SIgA in various pulmonary diseases

Abstract

Secretory immunoglobulin A (SIgA) is one of the most abundant immunoglobulin subtypes among mucosa, which plays an indispensable role in the first-line protection against invading pathogens and antigens. Therefore, the role of respiratory SIgA in respiratory mucosal immune diseases has attracted more and more attention. Although the role of SIgA in intestinal mucosal immunity has been widely studied, the cell types responsible for SIgA and the interactions between cells are still unclear. Here, we conducted a wide search of relevant studies and sorted out the relationship between SIgA and some pulmonary diseases (COPD, asthma, tuberculosis, idiopathic pulmonary fibrosis, COVID-19, lung cancer), which found SIgA is involved in the pathogenesis and progression of various lung diseases, intending to provide new ideas for the prevention, diagnosis, and treatment of related lung diseases.

Keywords: Lung disease; Mucosal immunity; Respiratory; Secretory immunoglobulin A.

Fig. 1

Production of SIgA in lung epithelial mucosa and its role in resisting the invasion of external pathogenic microorganisms. (1) Plasma cells in the lamina propria secrete dIgA. (2) DIgA binds to pIgR produced by pulmonary bronchial epithelial cells and stimulates endocytosis to form dIgA pIgR complex. (3) Under the action of proteolytic enzyme, the extracellular segment of pIgR, namely, SC, combines with dIgA to form SIgA, which is released into the top mucus layer. (4) SIgA drives immune rejection, agglutinates, intercepts and eliminates pathogenic microorganisms. Acknowledgements: the figure is drawn by Figdraw