Effects of florfenicol on LPS-induced nitric oxide and prostaglandin E₂ production in RAW 264.7 macrophages.

Florfenicol, an antibiotic commonly used to treat infections, has previously been shown to modulate lipopolysaccharide (LPS)-induced early cytokine responses by blocking the nuclear factor-κB (NF-κB) pathway. In this study, we investigated the effects of florfenicol on nitric oxide (NO) and prostaglandin E₂ (PGE₂) production as well as on inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression in LPS-stimulated murine RAW 264.7 macrophages. We also analysed the effects of florfenicol on mitogen-activated protein kinase (MAPK) pathways. Florfenicol significantly inhibited LPS-induced NO and PGE₂ production. Consistent with these observations, mRNA and protein expression of iNOS and COX-2 were also inhibited by florfenicol in a dose-dependent manner. Furthermore, phosphorylation of p38 and extracellular signal-regulated kinase 1/2 (ERK1/2) in LPS-stimulated RAW 264.7 cells was suppressed by florfenicol. However, c-Jun N-terminal kinase (JNK) phosphorylation remained unaffected. Using specific inhibitors of ERK and p38, we found that florfenicol may inhibit NO and PGE₂ mostly through ERK and p38 pathway. These results suggest that florfenicol inhibits NO and PGE₂ production in conjunction with an inhibition of iNOS and COX-2 expression, at least partially via suppression of ERK1/2 and p38 MAPK phosphorylation.