Study shows how lung macrophages increase allergic inflammation in the lungs

Study shows how lung macrophages increase allergic inflammation in the lungs

Alveolar macrophages are immune cells that live in the tiny air sacs in the lungs. Under normal conditions, these cells act as sentinels by keeping the lungs healthy, supporting breathing, and preventing unnecessary immune reactions.

However, new work led by Prof. Bart Lambrecht and Prof. Martin Guilliams (both VIB-UGent Center for Inflammation Research) shows that these macrophages can undergo a dramatic change during allergic reactions. Instead of calming down the immune system, they switch into an inflammatory mode that actively fuels allergy-related pneumonia.

Alveolar macrophages have long been considered peacekeepers in the lungs. Our results show that they can do the opposite in allergic reactions and actually help drive inflammation.”

Stijn Verwaerde, VIB

Remodeling of the lungs

Using an advanced mouse model that allowed researchers to precisely track and manipulate these lung cells, the team discovered that exposure to allergens causes alveolar macrophages to emit signals that attract other immune cells to the lungs. This influx increases inflammation and worsens allergic reactions. Remarkably, it was also found that the macrophages fuse to form large “giant cells” that change the structure of the lung tissue in the event of an allergy.

These results challenge the long-standing view that alveolar macrophages are stable cells that resist change. Instead, the study shows that they are surprisingly flexible and can be reprogrammed by their environment, sometimes with harmful consequences.

The discovery has important implications for understanding allergic lung diseases such as asthma. Current treatments primarily target other immune cells or inflammatory molecules. By identifying alveolar macrophages as active triggers of allergic inflammation, the study opens new avenues for exploring therapies that could prevent or reverse their harmful switching, potentially reducing inflammation while preserving essential lung function.

Taken together, the results offer a new perspective on how allergic reactions escalate in the lungs and highlight the complex, double-edged role of immune cells, which are essential for health but can contribute to disease under the wrong conditions.

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