Differential vaginal expression of interleukin-1 system cytokines in the presence of Mycoplasma hominis and Ureaplasma urealyticum in pregnant women

Abstract

Objective: The genital mycoplasmas, Ureaplasma urealyticum and Mycoplasma hominis, are commonly identified in the vagina of healthy pregnant women. However, these microorganisms are the most common isolates from the amniotic fluids of women in preterm labor. The mechanisms responsible for vaginal colonization and ascent to the uterus remain undetermined. We evaluated the association between U. urealyticum and M. hominis vaginal colonization and the presence of pro-inflammatory and anti-inflammatory interleukin-1 system components in asymptomatic pregnant women of different ethnicities. Methods: Vaginal specimens, obtained from 224 first trimester pregnant women, were assayed for interleukin-1β (IL-1β) and IL-1 receptor antagonist (IL-1ra) concentrations by ELISA. U. urealyticum and M. hominis vaginal colonization were identified by polymerase chain reaction (PCR). Results: Vaginal colonization with M. hominis was identified in 37 (16.5%) women, and was more prevalent in black (18.9%) and Hispanic (20.9%) than in white (4.2%) women (p = 0.01). U. urealyticum was present in 84 (37.5%) women and there was no ethnic disparity in its detection. M. hominis colonization was associated with elevated median vaginal IL-1β concentrations in both black women (p = 0.02) and Hispanic women (p = 0.04), and was unrelated to vaginal IL-1ra concentrations. In marked contrast, U. urealyticum colonization was associated with elevations in vaginal IL-1ra levels, but not with IL-1β concentrations, in black women (p = 0.02) and Hispanic women (p < 0.0001) and marginally in white women (p = 0.06). Conclusion: M. hominis colonization in healthy pregnant women is associated with localized pro-inflammatory immune activation, while U. urealyticum colonization is associated with immune suppression.