Browsing by Author "Badovinac, Vladimir (6603057711)"

We have shown recently that xanthine derivative pentoxifylline (PTX) downregulates an inflammatory autoimmune process triggered in genetically susceptible Dark Agouti rats by multiple low doses of streptozotocin (MLD-SZ, 20 mg/kg/day ip for 5 days). We studied the cellular and molecular consequences of PTX treatment during MLD-SZ-induced diabetes with special emphasis on local vs. systemic production of inflammatory mediators. Administration of PTX (200 mg/kg/day for 10 days) during induction of the disease reduced clinical signs of diabetes and protected rats from development of destructive intrainsulitis. Pentoxifylline did not affect diabetogenic effect of single high dose of SZ (100 mg/kg SZ). Ex vivo analysis of the islets of Langerhans performed in early disease development revealed that PTX downregulates production of proinflammatory cytokines IFN-γ and TNF, as well as inducible nitric oxide synthase (iNOS) expression and NO production. In addition, PTX treatment suppressed splenocyte autoreactivity, as well as the frequency of cells expressing IL-2R and MHC class II antigens. There was no evidence of any changes in proportion of ICAM-1 and LFA-1 expressing splenocytes in comparison to control MLD-SZ-treated animals. In contrast to suppressed intraislet production, high peripheral expression of both inos mRNA and NO was found in MLD-SZ rats treated with PTX. Taken together, the data indicate that the effect on both systemic and intra-islet production of NO, suppression of autoreactive cell activation and of local type 1 cytokine release may contribute to the therapeutic benefit achieved by PTX in the rat. © 2001 Academic Press.

We have shown recently that xanthine derivative pentoxifylline (PTX) downregulates an inflammatory autoimmune process triggered in genetically susceptible Dark Agouti rats by multiple low doses of streptozotocin (MLD-SZ, 20 mg/kg/day ip for 5 days). We studied the cellular and molecular consequences of PTX treatment during MLD-SZ-induced diabetes with special emphasis on local vs. systemic production of inflammatory mediators. Administration of PTX (200 mg/kg/day for 10 days) during induction of the disease reduced clinical signs of diabetes and protected rats from development of destructive intrainsulitis. Pentoxifylline did not affect diabetogenic effect of single high dose of SZ (100 mg/kg SZ). Ex vivo analysis of the islets of Langerhans performed in early disease development revealed that PTX downregulates production of proinflammatory cytokines IFN-γ and TNF, as well as inducible nitric oxide synthase (iNOS) expression and NO production. In addition, PTX treatment suppressed splenocyte autoreactivity, as well as the frequency of cells expressing IL-2R and MHC class II antigens. There was no evidence of any changes in proportion of ICAM-1 and LFA-1 expressing splenocytes in comparison to control MLD-SZ-treated animals. In contrast to suppressed intraislet production, high peripheral expression of both inos mRNA and NO was found in MLD-SZ rats treated with PTX. Taken together, the data indicate that the effect on both systemic and intra-islet production of NO, suppression of autoreactive cell activation and of local type 1 cytokine release may contribute to the therapeutic benefit achieved by PTX in the rat. © 2001 Academic Press.

The effects of immunosuppressant cyclosporin A (CsA) on nitric oxide (NO) production and inducible NO synthase (iNOS) mRNA expression in rat C6 glioma cell line were investigated. CsA applied simultaneously with iNOS activator IFN-γ caused dose-dependent reduction of NO synthesis in confluent C6 cells, as determined by measuring accumulation of nitrite, an indicator of NO production, in 48 h culture supernatants. IFN-γ-induced expression of iNOS, but not interferon regulatory factor-1 (IRF-1) mRNA was reduced in CsA- treated cells. The enzymatic activity of iNOS was not changed by CsA, since it failed to affect NO production in cells in which iNOS had already been induced with IFN-γ and any further induction was blocked by protein synthesis inhibitor cycloheximide (CHX). FK506 was not able to mimic inhibitory effect of CsA on NO production in C6 cells, suggesting calcineurin-independent mechanism of CsA action.

The effects of immunosuppressant cyclosporin A (CsA) on nitric oxide (NO) production and inducible NO synthase (iNOS) mRNA expression in rat C6 glioma cell line were investigated. CsA applied simultaneously with iNOS activator IFN-γ caused dose-dependent reduction of NO synthesis in confluent C6 cells, as determined by measuring accumulation of nitrite, an indicator of NO production, in 48 h culture supernatants. IFN-γ-induced expression of iNOS, but not interferon regulatory factor-1 (IRF-1) mRNA was reduced in CsA- treated cells. The enzymatic activity of iNOS was not changed by CsA, since it failed to affect NO production in cells in which iNOS had already been induced with IFN-γ and any further induction was blocked by protein synthesis inhibitor cycloheximide (CHX). FK506 was not able to mimic inhibitory effect of CsA on NO production in C6 cells, suggesting calcineurin-independent mechanism of CsA action.

Considering the role of pleiotropic interleukin-1 (IL-1) in inflammation and autoimmunity, studies were designed to examine whether specific blockade of IL-1 may influence these processes in the CNS. Although the role of CD4+ T cells in eliciting clinical signs of experimental autoimmune encephalomyelitis (EAE) has been unequivocally demonstrated, the exact mechanism by which encephalitogenic cells initiate disease process and bring about clinical signs still remains to be defined. We have evaluated the effect of human recombinant interleukin-1 receptor antagonist (IL-1Ra) in vivo on the course of actively induced EAE in highly susceptible Dark Agouti (DA) rats. The rats which were treated during the induction phase of disease (days 0-6) with IL-1Ra (350 μg/rat/day) developed milder signs of EAE, when compared to saline-treated control animals immunized with encephalitogen, which developed severe single episode disease. The transfer of lymph node cells (LNC) isolated from MBP-primed DA rats and stimulated in vitro with MBP and ConA to naive syngeneic animals resulted in the development of EAE in all recipients. However, rats injected with LNC that have been stimulated in vitro in the presence of IL-1Ra (10 μg/ml) developed significantly milder disease. Diminished encephalitogenic capacity of LNC correlated with lower proliferative response to antigen and mitogen and decreased expression of IL- 2 receptors. These data provide further evidence that IL-1 is an important factor for activation of EAE inducing T lymphocytes.

Considering the role of pleiotropic interleukin-1 (IL-1) in inflammation and autoimmunity, studies were designed to examine whether specific blockade of IL-1 may influence these processes in the CNS. Although the role of CD4+ T cells in eliciting clinical signs of experimental autoimmune encephalomyelitis (EAE) has been unequivocally demonstrated, the exact mechanism by which encephalitogenic cells initiate disease process and bring about clinical signs still remains to be defined. We have evaluated the effect of human recombinant interleukin-1 receptor antagonist (IL-1Ra) in vivo on the course of actively induced EAE in highly susceptible Dark Agouti (DA) rats. The rats which were treated during the induction phase of disease (days 0-6) with IL-1Ra (350 μg/rat/day) developed milder signs of EAE, when compared to saline-treated control animals immunized with encephalitogen, which developed severe single episode disease. The transfer of lymph node cells (LNC) isolated from MBP-primed DA rats and stimulated in vitro with MBP and ConA to naive syngeneic animals resulted in the development of EAE in all recipients. However, rats injected with LNC that have been stimulated in vitro in the presence of IL-1Ra (10 μg/ml) developed significantly milder disease. Diminished encephalitogenic capacity of LNC correlated with lower proliferative response to antigen and mitogen and decreased expression of IL- 2 receptors. These data provide further evidence that IL-1 is an important factor for activation of EAE inducing T lymphocytes.