M2 macrophages and inflammatory cells in oral lesions of chronic paracoccidioidomycosis

Background Paracoccidioidomycosis (PCM) is a systemic fungal infection caused by Paracoccidioides brasiliensis (Pb) and associated with deficient cellular immune response, which is modulated by inflammatory cells, mainly macrophages, and cytokines. Recently, the comprehension of the macrophage polarization mediated by Th1 and Th2 cytokines has contributed to elucidate the immune response that takes part in some diseases. Thus, the aim of this study was to assess the presence of Th1‐ and Th2‐immune response and also Pb counting in oral lesions of chronic PCM. Methods Forty‐eight cases of chronic PCM oral lesions were included. All cases were classified as loose or dense granulomas. S100 protein, IL‐1β, IL‐6, TNF‐α, CD163 and CD68 immunoexpressions, and Pb localization were evaluated. The fungi present in the tissue were quantified by anti‐Pb antibody. Results Most patients were white men with mean age of 47 years old and showed higher incidence of multiple lesions. Loose granulomas were predominant and exhibited a great amount of M2 macrophages, which were visualized with anti‐CD163 antibody. The expression for CD163 and CD68 was similar (P = 0.05), highlighting the predominance of M2 macrophages in PCM. IL‐1β, IL‐6, and TNF‐α immunoexpression did not significantly change with CD163, CD68, and S100 protein. The number of fungi was significantly higher in cases with intense IL‐1β immunoexpression (P = 0.003). Conclusions M2‐activated macrophages were the majority among inflammatory cells in chronic PCM, characterizing the action of a Th2‐immune response. Nevertheless, Th1 cytokines were also found; mainly IL‐1β, which was associated with fungi counting in oral lesions.