Gene polymorphisms and serum levels of pro- and anti-inflammatory markers in dengue viral infections

Abstract

Pro- and anti-inflammatory markers (tumor necrosis factor [TNF]-a, TNF-b, interferon [IFN]-c, interleukin [IL]-6, IL-8, IL-10, and C-reactive protein [CRP]) were investigated in 80 patients infected with dengue viruses, 100 patients presenting with febrile illness but negative for dengue, and 99 healthy subjects. Immunoenzyme methods were used for quantitative assays in the plasma. Polymorphisms of TNF-a, TNF-b, IL-6, IL-8, and IL- 10 genes were assessed by polymerase chain reaction (PCR)-restriction fragment length polymorphism and allele-specific oligonucleotide (ASO)-PCR for the IFN-c. The highest mean serum levels of TNF-a, IFN-c, IL-8, and CRP were observed in dengue-positive individuals. TNF-b, IL-6, and IL-10 levels were significantly higher in the dengue-negative individuals. No cytokine expression pattern was evidenced according to virus serotype. Genotypic frequency distributions were statistically significant for the polymorphisms of TNF-a and IFN-c among positive, negative, and control dengue groups and IFN-c among groups DENV-1, DENV-2, DENV-3, and controls. Modulation of cytokine expression and polymorphisms is a complex matter and needs further explanation considering the ethnic origins of the Brazilian population.