Raised inflammation markers in people with lung scarring after severe COVID sheds light on potential preventative treatments for severe respiratory conditions

Markers of inflammation, found in the bloodstream and upper airways of patients who had recovered from severe Covid infection, could be targeted with existing medications to prevent debilitating lung scarring conditions, a paper published on Wednesday 16 November in Science Translational Medicine finds.

A team of researchers from Royal Brompton and Harefield hospitals, in partnership with Imperial College London, Chelsea and Westminster Hospital and Royal Berkshire NHS Foundation Trust analysed the blood and upper airway mucus of patients who had experienced severe Covid infection and were treated in intensive care, between three and six months following their hospital discharge.

The study team compared individuals with evidence of persistent lung inflammation and scarring on chest CT with individuals whose lung inflammation had fully resolved, people who had mild Covid and healthy volunteers. They found a persistence of neutrophils, a type of white blood cell that is an important part of the immune system and helps the body fight infection, even up to six months following the acute phase of the disease with ongoing evidence of inflammation.

One of the study’s lead authors, Dr Anand Shah, respiratory consultant at Royal Brompton Hospital said, “While neutrophils can be helpful in combatting infections in the body, an excess of them can be damaging and can lead to scarring, something which we see in the lungs of some patients who had experienced a severe Covid infection. This scarring of the lungs can lead to patients becoming short of breath with persistent coughing, tiredness and weight loss; something which can take months to improve.

“Identifying neutrophils still remaining in the upper airways of patients even after they have recovered from Covid infection, provides us with a potential target to treat with existing medications to reduce inflammation and therefore reduce the severity of scarring on the lungs.”

In the UK, thousands of patients a year are diagnosed with an interstitial lung disease, a group of diseases encompassing more than 200 lung conditions that damage the lung tissue, caused by a diverse range of causes including viral infection.

Dr Aran Singanayagam, respiratory consultant at Harefield Hospital and another of the study’s lead authors said, “While this research was conducted on patients recovering from Covid, we hypothesise that the findings could apply to other respiratory infections which can lead to lung inflammation and potentially scarring, including influenza.

“Further research needs to be carried out in order to understand which inflammation markers are present in the airways of patients with other respiratory conditions so that we can then tailor treatments in order to limit the number of individuals who go on to develop an interstitial lung disease.”

Another of the study’s lead authors, Dr Peter George, consultant respiratory physician clinical lead for interstitial lung disease at Royal Brompton Hospital said, “This research was conducted in the early stages of the Covid pandemic, and quite uniquely for research conducted during this period, with seriously ill patients, many of whom were on cardiac and respiratory life support.

“This would not have been possible without the huge multi-disciplinary and multi-site research team who worked during extraordinarily difficult circumstances to improve long-term outcomes for some of the sickest patients at the time.

“We took a broad, hypothesis-free approach to the research which has led to findings which may go beyond the relevance to Covid and provide new insights into why some people develop inflammatory and scarring lung conditions. These discoveries may allow us to learn why some patients develop these serious, and at times, progressive diseases and to develop new treatments, improving patient outcomes.”

To read the full paper, visit the Science website.