Elevated NS1 serum levels reduce CD119 expression and CXCL-10 synthesis in patients with dengue hemorrhagic fever

ABSTRACT Background: The intensity of dengue virus (DV) replication and circulating non-structural protein 1 (NS1) levels may promote changes in the human immune response and favor severe forms of infection. We investigated the correlations between NS1 with CXCL-8, CXCL-10, IFN-γ, and IL-12p40 serum levels, and IFN-γ receptor α chain (CD119) expression, and CXCL10 production by peripheral blood mononuclear cells (PBMCs) stimulated with recombinant IFN-γ in DV-infected patients with different clinical forms. Methods: Dengue virus NS1, CXCL-8, CXCL-10, IFN-γ, and IL-12p40 serum levels were measured in 152 DV-infected patients with different clinical forms and 20 non-infected individuals (NI) using enzyme-linked immunosorbent assay (ELISA). In addition, we investigated the CXCL-10 production after in vitro IFN-γ stimulation of PBMCs from 48 DV-infected individuals (with different clinical forms of dengue fever) and 20 NI individuals using ELISA, and CD119 expression on CD14+ cells with flow cytometry. Results: Patients with dengue hemorrhagic fever (DHF) had significantly higher NS1, CXCL-8, and CXCL-10 serum levels than those with classic dengue fever (DF). The response of PBMCs to IFN-γ stimulation was lower in patients with DHF than in those with DF or dengue with complications (DWC), with lower CD119 expression and reduced CXCL-10 synthesis. In addition, these alterations are associated with high NS1 serum levels. Conclusions: Patients with DHF reported high NS1 levels, low CD119 expression, and low CXCL-10 synthesis in PBMCs, which may be associated with infection progression and severity

Genetic and Functional Role of TNF-alpha in the Development Trypanosoma cruzi Infection

TNF-alpha plays an important role in trypanocidal mechanisms and is related to tissue injury. This cytokine has been detected in the heart of human chagasic patients where it is associated with tissue damage. This study investigated whether TNF-alpha levels and the presence of genetic polymorphisms are associated with the presence of T. cruzi infection and/or with the development of the cardiac form in chronic chagasic patients. Genomic DNA of 300 subjects from an endemic area was extracted and analyzed by PCR using specific primers. TNF-alpha was assayed in culture supernatants by ELISA. An association was observed between the absence of the TNF-238A allele and negative serology. Furthermore, seropositive individuals carrying the TNF-238A allele produced significantly higher TNF-alpha levels without stimulation (p = 0.04) and after stimulation with LPS (p = 0.007) and T. cruzi antigens (p = 0.004). The present results suggest that the polymorphism at position -238 influences susceptibility to infection and that this allele is associated with higher TNF-alpha production in seropositive individuals

Levels of TNF-alpha in culture supernatants.

<p>TNF-alpha was assayed by ELISA in supernatants of PBMC cultured for 48 h in the absence of any stimulus and in the presence of <i>T. cruzi</i> antigen, LPS and PHA. Subjects were grouped according to TNF-238A genotypes (TNF-238AA, TNF-238GA and TNF-238GG). Individuals with positive and negative serology were analyzed. Results are expressed as pg/mL. The horizontal line indicates the median, bars the 25% and 75% percentiles, and vertical lines the 10% and 90% percentiles.</p

TNF-alpha genotypes found in subjects from an endemic area according to clinical form.

<p>TNF-alpha genotypes found in subjects from an endemic area according to clinical form.</p

Levels of TNF-alpha in culture supernatants.

<p>TNF-alpha was assayed by ELISA in supernatants of PBMC cultured for 48 h in the absence of any stimulus and in the presence of <i>T. cruzi</i> antigen, LPS and PHA. <b>A.</b> Subjects were grouped according to positive or negative serology; *p = 0.0003 (Mann-Whitney test). <b>B.</b> Subjects were grouped according to the cardiac or indeterminate form and negative serology: Cardiac x negative to medium: p = 0.0002; cardiac x negative to LPS stimulation: p = 0.005; indeterminate x negative to PHA: p = 0.03; cardiac x indeterminate to medium: p = 0.01; to LPS: p = 0.005; to <i>T. cruzi</i> antigens: p = 0.01 (Mann-Whitney test). Results are expressed as pg/mL. The horizontal line indicates the median, bars the 25% and 75% percentiles, and vertical lines the 10% and 90% percentiles.</p

TNF-alpha genotypes found in subjects from an endemic area according to the presence or absence of infection.

<p>TNF-alpha genotypes found in subjects from an endemic area according to the presence or absence of infection.</p

Levels of TNF-alpha in culture supernatants.

<p>TNF-alpha was assayed by ELISA in supernatants of PBMC cultured for 48 h in the absence of any stimulus and in the presence of <i>T. cruzi</i> antigen, LPS and PHA. <b>A.</b> Subjects with positive serology and negative serology were grouped according to the presence or absence of the TNF-238A allele; *p = 0.045 (Mann-Whitney test). <b>B.</b> Only subjects with positive serology were grouped according to the presence or absence of the TNF-238A allele; * p = 0.04 compared to medium, p = 0.004 compared to <i>T. cruzi</i> antigen, and p = 0.007 compared to LPS (Mann-Whitney test). Results are expressed as pg/mL. The horizontal line indicates the median, bars the 25% and 75% percentiles, and vertical lines the 10% and 90% percentiles.</p