Effect of Fonsecaea monophora on the Polarization of THP-1 Cells to Macrophages

Background Chromoblastomycosis is a chronic, progressive fungal disease of the skin and subcutaneous tissue caused by a unique group of dematiaceous fungi. Fonsecaea monophora , a new species distinct from Fonsecaea pedrosoi strains, is the main pathogen responsible for chromoblastomycosis in south China. Macrophages can be polarized into two categories: classically activated and alternatively activated. Objectives Little is known about the relationship between F. monophora and macrophage polarization. This study aimed to study the effect of F. monophora on the polarization of THP-1 cells to macrophages. Methods We established coculture systems of F. monophora and THP-1-derived macrophages in different activation states. Results F. monophora enhanced the phagocytosis by macrophages in the initially activated state and weakened the phagocytosis by classically activated macrophages without affecting that by alternatively activated macrophages. Classically activated macrophages had the strongest killing effect on F. monophora , while the initially activated macrophages had the weakest. The pathogen could not be rapidly cleared by any type of macrophage. F. monophora promoted the expression of proinflammatory cytokines and inhibited that of anti-inflammatory cytokines. Conclusions F. monophora promoted the polarization of THP-1 cells to classically activated macrophages and inhibited that of THP-1 cells to alternatively activated macrophages.