Biology subjects

Pellon, A.

Publications and source records attributed to Pellon, A..

5 recordsLinked to original sources

bioRxiv2026

The IL-1 Family Controls Acute Mucosal Fungal Infection and Mucosal-Systemic Dissemination.

Candida albicans is a major opportunistic pathogen in humans that is capable of breaching mucosal barriers and causing severe systemic infections with high mortality. How the host controls mucosal infection and prevents dissemination remains unclear but is essential for improving disease outcomes. Here, we demonstrate that C. albicans induces specific IL-1 family members, which are critical for initiating mucosal protection by controlling antimicrobial peptides, IL-17, and neutrophil responses. Loss of combined IL-1 family signalling led to severe mucosal C. albicans infection, which was eventually resolved by a potent neutrophil response. However, in neutropenic conditions (a key risk patient factor) abolishing IL-1 family signalling resulted in C. albicans dissemination, predominantly to the liver, mirroring clinical disease and leading to mortality. This study highlights the IL-1 family as a key initiator of mucosal immunity, restricting mucosal invasion and cooperating with neutrophils to prevent life- threatening systemic infections.

microbiology↗

bioRxiv2025

Metabolic imprinting drives epithelial memory during mucosal fungal infection

Epithelial cells at barrier sites are emerging as active participants in innate immune memory, yet the underlying metabolic and epigenetic mechanisms remain unclear. Here, we uncover a previously unrecognized form of trained immunity in oral epithelial cells that enhances protection against fungal infection. Using a mouse model, we show that mucosal exposure to Candida albicans confers sustained protective memory that is independent of adaptive immunity and myeloid cells. Mechanistically, mucosal memory is driven by proline catabolism via proline dehydrogenase (Prodh) in epithelial cells, which sustains mitochondrial function, epigenetic remodeling, and promotes cytokine production upon secondary challenge. Unlike classical trained immunity in immune cells, epithelial memory is independent of glycolysis but partially sustained by fatty acid oxidation via carnitine palmitoyltransferase-I (CPT1). These findings uncover a distinct metabolic-epigenetic axis that underlines long-term epithelial memory in the oral mucosa and reveal novel non-hematopoietic mechanisms of mucosal defense against fungal pathogens.

immunology↗

bioRxiv2025

Candida albicans enhances melanoma cell aggressiveness through p38-MAPK and HIF-1α pathways and metabolic reprogramming

Recent studies have increasingly focused on the role of fungi, including Candida albicans, in carcinogenesis. Since C. albicans is a component of the human microbiota, particularly on the skin, we investigated its effect on the phenotype and signalling pathways of melanoma cells. Assays for migration, adhesion, angiogenesis, and hepatic metastasis showed that C. albicans promotes a more malignant phenotype in melanoma cells. At the transcriptomic level, C. albicans increased the expression of VEGF (Vegfa), and genes associated with MAPK and HIF-1 signalling pathways, and with aerobic glycolysis. Further in vitro analysis revealed that TLRs and EphA2 receptors are involved in the recognition of live C. albicans, stimulating VEGF secretion and expression of the AP-1 transcription factor component c-Fos through p38-MAPK and HIF-1. These pathways also regulate the expression of other AP-1 constituents such as Atf3, Jun, and Jund. Moreover, p38-MAPK regulates glycolytic genes like Hk2, Slc2a1, and Eno2. In conclusion, C. albicans activates the p38-MAPK/c-Fos/AP-1 and HIF-1/HIF-1/c-Fos/AP-1 pathways in melanoma cells, promoting a pro-angiogenic environment and metabolic reprogramming. Therefore, this study clarifies the impact of C. albicans on melanoma cells, which can lead to the use of antifungal therapies as complementary to traditional treatments for melanoma.

microbiology↗

bioRxiv2023

EGR1 regulates oral epithelial cell responses to Candida albicans via the EGFR- ERK1/2 pathway

Candida albicans is a fungal pathobiont colonising mucosal surfaces of the human body, including the oral cavity. Under certain predisposing conditions, C. albicans invades mucosal tissues activating EGFR-MAPK signalling pathways in epithelial cells via the action of its peptide toxin candidalysin. However, our knowledge of the epithelial mechanisms involved during C. albicans colonisation is rudimentary. Here, we describe the role of the transcription factor early growth response protein 1 (EGR1) in human oral epithelial cells (OECs) in response to C. albicans. EGR1 expression increases in OECs when exposed to C. albicans independently of fungal viability, morphology, or candidalysin release, suggesting EGR1 is involved in the fundamental recognition of C. albicans, rather than in response to invasion or pathogenesis. Upregulation of EGR1 is mediated by EGFR via Raf1, ERK1/2 and NF-{kappa}B signalling but not PI3K/mTOR signalling. Notably, EGR1 mRNA silencing impacts on anti-C. albicans immunity, reducing GM-CSF, IL-1 and IL-1{beta} release, and increasing IL-6 and IL-8 production. These findings identify an important role for EGR1 in priming epithelial cells to respond to subsequent invasive infection by C. albicans and elucidate the regulation circuit of this transcription factor after contact.

immunology↗

bioRxiv2021

Integrative functional analysis uncovers metabolic differences between Candida species

Candida species are a dominant constituent of the human mycobiome and a better understanding of their metabolism from a fungal perspective can provide key insights into their ability to cause pathogenesis. Here, we have developed the BioFung database - a fungal specific tool for functional annotation using the KEGG database that provides an efficient method for annotation of protein-encoding gene. Analysis of carbohydrate-active enzyme (CAZymes) and BioFung, uncovered core and accessory features across Candida species demonstrating plasticity, adaptation to the environment and acquired features. Integerative functional analysis revealed that all Candida species can employ amino acid metabolism. However, metabolomics revealed that only a specific cluster of species (AGAu species - C. albicans, C. glabrata and C. auris) utilised amino acid metabolism. We identified critical metabolic pathways in the AGAu clusters with biomarkers and anti-fungal target potential in the CAZyme profile, polyamine, choline and fatty acid biosynthesis pathways. This study, combining genomic analysis, metabolomics and gene expression validation, highlights the metabolic diversity within AGAu species that underlies their remarkable ability to dominate the mycobiome and cause disease.

systems biology↗