内质网应激与心血管疾病

内质网(endoplasmic reticulum,ER)是细胞内蛋白质折叠、Ca2+储存和脂质生物合成的重要部位。氧化应激、缺血、Ca2+稳态的失衡都可以引起ER内非折叠蛋白的聚集,通过ER内的分子伴侣激活非折叠蛋白反应（unfolded protein response,UPR)可促进细胞的生存,但是过度ER应激(endoplasmic reticulum stress,ERS)可以诱导凋亡信号起始,通过线粒体依赖或者非线粒体依赖途径导致细胞死亡。因此,近年来ER被认为是决定细胞生存与凋亡的重要器官。最近研究提示,ERS在多种心血管疾病的病生理机制中起着重要作用,包括心功能不全及缺血性心脏疾病等。对这些疾病分子机制的进一步认识,将有助于开发新的靶向药物并治疗疾病。本文将对ERS和其与心血管疾病的关系进行综述。     

Endoplasmic reticulum stress and cardiovascular diseases

The endoplasmic reticulum (ER) serves several important functions, mainly post-translational modification, folding and assembly of newly synthesized secretary proteins, synthesizing lipids and cellular calcium storage. Various factors can disrupt ER homeostasis and disturb its functions, which leads to the accumulation of unfolded and misfolded proteins and to potential cellular dysfunction and pathological consequences, collectively termed ER stress. Recent progress suggests that ER stress plays a key role in the immune response, diabetes, tumor growth, and some neurodegenerative diseases. In particular, ER stress is involved in several processes of cardiovascular diseases, such as ischemia/reperfusion injury, cardiomyopathy, cardiac hypertrophy, heart failure, and atherosclerosis. Further research on the relation of ER stress to cardiovascular diseases will greatly enhance the understanding of these pathological processes and provide novel avenues to potential therapies.     

Autophagy as a therapeutic target in cardiovascular disease

The epidemic of heart failure continues apace, and development of novel therapies with clinical efficacy has lagged. Now, important insights into the molecular circuitry of cardiovascular autophagy have raised the prospect that this cellular pathway of protein quality control may be a target of clinical relevance. Whereas basal levels of autophagy are required for cell survival, excessive levels - or perhaps distinct forms of autophagic flux - contribute to disease pathogenesis. Our challenge will be to distinguish mechanisms that drive adaptive versus maladaptive autophagy and to manipulate those pathways for therapeutic gain. Recent evidence suggests this may be possible. Here, we review the fundamental biology of autophagy and its role in a variety of forms of cardiovascular disease. We discuss ways in which this evolutionarily conserved catabolic mechanism can be manipulated, discuss studies presently underway in heart disease, and provide our perspective on where this exciting field may lead in the future. This article is part of a special issue entitled ‘‘Key Signaling Molecules in Hypertrophy and Heart Failure.’’     

内质网应激与肝脏疾病研究进展

内质网应激是一种重要的细胞自我防御机制,内质网应激时,首先启动生存途径,但是持续的内质网应激将启动细胞凋亡途径.肝细胞内有大量的内质网,许多肝脏疾病均与内质网应激及其介导的细胞凋亡有关,如病毒性肝炎、酒精性肝病、非酒精性脂肪性肝病、药物性肝病、急性肝衰竭、肝癌等,针对内质网应激途径来进行凋亡保护或促进凋亡以寻找新靶点药物来治疗肝脏疾病在理论上成为可能.本文将从内质网应激反应的生存途径、凋亡途径,内质网应激及其介导的细胞凋亡在肝脏疾病发病机制中的作用以及在肝病干预治疗上的意义等方面进行综述.     

Rho kinase as a therapeutic target in cardiovascular disease

Rho kinase (ROCK) belongs to the AGC (PKA/PKG/PKC) family of serine/threonine kinases and is a major downstream effector of the small GTPase RhoA. ROCK plays central roles in the organization of the actin cytoskeleton and is involved in a wide range of fundamental cellular functions such as contraction, adhesion, migration, proliferation and gene expression. Two ROCK isoforms, ROCK1 and ROCK2, are assumed to be functionally redundant, based largely on the major common activators, the high degree of homology within the kinase domain and studies from overexpression with kinase constructs and chemical inhibitors (e.g., Y27632 and fasudil), which inhibit both ROCK1 and ROCK2. Extensive experimental and clinical studies support a critical role for the RhoA/ROCK pathway in the vascular bed in the pathogenesis of cardiovascular diseases, in which increased ROCK activity mediates vascular smooth muscle cell hypercontraction, endothelial dysfunction, inflammatory cell recruitment and vascular remodeling. Recent experimental studies, using ROCK inhibitors or genetic mouse models, indicate that the RhoA/ROCK pathway in myocardium contributes to cardiac remodeling induced by ischemic injury or persistent hypertrophic stress, thereby leading to cardiac decompensation and heart failure. This article, based on recent molecular, cellular and animal studies, focuses on the current understanding of ROCK signaling in cardiovascular diseases and in the pathogenesis of heart failure.     

Endoplasmic reticulum stress is a target for therapy in Waldenstrom macroglobulinemia

Waldenstrom macroglobulinemia (WM) is an incurable low-grade lymphoma characterized by bone marrow (BM) involvement of IgM secreting lymphoplasmacytic cells. The induction of unfolded protein response (UPR) genes ("physiologic" UPR) enables cells to differentiate into professional secretory cells capable of production of high amounts of endoplasmic reticulum (ER)-processed proteins, such as immunoglobulins. Ultimately, the initially cytoprotective UPR triggers an apoptotic cascade if ER stress is not corrected, called proapoptotic/terminal UPR. We show that WM cells inherently express the physiologic UPR machinery compared with normal BM cells, and that increased ER stress leads to proapoptotic/terminal UPR in WM cells. We therefore examined tunicamycin, ER stress inducer, for potential antitumor effects in WM. Tunicamycin induced significant cytotoxicity, apoptosis and cell-cycle arrest, and inhibited DNA synthesis in WM cell lines and primary BM CD19(+) cells from patients with WM with an inhibitory concentration (IC(50)) of 0.5 microg/mL to 1 microg/mL, but not in healthy donor cells. Importantly, coculture of WM cells in the context of the BM microenvironment did not inhibit tunicamycin-induced cytotoxicity. Finally, we demonstrate that ER stress inducer synergizes with other agents used in the treatment of WM. These preclinical studies provide a framework for further evaluation of ER stress inducing agents as therapeutic agents in WM.     

内质网应激与炎症性肠病

内质网(ER)是细胞内蛋白折叠修饰组装的场所,由于某种原因使错误折叠蛋白质或未折叠蛋白质在ER内聚集导致稳态失衡、生理功能发生紊乱称为内质网应激(ERS)。初期的ERS是一种代偿过程,能避免细胞损伤、恢复细胞功能,而ERS长时间持续或程度过强则会引起细胞凋亡,组织受损。近期研究发现,ERS在炎症性肠病的发生发展中起着重要作用。此文就近期ERS在炎症性肠病中作用的研究作一综述。     

Endoplasmic reticulum stress and inflammatory bowel disease

Endoplasmic reticulum (ER) stress arises from the accumulation of misfolded or unfolded proteins in the ER and elicits the unfolded protein response (UPR), an adaptive signalling pathway which aims at resolving ER stress. Genetic loci that confer risk for both forms of inflammatory bowel disease (IBD) include genes that are centrally involved in the UPR, including X-box binding protein-1 (XBP1), anterior gradient protein-2 (AGR2) and orosomucoid-1-like 3 (ORMDL3). The intestinal epithelium, in particular mucin-secreting goblet and antimicrobial peptide-secreting Paneth cells appear particularly sensitive towards disturbances of the UPR. Supportive of this view are mice with a genetic deletion of Xbp1 specifically in the intestinal epithelium, which develop spontaneous intestinal inflammation histologically remarkably similar to human IBD. Apart from such primary genetic factors that determine the threshold of tolerable ER stress within the epithelium, secondary factors emanating from the environment might intersect with the UPR as well. These secondary factors might include microbial products, inflammatory mediators per se, hypoxia and glucose deprivation, pharmacological agents, and many others. Interaction of such secondary factors in a genetically susceptible host might provide the basis for intestinal inflammation and might provide a framework to investigate gene-environment interactions in human IBD, whereby a normally homeostatic adaptive response (i.e. the UPR) transforms into a potent pathomechanism of intestinal inflammation in the context of unresolved (i.e. unresolvable) ER stress.     

内质网应激与酒精性肝病

在酒精性肝病的发病机制中,内质网应激作为新的关注点已经进入人们的视野。内质网应激是内质网内未折叠或错误折叠蛋白积聚所致,适宜的应激有利于细胞内环境的恢复,然而严重而持久的内质网应激将导致细胞凋亡。肝细胞具有高度发达的内质网,是对内质网应激最敏感的细胞之一,目前的研究也表明在细胞和动物模型中,内质网应激参与了酒精性肝病的发病过程。本文就内质网应激在酒精性肝病中的作用作一综述。     

Endothelin as a therapeutic target in the treatment of cardiovascular disease

Endothelins, a family of peptides derived from the vascular endothelium and smooth muscle cells possess vasoconstrictor and mitogenic properties. By acting predominantly in a paracrine fashion, these peptides activate specific receptors and have protean effects in normal and diseased organ systems. The wide distribution of these receptors in various tissues mediate the multiplicity of physiologic actions attributed to endothelins. Much of our understanding about endothelins has come from the development of an array of receptor-specific and mixed receptor antagonists. Based on the promising results from animal studies, active research and drug development programs are under way to investigate the clinical potential of endothelin antagonism for treatment of cardiovascular disease.     

Vascular inflammation as a therapeutic target for prevention of cardiovascular disease

Conclusions This is a dynamic and exciting time in cardiovascular medicine. Recent advances in understanding of the biologic, cellular, and molecular mechanisms involved in atherosclerosis and its acute complications have led to the identification of multiple new therapeutic targets. Inflammation is a fundamental contributor to atherosclerosis and its complications. Elevated inflammatory markers in prospective trials have been associated with increased cardiovascular risk among healthy individuals as well as those at higher risk because of the presence of other risk factors or known coronary disease. Some, but not all, standard therapies for prevention of cardiovascular disease have anti-inflammatory effects, effects that might contribute importantly to their observed clinical benefits. Specific targeting of the inflammatory process may result in improved and more effective treatments for control and prevention of cardiovascular disease. However, ultimate strategies that target inflammation will have to be developed cautiously because interference with the inflammatory process may have harmful, as well as beneficial, effects. At the present time, primary prevention and treatment of those risk factors known to initiate and propagate the disease (hypercholesterolemia, hypertension, diabetes, and smoking) should remain the focus of preventive cardiovascular strategies. However promising, before specific therapies targeting the inflammatory process can become a mainstay of preventive cardiovascular strategies, additional prospective, randomized trials are necessary to test directly their benefits and safety.     

内质网应激与非酒精性脂肪性肝病

近年来对内质网应激在代谢综合征等方面的作用研究十分广泛,而非酒精性脂肪性肝病的发病机制与代谢综合征密切相关,现就内质网应激在非酒精性脂肪性肝病发生、发展中的作用和意义作一综述。     

The P2Y 12 receptor as a therapeutic target in cardiovascular disease

Coronary thrombosis complicating rupture of atherosclerotic plaque is the predominant cause of acute coronary syndromes and platelets play a crucial role in this thrombus formation. Whilst aspirin has been successful in reducing cardiovascular morbidity and mortality, appreciation of its limited antiplatelet effects has stimulated the search for more effective antiplatelet agents. The thienopyridines, ticlopidine and clopidogrel, act, via metabolites, on the platelet ADP receptor subtype now designated P2Y 12 (formerly P 2T , P2T AC , P2Y ADP or P2Y cyc ) and these agents have proven clinical efficacy. Analogues of the natural P2Y 12 receptor antagonist ATP have been developed that act directly on the receptor and have a rapid onset of action. One such antagonist, AR-C69931MX, is being developed for clinical use. AR-C69931MX is a potent antagonist of ADPinduced platelet activation, aggregation and secretion and also antagonises platelet responses, including procoagulant activity, induced by all other agonists in view of the central role of the P2Y 12 receptor in amplifying platelet responses. Phase II studies of intravenous AR-C69931MX in patients with acute coronary syndromes show that this agent has a rapid onset of action, rapidly achieving steady-state inhibition of platelet aggregation, with a half-life of only a few minutes. AR-C69931MX appears to be safe and well tolerated as adjunctive therapy in these patients, and more effective inhibition of platelet function is achieved than with clopidogrel. Orally active ATP analogues are also being developed that may be more effective than clopidogrel. Limitations of platelet glycoprotein IIb/IIIa antagonists leave scope for development of alternative antiplatelet agents.     

Endoplasmic reticulum stress in the heart

Over the last decade, it has become clear that the accumulation of misfolded proteins contributes to a number of neurodegenerative, immune, and endocrine pathologies, as well as other age-related illnesses. Recent interest has focused on the possibility that the accumulation of misfolded proteins can also contribute to vascular and cardiac diseases. In large part, the misfolding of proteins takes place during synthesis on free ribosomes in the cytoplasm or on endoplasmic reticulum ribosomes. In fact, even under optimal conditions, approximately 30% of all newly synthesized proteins are rapidly degraded, most likely because of improper folding. Accordingly, stresses that perturb the folding of proteins during or soon after synthesis can lead to the accumulation of misfolded proteins and to potential cellular dysfunction and pathological consequences. To avert such outcomes, cells have developed elaborate protein quality-control systems for detecting misfolded proteins and making appropriate adjustments to the machinery responsible for protein synthesis and/or degradation. Important contributors to protein quality control include cytosolic and organelle-targeted molecular chaperones, which help fold and stabilize proteins from unfolding, and the ubiquitin proteasome system, which degrades terminally misfolded proteins. Both of these systems play important roles in cardiovascular biology. The focus of this review is the endoplasmic reticulum stress response, a protein quality-control and signal-transduction system that has not been well studied in the context of cardiovascular biology but that could be important for vascular and cardiac health and disease.     

Endoplasmic reticulum stress and inflammation

Endoplasmic reticulum (ER) stress due to the presence of misfolded or unfolded proteins in the ER invokes a fundamental biological response, termed the unfolded protein response (UPR). The UPR is orchestrated by three main proximal effectors, of which the IRE1/XBP1 pathway represents the evolutionarily most conserved one. Due to its high secretory burden, the intestinal epithelium is highly susceptible to perturbations in the UPR as has been revealed by functional investigations such as in mice that lack Xbp1 expression, specifically in the intestinal epithelial cells. Genetic studies have revealed several ER stress/UPR-associated genes, including XBP1, ORMDL3, AGR2 and MUC19 as risk factors for IBD, and specific functional, rare variants have been described for XBP1. Xbp1(Δ)(IEC) mice spontaneously develop small intestinal enteritis with crypt abscesses reminiscent of human IBD, while Agr2(-/-) mice develop granulomatous ileocolitis. Mechanistic studies into Xbp1(Δ)(IEC) mice revealed a major effect on Paneth cells associated with alterations in host-microbe interactions in the intestine, and the activation of key proinflammatory pathways in the host directly associated with unresolved ER stress and hypomorphic Xbp1 function. Remarkably, the intestinal epithelium of IBD patients commonly exhibits evidence of marked ER stress, which cannot easily be attributed to these genetic risk factors alone and indicates that the paradigm of ER stress-related inflammation might be both a primary originator as well as a potent perpetuator of intestinal inflammation in IBD.     

Lipoprotein(a) as a key target in combined therapeutic approaches for cardiovascular disease

Introduction and ObjectiveLipoprotein(a) [Lp(a)] is an independent cardiovascular risk factor but is closely associated with other similar risk factors that are manageable with appropriate treatment and guidance. We aimed to study the impact of using combined therapy for managing Lp(a) levels in patients at high cardiovascular risk but without major adverse cardiovascular events, in primary prevention.MethodsWe conducted a retrospective observational study in 516 patients randomly selected from a group of 1677 patients who attended cardiovascular risk and metabolism consultations between 1995 and 2015. The disorders observed and therapies used were classified into nosological and pharmacological groups, respectively. Cardiovascular risk was calculated based on the Framingham risk score, the European Society of Cardiology's SCORE and the American College of Cardiology's ASCVD Risk Estimator, and changes in patients’ lifestyle were assessed.ResultsSignificant differences (p<0.001) were found in almost all metabolic variables, except fasting insulin and C-peptide. Lp(a) levels were also significantly reduced (p<0.001). Carotid intima-media thickness improved, decreasing from 2.90 mm to 1.40 mm; however, there was no reduction in the number of cases of vascular stenosis. Of patients with hepatic steatosis (85.5%), 40.7% presented hepatomegaly, but liver function was only altered in a few patients (14.5%). Lipid-lowering therapy, especially statins, significantly decreased Lp(a), benefiting from synergy with other treatments.ConclusionsLp(a) is a key overall indicator of vascular risk and should be considered a therapeutic target. Besides a healthy lifestyle, primary prevention should include combined drug therapies to address all cardiovascular risk factors and to delay the atherosclerotic process.     

内质网应激与肝细胞凋亡

内质网(endoplasmic reticulum,ER)是一种重要的真核细胞器,由于各种原因引起的内质网中出现错误折叠与未折叠蛋白在腔内聚集以及Ca~(2 )平衡紊乱的状态,称为内质网应激(ER stress,ERS).细胞凋亡(apoptosis),又称为程序性细胞死亡(programmed cell death,PCD),是受细胞外微环境和细胞内基因调控的一种细胞主动性死亡方式,他是机体用来去除衰老、有害、无用及异型细胞的一种重要机制,是确保机体正常发育、维持机体正常生理过程所必须的.肝细胞凋亡是造成肝脏损伤和肝脏疾病最基本的中心环节.既往研究认为肝细胞凋亡主要通过两条信号通路介导,即死亡受体通路和线粒体依赖性的细胞凋亡通路.但近来发现ERS亦介导肝细胞发生凋亡,本文主要讨论ERS途径所致肝细胞凋亡的机制.