Activation of PPAR-gamma by carbon monoxide from CORM-2 leads to the inhibition of iNOS but not COX-2 expression in LPS-stimulated macrophages.

The effect of CO on the expression of iNOS and COX-2 was investigated by using a CO-releasing molecule (CORM)-2 in LPS-activated RAW 264.7 cells in vitro. Interestingly, CORM-2 significantly inhibited iNOS (NO) but not COX-2 (PGE(2)) expression. PPAR-gamma activators such as troglitazone, GW1929, and 15-deoxy-Delta12, 14- prostaglandin J(2) showed preferential inhibitory effect on iNOS over COX-2 expression in LPS-activated macrophages. The same effect was shown in lung tissues (iNOS, COX-2) and serum (NO, PGE(2)) when administered of CORM-2 in LPS-induced septic mice, indicating that CO derived from CORM-2 differentially regulates iNOS and COX-2 through PPAR-gamma activation under inflammation state.