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Abstract: TH-OR002

Mitochondrial DNA Leakage Causes Inflammation via the cGAS-STING Axis in Cisplatin-Mediated Tubular Damage

Session Information

Category: Acute Kidney Injury

  • 103 AKI: Mechanisms

Authors

  • Maekawa, Hiroshi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan
  • Jao, Tzu-Ming, National Taiwan University Hospital, Taipei, Taiwan
  • Inoue, Reiko, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan
  • Nishi, Hiroshi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan
  • Inoue, Tsuyoshi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan
  • Nangaku, Masaomi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan
  • Inagi, Reiko, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan
Background

Cisplatin is an anti-neoplastic drug that induces tubular inflammation. However, its detailed mechanisms are not fully understood. Stimulator of interferon genes (STING) and its upstream or downstream molecules (cGAS-STING axis) play an important role in 3self/non-self DNA-triggered signal transduction, leading to inflammation. Here, we investigated the potential role of STING-mediated inflammation in cisplatin-induced tubular inflammation.

Methods

The human proximal tubular cell line, HK-2, was treated with 10 μM of cisplatin and the renal cortex of C57BL/6 mice, injected with 25 mg/kg of cisplatin for 72 h, was analyzed. The changes in cGAS-STING activation, mitochondrial DNA (mtDNA) leakage, or BAX expression were evaluated using real-time PCR, western blotting, or immunofluorescence analysis.Cisplatin and/or STING siRNA-treated HK-2 culture supernatants were analyzed using cytokine arrays and migration assays. Amlexanox and ethidium bromide (EtBr) were used for cGAS-STING axis inhibition and mtDNA depletion, respectively.

Results

In cisplatin-treated HK-2 or kidney cortex, 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, IRF3, and P65) was activated due to cisplatin-mediated phosphorylation. Cisplatin also induced inflammatory cytokine(IL-6, IL-8, ICAM-1, CXCL10, and GMCSF) production and neutrophil chemotaxis, which were ameliorated by STING knockdown (P < 0.05). Amlexanox prevented cytokine production via cGAS-STING axis inhibition (IRF3 inactivation). Interestingly, cisplatin-mediated mtDNA leakage to the cytosol activated cGAS-STING axis-mediated inflammation. In fact, EtBr-mediated mtDNA depletion inhibited the inflammation by cisplatin in HK-2. Cisplatin-induced BAX expression,which interacted with the mitochondrial permeability transition pore, suggested that mtDNA leakage was caused by the increase in BAX expression.

Conclusion

mtDNA leakage to the cytosol induces tubular inflammation by activating the cGAS-STING axis in cisplatin nephrotoxicity.