EARLY TRANCRIPTIONAL RESPONSEOF MURINE DENDRITIC CELLS UPON INFECTION WITH PARACOCCIDIOIDES BRASILIENSIS YEAST CELLS.

Lorena da Silveira Derengowski (UnB); Karen Ferreira (USP); Simoneide Silva (UnB); Geraldo Passos (USP); Sandro Almeida (USP); Ildinete Silva Pereira (UnB)

Paracoccidioides brasiliensis is the etiologic agent of paracoccidioidomycosis (PCM), a systemic human mycosis geographically confined to Latin America. It is a thermal dimorphic fungus which can be found as mycelium at room temperature (25ºC) and as yeast cells at body temperature (37ºC). The most relevant defense of the host against PCM is the cellular immunity. Despite the importance role of dendritic cells (DCs), which are the most effective antigen-presenting cells for inducing cell-mediated immune responses in PCM, little is known about the regulation of their genes upon  P. brasiliensis infection. We therefore examined the gene expression of murine DCs infected with P. brasiliensis. Total RNA from DCs after 6h of infection was extracted and their transcriptional profiles were analyzed by microarray technology. We have been able to identify a total of 66 up-regulated genes and 113 down-regulated genes. Some of these genes are related to several immune processes such as cytokines, and chemokines (e.g., IL-12, TNF-a, CCL22, CCL27, and CXCL10), cell surface receptors, transcriptional regulation (e.g., NFkB), signal transduction and apoptosis (e.g., CASP2). We also show that the expression profile of genes analyzed by Real-time RT-PCR correlated with the profile observed in the microarray experiments. In addition, we have confirmed by immunoassay (ELISA) that IL-12 and TNF-a mRNA induction resulted also in an increase of protein secretion. We observed that these cytokines were strongly secreted by infected dendritic cells when compared to non-infected ones. Thus our data contribute to the current understanding of early host gene expression upon infection by P. brasiliensis. This work was supported by FAP-DF/CNPq.  L.S. Derengowski was supported by a fellowship from CNPq.