科研之友
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摘要
The airway epithelium provides a barrier that separates inhaled air and its various particulates from the underlying tissues. It provides key physiological functions in both sensing the environment and initiating appropriate innate immune defenses to protect the lung. Protease-activated receptor-2 (PAR(2)) is expressed both apically and basolaterally throughout the airway epithelium. One consequence of basolateral PAR2 activation is the rapid, Ca2+-dependent ion flux that favors secretion in the normally absorptive airway epithelium. However, roles for apically expressed PAR(2) activation have not been demonstrated, in part due to the lack of specific, high-potency PAR(2) ligands. In the present study, we used the newly developed PAR2 ligand 2at-LIGRLO(PEG(3)-Pam)-NH2 in combination with well-differentiated, primary cultured airway epithelial cells from wild-type and PAR(2)(-/-) mice to examine the physiological role of PAR(2) in the conducting airway after apical activation. Using digital imaging microscopy of intracellular Ca2+ concentration changes, we verified ligand potency on PAR2 in primary cultured airway cells. Examination of airway epithelial tissue in an Ussing chamber showed that apical activation of PAR(2) by 2at-LIGRLO(PEG(3)-Pam)-NH2 resulted in a transient decrease in transepithelial resistance that was due to increased apical ion efflux. We determined pharmacologically that this increase in ion conductance was through Ca2+-activated Cl- and large-conductance K+ channels that were blocked with a Ca2+-activated Cl- channel inhibitor and clotrimazole, respectively. Stimulation of Cl- efflux via PAR(2) activation at the airway epithelial surface can increase airway surface liquid that would aid in clearing the airway of noxious inhaled agents.
- 出版日期2014-10-15
