Oral Epithelial Cells Distinguish between Candida Species with High or Low Pathogenic Potential through MicroRNA Regulation

MiR- 146b-5p inhibits Candida albicans-induced inflammatory response through targeting HMGB1 in mouse primary peritoneal macrophages

Background

Candida albicans (C. albicans) is one of the most common pathogens associated with deep fungal infection, which represents a serious threat to human health. Although high mobility group box 1 (HMGB1) plays a key role in C. albicans infection, its mechanism is unclear. We aimed to explore the regulation of small-molecule non-coding RNA (miRNA) for HMGB1 in C. albicans infection.

Methods

Mouse primary peritoneal macrophages (MPMs) were isolated successfully. The optimum conditions for C. albicans infection were selected by Western blot and ELISA. The miRNA differential expression profiles of C. albicans infection were screened and verified by 6 miRNA gene chips and qRT-PCR. The direct regulation of the target gene HMGB1 by mmu-miR-146b-5p was confirmed through a dual-luciferase assay. The levels of mmu-miR-146b-5p, HMGB1, inflammatory mediators, p-IKK, IKK, p-IκBα, IκBα and NF-κB p65 were tested by qRT-PCR, Western blot, and ELISA. The nuclear and cytoplasm translocation of HMGB1 and NF-κB p65 were detected by Western blot and laser confocal microscopy. After siHMGB1 transfection, the expression levels of HMGB1, inflammatory mediators, p-IKK, IKK, p-IκBα, IκBα and NF-κB p65 were assessed using Western blot, qRT-PCR and ELISA.

Results

In our study, MPMs were successfully extracted and infected with C. albicans at optimum conditions of 1.5 × 107 CFU/mL for 36 h. Through miRNA gene chips analysis, 40 differential genes were screened. mmu-miR-146b-5p could directly and negatively regulate the expression and translocation of HMGB1, inhibit the expression of inflammatory mediators, and might participate in the NF-κB signaling pathway in a HMGB1-dependent manner under C. albicans infection.

Conclusion

mmu-miR-146b-5p may play an anti-inflammatory role in treating C. albicans infection and provide a novel target for it.

In Vitro Acid Resistance of Pathogenic Candida Species in Simulated Gastric Fluid

Background and Aims

Although species in the fungal genus Candida are often commensal residents of the gastrointestinal (GI) tract, they can also cause high-mortality systemic candidiasis. Most pathogenic Candida species are dimorphic fungi that exist predominantly in filamentous forms in the invading tissues. Candida albicans is the most prominent pathogen among Candida species, but nonalbicans Candida species have also emerged as important pathogens. The stomach is the most acidic niche in the GI tract and is maintained at pH 1-2 in healthy individuals. The aim of the present study was to determine whether Candida species can survive in gastric fluid and to observe their morphology under varied pH conditions.

Methods

We investigated the in vitro survival of the pathogenic Candida species C. albicans, Candida glabrata, Candida parapsilosis, and Candida tropicalis in simulated gastric fluid.

Results

We first described that a portion of the 4 Candida species can survive under highly acidic conditions. Moreover, dimorphic Candida species, namely, C. albicans, C. parapsilosis, and C. tropicalis, exhibited yeast-hyphal transition in simulated gastric fluid with elevated pH. Pathogenic filamentous cells had lower acid resistance than yeast cells.

Conclusion

These findings may illuminate the migration to the lower GI tract by commensal fungi of the oral cavity.

Isolation of Clavispora lusitaniae from the Oral Cavity of Immunocompetent Young Adults from the North of Mexico

The human oral cavity is normally colonized by microorganisms including bacteria, fungi, archaea, viruses and protozoa. The aim of this study was to determine the frequency of Candida spp., in de oral cavity in a group of medical students from the north of Mexico. Oral sample were obtained from 240 healthy students. The specimens were analyzed by traditional microbiology cultures and DNA sequencing. Candida spp., grew in Sabouraud dextrose agar from 57 samples and subsequently were isolated and phenotyped. The definitive identification to the species level was done by sequence analysis. The yeasts were identified as follow: 28 Clavispora lusitaniae, 20 Candida albicans, 5 Pichia kudriavzevii and 4 Candida parapsilosis. Our findings revealed that 23.75% of the healthy population has a potential pathogen in their mouth. Surprisingly, C. albicans is not the predominant yeast; instead other non-Candida species are the colonizers of the oral cavity as normal microbiota. C. lusitaniae is considered an emerging opportunistic pathogen in immunosuppressive patients. This paper pretends to highlight the presence of this yeast in the oral cavity in immunocompetent young adults.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01145-x.

Candida albicans increases the aerobic glycolysis and activates MAPK-dependent inflammatory response of liver sinusoidal endothelial cells

The liver, and more specifically, the liver sinusoidal endothelial cells, constitute the beginning of one of the most important responses for the elimination of hematogenously disseminated Candida albicans. Therefore, we aimed to study the mechanisms involved in the interaction between these cells and C. albicans. Transcriptomics-based analysis showed an increase in the expression of genes related to the immune response (including receptors, cytokines, and adhesion molecules), as well as to aerobic glycolysis. Further in vitro analyses showed that IL-6 production in response to C. albicans is controlled by MyD88- and SYK-pathways, suggesting an involvement of Toll-like and C-type lectin receptors and the subsequent activation of the MAP-kinases and c-Fos/AP-1 transcription factor. In addition, liver sinusoidal endothelial cells undergo metabolic reprogramming towards aerobic glycolysis induced by C. albicans, as confirmed by the increased Extracellular Acidification Rate and the overexpression of enolase (Eno2), hexonikase (Hk2) and glucose transporter 1 (Slc2a1). In conclusion, these results indicate that the hepatic endothelium responds to C. albicans by increasing aerobic glycolysis and promoting an inflammatory environment.

Clinical Assessment and Management in Improving the Quality of Life of HIV/AIDS Patients with Oral Candidiasis: A Case Series

Introduction

Oral candidiasis is the most prevalent opportunistic infection in patients with human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS), impacting their quality of life. This report aims to emphasize the importance of clinical assessment and management of HIV/AIDS patients with oral candidiasis to improve their quality of life.

Case

Five male patients, aged between 32 and 71 years, came to the HIV clinic and complained of white plaques in their mouths and painful swallowing. The World Health Organization's (WHO) clinical staging of all patients was 4. Three patients had not yet received antiretroviral therapy (ART), and their total lymphocyte counts (TLC) of <1.170 cells/mm3. Two patients had dropped out of ART with CD4 counts were <40 cells/mm3. The body mass index of two patients was underweight, while the others were normal. The oral hygiene index simplified (OHI-S) of the patients was fair to poor. The quality of life assessment using the oral health impact profile 14 (OHIP-14) questionnaires before therapy showed values from 6-20. Clinical examination defined the diagnosis as oral candidiasis, exfoliative cheilitis, oral hairy leukoplakia, and a cytomegalovirus-related ulcer.

Case Management

The patients were treated with fluconazole, 0.2% chlorhexidine gluconate mouthwash, 2% miconazole cream, diphenhydramine, and multivitamins. The oral lesions were improved within 14 days to a month of treatment, and OHIP-14 scores were significantly reduced (0-3).

Conclusion

Clinical assessment is important in managing HIV/AIDS patients with oral candidiasis, which improves the patient's quality of life. Therefore, routine clinical assessment and management of HIV/AIDS patients are strongly recommended.

Recent Advances in Understanding the Human Fungal Pathogen Hypoxia Response in Disease Progression

Fungal-mediated disease progression and antifungal drug efficacy are significantly impacted by the dynamic infection microenvironment. At the site of infection, oxygen often becomes limiting and induces a hypoxia response in both the fungal pathogen and host cells. The fungal hypoxia response impacts several important aspects of fungal biology that contribute to pathogenesis, virulence, antifungal drug susceptibility, and ultimately infection outcomes. In this review, we summarize recent advances in understanding the molecular mechanisms of the hypoxia response in the most common human fungal pathogens, discuss potential therapeutic opportunities, and highlight important areas for future research.

LncRNA: A Potential Target for Host-Directed Therapy of Candida Infection

Despite various drugs work against Candida, candidiasis represents clinical management challenges worldwide due to the rising incidence and recurrence rate, as well as epidemics, of new drug-resistant pathogens. Recent insights into interactions between Candida and hosts contribute to exploring novel therapeutic strategies, termed host-directed therapies (HDTs). HDTs are viable adjuncts with good efficacy for the existing standard antifungal regimens. However, HDTs induce other response unintendedly, thus requiring molecular targets with highly specificity. Long noncoding RNAs (lncRNAs) with highly specific expression patterns could affect biological processes, including the immune response. Herein, this review will summarize recent advances of HDTs based on the Candida–host interaction. Especially, the findings and application strategies of lncRNAs related to the host response are emphasized. We propose it is feasible to target lncRNAs to modulate the host defense during Candida infection, which provides a new perspective in identifying options of HDTs for candidiasis.

Role of Cellular Metabolism during Candida-Host Interactions

Microscopic fungi are widely present in the environment and, more importantly, are also an essential part of the human healthy mycobiota. However, many species can become pathogenic under certain circumstances, with Candida spp. being the most clinically relevant fungi. In recent years, the importance of metabolism and nutrient availability for fungi-host interactions have been highlighted. Upon activation, immune and other host cells reshape their metabolism to fulfil the energy-demanding process of generating an immune response. This includes macrophage upregulation of glucose uptake and processing via aerobic glycolysis. On the other side, Candida modulates its metabolic pathways to adapt to the usually hostile environment in the host, such as the lumen of phagolysosomes. Further understanding on metabolic interactions between host and fungal cells would potentially lead to novel/enhanced antifungal therapies to fight these infections. Therefore, this review paper focuses on how cellular metabolism, of both host cells and Candida, and the nutritional environment impact on the interplay between host and fungal cells.

Candida albicans Enhances the Progression of Oral Squamous Cell Carcinoma In Vitro and In Vivo

Oral squamous cell carcinoma (OSCC) is associated with oral Candida albicans infection, although it is unclear whether the fungus promotes the genesis and progression of OSCC or whether cancer facilitates fungal growth. In this study, we investigated whether C. albicans can potentiate OSCC tumor development and progression. In vitro, the presence of live C. albicans, but not Candida parapsilosis, enhanced the progression of OSCC by stimulating the production of matrix metalloproteinases, oncometabolites, protumor signaling pathways, and overexpression of prognostic marker genes associated with metastatic events. C. albicans also upregulated oncogenes in nonmalignant cells. Using a newly established xenograft in vivo mouse model to investigate OSCC-C. albicans interactions, oral candidiasis enhanced the progression of OSCC through inflammation and induced the overexpression of metastatic genes and significant changes in markers of the epithelial-mesenchymal transition. Finally, using the 4-nitroquinoline 1-oxide (4NQO) murine model, we directly correlate these in vitro and short-term in vivo findings with the progression of oncogenesis over the long term. Taken together, these data indicate that C. albicans upregulates oncogenes, potentiates a premalignant phenotype, and is involved in early and late stages of malignant promotion and progression of oral cancer. IMPORTANCE Oral squamous cell carcinoma (OSCC) is a serious health issue worldwide that accounts for 2% to 4% of all cancer cases. Previous studies have revealed a higher yeast carriage and diversity in oral cancer patients than in healthy individuals. Furthermore, fungal colonization in the oral cavity bearing OSCC is higher on the neoplastic epithelial surface than on adjacent healthy surfaces, indicating a positive association between oral yeast carriage and epithelial carcinoma. In addition to this, there is strong evidence supporting the idea that Candida contributes to carcinogenesis events in the oral cavity. Here, we show that an increase in Candida albicans burden promotes an oncogenic phenotype in the oral cavity.