Functional study of TNF-α as a promoter of polymorphisms in psoriasis.

Background: TNF-α is an important mediator in the pathogenesis of psoriasis and polymorphisms influence its transcription and could be implicated in psoriasis risk and modify certain aspects of disease, such as age at onset of psoriasis vulgaris and disease severity. Six TNF-α single nucleotide polymorphisms (SNPs) in promoter region has been identified and studied but with discordant results. The aim of this study was to evaluate whether the polymorphisms in TNF-α (-238 [rs361525], -308 [rs1800629], -857 [rs1799724], -1031 [rs1799964]) are associated with severity, itch, early onset or response to drug therapy in psoriasis in Caucasian Italian patients.

Methods: Fifty-eight psoriasis patients from Turin PSOCARE, 23 with psoriasis vulgaris and 35 with psoriatic arthritis were studied. Ready-to-use master mix for allelic discrimination of rs1800629, rs361525 and rs1799964 respectively.

Results: Our data showed a significant association between the -857(G) variant and both VAS-itch (P=0.03) and VAS-pain index (P=0.006), OR=0.2 (0.04-0.98) and OR=0.12 (0.02-0.59). No significant association between the genotypes or alleles of TNF-α SNPs has been observed with other clinic-pathologic parameters or etanercept response.

Conclusions: Our data suggest that -857 CC genotype could be involved in pain and itch severity in psoriasis patients.