Search

Acutemyocarditisisanin flammatorydisorderoftheheartmuscleinwhichtheseverityofinjurydependsbothonthenatureoftheoffendingagent(i.e.virus)andontheensuinginflammatoryresponse.Thede fini-tion excludes, however, the response to ischemic or toxic injury. Theheart, however, like other organs, may provide a stereotyped responsetoinjury.Followingischemicinjury,theformationoftheinfl ammasomein the heart promotes heart failure [1].Theinflammasome is a macro-molecular structure activated during injury that amplifies the responseby processing Interleukin-1β (IL-1β) and IL-18, and promotion of celldeath [2]. Viral infections may lead to either death of the virus and thecell (pyroptosis), or survival of both cell and virus with persistence ofthe infection through inhibition of the inflammasome (evasion) [3].Therearenoreportsoftheinflammasomeinacutemyocarditis.Wehy-pothesize that the viral infection or the ensuing cellular destructionleads to the formation of the inflammasome, providing an opportunityto explore inflammasome-related markers for diagnostic or prognosticpurposes. Furthermore at present day, there are no specific treatmentsfor acute myocarditis, and thus inhibitors of the inflammasome couldrepresent a new therapeutic approach.We studied samples obtainedthrough endomyocardialbiopsy in11patients with acute lymphocytic myocarditis (b4 weeks of symptomsonset) in Trieste, Italy. The diagnosis was based upon pathology exam-ination and clinical scenario (Table 1). As a comparison group westudied autopsy samples of 11 patients with acute myocarditis diag-nosed post mortem, and 5 control subjects who had died withoutacute myocarditis or other acute cardiac conditions.Weemployedimmunofluorescencestainingtodetectin flammasomeaggregatesusingantibodiesraisedagainstthescaffoldprotein,ApoptosisSpeck-like protein containing a caspase-1 recruiting domain (ASC), and/or the effector protein, caspase-1, as previously described [1].Tocharac-terizethetypeofcell,weusedadoublestainingtechniquewithantibod-ies against cardiac actin to identify cardiomyocytes, S100A4 to identifyfibroblasts, andCD31 forendothelialcells. To overcomefor the auto fluo-rescence of sarcomeric proteins, we used a solution of 1% Sudan black in70% ethanol for 5 min. Images of samples were acquired with an IX70microscope and cellSens Dimension di gital imaging software (Olympus,Central Valley, PA) using a 40× objective (400× magnification). Filtersets for each separate fluorescence-conjugated antibody were layeredtorenderacompositeimage.Theinflammasome “specks” were countedby cell type (cardiomyocyte, leukocytes, fibroblasts and endothelialcells) per high power field of view (40×). Data are presented as medianand interquartile range and non-parametric Mann–Whitney test wasused.Intracellularaggregates of ASC and/ or caspase-1 indicative of the for-mation of the inflammasome were seen in leukocytes, cardiomyocytes,fibroblasts and endothelial cells in heart biopsy samples of all 11 cases(100%), and in heart samples of 10 of 11 post-mortem cases (91%), andin none of the controls (0%, P b 0.002)(Fig. 1). ASC aggregates co-localized with caspase-1 aggregates in virtually all cases. The numberof inflammasomes was variable across cases ranging between 3 and 14specks in biopsies, and between 0 and 45 specks per field in autopsies,without statistically significant differences (data not shown). Some

Background: Multivessel coronary disease after myocardial infarction is a major risk factor for unfavorable cardiac remodeling and death due to pump failure, but underlying pathophysiologic mechanisms are still uncompletely established. Post-infarction myocardial apoptosis has been recently implicated as a cause of ongoing cell loss leading to cardiac failure. Our aim was to assess the role of post-infarction myocardial apoptosis and pro-apoptotic factor expression in the non-infarcted remote myocardium of subjects with multivessel coronary disease. Methods: Twenty-one males dying after recent myocardial infarction with permanent occlusion of the infarct-related artery were selected at autopsy. Apoptosis was assessed at viable myocardial regions remote from infarction by co-staining for in situ end-labeling of DNA fragmentation and cleaved caspase-3. Expression of pro-apoptotic factor bax and hypoxia-induced factor-1alpha was evaluated by immunohistochemistry. Results: Subjects with multivessel disease (N = 11) showed a significantly two-fold higher myocardial apoptosis in comparison to subjects with single vessel disease (N = 10) (0.9% vs. 0.5%, p = 0.013). Similarly, myocardial bax expression was increased in patients with multivessel disease (3.0% vs. 1.4%, p = 0.029). Stratification for the number of diseased coronary vessels confirmed the association between extent of coronary disease and apoptotic rates (p = 0.022). Even in subjects dying over 30 days after infarction multivessel disease remained predictive of enhanced myocardiocyte apoptosis at remote regions (p = 0.033). Conclusions: Post-infarction myocardial apoptosis and bax expression in remote left ventricular regions are significantly increased in male patients with multivessel coronary disease in comparison to those with isolated infarct-related artery occlusion. These findings suggest that apoptotic cell loss in the viable non-infarcted myocardium, possibly due ongoing ischemia, may play a relevant role in the unfavorable clinical course typical of multivessel disease after myocardial infarction. © 2004 Published by Elsevier Ireland Ltd.