Endothelin-1 contributes to the development of virus-induced demyelinating disease.

BACKGROUND: Experimental autoimmune encephalitis (EAE) and virally induced demyelinating disease are two major experimental model systems used to study human multiple sclerosis. Although endothelin-1 level elevation was previously observed in the CNS of mice with EAE and viral demyelinating disease, the potential role of endothelin-1 in the development of these demyelinating diseases is unknown. METHODS AND RESULTS: In this study, the involvement of endothelin-1 in the development and progression of demyelinating diseases was investigated using these two experimental models. Administration of endothelin-1 significantly promoted the progression of both experimental diseases accompanied with elevated inflammatory T cell responses. In contrast, administration of specific endothelin-1 inhibitors (BQ610 and BQ788) significantly inhibited progression of these diseases accompanied with reduced T cell responses to the respective antigens. CONCLUSIONS: These results strongly suggest that the level of endothelin-1 plays an important role in the pathogenesis of immune-mediated CNS demyelinating diseases by promoting immune responses.

The role of α4 integrin in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease: an infectious animal model for multiple sclerosis (MS).

Natalizumab, which is an antibody against α4 integrin, has been used for the treatment of multiple sclerosis. In the present study, we investigated both the role of α4 integrin and the therapeutic effect of HCA3551, a newly synthesized orally active small molecule α4 integrin antagonist, in the development of Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD). The mRNA levels of α4 integrins were significantly up-regulated in the central nervous system (CNS) of mice with TMEV-IDD as compared with naive mice (*P < 0.05). HCA3551 treatment in the effector phase significantly suppressed both the clinical and histological development of TMEV-IDD. The number of infiltrating mononuclear inflammatory cells in the CNS was significantly decreased in the mice treated with HCA3551 (**P < 0.01). The labeling indices for CD68 antigen and the absolute cell numbers of TNF-α-producing CD4+ T cells and IFN-γ-producing CD8+ T cells were significantly decreased in the CNS of mice treated with HCA3551 (*P < 0.05). HCA3551 treatment in the effector phase might inhibit the binding of α4 integrin to vascular cell adhesion molecule-1, thereby decreasing the number of mononuclear cells in the CNS.

Dimethyl fumarate suppresses Theiler's murine encephalomyelitis virus-induced demyelinating disease by modifying the Nrf2-Keap1 pathway.

Dimethyl fumarate (DMF) is a modifier of the nuclear factor (erythroid-derived 2)-2 (Nrf2)-kelch-like ECH-associated protein 1 (Keap1) pathway. DMF treatment in the effector phase significantly suppressed the development of Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD) both clinically and histologically. DMF treatment leads to an enhanced Nrf2 antioxidant response in TMEV-IDD mice. DMF treatment in the effector phase significantly suppressed the level of IL-17A mRNA. DMF is known to inhibit differentiation of T helper 17 (Th17) cells via suppressing NF-κB. Taken together, our data suggest that DMF treatment in the effector phase may suppress TMEV-IDD not only via enhancing the antioxidant response but also via suppressing IL-17A.

Role of the Programmed Death-1 (PD-1) pathway in regulation of Theiler's murine encephalomyelitis virus-induced demyelinating disease.

Programmed death-1 (PD-1) belongs to the CD28 family of co-stimulatory and co-inhibitory molecules and regulates adaptive immunity. This molecule induces the development of regulatory T cells, T cell tolerance, or apoptosis. We examined the role of PD-1 pathway in Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease (TMEV-IDD) mice. Up-regulation of PD-1 and PD-1 ligand-1 (PD-L1) mRNA expression in bone marrow-derived dendritic cells were induced by TMEV infection in vitro. Furthermore, PD-1 and PD-L1 mRNA expression was increased in the spinal cords of the TMEV-infected mice in vivo. Treatment with a blocking monoclonal antibody (mAb) against PD-1, especially during the effector phase, resulted in significant deterioration of the TMEV-IDD both clinically and histologically. Flow cytometric analysis revealed a dramatically increase of CD4(+) T cells producing Th1 cytokines such as IFN-γ and TNF-α in the spinal cord of anti-PD-1 mAb-treated mice. These results indicate that the PD-1 pathway plays a pivotal regulatory role in the development of TMEV-IDD.

Cytokine production profiles in chronic relapsing-remitting experimental autoimmune encephalomyelitis: IFN-γ and TNF-α are important participants in the first attack but not in the relapse.

Multiple sclerosis (MS) is a chronic demyelinating disease often displaying a relapsing-remitting course of neurological manifestations that is mimicked by experimental autoimmune encephalomyelitis (EAE) in animal models of MS. In particular, NOD mice immunized with myelin oligodendrocyte glycoprotein peptide 35-55 develop chronic relapsing-remitting EAE (CREAE). To elucidate the mechanisms that cause MS relapse, we investigated the histopathology and cytokine production of spleen cells and mRNA expression levels in the central nervous system (CNS) of CREAE mice. During the first attack, inflammatory cell infiltration around small vessels and in the subarachnoid space was observed in the spinal cord. Spleen cell production and mRNA expression in the CNS of several cytokines, including IFN-γ, TNF-α, IL-6, IL-17, and CC chemokine ligand 2 (CCL2), were higher in CREAE mice than in controls. Afterwards, parenchymal infiltration and demyelination were observed histologically in the spinal cord and corresponded with the more severe clinical symptoms of the first and second relapses. IL-17 and CCL2, but not IFN-γ, TNF-α, or IL-6, were also produced by spleen cells during recurrences. Our results suggested that the immune mechanisms in relapses were different from those in the first attack for CREAE. Further investigation of CREAE mechanisms may provide important insights into successful therapies for human relapsing-remitting MS.

The TIM-3 pathway ameliorates Theiler's murine encephalomyelitis virus-induced demyelinating disease.

Infection by Theiler's murine encephalomyelitis virus (TMEV) in the central nervous system (CNS) induces an immune-mediated demyelinating disease in susceptible mouse strains and serves as a relevant infection model for human multiple sclerosis. T-cell immunoglobulin and mucin domain-3 (TIM-3) has been demonstrated to play a crucial role in the maintenance of peripheral tolerance. In this study, we examined the regulatory role of the TIM-3 pathway in the development of TMEV-induced demyelinating disease (TMEV-IDD). The expression of TIM-3 was increased at both protein and mRNA levels in the spinal cords of mice with TMEV-IDD compared with naive controls. In addition, by utilizing a blocking mAb, we demonstrate that TIM-3 negatively regulates TMEV-specific ex vivo production of IFN-γ and IL-10 by CD4(+) T cells and IFN-γ by CD8(+) T cells from the CNS of mice with TMEV-IDD at 36 days post-infection (dpi). In vivo blockade of TIM-3 by using the anti-TIM-3 mAb resulted in significant exacerbation of the development of TMEV-IDD both clinically and histologically. The number of infiltrating mononuclear cells in the CNS was also increased in mice administered with anti-TIM-3 mAb both at the induction phase (10 dpi) and at the effector phase (36 dpi). Flow cytometric analysis of intracellular cytokines revealed that the number of CD4(+) T cells producing TNF, IL-4, IL-10 and IL-17 was significantly increased at the effector phase in the CNS of anti-TIM-3 mAb-treated mice. These results suggest that the TIM-3 pathway plays a critical role in the regulation of TMEV-IDD.

Therapeutic effect of anti-αv integrin mAb on Theiler's murine encephalomyelitis virus-induced demyelinating disease.

We examined the regulatory role of αv integrins in the development of Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), a model of multiple sclerosis (MS). Blockade of αv integrins by anti-αv integrin monoclonal antibody (mAb) in the effector phase significantly suppressed the development of TMEV-IDD both clinically and histologically. The number of infiltrating mononuclear cells (MNCs) in the CNS was significantly decreased in mice treated with anti-αv integrin mAb. Flow cytometric analysis of cytokine staining revealed that absolute numbers of IFN-γ- and IL-17-producing CD4+ and IFN-γ-producing CD8+ T cells were significantly decreased in the CNS of mice treated with anti-αv integrin mAb. These data suggest that αv integrins may play important roles in the development of TMEV-IDD.

The role of interleukin-6 in the expression of PD-1 and PDL-1 on central nervous system cells following infection with Theiler's murine encephalomyelitis virus.

Infection with Theiler's murine encephalomyelitis virus (TMEV) in the central nervous system (CNS) of susceptible mice results in an immune-mediated demyelinating disease which is considered a relevant viral model of human multiple sclerosis. We previously demonstrated that the expression of positive costimulatory molecules (CD40, CD80, and CD86) is higher on the microglia of TMEV-resistant C57BL/6 (B6) mice than the microglia of TMEV-susceptible SJL/J (SJL) mice. In this study, we analyzed the expression levels of the negative costimulatory molecules PD-1 and PDL-1 in the CNS of TMEV-infected SJL mice and B6 mice. Our results indicated that TMEV infection induces the expression of both PD-1 and PDL-1 on microglia and macrophages in the CNS but not in the periphery. The expression of PD-1 only on CNS-infiltrating macrophages and not on resident microglia was considerably higher (>4-fold) in TMEV-infected SJL mice than TMEV-infected B6 mice. We further demonstrated that interleukn-6 (IL-6) is necessary to induce the maximal expression of PDL-1 but not PD-1 after TMEV infection using IL-6-deficient mice and IL-6-transgenic mice in conjunction with recombinant IL-6. In addition, cells from type I interferon (IFN) receptor knockout mice failed to upregulate PD-1 and PDL-1 expression after TMEV infection in vitro, indicating that type I IFN signaling is associated with the upregulation. However, other IFN signaling may also participate in the upregulation. Taken together, these results strongly suggest that the expression of PD-1 and PDL-1 in the CNS is primarily upregulated following TMEV infection via type I IFN signaling and the maximal expression of PDL-1 additionally requires IL-6 signaling.

Downregulation of water channel aquaporin-4 in rats with experimental autoimmune encephalomyeritis induced by myelin basic protein.

Characteristics of myelin basic protein (MBP)-induced experimental autoimmune encephalomyelitis (EAE) include acute edema and infiltration of mononuclear cells (MNCs) in the microvessels of central nervous system (CNS). Aquaporin-4 (AQP4) is a water channel protein expressed in astrocytes foot process throughout the CNS. We performed immunostaining, western blotting and semi-quantitative real-time RT-PCR of AQP4 and glial fibrillary acidic protein (GFAP) in CNS from rats immunized with MBP. Immunohistochemical analysis revealed that AQP4 is down-regulated in MNCs infiltrated microvessels of rats with EAE. Furthermore, western blotting and real-time RT-PCR analyses showed that AQP4 was significantly decreased at the stage of severe EAE compared with control rats. On the other hand, expression of GFAP-protein was significantly increased after stage of severe EAE. Our findings suggest that AQP4 may be involved in forming edema in the inflammatory lesions of EAE accompanying with up-regulation of reactive astrocyte.

Therapeutic effects of anti-Delta1 mAb on Theiler's murine encephalomyelitis virus-induced demyelinating disease.

We examined the role of Notch ligand Delta-like 1 (Delta1) in the development of Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease (TMEV-IDD). Blocking of Delta1 by anti-Delta1 monoclonal antibody (mAb) in the effector phase significantly suppressed the disease development of TMEV-IDD both clinically and histologically. The number of infiltrating inflammatory mononuclear cells in the spinal cords was also decreased in mice treated with anti-Delta1 mAb at the effector phase. Flow cytometric analysis of cytokine staining revealed that IFN-γ- or IL-4-producing CD4(+) splenocytes were significantly decreased in mice treated with anti-Delta1 mAb in the spleens, whereas IL-10-producing CD4(+) splenocytes were increased. Furthermore, IFN-γ-, TNF-α-, IL-4-, or IL-10-producing CD4(+) cells were decreased in spinal cords, and IL-17-producing CD4(+) cells were increased. These data suggest that Delta1 may play important roles in the development of TMEV-IDD and that antibodies to Delta1 could be used as a novel therapeutic treatment of demyelinating diseases such as human multiple sclerosis.

IL-1 signal affects both protection and pathogenesis of virus-induced chronic CNS demyelinating disease.

BACKGROUND: Theiler's virus infection induces chronic demyelinating disease in mice and has been investigated as an infectious model for multiple sclerosis (MS). IL-1 plays an important role in the pathogenesis of both the autoimmune disease model (EAE) and this viral model for MS. However, IL-1 is known to play an important protective role against certain viral infections. Therefore, it is unclear whether IL-1-mediated signaling plays a protective or pathogenic role in the development of TMEV-induced demyelinating disease. METHODS: Female C57BL/6 mice and B6.129S7-Il1r1tm1Imx/J mice (IL-1R KO) were infected with Theiler's murine encephalomyelitis virus (1 x 106 PFU). Differences in the development of demyelinating disease and changes in the histopathology were compared. Viral persistence, cytokine production, and immune responses in the CNS of infected mice were analyzed using quantitative PCR, ELISA, and flow cytometry. RESULTS: Administration of IL-1ß, thereby rending resistant B6 mice susceptible to TMEV-induced demyelinating disease, induced a high level of Th17 response. Interestingly, infection of TMEV into IL-1R-deficient resistant C57BL/6 (B6) mice also induced TMEV-induced demyelinating disease. High viral persistence was found in the late stage of viral infection in IL-1R-deficient mice, although there were few differences in the initial anti-viral immune responses and viral persistent levels between the WT B6 and IL-1R-deficiecent mice. The initial type I IFN responses and the expression of PDL-1 and Tim-3 were higher in the CNS of TMEV-infected IL-1R-deficient mice, leading to deficiencies in T cell function that permit viral persistence. CONCLUSIONS: These results suggest that the presence of high IL-1 level exerts the pathogenic role by elevating pathogenic Th17 responses, whereas the lack of IL-1 signals promotes viral persistence in the spinal cord due to insufficient T cell activation by elevating the production of inhibitory cytokines and regulatory molecules. Therefore, the balance of IL-1 signaling appears to be extremely important for the protection from TMEV-induced demyelinating disease, and either too much or too little signaling promotes the development of disease.

TLR3 signaling is either protective or pathogenic for the development of Theiler's virus-induced demyelinating disease depending on the time of viral infection.

BACKGROUND: We have previously shown that toll-like receptor 3 (TLR3)-mediated signaling plays an important role in the induction of innate cytokine responses to Theiler's murine encephalomyelitis virus (TMEV) infection. In addition, cytokine levels produced after TMEV infection are significantly higher in the glial cells of susceptible SJL mice compared to those of resistant C57BL/6 mice. However, it is not known whether TLR3-mediated signaling plays a protective or pathogenic role in the development of demyelinating disease. METHODS: SJL/J and B6;129S-Tlr3tm1Flv/J (TLR3KO-B6) mice, and TLR3KO-SJL mice that TLR3KO-B6 mice were backcrossed to SJL/J mice for 6 generations were infected with Theiler's murine encephalomyelitis virus (2 × 105 PFU) with or without treatment with 50 µg of poly IC. Cytokine production and immune responses in the CNS and periphery of infected mice were analyzed. RESULTS: We investigated the role of TLR3-mediated signaling in the protection and pathogenesis of TMEV-induced demyelinating disease. TLR3KO-B6 mice did not develop demyelinating disease although they displayed elevated viral loads in the CNS. However, TLR3KO-SJL mice displayed increased viral loads and cellular infiltration in the CNS, accompanied by exacerbated development of demyelinating disease, compared to the normal littermate mice. Late, but not early, anti-viral CD4+ and CD8+ T cell responses in the CNS were compromised in TLR3KO-SJL mice. However, activation of TLR3 with poly IC prior to viral infection also exacerbated disease development, whereas such activation after viral infection restrained disease development. Activation of TLR3 signaling prior to viral infection hindered the induction of protective IFN-γ-producing CD4+ and CD8+ T cell populations. In contrast, activation of these signals after viral infection improved the induction of IFN-γ-producing CD4+ and CD8+ T cells. In addition, poly IC-pretreated mice displayed elevated PDL-1 and regulatory FoxP3+ CD4+ T cells in the CNS, while poly IC-post-treated mice expressed reduced levels of PDL-1 and FoxP3+ CD4+ T cells. CONCLUSIONS: These results suggest that TLR3-mediated signaling during viral infection protects against demyelinating disease by reducing the viral load and modulating immune responses. In contrast, premature activation of TLR3 signal transduction prior to viral infection leads to pathogenesis via over-activation of the pathogenic immune response.

γ-Secretase-regulated mechanisms similar to notch signaling may play a role in signaling events, including APP signaling, which leads to Alzheimer's disease.

Although γ-secretase was first identified as a protease that cleaves amyloid precursor protein (APP) within the transmembrane domain, thus producing Aß peptides that are thought to be pathogenic in Alzheimer's disease (AD), its physiological functions have not been fully elucidated. In the canonical Notch signaling pathway, intramembrane cleavage by γ-secretase serves to release an intracellular domain of Notch that shows activity in the nucleus through binding to transcription factors. Many type 1 transmembrane proteins, including Notch, Delta, and APP, have recently been shown to be substrates for γ-secretase, and their intracellular domains are released from the cell membrane following cleavage by γ-secretase. The common enzyme γ-secretase modulates proteolysis and the turnover of possible signaling molecules, which has led to the attractive hypothesis that mechanisms similar to Notch signaling contribute widely to proteolysis-regulated signaling pathways. APP is also likely to have a signaling mechanism, although the physiological functions of APP have not been elucidated. Indeed, we have shown that the intracellular domain of APP alters gene expression and induces neuron-specific apoptosis. These results suggest that APP signaling responds to the onset of AD. Here, we review the possibility of γ-secretase-regulated signaling, including APP signaling, which leads to AD.

The amyloid precursor protein intracellular domain alters gene expression and induces neuron-specific apoptosis.

Although amyloid precursor protein (APP) plays a central role in Alzheimer's disease, the physiological functions of this protein have yet to be fully elucidated. As previously reported, we established an embryonic carcinoma P19 cell line expressing the intracellular domain of APP (AICD). While neurons were differentiated from these cell lines with retinoic acid treatment, expression of AICD induced neuron-specific apoptosis. As the first step to identify the genes involved in this process, we evaluated AICD-induced changes in gene expression through cell death. The levels of expression of 41,256 transcripts were monitored by DNA microarray analysis. The expression of 277 genes showed up-regulation by more than 10-fold in the presence of AICD. Conversely, the expression of 341 genes showed down-regulation to less than one-tenth of the original level. Reverse transcription-polymerase chain reaction of 17 selected genes showed excellent agreement with the microarray results. These results suggest that AICD induces dynamic changes in gene expression, which may be closely correlated with AICD-induced neuron-specific apoptosis.

γ-Secretase-regulated signaling pathways, such as notch signaling, mediate the differentiation of hematopoietic stem cells, development of the immune system, and peripheral immune responses.

Notch signaling mediates the fates of numerous cells in both invertebrates and vertebrates. In the immune system, Notch signalling contributes to the generation of hematopoietic stem cells (HSCs), the promotion of HSC self-renewal, T lineage commitment, intrathymic T cell development, and peripheral lymphocyte differentiation/activation. The intracellular domain (ICD) of Notch is released from the cell membrane by γ-secretase and translocates to the nucleus to modulate gene expression. Hence, γ-secretase plays a central role in the regulation of Notch signaling. More than five dozen type 1 transmembrane proteins, including amyloid precursor protein, Notch, and Delta, are substrates for γ-secretase and their ICDs are released from the cell membrane. Therefore, it is highly possible that mechanisms similar to Notch signaling may widely contribute to γ-secretase-regulated signaling. Besides Notch, some transmembrane proteins such as CD44 and CSF-1R, which are important for immune responses, have been reported as substrates for γ-secretase. Since the ICDs of these proteins are also released by γ-secretase from the cell membrane and localize to the nucleus, it is thought that these ICDs modulate gene expression. Thus, γ-secretase-regulated signaling, including Notch signaling, may play a wide range of roles in the immune system.

Ameliorating effects of anti-Dll4 mAb on Theiler's murine encephalomyelitis virus-induced demyelinating disease.

We examined the role of Notch ligand Delta-like 4 (Dll4) in the development of Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease (TMEV-IDD). Treatment with mAb to Dll4, especially during the effector phase, resulted in significant suppression of the disease development both clinically and histologically. The number of infiltrating mononuclear inflammatory cells in the spinal cords was also decreased in mice treated with anti-Dll4 mAb. Semi-quantitative analysis of mRNA by using real-time PCR revealed that mRNAs of T(h)1-derived cytokines such as IFN-gamma and T(h)17-derived cytokines such as IL-17 were decreased in mice treated with anti-Dll4 mAb, whereas those of T(h)2-derived cytokines such as IL-4 and IL-10 were not. Flow cytometric analysis of cytokines indicated that there were no significant differences between mAb-treated mice and control mice in the relative frequency of splenic T(h)1 and T(h)2. However, absolute cell numbers of T(h)1-derived cytokine-producing cells in spinal cord were markedly decreased in mice treated with anti-Dll4 mAb in effector phase compared with control mice treated with non-specific IgG. These data suggest that Dll4 is critically involved in the pathogenesis of TMEV-IDD and that antibodies to Dll4 could be used as a novel therapeutic treatment of demyelinating diseases such as human multiple sclerosis.

Effects of human recombinant-interferon ß in experimental autoimmune encephalomyelitis in guinea pigs.

CONTEXT: Although clinical data for beneficial effects of Betaferon, human recombinant-interferon (r-IFN) ß-1b, are accumulating, what is less evident is how and why it works. OBJECTIVE: The present study was carried out to examine whether Betaferon suppresses progression of experimental autoimmune encephalomyelitis (EAE). MATERIALS AND METHODS: The EAE model was employed in guinea pigs in vivo, and mononuclear cell proliferation and 2',5'-oligoadenylate synthetase activity were assessed in vitro. RESULTS: Betaferon was more reactive in two assays of guinea pigs, mitogen-induced proliferation of peripheral blood mononuclear cells and 2',5'-oligoadenylate synthetase activity of blood, than in rats and rabbits. Guinea pigs were immunized actively by antigen, porcine myelin basic protein. The neurological deficits were assessed by clinical signs scored daily. Guinea pig Betaferon, replaced with guinea pig albumin (GPA), at 1.2 and 12.0 MIU/kg/day or vehicle was administered subcutaneously daily for 20 days in the immunized guinea pigs. GPA-Betaferon suppressed the manifestation of ataxia or more progression of chronic neurological deficits significantly at 1.2 MIU/kg (p <0.05). Two out of 10 animals manifested no clinical signs in the GPA-Betaferon-treated group with the higher dose, while all animals were worsened with typical clinical signs of EAE in the vehicle group where mononuclear cell infiltrates around blood vessels were seen in the spinal cord of vehicle-treated animals. DISCUSSION AND CONCLUSION: Human r-IFN ß-1b attenuates progression of neurological deficits in the EAE model of guinea pigs with evidence for higher susceptibility of animal cells/tissues to the human cytokine, in contrast with rodents and rabbits.

Glial cell line-derived neurotrophic factor is expressed by inflammatory cells in the sciatic nerves of Lewis rats with experimental autoimmune neuritis.

Neurotrophic factors, including glial cell line-derived neurotrophic factor (GDNF), have been known to play a role in neuroprotection in the injured peripheral nervous system (PNS). To evaluate the involvement of GDNF in experimental autoimmune neuritis (EAN) pathogenesis, the expression of GDNF in rat sciatic nerves with EAN was studied. Western blot analysis showed that the level of GDNF protein significantly increased 1.8-fold at the paralytic stage of EAN at day 12 post-immunization (PI) (p < 0.01), and its level further increased approximately 2.5-fold at day 21 PI (p < 0.001) in the sciatic nerves of EAN-affected rats compared with those of control rats, and then declined thereafter at day 28 PI. Immunohistochemical analysis showed that axons and Schwann cells constitutively contained GDNF in normal controls. In sciatic nerves with EAN at day 12 PI, GDNF was immunostained in infiltrating inflammatory cells including macrophages and T cells. Collectively, we postulate that GDNF plays a regulatory role in EAN paralysis. A paradoxical role of inflammatory cells to ameliorate PNS inflammation remains to be further studied in EAN, an animal model of human demyelinating disease.

Upregulation of erythropoietin in rat peripheral nervous system with experimental autoimmune neuritis.

The glycoprotein erythropoietin (EPO) is a multifunctional cytokine involved in erythropoiesis. Recent data have suggested that EPO and EPO receptors are expressed in the central nervous system, where EPO exerts neuroprotective effects. However, peripheral nervous system (PNS) EPO and EPO receptor expression has not been widely studied. EPO and EPO receptor expression was examined in the PNS in an experimental autoimmune neuritis (EAN) rat model in the present study to elucidate EPO/EPO-receptor binding pathway involvement in injured PNS tissue. Western blot analysis demonstrated that EPO was significantly increased in the PNS at the paralytic stage on day 14 post-immunization (PI); levels were significantly decreased at day 30 PI. EPO was identified in PNS-derived vascular endothelial cells, Schwann cells, and axons in normal control rats. Most inflammatory cells in EAN lesions were EPO immunopositive at day 14 PI. In addition, the intensity of EPO immunoreactivity in both Schwann and vascular endothelial cells was greater than that of normal controls at this stage; intensity declined at day 30 PI. These findings suggest that EPO is transiently upregulated in EAN lesions and that the EPO/EPO-receptor binding pathway is associated with neuroprotection in EAN-affected PNS tissues.

Effects of anti-CD70 mAb on Theiler's murine encephalomyelitis virus-induced demyelinating disease.

Ligation of CD27, a member of the tumor necrosis factor (TNF) receptor family, by its ligand CD70 is thought to be important in T cell activation, expansion and survival, B cell activation, and NK cell activation. We examined the role of CD70 in Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD) mice. Blocking of CD70 in effector phase by anti-CD70 monoclonal antibody (mAb) suppressed the development of TMEV-IDD. The number of IFN-gamma- or TNF-alpha-producing cells in the spleen and mRNA levels of IFN-gamma and TNF-alpha in spinal cord were decreased in mice treated with anti-CD70 mAb at the effector phase. In contrast, treatment with anti-CD70 mAb in induction phase failed to reduce these responses, compared to nonspecific IgG-treated control mice. These data suggest that CD70 is critically involved in the pathogenesis of TMEV-IDD and that antibodies against CD70 could be a novel therapeutic approach in the clinical treatment of demyelinating diseases such as human multiple sclerosis.