Epithelial barrier function properties of the 16HBE14o- human bronchial epithelial cell culture model.

Patrick J Callaghan,Elizabeth Rybakovsky,James M Mullin,Sunil Thomas,Bryan Ferrick

doi:10.1042/bsr20201532

Abstract

The human bronchial epithelial cell line, 16HBE14o- (16HBE), is widely used as a model for respiratory epithelial diseases and barrier function. During differentiation, transepithelial electrical resistance (TER) increased to approximately 800 Ohms × cm2, while 14C-d-mannitol flux rates (Jm) simultaneously decreased. Tight junctions (TJs) were shown by diffusion potential studies to be anion-selective with PC1/PNa = 1.9. Transepithelial leakiness could be induced by the phorbol ester, protein kinase C (PKC) activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), and the proinflammatory cytokine, tumor necrosis factor-α (TNF-α). Basal barrier function could not be improved by the micronutrients, zinc, or quercetin. Of methodological significance, TER was observed to be more variable and to spontaneously, significantly decrease after initial barrier formation, whereas Jm did not significantly fluctuate or increase. Unlike the strong inverse relationship between TER and Jm during differentiation, differentiated cell layers manifested no relationship between TER and Jm. There was also much greater variability for TER values compared with Jm. Investigating the dependence of 16HBE TER on transcellular ion conductance, inhibition of the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) chloride channel with GlyH-101 produced a large decrease in short-circuit current (Isc) and a slight increase in TER, but no significant change in Jm. A strong temperature dependence was observed not only for Isc, but also for TER. In summary, research utilizing 16HBE as a model in airway barrier function studies needs to be aware of the complexity of TER as a parameter of barrier function given the influence of CFTR-dependent transcellular conductance on TER.

Highlights

Epithelial cell layers are the interface between the outside environment and the interior of the body, functioning as a physical barrier and preventing pathogens, allergens, and noxious compounds from entering interstitial tissue and blood vessels [1,2]
Phase contrast microscopy revealed that 16HBE cells in subconfluent cultures typically aggregate together in large islands of closely opposed cells, a characteristic observed in many types of epithelial cell cultures (Figure 1A)
The 16HBE, human bronchial epithelial cell line, has become a widely utilized model for a variety of respiratory epithelial physiological and disease processes [16,17,18,19,20,21,22]. 16HBE like Calu-3 are both airway-derived established epithelial cell lines, whose cells at confluence become polar with apical microvilli, form tight junctional seals and manifest cAMP-regulated cystic fibrosis transmembrane conductance regulator (CFTR) channels which are major contributors to the cell layers’ short-circuit current [29,30]

Summary

Introduction

Epithelial cell layers are the interface between the outside environment and the interior of the body, functioning as a physical barrier and preventing pathogens, allergens, and noxious compounds from entering interstitial tissue and blood vessels [1,2] Proteins such as occludin and claudins form oligomeric complexes—known as tight junctions (TJs)—which create a continuous gasket-like seal around the apical perimeter of epithelial cells [2]. An intact barrier is vital to the functioning of organ systems such as the gastrointestinal, renal, respiratory, and genitourinary tracts Disruption of these barriers and consequential increased non-specific permeability of the epithelium can manifest in conditions like celiac disease, inflammatory bowel disease, and allergies [4,5,6,7].

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Conclusion