IL-1β, IL-6, TNFα, fetal fibronectin, and endotoxin in the lower genital tract of pregnant women with bacterial vaginosis

Background. In our studies on women with bacterial vaginosis (BV) in early pregnancy a strong association has been found between BV and the levels of endotoxin or interleukin-1 alpha (IL-1 alpha) in the lower genital tract. In the present study we investigated if an association could be found between BV and other cytokines (IL-1 beta, IL-6, tumor necrosis factor alpha, TNF) or fetal fibronectin (FFN). The cytokine-inducing capacity of endotoxins present in the cervical mucus was explored in a monocytic cell assay. Methods. Cervical mucus or cervicovaginal fluid was collected from women with (BV) and without BV (nonBV) attending a family planning unit for first trimester abortion. The concentrations of IL-1 beta, IL-6, TNF, and FFN were determined by quantitative enzyme immunoassays. TNF was determined in 63 women (BV, n=25) out of whom 37 (BV; n=11) were analyzed for IL-1 beta and the remaining 26 for IL-6 (BV, n=14). FFN was determined in another 36 women (BV, n=19). The cytokine-inducing capacity of endotoxin-containing cervical mucus and purified endotoxin of Prevotella bivia were studied by an in vitro cell assay using a human monocytic cell line (THP-1). Results. IL-1 beta and IL-6 were found in almost all women. The levels of IL-1 beta, but not IL-6, TNF or FFN, were significantly increased in women with BV compared with the nonBV women (p<0.05). Purified endotoxin from P. bivia, and cervical mucus from BV women containing high levels of endotoxin were able to induce a cytokine response (IL-6) in monocytic cells in vitro. Conclusion. BV is associated with increased levels of IL-1 beta in the lower genital tract of pregnant women in the first trimester. The ability of BV-associated endotoxins to induce cytokine production in monocytic cells may partly explain the increased IL-1 beta levels.