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Dabee S, Passmore JAS, Heffron R, Jaspan HB. The Complex Link between the Female Genital Microbiota, Genital Infections, and Inflammation. Infect Immun 2021; 89:e00487-20. [PMID: 33558324 PMCID: PMC8091093 DOI: 10.1128/iai.00487-20] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The female genital tract microbiota is part of a complex ecosystem influenced by several physiological, genetic, and behavioral factors. It is uniquely linked to a woman's mucosal immunity and plays a critical role in the regulation of genital inflammation. A vaginal microbiota characterized by a high abundance of lactobacilli and low overall bacterial diversity is associated with lower inflammation. On the other hand, a more diverse microbiota is linked to high mucosal inflammation levels, a compromised genital epithelial barrier, and an increased risk of sexually transmitted infections and other conditions. Several bacterial taxa such as Gardnerella spp., Prevotella spp., Sneathia spp., and Atopobium spp. are well known to have adverse effects; however, the definitive cause of this microbial dysbiosis is yet to be fully elucidated. The aim of this review is to discuss the multiple ways in which the microbiota influences the overall genital inflammatory milieu and to explore the causes and consequences of this inflammatory response. While there is abundant evidence linking a diverse genital microbiota to elevated inflammation, understanding the risk factors and mechanisms through which it affects genital health is essential. A robust appreciation of these factors is important for identifying effective prevention and treatment strategies.
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Affiliation(s)
- Smritee Dabee
- Seattle Children's Research Institute, Seattle, Washington, USA
| | - Jo-Ann S Passmore
- Institute of Infectious Disease and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- CAPRISA Centre of Excellence in HIV Prevention, University of Cape Town, Cape Town, South Africa
- National Health Laboratory Service, Cape Town, South Africa
| | | | - Heather B Jaspan
- Seattle Children's Research Institute, Seattle, Washington, USA
- Institute of Infectious Disease and Molecular Medicine (IDM), University of Cape Town, Cape Town, South Africa
- University of Washington, Seattle, Washington, USA
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Amabebe E, Anumba DOC. Psychosocial Stress, Cortisol Levels, and Maintenance of Vaginal Health. Front Endocrinol (Lausanne) 2018; 9:568. [PMID: 30319548 PMCID: PMC6165882 DOI: 10.3389/fendo.2018.00568] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 09/05/2018] [Indexed: 01/01/2023] Open
Abstract
Stress stimuli are ubiquitous and women do not enjoy any exemptions. The physiologic "fight-or-flight" response may be deleterious to the female lower genital tract microbiome if the stress stimuli persist for longer than necessary. Persistent exposure to psychosocial stress and stimulation of the hypothalamic-pituitary-adrenal (HPA) and sympathetic-adrenal-medullary (SAM) axes, and associated hormones are risk factors for several infections including genitourinary tract infections. Though this could be due to a dysregulated immune response, a cortisol-induced inhibition of vaginal glycogen deposition may be involved especially in the instance of vaginal infection. The estrogen-related increased vaginal glycogen and epithelial maturation are required for the maintenance of a healthy vaginal ecosystem (eubiosis). The ability of cortisol to disrupt this process as indicated in animal models is important in the pathogenesis of vaginal dysbiosis and the subsequent development of infection and inflammation. This phenomenon may be more crucial in pregnancy where a healthy Lactobacillus-dominated vaginal microbiota is sacrosanct, and there is local production of more corticotropin-releasing hormone (CRH) from the decidua, fetal membranes and placenta. To highlight the relationship between the stress hormone cortisol and the vaginal microbiomial architecture and function, the potential role of cortisol in the maintenance of vaginal health is examined.
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The role of lactic acid production by probiotic Lactobacillus species in vaginal health. Res Microbiol 2017; 168:782-792. [PMID: 28435139 DOI: 10.1016/j.resmic.2017.04.001] [Citation(s) in RCA: 264] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 04/03/2017] [Accepted: 04/03/2017] [Indexed: 12/12/2022]
Abstract
Vaginal eubiosis is characterised by beneficial lactobacillus-dominated microbiota. In contrast, vaginal dysbiosis (e.g. bacterial vaginosis, BV), characterised by an overgrowth of multiple anaerobes, is associated with an increased risk of adverse urogenital and reproductive health outcomes. A major distinguishing feature between the vaginal environment in states of eubiosis and dysbiosis is a high concentration of lactic acid, produced by lactobacilli, that acidifies the vagina in eubiosis versus a sharp drop in lactic acid and an increase in pH in dysbiosis. Here we review the antimicrobial, antiviral and immunomodulatory properties of lactic acid and the use of lactic acid and lactobacilli probiotics in preventing or treating BV.
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Smith SB, Ravel J. The vaginal microbiota, host defence and reproductive physiology. J Physiol 2016; 595:451-463. [PMID: 27373840 DOI: 10.1113/jp271694] [Citation(s) in RCA: 198] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 01/28/2016] [Indexed: 02/06/2023] Open
Abstract
The interaction between the human host and the vaginal microbiota is highly dynamic. Major changes in the vaginal physiology and microbiota over a woman's lifetime are largely shaped by transitional periods such as puberty, menopause and pregnancy, while daily fluctuations in microbial composition observed through culture-independent studies are more likely to be the results of daily life activities and behaviours. The vaginal microbiota of reproductive-aged women is largely made up of at least five different community state types. Four of these community state types are dominated by lactic-acid producing Lactobacillus spp. while the fifth is commonly composed of anaerobes and strict anaerobes and is sometimes associated with vaginal symptoms. The production of lactic acid has been associated with contributing to the overall health of the vagina due to its direct and indirect effects on pathogens and host defence. Some species associated with non-Lactobacillus vaginal microbiota may trigger immune responses as well as degrade the host mucosa, processes that ultimately increase susceptibility to infections and contribute to negative reproductive outcomes such as infertility and preterm birth. Further studies are needed to better understand the functional underpinnings of how the vaginal microbiota affect host physiology but also how host physiology affects the vaginal microbiota. Understanding this fine-tuned interaction is key to maintaining women's reproductive health.
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Affiliation(s)
- Steven B Smith
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Jacques Ravel
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.,Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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Aldunate M, Srbinovski D, Hearps AC, Latham CF, Ramsland PA, Gugasyan R, Cone RA, Tachedjian G. Antimicrobial and immune modulatory effects of lactic acid and short chain fatty acids produced by vaginal microbiota associated with eubiosis and bacterial vaginosis. Front Physiol 2015; 6:164. [PMID: 26082720 PMCID: PMC4451362 DOI: 10.3389/fphys.2015.00164] [Citation(s) in RCA: 201] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/12/2015] [Indexed: 12/14/2022] Open
Abstract
Lactic acid and short chain fatty acids (SCFAs) produced by vaginal microbiota have reported antimicrobial and immune modulatory activities indicating their potential as biomarkers of disease and/or disease susceptibility. In asymptomatic women of reproductive-age the vaginal microbiota is comprised of lactic acid-producing bacteria that are primarily responsible for the production of lactic acid present at ~110 mM and acidifying the vaginal milieu to pH ~3.5. In contrast, bacterial vaginosis (BV), a dysbiosis of the vaginal microbiota, is characterized by decreased lactic acid-producing microbiota and increased diverse anaerobic bacteria accompanied by an elevated pH>4.5. BV is also characterized by a dramatic loss of lactic acid and greater concentrations of mixed SCFAs including acetate, propionate, butyrate, and succinate. Notably women with lactic acid-producing microbiota have more favorable reproductive and sexual health outcomes compared to women with BV. Regarding the latter, BV is associated with increased susceptibility to sexually transmitted infections (STIs) including HIV. In vitro studies demonstrate that lactic acid produced by vaginal microbiota has microbicidal and virucidal activities that may protect against STIs and endogenous opportunistic bacteria as well as immune modulatory properties that require further characterization with regard to their effects on the vaginal mucosa. In contrast, BV-associated SCFAs have far less antimicrobial activity with the potential to contribute to a pro-inflammatory vaginal environment. Here we review the composition of lactic acid and SCFAs in respective states of eubiosis (non-BV) or dysbiosis (BV), their effects on susceptibility to bacterial/viral STIs and whether they have inherent microbicidal/virucidal and immune modulatory properties. We also explore their potential as biomarkers for the presence and/or increased susceptibility to STIs.
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Affiliation(s)
- Muriel Aldunate
- Centre for Biomedical Research, Burnet Institute Melbourne, VIC, Australia ; Department of Microbiology, Nursing and Health, Faculty of Medicine, Monash University Clayton, VIC, Australia
| | - Daniela Srbinovski
- Centre for Biomedical Research, Burnet Institute Melbourne, VIC, Australia ; Department of Microbiology, Nursing and Health, Faculty of Medicine, Monash University Clayton, VIC, Australia
| | - Anna C Hearps
- Centre for Biomedical Research, Burnet Institute Melbourne, VIC, Australia ; Department of Infectious Disease, Monash University Melbourne, VIC, Australia
| | - Catherine F Latham
- Centre for Biomedical Research, Burnet Institute Melbourne, VIC, Australia
| | - Paul A Ramsland
- Centre for Biomedical Research, Burnet Institute Melbourne, VIC, Australia ; Department of Immunology, Monash University Melbourne, VIC, Australia ; Department of Surgery Austin Health, The University of Melbourne Heidelberg, VIC, Australia ; School of Biomedical Sciences, CHIRI Biosciences, Curtin University Perth, WA, Australia
| | - Raffi Gugasyan
- Centre for Biomedical Research, Burnet Institute Melbourne, VIC, Australia ; Department of Immunology, Monash University Melbourne, VIC, Australia
| | - Richard A Cone
- Department of Biophysics, Johns Hopkins University Baltimore, MD, USA
| | - Gilda Tachedjian
- Centre for Biomedical Research, Burnet Institute Melbourne, VIC, Australia ; Department of Microbiology, Nursing and Health, Faculty of Medicine, Monash University Clayton, VIC, Australia ; Department of Infectious Disease, Monash University Melbourne, VIC, Australia ; Department of Microbiology and Immunology, The University of Melbourne at the Peter Doherty Institute for Infection and Immunity Parkville, VIC, Australia
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