Association of serum TRAIL levels with atherosclerosis in patients with type 2 diabetes mellitus

TRAIL and its receptors in cardiac diseases

Cardiovascular disease is a leading cause of death worldwide. Loss of cardiomyocytes that occurs during many types of damage to the heart such as ischemic injury and stress caused by pressure overload, diminishes cardiac function due to their limited regenerative capacity and promotes remodeling, which further damages the heart. Cardiomyocyte death occurs through two primary mechanisms, necrosis and apoptosis. Apoptosis is a highly regulated form of cell death that can occur through intrinsic (mitochondrial) or extrinsic (receptor mediated) pathways. Extrinsic apoptosis occurs through a subset of Tumor Necrosis Receptor (TNF) family receptors termed "Death Receptors." While some ligands for death receptors have been extensively studied in the heart, such as TNF-α, others have been virtually unstudied. One poorly characterized cardiac TNF related ligand is TNF-Related Apoptosis Inducing Ligand (TRAIL). TRAIL binds to two apoptosis-inducing receptors, Death Receptor (DR) 4 and DR5. There are also three decoy TRAIL receptors, Decoy Receptor (DcR) 1, DcR2 and osteoprotegerin (OPG). While TRAIL has been extensively studied in the cancer field due to its ability to selectively induce apoptosis in transformed cell types, emerging clinical evidence points towards a role for TRAIL and its receptors in cardiac pathology. This article will highlight our current understanding of TRAIL and its receptors in normal and pathological conditions in the heart.

The Prognostic, Diagnostic, and Therapeutic Potential of TRAIL Signalling in Cardiovascular Diseases

TNF-related apoptosis-inducing ligand (TRAIL) was originally discovered, almost 20 years ago, for its ability to kill cancer cells. More recent evidence has described pleiotropic functions, particularly in the cardiovascular system. There is potential for TRAIL concentrations in the circulation to act as prognostic and/or diagnostic factors for cardiovascular diseases (CVD). Pre-clinical studies also describe the therapeutic capacity for TRAIL signals, particularly in the context of atherosclerotic disease and diseases of the myocardium. Because diabetes mellitus significantly contributes to the progression and pathogenesis of CVDs, in this review we highlight recent evidence for the prognostic, diagnostic, and therapeutic potential of TRAIL signals in CVDs, and where relevant, the impact of diabetes mellitus. A greater understanding of how TRAIL signals regulate cardiovascular protection and pathology may offer new diagnostic and therapeutic avenues for patients suffering from CVDs.

Serum OPG/TRAIL ratio predicts the presence of cardiovascular disease in people with type 2 diabetes mellitus

AIMS

Cardiovascular disease (CVD) is the leading cause of mortality in type 2 diabetes mellitus (T2DM). Epidemiological studies suggest serum Osteoprotegrin (OPG)/Tumour-necrosis-factor-related-apoptosis-inducing- ligand (TRAIL) ratio may be a useful marker of cardiovascular risk. This study aimed to compare serum levels of TRAIL, OPG and OPG/TRAIL ratio in people with T2DM, with and without a history of CVD, and controls; and to determine which of these indices, if any, predict cardiovascular risk.

METHODS

In this single centre observational study of 133 participants, people with T2DM, with and without a history of a cardiovascular event in the last 5 years, were recruited along with a control cohort without T2DM or CVD. Demographic information and anthropometric measurements were recorded. Blood samples were taken and OPG and TRAIL were measured using ELISA.

RESULTS

People with T2DM and CVD had higher OPG/TRAIL ratios compared to controls or those with a new diagnosis of T2DM. After adjustment for potential confounding factors, OPG/TRAIL ratio was significantly associated with the presence of CVD in people with T2DM and an OPG/TRAIL ratio cut-off > 38.6 predicted the presence of CVD in this cohort with a sensitivity of 80% and specificity of 82%.

CONCLUSION

This study suggests that OPG/TRAIL ratio may have a role as a biomarker of CVD in people with T2DM.

Identification of Biomarkers of Autophagy-Related Genes Between Early and Advanced Carotid Atherosclerosis

Background

Accumulating evidence demonstrates that autophagy is important in inhibiting inflammation and cholesterol efflux. It suggested the autophagy may be a treatment of atherosclerosis. Thus, we screened autophagy-related mRNA to explore their mechanism of scientific basis for early diagnosis and therapy of atherosclerosis.

Methods

The GSE28829 datasets were assessed to analyze differentially expressed genes by GEO2R. And autophagy-related hub genes were identified by HADb. The biological function of autophagy-related DEmRNAs was examined by Metascape. The construction of a protein–protein network was explored by String. Cytohubba was utilized to screen hub genes. Analysis of DEmiRNA-mRNA pairs was executed by DIANA microT-CDS database. Finally, correlation analysis was carried out to identify the relationship between DEARGs and clinical and prognostic factors.

Results

A number of 1087 DEGs and 19 autophagy-related DEmRNAs were identified in advanced carotid atherosclerotic plaque compared with the early. The biological function containing development and growth was enriched. Moreover, we screened the top hub nodes with the highest degrees. MicroRNAs (miRNAs) are confirmed to participate in genesis and progression of atherosclerosis, so we further analyzed the miRNA–mRNA regulatory network genes with four hub genes to explore their potential mechanism in atherosclerosis. Then, we revealed co-expression of four key genes CTSB, ITGB1, CXCR4, TNFSF10 and autophagy-related genes. As for the clinical factors, hypertension factor showed higher expression of ITGB1. The probability of coronary heart disease factor was significantly increased with high expression of CTSB and CXCR4, as well as low expression of ITGB1 and TNFSF10. Diabetes factor tended to express distinguished levels of CTSB and ITGB1. TNFSF10 was highly expressed in both hyperlipidemia and ischemic stroke factor.

Conclusion

CTSB, ITGB1, CXCR4 and TNFSF10 may be critical in atherosclerosis development and were thought to be potential diagnostic biomarkers for atherosclerosis.

Repositioning the Role of Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) on the TRAIL to the Development of Diabetes Mellitus: An Update of Experimental and Clinical Evidence

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a member of the TNF protein superfamily, represents a multifaceted cytokine with unique biological features including both proapoptotic and pro-survival effects in different cell types depending on receptor interactions and local stimuli. Beyond its extensively studied anti-tumor and immunomodulatory properties, a growing body of experimental and clinical evidence over the past two decades suggests a protective role of TRAIL in the development of type 1 (T1DM) and type 2 (T2DM) diabetes mellitus. This evidence can be briefly summarized by the following observations: (i) acceleration and exacerbation of T1DM and T2DM by TRAIL blockade or genetic deficiency in animal models, (ii) prevention and amelioration of T1DM and T2DM with recombinant TRAIL treatment or systemic TRAIL gene delivery in animal models, (iii) significantly reduced circulating soluble TRAIL levels in patients with T1DM and T2DM both at disease onset and in more advanced stages of diabetes-related complications such as cardiovascular disease and diabetic nephropathy, (iv) increase of serum TRAIL levels in diabetic patients after initiation of antidiabetic treatment and metabolic improvement. To explore the underlying mechanisms and provide mechanistic links between TRAIL and diabetes, a number of animal and in vitro studies have reported direct effects of TRAIL on several tissues involved in diabetes pathophysiology such as pancreatic islets, skeletal muscle, adipose tissue, liver, kidney, and immune and vascular cells. Residual controversy remains regarding the effects of TRAIL on adipose tissue homeostasis. Although the existing evidence is encouraging and paves the way for investigating TRAIL-related interventions in diabetic patients with cardiometabolic abnormalities, caution is warranted in the extrapolation of animal and in vitro data to the clinical setting, and further research in humans is imperative in order to uncover all aspects of the TRAIL-diabetes relationship and delineate its therapeutic implications in metabolic disease.

TRAIL and Cardiovascular Disease-A Risk Factor or Risk Marker: A Systematic Review

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a pro-apoptotic protein showing broad biological functions. Data from animal studies indicate that TRAIL may possibly contribute to the pathophysiology of cardiomyopathy, atherosclerosis, ischemic stroke and abdominal aortic aneurysm. It has been also suggested that TRAIL might be useful in cardiovascular risk stratification. This systematic review aimed to evaluate whether TRAIL is a risk factor or risk marker in cardiovascular diseases (CVDs) focusing on major adverse cardiovascular events. Two databases (PubMed and Cochrane Library) were searched until December 2020 without a year limit in accordance to the PRISMA guidelines. A total of 63 eligible original studies were identified and included in our systematic review. Studies suggest an important role of TRAIL in disorders such as heart failure, myocardial infarction, atrial fibrillation, ischemic stroke, peripheral artery disease, and pulmonary and gestational hypertension. Most evidence associates reduced TRAIL levels and increased TRAIL-R2 concentration with all-cause mortality in patients with CVDs. It is, however, unclear whether low TRAIL levels should be considered as a risk factor rather than a risk marker of CVDs. Further studies are needed to better define the association of TRAIL with cardiovascular diseases.

TNF-Related Apoptosis-Inducing Ligand Receptor 1 in Patients With Ankylosing Spondylitis

OBJECTIVES

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) belongs to the tumor necrosis factor (TNF) superfamily and is reported to play a role in autoimmune diseases. In this study, we aimed to measure serum TRAIL receptor 1 (TRAIL-R1) concentration and assess any phenotypic relationship in patients with ankylosing spondylitis (AS).

METHODS

Fifty-three patients with AS were recruited from August 2014 to December 2014 cross-sectionally. Fifty-three sex- and age-matched healthy controls were also recruited. Serum TRAIL-R1 concentrations were measured using an enzyme-linked immunosorbent assay. The association between serum TRAIL-R1, TNF-α, disease activity indices, markers of systemic inflammation, and clinical features were evaluated.

RESULTS

Serum TRAIL-R1 and TNF-α levels were increased in patients with AS compared with healthy controls (4.5 ± 2.3 vs 3.5 ± 2.3 pg/mL, p = 0.036; 3.8 [1.6-7.7] vs 2.0 [0.21-5.7] pg/mL, p = 0.048, respectively). Serum TRAIL-R1 displayed a medium positive correlation with serum TNF-α concentrations (r = 0.412; p = 0.002). Serum TRAIL-R1 concentration was higher in human leucocyte antigen (HLA)-B27-positive patients compared with non-HLA-B27 patients (5.5 ± 2.2 vs 3.1 ± 1.6 pg/mL, p < 0.001). No relationship was found between serum TRAIL-R1 concentration and disease activity scores.

CONCLUSIONS

This study confirms that serum TRAIL-R1 levels are higher in AS patients than healthy controls. The persistence of significantly elevated serum TRAIL-R1 levels, even in patients with low disease activity or after excluding biologic treatment, and the association with HLA-B27 positivity, warrants further investigation due to the unclear role of TRAIL-R1 in the pathophysiology of AS.

TRAIL attenuates RANKL-mediated osteoblastic signalling in vascular cell mono-culture and co-culture models

Background and objectives

Vascular calcification (VC) is a major risk factor for elevated cardiovascular morbidity/mortality. Underlying this process is osteoblastic signalling within the vessel wall involving complex and interlinked roles for receptor-activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), and tumour necrosis factor-related apoptosis-inducing ligand (TRAIL). RANKL promotes vascular cell osteoblastic differentiation, whilst OPG acts as a neutralizing decoy receptor for RANKL (and TRAIL). With respect to TRAIL, much recent evidence points to a vasoprotective role for this ligand, albeit via unknown mechanisms. In order to shed more light on TRAILs vasoprotective role therefore, we employed in vitro cell models to test the hypothesis that TRAIL can counteract the RANKL-mediated signalling that occurs between the vascular cells that comprise the vessel wall.

Methods and results

Human aortic endothelial and smooth muscle cell mono-cultures (HAECs, HASMCs) were treated with RANKL (0–25 ng/mL ± 5 ng/mL TRAIL) for 72 hr. Furthermore, to better recapitulate the paracrine signalling that exists between endothelial and smooth muscle cells within the vessel wall, non-contact transwell HAEC:HASMC co-cultures were also employed and involved RANKL treatment of HAECs (±TRAIL), subsequently followed by analysis of pro-calcific markers in the underlying subluminal HASMCs. RANKL elicited robust osteoblastic signalling across both mono- and co-culture models (e.g. increased BMP-2, alkaline phosphatase/ALP, Runx2, and Sox9, in conjunction with decreased OPG). Importantly, several RANKL actions (e.g. increased BMP-2 release from mono-cultured HAECs or increased ALP/Sox9 levels in co-cultured HASMCs) could be strongly blocked by co-incubation with TRAIL. In summary, this paper clearly demonstrates that RANKL can elicit pro-osteoblastic signalling in HAECs and HASMCs both directly and across paracrine signalling axes. Moreover, within these contexts we present clear evidence that TRAIL can block several key signalling actions of RANKL in vascular cells, providing further evidence of its vasoprotective potential.

Soluble TRAIL Concentration in Serum Is Elevated in People with Hypercholesterolemia

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a multi-functional cytokine, which is involved in the pathophysiological processes of cardiovascular and metabolic diseases. Previously, we demonstrated that TRAIL stimulated lipid uptake and foam cell formation in macrophages in vitro. Several clinical studies have suggested that the serum concentration of TRAIL may be increased in humans with elevated blood cholesterol; however, the current data appear to be inconclusive in this regard. In the present study, we examined the relationships between the serum TRAIL concentration and cholesterol levels in 352 generally healthy subjects undergoing the routine annual health check. We showed that there were significant correlations between TRAIL concentration and levels of total and low-density lipoprotein cholesterols. The level of TRAIL was significantly elevated in subjects with hypercholesterolemia, although this relationship might be also associated with changes of other metabolic factors. Moreover, we showed that the level of blood cholesterol was significantly higher in subjects in the upper quartile of serum TRAIL. In conclusion, our data demonstrate that the serum TRAIL concentration is elevated in people with hypercholesterolemia.

The relationship between circulating TRAIL and endothelial dysfunction in subclinical hypothyroidism

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is associated with atherosclerosis. Subclinical hypothyroidism (sHT) is associated with the increased prevalence of atherosclerotic lesions and cardiovascular events. Therefore, we hypothesized that circulating TRAIL levels are associated with endothelial dysfunction in sHT patients. Two hundred and four patients with newly diagnosed sHT and 52 healthy subjects were recruited. Circulating TRAIL concentration was measured by an ELISA, and flow-mediated dilation (FMD) of brachial artery was measured using high-resolution ultrasound. The mean value of circulating TRAIL in newly diagnosed sHT patients was 67.2 pg/ml, which was lower than that in controls (78.5 pg/ml, p < 0.001). By dividing the distribution of FMD levels into quartiles, TRAIL levels were increased gradually with the increase of FMD levels (p < 0.001). Multivariate regression analysis demonstrated that serum TRAIL levels were independently associated with FMD (p = 0.007). By logistic regression analysis, the odds ratio for lower FMD levels was reduced by 12.1 % per 1 pg/ml increase in serum TRAIL concentration after adjustment for multivariate metabolic factors [OR (95 % CI); 0.879 (0.721-0.973)]. Circulating TRAIL level decreased in newly diagnosed sHT patients and is positively associated with endothelial function, suggesting that circulating TRAIL level may be a protective marker of endothelial function in sHT patients.

Tumor necrosis factor-related apoptosis-inducing ligand in vascular inflammation and atherosclerosis: a protector or culprit?

In addition to inducing tumor cell apoptosis, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) shows broad biological functions both in vitro and in vivo. TRAIL gene deletion enhanced atherogenesis in hyperlipidemic mice, supporting that endogenous TRAIL has protective actions in maintaining blood vessel homeostasis and repressing atherosclerosis. The mechanisms of this beneficial effect are not understood. It remains to be determined whether the athero-protective action of TRAIL is via direct impacts on residential vascular cells or indirectly by modulating systemic immune functions. However, in vitro experiments indicate that excessive TRAIL may stimulate endothelial cell apoptosis, smooth muscle proliferation and migration, and inflammatory responses. Moreover, TRAIL can stimulate lipid uptake and foam cell formation in cultured macrophages. Here we provide a critical review on the potential relationships between TRAIL and atherosclerosis. We propose that increased TRAIL production may also have potential detrimental effects on vascular inflammation and atherosclerosis. Further in vivo experiments are warranted to elucidate the effects of exogenous TRAIL on atherogenesis.

Association of serum tumor necrosis factor-related apoptosis inducing ligand with body fat distribution as assessed by dual X-rays absorptiometry

A low chronic inflammation mediated by cytokine release is considered a major pathogenic mechanism accounting for the higher risk of cardiovascular disease in the overweight/obese population. In this context, although the existence of a possible interaction between soluble tumor necrosis factor- (TNF-) related apoptosis inducing ligand (TRAIL) and quantity and localization, of adiposity in the body has been hypothesized, no studies have yet investigated this link by radiologic techniques able to assess directly fat mass (FM) in different body regions. To address this issue, we assessed body fat distribution by dual X-rays absorptiometry (DXA) in a sample of 103 women and investigated the possible association between the derived adiposity measures and serum TRAIL concentration. The level of TRAIL showed a positive and independent correlation with arms FM (P < 0.05), trunk FM (P < 0.001) and trunk FM% (P < 0.05), total FM and total FM% (P < 0.001 for both), and an inverse association with legs FM% (P < 0.05). Only trunk FM retained a significant correlation (P < 0.05) with TRAIL after adjusting for all the other indices of regional adiposity. In conclusion, from our study it emerged a significant and independent association of serum TRAIL levels with overall, and, mainly, central adiposity. Further studies are needed to longitudinally investigate the cause-effect relationship between change in body fat distribution and TRAIL.

Patients with ankylosing spondylitis and low disease activity because of anti-TNF-alpha therapy have higher TRAIL levels than controls: a potential compensatory effect

OBJECTIVE

TRAIL is a potential biomarker of cardiovascular (CV) disease. Ankylosing spondylitis (AS) is a chronic inflammatory disease associated with metabolic syndrome (MeS) and accelerated atherosclerosis. We assessed whether disease activity, systemic inflammation, and MeS features were associated with circulating TRAIL levels in AS patients undergoing TNF-α antagonist infliximab therapy and if infliximab infusion modified TRAIL levels.

METHODS

We measured TRAIL serum levels in 30 nondiabetic AS patients without CV disease undergoing anti-TNF-α therapy, immediately before and after an infliximab infusion, and in 48 matched controls. Correlations of TRAIL levels with disease activity, systemic inflammation and MeS features, adipokines, and biomarkers of endothelial activation were evaluated. Changes in TRAIL levels following anti-TNF-α infusion were analyzed.

RESULTS

TRAIL levels were higher in AS patients than controls. TRAIL levels displayed an inverse correlation with total and LDL cholesterol. We observed an inverse correlation with QUICKI and a marginal association with HOMA-IR. We also found an inverse correlation with resistin and a marginal association with apelin and OPN. Anti-TNF-α infusion did not change TRAIL levels after 120'.

CONCLUSION

Elevated TRAIL levels in AS patients may be the result of a compensatory mechanism to reduce CV risk in these patients.

Circulating level of TRAIL concentration is positively associated with endothelial function and increased by diabetic therapy in the newly diagnosed type 2 diabetic patients

OBJECTIVE

Tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is associated with atherosclerosis. This study was to investigate the changes of circulating TRAIL and its association with flow-mediated endothelium-dependent arterial dilation (FMD) before and after diabetic treatment in newly diagnosed type 2 diabetes.

MATERIALS AND METHODS

The study subjects included 55 newly diagnosed type 2 diabetes and 52 healthy subjects. Circulating TRAIL concentration was measured by an ELISA, and high-resolution ultrasound was used to measure FMD of brachial artery.

RESULTS

The circulating TRAIL in patients before treatment was 64·46 pg/ml, which was significantly lower than that in control (80·70 pg/ml, P < 0·001). After 6 months of diabetic treatment, TRAIL level increased markedly (75·11 pg/ml), which was still lower than that in control (P < 0·001). FMD was reduced compared with controls at baseline and increased after diabetic therapy (P < 0·001). In multivariate analysis, circulating TRAIL was significantly associated with FMD, fasting blood glucose (FBG), 2-h blood glucose (2-h BG), haemoglobinA1c (HbA1c) and C-reactive protein (CRP) at baseline (P < 0·01). The absolute change in TRAIL was correlated with the changes in FMD, FBG, 2-h BG, HbA1c and CRP (P < 0·01) before and after diabetic treatment.

CONCLUSION

Circulating TRAIL level decreased in newly diagnosed type 2 diabetes and increased after 6 months of diabetic treatment significantly. The circulating TRAIL level is positively associated with endothelial function. Our data showed that circulating TRAIL level may be a protective maker of endothelial function in type 2 diabetes.

On the TRAIL of obesity and diabetes

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has been extensively studied for its preferential ability to induce apoptosis of cancer cells. Beyond the cytotoxic capacity of TRAIL, new physiological and pathological roles for TRAIL have been identified, and there is now growing evidence supporting its involvement in the development of obesity and diabetes. This review summarizes the most recent findings associating TRAIL with obesity and diabetes in both humans and experimental settings. We also present and discuss some of the reported controversies behind TRAIL signaling and function. Understanding TRAIL mechanism(s) in vivo and its involvement in disease may lead to novel strategies to combat the growing pandemic of obesity and diabetes worldwide.

Association of circulating sTRAIL and high-sensitivity CRP with type 2 diabetic nephropathy and foot ulcers

BACKGROUND

Hyperglycemia is among the potent factors that may induce or facilitate apoptosis. TNF-Related Apoptosis-Inducing Factor (TRAIL) is known for its apoptotic and immunomodulatory effects that have recently been correlated with diabetes. We examined serum-soluble TRAIL (sTRAIL) and high-sensitivity CRP (hs-CRP) levels and their association with various distinct parameters in type 2 diabetic nephropathy patients with diabetic foot disease.

MATERIAL/METHODS

Twenty-two diabetic nephropathy patients with foot ulcers were enrolled in our study. Patients had been diagnosed with diabetes at age 24±10.58 years. Circulating sTRAIL and Hs-CRP levels were compared with control values, and possible correlations were investigated with parameters such as age, Wagner's Grade (WG), BMI, HbA1c, and creatinine.

RESULTS

Serum sTRAIL levels were significantly reduced in the patient group, compared to healthy subjects. High HsCRP levels correlated with age, and WGS correlated with BMI and creatinine levels.

CONCLUSIONS

Significantly suppressed sTRAIL levels in diabetic nephropathy patients with foot ulcers compared to healthy controls suggest a protective role for TRAIL in the disease setting.

The circulating levels of TRAIL are extremely low after delivery but rapidly recover in both mothers and newborns

TNF-related apoptosis inducing ligand (TRAIL) plasma levels was measured in plasma samples obtained 1h (time 1) and 2-3 days (time 2) after delivery in a group of healthy women (n=17) who underwent cesarean delivery, and showed a significantly increase from time 1 (39.3 pg/ml median; 41.2 ± 15.9 mean ± SD) to time 2 (71.6 pg/ml median; 73.8 ± 27.8 mean ± SD). Similarly, circulating TRAIL levels were extremely low in the plasma of newborns (n=41) within the first 24h after partum (time 1; 27.5 pg/ml, median; 31.5 ± 15.8 means ± SD), showing a significant increase 2-3 days after partum (time 2; 68.4 pg/ml, median; 75.1 ± 36.7 mean ± SD). It is also noteworthy that the highest levels of plasma TRAIL were observed in newborns with the following characteristics: (i) born at later gestational age, (ii) Apgar score >9, (iii) higher birth weight, (iv) born through vaginal partum. In conclusion, we have demonstrated for the first time that the levels of circulating TRAIL are markedly low in both mothers and children after delivery, rapidly rising thereafter. Moreover, the highest levels of TRAIL are observed in newborns with the best clinical parameters.

C-Reactive protein downregulates TRAIL expression in human peripheral monocytes via an Egr-1-dependent pathway

PURPOSE

To investigate the potential link between C-reactive protein (CRP), a known biomarker of acute and chronic inflammation, and TRAIL, a cytokine which plays a key role in the immune-surveillance against tumors.

EXPERIMENTAL DESIGN

Primary normal peripheral blood mononuclear cell (PBMC) and CD14(+) monocytes were exposed to recombinant CRP (1-10 μmol/L). TRAIL expression was analyzed by ELISA and/or by quantitative real-time PCR (qRT-PCR). In parallel, the potential role of the transcription factor Egr-1 was investigated by analyzing its modulation in response to CRP and by transfection experiments.

RESULTS

In vitro CRP exposure induced downregulation of TRAIL expression, both at the mRNA and protein level, in unfractionated PBMC and in purified CD14(+) monocytes. TRAIL downregulation was not due to a specific toxicity or to contaminating lipopolysaccharide (LPS), as shown by the lack of induction of monocyte apoptosis and by the inability of the inhibitor of LPS polymyxin B to interfere with CRP activity. Of note, CRP downregulated TRAIL expression/release in CD14(+) monocytes also in response to IFN-α, the most potent inducer of TRAIL. At the molecular level, the downmodulation of TRAIL by CRP was accompanied by a significant increase of Egr-1. Consistently, Egr-1 overexpression reduced the baseline levels of TRAIL mRNA, whereas knocking down Egr-1 counteracted the ability of CRP to downregulate TRAIL.

CONCLUSIONS

Our findings suggest that a chronic elevation of CRP, which occurs during systemic inflammation and often in patients with cancer, might contribute to promote cancer development and/or progression by downregulating TRAIL in immune cells.

Association of soluble Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL) with central adiposity and low-density lipoprotein cholesterol

OBJECTIVE

Tumor necrosis factor-Related Apoptosis-Inducing Ligand (TRAIL), in addition to having a prognostic value in patients with cardiovascular disease, seems to interact with adiposity, insulin resistance and other cardiovascular risk factors. However, the results of previous clinical studies, focused on the association of TRAIL with selected metabolic or anthropometric indices were inconclusive. The aim of this study was to further investigate how soluble TRAIL concentrations independently correlate with major cardiovascular risk factors, including lipid, glycemic and anthropometric features.

MATERIALS/METHODS

We examined the associations between serum soluble TRAIL concentrations, measured by ELISA, and lipid, glycemic and anthropometric features in 199 subjects recruited at our Metabolic Outpatient Clinic.

RESULTS

Soluble TRAIL concentrations had a significant and direct correlation with total cholesterol (p = 0.046), LDL-cholesterol (p = 0.032), triglycerides (p = 0.01), body mass index (p = 0.046), waist circumference (p = 0.008), fat mass (p = 0.056) and insulin (p = 0.046) and an inverse correlation with HDL-cholesterol (p = 0.02). In multivariable regression analyses adjusted for potential confounders (age, gender, C-reactive protein, HDL-cholesterol, triglycerides, waist circumference, and insulin), TRAIL levels continued to have an independent correlation with LDL-cholesterol and waist circumference (r(2) = 0.04).

CONCLUSIONS

Serum TRAIL levels were weakly but significantly and independently associated with waist circumference, a marker of visceral adiposity, and with LDL-cholesterol. Further studies are needed to clarify the biological basis of these relationships.

Circulating soluble tumor necrosis factor related apoptosis inducing-ligand (TRAIL) is decreased in type-2 newly diagnosed, non-drug using diabetic patients

We examined the association between serum sTRAIL measured by ELISA and HbA1C levels, pre/post-prandial blood glucose levels and body mass index in 22 newly diagnosed type-2 diabetic patients. A significant difference in sTRAIL levels was found between study group and controls.

Circulating TRAIL shows a significant post-partum decline associated to stressful conditions

Background

Since circulating levels of TNF-related apoptosis inducing ligand (TRAIL) may be important in the physiopathology of pregnancy, we tested the hypothesis that TRAIL levels change at delivery in response to stressful conditions.

Methods/Principal Findings

We conducted a longitudinal study in a cohort of 73 women examined at week 12, week 16, delivery and in the corresponding cord blood (CB). Serum TRAIL was assessed in relationship with maternal characteristics and to biochemical parameters. TRAIL did not vary between 12 (67.6±27.6 pg/ml, means±SD) and 16 (64.0±16.2 pg/ml) weeks' gestation, while displaying a significant decline after partum (49.3±26.4 pg/ml). Using a cut-off decline >20 pg/ml between week 12 and delivery, the subset of women with the higher decline of circulating TRAIL (41.7%) showed the following characteristics: i) nullipara, ii) higher age, iii) operational vaginal delivery or urgent CS, iv) did not receive analgesia during labor, v) induced labor. CB TRAIL was significantly higher (131.6±52 pg/ml) with respect to the corresponding maternal TRAIL, and the variables significantly associated with the first quartile of CB TRAIL (<90 pg/ml) were higher pre-pregnancy BMI, induction of labor and fetal distress. With respect to the biochemical parameters, maternal TRAIL at delivery showed an inverse correlation with C-reactive protein (CRP), total cortisol, glycemia and insulin at bivariate analysis, but only with CRP at multivariate analysis.

Conclusions

Stressful partum conditions and elevated CRP levels are associated with a decrease of circulating TRAIL.