Oropharyngeal candidiasis (OPC) causes significant morbidity in a large, diverse population, especially patients who are immunocompromised due to AIDS, neutropenia, diabetes mellitus, or the use of steroids. In fact, it is estimated that nearly 10 million cases of HIV/AIDS-associated OPC occur annually, and nearly a fifth of these individuals have esophageal involvement. Azole antifungal agents are the current mainstay of therapy for OPC. However, because of the emergence of azole resistance, it is critical to develop novel strategies to prevent and treat OPC. Our studies have focused on the hypothesis that C. albicans genes that promote adherence to and invasion of epithelial cells are critical for the organism to cause OPC. This hypothesis is based on the fact that invasion of the superficial epithelium occurs during OPC, and that biopsy specimens from OPC patients reveal organisms within oral epithelial cells. Adherence/invasion functions are carried out by cell surface proteins that interact with cognate receptors on host cells. These interactions enable the organism to invade oral epithelial cells and avoid being killed by phagocytes. Our data indicate that there are two adherence/invasion pathways that function in OPC. Pathway I includes the C. albicans surface proteins Als3 and Ssa1, which interact with the epithelial cell surface proteins epidermal growth factor receptor (EGFR) and HER2. Pathway II is newly described in our preliminary results. Pathway II includes the C. albicans surface protein Hyr1, which binds to the c-Met receptor tyrosine kinase on both oral epithelial cells and neutrophils. Our overall premise is that both Pathway I and Pathway II promote endocytosis of C. albicans by oral epithelial cells through E-cadherin. Pathway II also functions when C. albicans interacts with neutrophils to inhibit neutrophil killing. The objectives of the proposed studies are to test Pathway II function and its mechanistic basis, and to define the relationships between Pathway I and Pathway II. We will 1) determine the role of the Hyr1-c-Met interaction in inhibition of neutrophil fungicidal activity and epithelial cell invasion; 2) define the functional relationships among Hyr1 and the cell surface invasins Als3 and Ssa1 in vitro and in vivo; and 3) define additional Pathway I and II genes that function during OPC. The results from this research will provide new insight into the mechanisms by which C. albicans invades oral epithelial cells and down-regulates neutrophil fungicidal mechanisms. Not only will these data provide a deeper understanding of the pathogenesis of OPC, but they also hold promise to identify new potential drug and vaccine targets.

Public Health Relevance

Project Relevance / Narrative This research is highly relevant to public health because oropharyngeal candidiasis remains a significant problem in newly diagnosed AIDS patients, even with currently available treatment. Discovering how Candida albicans invades host cells and avoids being killed by neutrophils holds promise to provide new insight into the pathogenesis of oropharyngeal candidiasis and other type of microbial infections in which c-Met is activated. Furthermore, this information may be used to develop new diagnostic or therapeutic strategies against this disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE026600-04
Application #
9894647
Study Section
AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
Program Officer
Lumelsky, Nadya L
Project Start
2017-04-01
Project End
2022-03-31
Budget Start
2020-04-01
Budget End
2021-03-31
Support Year
4
Fiscal Year
2020
Total Cost
Indirect Cost
Name
Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center
Department
Type
DUNS #
069926962
City
Torrance
State
CA
Country
United States
Zip Code
90502
Forche, Anja; Cromie, Gareth; Gerstein, Aleeza C et al. (2018) Rapid Phenotypic and Genotypic Diversification After Exposure to the Oral Host Niche in Candida albicans. Genetics 209:725-741
Uppuluri, Priya; Lin, Lin; Alqarihi, Abdullah et al. (2018) The Hyr1 protein from the fungus Candida albicans is a cross kingdom immunotherapeutic target for Acinetobacter bacterial infection. PLoS Pathog 14:e1007056
Swidergall, Marc; Solis, Norma V; Lionakis, Michail S et al. (2018) EphA2 is an epithelial cell pattern recognition receptor for fungal ?-glucans. Nat Microbiol 3:53-61
Liu, Ning-Ning; Uppuluri, Priya; Broggi, Achille et al. (2018) Intersection of phosphate transport, oxidative stress and TOR signalling in Candida albicans virulence. PLoS Pathog 14:e1007076
Watkins, Tonya N; Gebremariam, Teclegiorgis; Swidergall, Marc et al. (2018) Inhibition of EGFR Signaling Protects from Mucormycosis. MBio 9:
Uppuluri, Priya; Singh, Shakti; Alqarihi, Abdullah et al. (2018) Human Anti-Als3p Antibodies Are Surrogate Markers of NDV-3A Vaccine Efficacy Against Recurrent Vulvovaginal Candidiasis. Front Immunol 9:1349
Davis, Sarah E; Tams, Robert N; Solis, Norma et al. (2018) Candida albicans cannot acquire sufficient ethanolamine from the host to support virulence in the absence of de novo phosphatidylethanolamine synthesis. Infect Immun :
Solis, Norma V; Park, Yang-Nim; Swidergall, Marc et al. (2018) Candida albicans White-Opaque Switching Influences Virulence but Not Mating during Oropharyngeal Candidiasis. Infect Immun 86:
McLellan, Catherine A; Vincent, Benjamin M; Solis, Norma V et al. (2018) Inhibiting mitochondrial phosphate transport as an unexploited antifungal strategy. Nat Chem Biol 14:135-141
Solis, Norma V; Swidergall, Marc; Bruno, Vincent M et al. (2017) The Aryl Hydrocarbon Receptor Governs Epithelial Cell Invasion during Oropharyngeal Candidiasis. MBio 8:

Showing the most recent 10 out of 13 publications