The study produces photographs of the myocardial transcription landscape of COVID-19

In a recent study posted on medRxiv* Preprint server, researchers have profiled the cardiac tissue transcriptome of patients with coronavirus disease 2019 (COVID-19).

Background

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus that causes COVID-19, is involved in lung and extrapulmonary diseases, including cardiac complications. Acute myocardial damage has been observed in the early stages of COVID-19. Moreover, increasing evidence indicates persistent cardiac dysfunction after recovery from acute illness. Individuals who recover with COVID-19 may be at higher risk of arrhythmias, heart failure, chest pain, and vascular complications than individuals who are not infected with SARS-CoV-2.

Autopsy of COVID-19 patients revealed the presence of SARS-CoV-2 negative sense ribonucleic acid (RNA), indicating acute viral replication in the myocardium. Cardiac complications are not unique to COVID-19. Influenza A virus (IAV) is also associated with myocardial infarction, atrial fibrillation, endocarditis, and tachycardia. However, it is unclear whether cardiomyocyte damage is associated with the presence of the virus or the secondary effects of the immune response on IAV infection.

Therefore, the contribution to heart-related complications induced by IAV or SARS-CoV-2 infection is unclear and controversial. Analysis of the transcriptome from the patient’s myocardial tissue may serve as a unique tool for characterizing the host’s response to extrarespiratory viral infections.

About research

In this study, researchers profiled the myocardial transcriptome of COVID-19, pandemic H1N1 (pH1N1) influenza and used target-space transcriptome to control patients. Myocardial tissue was obtained from the patient at the time of approval of the postmortem biopsy by the family. The patient’s infection status was confirmed by quantitative reverse transcription-polymerase chain reaction (RT-qPCR). Tissue microarray (TMA) was performed on SARS-CoV-2, pH1N1, and the core of control patients. Immunohistochemical analysis Spike protein Of SARS-CoV-2. RNA profiling was performed using the Nanostring GeoMX Digital Spatial Profiler (DSP) on a newly prepared TMA slide.

GeoMX DSP measured RNA abundance of over 1800 genes, including 4 SARS-CoV-2 specific genes, 22 add-in COVID-19-related genes, 2 negative control genes, and 32 internal reference genes. .. The region of interest (ROI) transcriptome was quantified and overall 48 ROIs were analyzed, including 16 COVID-19, 4 pH1N1 and 28 controls. Gene set enrichment analysis (GSEA) was performed using the molecular signature database, C2 and C5 categories, and gene sets obtained from the Kyoto Encyclopedia (KEGG) pathway of genes and genomes.

result

Heart tissue samples were obtained at necropsy from 7 SARS-CoV-2, 2 pH1N1 and 6 control patients. Immunohistochemical analysis revealed edema in all COVID-19 patients and myocarditis in one patient. All COVID-19 samples lacked viral RNA, as inferred from RNAscope analysis. Increased expression of interferon (IFN) responsive genes was observed in patients with pH 1N1 compared to patients with COVID-19. In contrast, expression of chemokine ligands such as CC Motif Chemokine Ligand 15 (CCL15) was elevated in COVID-19 patients. Significant differential expression (DE) of synovial sarcoma X family member 1 (SSX1) and CCL15 was observed with the COVID-19 set compared to the control.

In addition, heat shock protein family A member 1A (HSPA1A) was significantly upregulated in the COVID-19 sample compared to the control. The antiviral IFN response was more robust in the pH1N1 sample than in the control sample. Comparing overlapping DE genes among the three cohorts revealed COVID-19 exclusive upregulation of 16 genes and downregulation of 24 genes. Among the upregulated ones were the inflammatory response-related NFAT-activating protein with the ITAM motif 1 (NFAM1) gene and the tumor necrosis factor receptor gene TNFRSF10A. In particular, the interleukin 1-like receptor 1 (IL1RL1), a cardioprotective gene encoding a tumorigenic 2 (ST2) suppressor, was downregulated.

GSEA revealed downregulation of the complement activation pathway and IFN-related gene set in the COVID-19 sample compared to the pH1N1 sample. In addition, the gene set upregulated in the COVID-19 sample compared to the pH1N1 sample was associated with deoxyribonucleic acid (DNA) damage and repair, cell cycle, and cell abnormalities. Compared to the control sample, the COVID-19 sample showed upregulation of the cell death and aging-related gene set. The COVID-19 sample was also significantly enriched with the bone marrow and leukocyte gene sets. Finally, we performed gamma-H2A histone family member X (γ-H2AX) staining, which is a characteristic biomarker of DNA damage. Two COVID-19 samples produced a significant γ-H2AX signal indicating DNA damage in cardiac tissue.

Conclusion

Unlike pH1N1 influenza, the gene clusters altered by COVID-19 were primarily involved in DNA damage, repair pathways, and cell cycle arrest pathways. LIG4, a DNA ligase involved in DNA repair, was significantly upregulated in COVID-19 samples, suggesting that SARS-CoV-2-induced DNA damage in heart cells may have caused its expression. is showing. Gene clusters associated with specific mitochondrial function and metabolic regulation were downregulated in COVID-19 specimens. Changes in mitochondrial activity elicited by SARS-CoV-2 may allow the avoidance of mitochondrial-mediated innate immunity.

Overall, this study provided important insights into the transcriptomics profile of cardiac tissue in deceased COVID-19 subjects. However, there are some limitations, including limited analysis of autopsy subjects that are unlikely to reflect the comprehensive spectrum of COVID-19, and especially the small sample size of the pH1N1 cohort.

*Important Notices

medRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.