戊乙奎醚预处理对脓毒症小鼠肺损伤时MAPK信号转导通路的影响

目的 探讨戊乙奎醚(PHC)预处理对脓毒症小鼠肺损伤时丝裂原活化蛋白激酶(MAPK)信号转导通路的影响.方法 健康雌性昆明小鼠105只,体重20～25 g,随机分为3组(n=35):假手术组(S组)、脓毒症(CLP)组和戊乙奎醚(PHC)组.采用盲肠结扎并穿孔法制备脓毒症模型.PHC组于造模前1 h腹腔注射戊乙奎醚0.45 mg/kg,s组和CLP组于造模前1 h注射等容量生理盐水.于造模后即刻测定肺微血管通透性;造模后12 h时进行动脉血气分析,观察肺组织病理结果,测定肺组织丙二醛(MDA)含量、超氧化物歧化酶(SOD)活性和磷酸化的p38丝裂原活化蛋白激酶(p38MAPK)、细胞外信号调节激酶(ERK1/ERK2)和c-jun氨基末端蛋白激酶(JNK)表达.结果 与S组比较,CLP组PaO2、PaO2/FiO2和pH值降低,肺微血管通透性和肺组织MDA含量升高,SOD活性降低,磷酸化的p38MAPK、ERK1/ERK2和JNK表达上调(P<0.05或0.01);与CLP组比较,PHC组PaO2、PaO2/FiO2和pH值升高,肺微血管通透性和肺组织MDA含量降低,SOD活性升高,磷酸化的p38MAPK和ERK1/ERK2表达下调(P<0.05或0.01).结论 戊乙奎醚预处理可通过抑制MAPK信号转导通路(p38MAPK和ERK1/ERK2)的激活,从而减轻脓毒症小鼠肺损伤.     

Distinct signaling pathways are involved in hypoxia- and IL-1-induced VEGF expression in human articular chondrocytes.

Recent data suggest that vascular endothelial growth factor (VEGF) is involved in the pathogenesis of osteoarthritis (OA). Cartilage is an avascular tissue, leading to a low cartilage O2 level. Thus, in a variety of pathologic or physiologic conditions, VEGF is partly regulated by hypoxic stress. The implications of hypoxia for VEGF expression by OA chondrocytes, however, are not known. We investigated the regulatory system of VEGF in OA chondrocytes under hypoxic conditions. Chondrocytes were obtained from articular cartilage of patients with OA. Cells were cultured and then incubated under hypoxic (95% N2, 5% CO2) or normoxic conditions, with or without interleukin (IL)-1 (10 ng/mL) stimulation. The mitogen activated protein kinase (MAPK) inhibitors were also used. VEGF levels in the culture supernatants were measured using an enzyme-linked immunosorbent assay. Western blot analysis was used to examine the expression of hypoxia inducible factor (HIF)-1alpha. Hypoxia significantly increased VEGF levels (p<0.05). Hypoxia-induced VEGF secretion was abolished by p38MAPK inhibitor, but not by JNK inhibitor. In contrast, IL-1-induced VEGF secretion was blocked by JNK inhibitor, and not by p38MAPK inhibitor. Both hypoxia and IL-1-induced HIF-1alpha were attenuated by p38 MAPK and JNK inhibitors. We demonstrate that hypoxia and IL-1 induce VEGF production in chondrocytes through distinct MAPK signaling pathways, indicating that VEGF is induced in a HIF-1-dependent or -independent manner in chondrocytes.     

NK026680 inhibits T-cell function in an IL-2-dependent manner and prolongs cardiac allograft survival in rats

NK026680 is a triazolopyrimidine derivative that has been shown to inhibit dendritic cell maturation and activation. Here, we examined the immunosuppressive properties of NK026680 on T-cell function and assessed its immunosuppressive efficacy in an ACI (RT1^av1 haplotype) to Lewis (RT1^l) rat heart transplantation model. The effects of NK026680 on T-cell proliferation, activation, and cytokine production were investigated in vitro. Heart transplant recipient rats were administered NK026680 daily for 14 days post-transplantation. In addition to graft survival time, alloimmune responses and graft histology at 4-10 days post-transplantation were assessed. NK026680 was found to inhibit proliferation, CD25 upregulation, IL-2 production, and cell cycle progression in αCD3/αCD28-stimulated murine T cells. These effects were likely due to suppression of the p38 mitogen-activated protein kinase pathway and the subsequent inhibition of p65, c-Fos, and to a lesser extent, c-Jun. Daily NK026680 treatment suppressed alloimmune responses, prevented cellular infiltration into allografts, and prolonged graft survival. The anti-rejection effects of NK026680 were enhanced by tacrolimus. In conclusion, NK026680 inhibits the activation of T cells and prolongs cardiac allograft survival in rats. These features make it a potential candidate immunosuppressant for the treatment of organ transplant patients in the future.     

烧伤血清作用下心肌细胞蛋白激酶B和p38丝裂原活化蛋白激酶通路的交叉对话研究

目的 了解在烧伤血清刺激下大鼠心肌细胞内是否存在磷脂酰肌醇3-激酶(PI3K)/蛋白激酶B(Akt)与p38丝裂原活化蛋白激酶(p38MAPK,以下简称p38)信号通路的交叉对话,探讨此二通路在烧伤后心肌细胞损伤中的作用. 方法建立烧伤血清刺激下的大鼠心肌细胞模型.(1)检测体积分数10%的烧伤血清刺激不同时间后,心肌细胞内磷酸化p38(p-p38)和磷酸化Akt(p-Akt)的表达水平.(2)检测在不同体积分数(5%、10%、20%)的烧伤血清或体积分数10%烧伤血清+胰岛素(1×10-6、1×10-7、1×10-8mol/L)作用下,心肌细胞内p-p38和p-Akt的表达水平,并测定细胞培养上清液中肌酸激酶(CK)的含量.(3)采用p38MAPK通路抑制剂SB203580、PI3K/Akt通路抑制剂LY294002进行阻断实验,测定心肌细胞内p-p38和p-Akt的表达水平及细胞培养上清液中CK的含量. 结果 (1)体积分数10%烧伤血清作用1、3、6、12、24 h时,心肌细胞p-p38水平分别为4.0±0.8、3.6±0.8、5.1±1.6、2.4±0.5、3.0±0.6,较作用0 h时(加入血清后即刻)的水平(1.0)明显增高(P<0.01);而p-Akt表达水平分别为0.15±0.07、0.64±0.10、0.26±0.08、0.38±0.11、0.59±0.13,较作用0 h时水平(1.00)明显降低(P<0.01).(2)不同浓度烧伤血清或烧伤血清+胰岛素作用下,p-p38和p-Akt的表达水平呈相反变化趋势;心肌细胞CK的释放量随烧伤血清浓度升高而增高,胰岛素对此有明显的抑制作用(P<0.05或P<0.01).(3)LY294002能够升高烧伤血清导致的低P-p38水平,抵消胰岛素的保护作用(P<0.01);SB203580能使烧伤血清所致的低p-Akt水平得以回升(P<0.01),抑制烧伤血清引起的CK释放. 结论烧伤血清作用下的心肌细胞存在PI3K/Akt和p38信号通路的交叉对话,并可能对心肌细胞产生调控作用.     

Role of mitogen‐activated protein kinase in osteoblast differentiation

Local control of osteoblast differentiation and bone formation is not well understood. We have previously seen biphasic effects on cell differentiation in response to the short‐ and long‐term exposure to IL‐1β in rat calvarial osteoblasts. To characterize the signaling pathway mechanisms regulating IL‐1β biphasic effects, we examined the contribution of mitogen‐activated protein kinase (MAPK) family. Cells were pretreated with specific inhibitors to extracellular signal‐regulated kinase (ERK, PD98059), p38 (SB203580), and c‐JUN N‐terminal kinase (JNK, SP600125), then co‐cultured with IL‐1β for 2, 4, and 6 days. Cell differentiation was determined by measuring bone nodules after 10 days of culture. These inhibitors did not alter biphasic effects of IL‐1β on cell differentiation. However, PD98059 and U2016, another inhibitor of ERK activation robustly increased osteoblast differentiation compared to vehicle‐treated control in a time‐ and dose‐dependent manner. PD98059 appears to stimulate alkaline phosphatase (ALP) activity to promote cell differentiation, where IL‐1β appears to suppress it. Interestingly, continuous ERK inhibition with PD98059, after 2 and 4 days of IL‐1β treatment, enhanced the IL‐1β anabolic effect by increasing bone nodules formed. These observations provide a potential mechanism involving ERK pathway in osteoblasts differentiation and suggest that MAPK family may not directly regulate IL‐1β biphasic effects. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:204–210, 2011     

Fibronectin fragment activation of ERK increasing integrin α5 and β1 subunit expression to degenerate nucleus pulposus cells

Fibronectin fragments (Fn‐f), which are the breakdown products of fibronectin, accumulate in the disc during degeneration and are proved to induce the degeneration of intervertebral disc. The goal of this investigation was to determine the functional role of integrin α₅β₁, extracellular signal‐regulated kinase (ERK), and protein kinase C (PKC) in the process of Fn‐f degeneration nucleus pulposus (NP) cells. We found that Fn‐f (100 nM, 30 kDa) exposure led to degeneration of NP cells, up‐regulation of integrin α₅β₁ expression and phosphorylation of the ERK_1/2. After the expression of integrin α₅β₁ was silenced in NP cells, the phosphorylation of ERK_1/2 and the expression of MMP9, MMP13, and collagen II had no difference with control under the treatment of Fn‐f. Finally, when the inhibitor of ERK_1/2 and the inhibitor of PKC were added into the medium of NP cells; we found these two inhibitors could eliminate the effect of Fn‐f on NP cells. It is concluded that Fn‐f had the potential to enhance the NP cell degeneration in a vicious circle. And the integrin α₅β₁ subunit, ERK, and PKC were all included in this loop. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:556–561, 2011     

Molecular requirements for induction of CTGF expression by TGF-beta1 in primary osteoblasts

Connective tissue growth factor (CTGF/CCN2) is a cysteine rich, extracellular matrix protein that acts as an anabolic growth factor to regulate osteoblast differentiation and function. In osteoblasts, CTGF is induced by TGF-β1 where it acts as a downstream mediator of TGF-β1 induced matrix production. The molecular mechanisms that control CTGF induction by TGF-β1 in osteoblasts are not known. To assess the role of individual Smads in mediating the induction of CTGF by TGF-β1, we used specific Smad siRNAs to block Smad expression. These studies demonstrated that Smads 3 and 4, but not Smad 2, are required for TGF-β1 induced CTGF promoter activity and expression in osteoblasts. Since the activation of MAPKs (Erk, Jnk and p38) by TGF-β1 is cell type specific, we were interested in determining the role of individual MAPKs in TGF-β1 induction of CTGF promoter activity and expression. Using dominant negative (DN) mutants for Erk, Jnk and p38, we demonstrated that the expression of DN-Erk caused a significant inhibition of TGF-β1 induced CTGF promoter activity. In contrast, the expression of DN-p38 or DN-Jnk failed to inhibit activation of CTGF promoter activity. To confirm the vital role of Erk, we used the Erk inhibitor (PD98059) to block its activation, demonstrating that it prevented TGF-β1 activation of the CTGF promoter and up-regulation of CTGF expression in osteoblasts. Since Src can also act as a downstream signaling effector for TGF-β in some cell types, we determined its role in TGF-β1 induction of CTGF in osteoblasts. Treatment of osteoblasts with a Src family kinase inhibitor, PP2, or the expression of two independent kinase-dead Src mutant constructs caused significant inhibition of TGF-β1 induced CTGF promoter activity and expression. Additionally, blocking Src activation prevented Erk activation by TGF-β1 demonstrating a role for Src as an upstream mediator of Erk in regulating CTGF expression in osteoblasts. To investigate the involvement of the TGF-β1 response element (TRE) and the SMAD binding element (SBE) in CTGF induction, we cloned the rat CTGF proximal promoter (− 787 to + 1) containing the TRE and SBE motifs into a pGL3-Luciferase reporter construct. Using a combination of CTGF promoter deletion constructs and site-directed mutants, we demonstrated the unique requirement of both the TRE and SBE for CTGF induction by TGF-β1 in osteoblasts. Electro-mobility shift assays using specific probes containing the TRE, SBE or both showed TGF-β1 inducible complexes that can be ablated by mutation of the respective motif, confirming their requirement for TGF-β1 induced CTGF promoter activity. In conclusion, these studies demonstrate that CTGF induction by TGF-β1 in osteoblasts involves Smads 3 and 4, the Erk and Src signaling pathways, and requires both the TRE and SBE motifs in the CTGF proximal promoter.     

Calpain inhibition modulates glycogen synthase kinase 3β pathways in ischemic myocardium: A proteomic and mechanistic analysis

Background

Calpain inhibition has an enhancing effect on myocardial perfusion and improves myocardial density by inhibiting glycogen synthase kinase 3β (GSK-3β) and up-regulating downstream signaling pathways, including the insulin/PI3K and WNT/β-catenin pathways, in a pig model of chronic myocardial ischemia in the setting of metabolic syndrome.

Sodium butyrate inhibits the production of HMGB1 and attenuates severe burn plus delayed resuscitation-induced intestine injury via the p38 signaling pathway

BackgroundInflammatory response triggered by high mobility group box-1 (HMGB1) protein and oxidative stress play critical roles in the intestinal injury after severe burn. Sodium butyrate, a histone deacetylase inhibitor, has potential anti-inflammatory properties, inhibiting the expression of inflammatory mediators such as HMGB1 in diverse diseases. This study was designed to investigate the effects of sodium butyrate on severe burn plus delayed resuscitation-induced intestine injury, intestinal expressions of HMGB1 and intracellular adhesion molecule-1 (ICAM-1), oxidative stress, and signal transduction pathway changes in rats.Materials and methodsFifty-six Sprague-Dawley rats were divided into 3 groups randomly: (1) sham group, animals underwent sham burn; (2) burn group, rats subjected to full-thickness burns of 30% total body surface area (TBSA) and received 2 ml/kg/TBSA lactated Ringer solution for resuscitation at 6, 12, and 36 h after burn injury; (3) burn plus sodium butyrate (burn + SB) group, animals received burn injury and lactated Ringer solution with sodium butyrate inside for resuscitation in the same manner. Diamine oxidase (DAO) concentration in plasma was measured by enzyme-linked immunosorbent assay. Intestinal fatty acid binding protein (I-FABP) and ICAM-1 expressions in the intestine were analyzed by immunohistochemical method. HMGB1 and p38 mitogen-activated protein kinase (MAPK) expressions in the intestine tissues were examined by Western blot. The intestinal concentration of malondialdehyde (MDA) was also determined.ResultsIntestinal HMGB1 expression was significantly increased in burn group compared with sham group. Sodium butyrate administration significantly inhibited the HMGB1 expression in the intestine, decreased the DAO concentration in plasma, reduced the intestinal I-FABP expression, and improved the intestinal histologic changes induced by burn injury plus delayed resuscitation. Sodium butyrate treatment also markedly reduced the increase of intestinal ICAM-1 expression and MDA content, and inhibited p38 MAPK activity in the intestine of severely burned rats with delayed resuscitation.ConclusionsSodium butyrate inhibits HMGB1 expression which could be attributed to p38 MAPK signal transduction pathway and decreases intestinal inflammatory responses and oxidative stress, thus attenuates burn plus delayed resuscitation-induced intestine injury.     

Receptor activator of NF-κB (RANK)-mediated induction of metastatic spread and association with poor prognosis in renal cell carcinoma

Background

Inhibition of the receptor activator of NF-κB ligand (RANKL) has become a standard of care supportive treatment to prevent skeletal related events in cancer patients. Moreover, RANKL inhibition has been implicated with better survival outcome in lung cancer, while RANKL expression induces tumor progression and metastatic spread in vivo in breast cancer. Whether RANK/RANKL may have an impact on the pathogenesis of clear cell renal cell carcinoma (ccRCC) is currently unknown.

Steen solution protects pulmonary microvascular endothelial cells and preserves endothelial barrier after lipopolysaccharide-induced injury

ObjectivesAcute respiratory distress syndrome represents the devastating result of acute lung injury, with high mortality. Limited methods are available for rehabilitation of lungs affected by acute respiratory distress syndrome. Our laboratory has demonstrated rehabilitation of sepsis-injured lungs via normothermic ex vivo and in vivo perfusion with Steen solution (Steen). However, mechanisms responsible for the protective effects of Steen remain unclear. This study tests the hypothesis that Steen directly attenuates pulmonary endothelial barrier dysfunction and inflammation induced by lipopolysaccharide.MethodsPrimary pulmonary microvascular endothelial cells were exposed to lipopolysaccharide for 4 hours and then recovered for 8 hours in complete media (Media), Steen, or Steen followed by complete media (Steen/Media). Oxidative stress, chemokines, permeability, interendothelial junction proteins, and toll-like receptor 4-mediated pathways were assessed in pulmonary microvascular endothelial cells using standard methods.ResultsLipopolysaccharide treatment of pulmonary microvascular endothelial cells and recovery in Media significantly induced reactive oxygen species, lipid peroxidation, expression of chemokines (eg, chemokine [C-X-C motif] ligand 1 and C-C motif chemokine ligand 2) and cell adhesion molecules (P-selectin, E-selectin, and vascular cell adhesion molecule 1), permeability, neutrophil transmigration, p38 mitogen-activated protein kinase and nuclear factor kappa B signaling, and decreased expression of tight and adherens junction proteins (zonula occludens-1, zonula occludens-2, and vascular endothelial-cadherin). All of these inflammatory pathways were significantly attenuated after recovery of pulmonary microvascular endothelial cells in Steen or Steen/Media.ConclusionsSteen solution preserves pulmonary endothelial barrier function after lipopolysaccharide exposure by promoting an anti-inflammatory environment via attenuation of oxidative stress, toll-like receptor 4-mediated signaling, and conservation of interendothelial junctions. These protective mechanisms offer insight into the advancement of methods for in vivo lung perfusion with Steen for the treatment of severe acute respiratory distress syndrome.