AUTHOR=Li Ping , Wei Kehong , He Xia , Zhang Lu , Liu Zhaoxia , Wei Jing , Chen Xiaomei , Wei Hong , Chen Tingtao 

TITLE=Vaginal Probiotic Lactobacillus crispatus Seems to Inhibit Sperm Activity and Subsequently Reduces Pregnancies in Rat

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=9

YEAR=2021

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2021.705690

DOI=10.3389/fcell.2021.705690

ISSN=2296-634X

ABSTRACT=<sec><title>Background</title><p>The vaginal microbiota is associated with the health of the female reproductive system and the offspring. <italic>Lactobacillus crispatus</italic> belongs to one of the most important vaginal probiotics, while its role in the agglutination and immobilization of human sperm, fertility, and offspring health is unclear.</p></sec><sec><title>Methods</title><p>Adherence assays, sperm motility assays, and Ca<sup>2+</sup>-detecting assays were used to analyze the adherence properties and sperm motility of <italic>L. crispatus</italic> Lcr-MH175, attenuated <italic>Salmonella typhimurium</italic> VNP20009, engineered <italic>S. typhimurium</italic> VNP20009 DNase I, and <italic>Escherichia coli</italic> O157:H7 <italic>in vitro.</italic> The rat reproductive model was further developed to study the role of <italic>L. crispatus</italic> on reproduction and offspring health, using high-throughput sequencing, real-time PCR, and molecular biology techniques.</p></sec><sec><title>Results</title><p>Our results indicated that <italic>L. crispatus</italic>, VNP20009, VNP20009 DNase I, and <italic>E. coli</italic> O157:H7 significantly inhibited the sperm motility <italic>in vitro via</italic> adversely affecting the sperm intracellular Ca<sup>2+</sup> concentration and showed a high adhesion to sperms. The <italic>in vivo</italic> results indicated that <italic>L. crispatus</italic> and other tested bacteria greatly reduced the pregnancy rates, but <italic>L. crispatus</italic> had a positive effect on maternal health and offspring development. Moreover, the transplantation of <italic>L. crispatus</italic> could sustain a normal bacterial composition of the vaginal microbiota in healthy rats and markedly reduced the expression of uterine inflammatory factors (toll-like receptor-4/nuclear factor kappa-B, tumor necrosis factor-α, production of interleukin-1β, etc.) and apoptosis factors (Fas Ligand, Bcl-2-associated X protein/B cell lymphoma-2, etc.) compared with the other tested strains.</p></sec><sec><title>Conclusion</title><p>Our study demonstrated that the vaginal probiotic <italic>L. crispatus</italic> greatly affected the sperm activity and could also reduce pregnancies through its adhesion property, which might account for some unexplained infertility. Therefore, more caution should be paid when using <italic>L. crispatus</italic> as a vaginal viable preparation in women of child-bearing age, especially for women whose partners have abnormal sperms.</p></sec>