MRNA Vaccines and the Heart and Blood Vessels — What Is Prof. Bhakdi Warning About?

Aim of the study: COVID-19 vaccines have been linked to myocarditis, which, in some circumstances, can be fatal. This systematic review aims to investigate potential causal links between COVID-19 vaccines and death from myocarditis using post-mortem analysis.

Results: The mean age of death was 44.4 years old. The mean and median number of days from last COVID-19 vaccination until death were 6.2 and 3 days, respectively. We established that all 28 deaths were most likely causally linked to COVID-19 vaccination by independent review of the clinical information presented in each paper. The temporal relationship, internal and external consistency seen among cases in this review with known COVID-19 vaccine-induced myocarditis, its pathobiological mechanisms, and related excess death, complemented with autopsy confirmation, independent adjudication, and application of the Bradford Hill criteria to the overall epidemiology of vaccine myocarditis, suggests that there is a high likelihood of a causal link between COVID-19 vaccines and death from myocarditis.

Aim of the study: Messenger RNA (mRNA) vaccines against SARS-CoV-2 are highly effective and were instrumental in curbing the COVID-19 pandemic. However, rare cases of noninfective myocarditis, particularly in young males and typically after the second dose, have been observed.

Results: When exposed to these cytokines in vitro, human iPSC-derived cardiomyocytes (iPSC-CMs) exhibited impaired contractility, arrhythmogenicity, and proinflammatory gene expression patterns. Genistein, a phytoestrogen implicated in reducing cardiovascular inflammation, mitigated these effects in iPSC-CMs. In mice exposed to these cytokines or receiving BNT162b2 vaccination, genistein treatment reduced cardiac injury markers and attenuated infiltration of neutrophils and macrophages into the heart. These findings implicate CXCL10-IFN-γ signaling as a contributor to myocardial injury in experimental models of mRNA vaccination and indicate that pharmacologic modulation, such as with genistein, may mitigate cytokine-driven injury.

Aim of the study: Myocarditis is an established but rare adverse event following administration of messenger RNA-based coronavirus disease 2019 (COVID-19) vaccines and is most common in male adolescents and young adults. Symptoms typically develop within a few days of vaccine administration.

Results: Symptoms typically develop within a few days of vaccine administration. Most patients have mild abnormalities on cardiac imaging with rapid clinical improvement with standard treatment. However, longer term follow-up is needed to determine whether imaging abnormalities persist, to evaluate for adverse outcomes, and to understand the risk associated with subsequent vaccination. The purpose of the review is to evaluate the current literature related to myocarditis following COVID-19 vaccination, including the incidence, risk factors, clinical course, imaging findings, and proposed pathophysiologic mechanisms.

Aim of the study: The SARS-CoV-2 (severe acute respiratory syndrome coronavirus responsible for the COVID-19 disease) uses the Spike proteins of its envelope for infecting target cells expressing on the membrane the angiotensin converting enzyme 2 (ACE2) enzyme that acts as a receptor. To control the pandemic, genetically engineered vaccines have been designed for inducing neutralizing antibodies against the Spike proteins.

Results: ACE2 is present as membrane-bound on several cell types, including the mucosa of the upper respiratory and of the gastrointestinal tracts, the endothelium, the platelets, and in soluble form in the plasma. The ACE2 enzyme converts the vasoconstrictor angiotensin II into peptides with vasodilator properties. Here we review the pathways for immunization and the molecular mechanisms through which the Spike protein, either from SARS-CoV-2 or encoded by the mRNA-based vaccines, interferes with the Renin-Angiotensin-System governed by ACE2, thus altering the homeostasis of the circulation and of the cardiovascular system. Understanding the molecular interactions of the Spike protein with ACE2 and the consequent impact on cardiovascular system homeostasis will direct the diagnosis and therapy of the vaccine-related adverse effects and provide information for development of a personalized vaccination that considers pathophysiological conditions predisposing to such adverse events.

Aim of the study: The trimeric spike (S) protein on the envelope of the SARS-CoV-2 virus is the primary target structure for currently approved corona vaccines. For this reason, the two mRNA-based corona vaccines Comirnaty (BNT162b2, Pfizer/BioNTech) and Spikevax (mRNA-1273, Moderna) first induce the production of a spike monomer in body cells.

Results: In all three cell types, both BNT162b2 and mRNA-1273 produced two divergently sized monomer translation products from which one S1 subunit was formed after enzymatic cleavage. However, the number of identified S2 subunits varied between two and four depending on the cell line and mRNA used. Within a few hours, covalently bonded high-molecular complexes formed from both the spike monomers and their subunits. The arrangement of these complexes always adhered to a consistent pattern in each cell type. Particularly in AC16 cardiomyocytes, the various spike protein derivatives impaired not only cell proliferation, but also induced a pro-inflammatory response and oxidative stress. Only the secreted S1 subunit was detected as an immunogen in the supernatant of all three cell lines.