Innate lymphoid cells confer protection in a murine model of dermatophytosis

IGNACIO BECCACECE; ERÓNICA BURSTEIN1, MARIEL ALMEIDA1, LORENA GUASCONI1, CRISTIAN MENA1; LAURA CERVI1, ADRIANA GRUPPI1; MICHAIL LIONAKIS; CHIAPELLO, LAURA S.

San Luis

Congreso; eunión Anual de la Sociedad Argentina de Inmunología (SAI); 2023

Sociedad Argenina de Inmunología

Dermatophytosis is a cutaneous fungal infection caused by filamentous keratinophilic fungi. Despite its prevalence of 25% worldwide, the skin-specific immune response against dermatophytes has been scarcely investigated. Previously, using an experimental model of dermatophytosis in C57BL/6 mice, we demonstrated that IL17RA-dependent signaling is crucial to control the superficial infection caused by the human pathogens Microsporum canis and Nannizzia gypsea. Furthermore, we demonstrated that, after N. gypsea epicutaneous infection, IL-17A-producing cells in the skin were mainly αβ and γδ T cells and the skin resident lymphocytes were sufficient to prevent fungal overgrowth.The aim of this study was to further characterize the in vivo role of lymphoid cell populations in the protective immunity to Nannizzia gypsea experimental dermatophytosis.Wild type (WT), mice deficient in mature T and B cells (Rag1-/-, Rag2-/-) and mice deficient in lymphoid cells (Rag2-/-Il2rg-/- C57BL/6 mice, Rag2γC KO) were epicutaneously infected in the back with a fungal suspension of N. gypsea (DO=1,00 at 450 nm). At 3-, 7- or 20-days post-infection (dpi), mice were euthanized and the back skin was removed and trypsinized (2h, 37°C) to obtain an epidermal cell suspension used for fungal burden quantification (CFU/gr skin), cytokine production (ELISA) and FACS analysis of IL-17A-producing or RORγt-expressing skin cell populations.Results showed that N. gypsea-infected Rag-1, Rag-2 and WT mice have similar fungal burden at the different days post-infection. In addition, WT and Rag-2 mice completely cleared the infection by 20 dpi. Unsupervised tSNE and supervised FACS analyses revealed that infected Rag-1 mice maintained a lymphoid skin population characterized as innate lymphoid cells (CD45+ CD90+ CD3- CD11b CD11c- Ly6G- Ly6C-), which expressed high levels of the transcription factor RORγt+ suggesting an ILC3 phenotype. Interestingly, despite Rag-1 mice controlled the dermatophytosis and harbored RORγt+ ILC cells, these mice showed a significant decrease in the frequency of skin IL-17A-producing cells when compared to WT mice (P