Vaginal microbiota #15

Profiling the vaginal microbiota to prevent preterm birth

^{Pruski P, Correia GDS, Lewis HV, et al. Direct on-swab metabolic profiling of vaginal microbiome host interactions during pregnancy and preterm birth. Nat Commun. 2021 Oct;12(1):5967.}

Predicting the risk of preterm birth using a simple, rapid, and inexpensive method is a challenge for obstetricians, who still lack a reliable predictive method for this clinical complication, the leading cause of death in children under the age of five. The risk factors are well known: vaginal dysbiosis associated with local inflammation.

A team of researchers had the idea of using their recently-described DESI-MS (Desorption Electrospray Ionization Mass Spectrometry) analysis method to identify – in less than 3 minutes and without the need for sample preparation – the metabolites present in the cervicovaginal mucosa. Their hypothesis? The metabolome thus characterized may make it possible to predict the composition of the vaginal microbiota and local immune and inflammatory responses, and to monitor their development towards states associated with the risk of preterm birth. DESI-MS was used to analyze more than 1,000 cervicovaginal samples from 365 pregnant women in two cohorts.

Among the metabolites detected, 113 made it possible to effectively distinguish between two types of microbiota: one depleted and the other dominated by lactobacilli, a marker of good vaginal health. The metabolic profile obtained using DESI- MS also predicted the levels of several immune markers (IL-1β, IL-8, C3b/iC3b, IgG3, IgG2, MBL – Mannose-Binding Lectine) measured in a subgroup of 391 women. Some of these (C3b, IL-1β, IgG2, IgG3) were found at high levels in Lactobacillus- depleted vaginal microbiomes, indicating activation of the local innate and adaptive immune response.

In a final series of tests, the metabolic vaginal profile obtained using DESI-MS could not reliably predict the direct risk of preterm birth. However, the researchers foresee potential clinical applications. Monitoring vaginal metabolites using DESI- MS could help detect changes in the vaginal microbiota and local immune markers associated with preterm birth.