Significant association of TNF-α, but not other pro-inflammatory cytokines, single nucleotide polymorphisms with intervertebral disc degeneration in Iranian population

Abstract

ObjectivesAs the important role of inflammation in pathophysiology of intervertebral disc degeneration and inconsistency regarding the role of pro-inflammatory cytokine genes SNPs, the current case-control study was designed to assess this in Iranian population. Patients and MethodsThe genomic DNA of peripheral leukocytes of 76 patients and 140 healthy controls were investigated to sequence 9 SNPs of pro-inflammatory cytokine genes of interleukin 1 (IL-1), interleukin 6 (IL-6), and Tumor Necrosis Factor α (TNF-α) family. Results‘GA’ and ‘GG’ genotype of TNF-α −308 G/A SNP were significantly associated with IVDD. While ‘GA’ was 1.93 times more frequent in patients, the ‘GG’ genotype was more common among healthy subjects (OR = 0.51, P = 0.03). The ‘G’ allele of TNF-α −238 G/A was 2.51 times more common in IVDD patients while the ‘A’ genotype was more frequent in controls with odds ratio of 0.39 (P = 0.001). Interestingly, the homozygote ‘GG’ genotype was 2.98 times more prevalent in patients (P = 0.001) while the ‘GA’ heterozygote genotype was more common in healthy individuals (OR = 0.34). The other investigated SNPs were not significantly associated with disease in this study population. ConclusionPolymorphisms of pro-inflammatory cytokine genes could take part in IVDD pathophysiology as the result of alteration in their expression levels or structures. The current study indicated significant roles of TNF-α −308 G/A and TNF-α −238 G/A SNPs with IVDD among Iranian patients. However, this study did not show any significant association between IVDD and either of SNPs of IL-1 and IL-6 genes.