Trained immunity in the lung

Trained immunity represents a recent concept that elucidates the long-term reprogramming of innate immune cells, enabling them to adapt and respond more effectively to subsequent encounters with diverse pathogens. Initially recognized through the Bacillus Calmette-Guérin vaccine, Candida albicans infection, and β-glucan administration, this phenomenon challenges the traditional view that immune memory is exclusive to the adaptive immune system. Trained immunity is characterized by epigenetic and metabolic modifications in innate immune cells that facilitate enhanced responses to infections through mechanisms like chromatin remodeling and altered gene expression. This review focuses on the implications of trained immunity within the lung environment, which is constantly exposed to a plethora of pathogens and environmental irritants. We discuss the roles of various immune cell types, including alveolar macrophages and dendritic cells, in mediating trained immunity and how these adaptations may influence pulmonary insults and disease. Furthermore, we highlight the potential for leveraging trained immunity to enhance vaccine efficacy and develop novel therapeutic strategies for immune-related lung conditions. As research progresses, understanding trained immunity in the lung could pave the way for innovative interventions that improve lung health and resilience against infections.