Inhibition of S-antigen induced experimental autoimmune uveoretinitis by oral induction of tolerance with S-antigen

The ability to prevent the expression of retinal SAg induced experimental autoimmune uveitis (EAU) in Lewis rats by oral administration of the SAg and SAg fragments was investigated. Oral administration of the SAg molecule prevented or markedly diminished the clinical appearance of SAg-induced disease as measured by ocular inflammation. Furthermore, oral administration of the SAg also markedly diminished uveitis induced by the uveitogenic M and N fragments of the SAg. M and N fragments were not effective in preventing SAg-induced EAU, although feeding the M fragment prevented disease induced by the M fragment. Oral administration of the SAg did not prevent myelin basic protein induced experimental autoimmune encephalomyelitis, whereas feeding myelin basic protein did. In vitro studies demonstrated a significant decrease in proliferative responses to the SAg in lymph node cells draining the site of immunization from fed vs nonfed animals. Furthermore, the addition of splenocytes from SAg-fed animals to cultures of a CD4+ SAg-specific cell line profoundly suppressed the cell line's response to the SAg, whereas these splenocytes had no effect on a purified protein derivative-specific cell line. The Ag-specific in vitro suppression was blocked by anti-CD8 antibody (OX-8) demonstrating that this suppression is dependent on CD8+ T-cells. These experiments demonstrate that Ag-specific immunomanipulation can be achieved in the EAU model by oral administration of the SAg and raise the possibility that such an approach may have practical clinical implications in uveitis as well as other human autoimmune diseases.     

Hypercalcemia produced by parathyroid hormone suppresses experimental autoimmune encephalomyelitis in female but not male mice

Besides its role in regulating serum levels of calcium and phosphorus, 1alpha, 25-dihydroxyvitamin D3 (1,25-(OH)2D3) has potent effects on the immune system and suppresses disease in several animal models of autoimmune disorders including experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. While the amount of 1,25-(OH)2D3 needed to prevent EAE is dependent on the gender of the mouse and amount of calcium available in the diet, the minimum levels of 1,25-(OH)2D3 sufficient to prevent disease cause hypercalcemia. To test if hypercalcemia independent of high levels of 1,25-(OH)2D3 can suppress EAE, we used a 25-hydroxyvitamin D3-1alpha-hydroxylase (1alpha-hydroxylase) knockout mouse strain. Because these 1alpha-hydroxylase knockout mice lack the parathyroid hormone (PTH)-regulated enzyme that synthesizes 1,25-(OH)2D3, hypercalcemia from increased bone turnover was created by continuous administration of PTH without changing the circulating levels of 1,25-(OH)2D3. This PTH-mediated hypercalcemia generated after EAE induction prevented disease in female mice but not male mice. When hypercalcemia was prevented by diet manipulation, PTH administration no longer prevented EAE. We conclude that hypercalcemia is able to prevent EAE after disease induction in female mice.     

The effect of thymalin on the count of large granular lymphocytes in the peripheral blood of mice with leukemia P388]

Effect of thymaline injections on peripheral blood natural killer cells in mice with p388 leukemia has been studied. The content of natural killers that have been identified as large granular lymphocytes decreased in blood of leukemia mice. Multiple thymaline injections (0.66 mg/kg) maintain the numbers of the lymphocytes at the level of control animals but did not increase the life span of leukemia mice.     

Immunoneutralization of chemokines for the prevention and treatment of central nervous system autoimmune disease

Chemokine-induced lymphocyte migration has long been hypothesized to regulate the appearance and continued presence of lymphocytes and monocytes in tissue-specific autoimmune diseases, including central nervous system autoimmune diseases such as multiple sclerosis. For instance, a large body of evidence points to the temporal association of chemokine expression with the appearance of T lymphocytes and monocytes/macrophages. Furthermore, experiments using mice with targeted mutations for chemokines have shown the importance of those molecules in the development of central nervous system autoimmune disease. We have hypothesized that temporal and spatial expression of chemokines is a key factor in the pathogenesis of experimental autoimmune encephalomyelitis and multiple sclerosis. To test our hypothesis we have employed the strategy of eliminating chemokine function by the passive transfer of chemokine-specific polyclonal antibodies. This approach has allowed us not only to test the function of chemokines in experimental autoimmune encephalomyelitis development, but also to ask questions about the roles of chemokines during disease progression. Moreover, this approach has allowed us to assess the efficacy of targeting chemokines and their receptors for treatment of ongoing disease. In the present report we summarize our experience using anti-chemokine administration for the prevention and treatment of experimental autoimmune encephalomyelitis as well as provide specific examples of how this approach is efficacious for disease treatment.     

X-linked inhibitor of apoptosis regulates T cell effector function

To understand how the balance between pro- and anti-apoptotic signals influences effector function in the immune system, we studied the X-linked inhibitor of apoptosis (XIAP), an endogenous regulator of cellular apoptosis. Real-time PCR showed increased XIAP expression in blood of mice with experimental autoimmune encephalomyelitis, correlating with disease severity. Daily administration (10 mg/kg/day i.p.) of a 19-mer antisense oligonucleotide specific for XIAP (ASO-XIAP) abolished disease-associated XIAP mRNA and protein expression, and given from day of onset, alleviated experimental autoimmune encephalomyelitis and prevented relapses. Prophylactic treatment also reduced XIAP expression and prevented disease. Random or 5-base mismatched ASO was not inhibitory, and ASO-XIAP did not affect T cell priming. In ASO-XIAP-treated animals, infiltrating cells and inflammatory foci were dramatically reduced within the CNS. Flow cytometry showed an 88-93% reduction in T cells. The proportion of TUNEL(+) apoptotic CD4(+) T cells in the CNS was increased from <1.6 to 26% in ASO-XIAP-treated mice, and the proportion of Annexin V-positive CD4(+) T cells in the CNS increased. Neurons and oligodendrocytes were not affected; neither did apoptosis increase in liver, where XIAP knockdown also occurred. ASO-XIAP increased susceptibility of T cells to activation-induced apoptosis in vitro. Our results identify XIAP as a critical controller of apoptotic susceptibility of effector T cell function.     

Central nervous system expression of IL-10 inhibits autoimmune encephalomyelitis

Multiple sclerosis, an inflammatory, demyelinating disease of the CNS currently lacks an effective therapy. We show here that CNS inflammation and clinical disease in experimental autoimmune encephalomyelitis, an experimental model of multiple sclerosis, could be prevented completely by a replication-defective adenovirus vector expressing the anti-inflammatory cytokine IL-10 (replication-deficient adenovirus expressing human IL-10), but only upon inoculation into the CNS where local infection and high IL-10 levels were achieved. High circulating levels of IL-10 produced by i. v. infection with replication-deficient adenovirus expressing human IL-10 was ineffective, although the immunological pathways for disease are initiated in the periphery in this disease model. In addition to this protective activity, intracranial injection of replication-deficient adenovirus expressing human IL-10 to mice with active disease blocked progression and accelerated disease remission. In a relapsing-remitting disease model, IL-10 gene transfer during remission prevented subsequent relapses. These data help explain the varying outcomes previously reported for systemic delivery of IL-10 in experimental autoimmune encephalomyelitis and show that, for optimum therapeutic activity, IL-10 must either access the CNS from the peripheral circulation or be delivered directly to it by strategies including the gene transfer described here.     

Suppression of experimental allergic encephalomyelitis by 6-hydroxyphthalaldehydic acid, O-(p-chlorobenzyl)oxime (EN3638)

EN3638 is a new oxime derivative of salicylic acid that has immunosuppressive properties. Oral administration of the compound to rats during the incubation period of experimental allergic encephalomyelitis (EAE) delayed the onset of clinical signs. EN3638 was effective in both ordinary and hyperacute forms of EAE. Doses of 50, 100, or 150 mg/kg daily, 250 mg/kg three times a week, or 400 mg/kg twice a week suppressed both clinical and histologic evidence of EAE during the course of therapy (as long as 4 weeks) and for 8 or more days thereafter. Clinical EAE developed after a full incubation period after discontinuance of EN3638, probably due to the persisting depot of antigen in oil. When EAE was produced without an oily depot, a single dose suppressed the disease for at least 5 weeks in some rats. EN3638 was effective when given only in the second half of the incubation period but not when given at the time that EAE lesions and signs develop. Passive transfer experiments suggested that the drug prevented and even reversed sensitization to neural antigens. It had only slight effect on fully sensitized lymphoid cells or on the recruitment of nonimmune inflammatory cells in the nervous system, and it was not acting as a source of salicylate or as an adrenocortical stimulator.     

Modulation of experimental allergic encephalomyelitis with anti-T suppressor factor antibodies

mAb reactive with T suppressor factors (TsF) were used to alter the course of myelin basic protein-induced experimental allergic encephalomyelitis in (SJL/J x PL/J)F1 mice. In vivo administration of mAb 14-12, reactive with effector TsF, exacerbated the clinical expression of encephalomyelitis as evidenced by prolonged periods of total limb paralysis in affected animals. This aggravation of disease signs is probably related to the inhibition of effector Ts function by mAb 14-12 thus allowing T cell autoreactivity to proceed unchecked. Disease course was influenced more favorably by i.v. administration of mAb 14-30 reactive with a subset of inducer TsF. Ten days of treatment with this mAb resulted in a reduction in the incidence and severity of disease, noted as the development of minimal limb weakness but no paralysis in the majority of affected animals. Adoptive transfer experiments revealed the presence of Ag-specific Ts in mAb 14-30-treated mice that inhibited recipient Lyt-1+ responses to myelin basic protein, the immunizing autoantigen. Suppression by transferred Ts was revealed only by treatment of the donor population with anti-Lyt-1.2 plus C, however, indicating a role for contrasuppressor activity in the regulation of autoimmune T cell function. Results are considered relevant to the potential for immunotherapeutic management of multiple sclerosis in man.     

The central nervous system inflammatory response to neurotropic virus infection is peroxynitrite dependent.

We have recently demonstrated that increased blood-CNS barrier permeability and CNS inflammation in a conventional mouse model of experimental allergic encephalomyelitis are dependent upon the production of peroxynitrite (ONOO(-)), a product of the free radicals NO* and superoxide (O2*(-)). To determine whether this is a reflection of the physiological contribution of ONOO(-) to an immune response against a neurotropic pathogen, we have assessed the effects on adult rats acutely infected with Borna disease virus (BDV) of administration of uric acid (UA), an inhibitor of select chemical reactions associated with ONOO(-). The pathogenesis of acute Borna disease in immunocompetent adult rats results from the immune response to the neurotropic BDV, rather than the direct effects of BDV infection of neurons. An important stage in the BDV-specific neuroimmune response is the invasion of inflammatory cells into the CNS. UA treatment inhibited the onset of clinical disease, and prevented the elevated blood-brain barrier permeability as well as CNS inflammation seen in control-treated BDV-infected rats. The replication and spread of BDV in the CNS were unchanged by the administration of UA, and only minimal effects on the immune response to BDV Ags were observed. These results indicate that the CNS inflammatory response to neurotropic virus infection is likely to be dependent upon the activity of ONOO(-) or its products on the blood-brain barrier.     

Protective action of antioxidant preparations on the development of experimental allergic encephalomyelitis in guinea pigs

The authors studied the action of combined tocopherol, lithium hydroxybutyrate and pyridoxal phosphate on the development of experimental allergic encephalomyelitis (EAE) in guinea-pigs. The use of the combined drug from the first days of immunization with encephalitis-inducing material prevented the development of EAE, activation of lipid peroxidation (LPO), and the appearance of the blood serum neurotropic activity. Administration of the combined drug starting from the 7th day after immunization appeared ineffective as was the administration of each drug alone, starting from the first days of immunization. The data obtained support an important role of LPO activation for the pathogenesis of the neuroallergic process.     

Essential roles of the Fas-associated death domain in autoimmune encephalomyelitis

The Fas-associated death domain (FADD) protein mediates apoptosis by coupling death receptors with the caspase cascade. Paradoxically, it also promotes cell mitosis through its C-terminal region. Apoptosis and mitosis are opposing processes that can have radically different consequences. To determine which of the FADD effects prevails in T cell-mediated autoimmune diseases, we studied myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (EAE) using mice that express a dominant-negative FADD (FADD-DN) transgene in the T cell lineage. We found that FADD blockade in T cells prevented the development of autoimmune encephalomyelitis and inhibited both Th1 and Th2 type responses. Myelin oligodendrocyte glycoprotein-specific T cell proliferation was also dramatically reduced in FADD-DN mice despite the resistance of T cells to activation-induced cell death. These results indicate that although FADD expressed by T cells is involved in regulating both mitosis and apoptosis, its effect on mitosis prevails in EAE, and that strategies inhibiting FADD functions in T cells could be effective in preventing the disease.     

The effect of apoptosis inhibitors on experimental autoimmune encephalomyelitis: apoptosis as a regulatory factor

The effect of apoptosis inhibitors on experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis, was investigated by intraperitoneal or intracisternal administration of apoptosis inhibitors Ac-YVAD-cmk and zVAD-fmk. After onset of the disease, these agents had no suppressive effect on EAE and resulted in impaired recovery or earlier relapse. Histological examination revealed that administration of zVAD-fmk suppressed the apoptotic death of inflammatory cells in the central nervous system (CNS) of mice with EAE. The results indicated that the apoptotic elimination of infiltrated cells in the CNS might be one of the recovery mechanisms in EAE.     

Suppression of experimental autoimmune encephalomyelitis by oral administration of myelin basic protein and its fragments

We report that experimental autoimmune encephalomyelitis, a T cell-mediated autoimmune disease studied as a model for multiple sclerosis, can be suppressed in Lewis rats by the oral administration of myelin basic protein (MBP). Both the clinical and histopathologic manifestations of the disease were suppressed in a dose-dependent manner. In addition, proliferative responses to MBP and, to a lesser extent, serum levels of anti-MBP antibody were suppressed by feeding MBP. Suppression of clinical and histologic disease was observed whether animals were fed MBP before or after disease induction, although suppression was more complete when rats were fed before immunization. Disease was also suppressed by the oral administration of either encephalitogenic or nonencephalitogenic fragments and decapeptides of the MBP molecule, with more complete suppression observed when nonencephalitogenic fragments were fed, suggesting that suppressor determinants exist in the MBP molecule distinct from the encephalitogenic region. The oral administration of a non-disease-inducing portion of an autoantigen represents an antigen-specific method by which an experimental autoimmune disease can be immunoregulated.     

Effect of thymalin on the thymus and immunologic indices of irradiated animals

The intramuscular injection of thymaline (1 mg/kg/day during 5 days) enhanced the regenerative processes in the thymus and favored the normalization of some immunological indices of irradiated guinea pigs.     

The Experimental Autoimmune Encephalomyelitis Disease Course Is Modulated by Nicotine and Other Cigarette Smoke Components

Epidemiological studies have reported that cigarette smoking increases the risk of developing multiple sclerosis (MS) and accelerates its progression. However, the molecular mechanisms underlying these effects remain unsettled. We have investigated here the effects of the nicotine and the non-nicotine components in cigarette smoke on MS using the experimental autoimmune encephalomyelitis (EAE) model, and have explored their underlying mechanism of action. Our results show that nicotine ameliorates the severity of EAE, as shown by reduced demyelination, increased body weight, and attenuated microglial activation. Nicotine administration after the development of EAE symptoms prevented further disease exacerbation, suggesting that it might be useful as an EAE/MS therapeutic. In contrast, the remaining components of cigarette smoke, delivered as cigarette smoke condensate (CSC), accelerated and increased adverse clinical symptoms during the early stages of EAE, and we identify a particular cigarette smoke compound, acrolein, as one of the potential mediators. We also show that the mechanisms underlying the opposing effects of nicotine and CSC on EAE are likely due to distinct effects on microglial viability, activation, and function.     

Oral administration of highly oligomeric procyanidins of Jatoba reduces the severity of collagen-induced arthritis

We have previously reported that highly oligomeric procyanidins (HOPC) purified from Jatoba, a South American herb, ameliorated experimental autoimmune encephalomyelitis (EAE) in mice. In this present study, we report that symptoms of arthritis were also significantly reduced by administering the Jatoba extract, when compared with the vehicle-alone-treated control. Interferon-gamma (IFN-gamma) production by the splenocytes from mice injected with procyanidins was also dramatically decreased. The oral administration of purified HOPC was significantly more effective in disease prevention than the ethanol (EtOH) extract of Jatoba. Green tea polyphenol administration, however, surprisingly facilitated disease development. Observation of the joint histopathology on whole paws derived from the HOPC-treated mice showed complete abrogation of collagen induced arthritis (CIA), a characteristic of chronic inflammation in the synovial tissue. These results demonstrate that HOPC administration had an inhibitory effect on both chronic arthritis and EAE and that the oral administration of HOPC exerted its effect after the induction of secondary immunity.     

Niridazole suppression of experimental allergic encephalomyelitis in Lewis rats.

Administration of niridazole to Lewis rats beginning 2 days before sensitization with guinea pig spinal cord in combination with immunologic adjuvants exerted a dose related suppressive influence on development of experimental allergic encephalomyelitis (EAE). A daily dose of 75 mg/kg completely prevented clinical neurologic signs as well as markedly suppressed occurrence of immunohistopathologic manifestations of this autoimmune disease. A higher daily dose level of niridazole, i.e., 100 mg/k, also inhibited EAE but was associated with neurotoxic manifestations.     

Effect of thymalin and heterotransfusion on blood coagulation and fibrinolysis in thymectomized rats

Experiments on rats have shown that thymectomy brings about the development of hypercoagulation and inhibition of fibrinolysis. Heterotransfusion is accompanied by hypocoagulation and stimulation of fibrinolysis in both intact and thymectomized rats. At the same time fibrinolysis in thymectomized rats is stimulated to a lesser degree than in intact animals. Preinjection into thymectomized rats of the thymus low-molecular factor thymaline over one week does not only make blood coagulation and fibrinolysis return to normal but also leads to adequate changes in the hemostatic system in response to heterotransfusion.     

Suppression of experimental autoimmune encephalomyelitis by oral administration of myelin basic protein. III. Synergistic effect of lipopolysaccharide.

Oral administration of myelin basic protein (MBP) suppresses experimental autoimmune encephalomyelitis (EAE) in Lewis rats immunized with MBP in Freund's adjuvant. The immunomodulator bacterial lipopolysaccharide (LPS) when given orally in conjunction with MBP enhances the protective effects of MBP feeding in EAE. This synergy was achieved only following oral administration of LPS but not following subcutaneous injection. In contrast, subcutaneous administration of LPS abrogated oral tolerance. A synergism between oral LPS and MBP was also demonstrated for antigen-specific suppression of delayed type hypersensitivity (DTH) responses. Antibody responses to MBP were suppressed by oral administration of MBP but not by MBP plus LPS. The lipid A moeity of LPS mimicked the effects of LPS on disease protection and DTH suppression. These data demonstrate that adjuvants can enhance the induction of antigen-specific oral tolerance for suppression of cell-mediated experimental autoimmune responses.