Biology subjects

Naglik, J. R.

Publications and source records attributed to Naglik, J. R..

10 recordsLinked to original sources

bioRxiv2026

Candida albicans promotes self-adhesion and tumor cell progression of colorectal cancer cells.

Candida albicans, a benign commensal yeast in the healthy gut, is increasingly being recognized as a tumor-promoting component of the gut mycobiome that is linked to worse patient outcomes in colorectal cancer (CRC). Emerging evidence suggests that in the tumor microenvironment, C. albicans drives tumor progression in its pathogenic hyphal form with the secretion of its peptide toxin, candidalysin, enhancing tumor cell evolution. CRC cells differentially express transglutaminase 2 (TG2), which mediates covalent binding to C. albicans and can promote tumor adaptability and metastases. However, mechanistic insight into how C. albicans infection leads to CRC progression is incomplete. CRC lines that express high (SW480) and low (LoVo, HCT 116) TG2 were infected with C. albicans and examined for effects on epithelial to mesenchymal transition (EMT) and cell migration. Parallel studies were also conducted using a candidalysin-deficient C. albicans strain. C. albicans invasion stimulated TG2 activity that allowed covalent crosslinking of the hyphae adhesin, Hwp1, to SW480 cells in a candidalysin-dependent manner. Independent of TG2 expression, infection of SW480, LoVo, and HCT 116 cells induced EMT-like changes including downregulation of E-cadherin, altered N-glycosylation of N-cadherin, and variable Snail1 expression. Infection increased MGAT5 activity, which raised levels of branched {beta}(1-6) N-glycans. Infection promoted CRC cell motility that was blocked by pharmacological inhibition of MGAT5. Thus, C. albicans engages CRC cells through separable mechanisms: a candidalysin-TG2-Hwp1 axis that may stabilize fungal attachment in TG2-high tumor cells, and a TG2-independent program of epithelial plasticity, altered N-glycosylation and migration-associated behavior that requires validation in vivo.

microbiology↗

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

Bacterial suppression of intestinal fungi via activation of human gut γδ T-cells

Gut symbionts condition mucosal immunity to resist infection by enteropathogens, but the specific microbes and mechanisms involved differ significantly between host species. In higher primates, bacterial metabolite HMB-PP is sensed by a specialized population of V{gamma}9V{delta}2+T-cells, which we now report can potently suppress growth of endogenous fungi in human intestinal organ cultures. In healthy intestine, HMB-PP-stimulated V{delta}2+T-cells restricted outgrowth of keystone fungus Candida albicans via a mechanism that required IL-22. In contrast, Crohns disease (CD) patients with reduced V{delta}2+T-cell numbers displayed outgrowth of C. albicans strains that readily formed toxin-producing filaments, triggered neutrophil extracellular traps, and induced macrophage IL-1{beta} release ex vivo. Genomic and proteomic analysis of the Candida isolates suggested increased tissue adhesion of CD-derived strains, which rapidly invaded the gut barrier in an intestine-on-a-chip model. These data reveal that bacterial activation of V{delta}2+T-cells suppresses fungal pathobionts in human gut via an IL-22-dependent mechanism that is dysregulated in CD.

immunology↗

bioRxiv2025

Selective targeting of IL-1RAP-dependent eosinophilic inflammation in allergic fungal airway disease

It is estimated that in excess of 10 million people around the globe are affected by severe asthma and fungal sensitisation (SAFS) or allergic bronchopulmonary aspergillosis (ABPA), severe asthma endotypes driven by hypersensitivity to environmentally ubiquitous fungal pathogens, primarily Aspergillus fumigatus. Here, we sought to define the immunological pathways underlying these allergic fungal airway diseases. To do so, we exploit the chronic exposure repeat challenge model using live A. fumigatus conidia to systematically define the key immunological pathways driving airway inflammation in allergic fungal airway disease. In response to daily intranasal challenge, we observed increased absolute numbers of neutrophils and eosinophils in bronchoalveolar lavage fluid (BALF), characteristic of human allergic fungal airway disease, with significant depletion of the alveolar macrophage population. Transcriptomic analysis of BALF cells identified increased expression of IL-1 family cytokines and receptors including IL-1{beta}, IL-1RL1, IL-1R2 and the IL-18 binding protein. Complementary proteomic analysis of BALF revealed increased levels of cell death related proteins calprotectin and IL-1 Receptor Accessory Protein (IL-1RAP). Targeting IL-1RAP, using knockout mice, led to selective reduction in eosinophilia, IL-5 and IL-13 in the airways without impairment of fungal killing. This study identifies a role for IL-1RAP in the generation of eosinophilia independent of neutrophil influx and highlights its potential as a novel immunotherapeutic target for the treatment of allergic fungal airway disease. Author SummaryAllergic bronchopulmonary aspergillosis (ABPA) is a form of lung disease primarily affecting those with asthma or cystic fibrosis induced by the ubiquitous pathogen Aspergillus fumigatus. Understanding the immunological mechanisms contributing to this airway disease is important for the development of novel treatments to improve quality of life and preserve lung function. In this study, we show that an Aspergillus fumigatus repeat challenge model phenocopies immunological features of allergic fungal airway disease and is hallmarked by increased IL-1 family signalling. We identify the IL-1RAP as a contributor to eosinophilia and the release of Type 2 cytokines during allergic fungal airway disease. This work represents major step in describing the molecular mechanisms of airway eosinophilia in response to fungal exposure and lays the groundwork for further dissection of inflammatory pathways to target with immunotherapeutic approaches.

immunology↗

bioRxiv2025

Early Candida - Oral Tumor Interactions Suggest miRNA-Mediated Regulation of Inflammatory and Tumor-associated processes

When simultaneously present, oral cancer and oral candidiasis are associated with high mortality. Recently, fungi-driven OSCC has emerged as a recognized phenomenon, that is triggered by Candida and sustained by several pro-tumor mechanisms. This study aimed to deepen our understanding and investigate how these mechanisms are regulated at the early stages of fungi-tumor interactions. Post-transcriptional regulation was examined through the analysis of miRNA (miR) responses in a metastatic cell line. We characterized early tumor responses to two common oral yeasts, C. albicans, frequently responsible for oral infections, and C. parapsilosis, a yeast with mostly commensal behavior in this niche. Exposed to C. albicans, tumor cells exhibited overexpression of inflammatory and pro-tumor pathways. This was also mirrored at the miR-level. Intriguingly, this species induced upregulation of oncogenic miRs, while simultaneously downregulated tumor-suppressive miRs. miR-target analyses revealed targets primarily to be involved in inflammation (TNFa signaling via NFKB), albeit tumor progression was also heavily influenced based on the targets identified within the PanCancer Progression Panel. Several miR-target pairs were identified with TRIB1-miR-30c-1-3p highlighted at the route of inflammation, and MMP3-miR-374a-3p and JUN-miR-1268b/miR-16-1-3p/miR-30c-1-3p at the route of OSCC progression. These findings highlight that C. albicans drives OSCC progression, in part, through miR regulation. Contrarily, C. parapsilosis elicited tumor responses predominantly related to hypoxia and metabolic regulation, followed by a mild activation of inflammatory and tumorigenic processes. No significant miR-regulatory responses were identified. To sum up, we added a new layer to fungi-tumor interactions and identified regulatory elements, that might hold future translational potential. ImportancePrevious studies have shown that yeast carriage in the oral cavity of oral cancer patients is significantly higher than those of healthy individuals. Additionally, the abundance of fungal cells is higher at malignant epithelial surfaces compared to the unaffected mucosal tissues. These observations indicated a direct interaction between mouth residing yeasts and oral tumorous cells. We have previously demonstrated that certain Candida species actively contribute to tumor progression in metastatic oral epithelial cells via various mechanisms including the promotion of migration, MMP activity or oncometabolite secretion. In this study, our findings demonstrate, that fungi-driven OSCC progression is also evident at the level of miRNA regulation, when C. albicans is present. In this context, the fungus might also enhance existing post-transcriptional regulatory mechanisms in the malignant oral epithelium. This behavior seems to be species-specific, as another common resident of the oral microflora, C. parapsilosis does not trigger such an effect.

microbiology↗

bioRxiv2025

The fungal peptide toxin candidalysin induces distinct membrane repair mechanisms compared to bacterial pore-forming toxins

The common fungal pathogen, Candida albicans, relies on the pore-forming toxin candidalysin to damage host cells. Cells counteract pore-forming toxins by Ca2+-dependent mechanisms, such as microvesicle shedding and annexin recruitment to resist cholesterol-dependent cytolysins like streptolysin O (SLO), or annexin involvement and patch repair in the case of aerolysin. However, the specific Ca2+-dependent repair pathways engaged in response to candidalysin remain poorly understood. Here, we determined the involvement of different Ca2+-dependent repair mechanisms to candidalysin and compared responses to SLO and aerolysin using flow cytometry and high-resolution microscopy. We report that candidalysin triggered Ca2+-dependent repair, but patch repair and ceramide failed to provide significant protection. MEK-dependent repair and annexins A1, A2 and A6 contributed partially to repairing damage caused by candidalysin. However, annexin translocation after candidalysin challenge was delayed compared to SLO or aerolysin challenge. Surprisingly, extracellular Cl- improved cell survival after candidalysin challenge, but not after challenge with SLO or aerolysin. Finally, we found that candidalysin is removed via extracellular vesicle shedding. These findings reveal that Ca2+-dependent microvesicle shedding protects cells from candidalysin and can be engaged by multiple molecular mechanisms during membrane repair. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/653080v2_figa1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@433b3aorg.highwire.dtl.DTLVardef@1e583f3org.highwire.dtl.DTLVardef@139f086org.highwire.dtl.DTLVardef@de07b0_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract.C_FLOATNO Candidalysin is resisted by distinct repair mechanisms compared to bacterial PFTs.After pore formation and membrane damage by each toxin, multiple repair pathways are triggered downstream of Ca{superscript 2} flux. Candidalysin induces a protective Cl- influx and activates MEK-dependent repair, which contributes to cell protection. Annexin translocation occurs slowly and provides minor protection, while patch repair is ineffective. In contrast, aerolysin does not benefit from Cl- influx or MEK protection. Aerolysin triggers moderate annexin translocation and relies primarily on patch repair as the main protective mechanism. Streptolysin O elicits rapid annexin translocation and activates MEK signaling, both of which contribute to robust protection. Patch repair plays only a minor protective role against SLO. The figure was created using BioRender. C_FIG

cell biology↗

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↗

bioRxiv2022

Candida albicans promotes neutrophil extracellular trap formation and leukotoxic hypercitrullination via the peptide toxin candidalysin.

The cytolytic peptide toxin candidalysin is secreted by the invasive, hyphal form of the human fungal pathogen, Candida albicans. Candidalysin is essential for inducing host cell damage during mucosal and systemic C. albicans infections, resulting in neutrophil recruitment. Neutrophil influx to C. albicans-infected tissue is critical for limiting fungal growth and preventing the fungal dissemination. Here, we demonstrate that candidalysin secreted by hyphae promotes the stimulation of neutrophil extracellular traps (NETs), while synthetic candidalysin triggers a distinct mechanism for NET-like structures (NLS), which are more compact and less fibrous than canonical NETs. Candidalysin activates NADPH oxidase and calcium influx, with both processes contributing to morphological changes in neutrophils resulting in NLS formation. NLS are induced by leukotoxic hypercitrullination, which is governed by protein arginine deaminase 4 activation via calcium influx and initiation of intracellular signalling events. However, activation of signalling by candidalysin does not suffice to trigger downstream events essential for NET formation, as demonstrated by lack of lamin A/C phosphorylation, an event required for activation of cyclin-dependent kinases that are crucial for NET release. Interestingly, exposure to candidalysin does not immediately restrict the capability of neutrophils to produce reactive oxygen species (ROS), nor to phagocytose particles. Instead, candidalysin triggers ROS production, calcium influx and subsequent activation of downstream signalling that drive morphological alteration and the formation of NLS in a dose- and time-dependent manner. Notably, candidalysin-triggered NLS demonstrate anti-Candida activity, which is resistant to nuclease treatment and dependent on the deprivation of Zn2+. This study reveals that C. albicans hyphae releasing candidalysin concurrently trigger canonical NETs and NLS, which together form a fibrous sticky network that entangles C. albicans hyphae and inhibits their growth. Importantly, this explains discrepancies of previous studies demonstrating that neutrophil-derived extracellular chromatin structures triggered by C. albicans can be both dependent and independent of ROS. Our data also demonstrate that while candidalysin hampers neutrophil function, the toxin also increases the capability of neutrophils to entangle hyphae and to restrict their growth, reflecting the importance of human neutrophils in controlling the dissemination of C. albicans.

immunology↗

bioRxiv2022

EGFR-MAPK adaptor proteins mediate the epithelial response to Candida albicans via the cytolytic peptide toxin, candidalysin

Candida albicans (C. albicans) is a dimorphic human fungal pathogen that can cause severe oropharyngeal candidiasis (OPC, oral thrush) in susceptible hosts. During invasive infection, C. albicans hyphae invade oral epithelial cells (OECs) and secrete candidalysin, a pore-forming cytolytic peptide that is required for fungal pathogenesis at mucosal surfaces. Candidalysin induces cell damage and activates multiple MAPK-based innate signaling events that collectively drive the production of downstream inflammatory mediators. The activities of candidalysin are also dependent on the epidermal growth factor receptor (EGFR), but how these signals are integrated is undefined. Here, we identified five essential adaptor proteins as key mediators of the epithelial response to C. albicans infection on cultured OECs, including growth factor receptor bound protein 2 (Grb2), Grb2-associated-binding protein 1 (Gab1), Src homology and collagen (Shc), SH2 containing protein tyrosine phosphatase-2 (Shp2) and casitas B-lineage lymphoma (c-Cbl). All these signaling effectors were inducibly phosphorylated in response to C. albicans, in a candidalysin-dependent mechanism but additionally required EGFR phosphorylation, matrix metalloproteinases (MMPs) and cellular calcium flux. Of these, Gab1, Grb2 and Shp2 were the dominant drivers of ERK1/2 signaling and production of downstream cytokines. Together, these results identify the key adaptor proteins that drive EGFR signaling mechanisms, which determine oral epithelial responses to C. albicans.

microbiology↗

bioRxiv2021

Aspergillus fumigatus drives tissue damage via iterative assaults upon mucosal integrity and immune homeostasis

The human lung is constantly exposed to Aspergillus fumigatus spores, the most prevalent worldwide cause of fungal respiratory disease. Pulmonary tissue damage is a unifying feature of Aspergillus-related diseases; however, the mechanistic basis of damage is not understood. In the lungs of susceptible hosts A. fumigatus undergoes an obligatory morphological switch involving spore germination and hyphal growth. We modelled A. fumigatus infection in cultured A549 human pneumocytes, capturing phosphoactivation status of five host signalling pathways, nuclear translocation & DNA binding of eight host transcription factors, and expression of nine host response proteins over six time points encompassing exposures to live fungus and the secretome thereof. The resulting dataset, comprised of more than 1000 data points, reveals that pneumocytes mount differential responses to A. fumigatus spores, hyphae and soluble secreted products via the NF-kB, JNK, and JNK + p38 pathways respectively. Importantly, via selective degradation of host pro-inflammatory (IL-6 and IL-8) cytokines and growth factors (FGF-2), fungal secreted products reorchestrate the host response to fungal challenge as well as driving multiparametric epithelial damage, culminating in cytolysis. Dysregulation of NF-kB signalling, involving iterative stimulation of canonical and non-canonical signalling, was identified as a significant feature of host damage both in vitro and in a mouse model of invasive aspergillosis. Our data demonstrate that composite tissue damage results from iterative exposures to different fungal morphotypes and secreted products and suggest that modulation of host responses to fungal challenge might represent a unified strategy for therapeutic control of pathologically distinct types of Aspergillus-related disease. IMPORTANCEPulmonary aspergillosis is a spectrum of diseases caused primarily by Aspergillus fumigatus. This fungus is ubiquitous in the environment and grows as a mold, which harbors and disperses spores into the environment. Like other airborne pathogens, the lung mucosa is the first point of contact with the fungus post inhalation. The outcome and severity of disease depends on the host-fungal interaction at the lung interface. We studied how the human lung interacts with spore, germ tube and hyphae growth forms to understand the sequence and dynamics of the early events, which are critical drivers of disease development and progression. Our work is significant in identifying, in response to fungal secreted products, non-canonical NF-kB activation via RelB as being a driving factor in fungus-mediated lung damage. This process could be modulated therapeutically to protect the integrity of infected lung mucosae.

microbiology↗