A vector with constitutively active Renilla luciferase (pRL-CMV, Promega) was chosen as internal control. One day prior to transfection, approximately 0.5 × 105 cells per well were seeded in a 24-well format. Transfection was performed for 6 h using 1.5 μl/well of Lipofectamine 2000 (Invitrogen), 0.54 μg/well of pNFκB-Luc and 0.06 μg/well of pRL-CMV. Lipofectamine 2000 and plasmids were diluted in serum-free Opti-MEM (Invitrogen) during preparation of DNA-liposome complexes. All plasmids were isolated by an endofree plasmid isolation kit (Macherey-Nagel)

according to the manufacturer’s instructions. Luciferase was detected Selleckchem ITF2357 using the dual-luciferase reporter assay system (Promega) and a Turner TD20/20 luminometer (Turner biosystems) set to 10s measurement with an initial 2s delay. Transcription factor activation was expressed as relative NF-κB activation, defined as the ratio between firefly luciferase and Renilla luciferase activity. Ratios were normalized against either non-stimulated control cells or cells stimulated with E. coli. The difference between means was tested statistically by using Student’s t-test, with the limit for statistical Anti-infection Compound high throughput screening significance set to p-values < 0.05. Epithelial cell line challenge T24 bladder cells transfected with luciferase vectors (pNFκB-Luc

and pRL-CMV) were challenged for 24 h in a 24-well plate format with 2 × 107 cfu/ml of viable or the equivalent number of heat-killed lactobacilli (L. rhamnosus GR-1 or GG). For activation of NF-κB, as well as cytokine and chemokine release, epithelial cells were stimulated with heat-killed E. coli (108 cfu/ml). Cell culture supernatants for ELISA were collected from Carnitine palmitoyltransferase II challenge experiments using non-transfected cells and stored at -20°C until use. For qPCR, cells were stimulated

in the same way although all experiments were done in 6-well plates (with proportional increase in number of cells and bacteria) for increased amounts of RNA. Cell viability was determined by staining dead cells using propidium iodide followed by flow cytometry (Cytomics FC500, Beckman Coulter). To inhibit agonist activation of TLR4 in T24 cells, transfected cells were exposed to Polymyxin B (Invivogen), which effectively binds to LPS and thereby inhibits TLR4 activation, at a concentration of 50 μg/ml for 1 h prior to the experiment and subsequently challenged with bacteria, as previously described. Enzyme-linked immunosorbent assays TNF, IL-6 and CXCL8 levels were determined by BD ELISA sets (BD Biosciences) according to the manufacturer’s instructions. A volume of 100 μl of capture antibody (diluted 1:250 coating buffer) was added to each well of a 96-well ELISA microplate (Nunc) and allowed to bind overnight at 4°C. Wells were washed three times with PBST (PBS pH 7.0 with 0.05% Tween-20) and blocked with PBS supplemented with 10% heat-inactivated FBS (HyClone) for 1 h in room temperature after which the wells were washed three times with PBST.