How COVID-19 damages the lungs
Infection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, can lead to massive respiratory tract damage and fatal lung failure. But why does the coronavirus impact the lungs so brutally? Partially supported by the EU-funded XHaLe project, a team of researchers set out to help answer this question and achieved new insights into the effects of SARS-CoV-2 on the lungs. The researchers focused on the differences between lung damage caused by an influenza virus and SARS-CoV-2. Their findings were published in ‘The New England Journal of Medicine’. The researchers examined tissue samples from patients who died from COVID-19 and compared them with those obtained “from patients who died from acute respiratory distress syndrome (ARDS) secondary to influenza A(H1N1) infection,” as noted in the journal article. Summarising the findings of the study in a news item on the European Research Council website, Prof. Dr Danny Jonigk from XHaLe project host Hannover Medical School states: “Firstly, we were able to confirm an already known damage to the lungs, which occurs when the walls of the alveoli become inflamed. This phenomenon makes it difficult for oxygen to enter the blood. Secondly, we found a massive number of blood clots in all sections of the blood vessels, but particularly in the finest pulmonary vessels. This is what further increases the breathlessness of coronavirus patients and is similar, but less severe, in influenza patients.”
A distinct pulmonary pathobiology
Another observation of the team involves a feature of the coronavirus “that is usually encountered only by physicians analysing tumours or autoimmune diseases,” according to Prof. Dr Jonigk, who adds that COVID-19 “apparently triggers a special form of vascularisation in the lungs, an abnormal formation of blood vessels.” This is what “fundamentally distinguishes Covid-19 from the severe lung infections caused by influenza viruses,” he states. In the journal article, the researchers also emphasise that their sample was small – it covered 7 lungs from patients who died from COVID-19, 7 lungs from patients who died from ARDS secondary to influenza A(H1N1) and “10 age-matched, uninfected control lungs.” They conclude: “In our small series, vascular angiogenesis distinguished the pulmonary pathobiology of Covid-19 from that of equally severe influenza virus infection.” They note that further research is required to fully understand the mechanisms of the vascular changes in COVID-19 victims. “Additional work is needed to relate our findings to the clinical course in these patients.” XHaLe (Hanover experimental lung research project) will run until May 2023. The project aims to examine and ultimately cure a particular group of pulmonary diseases, the so-called non-neoplastic lung diseases like chronic obstructive pulmonary disease – a chronic inflammatory lung disease that causes obstructed airflow from the lungs – and interstitial lung diseases. The latter refers to various disorders that affect the interstitial space that consists of the walls of the lung air sacs (alveoli) and the spaces around blood vessels and small airways. Interstitial lung diseases result in abnormal accumulation of inflammatory cells in lung tissue, leading to shortness of breath and cough. The lung research group involved with XHaLe has already processed more than 500 lung explants taken from patients, as noted in the project factsheet. For more information, please see: XHaLe project
Keywords
XHaLe, COVID-19, coronavirus, lung disease, SARS-CoV-2