Potential biomarkers of infertility associated with microbiome imbalances

Abstract

Problem: The aim of this study was to investigate the possible relationship between vaginal/rectal microbiome disbalances and miRNA expression with infertility.

Method of study: Observational, exploratory, preliminary study. A total of 287 multiple IVF failure infertile patients were recruited. Twenty fertile women, not IVF failure, were recruited as the control group. Swab samples were collected from the vagina and rectum. Microbial composition by NGS and miRNA expression by real-time PCR of vaginal and rectal samples was measured. Immunometabolic markers from blood (insulin, vitamin D, LDL-cholesterol, ANA, TPO, Tg, and ASCA antibodies) and saliva (sIgA) were analyzed.

Result(s): Infertile patients showed a lower bacterial richness and increased Firmicutes/Bacteroidetes ratio at rectal level and an increased Lactobacillus brevis/Lactobacillus iners ratio in vaginal samples regarding the fertile group. In the same rectal swab samples, we found that miR-21-5p, which is associated with tight junction disruption and yeast overgrowth, is upregulated and that miR-155-5p, which is associated with inflammation, is overexpressed in the unexplained infertile group (*p < .05). These deregulated miRNAs were also upregulated in the vaginal samples from the same patients (*p < .05).

Conclusion: miRNAs could be potential biomarkers of the inflammatory impact of microbiome disbalances in unexplained infertile women.

Keywords: autoantibodies; infertility; intestinal permeability; miRNAs; microbiota.

FIGURE 1

Differences in bacterial communities using 16S rRNA sequencing of vaginal and rectal swabs. Bacterial gene count using 16S rRNA sequencing of rectal swabs (A). The relative proportion of microorganisms in rectal (B) and vaginal (C) swabs. Data are presented as total gene counts [median (middle line), interquartile range (top and bottom lines)], and statistical significance (Unpaired t-test) was defined as p < .05

FIGURE 2

Expression levels of dysregulated miRNAs identified in the selection cohort. Expression profiles of significantly altered miRNAs identified in the vaginal and anal swabs from infertile women. Data are presented as the relative expression values normalized to RNU48/RNU6B [median (middle line), interquartile range (top and bottom lines)], statistical significance (Mann-Whitney U test or Unpaired t-test) was defined as p < .05. *** designates p ≤ .001; ** designates p < .01; * designates p < .05. (A) For vaginal miR-21 (B) and miR-155 (C); for rectal miR-21 (D) and miR-155

FIGURE 3

Diagnostic estimates of miRNAs identified as dysregulated in the selection cohort. ROC curve analysis was performed for each of the miRNAs identified as being dysregulated in the selection cohort and the associated AUC and diagnostic sensitivities and specificities for individual miRNAs are presented in Table 1. (A) For vaginal miR-21 (B) and miR-155. (C) For rectal miR-21 (D) and miR-155