Vaginal Probiotics for Reproductive Health and Related Dysbiosis: Systematic Review and Meta-Analysis

Exploring the interaction and impact of probiotic and commensal bacteria on vitamins, minerals and short chain fatty acids metabolism

There is increasing evidence that probiotic and commensal bacteria play a role in substrate metabolism, energy harvesting and intestinal homeostasis, and may exert immunomodulatory activities on human health. In addition, recent research suggests that these microorganisms interact with vitamins and minerals, promoting intestinal and metabolic well-being while producing vital microbial metabolites such as short-chain fatty acids (SCFAs). In this regard, there is a flourishing field exploring the intricate dynamics between vitamins, minerals, SCFAs, and commensal/probiotic interactions. In this review, we summarize some of the major hypotheses beyond the mechanisms by which commensals/probiotics impact gut health and their additional effects on the absorption and metabolism of vitamins, minerals, and SCFAs. Our analysis includes comprehensive review of existing evidence from preclinical and clinical studies, with particular focus on the potential interaction between commensals/probiotics and micronutrients. Finally, we highlight knowledge gaps and outline directions for future research in this evolving field.

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.

Lacticaseibacillus rhamnosus TOM 22.8 (DSM 33500) is an effective strategy for managing vaginal dysbiosis, rising the lactobacilli population

AIM

The present study is a single-centre, randomized, controlled clinical trial aimed to evaluate the effectiveness of the probiotic Lacticaseibacillus rhamnosus TOM 22.8 (DSM 33500) strain, orally administrated, to treat vaginal dysbiosis.

METHODS AND RESULTS

Overall, 80 women, with signs and symptoms of vaginal dysbiosis, were enrolled and allocated to the treatment group (A, n=60), who took 1 capsule of the probiotic strain for 10 consecutive days, or the non-treatment group (B, n=20), who did not receive any treatment. Clinical (vaginal signs and symptoms; pH of the vaginal fluid; Amsel criteria; Nugent score; Lactobacillary grade) and microbiological examinations were performed at baseline (T0), 10 days (T1), and 30 (T2) days after the oral administration of the probiotic TOM 22.8 strain. The latter resulted in a restoration of the physiological pH, accompanied by remission or attenuation of clinical signs and symptoms as well as the improvement of the quality of life (QoL). Microbiological data revealed a significant reduction of potentially pathogenic bacteria.

CONCLUSION

The administration of the L. rhamnosus TOM 22.8 probiotic strain could be proposed as an effective strategy for the treatment of vaginal dysbiosis.

Interpretation of vaginal metagenomic characteristics in different types of vaginitis

Although vaginitis is closely related to vaginal microecology in females, the precise composition and functional potential of different types of vaginitis remain unclear. Here, metagenomic sequencing was applied to analyze the vaginal flora in patients with various forms of vaginitis, including cases with a clue cell proportion ranging from 1% to 20% (Clue1_20), bacterial vaginitis (BV), vulvovaginal candidiasis (VVC), and BV combined with VVC (VVC_BV). Our results identified Prevotella as an important biomarker between BV and Clue1_20. Moreover, a gradual decrease was observed in the relative abundance of shikimic acid metabolism associated with bacteria producing indole as well as a decline in the abundance of Gardnerella vaginalis in patients with BV, Clue1_20, and healthy women. Interestingly, the vaginal flora of patients in the VVC_BV group exhibited structural similarities to that of the VVC group, and its potentially functional characteristics resembled those of the BV and VVC groups. Finally, Lactobacillus crispatus was found in high abundance in healthy samples, greatly contributing to the stability of the vaginal environment. For the further study of L. crispatus, we isolated five strains of L. crispatus from healthy samples and evaluated their capacity to inhibit G. vaginalis biofilms and produce lactic acid in vitro to select the potential probiotic candidate for improving vaginitis in future clinical studies. Overall, we successfully identified bacterial biomarkers of different vaginitis and characterized the dynamic shifts in vaginal flora between patients with BV and healthy females. This research advances our understanding and holds great promise in enhancing clinical approaches for the treatment of vaginitis.

IMPORTANCE

Vaginitis is one of the most common gynecological diseases, mostly caused by infections of pathogens such as Candida albicans and Gardnerella vaginalis. In recent years, it has been found that the stability of the vaginal flora plays an important role in vaginitis. Furthermore, the abundant Lactobacillus-producing rich lactic acid in the vagina provides a healthy acidic environment such as Lactobacillus crispatus. The metabolites of Lactobacillus can inhibit the colonization of pathogens. Here, we collected the vaginal samples of patients with bacterial vaginitis (BV), vulvovaginal candidiasis (VVC), and BV combined with VVC to discover the differences and relationships among the different kinds of vaginitis by metagenomic sequencing. Furthermore, because of the importance of L. crispatus in promoting vaginal health, we isolated multiple strains from vaginal samples of healthy females and chose the most promising strain with potential probiotic benefits to provide clinical implications for treatment strategies.

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.

Characterization of vaginal Lactobacillus species as a predictor of fertility among Iranian women with unexplained recurrent miscarriage and fertile women without miscarriage history using machine learning modeling

BACKGROUND

Lactobacillus spp. are the predominant bacteria of the vaginal tract, the alteration of which has been previously linked to miscarriage. Here, we investigated differences between selected vaginal Lactobacillus species of women with a history of recurrent miscarriages and fertile women without a history of miscarriage in Iran.

METHODS AND RESULTS

Vaginal swabs were taken from 29 fertile and 24 infertile women and quantitative real-time PCR (qPCR) assay was used to determine a selection of vaginal Lactobacillus species in both groups. The logistic regression (LR) model, Naive Bayes (NB) model, support vector machine model (SVM), and neural network model (NN) were developed to predict disease outcome by selected variables. LR analysis was used to construct a nomogram indicating predictions of the risk of miscarriage. The most abundant species among the patients were L. rhamnosus, L. ruminis, and L. acidophilus, while L. gasseri, L. vaginalis, L. fermentum, and L. iners were more abundant in healthy subjects. The distribution of L. ruminis, L. iners, and L. rhamnosus was higher in patients, while L. acidophilus, L. gasseri, and L. fermentum were highly distributed among healthy subjects. Higher AUC in predicting the disease outcome was observed for L. gasseri, L. rhamnosus, L. fermentum, and L. plantarum.

CONCLUSION

Our findings provide experimental evidence of vaginal Lactobacillus imbalance in infertile women and a suitable predictor for miscarriage based on the AUC algorithms. Further studies with larger sample size and using high-throughput technologies are needed to boost our understanding of the role of lactobacilli in miscarriage.

The effects of pro-, pre-, and synbiotics supplementation on polycystic ovary syndrome: an umbrella review of meta-analyses of randomized controlled trials

Background

Synbiotics, refer to a combination of probiotics and prebiotics in a form of synergism that beneficially affect the host's health by alternating the composition and/or function of the gut microbiota. Numerous meta-analyses of randomized clinical trials have proven that pro, pre-, and synbiotics supplementation has health outcomes in women with polycystic ovary syndrome (PCOS). However, the strength and quality of this evidence in aggregate have not yet been synthesized in great detail.

Methods

PubMed, Scopus, Web of Sciences, and Google Scholar were searched up to March 2023. We pooled the mean difference and its 95% confidence interval (CI) by applying a random-effects model.

Results

Overall, nine meta-analyses including a total of 12 trials were identified. The results of the present study indicated that probiotic supplementation significantly reduced the homeostatic model assessment for insulin resistance (HOMA-IR; WMD: -0.29, 95% CI: -0.57 to -0.02, p = 0.03, n = 4; moderate certainty) and fasting glucose concentration (FGC; WMD: -7.5 mg/dL, 95% CI: -13.60 to -0.51, p = 0.03; n = 4; low certainty). Moreover, synbiotic supplementation had beneficial effects on glycemic control, lipid profile, and hormonal parameters, but the certainty of the evidence was rated as low to very low. However, supplementation with pro-/synbiotics did not affect inflammation and oxidative stress in women with PCOS. Furthermore, waist/hip circumference, fasting glucose concentration, lipid profile, dehydroepiandrosterone sulfate, high-sensitivity C-reactive protein, and hirsutism score were significantly reduced after prebiotics supplementation with low certainty of evidence.

Conclusion

Although pro-, pre-, and synbiotics supplementation had beneficial effects on some PCOS-related outcomes, the certainty of the evidence was rated as low to very low. Therefore, further well-designed RCTs might help to confirm our findings in women with PCOS.

Antibiotics therapy combined with probiotics administered intravaginally for the treatment of bacterial vaginosis: A systematic review and meta-analysis

The objective was to examine the pooled effects of antibiotic-probiotic combinations by examining the cure rate and recurrence rate for bacterial vaginosis (BV). A systematic literature search was conducted from electronic databases. All parallel randomized controlled trials (RCTs) that focused on the effects of antibiotics combined with intravaginal probiotics were included. Cure rate and recurrence rate were the primary and secondary outcomes to be analyzed. Meta-analysis was conducted following the Cochrane handbook for Systematic Reviews of Interventions. As a result, of 923 studies identified, 11 articles involving 1,493 BV patients met the inclusion criteria and nine were available for meta-analysis. A meta-analysis of two studies evaluated the recurrence rate 12-16 weeks after treatment. Results showed a statistically significant difference favoring the antibiotics plus probiotics group vs the antibiotics plus placebo group (relative risk 0.62, 95% confidence interval [CI]: 0.45-0.85). The narrative review in one study indicated that the cure rate was higher in the antibiotics plus probiotics group, giving a significant HR ratio of 0.73 (95% CI 0.54-0.98) (p = 0.042). In conclusion, vaginal application of Lactobacillus in combination with antibiotics for the treatment of BV could be a promising method for both reducing the recurrence rate and relieving symptoms of BV.

Role of the vaginal microbiome in miscarriage: exploring the relationship

Miscarriage is a devastating pregnancy loss that affects many women worldwide. It is characterized as a spontaneous miscarriage that occurs before 20 weeks of gestation which affects more than 25% of pregnancies. While the causes of miscarriage are complex and multifactorial, recent research has suggested a potential role of the vaginal microbiota. The vaginal microbiome is a dynamic ecosystem of microbes that are essential for preserving vaginal health and avoiding infections. Vaginal dysbiosis has been accompanied with numerous adverse pregnancy complications, such as preterm birth. However, the effect of the vaginal microbiome in miscarriage is not fully understood. This review aims to investigate the link between vaginal microbiota and miscarriage. Also, we investigate the various mechanisms through which the vaginal microbiota may affect miscarriage. Additionally, we examine the implications of these research findings, specifically the possibility of vaginal microbiome screening and targeted interventions to prevent miscarriage.

Pregnancy outcomes after vaginal probiotic supplementation before frozen embryo transfer: a randomized controlled study

In women receiving assisted reproductive treatment, intrauterine lactobacilli dominance has been associated with higher rates of pregnancy achievement. This randomized controlled trial conducted in the fertility clinic of the university hospital from 7 August 2019 to May 2021, aimed to compare the clinical outcome of embryo transfer in frozen-thaw cycles with Lactobacillus supplementation prior to embryo transfer and the standard treatment. A total of 340 infertile women underwent randomization. The biochemical and clinical pregnancy rates were comparable between the groups (39.9 and 34.2% in the study group vs. 41.8 and 31.7% in the control group); however, the miscarriage rate was significantly decreased in the study group (9.5 vs. 19.1%, respectively, p = 0.02), [OR = 0.44, 95% CI (0.23, 0.86)]. Among 49 women diagnosed with bacterial vaginosis, the live birth rate in the study group was higher than the control group (42.31 vs. 26.09%, p = 0.23), [OR = 2.08, 95% CI (0.62, 6.99)]. In the blastocyst transfer group (n = 206), the live birth rate was significantly higher in the study group than in the control group (35.71 vs. 22.22%, p = 0.03) [OR = 1.9, 95% CI (1.05, 3.59)]. Therefore, intravaginal lactobacilli supplementation before embryo transfer in the frozen-thaw cycle did not improve the biochemical and clinical pregnancy rate in the general population but significantly reduced the miscarriage rate.Trial Registration: TCTR20190429001 (29/04/2019) @ www.thaiclinicaltrials.org .

Development and Characterization of Lactobacillus rhamnosus-Containing Bioprints for Application to Catheter-Associated Urinary Tract Infections

Catheter-associated urinary tract infections (CAUTI) are a significant healthcare burden affecting millions of patients annually. CAUTI are characterized by infection of the bladder and pathogen colonization of the catheter surface, making them especially difficult to treat. Various catheter modifications have been employed to reduce pathogen colonization, including infusion of antibiotics and antimicrobial compounds, altering the surface architecture of the catheter, or coating it with nonpathogenic bacteria. Lactobacilli probiotics offer promise for a "bacterial interference" approach because they not only compete for adhesion to the catheter surface but also produce and secrete antimicrobial compounds effective against uropathogens. Three-dimensional (3D) bioprinting has enabled fabrication of well-defined, cell-laden architectures with tailored release of active agents, thereby offering a novel means for sustained probiotic delivery. Silicone has shown to be a promising biomaterial for catheter applications due to mechanical strength, biocompatibility, and its ability to mitigate encrustation on the catheter. Additionally, silicone, as a bioink, provides an optimum matrix for bioprinting lactobacilli. This study formulates and characterizes novel 3D-bioprinted Lactobacillus rhamnosus (L. rhamnosus)-containing silicone scaffolds for future urinary tract catheterization applications. Weight-to-weight (w/w) ratio of silicone/L. rhamnosus was bioprinted and cured with relative catheter dimensions in diameter. Scaffolds were analyzed in vitro for mechanical integrity, recovery of L. rhamnosus, antimicrobial production, and antibacterial effect against uropathogenic Escherichia coli, the leading cause of CAUTI. The results show that L. rhamnosus-containing scaffolds are capable of sustained recovery of live bacteria over 14 days, with sustained production of lactic acid and hydrogen peroxide. Through the use of 3D bioprinting, this study presents a potential alternative strategy to incorporate probiotics into urinary catheters, with the ultimate goal of preventing and treating CAUTI.

Male infertility and the human microbiome

The historical belief in urology was that the genitourinary system should be sterile in a normal, healthy, asymptomatic adult. This idea was perpetuated for decades until research revealed a diverse microbiota existing in human anatomical niches that contributed to both human health and disease processes. In recent years, the search for an etiology and modifiable risk factors in infertility has turned to the human microbiome as well. Changes in the human gut microbiome have been associated with changes in systemic sex hormones and spermatogenesis. Certain microbial species are associated with higher levels of oxidative stress, which may contribute to an environment higher in oxidative reactive potential. Studies have demonstrated a link between increased oxidative reactive potential and abnormal semen parameters in infertile men. It has also been hypothesized that antioxidant probiotics may be able to correct an imbalance in the oxidative environment and improve male fertility, with promising results in small studies. Further, the sexual partner's microbiome may play a role as well; studies have demonstrated an overlap in the genitourinary microbiomes in sexually active couples that become more similar after intercourse. While the potential applications of the microbiome to male fertility is exciting, there is a need for larger studies with uniform microbial sequencing procedures to further expand this topic.

The interplay between human papillomavirus and vaginal microbiota in cervical cancer development

Over the past few decades, we have grown accustomed to the idea that human papillomavirus can cause tumors. The genetic and environmental factors that make the difference between elimination of viral infection and the development of cancer are therefore an area of active investigation at present. Microbiota has emerged as an important factor that may affect this balance by increasing or decreasing the ability of viral infection to promote. The female reproductive system has its specific microbiota that helps to maintain health and prevent infection with pathogens. In contrast to other mucosal sites, the vaginal microbiota typically has low diversity and contains few Lactobacillus spp. which by using high-throughput 16s rRNA gene sequencing, classified into five different community state types. According to emerging information, increased diversity of vaginal microbiota and reduced abundance of Lactobacillus spp. contribute to HPV acquisition, persistence, and development of cervical cancer. In this review, the role of normal female reproductive tract microbiota in health, mechanisms which dysbiosis can cause diseases through interaction with microbes and several therapeutic approaches were addressed.

Use of probiotic lactobacilli in the treatment of vaginal infections: In vitro and in vivo investigations

The vaginal microbiome is a distinct component of the human microbiome that is colonized by a wide variety of microorganisms. Lactobacilli are the most frequently identified microorganisms in the healthy human vagina. These Gram-positive bacilli can acidify the vaginal microenvironment, inhibit the proliferation of other pathogenic microorganisms, and promote the maintenance of a eubiotic vaginal microbiome. However, a vaginal flora with a reduced proportion or abundance of lactobacilli is associated with various vaginal infections that have been linked to serious health consequences such as infertility, preterm birth, pelvic inflammatory disease, premature rupture of membranes, and miscarriage. Due to their “Generally Recognized as Safe” classification and critical role in vaginal health, probiotic lactobacilli have been widely used as an alternative or adjunct to traditional antibiotic therapy for the treatment of vaginal infections and restoration of the vaginal microbiome. This review focuses on the significant role of probiotic lactobacilli in the vaginal microenvironment and discusses the use of probiotic lactobacilli in the treatment of female vaginal infections in vitro and in vivo.

In Vitro Assessment of Lactobacillus crispatus UBLCp01, Lactobacillus gasseri UBLG36, and Lactobacillus johnsonii UBLJ01 as a Potential Vaginal Probiotic Candidate

In this study, Lactobacillus crispatus UBLCp01, Lactobacillus gasseri UBLG36, and Lactobacillus johnsonii UBLJ01 isolated from the vagina of healthy reproductive age Indian women were screened for beneficial probiotic properties. These strains showed the ability to survive acidic and simulated vaginal fluid conditions and could adhere to mucin. Lact. gasseri UBLG36, and Lact. johnsonii UBLJ01 produced D- and L-lactic acid, whereas Lact. crispatus UBLCp01 produced hydrogen peroxide and D- and L-lactic acid. All strains inhibited the growth of pathogens (Escherichia coli, Gardnerella vaginalis, Proteus mirabilis, and Candida albicans) and were capable of co-aggregating with them with varying degrees. Strains secreted exopolysaccharides and formed biofilms under in vitro conditions. Safety assessment showed that these strains had a usual antibiotic susceptibility profile, did not produce hemolysins, gelatinases, and mucin degrading enzymes. Based on strain characteristics and beneficial properties, we believe that these strains are promising candidates for human trials to confirm their ability to prevent/treat vaginal dysbiosis and maintain a healthy vaginal eco-system.

Impact of Lactobacillus crispatus-containing oral and vaginal probiotics on vaginal health: a randomised double-blind placebo controlled clinical trial

Health of reproductive tract is tightly associated with balance of microbial communities in this area. Bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC) represent common disturbances of vaginal communities. Vaginal discharge due to BV or VVC is a very frequent reason for visiting gynaecologist. We aimed to evaluate the impact of the novel evidence-based probiotics on BV and VVC patients. The study group included 89 BV and 93 VVC patients (aged 18-50 years) who were recruited into randomised double-blind placebo-controlled two-arm parallel trial. The patients of each diagnosis group received oral or vaginal probiotic capsules, or placebo capsules during 3 months. A probiotic capsule contained two (DSM32717 and DSM32720, in case of BV) or three (DSM32720, DSM32718 and DSM32716, in case of VVC) Lactobacillus crispatus strains. Vaginal, intestinal and general health was monitored weekly by questionnaire. Blood analyses were done in the beginning and at the end of trial. Vaginal samples were collected monthly, microscopic and molecular analyses were performed. The study revealed that both oral and vaginal capsules reduced the signs and symptoms in BV patients. Remarkable improvement was noted in Nugent score, amount and smell of discharge, but also in itching/irritation. Consumption of vaginal probiotics significantly increased the lactobacilli counts in their vagina while mean proportion of some BV-related bacteria decreased. In VVC patients, both oral and vaginal capsules lowered the combined score of two most important symptoms, amount of discharge and itching/irritation. In conclusion, the novel formulations of evidence-based well-focused probiotic L. crispatus strains are effective against BV and VVC being suitable for both vaginal and oral administration. Clinical trial registration: ISRCTN34840624, BioMed Central.

The bacterial communities in vagina of different Candida species-associated vulvovaginal candidiasis

The incidence of vaginal infection caused by Candida species has considerably increased over the past two decades. Candida albicans is the main cause of vulvovaginal candidiasis (VVC); however, non-albicans Candida (NAC) species, such as Candida glabrata and Candida tropicalis, are now frequently identified in VVC patients. Although the vaginal microbiome (VMB) was well studied in Candida albicans-associated VVC patients, the fungal influence on bacterial communities of NAC species-associated VVC and potential microbial interplay contributing to VVC pathology remain elusive. We characterized VMB via Candida albicans and NAC species-associated VVC patients, as Candida albicans (CA, n = 16), Candida glabrata (CG, n = 16), Candida tropicalis (CT, n = 4), and recruiting healthy (CON, n = 20) women as references of dysbiosis and eubiosis. The bacterial diversity of the vagina in the CG group significantly declined. Further, all VVC patients have a higher abundance of Lactobacillus iners, especially for the CG group. Meanwhile, the predicted functions in all VVC are toned which may be associated with a disruption in the bacterial network. In conclusion, according to the taxonomic analysis, we found that the vaginal microbiome in C. glabrata-associated VVC women is different from that of other Candida species-associated VVC women, implying a different pathogenesis.

Periodontal disease in pregnancy and adverse pregnancy outcomes: Progress in related mechanisms and management strategies

Periodontal disease is an inflammatory and destructive disease of tissues supporting the tooth. A large number of studies have confirmed that periodontal pathogens and their metabolites can lead to adverse pregnancy outcomes in direct or indirect ways. Adverse pregnancy outcomes, such as preterm birth, low birth weight, and pre-eclampsia, have a serious impact on human reproductive health. In recent years, although the level of global medical technology has gradually improved, the incidence of adverse pregnancy outcomes has not declined and is still a global public health problem. The purpose of this review is to summarize the current data on periodontal disease in pregnancy and adverse pregnancy outcomes, including the association between periodontal disease and adverse pregnancy outcomes, the pathogenic mechanism related to this association, the efficacy of different nutrition supplements for both periodontal disease and adverse pregnancy outcomes and the effect of providing periodontal treatment on the occurrence of adverse pregnancy outcomes, to provide guidance for the prevention and treatment of adverse pregnancy outcomes in clinical practice.

Integration of Omics Approaches Enhances the Impact of Scientific Research in Environmental Applications

In the original article [...]

The Use of Probiotics for Management and Improvement of Reproductive Eubiosis and Function

Reproductive tract dysbiosis, due to the action of pathogens and/or unhealthy lifestyle, has been related to many reproductive diseases and disorders in mammalian species. Classically, such a problem has been confronted by the administration of antibiotics. Despite their effectiveness for controlling disease, treatments with antibiotics may negatively affect the fertility of males and females and, mainly, may induce antibiotic resistance. Accordingly, safer alternatives for maintaining reproductive system eubiosis, such as probiotics, are required. The present review summarizes the current knowledge on the biodiversity of the microbiota at the reproductive tract, possible changes in the case of dysbiosis, and their relationships with adequate reproductive health and functioning in both females and males. Afterwards, mechanisms of action and benefits of different probiotics are weighed since the biological activities of probiotics may provide a promising alternative to antibiotics for maintaining and restoring reproductive eubiosis and function. However, at present, it is still necessary for further research to focus on: (a) identifying mechanisms by which probiotics can affect reproductive processes; (b) the safety of probiotics to the host, specifically when consumed during sensitive reproductive windows such as pregnancy; and (c) the hazards instructions and regulatory rules required for marketing these biological-based therapies with sufficient safety. Thus, in this review, to draw a comprehensive overview with a relatively low number of clinical studies in this field, we showed the findings of studies performed either on human or animal models. This review strategy may help provide concrete facts on the eligible probiotic strains, probiotics colonization and transfer route, and prophylactic and/or therapeutic effects of different probiotic strains.

The Endometrial Microbiome and Its Impact on Human Conception

Changes in the female genital tract microbiome are consistently correlated to gynecological and obstetrical pathologies, and tract dysbiosis can impact reproductive outcomes during fertility treatment. Nonetheless, a consensus regarding the physiological microbiome core inside the uterine cavity has not been reached due to a myriad of study limitations, such as sample size and experimental design variations, and the influence of endometrial bacterial communities on human reproduction remains debated. Understanding the healthy endometrial microbiota and how changes in its composition affect fertility would potentially allow personalized treatment through microbiome management during assisted reproductive therapies, ultimately leading to improvement of clinical outcomes. Here, we review current knowledge regarding the uterine microbiota and how it relates to human conception.

Can probiotics enhance fertility outcome? Capacity of probiotics as a single intervention to improve the feminine genital tract microbiota in non-symptomatic reproductive-aged women

Modifications in vaginal and endometrial microbiome and microbiota have been associated with fewer implantation rates and poorest pregnancy outcomes. Therefore, its study has emerged as a new biomarker in reproductive medicine. Despite the numerous papers published on probiotic use for vaginal dysbiosis and their actual wide empiric use especially for infertile patients, there is still no clear answer to justify their recommendation. The impact of probiotics on the vaginal or endometrial microbiota has often been investigated under a symptomatic altered vaginal microbial ecosystem, such as bacterial vaginosis. However 50% of women with bacterial vaginosis are asymptomatic. Actual clinical practice guidelines clearly recommend the use of specific antimicrobial agents for the management of symptomatic vaginal infections. Assuming this should be the management as well for an infertile population, what should be the treatment for the 50% non-symptomatic women presenting unfavorable vaginal/endometrial microbiota? The aim of this review is to assess the capacity of probiotics as a single intervention to alter the feminine genital tract microbiota in non-symptomatic reproductive-aged women.

Factors contributing to persistent disparate outcomes of in vitro fertilization treatment

PURPOSE OF REVIEW

Disparate healthcare outcomes are ubiquitous and occur across all fields of medicine, specifically for racial and ethnic minorities. Within reproductive health, minority women face disparate access to care, particularly infertility services, poor outcomes of fertility treatment, alarmingly higher rates of maternal morbidity and mortality as well as higher rates of preterm birth, lower live birth rates when they conceive spontaneously or when they conceive with assisted reproductive technology. The objective of this review is to highlight factors contributing to the persistent racial/ethnic disparities in in vitro fertilization (IVF) outcomes.

RECENT FINDINGS

Recent studies document poorer outcomes after IVF treatment. Black women have been shown to have lower live birth rates following IVF treatment for more than 15 years.

SUMMARY

In an effort to better understand these negative outcomes, scientists and clinicians have investigated possible biological contributing factors including the vaginal microbiome, differences in oocyte quality, embryo viability, endometrial factors, and hormonal differences. Multiple social/cultural factors also play a role including access to care, particularly for people with low income, patient (mis)education, and medical racism/bias.

Vaginal Lactobacilli and Vaginal Dysbiosis-Associated Bacteria Differently Affect Cervical Epithelial and Immune Homeostasis and Anti-Viral Defenses

Persistent infection with High Risk-Human Papilloma Viruses (HR-HPVs) is a primary cause of cervical cancer worldwide. Vaginal-dysbiosis-associated bacteria were correlated with the persistence of HR-HPVs infection and with increased cancer risk. We obtained strains of the most represented bacterial species in vaginal microbiota and evaluated their effects on the survival of cervical epithelial cells and immune homeostasis. The contribution of each species to supporting the antiviral response was also studied. Epithelial cell viability was affected by culture supernatants of most vaginal-dysbiosis bacteria, whereas Lactobacillus gasseri or Lactobacillus jensenii resulted in the best stimulus to induce interferon-γ (IFN-γ) production by human mononuclear cells from peripheral blood (PBMCs). Although vaginal-dysbiosis-associated bacteria induced the IFN-γ production, they were also optimal stimuli to interleukin-17 (IL-17) production. A positive correlation between IL-17 and IFN-γ secretion was observed in cultures of PBMCs with all vaginal-dysbiosis-associated bacteria suggesting that the adaptive immune response induced by these strains is not dominated by T_H1 differentiation with reduced availability of IFN-γ, cytokine most effective in supporting virus clearance. Based on these results, we suggest that a vaginal microbiota dominated by lactobacilli, especially by L. gasseri or L. jensenii, may be able to assist immune cells with clearing HPV infection, bypasses the viral escape and restores immune homeostasis.

Next Generation Probiotics for Neutralizing Obesogenic Effects: Taxa Culturing Searching Strategies

The combination of diet, lifestyle, and the exposure to food obesogens categorized into "microbiota disrupting chemicals" (MDC) could determine obesogenic-related dysbiosis and modify the microbiota diversity that impacts on individual health-disease balances, inducing altered pathogenesis phenotypes. Specific, complementary, and combined treatments are needed to face these altered microbial patterns and the specific misbalances triggered. In this sense, searching for next-generation beneficial microbes or next-generation probiotics (NGP) by microbiota culturing, and focusing on their demonstrated, extensive scope and well-defined functions could contribute to counteracting and repairing the effects of obesogens. Therefore, this review presents a perspective through compiling information and key strategies for directed searching and culturing of NGP that could be administered for obesity and endocrine-related dysbiosis by (i) observing the differential abundance of specific microbiota taxa in obesity-related patients and analyzing their functional roles, (ii) developing microbiota-directed strategies for culturing these taxa groups, and (iii) applying the successful compiled criteria from recent NGP clinical studies. New isolated or cultivable microorganisms from healthy gut microbiota specifically related to obesogens' neutralization effects might be used as an NGP single strain or in consortia, both presenting functions and the ability to palliate metabolic-related disorders. Identification of holistic approaches for searching and using potential NGP, key aspects, the bias, gaps, and proposals of solutions are also considered in this review.