Objective:To observe the changes of peripheral blood neutrophil apoptosis rate and the effect of p38 mitogen-activated protein kinase (p38MAPK) inhibitor on peripheral blood neutrophil apoptosis in severely burned patients.

Methods:Severe burn patients [burn area ≥ 30% total body surface area (TBSA), deep Ⅱ to Ⅲ degrees, burn index ≥ 20%, age > 20 years old] admitted to the department of burn and plastic surgery of Affiliated Suzhou Hospital of Nanjing Medical University from January to May in 2019 and health examination volunteers during the same period were enrolled. The peripheral blood neutrophils were isolated by Ficoll gradient centrifugation. The neutrophils of severely burned patients were divided into burn group and p38MAPK inhibitor SB203580 group (after 30 minutes incubation at room temperature and 24 hours incubation in incubator); the neutrophils of healthy volunteers were used as control group. The apoptosis of neutrophils was detected by flow cytometry; the level of reactive oxygen species (ROS) in neutrophils was detected by fluorescence probe; the expression of p38MAPK protein and its phosphorylation (p-p38MAPK) level were detected by Western Blot.

Results:Compared with the control group, the apoptosis rate of neutrophils in burn group was significantly decreased [(37.42±3.14)% vs. (50.20±9.87)%, P < 0.05], and the ROS production level in neutrophils was significantly increased (fluorescence intensity: 83.28±0.29 vs. 75.23±0.34, P < 0.05). The apoptosis rate of neutrophils in SB203580 group was further lower than that in burn group [(25.51±1.56)% vs. (37.42±3.14)%, P < 0.05], and the level of ROS production was further higher than that in burn group (fluorescence intensity: 95.56±3.67 vs. 83.28±0.29, P < 0.05). There was no significant difference in the protein expression of p38MAPK among the three groups. The p-p38MAPK protein level in burn group was significantly lower than that in control group (p-p38MAPK/p38MAPK: 0.45±0.06 vs. 0.91±0.09, P < 0.05), while the expression level of p-p38MAPK in SB203580 group was further lower than that in burn group (p-p38MAPK/p38MAPK: 0.22±0.04 vs. 0.45±0.06, P < 0.05).

Conclusion:Peripheral blood neutrophil apoptosis delayed and ROS production were increased in severely burned patients. The mechanism may be related to p38MAPK pathway inhibitor.