SUN-155 Mitochondrial DNA leakage causes inflammation via the cGAS-STING axis in cisplatin-induced acute kidney injury

Abstract

Cisplatin is an anti-neoplastic drug that induces tubular inflammation. However, its detailed mechanisms are not fully understood. Stimulator of interferon genes (STING) andits upstream or downstream molecules (cGAS-STING axis) play an important role inself/non-self DNA-triggered signal transduction, leading to inflammation. Here, weinvestigated the roles of STING-mediated inflammation in cisplatin-induced tubular injury. The human proximal tubular cell line, HK-2, treated with 20 μM cisplatin or the renal cortex of WT C57BL/6 and STING KO mice injected with 25 mg/kg cisplatin for 48 or 72 h, were analyzed. The changes in cGAS-STING axis activation, mitochondrial DNA (mtDNA)leakage, or BAX expression were evaluated using real-time PCR, western blotting, or immunostaining analysis. Cisplatin and/or STING siRNA-treated HK-2 culture supernatants were analyzed using cytokine arrays and migration assays. ethidium bromide (EtBr) were used for mtDNA depletion, respectively. In HK-2 or kidney cortex of animals treated with cisplatin, cGAS and STING expression was upregulated and translocated from the ER to the Golgi apparatus, indicating STING activation by cisplatin. Subsequently, the cGAS-STING axis(TBK-1 and P65) was activated due to cisplatin-mediated phosphorylation. Cisplatin also induced pro-inflammatory molecule(IL-6, IL-8, ICAM-1, CXCL10, and GM-CSF) production and neutrophil chemotaxis, which were ameliorated by STING knockdown (P < 0.05). Interestingly, cisplatin-mediated mtDNA leakage to the cytosol activated cGAS-STINGaxis-mediated inflammation. In fact, EtBr-mediated mtDNA depletion inhibited the inflammation by cisplatin and mtDNA transfection facilitated cGAS-STING axis and inflammation in HK-2. Cisplatin-inducedBAX expression,which interacted with the mitochondrial permeability transition pore, suggested that mtDNA leakage was caused by the increase in BAX expression. Moreover, STING KO ameliorated kidney dysfunction and tubular injury accompanied with inhibition of inflammation. mtDNA leakage to the cytosol induces tubular inflammationby activating the cGAS-STING axis in cisplatin nephrotoxicity.