Evaluation of the immunomodulatory and protective potential of extracellular vesicles produced by Aspergillus fumigatus

Author(s)

Mateus Silveira Freitas

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2023-10-09

Examining board members

Fausto Bruno dos Reis Almeida; Anamelia Lorenzetti Bocca; Paulo Sergio Rodrigues Coelho; João Paulo Bianchi Ximenez

• Advisor: Fausto Bruno dos Reis Almeida

Abstract

Aspergillus fumigatus is the main causative agent of invasive aspergillosis, a disease that has a high mortality rate and may affects immunocompromised patients. A. fumigatus has worldwide distribution and large conidia production, causing the human tract to be continuously exposed to conidia. Usually, conidia destruction and infection control are carried out by innate immune cells. They can identify the fungus and their products and respond appropriately. In this sense, we have the extracellular vesicles (EVs) produced by the fungus could interact with immune cells modulating its response. EVs are spherical structures formed by a lipid bilayer that have several described functions. They may act in cell communication, cell wall development, acquisition of resistance to antifungal agents, and modulation the host immune response. Important studies have described the interaction of fungal EVs with cells of the innate immune system, demonstrating the immunomodulatory potential of these EVs. This way we proposed to verify the immunomodulatory capabilities of A. fumigatus EVs, primarily over innate immunity cells. In this study, we stimulated innate immune cells and peripheral blood mononuclear cells (PBMCs) with A. fumigatus EVs and evaluated the conferred protection by EVs through in vivo model of Galleria mellonella. Furthermore, we verified that RAW 264.7 and AMJ2-C11 macrophages were able to produce TNF-α when stimulated with EVs, but not NO, IL-6, IL1-β, and superoxide. However, RAW 264.7 macrophages increased the expression of iNOS and Arginase-1, while AMJ2-C11 macrophages only increased Arginase-1. Stimulation with A. fumigatus EVs was able to induce conformational change in RAW 264.7 cells, but not in AMJ2-C11, as verified by light microscopy and increased transcription from C11b and CD18. Furthermore, neutrophils stimulated with A. fumigatus EVs, were not able to produce neutrophil extracellular traps (NETs) neither TNF-α and IL-10, while PMBCs were able to produce IL-6, but not TNF-α and IL-10. Despite the relatively low immune response produced, the administration of A. fumigatus EVs in G. mellonella was able to protect the larva against the fungal challenge. Our results suggest that A. fumigatus EVs possess a limited inflammatory action over innate immune cells, however, exert a role in the protection against the fungal infection. (AU)

• FAPESP's process: 19/22454-0 - Evaluation of the immunomodulatory potential of extracellular vesicles produced by Aspergillus fumigatus
• Grantee: Mateus Silveira Freitas
• Support Opportunities: Scholarships in Brazil - Doctorate