Competitive PCR quantification of pro- and anti-inflammatory cytokine mRNA in the central nervous system during autoimmune encephalomyelitis

The effect of 6 weeks of high intensity interval training on myelin biomarkers and demyelination in experimental autoimmune encephalomyelitis model

Exercise has been shown to increase myelin biomarkers such as klotho and PLP and improve clinical and pathological symptoms using the experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). In the present study, we evaluated whether 6 weeks of high-intensity interval training (HIIT) prior to induction of EAE increase klotho and/or PLP and attenuate the severity of symptoms and/or disease progression in EAE model. Our data demonstrate that HIIT increased klotho and PLP and decreased disability. These proteins are associated with maintaining myelination and further research is required to examine potential clinical relevance.

Effects of IFN-β1a and IFN-β1b treatment on the expression of cytokines, inducible NOS (NOS type II), and myelin proteins in animal model of multiple sclerosis

The aim of this study was to investigate the effects of interferon (IFN)-β1a and IFN-β1b treatment on inflammatory factors and myelin protein levels in the brain cortex of the Lewis rat experimental autoimmune encephalomyelitis (EAE), animal model of multiple sclerosis. To induce EAE, rat were immunized with inoculums containing spinal cord guinea pig homogenized in phosphate-buffered saline and emulsified in Freund's complete adjuvant containing 110 µg of the appropriate antigen in 100 µl of an emulsion and additionally 4-mg/ml Mycobacterium tuberculosis (H37Ra). The rats were treated three times per week with subcutaneous applications of 300,000 units IFN-β1a or IFN-β1b. The treatments were started 8 days prior to immunization and continued until day 14 after immunization. The rats were killed on the 14th day of the experiment. EAE induced dramatic increase in interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-concentrations and inducible nitric oxide synthase (iNOS) expression in the brain, which closely corresponded to the course of neurological symptoms and the loss of weight. Both IFN-β1b and IFN-β1a treatments inhibited the pro-inflammatory cytokines (IL-6, IL-1β, TNF-α and IFN-γ), decreased the activation of astrocytes, increased the myelin protein level in the brain cortex, and improved the neurological status of EAE rats by different mechanisms; IFN-β1a reduced iNOS expression, at least in part, by the enhancement of IL-10, while IFN-β1b diminished IL-10 concentration and did not decrease EAE-induced iNOS expression.

Mechanism of experimental autoimmune encephalomyelitis in Lewis rats: recent insights from macrophages

Experimental autoimmune encephalomyelitis (EAE) in Lewis rats is an acute monophasic paralytic central nervous system disease, in which most rats spontaneously recover from paralysis. EAE in Lewis rats is induced by encephalitogenic antigens, including myelin basic protein. EAE is mediated by CD4⁺ Th1 cells, which secrete pro-inflammatory mediators, and spontaneous recovery is mediated by regulatory T cells. Recently, it was established that classically activated macrophages (M1 phenotype) play an important role in the initiation of EAE, while alternatively activated macrophages (M2 phenotype) contribute to spontaneous recovery from rat EAE. This review will summarize the neuroimmunological aspects of active monophasic EAE, which manifests as neuroinflammation followed by neuroimmunomodulation and/or neuroprotection, with a focus on the role of alternatively activated macrophages.

Cannabinoids ameliorate disease progression in a model of multiple sclerosis in mice, acting preferentially through CB1 receptor-mediated anti-inflammatory effects

Multiple sclerosis (MS) is an autoimmune disease that affects the CNS and it is characterized by inflammation, demyelination, remyelination, gliosis and axonal damage that occur mainly in the spinal cord. Cannabinoids have been proposed as promising therapeutic agents in MS given their capability to alleviate specific MS symptoms (e.g., spasticity, pain). Although MS has been considered mainly an inflammatory disorder, recent evidence, however, revealed the importance of neurodegenerative events, opening the possibility that cannabinoid agonists, given their cytoprotective properties, may also serve to reduce oligodendrocyte death and axonal damage in MS. Thus, the treatment with WIN55,512-2, a potent CB(1) and CB(2) agonist, was reported to be effective to ameliorate tremor and spasticity in mice with chronic relapsing experimental autoimmune encephalomyelitis, a murine model of MS, but also to delay disease progression in this and other murine models of MS. The purpose of this investigation was to further explore the mechanism(s) underlying the amelioration in disease progression caused by WIN55,212-2. We have particularly focused on anti-glutamatergic and anti-inflammatory effects of this cannabinoid agonist. In this study, we used mice treated with myelin oligodendrocyte glycoprotein (MOG) that induces a progressive pattern of EAE and conducted the pharmacological experiments in early stages of the disease. As expected, the administration of WIN55,512-2 (5 mg/kg, i.p) had a positive effect in reducing neurological disability and improving motor coordination of EAE mice. Levels of glutamate and GABA in the spinal cord and also in the brainstem of EAE mice were similar to control animals, and, accordingly, they were not altered by the treatment with WIN55,212-2. However, EAE mice showed some subtle alterations in mRNA levels for the glutamate transporter GLT1 and, to a lesser extent, GLAST too, changes that were altered by the treatment with WIN55,212-2 in the spinal cord, but not in the brainstem. Regarding to inflammatory responses, EAE mice showed a marked up-regulation in mRNA levels for COX-2, inducible NOS and TNF-α in the spinal cord and the brainstem, these responses being attenuated after the treatment with WIN55,212-2. We also observed the presence of cell aggregates in the spinal cord of EAE mice that were significantly attenuated by the treatment with WIN55,212-2. Immunohistochemical analysis (with Iba-1 and Cd11b) of these aggregates indicated that they corresponded to microglia (resident macrophages) and peripheral macrophages. Lastly, experiments conducted with selective antagonists for the CB(1) (e.g. rimonabant) or CB(2) (e.g. AM-630) receptors revealed that WIN55,212-2 effects in EAE mice were mediated by the activation of CB(1) but not CB(2) receptors, as reflected the reversion of positive effects of this cannabinoid on neurological decline, TNF-α generation and accumulation of cell aggregates in the spinal cord with rimonabant, but not with AM-630. This was concordant with the lack of positive effects on neurological decline observed in EAE mice when they received HU-308, a selective CB(2) receptor agonist, instead WIN55,212-2. In summary, the treatment of EAE mice with the cannabinoid agonist WIN55,512-2 reduced their neurological disability and the progression of the disease. This effect was exerted through the activation of CB(1) receptors, which would exert a positive influence in the reduction of inflammatory events linked to the pathogenesis of this disease.

Immunohistochemical studies on disabled-2 protein in the spinal cords of rats with experimental autoimmune encephalomyelitis

Disabled-2 (Dab-2), an adaptor protein of transforming growth factor beta (TGF-β) signaling, was studied in the spinal cords of rats with experimental autoimmune encephalomyelitis (EAE) to evaluate the possible involvement of Dab-2 in the pathogenesis of EAE using Western blot and immunohistochemical analyses. Western blot analysis showed that two isoforms (p96 kDa and p67 kDa) of Dab-2 were detected in the spinal cords of rats used as controls. Both isoforms of Dab-2 were significantly elevated in the EAE spinal cord at the peak stage of EAE (P<0.05) and declined at the recovery stage. However, only the p96 kDa isoform was markedly phosphorylated in the EAE spinal cord. Immunohistochemistry showed that Dab-2 and p-Dab-2 were detected in some vascular endothelial cells, glial cells, and some neurons in the rat spinal cords of normal and immunized CFA-alone controls. In EAE lesions, Dab-2 and p-Dab-2 were immunodetected in some inflammatory cells (mainly in ED1-positive macrophages and R73-positive T cells), while the enhanced immunoreactivity of Dab-2 in spinal cord cells suggested constitutive expression. Additionally, TGF-β1 immunoreactivity showed a similar expression pattern of Dab-2 in EAE lesions. These findings suggest that Dab-2 is transiently upregulated and phosphorylated (particularly the p96 kDa isoform) in EAE, a CNS autoimmune disease, and may be involved in TGF-β signaling.

Smad3-dependent signaling underlies the TGF-β1-mediated enhancement in astrocytic iNOS expression

We previously demonstrated that transforming growth factor-beta1 (TGF-beta1), while having no effect alone, enhances nitric oxide (NO) production in primary, purified mouse astrocytes induced by lipopolysaccharide (LPS) plus interferon-gamma (IFN-gamma), by recruiting a latent population of astrocytes to respond, thereby enhancing the total number of cells that express Nos2. In this investigation, we evaluated the molecular signaling pathway by which this occurs. We found that purified murine primary astrocytes express mRNA for TGFbetaRII as well as the TGFbetaRI subunit activin-like kinase 5 (ALK5), but not ALK1. Immunofluorescence microscopy confirmed the expression of TGFbetaRII and ALK5 protein in astrocytes. Consistent with ALK5 signaling, Smad3 accumulated in the nucleus of astrocytes as early as 30 min after TGF-beta1 (3 ng/mL) treatment and persisted upto 32 hr after TGF-beta1 administration. Addition of ALK5 inhibitors prevented TGF-beta1-mediated Smad3 nuclear accumulation and NO production when given prior to the Nos2 induction stimuli, but not after. Finally, astrocyte cultures derived from Smad3 null mutant mice did not exhibit a TGF-beta1-mediated increase in iNOS expression. Overall, this data suggests that ALK5 signaling and Smad3 nuclear accumulation is required for optimal enhancement of LPS plus IFNgamma-induced NO production in astrocytes by TGF-beta1.

TNF-alpha promoter polymorphisms in multiple sclerosis: no association with -308 and -238 alleles, but the -857 alleles in associated with the disease in Turkish patients

Dysregulation in the expression of pro- and anti-inflammatory cytokines is one of the milestones in multiple sclerosis (MS) development and progression. Tumour necrosis factor (TNF-alpha), a proinflammatory cytokine is believed to play an important role in MS pathogenesis. The objective of this study is to investigate the association between TNF-alpha promoter region (TNF-alpha-238, -308 and -857) and susceptibility to MS and clinical course of the disease. Eighty-six relapsing remitting MS patients and 150 sex-, age- and ethnic-matched controls were enrolled in the study. Genotyping was performed by PCR-RFLP method. We observed a statistically significant increase in TNF-alpha 857 CC genotype in MS patients than controls (P < 0.001) while TNF-alpha 857 CT genotype showed a significant negative correlation with MS patients (P = 0.033). No differences in the distribution of the TNF-alpha-238 and -308 alleles were observed. None of the three polymorphisms (-238, -308 and -857) did not show relation with disease duration, Expanded Disability Status Scale or age of onset. On the other hand, significant difference of TNF -857 CC genotype was identified with the low disease index (P = 0.025). Although the study group is small, the results indicate that TNF-alpha 857 CC genotype may cause susceptibility to MS in the Turkish population.

Caffeic acid phenethyl ester (CAPE) protects brain against oxidative stress and inflammation induced by diabetes in rats

Diabetic patients reveal significant disorders, such as nephropathy, cardiomyopathy, and neuropathy. As oxidative stress and inflammation seem to be implicated in the pathogenesis of diabetic brain, we aimed to investigate the effects of caffeic acid phenethyl ester (CAPE) on oxidative stress and inflammation in diabetic rat brain. Diabetes was induced by a single dose of streptozotocin (45 mg kg(-1), i.p.) injection into rats. Two days after streptozotocin treatment 10 microM kg(-1) day(-1) CAPE was administrated and continued for 60 days. Here, we demonstrate that CAPE significantly decreased the levels of nitric oxide and malondialdehyde induced by diabetes, and the activities of catalase, glutathione peroxidase, and xanthine oxidase in the brain. However, glutathione levels were increased by CAPE. The mRNA expressions of tumor necrosis factor (TNF)-alpha and interferon (IFN)-gamma, and inducible nitric oxide synthase (iNOS) were remarkably enhanced in brain by diabetes. CAPE treatments significantly suppressed these inflammatory cytokines (about 70% for TNF-alpha, 26% for IFN-gamma) and NOS (completely). Anti-inflammatory cytokine IL-10 mRNA expression was not affected by either diabetes or CAPE treatments. In conclusion, diabetes induces oxidative stress and inflammation in the brain, and these may be contributory mechanisms involved in this disorder. CAPE treatment may reverse the diabetic-induced oxidative stress in rat brains. Moreover, CAPE reduces the mRNA expressions of TNF-alpha and IFN-gamma in diabetic brain; suggesting CAPE suppresses inflammation as well as oxidative stress occurred in the brain of diabetic patients.

Increased phosphorylation of cyclic AMP response element-binding protein in the spinal cord of Lewis rats with experimental autoimmune encephalomyelitis

To investigate whether the phosphorylation of cyclic AMP response element-binding protein (CREB) is implicated in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), the change in the level of CREB phosphorylation was analyzed in the spinal cord of Lewis rats with EAE. Western blot analysis showed that the phosphorylation of CREB in the spinal cord of rats increased significantly at the peak stage of EAE compared with the controls (p<0.05) and declined significantly in the recovery stage (p<0.05). Immunohistochemistry showed that the phosphorylated form of CREB (p-CREB) was constitutively immunostained in few astrocytes and dorsal horn neurons in the spinal cord of normal rats. In the EAE-affected spinal cord, p-CREB was mainly found in ED1-positive macrophages at the peak stage of EAE, and the number of p-CREB-immunopositive astrocytes was markedly increased in the spinal cord with EAE compared with the controls. Moreover, p-CREB immunoreactivity of sensory neurons, which are closely associated with neuropathic pain, was significantly increased in the dorsal horns at the peak stage of EAE. Based on these results, we suggest that the increased phosphorylation of CREB in EAE lesions was mainly attributable to the infiltration of inflammatory cells and astrogliosis, possibly activating gene transcription, and that its increase in the sensory neurons in the dorsal horns is involved in the generation of neuropathic pain in the rat EAE model.

A chronically implantable, hybrid cannula-electrode device for assessing the effects of molecules on electrophysiological signals in freely behaving animals

We describe a device for assessing the effects of diffusible molecules on electrophysiological recordings from multiple neurons. This device allows for the infusion of reagents through a cannula located among an array of micro-electrodes. The device can easily be customized to target specific neural structures. It is designed to be chronically implanted so that isolated neural units and local field potentials are recorded over the course of several weeks or months. Multivariate statistical and spectral analysis of electrophysiological signals acquired using this system could quantitatively identify electrical "signatures" of therapeutically useful drugs.

Elevated cAMP levels reverse Brucella melitensis-induced lipid peroxidation and stimulate IL-10 transcription in rats

Brucella species are able to survive and replicate within the phagocytic vacuole of macrophages that induce chronic infection in humans and domestic animals. The activation of oxidative bactericidal activity is one of the defense systems which protect the host from the toxic effects of pathogens. The aim of this study was to evaluate lipid peroxidation, NO production, antioxidative system and inflammation during a period of brucella infection in a rat model; in addition to investigate the role of elevated intracellular cyclic AMP on Brucella-induced events. Brucella significantly induced lipid peroxidation in plasma, liver and spleen by 3-5-fold at 7 days postinfection. NO concentration was significantly elevated in the liver and spleen while unchanged in plasma. Cyclic AMP elevating agent, rolipram, administration (1mg/kg/day i.p., 3 days) gradually suppressed lipid peroxidation and NO formation to the basal level in plasma and spleen whilst only a slight decrease was observed in liver. Brucella considerably decreased SOD activity in the liver and spleen, with rolipram restoring the enzyme activity in liver and activity in spleen being unchanged. Reverse transcriptase PCR analyses showed that Brucella melitensis does not alter TNF-alpha and IFN-gamma transcriptions in liver and spleen. The pathogen did not consistently induce nitric oxide synthase mRNA transcriptions in animals; even in those housed in the same group. IL-10 transcription was induced by rolipram in spleen but not in liver. Our results suggest that activation of the cAMP/PKA pathway suppressed lipid peroxidation and the elevated NO concentrations caused by B. melitensis. Moreover, rolipram induced anti-inflammatory cytokine IL-10 transcription and SOD activity, albeit in a tissue dependent manner.

Exogenous IL-12 suppresses experimental autoimmune encephalomyelitis (EAE) by tuning IL-10 and IL-5 levels in an IFN-γ-dependent way

Endogenous IL-12 is considered to be required for the generation and function of pathogenic Th1 effector cells in experimental autoimmune encephalomyelitis (EAE). We show here that IL-12 administration together with the immunization suppressed actively induced CREAE in SJL/J and in Biozzi/ABH mice and even subsequent spontaneous relapse incidence and severity in Biozzi ABH mice. IL-12 given during remission of primary disease inhibited re-induced relapses in SJL/J, but not spontaneous relapses in Biozzi mice. The protective effect of IL-12 is time- and dose-dependent. Protection is accompanied by subsequent increased production of IL-10 and IL-5 by lymph node and spleen cells and an inhibition of cell proliferation. Mice depleted of IFN-gamma by administration of neutralizing antibodies were poorly protected by exogenous IL-12, indicating that the inhibitory effect of IL-12 is partially IFN-gamma dependent.

Evaluation of oxidative stress and inflammation in long term Brucella melitensis infection

The Brucella genus is able to cause chronic infection in a wide range of mammals including humans. Oxidative events, lipid peroxidation and inflammatory response against Brucella infection have not yet been well elucidated in vivo. We have investigated oxidative/antioxidative status and nitric oxide production in plasma, brain, liver and spleen during a 60 day period of B. melitensis infection in a rat model. In addition, inducible nitric oxide synthase (iNOS), IL-10, IL-12, IFN-gamma and TNF-alpha mRNA transcriptions were analyzed by semiquantitative reverse transcriptase PCR (RT-PCR) in brain samples. Animals were infected with B. melitensis and sacrificed at 7th, 15th, 30th, 45th and 60th day of post-inoculation. Malondialdehyde (MDA), as an indicator of lipid peroxidation, and nitric oxide (NO) concentrations were significantly increased after Brucella inoculation and began to decline to basal levels from 45th day in plasma, liver and spleen. However, iNOS transcription was not induced during the infection period in brains. In contrast, MDA level was increased in brain during the late phase of infection without any change in NO production. The infection did not alter the antioxidant enzyme activities in the tissues; although significantly increased catalase activity was observed between days 30 and 45 in the liver. Transcription analyses demonstrated that IL-10, IL-12 and IFN-gamma mRNA level were not induced in the brain. Only TNF-alpha mRNA was weakly up-regulated in brain 30 days after pathogen inoculation. The results obtained in this study demonstrate that B. melitensis induces lipid peroxidation and NO production in the liver and spleen in the early days of infection, but that these levels subsequently decline. Moreover, Brucella does not appear to induce antioxidant enzyme activities and inflammation during two months of infection. However, the pathogen does stimulate cerebral lipid peroxidation in the late phase of infection without causing significant inflammation.

Characterization of relapsing autoimmune encephalomyelitis and its treatment with decoy chemokine receptor genes

To elucidate the pathomechanisms of relapses of autoimmune disorders and to develop immunotherapy against relapses, we induced acute monophasic and chronic relapsing (CR) experimental autoimmune encephalomyelitis (EAE) in DA rats. Immunopathological and cytokine-chemokine analyses demonstrated that the number of infiltrating macrophages was significantly elevated in the CR-EAE than in acute EAE lesions and that IFN-gamma and IP-10 in the spinal cord were significantly upregulated during the first attack and relapse of CR-EAE, respectively, than at the peak of acute EAE. In vivo administration of decoy chemokine receptor plasmid DNAs encoding the binding sites of CXCR3 and CCR2 suppressed the development of relapse of CR-EAE. Importantly, multiple injections of DNAs did not elicit the antibody production against chemokine receptors. Taken together, these findings demonstrated that neutralization therapy with decoy chemokine receptor DNAs is effective to control autoimmune diseases.

Effects of gadolinium chloride (GdCl(3)) on the appearance of macrophage populations and fibrogenesis in thioacetamide-induced rat hepatic lesions

Macrophages infiltrating injured tissue play an important part in fibrogenesis. To shed light on the functional roles of macrophages, we investigated the appearance of macrophage populations in thioacetamide (TAA)-induced rat hepatic lesions, with or without pretreatment with GdCl(3), a chemical capable of inhibiting Kupffer cell functions. In the GdCl(3)+TAA group rats received a single intraperitoneal injection of GdCl(3) (7.5mg/kg body weight) and, after 24h, a single intravenous injection of TAA (300mg/kg body weight). Rats in the TAA group received TAA only. Rats in both groups were examined on post-TAA injection (PTI) days 3, 5, and 7. In the TAA group, on PTI day 3, when TAA-induced hepatocyte injury was particularly prominent, the number of macrophages peaked, subsequently decreasing until PTI day 7. As compared with the TAA group, the GdCl(3)+TAA group showed significantly decreased numbers of ED1-immunolabelled cells (exudate macrophages) and ED2-immunolabelled cells (Kupffer cells) on PTI days 3, 5, and 7, and OX6-immunolabelled cells (antigen-presenting macrophages) on PTI days 3 and 5. Although less strikingly, the numbers of alpha-smooth muscle actin-positive myofibroblasts and fibrotic areas were decreased in the GdCl(3)+TAA group. By RT-PCR, the expression of TGF-beta1 mRNA was suppressed on PTI days 3 and 7 in the GdCl(3)+TAA group, and the suppressed expression was confirmed in vitro by treating rat macrophage-like cells (HS-P) with 1% GdCl(3). The study showed that GdCl(3) treatment decreased the numbers of macrophages appearing in hepatic lesions and inhibited TGF-beta1 mRNA expression in macrophages. Decreased numbers of macrophages may contribute to improvement of hepatic fibrosis.

Cisplatin-induced renal interstitial fibrosis in neonatal rats, developing as solitary nephron unit lesions

Cisplatin (CDDP)-induced renal lesions in rats prove a useful model for analysis of the pathogenesis of post-tubular injury-renal interstitial fibrosis. This study investigated the histopathological changes in 10-day-old neonatal rats induced by a single injection of CDDP (4.5 mg/kg). Compared with age-matched controls, on postinjection (PI) days 1 to 6, the number of apoptotic cells, demonstrable with TUNEL method, was significantly increased in CDDP-treated neonates, and there was no marked epithelial necrosis nor fibrotic lesions. Fibrotic lesions began to be developed solitarily around some nephrons with dilated ducts in the corticomedullary junction on PI day 10 and the lesions became more prominent until PI day 20. The alpha-SMA-positive myofibroblastic cells were seen exclusively in the fibrotic lesions. Additionally, the numbers of macrophages reacting with EDI (specific for exudate macrophages), ED2 (for resident macrophages), and OX6 (recognizing MHC class II antigens expressed in antigen-presenting macrophages/dendritic cells) were significantly increased around the affected renal tubules. A greater immunoreaction for TGF-beta1 was seen mostly in the renal epithelial cells of CDDP-treated neonates. These findings indicated that macrophage populations and myofibrolastic cells as well as TGF-beta1 may be responsible for the production of neonatal renal interstitial fibrosis. Compared with CDDP-injected adult rats that develop extensive interstitial fibrosis (Yamate et al., J Comp Pathol, 1995), the formation of fibrotic lesions was delayed, and the lesions were limited to the area around the affected nephrons; this could be attributable to differences in renal morphology between neonates and mature kidney of adult rats.

Coxsackievirus group B type 3 infection upregulates expression of monocyte chemoattractant protein 1 in cardiac myocytes, which leads to enhanced migration of mononuclear cells in viral myocarditis

Coxsackievirus group B type 3 (CVB3) is an important cause of viral myocarditis. The infiltration of mononuclear cells into the myocardial tissue is one of the key events in viral myocarditis. Immediately after CVB3 infects the heart, the expression of chemokine(s) by infected myocardial cells may be the first trigger for inflammatory infiltration and immune response. However, it is unknown whether CVB3 can induce the chemokine expression in cardiac myocytes. Monocyte chemoattractant protein 1 (MCP-1) is a potent chemokine that stimulates the migration of mononuclear cells. The objective of the present study was to investigate the effect of CVB3 infection on MCP-1 expression in murine cardiac myocytes and the role of MCP-1 in migration of mononuclear cells in viral myocarditis. Our results showed that the expression of MCP-1 was significantly increased in cardiac myocytes after wild-type CVB3 infection in a time- and dose-dependent manner, which resulted in enhanced migration of mononuclear cells in mice with viral myocarditis. The migration of mononuclear cells was partially abolished by antibodies specific for MCP-1 in vivo and in vitro. Administration of anti-MCP-1 antibody prevented infiltration of mononuclear cells bearing the MCP-1 receptor CCR2 in mice with viral myocarditis. Infection by UV-irradiated CVB3 induced rapid and transient expression of MCP-1 in cardiac myocytes. In conclusion, our results indicate that CVB3 infection stimulates the expression of MCP-1 in myocardial cells, which subsequently leads to migration of mononuclear cells in viral myocarditis.

Effects of lipopolysaccharide on the appearance of macrophage populations and fibrogenesis in cisplatin-induced rat renal injury

Macrophages play an important role in renal interstitial fibrosis via production of transforming growth factor-beta1 (TGF-beta1) and tumor necrosis factor-alpha (TNF-alpha); these fibrogenic factors mediate induction of myofibroblastic cells capable of producing extracellular matrices. We investigated the effects of lipopolysaccharide (LPS), a macrophage activator, on the appearance of macrophage populations and subsequent fibrogenesis in cisplatin (CDDP)-induced rat renal lesions. In keeping with the progression of interstitial fibrosis, alpha-smooth muscle actin (alpha-SMA)-immunopositive myofibroblastic cell number began to increase on day 4 and continued gradually until day 16 after CDDP injection. Cells immunoreactive for ED1 (for exudate macrophages), ED2 (for resident macrophages) and ED3 (for activated resident macrophages) showed the highest number on day 4 or day 7, and thereafter, the numbers were gradually decreased up to day 16. On the other hand, the number of cells immunoreactive for OX6 (rat MHC class II-recognizing antibody) was increased on day 7 and remained elevated up to day 16. LPS was injected on day 7 after CDDP injection when the greatest number of ED1-positive macrophages were present. In CDDP/LPS-injected rats, the numbers of macrophages reacting to ED1, ED2, ED3, and OX6 were higher than those in CDDP-injected rats during the observation period between days 7 and 16; ED3- and OX6-positive cells were more prominently increased than ED1- and ED2-postive cells. By RT-PCR analysis, the expression of TGF-beta1 and TNF-alpha mRNAs in CDDP/LPS-injected rats on day 7 was markedly increased in contrast to those in CDDP-injected rats. These findings indicate that LPS treatment enhanced the macrophage expression of fibrogenic factors. However, there was no marked difference in the fibrogenesis between CDDP/LPS- and CDDP-injected rats. These findings suggest that the macrophage populations appearing in CDDP-induced rat renal lesions should be investigated further, to address the complicated pathogenesis of renal interstitial fibrosis.

Tumour Lines from a Spontaneous Rat Endometrial Stromal Sarcoma, Showing Dendritic Cell-like and Myofibroblastic Cell-like Phenotypes

A transplantable tumour (RY) and cell lines (RY-PB and clone RY-B-E3 isolated from RY-PB) were established from a naturally occurring endometrial stromal sarcoma (ESS) found in a 24-month-old female F344 rat. The primary tumour and RY tumours, which had been serially passaged in syngeneic female rats up to the 10th generation, consisted of spindle or round cells arranged in ill-defined bundles or sheets. Neoplastic cells of the primary and RY tumours, as well as cultured cells of RY-PB and RY-B-E3, showed positive reactions to vimentin, ED1/ED2 (both for rat macrophages/histiocytes), OX6 (for dendritic cells expressing rat MHC class II antigens), and lysosomal enzymes such as acid phosphatase and non-specific esterase, in varying degrees. Ultrastructurally, neoplastic cells characteristically had tubulovesicular system-like structures and variously developed lysosomes in the cytoplasm. Neoplastic cells also exhibited immunoexpression to an alpha-smooth muscle actin (alpha-SMA). The addition of transforming growth factor (TGF)-beta1 to RY-PB and RY-B-E3 cultures increased the number of alpha-SMA-positive cells, whilst the positive cell number was decreased by anti-TGF-beta antibody. The RT-PCR method revealed the expression of TGF-beta1 mRNA in the cultured cells. The present study showed that rat ESS-derived cells exhibited dendritic cell-like and myofibroblastic cell-like phenotypes. The histogenesis of ESSs in human beings and rats remains poorly understood, and these tumour lines may therefore become useful tools for further research.

A protective effect of early pregnancy factor on experimental autoimmune encephalomyelitis induced in Lewis rats by inoculation with myelin basic protein

Experimental autoimmune encephalomyelitis (EAE) is an organ-specific autoimmune disease characterised by inflammation and demyelination of the central nervous system and is the best available animal model of multiple sclerosis (MS). Since previous studies have shown that EAE is less severe or is delayed in onset during pregnancy and that administration of the pregnancy hormone early pregnancy factor (EPF) down-regulates EAE, experiments in the present study were designed to explore further the role of EPF in EAE. By using the rosette inhibition test, the standard bioassay for EPF and, by semi-quantitative RT-PCR techniques, we have now shown that inflammatory cells from the spinal cord of rats with EAE can produce and secrete EPF, with production being greatest during recovery from disease. Administration of EPF to rats with EAE resulted in a significant increase in the expression of IL-4 and IL-10 mRNA and a significant decrease in IFN-gamma mRNA expression in spinal cord inflammatory cells. Encephalitogenic MBP-specific T cell lines were prepared from popliteal lymph nodes of rats with EAE. Proliferation assays using these cells demonstrated the ability of exogenous EPF to down-regulate the responses of T lymphocytes to MBP.

Regional and temporal expression patterns of interleukin-10, interleukin-10 receptor and adhesion molecules in the rat spinal cord during chronic relapsing EAE

Adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) mediate leukocyte infiltration into the CNS, in experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS). Because exogenous interleukin-10 (IL-10) inhibits ICAM-1 and VCAM-1 expression and clinical EAE, we hypothesize that endogenous IL-10 signaling may suppress expression of adhesion molecules. In a rat model of chronic relapsing EAE, expression levels of IL-10 and its receptor (IL-10R1), ICAM-1 and VCAM-1 mRNA in the spinal cord are markedly increased, whereas levels of IL-10 mRNA remain relatively low. The temporal pattern of mRNA and protein expression showed marked differences between spinal cord levels. During relapse, IL-10, IL-10R1, ICAM-1, VCAM-1 mRNA levels and neurological scores show positive correlations. We conclude that endogenous IL-10 is not a crucial factor inhibiting adhesion molecule expression in this model.

Differential efficacy of a synthetic antagonist of VLA-4 during the course of chronic relapsing experimental autoimmune encephalomyelitis

The integrin VLA-4 has been shown to play a key role in the entry of antigen-specific T cells into the CNS during autoimmune demyelination. Treatment of animals with experimental autoimmune encephalomyelitis (EAE), a model of multiple sclerosis, with antibodies to VLA-4 is known to suppress acute disease. In the present study, a synthetic antagonist of VLA-4 (TBC 3486) was injected subcutaneously into mice adoptively sensitized for chronic relapsing EAE. TBC 3486 was administered daily for 14 days at early (before acute signs) and late time points (during chronic disease). Early treatment led to marked delay in disease onset and reduction in clinical severity and demyelination. After termination of treatment, clinical severity remained lower than in controls for more than 1 week. TBC 3486-treated animals showing no clinical signs (at the height of disease in controls) displayed moderate levels of inflammation but little damage to myelin. Late administration of TBC 3486 to animals with chronic EAE had no effect clinically. Immunocytochemistry and Western blotting of CNS tissue from acutely treated animals supported a moderate shift toward a Th2-type cytokine profile after treatment. Thus, TBC 3486 effectively delayed and reduced the acute (but not chronic) phase of EAE, and this amelioration correlated with changes in the inflammatory molecule profile.

Emergence of different macrophage populations in hepatic fibrosis following thioacetamide-induced acute hepatocyte injury in rats

Macrophages may play a role in fibrogenesis. The kinetics and distribution of different macrophage populations were investigated immunohistochemically in hepatic lesions following acute hepatocyte injury induced in F344 rats by a single injection of thioacetamide (TAA) (300 mg/kg body weight, intraperitoneally). Hepatocyte degeneration or necrosis induced by TAA occurred mainly in the perivenular areas of hepatic lobules as early as post-injection (PI) days 1 and 3; fibrotic lesion development began in the damaged areas on day 1, and peaked on day 5; thereafter (PI days 7 and 10), the fibrotic areas decreased and were replaced by regenerated hepatocytes on PI days 15 and 20, indicating a remodelling process. In this rat model, the number of macrophages reacting with ED1 antibody (specific for exudate macrophages), ED2 (recognizing cell membrane antigens of resident macrophages, including Kupffer cells) and OX6 (recognizing MHC class II antigens expressed in antigen-presenting macrophages and dendritic cells) began to increase on PI day 1, peaking on PI day 3. The numbers gradually decreased on PI days 5 and 7; however, the statistically significant increase was maintained in respect of ED1-positive cells up to PI day 20, whereas no significant increase in ED2- and OX6-positive cells remained from PI day 10 onwards. Interestingly, of the ED1-, ED2- and OX6-positive cells, the OX6-positive cells were the least numerous. ED1- and OX6-positive cells appeared exclusively in the injured perivenular areas, whereas ED2-positive cells were present mainly in the mid-zonal areas and in smaller numbers in the perivenular areas. These findings indicated differences in kinetics and distribution between macrophage populations appearing in hepatic fibrosis. In addition, RT-PCR revealed that mRNA expression of osteopontin, a factor for induction and maintenance of macrophages in inflammation, was markedly increased on PI days 5, 7 and 10, suggesting a role in the pathogenesis of hepatic fibrosis.

Impact of aging and life-long calorie restriction on expression of apoptosis-related genes in male F344 rat liver

Aging enhances apoptosis of hepatocytes under normal physiological conditions and increases the susceptibility to apoptosis of hepatocytes, whereas chronic calorie restriction (CR) suppresses the age-enhanced susceptibility to apoptosis. To clarify the subcellular mechanisms of age-associated dysregulation of apoptosis and the effects of CR, we analyzed the expression of genes promoting apoptosis (p53, Fas receptor, Fas ligand, TNF receptor 1, TNFalpha, Bax, TGF beta 1) and genes preventing apoptosis (Bcl-2 and Bcl-XL) in the livers of 3-, 6-, 15-, and 24-month-old male F344 rats that were either fed ad libitum or subjected to a 30% reduction in food intake (CR). After the age of 6 months, expression of p53, Fas receptor, Fas ligand, and TNFalpha mRNAs was up-regulated with aging. CR suppressed this age-enhanced p53 and Fas receptor mRNA expression, but expression of the other genes was not altered significantly by aging or CR. Expression of Fas receptor in hepatocytes, as detected immunohistochemically, increased with age, but CR suppressed age-accelerated Fas receptor expression. Our findings suggest that TNF ligand/TNF receptor family signaling, particularly Fas receptor expression, is important in age- and CR-modulated apoptosis of hepatocytes. Hepatocytes that were immunoreactive for p53 had slightly increased with aging, suggesting that p53 may mediate the age-enhanced up-regulation of Fas receptor in hepatocytes.

Upregulation of monocyte chemotactic protein-1 and CC chemokine receptor 2 in the central nervous system is closely associated with relapse of autoimmune encephalomyelitis in Lewis rats

Experimental autoimmune encephalomyelitis (EAE) is a disease model of multiple sclerosis (MS) that is characterized by remittance and relapse of the disease and autoimmune and demyelinating lesions in the central nervous system (CNS). To better understand the mechanism of disease relapse, we induced acute and chronic relapsing (CR)-EAE in Lewis rats and examined the differences between the two groups. An immunohistochemical study revealed that significantly higher numbers of macrophages infiltrated the spinal cord during the first and second attacks of CR-EAE than at the peak of acute EAE, whereas the number of infiltrating T cells was essentially the same in acute and CR-EAE. In accordance with this finding, monocyte chemoattractant protein-1 (MCP-1) mRNA, but not MIP-1alpha and RANTES mRNA, increased significantly in CR-EAE lesions rather than in acute EAE lesions. More importantly, the level of MCP-1 during the remission of CR-EAE was significantly higher than during the recovery phase of acute EAE, suggesting that this high level of MCP-1 in CR-EAE is associated with relapse of the disease. CC chemokine receptor 2 (CCR2), the main receptor for MCP-1, was expressed on astrocytes, macrophages and T cells and the number of positive cells was higher in CR-EAE than in acute EAE. Collectively, these findings suggest that high expression of MCP-1 and its receptor, CCR2, in the CNS play important roles in relapse of EAE.

Identification of autoimmune encephalomyelitis-associated common CDR3 sequences by CDR3 spectratyping and subsequent DNA hybridization

In previous studies, we demonstrated that T cell receptor (TCR) Vbeta8.2 and Vbeta10, both of which are frequently used by encephalitogenic T cells, spectratypes expand oligoclonally in spinal cord lesions of Lewis rats with experimental autoimmune encephalomyelitis (EAE) and that the DSSYEQYF and WDGSGNVLYF sequences are predominantly found in the complementarity-determining region 3 (CDR3) of spectratype-derived TCR clones. However, it is unknown whether these CDR3 sequences are used only by Vbeta8.2- and Vbeta10-positive T cells or by encephalitogenic T cells bearing Vbetas other than these Vbetas. The present study was undertaken to address this issue using a new approach, i.e. CDR3 spectratyping and subsequent DNA hybridization with several probes corresponding to various parts of the CDR3 region. Consequently, we found that probes specific for the Vbeta8.2 spectratype-derived Dbeta and Jbeta2.7 hybridized only with the Vbeta8.2 spectratype in acute EAE and with the Vbeta8.2 and Vbeta12 spectratypes in chronic relapsing EAE. Similarly, a probe specific for the Vbeta10 spectratype-derived Dbeta hybridized only with the Vbeta10 spectratype in both acute and chronic relapsing EAE. In contrast, a probe specific for Jbeta1.3 hybridized with several Vbeta spectratypes including Vbeta8.2 and Vbeta10 only during the early stage of the disease. These findings suggest that T cells bearing a few Vbetas with a limited number of the CDR3 sequences are activated in acute and chronic relapsing EAE induced in Lewis rats. Characterization of the CDR3 region of pathogenic TCR by this approach may be of value for the screening of autoimmune disease-associated TCR and for the development of TCR-based specific immunotherapy.

Pertussis toxin-induced hyperacute autoimmune encephalomyelitis in Lewis rats is correlated with increased expression of inducible nitric oxide synthase and tumor necrosis factor alpha

The involvement of inducible nitric oxide synthase (iNOS) and tumor necrosis factor alpha (TNF-alpha), which have diverse roles in the progression of autoimmune disease models, was studied in pertussis toxin (PT)-induced hyperacute experimental autoimmune encephalomyelitis (EAE) in Lewis rats. The expression of TNF-alpha mRNA (increased 5-fold, P<0.01) and iNOS protein (3-fold, P<0.01) was much greater in the spinal cords with PT(+) EAE at the peak stage of EAE than in those with PT(-) EAE, as shown by competitive PCR and Western blot analysis, respectively. Immunohistochemistry showed that the majority of ED1-positive macrophages in EAE lesions contained iNOS, and that there were many more iNOS-positive cells in the CNS lesions of PT(+) rats than in those of PT(-) rats. These findings suggest that PT-induced hyperacute EAE is partly mediated by the enhanced expression of iNOS and TNF-alpha in the early stages of rat EAE.

Cyclosporin A treatment modulates cytokine mRNA expression by inflammatory cells extracted from the spinal cord of rats with experimental autoimmune encephalomyelitis induced by inoculation with myelin basic protein

In Lewis rats, treatment with high doses of cyclosporin A (CsA) suppresses clinical signs of experimental autoimmune encephalomyelitis (EAE), although disease occurs when treatment is ceased. Treatment with low doses of CsA causes EAE to take a chronic relapsing course. We have previously shown that CsA treatment causes a decline in the number of T cells and increased inflammatory cell apoptosis in the spinal cord. The present study was undertaken to assess whether CsA therapy also modulates cytokine mRNA expression by inflammatory cells in the spinal cord of rats with EAE, looking for changes that might contribute to the observed effects of CsA on the course of EAE. EAE was induced in Lewis rats by inoculation with myelin basic protein and adjuvants. At the peak of neurological signs, on day 14 after inoculation, rats were given a single intraperitoneal injection of saline, or CsA at a dose of 8, 16, 32 or 64 mg/kg. The next day, rats were sacrificed, the spinal cords removed, inflammatory cells were extracted from the cords, and mRNA isolated from these cells. Expression of cytokine mRNA was assessed by semi-quantitative reverse transcription polymerase chain reaction (PCR) and by quantitative real-time PCR. With both techniques, we found that CsA suppressed the expression of interferon-gamma mRNA and interleukin-2 (IL-2) mRNA. With real-time PCR, we found that CsA caused significantly increased expression of transforming growth factor-beta mRNA. With the different techniques, we observed no consistent pattern of alteration of expression of interleukin-10 or interleukin-4 mRNA. It is possible that these changes in cytokine mRNA expression contribute to the modulation of the clinical course of EAE that is produced by CsA treatment.

Two-step activation of T cells, clonal expansion and subsequent Th1 cytokine production, is essential for the development of clinical autoimmune encephalomyelitis

Lewis rats immunized with guinea pig myelin basic protein (GPBP) emulsified with incomplete Freund's adjuvant (IFA) do not develop experimental autoimmune encephalomyelitis (EAE). However, we found that GPBP/IFA with pertussis toxin (PT) administration induced full-blown EAE. By comparing the immunological status of rats immunized with GPBP/IFA plus PT [PT (+) rats] with that of rats immunized with GPBP/IFA alone [PT (-) rats], we tried to elucidate the pathomechanisms of EAE. Analysis of the TCR clonality by CDR3 spectratyping revealed that Vbeta8.2 and Vbeta10 expansion of T cells occurred in both PT (-) and PT (+) rats, indicating that activation of T cells at this level is not sufficient for the development of clinical EAE. Quantitation of cytokine mRNA and protein revealed that PT (-) rats showed a Th2-dominant, while PT (+) rats showed a Th1-dominant, cytokine profile. Furthermore, administration of IL-12, but not of IFN-gamma and TNF-alpha, induced clinical EAE in GPBP/IFA-immunized animals. Taken together, two-step activation, activation of T cells bearing a particular type of TCR by antigen immunization and subsequent overproduction of Th1 cytokines, mainly IL-12 production, induced by appropriate adjuvants is essential for the development of clinical EAE.

Intrathecal administration of endothelin-1 receptor antagonist ameliorates autoimmune encephalomyelitis in Lewis rats

The role of endothelin-1 (ET-1) in the development of experimental autoimmune encephalomyelitis (EAE) was studied by the blocking the action of ET-1 with a receptor antagonist, BQ-123. Intrathecal administration of BQ-123 significantly ameliorated EAE progression at the peak stage of EAE (p<0.05). By immunohistochemistry, ED-1-positive macrophages in EAE lesions were identified as major producers of ET-1, whereas the immunoreactivity of ET-1 on brain cells, such as astrocytes, was dramatically increased in accordance with the progression of EAE. This study points to a putative pro-1nflammatory role for ET-1 in the pathogenesis of EAE. One possible application for the ET-1 receptor antagonist might be helpful in the therapy of autoimmune neurological disorders.

STAT expression and localization in the central nervous system during autoimmune encephalomyelitis in Lewis rats

Autoimmune inflammation in the central nervous system (CNS) is maintained by secretion of a large number of cytokines. To elucidate its molecular mechanisms, we examined the expression and localization of STAT1, STAT3, STAT4 and STAT6 molecules, which are the downstream molecules of the cytokine signal transduction pathway, in the CNS during acute experimental autoimmune encephalomyelitis (EAE) induced in Lewis rats. Western blot analysis demonstrated that STAT1 protein increased gradually till the recovery stage, whereas STAT4 protein showed abrupt increase at the early stage followed by gradual decrease. STAT3 and STAT6 showed stable expression throughout the course of the disease. The kinetics of the phosphorylated form of STAT1 and STAT4 roughly paralleled that of the total protein although the peak of STAT3 phosphorylation was recognized at the preclinical stage. Immunohistochemical examinations revealed that STAT3 and STAT4, but not STAT1 and STAT6, immunoreactivities were mainly expressed in astrocytes and microglia, respectively, and were closely associated with inflammatory lesions. Taken together, these findings suggest that STAT3 and STAT4 play an important role in the formation of, and recovery from, autoimmune inflammation in the CNS.

Intracerebral recruitment and maturation of dendritic cells in the onset and progression of experimental autoimmune encephalomyelitis

Dendritic cells (DCs) are thought to be key elements in the initiation and maintenance of autoimmune diseases. In this study, we sought evidence that DCs recruited to the central nervous system (CNS), a site that is primarily devoid of resident DCs, play a role in the effector phase and propagation of the immune response in experimental autoimmune encephalomyelitis (EAE). After immunization of SJL mice with proteolipid protein 139-151 peptide, process-bearing cells expressing the DC markers DEC-205 and CD11c appeared early in the spinal cord. During acute, chronic, and relapsing EAE, DEC-205(+) DCs expressing a lymphostimulatory phenotype (including the mature DC marker MIDC-8, major histocompatibility complex class II, CD40, and CD86 molecules) accumulated within the CNS inflammatory cell infiltrates. More prominent infiltration of the spinal cord parenchyma by mature DCs was observed in mice with relapsing disease. Macrophage inflammatory protein 3alpha, a chemokine active on DCs and lymphocytes, and its receptor CCR6 were up-regulated in the CNS during EAE. These findings suggest that intracerebral recruitment and maturation of DCs may be crucial in the local stimulation and maintenance of autoreactive immune responses, and that therapeutic strategies aimed at manipulating DC migration could be useful in the treatment of CNS autoimmune disorders.

Specific Th2 cells accumulate in the central nervous system of mice protected against experimental autoimmune encephalomyelitis by copolymer 1

This study addresses the issue of the effect of immunomodulating therapies in the target organ-the central nervous system (CNS)-in the case of multiple sclerosis. Copolymer 1 (Cop 1, Copaxone, glatiramer acetate), an approved drug for the treatment of multiple sclerosis, is a potent inducer of Th2 regulatory cells in both mice and humans. Highly reactive Cop 1-specific T cell lines that secrete IL-4, IL-5, IL-6, IL-10, and transforming growth factor-beta in response to Cop 1 and crossreact with myelin basic protein (MBP) at the level of Th2 cytokine secretion were established from both brains and spinal cords of Cop 1-treated mice. In contrast, no reactivity to the control antigen lysozyme could be obtained in lymphocytes isolated from CNS of mice injected with lysozyme. Adoptively transferred labeled Cop 1-specific suppressor cells were found in brain sections 7 and 10 days after their injection to the periphery, whereas lysozyme-specific cells were absent in the CNS. Hence, Cop 1-induced Th2 cells cross the blood-brain barrier and accumulate in the CNS, where they can be stimulated in situ by MBP and thereby exert therapeutic effects in the diseased organ. This therapeutic effect was manifested, in brains of experimental autoimmune encephalomyelitis-induced mice, by a decrease in the inflammatory cytokine interferon-gamma and by secretion of the anti-inflammatory cytokine IL-10 in response to the autoantigen MBP.

Divergent roles for p55 and p75 tumor necrosis factor receptors in the pathogenesis of MOG(35-55)-induced experimental autoimmune encephalomyelitis

To clarify the role of tumor necrosis factor (TNF) in the inflammatory aspects of autoimmunity vs its potential role in the apoptotic elimination of autoreactive effector cells, we assessed the roles of the p55 (TNFR1/Tnfrsf1a/CD120a) and p75 (TNFR2/Tnfrsf1b/CD120b) TNF receptors in the pathogenesis of MOG(35-55)-induced experimental autoimmune encephalomyelitis (EAE). TNFR p55/p75(-/-) double knockout mice were completely resistant to clinical disease. TNFR p55(-/-) single knockout mice were also totally resistant to EAE, exhibiting reduced MOG(35-55)- specific proliferative responses and Th1 cytokine production, despite displaying equivalent DTH responses. Importantly, IL-5 was significantly increased in p55(-/-) mice. In contrast, p75(-/-) knockout mice exhibited exacerbated EAE, enhanced Th1 cytokine production, and enhanced CD4(+) and F4/80(+) CNS infiltration. Thus, p55/TNFR1 is required for the initiation of pathologic disease, whereas p75/TNFR2 may be important in regulating the immune response. These results have important implications for therapies targeting p55 and p75 receptors for treating autoimmune diseases.

Characterization of acute versus chronic relapsing autoimmune encephalomyelitis in DA rats

This study was undertaken to better understand the role of cytokines in the pathogenesis, especially in the mechanisms of relapse, of experimental autoimmune encephalomyelitis (EAE). For this purpose, we induced acute and chronic relapsing (CR) EAE in DA rats and determined several immunological parameters in rats at various stages of two types of EAE. Histopathological analysis revealed that there was no significant difference in the severity of inflammation in the spinal cord lesions between the two groups. However, demyelination was observed only in rats with CR EAE. Cytokine analysis by competitive PCR demonstrated that levels of TNF-alpha, IL-6 and IL-12 p40 mRNA in the spinal cord at the first attack of CR EAE were significantly higher than those at the peak stage of acute EAE. The mRNA expression of anti-inflammatory cytokines, IL-10 and TGF-beta1, was generally low in both acute EAE and the first attack of CR EAE and upregulated at later stages of CR EAE. These findings suggest that persistent high-level expression of pro-inflammatory cytokines is closely associated with demyelination and relapse of EAE. In contrast, anti-inflammatory cytokines play only a minor role in the relapse.

Aminoguanidine-induced amelioration of autoimmune encephalomyelitis is mediated by reduced expression of inducible nitric oxide synthase in the spinal cord

To elucidate whether an inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (AMG), affects the expression of iNOS in the spinal cords of rats with experimental autoimmune encephalomyelitis (EAE), we induced EAE in Lewis rats, and treated EAE rats with AMG. AMG (200mg/kg administered intraperitoneally from day 0 to day 7 post-immunization) significantly reduced the clinical severity of EAE paralysis. AMG, however did not prevent the occurrence of EAE. Western blot analysis showed that iNOS expression was significantly reduced in the spinal cords of rats with EAE treated with AMG compared with rats treated with the vehicle. This finding supports the conclusion that the production of nitric oxide by iNOS plays an important role in the induction of EAE. The corollary is that the amelioration of EAE paralysis by the treatment with AMG is associated with the suppression of iNOS expression in the target organ i.e. the spinal cord.

Analysis of experimental autoimmune encephalomyelitis induced in F344 rats by pertussis toxin administration

To elucidate the factor(s) accelerating the autoimmune disease processes, we induced two types of experimental autoimmune encephalomyelitis (EAE), severe and very mild, in F344 rats by immunization with myelin basic protein (MBP) plus pertussis toxin (PT) (PT+) or with MBP alone (PT-) and compared the differences between the two. Immunohistochemical examinations showed that although the nature of inflammation was essentially the same between the two groups, the proportion of Vbeta8.2(+) T cells in the CNS lesion of PT (+) rats was larger than that of PT (-) rats. Cytokine analysis by competitive PCR revealed that IL-10 mRNA in the lymphoid organ was significantly suppressed in the PT(+) group, whereas levels of IFN-gamma,TNF-alpha and TGF-beta mRNA were insignificantly different after PT administration. In addition, T cells taken from PT (+) rats proliferated well in response to MBP, while those from PT (-) rats showed a marginal response to the same antigen. However, this finding does not indicate the switching of non-encephalitogenic to encephalitogenic T cells upon PT administration because PT (-) rats contained encephalitogenic T cells and/or their precursor cells as revealed by adoptive transfer experiments. Taken together, these findings suggest that suppression of IL-10 by PT administration is the major factor contributing to the exacerbation of EAE in PT(+) rats.

Differential regulation in human amnion epithelial and fibroblast cells of prostaglandin E(2) production and prostaglandin H synthase-2 mRNA expression by dexamethasone but not tumour necrosis factor-alpha

Previous studies have identified both pro-inflammatory cytokines and glucocorticoids as positive regulators of amnion prostaglandin (PG) biosynthesis. The stimulatory effects of dexamethasone (Dex), a glucocorticoid agonist, on prostaglandin endoperoxide H synthase (PGHS)-2 mRNA expression and PG biosynthesis in amnion have been attributed to an atypical response by the mesenchymal cells of the amnion. The objective of this study was to confirm previous findings concerning cell type-dependant Dex-induced upregulation of PGHS-2 mRNA expression and PG production using separated amnion cell populations, in comparison with the effects of the pro-inflammatory cytokine tumour necrosis factor-alpha (TNF-alpha). Amnion cells from placentae delivered at term by caesarian section were isolated by tryptic digestion and epithelial cells were then separated from mesenchymal cells by differential absorption onto plastic. After 24-72 h, the two cell populations were passaged and sub-cultured. Cells were treated with Dex (10(-9)-10(-6) m) or TNF-alpha (0.1-50 ng/ml) or media alone. Thereafter, PGE(2)production was determined and PGHS-2 mRNA content analysed by a competitive quantitative RT-PCR method established and validated for this study. PGE(2)production in fibroblast-enriched cultures was increased to 310+/-41 per cent (mean+/-sem, n=4 wells per treatment point) of control in the presence of 10(-8) m Dex. Conversely, PGE(2)production in Dex-treated amnion epithelial cells was decreased to 67+/-24 per cent of control. Altered PGE(2)biosynthesis was accompanied by the upregulation of PGHS-2 mRNA in amnion fibroblasts but not in epithelial cells. TNF-alpha increased PG output and PGHS-2 expression independent of cell type. Glucocorticoids therefore appear to have opposing effects on PG biosynthesis in the two major cellular components of the human amnion.

Functional maturation of adult mouse resting microglia into an APC is promoted by granulocyte-macrophage colony-stimulating factor and interaction with Th1 cells

A precise knowledge of the early events inducing maturation of resting microglia into a competent APC may help to understand the involvement of this cell type in the development of CNS immunopathology. To elucidate whether signals from preactivated T cells are sufficient to induce APC features in resting microglia, microglia from the adult BALB/c mouse CNS were cocultured with Th1 and Th2 lines from DO11.10 TCR transgenic mice to examine modulation of APC-related molecules and Ag-presenting capacity. Upon Ag-specific interaction with Th1, but not Th2, cells, microglia strongly up-regulated the surface expression of MHC class II, CD40, and CD54 molecules. Induction of CD86 on mouse microglia did not require T cell-derived signals. Acutely isolated adult microglia stimulated Th1 cells to secrete IFN-gamma and, to a lesser extent, IL-2, but were inefficient stimulators of IL-4 secretion by Th2 cells. Microglia exposed in vitro to IFN-gamma showed enhanced expression of MHC class II, CD40, and CD54 molecules and became able to restimulate Th2 cells. In addition to IFN-gamma, GM-CSF increased the ability of microglia to activate Th1, but not Th2, cells without up-regulating MHC class II, CD40, or CD54 molecules. These results suggest that interaction with Th1 cells and/or Th1-secreted soluble factors induces the functional maturation of adult mouse microglia into an APC able to sustain CD4+ T cell activation. Moreover, GM-CSF, a cytokine secreted by T cells as well as reactive astrocytes, could prime microglia for Th1-stimulating capacity, possibly by enhancing their responsiveness to Th1-derived signals.

Successful TCR-based immunotherapy for autoimmune myocarditis with DNA vaccines after rapid identification of pathogenic TCR

The identification of TCRs of autoimmune disease-inducing T cells within a short period of time is a key factor for designing TCR-based immunotherapy during the course of the disease. In this study, we show that experimental autoimmune carditis-associated TCRs, Vbeta8.2 and Vbeta10, were determined by complementarity-determining region 3 (CDR3)-spectratyping analysis and subsequent sequencing of the CDR3 region of spectratype-derived TCR clones. Immunotherapy targeting both Vbeta8.2 and Vbeta10 TCRs using mAbs and DNA vaccines significantly reduced the histological severity of experimental autoimmune carditis and completely suppressed the inflammation in some animals. Since depletion or suppression of one of two types of effector cells does not improve the severity of the disease significantly, combined TCR-based immunotherapy should be considered as a primary therapy for T cell-mediated autoimmune diseases. TCR-based immunotherapy after rapid identification of autoimmune disease-associated TCRs by CDR3 spectratyping can be applicable, not only to animal, but also to human autoimmune diseases whose pathomechanism is poorly understood.

Fas-mediated apoptosis in clinical remissions of relapsing experimental autoimmune encephalomyelitis

PLP139-51-induced experimental autoimmune encephalomyelitis (R-EAE) displays a relapsing-remitting paralytic course in female SJL mice. We investigated the role of apoptosis/activation-induced cell death (AICD) in the spontaneous recovery from acute disease. Clinical EAE was significantly enhanced in Fas (CD95/APO-1)-deficient SJL lpr/lpr mice, which displayed significantly increased mean peak clinical scores, reduced remission rates, and increased mortality when compared with their SJL +/lpr littermates. PLP139-151-specific proliferative responses were fairly equivalent in the 2 groups, but draining lymph node T cells from SJL lpr/lpr mice produced dramatically increased levels of IFN-gamma. Central nervous system (CNS) Fas and FasL mRNA levels in wild-type SJL (H-2(s)) mice peaked just before spontaneous disease remission and gradually declined as disease remitted. We applied the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay to detect apoptosis in situ in spinal cords of mice at various clinical stages of EAE. Most TUNEL(+) cells were found during active periods of inflammation: the acute, peak, and relapse time points. Significantly fewer apoptotic cells were observed at preclinical and remission time points. Collectively, these findings indicate that Fas-mediated apoptosis/AICD plays a major role in the spontaneous remission after the initial acute inflammatory episode and represents an important intrinsic mechanism in regulation of autoimmune responses.

A critical role for B7/CD28 costimulation in experimental autoimmune encephalomyelitis: a comparative study using costimulatory molecule-deficient mice and monoclonal antibody blockade

The B7/CD28 pathway provides critical costimulatory signals required for complete T cell activation and has served as a potential target for immunotherapeutic strategies designed to regulate autoimmune diseases. This study was designed to examine the roles of CD28 and its individual ligands, B7-1 and B7-2, in experimental autoimmune encephalomyelitis (EAE), a Th1-mediated inflammatory disease of the CNS. EAE induction in CD28- or B7-deficient nonobese diabetic (NOD) mice was compared with the effects of B7/CD28 blockade using Abs in wild-type NOD mice. Disease severity was significantly reduced in CD28-deficient as well as anti-B7-1/B7-2-treated NOD mice. B7-2 appeared to play the more dominant role as there was a moderate decrease in disease incidence and severity in B7-2-deficient animals. EAE resistance was not due to the lack of effective priming of the myelin peptide-specific T cells in vivo. T cells isolated from CD28-deficient animals produced equivalent amounts of IFN-gamma and TNF-alpha in response to the immunogen, proteolipid protein 56-70. In fact, IFN-gamma and TNF-alpha production by Ag-specific T cells was enhanced in both the B7-1 and B7-2-deficient NOD mice. In contrast, peptide-specific delayed-type hypersensitivity responses in these animals were significantly decreased, suggesting a critical role for CD28 costimulation in in vivo trafficking and systemic immunity. Collectively, these results support a critical role for CD28 costimulation in EAE induction.

Analysis of neurotrophic effects of hepatocyte growth factor in the adult hypoglossal nerve axotomy model

Recent studies have shown that hepatocyte growth factor (HGF) promotes the survival of embryonic motor neurons. However, it remains unclear whether HGF has trophic effects on mature motor neurons. In the present study, we examined the effects of HGF on adult motoneurons using the hypoglossal nerve transection model. In adult rats, neurons in the hypoglossal nucleus show a dramatic loss of choline acetyltransferase (ChAT) protein and mRNA after the axotomy. This reduction of ChAT was markedly prevented when HGF was administered continuously at the cut end of the nerve using an osmotic pump. The HGF receptor, c-met, protein and mRNA, which were faintly expressed in hypoglossal neurons under normal conditions, gradually increased and reached maximal levels 2 weeks after the axotomy. Administration of HGF reduced this c-met upregulation almost to normal levels. We also quantified HGF mRNA in the tongue and hypoglossal nucleus. The tongue contained abundant HGF mRNA, whereas the nucleus contained only low levels. Interestingly, the HGF mRNA level in the nucleus did not increase after the axotomy. These findings suggest that HGF is principally produced in the tongue and contributes to maintain ChAT expression in the nucleus. HGF produced in the hypoglossal nucleus alone after disconnection from the tongue may not be sufficient for the maintenance of the motor neuron function. Thus, exogenously applied HGF was effective to prevent the downregulation of ChAT activities. These findings provide a strong rationale for the potential clinical use of HGF for the treatment of motor neuron degenerative disease.

The neuroprotective agent SR 57746A abrogates experimental autoimmune encephalomyelitis and impairs associated blood-brain barrier disruption: implications for multiple sclerosis treatment

Experimental autoimmune encephalomyelitis (EAE) is a T cell autoimmune disorder that is a widely used animal model for multiple sclerosis (MS) and, as in MS, clinical signs of EAE are associated with blood-brain barrier (BBB) disruption. SR 57746A, a nonpeptide drug without classical immunosuppressive properties, efficiently protected the BBB and impaired intrathecal IgG synthesis (two conventional markers of MS exacerbation) and consequently suppressed EAE clinical signs. This compound inhibited EAE-induced spinal cord mononuclear cell invasion and normalized tumor necrosis factor alpha and IFN-gamma mRNA expression within the spinal cord. These data suggested that pharmacological intervention aimed at inhibiting proinflammatory cytokine expression within the central nervous system provided protection against BBB disruption, the first clinical sign of EAE and probably the key point of acute MS attacks. This finding could lead to the development of a new class of compounds for oral therapy of MS, as a supplement to immunosuppressive agents.

Opposite effects of interferon-gamma and prostaglandin E2 on tumor necrosis factor and interleukin-10 production in microglia: a regulatory loop controlling microglia pro- and anti-inflammatory activities

Following brain injury, microglial cells produce pro- and anti-inflammatory cytokines, such as tumor necrosis factor (TNF) and interleukin-10 (IL-10). IL-10 provides an efficient autocrine mechanism for controlling microglia activation. To elucidate the mechanisms that regulate the cytokine profile of microglia, we examined the effects of several immunomodulators on IL-10 and TNF production by cultured mouse microglia. Lipopolysaccharide (LPS) was the only inducer of IL-10 and TNF gene expression and secretion. The T helper 1-type cytokine interferon-gamma (IFN-gamma) induced TNF transcripts, but not TNF secretion, and suppressed LPS-induced IL-10 mRNA and secretion by microglia. Opposite to IFN-gamma, the lipid mediator prostaglandin E2 (PGE2) enhanced the LPS-induced production of IL-10 and inhibited that of TNF. The effects of PGE2 on cytokine gene expression and secretion were antagonized by IFN-gamma. Agents that increase cAMP levels mimicked the action of PGE2 on cytokine secretion, indicating the involvement of cAMP-coupled prostaglandin receptors. In conclusion, IFN-gamma and PGE2, two mediators released at inflammatory sites, differentially regulate the production of a proinflammatory and an anti-inflammatory cytokine in microglia. We suggest that the activity and role of microglia in the damaged CNS could be finely tuned by the local concentration ratio of these mediators.

Nasal administration of transforming growth factor-beta1 induces dendritic cells and inhibits protracted-relapsing experimental allergic encephalomyelitis

Cytokines have a crucial role in initiation and perturbation of EAE that represents an animal model of multiple sclerosis (MS). Administration of transforming growth factor-beta1 (TGF-beta1) to EAE mice improves clinical EAE and prevents relapses by unknown mechanisms. Administering low doses of TGF-beta1 nasally, we confirmed that TGF-beta1 inhibited development and relapse of protracted-relapsing EAE (PR-EAE) in DA rats. Infiltration of CD4+ T-cells and macrophages within the central nervous system was clearly reduced, while proliferation and IFN-gamma secretion of mononuclear cells (MNC) was augmented in TGF-beta1-treated EAE rats compared to PBS-treated control EAE rats. TGF-beta1 administered nasally also increased nitric oxide production and CD4+ T cell apoptosis. TGF-beta1 treated rats showed augmented proliferation of dendritic cells (DC) compared to MNC. These data imply that low doses of TGF-beta1 given by the nasal route prevent PR-EAE and upregulate DC functions that may be involved for disease prevention.