MK2 deficiency decreases mortality during the inflammatory phase after myocardial infarction in mice

Abstract

Abstract Background: Altering the onset, intensity, or duration of inflammation can impact the recovering heart’s structure and function following myocardial infarction (MI). Substrates of MAP kinase-activated protein kinase 2 (MK2) include proteins that regulate the stability of AU-rich transcripts, including those of several pro-inflammatory cytokines. This study was to determine if MK2-deficiency impaired the inflammatory phase of post-MI wound repair. Methods and Results: Myocardial infarctions were induced by permanent ligation of the left anterior descending coronary artery in 12-week-old male MK2 +/+ and MK2 -/- littermate mice. Five days post-MI, survival was 100% in MI-MK2 -/- (n = 20) and 79% in MI-MK2 +/+ mice (n = 29; Mandel-Cox test: P < 0.05). Area at risk and infarct size were similar. Echocardiographic imaging revealed that both systolic and diastolic LV diameters were greater in MI-MK2 +/+ than MI-MK2 -/- mice. MK2-deficiency did not affect the increase in wall motion score index. Infiltration of neutrophils or monocytes did not differ significantly. Cytokine and chemokine transcripts were quantified in infarcted and non-infarcted LV tissue using qPCR arrays (QIAGEN). Three days post-MI, Ifna2 was increased and Il16 was decreased in infarcted tissue from MK2 -/- hearts, compared with infarcted MK2 +/+ tissue, whereas in the non-infarcted MK2 -/- myocardium Il27 increased and Tnfsf11 , Ccl3 , and Il1rn were decreased. Five days post-MI, Ctf16 and Il10 increased in infarcted MK2 -/- tissue whereas in the non-infarcted MK2 -/- myocardium Ccl9, Nodal, and Xcl2 increased and Il15 decreased. Conclusions: The findings of this study suggest MK2-deficiency is an advantage during the inflammatory phase of cardiac wound repair post-MI. Clinical Perspective What is new? -The effects of MAP kinase-activated protein kinase 2 (MK2) deficiency on survival, cardiac structure and function, and the inflammatory phase of wound healing following myocardial infarction were assessed using a constitutive, pan MK2-null mouse model. -MK2-deficiency reduced mortality but did not alter area at risk or infarct size post-myocardial infarction. Inflammatory cell infiltration was also unaffected. -MK2-deficiency altered the abundance of several cytokines (increased, decreased) in infarcted and non-infarcted myocardium post-MI. What are the clinical implications? -The initial phase of wound repair post-MI involves inflammation. -The risk of damage to the myocardium and mortality may be reduced by inhibition of MK2 activity during the inflammatory phase of wound healing post-MI.