PT - JOURNAL ARTICLE AU - Emily F.A. van 't Wout AU - Annemarie van Schadewijk AU - Jan Stolk AU - Pieter S. Hiemstra TI - <em>Pseudomonas aeruginosa</em> causes endoplasmic reticulum stress and loss of tight junctions (TJ) in primary bronchial epithelial cells (PBEC) DP - 2012 Sep 01 TA - European Respiratory Journal PG - 4732 VI - 40 IP - Suppl 56 4099 - http://erj.ersjournals.com/content/40/Suppl_56/4732.short 4100 - http://erj.ersjournals.com/content/40/Suppl_56/4732.full SO - Eur Respir J2012 Sep 01; 40 AB - P.aeruginosa has been shown to decrease epithelial barrier function by disrupting TJ, a process mediated by secreted virulence factors. In C.elegans, P.aeruginosa was shown to induce XBP-1 splicing (XBP1spl), a key event in endoplasmic reticulum (ER) stress. Moreover, patients with ER stress-associated lung diseases, like CF and COPD, show clinical deterioration after P.aeruginosa infection. We hypothesize that P.aeruginosa induces ER stress accompanied by loss of TJ, which is exaggerated in ER stress sensitized epithelial cells.PBEC were exposed to conditioned medium of P.aeruginosa strain PAO1 (PAO1-CM) and/or thapsigargin (Tg; chemical ER stress inducer). PAO1-CM caused a time- and dose-dependent ER stress response with a maximal 11.9-fold increase (±7.8;p&lt;0.001) of XBP1spl after 12 hours and 13.0-fold increase (±6.8;p=0.02) of CHOP mRNA after 8 hours, measured by qPCR. This increase was preceded by a 95.1% (±4.9%) reduction in zona occludens-1 (ZO-1) at 6 hours as assessed by Western blot. After 6 hours, cells showed a gradual decline in resistance until the monolayer was disrupted as assessed by ECIS. In the presence of Tg, PAO1-CM showed an accelerated decline in resistance and loss of TJ, together with a synergistic effect on IL-8 production, but no additional effect on ER-stress markers.PAO1-CM induces ER stress in PBEC which is associated with altered epithelial barrier function. Tg-induced ER stress increases the response to PAO1-CM. These mechanisms may contribute to the disease progression observed after P.aeruginosa infection.This study was supported by a grant from the Netherlands Asthma Foundation (grant number: 3.2.08.032).