Resumo

Paracoccidioides brasiliensis is a dimorphic fungus that causes paracoccidioidomycosis, the most prevalent systemic fungal infection in Brazil. It is believed that human infection occurs by inhalation of mycelial forms with subsequent transformation to yeast forms in host lungs. Pulmonary epithelial cells are the first contact for inhaled microorganisms, pollutants and allergens. In addition, these cells contribute to the host innate immune defense by secreting antimicrobial peptides and inflammatory mediators, such as cytokines and chemokines. Recently, our group described that P. brasiliensis yeasts are able to induce expression of inflammatory cytokines in the human lung epithelial cells A549. We also verified that IL-6 and IL-8 secretion promoted by this fungus was dependent on activation of p38 MAPK and ERK 1/2. Other kinases that may interact with cell receptors, such as Toll-like receptors, promoting modulation of cytokine secretion, are protein kinases C (PKCs). In this study, we show the role of PKCs in P. brasiliensis-induced cytokine secretion by A549 cells. A549 cells were incubated with yeast forms and concentrations of IL-6, IL-8 and IL-10 in these culture supernatants were determined by Sandwich ELISA kits. It was verified that IL-6 and IL-8 levels were higher in culture supernatants of A549 cells incubated with P. brasiliensis yeasts than in supernatants from A549 cells cultured in absence of fungi. IL-10 was undetectable in these cultures. By RT-PCR, we analyzed the expression of different PKC isoforms, we detected in A549 cells incubated with P. brasiliensis PKCs alpha, gamma, delta, epsilon, eta, theta, zeta, iota and mu. On the other hand, PKCs beta I and beta II were not observed. Next, the broad spectrum PKC inhibitor Go6983 and the selective PKC delta inhibitor Rottlerin were used to evaluate the importance of these kinases on cytokine secretion by A549 cells cultured in the presence of P. brasiliensis. We verified that these inhibitors reduced IL-6 and IL-8 levels in culture supernatants, suggesting that IL-6 and IL-8 secretion, promoted by P. brasiliensis, was dependent on activation of PKCs, particularly PKC delta. Role of each PKC, other than PKC delta, in cytokine secretion is being evaluated in our laboratory. Supported by FAPESP, CAPES and CNPq.