Inhibitory effects of vaginal Lactobacilli on Candida albicans growth, hyphal formation, biofilm development, and epithelial cell adhesion

Lactic acid in the vaginal milieu modulates the Candida-host interaction

Vulvovaginal candidiasis (VVC) is one of the most common infections caused by Candida albicans. VVC is characterized by an inadequate hyperinflammatory response and clinical symptoms associated with Candida colonization of the vaginal mucosa. Compared to other host niches in which C. albicans can cause infection, the vaginal environment is extremely rich in lactic acid that is produced by the vaginal microbiota. We examined how lactic acid abundance in the vaginal niche impacts the interaction between C. albicans and the human immune system using an in vitro culture in vaginal simulative medium (VSM). The presence of lactic acid in VSM (VSM+LA) increased C. albicans proliferation, hyphal length, and its ability to cause damage during subsequent infection of vaginal epithelial cells. The cell wall of C. albicans cells grown in VSM+LA displayed a robust mannan fibrillar structure, β-glucan exposure, and low chitin content. These cell wall changes were associated with altered immune responses and an increased ability of the fungus to induce trained immunity. Neutrophils were compromised in clearing C. albicans grown in VSM+LA conditions, despite mounting stronger oxidative responses. Collectively, we found that fungal adaptation to lactic acid in a vaginal simulative context increases its immunogenicity favouring a pro-inflammatory state. This potentially contributes to the immune response dysregulation and neutrophil recruitment observed during recurrent VVC.

The Oral Microbiome: A Key Determinant of Oral Health

As the second largest reservoir of human microbes, the oral cavity is colonized by millions of tiny creatures collectively named as oral microbiome. Species detected in human mouth are diverse, including bacteria, fungi, viruses, and protozoa. Active bidirectional interaction exists between the oral microbiome and the host. Stresses from hosts shape the composition, distribution pattern, and the community behaviors of the oral microbiome, while any changes occurring on the oral microbiome may disrupt its symbiosis relationship with the host and ultimately lead to oral and systemic diseases that jeopardize the host's health. In this chapter, the latest understanding about the role of oral microbiome in common oral diseases, including dental caries, periodontal disease, oral candidiasis, and hyposalivation, is discussed.

Dual Mechanisms of Action: Anti-Candida and Anti-Inflammatory Potential of Lactobacillus Fermentation Broth in Treating Vulvovaginal Candidiasis

Vulvovaginal candidiasis (VVC), a condition predominantly caused by Candida albicans, affects millions of women worldwide, prompting the need for alternative treatments due to the side effects and increasing resistance associated with conventional imidazole antifungals. This study investigated VAGINNE®, a novel fermentation broth derived from Lactobacillus species, as a potential VVC treatment. Using a BALB/c mouse model of C. albicans infection, we evaluated VAGINNE®'s effects on vaginal microbiome composition, inflammatory markers, and tissue integrity. Our findings revealed that VAGINNE® treatment enhanced the growth of beneficial Lactobacillus species while suppressing C. albicans proliferation, leading to a more balanced vaginal microbiome. Additionally, VAGINNE® significantly reduced pro-inflammatory cytokines (IL-17A, IL-22, IL-23) in vaginal tissues and systemic inflammatory markers (IL-6, IL-1β) in plasma. Histological analysis showed minimal fungal invasion and preserved vaginal epithelial integrity in VAGINNE®-treated mice compared to untreated controls. These results suggest that VAGINNE® could serve as an effective anti-Candida and anti-inflammatory agent for managing VVC, offering a promising alternative to traditional antifungal treatments. By promoting a healthy vaginal microbiome, reducing inflammation, and maintaining tissue health, this probiotic-based approach presents a novel strategy for addressing VVC, particularly in cases of drug resistance or adverse reactions to standard therapies. This study underscores the potential of microbiome-modulating strategies in managing vaginal infections, paving the way for more targeted and side-effect-free VVC treatments.

Insights into Women's health: Exploring the vaginal microbiome, quorum sensing dynamics, and therapeutic potential of quorum sensing quenchers

The vaginal microbiome is an important aspect of women's health that changes dynamically with various stages of the woman's life. Just like the gut microbiome, the vaginal microbiome can also be affected by pathologies that dramatically change the typical composition of native vaginal microorganisms. However, the mechanism as to how both vaginal endemic and gut endemic opportunistic microbes can express pathogenicity in vaginal polymicrobial biofilms is poorly understood. Quorum sensing is the cellular density-dependent bacterial and fungal communication process in which chemical signaling molecules, known as autoinducers, activate expression for genes responsible for virulence and pathogenicity, such as biofilm formation and virulence factor production. Quorum sensing inhibition, or quorum quenching, has been explored as a potential therapeutic route for both bacterial and fungal infections. By applying these quorum quenchers, one can reduce biofilm formation of opportunistic vaginal microbes and combine them with antibiotics for a synergistic effect. This review aims to display the relationship between the vaginal and gut microbiome, the role of quorum sensing in polymicrobial biofilm formation which cause pathology in the vaginal microbiome, and how quorum quenchers can be utilized to attenuate the severity of bacterial and fungal infections.

Clotrimazole-induced shifts in vaginal bacteriome and lipid metabolism: insights into recovery mechanisms in vulvovaginal candidiasis

AIMS

Vulvovaginal candidiasis (VVC) is a prevalent condition affecting a significant proportion of women worldwide, with recurrent episodes leading to detrimental effects on quality of life. While treatment with clotrimazole is common, the specific alterations it evokes in the vaginal bacteriome and metabolome were previously underexplored.

METHODS AND RESULTS

In this prospective study, we enrolled reproductive-age women diagnosed with single VVC and conducted comprehensive analyses of vaginal fungi, bacteriome, and metabolome before and after local clotrimazole treatment. We observed a significant reduction in Candida albicans and notable improvements in vaginal cleanliness. Advanced sequencing revealed substantial shifts in the vaginal bacteriome, with an increase in Lactobacillus-dominant communities post-treatment. Our findings identified 17 differentially abundant bacterial species, including notable decreases in pathogenic anaerobes such as Gardnerella vaginalis, Dialister micraerophilus, and Aerococcus christensenii, suggesting a restoration of a healthier microbial balance. Furthermore, metabolomic analysis revealed significant changes in 230 metabolites, particularly within lipid metabolism pathways, with marked downregulation of lipid-related compounds linked to inflammation. Correlation studies indicated a strong interplay between lipid metabolites and specific bacterial species, emphasizing the influence of clotrimazole treatment on microbial and metabolic interactions. Importantly, predictive models using microbiota and metabolite signatures demonstrated high accuracy in distinguishing pre- and post-treatment states.

CONCLUSIONS

This research highlights clotrimazole's dual role in effectively clearing Candida infection and promoting a healthier vaginal microenvironment, paving the way for novel microbial and metabolomic-based diagnostic approaches to enhance VVC management and understand its underlying mechanisms.

Vaginal microbiota of pregnant women with Ureaplasma urealyticum and Mycoplasma hominis infections

Background

The association between preterm birth and Mycoplasma species such as Mycoplasma hominis and Ureaplasma urealyticum has been extensively investigated. In a clinical setting, conventional diagnostic methods for them involve culture methods for Mycoplasma spp. and Ureaplasma spp., along with PCR tests. However, the clinical utility of these tests remains controversial, highlighting the necessity for more robust and reliable methods for identifying and understanding Mycoplasma infections.

Objective

This study aimed to assess the distribution of microbiota in pregnant women with Mycoplasma hominis and Ureaplasma urealyticum infection by the comparison of conventional diagnostic methods with vaginal microbial community analysis.

Study Design

This prospective case-control study involved 228 Korean pregnant women and utilized vaginal microbial community analysis, Ureaplasma/Mycoplasma culture, and 12-multiplex PCR for sexually transmitted diseases. Cross-correlation analysis in SPSS 27 compared the results of two conventional methods with vaginal microbial community analysis. R software generated box plots depicting the relative abundance of microorganisms. Network analysis was conducted using Cytoscape.

Results

Positive Ureaplasma urealyticum culture findings were observed in 60.2% of patients, with 76.4% positive for Ureaplasma parvum PCR and 13.2% positive for Ureaplasma urealyticum PCR. Mycoplasma hominis culture was positive only in two patients, while Mycoplasma hominis PCR was positive in eight women. Vaginal microbial community analysis identified significant differences in relative abundances of Gardnerella species type I and Fannyhessea vaginae between the Ureaplasma urealyticum PCR positive and negative groups. Mycoplasma hominis PCR positive patients exhibited significant differences in 11 bacterial species, including Gardnerella species I and Fannyhessea vaginae.

Conclusion

This study suggests that STD-PCR may be more accurate than Ureaplasma/Mycoplasma culture for the diagnosis of Mycoplasma hominis and Ureaplasma urealyticum infection. Also, the presence of Gardnerella species I and Fannyhessea vaginae implies their potential influences on Ureaplasma urealyticum and Mycoplasma hominis infections based on results of vaginal microbial community analysis. Therefore, vaginal microbial community analysis may give the more information of their pathophysiology.

Inflammatory cytokine signalling in vulvovaginal candidiasis: a hot mess driving immunopathology

Protective immunity to opportunistic fungal infections consists of tightly regulated innate and adaptive immune responses that clear the infection. Immune responses to infections of the vaginal mucosa by Candida species are, however, an exception. In the case of vulvovaginal candidiasis (VVC), the inflammatory response is associated with symptomatic disease, rather than that it results in pathogen clearance. As such VVC can be considered an inflammatory disease, which is a significant public health problem due to its predominance as a female-specific fungal infection. Particularly, women with recurrent VVC (RVVC) suffer from a significant negative impact on their quality of life and mental health. Knowledge of the inflammatory pathogenesis of (R)VVC may guide more effective diagnostic and therapeutic options to improve the quality of life of women with (R)VVC. Here, we review the immunopathogenesis of (R)VVC describing several elements that induce an inflammatory arson, starting with the activation threshold established by vaginal epithelial cells that prevent unnecessary ignition of inflammatory responses, epithelial and inflammasome-dependent immune responses. These inflammatory responses will drive neutrophil recruitment and dysfunctional neutrophil-mediated inflammation. We also review the, sometimes controversial, findings on the involvement of adaptive and systemic responses. Finally, we provide future perspectives on the potential of some unexplored cytokine axes and discuss whether VVC needs to be subdivided into subgroups to improve diagnosis and treatment.

Inhibiting pathogenicity of vaginal Candida albicans by lactic acid bacteria and MS analysis of their extracellular compounds

Maintaining healthy vaginal microflora post-puberty is critical. In this study we explore the potential of vaginal lactic acid bacteria (LAB) and their extracellular metabolites against the pathogenicity of Candida albicans. The probiotic culture free supernatant (PCFS) from Lactobacillus crispatus, L. gasseri, and L. vaginalis exhibit an inhibitory effect on budding, hyphae, and biofilm formation of C. albicans. LGPCFS manifested the best potential among the LAB PCFS, inhibiting budding for 24 h and restricting hyphae formation post-stimulation. LGPCFS also pre-eminently inhibited biofilm formation. Furthermore, L. gasseri itself grew under RPMI 1640 stimulation suppressing the biofilm formation of C. albicans. The PCFS from the LAB downregulated the hyphal genes of C. albicans, inhibiting the yeast transformation to fungi. Hyphal cell wall proteins HWP1, ALS3, ECE1, and HYR1 and transcription factors BCR1 and CPH1 were downregulated by the metabolites from LAB. Finally, the extracellular metabolome of the LAB was studied by LC-MS/MS analysis. L.gasseri produced the highest antifungal compounds and antibiotics, supporting its best activity against C. albicans. Vaginal LAB and their extracellular metabolites perpetuate C. albicans at an avirulent state. The metabolites produced by these LAB in vitro have been identified, and can be further exploited as a preventive measure against vaginal candidiasis.

Vaginal Microbiota Molecular Profiling in Women with Bacterial Vaginosis: A Novel Diagnostic Tool

Bacterial vaginosis (BV) is a most common microbiological syndrome. Multiplex next-generation sequencing (NGS) or molecular tests allow a complete and accurate vaginal microbiota profiling in order to determine the primary causative agent. Due to the high costs and limited availability of NGS, the multiplex real-time PCR draws more attention. The present study aimed to evaluate the microbial composition and dominant lactobacilli species in non-pregnant women with bacterial vaginosis using a multiplex RT-PCR test and determine its diagnostic significance. In total, 331 women complaining of vaginal discharge were included. BV was confirmed upon clinical examination and Nugent criteria. A real-time PCR test was carried out with a new Femoflor test, which identifies opportunistic bacteria, STD pathogens, and some viruses. According to the results, the rate of lactobacilli is significantly reduced in BV-affected patients when compared to healthy women. Moreover, the rate of L. crispatus significantly decreases, while the rate of L. iners remains high. Among obligate anaerobic bacteria, Gardnerella vaginalis was the most prevalent in women with BV. The Femoflor test demonstrated high sensitivity and specificity for diagnosing BV. Moreover, the test allows the identification of infection in women with intermediate vaginal microbiota, as well as STD pathogens, and viruses. Thus, the application of real-time PCR tests can be effectively used in vaginal microbiota evaluation in women with BV, intermediate vaginal microbiota, and healthy women. In addition, this test may be used as an alternative to the Amsel criteria and Nugent scoring method in diagnosing BV.