TGF-β1 Gene Polymorphism and Its Correlation with Serum Level of TGF-β1 in Psoriasis Vulgaris Among Iraqi People

PURPOSE: Many cytokines have been implicated in the pathogenesis of psoriasis, among these the transforming growth factor-beta 1 (TGF-β1) can be endorsed by different mechanisms besides inhibiting keratinocytes proliferation. The role of genetic polymorphisms of TGF-β1 has been studied in various inflammatory diseases. Our aim is to study the correlation of TGF-β1 gene polymorphism at codon 10 and 25 with the expression of serum level of TGF-β1 in a sample of Iraqi psoriatic patients compared to the control group. MATERIALS AND METHODS: A cross-sectional study involved 100 patients with psoriasis vulgaris and 50 sex- and age-matched healthy volunteers as control group. Serum and genomic DNA were prepared from peripheral blood samples. Amplification refractory mutation system–polymerase chain reaction technique (ARMS-PCR) had been applied for genotyping TGF-β1 codon 10 [rs1982073] and codon 25 [rs1800471] genetic polymorphisms. Enzyme-linked immunosorbent assay technique (ELISA) based on the sandwich principle was used for quantification of serum TGF-β1 level. Psoriasis Area and Severity Index (PASI) scoring was applied for determining the severity in psoriatic patients and classified accordingly to mild (PASI<7), moderate (PASI 7–12), severe (PASI>12) groups. RESULTS: Statistically significant difference was found in TGF-β1 gene polymorphism between psoriatic patients and control group at codon 10 (T869C) polymorphism (p=0.021) and codon 25 (G915C) polymorphism (p=0.040). No significant association was detected with the mean serum TGF-β1 level, severity of the disease, disease onset, gender, history of psoriatic arthritis, and smoking in both codons. Significant lower mean serum TGF-β1 level was found among psoriatic group (192.17 ± 531.12 ng/L) compared with controls (565.89 ± 1372.30 ng/L) (p = 0.018). Relation of mean serum TGF-β1 level with the onset of the disease was statistically significant (p = 0.004), early-onset disease group was lower (105.92 ± 68.02 ng/L) compared with the late-onset disease group (450.92 ±1027.79 ng/L). The mean serum TGF-β1 level showed no significant differences with the severity of psoriasis, gender, history of psoriatic arthritis, and smoking. CONCLUSION: Iraqi population showed a significant association between TGF-β1 gene polymorphism at codon 10 and 25 were with psoriasis susceptibility, and a significantly lower mean serum TGF-β1 level was detected in psoriatic patients.