Epithelial Barrier Dysfunction Induced by Hypoxia in the Respiratory System

A steady and continuous supply of oxygen is important for humans, since an excess or deficiency in oxygen levels may result in the death of cells, tissues, or organisms. As a mechanical barrier against pathogens, the respiratory epithelium is always exposed to hypoxia in some detrimental external environments and/or pathologic states. The barrier function is accordingly impaired as a result of the disrupted cell composition ratio, ion transport, and tight junctions in a hypoxia-inducible factor-dependent or independent way. Hypoxia has been identified as an element of the primary or secondary pathogenic factors of many respiratory diseases. Still, the relationship between hypoxia and epithelial barrier dysfunction is not fully understood. Thus, we summarized recent researches on epithelial barrier dysfunction induced by hypoxia in the respiratory system, aiming to explore the possible therapeutic targets in hypoxia-related respiratory system diseases.