Contact PD/PI: MYLONAKIS, ELEFTHERIOS PROJECT SUMMARY Despite the availability of anti-retroviral therapy, oral candidiasis caused by the overgrowth of Candida spp. is the most frequent opportunistic infection among individuals living with HIV. The widespread use of azoles to treat oral candidiasis in individuals living with HIV often results in treatment failure. In addition to antifungal resistance, the current therapeutic options for oral candidiasis are limited by side effects the challenges posed by biofilm drug recalcitrance. Moreover, Candida auris has recently emerged as a multi-drug–resistant fungal pathogen and is classified as 1 of the 5 pathogens in the highest category—Urgent Threats—in the Antibiotic Resistance Threats in the United States. Polyphenols are secondary plant metabolites that have protective properties for human health, including antioxidant, anti-inflammatory, anticancer, and antimicrobial activity. We found that caffeic acid phenethyl ester (CAPE) and ellagic acid (EA) are both active against Candida spp., including C. auris resistant strains. The minimum inhibitory concentration for EA ranged from 0.125 to 0.25 µg/mL and, at subinhibitory concentrations, EA inhibited phospholipase production by C. auris. CAPE inhibited fungal filamentation and biofilm formation. Both compounds were active in the invertebrate model hosts Caenorhabditis elegans and Galleria mellonella. We further demonstrated that neither CAPE nor EA is toxic to human erythrocytes. Importantly, in a mouse model of oral candidiasis, CAPE significantly increased the expression of the murine antifungal defensin β- defensin 3 and reduced pseudomembranous lesions, invasion of hyphae on epithelium surfaces, tissue damage, and inflammatory infiltrates. The purpose of this proposal is to advance the development of these natural phenolic compounds for the management of oral candidiasis. We have published “proof of concept” studies that gellan can be impregnated with CAPE, and that the hydrogel is active in a mouse model of oral candidiasis. We will further advance these goals with the following Aims: 1. To optimize hydrogels loaded with EA and/or CAPE for maximal release of compounds and test their antifungal activity and cytotoxicity in vitro. 2. To test the optimized hydrogels loaded with EA and/or CAPE in an established mouse model of oral candidiasis. 3. To test the antifungal immune response to hydrogels loaded with EA and/or CAPE in the oral mucosa of volunteers living with HIV. Our overall hypothesis is that the combination of CAPE and EA could provide an ideal natural treatment against oral candidiasis with direct antifungal activity and activity against resistant strains (including C. auris), efficacy against filaments and biofilms, and immunomodulatory activity through the production of antimicrobial peptides and chemokines. In this context, the proposed studies could represent a pivotal stage in the development and translation of these natural compou...