Dysbiosis of the endometrial microbiota and its association with inflammatory cytokines in endometrial cancer

The underlying molecular mechanisms involved in the pathogenesis of endometrial cancer (EC) are still not well understood. Our goal was to investigate the composition of the endometrial microbiota and the association with inflammatory cytokines in EC. Endometrial microbiota profiles of women with EC (n = 25) and benign uterine lesions (BUL, n = 25) were assessed by 16S ribosomal RNA gene amplicon sequencing. The expression levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-17 (IL-17) mRNA and protein in the endometrial tissues of the two groups were determined by real-time quantitative polymerase chain reaction and Western blot, respectively. There were significant differences in alpha diversity based on the observed operational taxonomic units (P = .002), Pielou evenness (P = .001), and Shannon index (P < .001) between EC and BUL groups. Significant differences were also found in Bray-Curtis (P = .001) and unweighted UniFrac (P = .001) beta diversity measures between the two groups. At the genus level, Micrococcus was more abundant in the EC group. Pseudoramibacter_Eubacterium, Rhodobacter, Vogesella, Bilophila, Rheinheimera, and Megamonas were enriched in the BUL group. There were no differences in IL-8 and IL-17 protein levels between the two groups, except IL-6 protein levels. However, the mRNA expression levels of IL-6, IL-8, and IL-17 were significantly different. Moreover, the relative abundances of Micrococcus was positively correlated with IL-6, and IL-17 mRNA levels. In conclusion, our results suggested that dysbiosis of endometrial microbiota and the inflammatory cytokines were associated with Micrococcus in EC patients, which might be useful for exploration of the mechanism between the endometrial microbiota and inflammatory responses in future studies.