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Powell AM, Ali Khan FZ, Ravel J, Elovitz MA. Untangling Associations of Microbiomes of Pregnancy and Preterm Birth. Clin Perinatol 2024; 51:425-439. [PMID: 38705650 PMCID: PMC11070640 DOI: 10.1016/j.clp.2024.02.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2024]
Abstract
This review illuminates the complex interplay between various maternal microbiomes and their influence on preterm birth (PTB), a driving and persistent contributor to neonatal morbidity and mortality. Here, we examine the dynamics of oral, gastrointestinal (gut), placental, and vaginal microbiomes, dissecting their roles in the pathogenesis of PTB. Importantly, focusing on the vaginal microbiome and PTB, the review highlights (1) a protective role of Lactobacillus species; (2) an increased risk with select anaerobes; and (3) the influence of social health determinants on the composition of vaginal microbial communities.
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Affiliation(s)
- Anna Maya Powell
- Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Phipps 249, Baltimore, MD 21287, USA
| | - Fouzia Zahid Ali Khan
- Department of Gynecology and Obstetrics, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Phipps 249, Baltimore, MD 21287, USA
| | - Jacques Ravel
- Department of Microbiology and Immunology, Institute for Genome Sciences, 670 West Baltimore Street, 3rd Floor, Room 3173, Baltimore, MD 21201, USA
| | - Michal A Elovitz
- Department of Obstetrics and Gynecology, Women's Health Research, Icahn School of Medicine at Mount Sinai, Women's Biomedical Research Institute, 1468 Madison Avenue, New York, NY 10029, USA.
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Odendaal J, Black N, Bennett PR, Brosens J, Quenby S, MacIntyre DA. The endometrial microbiota and early pregnancy loss. Hum Reprod 2024; 39:638-646. [PMID: 38195891 PMCID: PMC10988105 DOI: 10.1093/humrep/dead274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 12/18/2023] [Indexed: 01/11/2024] Open
Abstract
The human endometrium is a dynamic entity that plays a pivotal role in mediating the complex interplay between the mother and developing embryo. Endometrial disruption can lead to pregnancy loss, impacting both maternal physical and psychological health. Recent research suggests that the endometrial microbiota may play a role in this, although the exact mechanisms are still being explored, aided by recent technological advancements and our growing understanding of host immune responses. Suboptimal or dysbiotic vaginal microbiota, characterized by increased microbial diversity and reduced Lactobacillus dominance, has been associated with various adverse reproductive events, including miscarriage. However, the mechanisms linking the lower reproductive tract microbiota with pregnancy loss remain unclear. Recent observational studies implicate a potential microbial continuum between the vaginal and endometrial niche in patients with pregnancy loss; however, transcervical sampling of the low biomass endometrium is highly prone to cross-contamination, which is often not controlled for. In this review, we explore emerging evidence supporting the theory that a dysbiotic endometrial microbiota may modulate key inflammatory pathways required for successful embryo implantation and pregnancy development. We also highlight that a greater understanding of the endometrial microbiota, its relationship with the local endometrial microenvironment, and potential interventions remain a focus for future research.
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Affiliation(s)
- Joshua Odendaal
- Division of Biomedical Sciences, Clinical Sciences Research Laboratories, Warwick Medical School, Tommy's National Centre for Miscarriage Research, University of Warwick, Coventry, UK
- University Hospitals Coventry & Warwickshire, Coventry, UK
| | - Naomi Black
- Division of Biomedical Sciences, Clinical Sciences Research Laboratories, Warwick Medical School, Tommy's National Centre for Miscarriage Research, University of Warwick, Coventry, UK
- University Hospitals Coventry & Warwickshire, Coventry, UK
| | - Phillip R Bennett
- Tommy’s National Centre for Miscarriage Research, Imperial College London, London, UK
- March of Dimes Prematurity Research Centre at Imperial College London, London, UK
- Imperial College Parturition Research Group, Institute of Reproductive and Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Jan Brosens
- Division of Biomedical Sciences, Clinical Sciences Research Laboratories, Warwick Medical School, Tommy's National Centre for Miscarriage Research, University of Warwick, Coventry, UK
- University Hospitals Coventry & Warwickshire, Coventry, UK
| | - Siobhan Quenby
- Division of Biomedical Sciences, Clinical Sciences Research Laboratories, Warwick Medical School, Tommy's National Centre for Miscarriage Research, University of Warwick, Coventry, UK
- University Hospitals Coventry & Warwickshire, Coventry, UK
| | - David A MacIntyre
- Tommy’s National Centre for Miscarriage Research, Imperial College London, London, UK
- March of Dimes Prematurity Research Centre at Imperial College London, London, UK
- Imperial College Parturition Research Group, Institute of Reproductive and Developmental Biology, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
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Onyango S, Mi JD, Koech A, Okiro P, Temmerman M, von Dadelszen P, Tribe RM, Omuse G. Microbiota dynamics, metabolic and immune interactions in the cervicovaginal environment and their role in spontaneous preterm birth. Front Immunol 2023; 14:1306473. [PMID: 38196946 PMCID: PMC10774218 DOI: 10.3389/fimmu.2023.1306473] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 12/11/2023] [Indexed: 01/11/2024] Open
Abstract
Differences in the cervicovaginal microbiota are associated with spontaneous preterm birth (sPTB), a significant cause of infant morbidity and mortality. Although establishing a direct causal link between cervicovaginal microbiota and sPTB remains challenging, recent advancements in sequencing technologies have facilitated the identification of microbial markers potentially linked to sPTB. Despite variations in findings, a recurring observation suggests that sPTB is associated with a more diverse and less stable vaginal microbiota across pregnancy trimesters. It is hypothesized that sPTB risk is likely to be modified via an intricate host-microbe interactions rather than due to the presence of a single microbial taxon or broad community state. Nonetheless, lactobacilli dominance is generally associated with term outcomes and contributes to a healthy vaginal environment through the production of lactic acid/maintenance of a low pH that excludes other pathogenic microorganisms. Additionally, the innate immunity of the host and metabolic interactions between cervicovaginal microbiota, such as the production of bacteriocins and the use of proteolytic enzymes, exerts a profound influence on microbial populations, activities, and host immune responses. These interplays collectively impact pregnancy outcomes. This review aims to summarize the complexity of cervicovaginal environment and microbiota dynamics, and associations with bacterial vaginosis and sPTB. There is also consideration on how probiotics may mitigate the risk of sPTB and bacterial vaginosis.
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Affiliation(s)
- Stanley Onyango
- Department of Pathology, Aga Khan University, Nairobi, Kenya
- Centre of Excellence Women and Child Health, Aga Khan University, Nairobi, Kenya
| | - Jia Dai Mi
- Faculty of Life Sciences and Medicine, Department of Women and Children’s Health, School of Life Course and Population Sciences, King’s College London, London, United Kingdom
| | - Angela Koech
- Centre of Excellence Women and Child Health, Aga Khan University, Nairobi, Kenya
| | - Patricia Okiro
- Department of Pathology, Aga Khan University, Nairobi, Kenya
| | - Marleen Temmerman
- Centre of Excellence Women and Child Health, Aga Khan University, Nairobi, Kenya
| | - Peter von Dadelszen
- Faculty of Life Sciences and Medicine, Department of Women and Children’s Health, School of Life Course and Population Sciences, King’s College London, London, United Kingdom
| | - Rachel M. Tribe
- Faculty of Life Sciences and Medicine, Department of Women and Children’s Health, School of Life Course and Population Sciences, King’s College London, London, United Kingdom
| | - Geoffrey Omuse
- Department of Pathology, Aga Khan University, Nairobi, Kenya
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