Effects of hydrogen inhalation on serum pro-inflammatory factors and intestinal injury in mice with severe sepsis

Abstract:

To investigate the effects and mechanisms of hydrogen inhalation on serum levels of pro-inflammatory factors and intestinal injury in severe septic mice. 176 male ICR mice were randomly divided into four groups: sham operation group, hydrogen control group ( sham + hydrogen inhalation ), model group ( severe sepsis model ) and hydrogen treatment group ( severe sepsis model + hydrogen inhalation ), with 44 mice in each group. Severe sepsis model was reproduced by cecal ligation and puncture ( CLP ). 2% hydrogen inhalation was given for 1 hour at 1 hour and 6 hours after sham or CLP operation. Twenty animals in each group were selected and observed for 7-day survival rate. Six animals in each group were selected and sacrificed at 6, 12, 24 and 48 hours after sham or CLP, the concentrations of tumor necrosis factor-α ( TNF-α), interleukins ( IL-6, IL-10 ) and high mobility group box 1 ( HMGB1 ) in serum were determined, the intestinal histopathological changes and scores were evaluated by light microscopy, and the activities of myeloperoxidase ( MPO ) and caspase-3 were determined. The 7-day survival rate of severe sepsis mice was 0; the 7-day survival rate was increased to 60% in hydrogen treatment group, with statistical significance in variables compared with model group ( P < 0.05 ). Compared with sham operation group, the serum concentrations of TNF-α, IL-6, IL-10 and HMGB1 were obviously increased, the intestine were heavily injured along with higher histopathological scores, and the intestinal MPO and caspase-3 activities were significantly enhanced at different time points after CLP in model group ( all P < 0.05 ). Compared with model group, the serum concentrations of TNF-α, IL-6 and HMGB1 were significantly decreased [ TNF-α ( ng/L ): 6 hours: 110.34±9.28 vs. 440.55±25.78, 12 hours: 82.29±8.43 vs. 448.36±32.54, 24 hours: 79.68±9.04 vs. 346.42±22.24, 48 hours: 80.79±10.06 vs. 368.94±31.58; IL-6 ( ng/L ): 12 hours: 58.68±8.55 vs. 158.28±16.73, 24 hours: 46.98±7.58 vs. 146.74±18.02, 48 hours: 38.67±8.22 vs. 136.45±15.45; HMGB1 ( μg/L ): 6 hours: 15.75±4.32 vs. 55.56±10.04, 12 hours: 32.02±9.33 vs. 89.65±15.65, 24 hours: 35.87±8.54 vs. 86.44±20.33, 48 hours: 23.85±9.83 vs. 98.33±18.88, all P < 0.05 ], the serum concentrations of IL-10 ( ng/L ) at 24 hours and 48 hours after CLP were obviously increased ( 24 hours: 135.44±16.43 vs. 79.22±12.03, 48 hours: 110.92±12.54 vs. 74.47±11.18, both P < 0.05 ), the intestinal injury were ameliorated with decreased histopathological scores ( 12 hours: 1.70±0.06 vs. 3.23±0.44, 24 hours: 2.12±0.31 vs. 4.51±0.58, 48 hours: 2.03±0.42 vs. 4.27±0.58, all P < 0.05 ), and the intestinal MPO and caspase-3 activities were significantly decreased [ MPO ( U/g ): 6 hours: 13.75±4.21 vs. 25.56±5.34, 12 hours: 14.72±4.22 vs. 30.53±6.87, 24 hours: 11.62±3.14 vs. 33.58±7.24, 48 hours: 11.33±4.03 vs. 38.57±8.12; caspase-3 ( fluorescence intensity ): 6 hours: 0.37±0.07 vs. 0.69±0.23, 12 hours: 0.42±0.07 vs. 0.86±0.13, 24 hours: 0.53±0.11 vs. 1.36±0.23, 48 hours: 0.50±0.08 vs. 1.48±0.15, all P < 0.05 ] in hydrogen treatment group. Hydrogen inhalation can down-regulate the systemic inflammatory response to ameliorate the intestinal injury, and it may improve the septic process and increase the survival rate of mice with severe sepsis.