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). CONCLUSIONS Peripheral blood neutrophil apoptosis delayed and ROS production were increased in severely burned patients. The mechanism may be related to p38MAPK pathway inhibitor.
Apoptosis ; Burns ; Humans ; Neutrophils ; Signal Transduction ; p38 Mitogen-Activated Protein Kinases

OBJECTIVETo explore the effects of exogenous carbon monoxide-releasing molecules 2 (CORM-2) on LPS-induced abnormal activation of platelets in peripheral blood of healthy human donors and its possible molecular mechanism.

METHODSVenous blood samples were collected from a healthy volunteer, and platelet-rich plasma (PRP) from the blood were isolated by differential centrifugation. The PRP was subpackaged into siliconized test tubes and then divided into control group, LPS group, inactive CORM-2 (iCORM-2) group, 10 µmol/L CORM-2 group, and 50 µmol/L CORM-2 group according to the random number table, with 3 tubes in each group. The PRP in control group did not receive any treatment. The PRP in LPS group received LPS (20 mL, 10 µg/mL) stimulation, and the PRP in iCORM-2 group, 10 µmol/L CORM-2 group, and 50 µmol/L CORM-2 group underwent the same LPS stimulation and treatment of 50 µmol/L iCORM-2, 10 µmol/L CORM-2, and 50 µmol/L CORM-2, respectively, with the dosage of 20 mL. After being cultured for 30 min, the platelet adhesion rate was determined by glass bottle method, the number of platelet spreading on fibrinogen was determined with immunofluorescent method, and the platelet aggregation rate was measured by turbidimetric method. The platelet poor plasma (PPP) was prepared from PRP, the levels of ATP in PPP and platelets were determined by chemical fluorescein method. The expressions of platelet glycoprotein I bα (GPIbα) and GPVI were analyzed by flow cytometer. The expressions of glycogen synthase kinase 3β (GSK-3β) and phosphorylated GSK-3β were determined by Western blotting and immunoprecipitation, respectively. Measurement of the above indices was repeated for 3 times. Data were processed with one-way analysis of variance and SNK test.

RESULTSCompared with those in control group, the platelet adhesion rates, numbers of platelets spreading on fibrinogen, platelet aggregation rates, expressions of GPIbα and GPVI in PRP, levels of ATP in PPP in LPS and iCORM-2 groups were significantly increased, while levels of ATP in platelets were significantly decreased (with P values below 0.05). Compared with those in LPS group, the former 7 indices in iCORM-2 group showed no significant differences (with P values above 0.05), while the levels of ATP in platelets in the 10 µmol/L CORM-2 and 50 µmol/L CORM-2 groups were significantly increased, and the other 6 indices in 10 µmol/L CORM-2 and 50 µmol/L CORM-2 groups were significantly decreased (with P values below 0.05). The expression levels of GSK-3β of the platelets in PRP in control, LPS, iCORM-2, 10 µmol/L CORM-2, and 50 µmol/L CORM-2 groups were 0.550 ± 0.060, 1.437 ± 0.214, 1.210 ± 0.108, 0.720 ± 0.010, and 0.670 ± 0.010, respectively, and the expression levels of the phosphorylated GSK-3β of the platelets in PRP in the above 5 groups were 0.950 ± 0.070, 1.607 ± 0.121, 1.420 ± 0.040, 1.167 ± 0.015, and 0.513 ± 0.122, respectively. Compared with those in control group, both the expression levels of GSK-3β and phosphorylated GSK-3β of the platelets in PRP in LPS and iCORM-2 groups were significantly increased (with P values below 0.05). The expression levels of GSK-3β and phosphorylated GSK-3β of the platelets in PRP between LPS group and iCORM-2 group were similar (with P values above 0.05). The expression levels of GSK-3β and phosphorylated GSK-3β of the platelets in PRP in 10 µmol/L CORM-2 and 50 µmol/L CORM-2 groups were significantly decreased compared with those in LPS group (with P values below 0.05).

CONCLUSIONSLPS stimulation can abnormally activate the platelets in peripheral blood of healthy human, but the abnormal activation can be inhibited by CORM-2 intervention, and the mechanism of the latter may involve the phosphorylation of GSK-3β mediated by GP.

Blood Platelets ; drug effects ; metabolism ; Carbon Monoxide ; metabolism ; Glycogen Synthase Kinase 3 ; Glycogen Synthase Kinase 3 beta ; Humans ; Lipopolysaccharides ; pharmacology ; Organometallic Compounds ; pharmacology ; Phosphorylation ; drug effects ; Platelet Activation ; drug effects ; Platelet Aggregation ; drug effects ; Platelet-Rich Plasma

OBJECTIVE: To investigate the effect and mechanism of autophagy on the expression of neutrophil programmed death ligand-1 (PD-L1) in mice with sepsis. METHODS: (1) In vivo experiment: male C57BL/6 mice aged 6-8 weeks were divided into sham operation group (Sham group), cecum ligation and perforation (CLP) group, and rapamycin (RAP)+CLP group by random number table with 10 mice in each group. The sepsis model was reproduced by CLP, and the cecum and perforation were not ligated in Sham group, and other operations were the same as CLP group. The mice in RAP+CLP group were intraperitoneally injected with autophagy agonist RAP 4 mg×kg^-1×d^-1 7 days before modeling, while the mice in Sham group and CLP group were not treated. Lung, liver, spleen and pancreas tissues were harvested for immunohistochemical staining 4 days after the operation, and the infiltration of neutrophils in various organs was observed under light microscope. Meanwhile, the expressions of immunosuppressive molecule PD-L1 and autophagy marker microtubule-associated protein 1 light chain 3 (LC3) in lung neutrophils were determined by immunofluorescence staining. (2) In vitro experiment: mouse bone marrow neutrophils were extracted and re-suspended to 1×10¹⁰/L, and they were divided into blank control group (without any treatment), RAP control group (RAP 100 μmol/L), autophagy inhibitor Bafilomycin A1 (Baf) control group (Baf 10 μmol/L), lipopolysaccharide (LPS) stimulation group (LPS 1 mg /L), RAP+LPS group, and Baf+LPS group. The latter two groups were pretreated with 100 μmol/L RAP or 10 μmol/L Baf 30 minutes before LPS stimulation, respectively. The expression of PD-L1 mRNA of neutrophils was determined by reverse transcription-polymerase chain reaction (RT-PCR) at 0, 4, 12 hours after LPS stimulation. At the same time, the expressions of PD-L1, LC3 and p62 at the protein level were determined by Western Blot. RESULTS: (1) In vivo experiment: according to immunohistochemical experiments, a large amount of infiltration of neutrophils in lung, liver, spleen and pancreas was found at 4 hours after CLP. In the immunofluorescence, with the time extension after CLP, the positive expression of LC3 in the lung tissue showed a decreased tendency, and PD-L1 expression was significantly increased. RAP pretreatment could promote the expression of LC3 and reduce the expression of PD-L1 in CLP mice. (2) In vitro experiment: in terms of mRNA levels, with the extension of LPS stimulation time, the expression of PD-L1 mRNA in mouse neutrophils was increased continuously, and peaked at 12 hours, it was significantly higher than that in the blank control group (2^-ΔΔCT: 72.2±10.0 vs. 13.0±0.8, P < 0.01). Compared with LPS stimulation group, the expression of PD-L1 mRNA in RAP+LPS group was significantly down-regulated [12-hour PD-L1 mRNA (2^-ΔΔCT): 47.4±7.3 vs. 72.2±10.0, P < 0.01]. In Baf+LPS group, PD-L1 mRNA expression was significantly up-regulated as compared with that in LPS stimulation group [12-hour PD-L1 mRNA (2^-ΔΔCT): 109.1±7.4 vs. 72.2±10.0, P < 0.01]. At the protein levels, at 4 hours after LPS stimulation, the positive expressions of PD-L1, LC3 and p62 were increased significantly as compared with those in the blank control group, and PD-L1 and p62 were increased continuously with time. Compared with the LPS stimulation group, the expressions of PD-L1 and p62 in the RAP+LPS group were significantly down-regulated, while the expression of LC3 was continually increased, indicating that the level of autophagy was increased, and autophagy was circulated smoothly. On the contrary, the expressions of PD-L1, LC3 and p62 in the Baf+LPS group were significantly up-regulated, indicating that the binding of autophagy and lysosome was blocked, and autophagy was not smooth. CONCLUSIONS In sepsis, the infiltration of neutrophils in all organs increased, and the expression of PD-L1 of neutrophils in lungs was increased significantly, while the expression level of autophagy was decreased. The expression of PD-L1 stimulated by LPS can be inhibited by autophagy agonists, and promoted by autophagy inhibitors. PD-L1 has a negative regulatory effect on sepsis. It can reduce the expression of PD-L1 molecule in sepsis by targeting autophagy, so as to improve sepsis.
Animals ; Autophagy ; B7-H1 Antigen/metabolism* ; Male ; Mice ; Mice, Inbred C57BL ; Models, Animal ; Neutrophils ; Sepsis