Skin photoaging results from the comitant effects of UVA and UVB: one side, UVA and UVB induce MMPs expression and production of epidermal keratinocytes and dermal fibroblasts which exert degradation action to dermal excellular matrix;

• 皮肤光老化为UVA和UVB共同作用的结果：一方面，UVA和UVB诱导表皮角质形成细胞和真皮成纤维细胞表达和分泌MMPs，对真皮的细胞外基质发挥降解作用； 另一方面，UVA诱导真皮成纤维细胞合成和分泌出细胞因子IL-6，通过自分泌机制促进其自身表达MMPs；