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NEW HAVEN/CONNECTICUT – Mostly mild myositis/pericarditis, which can occur in rare cases, especially in younger men, after mRNA vaccination, may be due to an overreaction of the innate immune system.
research team in Immunology (2023; DOI: 10.1126/sciimmunol.adh3455) On the other hand do not confirm.
Heart complications have occasionally occurred in teens and young adults following the expansion of the COVID vaccine. Men between the ages of 12 and their mid-20s were particularly affected, who complained of chest pain with palpitations, fever and shortness of breath, preferably after the second dose of the mRNA vaccine.
An increase in C-reactive protein, troponin, and B-natriuretic peptide indicates inflammatory damage to the myocardium with a transient decrease in cardiac output.
Complications are very rare. US Centers for Disease Control and Prevention (Center for Disease Control) estimate the incidence rate for 12- to 17-year-olds from 22 to 36 cases per 100,000 second doses, making it less common than COVID-19-related myocarditis, which the CDC estimates is 50.1 to 64.9 cases per 100,000 in the mean. Same age group.
Myocarditis and pericarditis ended slightly. Heart function quickly recovered and the patients were discharged after a few days.
However, the question arises as to what led to these incidents. Team led by Kari Lucas of Yale UniversityCity Medical College In New Haven / Connecticut, 17 people between the ages of 13 and 21 were given extensive immunological testing. Most patients became ill 1 to 4 days after the second dose.
The researchers initially suspected a hypersensitivity reaction to the mRNA or the lipid nanoparticles into which the mRNA is packaged. The second suspicion was an autoimmune reaction in which antibodies against SARS-CoV-2 indiscriminately attack structures in the heart muscle.
The researchers found no confirmation of either hypothesis. The fact that there was no increase in the eosinophil granulocytes, which became active in allergic diseases, spoke against the patients’ hypersensitivity. The increase in Th2 cytokines, which trigger these interactions, was also not evident. Antibodies that can attack structures in heart muscle cells have also not been discovered.
In contrast, in systematic immunological studies, Lucas and colleagues found increases in various interleukins (IL-1beta, IL-1RA, and IL-15) and chemokines (CCL4, CXCL1, and CXCL10). Both indicate increased activity of the innate immune system, which may mistake the vaccination for invading pathogens, thus sounding the alarm.
The cytokines then apparently activate the natural killer cells. Together with cytotoxic T cells, they can attack certain muscle cells. Matrix metalloproteases, which are also increased, can degrade parts of the extracellular matrix. It was also possible to detect increased activation of monocytes from the bone marrow, which remove debris in tissues such as macrophages.
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The possible result is remodeling by replacing myocardial cells with connective tissue cells. This may explain the delayed improvement of gadolinium (LGE) in MRI observed in other studies in patients months after clinical recovery.
LGE results from delayed flow of contrast medium and is an indicator of cardiac fibrosis. It is not known if this has any long-term health drawbacks. Lucas advises regular follow-up visits for affected patients.
It is unclear whether the excessive immune response is caused by the lipid nanoparticles into which the mRNA is packaged or whether the spiky proteins produced by muscle cells are responsible. It is also not known why some people, especially young adults, develop these reactions. © rme/aerzteblatt.de