The mechanisms underlying sulfamethoxazole metaboites regulated cytokine production

Abstract

For many decades, sulphonamides together with trimethoprim have been used as antimicrobial agents against bacterial and protozoan infections in immunocompromised patients. During bacterial infection, proinflammatory cytokines including tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), as well as anti-inflammatory cytokines such as IL-10 are produced by macrophages. Here, we investigated the mechanisms and effects of sulfamethoxazole metabolites, which are related to hypersensitivity reactions, on cytokine production in primary human differentiated blood macrophages (PBMac). PBMac were incubated with the drug metabolites for 30 minutes and followed by the addition of bacterial endotoxin (LPS) for another 15 minutes to 3 hours. The results from the Real time Quantitative RT-PCR showed that the mRNA expressions of IL-6 and IL-10 in metabolites-treated cells were downregulated, compared to the LPS treatment alone. We also demonstrated the protein levels of IL-6, IL-10 and TNF-alpha were suppressed. To delineate the molecular mechanisms involved in the metabolites-induced cytokine production, we measured the activity levels of mitogen-activated protein kinases (MAPK), which are known to be key signaling modulators in cytokine induction. The results illustrated that sulfamethoxazole metabolites abrogated the LPSinduced MAPK phosphorylation, concomitant with their effects on cytokine downregulation. Furthermore, sulfamethoxazole metabolites could inhibit the LPS-activated nuclear factor-kappa B (NF-kappa B) functions. In conclusion, our data demonstrated that in addition to their antimicrobial effects, sulfamethoxazole metabolites may play a role in limiting the propagation of uncontrolled inflammation, via the suppression of MAPK and NF-kappa B activities, in microbial infections.