Leukocyte-Expressed beta2AR Are Essential for Survival After Acute Myocardial Injury.pdf Laurel A. Grisanti Anna M. Gumpert Christopher J. Traynham Joshua E. Gorsky Ashley A. Repas Erhe Gao Rhonda L. Carter John W. Calvert Andres Pun Garcia Borja Ibanez Joseph E. Rabinowitz Walter J. Koch Douglas G. Tilley 10.25376/hra.7819943.v1 https://hra.figshare.com/articles/journal_contribution/Leukocyte-Expressed_beta2AR_Are_Essential_for_Survival_After_Acute_Myocardial_Injury_pdf/7819943 Background: Immune cell–mediated inflammation is an essential<br>process for mounting a repair response after myocardial infarction (MI).<br>The sympathetic nervous system is known to regulate immune system<br>function through β-adrenergic receptors (βARs); however, their role in<br>regulating immune cell responses to acute cardiac injury is unknown.<br>Methods: Wild-type (WT) mice were irradiated followed by isoformspecific<br>βAR knockout (βARKO) or WT bone-marrow transplantation (BMT)<br>and after full reconstitution underwent MI surgery. Survival was monitored<br>over time, and alterations in immune cell infiltration after MI were examined<br>through immunohistochemistry. Alterations in splenic function were<br>identified through the investigation of altered adhesion receptor expression.<br>Results: β2ARKO BMT mice displayed 100% mortality resulting from<br>cardiac rupture within 12 days after MI compared with ≈20% mortality<br>in WT BMT mice. β2ARKO BMT mice displayed severely reduced post-<br>MI cardiac infiltration of leukocytes with reciprocally enhanced splenic<br>retention of the same immune cell populations. Splenic retention of the<br>leukocytes was associated with an increase in vascular cell adhesion<br>molecule-1 expression, which itself was regulated via β-arrestin–dependent<br>β2AR signaling. Furthermore, vascular cell adhesion molecule-1 expression<br>in both mouse and human macrophages was sensitive to β2AR activity, and<br>spleens from human tissue donors treated with β-blocker showed enhanced<br>vascular cell adhesion molecule-1 expression. The impairments in splenic<br>retention and cardiac infiltration of leukocytes after MI were restored to<br>WT levels via lentiviral-mediated re-expression of β2AR in β2ARKO bone<br>marrow before transplantation, which also resulted in post-MI survival rates<br>comparable to those in WT BMT mice.<br>Conclusions: Immune cell–expressed β2AR plays an essential role in<br>regulating the early inflammatory repair response to acute myocardial injury<br><div>by facilitating cardiac leukocyte infiltration.</div><div><br></div> 2019-03-08 13:39:08 immune system inflammation leukocytes myocardial infarction Cardiology (incl. Cardiovascular Diseases)