The impact of the Fungus-Host-Microbiota interplay upon Candida albicans infections: current knowledge and new perspectives

Cas5 Regulates the Exposure of β-Glucan, the Cell Surface Hydrophobicity, and the Expression of Cell Wall Proteins to Remodel the Candida albicans Cell Wall and Participates in the Recruitment of Neutrophils

Candida albicans (C. albicans) is a major opportunistic fungal pathogen that causes life-threatening infections, particularly in immunocompromised individuals, underscoring the critical need to understand its pathogenic mechanisms. This study investigates the role of Cas5, a key transcription factor, in regulating C. albicans cell wall remodeling, virulence, and host interactions. Genetic manipulation and biochemical assays were used to examine the effects of Cas5 depletion on C. albicans cell wall structure, adhesion to host cells, morphology transition, innate immune cells recruitment, and pathogenicity in a BALB/C mouse model of oropharyngeal candidiasis (OPC). The results showed that the Cas5 depletion mediated β-glucan exposure and enhanced C. albicans's ability to recruit neutrophils in vivo. Additionally, Cas5-mediated changes in cell surface hydrophobicity (CSH), CWP expressions, and morphological transition promoted C. albicans adhesion to biologically active surfaces (host cells) and increased fungal burden in the mouse model of OPC. In conclusion, Cas5 modulates C. albicans cell wall remodeling by masking cell wall β-glucan, altering CSH, and regulating the expression of cell wall proteins (CWPs). Additionally, Cas5 participates in inhibiting neutrophil recruitment and enhancing the C. albicans adhesion to host cells, as well as facilitating morphological transitions. These actions promote the colonization and invasion of C. albicans in OPC pathogenesis.

The Candida Genome Database: annotation and visualization updates

The Candida Genome Database (CGD; www.candidagenome.org) is unique in being both a model organism database and a fungal pathogen database. As a fungal pathogen database, CGD hosts locus pages for 5 species of the best-studied pathogenic fungi in the Candida group. As a model organism database, the species Candida albicans serves as a model both for other Candida spp. and for non-Candida fungi that form biofilms and undergo routine morphogenic switching from the planktonic form to the filamentous form, which is not done by other model yeasts. As pathogenic Candida species have become increasingly drug resistant, the high lethality of invasive candidiasis in immunocompromised people is increasingly alarming. There is a pressing need for additional research into basic Candida biology, epidemiology and phylogeny, and potential new antifungals. CGD serves the needs of this diverse research community by curating the entire gene-based Candida experimental literature as it is published, extracting, organizing, and standardizing gene annotations. Gene pages were added for the species Candida auris, recent outbreaks of which have been labeled an "urgent" threat. Most recently, we have begun linking clinical data on disease to relevant Literature Topics to improve searchability for clinical researchers. Because CGD curates for multiple species and most research focuses on aspects related to pathogenicity, we focus our curation efforts on assigning Literature Topic tags, collecting detailed mutant phenotype data, and assigning controlled Gene Ontology terms with accompanying evidence codes. Our Summary pages for each feature include the primary name and all aliases for that locus, a description of the gene and/or gene product, detailed ortholog information with links, a JBrowse window with a visual view of the gene on its chromosome, summarized phenotype, Gene Ontology, and sequence information, references cited on the summary page itself, and any locus notes. The database serves as a community hub, where we link to various types of reference material of relevance to Candida researchers, including colleague information, news, and notice of upcoming meetings. We routinely survey the community to learn how the field is evolving and how needs may have changed. For example, we asked our users which species we should next add to CGD, and the clear answer was Candida tropicalis. A key future challenge is management of the flood of high-throughput expression data to make it as useful as possible to as many researchers as possible. The central challenge for any community database is to turn data into knowledge, which the community can access, use, and build upon.

Mycobiome: an underexplored kingdom in cancer

SUMMARYThe human microbiome, including bacteria, fungi, archaea, and viruses, is intimately linked to both health and disease. The relationship between bacteria and disease has received much attention and intensive investigation, while that of the fungal microbiome, also known as mycobiome, has lagged far behind bacteria. There is growing evidence showing mycobiome dysbiosis in cancer patients, and certain cancer-specific fungi may contribute to cancer progression by interacting with both host and bacteria. It was also demonstrated that the role of fungi-derived products in cancer should also not be underestimated. Therefore, investigating how fungal pathogenesis contributes to the onset and spread of cancer would yield crucial information for cancer diagnosis, prevention, and anti-cancer therapy.

Virulence profile of pathogenic yeasts from snakes: Alternative ways for antifungal strategies

Reptiles may act as reservoirs or spreaders of potential pathogenic microorganisms including Candida yeasts. While the epidemiology of yeast species has been thoroughly studied, the virulence profile of isolated species is not well investigated. Therefore, this study aimed to assess the haemolytic, phospholipase, lipase activities and biofilm formation of yeasts isolated from the cloacal swabs of venomous snakes from Marrakech, Morocco (Group I, n = 40) and from non-venomous snakes from Cocullo, Italy (Group II, n = 32). All the isolated yeasts from Group 1 showed low production of lipase (Lz ≥  0.90) and haemolysin (Hz ≥ 0.90), and only 35% of them were low phospholipase (Pz) producers (Pz > 0.90). In contrast, all the yeasts from Group 2 produced enzymes and more than 62% produced high amounts of enzymes (Pz ≤  0.64; Lz ≤  0.69; Hz ≤ 0.69). Data show that yeasts from snakes were able to produce virulence factors, which vary according to the yeast species and the hosts or their origin, thus suggesting the potential role of snakes in harboring and spreading pathogenic yeasts in the environment. Since the virulence profile was lower in venomous snakes than that in non-venomous ones, we discussed that it may be affected by the venom composition. This will pave the way for fungal infection control, alternative to antifungal drugs in order to overcome resistance phenomena.

Oral Microbiota and Inflammatory Bowel Diseases: Detection of Emerging Fungal Pathogens and Herpesvirus

Background/Objectives: Ulcerative colitis (UC) and Crohn's disease (CD) are the usual clinical forms of inflammatory bowel disease (IBD). Changes in the oral microbiota, especially the presence of emerging fungi and herpesviruses, have been shown to worsen the clinical aspects of IBD. The aim of this study was to screen for emerging pathogens in the oral yeast microbiota and the presence of herpesvirus in IBD patients. Methods: Oral swabs of seven UC or CD patients were collected. The samples were plated on Sabouraud Dextrose Agar and subcultured on CHROMagar Candida and CHROMagar Candida Plus. Polyphasic taxonomy was applied and identified using molecular tools, such as MALDI-TOF MS and ITS partial sequencing. Multiplex qPCR was used to identify the herpesvirus. Results: The mean age was 38.67 ± 14.06 years, 57.14% were female, and two had diabetes. The CD patients presented with Rhodotorula mucilaginosa, Candida orthopsilosis and Kodamaea jinghongensis, while the UC patients presented with Cutaneotrichosporon dermatis, Candida glabrata, Candida lusitanea and Candida tropicalis. Two UC individuals had at least one herpesvirus. In the first individual, a co-detection of Herpes Simplex Virus 1 (HSV-1) and C. lusitaniae was observed. The second presented with co-infections of Epstein-Barr virus (EBV), Human Herpesvirus 7 (HHV-7) and C. tropicalis. Conclusions: We identified rarely described yeasts and co-infections in IBD patients, highlighting the need to identify emerging pathogens in the oral microbiota, as they may contribute to opportunistic infections.

Breaking Barriers: Candidalysin Disrupts Epithelial Integrity and Induces Inflammation in a Gut-on-Chip Model

Candida albicans is an opportunistic pathogenic yeast commonly found in the gastrointestinal tract of healthy humans. Under certain conditions, it can become invasive and cause life-threatening systemic infections. One mechanism used by C.albicans to breach the epithelial barrier is the secretion of candidalysin, a cytolytic peptide toxin. Candidalysin damages epithelial membranes and activates the innate immune response, making it key to C.albicans' pathogenicity and a promising therapeutic target. Although candidalysin mediates C. albicans translocation through intestinal layers, its impact on epithelial responses is not fully understood. This study aims to characterize this response and develop scalable, quantitative methodologies to assess candidalysin's toxicological effects using gut-on-chip models. We used the OrganoPlate® platform to expose Caco-2 tubules to candidalysin and evaluated their response with trans-epithelial electrical resistance (TEER), protein detection, and immunostaining. We then validated our findings in a proof-of-concept experiment using human intestinal organoid tubules. Candidalysin impaired barrier integrity, induced actin remodeling, and increased cell permeability. It also induced the release of LDH, cytokines, and the antimicrobial peptide LL37, suggesting cellular damage, inflammation, and antimicrobial activity. This study strengthens our understanding of candidalysin's role in C. albicans pathogenesis and suggests new therapeutic strategies targeting this toxin. Moreover, patient-derived organoids show promise for capturing patient heterogeneity and developing personalized treatments.

Sdd3 regulates the biofilm formation of Candida albicans via the Rho1-PKC-MAPK pathway

Candida albicans, the most frequently isolated fungal pathogen in humans, forms biofilms that enhance resistance to antifungal drugs and host immunity, leading to frequent treatment failure. Understanding the molecular mechanisms governing biofilm formation is crucial for developing anti-biofilm therapies. In this study, we conducted a genetic screen to identify novel genes that regulate biofilm formation in C. albicans. One identified gene is ORF19.6693, a homolog of the Saccharomyces cerevisiae SDD3 gene. The sdd3∆/∆ mutant exhibited severe defects in biofilm formation and significantly reduced chitin content in the cell wall. Overexpression of the constitutively active version of the Rho1 GTPase Rho1G18V, an upstream activator of the protein kinase C (PKC)-mitogen-activated protein kinase (MAPK) cell-wall integrity pathway, rescued these defects. Affinity purification, mass spectrometry, and co-immunoprecipitation revealed Sdd3's physical interaction with Bem2, the GTPase-activating protein of Rho1. Deletion of SDD3 significantly reduced the amount of the active GTP-bound form of Rho1, thereby diminishing PKC-MAPK signaling and downregulating chitin synthase genes CHS2 and CHS8. Taken together, our studies identify a new biofilm regulator, Sdd3, in C. albicans that modulates Rho1 activity through its inhibitory interaction with Bem2, thereby regulating the PKC-MAPK pathway to control chitin biosynthesis, which is critical for biofilm formation. As an upstream component of the pathway and lacking a homolog in mammals, Sdd3 has the potential to serve as an antifungal target for biofilm infections.IMPORTANCEThe human fungal pathogen Candida albicans is categorized as a critical priority pathogen on the World Health Organization's Fungal Priority Pathogens List. A key virulence attribute of this pathogen is its ability to form biofilms on the surfaces of indwelling medical devices. Fungal cells in biofilms are highly resistant to antifungal drugs and host immunity, leading to treatment failure. This study conducted a genetic screen to discover novel genes that regulate biofilm formation. We found that deletion of the SDD3 gene caused severe biofilm defects. Sdd3 negatively regulates the Rho1 GTPase, an upstream activator of the protein kinase C-mitogen-activated protein kinase pathway, through direct interaction with Bem2, the GTPase-activating protein of Rho1, resulting in a significant decrease in chitin content in the fungal cell wall. This chitin synthesis defect leads to biofilm formation failure. Given its essential role in biofilm formation, Sdd3 could serve as an antifungal target for biofilm infections.

Streptococcus dentisani inhibits the growth of Candida albicans and Candida glabrata: in vitro assay

BACKGROUND

Probiotic bacteria inhibit aggregation, biofilm formation, and dimorphism of Candida spp. However, the effects of a new probiotic, Streptococcus dentisani, on the growth of Candida albicans and Candida glabrata biofilms are unknown.

OBJECTIVE

To determine the effect of S. dentisani on the different phases of C. albicans and C. glabrata biofilm development.

METHODS

Growth quantification and ultrastructural analyses were performed on biofilms of C. albicans ATCC 90028, C. glabrata ATCC 2001, and clinical isolates of C. albicans from oral candidiasis (CA-C1), caries (CA-CR1), and periodontal pocket (CA-P1) treated with cell suspensions of S. dentisani CECT 7746. Cell viability was determined by quantifying colony-forming units (CFU/mL). The ultrastructural analyses were done with atomic force microscopy.

RESULTS

S. dentisani induced a significant reduction (p < 0.05) of CFU/mL of immature and mature biofilm in all strains of C. albicans and C. glabrata. Microscopic analysis revealed that S. dentisani reduced C. albicans density in mixed biofilm. The fungus-bacteria interaction affected cell membrane integrity in yeast.

CONCLUSION

For the first time, our data elucidate the antifungal effect of S. dentisani on the development of C. albicans and C. glabrata biofilms, supporting its usefulness as a niche-specific probiotic to prevent and treat oral dysbiosis.

Image-based quantification of Candida albicans filamentation and hyphal length using the open-source visual programming language JIPipe

The formation of hyphae is one of the most crucial virulence traits the human pathogenic fungus Candida albicans possesses. The assessment of hyphal length in response to various stimuli, such as exposure to human serum, provides valuable insights into the adaptation strategies of C. albicans to the host environment. Despite the increasing high-throughput capacity live-cell imaging and data generation, the accurate analysis of hyphal growth has remained a laborious, error-prone, and subjective manual process. We developed an analysis pipeline utilizing the open-source visual programming language Java Image Processing Pipeline (JIPipe) to overcome the limitations associated with manual analysis of hyphal growth. By comparing our automated approach with manual analysis, we refined the strategies to achieve accurate differentiation between yeast cells and hyphae. The automated method enables length measurements of individual hyphae, facilitating a time-efficient, high-throughput, and user-friendly analysis. By utilizing this JIPipe analysis approach, we obtained insights into the filamentation behavior of two C. albicans strains when exposed to human serum albumin (HSA), the most abundant protein in human serum. Our findings indicate that despite the known role of HSA in stimulating fungal growth, it reduces filamentous growth. The implementation of our automated JIPipe analysis approach for hyphal growth represents a long-awaited and time-efficient solution to meet the demand of high-throughput data generation. This tool can benefit different research areas investigating the virulence aspects of C. albicans.

Aloin remodels the cell wall of Candida albicans to reduce its hyphal virulence against oral candidiasis

Aloe vera (L.) Burm.f. is a traditional Chinese medicine known for treating various ailments, including fungal infections. Aloin is one of the major components from A. vera, but its antifungal mechanism and therapeutic potential against oral candidiasis are not clear. This study aimed to examine the mechanism of aloin against Candida albicans and its inhibitory activity against oral candidiasis. In this study, we for the first time found that aloin could induce the formation of abnormal hyphae with smaller hyphal diameters and fewer branching points in C. albicans including 11 clinical isolates without growth inhibition. The transcriptome and further cell wall contents analysis indicated that aloin remodeled the cell wall to increase the contents of β-1,3-glucan and furtherly showed an antagonistic effect with micafungin. Aloin also significantly inhibited the cell damage of oral epithelial cells and oral candidiasis in mice infected by C. albicans due to its inhibitory actions on the hyphal development and expressions of virulence factors, including candidalysin (coded by ECE1). Our results suggest that aloin is a promising antifungal agent for controlling candidiasis and targeting hyphal development and pathogenesis represents a practical strategy for developing new antifungal drugs. KEY POINTS: • Aloin remodels the C. albicans cell wall to form avirulent hyphae. • Aloin inhibits C. albicans infections in oral epithelial cells and mouse mucosa without toxicity. • Aloin is a promising antifungal agent with therapeutic potential against C. albicans infections.

A mouse model of immunosuppression facilitates oral Candida albicans biofilms, bacterial dysbiosis and dissemination of infection

Opportunistic pathogens are a major threat to people, especially those with impaired immune systems. Two of the most important microbes in this category are the fungus Candida albicans and Gram-positive bacteria of the genus Enterococcus, which share overlapping niches in the oral cavity, gastrointestinal and urogenital tracts. The clinical importance of oral C. albicans biofilm and its interaction with the host under immunosuppressive conditions remains largely understudied. Here, we used a mouse model of oropharyngeal candidiasis (OPC) with cortisone acetate injection on alternate days and a continuous supply of C. albicans in drinking water for three days, resulting in immunosuppression. Results showed abundant growth of resident oral bacteria and a strong C. albicans biofilm on the tongue consisting of hyphae which damaged papillae, the epidermal layer, and invaded tongue tissue with the accumulation of inflammatory cells as demonstrated by Grocott's methenamine silver and hematoxylin and eosin staining, respectively. The dispersed microbes from the oral biofilm colonized the gastrointestinal (GI) tract and damaged its integrity, disseminating microbes to other organs. Although no visible damage was observed in the kidney and liver, except increased lipid vacuoles in the liver cells, C. albicans was found in the liver homogenate. Intriguingly, we found co-occurrence of Enterococcus faecalis in the tongue, liver, and stool of immunosuppressed control and C. albicans infected organs. Targeted 16S rRNA and ITS2 amplicon sequencing of microbes from the fecal samples of mice confirmed the above results in the stool samples and revealed an inverse correlation of beneficial microbes in the dysbiosis condition. Our study shows that mucosal-oral infection of C. albicans under immunosuppressed conditions causes tissue damage and invasion in local and distant organs; the invasion may be aided by the overgrowth of the resident endogenous Enterobacteriaceae and other members, including the opportunistic pathogen Enterococcus faecalis.

Dual-antigen fusion protein vaccination induces protective immunity against Candida albicans infection in mice

Candida albicans Is a leading cause of nosocomial bloodstream infections, particularly in immunocompromised patients. Current therapeutic strategies are insufficient, highlighting the need for effective vaccines. This study aimed to evaluate the efficacy of a dual-antigen fusion protein vaccine (AH) targeting the Als3 and Hyr1 proteins of C. albicans, using AlPO4 as an adjuvant. The AH vaccine was constructed by fusing Als317-432 and Hyr125-350 proteins, and its immunogenicity was tested in BALB/c mice and New Zealand white rabbits. Mice received three intramuscular doses of the vaccine combined with AlPO4, followed by a lethal challenge with C. albicans SC5314. Survival rates, antibody responses, cytokine production, fungal burdens, and organ pathology were assessed. The vaccine's efficacy was also validated using rabbit serum. Mice vaccinated with the AH-AlPO4 combination exhibited significantly higher antibody titers, particularly IgG and its subclasses, compared to controls (p < .001). The survival rate of vaccinated mice was 80% post-infection, significantly higher than the control group (p < .01). Vaccinated mice showed reduced fungal loads in the blood, kidneys, spleen, and liver (p < .05). Increased levels of interferon gamma and interleukin (IL)-17A were observed, indicating robust T helper (Th) 1 and Th17 cell responses. Vaccination mitigated organ damage, with kidney and liver pathology scores significantly lower than those of unvaccinated mice (p < .05). Rabbit serum with polyclonal antibodies demonstrated effective antifungal activity, confirming vaccine efficacy across species. The AH-AlPO4 vaccine effectively induced strong immune responses, reduced fungal burden, and protected against organ pathology in C. albicans infections. These findings support further development of dual-antigen vaccine strategies.

Baicalin promotes β-1,3-glucan exposure in Candida albicans and enhances macrophage response

Among the diverse fungal opportunistic pathogens, Candida albicans garners significant attention due to its wide range of infections and high frequency of occurrence. The emergence of resistance and the limited number of antifungals drives the need to develop novel antifungal drugs. Although the natural product baicalin has been shown to trigger apoptosis in C. albicans in previous experiments, its influence on cell wall (CW) structure along with immune recognition remains elusive. In this work, baicalin showed a significant killing effect against C. albicans SC5314. Moreover, CW destruction, characterized by β-1,3-glucan unmasking and chitin deposition, was observed as a consequence of the treatment with baicalin. The RNA sequencing analysis revealed that treatment with baicalin resulted in eight hundred forty-two differentially expressed genes (DEGs). Sixty-five genes, such as GSC1, ENG1, CHS3, GWT1, and MKC1, were associated with CW organization or biogenesis. Baicalin-pretreated C. albicans SC5314 was phagocytosed more efficiently by RAW264.7 macrophages, accompanied by increased TNF-α and IL-1β production. Accordingly, it is hypothesized that baicalin could stimulate β-1,3-glucan unmasking by governing CW-associated gene expression in C. albicans SC5314, which contributes to macrophage recognition and clearance.

β-1,6-Glucan plays a central role in the structure and remodeling of the bilaminate fungal cell wall

The cell wall of human fungal pathogens plays critical roles as an architectural scaffold and as a target and modulator of the host immune response. Although the cell wall of the pathogenic yeast Candida albicans is intensively studied, one of the major fibrillar components in its cell wall, β-1,6-glucan, has been largely neglected. Here, we show that β-1,6-glucan is essential for bilayered cell wall organization, cell wall integrity, and filamentous growth. For the first time, we show that β-1,6-glucan production compensates the defect in mannan elongation in the outer layer of the cell wall. In addition, β-1,6-glucan dynamics are also coordinated by host environmental stimuli and stresses with wall remodeling, where the regulation of β-1,6-glucan structure and chain length is a crucial process. As we point out that β-1,6-glucan is exposed at the yeast surface and modulate immune response, β-1,6-glucan must be considered a key factor in host-pathogen interactions.

Ellagic Acid Potentiates the Inhibitory Effects of Fluconazole Against Candida albicans

Background/Objectives: Antifungal resistance to azoles, coupled with the increasing prevalence of Candida albicans infections, represents a significant public health challenge and has driven the search for new natural compounds that can act as alternatives or adjuvants to the current antifungals. Ellagic acid (EA) has demonstrated antifungal activity; however, its effects are not fully understood. In this study, we investigated the in vitro anti-Candida activity of EA and its ability to potentiate the effects of fluconazole (FLZ) on C. albicans.Methods: The Minimum Inhibitory Concentration (MIC) of EA was determined by broth microdilution and its interaction with FLZ was assessed using a checkerboard assay. Additionally, we examined the effects of EA on yeast-to-hypha transition, inhibition of biofilm formation, time-kill kinetics, hemolytic activity, and cytotoxicity in HeLa ATCC® CCL-2™ cells. Results: EA exhibited MIC values ranging from 250 to 2000 µg/mL and showed synergistic and additive interactions with FLZ, resulting in a marked reduction in the MIC values of FLZ (up to 32-fold) and EA (up to 16-fold). In the time-kill assay, the most effective combinations were 4× EA MIC, 2× EA MIC, and FIC EA + FLZ, which showed fungicidal activity. Furthermore, EA did not show hemolytic activity and demonstrated low and dose-dependent cytotoxicity in HeLa cells, with no cytotoxic effects observed in combination with FLZ. EA and the synergistic combination of EA and FLZ interfered with both the yeast-to-hypha transition process in C. albicans cells and biofilm formation. In addition to its antifungal efficacy, EA demonstrated a favorable safety profile at the concentrations used. Conclusions: This study presents promising results regarding the potential use of EA in combination with FLZ for the treatment of C. albicans infections.

Alpha1-antitrypsin impacts innate host-pathogen interactions with Candida albicans by stimulating fungal filamentation

Our immune system possesses sophisticated mechanisms to cope with invading microorganisms, while pathogens evolve strategies to deal with threats imposed by host immunity. Human plasma protein α1-antitrypsin (AAT) exhibits pleiotropic immune-modulating properties by both preventing immunopathology and improving antimicrobial host defence. Genetic associations suggested a role for AAT in candidemia, the most frequent fungal blood stream infection in intensive care units, yet little is known about how AAT influences interactions between Candida albicans and the immune system. Here, we show that AAT differentially impacts fungal killing by innate phagocytes. We observed that AAT induces fungal transcriptional reprogramming, associated with cell wall remodelling and downregulation of filamentation repressors. At low concentrations, the cell-wall remodelling induced by AAT increased immunogenic β-glucan exposure and consequently improved fungal clearance by monocytes. Contrastingly, higher AAT concentrations led to excessive C. albicans filamentation and thus promoted fungal immune escape from monocytes and macrophages. This underscores that fungal adaptations to the host protein AAT can differentially define the outcome of encounters with innate immune cells, either contributing to improved immune recognition or fungal immune escape.

The oral microbiome and its role in oral squamous cell carcinoma: a systematic review of microbial alterations and potential biomarkers

Background

Oral squamous cell carcinoma (OSCC) is one of the most common cancers worldwide. Despite advances in diagnosis and treatment, the incidence of OSCC is increasing, and the mortality rate remains high. This systematic review aims to examine the potential association between the composition of the oral microbiota and OSCC.

Materials and methods

This study's protocol was developed according to the PRISMA guidelines. Several search engines, including Medline-PubMed, Scopus (via Elsevier), and Google Scholar, were used to identify original studies that analyzed differences in the oral microbiome between OSCC patients and controls. Twenty-seven studies were identified that reported significant differences in microbial abundance between OSCC and controls.

Results

The systematic review highlights a complex relationship between the oral microbiome and the pathogenesis of OSCC. Significant changes in the microbial composition were identified, with a predominance of phyla such as Bacteroidetes and Fusobacteria, which are associated with inflammatory mechanisms facilitating tumor progression. A remarkable variability in microbial profiles emerged based on the different stages of the disease and the types of samples analyzed, demonstrating the complexity of the oral microbial ecosystem.

Conclusion

Although alterations in the oral cavity microbiome composition are evident in patients with OSCC, identifying a specific pattern remains challenging. However, the integration of advanced analytical techniques, such as artificial intelligence, could overcome this problem, allowing the identification of crucial biomarkers and improving the understanding of the role of the microbiome in carcinogenesis. This approach could transform microbiome analysis into a useful tool for screening and monitoring patients with OSCC.

Anti-Candida activity and biocompatibility of silver nanoparticles associated with denture glaze: a new approach to the management of denture stomatitis

The association of silver nanoparticles (AgNps) to sealant agent Palaseal® can be a promising alternative for complete denture wearers who may develop denture stomatitis (DS). The study aimed to evaluate the anti-Candida and biocompatible potential of silver nanoparticles synthesized by three routes associated with denture glaze to prevent and/or treat oral candidiasis. Surface acrylic resin specimens were treated with different associations of glaze with AgNps (VER+AgUV, VER+AgTurk and VER+AgGm). As controls, specimens were treated with glaze+nystatin (VER+Nyst), glaze only (VER) or submerged in PBS (PBS). Afterwards, Candida albicans biofilm was developed for 24 h, 15 d and 30 d. Subsequently, the biofilm was quantified by CFU/mL, XTT assay and confocal laser scanning microscopy. Fibroblasts were submitted to conditioned medium with the same associations for 24, 48 and 72 h and LIVE/DEAD® viability test was carried out. Regardless of the period, there was a significant reduction (p < 0.01) of viable fungal cells load, as well as inhibition of fungal metabolic activity, in specimens treated with glaze+AgNps associations, compared to VER and PBS. The anti-Candida effects of the associations were similar to the VER+Nyst group, with emphasis on VER+AgGm, which showed the highest percentage values of non-viable fungal cells maintained over time. The associations did not prove toxicity to fibroblasts. The AgNps exerted antimicrobial activity against C. albicans biofilms and are biocompatible. The most effective results were achieved with the association of glaze+silver nanoparticles synthesized by the green chemistry method (AgGm), proving to be an innovative alternative in the management of DS.

Combined action of two synthetic ultrashort antimicrobial peptides exhibiting synergistic effects against clinically significant resistant bacteria

Background and Aim

The emergence and proliferation of multidrug-resistant bacteria pose a global health crisis. This issue arises from the overuse and misuse of antibiotics, coupled with the pharmaceutical industry's limited development of new drugs, which is constrained by financial disincentives and regulatory hurdles. This study aimed to investigate the combined antibacterial efficacy and safety profile of the combined ultrashort antimicrobial peptides (AMPs) WW-185 and WOW against antibiotic-resistant bacterial strains.

Materials and Methods

The WW-185 and WOW peptides were synthesized through solid-phase methods and purified using reverse-phase high-performance liquid chromatography, and their purity was confirmed by mass spectrometry. Antibacterial activity was evaluated using broth dilution and checkerboard assays to assess both individual and combined effects of the peptides against Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus [MRSA]) and Escherichia coli (including extended-spectrum beta-lactamases [ESBL]-producing strains). The synergy between the peptides was quantified using fractional inhibitory concentration indices. Hemolytic activity was also assessed to determine cytotoxicity toward red blood cells.

Results

The combination of WW-185 and WOW exerted synergistic effects against both MRSA and ESBL-producing E. coli, with reduced minimal inhibitory concentrations compared with the individual treatments. The peptides exhibited minimal hemolytic activity, indicating low toxicity.

Conclusion

The combination of the ultrashort AMPs WW-185 and WOW shows promising synergistic antibacterial effects against resistant bacteria, with potential for further therapeutic development due to their enhanced efficacy and low toxicity.

Ctr9 promotes virulence of Candida albicans by regulating methionine metabolism

Candida albicans, a part of normal flora, is an opportunistic fungal pathogen and causes severe health issues in immunocompromised patients. Its pathogenicity is intricately linked to the transcriptional regulation of its metabolic pathways. Paf1 complex (Paf1C) is a crucial transcriptional regulator that is highly conserved in eukaryotes. The objective of this study was to explore the role of Paf1C in the metabolic pathways and how it influences the pathogenicity of C. albicans. Paf1C knockout mutant strains of C. albicans (ctr9Δ/Δ, leo1Δ/Δ, and cdc73Δ/Δ) were generated using the CRISPR-Cas9 system. To investigate the effect of Paf1C on pathogenicity, macrophage interaction assays and mouse survival tests were conducted. The growth patterns of the Paf1C knockout mutants were analyzed through spotting assays and growth curve measurements. Transcriptome analysis was conducted under yeast conditions (30°C without serum) and hyphal conditions (37°C with 10% FBS), to further elucidate the role of Paf1C in the pathogenicity of C. albicans. CTR9 deletion resulted in the attenuation of C. albicans virulence, in macrophage and mouse models. Furthermore, we confirmed that the reduced virulence of the ctr9Δ/Δ mutant can be attributed to a decrease in C. albicans cell abundance. Moreover, transcriptome analysis revealed that metabolic processes required for cell proliferation are impaired in ctr9Δ/Δ mutant. Notably, CTR9 deletion led to the downregulation of methionine biosynthetic genes and the cAMP-PKA signaling pathway-related hypha essential genes, which are pivotal for virulence. Our results suggest that Ctr9-regulated methionine metabolism is a crucial factor for determining C. albicans pathogenicity.

Modulation of C. albicans-Induced Immune Response in Vaginal Epithelial Cells by Garcinoic Acid

Vulvovaginal candidiasis (VVC) is a prevalent women's infection characterized by excessive inflammation and damage of the vaginal epithelium that, in its recurrent form (RVVC), causes more than three symptomatic episodes per year, impacting nearly 8% of women globally. Current antifungal treatments alleviate symptoms but often fail to restore the inflammatory homeostasis of mucosal tissue and prevent recurrences. α-Tocopherol (α-TOH) and garcinoic acid (GA), a vitamin E metabolite, with immunomodulatory properties, were investigated for the first time in vaginal epithelial cells exposed to C. albicans infection to assess their effects on inflammatory signaling parameters important to restore cellular homeostasis. For this purpose, the protein kinases MKK3/6, p38 stress kinase (SAPK), and ERK1/2 were studied together with c-Fos transcription factor and IL-6, IL-1α, and IL-1β secretion in A-431 vaginal epithelial cells pre-treated with GA or with α-TOH and then infected with C. albicans. GA, differently from α-TOH, significantly reduced the C. albicans-induced activation of p38-SAPK while increasing pro-survival MAPK ERK1/2 activity. This resulted in a significant reduction in the secretion levels of the inflammatory cytokines IL-6 and IL-1α, as well as IL-1β. Overall, our data indicate that GA holds potential for restoring the immuno-metabolic properties of the vaginal epithelium exposed to C. albicans infection, which may help to treat inflammatory symptoms in VVC/RVVC.

Gut microbiome and NAFLD: impact and therapeutic potential

Non-Alcoholic Fatty Liver Disease (NAFLD) affects approximately 32.4% of the global population and poses a significant health concern. Emerging evidence underscores the pivotal role of the gut microbiota-including bacteria, viruses, fungi, and parasites-in the development and progression of NAFLD. Dysbiosis among gut bacteria alters key biological pathways that contribute to liver fat accumulation and inflammation. The gut virome, comprising bacteriophages and eukaryotic viruses, significantly shapes microbial community dynamics and impacts host metabolism through complex interactions. Similarly, gut fungi maintain a symbiotic relationship with bacteria; the relationship between gut fungi and bacteria is crucial for overall host health, with certain fungal species such as Candida in NAFLD patients showing detrimental associations with metabolic markers and liver function. Additionally, the "hygiene hypothesis" suggests that reduced exposure to gut parasites may affect immune regulation and metabolic processes, potentially influencing conditions like obesity and insulin resistance. This review synthesizes current knowledge on the intricate interactions within the gut microbiota and their associations with NAFLD. We highlight the therapeutic potential of targeting these microbial communities through interventions such as probiotics, prebiotics, and fecal microbiota transplantation. Addressing the complexities of NAFLD requires comprehensive strategies that consider the multifaceted roles of gut microorganisms in disease pathology.

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.

Development of ROS-sensitive capofungin hydrogel by crosslinking chitosan with four-arm polyethylene glycol derivative for treatment of vulvovaginal candidiasis

Both exogenous and endogenous reactive oxygen species (ROS) in vulvovaginal candidiasis (VVC) play pivotal roles in promoting the hyphal formation of Candida albicans (CA), which suggests that clearing ROS could inhibit CA hyphae formation. A ROS-sensitive hydrogel (CAS@4Arm-PB/CS) was formulated by using a novel four-arm polyethylene glycol (4Arm-PEG) derivative (4Arm-PB) as a crosslinking agent, chitosan (CS) as the hydrogel matrix, and caspofungin (CAS) as the antifungal drug against CA. The ROS-sensitivity, disintegration mechanism, crosslinking action, swelling degree, microstructure, modulus, and rheological properties of 4Arm-PB were characterized. According to the results, 5.0 % 4Arm-PB could quickly and efficiently cross-link 0.5 mg/mL of CS. The ROS-sensitivity of 4Arm-PB was 10-50 μM, indicating a strong ROS sensitivity. The in vitro and in vivo anti-CA results indicated that CAS@4Arm-PB/CS not only cleared endogenous and exogenous ROS and inhibited the formation of CA hyphae and biofilm but also contributed beneficially to the treatment of VVC mice caused by CA infection, implying a certain safety aspect and an in vivo applicability. This research introduces a novel functional crosslinking agent for CS hydrogel formulation, presenting a new avenue for hydrogel-based drug delivery systems and therapeutic strategies for VVC treatment.

Oral Microbial Changes in Oral Squamous Cell Carcinoma: Focus on Treponema denticola, Lactobacillus casei, and Candida albicans

Background and Objectives: In this study, we aimed to explore the oral bacteria and fungi that can help discern oral squamous cell carcinoma (OSCC) and investigate the correlations between multiple key pathogens. Materials and Methods: Twelve participants (8 females and 4 males; mean age, 54.33 ± 20.65 years) were prospectively recruited into three groups: Group 1: healthy control, Group 2: patients with stomatitis, and Group 3: patients with OSCC, with 4 individuals in each group. Unstimulated whole saliva samples from these participants were analyzed using real-time PCR to assess the presence and abundance of 14 major oral bacterial species and Candida albicans. Results: The analysis revealed significant differences for certain microorganisms, namely, Treponema denticola (T. denticola), Lactobacillus casei (L. casei), and Candida albicans. T. denticola was most abundant in the OSCC group (5,358,692.95 ± 3,540,767.33), compared to the stomatitis (123,355.54 ± 197,490.86) and healthy control (9999.21 ± 11,998.40) groups. L. casei was undetectable in the healthy control group but was significantly more abundant in the stomatitis group (1653.94 ± 2981.98) and even higher in the OSCC group (21,336.95 ± 9258.79) (p = 0.001). A similar trend was observed for C. albicans, with DNA copy numbers rising from the healthy control (464.29 ± 716.76) to the stomatitis (1861.30 ± 1206.15) to the OSCC group (9347.98 ± 5128.54) (p = 0.006). The amount of T. denticola was positively correlated with L. casei (r = 0.890, p < 0.001) and C. albicans (r = 0.724, p = 0.008). L. casei's DNA copy number was strongly correlated with C. albicans (r = 0.931, p < 0.001). These three oral microbes exhibited strong positive correlations with each other and had various direct or indirect relationships with other species. Conclusions: In the OSCC group, T. denticola, L. casei, and C. albicans exhibited strong positive correlations with one another, further emphasizing the need for a deeper understanding of the complex microbial interactions in the OSCC environment.

Antifungal potential of marine bacterial compounds in inhibiting Candida albicans Yck2 to overcome echinocandin resistance: a molecular dynamics study

Candida albicans (C. albicans), a common fungal pathogen, poses a significant threat to immunocompromised individuals, particularly due to the emergence of resistance against echinocandins, a primary class of antifungal agents. Yck2 protein, a key regulator of cell wall integrity and signaling pathways in C. albicans, was targeted to overcome this resistance. A virtual screening was used to identify Yck2 inhibitors from marine bacterial compounds. Further re-docking, molecular dynamics simulations, and various analyses such as root mean square deviation (RMSD), root mean square fluctuation (RMSF), hydrogen bonding, free binding energy calculations, and RG-RMSD-based free energy landscape were conducted to evaluate the efficacy and stability of the identified compounds. Among the compounds screened, CMNPD27166 and CMNPD27283 emerged as the most promising candidates, demonstrating superior binding affinities, enhanced stability, and favorable interaction dynamics with Yck2, surpassing both the control and other compounds in efficacy. In contrast, CMNPD19660 and CMNPD24402, while effective, showed lesser potential. These findings highlight the utility of computational drug discovery techniques in identifying and optimizing potential therapeutic agents and suggest that marine-derived molecules could significantly impact the development of novel antifungal therapies. Further experimental validation of the leading candidates, CMNPD27166 and CMNPD27283, is recommended to confirm their potential as effective antifungal agents against echinocandin-resistant C. albicans infections.

Intestinal fungal-host interactions in promoting and maintaining health

The resident microbiota are a key component of a healthy organism. The vast majority of microbiome studies have focused on bacterial members, which constitute a significant portion of resident microbial biomass. Recent studies have demonstrated how the fungal component of the microbiota, or the mycobiome, influences mammalian biology despite its low abundance compared to other microbes. Fungi are known for their pathogenic potential, yet fungi are also prominent colonizers in healthy states, highlighting their duality. We summarize the characteristics that define the gut mycobiome across life, the factors that can impact its composition, and studies that identify mechanisms of how fungi confer health benefits. The goal of this review is to synthesize our knowledge regarding the composition and function of a healthy mycobiome with a view to inspiring future therapeutic advances.

Navigating the fungal battlefield: cysteine-rich antifungal proteins and peptides from Eurotiales

Fungi are ubiquitous in the environment and play a key role in the decomposition and recycling of nutrients. On the one hand, their special properties are a great asset for the agricultural and industrial sector, as they are used as source of nutrients, producers of enzymes, pigments, flavorings, and biocontrol agents, and in food processing, bio-remediation and plant growth promotion. On the other hand, they pose a serious challenge to our lives and the environment, as they are responsible for fungal infections in plants, animals and humans. Although host immunity opposes invading pathogens, certain factors favor the manifestation of fungal diseases. The prevalence of fungal infections is on the rise, and there is an alarming increase in the resistance of fungal pathogens to approved drugs. The limited number of antimycotics, the obstacles encountered in the development of new drugs due to the poor tolerability of antifungal agents in patients, the limited number of unique antifungal targets, and the low species specificity contribute to the gradual depletion of the antifungal pipeline and newly discovered antifungal drugs are rare. Promising candidates as next-generation therapeutics are antimicrobial proteins and peptides (AMPs) produced by numerous prokaryotic and eukaryotic organisms belonging to all kingdom classes. Importantly, filamentous fungi from the order Eurotiales have been shown to be a rich source of AMPs with specific antifungal activity. A growing number of published studies reflects the efforts made in the search for new antifungal proteins and peptides (AFPs), their efficacy, species specificity and applicability. In this review, we discuss important aspects related to fungi, their impact on our life and issues involved in treating fungal infections in plants, animals and humans. We specifically highlight the potential of AFPs from Eurotiales as promising alternative antifungal therapeutics. This article provides insight into the structural features, mode of action, and progress made toward their potential application in a clinical and agricultural setting. It also identifies the challenges that must be overcome in order to develop AFPs into therapeutics.

Role of ERG11 and MDR1 genes in cycloheximide and multidrug resistance in Candida species

Candida species are amongst the commensals of the mucosal surfaces of the human body which include the oral cavity, vagina, and intestinal mucosa. Fungal infections are on the rise worldwide. The overall burden of infections due to fungi is difficult to estimate because the majority of them remain undiagnosed. The present study aims to determine the burden of antifungal resistance in low socioeconomic country, Pakistan and the frequency of ERG11 and MDR1 genes involved. A total of 636 Candida isolates were obtained from various tertiary care institutions in Lahore in the form of culture on various culture plates. Sabouraud agar culture plates were used to culture the Candida spp. Antifungal resistance was determined against Fluconazole, Itraconazole, Ketoconazole, and Nystatin via disk diffusion technique. Most resistance was observed against Fluconazole followed by Itraconazole, Ketoconazole, and Nystatin. The Candida isolates recovering from CVP tip and tissue have a high resistance profile. Candida species resistant to at least two antifungals were chosen for further ERG11 and MDR1 detection through real-time PCR. Among 255 Candida isolates, 240 contained ERG11 gene while MDR1 gene is present in 149 Candida isolates. The isolates carrying both genes were tested by the broth microdilution technique for the susceptibility against cycloheximide, all of them were able to grow in cycloheximide. The genetic determinants of antifungal resistance such as ERG11 and MDR1 are as important in the multidrug resistance against a variety of compounds and antifungal drugs.

Bacillus species are core microbiota of resistant maize cultivars that induce host metabolic defense against corn stalk rot

BACKGROUND

Microbes colonizing each compartment of terrestrial plants are indispensable for maintaining crop health. Although corn stalk rot (CSR) is a severe disease affecting maize (Zea mays) worldwide, the mechanisms underlying host-microbe interactions across vertical compartments in maize plants, which exhibit heterogeneous CSR-resistance, remain largely uncharacterized.

RESULTS

Here, we investigated the microbial communities associated with CSR-resistant and CSR-susceptible maize cultivars using multi-omics analysis coupled with experimental verification. Maize cultivars resistant to CSR reshaped the microbiota and recruited Bacillus species with three phenotypes against Fusarium graminearum including niche pre-emption, potential secretion of antimicrobial compounds, and no inhibition to alleviate pathogen stress. By inducing the expression of Tyrosine decarboxylase 1 (TYDC1), encoding an enzyme that catalyzes the production of tyramine and dopamine, Bacillus isolates that do not directly suppress pathogen infection induced the synthesis of berberine, an isoquinoline alkaloid that inhibits pathogen growth. These beneficial bacteria were recruited from the rhizosphere and transferred to the stems but not grains of the CSR-resistant plants.

CONCLUSIONS

The current study offers insight into how maize plants respond to and interact with their microbiome and lays the foundation for preventing and treating soil-borne pathogens. Video Abstract.

Candida species-specific colonization in the healthy and impaired human gastrointestinal tract as simulated using the Mucosal Ileum-SHIME® model

Candida species primarily exist as harmless commensals in the gastrointestinal tract of warm-blooded animals. However, they can also cause life-threatening infections, which are often associated with gut microbial dysbiosis. Identifying the microbial actors that restrict Candida to commensalism remains a significant challenge. In vitro models could enable a mechanistic study of the interactions between Candida and simulated colon microbiomes. Therefore, this study aimed to elucidate the spatial and temporal colonization kinetics of specific Candida, including C. albicans, C. tropicalis, and C. parapsilosis, and their relative Nakaseomyces glabratus, by using an adapted SHIME® model, simulating the ileum, and proximal and distal colons. We monitored fungal and bacterial colonization kinetics under conditions of eubiosis (commensal lifestyle) and antibiotic-induced dysbiosis (pathogenic lifestyle). Our findings highlighted the variability in the colonization potential of Candida species across different intestinal regions. The ileum compartment proved to be the most favourable environment for C. albicans and C. parapsilosis under conditions of eubiosis. Antibiotic-induced dysbiosis resulted in resurgence of opportunistic Candida species, especially C. tropicalis and C. albicans. Future research should focus on identifying specific bacterial species influencing Candida colonization resistance and explore the long-term effects of antibiotics on the mycobiome and bacteriome.

Commensal Yeast Promotes Salmonella Typhimurium Virulence

Enteric pathogens engage in complex interactions with the host and the resident microbiota to establish gut colonization. Although mechanistic interactions between enteric pathogens and bacterial commensals have been extensively studied, whether and how commensal fungi affect pathogenesis of enteric infections remains largely unknown. Here we show that colonization with the common human gut commensal fungus Candida albicans worsened infections with the enteric pathogen Salmonella enterica serovar Typhimurium. Presence of C. albicans in the mouse gut increased Salmonella cecum colonization and systemic dissemination. We investigated the underlying mechanism and found that Salmonella binds to C. albicans via Type 1 fimbriae and uses its Type 3 Secretion System (T3SS) to deliver effector proteins into C. albicans . A specific effector, SopB, was sufficient to manipulate C. albicans metabolism, triggering increased arginine biosynthesis in C. albicans and the release of millimolar amounts of arginine into the extracellular environment. The released arginine, in turn, induced T3SS expression in Salmonella , increasing its invasion of epithelial cells. C. albicans deficient in arginine production was unable to increase Salmonella virulence in vitro or in vivo . In addition to modulating pathogen invasion, arginine also directly influenced the host response to infection. Arginine-producing C. albicans dampened the inflammatory response during Salmonella infection, whereas C. albicans deficient in arginine production did not. Arginine supplementation in the absence of C. albicans increased the systemic spread of Salmonella and decreased the inflammatory response, phenocopying the presence of C. albicans . In summary, we identified C. albicans colonization as a susceptibility factor for disseminated Salmonella infection, and arginine as a central metabolite in the cross-kingdom interaction between fungi, bacteria, and host.

Antibacterial and Antifungal Potential of Helichrysum italicum (Roth) G. Don Essential Oil

Helichrysum italicum (Roth) G. Don is a typical Mediterranean plant, with limited distribution on the islands of Sardinia, Corsica, and the Iberian Peninsula, as well as the islands of the Adriatic Sea and the Balkan Peninsula. In these regions, H. italicum is mainly collected from spontaneous nature, while in recent years, there has been a pronounced cultivation trend due to increased demand and market requirements for constant quality of raw materials. Bearing in mind that biological activity is linked with chemical composition, this review aimed to collect data from different scientific databases (Scopus, PubMed, Web of Science, and Google Scholar) on the antimicrobial activity of essential oil and its chemical composition. A total of 20 papers investigating the antibacterial, antibiofilm, and antifungal activities of H. italicum essential oil were found. Furthermore, in these samples, several compounds occurred as dominant: neryl acetate, α-pinene, and γ-curcumene. These compounds are known for their antimicrobial properties, which likely contribute to the essential oil's efficacy against various microbial strains.

Candida albicans natural diversity: a resource to dissect fungal commensalism and pathogenesis

Candida albicans is a ubiquitous fungus of humans. It is not only a component of the oral and intestinal microbiota of most healthy adults but also a major cause of mucosal disorders and life-threatening disseminated infections. Until recently, research on the biology and pathogenesis of the fungus was largely based on a single clinical isolate. We review investigations that have started to dissect a diverse set of C. albicans strains. Using different approaches to leverage the species' phenotypic and/or genetic diversity, these studies illuminate the wide range of interactions between fungus and host. While connecting genetic variants to phenotypes of interest remains challenging, research on C. albicans' natural diversity is central to understand fungal commensalism and pathogenesis.

Oral Candida albicans strain diversity and maintenance in HIV positive women in South Africa

OBJECTIVE

This study investigated C. albicans strain diversity and maintenance in the oral cavity of HIV positive women over a 6 month period.

STUDY DESIGN

C. albicans strains were isolated from 17 HIV positive women at Charlotte Maxeke Academic Hospital, Johannesburg at 3 intervals over a 6 month period. Strains were genotyped using ABC and Multilocus Sequence Typing (MLST) techniques. In the MLST technique, for each strain, a Diploid Sequence Type (DST) number was obtained. Using cluster analysis, an Unweighted Pair Group Method with Arithmetic Mean (UPGMA) dendrogram and a matrix of strain similarities were generated. Strains were also compared to the previous South African isolates documented in the MLST database.

RESULTS

Ninety four percent of women carried the same ABC genotype for 6 months. MLST technique, showed that ten women (58.8%) carried the same DST at 2 visits, while seven (41.2%) carried different DST at all visits. Further analysis showed that 64.7% of women were recolonised with different strains and 35.3% carried the same strains of C. albicans with heterozygosity. A total of 40 diploid sequence types were identified of which 27 DSTs were unique to this study group that were added to the MLST database. Most of the strains were closely related to previously isolated strains from South Africa.

CONCLUSION

Recolonization of the oral cavity with different strains and microevolution of the original strains of C. albicans can occur, which can be a potential problem for HIV patients, in whom highly virulent and drug resistant strains can emerge.

Cross interaction between bacterial and fungal microbiota and their relevance to human health and disease: mechanistic pathways and prospective therapy

Diverse bacterial and fungal microbiota communities inhabit the human body, and their presence is essential for maintaining host homeostasis. The oral cavity, lung, gut, and vagina are just a few of the bodily cavities where these microorganisms communicate with one another, either directly or indirectly. The effects of this interaction can be either useful or detrimental to the host. When the healthy microbial diversity is disturbed, for instance, as a result of prolonged treatment with broad spectrum antibiotics, this allows the growth of specific microbes at the expense of others and alters their pathogenicity, causing a switch of commensal germs into pathogenic germs, which could promote tissue invasion and damage, as occurs in immunocompromised patients. Consequently, antimicrobials that specifically target pathogens may help in minimizing secondary issues that result from the disruption of useful bacterial/fungal interactions (BFIs). The interface between Candida albicans and Aspergillus fumigatus with bacteria at various body sites is emphasized in the majority of the medically important BFIs that have been reported thus far. This interface either supports or inhibits growth, or it enhances or blocks the generation of virulence factors. The aim of this review is to draw attention to the link between the bacterial and fungal microbiota and how they contribute to both normal homeostasis and disease development. Additionally, recent research that has studied microbiota as novel antimicrobials is summarized.

Monoterpene antifungal activities: evaluating geraniol, citronellal, and linalool on Candida biofilm, host inflammatory responses, and structure-activity relationships

Introduction: Despite the rising concern with fungal resistance, a myriad of molecules has yet to be explored. Geraniol, linalool, and citronellal are monoterpenes with the same molecular formula (C10H18O), however, neither the effect of these compounds on inflammatory axis induced by Candida spp. nor the antibiofilm Structure-Activity Relationship (SAR) have been well-investigated. Herein we analyzed geraniol, linalool and citronellal antifungal activity, cytotoxicity, and distinctive antibiofilm SAR, also the influence of geraniol on Candida spp induced dysregulated inflammatory axis, and in vivo toxicity. Methods: Minimal inhibitory (MIC) and fungicidal (MFC) concentrations against Candida spp were defined, followed by antibiofilm activity (CFU-colony forming unit/mL/g of dry weight). Cytotoxic activity was assessed using human monocytes (THP-1) and oral squamous cell (TR146). Geraniol was selected for further analysis based on antifungal, antibiofilm and cytotoxic results. Geraniol was tested using a dual-chamber co-culture model with TR146 cells infected with C. albicans, and THP-1 cells, used to mimic oral epithelium upon fungal infection. Expression of Candida enzymes (phospholipase-PLB and aspartyl proteases-SAP) and host inflammatory cytokines (interleukins: IL-1β, IL-6, IL-17, IL-18, IL-10, and Tumor necrosis factor-TNF) were analyzed. Lastly, geraniol in vivo toxicity was assessed using Galleria mellonella. Results: MIC values obtained were 1.25-5 mM/mL for geraniol, 25-100 mM/mL for linalool, and 100-200 mM/mL for citronellal. Geraniol 5 and 50 mM/mL reduced yeast viability during biofilm analysis, only 500 mM/mL of linalool was effective against a 72 h biofilm and no biofilm activity was seen for citronellal. LD50 for TR146 and THP-1 were, respectively: geraniol 5.883 and 8.027 mM/mL; linalool 1.432 and 1.709 mM/mL; and citronellal 0.3006 and 0.1825 mM/mL. Geraniol was able to downregulate expression of fungal enzymes and host pro-inflammatory cytokines IL-1β, IL-6, and IL-18. Finally, safety in vivo parameters were observed up to 20 mM/Kg. Discussion: Despite chemical similarities, geraniol presented better antifungal, antibiofilm activity, and lower cytotoxicity when compared to the other monoterpenes. It also showed low in vivo toxicity and capacity to downregulate the expression of fungal enzymes and host pro-inflammatory cytokines. Thus, it can be highlighted as a viable option for oral candidiasis treatment.

A Nutrigenomic View on the Premature-Aging Disease Fanconi Anemia

Fanconi anemia, a rare disorder with an incidence of 1 in 300,000, is caused by mutations in FANC genes, which affect the repair of DNA interstrand crosslinks. The disease is characterized by congenital malformations, bone marrow failure within the first decade of life, and recurrent squamous cell carcinomas of the oral cavity, esophagus, and anogenital regions starting around age 20. In this review, we propose that Fanconi anemia should be considered a premature-aging syndrome. Interestingly, the onset and severity of the life-limiting clinical features of Fanconi anemia can be influenced by lifestyle choices, such as a healthy diet and physical activity. These factors shape the epigenetic status of at-risk cell types and enhance the competence of the immune system through nutritional signaling. Fanconi anemia may serve as a model for understanding the aging process in the general population, addressing research gaps in its clinical presentation and suggesting prevention strategies. Additionally, we will discuss how the balance of genetic and environmental risk factors-affecting both cancer onset and the speed of aging-is interlinked with signal transduction by dietary molecules. The underlying nutrigenomic principles will offer guidance for healthy aging in individuals with Fanconi anemia as well as for the general population.

Anadenanthera colubrina regulated LPS-induced inflammation by suppressing NF-κB and p38-MAPK signaling pathways

We aimed to determine the chemical profile and unveil Anadenanthera colubrina (Vell.) Brenan standardized extract effects on inflammatory cytokines expression and key proteins from immunoregulating signaling pathways on LPS-induced THP-1 monocyte. Using the RT-PCR and Luminex Assays, we planned to show the gene expression and the levels of IL-8, IL-1β, and IL-10 inflammatory cytokines. Key proteins of NF-κB and MAPK transduction signaling pathways (NF-κB, p-38, p-NF-κB, and p-p38) were detected by Simple Western. Using HPLC-ESI-MSn (High-Performance Liquid-Chromatography) and HPLC-HRESIMS, we showed the profile of the extract that includes an opus of flavonoids, including the catechins, quercetin, kaempferol, and the proanthocyanidins. Cell viability was unaffected up to 250 µg/mL of the extract (LD50 = 978.7 µg/mL). Thereafter, the extract's impact on the cytokine became clear. Upon LPS stimuli, in the presence of the extract, gene expression of IL-1β and IL-10 were downregulated and the cytokines expression of IL-1β and IL-10 were down an upregulated respectively. The extract is involved in TLR-4-related NF-κB/MAPK pathways; it ignited phosphorylation of p38 and NF-κB, orchestrating a reduced signal intensity. Therefore, Anadenanthera colubrina's showed low cytotoxicity and profound influence as a protector against the inflammation, modulating IL-1β and IL-10 inflammatory cytokines gene expression and secretion by regulating intracellular NF-κB and p38-MAPK signaling pathways.

Oral Microbiota Alterations in Subjects with SARS-CoV-2 Displaying Prevalence of the Opportunistic Fungal Pathogen Candida albicans

The oral cavity remains an underappreciated site for SARS-CoV-2 infection despite the myriad of oral conditions in COVID-19 patients. Recently, SARS-CoV-2 was shown to replicate in the salivary gland cells causing tissue inflammation. Given the established association between inflammation and microbiome disruption, we comparatively profiled oral microbial differences at a metagenomic level in a cohort of hospitalized COVID-19 patients and matched healthy controls. Specifically, we aimed to evaluate colonization by the opportunistic fungal pathogen Candida albicans, the etiologic agent of oral candidiasis. Comprehensive shotgun metagenomic analysis indicated that, overall, COVID-19 patients exhibited significantly reduced bacterial and viral diversity/richness; we identified 12 differentially abundant bacterial species to be negatively associated with COVID-19, and the functional pathways of certain bacteria to be highly associated with COVID-19 status. Strikingly, C. albicans was recovered from approximately half of the COVID-19 subjects but not from any of the healthy controls. The prevalence of Candida is likely linked to immune hypo-dysregulation caused by COVID-19 favoring Candida proliferation, warranting investigations into the interplay between Candida and SARS-CoV2 and potential therapeutic approaches directed toward oral candidiasis. Collectively, our findings prompt a reassessment of oral opportunistic infection risks during COVID-19 disease and their potential long-term impacts on oral health.

Mucocutaneous Candidiasis: Insights Into the Diagnosis and Treatment

Recent progress in the methods of genetic diagnosis of inborn errors of immunity has contributed to a better understanding of the pathogenesis of chronic mucocutaneous candidiasis (CMC) and potential therapeutic options. This review describes the latest advances in the understanding of the pathophysiology, diagnostic strategies, and management of chronic mucocutaneous candidiasis.

Oral Candida in post-radiotherapy patients with xerostomia/hyposalivation: A narrative review

OBJECTIVE

Head and Neck Cancer (HNC) patients receiving radiotherapy (RT) often suffer from xerostomia and/or hyposalivation. As saliva plays an important antimicrobial and cleansing roles, these patients are at higher risks of opportunistic infections. This narrative review aims to provide an overview of current evidence on oral Candida colonisation and infection in these patients.

METHODS

A literature review of clinical studies on oral Candida colonisation and candidiasis in HNC patients receiving radiotherapy/chemoradiotherapy was conducted.

RESULTS

Many clinical studies found high levels of Candida colonisation and a substantial proportion of post-RT HNC patients suffering from oropharyngeal candidiasis (OPC). Importantly, oral Candida could be a reservoir for life-threatening systemic infection in immunocompromised patients. The rising prevalence of non-albicans Candida species and drug-resistant infections has made identification of Candida species and antifungal susceptibility more important. Recent advances in oral microbiome and its interactions with Candida are discussed. This review also offers perspectives on limitations of current evidence and suggestions for future research.

CONCLUSION

Further research to better understand Candida carriage, microbiome, OPC, and xerostomia/hyposalivation post-RT would aid in devising a more comprehensive long-term management plan and novel therapeutic approaches for HNC patients to achieve the full benefits of RT while minimising side effects.

Saps1-3 Antigens in Candida albicans: Differential Modulation Following Exposure to Soluble Proteins, Mammalian Cells, and Infection in Mice

The secreted aspartic peptidases (Saps) of Candida albicans play crucial roles in various steps of fungal-host interactions. Using a flow cytometry approach, this study investigated the expression of Saps1-3 antigens after (i) incubation with soluble proteins, (ii) interaction with mammalian cells, and (iii) infection in immunosuppressed BALB/c mice. Supplementation strategies involving increasing concentrations of bovine serum albumin (BSA) added to yeast carbon base (YCB) medium as the sole nitrogenous source revealed a positive and significant correlation between BSA concentration and both the growth rate and the percentage of fluorescent cells (%FC) labeled with anti-Saps1-3 antibodies. Supplementing the YCB medium with various soluble proteins significantly modulated the expression of Saps1-3 antigens in C. albicans. Specifically, immunoglobulin G, gelatin, and total bovine/human sera significantly reduced the %FC, while laminin, human serum albumin, fibrinogen, hemoglobin, and mucin considerably increased the %FC compared to BSA. Furthermore, co-cultivating C. albicans yeasts with either live epithelial or macrophage cells induced the expression of Saps1-3 antigens in 78% (mean fluorescence intensity [MFI] = 152.1) and 82.7% (MFI = 178.2) of the yeast cells, respectively, compared to BSA, which resulted in 29.3% fluorescent cells (MFI = 50.9). Lastly, the yeasts recovered from the kidneys of infected immunosuppressed mice demonstrated a 4.8-fold increase in the production of Saps1-3 antigens (MFI = 246.6) compared to BSA, with 95.5% of yeasts labeled with anti-Saps1-3 antibodies. Altogether, these results demonstrated the positive modulation of Saps' expression in C. albicans by various key host proteinaceous components, as well as by in vitro and in vivo host challenges.

Candida albicans and Candida glabrata: global priority pathogens

SUMMARYA significant increase in the incidence of Candida-mediated infections has been observed in the last decade, mainly due to rising numbers of susceptible individuals. Recently, the World Health Organization published its first fungal pathogen priority list, with Candida species listed in medium, high, and critical priority categories. This review is a synthesis of information and recent advances in our understanding of two of these species-Candida albicans and Candida glabrata. Of these, C. albicans is the most common cause of candidemia around the world and is categorized as a critical priority pathogen. C. glabrata is considered a high-priority pathogen and has become an increasingly important cause of candidemia in recent years. It is now the second most common causative agent of candidemia in many geographical regions. Despite their differences and phylogenetic divergence, they are successful as pathogens and commensals of humans. Both species can cause a broad variety of infections, ranging from superficial to potentially lethal systemic infections. While they share similarities in certain infection strategies, including tissue adhesion and invasion, they differ significantly in key aspects of their biology, interaction with immune cells, host damage strategies, and metabolic adaptations. Here we provide insights on key aspects of their biology, epidemiology, commensal and pathogenic lifestyles, interactions with the immune system, and antifungal resistance.

Macrophage-derived CD36 + exosome subpopulations as novel biomarkers of Candida albicans infection

Invasive candidiasis (IC) is a notable healthcare-associated fungal infection, characterized by high morbidity, mortality, and substantial treatment costs. Candida albicans emerges as a principal pathogen in this context. Recent academic advancements have shed light on the critical role of exosomes in key biological processes, such as immune responses and antigen presentation. This burgeoning body of research underscores the potential of exosomes in the realm of medical diagnostics and therapeutics, particularly in relation to fungal infections like IC. The exploration of exosomal functions in the pathophysiology of IC not only enhances our understanding of the disease but also opens new avenues for innovative therapeutic interventions. In this investigation, we focus on exosomes (Exos) secreted by macrophages, both uninfected and those infected with C. albicans. Our objective is to extract and analyze these exosomes, delving into the nuances of their protein compositions and subgroups. To achieve this, we employ an innovative technique known as Proximity Barcoding Assay (PBA). This methodology is pivotal in our quest to identify novel biological targets, which could significantly enhance the diagnostic and therapeutic approaches for C. albicans infection. The comparative analysis of exosomal contents from these two distinct cellular states promises to yield insightful data, potentially leading to breakthroughs in understanding and treating this invasive fungal infection. In our study, we analyzed differentially expressed proteins in exosomes from macrophages and C. albicans -infected macrophages, focusing on proteins such as ACE2, CD36, CAV1, LAMP2, CD27, and MPO. We also examined exosome subpopulations, finding a dominant expression of MPO in the most prevalent subgroup, and a distinct expression of CD36 in cluster14. These findings are crucial for understanding the host response to C. albicans and may inform targeted diagnostic and therapeutic approaches. Our study leads us to infer that MPO and CD36 proteins may play roles in the immune escape mechanisms of C. albicans. Additionally, the CD36 exosome subpopulations, identified through our analysis, could serve as potential biomarkers and therapeutic targets for C. albicans infection. This insight opens new avenues for understanding the infection's pathology and developing targeted treatments.

Microfluidic Electrochemical Integrated Sensor for Efficient and Sensitive Detection of Candida albicans

Traditional methods for the detection of pathogenic bacteria are time-consuming, less efficient, and sensitive, which affects infection control and bungles illness. Therefore, developing a method to remedy these problems is very important in the clinic to diagnose the pathogenic diseases and guide the rational use of antibiotics. Here, microfluidic electrochemical integrated sensor (MEIS) has been investigated, functionally for rapid, efficient separation and sensitive detection of pathogenic bacteria. Three-dimensional macroporous PDMS and Au nanotube-based electrode are successfully assembled into the modeling microchip, playing the functions of "3D chaotic flow separator" and "electrochemical detector," respectively. The 3D chaotic flow separator enhances the turbulence of the fluid, achieving an excellent bacteria capture efficiency. Meanwhile, the electrochemical detector provides a quantitative signal through enzyme-linked immunoelectrochemistry with improved sensitivity. The microfluidic electrochemical integrated sensor could successfully isolate Candida albicans (C. albicans) in the range of 30-3,000,000 CFU in the saliva matrix with over 95% capture efficiency and sensitively detect C. albicans in 1 h in oral saliva samples. The integrated device demonstrates great potential in the diagnosis of oral candidiasis and is also applicable in the detection of other pathogenic bacteria.

Mechanistic Insights into Cellular and Molecular Targets of Zinc Oxide Quantum Dots (ZnO QDs) in Fungal Pathogen, Candida albicans: One Drug Multi-Targeted Therapeutic Approach

Rationally designed multitargeted drugs, known as network therapeutics/multimodal drugs, have emerged as versatile therapeutic solutions to combat drug-resistant microbes. Here, we report novel mechanistic insights into cellular and molecular targets of ZnO quantum dots (QDs) against Candida albicans, a representative of fungal pathogens. Stable, monodispersed 4-6 nm ZnO QDs were synthesized using a wet chemical route, which exhibited dose-dependent inhibition on the growth dynamics of Candida. Treatment with 200 μg/mL ZnO QDs revealed an aberrant morphology and a disrupted cellular ultrastructure in electron microscopy and led to a 23% reduction in ergosterol content and a 53% increase in intracellular reactive oxygen species. Significant increase in steady-state fluorescence polarization and fluorescence lifetime decay of membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH) in treated cells, respectively, implied reduction in membrane fluidity and enhanced microviscosity. The observed reduction in passive diffusion of fluorescent Rhodamine 6G across the membrane validated the intricate relationship between ergosterol, membrane fluidity, and microviscosity. An inverse relationship existing between ergosterol biosynthetic genes, ERG11 and ERG3 in treated cells, related well with displayed higher susceptibilities. Furthermore, treated cells exhibited impaired functionality and downregulation of ABC drug efflux pumps. Multiple cellular targets of ZnO QDs in Candida were validated by in silico molecular docking. Thus, targeting ERG11, ERG3, and ABC drug efflux pumps might emerge as a versatile, nano-ZnO-based strategy in fungal therapeutics to address the challenges of drug resistance.

Clostridioides difficile infection: history, epidemiology, risk factors, prevention, clinical manifestations, treatment, and future options

SUMMARYClostridioides difficile infection (CDI) is one of the major issues in nosocomial infections. This bacterium is constantly evolving and poses complex challenges for clinicians, often encountered in real-life scenarios. In the face of CDI, we are increasingly equipped with new therapeutic strategies, such as monoclonal antibodies and live biotherapeutic products, which need to be thoroughly understood to fully harness their benefits. Moreover, interesting options are currently under study for the future, including bacteriophages, vaccines, and antibiotic inhibitors. Surveillance and prevention strategies continue to play a pivotal role in limiting the spread of the infection. In this review, we aim to provide the reader with a comprehensive overview of epidemiological aspects, predisposing factors, clinical manifestations, diagnostic tools, and current and future prophylactic and therapeutic options for C. difficile infection.

Differential alteration in Lactiplantibacillus plantarum subsp. plantarum quorum-sensing systems and reduced Candida albicans yeast survival and virulence gene expression in dual-species interaction

Candida albicans (C. albicans) and Lactiplantibacillus plantarum subsp. plantarum (L. plantarum) are frequently identified in various niches, but their dual-species interaction, especially with C. albicans in yeast form, remains unclear. This study aimed to investigate the dual-species interaction of L. plantarum and C. albicans, including proliferation, morphology, and transcriptomes examined by selective agar plate counting, microscopy, and polymicrobial RNA-seq, respectively. Maintaining a stable and unchanged growth rate, L. plantarum inhibited C. albicans yeast cell proliferation but not hyphal growth. Combining optical microscopy and atomic force microscopy, cell-to-cell direct contact and co-aggregation with L. plantarum cells surrounding C. albicans yeast cells were observed during dual-species interaction. Reduced C. albicans yeast cell proliferation in mixed culture was partially due to L. plantarum cell-free culture supernatant but not the acidic environment. Upon polymicrobial transcriptomics analysis, interesting changes were identified in both L. plantarum and C. albicans gene expression. First, two L. plantarum quorum-sensing systems showed contrary changes, with the activation of lamBDCA and repression of luxS. Second, the upregulation of stress response-related genes and downregulation of cell cycle, cell survival, and cell integrity-related pathways were identified in C. albicans, possibly connected to the stress posed by L. plantarum and the reduced yeast cell proliferation. Third, a large scale of pathogenesis and virulence factors were downregulated in C. albicans, indicating the potential interruption of pathogenic activities by L. plantarum. Fourth, partial metabolism and transport pathways were changed in L. plantarum and C. albicans. The information in this study might aid in understanding the behavior of L. plantarum and C. albicans in dual-species interaction.IMPORTANCEThe anti-Candida albicans activity of Lactiplantibacillus plantarum has been explored in the past decades. However, the importance of C. albicans yeast form and the effect of C. albicans on L. plantarum had also been omitted. In this study, the dual-species interaction of L. plantarum and C. albicans was investigated with a focus on the transcriptomes. Cell-to-cell direct contact and co-aggregation with L. plantarum cells surrounding C. albicans yeast cells were observed. Upon polymicrobial transcriptomics analysis, interesting changes were identified, including contrary changes in two L. plantarum quorum-sensing systems and reduced cell survival-related pathways and pathogenesis determinants in C. albicans.