Unveiling a new class of macrophages that enhance lung repair following viral infections

Researchers at the University of Liège in Belgium have uncovered a new population of macrophages—vital immune cells that respond to lung damage caused by respiratory viruses. These macrophages are pivotal in the repair of the pulmonary alveoli, the structures responsible for gas exchange. This novel discovery could revolutionize our understanding of the immune system's role after infection and lead to new regenerative treatments.

Respiratory viruses can range from causing mild symptoms to severe outcomes, as evidenced by the Covid-19 pandemic, where some cases necessitated hospitalization and led to persistent conditions known as "long Covid." These serious infections often result in extensive damage to lung tissue, particularly to the alveoli. Poor healing of these areas can lead to conditions like Acute Respiratory Distress Syndrome (ARDS) or a lasting decline in lung function, resulting in chronic fatigue and reduced exercise capacity.

While the role of macrophages in the acute phase of respiratory infections is well-documented, their contribution during the recovery phase has been less understood. A recent study by the GIGA Institute at the University of Liège has identified a new type of macrophage that appears temporarily during the early stages of lung recovery and is essential for alveolar regeneration.

The research, led by Dr. Coraline Radermecker and Prof. Thomas Marichal from the Immunophysiology Laboratory and conducted by Dr. Cecilia Ruscitti, utilized advanced techniques such as flow cytometry, fluorescence microscopy, and single-cell RNA sequencing. "Our research highlights a new and critical role for these atypical macrophages in alveolar repair," explains Coraline Radermecker. "We have characterized their features, origins, and functions, particularly their role in assisting type 2 alveolar epithelial cells, which are crucial for alveolar regeneration." These macrophages had been overlooked previously due to their expression of a marker once believed to be specific to neutrophils and their transient presence during the repair phase.

"Our findings shed light on the healing functions of these macrophages, challenging the previous notion that macrophages following viral infections are detrimental," adds Thomas Marichal. "Enhancing or stimulating these macrophages could lead to new therapies that improve alveolar repair and reduce the impact of severe respiratory infections and ARDS."

To put it in perspective, imagine the lungs as a garden ravaged by a storm (viral infection). These newly discovered macrophages function like skilled gardeners who clear the debris and help plant new seeds, enabling the garden to recover and flourish.

This breakthrough not only highlights the significance of research at the University of Liège but also opens new pathways for treating respiratory diseases.

Original source: https://www.sciencedaily.com/releases/2024/08/240802144601.htm