Protein C and S and inflammation in sickle cell disease

Reduced activity of naturally occurring anticoagulants (NOAC) protein C and protein S may contribute to vaso-occlusion in sickle cell disease (SCD). We studied whether protein C and S are related to clinical vaso-occlusion, hematological markers of disease severity (hemoglobin levels, leukocyte counts, and percentage of fetal hemoglobin), and inflammation in SCD. Protein C activity, protein S (free and total) antigen, endothelial activation markers (soluble vascular cell adhesion molecule-1 [sVCAM-1], von Willebrand antigen [vWF]), and high sensitive C-reactive protein (hsCRP) levels were measured in 30 HbSS and 20 HbSC patients and in race-matched HbAA controls. NOAC levels were reduced in patients, and endothelial activation markers and hsCRP were elevated (except vWF in HbSC patients). Protein C activity and vWF levels were lower in HbSC patients who experienced painful crises compared to HbSC patients who were clinically asymptomatic. No other differences were observed between patients who did and did not experience vaso-occlusive events (painful crises, stroke, acute chest syndromes) or leg ulcers. A significant positive correlation between total protein S with hemoglobin levels and a significant negative correlation between total and free protein S and sVCAM-1 were detected in HbSS patients. Except perhaps for protein C in relation to painful crises in HbSC patients, these markers were not associated with the occurrence of clinical events. The protein S, hemoglobin, and sVCAM-1 associations may suggest decreased endothelial protein S production due to the more severe endothelial perturbation in HbSS patients with lower hemoglobin levels.     

Microvascular display of xanthine oxidase and NADPH oxidase in the spontaneously hypertensive rat

OBJECTIVE: Oxygen free radical production in hypertension may be associated with elevated arteriolar tone and organ injury. Previous results suggest an enhanced level of oxygen free radical formation in microvascular endothelium and in circulating neutrophils associated with xanthine oxidase activity in the spontaneously hypertensive rats (SHR) compared with their normotensive controls, the Wistar Kyoto rats (WKY). The aim of this study was to gain more detailed understanding of where oxidative enzymes are located in the microcirculation. METHODS: An approach was developed to delineate the cellular distribution of two selected oxidative enzymes, xanthine oxidase and nicotinamide adenine dinucleotide phosphate (NADPH) dependent oxidase (protein 67-kDa fraction). Immunolabeling with peroxidase substrate was utilized, which permits full delineation of the primary antibody in all microvascular structures of the mesentery. RESULTS: Xanthine oxidase is present in the endothelium of all segments of the microcirculation, in mast cells, and in parenchymal cells of the mesentery. NADPH oxidase can be detected in the endothelium, leukocytes, and mast cells and with lower levels in parenchymal cells. The mesentery of WKY and SHR has similar enzyme distributions with enhancements on the arteriolar and venular side of the microcirculation that coincide with the sites of enhanced free radical production recently reported. Immune label measurements under standardized conditions indicate that both enzymes are significantly enhanced in the SHR. Adrenalectomy, which serves to reduce the blood pressure and free radical production of the SHR to normotensive levels, leads to a reduction of NADPH and xanthine oxidase to normotensive levels, while supplementation of adrenalectomized SHR with dexamethasone significantly increases the oxidase expression in several parts of the microcirculation to levels above the WKY rats. CONCLUSION: The results indicate that enhanced expression of NADPH and xanthine oxidase in the SHR depends on an adrenal pathway that is detectable in the arteriolar and venular network at high and low pressure regions of the circulation.     

Activation-Dependent Isolation and Culture of Murine Pulmonary Microvascular Endothelium

Objective: Establish a reproducible method for the isolation and cultivation of murine pulmonary microvascular endothelium. To this end, we exploited the localized pattern of microvascular endothelial activation induced in vivo by inflammatory stimuli to isolate a subpopulation of endothelium for in vitro study. Methods: Immunohistochemical analyses of the pulmonary vasculature of mice treated systemically with gram-negative bacterial endotoxin (LPS) demonstrated selective expression of VCAM-1 (CD106) in the endothelial lining of small collecting veins, venules, septal capillaries, and, infrequently, small arteries, which was not observed in control mice. Single cell suspensions prepared by enzymatic dissociation of peripheral lobular tissues dissected from the lungs of LPS-stimulated mice were incubated with a phycoerythrin-conjugated antimouse VCAM-1 monoclonal antibody (MK 1.91). Cells expressing this antigen were isolated by sterile fluorescence-activated cell sorting (FACS). Positive cell populations were collected and cultured for 1–2 weeks. When confluent, these primary cultures were further FACS enriched for endothelium, positively selecting for cells incorporating a fluorescent derivative of acetylated low density lipoprotein (Di-I-Ac-LDL). Results: The resulting population of cells (mouse lung endothelial cells, MLEC) were uniformly positive for the endothelial markers von Willebrand factor, thrombomodulin, and Dil-Ac-LDL uptake. MLEC readily formed tube-like structures when cultured on Matrigel and spontaneously demonstrated a sprouting phenotype on fibronectin or collagen matrices. MLEC retained responsiveness to cytokines (IL-1α, IL-1β, TNFα, IFNγ) up to at least eight passages from primary culture and demonstrated upregulation of E-selectin (CD62E) and P-selectin (CD62P) mRNA as early as 2 hr after LPS stimulation. Characteristic temporal expression patterns of cell surface E-selectin (maximal at 4 hr and declining toward baseline by 24 hr), VCAM-1 (maximal at 6–8 hr and remaining elevated for 24–48 hr), and ICAM-1 (maximal at 6–8 hr and maintained at 24 hr) were observed when cultured MLEC were treated with recombinant murine TNFα or recombinant human (rh) IL-1α or rhIL-1β. The rolling, adhesion, and transmigration of human polymorphonuclear leukocytes was markedly increased on cytokine-activated MLEC monolayers under defined flow conditions. Conclusion: The strategy of activation-dependent isolation allows for the reproducible selection of a specific subset of microvascular endothelial cells for in vitro     

Elevated IL-8 levels during sickle cell crisis

Abstract: The vaso-occlusive process (VOC) in sickle cell disease is of a complex nature. It involves intricate interactions between sickle red blood cells, endothelium and probably also leukocytes. As these interactions are regulated by cytokines, we analyzed the role of the potent neutrophil chemokine IL-8 by measuring serum levels in sickle cell patients during sickle cell crisis. These results were compared to nonsymptomatics and healthy controls. In patients having a vaso-occlusive crisis both HbSS and HbSC patients showed significantly enhanced serum IL-8 levels compared to healthy controls. Several of these patients showed extremely elevated serum IL-8 levels which were independent of the crisis inducing factor. Furthermore, a sickle cell patient with VOC as a complication of rhGM-CSF treatment similarly showed high IL-8 serum levels at crisis onset. Nonsymptomatic sickle cell patients serum IL-8 levels were comparable to healthy controls. These results implicate a role for IL-8 at or during (the initiation of) sickle cell crisis.     

Increased aortic endothelial cell death and enhanced transendothelial macromolecular transport in streptozotocin-diabetic rats

Summary Hypertension, cigarette smoking and diabetes mellitus are well-known risk factors for atherosclerosis and coronary heart disease. Repeated endothelial cell injury and increased lipid entry have been suggested as initiating events in atherogenesis. Our previous studies have demonstrated that the frequency of endothelial cell death and associated endothelial permeability were significantly increased in the aorta of spontaneously hypertensive rats and chronic oral nicotine-treated rats. In the present investigation, we examined the hypothesis that diabetes also increases the frequency of arterial endothelial cell death and hence transendothelial macromolecular transport, which may have some implications in increasing lipid entry and thus accelerating atherogenesis. Diabetes was induced in 15 male Sprague-Dawley rats by intraperitoneal injection of 60 mg streptozotocin per kg body weight. The duration of diabetes was 6 weeks. A group of 15 age-matched rats, injected only with the buffer and maintained over the same time period, served. as the controls. In en face preparations of the thoracic aorta, IgG-containing dead endothelial cells were identified by an indirect immunoperoxidase method, and endothelial leakage to Evans blue-albumin complexes was quantified by fluorescence microscopy. Diabetic rats, compared to control rats, had significantly higher values for the frequency of endothelial cell death (0.77±0.10% vs 0.38±0.04%;p<0.005 by two-tailed, unpaired Student'st-test) and the number density of Evans blue-albumin leaky foci (4.33±0.48/mm² vs 2.99±0.38/mm²;p<0.05 by two-tailed, unpairedt-test) in the aorta. It is concluded that, similar to the situations in hypertension and nicotine consumption, the observed increase in the frequency of endothelial cell death and macromolecular permeability to large molecules in the aorta in streptozotocin-induced diabetic rats suggest that these changes may contribute to accelerated atherogenesis in diabetes.     

Synchronized renal tubular cell death involves ferroptosis

Receptor-interacting protein kinase 3 (RIPK3)-mediated necroptosis is thought to be the pathophysiologically predominant pathway that leads to regulated necrosis of parenchymal cells in ischemia–reperfusion injury (IRI), and loss of either Fas-associated protein with death domain (FADD) or caspase-8 is known to sensitize tissues to undergo spontaneous necroptosis. Here, we demonstrate that renal tubules do not undergo sensitization to necroptosis upon genetic ablation of either FADD or caspase-8 and that the RIPK1 inhibitor necrostatin-1 (Nec-1) does not protect freshly isolated tubules from hypoxic injury. In contrast, iron-dependent ferroptosis directly causes synchronized necrosis of renal tubules, as demonstrated by intravital microscopy in models of IRI and oxalate crystal-induced acute kidney injury. To suppress ferroptosis in vivo, we generated a novel third-generation ferrostatin (termed 16-86), which we demonstrate to be more stable, to metabolism and plasma, and more potent, compared with the first-in-class compound ferrostatin-1 (Fer-1). Even in conditions with extraordinarily severe IRI, 16-86 exerts strong protection to an extent which has not previously allowed survival in any murine setting. In addition, 16-86 further potentiates the strong protective effect on IRI mediated by combination therapy with necrostatins and compounds that inhibit mitochondrial permeability transition. Renal tubules thus represent a tissue that is not sensitized to necroptosis by loss of FADD or caspase-8. Finally, ferroptosis mediates postischemic and toxic renal necrosis, which may be therapeutically targeted by ferrostatins and by combination therapy.Regulated cell death may result from immunologically silent apoptosis or from immunogenic necrosis (1–3). Necroptosis, the best-characterized pathway of regulated necrosis, involves activation of receptor-interacting protein kinase 3 (RIPK3)-mediated phosphorylation of mixed lineage kinase domain-like protein (pMLKL) and subsequent plasma-membrane rupture, which was demonstrated in several disease states, including ischemia–reperfusion injury (IRI) in all organs analyzed (2–6); however, none of these previous studies clearly investigated the mode of cell death in the primary parenchymal cells. Therefore, it remained possible that the protective effects reported upon application of the necroptosis inhibitor necrostatin-1 (Nec-1) and for RIPK3-ko mice involve vascular, nonparenchymal effects. This possibility has been ruled out in non-IRI settings by conditional tissue targeting of proteins involved in the prevention of spontaneously occurring necroptosis, such as RIPK1, and components that regulate its ubiquitinylation status [linear ubiquitinylation chain assembly complex (LUBAC), cellular inhibitors of apoptosis proteins (cIAPs)), caspase-8, and Fas-associated protein with death domain (FADD)] in the gastrointestinal tract (7, 8), the skin (9, 10), the liver (11), and immune cells (12, 13), all of which result in spontaneous RIPK3-mediated tissue necroptosis and inflammation (7–9, 11, 12, 14–17).Ferroptosis is an iron-dependent necrotic type of cell death that occurs due to lipid peroxide accumulation, which routinely is prevented by glutathione peroxidase 4 (GPX4), a glutathione-(GSH)-dependent enzyme, and therefore depends on the functionality of a glu/cys antiporter in the plasma membrane referred to as system X_c-minus (18–20). Ferroptosis has been reported to cause several diseases and may be interfered with in vitro by the small molecule ferrostatin-1 (Fer-1) (18); however, Fer-1 was suggested to have low in vivo functionality due to potential metabolic and plasma instability.In the present studies, we used inducible, conditional kidney tubule-specific genetic deletion of FADD and caspase-8, intravital microscopy, fresh isolation of primary kidney tubules, and four preclinical models of acute organ failure to further assess the relative roles of necroptosis and ferroptosis. We find that ferroptosis is of functional in vivo relevance in acute tubular necrosis and IRI, and we introduce, to our knowledge, the first ferroptosis inhibitor that is applicable for inhibition of ferroptosis in vivo. We conclude that specific combinatory therapies will be most promising for the prevention of clinically relevant IRI and that the nephron represents, to our knowledge, the first described tissue that is not sensitized to necroptosis by loss of FADD or caspase-8.     

Microvascular endothelial cell death and rarefaction in the glucocorticoid-induced hypertensive rat

OBJECTIVE: The objective was to quantify and to describe microvascular endothelial cell death in glucocorticoid-induced hypertension. Microvascular rarefaction, which has been shown in human and animal hypertension, may result from increased endothelial cell apoptosis. METHODS: Wistar rats were administered the synthetic glucocorticoid dexamethasone (0.5 mg/kg b.w. per day, i.m.) for 5 days and were compared with a group of control rats treated with the vehicle. In vivo microvascular endothelial cell death was quantified by propidium iodide fluorescent labeling in the mesentery. Normal nuclear DNA (labeled with Hoechst 33342) and DNA with apoptotic characteristics in muscle endothelium (labeled with ethidium bromide) were visualized using confocal imaging. Microvessel length density was measured by using a fluorescein isothyocyanate-labeled lectin technique. RESULTS: The dexamethasone-treated rats exhibit approximately a 10% increase in cell death along the mesenteric arteriolar and venular endothelium compared with controls. Confocal analysis of cremaster muscle in dexamethasone-treated rats demonstrated nuclear fragmentation and decreased nuclear volumes in dying endothelial cells, which are consistent with an apoptotic process. The capillary length density in cremaster muscle was decreased on average by 16% in the hypertensive rats. CONCLUSIONS: These results suggest capillary structural rarefaction by an increased rate of apoptotic endothelial cell death in glucocorticoid-induced hypertension.     

胰岛素对自发性高血压大鼠离体主动脉的舒张作用及机制

目的 :探讨自发性高血压大鼠 （SHR）的动脉血管对胰岛素 （Ins）反应性的改变及其主要机制。方法 :采用离体血管灌流方法 ,对比观察成年 （15周龄 ）和幼年 （5周龄 ）自发性高血压大鼠以及成年和幼年正常大鼠 （WKY）的胸主动脉环 ,在未加干预或施加干预 （机械法去除血管内皮或用一氧化氮合酶抑制剂处理 ）后对 Ins反应的变化。结果 :Ins（1～ 12 0 U/ L ）对成年和幼年 WKY胸主动脉血管具有舒张作用 ,而对相应年龄 SHR的舒张作用均降低。在12 0 U/ L Ins时 ,成年 SHR和 WKY大鼠的血管收缩率为 :73 %± 4% vs2 9%± 4% ,P<0 .0 1;幼年 SHR和 WKY大鼠的血管收缩率为 :61%± 5% vs 3 2 %± 6% ,P<0 .0 1。去除内皮或用 10μm ol/ L一氧化氮合酶抑制剂处理后 ,Ins对成年和幼年 WKY胸主动脉血管的舒张作用均降低 ,且和相应周龄的 SHR无显著差异。此外 ,成年 SHR动脉环在去除内皮前后对 Ins的反应无显著差异 （73 %± 4% vs82 %± 6% ,P>0 .0 5） ,而幼年 SHR在去除内皮后对Ins的反应显著降低 （61%± 5% vs 78%± 5% ,P<0 .0 5）。结论 :Ins对血管的舒张作用是部分通过内皮和一氧化氮 （NO）介导的。成年 SHR血管内皮细胞功能受损 ,而幼年 SHR内皮功能无明显损害。此外 ,两者可能都存在胰岛素抵抗的状态 ,从而降低了血管对 In     

Variable adhesion of different red blood cell products to activated vascular endothelium under flow conditions

Red blood cells (RBCs) that have been stored prior to transfusion show increased adherence to vascular endothelium in vitro, which suggests a potential for stored blood transfusion to impede blood flow in some patients. Transfusion is often required in patients with sepsis or inflammation; however, whether activation of endothelium affects stored RBC-endothelial cell (EC) interactions is unknown. We investigated whether storage time and leukocyte content of RBC products influences the adhesion of RBCs to activated ECs. RBCs from nonleukocyte-reduced (S-RBCs), buffy-coat-poor (BCP-RBCs), and leukocyte-filtered (LF-RBCs) products and cultured EC layers were pretreated with endotoxin, tumor necrosis factor-alpha (TNF-alpha), or medium alone prior to perfusion of the RBCs across the EC layer in a continuous flow microchamber. After a single day of RBC storage, the number of adherent RBCs was increased in the endotoxin and TNF-alpha pretreated groups compared to the unactivated-control group. These differences were statistically significant for S-RBCs and LF-RBC products (P < 0.05). In contrast, there was no significant difference in RBC adherence to activated and unactivated endothelium at other time-points of RBC product storage. The strength of adhesion of stored RBCs from S-RBC products to activated ECs was not altered following treatment; however, endotoxin significantly increased the adhesive strength of LF-RBCs to endothelium. These results demonstrate that while fresh RBCs show increased adhesion to activated endothelium, storage of RBCs did not promote increased adhesion to activated endothelium. However, inflammatory conditions promote stronger adhesion of stored RBCs to ECs, which may contribute to impaired tissue perfusion in some transfusion recipients.     

Requirement of arteriovenular pairing for increased capillary filtration during acute inflammation

OBJECTIVE: The purpose of this study was to determine whether the leukocyte chemoattractant N-formyl methionyl-leucyl-phenylalanine (FMLP) increases capillary fluid filtration rate (Jv/S), and if so, to determine whether the mechanism involves arteriovenular communication. METHODS: Intravital microscopy was used in the rat mesentery to measure capillary Jv/S by a micro-occlusion technique. FMLP was locally superfused through a micropipette near vessels in three different arrangements: 1) near a venule in close pairing with the arteriole feeding the monitored capillary, 2) near an unpaired arteriole feeding the capillary, or 3) near an unpaired venule draining the capillary. In separate experiments, arteriolar hydrostatic pressure (downstream of arteriovenular pairing sites exposed to FMLP) was measured with a micropressure system. RESULTS: FMLP increased capillary Jv/S when applied to arteriovenular pairing sites, but not when applied to unpaired arterioles or venules. Micropressure measurements in paired arterioles remained essentially constant during FMLP exposure, suggesting that the increase in Jv/S is primarily due to increased capillary permeability. CONCLUSIONS: With FMLP applied locally to stimulate leukocytes, arteriovenular pairing is required to observe an increase in capillary filtration rate.     

Anthrax lethal toxin and Salmonella elicit the common cell death pathway of caspase-1-dependent pyroptosis via distinct mechanisms

Caspase-1 cleaves the inactive IL-1beta and IL-18 precursors into active inflammatory cytokines. In Salmonella-infected macrophages, caspase-1 also mediates a pathway of proinflammatory programmed cell death termed "pyroptosis." We demonstrate active caspase-1 diffusely distributed in the cytoplasm and localized in discrete foci within macrophages responding to either Salmonella infection or intoxication by Bacillus anthracis lethal toxin (LT). Both stimuli triggered caspase-1-dependent lysis in macrophages and dendritic cells. Activation of caspase-1 by LT required binding, uptake, and endosome acidification to mediate translocation of lethal factor (LF) into the host cell cytosol. Catalytically active LF cleaved cytosolic substrates and activated caspase-1 by a mechanism involving proteasome activity and potassium efflux. LT activation of caspase-1 is known to require the inflammasome adapter Nalp1. In contrast, Salmonella infection activated caspase-1 through an independent pathway requiring the inflammasome adapter Ipaf. These distinct mechanisms of caspase-1 activation converged on a common pathway of caspase-1-dependent cell death featuring DNA cleavage, cytokine activation, and, ultimately, cell lysis resulting from the formation of membrane pores between 1.1 and 2.4 nm in diameter and pathological ion fluxes that can be blocked by glycine. These findings demonstrate that distinct activation pathways elicit the conserved cell death effector mechanism of caspase-1-mediated pyroptosis and support the notion that this pathway of proinflammatory programmed cell death is broadly relevant to cell death and inflammation invoked by diverse stimuli.     

Role of endothelial cell survival and death signals in angiogenesis

Angiogenesis, the process of new microvessel development, is encountered in a select number of physiological processes and is central to the pathogenesis of a wide variety of diseases. There is now convincing evidence that regulated patterns of endothelial cell survival and death, a process known as apoptosis, play a central role in the periodic remodeling of the vasculature, and in the timely evolution and regression of angiogenic responses. In this review we discuss the current evidence suggesting a role for inducers and inhibitors of angiogenesis as well as other mediators that modify endothelial cells functions in the survival and death of endothelial cells. We also discuss how dysregulation of apoptosis can lead to aberrant angiogenesis as demonstrated in the pathogenesis of retinopathy of prematurity and cancer. This revised version was published online in June 2006 with corrections to the Cover Date.     

Enhancement of glucocorticoid and mineralocorticoid receptor density in the microcirculation of the spontaneously hypertensive rat

OBJECTIVE: Elevated blood pressure and abnormal physiological parameters in the microcirculation of the spontaneously hypertensive rat (SHR) can be normalized by adrenalectomy. Thus glucocorticoids and mineralocorticoids may have major control over blood pressure status and organ injury mechanisms in SHRs. As background, this study was designed to examine the distribution of the glucocorticoid and mineralocorticoid receptors in a microvascular network. METHODS: Mature SHR and their normotensive controls, the Wistar-Kyoto (WKY) rat, were studied. An immunohistochemical method was developed that provides a comprehensive display of the receptors in all segments of the mesentery microcirculation and the surrounding tissue parenchyma. RESULTS: All cells in the mesentery exhibit immunolabeling of the glucocorticoid receptor with predominant expression in the nuclei of parenchymal and endothelial cells. The mineralocorticoid receptor is expressed also in most cells of the microcirculation and adjacent parenchymal tissue. Both receptors exhibit the highest levels of immunolabel in the wall of the arterioles and venules, with lower levels in capillaries. Compared with WKY rats, the SHRs exhibit significantly enhanced density of glucocorticoid and mineralocorticoid receptors in endothelial cells of arterioles and venules as well as in parenchymal cells. CONCLUSIONS: These results suggest that the enhanced sensitivity of the SHR to glucocorticoids and aldosterone may be in part associated with enhanced glucocorticoid and mineralocorticoid receptor densities in the microcirculation.     

Participation of Mac-1, LFA-1 and VLA-4 integrins in the in vitro adhesion of sickle cell disease neutrophils to endothelial layers, and reversal of adhesion by simvastatin

Background

Pharmacological approaches to inhibit increased leukocyte adhesive interactions in sickle cell disease may represent important strategies for the prevention of vaso-occlusion in patients with this disorder. We investigated, in vitro, the adhesion molecules involved in endothelial-sickle cell disease neutrophil interactions and the effect of simvastatin on sickle cell disease neutrophil adhesion to tumor necrosis factor-α-activated endothelial monolayers (human umbilical vein endothelial cells), and neutrophil chemotaxis.

Design and Methods

Sickle cell disease patients in steady state and not on hydroxyurea were included in the study. Endothelial cells treated, or not, with tumor necrosis factor-α and simvastatin were used for neutrophil adhesion assays. Neutrophils treated with simvastatin were submitted to interleukin 8-stimulated chemotaxis assays.

Results

Sickle cell disease neutrophils showed greater adhesion to endothelial cells than control neutrophils. Adhesion of control neutrophils to endothelial cells was mediated by Mac-1 under basal conditions and by the Mac-1 and LFA-1 integrins under inflammatory conditions. In contrast, adhesion of sickle cell disease neutrophils to endothelium, under both basal and tumor necrosis factor-α-stimulated conditions, was mediated by Mac-1 and LFA-1 integrins and also by VLA-4. Under stimulated inflammatory conditions, simvastatin significantly reduced sickle cell disease neutrophil adhesion, and this effect was reversed by inhibition of nitric oxide synthase. Furthermore, intercellular adhesion molecule-1 expression was significantly abrogated on tumor necrosis factor-α-stimulated endothelium incubated with simvastatin, and statin treatment inhibited the interleukin-8-stimulated migration of both control and sickle cell disease neutrophils.

Conclusions

The integrins Mac-1, LFA-1 and, interestingly, VLA-4 mediate the adhesion of sickle cell disease leukocytes to activated endothelial cell layers, in vitro. Our data indicate that simvastatin may be able to reduce endothelial activation and consequent leukocyte adhesion in this in vitro model; future experiments and clinical trials may determine whether simvastatin therapy could be employed in patients with sickle cell disease, with beneficial effects on vaso-occlusion.     

伊贝沙坦对自发性高血压大鼠细胞钙离子转运蛋白的影响

目的观察在高血压发病过程中,主动脉血管平滑肌细胞Ca~(2+)转运蛋白活性的改变,阐明伊贝沙坦(IBT)降低血压与上述蛋白活性改变的相关性。方法选取16周龄健康雄性自发性高血压大鼠(SHR)16只,随机分为IBT组(8只)和SHR组(8只),另选健康雄性Wistar Kyoto大鼠8只为正常对照组(WKY组)。IBT组大鼠给予IBT 60 mg/(kg·d)加适量蒸馏水灌胃14周。观察给药前后大鼠尾动脉收缩压的变化,并检测胸主动脉平滑肌细胞Na~+-K~+ATP酶和Ca~(2+)Mg~(2+)-ATP酶的活性。结果与SHR组比较,给药14周后,IBT组和WKY组大鼠尾动脉收缩压明显降低;IBT组和WKY组大鼠血管平滑肌细胞Na~+-K~+-ATP酶和Ca~(2+)-Mg~(2+)ATP酶活性均明显升高(P0.05,P0.01)。Na~+-K~+-ATP酶和Ca~(2+)-Mg~(2+)-ATP酶活性与血压呈显著负相关(r=-0.446,r=-0.387,P0.01)。结论高血压的发病与细胞Ca~(2+)转运蛋白活性的改变有关。IBT干预14周可以改善SHR的血管平滑肌细胞Ca~(2+)转运蛋白活性。     

Caspase-dependent cell death mediates the early phase of aortic hypertrophy regression in losartan-treated spontaneously hypertensive rats

Blockade of angiotensin type 1 (AT1) receptors induces smooth muscle cell (SMC) death and regression of aortic hypertrophy in spontaneously hypertensive rats (SHR). We postulated that SMC death and vascular remodeling in this model may be attenuated by z-Val-Ala-Asp(OMe)-CH2F (z-VAD-fmk), a tripeptide inhibitor of caspase enzymes mediating apoptosis. To determine the time course of SMC death and aortic remodeling, SHR were treated with losartan (30 mg/kg per day) for up to 9.5 days. Transient SMC apoptosis occurred in the aortic media with a peak around day 5 of treatment, with increases in the Bax to Bcl-2 protein ratio (>3-fold), in active caspase-3 (5.6-fold), in TUNEL-positive nuclei (19-fold), preceding by 24 hours the peak activation of capase-9 (3.8-fold), and significant reductions in SMC number (46%) and aortic cross-sectional area (8.5%) at 5.5 days. The decrease in total aortic DNA reached significance at 6.5 days (29%). Blood pressure reduction with losartan was progressive and reached significance at day 7 of treatment. Next, we examined the causal link between vascular apoptosis and remodeling. SHR received placebo or losartan (30 mg/kg per day) for 6 days. During the last 24 hours, a subgroup of losartan-treated rats received 3 IV injections of z-VAD-fmk (cumulative dose: 4.4 mg x kg(-1)). All other rats received the vehicle, DMSO. The 24-hour cotreatment with z-VAD-fmk effectively prevented losartan-induced caspase-3 activation and internucleosomal DNA fragmentation, as well as SMC depletion and the reductions in aortic mass and DNA content. Together, these data suggest that caspase-dependent SMC death mediates the early phase of vascular remodeling in response to AT1 receptor blockade in this model of hypertension.     

Inhibitory effects of TSG-6 Link module on leukocyte-endothelial cell interactions in vitro and in vivo

OBJECTIVE: The authors investigated whether the anti-inflammatory protein tumor necrosis factor (TNF)-stimulated gene-6 (TSG-6) and its Link module (Link_TSG6) could affect the complex multistep process of leukocyte/endothelial cell (EC) interaction. METHODS: Mouse mesenteries were inflamed with interleukin (IL)-1beta and the extent of leukocyte rolling, adhesion, and emigration was determined after 2 h. Link_TSG6 and a single-point mutant (termed K13E) were given intraperitoneally together with the cytokine. Human neutrophil chemotaxis and transmigration were determined in vitro in response to IL-8 and/or TNF-alpha. TSG-6, Link_TSG6, and K13E were added to the leukocytes or the EC monolayers. RESULTS: Co-injection of Link_TSG6 with IL-1beta selectively inhibited cell flux, adhesion, and emigration as analyzed in mesenteric postcapillary venules. The fewer cells that rolled in the animals treated with Link_TSG6 displayed a velocity similar to that measured in vehicle-treated mice. In vitro, Link_TSG6 did not affect neutrophil chemotaxis or EC activation but did inhibit neutrophil transmigration across EC monolayers. The latter effect was shared by full-length TSG-6 and observed equally in response to IL-8 or TNF-alpha. CONCLUSIONS: These data restrict the site of action for at least some of the anti-inflammatory effects ascribed to TSG-6/Link_TSG6 to the microenvironment of the extravasating leukocyte.     

Enhanced endothelial activation in diabetic patients with unstable angina and non-Q-wave myocardial infarction.

AIMS: Diabetes mellitus (DM) is associated with chronic endothelial dysfunction. Diabetic patients presenting with acute coronary syndromes have a worse prognosis than non-diabetics. An acute inflammatory reaction at the site of coronary plaque rupture and increased expression of surface and soluble cellular adhesion molecules (CAMs) are pathological features of acute coronary syndromes. We set out to characterize the expression of soluble CAMs in patients with and without diabetes presenting with unstable angina (UA) and non Q-wave myocardial infarction (NQMI). METHODS: Patients presenting with UA and NQMI had serum samples taken on presentation, after 72 h and then 3, 6 and 12 months after discharge. Levels of soluble intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin and P-selectin were measured using an ELISA technique. RESULTS: We studied 15 diabetic patients and 15 age- and sex-matched non-diabetic patients presenting with either UA or NQMI. Levels of soluble E-selectin were elevated in the diabetic patients in comparison with the non-diabetic patients at all measured time points: 74 +/- 10 ng/ml vs. 47 +/- 3 ng/ml, P < 0.03 at t = 0 h, 55 +/- 5 ng/ml vs. 38 +/- 2 ng/ml, P < 0.02 at t = 72 h. However, levels of soluble P-selectin were lower in the diabetic cohort during follow-up: 134 +/- 15 ng/ml vs. 225 +/- 32 ng/ml, P < 0.02 at t = 3/12 and 112 +/- 8 ng/ml vs. 197 +/- 23 ng/ml, P < 0.02 at t = 6/12. There was no significant difference in levels of soluble ICAM-1 and VCAM-1 between diabetic and non-diabetic patients. CONCLUSIONS: Levels of soluble E-selectin are significantly elevated in diabetic patients presenting with UA and NQMI in comparison with non-diabetics. This finding may reflect enhanced endothelial activation which may contribute to the adverse prognosis of diabetic patients with acute coronary syndromes.