The human β-defensin-2 (HBD-2) was also quantified in Caco-2/TC7 cells supernatant. The results show that the two strains of P. mosselii were able to induce HBD-2 secretion by Caco-2/TC7 cells (Figure 3C).

Infection with P. mosselii ATCC BAA-99 and MFY161 strains led to a major increase of HBD-2 production by Caco-2/TC7 with 125 +/−26 pg.mL-1 and 136 +/−31 pg.mL-1, respectively, compared to the 4 +/−2 pg.mL-1 basal secretion of HBD-2 in uninfected cells. The induction of HBD-2 by the two P. mosselii strains was almost similar to that obtained with P. aeruginosa PAO1 (165 +/−14 pg.mL-1). Transepithelial LXH254 purchase buy Trichostatin A electrical resistance measurements The effect of the bacteria on epithelial permeability was evaluated by measuring the TER across differentiated Caco-2/TC7 monolayers. TER values were

measured at the onset of the experiment and at times 3, 6, 9 and 24 h. Up to 9 h after the beginning of the experiment, the TER values of the infected monolayers remained unchanged (data not shown). After 24 h of infection, the TER values of the monolayers exposed to the bacteria were significantly decreased (Figure 4). The decrease MEK162 mw of TER induced by P. mosselii MFY161 was 20.8 +/−4.7% compared to uninfected control cells whereas P. mosselii ATCC BAA-99 led to a decrease of TER reaching 39 +/− 3.2% and P. aeruginosa PAO1 provoked a deeper decrease of the TER value (55.8 +/−5.3%). These falls in TER cannot be attributed to damages provoked by acidification of the medium since the pH of the medium remained constant over the studies. Figure 4 Effects of P. mosselii ATCC BAA-99, P. mosselii MFY161 and P. aeruginosa PAO1 on the transepithelial electrical resistance of Caco-2/TC7 cells. Differentiated Caco-2/TC7 cells were infected for 24 h. The TER was expressed as percentages of the initial control TER measured across each individual cell monolayer at the onset of the experiment. Results are Decitabine the mean values

(+/−SEM) of three independent experiments. *** P < 0.001 versus uninfected Caco-2/TC7 cells, ** P < 0.01 versus uninfected Caco-2/TC7 cells. Actin visualisation The effect of P. mosselii ATCC BAA-99 and MFY161 on the organization of the sub-membrane F-actin microfilament network was studied and compared to that of P. aeruginosa PAO1. Whereas the staining pattern of untreated Caco-2/TC7 cells showed a continuous fine meshwork of microfilaments lining the cell border (Figure 5), the cells exposed for 24 h with P. mosselii ATCC BAA-99, P. mosselii MFY161 or P. aeruginosa PAO1 lost their normal organization. All these bacteria induced a dramatic disruption of F-actin. Figure 5 Effects of P. mosselii ATCC BAA-99, P. mosselii MFY161 and P. aeruginosa PAO1 on the F-actin cytoskeleton of Caco-2/TC7 cells. Differentiated Caco-2/TC7 cells were infected for 24 h. F-actin was stained and examined using a confocal laser scanning microscope. (A) Uninfected cells, (B) infection by P. mosselii ATCC BAA-99, (C) infection by P.