Book of Abstracts - New Frontiers 2022

Abstracts of oral presentations

NECROPTOSIS MEDIATES CARDIAC DAMAGE UNDER CONDITIONS OF ISCHEMIA AND REPERFUSION: EMPHASIS ON DURATION OF REPERFUSION C. Horváth 1 , A. Szobi 1 , M. Young 2 , I. Jarabicová 1 , J. Hrdlička 3 , J. Neckář 3 , M. Lewis 2 , F. Kolář 3 , T. Ravingerová 4 , M. S. Suleiman 2 , A. Adameová 1,4 1 Faculty of Pharmacy, Department of Pharmacology and Toxicology, Comenius University, Bratislava, Slovakia; 2 Faculty of Health Sciences, Bristol Heart Institute, The Bristol Medical School, University of Bristol, Bristol, United Kingdom; 3 Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic; 4 Centre of Experimental Medicine, Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovakia Since the discovery of necroptosis, this form of regulated necrosis mediated by receptor-interacting protein kinase 3 (RIP3) and mixed lineage domain kinase domain-like pseudokinase (MLKL), was implemented in various cardiovascular diseases, including ischemia/reperfusion (IR) injury. However, a potential relationship in the extent of necroptotic damage with respect to the duration of reperfusion phase remains elusive. Therefore, Wistar rat hearts were subjected to a 30-min ischemia followed by either a brief 10-min or longer 40-min reperfusion phase. Moreover, to elucidate necroptosis activation in a chronic model of IR mimicking post-ischemic heart failure (HF), regional 30-min ischemia followed by 42-day reperfusion was used. Although 10-min reperfusion impaired cardiac function, necroptosis activation via its either pThr231/Ser232-RIP3-MLKL canonical or non-canonical pathways, including Ca 2+ /calmodulin dependent protein kinase II-mitochondrial permeability transition pore (CaMKII-mPTP) or phosphoglycerate mutase 5-dynamin-related protein 1 (PGAM5-Drp1) axes, was absent. Contrary, prolonged 40-min reperfusion caused both cardiac dysfunction and necroptotic damage evidenced by upregulation of RIP3, pSer229-RIP3 and MLKL. In support, the membrane fraction of these hearts was positive for MLKL translocation, thereby indicating robust evidence of necroptotic cell membrane disruption. Similarly, necroptosis was active in the infarcted area of postischemic HF which was accompanied by cardiac fibrosis. In contrast, increased level of pSer229-RIP3 in the non-infarcted tissue unlikely activated necroptotic cell loss and rather induced pro-inflammatory pyroptosis-like cell death. In summary, our findings suggest that prolonged reperfusion phase is needed to execute necroptosis in the heart while brief reperfusion may induce cardiac damage due to different mechanisms unlikely involving necroptosis activation. Therefore, limitation of necroptotic cell death might represent a cardioprotective strategy in the settings of chronic, but not acute myocardial IR injury.

Keywords: necroptosis, ischemia, reperfusion, heart failure, cell death

Funding:Supported by grants APVV-15-0607, APVV-20-0242, APVV-19-0540, VEGA 1/0016/20, 2/0141/18, and Medical Research Council Grant No. MR/N001389/1.

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