Gut microbiota imbalance and its correlations with hormone and inflammatory factors in patients with stage 3/4 endometriosis

Endometriosis (EM) in reproductive females has an incidence of 6-10% and greatly affects female fertility, quality of life, and long-term health. The gut microbiota can affect the physiological and pathological processes of humans through various pathways, such as those involving the nervous and endocrine systems and immunity, and it plays important roles in endocrine and inflammatory diseases. Whether the gut microbiota plays a role in EM has gradually attracted researchers' attention. In the present study, fecal and blood samples were collected from 12 patients with stage 3/4 EM and 12 healthy controls. We performed 16S rRNA high-throughput sequencing to compare the gut microbiota between the EM and control groups. Serum levels of hormones and inflammatory cytokines were measured. We found that compared with the control group, the EM group had a lower α diversity of gut microbiota and a higher Firmicutes/Bacteroidetes ratio. The abundances of various taxa (such as Actinobacteria, Tenericutes, Blautia, Bifidobacterium, Dorea, and Streptococcus) were significantly different between the two groups. The taxon with the highest abundance in the EM group was Prevotella_7, and that in the control group was Coprococcus_2. The serum levels of E2 and IL-8 were significantly higher in the EM group than in the control group (E2: EM group 74.7 ± 22.5 pg/L vs CON group 47.9 ± 12.5 pg/L; IL-8: EM group 6.39 ± 1.59 pg/mL vs CON group 4.14 ± 0.73 pg/mL). Additionally, the gut microbiota of the EM group was enriched for the microbial function categories environmental information processing, endocrine system, and immune system. Correlations were detected between each of Blautia and Dorea abundance and estradiol level and between Subdoligranulum abundance and IL-8 level. This study elucidated the associations between the gut microbiota and both serum hormones and inflammatory factors in EM. However, the findings need to be verified in future studies.