2023-05-08 17:27:30
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New Haven/Connecticut The mostly mild myo-/pericarditis, which can occur in rare cases, especially in younger men, after vaccination with mRNA vaccines, is possibly due to an increased reaction of the innate immune system.
A research team in Science Immunology (2023; DOI: 10.1126/sciimmunol.adh3455) on the other hand do not confirm.
Cardiac complications have occasionally occurred in adolescents and young adults following the expansion of COVID vaccination. Men aged between 12 and their mid-20s were particularly affected, who complained of chest pain with palpitations, fever and shortness of breath, preferably after the 2nd dose of an mRNA vaccine.
An increase in C-reactive protein, troponin and B-natriuretic peptide indicated inflammatory damage to the myocardium with a transient reduction in cardiac output.
Complications are very rare. The US Centers for Disease Control and Prevention (CDC) estimate the incidence in 12- to 17-year-olds at 22 to 36 cases per 100,000 second doses, which is less common than COVID-19-related myocarditis, whose incidence the CDC estimates is 50.1 to 64.9 cases per 100,000 in the same age group indicates.
The myocarditis and pericarditis mostly ended mildly. Cardiac function recovered quickly and the patients were discharged from the hospital after a few days.
Nevertheless, the question arises as to what triggers the incidents. A team led by Carrie Lucas from the Yale University School of Medicine in New Haven/Connecticut therefore carried out detailed immunological tests on 17 people between the ages of 13 and 21. Most patients became ill 1 to 4 days after the 2nd dose.
The researchers initially suspected a hypersensitivity reaction to the mRNA or the lipid nanoparticles in which the mRNA is packaged. A second suspicion was an autoimmune reaction in which antibodies against SARS-CoV-2 randomly attack structures in the heart muscle.
The researchers found no confirmation for either of these hypotheses. The fact that there was no increase in the eosinophilic granulocytes, which become active in allergic diseases, spoke against hypersensitivity in the patients. An increase in Th2 cytokines, which trigger these reactions, was also not evident. Antibodies that can attack structures on the heart muscle cells were also not detectable.
In contrast, in systematic immunological studies, Lucas and co-workers found increases in various interleukins (IL-1beta, IL-1RA, and IL-15) and chemokines (CCL4, CXCL1, and CXCL10). Both point to an increased activity of the innate immune system, which possibly mistakes the vaccination for the invasion of pathogens and therefore raises the alarm.
The cytokines then apparently call natural killer cells into action. Together with cytotoxic T-cells, these could attack some muscle cells. Matrix metalloproteases, which were also increased, could then have degraded parts of the extracellular matrix. An increased activation of monocytes from the bone marrow, which clear away the debris in the tissue as macrophages, was also detectable.
on the subject
German medical journal print
aerzteblatt.de
A possible consequence is a remodeling with the replacement of heart muscle cells by connective tissue cells. This could explain the late gadolinium enhancement (LGE) in MRI that was observed in other studies in patients months after clinical recovery.
The LGE is caused by a delayed outflow of the contrast medium and is considered an indication of cardiac fibrosis. It is not known whether this has any long-term health disadvantages. Lucas recommends regular follow-up visits for affected patients.
It is unclear whether the excessive immune response was triggered by the lipid nanoparticles in which the mRNA is packaged or whether the spike proteins produced by the muscle cells are responsible. It is also unknown why some people, especially young men, experience these reactions. rme/aerzteblatt.de
#Cytokinopathy #myocarditis #mRNA #vaccination..