Title-Inflammatory Signaling Pathways in Allergic and Infection-Associated Lung Diseases

Lung inflammation can be caused by pathogen infection alone or by allergic disease, leading to pneumonitis. Most of the allergens (antigens) that cause allergic lung diseases, including asthma and hypersensitivity pneumonitis (HP), are derived from microorganisms, such as bacteria, viruses, and fungi, but some inorganic materials, such as mercury, can also cause pneumonitis. Certain allergens, including food and pollen, can also cause acute allergic reactions and lead to lung inflammation in individuals predisposed to such reactions. Pattern recognition-associated and damage-associated signaling by these allergens can be critical in determining the type of hypersensitization and allergic disease, as well as the potential for fibrosis and irreversible lung damage. This review discusses the signs, symptoms, and etiology of allergic asthma, and HP. Furthermore, we review the immune response and signaling pathways involved in pneumonitis due to both microbial infection and allergic processes. We also discuss current and potential therapeutic interventions for infection-associated and allergic lung inflammation.