Adenosine Blocker(Crossignal Therapeutics)

The newer adenosine diphosphate (ADP) receptor blockers ticagrelor and prasugrel are superior to clopidogrel in the long-term management of acute coronary syndrome (ACS). We evaluated the acute performance (prehospital loading) of these ADP receptor blockers in a primary percutaneous coronary intervention (PCI) for an ST-elevation myocardial infarction (STEMI).

In a retrospective, single-center registry study, data on all STEMI patients admitted for their first primary PCI between January 2007 and April 2020 were analyzed (n = 3218). The three ADP receptor blockers were mainly used during consecutive periods (clopidogrel 2007-2010, prasugrel 2011-2014, and ticagrelor 2014-2020), and were compared with risk factor-adjusted multivariate logistic regression for acute 3- and 7-day mortality and culprit artery flow before and after PCI.

Of the 3218 total patients, 47.6% (n = 1532) were treated with ticagrelor, 22.1% (n = 711) were treated with prasugrel, and 30.3% (n = 975) were treated with clopidogrel. The use of ticagrelor or prasugrel as opposed to clopidogrel was associated with better culprit artery flow before PCI (odds ratio [OR] 1.21 for moderate or good flow, 95% confidence interval [CI] 1.03-1.42, p = 0.022), as well as lower acute mortality (OR 0.66 for 3-day mortality, 95% CI 0.46-0.95, p = 0.025; and OR 0.71 for 7-day mortality, 95% CI 0.52-0.98, p = 0.039). The results in regard to acute mortality were highlighted among patients with short treatment delays (disappearing with longer treatment delays; p < 0.05 for interaction).

The newer ADP receptor blockers are associated with lower mortality and better culprit artery flow at presentation when compared with clopidogrel. There are no significant differences between the two newer drugs. As the drugs were mainly used during three consecutive periods, unmeasured confounding related to the development of cardiac care and changes in the population may contribute to the results.

Protein kinase C (PKC) is an important mediator in the cardioprotection of ischemic preconditioning and has been shown to translocate to mitochondria upon activation. However, little is known about the cellular signaling underlying the translocation of PKC isoforms to mitochondria and its age-dependence. The present study aimed to explore whether adenosine-induced translocation of PKCε to mitochondria is mediated by caveolin-3 and/or adenosine A2B receptor/PI3 kinase mediated signaling, and whether the mitochondrial targeting of PKCε is age-related. Immunofluorescence imaging of isolated mitochondria from cardiomyocytes and H9c2 cells showed that while adenosine-induced increase in mitochondrial PKCε was inhibited by adenosine A1 receptor blocker, pretreatment with adenosine A2B receptor specific inhibitor MRS 1754 or PI3K inhibitor Wortmannin did not significantly reduce adenosine-mediated increase in mitochondrial PKCε. Interestingly, adenosine-induced increase in mitochondrial translocation of PKCε was significantly blocked by suppressing caveolin-3 expression with specific siRNA. When compared to that in young adult rat hearts, the level of mitochondrial PKCε in middle-aged rat hearts was significantly lower at the basal condition and in response to adenosine treatment, along with largely decreased mitochondrial HSP90 and TOM70 protein expression. We demonstrate that adenosine-induced translocation of PKCε to mitochondria is mediated by a caveolin-3-dependent mechanism and this process is age-related, possibly in part, through regulation of HSP90 and TOM70 expression. These results point out a novel mechanism in regulating PKC function in mitochondria.