Association of genetic polymorphisms in interferon-γ, interleukin-6 and transforming growth factor-β1 gene with oral lichen planus susceptibility

Abstract

Background: Oral lichen planus (OLP) is a premalignant mucocutaneous disease in which genetic factors and immune responses play a major role. Cytokines play an important role in the pathogenesis and disease progression of OLP. The aim of this study was to investigate the impact of gene polymorphisms of T helper cell subtype Th1 and Th2 cytokines, interferon-gamma (IFN-γ), interleukin-6 (IL-6) and transforming growth factor (TGF)-β1 on OLP susceptibility in a Saudi cohort.

Methods: Forty two unrelated patients with OLP and 195 healthy controls were genotyped for IFN-γ (874A/T), IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms.

Results: The frequency of genotype AT of IFN-γ (874A/T) was significantly higher while genotype AA was lower in OLP patients as compared to controls (P < 0.05). The frequency of T containing genotypes (AT + TT) was also higher in OLP patients as compared to that in controls (P = 0.003). The frequencies of allele T was higher while that of allele A lower in patients than the controls however the difference was not statistically significant (P = 0.07). There was no significant difference in the frequencies of alleles and genotypes of IL-6 (174G/C) and TGF-β1 (509C/T) polymorphisms between patient and control groups. These results indicated that genotype AT of IFN-γ (874A/T) polymorphism is associated with OLP risk and genotype AA is protective to OLP. On the other hand the polymorphisms IL-6 (174G/C) and TGF-β1 (509C/T) may not be associated with OLP risk in our population.

Conclusion: It is concluded that IFN-γ (874A/T) polymorphism is associated with the susceptibility of OLP, however further studies with large sample size involving different ethnic populations should be conducted to strengthen our results.

Keywords: Interferon-γ; Interleukin -6; Oral lichen planus; Polymorphism; Saudis; Transforming growth factor -β1.

Fig. 1

Shows the amplification of IFN-γ (874A/T) genotypes (TT, TA and AA). Lane M: 100 bp DNA marker, Lane 1 and 3: amplification of allele T, Lane 2 and 6: amplification of allele A (taking both alleles together: lanes 1 and 2 indicate TA genotype, lanes 3 and 4, TT genotype and lanes 5 and 6 AA genotype), 265 bp band for target DNA, 426 bp band for internal control

Fig. 2

Amplified DNA digested with SfaNI showing genotypes of IL-6(174G/C). Lane M: 100 bp DNA marker, Lane 1, 2, 3,5,6,7 and 8 for genotype GC (3 bands of 198, 140 and 58 bp), Lane 4 for genotype CC (uncut DNA of 198 bp), Lane 10 for genotype GG (2 bands of 140 and 58 bp)

Fig. 3

Amplified DNA digested with Bsu36 I showing genotypes of TGF-β1 (509C/T). Lane M: 100 bp DNA marker, Lane 1, 3 and 6 for genotype CT(3 bands of 441, 251and190bp), Lane 2 and 5 for genotype TT (uncut DNA of 441 bp), Lane 4 for genotype CC (2 bands of 251 and 190 bp)