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bioRxiv · 10.1101/2024.02.18.580923

Characterisation and comparison of semen microbiota and sperm function in men with infertility, recurrent miscarriage, or proven fertility

Mowla, S.·Farahani, L.·Tharakan, T.·Davies, R.·Correia, G. D.·Lee, Y. S.·Kundu, S.·Khanjani, S.·Sindi, E.·Rai, R.·Regan, L.·Khalifa, D.·Henkel, R.·Minhas, S.·S. Dhillo, W.·Ben Nagi, J.·Bennett, P.·MacIntrye, D. A.·Jayasena, C. N.
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Abstract

Several studies have associated seminal microbiota abnormalities with male infertility but have yielded differing results owing to their limited sizes or depths of analyses. The semen microbiota during recurrent pregnancy loss (RPL) has not been investigated. Comprehensively assessing the seminal microbiota in men with reproductive disorders could elucidate its potential role in clinical management. We used semen analysis, terminal-deoxynucleotidyl-transferase-mediated-deoxyuridine-triphosphate-nick-end-labelling, Comet DNA fragmentation, luminol ROS chemiluminescence and metataxonomic profiling of semen microbiota by16S rRNA amplicon sequencing in this prospective, cross-section study to investigate composition and bacterial load of seminal bacterial genera and species, semen parameters, reactive oxidative species (ROS), and sperm DNA fragmentation in men with reproductive disorders and proven fathers. 223 men were enrolled included healthy men with proven paternity (n=63), the male partners in a couple encountering RPL (n=46), men with male factor infertility (n=58), and the male partners of couples unexplained infertility (n=56). Rates of high sperm DNA fragmentation, elevated ROS and oligospermia were more prevalent in the study group compared with control. In all groups, semen microbiota clustered into three major genera-dominant groups (1, Streptococcus; 2, Prevotella; 3, Lactobacillus and Gardnerella); no species clusters were identified. Group 2 had the highest microbial richness (P<0.001), alpha-diversity (P<0.001), and bacterial load (P<0.0001). Overall bacterial composition or load has not found to associate with semen analysis, ROS or DNA fragmentation. Whilst, global perturbation of the seminal microbiota is not associated with male reproductive disorders, men with unidentified seminal Flavobacterium are more likely to have abnormal seminal analysis. Future studies may elucidate if Flavobacterium reduction has therapeutic potential.

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Mowla, S., Farahani, L., Tharakan, T., Davies, R., Correia, G. D., Lee, Y. S., Kundu, S., Khanjani, S., Sindi, E., Rai, R., Regan, L., Khalifa, D., Henkel, R., Minhas, S., S. Dhillo, W., Ben Nagi, J., Bennett, P., MacIntrye, D. A., Jayasena, C. N.. 2024-02-20. Characterisation and comparison of semen microbiota and sperm function in men with infertility, recurrent miscarriage, or proven fertility. https://doi.org/10.1101/2024.02.18.580923

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