Influence of cytokine gene polymorphisms on proinflammatory/anti-inflammatory cytokine imbalance in premature coronary artery disease.

BACKGROUND: Genetic information has the potential to create a more personalised, prompt, early and accurate risk evaluation. The effect of these genetic variants on the serum biomarker levels (phenotype) needs to be studied to assess their potential causal role in the pathogenesis of premature coronary artery disease (PCAD). Objectives were to determine the genotypic distribution of interleukin ( IL) 18 , tumour necrosis factor-α ( TNFA ) , IL6 and IL10 single nucleotide polymorphisms (SNPs) in Pakistani PCAD cases and disease free controls and to study the effect of these gene polymorphisms on the serum cytokine levels (IL18, TNFA, IL6 and IL10) and cytokine imbalance (IL18:IL10 and TNFA:IL10).

MATERIAL AND METHODS: The case-control study was carried out in National University of Sciences and Technology, Islamabad in collaboration with the Cardiovascular Genetics Institute, University College London, UK. Subjects (n=340) with >70% stenosis in at least a single major coronary artery on angiography were taken as PCAD cases along with 310 angiographically verified controls. ELISA was performed for measuring the concentrations of serum IL18, TNFA, IL6 and IL10. Genotyping was done using TAQMAN assay.

RESULTS: The risk allele frequencies (RAFs) of rs1800795 (IL6) and rs187238 (IL18) cytokine gene promoter SNPs were significantly higher in the PCAD cases as compared with the controls. Serum IL18 and IL10 levels were significantly greater in the IL18 rs187238 GG genotype patients while serum IL18 and IL6 levels were significantly higher in patients having the IL6 rs1800795 CC genotype. IL18 SNP rs1946519 significantly altered the IL18, TNFA, IL6, IL18/IL10 and TNFA/IL10 ratio levels followed by TNFA SNP rs1800629 which significantly altered the serum levels of IL18, IL18:IL-0 and TNFA:IL10 ratios.

CONCLUSIONS: The association of the selected SNPs with differential serum cytokine levels especially the cytokine imbalance points towards their potential causal role in the immune inflammatory pathogenic pathway of PCAD.