NIH-supported study shows the virus that causes COVID-19 can damage the heart without directly infecting heart tissue.

SARS-CoV-2, the virus that causes COVID-19, can cause damage to the heart without directly infecting heart tissue, a study supported by the National Institutes of Health shows. Research has revealed this. The study, published in the journal Circulation, specifically looked at damage to the heart in patients with SARS-CoV2-associated acute respiratory distress syndrome (ARDS), a serious lung disease that can be fatal. be. But researchers said the finding could be relevant to organs other than the heart and to viruses other than SARS-CoV-2.

Scientists have long known that COVID-19 increases the risk of heart attacks, strokes, and long-term coronavirus infections, and previous imaging studies have shown that 50% of people infected with COVID-19 These have been shown to have experienced some form of inflammation or heart damage. What scientists didn’t know was whether the damage was caused by the virus infecting the heart tissue itself, or by systemic inflammation caused by the body’s well-known immune response to the virus. .

“This is an important question, and finding the answer will open up a whole new understanding of the link between this severe lung injury and the types of inflammation that can lead to cardiovascular complications. ,” said Dr. Michel Olive, deputy director of the institute. Basic and Early Translational Research Program of the National Heart, Lung, and Blood Institute (NHLBI), part of the NIH. “Study also suggests that suppressing inflammation through treatment may help minimize these complications.”

To arrive at this discovery, the researchers focused on immune cells known as cardiac macrophages. These immune cells normally play an important role in keeping tissues healthy, but they can become inflamed in response to injury, such as a heart attack or heart failure. Researchers analyzed heart tissue specimens from 21 patients who died from SARS-CoV-2-related ARDS and compared them with specimens from 33 patients who died from causes other than COVID-19. . They also infected mice with SARS-CoV-2 and tracked what happened to the macrophages after infection.

In both humans and mice, SARS-CoV-2 infection was found to increase the total number of cardiac macrophages and to alter macrophages from their normal daily routine, leading to inflammation.

Matthias Nahlendorf, M.D., Ph.D., explains that macrophages weaken the heart and the rest of the body by not doing their normal jobs, such as maintaining the heart’s metabolism and eliminating harmful bacteria and other foreign substances. He said he would. He is a professor of radiology at Harvard Medical School and senior author of the study.

The researchers then asked whether the observed responses were due to SARS-CoV-2 directly infecting the heart, or whether SARS-CoV-2 infection in the lungs further exacerbates inflammation in cardiac macrophages. We planned a study using mice to test whether this was because the symptoms were so severe. . The study mimicked inflammatory signals in the lungs, but no actual virus was present. The results showed that even in the absence of the virus, the researchers observed the same results in both patients who died from COVID-19 and mice infected with SARS-CoV-2. The mice displayed an immune response strong enough to cause a cardiac macrophage shift.

“What this study shows is that after infection with the coronavirus, the immune system causes severe inflammation throughout the body and can cause distant damage to other organs. This is because the virus itself “This is in addition to the direct damage to the lung tissue,” he said. Nahrendorf. “These findings can also be applied more generally, as our results suggest that severe infections can send shock waves throughout the body.”

The researchers also found that blocking the immune response with neutralizing antibodies in mice halted the flow of inflammatory cardiac macrophages, preserving heart function. Professor Nahlendorf said such treatments, which have not yet been tested in humans, could help people with COVID-19 who have pre-existing conditions and who are at higher risk of severe outcomes from SARS-CoV-. He said it could be used as a preventive measure. Two related his ARDS.

Research: Grune J, Bajpai G, Ocak PT, et al. Virus-induced ARDS causes an inflammatory response in the heart, leading to cardiomyopathy. Circulation. 2024.doi:10.1161/CIRCULATIONAHA.123.066433.

Funding: This research was supported by NHLBI grants: HL139598, HL142494, HL155097, and HL149647.