Fucoidan-proanthocyanidins nanoparticles protect against cisplatin-induced acute kidney injury by activating mitophagy and inhibiting mtDNA-cGAS/STING signaling pathway.

Fucoidan (FU) is a natural polymer from marine organisms, which has been widely studied and applied in drug delivery. In this study, FU nanoparticles loaded with proanthocyanidins (PCs) (FU/PCs NPs) were prepared and their effect and mechanism in protecting cisplatin-induced acute kidney injury (AKI) were studied. The in vitro studies confirmed that FU/PCs NPs increased the antioxidant activity of free PCs and protected the death of human kidney proximal tubule (HK-2) cells induced by cisplatin. Further mechanism studies showed that FU/PCs NPs protected the mitochondrial damage induced by cisplatin, activated mitophagy, inhibited the release of mitochondrial DNA (mtDNA), and inhibited the cGAS/STING signal pathway. The in vivo results also indicated that FU/PCs NPs protected cisplatin-induced AKI, including inhibiting the increase of blood urea nitrogen (BUN) and serum creatinine (SCr) levels induced by cisplatin. The mechanism studies confirmed that cisplatin induced an increase in the expression of mitophagy-related protein Pink/Pakrin, mitochondrial mtDNA release and cGAS/STING expression in mice kidney tissues. Pre-administration of FU/PCs NPs further activated mitophagy, as well as inhibiting mtDNA release and cGAS/STING expression. In conclusion, our research proved the role of mitophagy-mtDNA-cGAS/STING signal was involved in cisplatin-induced AKI.