The morphological response of the heart and spleen following acute myocardial infarction-induced sterile inflammation: a clinicopathological study

Abstract

Introduction: as an outcome of sterile inflammation-inducing acute ischemic processes, many splenic cells enter the circulatory system and migrate into the lesion, defending tissues against the spread of ischemia or enhancing necrosis.Objective: investigating the therapeutic effect of splenic morphological response to sterile inflammation-inducing myocardial infarction.Material and method: We examined the weight and structure of the heart and spleen of 106 patients deceased due to acute myocardial infarction. These data were correlated with demographic (personal) and epidemiological data, and disease history. After morphological investigation of archived myocardial and splenic tissue samples, the acute ischemia-induced structural alterations of splenic samples were quantified using a digital morpho-metric method. Results were evaluated in comparison to the myocardial ischemia coefficient. Changes in distribution of ischemia-induced cell types were characterized by defining the immunological phenotypes of macrophages (M1 vs. M2). Spleen samples from patients without history of ischemia were used as controls.Results: The modification of the spleen weight was associated with an increase in peripheral blood leucocyte levels. Our morphological analysis proved a positive correlation between the ischemia coefficient and the decrease of spleen weight. Structural analysis of splenic tissue revealed the collapse of red pulp sinusoids, a significant size decrease of the white pulp marginal zone (p<0.05), and depleted follicles with irregular margins without any distinct germinative centers. Concurrently, with the proliferation of granulocytes, the increase of M1 macrophages was observed in the myocardium, and a higher M1/M2 ratio was detected in the marginal zone of splenic follicles.Conclusion: On the background of acute ischemia, time critically determines the dynamic structural changes of the spleen. Along with reducing the marginal zone, immunomodulation targeting its cellular composition will be a putative therapeutic approach in the future.