Níveis séricos in vivo da proteína não estrutural 1 e parâmetros da resposta imune em pacientes infectados com o vírus dengue apresentando diferentes desfechos clínicos

Abstract

Immunopathological mechanism involved in the development of severe clinical manifestations during dengue virus (DENV) infection are not yet fully understood. However, it is apparent that monocyte-endothelial interactions play a central role in the pathophysiology of severe disease. During DENV infection, activated monocytes produce important soluble factors, such as tumor necrosis factor alpha (TNF-α), interleukin 10 and 12 (IL-10 and IL-12p40) and nitric oxide (NO), which might be critical to immunopathogenesis. These molecules are produced by monocytes in response to toll like receptor 4 (TLR4) stimulation. Given the fact that intensity of DENV replication during the early times of infection could determine clinical outcomes, it’s important to know the impact of viral proteins on innate immune parameters of DENV infected patients, such as TLR4 expression and IL-10,TNF-α and NO production. A precise link between dengue nonstructural protein 1 (NS1) levels and alterations of innate immune response is still obscure. Thus, the aim of the present study was to investigate the relationships between in vivo dengue nonstructural protein 1 (NS1) levels and immune response parameters (TLR4 expression, IL-10, IL-12p40, TNF-α and NO production) on infected dengue patients with different clinical outcomes. We evaluated TNF-α, IL-10, IL-12p40 and NS1 serum levels (ELISA) and NO (Griess Reaction) on a group of 196 DENV infected patients. Besides that, TNF-α production by peripheral blood mononuclear cells (PBMC) and TLR4 expression on CD14+ cells (flow cytometry) were also analyzed on a subgroup of 37 dengue patients with different clinical outcomes and 20 healthy controls. We detected a lower expression of TLR4 in patients with severe dengue when compared to patients with dengue fever (DF). In addition, we also found higher NS1 and lower NO serum levels and a poor response of TLR4 to LPS (with a reduced TNF-α production) in PBMCs obtained from severe dengue patients when compared to DF patients. These results show that in the course of dengue disease, some innate immune parameters may changes, depending on the phase and severity of the disease. During the acute phase of DENV infection, severe dengue patients display higher serum levels of NS1 and alterations on some innate immune response parameters, that may contribute to different clinical outcomes observed on dengue virus infection in humans.