p38 Mitogen-activated protein kinase up-regulates LPS-induced NF-kappaB activation in the development of lung injury and RAW 264.7 macrophages

Clarification of the key regulatory steps that lead to nuclear factor-kappa B (NF-kappaB) under cellular and pathological conditions is very important. The action of p38 mitogen-activated protein kinase (MAPK) on the upstream of NF-kappaB activation remains controversial. To examine this issue using an in vivo lung injury model, SB203580, a p38 MAPK inhibitor was given intraorally 1h prior to lipopolysaccharide (LPS) treatment (intratracheally). The mice were sacrificed 4 h after LPS treatment. SB203580 substantially suppressed LPS-induced rises in p38 MAPK phosphorylation, neutrophil recruitment, total protein content in bronchoalveolar lavage fluid, and apoptosis of bronchoalveolar cells. Furthermore, SB203580 blocked LPS-induced NF-kappaB activation in lung tissue through down-regulation of serine phosphorylation, degradation of IkappaB-alpha, and consequent translocation of the p65 subunit of NF-kappaB to the nucleus. It is likely that, in cultured RAW 264.7 macrophages, SB203580 also blocked LPS-induced NF-kappaB activation in a dose-dependent manner. SB203580 inhibited LPS-induced serine phosphorylation, degradation of IkappaB-alpha, and tyrosine phosphorylation of p65 NF-kappaB. These data indicate that p38 MAPK acts upstream of LPS-induced NF-kappaB activation by modulating the phosphorylation of IkappaB-alpha and p65 NF-kappaB during acute lung injury. Because LPS-stimulated macrophages may contribute to inflammatory lung injury, the inhibition of the p38 MAPK-mediated intracellular signaling pathway leading to NF-kappaB activation represents a target for the attenuation of lung inflammation and parenchymal damage.     

Blockade of p38 map kinase inhibits complement-induced acute lung injury in a murine model

Features of acute lung injury include neutrophil influx and increased vascular permeability with resultant pulmonary edema. Inhibition of p38 mitogen-activated protein kinase (MAPK) in in vivo models of endotoxin-induced inflammation results in reduction of organ injury as well as symptomatic relief. In this study, mice received an oral dose (100 mg/kg) of the p38 MAPK inhibitor, SB203580, followed by intratracheal instillation of an agent of complement origin, C5a des arg, at a concentration (10 microg) that induced acute lung injury. Neutrophil and protein content of bronchoalveolar lavage fluid as indicators of leukocyte influx and vascular permeability respectively were assessed. Animals that received C5a-instillation had a significant influx of neutrophils into the lungs (49+/-8%) while mice receiving C5a-instillation and prior treatment with SB203580 exhibited diminished influx (16+/-5%). Similarly, pretreatment with oral SB203580 resulted in decreased vascular permeability (241+/-34 microg/ml) than the positive control animals (407+/-135 microg/ml). Activity analysis of total lung p38 MAPK revealed that p38 activity was increased at 4 h after C5a-instillation and that SB203580-treated C5a-instilled mouse lungs had lower p38 activity than did the C5a-instilled control. These data indicate that oral administration of an agent inhibitory for p38 MAPK offers a protective effect in the lungs from both neutrophil influx and protein leak associated with acute lung injury.     

p38 but not p44/42 mitogen-activated protein kinase is required for nitric oxide synthase induction mediated by lipopolysaccharide in RAW 264.7 macrophages

Protein kinase C (PKC)-alpha, -betaI, and -delta are known to be involved in the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages. The role of mitogen-activated protein kinases (MAPK) p44/42 and p38 in the LPS effect was studied further. LPS-mediated NO release and the inducible form of NO synthase expression were inhibited by the p38 inhibitor, SB 203580, but not by the MAPK kinase inhibitor, PD 98059. Ten-minute treatment of cells with LPS resulted in the activation of p44/42 MAPK, p38, and c-Jun NH2-terminal kinase. Marked or slight activation, respectively, of p44/42 MAPK or p38 was also seen after 10-min treatment with 12-O-tetradecanoylphorbol-13-acetate, but c-Jun NH2-terminal kinase activation did not occur. Tyrosine kinase inhibitor, genestein, attenuated the LPS-induced activation of both p44/42 MAPK and p38, whereas the PKC inhibitors, Ro 31-8220 and calphostin C, or long-term treatment with 12-O-tetradecanoylphorbol-13-acetate resulted in inhibition of p44/42 MAPK activation, but had only a slight effect on p38 activation, indicating that LPS-mediated PKC activation resulted in the activation of p44/42 MAPK. Nuclear factor-kappaB (NF-kappaB)-specific DNA-protein-binding activity in the nuclear extracts was enhanced by 10-min, 1-h, or 24-h treatment with LPS. Analysis of the proteins involved in NF-kappaB binding showed translocation of p65 from the cytosol to the nucleus after 10-min treatment with LPS. The onset of NF-kappaB activation correlated with the cytosolic degradation of both inhibitory proteins of NF-kappaB, IkappaB-alpha and IkappaB-beta. IkappaB-alpha was resynthesized rapidly after loss (1-h LPS treatment), whereas IkappaB-beta levels were not restored until after 24-h treatment. SB 203580 but not PD 98059 inhibited the LPS-induced stimulation of NF-kappaB DNA-protein binding. Thus, activation of p38 but not p44/42 MAPK by LPS resulted in the stimulation of NF-kappaB-specific DNA-protein binding and the subsequent expression of inducible form of NO synthase and NO release in RAW 264.7 macrophages.     

Glutathione depletion in CYP2E1-expressing liver cells induces toxicity due to the activation of p38 mitogen-activated protein kinase and reduction of nuclear factor-kappaB DNA binding activity

Depletion of glutathione (GSH) from CYP2E1-expressing cells by treatment with l-buthionine sulfoximine (BSO) causes decreased cell viability. The possible role of mitogen-activated protein kinases (MAPK) in this toxicity was evaluated. SB203580 [4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole], an inhibitor of p38 MAPK decreased the BSO-dependent toxicity in HepG2 E47 cells, which express CYP2E1 and in hepatocytes from pyrazole-treated rats. Inhibitors of extracellular signal-regulated kinase, phosphatidylinositol 3-kinase, and c-Jun amino-terminal kinase were not protective. SB203580 did not prevent the loss of GSH nor lower the increase in reactive oxygen production; hence, protection by SB203580 was downstream of the elevated oxidative stress. Treatment with BSO caused activation of p38 MAPK whereas activation of nuclear factor-kappaB (NF-kappaB) was decreased; these effects were prevented by SB203580. We speculated that the decrease in NF-kappaB activation prevented production of hepatoprotective factors. One such factor could be nitric oxide (NO); indeed a NO donor decreased the BSO plus CYP2E1-dependent toxicity, whereas inhibition of inducible NO synthase (iNOS) potentiated toxicity. BSO treatment down-regulated iNOS and lowered NO levels, reactions blocked by SB203580; however, protection by SB203580 was the same in the absence or presence of an iNOS inhibitor, indicating that recovery of iNOS and NO production was not the mechanism by which SB203580 afforded protection against the BSO plus CYP2E1-dependent toxicity. Presumably other protective factors besides nitric oxide may be produced from activated NF-kappaB when p38 MAPK is inhibited by SB203580. These results suggest that the activation of p38 MAPK by BSO treatment in CYP2E1-expressing liver cells cause a loss in NF-kappaB-dependent production of hepatoprotective factors. This loss, coupled to CYP2E1-generated oxidant stress, synergize to promote cell injury.     

Role of p38 MAP kinase in LPS-induced airway inflammation in the rat

We investigated the effect of the p38 kinase inhibitor SB 203580 on airway inflammation induced by aerosolized lipopolysaccharide (LPS) in male Wistar rats. SB 203580 significantly inhibited (ED(50)=15.8 mg kg(-1)) plasma levels of TNF-alpha in rats challenged with LPS (1.5 mg kg(-1), i.p.). Aerosolized LPS induced a peak in TNF-alpha levels and the initiation of a neutrophilic response in bronchoalveolar lavage (BAL) fluid at the 2 h time point. Furthermore, the 4 h time point was associated with the peak in IL-1beta levels and the initial plateau of neutrophilia observed in the BAL fluid. SB 203580 (100 mg kg(-1)), had no effect on peak TNF-alpha levels or the associated neutrophilia in the BAL. Interestingly, the PDE 4 inhibitor RP 73401 (100 mg kg(-1)) significantly reduced both TNF-alpha levels and neutrophilic inflammation. However, the BAL fluid from rats pre-treated with either compound significantly inhibited TNF-alpha release from cultured human monocytes 18 h after LPS treatment (83.6 and 44.5% inhibition, respectively). Alternatively, SB 203580 (100 mg kg(-1)) produced dose-related inhibition of BAL IL-1beta levels (67.5% inhibition, P<0.01) and BAL neutrophilia (45.9% inhibition, P<0.01) 4 h after LPS challenge. P38 protein was present in lung tissue and the level of expression was not affected by LPS treatment. P38 kinase appears to be involved in the release of IL-1beta and the sustained neutrophilic response in the BAL fluid. This data may suggest a role for p38 inhibitors in the treatment of airway inflammatory diseases in which neutrophilia is a feature of the lung pathology.     

槐定碱对LPS诱导的RAW264.7巨噬细胞p38、iNOS表达的影响

目的探讨槐定碱(sophoridine,SRI)在内毒素导致的炎症反应中的作用。方法采用LPS诱导的RAW264.7巨噬细胞建立细胞炎症反应模型,实验细胞分为5组(n=6):空白对照组、LPS组、槐定碱组、SB203580组、SB203580+槐定碱组,利用反转录聚合酶链反应(RT-PCR)技术检测RAW264.7巨噬细胞p38 mRNA表达量;利用Western blot技术检测RAW264.7巨噬细胞p-p38与iNOS蛋白的表达量。结果槐定碱组与LPS组比较p-p38蛋白表达量和p38 mRNA表达量降低,但高于空白对照组(P<0.01),表明槐定碱可以抑制LPS诱导的RAW264.7巨噬细胞p-p38蛋白表达和p38 mRNA表达量;与LPS组比较,槐定碱组iNOS蛋白表达量降低,但高于空白对照组(P<0.01),SB203580+槐定碱组iNOS蛋白表达量低于槐定碱组和SB203580组(P<0.01),表明槐定碱可以抑制LPS诱导的RAW264.7巨噬细胞P38MAPK信号通路下游iNOS蛋白表达,并且与SB203580有协同作用。结论槐定碱可以通过抑制p38MAPK位点而下调p-p38、iNOS蛋白表达而发挥抗炎作用。     

己酮可可碱对大鼠脓毒症急性肺损伤p38MAPK活性的影响

目的探讨己酮可可碱（pentoxifylline,PTX）对腹腔感染致脓毒症急性肺损伤发挥肺保护作用与p38MAPK活化的关系。方法采用盲肠结扎穿孔致脓毒症模型,将大鼠随机分为Ⅰ组（Sham组）、Ⅱ组（脓毒症CLP组）、Ⅲ组（脓毒症加西黄著胶CLP＋V组）、Ⅳ组（脓毒症加生理盐水CLP＋N组）、Ⅴ组（脓毒症加SB203580 CLP＋SB组）、Ⅵ组（脓毒症加己酮可可碱CLP＋PTX组）,其中Ⅲ组、Ⅳ组为溶媒对照组。用Western Blot检测假手术组,脓毒症1,3,6,12,24 h后p38MAPK的磷酸化,然后选择1,6,24 h分别检测应用SB203580或PTX后p38MAPK的表达,同时检测血浆TNF-α、IL-6的含量并观察24 h内肺组织病理改变。结果与假手术组比较,脓毒症组在各个时间点p38MAPK均有较强的表达,SB203580或PTX预处理后各组的p38MAPK的磷酸化明显受到抑制,且与血浆TNF-α、IL-6的含量以及肺的病理切片变化一致。结论己酮可可碱可能是通过抑制p38MAPK的磷酸化抑制促炎因子的过度表达,发挥对脓毒症急性肺损伤的保护作用。     

Src tyrosine kinases mediate crystalline silica-induced NF-kappaB activation through tyrosine phosphorylation of IkappaB-alpha and p65 NF-kappaB in RAW 264.7 macrophages.

Protein tyrosine kinases (PTKs) and mitogen-activated protein kinases (MAPKs) have been demonstrated to play a crucial role in the signaling pathways induced by silica. In the present study, we investigated whether Src family TKs play a role in crystalline silica-induced NF-kappaB activation and whether NF-kappaB activation requires Src TK-dependent MAPK activity in RAW 264.7 cells, a mouse peritoneal macrophage cell line. Selective Src TK inhibitors, damnacanthal or PP1, inhibited silica-induced NF-kappaB activation in a dose-dependent manner. Furthermore, these kinase inhibitors suppressed silica-induced tyrosine phosphorylation of IkappaB-alpha and p65 NF-kappaB. Within a similar time frame, c-Src and Lck were physically associated with IkappaB-alpha and with p65 NF-kappaB. Silica stimulated the phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2), but not p38 MAPK and c-Jun NH(2)-terminal kinase 1 and 2 (JNK1/2). Damnacanthal or PP1 substantially blocked the silica-induced activation of ERK1/2. Moreover, PD98059, an inhibitor of ERK1/2, or SB203580, an inhibitor of p38 MAPK, failed to inhibit silica-induced NF-kappaB activation. These results suggest that c-Src and Lck act for silica-induced NF-kappaB activation by mediating the tyrosine phosphorylations of IkappaB-alpha and p65 NF-kappaB. However, the Src TK-dependent activation of ERK1/2 may not be involved in the silica signaling pathway leading to NF-kappaB activation.     

p38蛋白激酶抑制剂SB203580对支气管哮喘小鼠气道炎症和Th2类细胞因子的影响

目的观察特异性p38蛋白激酶(p38 MAPK)抑制剂SB203580对哮喘小鼠气道炎症和Th2类细胞因子的影响。方法BALB/c小鼠30只随机分成3组,即正常对照组、哮喘模型组和SB203580干预组。通过原位分子杂交和酶联免疫吸附法(ELISA)检测肺组织IL-4、IL-5 mRNA和支气管肺泡灌洗液(BALF)中白细胞介素(IL-4、IL-5)含量的变化,并观察BALF中炎症细胞和肺组织病理学改变。结果哮喘模型组小鼠BALF中炎症细胞计数和IL-4、IL-5含量以及肺组织IL-4、IL-5mRNA的表达较正常对照组明显升高,差异具有显著性(P<0.01);SB203580干预组小鼠上述指标较哮喘模型组小鼠明显降低,差异亦具有显著性(P<0.01),肺组织病理学改变明显减轻。结论SB203580能降低气道炎症细胞的聚集和炎症介质的表达。抑制p38 MAPK的活性可能成为哮喘治疗的新途径。     

Role of p38 mapk on the down-regulation of matrix metallo-proteinase-9 expression in rat astrocytes

In spite of their pathophysiological importance in neuro-inflammatory diseases, little is known about the signal transduction pathways that lead to the induction of matrix metalloproteinases (MMPs) in the central nervous system. We reported previously that lipopolysaccharide (LPS) induced MMP-9 expression through ERK1/2 pathway in rat primary astrocytes (Glia 41:15-24, 2003). Here, we investigated the role of other MAPK pathways, including p38 and JNK/SAPK, on the regulation of MMP-9 expression in LPS-stimulated rat primary astrocytes. LPS activated both p38 and JNK in astrocytes. Treatment with a specific p38 MAPK inhibitor SB203580, but not JNK inhibitor SP600125, increased the LPS-stimulated MMP-9 expression in a concentration-dependent manner. Anti-inflammatory cytokines, including IFN-gamma and IL-4, activated p38 MAPK and decreased MMP-9 production in LPS-stimulated astrocytes. When p38 MAPK activation was blocked by SB203580, the inhibitory effects of these cytokines on MMP-9 induction were abolished. Finally, direct injection of SB203580 into the lateral ventricle of rat brain increased the LPS-induced MMP-9 activity in cerebral cortex. Altogether, these results suggest that p38 activation down-regulates the inflammatory stimulation-induced overexpression of MMP-9, both in primary astrocytes and in cerebral cortex. The elaborate interplay between ERK1/2 and p38 pathways provides a more sophisticated mechanism for regulating MMP-9 activity in neuroinflammatory diseases.     

Differential regulation of eotaxin-1/CCL11 and eotaxin-3/CCL26 production by the TNF-alpha and IL-4 stimulated human lung fibroblast

Allergic asthma and allergic dermatitis are chronic inflammatory diseases and are characterized by an accumulation of eosinophils at sites of inflammation. Eotaxin-1/CCL11 and eotaxin-3/CCL26 are members of the CC chemokine family, which are known to be potent chemoattractants for eosinophils. We observed that a human lung fibroblast, HFL-1 produces eotaxin-1 and -3 in response to TNF-alpha plus IL-4 stimulation, accompanied with NF-kappaB and STAT6 activation. We explored which signaling pathways are operative in the production of eotaxin-1 and -3 using several inhibitors. Eotaxin-1/CCL11 production was inhibited by a p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, but not by the MEK (MAPK/ERK kinase) inhibitors, PD98059 and U0126. In contrast, eotaxin-3/CCL26 production was inhibited similarly by PD98059 as well as U0126 and SB203580. In addition, two proteasome inhibitors, N-acetyl-leucyl-leucyl-norleucinal (ALLN) and bortezomib with significant inhibitory activity on NF-kappaB activation, inhibited eotaxin-1/CCL11 production with IC(50) 8 muM for ALLN and IC(50) 16 nM for bortezomib. In contrast, eotaxin-3/CCL26 production was not inhibited significantly up to 10 muM of ALLN (IC(50 )16 muM) and up to 10 nM of bortezomib (IC(50) 11 nM), giving inhibition of eotaxin-3/CCL26 less sensitive than eotaxin-1/CCL11 production by the proteasome inhibitors. Synergistic inhibition was observed among lower doses of SB203580 and proteasome inhibitors, particularly in the eotaxin-1/CCL11 production. No such prominent synergism was found on the eotaxin-3/CCL26 production. The suppression of eotaxin family production by these inhibitors may be efficacious against allergic diseases.     

p38 MAPK activation is required for esculetin-induced inhibition of vascular smooth muscle cells proliferation

The phenolic compound esculetin is known to inhibit the proliferation of vascular smooth muscle cells (VSMC). However, the signaling pathway by which esculetin mediates its molecular effects in VSMC remains to be identified. The present results suggest an unexpected role of the p38 MAPK signaling pathway in esculetin-induced inhibition of VSMC growth. Treatment of VSMC with esculetin resulted in significant growth inhibition and G1-phase cell-cycle arrest, which was followed by down-regulation of cyclins and cyclin-dependent kinase (CDK) expression. This G1-phase cell-cycle arrest was due to up-regulation of p21WAF1 expression. In addition, esculetin treatment activated p38 MAPK and ERK1/2. Pretreatment with SB203580, which is a p38 MAPK specific inhibitor, or expression of the dominant negative p38 MAPK (DN p38 MAPK) gene blocked esculetin-induced p38 MAPK activation and p21WAF1 expression. Finally, both the growth inhibition and the down-regulation of CDKs induced by esculetin were suppressed by either SB203580 or the DN p38 MAPK mutant gene. In conclusion, these results demonstrate that activation of p38 MAPK contributes to esculetin-induced p21WAF1 expression in VSMC by decreasing both the cyclin D1/CDK4 and cyclin E/CDK2 complexes. These novel results regarding the molecular mechanism of esculetin action suggest new preventive and therapeutic treatments for atherosclerosis.     

黄芪多糖在未成年大鼠心肌缺血再灌注炎性损伤中的作用

目的：研究黄芪多糖在未成年大鼠心肌缺血再灌注炎性损伤中的作用。方法：1周龄雄性SD大鼠随机分为5组,假手术组（S组）、缺血再灌注组（I/R组）、黄芪多糖组（40 mg·kg^-1,APS组、p38MAPK阻断剂SB203580组（5 mg·kg^-1,SB组）,APS+SB203580组（APS 40 mg·kg^-1+SB203580 5 mg·kg^-1,APS+SB组） ,给药20 d后,进行冠状动脉左前降支结扎60 min后恢复血流再灌注120 min,经眼眶采血后处死大鼠。ELISA法和Western-blot法分别测定外周血和心肌组织中TNF-α、NF-κB、p38MAPK及p-p38MAPK蛋白表达。结果：在外周血和心肌组织中,与S组比较,I/R组、APS组、SB组、及APS+SB组中TNF-α、NF-κB、p-p38MAPK表达水平均明显升高（P值均小于0.05）;与I/R组比较,APS组、SB组及黄芪APS+SB组中TNF-α、NF-κB和p-p38MAPK表达水平明显降低（P值均小于0.05）。APS+SB组对TNF-α、NF-κB、和p-p38的蛋白表达抑制作用要显著强于APS组的抑制作用（P值均小于0.05）。结论：黄芪多糖和p38MAPK阻断剂（SB203580）均能够有效改善未成年大鼠的心肌缺血再灌注损伤时的炎症反应,黄芪多糖和SB203580联用可以明显抑制TNF-α和NF-κB的表达,抑制p38MAPK信号通路,具有抑制心肌缺血再灌注损伤的协同作用。     

Iron tetrakis (N-methyl-4'-pyridyl) porphyrinato inhibits proliferative activity of thymocytes by blocking activation of p38 mitogen-activated protein kinase,nuclear factor-kappaB,and interleukin-2 secretion

Iron tetrakis (N-methyl-4'-pyridyl) porphyrinato (FeTMPyP) has been demonstrated to be a potent scavenger of reactive oxygens and to have antiinflammatory activities. However, the effects of FeTMPyP on the function of T cells have not been illustrated. The objective of this study was to determine whether treatment of thymocytes with FeTMPyP inhibited the proliferative activity in response to various mitogens and, if so, to further characterize the mechanism of FeTMPyP immune modulation. The results indicate that treatment of thymocytes with FeTMPyP resulted in dose-dependent inhibition of thymocyte proliferation stimulated by concanawalin (Con) A-, Interleukin (IL)-1beta; or lipopdy socchande-exposed macrophage supernatant. FeTMPyP treatment also inhibited Con A- or IL-1beta-induced DNA-binding activity of NF-kappaB and IL-2 secretion by thymocytes. Both the p38 MAP kinase inhibitor SB203580 and the extracellular signal-regulated protein kinases inhibitor PD98059 blocked proliferative activity in Con A-stimulated thymocytes, while SB203580 but not PD98059 blocked nuclear factor (NF)-kappaB activation. FeTMPyP inhibited the activation and phosphorylation of p38 mitogen-activated protein kinase (MAPK) in response to Con A. These data suggest that FeTMPyP downregulates the proliferative activity by inhibition of p38 MAPK activation, NF-kappaB activation, and IL-2 secretion during mitogenic stimulation of thymocytes. Therefore, further studies concerning the effects of FeTMPyP on the human diseases associated with both inflammatory disorders and immunologic overactivation are warranted.     

Additive effects of heat and p38 mapk inhibitor treatment on melanin synthesis

It has been reported that the activation of extracellular signal-regulated kinase (ERK) reduces melanin synthesis. Recently, we also found that heat treatment induces ERK activation and inhibits melanogenesis in Mel-Ab cells (a mouse melanocyte cell line). In addition, it was reported that p38 MAPK (mitogen-activated protein kinase) inhibition blocks melanogenesis. Thus, we investigated the effects of heat and of the p38 MAPK inhibitor, SB203580, on melanogenesis. In this study, we found that heat treatment activates ERK and reduces melanin production in human melanocytes, and that this is accompanied by a reduction in tyrosinase activity. To regulate the ERK and p38 MAPK pathways simultaneously, we combined heat treatment and SB203580 and measured melanin synthesis. The results obtained showed that heat treatment and SB203580 reduced melanin synthesis more effectively than heat or SB203580 alone. We conclude that ERK activation and p38 MAPK inhibition can work in an additive manner to decrease melanogenesis.     

Hyaluronan ameliorates LPS-induced acute lung injury in mice via Toll-like receptor (TLR) 4-dependent signaling pathways

Toll-like receptor-4 (TLR4) signaling has been implicated in innate immunity and acute inflammation following acute lung injury (ALI). As such, modulating inflammatory response through TLR4 represents an attractive therapeutic approach to treat ALI. Increasing evidence demonstrates that hyaluronan (HA) can modulate TLR4 activation and has shown early promise as a therapeutic agent in ALI. However, the mechanism associated with HA has not been fully elucidated. In the current study, we sought to determine the effects of HA on lipopolysaccharide (LPS)-induced inflammatory response and gain insights into the mechanism of action in mice with intratracheal instillation of LPS. Our results demonstrate that in contrast to mice challenged with LPS, pretreatment with HA significantly inhibited inflammatory cell recruitment, attenuated lung injury and suppressed the level of cytokine/chemokine in bronchial alveolar lavage fluid (BALF). Investigation of the mechanism responsible for inhibition of LPS activation showed HA treatment significantly inhibited the nuclear translocation of NF-κB p65 and protein expression of myeloid differentiation primary response protein (MyD88) and TIR-domain-containing adapter-inducing interferon-β (TRIF) and p38 MAPK, JNK and ERK activation in lung tissue. Furthermore, we compared the protection effect of HA in TLR4-deficient mice with those of genetically matched wild type (WT) mice in an acute model of lung injury. However, in TLR4-deficient mice, HA pretreatment before LPS instillation fail to affect the LPS response. Therefore, our findings suggest that HA pretreatment attenuated LPS-induced ALI and the anti-inflammatory function of HA was partial dependent on TLR4, which shed new light on potential elements that regulate the lung injury response.     

己酮可可碱弱化大鼠脓毒症急性肺损伤对p38MAPK/IκBα磷酸化的影响

目的探讨己酮可可碱（pentoxifylline,PTX）对腹腔感染致脓毒症急性肺损伤发挥保护作用的上游信号机制。方法采用盲肠结扎穿孔（cecal ligation and puncture,CLP）致脓毒症模型,将大鼠随机分为假手术组、脓毒症组、脓毒症＋西黄著胶组、脓毒症＋生理盐水组、脓毒症＋SB203580组、脓毒症＋PTX组。检测假手术组、脓毒症组各时间点（1,3,6,12,24 h）p38MAPK及IκBα的磷酸化,然后选择1,6,24 h组分别检测应用SB203580或PTX后p38MAPK及IκBα的表达,同时检测血浆TNF-α、IL-6的含量并观察24 h组肺组织病理改变。结果与假手术组比较,脓毒症组在各个时间点p38MAPK及IκBα均有较强的表达,SB203580或PTX预处理后各组的p38MAPK及IκBα的磷酸化明显受到抑制,且与血浆TNF-α、IL-6的含量以及肺的病理切片变化一致。结论 PTX对脓毒症急性肺损伤的保护作用以及抑制促炎因子产生的作用可能是通过抑制p38MAPK的磷酸化从而抑制NF-κB的活化而产生的。