Effects of exogenous carbon monoxide-releasing molecule 2 intervention in vitro on formation of human neutrophil extracellular traps stimulated by endotoxin/lipopolysaccharide and its mechanism / 中华烧伤杂志

<p><b>OBJECTIVE</b>To explore the effects of exogenous carbon monoxide-releasing molecule 2 (CORM-2) on formation of human neutrophil extracellular traps (NETs) stimulated by endotoxin/lipopolysaccharide (LPS) and its relevant mechanism.</p><p><b>METHODS</b>Venous blood samples were collected from a healthy adult volunteer to isolate neutrophils. The neutrophils were divided into normal control (NC) group, LPS group, LPS+ 10 μmol/L CORM-2 group, LPS+ 50 μmol/L CORM-2 group, and LPS+ inactive CORM-2 (iCORM-2) group according to the random number table. No treatment was given to the neutrophils in NC group. The neutrophils in LPS group underwent LPS stimulation (1 μL, 1 μg/mL). The neutrophils in LPS+ 10 μmol/L CORM-2 group, LPS+ 50 μmol/L CORM-2 group, and LPS+ iCORM-2 group underwent the same LPS stimulation as that in LPS group and treatment of 10 μmol/L CORM-2, 50 μmol/L CORM-2, and 50 μmol/L iCORM-2, respectively, with the volune of 1 μL. After conventional culture for 1 h, the number of NETs was determined with propidium iodide staining method; the early cell apoptosis rate was determined with flow cytometer; the generation level of reactive oxygen species (ROS) was assessed with dihydrogenrhodamine 123 fluorescent probe staining method (denoted as mean fluorescence intensity); the expression level of phosphorylated extracellular regulated kinase 1/2 (p-ERK1/2) was determined by Western blotting. The sample numbers of each group in the 4 experiments were all 5. Data were processed with one-way analysis of variance and SNK test.</p><p><b>RESULTS</b>(1) The numbers of NETs per 400-time visual field in cells of LPS and LPS+ iCORM-2 groups were close to the number in NC group (with P values above 0.05). The number of NETs per 400-time visual field was significantly larger in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups than in NC and LPS groups (with P values below 0.05). The number of NETs per 400-time visual field in cells of LPS+ iCORM-2 group was close to that of LPS group (P>0.05). (2) The early cell apoptosis rate was significantly increased in LPS, LPS+ 10 μmol/L CORM-2, LPS+ 50 μmol/L CORM-2, and LPS+ iCORM-2 groups than in NC group (with P values below 0.05). The early cell apoptosis rates in LPS+ 10 μmol/L CORM-2, LPS+ 50 μmol/L CORM-2, and LPS+ iCORM-2 groups were close to the rate in LPS group (with P values above 0.05). (3) The generation level of ROS was significantly higher in cells of LPS, LPS+ 10 μmol/L CORM-2, and LPS+ iCORM-2 groups than in NC group (with P values below 0.05). The generation level of ROS in cells of LPS+ 50 μmol/L CORM-2 group was close to that of NC group (P>0.05). The generation level of ROS was lower in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups than in LPS group (with P values below 0.05), while the generation level of ROS in cells of LPS+ iCORM-2 group was close to that of LPS group (P>0.05). (4) The expression levels of p-ERK1/2 in cells of LPS and LPS+ iCORM-2 groups (respectively 0.0311±0.001 and 0.0309±0.0018) were close to the level in NC group (0.0304±0.0046, with P values above 0.05). The expression level of p-ERK1/2 was significantly higher in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups (respectively 0.7891±0.0201 and 1.2970±0.0056) than in NC group (with P values below 0.05). The expression level of p-ERK1/2 was significantly higher in cells of LPS+ 10 μmol/L CORM-2 and LPS+ 50 μmol/L CORM-2 groups than in LPS group (with P values below 0.05). The expression level of p-ERK1/2 in cells of LPS+ iCORM-2 group was close to that of LPS group (P>0.05).</p><p><b>CONCLUSIONS</b>CORM-2 can obviously increase the production of NETs in LPS-induced neutrophils, and it might be attributable to the promotion of inhibition of ROS generation and phosphorylation of ERK1/2.</p>

Suppressive effect of exogenous carbon monoxide on abnormal platelet exocytosis and its molecular mechanism in sepsis / 中华危重病急救医学

Objective To investigate the suppressive effect of exogenous carbon monoxide (CO) on abnormal platelet exocytosis and its possible molecular mechanism. Methods Venous blood was collected from healthy volunteers. Platelet-rich plasma (PRP) was isolated from the blood by differential centrifugation. The PRP was randomly divided into five groups by random number table, namely normal control group, lipopolysaccharide (LPS) group (challenged with 10 mg/L LPS), inactively exogenous carbon monoxide releasing molecule 2 (iCORM-2) group (given 10 mg/L LPS + 50 μmol/L iCORM-2 for intervention), exogenous carbon monoxide releasing molecule 2 (CORM-2) 10 μmol/L and 50 μmol/L groups (given 10 mg/L LPS + CORM-2 10 μmol/L or 50 μmol/L for intervention). After 30 minutes, enzyme linked immunosorbent assay (ELISA) was used to determine the platelet-derived growth factor BB (PDGF-BB) and matrix metalloproteinase 2 (MMP-2). Chemical fluorescein method was used to determine the platelet adenosine triphosphate (ATP). Flow cytometer was used to determine the expression of P-selectin. The expressions of Toll-like receptor 4 (TLR4), phosphorylation of protein kinase Cθ (PKCθ) and syntaxin binding protein 1 (STXBP-1) were determined by Western Bolt. The soluble N-ethylmaleimide-sensitive factor-attachment protein receptors (SNAREs) complex formation [syntaxin 2-synaptosomal-associated protein 23-vesicle associated membrane protein 8 (STX2-SNAP23-VAMP8)] mediated by STXBP-1 was determined by immunoprecipitation. Results ① Compared with normal control group, the platelet release of PDGF-BB, MMP-2 and ATP was significantly increased after LPS challenge, and the P-selectin expression of platelet was also obviously up-regulated [PDGF-BB (μg/L): 127.53±1.78 vs. 94.35±5.84, MMP-2 (ng/L): 51.87±9.20 vs. 35.83±3.17, ATP (μmol/L): 1.288±0.056 vs. 0.975±0.010, P-selectin: (3.93±0.19)% vs. (0.44±0.10)%, all P < 0.05]. The increases in platelet release of PDGF-BB, MMP-2 and ATP were suppressed by 10 μmol/L or 50 μmol/L CORM-2 administration, as well as high-expression of P-selectin in a dose-dependent manner [PDGF-BB (μg/L): 114.68±1.35, 97.08±6.14 vs. 127.53±1.78, MMP-2 (ng/L): 32.67±8.00, 24.63±1.63 vs. 51.87±9.20, ATP (μmol/L): 0.999±0.015, 0.965±0.008 vs. 1.288±0.056, P-selectin: (1.95±0.27)%, (0.94±0.11)% vs. (3.93±0.19)%, all P < 0.05]. ② Compared with normal control group, LPS challenge resulted in a significant increase in the expression of TLR4 and the phosphorylation of PKCθ and STXBP-1 [TLR4 (gray value): 1.21±0.38 vs. 0.67±0.06, p-PKCθ (gray value): 1.36±0.20 vs. 0.44±0.03, p-STXBP-1 (gray value): 1.13±0.06 vs. 0.59±0.04, all P < 0.05]. The increases in above parameters were suppressed by 10 μmol/L or 50 μmol/L CORM-2 administration in a dose-dependent manner [TLR4 (gray value): 0.76±0.05, 0.65±0.04 vs. 1.21±0.38; p-PKCθ (gray value): 0.71±0.07, 0.47±0.10 vs. 1.36±0.20; p-STXBP-1 (gray value): 0.56±0.02, 0.48±0.01 vs. 1.13±0.06, all P < 0.05]. ③ Compared with normal control group, the SNAREs proteins in platelet that combined with STXBP-1, including STX2, SNAP23 and VAMP8, were obviously increased after LPS challenge [STX2 (gray value): 1.35±0.06 vs. 0.57±0.04, SNAP23 (gray value): 0.97±0.04 vs. 0.30±0.12, VAMP8 (gray value): 1.37±0.12 vs. 0.77±0.10, all P < 0.05]. The increases in SNAREs complex formation were suppressed by 10 μmol/L or 50 μmol/L CORM-2 administration in a dose-dependent manner [STX2 (gray value): 0.77±0.02, 0.39±0.03 vs. 1.35±0.06, SNAP23 (gray value): 0.41±0.03, 0.22±0.08 vs. 0.97±0.04, VAMP8 (gray value): 0.85±0.07, 0.66±0.07 vs. 1.37±0.12, all P < 0.05]. There was no significant difference in the above mentioned parameters between iCORM-2 group and LPS group. Conclusions LPS-induced abnormal secretion of platelet was suppressed by CORM-2 administration. The mechanism may involve the TLR4/PKCθ/STXBP-1 signaling pathway activation and the SNAREs complex formation.

novel strategy for antimicrobial agent: role of exogenous carbon monoxide on suppressing Escherichia coli vitality and toxicity

Sepsis is a severe systemic inflammatory response mostly caused by gram-negative bacterial infections. The rates of mortality in sepsis patients remain high. To date little is known about whether exogenous carbon monoxide can directly or indirectly inhibit or even kill gram negative bacteria. In our study, we demonstrate a critical role of CO-releasing molecules in the suppressive effects on bacterial vitality and toxicity. We found the bacterial growth and colony forming were markedly suppressed in the presence of CORM-2 with significant cell damage, decreased or disappeared pili and flagella. In contrast, qRT-PCR showed the expression of fliA was downregulated, while dnaK and waaQ were upregulated in E. coli+CORM-2. Subsequent in vivo experiments showed the mouse survival in the CORM- 2 intervened-E.coli injection tended to improve with 60%-100% survival rates, and colony distribution in major organs were significantly decreased with attenuated histological damage. In parallel, cytokine levels and myeloperoxidase accumulation in livers and lungs decreased significantly compared with E. coli group. These data provide the first evidence and a potential strategy that exogenous carbon monoxide can significantly suppress bacterial vitality and toxicity. This may be associated with the regulatory functions of CORM-2 on the expression of essential genes [fliA, dnaK and waaQ] in E. coli

Effect and mechanism of exogenous carbon monoxide against excessive neutrophil infiltration in liver and lung tissues during sepsis / 中华创伤杂志

Objective To determine the inhibitory effect and mechanism of exogenous carbon monoxide against excessive neutrophil infiltration in liver and lung tissues during sepsis.Methods Thirty-two mice were subjected to sham operation (sham group),cecal ligation and perforation (CLP) group,CLP with 8 mg/kg of exogenous carbon monoxide releasing molecule Ⅱ (CORM-2) (CORM-2 group),and CLP with 8 mg/kg of inactive variants of CORM-2 (iCORM-2) (iCORM-2 group) according to the random number table,with 8 mice per group.Liver and lung tissues were collected at 24 hours after surgery to examine the pathologic changes,myeloperoxidase (MPO) activity and malonaldehyde (MDA) content.Another 60 mice were enrolled into the same 4 groups with 15 mice per group and were tested for 72-hour survival rate.Bone marrow neutrophils were isolated and divided into normal control group,1 μg/ml lipopolysaccharide (LPS) group,1 μg/ml LPS plus 10 μmol/L CORM-2 group (low dose group),1 μg/ml LPS plus 50 μmol/L CORM-2 group (high dose group),1 μg/ml LPS plus 50 μmol/L iCORM-2 group (iCORM-2 group).Under the agarose chemotaxis,qPCR and immunofluorescence detection of formyl peptide receptor 1 (FPR1) were performed.Results CLP group presented enhanced activity of MPO [liver:(9.1 ± 1.1) U/g,lung:(16.3 ± 2.8) U/g],increased MDA content [liver:(76.5 ±11.3) nmol/mg,lung:(32.4 ± 10.3) nmol/mg] and 72-hour survival rate of 20％ as compared with the sham group (all P ＜ 0.05).CORM-2 group showed inhibited activity of MPO [liver:(5.2 ± 0.8) U/g,lung:(7.5 ± 2.4) U/g],increased MDA content [liver:(46.7 ± 6.1) nmol/mg,lung:(23.8 ±7.3) nmol/mg] and 72-hour survival rate of 67％ as compared with the sham group (all P ＜ 0.05).LPS enhanced neutrophil migration (61.3 ± 7.1) (P ＜ 0.05) and expression of FPR1 which was enriched in the membrane.Meanwhile,neutrophil migration was significantly inhibited in a dose-dependent of CORM-2 (low dose group:43.3 ±6.1,high-dose group:23.3 ±5.9) (P＜0.05).Conclusions Exogenous carbon monoxide is effective to inhibit the excessive neutrophil infiltration,attenuate oxidative stress or pathological injury,and improve the survival from sepsis.The mechanism is associated with the down-regulation of FPR1,inhibition of FPR1 enrichment in the membrane,and decreased neutrophil migration.

Inhibitory effects of Kukoamine B on the inflammatory response of small intestine in lipopolysaccharide- induced septic mice and its potential mechanisms / 中华危重病急救医学

ObjectiveTo study the role of Kukoamine B (KB) in inhibiting the inflammatory response of small intestine in septic mice and its molecular mechanisms.Methods Twenty-four male ICR mice were randomly divided into control group, model group, and KB intervention group (each,n= 8). Sepsis model was reproduced by intra-peritoneal injection of 20 mg/kg lipopolysaccharide (LPS), while equivalent normal saline was given in control group, and 20μg/kg KB was injected through caudal vein 4 hours after LPS challenge in KB intervention group. The blood/tissue samples (jejunum and ileum) were harvested 8 hours after LPS injection. The levels of plasma LPS, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured. The pathological changes in small intestine tissues were observed under light microscope, while the levels of inflammatory cytokines TNF-α and IL-1β in the tissue homogenates (jejunum and ileum) were assessed by enzyme linked immunosorbent assay (ELISA). The activity of myeloperoxidase (MPO) was measured by colorimetry. The expression of intercellular adhesion molecule-1 (ICAM-1) was determined by immunohistochemistry. The expressions of inducible nitric oxide synthase (iNOS) mRNA was assayed by reverse transcription-polymerase chain reaction (RT-PCR). The activation of nuclear factor-κΒ (NF-κΒ) was determined by Western Blot.Results The mice in model group were found to have an increase in microvascular permeability, interstitial edema, and infiltration of white blood cells, and the levels of LPS, TNF-α and IL-1β in their plasma, with an increase in concentrations of TNF-α and IL-1β, activity of MPO, positive expression of ICAM-1, expression of iNOS mRNA and NF-κB protein in small intestine (jejunum and ileum). Compared with model group, in mice with KB intervention, microvascular permeability, interstitial edema, and infiltration of white blood cells were reduced significantly, while the levels of LPS, TNF-α and IL-1β in plasma, the concentration of TNF-α and IL-1β, the activity of MPO, the positive expression of ICAM-1, the expression of iNOS mRNA and NF-κB protein in small intestine (jejunum and ileum) were significantly decreased [plasma LPS (kEU/L): 654.09±28.13 vs. 1 155.65±47.15, TNF-α (ng/L): 12.75±0.47 vs. 30.61±0.71, IL-1β (ng/L): 53.06±5.32 vs. 64.47±2.61; jejunum TNF-α(ng/L): 43.27±1.20 vs. 64.82±2.09, IL-1β (ng/L): 326.38±14.47 vs. 535.22±13.48, MPO (U/g): 0.14±0.01 vs. 0.32±0.02, iNOS mRNA (2-ΔΔCt): 2.39±0.13 vs. 10.80±0.22, NF-κB protein (gray value): 0.687±0.062 vs. 1.404±0.046; ileum TNF-α (ng/L): 62.75±3.92 vs. 104.24±2.82, IL-1β(ng/L): 408.06±1.70 vs. 521.97±1.16, MPO (U/g): 0.36±0.08 vs. 0.66±0.05, iNOS mRNA (2-ΔΔCt): 1.65±0.11 vs. 3.59±0.29, NF-κB protein (gray value):0.830±0.114 vs. 1.609±0.051, allP< 0.05].Conclusion KB can combine with LPS and inhibit LPS/Toll-like receptor 4 (TLR4) signaling pathway, thereby significantly inhibit the inflammatory response and protect the function of the small intestine in LPS-induced septic mice.

Inhibitory effect of kukoamine B on lung inflammatory responses in mice with sepsis / 中华危重病急救医学

Objective To investigate the inhibitory effect of kukoamine B (KB) on lung inflammatory responses in mice with sepsis and its possible molecular mechanism.Methods Twenty-eight male mice were randomly divided into control group (n=8),lipopolysaccharide (LPS) group (n=10),and LPS + KB group (n=10).Sepsis model was reproduced by intra-peritoneal injection of 20 mg/kg LPS,while equivalent normal saline was given in control group,and 20 μg/kg KB was injected through caudal vein 4 hours after LPS challenge in LPS + KB group.After 8 hours of LPS challenge,the concentration of LPS in plasma and the activity of myeloperoxidase (MPO) in the lung tissue were determined.The contents of tumor necrosis factor-α (TNF-α) and interleukin-lβ (IL-1β) in plasma,alveolar lavage fluid and lung tissue homogenates were assessed by enzyme linked immunosorbent assay (ELISA).The activation of nuclear factor-κB (NF-κB) and the expression of inducible nitric oxide synthase (iNOS) in lung tissue were determined by Western Blot.The pathological changes in lung tissues were observed with hematoxylin-eosin (HE) staining.The expression of intercellular adhesion molecule-1 (ICAM-1) in lung tissue was determined by immunohistochemistry.Results Compared with control group,the concentration of LPS in plasma (kEU/L:1 155.650 ± 147.149 vs.31.390 ± 18.859),MPO activity (U/g:1.177 ±0.093 vs.0.775 ±0.166),NF-κB activity (gray value:1.557 ±0.105 vs.0.824 ±0.032) and the expression of iNOS (gray value:0.650 ±0.129 vs.0.392 ±0.097) were significantly increased in LPS group (all P＜0.05).After KB intervention,the concentration of LPS (624.461 ± 149.012),MPO activity (0.919 ±0.023),NF-κB activity (1.127 ±0.074) and the expression ofiNOS (0.425 ± 0.066) were significantly lowered (all P＜0.05).Compared with control group,the contents of TNF-α (ng/L:47.325 ± 13.864 vs.6.534 ± 0.544,13.382 ± 2.231 vs.3.748 ± 0.692,31.127 ± 7.399 vs.14.948 ± 4.673) and IL-1β (ng/L:74.329 ± 11.890 vs.29.921 ± 6.487,9.422 ± 2.674 vs.1.105 ± 0.364,528.509 ± 32.073 vs.109.945 ± 13.561) in plasma,alveolar lavage fluid and lung tissue homogenates were obviously enhanced in LPS group (all P＜0.05).With KB intervention,the contents of TNF-α (20.331 ± 7.789,7.145 ± 1.202,15.966 ± 2.946) and IL-1β (57.707 ±8.098,2.212 ± 0.878,426.154 ± 11.270) were markedly reduced (plasma TNF-α:F=16.052,P=0.002; IL-1β:F=20.649,P=0.000; lung tissue homogenates TNF-α:F=31.134,P=0.001; IL-1β:F=22.792,P=0.002;alveolar lavage fluid TNF-α:F=10.013,P=0.009; IL-1β:F=319.857,P=0.000).In addition,leukocyte infiltration to the lung tissue was attenuated,and the expression of ICAM-1 was reduced by KB in histological examination.Conclusion KB,as a neutralizer of LPS,can inhibit the release of inflammatory mediators,reduce the pulmonary inflammatory response and protect the function of lung in septic mice.