Host and Microbiome Interplay Shapes the Vaginal Microenvironment

The association between lifestyle factors and the composition of the vaginal microbiota: a review

PURPOSE

The vaginal microbiota offers valuable insights into women's sexual health and the risk of developing sexually transmitted infections (STIs) and bacterial vaginosis. Despite the public health implications of changes in the vaginal environment, existing data on this topic remain sparse.

METHODS

Following the PRISMA statement guidelines, we consulted five bibliographic databases, focusing on five main daily habits and behaviors. We included only studies published up to October 2023, investigating the influence of personal hygiene, sexual behaviors, hormonal contraception, smoking, alcohol consumption, and psychosocial stress on the vaginal microbiota using next-generation sequencing.

RESULTS

Based on our inclusion criteria, we incorporated 37 studies into this review. Hormonal contraception and personal hygiene were found to promote eubiosis of the vaginal microbiota. In contrast, sexual behaviors, smoking, alcohol consumption, and psychosocial stress were associated with an increased susceptibility to bacterial vaginosis, STIs, and severe pelvic inflammatory diseases due to a modified vaginal microbiota. Black ethnicity emerged as a confounding factor, with this population showing unstable vaginal microbiota. Oral contraception and a stable male sexual partner were found to favor Lactobacillus colonization, acting as a protective factor. Conversely, non-hormonal contraception and unprotected or non-penile/vaginal sexual activity increased the incidence of vaginal inflammation and bacterial vaginosis by disturbing the vaginal microbiota and reducing Lactobacillus abundance.

CONCLUSION

Daily habits and lifestyle can influence the composition of the vaginal microbiota, thereby affecting vaginal health. Disturbances in the vaginal microbiota could be associated factors for STIs and vaginosis. Therefore, prioritizing more appropriate management of the vaginal microbiota is crucial.

Linking reproductive tract microbiota to premature ovarian insufficiency: Pathophysiological mechanisms and therapies

Over the past decade, research on the human microbiota has become a hot topic. Among them, the female reproductive tract (FRT) also has a specific microbiota that maintains the body's health and dynamic balance, especially in the reproductive aspect. When the FRT ecosystem is dysregulated, changes in immune and metabolic signals can lead to pathological and physiological changes such as chronic inflammation, epithelial barrier disruption, changes in cell proliferation and apoptosis, and dysregulation of angiogenesis and metabolism, thereby causing disruption of the female endocrine system. Premature ovarian insufficiency (POI), a clinical syndrome of ovarian dysfunction, is primarily influenced by immune, genetic, and environmental factors. New evidence suggests that dysbiosis of the FRT microbiota and/or the presence of specific bacteria may contribute to the occurrence and progression of POI. This influence occurs through both direct and indirect mechanisms, including the regulation of estrogen metabolism. The use of probiotics or microbiota transplantation to regulate the microbiome has also been proven to be beneficial in improving ovarian function and the quality of life in women with premature aging. This article provides an overview of the interrelationships and roles between the FRT microbiome and POI in recent years, to fully understand the risk factors affecting female reproductive health, and to offer insights for the future diagnosis, treatment, and application of the FRT microbiome in POI patients.

Defining Vaginal Community Dynamics: daily microbiome transitions, the role of menstruation, bacteriophages, and bacterial genes

BACKGROUND

The composition of the vaginal microbiota during the menstrual cycle is dynamic, with some women remaining eu- or dysbiotic and others transitioning between these states. What defines these dynamics, and whether these differences are microbiome-intrinsic or mostly driven by the host is unknown. To address this, we characterized 49 healthy, young women by metagenomic sequencing of daily vaginal swabs during a menstrual cycle. We classified the dynamics of the vaginal microbiome and assessed the impact of host behavior as well as microbiome differences at the species, strain, gene, and phage levels.

RESULTS

Based on the daily shifts in community state types (CSTs) during a menstrual cycle, the vaginal microbiome was classified into four Vaginal Community Dynamics (VCDs) and reported in a classification tool, named VALODY: constant eubiotic, constant dysbiotic, menses-related, and unstable dysbiotic. The abundance of bacteria, phages, and bacterial gene content was compared between the four VCDs. Women with different VCDs showed significant differences in relative phage abundance and bacterial composition even when assigned to the same CST. Women with unstable VCDs had higher phage counts and were more likely dominated by L. iners. Their Gardnerella spp. strains were also more likely to harbor bacteriocin-coding genes.

CONCLUSIONS

The VCDs present a novel time series classification that highlights the complexity of varying degrees of vaginal dysbiosis. Knowing the differences in phage gene abundances and the genomic strains present allows a deeper understanding of the initiation and maintenance of permanent dysbiosis. Applying the VCDs to further characterize the different types of microbiome dynamics qualifies the investigation of disease and enables comparisons at individual and population levels. Based on our data, to be able to classify a dysbiotic sample into the accurate VCD, clinicians would need two to three mid-cycle samples and two samples during menses. In the future, it will be important to address whether transient VCDs pose a similar risk profile to persistent dysbiosis with similar clinical outcomes. This framework may aid interdisciplinary translational teams in deciphering the role of the vaginal microbiome in women's health and reproduction. Video Abstract.

The influence of the vaginal ecosystem on vaginitis, bacterial vaginosis, and sexually transmitted diseases: an epidemiological study and literature review

PURPOSE

This study aimed to demonstrate the correlation between altered balance of the vaginal ecosystem and increased risk of vaginitis, bacterial vaginosis, and sexually transmitted diseases and the association between specific alterations found in fresh bacterioscopic examinations (FBE) and the risk of certain infections.

METHODS

A retrospective, monocentric study was conducted from January 2013 to December 2023. Patients who underwent FBE and vaginal swabs following reported symptoms or suspected syndromic pictures of vulvovaginal infections were included.

RESULTS

Two thousand one hundred ten patients were included and divided into a control group (n = 811, 38.4%) and a pathological group (n = 1299 patients, 61.6%), based on the presence of alterations at the FBE. In the pathological group, 1185 women (91% of positive FBE) had vaginal infections detected through vaginal swabs. The presence of lactobacilli and typical inflammatory cells was detected in 111 (8%) women with pathological FBE and correlated with higher rates of positive swabs for common germs (n = 104, 94%), often leading to co-infections (n = 30, 29%). Conversely, Döderlein's cytolysis (n = 56, 4.3% of positive FBE) indicated a predominance of positive human papillomavirus (HPV) swabs (n = 33, 59%). The presence of fungal elements (n = 208, 16% of positive FBE) suggested a higher prevalence of co-infections (n = 62, 30%). Similarly, mixed bacterial flora (n = 470, 36% of positive FBE) and Trichomonas vaginalis (n = 11, 0.8% of positive FBE) correlated with positive swabs for other pathogens, except for Mycoplasma (n = 0). Bacterial vaginosis (n = 443, 34% of positive FBE) was linked to co-infections (n = 142, 32%) and HPV (n = 123, 28%).

CONCLUSION

The importance of conducting FBE in patients with vulvovaginal symptoms is emphasized. This approach aids in determining the need for further diagnostic tests like vaginal swabs, guided by microscopic findings. A strong correlation emerges between the presence of specific alterations in the FBE and an increased prevalence of certain infections.

Vaginal microbiota and gynecological cancers: a complex and evolving relationship

The vagina hosts a community of microorganisms known as the vaginal microbiota. This community is relatively stable and straightforward, with Lactobacillus species being the most dominant members. The vaginal microbiota has various functions that are essential for maintaining human health and balance. For example, it can metabolise dietary nutrients, produce growth factors, communicate with other bacteria, modulate the immune system, and prevent the invasion of harmful pathogens. When the vaginal microbiota is disrupted, it can lead to diseases and infections. The observed disturbance is distinguished by a reduction in the prevalence of Lactobacillus and a concurrent rise in the number of other bacterial species that exhibit a higher tolerance to low oxygen levels. Gynecologic cancers are a group of cancers that affect the female reproductive organs and tissues, such as the ovaries, uterus, cervix, vagina, vulva, and endometrium. These cancers are a major global health problem for women. Understanding the complex interactions between the host and the vaginal microorganisms may provide new insights into the prevention and treatment of gynecologic cancers. This could improve the quality of life and health outcomes for women.

The microbiome in recurrent pregnancy loss - A scoping review

Recurrent pregnancy loss (RPL) is a troubling condition that affects couples worldwide. Despite extensive research efforts, many RPL cases remain unexplained, highlighting the need for novel approaches to unravel its underlying mechanisms. Recent advances in microbiome research have shed light on the potential role of the microbiome in reproductive health and outcomes. Based on a systematic literature research, this review aims to comprehensively explore the current understanding of the microbiome's involvement in RPL, focusing on the vaginal, endometrial, and gut microbiomes. Evidence from the available studies is examined to explain the relationship between the microbiome and RPL. Furthermore, we discuss the diagnostic potential of the microbiome, therapeutic interventions, and future directions in microbiome research for RPL. Understanding the complex interactions between the microbiome and reproductive health holds promise for developing targeted interventions to help patients today diagnosed as unexplained.

Global perspectives on the burden of sexually transmitted diseases: A narrative review

Sexually transmitted diseases (STDs) pose a significant global health challenge with far-reaching social, economic, and public health implications. These infections have haunted humanity from ancient times to today, transcending geographical boundaries and cultural contexts. This article explores the multifaceted landscape of STDs, delving into their epidemiology, pathophysiology, clinical manifestations, and global response strategies. The global prevalence of STDs is staggering, with millions of new cases reported annually. Prominent among these infections is HIV/AIDS, which remains a major global health crisis, affecting over 38 million people worldwide. Additionally, bacterial STDs like chlamydia, gonorrhea, and syphilis continue to pose significant health risks, with millions of new cases reported yearly. Beyond the physical manifestations, STDs have profound social and economic implications. They can result in severe reproductive health issues, stigma, discrimination, and psychological distress, burdening healthcare systems and affecting individuals' quality of life. The global response to STDs has been multifaceted, with international organizations and governments implementing various prevention and control strategies, including sexual education programs and scaling up access to testing and treatment. However, challenges persist, including disparities in healthcare access, sociocultural factors influencing transmission, and evolving pathogens with increasing resistance to treatment. Through case studies and real-world examples, we illuminate the human stories behind the statistics, highlighting the lived experiences of individuals grappling with STDs and the complex interplay of factors shaping their journeys. Ultimately, this review calls for continued research, innovative strategies, and sustained global commitment to mitigating the burden of STDs and promoting sexual health and well-being for all.

Vaginal microbiomes show ethnic evolutionary dynamics and positive selection of Lactobacillus adhesins driven by a long-term niche-specific process

The vaginal microbiome's composition varies among ethnicities. However, the evolutionary landscape of the vaginal microbiome in the multi-ethnic context remains understudied. We perform a systematic evolutionary analysis of 351 vaginal microbiome samples from 35 multi-ethnic pregnant women, in addition to two validation cohorts, totaling 462 samples from 90 women. Microbiome alpha diversity and community state dynamics show strong ethnic signatures. Lactobacillaceae have a higher ratio of non-synonymous to synonymous polymorphism and lower nucleotide diversity than non-Lactobacillaceae in all ethnicities, with a large repertoire of positively selected genes, including the mucin-binding and cell wall anchor genes. These evolutionary dynamics are driven by the long-term evolutionary process unique to the human vaginal niche. Finally, we propose an evolutionary model reflecting the environmental niches of microbes. Our study reveals the extensive ethnic signatures in vaginal microbial ecology and evolution, highlighting the importance of studying the host-microbiome ecosystem from an evolutionary perspective.

Harnessing the power within: engineering the microbiome for enhanced gynecologic health

Abstract

Although numerous studies have demonstrated the impact of microbiome manipulation on human health, research on the microbiome's influence on female health remains relatively limited despite substantial disease burden. In light of this, we present a selected review of clinical trials and preclinical studies targeting both the vaginal and gut microbiomes for the prevention or treatment of various gynecologic conditions. Specifically, we explore studies that leverage microbiota transplants, probiotics, prebiotics, diet modifications, and engineered microbial strains. A healthy vaginal microbiome for females of reproductive age consists of lactic acid-producing bacteria predominantly of the Lactobacillus genus, which serves as a protective barrier against pathogens and maintains a balanced ecosystem. The gut microbiota's production of short-chain fatty acids, metabolism of primary bile acids, and modulation of sex steroid levels have significant implications for the interplay between host and microbes throughout the body, ultimately impacting reproductive health. By harnessing interventions that modulate both the vaginal and gut microbiomes, it becomes possible to not only maintain homeostasis but also mitigate pathological conditions. While the field is still working toward making broad clinical recommendations, the current studies demonstrate that manipulating the microbiome holds great potential for addressing diverse gynecologic conditions.

Lay summary

Manipulating the microbiome has recently entered popular culture, with various diets thought to aid the microbes that live within us. These microbes live in different locations of our body and accordingly help us digest food, modulate our immune system, and influence reproductive health. The role of the microbes living in and influencing the female reproductive tract remains understudied despite known roles in common conditions such as vulvovaginal candidiasis (affecting 75% of females in their lifetime), bacterial vaginosis (25% of females in their lifetime), cervical HPV infection (80% of females in their lifetime), endometriosis (6-10% of females of reproductive age), and polycystic ovary syndrome (10-12% of females of reproductive age). Here, we review four different approaches used to manipulate the female reproductive tract and gastrointestinal system microbiomes: microbiota transplants, probiotics, prebiotics, and dietary interventions, and the use of engineered microbial strains. In doing so, we aim to stimulate discussion on new ways to understand and treat female reproductive health conditions.

Vaginal microbiota: Potential targets for vulvovaginal candidiasis infection

Vulvovaginal candidiasis (VVC) is the second most common cause of vaginal infection globally after bacterial vaginosis (BV) and associated with adverse reproductive and obstetric outcomes, including preterm delivery, sexually transmitted infections and pelvic inflammatory disease. Although effective control of VVC is achievable with the use of traditional treatment strategies (i.e., antifungals), the possibility of drug intolerance, treatment failure and recurrence, as well as the appearance of antifungal-resistant Candida species remain critical challenges. Therefore, alternative therapeutic strategies against VVC are urgently required. In recent years, an improved understanding of the dysbiotic vaginal microbiota (VMB) during VVC has prompted the consideration of administering -biotics to restore the balance of the VMB within the context of VVC prevention and treatment. Here, we aim to summarize the current evidence of the anti-Candida effects of probiotics, postbiotics and synbiotics and their potential use as an alternative/complementary therapy against VVC. Additionally, this review discusses advantages and challenges associated with the application of -biotics in VVC to provide guidance for their later use. We also review new developments in VVC therapy, i.e., vaginal microbiota transplantation (VMT) as an emerging live biotherapeutic therapy against VVC and discuss existing shortcomings associated with this nascent field, expecting to stimulate further investigations for introduction of new therapies against VVC.

Hormonal steroids induce multidrug resistance and stress response genes in Neisseria gonorrhoeae by binding to MtrR

Transcriptional regulator MtrR inhibits the expression of the multidrug efflux pump operon mtrCDE in the pathogenic bacterium Neisseria gonorrhoeae. Here, we show that MtrR binds the hormonal steroids progesterone, β-estradiol, and testosterone, which are present at urogenital infection sites, as well as ethinyl estrogen, a component of some hormonal contraceptives. Steroid binding leads to the decreased affinity of MtrR for cognate DNA, increased mtrCDE expression, and enhanced antimicrobial resistance. Furthermore, we solve crystal structures of MtrR bound to each steroid, thus revealing their binding mechanisms and the conformational changes that induce MtrR.

Evaluation of the Microbiome Identification of Forensically Relevant Biological Fluids: A Pilot Study

In forensic sciences, body fluids, or biological traces, are a major source of information, and their identification can play a decisive role in criminal investigations. Currently, the nature of biological fluids is assessed using immunological, physico-chemical, mRNA and epigenetic methods, but these have limits in terms of sensitivity and specificity. The emergence of next-generation sequencing technologies offers new opportunities to identify the nature of body fluids by determining bacterial communities. The aim of this pilot study was to assess whether analysis of the bacterial communities in isolated and mixed biological fluids could reflect the situation observed in real forensics labs. Several samples commonly encountered in forensic sciences were tested from healthy volunteers: saliva, vaginal fluid, blood, semen and skin swabs. These samples were analyzed alone or in combination in a ratio of 1:1. Sequencing was performed on the Ion Gene StudioTM S5 automated sequencer. Fluids tested alone revealed a typical bacterial signature with specific bacterial orders, enabling formal identification of the fluid of interest, despite inter-individual variations. However, in biological fluid mixtures, the predominance of some bacterial microbiomes inhibited interpretation. Oral and vaginal microbiomes were clearly preponderant, and the relative abundance of their bacterial communities and/or the presence of common species between samples made it impossible to detect bacterial orders or genera from other fluids, although they were distinguishable from one another. However, using the beta diversity, salivary fluids were identified and could be distinguished from fluids in combination. While this method of fluid identification is promising, further analyses are required to consolidate the protocol and ensure reliability.

An Insight into Functional Metagenomics: A High-Throughput Approach to Decipher Food-Microbiota-Host Interactions in the Human Gut

Our understanding of the symbiotic relationship between the microbiota and its host has constantly evolved since our understanding that the "self" was not only defined by our genetic patrimony but also by the genomes of bugs living in us. The first culture-based methods highlighted the important functions of the microbiota. However, these methods had strong limitations and did not allow for a full understanding of the complex relationships that occur at the interface between the microbiota and the host. The recent development of metagenomic approaches has been a groundbreaking step towards this understanding. Its use has provided new insights and perspectives. In the present chapter, we will describe the advances of functional metagenomics to decipher food-microbiota and host-microbiota interactions. This powerful high-throughput approach allows for the assessment of the microbiota as a whole (including non-cultured bacteria) and enabled the discovery of new signaling pathways and functions involved in the crosstalk between food, the gut microbiota and its host. We will present the pipeline and highlight the most important studies that helped to develop the field. To conclude, we will emphasize the most recent developments and hot topics in functional metagenomics.

The effect of sex steroid hormones on the ecology of in vitro oral biofilms

Sex steroid hormones (SSH) such as oestrogen, progesterone and testosterone are cholesterol derived molecules that regulate various physiological processes. They are present in both blood and saliva, where they come in contact with oral tissues and oral microorganisms. Several studies have confirmed the effect of these hormones on different periodontal-disease-associated bacteria, using single-species models. Bacteria can metabolize SSH, use them as alternative for vitamin K and also use them to induce the expression of virulence factors. However, it is still unclear what the effects of SSH are on the oral microbiome. In this study, we investigated the effects of four SSH on commensal in vitro oral biofilms. Saliva-derived oral biofilms were grown in Mc Bain medium without serum or menadione using the Amsterdam Active-Attachment model. After initial attachment in absence of SSH, the biofilms were grown in medium containing either oestradiol, oestriol, progesterone or testosterone at a 100-fold physiological concentration. Menadione or ethanol were included as positive control and negative control, respectively. After 12 days with daily medium refreshments, biofilm formation, biofilm red fluorescence and microbial composition were determined. The supernatants were tested for proteolytic activity using the Fluorescence Resonance Energy Transfer Analysis (FRET). No significant differences were found in biofilm formation, red fluorescence or microbial composition in any of the tested groups. Samples grown in presence of progesterone and oestradiol showed proteolytic activity comparable to biofilms supplemented with menadione. In contrast, testosterone and oestriol showed a decreased proteolytic activity compared to biofilms grown in presence of menadione. None of the tested SSH had large effects on the ecology of in vitro oral biofilms, therefore a direct translation of our results into in vivo effects is not possible. Future experiments should include other host factors such as oral tissues, immune cells and combinations of SSH as present in saliva, in order to have a more accurate picture of the phenomena taking place in both males and females.

The relationship between vaginal microenvironment and pelvic dysfunctional diseases in Chinese women: a systematic review and meta-analysis

OBJECTIVE

The aim of this review is to synthesize existing evidence on the combined effects of the vaginal microenvironment on pelvic dysfunctional diseases.

METHODS

This systematic review was conducted in accordance with the PRISMA guidelines. The PubMed, Embase, Cochrane Library, Web of Science, Wanfang, and China Knowledge Network (CNKI) databases were systematically searched up to January 2023 using the following MeSH terms: "pelvic organ prolapse", "stress urinary incontinence" and "vaginal microenvironment", "microenvironment", "vaginal cleanliness", "vaginitis", "lactobacillus" and other related keywords. Study methods were limited to case-control studies or cross-sectional studies. Quality assessment was performed using the Newcastle-Ottawa scale, and meta-analysis of the included literature was performed using Review Manager 5.3.

RESULTS

A total of eight articles were included in this systematic review (SR) and meta-analysis (MA), which involved a total of 7298 study participants. The pooled results of this meta-analysis showed that the vaginal microenvironment (number of vaginal lactobacilli, leukorrhea cleanliness, and presence of vaginitis) were all statistically significantly associated with pelvic dysfunctional diseases in Chinese women.

CONCLUSION

This review indicates that the vaginal microenvironment has an impact on the development of PFD in Chinese women.

TRIAL REGISTRATION

The protocol of this systematic review (SR) and meta-analysis (MA) has been registered in PROSPERO databases with the Registration number of CRD42023407251.

New insights into the role of Cutibacterium acnes-derived extracellular vesicles in inflammatory skin disorders

Cutibacterium acnes (C. acnes) is one of the most prevalent bacteria that forms the human skin microbiota. Specific phylotypes of C. acnes have been associated with the development of acne vulgaris, while other phylotypes have been linked to healthy skin. In this scenario, bacterial extracellular vesicles (EVs) play a role in the interkingdom communication role with the human host. The purpose of this study was to examine the impact of EVs generated by various phylotypes of C. acnes on inflammation and sebum production using different in vitro skin cell types. The main findings of this study reveal that the proteomic profile of the cargo embodied in the EVs reflects distinct characteristics of the different C. acnes phylotypes in terms of life cycle, survival, and virulence. The in vitro skin cell types showed an extended pro-inflammatory modulation of SLST A1 EVs consistently triggering the activation of the inflammation-related factors IL-8, IL-6, TNFα and GM-CSF, in comparison to SLST H1 and SLST H2. Additionally, an acne-prone skin model utilizing PCi-SEB and arachidonic acid as a sebum inducer, was employed to investigate the impact of C. acnes EVs on sebum regulation. Our findings indicated that all three types of EVs significantly inhibited sebum production after a 24-h treatment period, with SLST H1 EVs exhibiting the most pronounced inhibitory effect when compared to the positive control. The results of this study highlight the protective nature of C. acnes SLST H1 EVs and their potential use as a natural treatment option for alleviating symptoms associated with inflammation and oily skin.

A Narrative Review Discussing the Obstetric Repercussions Due to Alterations of Personalized Bacterial Sites Developed within the Vagina, Cervix, and Endometrium

BACKGROUND

The reproductive tract microbiota that evolved as an integrative component has been studied intensively in the last decade. As a result, novel research, clinical opportunities, and perspectives have been derived following the close investigation of this microecological environment. This has paved the way for an update to and improvement of the management strategies and therapeutic approaches. However, obscurities, contradictions, and controversies arise regarding the ascension route from the vagina to the endometrium via the cervix, with finality in adverse obstetric outcomes.

METHODS

Starting from these considerations, we aimed to gather all existing data and information from four major academic databases (PubMed, ISI Web of Knowledge, Scopus, and ScienceDirect) published in the last 13 years (2010-2023) using a controlled vocabulary and dedicated terminology to enhance the coverage, identification, and sorting of potentially eligible studies.

RESULTS

Despite the high number of returned entries (n = 804), only a slight percentage (2.73%) of all manuscripts were deemed eligible following two rounds of evaluation. Cumulatively, a low level of Lactobacillus spp. and of other core microbiota members is mandatory, with a possible eubiosis-to-dysbiosis transition leading to an impairment of metabolic and endocrine network homeostasis. This transposes into a change in the pro-inflammatory landscape and activation of signaling pathways due to activity exerted by the bacterial lipopolysaccharides (LPSs)/endotoxins that further reflect a high risk of miscarriage in various stages. While the presence of some pathogenic entities may be suggestive of an adverse obstetric predisposition, there are still pros and cons of the role of specific strains, as only the vagina and cervix have been targeted as opposed to the endometrium, which recently started to be viewed as the key player in the vagina-cervix-endometrium route. Consequently, based on an individual's profile, diet, and regime, antibiotics and probiotics might be practical or not.

CONCLUSIONS

Resident bacteria have a dual facet and are beneficial for women's health, but, at the same time, relaying on the abundance, richness, and evenness that are definitory indexes standing as intermediaries of a miscarriage.

Occupational exposure in swine farm defines human skin and nasal microbiota

Anthropogenic environments take an active part in shaping the human microbiome. Herein, we studied skin and nasal microbiota dynamics in response to the exposure in confined and controlled swine farms to decipher the impact of occupational exposure on microbiome formation. The microbiota of volunteers was longitudinally profiled in a 9-months survey, in which the volunteers underwent occupational exposure during 3-month internships in swine farms. By high-throughput sequencing, we showed that occupational exposure compositionally and functionally reshaped the volunteers’ skin and nasal microbiota. The exposure in farm A reduced the microbial diversity of skin and nasal microbiota, whereas the microbiota of skin and nose increased after exposure in farm B. The exposure in different farms resulted in compositionally different microbial patterns, as the abundance of Actinobacteria sharply increased at expense of Firmicutes after exposure in farm A, yet Proteobacteria became the most predominant in the volunteers in farm B. The remodeled microbiota composition due to exposure in farm A appeared to stall and persist, whereas the microbiota of volunteers in farm B showed better resilience to revert to the pre-exposure state within 9 months after the exposure. Several metabolic pathways, for example, the styrene, aminobenzoate, and N-glycan biosynthesis, were significantly altered through our PICRUSt analysis, and notably, the function of beta-lactam resistance was predicted to enrich after exposure in farm A yet decrease in farm B. We proposed that the differently modified microbiota patterns might be coordinated by microbial and non-microbial factors in different swine farms, which were always environment-specific. This study highlights the active role of occupational exposure in defining the skin and nasal microbiota and sheds light on the dynamics of microbial patterns in response to environmental conversion.

Effects of emergency/nonemergency cervical cerclage on the vaginal microbiome of pregnant women with cervical incompetence

Background

Evaluation of the therapeutic effects of cerclage on preterm birth (PTB) caused by cervical incompetence remains challenging. The vaginal microbiome is associated with preterm births. Thus, this study aimed to analyse the vaginal microbiota of patients with cervical incompetence, explore the relationship between the composition of the vaginal microbiota before cervical cerclage and at term delivery, and assess the effect of cervical cerclage on the vaginal microbiota.

Methods

Patients (n = 30) underwent cerclage performed by the same surgical team. Vaginal swabs were obtained pre-surgery and seven days post-surgery. A gestational age-matched cohort of healthy pregnant women (n = 20) (no particular abnormality during pregnancy, delivery at term) was used as the control group and sampled during a comparable pregnancy. All collected vaginal swabs were analysed by 16S rRNA gene sequencing.

Results

When comparing the healthy control and cervical cerclage groups, the enriched microorganism in the healthy controls was G. Scardovia, and the enriched microorganism of the cerclage was G. Streptococcus. α diversity was significantly increased in patients who received cerclage with preterm delivery compared with those with full-term delivery, and the enriched microorganism was F. Enterococcus. A comparison before and after nonemergency cerclage suggested that the enriched microorganisms were G. Lactobacillus and F. Lactobacillaceae before surgery. After nonemergency cerclage, the enriched microorganisms were F. Enterobacteriaceae and C. Gammaproteobacteria. Vaginal microbiota diversity significantly increased, and the proportion of women with Lactobacillus spp.-depleted microbiomes increased after emergency cerclage. Significant differences in β diversity were found between the groups. Before the emergency cerclage, the enriched microorganisms were G. Lactobacillus, O. Alteromonadales, and P. Firmicutes. After emergency cerclage, the enriched microorganisms were P. Actinobacteria, C. Actinobacteria, P. Proteobacteria, F. Bifidobacteriaceae, O. Bifidobacteriales, G. Gardnerella, and G. Veillonella.

Conclusion

Cerclage (particularly emergency cerclage) may alter the vaginal microbiota by increasing microbiota diversity, decreasing vaginal Lactobacillus abundance, and increasing the abundance of pathogenic bacteria that are not conducive to pregnancy maintenance, thereby affecting surgical efficacy. Therefore, the role of the vaginal microbiome should be considered when developing treatment strategies for pregnant women with cervical incompetence.

Clinical trial registration

https://www.chictr.org.cn, identifier ChiCTR2100046305.

The Molecular Gut-Brain Axis in Early Brain Development

Millions of nerves, immune factors, and hormones in the circulatory system connect the gut and the brain. In bidirectional communication, the gut microbiota play a crucial role in the gut-brain axis (GBA), wherein microbial metabolites of the gut microbiota regulate intestinal homeostasis, thereby influencing brain activity. Dynamic changes are observed in gut microbiota as well as during brain development. Altering the gut microbiota could serve as a therapeutic target for treating abnormalities associated with brain development. Neurophysiological development and immune regulatory disorders are affected by changes that occur in gut microbiota composition and function. The molecular aspects relevant to the GBA could help develop targeted therapies for neurodevelopmental diseases. Herein, we review the findings of recent studies on the role of the GBA in its underlying molecular mechanisms in the early stages of brain development. Furthermore, we discuss the bidirectional regulation of gut microbiota from mother to infant and the potential signaling pathways and roles of posttranscriptional modifications in brain functions. Our review summarizes the role of molecular GBA in early brain development and related disorders, providing cues for novel therapeutic targets.

Vitamin D deficiency increases the risk of bacterial vaginosis during pregnancy: Evidence from a meta-analysis based on observational studies

Background

Bacterial vaginosis (BV) is the most common microbiological syndrome in women of childbearing age, causing numerous adverse health issues in pregnant women. Several observational studies have discussed the association between vitamin D deficiency and the risk of BV during pregnancy, but the results were inconclusive. Therefore, this meta-analysis aimed to explore the association between vitamin D deficiency and BV risk in pregnant women.

Materials and methods

We searched four databases, including PubMed, Embase, Cochrane Library, and Web of Science, from their inception to July 2022. Pooled odds ratios (OR) with corresponding 95% confidence intervals (CI) were estimated using random effects models. Additionally, we conducted subgroup analyses to identify the potential sources of between-study heterogeneity. Sensitivity analysis was performed using the method of exclusion, one study at a time. Publication bias was examined using Egger’s test and funnel plot.

Results

A total of 14 studies from 13 articles including 4,793 participants were eligible for this meta-analysis. The outcome showed that vitamin D deficiency may increase the risk of BV during pregnancy by 54% (OR, 1.54; 95% CI, 1.25–1.91; P < 0.001). In subgroup analyses, positive associations were also found in studies that were: conducted in black women (OR, 1.56; 95% CI, 0.98–2.48; P = 0.060), focused on the first trimester of pregnancy (OR, 2.22; 95% CI, 1.35–3.64; P = 0.002), of high quality (OR, 3.05; 95% CI, 1.26–7.41; P = 0.014), and adjusted for confounders (OR, 1.28; 95% CI, 1.06–1.55; P = 0.012). Sensitivity analysis reported that BV risk during pregnancy resulting from vitamin D deficiency increased by 157% (OR, 2.57; 95% CI, 1.50–4.42; P = 0.001) when removing the first two high-weight studies. Publication bias was observed using Egger’s test (t = 3.43, P = 0.005) and a visual funnel plot.

Conclusion

This meta-analysis showed that vitamin D deficiency is positively associated with the risk of BV during pregnancy. Further high-quality prospective cohort studies are needed to determine whether vitamin D intake reduces the prevalence of BV in pregnant women.