Researchers in Belgium have discovered a novel population of immune cells in the lungs that promote regeneration after injury caused during a viral infection, opening new doors to treating respiratory diseases. 

Severe viral infections like Covid-19 and influenza damage the alveoli – the areas of the lung that are responsible for gas exchange – via an excessive immune response called the cytokine storm. In response, the lung recruits specialised immune cells, called macrophages, that repair the damage by clearing up dead cells so new, healthy ones can develop (alevolar regeneration). 

Scientists at the GIGA institute at EARA member the University of Liège, using mice infected with influenza A, discovered that during the early recovery phase after lung damage, a short-lived, specialised population of macrophages arises in the areas that are undergoing regeneration.  

These macrophages were also found in the airspaces between the lungs from patients with suspected pneumonia, while genetically altered mice that lacked these specialised macrophages showed reduced alveoli regeneration after infection.  

Thomas Marichal, one of the researchers, said: “By targeting the amplification of these macrophages or stimulating their repair functions, we could develop therapies to improve alveolar regeneration and reduce complications from serious respiratory infections.”