New Insights of Punicalagin in Alleviating Diabetic Liver Injury: Inhibition of NEK7-NLRP3 via Modulating Mitochondrial Dynamics.

Diabetic liver injury (DLI) is a chronic complication of the liver caused by diabetes mellitus, and its pathomechanism has not been fully elucidated. Punicalagin (PU), a polyphenol extracted from pomegranate peel, has physiological activities such as anti-inflammatory. In this study, the effects of PU on DLI and its molecular mechanisms were investigated. In vitro and in vivo studies were conducted using streptozotocin-induced diabetic mouse models and high glucose-induced HepG2 cells. After PU intervention, the effects of PU on DLI were assessed by histopathology, immunohistochemistry, western blot, immunofluorescence and transmission electron microscopy. The results showed that PU improved the pathological damage of liver tissue in diabetic mice, reduced the levels of inflammatory factors such as TNF-α, IL-18 and IL-1β in serum and liver, down-regulated the protein levels of NEK7, NLRP3 and Caspase1 in liver and HepG2 cells, and attenuated the fluorescence co-localization of NEK7 and NLRP3 in HepG2 cells. Additionally, PU up-regulated the expression of mitochondrial fusion-related proteins OPA1 and Mfn2 and their transfer to mitochondria, and inhibited the expression of mitochondrial fission-related proteins Drp1 and p-Drp1 (Ser616). The mitochondrial fusion inhibitor MYLS22 reversed the inhibitory effect of PU on NEK7-NLRP3 complex. In conclusion, the present study shows that PU inhibits NEK7-NLRP3 complex activation by regulating mitochondrial dynamics, thereby reducing liver inflammation and alleviating DLI.