Enhanced Expression of ANGPTL2 in the Microvascular Lesions of Diabetic Glomerulopathy

ANGPTL2 knockdown induces autophagy to relieve alveolar macrophage pyroptosis by reducing LILRB2-mediated inhibition of TREM2

Acute lung injury (ALI) is featured with a robust inflammatory response. Angiopoietin-like protein 2 (ANGPTL2), a pro-inflammatory protein, is complicated with various disorders. However, the role of ANGPTL2 in ALI remains to be further explored. The mice and MH-S cells were administrated with lipopolysaccharide (LPS) to evoke the lung injury in vivo and in vitro. The role and mechanism of ANGPTL was investigated by haematoxylin-eosin, measurement of wet/dry ratio, cell count, terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labeling, reverse transcription quantitative polymerase chain reaction, immunofluorescence, enzyme-linked immunosorbent assay, detection of autophagic flux and western blot assays. The level of ANGPTL2 was upregulated in lung injury. Knockout of ANGPTL2 alleviated LPS-induced pathological symptoms, reduced pulmonary wet/dry weight ratio, the numbers of total cells and neutrophils in BALF, apoptosis rate and the release of pro-inflammatory mediators, and modulated polarization of alveolar macrophages in mice. Knockdown of ANGPTL2 downregulated the level of pyroptosis indicators, and elevated the level of autophagy in LPS-induced MH-S cells. Besides, downregulation of ANGPTL2 reversed the LPS-induced the expression of leukocyte immunoglobulin (Ig)-like receptor B2 (LILRB2) and triggering receptor expressed on myeloid cells 2 (TREM2), which was reversed by the overexpression of LILRB2. Importantly, knockdown of TREM2 reversed the levels of autophagy- and pyroptosis-involved proteins, and the contents of pro-inflammatory factors in LPS-induced MH-S cells transfected with si ANGPTL2, which was further inverted with the treatment of rapamycin. Therefore, ANGPTL2 silencing enhanced autophagy to alleviate alveolar macrophage pyroptosis via reducing LILRB2-mediated inhibition of TREM2.

Blocking angiotensin 2 receptor attenuates diabetic nephropathy via mitigating ANGPTL2/TL4/NF-κB expression

BACKGROUND

Diabetic nephropathy (DN) is a consequence of diabetes mellitus (DM) and is associated with early changes in renal angiotensin II (ANG II). These changes were evaluated using ANG II blocker valsartan early from week two of diabetes (experiment I, renoprotective) and late from week nine of diabetes (experiment II, renotherapeutic) to the end of both experiments at week twelve.

METHODS AND RESULTS

In both experiments, adult male Wister rats were divided into (i) vehicle group; (ii) valsartan received oral 30 mg/Kg/day; (iii) diabetic received single 50 mg/Kg intraperitoneal streptozotocin injection; (iv) renoprotection, diabetic rats received valsartan treated in experiments I and II. DM effects on urine albumin excretion, blood pressure, and renal ANG II were measured. Urinary nephrin, kidney injury molecule-1 (KIM-1), renal angiopoietin-like protein 2 (ANGPTL2), and toll-like receptor 4 (TLR 4) mRNA expression were tested. DM-initiated fibrotic markers integrin, α-smooth muscle actin expression, and collagen IV and apoptotic protein caspase 3 were tested. DM induced early changes starting from week four in the tested variables. At week twelve, in both experiments, valsartan intervention showed a significant reduction in ANG II, ANGPTL2, TLR 4 and integrin expression and improvement in albuminuria, blood pressure, urinary biomarkers, fibrotic and apoptotic markers.

CONCLUSIONS

Changes leading to DN starts early in the disease course and ANG II reduction decreased the expression of ANGPTL2 and integrin which preserve the glomerular barrier. Blocking ANG II was able to decrease TLR 4 and inflammatory cytokines leading to decreasing DN.

Protective Effect of Irbesartan by Inhibiting ANGPTL2 Expression in Diabetic Kidney Disease

Angiopoietin-like protein 2 (ANGPTL2) stimulates inflammation and is important in the pathogenesis of diabetic kidney disease (DKD). Irbesartan is helpful in reducing diabetes-induced renal damage. In this study, the effects of irbesartan on DKD and its renal protective role involving ANGPTL2 in DKD rats were examined. Wistar rats were divided into normal, DKD, and DKD + irbesartan groups. The DKD + irbesartan group was treated once daily for 8 weeks with 50 mg/kg irbesartan via intragastric gavage. The 24-h urinary albumin was determined each week, renal pathological changes were observed, and expression of ANGPTL2 and nuclear factor-kappa B (NF-κB) in rat renal tissue was assessed by immunohistochemistry. Mouse podocytes cultured in a high concentration of glucose were classified into four groups based on the irbesartan concentrations (0, 25, 50, and 75 ºg/mL). Expression of ANGPTL2 and phosphorylated IκB-α was assessed by Western blotting. The mRNA levels of ANGPTL2 and monocyte chemotactic protein 1 (MCP-1) were assessed by real-time polymerase chain reaction. The DKD rats displayed proteinuria, podocyte injury, and increased ANGPTL2 and NF-κB expression. All were relieved by irbesartan treatment. In podocytes cultured in elevated glucose, ANGPTL2 and phosphorylated IκB-α were overexpressed at the protein level, and ANGPTL2 and MCP-1 were highly expressed at the mRNA level. Irbesartan down-regulated ANGPTL2 and phosphorylated IκB-αexpression at the protein level and inhibited ANGPTL2 and MCP-1 expression at the mRNA level. The ameliorative effects of irbesartan against DKD involves podocyte protection and suppression of ANGPTL2.

Diabetic Kidney Disease, Endothelial Damage, and Podocyte-Endothelial Crosstalk

Diabetes-related complications are a significant source of morbidity and mortality worldwide. Diabetic kidney disease is a frequent microvascular complication and a primary cause of kidney failure in patients with diabetes. The glomerular filtration barrier is composed of 3 layers: the endothelium, glomerular basement membrane, and podocytes. Podocytes and the endothelium communicate through molecular crosstalk to maintain filtration at the glomerular filtration barrier. Chronic hyperglycemia affects all 3 layers of the glomerular filtration barrier, as well as the molecular crosstalk that occurs between the 2 cellular layers. One of the earliest events following chronic hyperglycemia is endothelial cell dysfunction. Early endothelial damage is associated with progression of diabetic kidney disease. However, current therapies are based in controlling glycemia and arterial blood pressure without targeting endothelial dysfunction. Disruption of the endothelial cell layer also alters the molecular crosstalk that occurs between the endothelium and podocytes. This review discusses both the physiologic and pathologic communication that occurs at the glomerular filtration barrier. It examines how these signaling components contribute to podocyte foot effacement, podocyte detachment, and the progression of diabetic kidney disease.

Association between angiopoietin-like protein 2 and lectin-like oxidized low-density lipoprotein receptor 1 ligand containing apolipoprotein B in patients with type 2 diabetes

Objective

This study was performed to evaluate the association of the serum level of angiopoietin-like protein 2 (ANGPTL2) with circulating inflammatory markers and oxidized and modified low-density lipoprotein (LDL) cholesterol as evaluated by lectin-like oxidized LDL receptor 1 ligand containing apolipoprotein B (LAB) in patients with type 2 diabetes.

Methods

The study included 70 patients with type 2 diabetes hospitalized for glycemic control and 9 control subjects.

Results

The serum level of ANGPTL2 was significantly higher in the patients with type 2 diabetes than in the healthy controls. There was a significant positive correlation between ANGPTL2 and the high-sensitivity C-reactive protein, fibrinogen, and LAB levels and a significant negative correlation between ANGPTL2 and the estimated glomerular filtration rate (eGFR).

Conclusions

These results suggest that the serum ANGPTL2 level has a close positive association with inflammatory markers, especially fibrinogen and oxidized and modified LDL as evaluated by LAB. The data also suggest that the serum ANGPTL2 level is influenced by renal function as reflected by the eGFR.

Kaempferol modulates Angiopoietin-like protein 2 expression to lessen the mastitis in mice

BACKGROUND

Mastitis is inflammation of a breast (or udder). Angiopoietin-like protein 2 (ANGPTL2) has been found as a key inflammatory mediator in mastitis. Purpose of this research was to investigate the mechanisms about repressing effect of kaempferol on mastitis.

METHODS

Forty mice were randomly divided into 4 groups (n=10): C57BL/6J control mice, untreated murine mastitis, 10mg/kg kaempferol treated murine mastitis (ip), and 30mg/kg kaempferol treated murine mastitis (ip). Primary cultured mouse mammary epithelial cells (MMEC) were indiscriminately divided into seven groups including control group, 10mmol/L vehicle of kaempferol group, 10μmol/L kaempferol treated group, 20μg/mL LPS treated group, 1μmol/L kaempferol plus LPS treated group, 3μmol/L kaempferol plus LPS treated group, and 10μmol/L kaempferol plus LPS treated group.

RESULTS

In murine mastitis, kaempferol (10 or 30mg/kg) treatment prevented mastitis development, decreased myeloperoxidase (MPO) production, interleukin (IL)-6 level, tumour necrosis factor-α (TNF-α) concentration, and ANGPTL2 expression. In MMEC, kaempferol (1, 3 or 10μM) reduced MPO production, TNF-α concentration, IL-6 level, and ANGPTL2 expression.

CONCLUSIONS

The results in present study show that kaempferol modulates the expression of ANGPTL2 to lessen the mastitis in mice.

High Circulating Levels of ANGPTL2: Beyond a Clinical Marker of Systemic Inflammation

Angiopoietin-like 2 (ANGPTL2) is a proinflammatory protein belonging to the angiopoietin-like family. ANGPTL2 is secreted and detected in the systemic circulation. Different observational clinical studies reported that circulating levels of ANGPTL2 increase significantly in various chronic inflammatory diseases and showed associations between ANGPTL2 levels and diagnosis and/or prognosis of cardiovascular diseases, diabetes, chronic kidney disease, and various types of cancers. However, these studies did not address the following questions: (a) what are the sources of circulating ANGPTL2? (b) How and by which mechanisms an increase in circulating ANGPTL2 contributes to the pathogenesis of chronic inflammatory diseases? (c) Does an increase in circulating levels of ANGPTL2 measured in a well-defined chronic medical condition originate from a specific cell type? Mechanistic hypotheses have been proposed based on studies performed in mice and cultured cells, and proinflammatory, prooxidative, proangiogenic, proliferative, and antiapoptotic properties of ANGPTL2 have been reported. The aim of this review is to propose answers concerning the potential sources of circulating ANGPTL2 and its common pathological properties associated with various chronic inflammatory diseases and death in humans. We believe that high circulating ANGPTL2 levels are more than an inflammatory marker and may reflect the senescent cellular load of an individual.

Angiopoietin-like protein 2 and kidney fibrosis: lessons from knockout mice

The angiopoietin-like protein (ANGPTL) family is homologous to angiopoietins but does not bind to the Tie2 receptor. The function of ANGPTLs has been elucidated largely in the context of angiogenesis and lipid metabolism. Morinaga et al. demonstrated that genetic depletion of Angptl2 confers amelioration of the mouse kidney fibrosis induced by a unilateral ureteral obstruction, implicating that ANGPTL2, predominantly in the renal tubular compartments, activates the transforming growth factor-β signaling and vice versa through miR-221.

A Systems Biology Overview on Human Diabetic Nephropathy: From Genetic Susceptibility to Post-Transcriptional and Post-Translational Modifications

Diabetic nephropathy (DN), a microvascular complication occurring in approximately 20-40% of patients with type 2 diabetes mellitus (T2DM), is characterized by the progressive impairment of glomerular filtration and the development of Kimmelstiel-Wilson lesions leading to end-stage renal failure (ESRD). The causes and molecular mechanisms mediating the onset of T2DM chronic complications are yet sketchy and it is not clear why disease progression occurs only in some patients. We performed a systematic analysis of the most relevant studies investigating genetic susceptibility and specific transcriptomic, epigenetic, proteomic, and metabolomic patterns in order to summarize the most significant traits associated with the disease onset and progression. The picture that emerges is complex and fascinating as it includes the regulation/dysregulation of numerous biological processes, converging toward the activation of inflammatory processes, oxidative stress, remodeling of cellular function and morphology, and disturbance of metabolic pathways. The growing interest in the characterization of protein post-translational modifications and the importance of handling large datasets using a systems biology approach are also discussed.

Angiopoietin-like-2: a multifaceted protein with physiological and pathophysiological properties

Angptl2 is a multifaceted protein, displaying both physiological and pathological functions, in which scientific and clinical interest is growing exponentially within the past few years. Its physiological functions are not well understood, but angptl2 was first acknowledged for its pro-angiogenic and antiapoptotic capacities. In addition, angptl2 can be considered a growth factor, since it increases survival and expansion of hematopoietic stem cells and may promote vasculogenesis. Finally, angptl2 has an important, but largely unrecognised, physiological role: in the cytosol, angptl2 binds to type 1A angiotensin II receptors and induces their recycling, with recovery of the receptor signal functions. Despite these important physiological properties, angptl2 is better acknowledged for its deleterious pro-inflammatory properties and its contribution in multiple chronic diseases such as cancer, diabetes, atherosclerosis, metabolic disorders and many other chronic diseases. This review aims at presenting an updated description of both the beneficial and deleterious biological properties of angptl2, in addition to its molecular signalling pathways and transcriptional regulation. The multiplicity of diseases in which angptl2 contributes makes it a new highly relevant clinical therapeutic target.

Endothelial-podocyte crosstalk: the missing link between endothelial dysfunction and albuminuria in diabetes

Although diabetes is the most common cause of end-stage renal disease (ESRD) worldwide, most people with diabetic nephropathy will never develop ESRD but will instead die of cardiovascular (CV) disease (CVD). The first evidence of kidney injury in diabetes is often microalbuminuria, itself also an independent risk marker for CVD. Although the two processes are closely associated, the recent failure of antialbuminuric therapies to affect CV outcomes has encouraged a reconsideration of how albuminuria may occur in diabetes and how increased urinary albumin excretion may be indicative of CV risk. The relationship between CVD and urinary albumin content (even within the normal range) is widely considered to reflect the common underlying pathology of endothelial dysfunction. At the same time, recent years have witnessed a growing appreciation that diabetic albuminuria commonly arises from damage to glomerular podocytes, specialized epithelial cells acting as the final barrier to macromolecular flow into the urinary filtrate. These superficially discordant paradigms can be assimilated by the emerging concept of endothelial-podocyte crosstalk across the glomerular filtration barrier, whereby the actions of one type of cell may profoundly influence the function of the other. The bidirectional nature of this paracrine network is illustrated by the actions of the vascular endothelial growth factor-A (VEGF-A)/VEGF receptor-2 and activated protein C systems, among others. Identification of novel mediators of endothelial-podocyte crosstalk may lead to the development of more effective treatments for diabetic nephropathy and its sequelae.

Effect of qubi zhentong recipe on synovial gene expression in collagen-induced arthritis in rats

OBJECTIVE

To investigate the effect of the Chinese medical formula Qubi Zhentong Recipe(, QZR) on the synovial gene expression profile in collagen-induced arthritis (CIA) rats.

METHODS

Ten rats were randomly chosen from 60 rats as the control group, and the other 50 rats were used for the CIA models. The CIA model group was constructed by bovine injection of type II collagen through the rats' neck and tail. Twenty rats were randomly chosen from 34 successful CIA models and randomly assigned into two groups: the model group (n =10) and the QZR group (n=10). The QZR group was fed intragastrically with QZR 22.9 g/(kg·d) (10 times the clinical adult dose), and the CIA model group was given the same dose of normal saline. Both model and QZR groups were administered treatment once a day. Total RNA was collected from the knee joint synovium after 30 days. The change in gene expression profile was analyzed by a whole gene chip.

RESULTS

A total of 76 genes showed a difference in expression between CIA model group and the control group; 35 genes were down-regulated and 41 were up-regulated. A total of 67 genes showed a difference in expression between the model group and the QZR group; 48 genes were down-regulated and 19 were upregulated.

CONCLUSIONS

QZR may affect CIA by stimulating multiple genes and targets, which are related to oncogenes, apoptosis, metabolism, the immune system, ion channels, and transport proteins.

Serum Angptl2 levels are independently associated with albuminuria in type 2 diabetes

BACKGROUND

Elevated serum Angptl2 levels are positively associated with the development of type 2 diabetes. We investigated whether serum Angptl2 levels are associated with diabetic nephropathy in patients with type 2 diabetes.

METHODS

Two hundred and thirty patients with type 2 diabetes and 63 healthy controls participated in this cross-sectional study. Subjects with type 2 diabetes were divided into three groups using urinary albumin-to-creatinine ratio (ACR): a normoalbuminuric group (n=57), a microalbuminuric group (n=130) and a macroalbuminuria group (n=43). Serum Angptl2 concentrations were measured by enzyme-linked immunosorbent assay.

RESULTS

Median serum (interquartile range) Angptl2 levels in control subjects and patients with type 2 diabetes with normoalbuminuria, microalbuminuria and macroalbuminuria were 24.03 (16.3-33.45), 36.14 (27.91-43.07), 44.6 (37.47-49.92), 50.19 (45.95-60.13)ng/ml (p<0.01) respectively. Angptl2 levels correlated with urinary ACR in participants with type 2 diabetes (r=0.38, p<0.01). Significant intercorrelations of Angptl2 were found with age, duration of diabetes, and fasting plasma glucose. After adjustment for significant covariates, albuminuria was still significantly associated with Angptl2 levels in type 2 diabetes (r=0.31, p<0.01).

CONCLUSIONS

Angptl2 levels are elevated in patients with type 2 diabetes with an independent association between increasing Angptl2 levels and increasing levels of albuminuria. This suggests a possible role of Angptl2 in progressive nephropathy in patients with type 2 diabetes.

VEGF and angiopoietins in diabetic glomerulopathy: how far for a new treatment?

Diabetic nephropathy (DN) is the major cause of end-stage renal disease in Western countries and its prevalence continues to increase (United States Renal Data System 2010, http://www.usrds.org/). Treatments currently utilised for DN provide only partial renoprotection, hence the need to identify new targets for therapeutic intervention. Metabolic and haemodynamic abnormalities have been implicated in the pathogenesis of DN, triggering the activation of intracellular signaling molecules that lead to the dysregulation of vascular growth factors and cytokines, such as vascular endothelial growth factor (VEGF) and angiopoietins, important players in the functional and structural regulation of the glomerular filtration barrier. This review focuses on the importance of VEGF-A and angiopoietins in kidney physiology and in the diabetic kidney, exploring their potential therapeutic role in the prevention and delay of diabetic glomerulopathy.

Angiopoietin-like protein 2 mediates endotoxin-induced acute inflammation in the eye

Angiopoietin-like protein (Angptl) 2 is a key mediator linking obesity to chronic adipose-tissue inflammation and systemic insulin resistance, and increasing evidence has shown that Angptl2 is associated with various chronic inflammatory diseases such as cancer and dermatomyositis; however, it remains unclear that Angptl2 functions in acute inflammation. In this study, we investigate whether Angptl2 has a role in acute inflammation in the eye with endotoxin-induced uveitis (EIU). Angptl2 was widely expressed in the normal mouse retina, while Angptl2⁻/⁻ mice did not exhibit any changes in retinal cell marker expression and morphological analyses. Treatment with lipopolysaccharide (LPS) stimulated retinal Angptl2 mRNA expression in vivo and in vitro. We generated EIU in wild-type (C57BL/6) and Angptl2⁻/⁻ mice by injecting LPS intraperitoneally. Compared with wild-type animals, Angptl2⁻/⁻ mice significantly reduced various EIU-associated cellular and molecular parameters including leukocyte adhesion to the retinal vessels and infiltration into the vitreous cavity and retinal mRNA expression levels of monocyte chemotactic protein-1, intercellular adhesion molecule-1, interleukin (IL)-6, and tumor necrosis factor (TNF)-α, together with nuclear translocation of nuclear factor (NF)-κB p65 subunit. In vitro, antibody-based inhibition of α5β1 integrin, a receptor for Angptl2, significantly repressed LPS-induced expression of IL-6 and TNF-α, both of which are the major inflammatory cytokines derived from macrophages. The present findings indicate that Angptl2 mediates endotoxin-induced retinal inflammation through the activation of NF-κB signaling pathway and suggest a potential validity of Angptl2 as a new molecular target for the treatment of acute inflammation.

The endothelium in diabetic nephropathy

The long-term complications of diabetes are characterized by pathologic changes in both the microvasculature and conduit vessels. Although the fenestrated glomerular endothelium classically has been viewed as providing little in the way of an impediment to macromolecular flow, increasing evidence illustrates that this is not the case. Rather, hyperglycemia-mediated endothelial injury may predispose to albuminuria in diabetes both through direct effects and through bidirectional communication with neighboring podocytes. Although neo-angiogenesis of the glomerular capillaries may be a feature of early diabetes, particularly in the experimental setting, loss of capillaries in the glomerulus and in the interstitium are key events that each correlate closely with declining glomerular filtration rate in patients with diabetic nephropathy. The hypoxic milieu that follows the microvascular rarefaction provides a potent stimulus for fibrogenesis, leading to the glomerulosclerosis and tubulointerstitial fibrosis that characterize advanced diabetic kidney disease. Given the pivotal role the endothelium plays in both the development and the progression of diabetic nephropathy we need effective strategies that prevent its loss or accelerate its regeneration. Such advances likely will lead not only to improved tissue oxygenation and reduced fibrosis, but also to improved long-term renal function.

Tumor necrosis factor-α increases angiopoietin-like protein 2 gene expression by activating Foxo1 in 3T3-L1 adipocytes

Angiopoietin-like protein 2 (Angptl2) is a key adipocyte-derived inflammatory mediator linking obesity to systemic insulin resistance, which is overexpressed in obesity and related metabolic diseases. However, its regulatory mechanism remains unclear. In this study, we showed that tumor necrosis factor (TNF)-α treatment increased the expression of Angptl2 gene in 3T3-L1 adipocytes. The cloning and sequence analysis of the Angptl2 gene promoter revealed the presence of several putative-binding sites for transcriptional factors, including two IREs. Insulin suppressed Angptl2 mRNA expression in dose-dependent manners, which could be attenuated by a phosphoinositide 3-kinase (PI3K) inhibitor LY294002. The interactions between IRE sites within Angptl2 promoter and forkhead transcription factor Foxo1 were identified by EMSA and ChIP assay. Furthermore, lentivirus-mediated knockdown of Foxo1 expression inhibited the transcriptional activity of Angptl2 promoter and decreased Angptl2 mRNA expression. Finally, TNF-α inhibited Foxo1 phosphorylation and enhanced its transcriptional activity, through which TNF-α increased the expression of Angptl2 in adipocytes. These results suggest that TNF-α up-regulates Angptl2 mRNA expression via PI3K/Foxo1 pathway in 3T3-L1 adipocytes, which may be involved in obesity-induced inflammation and insulin resistance.

Angiopoietin-like proteins--potential therapeutic targets for metabolic syndrome and cardiovascular disease

Recent major increases in obesity and related metabolic diseases (known as the metabolic syndrome (MetS)) because of sedentary lifestyles and overnutrition in developed and developing countries, are an exploding medical and social problem. These conditions are associated with increased risk of cardiovascular disease (CVD), the leading cause of death. Thus, it is necessary to understand the molecular basis underlying MetS and develop effective preventive and therapeutic approaches against CVD. To date, 7 angiopoietin-like proteins (Angptls) that are structurally similar to angiopoietins have been identified. However, none binds to the angiopoietin receptor, Tie2, or to the closely related Tie1 receptor, suggesting that these ligands function differently from angiopoietins. Some Angptls potently regulate angiogenesis, similar to angiopoietins, whereas others have pleiotropic activity other than angiogenesis and function in lipid and energy metabolism. In this review, we focus on the roles of Angptl2 and Angptl6/angiopoietin-like growth factor (AGF) in the development of MetS and CVD, and discuss the potential for Angptl2 and Angptl6/AGF to function as molecular targets for the prevention and treatment of both conditions.

Stress-induced senescence predominates in endothelial cells isolated from atherosclerotic chronic smokers

Age-associated telomere shortening leads to replicative senescence of human endothelial cells (EC). Risk factors for cardiovascular disease (CVD) accelerate ageing, while there is a concomitant rise in oxidative stress known to promote stress-induced senescence (SIS) in vitro. Of all risk factors for CVD, smoking is most associated with the development of inflammation and accelerated atherosclerosis due to a prooxidant-antioxidant imbalance. We tested the hypothesis that SIS predominates in EC isolated from chronic smokers with premature atherosclerosis undergoing coronary artery bypass graft surgery (CABG). We isolated and cultured EC from segments of internal mammary arteries from smoker, former smoker, and nonsmoker coronary patients. Senescence of EC was induced by serial passage and quantified by the measurement of telomere length and senescence-associated beta-galactosidase activity. Compared with nonsmokers, smoker patients were 10 years younger at the time of CABG, evidence of premature atherosclerosis. Cellular senescence was independent of telomere length and directly related to oxidative damage. EC exhibited higher expression levels of markers of oxidative stress (lipid peroxydation level and caveolin-1 mRNA), inflammation (angiopoietin-like 2 mRNA), hypoxia (vascular endothelial growth factor (VEGF)-A mRNA), and cell damage (p53 mRNA). In conclusion, a high oxidative stress environment in EC isolated from atherosclerotic chronic smokers predisposes to SIS rather than replicative senescence.

Creation, validation, and quantitative analysis of protein expression in vascular tissue microarrays

BACKGROUND

Tissue microarrays (TMAs) are collections of multiple tissue cores placed in parallel in a single acceptor block and traditionally used to investigate protein expression in neoplastic tissues. We validated the use of TMAs to investigate protein expression in vascular segments.

METHODS

Vascular tissues were collected from 100 adult subjects undergoing autopsy. A diverse set of vessels were harvested and arrayed over 17 TMAs. A total of 1377 unique tissues, each with a 1.5-mm feature size, were analyzed using histochemical and immunohistochemical (IHC) diaminobenzidine (DAB) methods.

RESULTS

Histomorphometric analysis of vascular disease demonstrated the TMA features captured the majority of the vascular alterations (intimal hyperplasia and atherosclerosis) seen in the original blood vessel section. Measurements of IHC staining intensity based on color deconvolution were used to quantify antigen abundance in defined regions of interest (ROI). Validation was performed using antibodies to connective tissue growth factor (CTGF), receptor for advanced glycation end products (AGER/RAGE), and matrix metalloproteinase 3 (MMP-3). IHC staining was highly correlated between duplicate features from the same vascular site over these three proteins.

CONCLUSION

This study validates the use of TMA technology to investigate the vascular wall utilizing staining intensity data.