Table 1.
Physico-chemical properties of KLK and its derivatives.
Fig 1.
Effect of KLK peptide and its analogs on cell viability.
RAW 264.7 cells were treated with various concentrations of each peptide or vehicle for 48 h and cell viability was assessed by an MTT assay. Data are presented as mean ± SD of independent experiments.
Fig 2.
Effects of KLK peptide and its analogs on LPS-stimulated NO production in RAW 264.7 macrophages.
Cells were stimulated with LPS (1 μg/mL) in the presence or absence of different concentrations of each peptide for 48 h. The level of nitrite in culture supernatant was measured by Griess reagents. Data are presented as mean ± SD of independent experiments. ###, P <0.001 compared with the unstimulated macrophages; **, P < 0.01 and ***, P < 0.001 compared with the LPS-stimulated macrophage cells.
Fig 3.
Effects of KLK peptide and its analogs on pro-inflammatory cytokine production in LPS-stimulated RAW 264.7 macrophages.
Cells were stimulated with LPS (1 μg/mL) in the presence or absence of different concentrations of individual peptides for 72 h. The levels of IL-1β (A) and TNF-α (B) were evaluated by sandwich ELISA. Data are presented as mean ± SD of independent experiments. ##, P <0.01 and ###, P <0.001 compared with the unstimulated macrophages; *, P < 0.05; **, P < 0.01 and *** P < 0.001 compared with the LPS-stimulated macrophage cells.
Fig 4.
Effect of KLK peptide on LPS-induced PGE2 production in RAW 264.7 macrophages.
Cells were stimulated with LPS (1 μg/mL) in the presence or absence of KLK peptide (5, 10 and 25 μg/mL) or indomethacin (10 μM) for 48 h. After the incubation, PGE2 concentration in culture supernatant was measured by enzyme-immunoassay. Data are presented as mean ± SD of independent experiments. ##, P <0.01 compared with the unstimulated macrophages; **, P < 0.01 compared with the LPS-stimulated macrophage cells.
Fig 5.
Effects of KLK peptide on iNOS, COX-2, IL-1β and TNF-α mRNA expression in LPS-stimulated RAW 264.7 macrophages.
Cells were stimulated with LPS (1 μg/mL) in the presence or absence of different concentrations of KLK peptide for 18 h. Total mRNA was isolated and the mRNA expression of iNOS, COX-2, IL-1β and TNF-α was examined by RT-PCR. Data are expressed as means ± SD of three independent experiments. ##, P <0.01 and ###, P <0.001 compared with the unstimulated macrophages; *, P < 0.05; **, P < 0.01 and *** P < 0.001 compared with the LPS-stimulated macrophage cells.
Fig 6.
Effects of KLK peptide on iNOS and COX-2 protein expression in LPS-stimulated RAW 264.7 macrophages.
Cells were stimulated with LPS (1 μg/mL) in the presence or absence of various concentrations of KLK peptide. After 24 h, the protein expression was determined by Western blotting. Data are presented as mean ± SD of three independent experiments. ###, P <0.001 compared with the untreated macrophages; **, P < 0.01 and ***, P < 0.001 compared with the LPS-stimulated macrophage cells.
Fig 7.
Effects of KLK peptide on LPS-induced activation of NF-κB in RAW 264.7 macrophages.
Cells were stimulated with LPS (1 μg/mL) in the presence or absence of KLK peptide. After 30 min incubation, the expression of cytosolic and nuclear protein fractions of NF-κB p65 (A) as well as IκB and its phosphorylated form (B) was detected by Western blotting. The results are presented as mean ± SD of three independent experiments. ##, P <0.01 and ###, P <0.001 compared with the untreated macrophages; *, P < 0.05; **, P < 0.01 and ***, P < 0.001 compared with the LPS-stimulated macrophage cells.
Fig 8.
Binding of the KLK peptide to LPS.
RAW 264.7 cells were pre-treated in medium containing 10 μg/mL KLK peptide or 10 μg/mL polymyxin B (PMB) for 1 h, washed three times and then stimulated with LPS (1 μg/mL). After 48 hr at 37°C, 5% CO2, nitrite from culture supernatant was measured by Griess assay. The results are presented as mean ± SD of independent experiments. *, P < 0.05 compared with the respective no wash group.
Fig 9.
Helical wheel diagram of KLK, KLK1 and KLK2 peptides.
The helical wheel projection was performed using online program of the HeliQuest: http://heliquest.ipmc.cnrs.fr [23]. The yellow color represents hydrophobic amino acids and blue color represents the basic residues.