Measurement of Airway Epithelial Permeability: Methods and Protocols.

The epithelial barrier is the basic unit that ensures the continuation of life for all living things. It provides separation of living cells or organelles from nature and microenvironment. Thus, life and functions continue. It is the same for the human organism. However, the normal properties of this epithelial barrier may differ in each organ and tissue. The two most important barriers that separate humans from nature and their microenvironment are the respiratory tract and the gastrointestinal system. The respiratory tract continues from the tip of the nose to the alveola. The epithelial barrier in the respiratory tract has to be semipermeable in places. However, the increase in permeability exceeding the limit is the cause of the diseases and the increase in clinical weight. Therefore, measuring the level of epithelial permeability in these units is important for understanding experimental models, disease cause, clinical severity, and prognosis. In this article, the measurement of epithelial permeability in the respiratory tract will be discussed with in vitro, in vivo aspects and methods.