Molecular detection of microbial colonization in cervical mucus of women with and without endometriosis

Abstract

ProblemIntrauterine microbial colonization and its association with the pathogenesis of endometriosis via an innate immune cascade have been reported. As a potential source of microbial transmission, information on microbial colonization in cervical mucus is unknown. We investigated pattern of microbiota in the cervical mucus collected from women with and without endometriosis using next‐generation sequencing (NGS) technology.Method of studyCervical mucus samples were collected from women with (n = 30) and without (n = 39) endometriosis. The communities of microbiota in cervical mucus in the endometriosis group and the control group were examined by Gram staining and NGS targeting the V5‐V6 region of 16S ribosomal RNA gene. Copy number of some target bacteria was detected by real‐time PCR.ResultsWe confirmed visual presence of bacteria in cervical mucus by Gram staining. NGS analysis showed that distribution of microbiota was similar in cervical mucus of women with and without endometriosis regardless of the phases of the menstrual cycle. In addition to predominant Lactobacilli spp., the populations of Corynebacterium, Enterobacteriaceae, Flavobacterium, Pseudomonas, and Streptococcus were increased in the endometriosis group. Of them, Enterobacteriaceae and Streptococcus were identified as the more significant candidates in the endometriosis group than in controls by real‐time PCR (P < 0.05 for each).ConclusionOur NGS analysis of cervical mucus indicated that among a variable microbiota, two candidates (Enterobacteriaceae and Streptococcus) were more frequently detected in women with endometriosis. Further investigation is needed to elucidate a mechanistic link of these bacteria in the pathophysiology of endometriosis.

Endometriosis and the microbiome: a systematic review

“…Unclear or absent from the full texts in all but one human study was whether study participants were consecutively recruited, permitting the closest representation of patients with endometriosis. Human studies that had an NOS score of ≥6 (out of 8, as the nonresponse rate category was not applicable for these study methodologies) had reliably strong definitions of cases versus controls, appropriate selection of controls, and laparoscopic evidence of endometriosis presence or absence …”

“…The various kits and sequencing methods used are outlined in Table . Of the seven studies that used 16S rRNA amplicon sequencing, only five discussed the targeted sequencing region . Each study targeted different regions, including region V3/V4, region V4, region V3–V5, region V4/V5 and region V5/V6 .…”

“…α ‐Diversity is used to describe the diversity of a microbial community within a single sample or site whereas β ‐diversity is an index used to compare the diversity of microbial communities across different samples or sites . Five of eighteen studies assessed α ‐diversity . Three studies used Shannon's Diversity Index to assess α ‐diversity .…”

“…Five of eighteen studies assessed α ‐diversity . Three studies used Shannon's Diversity Index to assess α ‐diversity . The study by Yuan et al .…”

Regulation of Inflammation Pathways and Inflammasome by Sex Steroid Hormones in Endometriosis

“…Most of the studies have reported the presence of members of phyla Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria, among others, as part of "health" uterine microbiota (127)(128)(129), and that changes of this diversity and its abundance are related to alterations in endometrial function (127,130,131), benign uterine pathologies (128,132,133), or endometrial cancer. In the case of endometriosis, changes of taxonomic bacterial composition to potentially pathogen bacteria in patients diagnosed with the disease have been detected in peritoneal fluid, cervical mucus, and cervicovaginal microbiota (129,134,135). However, studies that detect the real changes in endometrial microbiota related to endometriosis are lacking; furthermore, studies carried out to date in general lack a control group with healthy women (without any benign pathology) and face difficulties to obtain endometrial samples, among other technical complications (126,134,136).…”