According to the National Center for Health and Statistics, under the Centers for Disease Control and Prevention (CDC), roughly 30% of both adults and children have allergy symptoms. Therefore, over 100 million people in the United States are affected by allergies. Common allergic diseases include asthma, eczema, and season and food allergies. Once diagnosed physicians may prescribe decongestants, corticosteroids, and other allergen treatments to target symptoms. The type of allergy and severity of the disease best informs which treatment is optimal. Unfortunately, there is not “cure”, but patients can invest in allergy vaccinations that help build lasting tolerance to specific allergens.
Allergies result from overreactions by the immune system to external stimuli like pollen, food, dust particles, and others. In the context of allergies, our immune system detects these particles as extremely harmful to our bodies and mounts an exaggerated response. If the allergy is severe enough, responses can put patients in anaphylactic shock. Key immune cells that drive allergic reactions include B cells, mast cells, basophils, and eosinophils. Each of these subsets triggers inflammation through antibodies and other molecules. B cells produce a specific antibody known as immunoglobulin E (IgE) antibodies, which then prime mast cells and others to release histamine, heparin, and other inflammatory molecules. However, one particular cell type is key to process allergens and control allergic reactions. These immune cells are known as macrophages and have pro-inflammatory roles in healthy individuals. In the context of allergy and asthma, the role of macrophages is unclear.
Asthma is a leading childhood illness and causes millions of deaths each year. Macrophages in the lung could be the key to improving treatment outcomes. Tiny air sacs in the lungs are known as alveolar. This is where the transition of oxygen and carbon dioxide occur. Macrophages present around these air sacs are known as alveolar macrophages and are suspected of driving asthmatic symptoms. Under healthy contexts, alveolar macrophages act as guardians and keep lungs healthy. However, new evidence concludes that they might also promote asthma.
A recent study in Immunity, by Dr. Bart Lambrecht and others, demonstrate that alveolar macrophages alter their function and enhance asthmatic activity, fueling lung inflammation. Lambrecht is the Vlaams Insituut voor Biotechnologie VIB Science Director and Professor of Pulmonary Medicine at two institutions, including Ghent University and Erasmus University. His work focuses on pulmonary disease and their underlying inflammatory pathways that drive progression.
Lambrecht and his team made the first discovery that alveolar macrophages can be deleterious in the context of asthma. Researchers used mouse models to demonstrate that allergen exposure triggers alveolar macrophages to recruit other immune cells to the lung. Consequently, cell influx enhanced inflammation and exacerbated symptoms. The cells were also observed to merge together and form a collective cell that reshaped the lung tissue, which further bolstered asthmatic symptoms. Lambrecht and others report how these cells can become reprogrammed and reshape the environment conducive to inflammatory processes. These findings change the long-held belief that alveolar macrophages are strictly beneficial against allergens. More importantly, this work provides an underlying mechanism behind asthma and has major implications to the clinic. Overall, this report informs scientists to consider alveolar macrophages as a therapeutic target and provides insight to improve therapy for patients with asthma.
Study, Immunity, Bart Lambrecht, VIB, Ghent University, Erasmus University
