The roles of AMPK-mediated autophagy and mitochondrial autophagy in a mouse model of imiquimod-induced psoriasis

Background: Psoriasis is a systemic inflammatory disease characterized by epidermal hyperplasia and skin inflammatory infiltrates. Inactivation of AMPK has been shown to decrease autophagy, thereby inhibiting elimination of inflammatory factors and harmful substances, and aggravating psoriasis. However, the molecular mechanism through which AMPK affects psoriasis remains to be further explored. In this study, we investigated whether AMPK regulates autophagy through the ULK1/Atg7 signaling pathway and regulates mitochondrial autophagy through the PINK1/Parkin signaling pathway, thereby affecting a mouse model of psoriasis. Methods: Imiquimod was used to induce psoriasis-like lesions on the backs of mice. The severity of skin lesions in psoriatic mice was evaluated with the skin inflammation severity score, and epidermal thickness was measured on the basis of H&E staining. RT-PCR, western blotting and immunofluorescence staining were used to detect indicators of autophagy and mitochondrial autophagy. Results: AMPK activity was inhibited in the psoriasis mouse model, the autophagy-associated proteins ULK1/Atg7 were inhibited, and the mitochondrial autophagy proteins PINK1/Parkin were also decreased. Results indicated that autophagy and mitochondrial autophagy were inhibited in the mouse model. When AMPK signaling was upregulated, ULK1/Atg7 and PINK1/Parkin were upregulated, autophagy and mitochondrial autophagy increased, and skin lesions in the mouse model were alleviated. ULK1/Atg7 and PINK1/Parkin were down-regulated when AMPK signaling was downregulated, and psoriasis-like skin lesions were aggravated in mice. These results indicated that AMPK regulates autophagy through the ULK1/Atg7 signaling pathway and regulates mitochondrial autophagy through the PINK1/Parkin signaling pathway, thus affecting the prognosis of psoriasis in the mouse model. Conclusion: AMPK affects the prognosis of psoriasis in a mouse model by regulating autophagy and mitochondrial autophagy.