The serum concentration of active transforming growth factor-beta is severely depressed in advanced atherosclerosis

TGF-[beta]1 limits plaque growth, stabilizes plaque structure, and prevents aortic dilation in apolipoprotein E-null mice

OBJECTIVE

Impairment of transforming growth factor (TGF)-beta1 signaling accelerates atherosclerosis in experimental mice. However, it is uncertain whether increased TGF-beta1 expression would retard atherosclerosis. The role of TGF-beta1 in aneurysm formation is also controversial. We tested whether overexpression of active TGF-beta1 in hyperlipidemic mice affects atherogenesis and aortic dilation.

METHODS AND RESULTS

We generated apolipoprotein E-null mice with transgenes that allow regulated overexpression of active TGF-beta1 in their hearts. Compared to littermate controls, these mice had elevated cardiac and plasma TGF-beta1, less aortic root atherosclerosis (P< or =0.002), fewer lesions in the thoracic and abdominal aortae (P< or =0.01), less aortic root dilation (P<0.001), and fewer pseudoaneurysms (P=0.02). Mechanistic studies revealed no effect of TGF-beta1 overexpression on plasma lipids or cytokines, or on peripheral lymphoid organ cells. However, aortae of TGF-beta1-overexpressing mice had fewer T-lymphocytes, more collagen, less lipid, lower expression of inflammatory cytokines and matrix metalloproteinase-13, and higher expression of tissue inhibitor of metalloproteinase-2.

CONCLUSIONS

When overexpressed in the heart and plasma, TGF-beta1 is an antiatherogenic, vasculoprotective cytokine that limits atherosclerosis and prevents aortic dilation. These actions are associated with significant changes in cellularity, collagen and lipid accumulation, and gene expression in the artery wall.

Hypercholesterolemia leads to elevated TGF-beta1 activity and T helper 3-dependent autoimmune responses in atherosclerotic mice

OBJECTIVE

The pathogenesis of atherosclerosis involves inflammation and immune reactions. Low-density lipoproteins accumulate and are oxidized (oxLDL) in the arterial intima during hypercholesterolemia, leading to activation of endothelial cells, macrophages and T cells. We have previously found that severe hypercholesterolemia can induce a switch of autoimmune responses from T helper (Th)1 to Th2 effector type in atherosclerotic apoE knockout (E0) mice. The present study was performed to investigate whether Th3 immune effector responses and their inducing cytokine, transforming growth factor-beta (TGF-beta) are affected by hypercholesterolemia.

METHODS AND RESULTS

In E0 mice fed with high cholesterol diet and in C57BL/6J mice treated with poloxamer P-407, an agent that elevates plasma cholesterol and triglycerides, severe hypercholesterolemia led to elevated circulating TGF-beta1 levels, increased TGF-beta1(+)CD4(+) Th3 cells in lesions and spleen, and increased Th3 dependent IgG2b antibodies to oxLDL. A positive correlation was observed between plasma TGF-beta1 and cholesterol levels and between plasma TGF-beta1 and IgG2b anti-oxLDL.

CONCLUSIONS

Such elevation of TGF-beta may increase the stability of plaques by inhibiting T cell responses and macrophage activation and by stimulating collagen synthesis. This new finding could be important in the regulation of immune activity, inflammation and fibrosis in the atherosclerotic plaque.

Proteomic identification and functional validation of activins and bone morphogenetic protein 11 as candidate novel muscle mass regulators

Myostatin is a secreted TGF-beta family member that controls skeletal muscle growth. Humans, cattle, and dogs carrying natural loss-of-function mutations in the myostatin gene and myostatin knockout mice exhibit significant increases in skeletal muscle mass. Treatment of adult mice with antimyostatin antibodies also resulted in significant muscle mass increases. However, myostatin-knockout mice that were treated with a soluble form of the activin type II receptor (ActRII) B increased their muscle mass by an additional 15-25%, indicating that there is at least one additional ligand, in addition to myostatin, that functions to limit muscle growth. Here, both soluble ActRII and -IIB fragment-crystallizable proteins were used to affinity purify their native ligands from human and mouse sera. Using mass spectrometry-based proteomics and in vitro binding assays we have identified and confirmed that a number of TGF-beta family members, including myostatin, activins-A, -B, and -AB, bone morphogenetic proteins (BMPs) -9, -10, and -11, bind to both ActRIIs. Many of these factors, such as BMPs-11, -9, and -10 were discovered in systemic circulation for the first time, indicating that these ligands may also act in an endocrine fashion. Using a promoter-specific gene reporter assay, we demonstrated that soluble ActRIIB fragment-crystallizable proteins can inhibit the canonical signaling induced by these ligands. In addition, like myostatin, these factors were able to block the differentiation of myoblast cells into myotubes. However, in addition to myostatin, only BMP-11, and activins-A, -B, and -AB could be blocked from inhibiting the myoblast-to-myotube differentiation with both soluble ActRIIs, thus implicating them as potential novel regulators of muscle growth.

Mechanisms of disease: the evolving role of regulatory T cells in atherosclerosis

Atherosclerosis and related complications still represent the major cause of morbidity and mortality in the western world. The mechanisms that govern the progression and destabilization of atheromatous lesions are multiple and complex. Despite their widespread use, lipid-lowering agents do not provide sufficient protection from future clinical cardiovascular-associated events. Interest in the role of immunity in atherosclerosis and support for this relationship has grown significantly over recent years. This paradigm, in which inflammation is an instrumental process in plaque development and rupture, is further supported by studies showing that immune subsets are operative in atherosclerosis. Regulatory T-cell subpopulations consist of lymphocytes--with several phenotypic markers--that share the ability to suppress, by various mechanisms, inflammatory responses. These regulatory T cells consist of subsets such as interleukin-10 secreting type I regulatory cells, type 3 effector T-helper cells that produce transforming growth factor-beta, as well as adaptive and natural CD4(+)CD25(+) regulatory T cells. In this Review, I focus on the direct and indirect evidence for the involvement of regulatory T cells in atherogenesis in experimental models and in humans. The growing knowledge of the role of regulatory T cells could result in the future development of novel therapeutic modalities to attenuate atherosclerosis and stabilize vulnerable plaques.

Genetic variation and atherosclerosis

A family history of atherosclerosis is independently associated with an increased incidence of cardiovascular events. The genetic factors underlying the importance of inheritance in atherosclerosis are starting to be understood. Genetic variation, such as mutations or common polymorphisms has been shown to be involved in modulation of a range of risk factors, such as plasma lipoprotein levels, inflammation and vascular calcification. This review presents examples of present studies of the role of genetic polymorphism in atherosclerosis.

Genetics and reverse epidemiology among patients on chronic hemodialysis

A reversal in the association between traditional and nontraditional risk factors and clinical outcomes is often encountered in patients with chronic illness, including among those with advanced chronic kidney disease (CKD) on maintenance hemodialysis (MHD). The effects of the malnutrition-inflammation complex syndrome (MICS) may play a significant role in the reversal of this risk factor-outcomes association. the MICS, this syndrome complex is not universal in its prevalence among MHD patients. The significant inter- and intra-individual differences in the prevalence of inflammation, oxidative stress, and malnutrition, indicates the influence of genetic factors in this variability. In recent years, enormous advancement in the field of molecular genetics, genomics and bioinformatics, have revolutionized studies of the genetic epidemiology of several diseases. However, genetic association studies are at a preliminary stage in the population with advanced CKD (Table 1). Preliminary studies of the impact of polyphisms in inflammation and oxidative stress-related genes and genes affecting body composition and metabolism suggest that genetic variation may indeed affect the phenotype of the MHD population. Further, some of these gene polymorphisms may also contribute to a reversal of the association between traditional risk factors, such as BMI, blood pressure, and cholesterol and clinical outcomes in this vulnerable patient population. Genetic studies in patients with advanced CKD pose enormous challenges, including recruitment of sufficient numbers of patients to achieve adequate statistical power, resolution of immense genotypic and phenotypic heterogeneity, and gene-environment and gene-gene interactions. However, well-designed adequately powered studies with carefully defined phenotypes may potentially allow definition of risk profiles characterized by combinations of relevant Single nucleotide polymorphisms in the setting of given environmental factors. Accurate risk stratification that takes into account genetic information would allow more informed targeting of pharmacologic intervention and better refined clinical trial methodologies.

Biomarkers of hepatic fibrosis, fibrogenesis and genetic pre-disposition pending between fiction and reality

Fibrosis is a frequent, life-threatening complication of most chronic liver diseases. Despite major achievements in the understanding of its pathogenesis, the translation of this knowledge into clinical practice is still limited. In particular, non-invasive and reliable (serum-) biomarkers indicating the activity of fibrogenesis are scarce. Class I biomarkers are defined as serum components having a direct relation to the mechanism of fibrogenesis, either as secreted matrix-related components of activated hepatic stellate cells and fibroblasts or as mediators of extracellular matrix (ECM) synthesis or turnover. They reflect primarily the activity of the fibrogenic process. Many of them, however, proved to be disappointing with regard to sensitivity and speci-ficity. Up to now hyaluronan turned out to be the relative best type I serum marker. Class II biomarkers comprise in general rather simple standard laboratory tests, which are grouped into panels. They fulfil most criteria for detection and staging of fibrosis and to a lesser extent grading of fibrogenic activity. More than 20 scores are currently available, among which Fibrotest™ is the most popular one. However, the diagnostic use of many of these scores is still limited and standardization of the assays is only partially realized. Combining of panel markers in sequential algorithms might increase their diagnostic validity. The translation of genetic pre-disposition biomarkers into clinical practice has not yet started, but some polymorphisms indicate a link to progression and outcome of fibrogenesis. Parallel to serum markers non-invasive physical techniques, for example, transient elastography, are developed, which can be combined with serum tests and profiling of serum proteins and glycans.

Arteriogenesis: basic mechanisms and therapeutic stimulation

Pharmacological attempts to stimulate the growth of collateral arteries (arteriogenesis) are evolving towards a new treatment option for patients with vascular occlusive diseases. This enlargement of small pre-existing anastomoses towards large conductance arteries takes place independent of local oxygen tension and is driven by changes in luminal shear stress and infiltration of circulating cells. With the increasing knowledge regarding the distinct differences between capillary sprouting (angiogenesis) and arteriogenesis, several cytokines and growth factors have been demonstrated to stimulate the growth of arterial blood vessels in preclinical models of vascular disease. However, the translation towards clinical practice remains difficult and first in-man trials show limited success. Intensive research especially regarding new drug delivery platforms and the potentially serious side effects of pro-arteriogenic therapeutics is warranted before stimulation of arteriogenesis could become a significant treatment option for vascular occlusive diseases. This review focuses on the recent advances in the field of collateral artery growth. In addition, possible means to overcome the hurdles that have hampered the clinical implementation of pro-arteriogenic therapies will be discussed.

Cholesterol suppresses cellular TGF-beta responsiveness: implications in atherogenesis

Hypercholesterolemia is a major causative factor for atherosclerotic cardiovascular disease. The molecular mechanisms by which cholesterol initiates and facilitates the process of atherosclerosis are not well understood. Here, we demonstrate that cholesterol treatment suppresses or attenuates TGF-beta responsiveness in all cell types studied as determined by measuring TGF-beta-induced Smad2 phosphorylation and nuclear translocation, TGF-beta-induced PAI-1 expression, TGF-beta-induced luciferase reporter gene expression and TGF-beta-induced growth inhibition. Cholesterol, alone or complexed in lipoproteins (LDL, VLDL), suppresses TGF-beta responsiveness by increasing lipid raft and/or caveolae accumulation of TGF-beta receptors and facilitating rapid degradation of TGF-beta and thus suppressing TGF-beta-induced signaling. Conversely, cholesterol-lowering agents (fluvastatin and lovastatin) and cholesterol-depleting agents (beta-cyclodextrin and nystatin) enhance TGF-beta responsiveness by increasing non-lipid raft microdomain accumulation of TGF-beta receptors and facilitating TGF-beta-induced signaling. Furthermore, the effects of cholesterol on the cultured cells are also found in the aortic endothelium of ApoE-null mice fed a high-cholesterol diet. These results suggest that high cholesterol contributes to atherogenesis, at least in part, by suppressing TGF-beta responsiveness in vascular cells.

Cellular, molecular and clinical aspects of vitamin E on atherosclerosis prevention

Randomised clinical trials and epidemiologic studies addressing the preventive effects of vitamin E supplementation against cardiovascular disease reported both positive and negative effects, and recent meta-analyses of the clinical studies were rather disappointing. In contrast to that, many animal studies clearly show a preventive action of vitamin E in several experimental settings, which can be explained by the molecular and cellular effects of vitamin E observed in cell cultures. This review is focusing on the molecular effects of vitamin E on the cells playing a role during atherosclerosis, in particular on the endothelial cells, vascular smooth muscle cells, monocytes/macrophages, T cells, and mast cells. Vitamin E may act by normalizing aberrant signal transduction and gene expression in antioxidant and non-antioxidant manners; in particular, over-expression of scavenger receptors and consequent foam cell formation can be prevented by vitamin E. In addition to that, the cellular effects of alpha-tocopheryl phosphate and of EPC-K1, a composite molecule between alpha-tocopheryl phosphate and l-ascorbic acid, are summarized.

Endothelial expression of endoglin in normocholesterolemic and hypercholesterolemic C57BL/6J mice before and after atorvastatin treatment

Endoglin (CD105) is a homodimeric transmembrane glycoprotein strongly related to transforming growth factor (TGF)-β signaling and many pathological states. In this study, we wanted to evaluate whether endoglin is expressed in normocholesterolemic and hypercholesterolemic C57BL/6J mice as well as whether it is affected by atorvastatin treatment in these mice. C57BL/6J mice were fed with chow diet or an atherogenic diet for 12 weeks after weaning. In 2 atorvastatin-treated groups, mice were fed the same diets (chow or atherogenic) as described above except atorvastatin was added at the dosage of 10 mg·kg–1·day–1for the last 8 weeks before euthanasia. Biochemical analysis of blood samples revealed that administration of atherogenic diet significantly increased levels of total cholesterol, VLDL, LDL, and decreased levels of HDL. Atorvastatin treatment resulted in a significant decrease in total cholesterol and VLDL only in mice fed by atherogenic diet. Quantitative stereological analysis revealed that atorvastatin significantly decreased endothelial expression of endoglin in C57BL/6J mice fed the atherogenic diet. In conclusion, we demonstrated that endothelial expression of endoglin is upregulated by hypercholesterolemia and decreased by the hypolipidemic effect of atorvastatin in C57BL/6J mice, suggesting that endoglin expression could be involved in atherogenesis.

'Correction:' Serum transforming growth factor beta-1 (TGF-beta-1) levels in diabetic patients are not associated with pre-existent coronary artery disease

Background

The association between TGF-β1 levels and long-term major adverse cardiovascular events (MACE) in patients with coronary artery disease (CAD) is controversial. No study specifically addressed patients with CAD and diabetes mellitus (DM). The association between TGF-β1 levels and long-term major adverse cardiovascular events (MACE) in patients with coronary artery disease (CAD) is controversial. No study specifically addressed patients with CAD and diabetes mellitus (DM).

Methods

Patients (n = 135, 30–80 years) referred for coronary angiography were submitted to clinical and laboratory evaluation, and the coronary angiograms were evaluated by two operators blinded to clinical characteristics. CAD was defined as the presence of a 70% stenosis in one major coronary artery, and DM was characterized as a fasting glycemia > 126 mg/dl or known diabetics (personal history of diabetes or previous use of anti-hyperglycemic drugs or insulin). Based on these criteria, study patients were classified into four groups: no DM and no CAD (controls, C n = 61), DM without CAD (D n = 23), CAD without DM (C-CAD n = 28), and CAD with DM (D-CAD n = 23). Baseline differences between the 4 groups were evaluated by the χ² test for trend (categorical variables) and by ANOVA (continuous variables, post-hoc Tukey). Patients were then followed-up during two years for the occurrence of MACE (cardiac death, stroke, myocardial infarction or myocardial revascularization). The association of candidate variables with the occurrence of 2-year MACE was assessed by univariate analysis.

Results

The mean age was 58.2 ± 0.9 years, and 51% were men. Patients with CAD had a higher mean age (p = 0.011) and a higher percentage were male (p = 0.040). There were no significant baseline differences between the 4 groups regarding hypertension, smoking status, blood pressure levels, lipid levels or inflammatory markers. TGF-β1 was similar between patients with or without CAD or DM (35.1 ×/÷ 1.3, 33.6 ×/÷ 1.6, 33.9 ×/÷ 1.4 and 31.8 ×/÷ 1.4 ng/ml in C, D, C-CAD and D-CAD, respectively, p = 0.547). In the 2-year follow-ip, independent predictors of 2-year MACE were age (p = 0.007), C-reactive protein (p = 0.048) and systolic blood pressure (p = 0.008), but not TGF-β1.

Conclusion

Serum TGF-β1 was not associated with CAD or MACE occurrence in patients with or without DM.

Increased plasma levels of cystatin C and transforming growth factor-beta1 in patients with coronary artery ectasia: can there be a potential interaction between cystatin C and transforming growth factor-beta1

Cystatin C, known as an inhibitor of the cathepsin family of cysteine proteases, has been evaluated in several cardiovascular disorders such as atherosclerosis and acute myocardial infarction. The potential interaction between transforming growth factor-beta1 and cystatin C has also been demonstrated in some cell types. Accordingly, we aimed to compare the plasma levels of cystatin C and transforming growth factor-beta1 in patients with coronary artery ectasia coexisting with coronary artery disease and those with coronary artery disease alone. Thirty-nine patients with coronary artery ectasia and coronary artery disease and 35 age and sex-matched patients with coronary artery disease alone were prospectively enrolled in the study. Blood samples of all patients and control participants for measuring plasma cystatin C and transforming growth factor-beta1 levels were drawn>or=24 h after the coronary angiography. Cystatin C concentrations in plasma were measured by latex-enhanced reagent on a Behring Nephelometer II. Plasma levels of transforming growth factor-beta1 were measured by using transforming growth factor-beta1 enzyme-linked immunosorbent assay kit (BioSource International, Inc., Camarillo, California, USA). Plasma level of cystatin C was significantly higher in patients with coronary artery ectasia+coronary artery disease than in patients with coronary artery disease alone (1.05+/-0.30 mg/dl vs. 0.92+/-0.18 mg/mdl, P=0.025, respectively). Transforming growth factor-beta1 was also found to be significantly higher in patients with coronary artery ectasia+coronary artery disease compared with those with coronary artery disease (2.47+/-0.43 vs. 2.22+/-0.43 pg/ml, P=0.02, respectively). The plasma level of cystatin C was significantly but weakly correlated with that of transforming growth factor-beta1 (r=0.217 P=0.02). We conclude that plasma levels of cystatin C and transforming growth factor-beta1 are significantly higher in patients with combined coronary artery ectasia and coronary artery disease than in those with coronary artery disease. Correlation between transforming growth factor-beta1 and cystatin C may also suggest that pathogenesis of coronary artery ectasia might have some different pathways from atherosclerosis with respect to the regulation of extracellular matrix remodeling. Therefore, the role of cystatin in the pathogenesis of coronary artery ectasia and its potential interaction with transforming growth factor-beta1 should be evaluated in further studies.

The role of Smad3-dependent TGF-beta signal in vascular response to injury

Transforming growth factor (TGF)-beta is a multifunctional cytokine involved in the regulation of proliferation, differentiation, migration, and survival of many different cell types. The role of TGF-beta in atherosclerosis has been intensively studied, but the precise function of the downstream signals in this disease entity remains unclear. We recently discovered that mice lacking Smad3, a major downstream mediator of TGF-beta, show enhanced neointimal hyperplasia with decreased matrix deposition in response to vascular injury. This review summarizes the current view on involvement of TGF-beta in atherosclerotic vascular disease and discusses the role of Smad3-dependent TGF-beta signal in vascular response to injury.

TGF-β1: a novel target for cardiovascular pharmacology

Transforming growth factor beta-1 (TGF-beta1) plays a key role in cardiovascular disease by a process which allows the loss of its protective properties. The first therapeutic attempt to restore its function by selectively designed novel drugs are being made. In addition, it has been recognized that the TGF-beta1 pathway is involved in the vascular mechanism of action of some current clinical drugs, such as acetylsalicylic acid, thiazolidinediones and statins. The aim of this paper is to review the possible value of TGF-beta1 as both a disease marker and a therapeutical target for cardiovascular disease.

Elevated serum soluble endoglin (sCD105) decreased during extracorporeal elimination therapy for familial hypercholesterolemia

Extracorporeal elimination is a method of LDL-lowering therapy that is used in severe familial hypercholesterolemia (FH) after other therapeutic approaches have failed. There are currently no universally accepted biomarkers that would allow determining necessary intensity of therapy and frequency of future therapeutic interventions. An ideal tool for immediate evaluation would be a readily measurable serum marker. We hypothesized that soluble endoglin (sCD105), a recently described indicator of endothelial dysfunction, may represent such a tool. Eleven patients with FH (three homozygous, eight heterozygous; Fredrickson type IIa, IIb) that have been monitored for 4.5+/-2.8 years were treated; eight by LDL-apheresis and three by hemorheopheresis. 40 sCD105 measurements were done, before and after two consecutive elimination procedures. Baseline serum sCD105 levels were significantly higher in the patients (5.74+/-1.47 microg/l in series I, 6.85+/-1.85 microg/l in series II) than in the control group (3.85+/-1.25 microg/l). They decreased to normal after LDL-elimination (p=0.0003) in all except for one patient. This return to normal was not due to a non-specific capture of endoglin in adsorption or filtration columns as demonstrated by measurement of sCD105 before and after passage through the elimination media. We conclude that the soluble endoglin levels in patients with severe FH remain elevated despite long-term intensive therapy and that they decrease after extracorporeal elimination. Endoglin can therefore serve as a marker for evaluation of the treatment efficacy and of the decreased atherosclerotic activity in patients with FH treated by extracorporeal LDL-cholesterol elimination.

Indoleamine 2,3-dioxygenase enzyme activity correlates with risk factors for atherosclerosis: the Cardiovascular Risk in Young Finns Study

Indoleamine 2,3 dioxygenase (IDO), an enzyme involved in the catabolism of tryptophan, suppresses T cell activity and is up-regulated by various inflammatory stimuli. The ratio of kynurenine, the main metabolite of tryptophan, to tryptophan (kyn/trp) reflects IDO activity. We calculated IDO activity and measured carotid intima-media thickness (IMT), a presymptomatic predictor of atherosclerosis, in 986 young adults (544 female, 442 male) for whom data on levels of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride, high sensitive C-reactive protein (CRP), body mass index (BMI), waist circumference, waist-to-hip ratio, systolic and diastolic blood pressure and smoking habits were available. IDO activity correlated significantly with IMT in female subjects, but not in males. In a multivariate linear regression model, IDO did not correlate independently with IMT in female subjects. However, IDO activity correlated significantly with several risk factors for atherosclerosis in females, i.e. with age, LDL-C, BMI, weakly with CRP and inversely with HDL-C and triglyceride. In males IDO activity correlated significantly with CRP and inversely with HDL-C. In conclusion, our results suggest that the IDO enzyme is involved in the immune regulation of early atherosclerosis, particularly in young female adults, and could constitute a novel marker of immune activation in early atherosclerosis in females.

Low transforming growth factor-beta1 serum levels in idiopathic male osteoporosis

INTRODUCTION

Although the etiology of osteoporosis is different between men and women, the underlying pathophysiological mechanism is similar, namely an absolute or relative increase in bone resorption, leading to progressive bone loss. Transforming growth factor (TGF)-beta1 is a growth factor in human bone, which is produced by osteoblasts, and which has various effects on osteoclasts and osteoblasts. The aim of our study was to determine serum TGF-beta1 levels in male patients with idiopathic osteoporosis.

METHODS

Twenty five males with idiopathic osteoporosis and 25 age-matched controls were studied. Osteoporosis was defined by a T score of <-2.5 in the lumbar spine or at the femoral neck. We measured levels of TGF-beta1, estradiol, total and bioactive testosterone. Various markers of bone remodeling were also measured.

RESULTS

TGF-beta1 was significantly lower in osteoporotic patients than in controls (3.706 ng/dl, 25-75 percentiles: 2.81-5.33 vs 8.659 ng/dl, 25-75 percentiles: 4.837-11.835; p=0.000). Moreover, TGF-beta1 levels were positively correlated with bone mineral density (BMD) at the femoral neck (r=0.439, p=0.028), and at the lumbar spine (r=0.41, p=0.042). No correlation was found between serum estradiol, testosterone and TGF-beta1 levels.

DISCUSSION

Serum TGF-beta1 levels are depressed in osteoporotic men and are positively correlated with hip and spine BMD. The results of our study suggest that TGF-beta1 may play a role in the pathogenesis of idiopathic male osteoporosis.

Transforming growth factor-beta-regulated expression of genes in macrophages implicated in the control of cholesterol homoeostasis

The regulation of macrophage cholesterol homoeostasis is of crucial importance in the pathogenesis of atherosclerosis, an underlying cause of heart attack and stroke. Several recent studies have revealed a critical role for the cytokine TGF-beta (transforming growth factor-beta), a key regulator of the immune and inflammatory responses, in atherogenesis. We discuss here the TGF-beta signalling pathway and its role in this disease along with the outcome of our recent studies on the action of the cytokine on the expression of key genes implicated in the uptake or efflux of cholesterol by macrophages and the molecular mechanisms underlying such regulation.

Fat Cell‐Derived Modulators of Vascular Cell Pathophysiology: The List Keeps Growing

Independent of the association of obesity with dyslipidemia, hypertension, and increased propensity for diabetes, fatness per se is increasingly recognized as a cardiovascular offender. That adipose tissue releases a wide range of adipokines, growth factors, enzymes, and enzyme substrates linked to vascular injury provides a plausible explanation for the role of fat in vascular disease: tumor necrosis factor-alpha, leptin, resistin, interleukin-1, -6, -8, and -18, serum amyloid A, monocyte chemoattractant protein I, macrophage inhibitory factor, aortic carboxypeptidase, hepa-rin-binding epidermal growth factor-like growth factor, vascular endothelial growth factor, transforming growth factor beta, angiotensinogen, cathepsin S, estradiol, cortisol, mineralocorticoid releasing factor, and calcitonin peptides are probable fat-derived prothrombotic, proinflammatory, and proatherosclerotic agents acting in a paracrine and/or endocrine manner. Other adipocyte products such as adiponectin, transforming growth factor beta, and interleukin-10 exert some antiatherogenic effects. The following is a short overview of how adipose tissue products affect the vasculature.

D-glucose stimulation ofL-arginine transport and nitric oxide synthesis results from activation of mitogen-activated protein kinases p42/44 and Smad2 requiring functional type II TGF-β receptors in human umbilical vein endothelium

Elevated extracellular D-glucose increases transforming growth factor beta1 (TGF-beta1) release from human umbilical vein endothelium (HUVEC). TGF-beta1, via TGF-beta receptors I (TbetaRI) and TbetaRII, activates Smad2 and mitogen-activated protein kinases p44 and p42 (p42/44(mapk)). We studied whether D-glucose-stimulation of L-arginine transport and nitric oxide synthesis involves TGF-beta1 in primary cultures of HUVEC. TGF-beta1 release was higher ( approximately 1.6-fold) in 25 mM (high) compared with 5 mM (normal) D-glucose. TGF-beta1 increases L-arginine transport (half maximal effect approximately 1.6 ng/ml) in normal D-glucose, but did not alter high D-glucose-increased L-arginine transport. TGF-beta1 and high D-glucose increased hCAT-1 mRNA expression ( approximately 8-fold) and maximal transport velocity (V(max)), L-[(3)H]citrulline formation from L-[(3)H]arginine (index of NO synthesis) and endothelial NO synthase (eNOS) protein abundance, but did not alter eNOS phosphorylation. TGF-beta1 and high D-glucose increased p42/44(mapk) and Smad2 phosphorylation, an effect blocked by PD-98059 (MEK1/2 inhibitor). However, TGF-beta1 and high D-glucose were ineffective in cells expressing a truncated, negative dominant TbetaRII. High D-glucose increases L-arginine transport and eNOS expression following TbetaRII activation by TGF-beta1 involving p42/44(mapk) and Smad2 in HUVEC. Thus, TGF-beta1 could play a crucial role under conditions of hyperglycemia, such as gestational diabetes mellitus, which is associated with fetal endothelial dysfunction.

Repair of the injury to respiratory epithelial cells characteristic of asthma is stimulated by Allomyrina dichotoma agglutinin specific serum glycoproteins

BACKGROUND

The airway epithelium acts as a protective barrier, separating the external environment from the underlying tissue. Daily challenges result in damage to the epithelium that, in normal individuals, is quickly and effectively repaired. In respiratory diseases, such as asthma, this repair is compromised. Following injury to the epithelium, plasma leaks into the airway lumen acting as a protective protein cap. Carbohydrates are mediators of epithelial repair, however, the associated regulatory proteins remain unknown.

OBJECTIVE

To identify mediators of epithelial repair based on their carbohydrate moieties using an in vitro wound repair culture model of human airway epithelial cells (1HAEo(-)).

METHODS

Using the lectin Allomyrina dichotoma agglutinin (AlloA) as a tool, ligands essential in the repair of damaged epithelium were characterized. AlloA was subsequently used to purify and identify a glycoprotein associated with epithelial repair.

RESULTS

The addition of AlloA to the media of mechanically wounded monolayers inhibited repair. Fetuin, a highly glycosylated serum protein, was identified as a glycoprotein bound by AlloA. The addition of fetuin to serum starved monolayers stimulated wound closure.

CONCLUSION

These results indicate that following mechanical injury to the epithelium, serum glycoproteins, not only provide a protective barrier, but also are involved in the initiation of wound closure.

Polymorphisms of TGF-beta1 in cystic fibrosis patients

There is a significant phenotypic variance among cystic fibrosis (CF) patients. Due to the role of TGF-beta1 in fibrotic processes we investigated its role in CF pathogenesis. TGF-beta 1 codons 10 and 25 were genotyped in 118 Czech CF patients and 268 controls by PCR-ARMS. Difference between CF and controls was found at codon 10, lower frequency of T/T homozygotes, and codon 25, higher frequency of G/C heterozygotes. We did not prove the association of TGF-beta1 polymorphisms and lung function in CF, however, the TT (codon 10)/GG (codon 25) genotype was preferentially associated with CF-related liver disease and diabetes. Independent of the TGF-beta1 genotype, production of cytokine was higher in patients than in controls with the notable exception of very low levels in Burkholderia cepacia complex colonized patients. In CF, both extremes, highest or lowest TGF-beta 1 production, were associated with impaired lung function.

TGF-beta 1 polymorphisms and risk of myocardial infarction and stroke: the Rotterdam Study

BACKGROUND AND PURPOSE

Inflammation plays a pivotal role in the pathogenesis of atherosclerosis and of cardiovascular and cerebrovascular complications. Transforming growth factor-beta1 (TGF-beta1) is a pleiotropic cytokine with a central role in inflammation. Little is known of the relation of variations within the gene and risk of cardiovascular and cerebrovascular disease. We therefore investigated 5 polymorphisms in the TGF-beta1 gene (-800 G/A, -509 C/T, codon 10 Leu/Pro, codon 25 Arg/Pro, and codon 263 Thr/Ile) in relation to the risk of myocardial infarction and stroke in a population-based study.

METHODS

Participants (N=6456) of the Rotterdam Study were included in the current study. Analyses of the relations of genotypes with the risk of myocardial infarction and stroke were performed according to Cox proportional-hazards methods. All analyses were adjusted for age, sex, conventional cardiovascular risk factors, and medical history.

RESULTS

We found no association with the risk of myocardial infarction. A significantly increased risk of stroke was found, associated with the T allele of the -509 C/T polymorphism (relative risk, 1.26; (95% CI, 1.06 to 1.49) and the Pro variant of the codon 10 polymorphism (relative risk, 1.24; 95% CI, 1.04 to 1.48).

CONCLUSIONS

No association between the TGF-beta1 polymorphisms and myocardial infarction was observed; however, the -509 C/T and codon 10 Leu/Pro polymorphisms were associated with the risk of stroke.

Atherosclerosis: immune and inflammatory aspects

This review article discusses the historical origin of our continuously evolving model of the etiology of atherosclerotic cardiovascular disease. The basic molecular biologic concepts underlying the development of coronary artery disease and the dynamic connection between the immune system and arterial integrity are explored. Emphasis is placed on the role of inflammation as a driving force in the process of atherosclerosis and vascular endothelium as a modulating factor in the pathogenesis of coronary artery disease.

TGF-beta1 generates a specific multicomponent extracellular matrix in human coronary SMC

BACKGROUND

Transforming growth factor (TGF-beta(1)) is postulated to play an important role in maintaining the structure and function of arterial tissue and protection against development of arteriosclerosis. The TGF-beta(1)-induced production of a stable extra-cellular matrix-rich plaque phenotype is suggested to be part of the protection against a switch to an unstable rupture-prone arteriosclerotic plaque.

MATERIALS AND METHODS

This study addresses the question of whether the expression profile and the type of extra-cellular matrix (ECM) generated by TGF-beta(1) stimulation have the structural feature of a fibril-rich stable matrix. Seventeen genes codings for ECM components of human coronary smooth muscle cells (SMCs) after a 24-h stimulation by TGF-beta(1) have been analyzed.

RESULTS

Real-time RT-PCR was used to quantify the mRNA of genes under investigation. It was found that after TGF-beta(1) stimulation (a) the up-regulation of COL1A1-specific mRNA was associated with increased [(3)H]proline incorporation into the alpha-1 and -2 chains of collagen type I, (b) the up-regulation of biglycan- and syndecan-1-specific mRNA corresponded to an increased [(35)S]sulphate and [4,5-(3)H]leucine incorporation into the biglycan molecule and to an increase of syndecan-1 protein, (c) the up-regulated FGF-2 gene accounted predominantly for the ECM-bound subfraction of FGF-2-protein and (d) fibronectin and thrombospondin exhibited a significantly higher mRNA level. In contrast collagen XIV, a minor collagen type, and the proteoglycan decorin were down-regulated. The down-regulated decorin changed its structure by elongation and reduced GlcA to IdoA epimerization of the dermatan sulphate side-chain as judged by [(35)S]sulphate metabolic labelling experiments. No significant changes in response to TGF-beta(1) were observed for the collagen types III, VI and XVI, for versican, perlecan and the syndecans-2 and -4.

CONCLUSIONS

It was concluded from the data that the TGF-beta(1)-induced formation of a highly specific multicomponent extra-cellular matrix on coronary arterial SMCs could provide in vivo mechanical strength to the neointima in arteriosclerotic lesions and to the fibrous cap overlying the lipid core.

Transforming growth factor-beta regulation of immune responses

Transforming growth factor-beta (TGF-beta) is a potent regulatory cytokine with diverse effects on hemopoietic cells. The pivotal function of TGF-beta in the immune system is to maintain tolerance via the regulation of lymphocyte proliferation, differentiation, and survival. In addition, TGF-beta controls the initiation and resolution of inflammatory responses through the regulation of chemotaxis, activation, and survival of lymphocytes, natural killer cells, dendritic cells, macrophages, mast cells, and granulocytes. The regulatory activity of TGF-beta is modulated by the cell differentiation state and by the presence of inflammatory cytokines and costimulatory molecules. Collectively, TGF-beta inhibits the development of immunopathology to self or nonharmful antigens without compromising immune responses to pathogens. This review highlights the findings that have advanced our understanding of TGF-beta in the immune system and in disease.

The immune response in atherosclerosis: a double-edged sword

Immune responses participate in every phase of atherosclerosis. There is increasing evidence that both adaptive and innate immunity tightly regulate atherogenesis. Although improved treatment of hyperlipidaemia reduces the risk for cardiac and cerebral complications of atherosclerosis, these remain among the most prevalent of diseases and will probably become the most common cause of death globally within 15 years. This Review focuses on the role of immune mechanisms in the formation and activation of atherosclerotic plaques, and also includes a discussion of the use of inflammatory markers for predicting cardiovascular events. We also outline possible future targets for prevention, diagnosis and treatment of atherosclerosis.

[Immunological aspects of atherosclerosis]

The pathogenesis of atherosclerosis remains incompletely understood. Accumulation of oxidized lipoproteins (oxLDL) within the vascular wall drives a related immune response very early during the disease course. Such an immune response is self-amplified and eventually escapes from physiologic control mechanisms. Certain lymphocytes may become pathogenic. B cells play a protective role by producing antibodies able to neutralize oxLDL. Elucidation of the immune control mechanisms in atherosclerosis will open the way to new therapeutic perspectives.

Cytokines in Atherosclerosis: Pathogenic and Regulatory Pathways

Atherosclerosis is a chronic disease of the arterial wall where both innate and adaptive immunoinflammatory mechanisms are involved. Inflammation is central at all stages of atherosclerosis. It is implicated in the formation of early fatty streaks, when the endothelium is activated and expresses chemokines and adhesion molecules leading to monocyte/lymphocyte recruitment and infiltration into the subendothelium. It also acts at the onset of adverse clinical vascular events, when activated cells within the plaque secrete matrix proteases that degrade extracellular matrix proteins and weaken the fibrous cap, leading to rupture and thrombus formation. Cells involved in the atherosclerotic process secrete and are activated by soluble factors, known as cytokines. Important recent advances in the comprehension of the mechanisms of atherosclerosis provided evidence that the immunoinflammatory response in atherosclerosis is modulated by regulatory pathways, in which the two anti-inflammatory cytokines interleukin-10 and transforming growth factor-β play a critical role. The purpose of this review is to bring together the current information concerning the role of cytokines in the development, progression, and complications of atherosclerosis. Specific emphasis is placed on the contribution of pro- and anti-inflammatory cytokines to pathogenic (innate and adaptive) and regulatory immunity in the context of atherosclerosis. Based on our current knowledge of the role of cytokines in atherosclerosis, we propose some novel therapeutic strategies to combat this disease. In addition, we discuss the potential of circulating cytokine levels as biomarkers of coronary artery disease.

CD44 and TGFbeta1 synergise to induce expression of a functional NADPH oxidase in promyelocytic cells

Bone marrow stromal cells produce large amounts of extracellular matrix and cytokines. Amongst them, hyaluronan, a glycosaminoglycan and ligand for the cell surface molecule CD44, and TGFbeta1, a cytokine particularly important in monocyte differentiation. We have studied in vitro the role of hyaluronan and TGFbeta1 in the differentiation process of U937 monocytic progenitor cells. We provide evidence that, in the presence of whole blood-derived serum, the addition of hyaluronan is sufficient to induce the expression of NADPH-oxidase components but not of other monocytic markers (CD14, CD11b, and VLA-4). In the presence of plasma-derived serum, besides hyaluronan, the additional presence of TGFbeta1 was required for the expression of all of the components of the NADPH oxidase. We further show that hyaluronan mediates its effect through CD44. We conclude that cell matrix factors act cooperatively with cytokines to induce the expression of the components of the NADPH-oxidase in monocytic progenitor cells.

A pattern of anti-carbohydrate antibody responses present in patients with advanced atherosclerosis

We have previously shown that an antibody pool present in normal human serum binds cytokine receptors in vitro and may therefore interfere with assays that capture cytokines using their receptors. Here we show that this antibody pool is the same as the natural antibody termed anti-gal, that binds to the alpha-galactosyl carbohydrate epitope (alpha-gal) and which is the predominant obstacle to xenotransplantation. We report that there are high levels of IgD anti alpha-gal in most volunteers, in addition to the IgG2, IgA and IgM immunoglobulin isotypes against alpha-gal previously described. To determine if anti-gal may interfere with assays that depend on capture of cytokine with its receptor, we measured levels of several anti-carbohydrate antibodies in a cohort of patients with advanced atherosclerosis that had previously been used to measure levels of active TGF-beta using such an assay. For many isotype / carbohydrate combinations, there is a large and significant difference between the levels of anti-carbohydrate antibodies in patients with atherosclerosis and controls, after adjustment for age, sex and blood group. These results are similar to the previous data obtained for active TGF-beta, and therefore we cannot discount the possibility that anti-gal contributed to the previous data. Following further adjustment for several risk factors associated with cardiovascular disease, several anti-carbohydrate antibodies were still significantly different between patients and controls. Therefore, anti-carbohydrate antibodies may represent a new class of risk factors that may be associated with presence of advanced atherosclerosis, although larger studies will be required to confirm this hypothesis.

Significant Expression of Endoglin (CD105), TGFβ-1 and TGFβ R-2 in the Atherosclerotic Aorta: An Immunohistological Study

To date, the glycoprotein endoglin and its receptor complex, formed between TGFbeta and TGFbeta R-2, have been studied in tumor angiogenesis. The purpose of this study is to investigate the expression profile of endoglin and its receptor complex in human atherosclerotic lesions, and compare it to that in non-atherosclerotic tissues. Twenty-six atherosclerotic lesions and twenty-six non-atherosclerotic aortic tissues were collected from thirty-six autopsy cases. Indirect immunohistochemical staining was performed to detect the presence of endoglin, TGFbeta-1, and TGFbeta R-2 proteins in aortic tissues. Endoglin expression was observed in smooth muscle cells (SMC), macrophages and endothelial cells of aortic atherosclerotic lesions. The levels of TGFbeta-1 and TGFbeta R-2 were increased in the intimal matrices, smooth muscle cells, and macrophages, as well as in endothelial cells. The expression levels of endoglin, TGFbeta-1, and TGFbeta R-2 were higher in atherosclerotic lesions than in non-atherosclerotic aortic tissues (p < 0.0001), and there was a correlation among the expression of endoglin, TGFbeta-1, and TGFbeta R-2 in atherosclerotic aortic lesions (p < 0.001). Endoglin or its receptor complex may participate in the atherogenesis.

Wound healing morbidity in STS patients treated with preoperative radiotherapy in relation to in vitro skin fibroblast radiosensitivity, proliferative capacity and TGF-β activity

BACKGROUND AND PURPOSE

In a recent study, we demonstrated that the ability of dermal fibroblasts, obtained from soft tissue sarcoma (STS) patients, to undergo initial division in vitro following radiation exposure correlated with the development of wound healing morbidity in the patients following their treatment with preoperative radiotherapy. Transforming growth factor beta (TGF-beta) is thought to play an important role in fibroblast proliferation and radiosensitivity both of which may impact on wound healing. Thus, in this study we examined the interrelationship between TGF-beta activity, radiosensitivity and proliferation of cultured fibroblasts and the wound healing response of STS patients after preoperative radiotherapy to provide a validation cohort for our previous study and to investigate mechanisms.

PATIENTS AND METHODS

Skin fibroblasts were established from skin biopsies of 46 STS patients. The treatment group consisted of 28 patients who received preoperative radiotherapy. Eighteen patients constituted a control group who were either irradiated postoperatively or did not receive radiation treatment. Fibroblast cultures were subjected to the colony forming and cytokinesis-blocked binucleation assays (low dose rate: approximately 0.02 Gy/min) and TGF-beta assays (high dose-rate: approximately 1.06 Gy/min) following gamma-irradiation. Fibroblast radiosensitivity and initial proliferative ability were represented by the surviving fraction at 2.4 Gy (SF(2.4)) and binucleation index (BNI), respectively. Active and total TGF-beta levels in fibroblast cultures were determined using a biological assay. Wound healing complication (WHC), defined as the requirement for further surgery or prolonged deep wound packing, was the clinical endpoint examined.

RESULTS

Of the 28 patients treated with preoperative radiotherapy, 8 (29%) had wound healing difficulties. Fibroblasts from patients who developed WHC showed a trend to retain a significantly higher initial proliferative ability after irradiation compared with those from individuals in the treatment group with normal wound healing, consistent with the results of our previous study. No link was observed between fibroblast radiosensitivity and WHC. Neither active nor total TGF-beta levels in cultures were significantly affected by irradiation. Fibroblast proliferation in unirradiated and irradiated cultures, as well as radiosensitivity, was not influenced by TGF-beta content. TGF-beta expression in fibroblast cultures did not reflect wound healing morbidity.

CONCLUSIONS

These data are consistent with our previous study and combined the results suggest that in vitro fibroblast proliferation after irradiation may be a useful predictor of wound healing morbidity in STS patients treated with preoperative radiotherapy. TGF-beta levels in culture do not predict WHC, suggesting that the role of TGF-beta in wound healing is likely controlled by other in vivo factors.

Different effects of simvastatin and losartan on cytokine levels in coronary artery disease

BACKGROUND AND OBJECTIVE

Use of HMG-CoA reductase inhibitors (statins) and angiotensin II type 1 (AT(1)) receptor antagonists reduces the incidence of cardiovascular events. The cytokines macrophage colony-stimulating factor (M-CSF) and transforming growth factor (TGF)-beta may exert proatherogenic and antiatherogenic effects, respectively. In this study, we examined whether treatment with a statin or an AT(1) receptor antagonist alters M-CSF and TGF-beta levels in patients with coronary artery disease.

METHODS

Twenty-seven consecutive patients with coronary artery disease were randomly assigned to the following three treatment groups for 8 weeks: simvastatin 5 mg/day (n = 10); losartan 50 mg/day (n = 9); or control (usual treatment; n = 8). Blood samples were collected before and after treatment.

RESULTS

Clinical characteristics and baseline cytokine levels were comparable among the three groups. Serum levels of M-CSF were significantly decreased only in the simvastatin group (from 403 +/- 71 to 303 +/- 116 pg/mL; p = 0.009). Plasma levels of TGF-beta were significantly increased only in the losartan group (from 5.01 +/- 1.13 to 7.50 +/- 3.83 ng/mL; p = 0.021). Simvastatin decreased serum M-CSF levels independently of changes in total cholesterol or low-density lipoprotein-cholesterol.

CONCLUSIONS

The results of this study indicate that simvastatin decreases serum levels of M-CSF while losartan increases plasma levels of TGF-beta, suggesting that the two drugs may have different anti-atherosclerotic properties.

Kruppel-like factor 4 is a mediator of proinflammatory signaling in macrophages

Activation of macrophages is important in chronic inflammatory disease states such as atherosclerosis. Proinflammatory cytokines such as interferon-gamma (IFN-gamma), lipopolysaccharide (LPS), or tumor necrosis factor-alpha can promote macrophage activation. Conversely, anti-inflammatory factors such as transforming growth factor-beta1 (TGF-beta1) can decrease proinflammatory activation. The molecular mediators regulating the balance of these opposing effectors remain incompletely understood. Herein, we identify Kruppel-like factor 4 (KLF4) as being markedly induced in response to IFN-gamma, LPS, or tumor necrosis factor-alpha and decreased by TGF-beta1 in macrophages. Overexpression of KLF4 in J774a macrophages induced the macrophage activation marker inducible nitric-oxide synthase and inhibited the TGF-beta1 and Smad3 target gene plasminogen activator inhibitor-1 (PAI-1). Conversely, KLF4 knockdown markedly attenuated the ability of IFN-gamma, LPS, or IFN-gamma plus LPS to induce the iNOS promoter, whereas it augmented macrophage responsiveness to TGF-beta1 and Smad3 signaling. The KLF4 induction of the iNOS promoter is mediated by two KLF DNA-binding sites at -95 and -212 bp, and mutation of these sites diminished induction by IFN-gamma and LPS. We further provide evidence that KLF4 interacts with the NF-kappaB family member p65 (RelA) to cooperatively induce the iNOS promoter. In contrast, KLF4 inhibited the TGF-beta1/Smad3 induction of the PAI-1 promoter independent of KLF4 DNA binding through a novel antagonistic competition with Smad3 for the C terminus of the coactivator p300/CBP. These findings support an important role for KLF4 as a regulator of key signaling pathways that control macrophage activation.

Circulating levels of active transforming growth factor β1 are reduced in diffuse cutaneous systemic sclerosis and correlate inversely with the modified Rodnan skin score

OBJECTIVES

To determine the relationship between clinical features and circulating levels of active transforming growth factor (TGF) beta1 in the major subsets of systemic sclerosis (SSc).

METHODS

In a cross-sectional study cases of diffuse cutaneous SSc (dose) (n = 27) or limited cutaneous SSc (dose) (n = 20) were compared with healthy controls (n = 22). Active and total TGFbeta1 was measured in serum and plasma by a high-sensitivity enzyme-linked immunosorbent assay.

RESULTS

There were no significant differences between levels of total serum TGFbeta1. However, cases of dcSSc had lower levels of active TGFbeta1 than cases of lcSSc or controls. In addition, more cases of dcSSc (18/27; 66%, P < 0.025) had no detectable active TGFbeta1 than controls (7/22, 32%) or lcSSc (7/20, 35%). In dcSSc, serum active TGFbeta1 levels correlated negatively with skin score and positively with disease duration.

CONCLUSIONS

Contrary to expectation, levels of active TGFbeta1 are reduced in dcSSc and this correlates with two variables known to associate with disease activity, shorter duration and more extensive skin sclerosis. This suggests that active TGFbeta1 may be sequestered in active involved SSc skin and that serum levels are reduced despite strong evidence implicating TGFbeta isoforms in the pathogenesis of fibrosis. Our findings may have implications for systemic TGFbeta-trapping therapies in this disease.

Impact of cytokine gene polymorphism on cardiovascular risk in renal transplant recipients

Cardiovascular events are the leading causes of morbidity and mortality in renal transplant recipients (RTR). Given the role of inflammation in atherosclerosis, the contribution of functional polymorphisms of cytokines to cardiovascular diseases (CVD) was assessed in RTR in this study. Polymorphisms of tumour necrosis factor alpha (TNF-alpha) gene [-308 (G-->A), -238 (G-->A)], interleukin-10 (IL-10) gene [-1082(A-->G), -819 (T-->C), -592 (A-->C)], transforming growth factor beta 1 (TGF-beta1) gene [codon 10 (T-->C), codon 25 (G-->C)], carotis intima media thickness (CIMT), left ventricular mass index (LVMI), 24-h ambulatory blood pressure and serum lipoprotein homocysteine level, erythrocyte sedimentation rate, serum C-reactive protein (CRP) and serum fibrinogen level of RTR were determined. Seventy-two RTR (26 cadaveric allograft, 46 living-related allograft, 43 male, 29 female) were included in this study. LVMI were similar in TNF-alpha, IL-10 and TGF-beta1 genotypes. Right and left CIMT were higher in TT genotype (n = 16) than CT (n = 46) and CC (n = 10) genotypes of TGF-beta1 codon 10 (T-->C) gene polymorphism (RCIMT, 7.7 +/- 2.2 mm vs. 7.0 +/- 1.4 mm vs. 5.9 +/- 1.4 mm, P = 0.025; LCIMT, 8.5 +/- 2.5 mm vs. 7.0 +/- 1.3 mm vs. 6.1 +/- 1.2 mm, P = 0.002). Lipoprotein (a) level of TT genotype (35.5 +/- 22.5 mg/dl) was higher than CC (4.1 +/- 2.8 mg/dl) and CT (20.4 +/- 11.2 mg/dl) genotypes of TGF-beta1 codon 10 (T-->C) gene polymorphism (P = 0.037). High producers of cytokine IL-10 -1082 [GG (n = 22) vs. AA + AG (n = 50)] and low producers of TGF-beta codon 25 [GC + CC (n = 17) vs. GG (n = 55)] had lower IMT of carotid artery but the difference did not reach statistical significance (P > 0.05). The CIMT of renal transplant patients was similar in IL-10 (-819, -592) and TNF-alpha (-308, -238) genotypes. No difference was observed in 24-h ambulatory blood pressure levels, serum lipoproteins, plasma homocysteine level, erythrocyte sedimentation rate, serum CRP, serum fibrinogen level in IL-10, TNF-alpha and TGF-beta1 genotypes. Besides the well-known factors, TGF-beta1 gene polymorphisms might play a role in CVD in RTR even at early stages of asymptomatic atherosclerosis.

Nicotine modulates cytokine production by Chlamydia pneumoniae infected human peripheral blood cells

Nicotine, the addictive component of cigarette smoke, has been shown to have immunomodulatory effects. This drug alters proinflammatory cytokine production by immune cells, including lymphocytes, monocytes, and macrophages. The present study focuses on the effects of nicotine on infection by Chlamydia pneumoniae (Cpn), a ubiquitous intracellular pathogen which causes acute and chronic inflammatory diseases such as pulmonary infections, and may be associated with arthritis and atherosclerosis. Previous studies in our laboratory showed that lymphocytes and macrophages are susceptible to Cpn infection. The present study aimed at investigating the effect of nicotine on TGF-beta1, IL-10, IL-12, and TNF-alpha production in Cpn-infected human peripheral blood mononuclear cells (PBMCs). Cytokine levels in the supernatant were assessed by ELISA. The results showed that Cpn infection alters the expression levels of IL-10, IL-12, and TNF-alpha in a time-dependent fashion. Nicotine treatment of the Cpn-infected cells up-regulated IL-10, but not TNF-alpha and IL-12, and also resulted in significant down-regulation of TGF-beta1 production which was marked in the Cpn-infected control cells. The combined action of nicotine and Cpn on cytokine production may have an impact in chronic inflammatory diseases.

Gene Polymorphism Association Studies in Dialysis: The Nutrition-Inflammation Axis

Although traditional risk factors for cardiovascular disease are common in dialysis patients, they alone cannot explain the unacceptably high prevalence of vascular disease in this patient group. Much recent interest has therefore focused on the role of various nontraditional cardiovascular risk factors, such as inflammation, wasting, obesity, vascular calcification, and oxidative stress. In addition, genetic factors such as single nucleotide polymorphisms (SNPs) may significantly influence the immune response, the levels of inflammatory markers and body composition, as well as the prevalence of vascular calcification in this patient group. While genetic variations in the tumor necrosis factor (TNF)-alpha-308 and interleukin (IL)-10 -1082 SNPs seem to be consistently associated with adverse clinical outcome in end-stage renal disease (ESRD) patients, the results regarding genetic variations in the IL-6 gene have been conflicting. To elucidate the respective role of DNA polymorphisms in the IL-6 and C-reactive protein (CRP) genes, as well as genes that encode vascular calcification inhibitors (such as fetuin-A, matrix Gla protein, and osteoprotegerin), sufficiently powered studies are needed in which both the protein product and the specific phenotype are determined. In addition, polymorphisms in genes related to body composition may be excellent candidates for analysis in the ESRD population, since nutritional parameters are strongly associated with adverse events in these patients. It seems conceivable that in the future, prognostic or predictive multigene DNA assays (which allow a simultaneous and rapid assessment of multiple genetic variants) will provide nephrologists with a more precise approach for the identification of "high-risk" ESRD patients and the development of accurate individualized treatment strategies.

End-stage renal disease--not an equal opportunity disease: the role of genetic polymorphisms

Despite several decades of development in renal replacement therapy, end-stage renal disease (ESRD) patients continue to have markedly increased morbidity and mortality especially caused by cardiovascular disease (CVD). This shows that current strategies, e.g. the focus on dialysis adequacy, to improve the clinical outcome in ESRD patients have to be complemented by novel approaches. Although traditional risk factors are common in dialysis patients they cannot alone explain the unacceptably high prevalence of CVD in this patient group. Much recent interest has therefore focused on the role of various nontraditional cardiovascular risk factors, such as inflammation, vascular calcification and oxidative stress. Recent studies show that genetic factors, such as DNA single nucleotide polymorphisms, may significantly influence the immune response, the levels of inflammatory markers, as well as the prevalence of atherosclerosis in this patient group. To elucidate the respective roles of DNA polymorphisms in genes that encode inflammatory markers (such as IL-10, IL-6 and TNF-alpha) and other factors that may affect the development of atherosclerosis (such as apolipoprotein E, transforming growth factor and fetuin-A), sufficiently powered studies are needed in which genotype, the protein product and the specific phenotype all are analysed in relation to outcome. The recent developments in the field of genetics have opened up entirely new possibilities to understand the impact of genotype on disease development and progress and thus offer new options and strategies for treatment. It seems conceivable that in the near future, prognostic or predictive multigene DNA assays will provide the nephrological community with a more precise approach for the identification of "high-risk" ESRD patients and the development of accurate individual treatment strategies. For this purpose, integrative studies on genotype-phenotype associations and impact on clinical outcome are needed.

Effects of dietary phytoestrogens on cardiac remodeling secondary to chronic volume overload in female rats

Previously, we demonstrated that intact female rats fed a standard rodent diet containing soybean products exhibit essentially no adverse left ventricular (LV) remodeling in response to aortocaval fistula-induced chronic volume overload. We hypothesized that phytoestrogenic compounds in the diet contributed to the female cardioprotection. To test this hypothesis, four groups of female rats were studied: sham-operated (Sham) and fistula (Fist) rats fed a diet with [P(+)] or without [P(-)] phytoestrogens. Eight weeks postfistula, systolic and diastolic cardiac function was assessed by using a blood-perfused, isolated heart preparation. High-phytoestrogen diet had no effect on body, heart, and lung weights, or cardiac function in Sham rats. Fistula groups developed LV hypertrophy, which was not reduced by dietary phytoestrogens [1,184 +/- 229 mg Fist-P(-) and 1,079 +/- 199 mg Fist-P(+) vs. 620 +/- 47 mg for combined Sham groups, P < 0.05]. Unstressed LV volume increased in Fist-P(-) rats (428 +/- 16 vs. 300 +/- 14 microl Sham, P < 0.0001), but it was not different from Sham for Fist-P(+) animals (286 +/- 17 microl). Fist-P(-) rats developed increased ventricular compliance (5.3 +/- 0.8 vs. 2.3 +/- 0.3 microl/mmHg Sham, P < 0.01), whereas Fist-P(+) rats had no change in compliance (2.8 +/- 0.4 mul/mmHg). Intrinsic ventricular contractility was maintained in the Fist-P(+) rats, but it was reduced (P < 0.001) in the Fist-P(-) rats [systolic pressure-volume slope: 1.04 +/- 0.03, 0.60 +/- 0.06, and 0.99 +/- 0.08 mmHg/microl, for Fist-P(+), Fist-P(-), and Sham, respectively]. These data indicate that dietary phytoestrogens contribute significantly to female cardioprotection against volume overload-induced adverse ventricular remodeling and that studies evaluating gender differences in cardiovascular remodeling must consider the influence of dietary phytoestrogens.

Targeted disruption of TGF-beta-Smad3 signaling leads to enhanced neointimal hyperplasia with diminished matrix deposition in response to vascular injury

The role of transforming growth factor (TGF)-beta and its signal in atherogenesis is not fully understood. Here, we examined mice lacking Smad3, a major downstream mediator of TGF-beta, to clarify the precise role of Smad3-dependent signaling in vascular response to injury. Femoral arteries were injured in wild-type and Smad3-null (null) male mice on C57Bl/6 background. Histopathological evaluation of the arteries 1 to 3 weeks after the injury revealed significant enhancement of neointimal hyperplasia in null compared with wild-type mice. Transplantation of null bone marrow to wild-type mice did not enhance neointimal thickening, suggesting that vascular cells in situ play a major role in the response. Null intima contained more proliferating smooth muscle cells (SMC) with less amount of collagen compared with wild-type intima. TGF-beta caused significant inhibition of cellular proliferation in wild-type aortic SMC, whereas the growth of null SMC was only weakly inhibited by TGF-beta in vitro, indicating a crucial role of Smad3 in the growth inhibitory function. On the other hand, Smad3-deficiency did not attenuate chemotaxis of SMC toward TGF-beta. TGF-beta increased transcript level of alpha2 type I collagen and tissue inhibitor of metalloproteinases-1, and suppressed expression and activity of matrix metalloproteinases in wild-type SMC. However, these effects of TGF-beta were diminished in null SMC. Our findings altogether show that the loss of Smad3 pathway causes enhanced neointimal hyperplasia on injury through modulation of growth and matrix regulation in vascular SMC. These results indicate a vasculoprotective role of endogenous Smad3 in response to injury.

Immunomodulation and vaccination for atherosclerosis

During the last few decades, the pathogenesis of atherosclerosis has been related not only to cholesterol deposition and cell proliferation in the lesions, but also to infiltration of immune cells, which are involved in both systemic and local, innate as well as adaptive, immune responses. A number of antigen candidates, such as oxidised low-density lipoprotein and heat-shock proteins, have been associated with the disease process. As some inflammatory and autoimmune diseases could be treated by immunologically based therapy, it is of particular interest whether such principles can also be applied to prevent or treat atherosclerosis. Indeed, modification of immune reactions in animal models can greatly affect the development and progression of atherosclerosis. This review provides an overview of our current understanding of how immunomodulation changes the course of atherosclerosis and how vaccination may be used for preventing the disease.

Inhibitory control of TGF-beta1 on the activation of Rap1, CD11b, and transendothelial migration of leukocytes

Beta2-integrins are a family of dimeric adhesion molecules expressed on leukocytes. Their capacity to bind ligand is regulated by their state of activation. CD11b, an alphaMbeta2 integrin, is implicated in a number of physiological and pathological events such as inflammation, thrombosis, or atherosclerosis. The GTPase Rap1 is essential for its activation and could therefore play a strategic role in the regulation of leukocyte functioning. Because low levels of circulating TGF-beta have been linked with severe atherosclerosis, we have assessed the role of this cytokine in the regulation of Rap1 and CD11b activation in differentiated U937 cells and in human peripheral blood monocytes. TGF-beta1 caused a significant reduction in the expression of CD11b but not in the expression of other integrins tested. More importantly, TGF-beta1 greatly reduced the capacity of PMA or chemokines to activate CD11b and Rap1, a phenomenon paralleled by a loss of the Epac transcript and a reduction in 8-pCPT-2'-O-Me-cAMP-mediated activation of Rap1. This inhibition diminished the capacity of monocytes to migrate across a monolayer of endothelial cells. The inhibitory effect of TGF-beta1 on Rap1 activity may exert a general protective influence against aberrant transendothelial migration, thereby holding inflammatory responses in check.