The Therapeutic Potential of Lactobacillus crispatus for Chronic Endometritis: A Comprehensive Clinical Trial and Experimental Investigation

Chronic endometritis (CE) is common in patients with infertility, and it is challenging to treat with antibiotics as bacteria often acquire resistance to the antibiotics, which leads to frequent recurrence of the condition. Probiotics, especially Lactobacillus species, are known for their usefulness in treating reproductive infections. This study evaluated Lactobacillus crispatus chen 01 (L. crispatus chen 01) isolated from healthy women who were 22–30 years old and married with children. In vitro experiments showed that L. crispatus chen 01 inhibited pathogens and reduced inflammation in CE mice by downregulating inflammatory proteins (TLR, MyD88, and p65/p-p65; L + Abx vs M, P < 0.01), improving histopathological features, and inhibiting bacterial growth. It also regulated endometrial processes, such as enhancing embryo implantation (BMP2 and Wnt4, L + Abx vs M, P < 0.01) via the Wnt/β-catenin pathway, leading to increased pregnancy rates (L + Abx vs M, 100% vs 0%) in mice. In clinical trials, L. crispatus chen 01 improved progesterone levels (P = 0.0038), pregnancy rates (C vs Abx + L. c, 76.19% vs 87.18%), and pathological changes in CE patients. The findings from this study identify the administration of L. crispatus chen 01 as a promising intervention for CE that could improve pregnancy rates.