Effect of hydrogen on autophagy during inflammatory responses following lung injury in burned mice

Abstract

Objective To evaluate the effect of hydrogen on autophagy during inflammatory responses following lung injury in burned mice. Methods Ninety-six clean-grade healthy male ICR mice, aged 6 weeks, weighing 20-25 g, were divided into 4 groups (n=24 each) using a random number table: sham operation group (SH group), H2 group (H2 group), burn group (B group) and burn plus H2 group (B+ H2 group). Forty percent of the total body surface was shaved with 80 g/L sodium sulfide and then exposed to a 92 ℃ scald device for 18 s in B and B+ H2 groups.Forty percent of the total body surface was shaved with 80 g/L sodium sulfide and then exposed to a scald device of skin temperature for 18 s in SH and H2 groups.Mice inhaled 2% H2 for 1 h starting from 1 and 6 h after burn in H2 and B+ H2 groups.The animals were sacrificed at 24 h after burn and lungs were removed for determination of wet/dry weight ratio (W/D ratio), expression of autophagy-related microtubule-associated protein 1 light chain 3 (LC3) (by Western blot), activity of myeloperoxidase (MPO), and contents of interleukin-6 (IL-6) and high mobility group box 1 (HMGB1) (by enzyme-linked immunosorbent assay). The ratio of LC3-Ⅱ to LC3-Ⅰexpression (LC3-Ⅱ/LC3-Ⅰ) was calculated.The bronchoalveolar lavage fluid (BALF) was collected at 24 h after burn to detect the concentrations of IL-6 and HMGB1 and to count neutrophil. Results Compared with group SH, the W/D ratio, levels of LC3-Ⅱ/LC3-Ⅰ, MPO, IL-6 and HMGB1, concentrations of IL-6 and HMGB1 in BALF and neutrophil count were significantly increased at 24 h after scald in B and B+ H2 groups (P<0.05). Compared with group B, the W/D ratio, levels of LC3-Ⅱ/LC3-Ⅰ, MPO, IL-6 and HMGB1, concentrations of IL-6 and HMGB1 in BALF and neutrophil count were significantly decreased at 24 h after scald in group B+ H2 (P<0.05). Conclusion Hydrogen can alleviate the lung injury in burned mice, and the mechanism is related to enhancing autophagy. Key words: Hydrogen; Burn; Lung; Inflammation; Autophagy