Investigation of association between IL-6 level, il6 and il6r variants and community acquired pneumonia among Iranian children <5 years

Background Community-acquired pneumonia (CAP) is known as a dangerous illness accounted for approximately 20% of mortality in children younger than five years around the world. Regarding the immaturity of the immune system in this group; they are more inclined to infections particularly, CAP. In the onset of pneumonia, pro-inflammatory cytokines such as interleukin (IL)-1, tumor necrosis factor-α and IL-6 are essential for amplifying local immune response against the pathogen(s). As IL-6 is a multipotent cytokine with dual pro- and anti-inflammatory functions, this study aimed to evaluate the association of IL-6 level and the variants in IL-6 and IL-6 receptor (R) genes with community-acquired pneumonia in children under five years. Materials and methods This case–control study included 126 children with CAP and 70 healthy control children who matched the case group by age and sex. IL-6 rs1800795 and IL-6R rs8192284 polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP); also, the serum IL-6 levels were measured by enzyme-linked immunosorbent assay (ELISA) method. Results Compared to the healthy controls, the frequency of AC genotypes and allele A in IL6R rs8192284 were significantly higher in the CAP group compared with those in the controls (P value = 0.01 and 0.00001, respectively). Although the serum level of IL-6 was not significantly different between two groups, higher IL-6 level was associated with febrile condition (P = 0.001). Conclusion The results revealed that carriage of A allele and AC genotype at rs8192284 position of IL-6R may be a predisposing factor for CAP in children and increased level of IL-6 is associated with the presence of clinical manifestation such as fever. So, this factor could be added to the inflammatory panel for assessing the severity of disease as well as lung injury in children with CAP.