The Interplay between Candida albicans, Vaginal Mucosa, Host Immunity and Resident Microbiota in Health and Disease: An Overview and Future Perspectives

Health benefits and risks of fermented foods-the PIMENTO initiative

Worldwide, fermented foods (FF) are recognized as healthy and safe. Despite the rapid increase of research papers, there is a lack of systematic evaluation of the health benefits and risks of FF. The COST Action CA20128 "Promoting innovation of fermented foods" (PIMENTO) aims to provide a comprehensive assessment on the available evidence by compiling a set of 16 reviews. Seven reviews will cover clinical and biological endpoints associated with major health indicators across several organ systems, including the cardiovascular, gastrointestinal, neurological, immune, and skeletal systems. Nine reviews will address broader biological questions associated with FF including bioactive compounds and vitamin production, nutrient bioavailability and bioaccessibility, the role of FF in healthy diets and personalized nutrition, food safety, regulatory practices, and finally, the health properties of novel and ethnic FF. For each outcome assessed in the reviews, an innovative approach will be adopted based on EFSA's published guidance for health claim submissions. In particular, each review will be composed of three parts: (1) a systematic review of available human studies; (2) a non-systematic review of the mechanism of action related to the clinical endpoints measured by the human studies identified in part 1; and (3) a non-systematic review of the characterization of the FF investigated in the human studies identified in part 1. The evidence and research gaps derived from the reviews will be summarized and published in the form of a strategic road map that will pave the way for future research on FF.

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.

Bacillus coagulans LMG S-24828 Impairs Candida Virulence and Protects Vaginal Epithelial Cells against Candida Infection In Vitro

Probiotics are living microbes that provide benefits to the host. The growing data on health promotion, following probiotics administration, increased interest among researchers and pharmaceutical companies. Infections of the lower genital tract in females, caused by a wide range of pathogens, represent one of the main areas for the use of probiotics and postbiotics. Vulvovaginal candidiasis (VVC) affects 75% of women of reproductive age at least once during their lifetime, with 5-8% developing the recurrent form (RVVC). The disease is triggered by the overgrowth of Candida on the vaginal mucosa. Here, in order to establish its probiotic potential in the context of VVC, we evaluated the anti-fungal effects of the spore-producing Bacillus coagulans LMG S-24828 against C. albicans and C. parapsilosis as well as its beneficial effects in counteracting Candida vaginal infection in vitro. Our results show that both live B. coagulans and its Cell-Free Supernatant (CFS) exerted antifungal activity against both fungi. Moreover, live B. coagulans reduced hyphal formation, inhibited C. albicans adhesion to vaginal epithelial cells, showed co-aggregation capacity, and exerted a protective effect on vaginal epithelial cells infected with C. albicans. These data suggest that B. coagulans LMG S-24828 may provide benefits in the context of Candida vaginal infections.

Effect of pH and neutrophil count on the motility and persistence of spermatozoa in the vagina of candidiasis rat models

Sexual violence is a global issue affecting individuals regardless of their relationship to the perpetrator or the setting. Microscopic examination of spermatozoa from vaginal swabs is crucial in investigating cases of sexual intercourse to determine the time of the crime. Factors such as vaginal pH and neutrophil count influence the motility and persistence of spermatozoa in the vagina, particularly in conditions like candidiasis, highlighting the need for further research in this area. This study aimed to determine the effect of pH and neutrophil count on the motility and persistence of spermatozoa in the vagina with candidiasis. An experimental study was conducted using white rats (Rattus norvegicus) of the Wistar strain, with four male rats providing spermatozoa samples and 32 female rats receiving treatment. The female rats were divided into two groups: the normal group and the candidiasis model group. In both groups, the female rats were given vaginal insemination of spermatozoa. Variables measured included pH, neutrophil count, motility, and persistence of spermatozoa in the vagina. Data were analyzed using the Mann-Whitney test, followed by the Spearman correlation test. The findings revealed that spermatozoa motility lasted up to three minutes in normal rats, whereas in the candidiasis model, it was reduced to two minutes. Additionally, spermatozoa persistence in the vagina lasted up to six days in the normal group compared to up to three days in the candidiasis model. There were significant differences in pH, neutrophil count, motility, and persistence of spermatozoa in the vagina between the normal group and the candidiasis model (all had p<0.001). There was a correlation between pH and neutrophil count with the motility and persistence of spermatozoa in the rat's vagina (p<0.001). In conclusion, vaginal pH and neutrophil count influence the motility and persistence of spermatozoa in the vagina of candidiasis rat models.

In vitro and in vivo inhibitory effects of the Sanghuang mushroom extracts against Candida albicans

Aim: To explore the antifungal potential of Sanghuang mushroom, a traditional Chinese medicine. Materials & methods: The antifungal properties and the potential mechanism of Sanghuang mushroom extracts against Candida albicans were studied in vitro and in vivo. Results: Sanghuang mushroom extracts inhibited the biofilm formation, increased the cell membrane permeability and promoted cell apoptosis of C. albicans in vitro. In a murine model of vulvovaginal candidiasis, Sanghuang mushroom extracts reduced the vaginal fungal load, improved inflammatory cell infiltration and downregulated the expression of TNF-α, IL-1β and IL-6. Untargeted metabolomic analysis suggested the presence of ten antifungal components in Sanghuang mushroom extracts. Conclusion: Sanghuang mushroom extracts showed promise as antifungal agent against candidiasis, with potential therapeutic implications.

Effect of Pulsatilla decoction on vulvovaginal candidiasis in mice. Evidences for its mechanisms of action

BACKGROUND

Vulvovaginal candidiasis (VVC) is a common infection that affects the female reproductive tract. Pulsatilla decoction (PD), a traditional Chinese herbal medicine, is a classic and effective prescription for VVC. However, its mechanism of action remains unclear.

PURPOSE

This study aimed to evaluate the efficacy and potential mechanism of action of the n-butanol extract of Pulsatilla decoction (BEPD) in VVC treatment.

METHODS

High performance liquid chromatography (HPLC) was used to detect the main active ingredients in BEPD. A VVC-mouse model was constructed using an estrogen-dependent method to evaluate the efficacy of BEPD in VVC treatment. Fungal burden and morphology in the vaginal cavity were comprehensively assessed. Candida albicans-induced inflammation was examined in vivo and in vitro. The effects of BEPD on the Protein kinase Cδ (PKCδ) /NLR family CARD domain-containing protein 4 (NLRC4)/Interleukin-1 receptor antagonist (IL-1Ra) axis were analyzed using by immunohistochemistry (IHC), immunofluorescence (IF), western blot (WB), and reverse transcription-quantitative polymerase chain reaction (qRT-PCR).

RESULTS

BEPD inhibited fungal growth in the vagina of VVC mice, preserved the integrity of the vaginal mucosa, and suppressed inflammatory responses. Most importantly, BEPD activated the "silent" PKCδ/NLRC4/IL-1Ra axis and negatively regulated NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome, thereby exerting a therapeutic efficacy on VVC.

CONCLUSIONS

BEPD effects on mice with VVC were dose-dependent. BEPD protects against VVC by inhibiting inflammatory response and NLRP3 inflammasome via the activation of the PKCδ/NLRC4/IL-1Ra axis. This study revealed the pharmacological mechanism of BEPD in VVC treatment and provided further evidence for the application of BEPD in VVC treatment.

Stephanoascus ciferrii Complex: The Current State of Infections and Drug Resistance in Humans

In recent years, the incidence of fungal infections in humans has increased dramatically, accompanied by an expansion in the number of species implicated as etiological agents, especially environmental fungi never involved before in human infection. Among fungal pathogens, Candida species are the most common opportunistic fungi that can cause local and systemic infections, especially in immunocompromised individuals. Candida albicans (C. albicans) is the most common causative agent of mucosal and healthcare-associated systemic infections. However, during recent decades, there has been a worrying increase in the number of emerging multi-drug-resistant non-albicans Candida (NAC) species, i.e., C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, C. auris, and C. ciferrii. In particular, Candida ciferrii, also known as Stephanoascus ciferrii or Trichomonascus ciferrii, is a heterothallic ascomycete yeast-like fungus that has received attention in recent decades as a cause of local and systemic fungal diseases. Today, the new definition of the S. ciferrii complex, which consists of S. ciferrii, Candida allociferrii, and Candida mucifera, was proposed after sequencing the 18S rRNA gene. Currently, the S. ciferrii complex is mostly associated with non-severe ear and eye infections, although a few cases of severe candidemia have been reported in immunocompromised individuals. Low susceptibility to currently available antifungal drugs is a rising concern, especially in NAC species. In this regard, a high rate of resistance to azoles and more recently also to echinocandins has emerged in the S. ciferrii complex. This review focuses on epidemiological, biological, and clinical aspects of the S. ciferrii complex, including its pathogenicity and drug resistance.

Patients with recurrent vulvovaginal candidiasis exhibit a decrease in both the fungicidal activity of neutrophils and the proliferation of peripheral blood mononuclear cells

BACKGROUND

Recurrent vulvovaginal candidiasis (RVVC) is an important and underestimated fungal infection.

OBJECTIVE

We aimed to determine the fungicidal and proliferative capacities of neutrophils and peripheral blood mononuclear cells (PBMCs), respectively and the clinical and microbiological characteristics of a cohort of Colombian patients diagnosed with RVVC.

METHODS

A cross-sectional study was conducted. A total of 66 women were included (40 diagnosed with RVVC and 26 healthy women [HW]). Demographic and clinical data were recorded. Vaginal fluid samples were obtained for isolation, identification and antifungal susceptibility testing of Candida species using selective culture media and the Vitek 2.0® system. Blood samples were also obtained to evaluate cell subpopulations; furthermore, neutrophils and PBMCs were isolated to determine their fungicidal and proliferative capacities, respectively.

RESULTS

The median age was 29 (IQR: 34-23) for RVVC and 24 (IQR: 30-23) for HW. Only two species of the genus Candida were identified: Candida albicans (92.5%) and Candida lusitaniae (7.5%). Resistance to fluconazole, voriconazole, flucytosine and amphotericin B was observed on six C. albicans isolates and one C. lusitaniae isolate. Only the family history of vulvovaginal candidiasis was associated with RVVC occurrence. The RVVC group exhibited a significantly higher number of neutrophils but with lower fungicidal activity in comparison to HW; likewise, PBMCs from RVVC patients presented a lower proliferation index when stimulated with C. albicans.

CONCLUSION

Contrary to what has been reported worldwide, in Colombian patients with RVVC, C. albicans was the main isolated species without increased antifungal resistance. The diminished fungicidal and proliferative capacities of neutrophils and PBMCs, respectively, could suggest a possible alteration in the innate and adaptive immune responses.

Bacterial Vaginosis and Vulvovaginal Candidiasis Pathophysiologic Interrelationship

Among the infectious causes of vulvovaginal symptoms, bacterial vaginosis (BV) and vulvovaginal candidiasis (VVC) dominate. Apart from infrequent mixed infections, both are considered independent and caused by unrelated pathogenic mechanisms. Clinical experience, however, is strongly suggestive that in some populations these infections are linked with recurrent BV (RBV) serving as the dominant etiopathogenic trigger for development of recurrent VVC (RVVC) with profound clinical and therapeutic consequences. The biologic basis for this critical interrelationship is discussed and suggests that as a consequence of BV dysbiosis, and not necessarily because of antibiotics prescribed, immune defenses are compromised, neutralizing vaginal yeast tolerance. The consequent BV-induced vaginal proinflammatory environment predisposes to mixed infection or consecutive episodes of post-treatment VVC. Recurrent BV and repeated antimicrobial drug exposure also predispose to acquired fluconazole resistance in C. albicans isolates, contributing to refractory vulvovaginal candidiasis.

Selected N-Terpenyl Organoselenium Compounds Possess Antimycotic Activity In Vitro and in a Mouse Model of Vulvovaginal Candidiasis

In the present work, a series of N-terpenyl organoselenium compounds (CHB1-6) were evaluated for antimycotic activity by determining the minimum inhibitory concentration (MIC) for each compound in fluconazole (FLU)-sensitive (S1) and FLU-resistant (S2) strains of Candida albicans (C. albicans). The most active compounds in the MIC screen were CHB4 and CHB6, which were then evaluated for cytotoxicity in human cervical cancer cells (KB-3-1) and found to be selective for fungi. Next, CHB4 and CHB6 were investigated for skin irritation using a reconstructed 3D human epidermis and both compounds were considered safe to the epidermis. Using a mouse model of vulvovaginal candidiasis (VVC), CHB4 and CHB6 both exhibited antimycotic efficacy by reducing yeast colonization of the vaginal tract, alleviating injury to the vaginal mucosa, and decreasing the abundance of myeloperoxidase (MPO) expression in the tissue, indicating a reduced inflammatory response. In conclusion, CHB4 and CHB6 demonstrate antifungal activity in vitro and in the mouse model of VVC and represent two new promising antifungal agents.

Advancing Vaccine Strategies against Candida Infections: Exploring New Frontiers

Candida albicans, along with several non-albicans Candida species, comprise a prominent fungal pathogen in humans, leading to candidiasis in various organs. The global impact of candidiasis in terms of disease burden, suffering, and fatalities is alarmingly high, making it a pressing global healthcare concern. Current treatment options rely on antifungal drugs such as azoles, polyenes, and echinocandins but are delimited due to the emergence of drug-resistant strains and associated adverse effects. The current review highlights the striking absence of a licensed antifungal vaccine for human use and the urgent need to shift our focus toward developing an anti-Candida vaccine. A number of factors affect the development of vaccines against fungal infections, including the host, intraspecies and interspecies antigenic variations, and hence, a lack of commercial interest. In addition, individuals with a high risk of fungal infection tend to be immunocompromised, so they are less likely to respond to inactivated or subunit whole organisms. Therefore, it is pertinent to discover newer and novel alternative strategies to develop safe and effective vaccines against fungal infections. This review article provides an overview of current vaccination strategies (live attenuated, whole-cell killed, subunit, conjugate, and oral vaccine), including their preclinical and clinical data on efficacy and safety. We also discuss the mechanisms of immune protection against candidiasis, including the role of innate and adaptive immunity and potential biomarkers of protection. Challenges, solutions, and future directions in vaccine development, namely, exploring novel adjuvants, harnessing the trained immunity, and utilizing immunoinformatics approaches for vaccine design and development, are also discussed. This review concludes with a summary of key findings, their implications for clinical practice and public health, and a call to action for continued investment in candidiasis vaccine research.