There was a significant difference among the experimental groups (p < 0. 01) (Table 1). These results indicated PCN can induce oxidative damage. Table 1 The oxidative effect of pyocyanin on differentiated

U937 cells ( ± s n=3) Group LDH (U · L-1) MDA (mmol · L-1) SOD (Eu · mL-1) CAT (Eu.mL-1) C0 301 ± 48 0.91 ± 0.07 5.99 ± 0.96 1.86 ± 0.21 C1 521 ± 48** 2.01 ± 0.23** 4.66 ± 0.75* learn more 1.27 ± 0.18* C2 590 ± 52** 2.93 ± 0.19** 3.86 ± 0.62** 1.01 ± 0.14** C3 668 ± 76** 3.85 ± 0.25** 3.12 ± 0.41** 0.62 ± 0.11** Notice: C0: Control group; C1: PCN (5 μM); C2: PCN (25 μM); C3: PCN (50 μM). * P < 0.05, compared with control; ** P < 0.01, compared with control. Effects of MAPK inhibitors on PCN-induced IL-8 release A number of studies show that the MAPK signal transduction pathways mediate IL-8 expressions induced by a variety of stimulating factors [26]. We therefore went on to explore the possibility that PCN may induce U937 cells to express IL-8 through MAPK signaling. In some experiments, different concentrations of the ERK and P38 MAPK blockers (PD98059 at 10, 30, or 50 μM and SB203580 at 10, 30, or 50 μM, respectively) were added into the fresh medium of U937 cells 60 min before PCN addition. After 24 hours, the supernatants were collected and IL-8 concentrations were detected by ELISA.

The results showed that PD98059 and SB203580 significantly decreased the NCT-501 secretion of IL-8, and as either substance’s concentration increased, IL-8 secretion decreased, indicating that PCN may stimulate U937 Blasticidin S nmr before cells to express IL-8 by both MAPK signaling pathways (Figure 3). Figure 3 MAPK inhibitors attenuate PCN-induced IL-8 release. Different concentrations of the ERK or P38MAPK blockers (PD98059 at 10, 30, or 50 μM or SB203580 at 10, 30, or 50 μM) were added into fresh medium of PMA-differentiated U937 cells 60 min before PCN was added.

Cells were exposed to PCN (50 μM) for 24 h. Supernatants were harvested for measuring IL-8 by ELISA. **p < 0.01 compared with PMA-differentiated U937 cells. MAPK: mitogen-activated protein kinase; ERK: extracellular signal-regulated kinase; PMA: phorbol 12-myristate 13-acetate. Effects of NF-κB inhibitor on PCN-induced IL-8 release To further investigate whether NF-κB is involved in PCN-induced IL-8 production, different concentrations of NF-κB blockers (PDTC at 50, 100, or 200 μmol/L) were added into fresh medium of PMA-differentiated U937 cells 60 min before PCN was added. After 24 hours of further incubation, the supernatants were collected and IL-8 concentrations were detected. Results showed that PDTC significantly decreased the secretion of IL-8, and with increasing concentrations PDTC, IL-8 secretion decreased, although in the presence of high concentrations of PCN, indicating that the PCN may stimulate PMA-differentiated U937 cells to express IL-8 by NF-κB signaling pathway (Figure 4). Figure 4 NF-κB inhibitor reduces PCN-induced IL-8 release.