Association of IL-1β polymorphisms and plasma levels with chronic heart failure: A case-control study in Chinese patients

Heart failure (HF) has been major health concern affecting 1%-2% of world adult population. Role of various cytokines in chronic heart failure (CHF) have been demonstrated in different populations; however, association of an important cytokine, interleukin-1 beta (IL-beta), is poorly documented. Furthermore, polymorphism in promoter region is shown to be linked with cytokines levels. In this study, we explored plasma levels of IL-1 beta in healthy controls (HCs) and different clinical categories of CHF and association of common IL-1 beta promoter variants with susceptibility to development of HF. In all, 354 CHF patients admitted to Department of Cardiology at the first affiliated hospital of Soochow University were enrolled in this study. These patients were further clinically sub-categorized into New York Heart Association (NYHA)-I to IV based on NYHA criteria. A total of 77 HCs were included in the current investigation. Plasma levels of IL-1 beta were quantified by enzyme-linked immunosorbent assay (ELISA) and common promoter gene polymorphisms in IL-1 beta gene were genotyped by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). CHF patients displayed higher plasma IL-1 beta compared to HCs. Interestingly, plasma levels of IL-1 beta were associated with severity of HF patients: NYHA-IV had highest levels, and least quantity was noticed in NYHA-I cases. Prevalence of heterozygous and homozygous mutant for C-511T polymorphisms were significantly higher in CHF patients when compared to HCs. Importantly, these observations remained valid for NYHA-III and IV sub-groups in comparison to controls. Elevated plasma levels of IL-1 beta were observed in 511 mutants (CT and TT) than wild type (CC), indicating important function variants determining plasma levels of cytokine in both controls and patients. In conclusion, IL-1 beta (C-511T) variants are associated with elevated plasma IL-1 beta and predisposed to severe chronic HF in Chinese.