Cell lines of pulmonary and non-pulmonary origin as tools to study the effects of house dust mite proteinases on the regulation of epithelial permeability

Background Allergenic and non-allergenic proteinases from house dust mites (HDM) cause loss of adhesion between airway epithelial cells that may resul t in a loss of functional cohesion between the cells and thus assist in all ergen presentation. Improved cellular assay systems are needed to ascertain the mechanisms involved. Objectives To survey a series of epithelial cell lines (Calu-3, 16HBE14o(-) , NCI-H292 and A549 from human airways, and MDCK from dog kidney) and estab lish their utility for studies of the effects of HDM proteinases from D. pt eronyssinus on epithelial permeability, To develop an improved method for m easuring changes in epithelial permeability induced by HDM proteinases and other provocants. Methods The permeability of epithelial monolayer cultures to mannitol was c alculated from measurements of clearance using a technique that permits mat hematical estimation and reduction of non-cellular diffusional constraints. Permeability was studied under control conditions and after perturbation o f monolayers with HDM proteinases (separated into serine- and cysteine-prot einase classes) or chelation of extracellular Ca2+. Fluorescent antibody st aining was used to investigate whether the cells expressed tight junctions (staining of ZO-1), desmosomes (staining of desmoplakin) and zonulae adhere ntes (staining of E-cadherin). Results The Calu-3 line was identified as an airway cell line that expresse d functional light junctions, desmosomes and zonulae adherentes. Calu-3 mon olayers exhibited a low clearance and permeability to mannitol, similar to that seen in the extensively characterized MDCK cell line. Clearance and pe rmeability were significantly increased by treatment with either HDM protei nase fraction or by calcium chelation. 16HBE14o(-) cells also had a low per meability to mannitol under control conditions and expressed a similar repe rtoire of functional proteins from major intercellular junctions. In contra st, NCI-H292 and A549 cell lines were functionally deficient in tight junct ions, although they did express desmosomes and zonulae adherentes to a grea ter extent. Epithelial permeability was found to be a more appropriate and sensitive index of epithelial perturbation than was tracer clearance. Conclusion These results suggest that the Calu-3 and 16HBE14o(-) cell lines are useful tools in studying the mechanism of HDM proteinases on airway ep ithelial cell function. HDM proteinases of both cysteine and serine mechani stic classes were found to perturb epithelial adhesion and function.