P0 myelin protein produces experimental allergic neuritis in Lewis rats

P0 protein was prepared from bovine spinal root myelin. The purity was shown by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunostaining with affinity purified antisera. P0 in the presence of lysophosphatidylcholine induced paralysis and histological lesions resembling experimental allergic neuritis in Lewis rats. Lysophosphatidylcholine also enhanced the ability of P2 to produce neuritis. The conformation of these proteins may be important in determining their ability to induce experimental allergic neuritis. P0 deserves consideration as an antigen relevant to Guillain-Barré syndrome.     

Anti-cytokine autoantibodies in experimental autoimmune neuritis in Lewis rats

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-Barre syndrome (GBS) in humans. Cytokine production has been suggested to act a pathogenic role for EAN. To study the potential role of cytokines in context with cytokine autoantibodies (Aabs) in EAN, we used in situ hybridization to detect mRNA expression of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, IL-4, IL-10, and transforming growth factor (TGF)-beta in lymph node mononuclear cell (MNC) and in sciatic nerve sections, as well as ELISA for detection of their autoantibodies in sera and cerebrospinal fluid (CSF) over the course of EAN. Increased mRNA expression for IFN-gamma and TNF-alpha was registered correlating with the peak of clinical signs of EAN, and high levels of mRNA expression for IL-4, IL-10, and TGF-beta were associated with EAN recovery. The levels of cytokine mRNAs were generally inversely correlated to their autoantibodies in serum and CSF, whereby the CSF levels were equal to or lower than the serum levels. Autoantibodies to IFN-gamma dose-dependently inhibited IFN-gamma-induced MHC expression by peritoneal macrophages proving a neutralizing biological effect of these autoantibodies. Our data demonstrate the existence of the anti-cytokine autoantibodies in the sera and CSF of rats with EAN; however, the role of anti-cytokine autoantibodies in the disease process of EAN remains to be resolved.     

Antigen-specific inhibition of the adoptive transfer of experimental autoimmune encephalomyelitis in Lewis rats.

The efficacy of antigen-specific immunoregulation as a treatment for the efferent limb of an autoimmune disease was tested in a rat model of adoptive experimental autoimmune encephalomyelitis (EAE). Lewis rats receiving 4-5 x 10(7) guinea pig (GP) myelin basic protein (MBP)-activated lymph node T cell blasts from GPMBP/CFA sensitized donors routinely show clinical signs of disease 5-6 days post transfer. Intravenous injection of GPMBP coupled to syngeneic splenocytes using the chemical cross-linker carbodiimide was effective in completely abrogating the expression of clinical EAE in rats that received MBP-specific T cells 2 days previously. Partial inhibition was also observed in rats injected as early as day 0 (the same day as MBP-specific T cell transfer) and as late as 1 day prior to the onset of clinical signs (days 4-5 post transfer). Unresponsiveness was shown to be dose-dependent, dependent on the route of injection of the neuroantigen-coupled splenocytes, and was antigen-specific. Splenocytes coupled with GP or rat MBP (which are identical within the major encephalitogenic GP68-86 Lewis rat determinant with the exception of the residue at position 80) were equally efficient at eliminating disease expression in recipients of GPMBP-specific T cells. In contrast, splenocytes coupled with bovine or rabbit MBP (which differ significantly from GPMBP within the 68-86 region) had no inhibitory effect. The antigen specificity of the tolerance induction was also illustrated by the fact that splenocytes coupled with GP68-86, but not those coupled with the truncated GP68-84 peptide, induced profound unresponsiveness. Interestingly, de novo antigen processing by the antigen-coupled cells did not appear to be necessary as the inclusion of antigen processing inhibitors had no effect on inhibition of disease. However, the use of the carbodiimide coupling reagent was critical for the induction of unresponsiveness as essentially equivalent amounts of 125I-labelled MBP were bound in its presence or absence, but only splenocytes incubated in the presence of both MBP and carbodiimide inhibited clinical expression of disease. Antigen-specific tolerance is thus an effective means of inhibiting expression of clinical disease in the rat EAE model, and a powerful tool for determining the fine epitope specificity of encephalitogenic T cells.     

P0 glycoprotein peptides 56-71 and 180-199 dose-dependently induce acute and chronic experimental autoimmune neuritis in Lewis rats associated with epitope spreading

Two synthetic peripheral nerve myelin P0 protein peptides, an immunodominant (amino acids 180-199) and a cryptic (amino acids 56-71) one, induced an acute or chronic course of experimental autoimmune neuritis (EAN) in Lewis rats, when given at low dose (50-100 microg/rat) or high dose (250 microg/rat), respectively. Corresponding to the different clinical course, pathological changes and immune responses were found: (1) Onset of clinical signs of P0 peptide 56-71 (P0 56-71) induced EAN was 1-3 days later than in P0 peptide 180-199 (P0 180-199) induced EAN at all immunizing doses, whereas the peak of the disease occurred at a similar time point post immunization (p.i.), i.e. at days 14-16 p.i. in P0 56-71 induced EAN and at day 16 p.i. in P0 180-199 induced EAN. (2) Intramolecular epitope spreading as assessed by delayed type hypersensitivity response occurred in P0 56-71 induced EAN at both low and high antigen doses and in P0 180-199 induced EAN at high antigen dose (250 microg/rat) only. (3) P0 180-199 stimulated higher levels of interferon-gamma production in P0 180-199 induced EAN than in P0 56-71 induced EAN and vice versa. (4) Histopathologic evaluation revealed a similar grade of mononuclear cell infiltration in the sciatic nerves of both types of EAN, but more severe demyelination was found in P0 180-199 induced EAN compared to P0 56-71 induced EAN. The results support the hypothesis that high dose autoantigen immunization induces extensive determinant spreading and chronic course of autoimmune diseases.     

Antigen-specific inhibition of the adoptive transfer of experimental autoimmune enceophalomyelitis in Lewis rats

The efficacy of antigen-specific immunoregulation as a treatment for the efferent limb of an autoimmune disease was tested in a rat model of adoptive experimental autoimmune encephalomyelitis (EAE). Lewis rats receiving 4–5 × 10⁷ guinea pig (GP) myelin basic protein (MBP)-activated lymph node T cell blasts from GPMBP/CFA sensitized donors routinely show clinical signs of disease 5–6 days post transfer. Intravenous injection of GPMBP coupled to syngeneic splenocytes using the chemical cross-linker carbodiimide was effective in completely abrogating the experssion of clinical EAA in rats that received MBP-specific T cells 2 days previously. Partial inhibition was also observed in rats injected as early as day 0 (the same day as MBP-specific T cell transfer) and as late as 1 day prior to the onset of clinicla signs (days 4–5 post trasfer). Unresponsiveness was shwon to be dose-dependent, dependent on the route of injection of the neuroantigen-coupled splenocytes, and was antigen-specific. Splenocytes coupled with GP or rat MBP (which are identical within the major encephalitogenic GP68–86 Lewis rat determinant with the exception of the residue at position 80) were equally efficient at eliminating disease expression in recipients of GPMBP-specific T cells. In contrast, splenocytes coupled with bovine or rabbit MBP (which differ significantly from GPMBP within the 68–86 region) had no inhibitory effects. The antigen specificity of the tolerance induction was also illustrated by the fact that splenocytes coupled with GP68–86, but not those coupled with the truncated GP68–84 peptide, induced profound unresponsiveness. Interestingly, de novo antigen processing by the antigen-coupled cells did not appear to be necessary as the inclusion of antigen processing inhibitors had no effect on inhibition of disease. However, the use of the carbodiimide couplign reagent was critical for the induction of unrespnosiveness as essentially equivalent amounts of ¹²⁵I-labelled MBP were bound in its presence or absence, but only splenocytes incubated in the presence of both MBP and carbodiimide inhibited clinical expression of disease. Antigen-specific tolerance is thus an effective means of inhibiting expression of clinical disease in teh rat EAE model, and a powerful tool for determining the fine epitope specificity of encephalitogenic T cells.     

丙戊酸对实验性自身免疫性神经炎大鼠保护作用的机制

目的观察丙戊酸(VAP)对实验性自身免疫性神经炎(EAN)大鼠的保护作用及其机制。方法实验大鼠随机分为VAP高剂量组、VAP低剂量组、EAN模型组、正常组,应用P2 57-81多肽与完全弗氏佐剂的混合液诱导EAN模型。VAP于免疫当天至第15d每天腹腔内注射。观察各组大鼠发病情况和坐骨神经组织病理学变化,检测外周血中Th17细胞和Foxp3+Treg细胞含量,检测淋巴结中TNF-α、IFN-γ、IL-17、TGF-βmRNA表达。结果 VAP高剂量组的最初发病时间迟于EAN组(P<0.05),其高峰期临床评分显著低于EAN组(P<0.05),坐骨神经炎性细胞浸润较EAN组明显减少;VAP高剂量组和低剂量组外周血中Th17细胞比例较EAN组显著减少(P<0.05),Foxp3+Treg细胞比例较EAN组显著增加(P<0.05),淋巴结中促炎细胞因子TNF-α、IFN-γ及IL-17mRNA表达与EAN组比较明显下降(P<0.05),VAP高剂量组抑炎细胞因子TGF-βmRNA表达与EAN组比较明显升高(P<0.05)。结论 VAP对EAN有治疗作用,这种作用可能与其能够增加Foxp3+Treg细胞和抑炎细胞因子TGF-β含量、减少TH17细胞含量和促炎细胞因子的表达有关。     

双类似物鼻粘膜耐受对实验性自身免疫性重症肌无力的影响

目的　在实验性自身免疫性重症肌无力 (EAMG)动物模型采用双类似物进行鼻粘膜免疫耐受 ,观察其临床及免疫功能变化 ,评价疗效并探讨其作用机制。方法　建立Lewis大鼠EAMG动物模型 ,选取经预实验证实有效的最低剂量为治疗量 ,检测致敏同时 (A组 )和缓解期第 1天 (B组 )给予双类似物鼻粘膜免疫耐受治疗后 ,大鼠体重、临床症状、致敏第 35天血清抗AChR抗体IgG含量及其淋巴细胞在不同刺激原作用下的增殖情况。结果　 (1 )治疗后EAMG大鼠体重增加 ,临床症状缓解。 (2 )治疗后血清抗AChR抗体IgG含量 (吸光度 ,A值 ) :A组 (0 98± 0 2 4 )和B组 (0 95± 0 2 6)均少于各自对照组 (分别为 1 1 8± 0 1 0和 1 1 9± 0 1 2 ) ,但A、B组间差异无显著意义。 (3)针对AChR等特异性抗原的淋巴细胞增殖指数 :A组 (1 71± 0 78)和B组 (1 97± 0 56)与对照组 (3 2 4± 1 31和 3 1 9±1 50 )相比均减低 ,增殖反应明显受抑制。结论　双类似物鼻粘膜耐受能明显缓解EAMG的肌无力症状 ,并伴有特异性T、B细胞免疫功能抑制     

预防性双类似物鼻粘膜耐受对EAMG的影响

目的选择双类似物(Lys262-Ala207)通过不同时间点对实验性自身免疫性重症肌无力(EAMG)模型进行鼻粘膜耐受预防性给药,观察其临床及免疫指标变化,并评价疗效,探讨预防性鼻粘膜耐受在EAMG中的预防作用机制。方法应用乙酰胆碱受体(AChR)加CFA致敏Lewis大鼠建立EAMG模型,并在致敏前10 d(预防耐受A组)及致敏当日(预防耐受B组)给予耐受肽Lvs262-Ala207及相应对照组CA、CB采用相同剂量对照肽MBP-p83-99鼻腔给药。检测给药后A、B组及相应对照组大鼠的体重、临床评分、肌电图、肌肉中AChR含量丢失变化及致敏第42 d血清抗AChR抗体IgG含量。结果急性期和慢性期A、B组体重明显超过相应对照组,临床症状明显轻于相应对照组,慢性期A组体重明显超过B组、病情明显轻于B组;A、B组低频重复电刺激出现衰减反应D5阳性率低于相应对照组;A、B组肌肉AChR含量丢失分别明显低于相应对照组,而A组低于B组;慢性期42 d A、B组IgG含量明显低于相应对照组,同时A组明显低于B组。结论本实验表明,预防耐受的疗效与自身免疫启动时间有关,启动前优于启动时耐受;双类似物鼻粘膜耐受预防不仅可有效地抑制临床症状,且可特异性减低致病性循环抗体含量和减少神经肌接头AChR含量丢失,为采用双类似物鼻粘膜耐受防治人类重症肌无力(MG)提供了依据。     

Modulation of experimental autoimmune neuritis in Lewis rats by oral application of myelin antigens

Experimental autoimmune neuritis (EAN) in Lewis rats is a T cell-mediated disease and serves as an animal model of human inflammatory demyelinating neuropathies. EAN can be induced by immunization with complete bovine peripheral nerve myelin (BPM), the myelin protein P2 or its neuritogenic peptide, each emulsified in complete Freund's adjuvant (CFA). The present study evaluates the effect of oral tolerization with BPM or P2 protein on the development of actively induced EAN. Oral administration of BPM strongly suppressed clinical and histological signs of EAN subsequently induced by BPM/CFA, but feeding of P2 protein alone did not affect its course. In contrast, feeding of BPM did not mitigate the course of EAN subsequently induced by immunization with neuritogenic P2 peptide/CFA. Oral therapy with BPM after onset of myelin-induced EAN only slightly ameliorated the further course of disease, but significantly reduced lethality of this severe form of disease. The findings suggest that immunogenicity of the antigens fed determine strength of tolerance, that downregulation of EAN occurs at the site of immunization and not in the nerve, and that active suppression rather than specific anergization is operative in mediating resistance to EAN. However, only partial tolerance to myelin-induced EAN was achieved in naive animals by transfer of spleen/LN cells from rats orally tolerized with BPM. Although methodic factors may have limited the effect of the cells, the result is suggestive of some contribution of anergy to oral tolerance in the present model. Cholera toxin and LPS were identified as oral adjuvants for BPM and prolonged the state of tolerance. However, LPS exhibited proinflammatory properties if EAN was induced early after BPM/LPS-feeding. Thus, oral application of a mixture of myelin components in combination with cholera toxin may be a useful treatment for chronic inflammatory neuropathies considered autoimmune in nature.     

Oral tolerance in experimental autoimmune neuritis (EAN) of the Lewis rat. II. Adjuvant effects and bystander suppression in P2 peptide-induced EAN

Experimental autoimmune neuritis (EAN) in Lewis rats serves as an animal model of human inflammatory demyelinating neuropathies. We previously demonstrated that EAN actively induced by immunization with bovine PNS-myelin can be suppressed by feeding of myelin. This myelin-specific oral tolerance (OT) was enhanced by coapplication of cholera toxin (CT).In the present study, EAN induced by immunization with a neuritogenic P2 peptide was completely prevented by precedent feeding of the peptide. Oral application of the P2 peptide mediated tolerance as efficient as did nasal administration. In contrast to OT by myelin, addition of CT completely prevented oral induction of tolerance to peptide-induced EAN, while adjuvant feeding alone did not modulate disease. As a possible immunological basis to explain the prevention of OT induction by CT, we identified a highly enhanced protein-specific in vitro proliferation of splenocytes from antigen/CT-fed animals compared to those of rats fed with the antigen only.The opposite effects of oral CT in combination with proteins versus myelin confirm our former assumption that CT augments myelin-induced tolerance by its binding to gangliosides present in the myelin but not in the P2 peptide solution, while free CT prevents the induction of OT. It is suggested that CT is a useful adjuvant for OT if coadministered with myelin, but requires chemical linkage to proteins to exert this function. Regulatory lymphocytes orally induced by feeding the protein keyhole limpet hemocyanine (KLH) slightly ameliorated peptide-induced EAN via bystander mechanisms, but injection of KLH in close proximity to the site of peptide-immunization was essential. The restriction of bystander suppression to that site in the lymphoid system where neuritogenic T cells are activated may limit the impact of OT as a bonafide treatment strategy in human autoimmune diseases and underscores the necessity to identify the autoantigens involved.     

Increased phosphorylation of caveolin-1 in the sciatic nerves of Lewis rats with experimental autoimmune neuritis

The levels of phosphorylated caveolin-1 (p-caveolin-1) were analyzed in the sciatic nerves of Lewis rats with experimental autoimmune neuritis (EAN). Western blot analysis showed that the phosphorylation of caveolin-1 increased significantly in the sciatic nerves of EAN-affected rats at the paralytic stage of EAN on day 14 post-immunization (PI) (P<0.05) and declined slightly thereafter during the recovery stage. Immunohistochemistry showed intense p-caveolin-1 immunostaining in some inflammatory macrophages, as well as in T-cells in individual nerve fascicles at the peak stage of EAN, while p-caveolin-1 was weakly expressed in some of the vascular endothelial cells and Schwann cells of normal sciatic nerves. The inflammatory cells with intense p-caveolin-1 expression in the EAN-affected individual nerve fascicles were not positive for terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), while the TUNEL-positive apoptotic cells in the perineurium, where infiltration initially occurred, were weakly positive for p-caveolin-1. Based on these findings, we postulate that caveolin-1 is phosphorylated in inflammatory cells soon after they infiltrate the sciatic nerve, as well as in the perineurium, and that p-caveolin-1 activates intracellular signaling in inflammatory cells, leading to cell death, which ultimately eliminates the infiltrating inflammatory cells from the sciatic nerves of animals with EAN.     

IFN-beta suppresses experimental autoimmune neuritis in Lewis rats by inhibiting the migration of inflammatory cells into peripheral nervous tissue.

The putative prophylactic and therapeutic effect of interferon-beta (IFN-beta) on autoimmune inflammation of the peripheral nervous system was evaluated in experimental autoimmune neuritis (EAN), a well-known animal model of the human Guillain-Barré syndrome (GBS). We report that treatment of rats with 300,000 U of recombinant rat IFN-beta (rrIFN-beta) given every other day starting at the day of immunization prevented clinical signs of EAN. When treatment was started at the onset of disease development, the cytokine clearly ameliorated EAN. Both B- and T-cell responses towards peripheral myelin were suppressed by the IFN-beta, and immunohistochemical analyses revealed a strong decrease in the numbers of infiltrating CD4(+) T cells, macrophages, and other inflammatory cells as well as a significant reduction in MHC class II antigen expression and monocyte chemotactic protein-1 (MCP-1) production, which induces chemotaxis and chemokinesis of leukocytes from blood. It is concluded that the observed suppression of EAN by rrIFN-beta is associated with a decrease in the migration of inflammatory cells into peripheral nervous tissue.     

Increased lipocortin-1 (annexin-1) expression in the sciatic nerve of Lewis rats with experimental autoimmune neuritis

Lipocortin-1 exerts a potent immunosuppressive effect on pathogenic T cells. In multiple sclerosis and experimental autoimmune encephalomyelitis levels of lipocortins are raised, suggesting their involvement in the recovery from an immunological insult or in neural regeneration. To further understand the role of lipocortins in the peripheral nervous system we have characterized lipocortin-1 levels and cellular distribution of lipocortin-1 immunoreactivity in sciatic nerves of rats with experimental autoimmune neuritis (EAN), a model of human Guillain-Barré syndrome. EAN was induced actively by immunization with bovine peripheral myelin (active EAN) or by adoptive-transfer (AT-EAN) of P2-specific T cells. Cellular infiltrates in serial and semithin cryosections were characterized by immunohistochemistry. In parallel, lipocortin-1 levels in tissue extracts were quantified by a sandwich-ELISA. Only weak lipocortin-1 immunoreactivity was found in nerves of control animals injected with non-pathogenic T cells. The majority of macrophages and lymphocytes in EAN lesions exhibited lipocortin-1 immunoreactivity. Some very heavily stained cells showed a distribution and morphology similar to ED-2-positive macrophages which were abundant during early stages of EAN. Lipocortin-1 expression in T cells and macrophages was proven by immunocytochemical studies in semithin serial sections. In tissue extracts, lipocortin-1 levels increased from 0.24 ± 0.14 μg/mg protein in controls receiving non-pathogenic T cells to a maximum of 0.55 ± 0.1 μg/mg protein in AT-EAN at the peak of disease, and then slowly decreased during clinical recovery but still remained elevated. In dose-response studies in AT-EAN, highest values of lipocortin-1 (0.71 ± 0.23 μg/mg protein) were recorded after transfer of 2 × 10⁷ T cells. Increased levels of lipocortin-1 were also measured in active EAN but occurred during the recovery phase (0.65 ± 0.27 μg/mg protein). By analogy with other immune-mediated disorders, increased lipocortin-1 expression in the inflamed sciatic nerve in EAN may exert immunoregulatory functions in-situ and contribute to the termination of the autoimmune response. Received: 20 May 1999 / Accepted: 12 July 1999     

New cyclooxygenase-2 inhibitors for treatment of experimental autoimmune neuritis

We analyzed two new cyclooxygenase-2 (COX-2) inhibitors, celecoxib (SC-58635) and meloxicam, for the treatment of experimental autoimmune neuritis (EAN) in rats. Celecoxib and meloxicam significantly reduced clinical EAN score and histopathological damage of the sciatic nerve. They induced no serious side effects, whereas indomethacin used as a control caused severe intestinal ulceration and dysfunction of liver and kidney. These findings suggest that the new COX-2 inhibitors may be useful as additional therapeutic agents for patients with Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy.     

Neurophysiological changes in demyelinating and axonal forms of acute experimental autoimmune neuritis in the Lewis rat

Myelin-sensitized T- and B-cells (lymph node cells) induced experimental autoimmune neuritis (EAN) in Lewis rats after passive transfer to naive recipients. After 6 days, all recipient rats developed tail paresis that progressed to limb paresis within 12-72 h. Progressive nerve conduction changes consistent with demyelination in the sciatic nerve (conduction block and prolongation of the distal motor latencies) and lumbar nerve roots (initial low F-wave frequencies followed by later prolongation in F-wave latencies) were observed during the disease. For comparison, adoptive transfer experimental autoimmune neuritis (AT-EAN) of differing disease severity was induced by titrating the dose of P2-specific T-cells. In contrast to EAN induced by myelin-sensitized T- and B-cells, AT-EAN was predominantly associated with rapid nerve conduction changes consistent with axonal dysfunction and degeneration. These findings demonstrate that distinct forms of EAN with different pathophysiological mechanisms are induced by the passive transfer of P2-specific T-cell lines or myelin-specific T-cells and B-cells. The electrophysiological changes in EAN induced by myelin-specific T- and B-cells are very similar to those seen clinically during acute inflammatory demyelinating polyneuropathy, whereas AT-EAN has less resemblance to axonal forms of Guillain-Barré syndrome.     

Chronic relapsing experimental allergic neuritis in Lewis rats: Effects of thymectomy and splenectomy

Summary Experimental allergic neuritis (EAN) was induced in Lewis rats aged 4 months by the inoculation of whole bovine dorsal root with Freund's complete adjuvant. Prolonged follow-up demonstrated that a relapsing course is a regular feature of the disorder in animals at this age. Although the initial disease episode was the most severe, clinical recovery from subsequent relapses was less satisfactory, this probably being related to persistent morphological abnormalities in the peripheral nervous system. Antecedent thymectomy, splenectomy, or the two combined, had little effect on the clinical course of the disorder, apart from reducing the duration of relapses. This was only statistically significant following combined thymectomy/splenectomy. Histological abnormalities, however, tended to be less severe in the operated as compared with normal control or sham-operated animals with EAN. The animals must have attained an immunocompetent state at the time of thymectomy and/or splenectomy. The capacity to develop EAN presumably resides in the draining lymph nodes and the occurrence of relapses is due to the continuing presence of antigen at the injection sites.Supported by the National Fund for Research into Crippling Diseases and the Medical Research Council     

Inflammation and proinflammatory cytokine production,but no demyelination of facial nerves,in experimental autoimmune neuritis in Lewis rats

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. The facial nerve paralysis is relatively commonly found in GBS patients. Here, EAN was established in Lewis rats by immunization with P2 peptide 57–81, a purified component of peripheral nerve myelin, and Freund's complete adjuvant (FCA). To study whether the facial nerves are involved in the pathogenic process during the EAN course, we observed the clinical and pathological changes as well as cytokine production in facial nerves on Day 14 postimmunization (p.i.), i.e. at height of clinical EAN. As a result, all rats immunized with P2 peptide 57–81 developed severe EAN on Day 14 p.i., but none of the rats manifested clinical signs of facial nerve paralysis. Additionally, only mild inflammatory cell infiltration and proinflammatory cytokine, interferon-γ (IFN-γ) and tumour necrosis factor (TNF-) production as well as devoid demyelination were seen in facial nerves of the EAN rats. On the contrary, severe inflammation and demyelination as well as upregulated IFN-γ and TNF- production were observed in sciatic nerves of the same EAN rats. The underlying mechanism for the difference of the local manifestation of the disease process of EAN remains to be resolved.     

Evoked potential and behavioral outcomes for experimental autoimmune encephalomyelitis in Lewis rats

A reliable outcome measurement is needed to assess the effects of experimental lesions in the rat spinal cord as well as to assess the benefits of therapies designed to modulate them. The Basso, Beattie, and Bresnahan (BBB) behavioral scores can be indicative of the functionality in motor pathways. However, since lesions are often induced in the more accessible dorsal parts associated with the sensory pathways, the BBB scores may not be ideal measure of the disability. We propose somatosensory evoked potential (SEP) as a complementary measure to assess the integrity of sensory pathways. We used the focal experimental autoimmune encephalomyelitis (EAE) model, in which focal demyelinating lesions were induced by injecting cytokine-ethidium bromide into dorsal white matter after MOG-IFA immunization. Both the SEP and BBB measures reflected injury; however, the SEP was uniformly and consistently altered after the injury whereas the BBB varied widely. The results suggest that the SEP measures are more sensitive and reliable markers of focal spinal cord demyelination compared to the behavioral measures like the BBB score.     

T-cell receptor Vβ-element expression in peripheral nerves of Lewis rats suffering from experimental autoimmune neuritis

In experimental autoimmune neuritis (EAN), peripheral nerves are infiltrated by T-lymphocytes and macrophages. By RT-PCR and sequence analysis we characterized TCR Vβ-element usage in sciatic nerve tissue of Lewis rats suffering from EAN induced by immunization with peripheral myelin antigens. Several TCR Vβ-chain sequences were detected, which did not show homology to sequences of P2-reactive T cells published so far. In EAN induced with peripheral nerve myelin, but not with P2-protein or P2 peptide aa 53–78, TCR Vβ 8.2 sequences identical to sequences of encephalitogenic myelin basic protein (MBP) reactive T-cells were identified. These results provide further evidence for a contribution of MBP-directed T-cell reactivity to the pathogenesis of myelin induced EAN and may have implications for the pathogenesis of human demyelinating neuropathies.