The Dwindling Microbiota of Aerobic Vaginitis, an Inflammatory State Enriched in Pathobionts with Limited TLR Stimulation.

Eline F M Oerlemans,Ilke De Boeck,Stijn Wittouck,Kateryna Ruban,Gert Bellen,Sander Wuyts,Sarah Lebeer,Marianne F L Van Den Broek,Gilbert G G Donders,Camille Nina Allonsius

doi:10.3390/diagnostics10110879

Eline F M Oerlemans, Ilke De Boeck + Show 8 more

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https://doi.org/10.3390/diagnostics10110879

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Journal: Diagnostics	Publication Date: Oct 28, 2020
Citations: 21	License type: CC BY 4.0

Affiliation: University of Antwerp, Antwerp University Hospital

Abstract

While bacterial vaginosis (BV) is a well-known type of vaginal dysbiosis, aerobic vaginitis (AV) is an inflammatory condition that remains understudied and under-recognised. It predisposes women to serious complications including urogenital infections and pregnancy problems. Here, we investigated the bacterial community in AV to explore its possible role in AV pathogenesis. We collected vaginal lavage fluid samples of women (n = 58) classified by wet-mount microscopy as suffering from AV or BV and included an asymptomatic reference group without signs of AV or BV. AV samples showed reduced absolute abundances of bacteria in general and specifically of lactobacilli by qPCR, but 16S rRNA gene sequencing and amplicon sequence variant analysis revealed that Lactobacillus remained the dominant taxon in 25% of the AV samples studied. The other AV samples showed high relative abundances of Streptococcus agalactiae and, unexpectedly, the anaerobes Gardnerella vaginalis and Prevotella bivia in more than half of the AV samples studied. Yet, despite increased relative abundance of these potential pathogens or pathobionts in the AV bacterial communities, the AV samples only slightly stimulated Toll-like receptor 4 and showed reduced activation of Toll-like receptor 2/6, receptors of two pathways central to mucosal immunity. Our findings indicate that the reduced total bacterial abundance with associated enrichment in certain pathobionts in AV might be mainly a consequence of the inflammatory conditions and/or altered hormonal regulation rather than bacteria being a major cause of the inflammation.

Highlights

Aerobic vaginitis (AV) is a highly relevant, yet still underexplored vaginal condition, first described by Donders et al in 2002 [1]
The vaginal bacterial communities of women suffering from aerobic vaginitis (AV) (n = 20) or bacterial vaginosis (BV) (n = 20, 19 samples passed quality control), diagnosed by conventional phase contrast microscopy (Table S1 and Figure S1), and a reference group of women (n = 18) with a normal Lactobacillus-dominated (NL) microscopy image were characterized by 16S rRNA gene sequencing
Of our samples was initially based on wet-mount microscopy [1], 16S rRNA gene sequencing analysis confirmed that most samples of the NL and BV group showed distinct community compositions as expected (Figure 1, Figure S2)

Summary

Introduction

Aerobic vaginitis (AV) is a highly relevant, yet still underexplored vaginal condition, first described by Donders et al in 2002 [1]. (i) a variable amount of inflammation, (ii) thinning of the vaginal epithelium, and (iii) a disturbed bacterial community, deviating from the often-encountered high abundance of lactobacilli [2] These three features are microscopically examined and numerically scored by evaluating the number and appearance of leukocytes, immature epithelial cells (or parabasal cells), as well as the presence of specific members of the bacterial community based on their morphologies. As these characteristics are present in their most severe form in desquamative inflammatory vaginitis, this condition could be seen as the most severe form of AV [1]. BV can be recognized by (i) a malodorous vaginal discharge, (ii) an elevated pH of

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