Saccharomyces cerevisiae-Based Probiotics as Novel Antimicrobial Agents to Prevent and Treat Vaginal Infections

Vaginal infections affect 70% of women during their lifetimes and account for millions of annual doctors' visits. These infections are predominantly represented by vulvovaginal candidiasis (VVC) and bacterial vaginosis (BV). Although standard antimicrobial agents remain the major strategy for the prevention and treatment of vaginal infections, both VVC and BV are difficult to treat due to high rates of resistance and recurrence, high probability of complications, and negative effects on the vaginal microbiota. This review focuses on a new approach of yeast-based probiotics for the prevention and/or treatment of these common vaginal infections

Induction of caspase-11 by aspartyl proteinases of Candida albicans and implication in promoting inflammatory response

We recently demonstrated that the secreted aspartyl proteinases (Saps), Sap2 and Sap6, of Candida albicans have the potential to induce the canonical activation of NLRP3-inflammasome leading to the secretion of IL-1β and IL-18 via caspase-1 activation. We also observed that the activation of caspase-1 is partially independent from the NLRP3 activation pathway. In this study, we examined whether Sap2 and Sap6 are also able to activate the noncanonical inflammasome pathway in murine macrophages. Our data show that both, Sap2 and Sap6, can activate caspase-11 through type I IFN production. Caspase-11 concurs to activate caspase-1 with subsequent increase of IL-1β secretion. Endocytosis and internalization of Saps are required for the induction of type I IFN production, that is essential for induction of noncanonical inflammasome activation. Our study indicates a sophisticated interplay between caspase-1 and caspase-11 that connects canonical and noncanonical pathways of inflammasome activation in response to C. albicans Saps

In vivo induction of neutrophils chemotaxis by secretory aspartyl proteinases of Candida albicans

Secretory aspartyl proteinases (Saps) of Candida albicans are key virulence traits which cause inflammasome-dependent, aseptic inflammation in a mouse model of vaginitis. In this paper, neutrophil migration in response to Sap2, Sap6 and chemo-attractive products released from Sap-treated vaginal epithelium was measured in vitro, ex vivo and in vivo. Our results show that Sap2 and Sap6 induce neutrophil migration and production of potent chemoattractive chemokines such as IL-8 and MIP-2 by vaginal epithelial cells. Our data suggest that at least part of MIP-2 production depends upon IL-1β activity. The vaginal fluid of Candida-infected mice contained a heat-labile inhibitor of neutrophil candidacidal activity that was absent from the vaginal fluid of Sap-treated mice. Overall, our data provide additional information on the capacity of C. albicans Saps to cause aseptic vaginal inflammation and highlight the potential role of some chemokines released from vaginal epithelial cells in this phenomenon

Saccharomyces cerevisiae CNCM I-3856 as a New Therapeutic Agent Against Oropharyngeal Candidiasis

Oropharyngeal candidiasis is a common opportunistic mucosal infection of the oral cavity, mainly caused by an overgrowth of Candida albicans. This infection can inhibit nutritional intakes and strongly affect quality of life. To date, standard therapeutic strategies involving the administration of antifungal drugs can bring several side effects, not least the emergence of drug-resistant strains. The purpose of this study is to investigate the effectiveness of Saccharomyces cerevisiae CNCM I-3856 (live or inactivated cells) against oropharyngeal candidiasis. Our results show that administration of S. cerevisiae CNCM I-3856 (live or inactivated cells) in the oral cavity of C57BL/6J mice resulted in a protective effect against oropharyngeal candidiasis. The strongest effect was obtained with live S. cerevisiae CNCM I-3856. This was related to: (1) a decrease in C. albicans load in the oral cavity, esophagus, stomach, and duodenum; (2) an early resolution of inflammatory process in the tongue; (3) a marked reduction in C. albicans virulence factors; and (4) a consistent increase in neutrophil antimicrobial capacity. These findings suggest that S. cerevisiae products are potentially beneficial in the treatment of oropharyngeal candidiasis

Zinc prevents vaginal candidiasis by inhibiting expression of an inflammatory fungal protein

This is the author accepted manuscript. The final version is available from the American Association for the Advancement of Science via the DOI in this recordData and materials availability: All data associated with this study are present in the paper or the Supplementary Materials. Raw data from the figures are given in data file S1.Candida causes an estimated half-billion cases of vulvovaginal candidiasis (VVC) every year. VVC is most commonly caused by Candida albicans, which, in this setting, triggers nonprotective neutrophil infiltration, aggressive local inflammation, and symptomatic disease. Despite its prevalence, little is known about the molecular mechanisms underpinning the immunopathology of this fungal infection. In this study, we describe the molecular determinant of VVC immunopathology and a potentially straightforward way to prevent disease. In response to zinc limitation, C. albicans releases a trace mineral binding molecule called Pra1 (pH-regulated antigen). Here, we show that the PRA1 gene is strongly up-regulated during vaginal infections and that its expression positively correlated with proinflammatory cytokine concentrations in women. Genetic deletion of PRA1 prevented vaginal inflammation in mice, and application of a zinc solution down-regulated expression of the gene and also blocked immunopathology. We also show that treatment of women suffering from recurrent VVC with a zinc gel prevented reinfections. We have therefore identified a key mediator of symptomatic VVC, giving us an opportunity to develop a range of preventative measures for combatting this disease.Wellcome TrustMedical Research Council (MRC)National Institute for Health and Care Research (NIHR)Biotechnology and Biological Sciences Research Council (BBSRC

Impact of secreted glucanases upon the cell surface and fitness of Candida albicans during colonisation and infection.

Acknowledgements We thank Raif Yuecel and Attila Bebes in the Exeter Centre for Cytomics for their help with the cytometry, and Annie Phillips-Brookes, Jamie Harvey and the BSU staff for their support with the animal experimentation. We are grateful to Karen Moore, Paul O’Neill and Jemima Onime in the University of Exeter Sequencing Facility University of Exeter Sequencing Facility for their help with the barcode sequencing. We also thank Paulina Cherek in the Bioimaging Facility in Exeter Biosciences for her help with the transmission electron microscopy, and Darren Thomson in the MRC Centre for Medical Mycology for his support for our the DeltaVision imaging. For the purpose of open access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission.Peer reviewe

Saccharomyces cerevisiae-based probiotic as novel anti-fungal and anti-inflammatory agent for therapy of vaginal candidiasis

Previously we demonstrated that the treatment with live Saccharomyces cerevisiae exerts beneficial therapeutic effects against vaginal candidiasis. Here, we address potential mechanisms particularly examining the probiotic capacity to modulate both fungus and host-related factors. We show that the S. cerevisiae-based probiotic markedly affects the expression of virulence traits of Candida albicans such as aspartyl proteinases (SAPs) as well as hyphae-associated proteins Hwp1 and Ece1 in the vaginal cavity. On the host side, the probiotic suppression of the influx of neutrophils caused by the fungus into the vaginas of the mice is likely related to: (1) lower production of interleukin-8; and (2) inhibition of SAPs expression. However, these neutrophils displayed reactive oxygen species hyperproduction and increased killing activity as compared to the neutrophils of placebo-treated mice. There was no evidence of any cytotoxic effect by the probiotic, either when used in vivo on vaginal epithelial cell and organ architecture, or in in vitro in human vaginal epithelium. Inactivated yeast cells did not affect any of the factors above. In summary, the data suggest that the beneficial effect exerted by this S. cerevisiae-based probiotic is the result of its interference with the expression of fungus virulence factors coupled with the modulation of the inflammatory response of the host

The Candida albicans Pra1 zincophore promotes neutrophils recruitment and inflammation during vulvovaginal candidiasis

The symptoms of infectious diseases are frequently caused by an over­zealous host immune response against the invading microorganism, rather than by the microorganism itself. This is the case for one of the most common mucosal infection, vulvovaginal candidiasis (VVC), where the yeast Candida albicans triggers a non‐protective influx of host immune cells, resulting in aggressive local inflammation and symptomatic disease. The aim of our study was to investigate the role of the zincophore Pra1 in VVC immunopathology. Pra1 is a secreted C. albicans zinc binding protein released during zinc limitation and used by the fungus to forage for this essential micronutrient from the environment. In vitro tissue culture systems, a murine model of experimental vaginal candidiasis and vaginal samples from VVC patients were used to evaluate the role of Pra1 in immunopathology during VVC. Our results show that Pra1 induced neutrophil migration, is expressed at both, neutral and acidic pH by C. albicans during infection of vaginal epithelial cells and the expression was repressed by the addition of zinc. Robust PRA1 expression was also found in clinical vaginal samples and a strong correlation between PRA1 expression and the neutrophil­activating cytokine IL­8 has been demonstrated. In an experimental murine model of VVC, deletion of C. albicans PRA1 abrogated inflammation without affecting fungal burden. These data demonstrate that the zincophore Pra1 is expressed during the VVC and can act as a potent neutrophil chemoattractant molecule, driving inflammation