How the coronavirus destroys the lungs

Berlin, Dec 8 (Usa): We have long known about the damage a serious case of Covid-19 can do to a person’s lungs, but the exact causes of this damage are still being studied.

With a study that may help develop better treatments for people infected with the coronavirus, researchers in Germany have now shown that Covid-19 is often accompanied by severe scarring of lung tissue.

Lung failure may not be caused by the multiplication of the virus itself, but by the body’s immune system response, among other factors, says a team of researchers led by Leif-Eric Sander at the Charité Hospital in Berlin.

Their findings, published in the scientific journal Cell, indicate that the Sars-CoV-2 virus causes the sweeping cells of the immune system to initiate scarring processes that eventually damage the lungs, according to the German news agency (dpa).

This response ultimately means that Covid-19 patients must be given oxygen for a very long time or even ventilated with an artificial lung (ECMO). If Covid-19 is severe, patients often develop acute respiratory distress syndrome (ARDS).

In their study, researchers led by Sander came to the conclusion that patients’ lung tissue became scarred, thickened and inflexible. Very similar processes occur in the incurable form of lung scarring, idiopathic pulmonary fibrosis.

Scientists first examined the lung tissue of deceased patients under a microscope and found distinctive features of severe fibrosis.

“Almost all affected patients showed significant tissue damage. The majority of the alveoli were destroyed and the alveolar walls showed extensive thickening. We also found ubiquitous deposits of collagen, which is the main component of scar tissue,” said Peter Bohr of the Institute of Pathology. at RWTH University Aachen.

Sander explained that lung failure usually does not develop until two to three weeks after the first symptoms appear.

“This indicates that lung failure is not caused by uncontrolled viral replication, but by secondary host responses, including those involving the immune system.”

As a result, the team then examined immune cells in the lungs of critically ill or deceased COVID-19 patients.

They found that the lungs of infected patients experience a buildup of macrophages — immune cells that eliminate pathogens or cellular debris, but are also involved in wound healing.

In severe cases of Covid-19, they appear to come into contact with certain cells of connective tissue. These then multiply vigorously and form large amounts of collagen.

Subsequent investigations in cell cultures indicated that the SARS-CoV-2 virus triggers an erroneous reaction of macrophages. On the other hand, influenza viruses do not.

“Our data thus show similarities between Covid-19 and idiopathic pulmonary fibrosis,” said Antoine Emmanuel Saliba of the Helmholtz Institute for Research on RNA-Based Infection in Würzburg, Germany.

“This may explain why some of the risk factors for Covid-19 are also risk factors for idiopathic pulmonary fibrosis. These include underlying medical conditions, smoking, male gender and age over 60.”

Unlike idiopathic pulmonary fibrosis, the cause of which is unknown, scarring in Covid-19 patients is repairable, the researchers say. During the recovery period, the thickenings and scars at least partially dissolve again.

More detailed investigation of regressions should now contribute to the development of possible treatment options for both diseases or to prevent scarring from the start.

HF