[Expression of inducible nitric oxide synthase was regulated by activating nuclear factor kappaB in mouse macrophages stimulated with ureaplasma urealyticum lipid-associated membrane proteins].

ABSTRACT

The aim was to investigate the molecular mechanisms responsible for the inducible nitric oxide synthase (iNOS) gene expression stimulated by lipid associated membrane proteins (LAMPs) of Ureaplasma urealyticum (Uu). Mouse macrophages were stimulated by Ureaplasma urealyticum LAMPs to analyze the production of nitric oxide (NO) and the expression of iNOS detected by RT-PCR and Western blot. The activation of NF-kappaB was examined in mouse macrophages treated with LAMPs by indirect immunofluorescence (IFA), immunocytochemistry and Western blot. The effects of pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-kappaB and of cycloheximide (CHX), a protein synthase inhibitor, on the expression of iNOS and on the activation of NF-kappaB were also investigated in mouse macrophages treated with LAMPs. Results showed Ureaplasma urealyticum LAMPs stimulated mouse macrophages to express iNOS and thus produce NO in dose- and time-dependent manners by activating nuclear factor kappaB. The activation of NF-kappaB and the expression of iNOS were inhibited by LAMPs combination with PDTC or CHX. In conclusion, these findings suggested Ureaplasma urealyticum may be an important pathogenic factor due to the ability of LAMPs to stimulate the expression of iNOS, which is probably medicated by the activation of NF-kappaB.