Cardiac SARS-CoV-2 Infection, Involvement of Cytokines in Postmortem Immunohistochemical Study

Abstract

In the context of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, significant attention was given to pulmonary manifestations. However, cardiac involvement is increasingly recognized as a critical factor influencing the prognosis, leading to myocardial damage, heart failure, acute coronary syndromes, potentially lethal arrhythmic events, and sudden cardiac death. Despite these findings, there is a lack of studies detailing the necroscopic, macroscopic, and microscopic cardiac changes associated with SARS-CoV-2. This study aimed to investigate the presence of SARS-CoV-2 viral proteins in cardiac tissue using immunohistochemical techniques to assess viral tropism. The analysis of cardiac tissue samples from deceased subjects, in different stages of conservation, confirmed to be positive for SARS-CoV-2 via reverse transcriptase-polymerase chain reaction (RT-PCR), showed immunopositivity for the SARS-CoV-2-NP viral antigen in 33% of cases. Notably, the presence of leukocyte infiltrates sufficient for diagnosing lymphocytic myocarditis was not observed. The central proinflammatory cytokines involved in the pathogenetic mechanism of coronavirus disease 19 (COVID-19) were researched using the immunohistochemical method. A significant increase in cytokine expression was detected, indicating myocardial involvement and dysfunction during SARS-CoV-2 infection. These findings suggest that the immunohistochemical detection of SARS-CoV-2 viral antigens and inflammatory cytokine expression in cardiac tissue could be crucial for a proper forensic assessment of the cause of death, even in sudden cardiac death.

Keywords: COVID-19; SARS-CoV-2; cardiovascular diseases; cytokine; immunohistochemistry; inflammation; sudden cardiac death.

Figure 1

The immunohistochemical reaction against the antibody anti-SARS-CoV-2: (A) Group 1: the widespread positive immunoreaction to SARS-CoV-2 localized in myofiber; (B) Group 2: negative reaction. The graphical representation of the statistical analysis is collocated in the lower part of the figure, **** (statistically significant): p < 0.0001.

Figure 2

IL-1β immunohistochemical results: (A) Group 1’s over-expression of IL-1β, a widespread positive immunoreaction localized in myofiber; (B) Group 2’s mild reaction in the control case. The graphical representation of the statistical analysis is collocated in the lower part of the figure, **** (statistically significant): p < 0.0001.

Figure 3

IL-6 immunohistochemical results: (A) Group 1, a widespread positive immunoreaction localized in myofiber, shows the over-expression of IL-6; (B) Group 2’s mild reaction in the control case. The graphical representation of the statistical analysis is collocated in the lower part of the figure, **** (statistically significant): p < 0.0001.

Figure 4

IL-15 immunohistochemical results: (A) Group 1’s myofiber shows the over-expression of IL-5 with a widespread positive immunoreaction localization; (B) Group 2’s mild reaction in the control case. The graphical representation of the statistical analysis is collocated in the lower part of the figure, **** (statistically significant): p < 0.0001.

Figure 5

TNF-α immunohistochemical results: (A) Group 1: a diffuse positive immunoreaction localized in myofiber and vessels of TNF-α; (B) Group 2: basal reaction in the control case. The graphical representation of the statistical analysis is collocated in the lower part of the figure, **** (statistically significant): p < 0.0001.

Figure 6

MCP-1 immunohistochemical results: (A) Group 1: a mild positive immunoreaction localized in the myofiber of MCP-1; (B) Group 2: basal reaction in the control case. The graphical representation of the statistical analysis is collocated in the lower part of the figure, **** (statistically significant): p < 0.0001.