Proinflammatory cytokine and nitric oxide production by human macrophage stimulated with Trichomonas vaginalis

Abstract

Trichomonas vaginalis commonly causes vaginitis and perhaps cervicitis in women and urethritis in both sexes. Trichomonas vaginalis recruits various inflammatory cells, such as neutrophils and macrophage, around the site of inflammation. Macrophages play an important role in human immune system protecting against microorganism. Our previous experiment showed that mouse peritoneal macrophages are spontaneously cytotoxic for Trichomonas vaginalis, and their nitric oxide plays an important role in the host defense mechanism against Trichomonas vaginalis. In this study, we investigated wether human macrophages may be involved in inflammation induced by Trichomonas vaginalis. Human monocyte-derived macrophages(HMDM) were co-cultured with Trichomonas vaginalis(T016 isolate). Live, opsonized-live trichomonads, and Trichomonas vaginalis lysates increased proinflammatory cytokines such as TNF-alpha, IL-1 beta, IL-6 by HMDM, measured by ELISA and/or RT-PCR. The involvement of NF-kB signaling pathway in cytokine production was determined. Phospho NF-kB expression was observed by Western blot, nuclear translocation of activated NF-kB(NF-kB p65)was also confirmed by fluorescent microscopy after 30mins with live trichomonads. However, human macrophages showed increased nitric oxide production and iNOS expression measured by Griess reagent and Western blot, respectively when incubated with Trichomonas vaginalis. L-NMMA(nitric oxide inhibitor)-pretreated HMDM showed significantly reduced TNF-alpha expression by RT-PCR and ELISA. In conclusion, human macrophage may be involved in vaginal inflammation by Trichomonas vaginalis via proinflammatory cytokine and nitric oxide production. Also proinflammatory TNF-alpha production might be regulated by nitric oxide.