Analysis of intronic SNP (rs4147358) and expression of SMAD3 gene in Atopic Dermatitis: A case-control study.

BACKGROUND: Atopic Dermatitis (AD) is a multifactorial cutaneous disorder associated with chronic inflammation of the skin. Growing evidence points to TGF-ß/SMAD signaling as a key player in mediating inflammation and the subsequent tissue remodeling, often resulting in fibrosis. This study investigates the role of a core transcription factor involved in TGF-ß signaling i.e., SMAD3 genetic variants (rs4147358) in AD predisposition and its association with SMAD3 mRNA expression, serum IgE levels, and sensitization to various allergens in AD patients. METHODS: A total of 246 subjects including 134 AD cases and 112 matched healthy controls were genotyped for SMAD3 intronic SNP by PCR-RFLP. mRNA expression of SMAD3 was determined by quantitative Real-Time PCR (qRT-PCR), Vitamin-D levels by chemiluminescence, and total serum IgE levels by ELISA. In-vivo allergy testing was performed for the evaluation of allergic reactions to house dust mites (HDM) and food allergens. RESULTS: A significantly higher frequency of mutant genotype AA (cases: 19.4% vs controls: 8.9%) (OR = 2.8, CI = 1.2 - 6.7, p = 0.01) was observed in AD cases. The mutant allele 'A' also showed a 1.9-fold higher risk for AD compared to the wild allele 'C' indicating that the carriers of the A allele have a higher risk for AD predisposition (OR-1.9, CI = 1.3-2.8, p < 0.001). In addition, quantitative analysis of SMAD3 mRNA in peripheral blood showed 2.8-fold increased expression in AD cases as compared to healthy controls. Stratification analysis revealed the association of the mutant AA genotype with deficient serum Vitamin D levels (p = 0.02) and SMAD3 mRNA overexpression with HDM sensitization (p = 0.03). Furthermore, no significant association of genotypes with SMAD3 mRNA expression was observed. CONCLUSION: Our study indicates that SMAD3 intronic SNP bears a significant risk of AD development. Moreover, overexpression of SMAD3 mRNA and its association with HDM sensitization highlights the possible role of this gene in AD pathogenesis.

Unveiling the TGF- ß1 paradox: Significant implication of TGF- ß1 promoter variants and its mRNA and protein expression in atopic dermatitis.

BACKGROUND: Atopic Dermatitis (AD) is a chronic inflammatory skin disorder with evidence of lichenification in later stages. There is mounting evidence supporting the role of TGF- ß1 in mediating inflammation as well as subsequent tissue remodeling, often resulting in fibrosis. Given the role of genetic variants in the differential expression of TGF-ß1 in various diseases, this study seeks to ascertain the role of TGF-ß1 promoter variants (rs1800469 and rs1800468) in AD susceptibility, as well as their association with TGF- ß1 mRNA expression, TGF- ß1 serum levels and skin prick test positivity in Atopic Dermatitis patients. METHODS: An aggregate of 246 subjects including 134 AD cases and 112 matched healthy controls were genotyped for TGF-ß1 promoter polymorphisms by PCR-RFLP. TGF- ß1 mRNA was quantified by quantitative Real-Time PCR (qRT-PCR), Vitamin-D levels by chemiluminescence, and serum TGF- ß1, and total IgE levels were determined by ELISA. In-vivo allergy testing was performed for the evaluation of allergic reactions to house dust mites and food allergens. RESULTS: A higher frequency of TT genotypes of rs1800469 (OR = 7.7, p = 0.0001) and GA+AA genotypes of rs1800468 (OR-4.4, p < 0.0001) were observed in AD cases than those in controls. Haplotype analysis demonstrated that TG haplotype carriers had an increased risk of AD (p = 0.013). Quantitative analysis revealed a significant upregulation of both mRNA (p = 0.0002) and serum levels (p < 0.0001) of TGF- ß1 with a substantial positive correlation between them (Correlation coefficient=0.504; p = 0.01). Moreover, serum TGF-ß1 levels were associated with quality of life (p = 0.03), the severity of the disease (p = 0.03), and House dust mite allergy (p = 0.01) whereas TGF-ß1 mRNA levels positively correlated with disease severity(p = 0.02). Stratification analysis revealed that the TT genotype of rs1800469 was associated with higher IgE levels (p = 0.01) and eosinophil percentage(p = 0.007) whereas the AA genotype of rs1800468 correlated with elevated serum IgE levels (p = 0.01). Besides, no significant association of genotypes with mRNA and serum expression of TGF-ß1 was observed. CONCLUSION: Our study indicates that TGF-ß1 promoter SNPs bear a significant risk of AD development. Moreover, upregulation of TGF-ß1 mRNA and serum levels and their association with disease severity, quality of life, and HDM allergy suggests its role as a diagnostic/prognostic biomarker that could help in the development of new therapeutic and prevention strategies.