Session Information
Session Type: Abstract Submissions (ACR)
Background/Purpose
A significant amount of myocardial damage during a myocardial infarction (MI) occurs during the reperfusion stage which is known as ischaemic reperfusion (I/R) injury and can account for up to 50% of cell death. Systemic lupus erythematosus (SLE) is associated with increased cardiovascular morbidity and mortality. Many of these patients are treated with the drug Hydroxycholoroquine (HCQ) and whilst retrospective studies have suggested HCQ lowers the risk of suffering an MI, inevitably many still do. This study investigates the effects of HCQ on myocardial survival during reperfusion (I/R injury).
Methods
Male Sprague-Dawley rats (200-220g) were dosed by gavage with 200mg/kg of HCQ once a day for three days which yielded blood concentrations of HCQ in line with that seen in patients (1-2µg/ml). Rats underwent myocardial I/R injury by occlusion of the left anterior descending (LAD) coronary artery, with reperfusion after 40 mins. Twenty-four hours later animals were sacrificed, hearts excised, the LAD re-occluded and the hearts perfused with Evans Blue dye (to label perfused myocardium). Hearts were then cut into 1mm slices and stained with TTC to label viable myocardium). Infarct size (IS) was calculated as entire myocardium area – area of viable tissue. Area at risk (AAR) was then calculated from entire myocardium area – perfused myocardium from the area of viable myocardium. In vitro experiments were performed in neonatal rat cardiomyocytes isolated from 1-2 day old rat pups and exposed to simulated I/R injury using a hypoxic chamber. Protein lysates were collected and processed for use in western blot.
Results
In vivo, HCQ resulted in a significant reduction in infarct size (IS) presented as a percentage of area at risk (AAR) (area supplied by the LAD). Control rats had an IS/AAR of 20.36% (n=5)), which was significantly reduced in the presence of HCQ to 13.41% (n=5)(p=0.0159). When the hearts were probed for the protective kinase ERK, there was a significant increase in the phosphorylation of ERK in the presence of HCQ – control 0.11 for p-p42 and 0.14 for p-p44 versus HCQ 0.55 (p=0.029) for p-p42 and 0.52 (p=0.020) for p-p44. In vitro data has also shown that pre-treatment of neonatal rat cardiomyocytes with HCQ prior to simulated I/R injury was protective, specifically reducing apoptosis. This was observed by a reduction of 43.74% (p value <0.0001) in the number of TUNEL positive cells during reoxygenation and also confirmed thorough probing for cleaved caspase-3. A cell viability assay confirmed that HCQ caused a reduction in total cell death in cells exposed to simulated I/R injury of 57.85% (p value = 0.0213). Correlating with decreased cell death, enhanced ERK phosphorylation in HCQ treated cells was observed in a dose-dependent manner with no significant differences in p38, JNK nor Akt. Cells treated with HCQ and exposed to simulated I/R injury were incubated with the ERK inhibitor U1026 and protective effects of HCQ as assessed via caspase-3 cleavage were completely reversed.
Conclusion
HCQ is cardioprotective in this in vivo I/R injury model and phosphorylation of the pro-survival kinase ERK is enhanced in the presence of HCQ. Mechanistic experiments in vitro demonstrate that HCQ protection is ERK dependent.
Disclosure:
L. Bourke,
None;
V. Taylor,
None;
J. McCormick,
None;
C. Pericelous,
None;
J. Franklin,
None;
D. Stuckey,
None;
M. Lythgoe,
None;
A. Stephanou,
None;
Y. Ioannou,
None.
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/hydroxycholorquine-is-cardioprotective-in-an-in-vivo-rat-model-of-myocardial-ischaemic-reperfusion-injury/