concanavalin-a and roquinimex

Linomide prevents the development of autoimmune insulitis and insulin-deficient diabetes mellitus in female NOD mice. Linomide prevents development of autoimmune manifestations in other experimentally induced and spontaneous autoimmune diseases as well, but the mechanism of action is unknown. The present report summarizes our investigations on the effect of Linomide on different functional T cell subsets in NOD mice analyzed according to their cytokine profile. Supernatants from cultured splenocytes and peritoneal cells taken from Linomide-treated mice contained lower levels of TNFalpha, IL-1 beta, IFN gamma and IL-12 versus higher levels of IL-4, IL-6 and IL-10 in comparison with supernatants from cultures of untreated mice. Our results suggest that regulation of autoimmunity following oral Linomide administration in NOD mice induces a shift from Th(1) to Th(2) phenotype response, thereby preventing the development of diabetes by active cytokine-induced immunoregulation of T cell subsets, including downregulation of Th(1) and upregulation of Th(2).

Topics: Adjuvants, Immunologic; Animals; Autoimmunity; Concanavalin A; Cytokines; Diabetes Mellitus, Type 1; Female; Hydroxyquinolines; Inflammation; Mice; Mice, Inbred NOD; Spleen; Th1 Cells; Th2 Cells

Linomide (quinoline-3-carboxamide, LS-2616), a synthetic immunomodulator, protects animals against a variety of experimental autoimmune diseases. In experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis (MS), linomide blocks both the clinical and histological signs of the disease, without inducing generalized immunosuppression. In the first clinical trial in patients with MS, linomide was shown to inhibit the progression of the disease. In the present study we investigated several aspects of the mechanisms of action of this immunomodulator. We found that linomide can inhibit acute EAE even when given as pretreatment, prior to induction of disease (days - 10 to 0). This inhibitory effect was reversed by adoptive transfer of naive spleen cells. A short course (7 days) of linomide treatment also inhibited EAE, especially when administered immediately after disease induction. Spleen cells from linomide-treated mice failed to present myelin antigens to T-cell lines in vitro. The defective antigen presentation was normalized by anti-oxidants such as 2-mercaptoethanol. The proportion of Mac1+ cells in the spleens of linomide-treated mice was significantly reduced and macrophage growth was inhibited in long term cultures of spleen cells derived from linomide-treated animals. Our findings suggest that the effect of linomide on EAE may be attributed, at least in part, to inactivation of antigen presenting cells, possibly following a short period of over-stimulation and increased oxidant production. This mechanism may play a universal role in the regulation of autoimmune reactivity and merits further investigation.

Topics: Adjuvants, Immunologic; Animals; Antigen-Presenting Cells; Autoimmunity; Cell Adhesion; Cell Count; Cell Division; Cells, Cultured; Concanavalin A; Encephalomyelitis, Autoimmune, Experimental; Female; Hydroxyquinolines; Lipopolysaccharides; Macrophages; Macrophages, Peritoneal; Mice; Reference Values; Spleen; Time Factors

Linomide, a quinoline-3-carboxamide, has a pleiotropic immune modulating capacity and inhibits development as well as progression of disease in animal models of autoimmunity. Linomide treatment of mice resulted in a dramatic, dose-dependent decrease of the thymic cell number shortly after the start of administration. Flow cytometric analysis revealed that the major thymocyte subset, the early immature type CD4+CD8+ thymocytes, were reduced in number by 75%, mature CD4+CD8- or CD4-CD8+ thymocytes were less sensitive to treatment. The polyclonal T cell activator Con A (Concanavalin A) was used together with IL-2 to evaluate the potential proliferative responsiveness of ex vivo thymocytes. Thymocytes from mice treated with Linomide exhibited a more vigorous proliferation than control cultures. An effect shown to not only be due to the enrichment of mature thymocytes in the cultures from Linomide treated animals, but also when purified, mature thymocytes (CD4+CD8- and CD4-CD8+) were cultured with Con A and IL-2, these cells responded with a significantly enhanced proliferation. In vivo Linomide treatment did not result in increased plasma concentrations of corticosterone and treatment of adrenalectomized mice resulted in a reduction of thymocytes which was comparable to the effect in intact mice, indicating that glucocorticoids (GC) are not major mediators of Linomide-induced thymocyte deletion. In addition to this, and supporting a glucocorticoid independent mode of action, Linomide treatment of thymocytes in vitro resulted in a significant increase in the number of apoptotic cells, specifically in the CD4+CD8+ subset, implicating apopotosis as one component in the course of thymocyte reduction. In addition to this, in vivo treatment with Linomide resulted in an identical pattern to that seen in vitro in that there was significantly increased apoptosis only in the CD4+CD8+. These data indicate that Linomide modifies thymocyte development using a glucocorticoid independent pathway and results in the increased apoptosis of the CD4+CD8+ subset.

Topics: Adjuvants, Immunologic; Adrenalectomy; Animals; Apoptosis; CD4 Antigens; CD4-Positive T-Lymphocytes; CD8 Antigens; CD8-Positive T-Lymphocytes; Cell Differentiation; Cells, Cultured; Concanavalin A; Corticosterone; Dose-Response Relationship, Drug; Female; Glucocorticoids; Hydroxyquinolines; Interleukin-2; Lymphocyte Activation; Lymphocyte Count; Mice; Mice, Inbred C57BL; T-Lymphocyte Subsets; Thymus Gland

Spleen cells from mice treated with LS2616 display a highly increased response to the polyclonal T cell lectin ConA. The total number of splenic T cells, and the relative ratios between L3T4+ and Lyt-2+ T cells were not altered by LS2616 treatment. By dissecting the overall ConA response it was found that the number of ConA-inducible, IL-2 reactive T cells was unaffected, while ConA-induced IL-2 production was enhanced after LS2616 treatment. Spleen cells from LS2616 treated mice, depleted of G10 adherent macrophages (M phi) and reconstituted with M phi from untreated mice displayed normal levels of ConA responses. M phi depleted spleen cells from untreated animals, cocultured with M phi enriched populations from LS2616 treated animals resulted in an increased ConA response. Furthermore, spleen cells from treated mice were found to be excellent stimulators for alloantigen-induced T cell responses; when used as responders in MLC, however, these cells were comparable to responders from non-treated animals. Taken together the results demonstrate that LS2616 exerts an immunostimulatory effect on M phi, which indirectly facilitates polyclonal and antigen-specific T cell responses. The possible implications of this observation on various immunoregulatory events are discussed.

Topics: Animals; Concanavalin A; Hydroxyquinolines; Interleukin-2; Lymphocyte Activation; Lymphocyte Culture Test, Mixed; Macrophage Activation; Macrophages; Mice; Spleen; T-Lymphocytes