Evaluation of the local immune response and immunological factors correlated with cell exhaustion in chromoblastomycosis

Author(s)

Italo Novais Cavallone

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
• Defense date: 2024-08-16

Examining board members

Luiz Felipe Domingues Passero; Walter Belda Junior; Karen Spadari Ferreira; Marcia Dalastra Laurenti

• Advisor: Luiz Felipe Domingues Passero

Abstract

Chromoblastomycosis (CBM) is a neglected chronic subcutaneous disease caused by various species of melanized fungi, which are inoculated into the skin through lesions with materials contaminated with hyphae. This dissertation aimed to evaluate the immune response in the skin of CBM patients and correlate it with the involvement of the cell exhaustion molecules PD-1 and PD-L1. Thus, histological analyses, through hematoxylin-eosin staining and immunohistochemistry, were performed in twenty-three paraffin-embedded skin samples of CBM patients to determine the composition of the inflammatory infiltrate and the polarization of the immune response, respectively. Additionally, skin fragments from individuals submitted to plastic surgery were used as controls. Fungal DNA was isolated and sequenced to identify the etiological agent of the disease. The results indicated the presence of an inflammatory infiltrate composed mainly of histiocytes, with a high participation of giant cells with muriform cells inside, as well as lymphocytes, plasma cells, and polymorphonuclear cells. An increase in CD4+ and CD8+ T cells was observed, as well as M1 and M2 macrophage subsets, in patients with CBM compared to the healthy group. A mixed immune response in CBM samples was characterized by an increase in the density of IFN-+, iNOS+, IL-4+, and predominantly IL-10+ and IL-17+ cells, along with an increase in the expression of inhibitory markers related to cell exhaustion in PD-1+ and PD-L1+ cells compared to the control group. It was possible to identify the etiological agents of 5 samples (~ 27.7% of the samples), which belong to the Cladosporium and Alternaria genera. The data obtained in this study suggest that the inflammatory response in CBM is not related to the parasitic load, since patients with low and high parasitic burden presented the same immune response profile. Furthermore, despite the microbicidal response observed by the presence of IFN-+ and IL-17+ cells and macrophages M1, this is impaired by the predominance of the Treg response and the presence of cell exhaustion, allowing infection persistence and disease continuity (AU)

• FAPESP's process: 21/13772-8 - Evaluation of the local immune response and immunological factors correlated with cell exhaustion in chromoblastomycosis
• Grantee: Italo Novais Cavallone
• Support Opportunities: Scholarships in Brazil - Master