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Swidergall M, Solis NV, Millet N, Huang MY, Lin J, Phan QT, Lazarus MD, Wang Z, Yeaman MR, Mitchell AP, Filler SG. Activation of EphA2-EGFR signaling in oral epithelial cells by Candida albicans virulence factors. PLoS Pathog 2021; 17:e1009221. [PMID: 33471869 PMCID: PMC7850503 DOI: 10.1371/journal.ppat.1009221] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 02/01/2021] [Accepted: 12/05/2020] [Indexed: 12/12/2022] Open
Abstract
During oropharyngeal candidiasis (OPC), Candida albicans invades and damages oral epithelial cells, which respond by producing proinflammatory mediators that recruit phagocytes to foci of infection. The ephrin type-A receptor 2 (EphA2) detects β-glucan and plays a central role in stimulating epithelial cells to release proinflammatory mediators during OPC. The epidermal growth factor receptor (EGFR) also interacts with C. albicans and is known to be activated by the Als3 adhesin/invasin and the candidalysin pore-forming toxin. Here, we investigated the interactions among EphA2, EGFR, Als3 and candidalysin during OPC. We found that EGFR and EphA2 constitutively associate with each other as part of a heteromeric physical complex and are mutually dependent for C. albicans-induced activation. Als3-mediated endocytosis of a C. albicans hypha leads to the formation of an endocytic vacuole where candidalysin accumulates at high concentration. Thus, Als3 potentiates targeting of candidalysin, and both Als3 and candidalysin are required for C. albicans to cause maximal damage to oral epithelial cells, sustain activation of EphA2 and EGFR, and stimulate pro-inflammatory cytokine and chemokine secretion. In the mouse model of OPC, C. albicans-induced production of CXCL1/KC and CCL20 is dependent on the presence of candidalysin and EGFR, but independent of Als3. The production of IL-1α and IL-17A also requires candidalysin but is independent of Als3 and EGFR. The production of TNFα requires Als1, Als3, and candidalysin. Collectively, these results delineate the complex interplay among host cell receptors EphA2 and EGFR and C. albicans virulence factors Als1, Als3 and candidalysin during the induction of OPC and the resulting oral inflammatory response. Oropharyngeal candidiasis occurs when the fungus Candida albicans proliferates in the mouth to a point at which tissue damage occurs. The disease is characterized by fungal invasion of the superficial epithelium and a localized inflammatory response. Two C. albicans virulence factors contribute to the pathogenesis of OPC, Als3 which enables the organism to adhere to and invade host cells, and candidalysin which is a pore-forming toxin that damages host cells. Two epithelial cell receptors, ephrin type-A receptor 2 (EphA2) and the epidermal growth factor receptor (EGFR) are activated by C. albicans. Here, we show that EphA2 and EGFR form part of complex wherein these co-receptors are required to activate each other. Als3 enhances the host cell targeting of candidalysin by stimulating epithelial cell endocytosis of C. albicans, leading to the formation of an endocytic vacuole in which candidalysin accumulates. Thus, Als3 and candidalysin synergize to damage epithelial cells, activate EphA2 and EGFR, and stimulate the production of inflammatory mediators. In the mouse model of OPC, candidalysin elicits of a subset of the oral inflammatory response molecular repertoire. Of the cytokines and chemokines induced by this toxin, some require the activation of EGFR while others are induced independently of EGFR. Collectively, this work provides a deeper understanding of the interactions among C. albicans virulence factors, host cell receptors and immune responses during OPC.
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Affiliation(s)
- Marc Swidergall
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
- Institute for Infection and Immunity, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
- * E-mail: (MS); (SGF)
| | - Norma V. Solis
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
- Institute for Infection and Immunity, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Nicolas Millet
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
- Institute for Infection and Immunity, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Manning Y. Huang
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Jianfeng Lin
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
- Institute for Infection and Immunity, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Quynh T. Phan
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
- Institute for Infection and Immunity, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Michael D. Lazarus
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Zeping Wang
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Michael R. Yeaman
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
- Institute for Infection and Immunity, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
- Division of Molecular Medicine, Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Aaron P. Mitchell
- Department of Microbiology, University of Georgia, Athens, Georgia, United States of America
| | - Scott G. Filler
- Division of Infectious Diseases, Harbor-UCLA Medical Center, Torrance, California, United States of America
- Institute for Infection and Immunity, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, California, United States of America
- David Geffen School of Medicine at UCLA, Los Angeles, California, United States of America
- * E-mail: (MS); (SGF)
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