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CFTR-rich ionocytes mediate chloride absorption across airway epithelia
Journal article   Open access   Peer reviewed

CFTR-rich ionocytes mediate chloride absorption across airway epithelia

Lei Lei, Soumba Traore, Guillermo S Romano Ibarra, Philip H Karp, Tayyab Rehman, David K Meyerholz, Joseph Zabner, David A Stoltz, Patrick L Sinn, Michael J Welsh, …
The Journal of clinical investigation, Vol.133(20), e171268
10/2023
DOI: 10.1172/JCI171268
PMCID: PMC10575720
PMID: 37581935
url
https://doi.org/10.1172/JCI171268View
Published (Version of record) Open Access

Abstract

The volume and composition of a thin layer of liquid covering the airway surface defend the lung from inhaled pathogens and debris. Airway epithelia secrete Cl– into the airway surface liquid through CFTR (cystic fibrosis transmembrane conductance regulator) channels, thereby increasing the volume of airway surface liquid. The discovery that pulmonary ionocytes contain high levels of CFTR led us to predict that ionocytes drive secretion. However, we found the opposite. Elevating ionocyte abundance increased liquid absorption, whereas reducing ionocyte abundance increased secretion. In contrast to other airway epithelial cells, ionocytes contained barttin/Cl– channels in their basolateral membrane. Disrupting barttin/Cl– channel function impaired liquid absorption, and overexpressing barttin/Cl– channels increased absorption. Together, apical CFTR and basolateral barttin/Cl– channels provide an electrically conductive pathway for Cl– flow through ionocytes, and the transepithelial voltage generated by apical Na+ channels drives absorption. These findings indicate that ionocytes mediate liquid absorption, and secretory cells mediate liquid secretion. Segregating these counteracting activities to distinct cell types enables epithelia to precisely control the airway surface. Moreover, the divergent role of CFTR in ionocytes and secretory cells suggests that cystic fibrosis disrupts both liquid secretion and absorption.

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