In vitro modulation of probiotic bacteria on the biofilm of Candida glabrata

A conspicuous new concept of pathogens living as the microbial societies in the human host rather than free planktonic cells has raised considerable concerns among scientists and clinicians. Fungal biofilms are communities of cells that possess distinct characteristic such as increased resistance to the immune defence and antimycotic agents in comparison to their planktonic cells counterpart. Therefore, inhibition of the biofilm may represent a new paradigm for antifungal development. In this study, we aim to evaluate the in vitro modulation of vulvovaginal candidiasis (VVC)-causing Candida glabrata biofilms using probiotic lactobacilli strains. Probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 were shown to have completely inhibited C. glabrata biofilms and the results were corroborated by scanning electron microscopy (SEM), which revealed scanty structures of the mixed biofilms of C. glabrata and probiotic lactobacilli strains. In addition, biofilm-related C. glabrata genes EPA6 and YAK1 were downregulated in response to the probiotic lactobacilli challenges. The present study suggested that probiotic L. rhamnosus GR-1 and L. reuteri RC-14 strains inhibited C. glabrata biofilm by partially impeding the adherence of yeast cells and the effect might be contributed by the secretory compounds produced by these probiotic lactobacilli strains. Further investigations are required to examine and identify the biofilm inhibitory compounds and the mechanism of probiotic actions of these lactobacilli strains

Physiologically Relevant Alternative Carbon Sources Modulate Biofilm Formation, Cell Wall Architecture and the Stress and Antifungal Resistance of Candida glabrata

Acknowledgments: This study was funded by Fundamental Research Grant Scheme (FRGS) from Ministry of Education (MOE), Malaysia (Grant number: 01-01-14-1456FR). S.Y.C. is a recipient of the MyBrain 15 Scholarship from MOE, Malaysia. AB was supported by the UK Medical Research Council (www.mrc.ac.uk: MR/M026663/1), the Medical Research Council Centre for Medical Mycology (MR/N006364/1), the Wellcome Trust (www.wellcome.ac.uk: 097377), and the European Commission (FunHoMic: H2020-MSCA-ITN-2018-812969)Peer reviewedPublisher PD

Characterisation of the probiotic qualities exhibited by lactobacilli strains isolated from the anogenital tract

Introduction: Lactobacilli are well-documented probiotics that exert health benefits on their host. They exhibit characteristics that make them potential alternative treatments to address the antimicrobial resistance conundrum and diseases. Their mechanism of action varies with strain and species. Five lactobacilli strains previously isolated from the anogenital region were subjected to several assessments highlighted in the FAO/WHO document, ‘Guidelines for the Evaluation of Probiotics in Food’ to determine its suitability as potential probiotics. Methods: The five lactobacilli strains were subcultured onto Man de Rogosa agar (MRS). Their ability to auto- and co-aggregate was determined spectrophotometrically. Simultaneously, the cell surface hydrophobic properties of these strains towards xylene and toluene were evaluated using the microbial adhesion to hydrocarbon (MATH) test. The lactobacilli strains were also tested for their ability to withstand acid, bile and spermicide to determine their level of tolerance. Results: Lact. reuteri 29A, L. delbrueckii 45E and L. reuteri 29B exhibited the highest degree of auto- and co-aggregation properties. These lactobacilli strains also demonstrated high cell surface hydrophobicity, with the exception of L. delbrueckii 45E. Further tests to evaluate the isolated lactobacilli tolerance identified L. reuteri 29B as the most tolerant strain towards low pH (pH 2.5 for 4 h), high bile concentration (0.5% for 4 h) and high spermicides concentration (up to 10%). Conclusion: Out of the five lactobacilli strains which possessed high antimicrobial activities, L. reuteri 29B portrayed the best probiotic qualities with good auto- and co-aggregation abilities and high tolerance against acid, bile and spermicide

Glyoxylate cycle gene ICL1 is essential for the metabolic flexibility and virulence of Candida glabrata

We would like to acknowledge Professor Karl Kuchler from Medical University of Vienna for the kind gifts of C. glabrata strains used in this study. This study was funded by Fundamental Research Grant Scheme (FRGS) from Ministry of Education (MOE), Malaysia (Grant number: 01-01-14-1456FR). S.Y. is a recipient of the MyBrain 15 Scholarship from MOE, Malaysia. A.B. was supported by the Medical Research Council Centre for Medical Mycology at the University of Aberdeen (MR/N006364/1), by a programme grant from the UK Medical Research Council (MR/M026663/1), by a Strategic Award from the Wellcome Trust (097377) and by a grant from the UK Biotechnology and Biological Sciences Research Council (BB/P020119/1).Peer reviewedPublisher PD

Multiancestry Genome-Wide Association Study of Lipid Levels Incorporating Gene-Alcohol Interactions

A person's lipid profile is influenced by genetic variants and alcohol consumption, but the contribution of interactions between these exposures has not been studied. We therefore incorporated gene-alcohol interactions into a multiancestry genome-wide association study of levels of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides. We included 45 studies in stage 1 (genome-wide discovery) and 66 studies in stage 2 (focused follow-up), for a total of 394,584 individuals from 5 ancestry groups. Analyses covered the period July 2014-November 2017. Genetic main effects and interaction effects were jointly assessed by means of a 2-degrees-of-freedom (df) test, and a 1-df test was used to assess the interaction effects alone. Variants at 495 loci were at least suggestively associated (P <1 x 10(-6)) with lipid levels in stage 1 and were evaluated in stage 2, followed by combined analyses of stage 1 and stage 2. In the combined analysis of stages 1 and 2, a total of 147 independent loci were associated with lipid levels at P <5 x 10(-8) using 2-df tests, of which 18 were novel. No genome-wide-significant associations were found testing the interaction effect alone. The novel loci included several genes (proprotein convertase subtilisin/kexin type 5 (PCSK5), vascular endothelial growth factor B (VEGFB), and apolipoprotein B mRNA editing enzyme, catalytic polypeptide 1 (APOBEC1) complementation factor (A1CF)) that have a putative role in lipid metabolism on the basis of existing evidence from cellular and experimental models.Peer reviewe

A multi-ancestry genome-wide study incorporating gene-smoking interactions identifies multiple new loci for pulse pressure and mean arterial pressure

Elevated blood pressure (BP), a leading cause of global morbidity and mortality, is influenced by both genetic and lifestyle factors. Cigarette smoking is one such lifestyle factor. Across five ancestries, we performed a genome-wide gene-smoking interaction study of mean arterial pressure (MAP) and pulse pressure (PP) in 129 913 individuals in stage 1 and follow-up analysis in 480 178 additional individuals in stage 2. We report here 136 loci significantly associated with MAP and/or PP. Of these, 61 were previously published through main-effect analysis of BP traits, 37 were recently reported by us for systolic BP and/or diastolic BP through gene-smoking interaction analysis and 38 were newly identified (P <5 x 10(-8), false discovery rate <0.05). We also identified nine new signals near known loci. Of the 136 loci, 8 showed significant interaction with smoking status. They include CSMD1 previously reported for insulin resistance and BP in the spontaneously hypertensive rats. Many of the 38 new loci show biologic plausibility for a role in BP regulation. SLC26A7 encodes a chloride/bicarbonate exchanger expressed in the renal outer medullary collecting duct. AVPR1A is widely expressed, including in vascular smooth muscle cells, kidney, myocardium and brain. FHAD1 is a long non-coding RNA overexpressed in heart failure. TMEM51 was associated with contractile function in cardiomyocytes. CASP9 plays a central role in cardiomyocyte apoptosis. Identified only in African ancestry were 30 novel loci. Our findings highlight the value of multi-ancestry investigations, particularly in studies of interaction with lifestyle factors, where genomic and lifestyle differences may contribute to novel findings.Peer reviewe

Glyoxylate cycle and alternative carbon metabolism in metabolic flexibility and pathogenicity of Candida glabrata

Distinct microenvironments in the host can differ significantly (e.g. nutrients availability) and that Candida glabrata, in order to be an effective human pathogen, must transit between these niches and adapt to the differences. In addition, most of the immune cells also actively deprive nutritional resources from invading pathogens, which makes the survival of intracellular pathogens even more challenging. Candida glabrata appears to utilise unique stealth, evasion and persistence strategies in subverting the onslaught of host immune response during systemic infection. In fact, it is surprising that C. glabrata triggers its own engulfment by macrophages. Considering the glucose-deficient condition within the macrophages, C. glabrata must be able to assimilate endogenous resources such as alternative carbon sources for their survival. The present study concentrated on the impact of alternative carbon metabolism in the metabolic flexibility and pathogenicity of C. glabrata. Growth on alternative carbon sources such as acetate, lactate, ethanol and oleic acid induced alteration in several fitness and pathogenic attributes of C. glabrata. These include the reduction in planktonic growth, biofilm formation, and oxidative stress resistance. Alternative carbon sources also modulated the cell wall architecture of C. glabrata, as demonstrated by the reduction of β-glucan and chitin layer, and the increase of mannan layer. Furthermore, the antifungal resistance of C. glabrata grown in alternative carbon sources was significantly enhanced. The metabolic regulation of alternative carbon metabolism in C. glabrata was subsequently explored using high-throughput transcriptomic and proteomic analyses in response to acetate, an alternative carbon source that has been proven to be relevant in vivo. Collectively, both transcriptome and proteome data revealed that the regulation of alternative carbon metabolism in C. glabrata substantially resembled human fungal pathogens such as Candida albicans and Cryptococcus neoformans, with up-regulation of many proteins and transcripts from the glyoxylate cycle and gluconeogenesis, namely isocitrate lyase (ICL1), malate synthase (MLS1), phosphoenolpyruvate carboxykinase (PCK1) and fructose 1,6- biphosphatase (FBP1). In the absence of glucose, C. glabrata shifted its metabolism to hexose anabolism from the available carbon source. The results essentially suggest that the gluconeogenic metabolism are possibly critical for the survival of phagocytosed C. glabrata within the glucose-deficient macrophages. The importance of the glyoxylate cycle enzyme gene ICL1 in the metabolic flexibility and pathogenicity of C. glabrata was further substantiated by the comprehensive analyses of icl1Δ mutant strains. Indeed, disruption of ICL rendered C. glabrata unable to assimilate several alternative carbon sources, as well as reduced its biofilm formation capability. In addition, ICL1 is also pivotal for the survival of phagocytosed C. glabrata, as the icl1Δ mutant strains were significantly more susceptible to macrophage killing relative to wild-type strain. Finally, evaluation of icl1Δ mutant strains in a mouse model of invasive candidiasis showed that ICL1 is essentially required for the full virulence of C. glabrata in vivo. In conclusion, the present study demonstrated that alternative carbon metabolism and the glyoxylate cycle is crucial for the metabolic flexibility and pathogenicity of C. glabrata in vitro and in vivo. The findings implicate ICL1 as a promising target in the development of novel and innovative treatments for a better management of invasive candidiasis

Vulvovaginal candidosis: contemporary challenges and the future of prophylactic and therapeutic approaches

Vulvovaginal candidosis (VVC) is a common gynaecological disorder that is delineated by the inflammation of vaginal wall and it is caused by the opportunistic fungal pathogen Candida species. In fact, three out of every four women will experience at least one occasion of VVC during some point in their lives. Although uncomplicated VVC is relatively harmless, the complicated VVC such as recurrent attack often creates restlessness and depression in the patients, thus greatly affects their quality of life. Managements of VVC are usually associated with the use of antimycotic suppositories, topical cream or oral agents. These antimycotic agents are either available over-the-counter or prescribed by the clinicians. In recent decades, the rise of clinical challenges such as the increased prevalence of resistant Candida strains, recurrent VVC infection and adverse effects of multidrug interactions have necessitated the development of novel therapeutic or prophylactic options to combat the complicated VVC in the future. In this review, we discuss the current antimycotic treatments available for Candida vaginitis and the problems that exist in these seemingly effective treatments. Besides, we attempt to contemplate some of the future and prospective strategies surrounding the development of alternative therapeutic and prophylactic options in treating and preventing complicated VVC respectively

Candida glabrata: pathogenicity and resistance mechanisms for adaptation and survival

Candida glabrata is a yeast of increasing medical relevance, particularly in critically ill patients. It is the second most isolated Candida species associated with invasive candidiasis (IC) behind C. albicans. The attributed higher incidence is primarily due to an increase in the acquired immunodeficiency syndrome (AIDS) population, cancer, and diabetic patients. The elderly population and the frequent use of indwelling medical devices are also predisposing factors. This work aimed to review various virulence factors that facilitate the survival of pathogenic C. glabrata in IC. The available published research articles related to the pathogenicity of C. glabrata were retrieved and reviewed from four credible databases, mainly Google Scholar, ScienceDirect, PubMed, and Scopus. The articles highlighted many virulence factors associated with pathogenicity in C. glabrata, including adherence to susceptible host surfaces, evading host defences, replicative ageing, and producing hydrolytic enzymes (e.g., phospholipases, proteases, and haemolysins). The factors facilitate infection initiation. Other virulent factors include iron regulation and genetic mutations. Accordingly, biofilm production, tolerance to high-stress environments, resistance to neutrophil killings, and development of resistance to antifungal drugs, notably to fluconazole and other azole derivatives, were reported. The review provided evident pathogenic mechanisms and antifungal resistance associated with C. glabrata in ensuring its sustenance and survival

The antibiofilm role of biotics family in vaginal fungal infections

“Unity in strength” is a notion that can be exploited to characterize biofilms as they bestow microbes with protection to live freely, escalate their virulence, confer high resistance to therapeutic agents, and provide active grounds for the production of biofilms after dispersal. Naturally, fungal biofilms are inherently resistant to many conventional antifungals, possibly owing to virulence factors as their ammunitions that persistently express amid planktonic transition to matured biofilm state. These ammunitions include the ability to form polymicrobial biofilms, emergence of persister cells post-antifungal treatment and acquisition of resistance genes. One of the major disorders affecting vaginal health is vulvovaginal candidiasis (VVC) and its reoccurrence is termed recurrent VVC (RVVC). It is caused by the Candida species which include Candida albicans and Candida glabrata. The aforementioned Candida species, notably C. albicans is a biofilm producing pathogen and habitually forms part of the vaginal microbiota of healthy women. Latest research has implicated the role of fungal biofilms in VVC, particularly in the setting of treatment failure and RVVC. Consequently, a plethora of studies have advocated the utilization of probiotics in addressing these infections. Specifically, the excreted or released compounds of probiotics which are also known as postbiotics are being actively researched with vast potential to be used as therapeutic options for the treatment and prevention of VVC and RVVC. These potential sources of postbiotics are harnessed due to their proven antifungal and antibiofilm. Hence, this review discusses the role of Candida biofilm formation in VVC and RVVC. In addition, we discuss the application of pro-, pre-, post-, and synbiotics either individually or in combined regimen to counteract the abovementioned problems. A clear understanding of the role of biofilms in VVC and RVVC will provide proper footing for further research in devising novel remedies for prevention and treatment of vaginal fungal infections