Paracoccidioidomycosis (PCM) is an important systemic mycosis in Latin America caused by the fungus Paracoccidioides brasiliensis (P. brasiliensis). It is more common in Brazil, Argentina, Colombia and Venezuela. The disease is characterized by two clinical forms: acute or juvenile and chronic type. The latter affects adults and lesions begin in the lungs and can spread to other organs including the skin. A fault in the specific immune response mediated by T cells in the PCM can allow the multiplication and spread of the fungus, including mucocutaneous manifestations. Regulatory T cells (Treg) are important in induction and maintenance of immune tolerance and immune response termination. A deficiency or dysfunction of these cells may lead to aggravation of inflammation induced by pathogens. The CD25 molecule is constitutively expressed by Treg but also other T cells can express it. Thus, the presence of CD25 alone is not an indicator of Treg cells and other markers must be involved to identify Treg in situ including the marker Foxp3, which is more specific. Treg cells, once activated, can suppress T or B lymphocytes, in addition to action on the function of elements of the innate immune system, such as macrophages and dendritic cells. The expression of TGF-beta, and IL10, seems to have suppressive activity on T cells. A recent study showed PCM high expression of Foxp3 in peripheral blood mononuclear cells from patients with active disease, that was lower in cured patients or healthy. There were still large numbers of CD4+CD25+ cells in the circulation of these patients. These characteristics of circulating cells were demonstrated in the lesions. In recent studies it was showed that Treg cells are elevated in blood and oral lesions of patients with PCM. Such cells accumulate in sites of infection, limiting the effector immune response and allowing the persistence of the fungus and induction of chronicity. There are still few studies that explore the population of Treg cells in lesions showing them in human PCM. In this project, we intend to contribute to the study of the characterization of skin lesions in PCM, addressing the involvement of Treg cells by immunostaining of CD25 and FOXP3. We also plan to detect and quantify the presence of cells with TGF-beta and IL10. We will study 30 skin biopsies selected from the files of Dermatopathology Laboratory, Division of Clinical Dermatology HCFMUSP of patients with clinical and pathological PCM. 10 fragments of normal skin will form the control group. The examination of the lesions will be done after staining with hematoxylin-eosin (HE) for observation of epidermal and dermal alterations. For detection of FOXP3 Treg cells, CD25 cells, TGF-beta and IL10 we will use the method of immunohistochemical streptavidin-biotin peroxidase. All reactions will be accompanied by positive controls to the antigens studied. The reaction protocols to be employed are the already developed in the Laboratory of Pathology of Transmissible Diseases, FMUSP, where the work will be developed. Reaction will also be done in double-labeling immunohistochemistry with use of different systems of disclosure (with the use of peroxidase and alkaline phosphatase) to detect cells expressing both CD25 and Foxp3. We hope to contribute to a better understanding of the phenomena that mediate the differences in local immune response in PCM skin lesions. The evaluation of the immunopathological mechanisms that occur in the skin may represent a model for understanding the pathogenic mechanisms of lung damage, since the skin lesions have diagnostic and predictive value for lung injury in Paracoccidioidomycosis.
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