The co-incubated THP-1 cells and bacteria were resuspended in streptavidin–allophycocyanin (Pierce) diluted 1 : 25 in 1% BSA (Sigma). Following streptavidin staining, cells were resuspended in PBS for flow cytometry analysis. Samples were run on a BD FACScalibur™ flow cytometer

and data were analysed using CellQuest Pro software. The co-incubated THP-1 cells and bacteria were washed twice in PBS, resuspended in 300 μl PBS and added to a Polysine slide (Thermo Scientific, Waltham, ABT-888 MA). The unbound cells were then aspirated after 30 min and the bound cells were fixed with 10% neutral buffered formalin. The cells were stained with streptavidin–allophycocyanin diluted 1 : 25 in 1% BSA for 30 min at 4°. Cells were permeabilized with 0·2% Triton X-100 (Sigma). Selleckchem ZIETDFMK Filamentous (F)-actin was stained with 0·165 μm rhodamine phalloidin (Molecular Probes) for 15 min. Cells were mounted with ProLong® Gold antifade reagent (Molecular Probes) using No. 1·5 coverslips

(Marienfeld, Lauda-Königshofen, Germany). Slides were viewed with an Olympus FV1000 confocal laser scanning microscope (Olympus) consisting of an Olympus IX81 inverted microscope equipped with an oil-immersion Plan-Apo 60 ×/1·1 objective lens and a three-channel photomultiplier transmission detector using 1·5 × digital magnification. Five fields of view were collected from each slide to give a total of at least 100 cells per sample. Statistical analysis was carried out using GraphPad Prism (version 4.03; GraphPad Software, San Diego, CA). Means with standard error (SEM) are presented in each graph. Differences between two groups were calculated using Student’s

t-test. Differences between three or more groups were calculated by analysis of variance with Tukey’s post-hoc test. Differences were considered significant at P < 0·05. Microarray data were analysed using GeneSpring 7.3.1 software (Silicon Genetics) to determine significant changes with P < 0·05, and > 1·5-fold difference. Tenoxicam To increase stringency, the cut-off was increased to twofold for some analyses where indicated. Cluster analysis and visualization were performed using Genesis14 and VENNY was used for visualization of differentially expressed data sets.16 To investigate possible responsiveness of M cells to commensal bacteria we used a well described in vitro model of M-cell function.10 Transepithelial electrical resistance was used to confirm the integrity of the C2BBe1 (C2) monolayer. The transepithelial electrical resistance values for the C2BBe1 (C2) control wells and co-cultured C2 plus Raji cells (C2-M) M cells were 475·2 ± 88·7 Ω·cm2 and 457·2 2 ± 71·4 Ω·cm2, respectively (data not shown). TNF receptor superfamily, member 9 (TNFRSF9) is induced by lymphocyte activation and is up-regulated in M cells17 and matrix metallopeptidase 15 (MMP15) has also been found to be up-regulated in M cells in vitro.