS) and inducible NOS (iNOS) in the sciatic nerve of Lewis rats with experimental autoimmune neuritis (EAN). Western blot analysis showed that both eNOS and iNOS expressions in the sciatic nerves of rats increased significantly during the peak stage of EAN, but declined thereafter. Only minimal amounts of these enzymes were identified in normal rat sciatic nerves. Immunohistochemical studies showed that eNOS was increased in vascular endothelial cells and Schwann cells, but not in inflammatory cells, during the peak stage of EAN. However, iNOS was found mainly in inflammatory macrophages in sciatic nerve EAN lesions.These findings suggest that, depending on the stage of peripheral nervous system autoimmune disease, the increased expressions of both eNOS and iNOS might be involved in either the production of detrimental effects during the induction stage of EAN or in the recovery from EAN paralysis.

Animals↗

Experimental autoimmune neuritis induces differential microglia activation in the rat spinal cord.

The reactive spatial and temporal activation pattern of parenchymal spinal cord microglia was analyzed in rat experimental autoimmune neuritis (EAN). We observed a differential activation of spinal cord microglial cells. A significant increase in ED1(+) microglia predominantly located in the dorsal horn grey matter of lumbar and thoracic spinal cord levels was observed on Day 12. As revealed by morphological criteria and by staining with further activation markers [allograft inflammatory factor 1 (AIF-1), EMAPII, OX6, P2X(4)R], reactive microglia did not reach a macrophage-like state of full activation. On Day 12, a significant proliferative response could be observed, affecting all spinal cord areas and including ED1(+) microglial cells and a wide range of putative progenitor cells. Thus, in rat EAN, a reactive localized and distinct microglial activation correlating with a generalized proliferative response could be observed.

Animals↗

Linomide suppresses experimental autoimmune neuritis in Lewis rats by inhibiting myelin antigen-reactive T and B cell responses.

Linomide (quinoline-3-carboxamide) is a synthetic immunomodulator that suppresses several experimental autoimmune diseases. Here we report the effects of Linomide on experimental autoimmune neuritis (EAN), a CD4+ T cell-mediated animal model of acute Guillain-Barré syndrome (GBS) in humans. EAN induced in Lewis rats by inoculation with bovine peripheral nervous system (PNS) myelin and Freund's complete adjuvant was strongly suppressed by Linomide administered daily subcutaneously from the day of inoculation. Linomide dose-dependently delayed the interval between immunization and onset of clinical EAN, as well as the severity of EAN symptoms. These clinical effects were associated with dose-dependent down-modulation of PNS antigen-induced T and B cell responses and with suppression of the proinflammatory cytokines IL-12, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) mRNA. In PNS sections, Linomide suppressed IL-12 and TNF-alpha, and up-regulated IL-10 mRNA expression. These findings suggest that Linomide could be useful in certain T cell-dependent autoimmune diseases.

Adjuvants, Immunologic↗

Involvement of cyclooxygenase-1 and -2 in the sciatic nerve of rats with experimental autoimmune neuritis.

The expression of both cyclooxygenase (COX)-1 and COX-2, which are representative enzymes in prostaglandin synthesis, was evaluated in the sciatic nerve of rats with experimental autoimmune neuritis (EAN). Western blot analysis showed that both COX-1 and COX-2 were significantly increased in the sciatic nerve at the peak stage of EAN and declined during the recovery stage. Vascular endothelial cells in normal sciatic nerves immunostained for both COX-1 and COX-2. COX-1 was mainly detected in macrophages, and not in other cell types, while COX-2 was detected in Schwann cells and axons as well as inflammatory macrophages in EAN lesions. This suggests that COXs are involved in the pathogenesis of peripheral demyelinating disease, including EAN, and the major cellular source of both COXs in EAN lesions is inflammatory macrophages. Furthermore, COX-2 is enhanced in some Schwann cells and neural elements, possibly mediating peripheral nervous system inflammation.

Animals↗