Effect Of Hydrogen On The Early Lung Injury In Severe Burned Mice

Objective:Burns are one of the most devastating diseases and one of the main causes of the global public health crisis.Severe physical disturbance and respiratory failure after burns are the main causes of high mortality.The early lung injury after burns is the early pathophysiological change of acute respiratory distress syndrome which can lead to the dysfunction of distant organ.Therefore,stop from the early lung injury in burns is the key point to bring the disease under control.Our previous studies have shown that hydrogen gas can alleviate the acute lung injury in septic mice,and effectively improve the survival rate and the organ function of septic mice.The mechanism is related to anti-oxidative stress response,inhibition of inflammatory response and apoptosis.On this basis,we will further explore the effects of hydrogen on the early lung injury of burned mice,which will lays a scientific foundation for new treatment strategies for burn patients.Methods:One hundred and ninety-two adult male ICR mice,aged 6 weeks,weighing20²5 g,were divided into four groups using a random number table?n=48?:sham operation group?SH group?,H₂ group,burn blast group?BB group?and burn blast+H₂ group?BB+H₂ group?.Mice in BB group and BB+H₂ group were inflicted with40%total body surface area full-thickness scald on the back,while mice in SH group and H₂ group were sham injured.Mice in H₂ group and BB+H₂ group inhaled 2%hydrogen for 1 h at post injury hour?PIH?1 and 6,respectively,while mice in SH group and BB group inhaled air for 1 h.The survival rates of twenty mice in each group during post injury days 7 were calculated.At PIH 24,lung tissue of six mice in each group was harvested,and then pathological changes of lung tissue were observed by HE staining and the lung tissue injury pathological score was calculated.At PIH 24,after arterial blood of six mice in each group was collected for detection of arterial partial pressure of oxygen?PaO₂?,the wet and dry weight of lung tissue were weighted to calculate lung wet to dry weight ratio.Inferior vena cava blood and lung tissue of other eight mice in each group were obtained,and then content of high mobility group box 1?HMGB1?and interleukin-6?IL-6?in serum and lung tissue was determined by enzyme-linked immunosorbent assay.Activity of superoxide dismutase?SOD?in serum and lung tissue was detected by spectrophotometry.Activity of myeloperoxidase?MPO?was detected by MPO test kit.The Bronchoalveolar lavage fluid of eight mice in each group was collected to detect the content of HMGB1 and IL-6.Total cellular score and neutrophil differential count were counted by hemocytometer.Results:The survival rate of mice in SH group and H₂ group during post injury days7 were 100%.Compared with those in SH group,survival rates of mice in BB group from post injury days 3 to 7 were significantly decreased?P<0.05?.Compared with those in BB group,survival rates of mice in BB+H₂ group from post injury days 5 to7 were significantly increased?P<0.05?.At PIH 24,lung tissue of mice in sham injury group and hydrogen group showed no abnormality.Mice in BB group were with pulmonary interstitial edema,serious rupture of alveolar capillary wall,and infiltration of a large number of inflammatory cells.Mice in BB+H₂ group were with mild pulmonary interstitial edema,alveolar capillary congestion accompanied by slight rupture and bleeding,and the number of infiltration of inflammatory cells was smaller than that in BB group.The lung tissue injury pathological scores of mice in SH group,H₂ group,BB group and BB+H₂ were?0.7±0.5?,?0.8±0.5?,?6.1±1.0?and?2.8±0.8?points,respectively.The lung tissue injury pathological score of mice in BB group was significantly higher than that in SH group?P<0.05?.The lung tissue injury pathological score of mice in BB+H₂ group was significantly lower than that in BB group?P<0.05?.At PIH 24,there was no statistically significant difference in PaO₂ among the mice in four groups?F=0.04,P>0.05?.At PIH 24,the ratios of lung wet to dry weight of mice in SH group,H₂ group,BB group and BB+H₂ group were 3.52±0.22,3.61±0.24,7.24±0.32,5.21±0.41,respectively.The ratio of lung wet to dry weight of mice in BB group was significantly higher than that in SH group?P<0.05?.The ratio of lung wet to dry weight of mice in BB+H₂ group was significantly lower than that in BB group?P<0.05?.At PIH 24,the content of HMGB1 and IL-6 in serum and lung tissue of mice in H₂ group was close to that in SH group?P>0.05?.The content of HMGB1 and IL-6 in serum and lung tissue of mice in BB group was significantly higher than that in SH group?P<0.05?.The content of HMGB1 and IL-6 in serum and lung tissue of mice in BB+H₂ group was significantly lower than that in BB group?P<0.05?.At PIH 24,the activity of SOD in serum and lung tissue of mice in H₂ group was close to that in SH group?P>0.05?.The activity of SOD in serum and lung tissue of mice in BB group was significantly lower than that in SH group?P<0.05?.The activity of SOD in serum and lung tissue of mice in BB+H₂ group was significantly higher than than in BB group?P<0.05?.At PIH 24,the activity of MPO in lung tissue of mice in H₂ group was close to that in SH group?P>0.05?.The activity of MPO in lung tissue of mice in BB group was significantly higher than that in SH group?P<0.05?.The activity of MPO in lung tissue of mice in BB+H₂ group was significantly lower than than in BB group?P<0.05?.At PIH 24,the content of HMGB1 and IL-6,total cellular score and neutrophil differential count in bronchoalveolar lavage fluid of mice in H₂ group was close to that in SH group?P>0.05?.The content of HMGB1 and IL-6,total cellular score and neutrophil differential count in bronchoalveolar lavage fluid of mice in BB group was significantly higher than that in SH group?P<0.05?.The content of HMGB1 and IL-6,total cellular score and neutrophil differential count in bronchoalveolar lavage fluid of mice in BB+H₂ group was significantly lower than than in BB group?P<0.05?.Conclusions:2%hydrogen gas inhalation can significantly improve the 7-day survival rate of the severe burn mice with early lung injury.Hydrogen can significantly alleviate the infiltration of inflammatory cells and improve the pathological lesions of lung tissue of mice with severe burn.It has the effects of reducing inflammatory reaction and inhibiting oxidative stress,further showing the protective effect on the lung of burn mice.