Application of Ligilactobacillus salivarius CECT5713 to Achieve Term Pregnancies in Women with Repetitive Abortion or Infertility of Unknown Origin by Microbiological and Immunological Modulation of the Vaginal Ecosystem

Expert Opinion: Place in Therapy of Probiotics in Infertility and Recurrent Implantation Failure

Infertility is a widespread medical condition, affecting a notable percentage of couples globally, with a rising prevalence in India. While assisted reproductive technologies (ART) provide hope, recurrent implantation failure (RIF) continues to challenge approximately one in 10 couples undergoing in-vitro fertilization (IVF). This expert opinion document intends to highlight the promise of probiotics, particularly from Lactobacillus, as a therapeutic approach for improving fertility and treating RIF. In India, on June 29-30, 2024, a physical expert meeting was organized involving 14 specialists from gynecology, obstetrics, and fertility fields. The role of probiotics in reproductive health was discussed in the meeting with an emphasis on infertility and RIF. All experts agree that microbial dysbiosis characterized by an imbalance among the dominant Lactobacillus species is associated with RIF leading to increased inflammation hence poor reproductive outcomes. Probiotics have emerged as possible therapies that restore microbial equilibrium while reducing inflammation and enhancing the intactness of the genital epithelium barrier. All experts have strongly supported the use of Lactobacillus-based oral probiotic supplementation particularly for preventing miscarriages and maintaining pregnancy. All the experts unanimously agreed that oral probiotic supplementation, particularly Lactobacillus-based, should be considered as a potential method to prevent miscarriages and aid in maintaining pregnancy. They recommend oral probiotic use prior to embryo transfer to enhance implantation and pregnancy rates. This expert opinion emphasizes the value of probiotics as a safe and non-invasive approach to treating infertility and RIF. By fostering a balanced microbiome, probiotics may increase the likelihood of successful pregnancies.

All Properties of Infertility Microbiome in a Review Article

BACKGROUND

The microbiome is crucial for many physiological processes, including immunity, metabolism, and reproduction.

AIMS

This review aims to contribute to a detailed understanding of the microbiome of the genital tract, which can lead to better management of dysbiosis and reproductive disorders.

METHODS

Data from the four international information databases Medline, Scopus, Embase, and Google Scholar. The search strategy was based on the combination of the following terms: "microbiota," "microbiome," "microfilm," "microflora," "fertility," or "infertility."

RESULT

The advent of next-generation sequencing-based technologies during the last decade has revealed the presence of microbial communities in nearly every part of the human body, including the reproductive system. Several studies have shown significant differences between the microbiota of the vagina and endometrium, as well as other parts of the upper genital tract.

DISCUSSION

The human microbiome plays a critical role in determining a person's health state, and the microbiome of the genital tract may impact fertility potential before and after assisted reproductive treatments (ARTs).

CONCLUSION

To completely understand the role of the microbiome, future research should focus not only on the description of microbiota but also on the interaction between bacteria, the production of biofilms, and the interaction of microorganisms with human cells.

Expert Opinion on the Use of Probiotics in Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) involves multiple consecutive miscarriages in early pregnancy, affecting a significant number of Indian women and placing substantial physical and emotional stress on expecting couples. This expert consensus aims to highlight probiotics as a promising option for enhancing fertility and supporting successful pregnancy outcomes, offering hope to individuals and couples affected by RPL. A group of fourteen experts with diverse expertise in gynecology, obstetrics, and fertility from across India gathered between June 29 and June 30, 2024. According to the experts, advanced maternal age emerges as an independent risk factor for miscarriage, with increased risks among older Indian women. The major contributors to RPL include thyroid disease and polycystic ovarian disease. Experts emphasize that the vaginal microbiome dysbiosis, characterized by the reduced dominance of Lactobacilli, is associated with adverse pregnancy outcome, such as preterm birth, early pregnancy loss, and increased events of RPL. Oral probiotic supplementation, particularly strains like L. acidophilus and L. rhamnosus, may improve embryo implantation, reduce miscarriage risk, and support pregnancy maintenance. A healthy lifestyle choice and minimal use of antibiotics are important in creating a positive reproductive outcome. The present expert opinion supports the potential benefits of probiotics, particularly Lactobacillus species, in managing RPL and improving reproductive outcomes. By promoting a balanced microbiota, reducing inflammation, and modulating immune responses, probiotics may play a critical role in enhancing reproductive success.

Understanding the Associations of Urogenital Microbiomes With Fertility and In Vitro Fertilization

Infertility, defined as the inability to establish a clinical pregnancy after a year of regular, unprotected sexual intercourse, impacts 8%-12% of couples worldwide. Many of these couples turn to in vitro fertilization (IVF) to build their families. The success rate of IVF procedures is variable, with estimates of up to 40% of embryo transfers being unsuccessful. Herein we review the existing literature on the role of the female and male urogenital microbiomes and genital inflammation on fertility and IVF outcomes. We discuss the microbiome across the female reproductive tract (FRT) and identify associations with female infertility, female genital tract inflammation, and success of IVF procedures. We also discuss the male urogenital microbiome and the associations between microbial taxa, genital inflammation, and male fertility parameters. Finally, we consider microbial transfer within couples and the impact this may have on fertility and the success of IVF procedures.

Ligilactobacillus salivarius PS11610 Enhances the Fertilization Success of IVF: A Preliminary Retrospective Analysis

BACKGROUND/OBJECTIVES

Infertility affects couples at reproductive age, with in vitro fertilization (IVF) being the most effective treatment. Success rates of IVF are influenced by several factors, including a healthy female reproductive system microbiome, which can improve implantation rates and pregnancy outcomes. This study evaluated the impact of Ligilactobacillus salivarius PS11610 on IVF outcomes. This strain showed antimicrobial activity against pathogens related to dysbiosis, commonly observed in women undergoing assisted reproductive treatment.

RESULTS

The administration of L. salivarius PS11610 at a dose of 1 × 109 CFU every 12 h for at least one month before IVF procedures, particularly in the frozen embryo transfer (FET) group, appears to enhance the success rate of IVF. IVF procedures without embryo transfer showed no significant differences between the groups. However, there were statistically significant differences in the quality of embryos, specifically in category 2, which were higher in the group without L. salivarius PS11610 supplementation (p = 0.042). Similar results were seen in the IVF with embryo transfer group, where the quality of embryos in categories 2 and 3 was higher in the group without L. salivarius PS11610 (p = 0.019 and p = 0.05, respectively). IVF with FET showed notable improvements, where intake of L. salivarius PS11610 was associated with a significant increase in live birth infants (26.4% with L. salivarius PS11610 vs. 17.9% without, p = 0.034) and higher biochemical pregnancy rates (42.6% vs. 34%, p = 0.071).

CONCLUSIONS

Despite some differences in embryo quality, the overall positive impact on pregnancy and birth outcomes highlights L. salivarius PS11610 as a promising supplement in assisted reproductive treatments.

The Safety of Probiotics Intended for Use in Pregnant and Lactating Women: From a Desirable to a Required Task

During pregnancy, women undergo changes that affect virtually every organ, apparatus, or system, including the host microbiota. Most pregnancies progress smoothly despite the common presence of minor side-effects arising from such adaptations. However, some women may experience more serious complications, including gestational diabetes mellitus, preeclampsia, or preterm delivery. Probiotics are one of the products most used to try to prevent or treat any of the minor or severe symptoms or complications that women may experience during pregnancy or lactation; however, most of them have never been tested in such populations and, therefore, their efficacy and safety claims are frequently unsubstantiated. Overall, probiotic trials involving pregnant or lactating women have shown that these products are usually well-tolerated and safe although adverse effects may also exist. Therefore, health professionals attending pregnant or lactating women should be aware of their use and monitor their efficacy and safety. In conclusion, probiotics recommendations for pregnant or lactating women should be based on scientific evidence, opting exclusively for those products that have been designed for the specific target or condition that a pregnant or lactating woman may be experiencing or at risk of, and which efficacy and safety has already been convincingly tested in such populations.

Intravaginal probiotics before embryo transfer do not improve pregnancy rates in recurrent implantation failure cases: An RCT

Background

Considering the considerable influence of the vaginal microbiome on endometrial receptivity and embryo implantation, we hypothesized that cases of recurrent implantation failure (RIF) might benefit from the intravaginal probiotic administration.

Objective

Evaluation of the effects of intravaginal probiotic administration before frozen embryo transfer (FET) on the rates of pregnancy and the status of vaginal lactobacillary flora in cases of RIF.

Materials and Methods

This was a randomized, parallel-group, clinical trial conducted at an infertility clinic in Tehran, Iran between January 2021 and September 2022. A total of 166 reproductive-aged women with a history of unexplained RIF were randomly assigned to either the probiotic group or the control group (n = 83/each group). The probiotic group received intravaginal probiotics (LactoVagⓇ) daily for 2 wk from the second day of the menstrual cycle along with the routine treatment of FET. The control group received only the routine treatment of FET. The primary outcome was the chemical pregnancy rate, and the secondary outcomes were the clinical pregnancy rate and the status of vaginal lactobacillary flora.

Results

A total of 163 participants were included in the final analysis. The probiotic group had a slightly higher chemical pregnancy rate than the control group (39.02% vs. 33.33%), but the difference was not statistically significant (risk ratio: 1.71, 95% CI: 0.77-1.76; p = 0.449). The clinical pregnancy rate was also non-significantly higher in the probiotic group than the control group (37.80% vs. 33.33%; RR: 1.14, 95% CI: 0.76-1.74; p = 0.623).

Conclusion

Intravaginal probiotic administration did not significantly improve the pregnancy rates in RIF cases undergoing FET. Further studies are needed to explore the optimal dose, duration, and timing of probiotic administration, as well as the mechanisms of action and the potential adverse effects of probiotics on the vaginal microbiome and the implantation process.

Do probiotic interventions improve female unexplained infertility? A critical commentary

Disruption of women's gut and cervicovaginal microbiota has been associated with multiple gynaecological diseases such as endometriosis, polycystic ovary syndrome, non-cyclic pelvic pain and infertility. Female infertility affects 12.6% of women worldwide; its aetiology is complex and multifactorial and can be underpinned by uterine pathologies, systemic diseases and age. In addition, a new perspective has emerged on the role of the gut and vaginal microbiomes in reproductive health. Research shows that the administration of precisely selected probiotics, often in combination with prior antibiotic treatment, may facilitate the restoration of symbiotic microbiota to increase successful conception and assisted reproductive technology outcomes. However, clarity on this issue from fuller research is currently hampered by a lack of consistency and harmonization in clinical studies: various lactobacilli and bifidobacteria species have been delivered through both the oral and vaginal routes, in different dosages, for different treatment durations. This commentary explores the intricate relationship between the microbiota in the cervicovaginal area and gut of women, exploring their potential contribution to infertility. It highlights ongoing research on the use of probiotic formulations in improving pregnancy outcomes, critically examining the divergent findings in these studies, which complicate a conclusive assessment of the efficacy of these interventions.

The role of probiotics in women's health: An update narrative review

Probiotics, live microorganisms that confer health benefits to the host when administered in adequate amounts, have gained considerable attention for their potential role in maintaining women's health. This overview summarizes key clinical findings on the beneficial effects of probiotics in various aspects of women's health. Probiotics, particularly Lactobacillus species, contribute to vaginal health by promoting a balanced vaginal microbiome to prevent infections and maintain an acidic environment. In gynecologic conditions, probiotics show potential in preventing and managing bacterial vaginosis, vulvovaginal candidiasis, and sexually transmitted infections. Probiotic supplementation has also been associated with improvements in metabolic parameters and menstrual irregularities in polycystic ovary syndrome patients. During pregnancy, probiotics may be helpful in reducing the risk of gestational diabetes, maternal group B streptococcal colonization, obstetric anemia, and postpartum mastitis. In recent years, the potential role of probiotics in the prevention and management of gynecologic cancer has gained attention. Further research is needed to better understand the specific mechanisms and determine the optimal Lactobacillus strains and dosages regimens for gynecologic cancer prevention and therapy. In conclusion, probiotics offer a non-invasive and cost-effective approach to support women's health and prevent obstetric and gynecologic complications.

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.

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 .

A randomized pilot trial assessing the reduction of gout episodes in hyperuricemic patients by oral administration of Ligilactobacillus salivarius CECT 30632, a strain with the ability to degrade purines

Introduction

Hyperuricemia and gout are receiving an increasing scientific and medical attention because of their relatively high prevalence and their association with relevant co-morbidities. Recently, it has been suggested that gout patients have an altered gut microbiota. The first objective of this study was to investigate the potential of some Ligilactobacillus salivarius strains to metabolize purine-related metabolites. The second objective was to evaluate the effect of administering a selected potential probiotic strain in individuals with a history of hyperuricemia.

Methods

Inosine, guanosine, hypoxanthine, guanine, xanthine, and uric acid were identified and quantified by high-performance liquid chromatography analysis. The uptake and biotransformation of these compounds by a selection of L. salivarius strains were assessed using bacterial whole cells and cell-free extracts, respectively. The efficacy of L. salivarius CECT 30632 to prevent gout was assessed in a pilot randomized controlled clinical trial involving 30 patients with hyperuricemia and a history of recurrent gout episodes. Half of the patients consumed L. salivarius CECT 30632 (9 log₁₀ CFU/day; probiotic group; n = 15) for 6 months while the remaining patients consumed allopurinol (100-300 mg/daily; control group; n = 15) for the same period. The clinical evolution and medical treatment received by the participants were followed, as well as the changes in several blood biochemical parameters.

Results

L. salivarius CECT 30632 was the most efficient strain for inosine (100%), guanosine (100%) and uric acid (50%) conversion and, therefore, it was selected for the pilot clinical trial. In comparison with the control group, administration of L. salivarius CECT 30632 resulted in a significant reduction in the number of gout episodes and in the use of gout-related drugs as well as an improvement in some blood parameters related to oxidative stress, liver damage or metabolic syndrome.

Conclusion

Regular administration of L. salivarius CECT 30632 reduced serum urate levels, the number of gout episodes and the pharmacological therapy required to control both hyperuricemia and gout episodes in individuals with a history of hyperuricemia and suffering from repeated episodes of gout.

Immunomodulation of the Vaginal Ecosystem by Ligilactobacillus salivarius CECT 30632 Improves Pregnancy Rates among Women with Infertility of Unknown Origin or Habitual Abortions

In this study, the probiotic potential of Ligilactobacillus salivarius CECT 30632 was assessed, including properties specifically related with gynecological targets. This strain displayed co-aggregative and antimicrobial activity against a wide spectrum of vaginal pathogens while being respectful with the growth of vaginal lactobacilli. The strain produced a high concentration of lactic acid and displayed α-amylase activity when assayed in vitro. It showed a noticeable survival rate after exposition to conditions similar to those present in the human digestive tract and was adhesive to both vaginal and intestinal cells. Subsequently, their capacity to increase pregnancy rates among women with habitual abortion or infertility of unknown origin was studied. Administration of L. salivarius CECT 30632 (~9 log₁₀ CFU) daily for a maximum of six months to these women was safe and led to a successful pregnancy rate of 67.5% (80% and 55% for women with repetitive abortion and infertile women, respectively). Significant differences in Nugent score, vaginal pH, and vaginal concentrations of lactobacilli, TGF-β, and VEFG were observed when the samples collected before the intervention were compared with those collected after the treatment among those women who got pregnant. Therefore, this strain can modulate the vaginal ecosystem and lead to better fertility outcomes.

Diet and Microbiome in Health and Aging

After several years of research, sufficient evidence has been found supporting that diet is one of the main factors able to modulate both composition and activity of the intestinal microbiota, thus positioning it as a cornerstone in the host-microbiota interface [...]

Healthy Vaginal Microbiota and Influence of Probiotics Across the Female Life Span

Vaginal microbiota plays a central role in women's health and reproduction. Vaginal microbiota is dynamic and shaped by hormonal shifts in each stage of a woman's life from pre-puberty to postmenopause. Current research has mainly focused on vaginal bacterial and fungal members of the community and emphasized their role in disease. However, the impact of balanced vaginal microbiota on health and its interaction with the host is yet poorly understood. High abundance of vaginal lactobacilli is most strongly associated with health, but the concept of health may vary as vaginal dysbiosis may be asymptomatic. Furthermore, there is a lot of variation between ethnic groups in terms of dominating vaginal bacteria. Probiotic lactobacilli could be a safe and natural means to balance and maintain healthy vaginal microbiota. Research evidence is accumulating on their role in supporting women's health throughout life. This review describes the current literature on vaginal microbiota, the major factors affecting its composition, and how the communities change in different life stages. Furthermore, we focused on reviewing available literature on probiotics and their impact on vaginal microbiota and health.

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.

Ligilactobacillus salivarius functionalities, applications, and manufacturing challenges

Ligilactobacillus salivarius is a lactic acid bacteria that has been gaining attention as a promising probiotic. Numerous strains exhibit functional properties with health benefits such as antimicrobial activity, immunological effects, and the ability to modulate the intestinal microbiota. However, just a small number of them are manufactured at an industrial scale and included in commercial products. The under exploitation of L. salivarius strains that remain in the freezer of companies is due to their incapacity to overcome the environmental stresses induced by production and stabilization processes.The present study summarizes the functionalities and applications of L. salivarius reported to date. It aims also at providing a critical evaluation of the literature available on the manufacturing steps of L. salivarius concentrates, the bacterial quality after each step of the process, and the putative degradation and preservation mechanisms. Here, we highlight the principal issues and future research challenges for improving the production and long-term preservation at the industrial scale of this microorganism, and probably of other probiotics.Key points• L. salivarius beneficial properties and commercialized products.• Production conditions and viability of L. salivarius after stabilization processes.• Prospects for identifying preservation mechanisms to improve L. salivarius stability.

Role of Transforming Growth Factor-β1 in Regulating Fetal-Maternal Immune Tolerance in Normal and Pathological Pregnancy

Transforming growth factor-β (TGF-β) is composed of three isoforms, TGF-β1, TGF-β2, and TGF-β3. TGF-β1 is a cytokine with multiple biological functions that has been studied extensively. It plays an important role in regulating the differentiation of immune cells and maintaining immune cell functions and immune homeostasis. Pregnancy is a carefully regulated process. Controlled invasion of trophoblasts, precise coordination of immune cells and cytokines, and crosstalk between trophoblasts and immune cells play vital roles in the establishment and maintenance of normal pregnancy. In this systematic review, we summarize the role of TGF-β1 in regulating fetal-maternal immune tolerance in healthy and pathological pregnancies. During healthy pregnancy, TGF-β1 induces the production of regulatory T cells (Tregs), maintains the immunosuppressive function of Tregs, mediates the balance of M1/M2 macrophages, and regulates the function of NK cells, thus participating in maintaining fetal-maternal immune tolerance. In addition, some studies have shown that TGF-β1 is dysregulated in patients with recurrent spontaneous abortion or preeclampsia. TGF-β1 may play a role in the occurrence and development of these diseases and may be a potential target for the treatment of these diseases.

Administration of Ligilactobacillus salivarius MP101 in an Elderly Nursing Home during the COVID-19 Pandemic: Immunological and Nutritional Impact

The elderly population living in nursing homes is particularly vulnerable to COVID-19 although individual susceptibility to SARS-CoV-2 infection may be related to the host microbiota. The objective of this work was to investigate the effect of Ligilactobacillus salivarius MP101 on the functional (Barthel index), cognitive (GDS/FAST), and nutritional (MNA) status as well as on the nasal and fecal inflammatory profiles of elderly residents living in a nursing home that is highly affected by COVID-19. A total of 25 residents participated in the trial, which involved the daily ingestion of a dairy product (L. salivarius MP101: 9.3 log10 CFU per unit) for 4 months. Nasal and fecal samples were analyzed for 37 immune factors at recruitment and at the end of the study. After the trial, no change in the GDS/FAST scores were found but, in contrast, the values for the Barthel index and the MNA score improved significantly. The concentrations of some immune factors changed significantly after the trial, including a decrease in the concentrations of BAFF/TNFSF13B, APRIL/TNFSF13, IL8, IL31, osteopontin, sTNF-R1, and sTNF-R2, and an increase in chitinase 3-like 1, IL19, IL35, and pentraxin 3 was also observed. In conclusion, L. salivarius MP101 seems to be a promising strain for improving or maintaining health in this highly vulnerable population.