New York, Apr 30 (IANS): A team of US researchers has conducted a novel cell study that reveals mechanisms which result in lethal Covid-19, and may explain long-term complications and show how Covid-19 differs from other infectious diseases.

In patients who died of the infection, Covid-19 unleashed a detrimental trifecta of runaway inflammation, direct destruction and impaired regeneration of lung cells involved in gas exchange, and accelerated lung scarring, showed the findings, led by researchers at Columbia University Vagelos College of Physicians and Surgeons and Herbert Irving Comprehensive Cancer Centre.

Though the study looked at lungs from patients who had died of the disease, it provides solid leads as to why survivors of severe Covid may experience long-term respiratory complications due to lung scarring.

"It's a devastating disease, but the picture we're getting of the Covid-19 lung is the first step towards identifying potential targets and therapies that disrupt some of the disease's vicious circuits. In particular, targeting cells responsible for pulmonary fibrosis early on could possibly prevent or ameliorate long-term complications in survivors of severe Covid-19," said Benjamin Izar, assistant professor of medicine at Columbia University.

The study, published the journal Nature, examined the lungs of 19 individuals who died of Covid-19 and underwent rapid autopsy (within hours of death) -- during which lung and other tissues were collected and immediately frozen -- and the lungs of non-Covid-19 patients.

Compared to normal lungs, lungs from the Covid patients were filled with immune cells called macrophages, the study found.

Further, the SARS-CoV-2 virus not only does destroy alveolar epithelial cells important for gas exchange, the ensuing inflammation also impairs the ability of the remaining cells to regenerate the damaged lung.

The researchers also found a large number of specific fibroblast cells, called pathological fibroblasts, which create rapid scarring in Covid-19 lungs. When the fibroblast cells fill the lung with scar tissue, a process called fibrosis, the lung has less space for cells involved in gas exchange and is permanently damaged.

--IANS

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