Overexpression of interleukin-1 receptor antagonist provides cardioprotection against ischemia-reperfusion injury associated with reduction in apoptosis.
BACKGROUND
Interleukin-1 (IL-1) plays a role in mediating acute inflammation during ischemia-reperfusion (I/R) injury in the heart, which leads to both necrosis and apoptosis of cardiomyocytes. IL-1 receptor antagonist (IL-1ra) is known to inhibit the effects of IL-1alpha and IL-1beta, resulting in attenuated inflammatory injury, and to protect cells from IL-1beta-induced apoptosis in vitro. We hypothesized that IL-1ra overexpression would provide cardioprotection by reducing inflammation-mediated myocardial damage including apoptosis after I/R injury in vivo.


RESULTS
Rat hearts were transfected with human secreted-type IL-1ra gene by intracoronary infusion of Hemagglutinating Virus of Japan liposome and were heterotopically transplanted. IL-1ra overexpression in these hearts was confirmed by enzyme immunoassay and immunohistochemistry. Myocardial tolerance of the transplanted heart was evaluated with the use of a novel system in which the heart, existing within the recipient's abdomen, was given 30 minutes of ischemia by left coronary artery occlusion and 24 hours of reperfusion. Consequently, infarct size was decreased in IL-1ra-transfected hearts compared with control-transfected ones (26.9+/-3.2% versus 46.2+/-3.0%, P=0.001), corresponding to lower myocardial myeloperoxidase activity (2.20+/-0.69 versus 6.82+/-1.19 U/g wet wt, P<0.001) and decreased neutrophil infiltration in histological study. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling and DNA-laddering studies demonstrated that cardiomyocyte apoptosis was attenuated in IL-1ra-transfected hearts (21.4+/-3.3 versus 41.4+/-3.4%, P=0.002), correlating with reduced post I/R upregulation of Bax, Bak, and caspase-3.


CONCLUSIONS
IL-1ra introduced by gene transfection protected myocardium from I/R injury by attenuating the inflammatory response, which was associated with decreased apoptosis. This suggests a potentially important role of IL-1/IL-1ra in myocardial I/R injury and the value of IL-1ra-gene therapy for myocardial preservation.
Suzuki
K
K
Department of Cardiothoracic Surgery, National Heart and Lung Institute, Imperial College School of Medicine at the Heart Science Centre, Harefield Hospital, Middlesex, UK.
Murtuza
B
B
Smolenski
R T
RT
Sammut
I A
IA
Suzuki
N
N
Kaneda
Y
Y
Yacoub
M H
MH
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D004195:Disease Models, Animal; D015870:Gene Expression; D016027:Heart Transplantation; D006801:Humans; D066298:In Vitro Techniques; D007249:Inflammation / Q000473:pathology / Q000517:prevention & control; D053590:Interleukin 1 Receptor Antagonist Protein; D008081:Liposomes; D008297:Male; D009203:Myocardial Infarction / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D015427:Reperfusion Injury / Q000473:pathology / Q000517:prevention & control*; D018108:Respirovirus / Q000235:genetics; D012795:Sialoglycoproteins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D014162:Transfection
C507763:IL1RN protein, human; D053590:Interleukin 1 Receptor Antagonist Protein; D008081:Liposomes; D012795:Sialoglycoproteins; D009195:Peroxidase