Lisovyy O. Lipoxygenase and epoxygenase pathways of arachidonic acid metabolism at acute myocardial infarction: molecular aspects and gene therapy prospects

Dissertation is devoted to the study of molecular aspects of lipoxygenase and epoxygenase pathways of arachidonic acid metabolism involvement in processes occurring during anoxia-reoxygenation of cardiomyocytes and heart ischemia-reperfusion in vivo. In experiments on cultivated cardiomyocytes with anoxia-reoxygenation (AR) and in vivo using rat model of heart ischemia-reperfusion (IR) we determined ALOX5 and CYP2J2 expression in isolated cardiomyocytes and in heart tissue at normal conditions and after experimental simulation of myocardial infarction as well as influence of ALOX5 silencing on myocardial cell death. ALOX5 silencing was quantified using real-time PCR, semi quantitative PCR, and evaluation of LTC4 concentration in cardiac tissue. A 4.7 fold decrease of ALOX5 expression (P<0.05) was observed in isolated cardiomyocytes together with a reduced number of necrotic cardiomyocytes (P<0.05), increased number live (P<0.05) and unchanged number of apoptotic cells during AR of cardiomyocytes. Downregulation of ALOX5 expression in myocardial tissue by 19% (P<0.05) resulted in a 3.8-fold reduction of infarct size in an open chest rat model of heart IR (P<0.05). Thus, RNAi targeting of ALOX5 protects heart cells against IR injury both in culture and in vivo. It was also shown that treatment with non-specific 5-lipoxygenase inhibitor quercetine exerts protective effect on cardiomyocytes during anoxia-reoxygenation whereas specific epoxygenase 2J2 inhibitor MS-PPOH was inefficient at the same conditions. G-50>T promoter polymorphism of CYP2J2 is not associated with acute coronary syndrome in Ukrainian population. Obtained data supports opinion about pathogenic role of 5-lipoxygenase pathway at anoxia-reoxygenation of cardiomyocytes and heart ischemia-reperfusion in vivo. Targeted ALOX5 silencing protects heart cells against IR injury both in culture and in vivo.