Inhibitory effect of kukoamine B on high mobility group protein B1/nuclear factor-κB signaling pathway in lung injury of mice with sepsis

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Objective To investigate the inhibitory effect of kukoamine B (KB) on high mobility group protein B1 (HMGB1)/nuclear factor-κB (NF-κB) signaling pathway in lung injury of induced septic mice and its protective effect. Methods Thirty C57BL/6 mice were randomly divided into three groups (n = 10): control group, lipopolysaccharide (LPS) model group and KB intervention group. Sepsis model was reproduced by intra-peritoneal injection of 20 mg/kg LPS, while equivalent normal saline was given in control group, and 20 μg/kg KB was injected through caudal vein 4 hours after LPS challenge in KB intervention group. The blood and lung tissue samples were harvested 24 hours after LPS injection. The lung wet/dry weight ratio (W/D), the activity of myeloperoxidase (MPO) and protein content in bronchoalveolar lavage fluid (BALF) were determined, and tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in plasma and lung tissue were determined by enzyme linked immunosorbent assay (ELISA). Western Blot was applied for determining the protein expressions of HMGB1 and NF-κB. Results Compared with control group, LPS could significantly increase lung W/D ratio, MPO activity, protein content in BALF, the levels of TNF-α and IL-1β in plasma and lung tissues, and protein expressions of HMGB1 and NF-κB [lung W/D ratio: 6.84±0.42 vs. 3.36±0.31, lung MPO (U/g): 36.46±2.72 vs. 2.32±0.52, protein content in BALF (g/L): 6.21±1.35 vs. 0.35±0.12, plasma TNF-α (ng/L): 36.31±1.53 vs. 8.53±0.82, lung TNF-α (ng/L): 65.35±2.32 vs. 12.36±1.47, plasma IL-1β (ng/L): 64.26±7.53 vs. 28.83±5.74, lung IL-1β (ng/L): 542.36±14.47 vs. 58.46±7.24, lung HMGB1 (gray value): 316.43±4.26 vs. 100.21±0.06, lung NF-κB (gray value): 465.84±6.38 vs. 100.15±0.08, all P < 0.05], which indicated that LPS induced mice sepsis model was successful, and lung injury occurred. However, compared with the mice in LPS group, KB could significantly provide the protective effects for lung injury, and alleviate the changes in above parameters [lung W/D ratio: 4.56±0.43 vs. 6.84±0.42, lung MPO activity (U/g): 14.83±1.47 vs. 36.46±2.72, protein content in BALF(g/L): 2.33±1.24 vs. 6.21±1.35, plasma TNF-α (ng/L): 12.53±0.42 vs. 36.31±1.53, lung TNF-α (ng/L): 32.27±1.41 vs. 65.35±2.32, plasma IL-1β (ng/L): 42.37±6.24 vs. 64.26±7.53, lung IL-1β (ng/L): 314.42±17.38 vs. 542.36±14.47, lung HMGB1 (gray value): 224.57±3.42 vs. 316.43±4.26, lung NF-κB (gray value): 258.73±5.42 vs. 465.84±6.38, all P < 0.05], which indicated that KB had obvious protective effect on the lung of septic mice. Conclusion KB could provide protective effect on lung injury in LPS-induced septic mice through anti-inflammation, which is related to HMGB1/NF-κB signaling pathway. Key words: Sepsis; Kukoamine B; High mobility group protein B1; Nuclear factor-κB; Inflammatory reaction; Lung