Stefan Jung

Administration of nitric oxide synthase inhibitors in experimental autoimmune neuritis and experimental autoimmune encephalomyelitis

The nitric oxide (NO) synthase pathway is activated during experimental autoimmune inflammation of the central nervous system, and administration of aminoguanidine, an inhibitor of the cytokine-inducible NO synthase (NOS), ameliorated the disease course of autoimmune encephalomyelitis in the SJL mouse. We studied the role of nitric oxide synthase (NOS) in the pathogenesis of experimental autoimmune neuritis (EAN) and experimental autoimmune encephalomyelitis (EAE) in the Lewis rat. NG-L-monomethyl-arginine (L-NMMA), a competitive inhibitor of NOS, partially suppressed T cell line-mediated EAN, but not myelin-induced EAN, myelin basic protein (MBP)-induced EAE, or T cell line-mediated EAE. Aminoguanidine (AG), a selective inhibitor of the cytokine-inducible NOS, enhanced MBP-induced EAE, but had no significant effects on myelin-induced EAN. Two other NOS inhibitors, nitro-arginine methyl-ester and N-nitro arginine, had only little or no effects in EAN and EAE. The administration of NOS inhibitors showed some striking effects in EAN and EAE, but the observed diversity of actions points to a much more complex role of the NO pathway than previously suggested.

T cell vaccination does not induce resistance to experimental autoimmune neuritis

The effectiveness of T cell vaccination was analyzed in experimental autoimmune neuritis (EAN) that can be induced by immunization with bovine P2 protein or a peptide representing the amino acids 53-78 of P2 (P2 53-78). Lewis rats were vaccinated with glutaraldehyde-fixed lymph node cells which had been primed in vivo with P2 protein or P2 53-78 and had been activated in vitro with concanavalin A. Vaccinated animals were not protected from EAN induced by immunization with P2 protein in complete Freunds adjuvant (CFA). In a second set of experiments Lewis rats were vaccinated with irradiated or fixed P2-specific T cell lines of different specificity and neuritogenicity and were subsequently challenged with P2 53-78 in CFA. Likewise, severity of P2 53-78-induced EAN was not different between naive and T line-vaccinated groups. In spleens of vaccinated animals a substantial suppressive activity was demonstrated which was positively correlated with a weak anti-ergotypic response of these spleen cells. The fact that development of actively induced EAN was not prevented or even mitigated by T cell vaccination, in spite of an apparent vaccination-induced response to and on T lymphocytes, suggests that protection from disease is not readily induced in every autoimmune disease model.

K+ channel-blocking alkoxypsoralens inhibit the immune response of encephalitogenic T line cells and lymphocytes from Lewis rats challenged for experimental autoimmune encephalomyelitis

Alkoxypsoralens, known as DNA photomodifying agents, have been shown to block voltage-dependent K(+) channels (Kv) as well as to alleviate functional deficits in certain multiple sclerosis (MS) patients in a manner similar to 4-aminopyridine. Since Kv channel blockers are known to inhibit T cell-mediated immune responses both in vitro and in vivo, we investigated the effects of three alkoxypsoralens, 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), and 5,8-diethoxypsoralen (H37), on the following parameters: (1) whole-cell K(+) currents of encephalitogenic, myelin basic protein-specific memory T cell line cells (MBP-TCLC) derived from Lewis rats as measured by patch-clamp technique, (2) proliferation of MBP-TCLC and lymph node cells (LNC) from Lewis rats challenged for experimental autoimmune encephalomyelitis (EAE) by immunisation with spinal cord homogenate as measured by 3H-thymidine incorporation, (3) interferon-gamma (IFN-gamma) secretion of MBP-TCLC as measured by ELISA, and (4) IFN-gamma gene expression of LNC as measured by quantitative reverse transcription polymerase chain reaction (RT-PCR) with ELISA-detection. The examined alkoxypsoralens exhibited suppressive effects on the measured parameters with the same sequence of efficacy: H37>5-MOP>8-MOP. We, therefore, conclude that Kv channel-blocking alkoxypsoralens interfere with voltage-controlled signal transduction in lymphocytes and might thereby suppress immune responses in autoimmune diseases of the central nervous system and most likely also in other autoimmune disorders. Thus, alkoxypsoralens, especially the non-phototoxic substance H37, are new candidates for further studies on K(+) channel blocking immunosuppressive drugs. The agents may exert a dual beneficial effect on demyelinating diseases like MS, because they could attenuate the inflammatory process and improve axonal conductivity.

Multidrog transport in human autoimmune T line cells and peripheral blood lymphocytes

Abstract We studied multidrug transport in human autoimmune T line cells and peripheral blood leukocytes, because muitidrug transport is pleiotropically limiting the intracellular accumulation of immunosuppressive and chsmotherapeutie agents. We observed that a subpopulation of peripheral blood leukocytes containing CD4+. CD8+ and Ig+ lymphocytes expressed a muitidrug transport system. Lymphocytic muitidrug transport was seen with all peripheral blood samples analyzed, but showed considerable variations between individuals. In further studies with human lymphocytic cell lines multidrug transport was seen with 18 23 human CD4+ T cell lines, interestingly, expression of multidrug transport was independent of T cell activation. No significant transport was observed with EBV-transformed human B lymphocytes, rat T line cells or rat, mouse, or guinea pig leukocytes.

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

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

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

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