Recessive dystrophic epidermolysis bullosa (RDEB) is a genetic extracellular matrix disease caused by deficiency in type VII collagen (Col VII). The disease manifests with devastating mucocutaneous fragility leading to progressive fibrosis and metastatic squamous cell carcinomas. Although Col VII abundance is considered the main predictor of symptom course, previous studies have revealed the existence of mutation-independent mechanisms that control disease progression. Here, to investigate and validate new molecular modifiers of wound healing and fibrosis in a natural human setting, and toward development of disease-modulating treatment of RDEB, we performed gene expression profiling of primary fibroblast from RDEB siblings with marked phenotypic variations, despite having equal COL7A1 genotype. Gene enrichment analysis suggested that severe RDEB was associated with enhanced response to TGF-β stimulus, oxidoreductase activity, and cell contraction. Consistently, we found an increased response to TGF-β, higher levels of basal and induced reactive oxygen species (ROS), and greater contractile ability in collagen lattices in RDEB fibroblasts (RDEBFs) from donors with severe RDEB vs mild RDEB. Treatment with antioxidants allowed a reduction of the pro-fibrotic and contractile phenotype. Importantly, our analyses revealed higher expression and deposition in skin of the relatively uncharacterized small leucine-rich extracellular proteoglycan PRELP/prolargin associated with milder RDEB manifestations. Mechanistic investigations showed that PRELP effectively attenuated fibroblasts' response to TGF-β1 stimulus and cell contractile capacity. Moreover, PRELP overexpression in RDEBFs enhanced RDEB keratinocyte attachment to fibroblast-derived extracellular matrix in the absence of Col VII. Our results highlight the clinical relevance of pro-oxidant status and hyper-responsiveness to TGF-β in RDEB severity and progression. Of note, our study also reveals PRELP as a novel and natural TGF-β antagonist with a likely dermo-epidermal pro-adhesive capacity.

隐性营养不良性大疱性表皮松解症 (RDEB) 是一种由 VII 型胶原蛋白 (Col VII) 缺乏引起的遗传性细胞外基质疾病。该疾病表现为破坏性的皮肤粘膜脆弱性，导致进行性纤维化和转移性鳞状细胞癌。尽管 Col VII 丰度被认为是症状过程的主要预测因子，但之前的研究已经揭示了控制疾病进展的突变独立机制的存在。在这里，为了研究和验证自然人类环境中伤口愈合和纤维化的新分子修饰剂，并朝着开发 RDEB 疾病调节治疗的方向发展，我们对具有显着表型变异的 RDEB 同胞的原代成纤维细胞进行基因表达谱分析，尽管具有相同的COL7A1基因型。基因富集分析表明，严重的 RDEB 与对 TGF-β 刺激、氧化还原酶活性和细胞收缩的反应增强有关。一致地，我们发现来自严重 RDEB 与轻度 RDEB 供体的 RDEB 成纤维细胞 (RDEBFs) 中对 TGF-β 的反应增加，基础和诱导活性氧 (ROS) 水平更高，胶原晶格收缩能力更强。用抗氧化剂治疗可以减少促纤维化和收缩表型。重要的是，我们的分析揭示了与较温和的 RDEB 表现相关的相对未表征的富含亮氨酸的小细胞外蛋白多糖 PRELP/prolargin 在皮肤中的较高表达和沉积。机理研究表明 PRELP 有效地减弱了成纤维细胞 对 TGF-β1 刺激和细胞收缩能力的反应。此外，在没有 Col VII 的情况下，RDEB 中的 PRELP 过表达增强了 RDEB 角质形成细胞与成纤维细胞衍生的细胞外基质的附着。我们的结果强调了促氧化状态和对 TGF-β 的高反应性在 RDEB 严重程度和进展中的临床相关性。值得注意的是，我们的研究还揭示了 PRELP 作为一种新型天然 TGF-β 拮抗剂，具有可能的真皮-表皮促粘附能力。