Post-mortem immunohistochemical analysis of dystrophin and matrix metalloproteinase 9 expression in sudden cardiac death due to coronary atherosclerotic disease

Sudden Cardiac Death (SCD) is an unexpected natural death due to cardiac causes that occurs within a short time period in a person without any prior condition that appears to be fatal. Coronary artery disease (CAD) and ischemic cardiac damage are the main causes of SCD. In these cases, in which the death occurs within six hours from the onset of ischemic damage, the histological myocardial changes are not specific and cannot provide clear evidence for the postmortem diagnosis. The immunohistochemical analysis was suggested to fill the gaps in the histological diagnosis of early myocardial ischemia and several markers have been analyzed [1]. Thus, this is a field constantly evolving in which the knowledge about the chronology of the inflammatory reaction and myocardial tissue response after the ischemic insult become very useful in forensic research. This study evaluates the expression of dystrophin and MMP-9 in cases of sudden cardiac death due to coronary atherosclerotic disease with and without specific microscopic signs of myocardial ischemia. These proteins have different role in cardiac tissue: dystrophin is normally expressed in cardiomyocytes contributing in stabilizing the sarcolemma during cardiac contraction and in the transmission of myofibers contraction force; MMP-9 is a protease generally associated with degradation and regulation of the extracellular matrix and recently related to regulatory mechanism for precise cellular control of biological processes. Their expression was also compared to C5b-9 complex and fibronectin expression to analyze if markers provide the same or no findings. The study reveals that dystrophin and MMP-9 show different post-ischemic time-dependent expression as, respectively, depletion of sarcolemmal staining and increasing of interstitial and leucocytes immunopositivity. Dystrophin and MMP-9 seem to be useful immunohistochemical markers for the detection of early ischemic damage. These proteins, and especially dystrophin, show early modification of expression as well as C5b-9 complex.