Microorganisms in the reproductive system and probiotic's regulatory effects on reproductive health

Abstract

The presence of microbial communities in the reproductive tract has been revealed, and this resident microbiota is involved in the maintenance of health. Intentional modulation via probiotics has been proposed as a possible strategy to enhance reproductive health and reduce the risk of diseases. The male seminal microbiota has been suggested as an important factor that influences a couple's health, pregnancy outcomes, and offspring health. Probiotics have been reported to play a role in male fertility and to affect the health of mothers and offspring. While the female reproductive microbiota is more complicated and has been identified in both the upper and lower reproductive systems, they together contribute to health maintenance. Probiotics have shown regulatory effects on the female reproductive tract, thereby contributing to homeostasis of the tract and influencing the health of offspring. Further, through transmission of bacteria or through other indirect mechanisms, the parent's reproductive microbiota and probiotic intervention influence infant gut colonization and immunity development, with potential health consequences. In vitro and in vivo studies have explored the mechanisms underlying the benefits of probiotic administration and intervention, and an array of positive results, such as modulation of microbiota composition, regulation of metabolism, promotion of the epithelial barrier, and improvement of immune function, have been observed. Herein, we review the state of the art in reproductive system microbiota and its role in health and reproduction, as well as the beneficial effects of probiotics on reproductive health and their contributions to the prevention of associated diseases.

Keywords: BTB, Blood-testis barrier; BV, Bacterial vaginosis; DEHP, Diethylhexyl phthalate; FMT, Fecal microbiota transplantation; FSH, Follicle-stimulating hormone; GDM, Gestational diabetes mellitus; PCOS, Polycystic ovary syndrome; Probiotic; Regulation effect; Reproduction; Reproductive microbiome; Reproductive system; TLR, Toll-like receptor; VMT, Vaginal microbiota transplantation.

Graphical abstract

Fig. 1

Proposed modes of action of probiotics on reproductive health. Probiotics may exert beneficial effects on reproduction through the modulation of microbiota composition, regulation of metabolism, promotion of the epithelial barrier, and improvement of immune function.

Fig. 2

Overview of the potential pathway by which probiotics affect reproductive health in both males and females as well as their offspring. 1. Probiotic supplements have positive effects on testicular function, improving semen quality, which may influence couple and offspring health through sexual intercourse. 2. Probiotic supplements can modulate the microbiota composition of the gut and regulate the metabolism of the female, thus impacting microbiome configuration, biofilm integrity, and the immune response of female reproductive organs. The affected female reproductive tract then influences the health of infants through mother-to-child transmission. Additionally, probiotic supplements can influence bacterial transmission from the gut to milk, and then influence infant health through breast feeding. 3. Probiotics may also act through the vagina by changing its microbiota composition directly and balancing its microbial ecology, thus contributing to vaginal reproductive health.