Inhibition of p38 mitogen-activated protein kinase blocks activation of rat pancreatic stellate cells

Activated pancreatic stellate cells (PSCs) have recently been implicated in the pathogenesis of pancreatic fibrosis and inflammation. However, the signal transduction pathways in PSCs remain largely unknown. We examined the role of p38 mitogen-activated protein (MAP) kinase in the activation of PSCs. PSCs were isolated from rat pancreas tissue and used in their culture-activated, myofibroblast-like phenotype. Activation of p38 MAP kinase was determined by Western blotting using anti-phosphospecific antibody. The effects of two p38 MAP kinase inhibitors, 4-(4-flurophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole (SB203580) and 4-(4-flurophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole (SB202190), on the parameters of PSC activation, including proliferation, expression of alpha-smooth muscle actin, alpha1(I) procollagen, and prolyl 4-hydroxylase (alpha) genes, and monocyte chemoattractant protein-1 production were evaluated. Interleukin-1beta and platelet-derived growth factor-BB activated p38 MAP kinase. Platelet-derived growth factor-induced PSC proliferation was inhibited by SB203580 and SB202190. These reagents decreased alpha-smooth muscle actin protein expression, and alpha1(I) procollagen and prolyl 4-hydroxylase (alpha) mRNA levels. Treatment with these p38 MAP kinase inhibitors also resulted in inhibition of monocyte chemoattractant protein-1 expression. In addition, SB203580 inhibited spontaneous activation of freshly isolated PSCs in culture on plastic. Thus, inhibition of p38 MAP kinase modulated profibrogenic and proinflammatory actions in PSCs, implying a potential application of p38 MAP kinase inhibitors for the treatment of pancreatic fibrosis and inflammation.     

Role of p38 mitogen-activated protein kinase in lung injury after burn trauma

This study was undertaken to evaluate the effect of SB203580, a specific p38 mitogen-activated protein (MAP) kinase inhibitor, on burn-induced lung injury as well as the release of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta in rats to characterize the role of p38 MAP kinase in lung injury after burn trauma. Sprague-Dawley rats were divided into three groups: 1) sham group, or rats who underwent sham burn; 2) control group, or rats given third-degree burns over 30% total body surface area (TBSA) and lactated Ringer solution for resuscitation; and 3) SB203580 group, or rats given burn injury and lactated Ringers solution with SB203580 inside for resuscitation. Pulmonary injury was assessed at 24 h by pulmonary capillary permeability determined with fluorescein isothiocyanate-labeled albumin and lung histologic analysis. TNF-alpha and IL-1beta protein in bronchoalveolar lavage fluid and serum were measured by enzyme-linked immunosorbent assay and p38 MAP kinase was activity determined in lung by Western blot analysis. These studies showed that significant activation of p38 MAP kinase at 24 h postburn compared with control. Burn trauma resulted in increased pulmonary capillary leakage permeability, elevated levels of TNF-alpha and IL-1beta in bronchoalveolar lavage fluid and serum, and worsened histologic condition. SB203580 inhibited the activation of p38 MAP kinase, reduced the levels of TNF-alpha and IL-1beta, and prevented burn-mediated lung injury. These data suggest that p38 MAP kinase activation is one important aspect of the signaling event that may mediate the release of TNF-alpha and IL-1beta and contributes to burn-induced lung injury.     

SB 203580, an inhibitor of p38 mitogen-activated protein kinase, enhances constitutive apoptosis of cytokine-deprived human eosinophils.

The role of p38 mitogen-activated protein (MAP) kinase, and extracellular-regulated protein kinase -1 and -2 in regulating constitutive apoptosis and interleukin (IL)-5-induced survival of human eosinophils have been investigated. Two populations of donors were identified whose eosinophils, in the absence of exogenous cytokines, underwent apoptosis at different rates. Eosinophils were thus arbitrarily classified as either "fast"- or "slow"-dying cells, where greater or less than 15% of the cells were apoptotic at 2 days, respectively. The selective p38 MAP kinase inhibitor, SB 203580, increased constitutive eosinophil apoptosis in both populations (EC(50) approximately 2 microM) as evinced from morphological analysis, flow cytometry, and DNA laddering. The ability of SB 203580 to kill eosinophils was not due to nonspecific toxicity or through the inhibition of prostanoid or leukotriene production. Exposure of eosinophils to IL-5, at a concentration (10 pM) that enhanced survival maximally, abolished SB 203580-induced apoptosis. In contrast PD 098059, which selectively blocks MAP kinase kinase (MEK) 1, did not affect apoptosis of fast- or slow-dying eosinophils, or the enhanced survival of cells effected by IL-5. Collectively, these results suggest that: 1) the basal activity of p38 MAP kinase may regulate the survival of cytokine-deprived eosinophils through inhibition of apoptosis, 2) the enhancement of eosinophil survival effected by IL-5 is mediated by a mechanism(s) divorced from the activation of p38 MAP kinase, and 3) neither spontaneous eosinophil apoptosis nor their enhanced survival by IL-5 involves the activation of MEK-1.     

Angiotensin converting enzyme inhibitor attenuates oxidative stress-induced endothelial cell apoptosis via p38 MAP kinase inhibition

BACKGROUND: The effects of angiotensin converting enzyme (ACE) inhibitors on oxidative stress-induced apoptosis of endothelial cells and the intracellular signaling were investigated. METHODS: Cultured endothelial cells derived from a bovine carotid artery were treated with H2O2 or TNF-alpha to induce apoptosis. Apoptosis was evaluated by DNA fragmentation and cell viability, p38 MAP kinase activity by Western blotting, and oxidative stress by formation of 8-isoprostane. The effects of ACE inhibitors were examined by adding them into the medium throughout the experiments. RESULTS: Apoptosis was attenuated by ACE inhibitors, temocapril and captopril, in a dose-dependent manner (1-100 micromol/l). H2O2 (0.2 mmol/l for 1.5 h) or TNF-alpha (10 ng/ml for 72 h) treatment stimulated the activities of p38 MAP kinase. Temocapril and captopril decreased the activity of p38 MAP kinase as well as 8-isoprostane formation induced by H2O2. A p38 MAP kinase inhibitor, SB203580, partially inhibited the effect of temocapril on apoptosis. CONCLUSIONS: These results suggest that ACE inhibitors protect endothelial cells from oxidative stress-induced apoptosis, and that p38 MAP kinase plays a critical role in the process.     

Cocaine induces apoptosis in fetal rat myocardial cells through the p38 mitogen-activated protein kinase and mitochondrial/cytochrome c pathways

Cocaine induces apoptosis in fetal rat myocardial cells (FRMCs). However, the mechanisms are not clear. The present study examined the role of p38 mitogen-activated protein kinase (MAPK) and cytochrome c release in the cocaine-induced apoptosis in primary culture of FRMCs prepared from the fetal heart of gestational age of 21 days. Cocaine induced time-dependent, concurrent increases in cytochrome c release and activities of caspase-9 and caspase-3, which preceded apoptosis. Caspase-8 was not activated. In accordance, cyclosporin A and the inhibitors of caspase-9 and caspase-3 inhibited cocaine-induced caspase activation and apoptosis. Cocaine stimulated a transient increase in the p38 MAPK activity at a time point of 15 min but reduced the extracellular signal-regulated kinase (ERK) activity at 5 and 15 min in FRMCs. The p38alpha MAPK inhibitor SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole] inhibited cocaine-induced activation of caspases and apoptosis. In contrast, the p38beta MAPK and mitogen-activated protein kinase kinase/ERK inhibitors SB 202190 [4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)-1H-imidazole] and PD98059 (2'-amino-3'-methoxyflavone), respectively, increased apoptosis in the absence of cocaine and potentiated cocaine-induced apoptosis. Consistent with its inhibition of apoptosis, SB203580 inhibited cocaine-induced cytochrome c release and activation of caspase-9 and caspase-3. In addition, cocaine induced a decrease in Bcl-2 protein levels, with no effect on Bax levels. The cocaine-mediated reduction of Bcl-2 levels was not affected with SB203580 and the caspase inhibitors. The results suggest that in FRMCs, p38alpha MAPK plays an important role in the cocaine-induced apoptosis by promoting cytochrome c release, downstream or independent of Bcl-2 protein-mediated regulation. In contrast, p38beta MAPK and ERK protect fetal myocardial cells against apoptosis.     

周期性张应力诱导成纤维细胞凋亡中p38MAPK信号通路的作用

背景：当牙齿受异常咬合力时会导致牙体吸收、牙周组织的大量破坏。目的：研究牙周膜成纤维细胞在受到周期性张应力刺激后是否发生凋亡及p38MAPK信号通路是否参与该凋亡过程。方法：取4～7代成纤维细胞,同步化后随机分为对照组、加力组和SB203580组。加力组和SB203580组细胞加载力值为12%表面应变率,加力频率为6个循环/min,即5s拉伸,5s松弛。SB203580组细胞在加力前1h加入终浓度为20mmol/L的p38MAPK抑制剂SB203580。分别在加力6,12,24h,取各组细胞,流式细胞仪检测细胞凋亡,RT-PCR检测细胞凋亡基因baxmRNA的表达。结果与结论：与对照组比较,加力后成纤维细胞凋亡率及baxmRNA表达增加（P〈0.05）,且随着加力时间的延长而增强,12h达高峰,之后逐渐下降。与加力组比较,SB203580组对应时间点细胞凋亡减少（P〈0.05）,baxmRNA表达降低。说明细胞受到力学刺激会发生凋亡,而丝裂原活化蛋白激酶p38MAPK信号通路参与了该凋亡过程。     

周期性张应力诱导成纤维细胞凋亡中p38MAPK信号通路的作用

背景:当牙齿受异常咬合力时会导致牙体吸收、牙周组织的大量破坏.目的:研究牙周膜成纤维细胞在受到周期性张应力刺激后是否发生凋亡及p38MAPK信号通路是否参与该凋亡过程.方法:取4～7代成纤维细胞,同步化后随机分为对照组、加力组和SB203580组.加力组和SB203580组细胞加载力值为12%表面应变率,加力频率为6个循环/min,即5 s拉伸,5 s松弛.SB203580组细胞在加力前1 h加入终浓度为20 mmol/L的p38MAPK抑制剂SB203580.分别在加力6,12,24 h,取各组细胞,流式细胞仪检测细胞凋亡,RT-PCR检测细胞凋亡基因bax mRNA的表达.结果与结论:与对照组比较,加力后成纤维细胞凋亡率及bax mRNA表达增加(P < 0.05),且随着加力时间的延长而增强,12 h达高峰,之后逐渐下降.与加力组比较,SB203580组对应时间点细胞凋亡减少(P < 0.05),bax mRNA表达降低.说明细胞受到力学刺激会发生凋亡,而丝裂原活化蛋白激酶p38MAPK信号通路参与了该凋亡过程.     

Selective inhibitor of p38 mitogen-activated protein kinase inhibits lipopolysaccharide-induced interleukin-8 expression in human pulmonary vascular endothelial cells

Adult respiratory distress syndrome (ARDS) characterized by permeability edema is observed in severe insults such as bacteremia sepsis. Interleukin (IL)-8, which chemoattracts and activates neutrophils, has been suggested to play an important role in the production of ARDS. Therefore, the inhibition of IL-8 production is an important strategy for the treatment of ARDS. Recent studies have revealed the role of p38 mitogen-activated protein (MAP) kinase in cytokine expression and the inhibition by a selective inhibitor of p38 MAP kinase activity of cytokine expression in a variety of cell types. However, little is known about the role of p38 MAP kinase in lipopolysaccharide (LPS)-induced IL-8 expression in pulmonary vascular endothelial cells and the effect of a selective p38 MAP kinase inhibitor on it. In the present study, we therefore attempted to clarify these issues. The results showed that LPS induced p38 MAP kinase phosphorylation and activity, and SB 203580 as a selective inhibitor of p38 MAP kinase activity inhibited p38 MAP kinase activity and IL-8 expression in LPS-stimulated pulmonary vascular endothelial cells. These results indicate that p38 MAP kinase regulates LPS-induced IL-8 expression in pulmonary vascular endothelial cells. Although it is currently not known whether SB 203580 is capable of producing beneficial effects on ARDS, a strategy of inhibiting p38 MAP kinase activity by a selective p38 MAP kinase inhibitor may apply to the therapy for ARDS.     

Cytosolic phospholipase A2 activation by the p38 kinase inhibitor SB203580 in rabbit aortic smooth muscle cells.

SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole] is widely used as a specific inhibitor of p38 mitogen-activated protein kinase (MAPK). Here we report that SB203580, which blocked p38 kinase activation elicited by anisomycin, increased the phosphorylation and activity of cytosolic phospholipase A2 (cPLA2) and arachidonic acid (AA) release in quiescent vascular smooth muscle cells from rabbit aortae. SB203580 also increased the activity of calcium (Ca2+)/camodulin-dependent kinase II (CaMKII) and ERK1/2 MAPK. The increase in CaMKII activity and cPLA2 phosphorylation caused by SB203580 was attenuated by CaMKII inhibitor KN-93, indicating involvement of CaMKII in cPLA2 phosphorylation by this compound. Since KN-93 also inhibited SB203580-induced ERK1/2 activation, it appears that ERK1/2 activation is also mediated by CaMKII. SB203580-induced cPLA2 phosphorylation was inhibited by depletion of Ca2+ from the medium, by the voltage-operated Ca2+ channel blocker nifedipine, and by the calmodulin inhibitor W-7. cPLA2 translocation from cytoplasm to the nuclear envelope caused by SB203580 was also inhibited in the absence of extracellular Ca2+. Other p38 kinase inhibitors, SB202190 and PD169316, failed to alter CaMKII, ERK1/2, and cPLA2 activity or cPLA2 translocation to the nuclear envelope. These data suggest that SB203580 not only inhibits p38 kinase activity but also increases Ca2+ influx through voltage-sensitive Ca2+ channels, which promotes cPLA2 translocation to the nuclear envelope, and by interacting with calmodulin, activates CaMKII and cPLA2 and releases AA.     

Activation of mitogen-activated protein kinases during granulocyte apoptosis in patients with severe sepsis

Reduction of neutrophil apoptosis represents a major cause for granulocytosis and increases the destructive potential of theses cells during systemic inflammatory response syndrome (SIRS) and sepsis. In this light, the role of protein kinases for the regulation of altered neutrophil apoptosis under infectious conditions was investigated. Neutrophils, obtained from patients with severe sepsis (n = 18), were incubated ex vivowith either LPS (1 microg/mL) or interferon-gamma (IFN-gamma; 10 ng/mL) for 16 h. Apoptosis was determined by propidium iodine (PI) staining of DNA fragments and was compared with the rate of spontaneous apoptosis. Tyrosine kinases were inhibited by herbimycin (1 microM), the mitogen-activated protein (MAP) kinase ERK was inhibited with PD98059 (50 microM), and p38 MAP kinase was inhibited with SB203580 (5 microM). Herbimycin reconstituted LPS-reduced apoptosis in neutrophils from controls (39.9 +/- 3.8%) and patients (20.8 +/- 2.8%) to levels seen in spontaneous apoptosis (70.9 +/- 2.8% and 40.7 +/- 3.7%, respectively). Inhibition of the ERK kinase yielded similar results, whereas SB203580 had no effect on LPS-reduced apoptosis. However, inhibition of p38 partially reconstituted IFN-gamma-reduced apoptosis (51.3 +/- 7.7% and 25.6 +/- 5.8%) and increased spontaneous apoptosis (82.4 +/- 3.3% and 42.0 +/- 5.8%) in controls and patients, respectively. Western blot analysis revealed phosphorylation of both MAP kinases by LPS, but not by IFN-gamma. Inhibition of MAP kinases did not augment neutrophil apoptosis in patients to the level seen in controls, indicating that other mechanisms must be involved in the regulation of neutrophil apoptosis. Although the ERK kinase regulates LPS-induced reduction of apoptosis, the p38 MAP kinase might be involved in IFN-gamma signaling and the feedback regulation of neutrophil apoptosis.     

Hyperbaric oxygen activates discoidin domain receptor 2 via tumour necrosis factor-alpha and the p38 MAPK pathway to increase vascular smooth muscle cell migration through matrix metalloproteinase 2

DDR2 (discoidin domain receptor 2) regulates collagen turnover mediated by SMCs (smooth muscle cells) in atherosclerosis. HBO (hyperbaric oxygen) has been used in medical practice; however, the molecular mechanism of the beneficial effects of HBO is poorly understood. Furthermore, the effect of HBO on DDR2 has not been reported previously. In the present study, we investigated the cellular and molecular mechanisms of DDR2 regulation by HBO in VSMCs (vascular SMCs). Cells were exposed to 2.5 ATA (atmosphere absolute) of oxygen in a hyperbaric chamber. DDR2 protein (3.63-fold) and mRNA (2.34-fold) expression were significantly increased after exposure to 2.5 ATA HBO for 1 h. Addition of SB203580 and p38 MAPK (mitogen-activated protein kinase) siRNA (small interfering RNA) 30 min before HBO inhibited the induction of DDR2 protein. HBO also significantly increased DNA-protein binding activity of Myc/Max. Addition of SB203580 and an anti-TNF-alpha (tumour necrosis factor-alpha) monoclonal antibody 30 min before HBO abolished the DNA-protein binding activity induced by HBO. HBO significantly increased the secretion of TNF-alpha from cultured VSMCs. Exogenous addition of TNF-alpha significantly increased DDR2 protein expression, whereas anti-TNF-alpha and anti-(TNF-alpha receptor) antibodies blocked the induction of DDR2 protein expression. HBO significantly increased VSMC migration and proliferation, whereas DDR2 siRNA inhibited the migration induced by HBO. HBO increased activated MMP2 (matrix metalloproteinase 2) protein expression, and DDR2 siRNA abolished the induction of activated MMP2 expression induced by HBO. In conclusion, HBO activates DDR2 expression in cultured rat VSMCs. HBO-induced DDR2 is mediated by TNF-alpha and at least in part through the p38 MAPK and Myc pathways.     

Drugs designed to inhibit human p38 mitogen-activated protein kinase activation treat Toxoplasma gondii and Encephalitozoon cuniculi infection

We recently showed that the pyridinylimidazoles SB203580 and SB202190, drugs designed to block human p38 mitogen-activated protein kinase (MAPK) activation, also inhibited replication of the medically important intracellular parasite Toxoplasma gondii in cultured human fibroblasts through a direct effect on the parasite. We now show that additional pyridinylimidazole and imidazopyrimidine p38 MAPK inhibitors inhibit intracellular T. gondii replication in vitro and protect mice against fatal T. gondii infection. Mice surviving infection following treatment with p38 MAPK inhibitors were resistant to subsequent T. gondii challenge, demonstrating induction of protective immunity. Thus, drugs originally developed to block human p38 MAPK activation are useful for treating T. gondii infection without inducing significant immunosuppression. MAPK inhibitors combined with either of the approved anti-Toxoplasma drugs sulfadiazine and pyrimethamine resulted in improved survival among mice challenged with a fatal T. gondii inoculum. A MAPK inhibitor also treated mice infected with the Microsporidium parasite Encephalitozoon cuniculi, suggesting that MAPK inhibitors represent a novel class of agents that may have a broad spectrum of antiparasitic activity. Preliminary studies implicate a T. gondii MAPK homologue as the target of drug action, suggesting possibilities for more-selective agents.     

LPS-induced vascular endothelial growth factor expression in rat lung pericytes

Vascular endothelial growth factor (VEGF) is a potent angiogenic and vascular permeability factor. Recent studies have shown that the VEGF levels increase in several cell types, for example, macrophages and smooth muscle cells after LPS stimulation, suggesting that it is important in the initiation and development of sepsis. In particular, LPS-regulated contractility in lung pericytes may play an important role in mediating pulmonary microvascular fluid hemodynamics during sepsis. This study investigated the production of VEGF by rat lung pericytes in response to LPS. LPS was found to enhance VEGF mRNA expression in a concentration-dependent manner peaking 2 h after stimulation in pericytes. Vascular endothelial growth factor protein levels in conditioned medium and in cell lysate also increased on increasing LPS and peaked after 24 to 48 h. LPS also significantly augmented iNOS expression in lung pericytes within 6 h. However, iNOS mRNA induction occurred later than LPS-induced VEGF mRNA increases. Interestingly, attempted inhibition with nuclear factor-kappaB or tyrosine kinase did not suppress LPS-induced augmented VEGF mRNA expression in lung pericytes, although both inhibitors markedly inhibited LPS-induced iNOS mRNA expression. SB203580, a p38 MAP kinase inhibitor, repressed LPS-induced VEGF mRNA expression. Furthermore, LPS stimulated a rapid and sustained phosphorylation of p38 MAP kinase. These results show that pericytes produce VEGF in response to LPS stimulation, and that this may be partly mediated by the p38 MAP kinase pathway. More research should be done to establish the regulation of capillary hemodynamics and identify mechanisms of their regulation.     

Cytokine-induced epithelial permeability changes are regulated by the activation of the p38 mitogen-activated protein kinase pathway in cultured Caco-2 cells

Increased intestinal/epithelial permeability in sepsis and endotoxemia has been noted to be induced by proinflammatory cytokines such as interferon-gamma, TNF-alpha, and IL-1beta. The p38 mitogen-activated protein kinase (MAPK) signaling pathway plays an important role in regulating the inflammatory response induced by these cytokines. We tested the hypothesis that epithelial permeability changes are regulated through the p38 MAPK signaling pathway. Caco-2 cells were cultured for 21 days and then stimulated with a cytokine mixture (CytoMix: TNF-alpha, interferon-gamma, and IL-1beta). Epithelial barrier function was evaluated by measuring permeability in an Ussing chamber. CytoMix-induced changes of MAPKs (p38, c-Jun amino-terminal kinase, and extracellular-regulated kinase), NO production, and inflammatory responses (IL-6 and IL-8 levels) were also assessed. The signaling pathways were further studied by pretreating cells with SB203580, a specific p38 MAPK inhibitor. CytoMix increased permeability at 24 and 48 h but not at 4 h. This was associated with increased IL-6 and IL-8 production, as well as increases in phosphorylation of all three MAPKs. Treatment with SB203580 completely blocked p38 activity with transient inhibition of p38 phosphorylation. SB203580 also prevented the CytoMix-induced permeability increase and reduced NO, IL-6, and IL-8 levels. The results suggest that p38 MAPK plays an important role in regulating epithelial barrier function during inflammation.     

Kinetics of mitogen-activated protein kinase family in lipopolysaccharide-stimulated mouse Kupffer cells and their role in cytokine production

This study was designed to systemically investigate the kinetics of extracellular signal-regulated kinase (ERK) 1/2, p54 c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinases (MAPKs) in lipopolysaccharide (LPS)-stimulated Kupffer cells (KC) simultaneously at the levels of protein expression, phosphorylation, and kinase activity, respectively, and their role in mediating pro- and anti-inflammatory cytokines. The protein expression, phosphorylation, and activities of these MAPKs in LPS-stimulated primary mouse KCs were determined with SDS-PAGE and western blotting using nonphosphorylated or phosphospecific antibodies or their corresponding substrates. The levels of TNF-alpha and IL-10 in culture supernatants were measured with ELISA kits. The results revealed that LPS stimulation, although not up- or downregulating the protein expression of ERK1/2, p54JNK, and p38 MAPKs in KCs, could induce rapid and significant activation of these kinases, with parallel profiles of changes in both phosphorylation and kinase activities. Although ERK1/2, p54JNK, and p38 kinases in LPS-stimulated KCs have similar kinetics of activation, the activation of ERK1/2 and p38 kinases was the most prominent. Inhibition of p38 MAPK with SB203580 inhibited the production of TNF-alpha and IL-10 by LPS-stimulated KCs, whereas blockade of ERK1/2 with PD98059 could reduce TNF-alpha production, but did not affect IL-10 production. Furthermore, PD98059 and SB203580 had an additive effect on TNF-alpha production, but PD98059 did not augment the SB203580-induced inhibition of IL-10 production. These data indicate that LPS stimulation, although not inducing any change in protein expression, results in rapid activation of ERK1/2, p54JNK, and p38 kinases in KCs, and that they may have different importance in the regulation of pro- and anti-inflammatory responses by LPS-stimulated KCs.     

Roflumilast inhibits lipopolysaccharide-induced inflammatory mediators via suppression of nuclear factor-kappaB, p38 mitogen-activated protein kinase, and c-Jun NH2-terminal kinase activation

Roflumilast, a potent and selective phosphodiesterase 4 (PDE4) inhibitor, has been demonstrated to be an effective anti-inflammatory agent in airway inflammatory diseases. In the present study, we investigated the mechanism of anti-inflammatory effects of roflumilast in murine macrophage cell line RAW264.7 cells. Roflumilast inhibited NO, tumor necrosis factor (TNF)-alpha, and interleukin (IL)-1beta production via suppression of their gene expressions in lipopolysaccharide (LPS)-stimulated macrophages. To elucidate the mechanism by which roflumilast inhibits the production of inflammatory mediators, we examined the effect of roflumilast on the activation of nuclear factor-kappaB (NF-kappaB) in these cells. Roflumilast inhibited the DNA binding activity of NF-kappaB by preventing inhibitor kappaBalpha phosphorylation and degradation. The phosphorylation of mitogen-activated protein (MAP) kinases, including stress-activated protein kinase/c-Jun NH2-terminal kinase (JNK) and p38 MAP kinase, was also markedly inhibited by roflumilast. Similar to the effects of roflumilast, treatment of either SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole] or SP600125 [anthra(1,9-cd)pyrazol-6(2H)-one 1,9-pyrazoloanthrone], specific inhibitors of p38 MAP kinase and JNK, respectively, suppressed NO, TNF-alpha, and IL-1beta production. Consistent with in vitro results, administration of roflumilast recovered the survival rate of LPS-treated mice, with concurrent suppression of plasma levels of nitrite/nitrate, TNF-alpha, and IL-1beta. These results suggest that the inhibitory activity of roflumilast on the production of inflammatory mediators seems to be mediated via inhibition of NF-kappaB, p38 MAP kinase, and JNK activation in macrophages.     

脂多糖诱导血管平滑肌细胞分泌白细胞介素-6及p38丝裂素活化蛋白激酶的调控作用

目的 探讨p38丝裂素活化蛋白激酶(MAPK)信号转导通路在脂多糖(LPS)作用下血管平滑肌细胞(VSMC)分泌白细胞介素-6(IL-6)中的调节作用.方法 将体外培养的大鼠胸主动脉VSMC分为LPS刺激组、p38MAPK抑制剂SB203580干预组、SB203580对照组和溶液对照组.LPS组以终浓度100μg/L的LPS与VSMC共同孵育;干预组VSMC以p38MAPK抑制剂SB203580 10μmol/L预处理2 h,再加入终浓度100 9g/L的LPS共同孵育;对照组仅以SB203580 10 μmol/L预处理2 h;溶液组仅加入去血清培养液培养.各组于培养0、3、6、12、24 h后采用实时聚合酶链反应(real-time PCR)和酶联免疫吸附法(ELISA)分别检测细胞IL-6 mRNA和上清液中IL-6蛋白表达.结果 LPS刺激3 h,VSMC中IL-6 mRNA和蛋白表达即出现明显增高CmRNA(21.3±3.2)×104,蛋白(296.2±19.6)ng/L],12 h达高峰CmRNA(131.4±11.2)×104,蛋白(897.7±34.0)ng/L],24 h有所降低[mRNA(15.3±4.7)×104,蛋白(194.3±24.0)ng/L],但仍显著高于溶液组(mRNA(9.4±1.9)×104,蛋白(29.4±4.4)ng/L,均P<0.05].干预组3、6、12 h可明显抑制LPS诱导VSMC中IL-6的分泌[mRNA(15.4±3.6)×104、(43.2±6.6)X 104、(56.2±5.5)×104,蛋白(180.3±23.6)、(432.2±56.8)、(546.2±57.9)ng/L,均P<0.05].结论 LPS诱导VSMC可明显增加IL-6的mRNA和蛋白表达,p38MAPK抑制剂SB203580可显著抑制IL-6转录和蛋白合成,表明p38MAPK信号转导通路可能通过直接或间接作用参与了IL-6的分泌调节作用.     

Carbon monoxide generated by heme oxygenase 1 suppresses endothelial cell apoptosis

Heme oxygenase 1 (HO-1) inhibits apoptosis by regulating cellular prooxidant iron. We now show that there is an additional mechanism by which HO-1 inhibits apoptosis, namely by generating the gaseous molecule carbon monoxide (CO). Overexpression of HO-1, or induction of HO-1 expression by heme, protects endothelial cells (ECs) from apoptosis. When HO-1 enzymatic activity is blocked by tin protoporphyrin (SnPPIX) or the action of CO is inhibited by hemoglobin (Hb), HO-1 no longer prevents EC apoptosis while these reagents do not affect the antiapoptotic action of bcl-2. Exposure of ECs to exogenous CO, under inhibition of HO-1 activity by SnPPIX, substitutes HO-1 in preventing EC apoptosis. The mechanism of action of HO-1/CO is dependent on the activation of the p38 mitogen-activated protein kinase (MAPK) signaling transduction pathway. Expression of HO-1 or exposure of ECs to exogenous CO enhanced p38 MAPK activation by TNF-alpha. Specific inhibition of p38 MAPK activation by the pyridinyl imidazol SB203580 or through overexpression of a p38 MAPK dominant negative mutant abrogated the antiapoptotic effect of HO-1. Taken together, these data demonstrate that the antiapoptotic effect of HO-1 in ECs is mediated by CO and more specifically via the activation of p38 MAPK by CO.