RESUMO
Endometrial receptivity (ER) is a key factor required for the successful implantation of the embryo. However, the evaluation of ER is challenging, as a nondisruptive sampling of endometrial biomaterial by conventional methods is only possible outside of the embryo transfer (ET) cycle. We propose a novel approach for the assessment of ER-microbiological and cytokine profiling of menstrual blood aspirated directly from the uterine cavity at the beginning of the cryo-ET cycle. The aim of the pilot study was to evaluate its prognostic potential regarding the outcome of the in vitro fertilization procedure. Samples collected from a cohort of 42 patients undergoing cryo-ET were analyzed by a multiplex immunoassay (48 various cytokines, chemokines, and growth factors) and a real-time PCR assay (28 relevant microbial taxa and 3 members of the Herpesviridae family). Significant differences between groups of patients who achieved and did not achieve pregnancy were observed for G-CSF, GRO-α, IL-6, IL-9, MCP-1, M-CSF, SDF-1α, TNF-ß, TRAIL, SCF, IP-10, and MIG (p < 0.05), whereas microbial profiles were not associated with the outcome of cryo-ET. It appeared that levels of IP-10 and SCGF-ß were significantly lower (p < 0.05), in patients with endometriosis. Menstrual blood may provide great opportunities to noninvasively investigate various parameters of the endometrium.
RESUMO
For decades, the endometrium was considered to be a sterile environment. However, now this concept is disputed, and there is growing evidence that microbiota composition might affect endometrial receptivity. Routine clinical management of infertility is still limited to a microbiological assessment of the lower reproductive tract. The purpose of this study was to compare the abundance of various bacterial, fungal, and viral species, qualitatively and quantitatively, in vaginal, cervical, and endometrial biomaterial of infertile patients. A total of 300 samples from 100 infertile patients of a private assisted reproduction clinic were analyzed. A broad real-time polymerase chain reaction panel was used to identify 28 relevant microbial taxa as well as three members of the Herpesviridae family. All patients underwent endometrial biopsy for further histopathological evaluation. Analysis of the microbial diversity (within the boundaries of the detection panel) revealed that Shannon indexes in the cervix and vagina were similar (1.4 × 10-2 (1.6 × 10-3 - 6.5 × 10-1) vs 1.9 × 10-2 (2.3 × 10-3 - 5.3 × 10-1), respectively, p = 0.502), whereas endometrial indexes differed significantly from both regions (0 (0 - 1.4 × 10-1), p < 0.0001). Surprisingly, 17 microbial and viral taxa were detected in at least one sample. Endometrium exhibited a quite distinct microbiological profile, being different at the detection rates of 14 taxa (p < 0.05). Remarkably, 4% and 2% of endometrial samples were positive for Cytomegalovirus and Candida spp., respectively, while these were undetectable in corresponding cervical and vaginal samples. Prevalence of the Gardnerella vaginalis + Prevotella bivia + Porphyromonas spp. group in endometrium was associated with a low abundance of Lactobacillus spp. (p = 0.039). No noteworthy associations were identified between various microbiota characteristics and clinical parameters, such as chronic endometritis, uterine polyps and adhesions, endometriosis, and a history of sexually transmitted infections. These findings indicate that the microbiological profile of the endometrium is unique, and the analysis of the lower reproductive tract should supplement, rather than be a substitute for it.