Gholiof Mahsa, Adamson-De Luca Emma, Wessels Jocelyn M
Department of Obstetrics and Gynecology, McMaster University, Hamilton, ON, Canada.
AIMA Laboratories Inc., Hamilton, ON, Canada.
Front Reprod Health. 2022 Aug 9;4:963752. doi: 10.3389/frph.2022.963752. eCollection 2022.
The intricate interactions between the host cells, bacteria, and immune components that reside in the female reproductive tract (FRT) are essential in maintaining reproductive tract homeostasis. Much of our current knowledge surrounding the FRT microbiota relates to the vaginal microbiota, where 'health' has long been associated with low bacterial diversity and dominance. This concept has recently been challenged as women can have a diverse vaginal microbial composition in the absence of symptomatic disease. The structures of the upper FRT (the endocervix, uterus, Fallopian tubes, and ovaries) have distinct, lower biomass microbiotas than the vagina; however, the existence of permanent microbiotas at these sites is disputed. During homeostasis, a balance exists between the FRT bacteria and the immune system that maintains immune quiescence. Alterations in the bacteria, immune system, or local environment may result in perturbances to the FRT microbiota, defined as dysbiosis. The inflammatory signature of a perturbed or "dysbiotic" FRT microbiota is characterized by elevated concentrations of pro-inflammatory cytokines in cervical and vaginal fluid. It appears that vaginal homeostasis can be disrupted by two different mechanisms: first, a shift toward increased bacterial diversity can trigger vaginal inflammation, and second, local immunity is altered in some manner, which disrupts the microbiota in response to an environmental change. FRT dysbiosis can have negative effects on reproductive health. This review will examine the increasing evidence for the involvement of the FRT microbiotas and inflammation in gynecologic conditions such as endometriosis, infertility, and endometrial and ovarian cancer; however, the precise mechanisms by which bacteria are involved in these conditions remains speculative at present. While only in their infancy, the use of antibiotics and probiotics to therapeutically alter the FRT microbiota is being studied and is discussed herein. Our current understanding of the intimate relationship between immunity and the FRT microbiota is in its early days, and more research is needed to deepen our mechanistic understanding of this relationship and to assess how our present knowledge can be harnessed to assist in diagnosis and treatment of gynecologic conditions.
宿主细胞、细菌和免疫成分之间复杂的相互作用存在于女性生殖道（FRT）中，对维持生殖道的稳态至关重要。我们目前关于FRT微生物群的许多知识都与阴道微生物群有关，长期以来，“健康”一直与低细菌多样性和优势菌相关。随着女性在没有症状性疾病的情况下也可能有多样的阴道微生物组成，这一概念最近受到了挑战。FRT上部（宫颈管、子宫、输卵管和卵巢）的结构具有与阴道不同的、生物量较低的微生物群；然而，这些部位是否存在常驻微生物群仍存在争议。在稳态期间，FRT细菌与免疫系统之间存在平衡，维持免疫静止。细菌、免疫系统或局部环境的改变可能导致FRT微生物群紊乱，即生态失调。受干扰或“生态失调”的FRT微生物群的炎症特征表现为宫颈和阴道液中促炎细胞因子浓度升高。阴道稳态似乎可通过两种不同机制被破坏：第一，细菌多样性增加的转变可引发阴道炎症；第二，局部免疫以某种方式改变，从而在环境变化时破坏微生物群。FRT生态失调会对生殖健康产生负面影响。本综述将研究越来越多的证据，证明FRT微生物群和炎症与子宫内膜异位症、不孕症以及子宫内膜癌和卵巢癌等妇科疾病有关；然而，目前细菌参与这些疾病的确切机制仍具有推测性。虽然抗生素和益生菌用于治疗性改变FRT微生物群的研究尚处于起步阶段，但本文对此进行了讨论。我们目前对免疫与FRT微生物群之间密切关系的理解尚处于初期，需要更多研究来深化我们对这种关系的机制理解，并评估如何利用我们目前的知识来辅助妇科疾病的诊断和治疗。
