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Circ Cardiovasc Interv. 2016 Jan;9(1):e002547. doi: 10.1161/CIRCINTERVENTIONS.115.002547.

Natural IgM Blockade Limits Infarct Expansion and Left Ventricular Dysfunction in a Swine Myocardial Infarct Model.

Author information

1
From the Transplantation Biology Research Center, Massachusetts General Hospital, Charlestown (S.S., J.D.G., J.C.M., D.H.S., J.S.A.); Cardiac Surgery Research Laboratory, Massachusetts General Hospital, Boston, (J.L.G., J.B., J.S.A.); DecImmune Therapeutics, Cambridge, MA (M.S.H., E.M.A., F.S., R.J.P., W.N.); Program in Cellular and Molecular Medicine, Boston Children's Hospital, MA (M.C.C.); Department of Pediatrics, Harvard Medical School, Boston, MA (M.C.C.); and Division of Cardiovascular Surgery, Hospital of the University of Pennsylvania, Philadelphia (K.M.K.).

Abstract

BACKGROUND:

Acute coronary syndrome is the leading cause of mortality worldwide. However, treatment of acute coronary occlusion inevitably results in ischemia-reperfusion injury. Circulating natural IgM has been shown to play a significant role in mouse models of ischemia-reperfusion injury. A highly conserved self-antigen, nonmuscle myosin heavy chain II, has been identified as a target of pathogenic IgM. We hypothesized that a monoclonal antibody (m21G6) directed against nonmuscle myosin heavy chain II may inhibit IgM binding and reduce injury in a preclinical model of myocardial infarction. Thus, our objective was to evaluate the efficacy of intravenous m21G6 treatment in limiting infarct expansion, troponin release, and left ventricular dysfunction in a swine myocardial infarction model.

METHODS AND RESULTS:

Massachusetts General Hospital miniature swine underwent occlusion of the midleft anterior descending coronary artery for 60 minutes, followed by 1 hour, 5-day, or 21-day reperfusion. Specificity and localization of m21G6 to injured myocardium were confirmed using fluorescently labeled m21G6. Treatment with m21G6 before reperfusion resulted in a 49% reduction in infarct size (P<0.005) and a 61% reduction in troponin-T levels (P<0.05) in comparison with saline controls at 5-day reperfusion. Furthermore, m21G6-treated animals recovered 85.4% of their baseline left ventricular function as measured by 2-dimensional transthoracic echocardiography in contrast to 67.1% in controls at 21-day reperfusion (P<0.05).

CONCLUSIONS:

Treatment with m21G6 significantly reduced infarct size and troponin-T release, and led to marked preservation of cardiac function in our study. Overall, these findings suggest that pathogenic IgM blockade represents a valid therapeutic strategy in mitigating myocardial ischemia-reperfusion injury.

KEYWORDS:

immunology; inflammation; left ventricular function; myocardial infarction; troponin T

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