Small-Molecule Inhibitors of Cyclophilins Block Opening of the Mitochondrial Permeability Transition Pore and Protect Mice From Hepatic Ischemia/Reperfusion Injury

Mathieu Panel (1) , Isaac Ruiz (1) , Rozenn Brillet (1) , Fouad Lafdil (1) , Fatima Teixeira-Clerc (1) , Cong Trung Nguyen (1) , Julien Caldéraro (1) , Muriel Gelin (2) , Fred Allemand (2) , Jean-François Guichou (2) , Bijan Ghaleh (1) , Abdelhakim Ahmed-Belkacem (1) , Didier Morin (1) , Jean-Michel Pawlotsky (1)

1 IMRB - Institut Mondor de Recherche Biomédicale
2 CBS - Centre de Biochimie Structurale [Montpellier]

Background & Aims: Hepatic ischemia-reperfusion injury is a complication of liver surgery that involves mitochondrial dysfunction resulting from mitochondrial permeability transition pore (mPTP) opening. Cyclophilin D (PPIF or CypD) is a peptidyl-prolyl cis-trans isomerase that regulates mPTP opening in the inner mitochondrial membrane. We investigated whether and how recently created small-molecule inhibitors of CypD prevent opening of the mPTP in hepatocytes and the resulting effects in cell models and livers of mice undergoing ischemia/reperfusion injury Methods: We measured the activity of 9 small-molecule inhibitors of cyclophilins in an assay of CypD activity. The effects of the small-molecule CypD inhibitors or vehicle on mPTP opening were assessed by measuring mitochondrial swelling and calcium retention in isolated liver mitochondria from C57BL/6J (wild-type) and Ppif–/– (CypD knockout) mice and in primary mouse and human hepatocytes by fluorescence microscopy. We induced ischemia/reperfusion injury in livers of mice given a small-molecule CypD inhibitor or vehicle before and during reperfusion and collected samples of blood and liver for histologic analysis. Results: The compounds inhibited peptidyl-prolyl isomerase activity (half maximal inhibitory concentration values, 0.2–16.2 μmol/L) and, as a result, calcium-induced mitochondrial swelling, by preventing mPTP opening (half maximal inhibitory concentration values, 1.4–132 μmol/L) in a concentration-dependent manner. The most potent inhibitor (C31) bound CypD with high affinity and inhibited swelling in mitochondria from livers of wild-type and Ppif–/– mice (indicating an additional, CypD-independent effect on mPTP opening) and in primary human and mouse hepatocytes. Administration of C31 in mice with ischemia/reperfusion injury before and during reperfusion restored hepatic calcium retention capacity and oxidative phosphorylation parameters and reduced liver damage compared with vehicle. Conclusions:Recently created small-molecule inhibitors of CypD reduced calcium-induced swelling in mitochondria from mouse and human liver tissues. Administration of these compounds to mice during ischemia/reperfusion restored hepatic calcium retention capacity and oxidative phosphorylation parameters and reduced liver damage. These compounds might be developed to protect patients from ischemia/reperfusion injury after liver surgery or for other hepatic or nonhepatic disorders related to abnormal mPTP opening.

Mots clés: Drug; Mitochondrial swelling; PPIase activity; Mouse model

Domaines: Hépatologie et Gastroentérologie; Chirurgie; Pharmacologie

Mathieu Panel, Isaac Ruiz, Rozenn Brillet, Fouad Lafdil, Fatima Teixeira-Clerc, et al.. Small-Molecule Inhibitors of Cyclophilins Block Opening of the Mitochondrial Permeability Transition Pore and Protect Mice From Hepatic Ischemia/Reperfusion Injury. Gastroenterology, 2019, 157 (5), pp.1368-1382. ⟨10.1053/j.gastro.2019.07.026⟩. ⟨hal-02391962⟩