Macrophages play an important role in the innate and adaptive immune responses of organ systems, including the lungs, to particles and pathogens. Cumulative results show that macrophages contribute to the development and progression of acute or chronic inflammatory responses through the secretion of inflammatory cytokines/chemokines and the activation of transcription factors in the pathogenesis of inflammatory lung diseases, such as acute lung injury (ALI), acute respiratory distress syndrome (ARDS), ARDS related to COVID-19 (coronavirus disease 2019, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)), allergic asthma, chronic obstructive pulmonary disease (COPD), and idiopathic pulmonary fibrosis (IPF). This review summarizes the functions of macrophages and their associated underlying mechanisms in the development of ALI, ARDS, COVID-19-related ARDS, allergic asthma, COPD, and IPF and briefly introduces the acute and chronic experimental animal models. Thus, this review suggests an effective therapeutic approach that focuses on the regulation of macrophage function in the context of inflammatory lung diseases.

Acute lung injury (ALI) is induced by pneumonia, sepsis and other conditions. The disease characteristics include severe lung inflammation, in which various cells, such as epithelial cells, macrophages, and neutrophils, play a pivotal role. Corticosteroids and antibiotics are used to treat ALI; however, they may have side effects. Cumulative data confirm that traditional herbal medicines exert therapeutic effects against endotoxin-induced inflammatory responses in both in vitro and in vivo ALI studies. This review briefly describes the anti-ALI effects of medicinal herbal extracts (MHEs) and their molecular mechanisms, especially focusing on Toll-like receptor 4/nuclear factor kappa B cell pathways, with a brief summary of in vitro and in vivo ALI experimental models. Thus, the present review highlights the excellent potential of MHEs for ALI therapy and prevention and may also be useful for the establishment of in vitro and in vivo ALI models.