Chronic exposure to UVB radiation causes photoaging, immunosuppression, and ultimately photocarcinogenisis through the generation of reactive oxygen species (ROS). The ability of natural compounds in neutralizing the effects of oxidative stress is being explored with increased interest. Silk sericin, a biopolymer is reported to have diverse biological properties. In an effort to make the silk sericin pure, more effective and multifunctional, we have recombinantly expressed both functional sericin as well as sericin-cecropin B fusion proteins. Herein, we studied the antioxidant and anti-UVB potential of recombinant sericin and sericin-cecropin B proteins against oxidative stress using human primary dermal fibroblast cells. Treating the cells with recombinant sericin (RS) or sericin-cecropin B (RSC) prior to exposure to UVB and H2O2, effectively increased the cell viability by approximately 30% and 50%, respectively, in comparison to non-treated control. The protective effects were further evident in terms of significant reduction of LDH in oxidatively challenged cells treated with RS and RSC. A reduction in LDH release of at least 16 and 33% was observed with RS and RSC treatments, respectively, in comparison to exposed control. Further, elevated levels of catalase and superoxide dismutase (SOD) activity were observed. Importantly, the RSC fusion protein exhibited enhanced protective effects than cells treated with RS alone. Our results demonstrate that the functional attributes of cecropin B along with sericin activity in the fusion protein conferred enhanced protection against UVB- and H2O2-induced oxidative damage in human dermal fibroblasts. The improved antioxidant activity of recombinant sericin fusion biopolymer has great potential as a promising therapeutic agent for ROS-induced skin diseases.

中文翻译：

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丝胶-天蚕素融合蛋白对成人真皮成纤维细胞氧化应激的增强抗氧化特性

长期暴露于 UVB 辐射会导致光老化、免疫抑制，并最终通过产生活性氧 (ROS) 导致光致癌。人们越来越感兴趣地探索天然化合物中和氧化应激影响的能力。据报道，丝胶是一种生物聚合物，具有多种生物学特性。为了使丝胶更纯、更有效和多功能，我们重组表达了功能性丝胶以及丝胶-天蚕素 B 融合蛋白。在此，我们使用人原代真皮成纤维细胞研究了重组丝胶蛋白和丝胶蛋白-天蚕蛋白 B 抗氧化应激的抗氧化和抗 UVB 潜力。在暴露于 UVB 和 H2O2 之前，用重组丝胶 (RS) 或丝胶-天蚕素 B (RSC) 处理细胞，与未处理的对照相比，细胞活力分别有效地增加了约 30% 和 50%。在用 RS 和 RSC 处理的氧化挑战细胞中 LDH 显着减少方面，保护作用进一步明显。与暴露对照相比，RS 和 RSC 处理分别观察到 LDH 释放减少至少 16% 和 33%。此外，还观察到过氧化氢酶和超氧化物歧化酶 (SOD) 活性水平升高。重要的是，RSC 融合蛋白表现出比单独用 RS 处理的细胞增强的保护作用。我们的结果表明，天蚕素 B 的功能特性以及融合蛋白中的丝胶活性增强了对 UVB 和 H2O2 诱导的人真皮成纤维细胞氧化损伤的保护。