C-reactive protein promotes atherosclerosis by increasing LDL transcytosis across endothelial cells

Background and Purpose

The retention of plasma low-density lipoprotein (LDL) particles in subendothelial space following transcytosis across the endothelium is the initial step of atherosclerosis. Whether or not C-reactive protein (CRP) can directly affect the transcytosis of LDL is not clear. Here we have examined the effect of CRP on transcytosis of LDL across endothelial cells and have explored the underlying mechanisms.

Experimental Approach

Effects of CRP on transcytosis of FITC-labelled LDL were examined with human umbilical vein endothelial cells and venous rings in vitro and, in vivo, ApoE^-/- mice. Laser scanning confocal microscopy, immunohistochemistry and Oil Red O staining were used to assay LDL.

Key Results

CRP increased transcytosis of LDL. An NADPH oxidase inhibitor, diphenylene iodonium, and the reducing agent, dithiothreitol partly or completely blocked CRP-stimulated increase of LDL transcytosis. The PKC inhibitor, bisindolylmaleimide I and the Src kinase inhibitor, PP2, blocked the trafficking of the molecules responsible for transcytosis. Confocal imaging analysis revealed that CRP stimulated LDL uptake by endothelial cells and vessel walls. In ApoE^-/- mice, CRP significantly promoted early changes of atherosclerosis, which were blocked by inhibitors of transcytosis.

Conclusions and Implications

CRP promoted atherosclerosis by directly increasing the transcytosis of LDL across endothelial cells and increasing LDL retention in vascular walls. These actions of CRP were associated with generation of reactive oxygen species, activation of PKC and Src, and translocation of caveolar or soluble forms of the N-ethylmaleimide-sensitive factor attachment protein.     

Isoproterenol disperses distribution of NADPH oxidase,MMP-9, and pPKCε in the heart,which are mitigated by endothelin receptor antagonist CPU0213

Aim： Spatial dispersion of bioactive substances in the myocardium could serve as pathological basis for arrhythmogenesis and cardiac impairment by β-adrenoceptor stimulation. We hypothesized that dispersed NADPH oxidase, protein kinase Cε （PKCε）, early response gene （ERG）, and matrix metalloproteinase 9 （MMP-9） across the heart by isoproterenol （ISO） medication might be mediated by the endothelin （ET） - ROS pathway. We aimed to verify if ISO induced spatially heterogeneous distribution of pPKCε, NAPDH oxidase, MMP-9 and ERG could be mitigated by either an ET receptor antagonist CPU0213 or iNOS inhibitor aminoguanidine. Methods：Rats were treated with ISO （1 mg/kg sc） for 10 days, and drug interventions （mg/kg） either CPU0213 （30 sc） or aminoguanidine （100 ip） were administered on days 8-10. Expression of NADPH oxidase, MMP-9, ERG, and PKCε in the left and right ventricle （LV, RV） and septum （S） were measured separately. Results： Ventricular hypertrophy was found in the LV, S, and RV, in association with dispersed QTc and oxidative stress in ISO-treated rats. mRNA and protein expression of MMP-9, PKCε, NADPH oxidase and ERG in the LV, S, and RV were obviously dispersed, with augmented expression mainly in the LV and S. Dispersed parameters were re-harmonized by either CPU0213, or aminoguanidine. Conclusion： We found at the first time that ISO-induced dispersed distribution of pPKCε, NADPH oxidase, MMP-9, and ERG in the LV, S, and RV of the heart, which were suppressed by either CPU0213 or aminoguanidine. It indicates that the ET-ROS pathway plays a role in the dispersed distribution of bioactive substances following sustained β-receptor stimulation.     

姜黄素对氯化铝染毒的NG108 - 15细胞凋亡及PKC - NMDAR通路表达的影响

目的 探讨姜黄素对氯化铝染毒所致NG108 - 15细胞凋亡的影响及其机制,为铝致学习记忆损伤的治疗提供参考。方法 取对数生长期NG108 - 15细胞,随机分为空白对照组、DMSO组（溶剂对照）、姜黄素组（16 μmol/L姜黄素）、铝组（160 mg/L氯化铝染毒 ）、铝+姜黄素组（160 mg/L氯化铝染毒24 h后,给予16 μmol/L姜黄素处理24 h）。收集各组细胞,采用吖啶橙/嗅化乙锭（AO/EB）双荧光染色观察细胞凋亡形态,计数凋亡细胞数并计算凋亡率;流式细胞术检测细胞凋亡率, qRT - PCR检测细胞中PKC、NMDAR1、NMDAR2B 的mRNA表达水平,western blot检测细胞中凋亡相关蛋白（caspase3、Bax）和PKC、NMDAR1、NMDAR2B的蛋白表达水平。多组间均数的比较采用单因素方差分析（one - way ANOVA）,组间两样本均数的比较采用LSD法。结果 与空白对照组相比,铝染毒组的caspase3、Bax蛋白表达水平升高（t = - 5.547、 - 4.948,P＜0.001）,PKC、NMDAR1、NMDAR2B的mRNA（t = 4.926,P = 0.003;t = 6.330,P＜0.001;t = 4.224,P = 0.019）和蛋白（t = 20.638,P＜0.001;t = 4.509,P＜0.001;t = 17.388,P = 0.002）表达水平降低, AO/EB染色和流式细胞术结果均表明细胞凋亡率升高（t = - 5.153、 - 7.390,P＜0.001）;加入姜黄素处理后,与铝染毒组相比,铝+姜黄素组的caspase3、Bax蛋白表达水平降低（t = 2.930,P = 0.006;t = 4.907,P＜0.001）,PKC、NMDAR1、NMDAR2B 的mRNA（t = - 10.337、 - 6.621、 - 6.847,P＜0.001）和蛋白（t = - 30.551、 - 7.451、 - 26.294,P＜0.001）表达水平升高,AO/EB染色和流式细胞术结果均表明细胞凋亡率降低（t = 2.707,P = 0.01;t = 4.632,P＜0.001）。结论 上调PKC - NMDAR信号通路表达,可能是姜黄素减轻氯化铝染毒所致NG108 - 15细胞凋亡的机制之一。     

PKC-ERK1/2通路在臭氧预处理减轻大鼠肝缺血再灌注损伤的作用

目的 探讨PKC介导的ERK1/2信号通路在臭氧（ozone,O₃）预处理大鼠肝缺血再灌注中的作用。方法 60只大鼠随机分成6组：对照组、缺血再灌注组、O₃预处理组、O₃预处理+ERK抑制剂组（O₃+PD98059组）、O₃预处理+PKC抑制剂组（O₃+CHE组）、缺血再灌注+PKC激活剂组（IR+PMA组）。除对照组外,其余各组均进行肝缺血再灌注手术。O₃相关组予O₃预处理,调节剂组予相应的调节剂。分别检测各组的血清中丙氨酸氨基转移酶、天冬氨酸氨基转氨酶水平,进行病理学观察,Western blotting检测肝组织中的热休克蛋白70（heat shock protein 70,HSP70）、蛋白激酶C（protein kinase C,PKC）和细胞外调节蛋白激酶1/2（extracellular regulated protein kinases,ERK1/2）的表达水平。结果 与对照组相比,缺血再灌注组肝组织细胞损伤明显加重（P<0.05）,肝组织中PKC、ERK1/2的磷酸化和HSP70的表达水平明显升高（P<0.05）。与缺血再灌注组相比,O₃相关组肝组织细胞损伤明显减轻（P<0.05）,肝组织中PKC、ERK1/2的磷酸化和HSP70的表达水平明显升高（P<0.05）。与O₃预处理组相比,当使用PKC和ERK1/2抑制剂后,肝组织细胞损伤明显加重（P<0.05）,肝组织中PKC、ERK1/2的磷酸化和HSP70的表达水平明显降低（P<0.05）。结论 O₃氧化预处理可通过激活PKC介导的ERK1/2信号通路,使HSP70的表达水平明显增加,使大鼠肝脏缺血再灌注损伤明显减轻。     

Status and prospect of current inotropic agents

Critical reassessment of established inotropic drugs such as the phosphodiesterase inhibitors and the digitalis glycosides has reaffirmed the need for novel cardiotonic agents that will not only beneficially affect the haemodynamic and functional impairment of patients with overt congestive heart failure, but also prevent its clinical manifestation and reduce the high mortality. None of the drugs examined in these directions - calcium sensitisers, β-receptor blockers, sodium channel modulators, digitalis derivatives - have been shown to achieve these goals. The research on endogenous digitalis did not, as was hoped, reveal a general strategy for improving the therapeutic index of cardiac glycosides. The proof that Na+/K+-transporting ATPase of cardiac muscle is the molecular point of attack (receptor) for the inotropic and toxic effects of digitalis-like acting C/D-cis and C/D-trans steroids revealed the cyclopentano-perhydrophenanthrene nucleus as their common pharmacophoric lead structure. This has opened a wide field for lead development in the direction of derivatives that favourably discriminate between the inotropy-linked α1-isoform and the toxicity-linked α3-isoform of Na+/K+-ATPase as the basis for the design of inotropic agents with high therapeutic margin.     

加味丹参饮预处理对乳鼠缺氧/复氧心肌细胞的延迟保护作用及对蛋白激酶C的影响

目的观察加味丹参饮预处理对乳鼠缺氧/复氧心肌细胞的延迟保护作用及对蛋白激酶C(PKC)的影响。方法将培养72h的乳鼠心肌细胞随机分为6组,空白组正常培养;血清对照组加50%大鼠血清培养;含药血清组加50%含加味丹参饮的药物血清培养;缺氧/复氧组予缺氧再给氧。缺氧预处理组、加味丹参饮预处理组先给予缺氧预处理和加味丹参饮预处理,24h后再予缺氧再给氧。结果加味丹参饮预处理24h后可防止缺氧/复氧心肌细胞存活率的降低,防止乳酸脱氢酶(LDH)、肌酸激酶(CK)活性的升高(P<0.01),提高蛋白激酶C活性(P<0.01)。结论加味丹参饮预处理具有延迟保护作用,其机制与激发细胞内PKC信号转导通路有关。     

PKCδ在游离脂肪酸诱导内皮细胞凋亡过程中的作用研究

目的：探讨蛋白激酶 Cδ（PKCδ）在游离脂肪酸（FFAs）诱导内皮细胞凋亡过程中的作用。方法培养人脐静脉内皮细胞,分别给予不同浓度的 FFAs 刺激,转染 PKCδsiRNA 以抑制 PKCδ的表达。使用比色法检测细胞的增殖情况,采用定量流式细胞术测定细胞凋亡情况,免疫印迹法检测 PKCδ蛋白及磷酸化蛋白的表达水平。结果在人脐静脉内皮细胞内 FFAs 可产生多种效应,包括浓度依赖性的抑制细胞增殖、诱导细胞凋亡、增加 PKCδ的表达和磷酸化等。抑制 PKCδmRNA 的表达可导致 FFAs 诱导细胞凋亡减少。结论PKCδ可能介导内皮细胞中 FFAs 诱导的细胞凋亡。     

Different mechanisms of homologous and heterologous μ-opioid receptor phosphorylation

The efficiency of μ-opioid receptor signalling is tightly regulated and ultimately limited by the coordinated phosphorylation of intracellular serine and threonine residues. Here, we review and discuss recent progress in the generation and application of phosphosite-specific μ-opioid receptor antibodies, which have proved to be excellent tools for monitoring the spatial and temporal dynamics of receptor phosphorylation and dephosphorylation. Agonist-induced phosphorylation of μ-opioid receptors occurs at a conserved 10 residue sequence ³⁷⁰TREHPSTANT³⁷⁹ in the receptor''s carboxyl-terminal cytoplasmic tail. Diverse opioids induce receptor phosphorylation at S375, present in the middle of this sequence, but only high-efficacy opioids have the ability to drive higher order phosphorylation on flanking residues (T370, T376 and T379). S375 is the initiating residue in a hierarchical phosphorylation cascade. In contrast, agonist-independent heterologous μ-opioid receptor phosphorylation occurs primarily at T370. The combination of phosphosite-specific antibodies and siRNA knockdown screening also facilitated the identification of relevant kinases and phosphatases. In fact, morphine induces a selective S375 phosphorylation that is predominantly catalysed by GPCR kinase 5 (GRK5), whereas multisite phosphorylation induced by high-efficacy opioids specifically requires GRK2/3. By contrast, T370 phosphorylation stimulated by phorbol esters or heterologous activation of G_q-coupled receptors is mediated by PKCα. Rapid μ-opioid receptor dephosphorylation occurs at or near the plasma membrane and is catalysed by protein phosphatase 1γ (PP1γ). These findings suggest that there are distinct phosphorylation motifs for homologous and heterologous regulation of μ-opioid receptor phosphorylation. However, it remains to be seen to what extent different μ-opioid receptor phosphorylation patterns contribute to the development of tolerance and dependence in vivo.

LINKED ARTICLES

This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2     

条件培养液预处理对乳鼠心肌细胞缺氧复氧损伤的影响及其机理探讨

目的观察短暂缺氧条件培养液对乳鼠心肌细胞缺氧复氧损伤的影响，并探讨其作用机理。方法采用乳鼠心肌细胞缺氧／复氧（A／R）损伤模型。用短暂缺氧条件培养液进行预处理。结果条件培养液预处理能够提高A／R损伤后心肌细胞存活率（7638±4．12vsA／R组56．87±3．17％，P＜0．01），减少细胞MDA产生（0．91±0．05VSA／R组1．61±0．06nmol／mg·pr，P＜0．01），减少LDH漏出（35．12±845vsA／R组56．47±9．15U／L，P＜0．01）及细胞内蛋白漏出（0．32±0．04vsA／R组0．43±0．07，P＜0．01）。PKC抑制剂（H_7）完全阻断条件培养液预处理的上述保护作用。结论条件培养液对乳鼠心肌细胞的缺氧复氧损伤具有保护作用，其机理是通过PKC介导的。     

细胞外信号调节激酶在糖尿病大鼠肺病变中的作用

目的　观测糖尿病大鼠肺组织的病理改变及蛋白激酶C、胞外调节蛋白激酶活性的变化 ,探讨细胞信号传导系统在糖尿病大鼠肺病变中的作用。方法　制作糖尿病大鼠模型 ,4w后应用透射电镜观察大鼠肺组织病理改变 ,采用改良的Takay法测定蛋白激酶C活性 ,同位素法及蛋白质免疫印迹分析方法检测胞外调节蛋白激酶在糖尿病大鼠肺组织表达的变化。结果　糖尿病大鼠 4w肺组织病理改变为毛细血管基底膜及Ⅱ型肺泡上皮细胞基底膜不同程度增厚 ,肺间质胶原成份增多 ,蛋白激酶C、胞外调节蛋白激酶在肺组织活性增强。结论　链脲菌素糖尿病大鼠肺组织高糖环境下细胞内信号传导系统被激活 ,可能参与了糖尿病肺部并发症的发生和发展