Department of Immunology & Molecular Medicine, SKIMS, Srinagar 190011, India.
Department of Immunology & Molecular Medicine, SKIMS, Srinagar 190011, India.
Immunobiology. 2023 May;228(3):152390. doi: 10.1016/j.imbio.2023.152390. Epub 2023 Apr 23.
Atopic Dermatitis (AD) is a multifactorial cutaneous disorder associated with chronic inflammation of the skin. Growing evidence points to TGF-β/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-β 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.
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.
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.
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.
特应性皮炎（AD）是一种与皮肤慢性炎症相关的多因素皮肤疾病。越来越多的证据表明，TGF-β/SMAD 信号转导是介导炎症和随后组织重塑的关键因素，通常导致纤维化。本研究调查了参与 TGF-β信号转导的核心转录因子 SMAD3 遗传变异（rs4147358）在 AD 易感性中的作用及其与 AD 患者的 SMAD3 mRNA 表达、血清 IgE 水平和对各种过敏原的敏感性的关系。
共纳入 246 例受试者，包括 134 例 AD 患者和 112 例匹配的健康对照，采用 PCR-RFLP 法对 SMAD3 内含子 SNP 进行基因分型。采用实时定量 PCR（qRT-PCR）法测定 SMAD3mRNA 的表达，用化学发光法测定维生素 D 水平，用 ELISA 法测定总血清 IgE 水平。进行体内过敏试验以评估对屋尘螨（HDM）和食物过敏原的过敏反应。
AD 患者中突变基因型 AA（病例：19.4%，对照：8.9%）（OR=2.8，CI=1.2-6.7，p=0.01）的频率显著升高。与野生型等位基因“C”相比，突变等位基因“A”也使 AD 的风险增加 1.9 倍，表明携带 A 等位基因的个体患 AD 易感性的风险更高（OR-1.9，CI=1.3-2.8，p<0.001）。此外，外周血中 SMAD3mRNA 的定量分析显示，AD 病例的表达增加了 2.8 倍。分层分析显示，突变 AA 基因型与血清维生素 D 水平不足（p=0.02）和 SMAD3mRNA 过表达与 HDM 致敏（p=0.03）相关。此外，未观察到基因型与 SMAD3mRNA 表达之间存在显著关联。
本研究表明，SMAD3 内含子 SNP 与 AD 发病风险显著相关。此外，SMAD3mRNA 的过表达及其与 HDM 致敏的关联突出了该基因在 AD 发病机制中的可能作用。
