title: Toll-like receptor 2 regulates the barrier function of human bronchial epithelial monolayers through atypical protein kinase C zeta, and an increase in expression of claudin-1.
abstract: We investigated the role of Toll-like receptor (TLR) 2 in maintaining the integrity of the airway epithelial barrier using the human bronchial epithelial cell line Calu-3. Activation of TLR2 by its ligands, Pam3CysSK4 and Peptidoglycan showed a concentration dependent increase in epithelial barrier function, as measured by transepithelial electrical resistance (TEER). This was confirmed by a decrease in paracellular flux of fluorescein sodium. This TLR2 induced increase in TEER was significantly reduced by pretreatment with polyclonal anti-human TLR2-neutralizing antibody. TLR2 stimulation in Calu-3 cell monolayers resulted in an increased expression of the tight junction proteins claudin-1 and ZO-1, and a decreased expression of occludin, at both the mRNA and protein levels. A pseudosubstrate inhibitor to PKCζ significantly prevented the TLR2 mediated increase in barrier function. It also prevented the increase in claudin-1 in a concentration dependent manner up to 1 µM. TLR2 stimulation led to an increase in phosphorylation of atypical PKC ζ, which was prevented by the pseudosubstrate inhibitor in a concentration dependent manner. Taken together, our observations support a model whereby increased tight junction barrier function induced by activation of TLR2 occurs through increased expression of claudin-1, and through modulation of PKC ζ activity.
authors.affiliation: School of Pharmaceutical Sciences; University of Geneva; University of Lausanne; Geneva, Switzerland.
authors.forename: Sakthikumar
authors.initials: S
authors.lastname: Ragupathy
authors.affiliation: School of Pharmaceutical Sciences; University of Geneva; University of Lausanne; Geneva, Switzerland.
authors.forename: Farnaz
authors.initials: F
authors.lastname: Esmaeili
authors.affiliation: Department of Molecular Biology; Institute of Genetics and Genomics; University of Geneva; Geneva, Switzerland ; Department of Cell Biology; Institute of Genetics and Genomics; University of Geneva; Geneva, Switzerland.
authors.forename: Serge
authors.initials: S
authors.lastname: Paschoud
authors.affiliation: School of Pharmaceutical Sciences; University of Geneva; University of Lausanne; Geneva, Switzerland.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Sublet
authors.affiliation: Department of Molecular Biology; Institute of Genetics and Genomics; University of Geneva; Geneva, Switzerland ; Department of Cell Biology; Institute of Genetics and Genomics; University of Geneva; Geneva, Switzerland.
authors.forename: Sandra
authors.initials: S
authors.lastname: Citi
authors.affiliation: School of Pharmaceutical Sciences; University of Geneva; University of Lausanne; Geneva, Switzerland.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Borchard
keywords: Calu-3; airway inflammation; barrier function; epithelial permeability; protein kinase C; tight junctions; toll-like receptor
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