2023-09-04 12:35:33
by Health Editor
In half of the cases, patients hospitalized for Covid with heart damage suffer from heart complications for months. Humanitas researchers have discovered the mechanism
There are thousands of immune cells circulating in our body that can recognize and potentially attack our organs and tissues. It exists for a tolerance program which, if active, prevents aggression to the detriment of our body. A study conducted by Humanitas researchers involving patients with cardiac sequelae from Covid has shown that the encounter of some of these immune cells with SARS-CoV-2 can accidentally turn off the tolerance program, unleashing the cells against the tissue cardiac. The results were published in the journal Circulation and pave the way for a better understanding of Long Covid: the identified autoimmune mechanism, which can persist for months after the end of the infection, could also explain other symptoms typically associated with this pathology.
The research stems from the joint work between the group of Marinos Kallikourdis, head of the Humanitas Adaptive Immunity Laboratory, and the group of Gianluigi Condorelli, director of the Humanitas Cardiovascular Department, with the support of the team of Marco Francone, head of Imaging Cardiovascular of Humanitas, all three professors at Humanitas University. The study was conducted on blood samples from patients hospitalized for COVID-19 at the IRCCS Istituto Clinico Humanitas, and was also possible thanks to the support of the Ministry of University and Research and the Umberto Veronesi ETS Foundation.
Long Covid and cardiovascular complications
Cardiovascular complications are frequent in patients recovered from Covid-19, especially in those who have suffered from a severe form of the infection – explains prof. Gianluigi Condorelli, director of the Cardiovascular Department of Humanitas and professor at Humanitas University- Studies tell us that half of patients hospitalized for Covid-19 with high levels of troponin (an indicator of damage to heart tissue) have cardiac magnetic resonance abnormalities even at 6 months of recovery. In general, the damage suffered by organs and tissues following an infection such as Covid-19 can be explained by two phenomena, which can coexist: direct aggression by the virus and collateral damage due to the immune response triggered by the virus and then turned – erroneously – against the fabric. The second phenomenon capable of explaining the damage to tissues that Sars-CoV-2 did not attack directly – continues prof. Condorelli- In addition to explaining why this damage persists even after the infection, that is, when the virus is no longer present, as happens in Long Covid.
The loss of immunological tolerance
To understand what happens in the case of cardiovascular complications, the researchers involved patients hospitalized at the IRCCS Istituto Clinico Humanitas with Covid-19, focusing in particular on those who, 6 months after discharge, still showed, on MRI, a heart damage. These are people who had no history of cardiovascular disease behind them. Analyzing the samples of these patients, we discovered an abnormal activation of some types of white blood cells – the B cells, those responsible for producing antibodies – and we identified the presence of some auto-antibodies that recognize the tissues of the heart. As we later demonstrated in a laboratory study, these auto-antibodies are absent in patients hospitalized with COVID-19 but without heart damage and are sufficient to trigger an autoimmune reaction against the heart, explain researchers Marco Cremonesi and Arianna Felicetta, first authors of the Circulation study. The data of the study, although indicative and derived from a small number of patients, support our starting hypothesis – says prof. Marinos Kallikourdis, head of the Humanitas Adaptive Immunity Laboratory and professor at Humanitas University – heart damage is compatible with a mechanism called “loss of immunological tolerance”. The hypothesis of the Humanitas researchers that during the Covid-19 infection some immune cells made to recognize our tissues are accidentally stimulated by the encounter with the virus and turn off the brake which, under normal conditions, prevents them from orchestrating a aggression against our body.
The variety of Long Covid symptoms
The loss of immunological tolerance could also explain the variety of symptoms of Long Covid: although it is a single mechanism, it can in fact produce very different clinical consequences, depending on the type of specificity of the immune cells that lose tolerance after the accidental encounter with Sars-CoV-2- continues Kallikourdis- This means that the same mechanism could explain other autoimmune reactions, for example against nervous tissue, typical of Long Covid. If further confirmed, the results obtained will help demonstrate the decisive role of immunity in heart disease and the efficacy demonstrated by some immunomodulatory drugs in the treatment of Covid patients.
September 4, 2023 (change September 4, 2023 | 12:30)
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