Kidney Week

Abstract: TH-OR002

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

Session Information

• AKI: New Players and New Mechanisms
  October 25, 2018 | Location: 6D, San Diego Convention Center
  Abstract Time: 04:42 PM - 04:54 PM

Category: Acute Kidney Injury

• 103 AKI: Mechanisms

Authors

• Maekawa, Hiroshi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan

Hiroshi Maekawa, MD

Positions and Employment 2011-2012 Resident in the University of Tokyo Hospital, Tokyo, Japan. 2012-2013 Resident in Department of Internal medicine, Toshiba General Hospital, Tokyo, Japan. 2013-2014 Fellow in Department of Internal medicine, Toshiba General Hospital, Tokyo, Japan. 2014-2015 Fellow in Department of Nephrology and Hypertension, St. Marianna University School of Medicine, Kanagawa, Japan. 2015- PhD Student in Division of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan Other Experience and Professional Memberships 2012- Member, the Japanese Society of Internal Medicine 2013- Member, the Japanese Society of Nephrology 2013- Member, the Japanese Society for Dialysis Therapy 2014- Board Certified Member of the Japanese Society of Internal Medicine 2018- Fellow of the Japanese Society of Nephrology 2018- Fellow of the Japanese Society for Dialysis Therapy Honors 2018 Best Presentation Award Runner Up of the 2nd annual meeting of Japanese society of Uremic Toxin Research, Tokyo, Japan

• Jao, Tzu-Ming, National Taiwan University Hospital, Taipei, Taiwan

Tzu-Ming Jao,

• Inoue, Reiko, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan

Reiko Inoue,

• Nishi, Hiroshi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan

Hiroshi Nishi,

• Inoue, Tsuyoshi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan

Tsuyoshi Inoue,

• Nangaku, Masaomi, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan

Masaomi Nangaku,

• Inagi, Reiko, The Univ of Tokyo Grad Sch of Med, Tokyo, Japan

Reiko Inagi,

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.