"Role of human neutrophils in the modulation of the adaptive immune response to Paracoccidioides brasiliensis: transcriptional analysis of involved cells"

Abstract

The thermodimorphic fungus Paracoccidioides brasiliensis (Pb) is the etiological agent of paracoccidioidomycosis (PCM) a systemic mycosis endemic in Latin America. Studies aiming to characterize the immune response of the infected host have focused on the role of different subpopulations of CD4+ cells, with special interest for the mechanisms involved in the induction of one or other subpopulation, which are largely dependent on the initial interaction between the infectious agent and the cells of the innate immune response. Among these cells, neutrophils (PMNs) have attracted attention in recent years since they can be induced to express genes encoding important inflammatory mediators, including a number of cytokines and other molecules. Thus, these cells that have traditionally considered only as effector cells of the innate immune response reemerged as important modulators of the adaptive immune system. In this context, we hypothesized that these cells play an important role in modulating the adaptive immune response to Pb. During this process, PMNs may act both directly as indirectly by modulating the activity of dendritic cells (DCs). Thus, the following modulatory activities of PMNs will be tested: 1 - ability to act as antigen-presenting cells for CD4+ cells, 2 - recruit different subsets of CD4+ lymphocytes, as well as release modulatory cytokines involved in CD4+ differentiattion and 3 - recruit and modulate the activity of DCs in relation to their role in the differentiation of CD4+ subpopulations. We choose as an experimental approach for the development of the present study, the analysis of the global transcriptional profile of the cells involved in the modulatory process, i.e. PMNs, DCs and CD4+. Accordingly, the objectives of the study are: 1. To analyze the transcriptional profile of PMNs in response to the fungus, with special attention to the molecules involved in the recruitment of different subpopulations of CD4+ cells as well as to those involved in recruitment and modulation of the activity of DCs in relation to their capacity to antigen presentation and in modulating the differentiation of CD4+ cells subpopulations, 2. To analyze the transcriptional profile of DCs in response to PMNs infected with the fungus, with special attention to molecules related to phenotypic maturation of these cells and cytokines important for differentiation of CD4+ cells subpopulations and 3. To evaluate the transcriptional profile of CD4+ cells cocultured with PMNs infected with the fungus or cocultured with DCs that came in contact with PMNs primed with the fungus, focusing on transcription factors and regulatory cytokines involved in the differentiation of CD4+ cells subpopulations.