Differential anti-inflammatory effects of immunosuppressive drugs: Cyclosporin, rapamycin and FK-506 on inducible nitric oxide synthase, nitric oxide, cyclooxygenase-2 and PGE(2) production

Objective and Design: Cyclosporin, FK-506 and rapamycin have similar but di stinct modes of interaction with cyclophilins, calcineurins and transcripti on factors. These immunosuppressive drugs have also been shown to inhibit c ytotoxic and inflammatory responses in macrophage. Therefore, we evaluated the mechanism of action of these drugs on iNOS and COX-2 expression by macr ophages, the products of which (NO and PGE(2)) have cytotoxic and proinflam matory activities. Materials and Methods: The murine macrophage cell line RAW 264.7 was grown as monolayer cultures. The effects of pharmacologically relevant concentrat ions of cyclosporin, rapamycin and FK-506 were evaluated in the presence an d absence of lipopolysaccharide (LPS) which is a known inducer of iNOS and COX-2. Subsequently the expression of iNOS and COX-2 were analyzed by Weste rn and Northern analysis. The production of NO and PGE(2) were assayed by G reiss and RIA respectively. Results: Cyclosporin (1-5 mu g/ml) and rapamycin (1.0-10 nM) but not FK-506 (5-10 nM) inhibited both INOS and COX-2 expression at mRNA level which led to significant inhibition of NO and PGE(2) production. Conclusion: These studies characterize differential mechanistic capacity of the immunophilin-binding immunosuppressive drugs (comparable to hydrocorti sone) to inhibit both INOS and COX-2 expression. Inhibition of iNOS and COX -2 mRNA accumulation by cyclosporin and rapamycin seem to be distinct. Thes e studies also highlight potential anti-inflammatory properties of these dr ugs in addition to their known immunosuppressive activity.