UVB irradiation induces pro-inflammatory cytokines including interleukin-1 (IL-1) and tumor necrosis factor-α (TNFα) in the skin. TNFα stimulates the chemotaxis of inflammatory cells to the skin. These cells secrete metalloproteinases (MMPs) and other enzymes that damage the cutaneous matrix. Therefore, blocking TNFα activity could be effective in preventing the influx of inflammatory cells and subsequent collagen degradation in the skin. In addition, TNFα downregulates procollagen mRNA, and thus blockade may be beneficial to production of type I collagen. Female C57BL/6 J mice were treated with etanercept (TNFα blocker, 4 mg/kg/day) for 4 days 1 h prior to UVB irradiation (100 mJ/cm²/day for 5 days). On the 5th day mice were sacrificed 3 h after UVB exposure. Blocking TNFα significantly inhibited UVB-induced recruitment of macrophages, mast cells, and neutrophils. UVB-irradiated mice skin contained more mature collagen compared to etanercept and UVB + etanercept-treated mice. Skin from UVB + etanercept-treated mice had more collagen fragments relative to UVB-irradiated mice. Procollagen protein was lower in UVB-irradiated and UVB + etanercept-treated mice. TNFα blockade decreased decorin and TGF-β1 in UVB-irradiated mice compared to UVB alone. MMP13 was inhibited by etanercept in UVB-irradiated mice (p < 0.01). In conclusion, blockade of TNFα significantly decreased mature collagen in UVB-irradiated mice, while increasing collagen fragmentation and decreasing procollagen.

UVB辐射在皮肤中诱导促炎性细胞因子，包括白介素-1（IL-1）和肿瘤坏死因子-α（TNFα）。TNFα刺激炎性细胞对皮肤的趋化性。这些细胞分泌金属蛋白酶（MMP）和其他破坏皮肤基质的酶。因此，阻断TNFα的活性可能有效地防止炎症细胞的大量涌入以及随后胶原蛋白在皮肤中的降解。另外，TNFα下调胶原蛋白的表达，因此阻断作用可能有利于I型胶原蛋白的产生。在紫外线（100 mJ / cm ^2）照射前1小时，雌性C57BL / 6 J小鼠接受依那西普（TNFα阻滞剂，4 mg / kg /天）治疗4天。/天，共5天）。在第5天，在UVB暴露3小时后处死小鼠。阻断TNFα可以显着抑制UVB诱导的巨噬细胞，肥大细胞和中性粒细胞募集。与依那西普和经紫外线B +依那西普处理的小鼠相比，经紫外线B照射的小鼠皮肤含有更多的成熟胶原蛋白。相对于用UVB照射的小鼠，经UVB +依那西普处理的小鼠的皮肤具有更多的胶原蛋白碎片。在UVB照射和UVB + etanercept治疗的小鼠中，原胶原蛋白含量较低。与单独使用UVB相比，TNFα阻断可降低UVB辐照小鼠的除蛋白和TGF-β1。依那西普在经UVB照射的小鼠中抑制了MMP13（p  <0.01）。总之，TNFα的阻断显着降低了经UVB照射的小鼠的成熟胶原蛋白，同时增加了胶原蛋白片段化并降低了原胶原蛋白。