Female reproductive tract-organ axes

Abstract

The female reproductive tract (FRT) and remote/versatile organs in the body share bidirectional communication. In this review, we discuss the framework of the “FRT-organ axes.” Each axis, namely, the vagina-gut axis, uterus-gut axis, ovary-gut axis, vagina-bladder axis, vagina-oral axis, uterus-oral axis, vagina-brain axis, uterus-brain axis, and vagina-joint axis, is comprehensively discussed separately. Each axis could be involved in the pathogenesis of not only gynecological diseases but also diseases occurring apart from the FRT. Although the microbiota is clearly a key player in the FRT-organ axes, more quantitative insight into the homeostasis of the microbiota could be provided by host function measurements rather than current microbe-centric approaches. Therefore, investigation of the FRT-organ axes would provide us with a multicentric approach, including immune, neural, endocrine, and metabolic aspects, for understanding the homeostatic mechanism of women’s bodies. The framework of the FRT-organ axes could also provide insights into finding new therapeutic approaches to maintain women’s health.

Relationship between vaginal and oral microbiome in patients of human papillomavirus (HPV) infection and cervical cancer

“…This suggests that the oral cavity and vagina share a common microbial community and that there is also a reciprocal exchange of related microbial communities. The salivary microbiota of participants with bacterial vaginosis (BV) was more diverse than that of BV-negative participants [ 36 ], and Prevotella intermedia and Porphyromonas endodontalis were enriched in the subgingival gingival microbiota of BV-infected women compared to women without BV, which indicates the presence of a vagino–oral axis [ 37 ]. Moreover, Porphyromonas and Prevotella have been proven to have carcinogenic potential via several different mechanisms.…”

“…Vaginal microbiome transformations along the cervical carcinogenesis route have been characterized, but the associated impacts on the oral niche remain underexplored. This study revealed that the oral cavity contains a significantly greater number of bacterial species than does the vagina and revealed extensive bidirectional sharing of microbial communities between the vaginal and oral cavities through an emerging vagino–oral axis [ 37 ]. This study provides insight into the microbial community shared between the oral and vaginal parts of the human body, as well as the exchange of related microbial communities.…”

Association between gut microbiota and menstrual disorders: a two-sample Mendelian randomization study

“…Excess short-chain fatty acids may be a possible cause of cervicovaginal inflammation, according to an in vitro investigation ( Delgado-Diaz et al, 2020 ). Therefore, vaginal microecological dysregulation brought on by the flow of short-chain fatty acids from the gut to the vagina may cause menstruation abnormalities ( Takada et al, 2023 ).…”

“…When circulating estrogen reaches the distal epithelium of the vagina, it modifies the physiological traits of the cells that line the vagina, including the generation of mucus and glycogen. Since glycogen can be a vital source of energy for Lactobacilli , increased glycogen promotes Lactobacillus dominance in the vagina ( Witkin, 2018 ; Linhares et al, 2019 ; Takada et al, 2023 ). Therefore, the number of Lactobacillus in the vaginal microbiota can be influenced by the number of bacteria in the gut microbiota that metabolize estrogen.…”

Does “all disease begin in the gut”? The gut-organ cross talk in the microbiome

“…Dysbiosis of the gut microbiota has been linked to an increased risk of vaginal infections, including BV and VVC (Tuddenham et al 2019 ; Han et al 2021 ). Furthermore, emerging evidence suggests that the transmission of microbial communities between the gut and vagina may occur through various routes, including the bloodstream, mucosal surfaces, and shared anatomical pathways (Takada et al 2023 ) .…”