Mechanism of salutary effects of estrogen on cardiac function following trauma-hemorrhage: Akt-dependent HO-1 up-regulation.

OBJECTIVES: Because administration of 17beta-estradiol following trauma-hemorrhage improves cardiovascular responses, we investigated whether the salutary effects of 17beta-estradiol on cardiac function are mediated via Akt-dependent heme oxygenase-1 up-regulation under those conditions. DESIGN: Experimental animal study. SETTING: University laboratory. SUBJECTS: Male Sprague-Dawley rats. INTERVENTIONS: Rats underwent trauma-hemorrhage (mean blood pressure approximately 40 mm Hg for 90 mins) followed by fluid resuscitation. Before resuscitation, rats received either vehicle, 17beta-estradiol (1 mg/kg), or 17beta-estradiol plus the phosphoinositide 3-kinase inhibitor wortmannin (1 mg/kg). At 2 hrs after trauma-hemorrhage or sham operation, the rats were killed. MEASUREMENTS AND MAIN RESULTS: Cardiac function, heart tissue myeloperoxidase activity, cardiac and circulatory cytokine levels, cardiac intercellular adhesion molecule-1, and chemokine levels were measured. Cardiac Akt and heme oxygenase-1 were also determined. We found that 17beta-estradiol prevented the trauma-hemorrhage-induced impairment in cardiac function and increase in cardiac myeloperoxidase activity. Cardiac and systemic interleukin-6 and tumor necrosis factor-alpha levels as well as cardiac intercellular adhesion molecule-1, cytokine-induced neutrophil chemoattractant-1, and macrophage inflammatory protein-2 contents were increased following trauma-hemorrhage, which were normalized by 17beta-estradiol. Administration of 17beta-estradiol following trauma-hemorrhage restored cardiac Akt phosphorylation and further increased heme oxygenase-1 expression. Coadministration of wortmannin following trauma-hemorrhage abolished the previous effects by 17beta-estradiol. CONCLUSIONS: These results suggest that the 17beta-estradiol-meditated improvement in cardiac function following trauma-hemorrhage occurs via Akt-dependent heme oxygenase-1 up-regulation.

Role of extracellular signal-regulated protein kinase (ERK) in 17beta-estradiol-mediated attenuation of lung injury after trauma-hemorrhage.

BACKGROUND: Extracellular signal-regulated protein kinase (ERK) is known to be involved in pro-inflammatory and chemotactic events in response to injury. The aim of this study is to elucidate whether ERK plays any role in 17beta-estradiol (E2)-mediated attenuation of lung injury and pro-inflammatory mediators after trauma-hemorrhage. METHODS: Male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure approximately 40 mm Hg for 90 min) followed by fluid resuscitation. At the onset of resuscitation, rats were treated with vehicle (cyclodextrin), E2 (1 mg/kg body weight [BW]), or the ERK inhibitor PD98059 (2 mg/kg BW). At 2 h after sham operation or trauma-hemorrhage, various parameters were measured. RESULTS: Trauma-hemorrhage led to a significant increase in lung ERK phosphorylation, which was associated with increased lung myeloperoxidase activity, wet-to-dry weight ratio, interleukin (IL)-6, tumor necrosis factor (TNF)-alpha, intercellular adhesion molecule (ICAM)-1, cytokine-induced neutrophil chemoattractant (CINC)-1, and macrophage inflammatory protein-2 levels. Circulatory IL-6, TNF-alpha, and lactate levels were also increased after trauma-hemorrhage compared with shams. Administration of E2 or ERK inhibitor PD98059 after trauma-hemorrhage attenuated the trauma-hemorrhage-induced increase in lung injury markers, ERK phosphorylation and cytokines/chemokines, ICAM-1 production, as well as circulatory cytokines and lactate levels. CONCLUSION: These results collectively suggest that the salutary effects of E2 on the lung after trauma-hemorrhage are mediated via an ERK pathway and subsequent downregulation of pro-inflammatory mediator production.

The role of MIP-1 alpha in the development of systemic inflammatory response and organ injury following trauma hemorrhage.

Although MIP-1alpha is an important chemokine in the recruitment of inflammatory cells, it remains unknown whether MIP-1alpha plays any role in the development of systemic inflammatory response following trauma-hemorrhage (T-H). C57BL/6J wild type (WT) and MIP-1alpha-deficient (KO) mice were used either as control, subjected to sham operation (cannulation or laparotomy only or cannulation plus laparotomy) or T-H (midline laparotomy, mean blood pressure 35 +/- 5 mmHg for 90 min, followed by resuscitation) and sacrificed 2 h thereafter. A marked increase in serum alpha-glutathione transferase, TNF-alpha, IL-6, IL-10, MCP-1, and MIP-1alpha and Kupffer cell cytokine production was observed in WT T-H mice compared with shams or control. In addition lung and liver tissue edema and neutrophil infiltration (myeloperoxidase (MPO) content) was also increased following T-H in WT animals. These inflammatory markers were markedly attenuated in the MIP-1alpha KO mice following T-H. Furthermore, compared with 2 h, MPO activities at 24 and 48 h after T-H declined steadily in both WT and KO mice. However, normalization of MPO activities to sham levels within 24 h was seen in KO mice but not in WT mice. Thus, MIP-1alpha plays an important role in mediating the acute inflammatory response following T-H. In the absence of MIP-1alpha, acute inflammatory responses were attenuated; rapidly recovered and less remote organ injury was noted following T-H. Thus, interventions that reduce MIP-1alpha levels following T-H should be useful in decreasing the deleterious inflammatory consequence of trauma.

Estrogen ameliorates trauma-hemorrhage-induced lung injury via endothelial nitric oxide synthase-dependent activation of protein kinase G.

OBJECTIVE: In this study, we tested the hypothesis that 17beta-estradiol (E2) administration after trauma-hemorrhage reduces lung injury through a mechanism involving estrogen receptor (ER)-dependent activation of the endothelial nitric oxide (NO) synthase (eNOS)/protein kinase G (PKG)/vasodilator-stimulated phosphoprotein (VASP) pathway. BACKGROUND: Estrogen provides protection after injury via activation of multiple signaling cascades, including the cyclic GMP-dependent PKG pathway. Phosphorylation of VASP at Ser239 (p-VASP) can be used to assess PKG signaling activity. METHODS: Male Sprague-Dawley rats (275-325 g) underwent soft tissue trauma (midline laparotomy) and hemorrhagic shock (mean blood pressure 35-40 mm Hg for 90 minutes) followed by fluid resuscitation. Animals were pretreated with a nonselective NOS inhibitor (N(omega)-nitro-L-arginine methyl ester; 30 mg/kg), a soluble guanylyl cyclase (sGC) inhibitor [1H-(1, 2, 4) oxadiazolo (3, 4-alpha) quinoxalin-1-one; 10 mg/kg] or an ER antagonist (ICI 182,780; 3 mg/kg) 30 minutes before E2 (100 microg/kg) or vehicle administration. Animals were killed at 2 hours after resuscitation. RESULTS: Lung injury induced by trauma-hemorrhage is evidenced by edema (wet/dry ratio), neutrophil infiltration (myeloperoxidase activity), and with an increased expression of cytokines, chemokines, and adhesion molecules. E2 treatment after trauma-hemorrhage resulted in an increase in eNOS expression/phosphorylation, PKG-I activation, and VASP/p-VASP expression, which paralleled a decrease in lung injury. Inhibition of NOS and sGC abolished the E2-induced increase in PKG-I activity, VASP/p-VASP expression. Blockade of eNOS, PKG-I, and ER exacerbated lung inflammation and injury. CONCLUSIONS: These results collectively suggest that activation of the eNOS-PKG/VASP pathway by E2 protects against trauma-hemorrhage-induced lung injury.

Selective inhibition of iNOS attenuates trauma-hemorrhage/resuscitation-induced hepatic injury.

Although trauma-hemorrhage produces tissue hypoxia, systemic inflammatory response and organ dysfunction, the mechanisms responsible for these alterations are not clear. Using a potent selective inducible nitric oxide (NO) synthase inhibitor, N-[3-(aminomethyl) benzyl]acetamidine (1400W), and a nonselective NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), we investigated whether inducible NO synthase plays any role in producing hepatic injury, inflammation, and changes of protein expression following trauma-hemorrhage. To investigate this, male Sprague-Dawley rats were subjected to midline laparotomy and hemorrhagic shock (mean blood pressure 35-40 mmHg for approximately 90 min) followed by fluid resuscitation. Animals were treated with either vehicle (DMSO) or 1400W (10 mg/kg body wt ip), or L-NAME (30 mg/kg iv), 30 min before resuscitation and killed 2 h after resuscitation. Trauma-hemorrhage/resuscitation induced a marked hypotension and increase in markers of hepatic injury (i.e., plasma alpha-glutathione S-transferase, tissue myeloperoxidase activity, and nitrotyrosine formation). Hepatic expression of iNOS, hypoxia-inducible factor-1alpha, ICAM-1, IL-6, TNF-alpha, and neutrophil chemoattractant (cytokine-induced neutrophil chemoattractant-1 and macrophage inflammatory protein-2) protein levels were also markedly increased following trauma-hemorrhage/resuscitation. Administration of the iNOS inhibitor 1400W significantly attenuated hypotension and expression of these mediators of hepatic injury induced by trauma-hemorrhage/resuscitation. However, administration of L-NAME could not attenuate hepatic dysfunction and tissue injury mediated by trauma-hemorrhage, although it improved mean blood pressure as did 1400W. These results indicate that increased expression of iNOS following trauma-hemorrhage plays an important role in the induction of hepatic damage under such conditions.

Flutamide protects against trauma-hemorrhage-induced liver injury via attenuation of the inflammatory response, oxidative stress, and apopotosis.

Although studies have shown that administration of testosterone receptor antagonist, flutamide, following trauma-hemorrhage, improves hepatic, cardiovascular, and immune functions, the precise cellular/molecular mechanisms responsible for producing these salutary effects remain largely unknown. To study this, male C3H/HeN mice were subjected to a midline laparotomy and hemorrhagic shock (35+/-5 mmHg for approximately 90 min), followed by resuscitation with Ringer lactate. Flutamide (25 mg/kg) or vehicle was administered subcutaneously at the onset of resuscitation, and animals were killed 2 h thereafter. Hepatic injury was assessed by plasma alpha-glutathione S-transferase concentration, liver myeloperoxidase activity, and nitrotyrosine formation. Hepatic malondialdehyde and 4-hydroxyalkenals (lipid peroxidation indicators), cellular DNA fragmentation, and the expression of inducible nitric oxide synthase and hypoxia-inducible factor-1alpha were also evaluated. Cytokines (TNF-alpha, IL-6) and chemokines (keratinocyte-derived chemokine and monocyte chemoattractant protein-1) levels were determined by cytometric bead array. The results indicate that flutamide administration after trauma-hemorrhage reduced liver injury, which was associated with decreased levels of alpha-glutathione S-transferase, myeloperoxidase activity, nitrotyrosine formation, lipid peroxidation, and cytokines/chemokines (systemic, liver tissue, and intracellular cytokines/chemokines). Cellular apoptosis, hepatocyte hypoxia-inducible factor-1alpha, and inducible nitric oxide synthase expression were also decreased under such conditions. Thus administration of flutamide following trauma-hemorrhage protects against liver injury via reduced inflammation, cellular oxidative stress, and apoptosis.

Systematic analysis of the salutary effect of estrogen on cardiac performance after trauma-hemorrhage.

Although 17beta-estradiol (estrogen) and estrogen receptor (ER) agonist administration after trauma-hemorrhage improves cardiac function, it remains unknown what the optimal estrogen or ER agonist dosage is to elicit this beneficial effect. To study this, the dose-dependent effects of estrogen, propylpyrazole triol (ER-alpha agonist), and diarylpropionitrile (DPN; ER-beta agonist) on heart performance (+dP/dt) were determined in sham rats and in experimental animals at the time of maximal bleedout (MBO) or at 2 h after trauma-hemorrhage. The results showed that estrogen and DPN induced dose-dependent increases in the maximal rate of left ventricular pressure increase (+dP/dt) in all groups, whereas propylpyrazole triol was ineffective at all doses. The maximal dose and the 50% effective dose of DPN were approximately 100-fold lower than those of estrogen. The half-life of estrogen in plasma was approximately 25 min in sham and MBO groups. A positive correlation between the estrogen-induced increase in +dP/dt and survival in MBO rats were observed. These results collectively suggest that the salutary effects of estrogen on cardiac performance are dose-dependent and mediated via ER-beta.

p38 MAPK-dependent eNOS upregulation is critical for 17beta-estradiol-mediated cardioprotection following trauma-hemorrhage.

Studies have shown that p38 MAPK and nitric oxide (NO), generated by endothelial NO synthase (eNOS), play key roles under physiological and pathophysiological conditions. Although administration of 17beta-estradiol (E2) protects cardiovascular injury from trauma-hemorrhage, the mechanism by which E2 produces those effects remains unknown. Our objective was to determine whether the E2-mediated activation of myocardial p38 MAPK and subsequent eNOS expression/phosphorylation would protect the heart following trauma-hemorrhage. To study this, male Sprague-Dawley rats underwent soft-tissue trauma (midline laparatomy) and hemorrhagic shock (mean blood pressure 35-40 mmHg for 90 min), followed by fluid resuscitation. Animals were pretreated with specific p38 MAPK inhibitor SB-203580 (SB; 2 mg/kg), and nonselective NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME; 30 mg/kg) 30 min before vehicle (cyclodextrin) or E2 (100 microg/kg) treatment, followed by resuscitation, and were killed 2 h thereafter. Cardiovascular performance and other parameters were measured. E2 administration following trauma-hemorrhage increased cardiac p38 MAPK activity, eNOS expression and phosphorylation at Ser(1177), and nitrate/nitrite levels in plasma and heart tissues; these were associated with normalized cardiac performance, which was reversed by SB administration. In addition, E2 also prevented trauma-hemorrhage-induced increase in cytokines (IL-6 and TNF-alpha), chemokines (macrophage inflammatory protein-2 and cytokine-induced neutrophil chemoattractant-1), and ICAM-1, which was reversed by l-NAME administration. Administration of E2 following trauma-hemorrhage attenuated cardiac tissue injury markers, myeloperoxidase activity, and nitrotyrosine level, which were reversed by treatment with SB and l-NAME. The salutary effects of E2 on cardiac functions and tissue protection following trauma-hemorrhage are mediated, in part, through activation of p38 MAPK and subsequent eNOS expression and phosphorylation.

Mechanism of estrogen-mediated intestinal protection following trauma-hemorrhage: p38 MAPK-dependent upregulation of HO-1.

p38 MAPK has been reported to regulate the inflammatory response in various cell types via extracellular stimuli. p38 MAPK activation also results in the induction of heme oxygenase (HO)-1, which exerts potent anti-inflammatory effects. Although studies have shown that 17beta-estradiol (E(2)) prevented organ dysfunction following trauma-hemorrhage, it remains unknown whether p38 MAPK/HO-1 plays any role in E(2)-mediated attenuation of intestinal injury under those conditions. To study this, male rats underwent trauma-hemorrhage (mean blood pressure approximately 40 mmHg for 90 min) followed by fluid resuscitation. At the onset of resuscitation, rats were treated with vehicle, E(2) (1 mg/kg body wt), the p38 MAPK inhibitor SB-203580 (2 mg/kg body wt) or E(2) plus SB-203580. Two hours thereafter, intestinal myeloperoxidase (MPO) activity and lactate, TNF-alpha, IL-6, ICAM-1, cytokine-induced neutrophil chemoattractant (CINC)-1, and macrophage inflammatory protein (MIP)-2 levels were measured. Intestinal p38 MAPK and HO-1 protein levels were also determined. Trauma-hemorrhage led to an increase in intestinal MPO activity and lactate, TNF-alpha, IL-6, ICAM-1, CINC-1, and MIP-2 levels. This was accompanied with a decrease in intestinal p38 MAPK activity and increase in HO-1 expression. Administration of E(2) normalized all the above parameters except HO-1, which was further increased following trauma-hemorrhage. Administration of SB-203580 with E(2) abolished the E(2)-mediated restoration of the above parameters as well as the increase in intestinal HO-1 expression following trauma-hemorrhage. These results suggest that the p38 MAPK/HO-1 pathway plays a critical role in mediating the salutary effects of E(2) on shock-induced intestinal injury.

Mechanism of estrogen-mediated improvement in cardiac function after trauma-hemorrhage: p38-dependent normalization of cardiac Akt phosphorylation and glycogen levels.

Both p38 mitogen-activated protein kinase (p38) activation and protein kinase B (Akt) activation have been reported to regulate glucose transport during myocardial I/R. An increase in cardiac glycogen levels prevents myocardial injury in the ischemic or stressed heart. Although studies have shown that 17"-estradiol (E2)-mediated improvement in cardiac function after trauma-hemorrhage is via p38 activation, it remains unknown whether p38/Akt plays any role in regulation of cardiac glycogen levels under these conditions. To study this, male rats underwent trauma-hemorrhage(mean blood pressure, x40 mmHg for 90 min) followed by fluid resuscitation. At the onset of resuscitation, rats (n=6 per group) were treated with vehicle, E2 (1 mg/kg body weight), the p38 inhibitor SB203580 (2 mg/kg body weight), or E2 and SB203580. Various parameters were measured at 2 h after resuscitation. One-way ANOVA and Tukey test were used for statistical analysis, and differences were considered significant at P<0.05. The depressed cardiac function after trauma-hemorrhage was restored by E2 treatment (P<0.05). Administration of E2 after trauma-hemorrhage also normalized the p38/Akt phosphorylation, which was associated with restoration of cardiac glycogen, glycogen synthase kinase 3"activation, glucose transporter 4 translocation, and increased hexokinase II levels (all parameters, P<0.05). Inhibition of the p38 pathway abolished the E2-induced restoration in above parameters after trauma-hemorrhage. These results suggest that p38-dependent normalization of cardiac Akt phosphorylation and glycogen levels plays an important role in E2-mediated restoration of cardiac function after trauma-hemorrhage.

Mechanism of estrogen-mediated attenuation of hepatic injury following trauma-hemorrhage: Akt-dependent HO-1 up-regulation.

Protein kinase B (Akt) is known to be involved in proinflammatory and chemotactic events in response to injury. Akt activation also leads to the induction of heme oxygenase (HO)-1. Up-regulation of HO-1 mediates potent, anti-inflammatory effects and attenuates organ injury. Although studies have shown that 17beta-estradiol (E2) prevents organ damage following trauma-hemorrhage, it remains unknown whether Akt/HO-1 plays any role in E2-mediated attenuation of hepatic injury following trauma-hemorrhage. To study this, male rats underwent trauma-hemorrhage (mean blood pressure, approximately 40 mmHg for 90 min), followed by fluid resuscitation. At the onset of resuscitation, rats were treated with vehicle, E2 (1 mg/kg body weight), E2 plus the PI-3K inhibitor (Wortmannin), or the estrogen receptor (ER) antagonist (ICI 182,780). At 2 h after sham operation or trauma-hemorrhage, plasma alpha-GST and hepatic tissue myeloperoxidase (MPO) activity, IL-6, TNF-alpha, ICAM-1, cytokine-induced neutrophil chemoattractant-1, and MIP-2 levels were measured. Hepatic Akt and HO-1 protein levels were also determined. Trauma-hemorrhage increased hepatic injury markers (alpha-GST and MPO activity), cytokines, ICAM-1, and chemokine levels. These parameters were markedly improved in the E2-treated rats following trauma-hemorrhage. E2 treatment also increased hepatic Akt activation and HO-1 expression compared with vehicle-treated, trauma-hemorrhage rats, which were abolished by coadministration of Wortmannin or ICI 182,780. These results suggest that the salutary effects of E2 on hepatic injury following trauma-hemorrhage are in part mediated via an ER-related, Akt-dependent up-regulation of HO-1.

Lung, spleen, and kidney are the major places for inducible nitric oxide synthase expression in endotoxic shock: role of p38 mitogen-activated protein kinase in signal transduction of inducible nitric oxide synthase expression.

Bacterial lipopolysaccharide (LPS) is known to induce endotoxic shock with inducible nitric oxide (NO) synthase (iNOS) expression and NO production. However, the major place for NO production in shock remains unclear. Although there is some literature about p38 mitogen-activated protein kinase (MAPK) in regulating LPS-induced iNOS expression, the results are contradictory. To interpret the precise cell mechanism and the role of p38 MAPK in the expression of iNOS during endotoxic shock, we carried out the following investigations. A severe endotoxic shock model was reproduced in mice 6 h after LPS injection. The plasma NO level was increased in a dose- and time-dependent manner after LPS stimulation and was suppressed by administration of SB203580 [4-(4-fluorophenyl)-2-4-methylsulfonylphenyl-5-(4-pyridyl) imidazole], a highly specific inhibitor of p38 MAPK. The iNOS expression was increased in many organs, including heart, liver, spleen, lung, gut, and kidney in endotoxic shock. Among them, the highest expression of iNOS mRNA and protein was in the lung, moderate expression was in the spleen and kidney, and the lowest expression was in the heart, gut, and liver. The level of expression in lung was 5.5 times that of iNOS mRNA and was 3.1 times that of iNOS protein than in heart, and 1.6 and 1.8 times that of iNOS mRNA and 1.7 and 1.4 times that of iNOS protein than in spleen and kidney, respectively. The p38 MAPK activity increased after LPS injection, and SB203580 markedly reduced LPS-induced expressions of iNOS protein and mRNA in the lung. The results indicates that lung, spleen, and kidney are the major places for iNOS expression in endotoxic shock and are important therapeutic target organs for attenuating NO production in shock treatment.

Regulation of inducible nitricoxide synthase gene transcription by p38 mitogen-activated protein kinase in human embryonic kidney 293 cells.

OBJECTIVE: To study the transcriptional regulation of inducible nitric oxide synthase (iNOS) gene by p38 mitogen-activated protein kinase (MAPK). METHODS: With human embryonic kidney (HEK) 293 cells as the target and the assistance of lipofectamine-mediated co-transfection techniques and luciferase reporter gene systems, FLAG-tagged p38 isoforms (namely FLAG-p38 alpha, FLAG-p38 beta;, FLAG-p38 gamma and FLAG-p38 phi;) in pcDNA3, pcDNA3, piNOS-Luc and pCMV-beta; were transfected into HEK 293 cells, and the relative activity of luciferase was subsequently tested. RESULTS: Highest luciferase activity occurred only in p38 alpha group compared with the other three isoform groups under no stimulation. Under the stimulation by lipopolysaccharide (LPS), the luciferase activity of each group was obviously increased and the highest activity occurred in p38 beta group. CONCLUSION: LPS can induce transcription and activation of iNOS gene, and p38 MAPK is involved in the transcription regulation of iNOS gene in HEK 293 cells.

The mechanism of Polydatin in shock treatment.

Polydatin is extracted from a traditional Chinese herbal medicine, Polygonum cuspidatum, and has a special effect in shock treatment. The aim of this study is to explain the cellular and molecular basis of Polydatin in shock treatment. The fluorescent probe techniques, patch clamp method, and cellular flow chamber were used to test intracellular variables of vascular smooth muscle cells (VSMC), myocardial cells (MC), endothelial cells (EC), and white blood cell (WBC). It was shown that Polydatin could inhibit ICAM-1 expression in EC stimulated by lipopolysaccharide (LPS), attenuate WBC-EC adhesion, increase [Ca2+]i in MC with enhancement of MC contraction extent, activate KATP channels of VSMC, and decrease pHi value and [Ca2+]i of VSMC in shock. The study suggests that Polydatin has multiple effects on VSMC, MC, WBC and EC, which are related to the enhancement of heart function and improvement of microcirculatory perfusion in shock.

[Effect of complex dribbing-pill of xue shuan tong on thrombus formation and microcirculation in rat].

OBJECTIVE: To investigate the effect of Chinese traditional medicine complex dribbing-pill of Xue Shuan Tong on thrombus formation in vivo and thrombolysis in vitro of rats. METHODS: Thrombus and thrombolysis were evaluated by carotid artery-jugular vein circuit in vivo and constant temperature natural lysis in vitro respectively. RESULTS: Complex dribbing-pill of Xue Shuan Tong could significantly inhibit thrombus formation in vivo. Coagulated blood could be apparently dissolved by complex dribbing-pill of Xue Shuan Tong. CONCLUSION: Complex dribbing-pill of Xue Shuan Tong could significantly inhibit the thrombus and increase thrombolysis.

Role of p38 mitogen-activated protein kinase in lipopolysaccharide-induced expression of inducible nitric oxide synthase in human endothelial cells.

OBJECTIVE: To understand the role of p38 mitogen-activated protein kinase (p38MAPK) in the expression of inducible nitric oxide synthase (iNOS) and NO production in human endothelial cells under the stimulation by lipopolysaccharide (LPS). METHODS: NO level in the supernatant of the cell culture media was measured with Griess method, and iNOS protein and mRNA expressions by the cells were detected with immunofluorescence analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) respectively. Immunoprecipitation assay was employed to examine p38 MAPK activity. RESULTS: It was shown that in comparison with the basal level of iNOS expression in cultured endothelial cells line ECV304, iNOS mRNA and protein expressions were significantly increased in the cells after LPS stimulation. In response to LPS treatment, obvious enhancement of p38 MAPK activity in ECV304 took place after the stimulation, with the peak level occurring at 15 min that maintained for approximately 45 min before gradual decline. When treated with SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl) imidazole], a highly specific inhibitor of p38 MAPK, significant inhibition of LPS-induced iNOS protein and mRNA expressions was observed. CONCLUSIONS: p38 MAPK plays an important role in iNOS expression and NO production in ECV304 cells, and, inhibition of the signal transduction pathway may consequently be an effective approach to reduce the production of iNOS and other cytokines for the treatment of septic shock.

Role of p38 MAPK in ICAM-1 expression of vascular endothelial cells induced by lipopolysaccharide.

Lipopolysaccharide (LPS) stimulation of endothelial cells induces the expression of intercellular adhesion molecule-1 (ICAM-1), a critical adhesion molecule involved in the adhesive interaction between leukocytes and endothelial cells in shock and inflammation. Although there is little literature about role of p38 mitogen-activated protein kinase (MAPK) in ICAM-1 protein expression of LPS-induced endothelial cells, it is still not defined whether gene transcription is regulated by p38 MAPK in ICAM-1 expression of LPS-induced endothelial cells. In this study, the potential role of p38 MAPK in ICAM-1 expression of LPS-induced endothelial cells was studied in vitro and in vivo. In vitro studies, the results showed that compared with basic expression of ICAM-1 protein on cultured human umbilical vein endothelial cells (HUVECs), the ICAM-1 expression was increased initially at 2 h after LPS stimulation, reached peak value at 24 h, and descended at 36 h obviously. A dose-dependent relationship existed between LPS concentration and ICAM-1 expression. The abundance of ICAM-1 mRNA in cytoplasma of endothelial cells was upregulated significantly by LPS stimulation at 2 h and was maintained at a high level from 4 to 36 h. The upregulation of ICAM-1 protein and mRNA expression of LPS-induced HUVECs was markedly inhibited by SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole], a highly specific inhibitor of p38 MAPK. Activity of p38 MAPK in HUVECs was increased at 15 min after LPS stimulation and reached the maximum at 60 min, then descended significantly. Activity of p38 MAPK was inhibited significantly by SB203580 in vitro. In vivo studies, administration of SB203580 (12.5 or 25 mg/kg, per ora) markedly reduced LPS-induced expression of ICAM-1 protein and mRNA of lung tissues of male BALB/c mice. These data highlight that the upregulation of ICAM-1 expression of LPS-induced endothelial cells in vitro and in vivo is mediated by p38 MAPK pathway at the level of gene transcription. The ICAM-1 expression of LPS-induced endothelial cells is characteristic of time dependence and dose dependence, and tolerates to chronic LPS stimulation. Inhibition of the p38 MAPK signal pathway may be used as an approach to attenuate ICAM-1 production in the treatment of septic shock.

[Expression of intercellular adhesion molecule-1 in different organs of the mice with endotoxic shock induced by lipopolysaccharide].

To investigate and compare the expression of intercellular adhesion molecule-1 (ICAM-1) in different organs of the mice with endotoxic shock induced by lipopolysaccharide (LPS), protein and mRNA of ICAM-1 were measured by Western blotting and RT-PCR respectively in different organs of BALB/c mice administered intraperitoneally with 5 mg/kg LPS. The results showed that the constitutive expression of ICAM-1 protein and mRNA was the greatest in the lungs, followed by the spleen, kidney and intestine. After LPS stimulation, the upregulation of ICAM-1 was still greatest in the lungs, followed by the liver, spleen, heart, kidney and intestine. Compared with the normal mice, the expression of ICAM-1 protein in endotoxic shocked mice increased by 4.5-fold in the lungs, 3.0-fold in the kidney, 1.5-fold in the spleen; the expression in the liver and heart was negative under normal condition and changed into positive during endotoxic shock; but ICAM-1 expression in the intestine did not change significantly. The expression of ICAM-1 mRNA also increased consistently. These data highlight that LPS can up-regulate ICAM-1 protein and mRNA expression in different tissues of the mice with endotoxic shock. The difference in ICAM-1 expression among the organs may lead to different sensitivity of organ damage in endotoxic shock. This suggests that inhibition of ICAM-1 expression may be a useful principle for prevention and treatment of endotoxic shock.