Apoptosis in normal bronchial respiratory epithelium between certainties and uncertainties

The respiratory epithelium lines the conducting airways and functions as a selective barrier interposed between external environment and human body. It is exposed to various aggressive factors such as viral and bacterial microorganisms, or cigarette smoke and other inhaled noxious substances. The normal airway epithelium has its own mechanisms that maintain the integrity of the epithelial barrier and it is relatively refractory to a number of apoptotic stimuli. The up to date data about apoptosis in normal airway epithelium are limited, especially regarding the regulatory factors of this process. The current knowledge concerning the airway epithelium apoptosis regulation needs to be further studied by exploring the Bcl-2 superfamily members, Zn, p21, or peroxiredoxine V and pirine.