Role Of TNF-related Apoptosis-inducing Ligand Research Articles

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 Role of TRAIL in Apoptosis and Immunosurveillance in Cancer

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that selectively induces apoptosis in tumor cells without harming normal cells, making it an attractive agent for cancer therapy. TRAIL induces apoptosis by binding to and activating its death receptors DR4 and DR5. Several TRAIL-based treatments have been developed, including recombinant forms of TRAIL and its death receptor agonist antibodies, but the efficacy of TRAIL-based therapies in clinical trials is modest. In addition to inducing cancer cell apoptosis, TRAIL is expressed in immune cells and plays a critical role in tumor surveillance. Emerging evidence indicates that the TRAIL pathway may interact with immune checkpoint proteins, including programmed death-ligand 1 (PD-L1), to modulate PD-L1-based tumor immunotherapies. Therefore, understanding the interaction between TRAIL and the immune checkpoint PD-L1 will lead to the development of new strategies to improve TRAIL- and PD-L1-based therapies. This review discusses recent findings on TRAIL-based therapy, resistance, and its involvement in tumor immunosurveillance.

Electronic Cigarette Exposure Increases the Severity of Influenza a Virus Infection via TRAIL Dysregulation in Human Precision-Cut Lung Slices.

The use of electronic nicotine dispensing systems (ENDS), also known as electronic cigarettes (ECs), is common among adolescents and young adults with limited knowledge about the detrimental effects on lung health such as respiratory viral infections and underlying mechanisms. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), a protein of the TNF family involved in cell apoptosis, is upregulated in COPD patients and during influenza A virus (IAV) infections, but its role in viral infection during EC exposures remains unclear. This study was aimed to investigate the effect of ECs on viral infection and TRAIL release in a human lung precision-cut lung slices (PCLS) model, and the role of TRAIL in regulating IAV infection. PCLS prepared from lungs of nonsmoker healthy human donors were exposed to EC juice (E-juice) and IAV for up to 3 days during which viral load, TRAIL, lactate dehydrogenase (LDH), and TNF-α in the tissue and supernatants were determined. TRAIL neutralizing antibody and recombinant TRAIL were utilized to determine the contribution of TRAIL to viral infection during EC exposures. E-juice increased viral load, TRAIL, TNF-α release and cytotoxicity in IAV-infected PCLS. TRAIL neutralizing antibody increased tissue viral load but reduced viral release into supernatants. Conversely, recombinant TRAIL decreased tissue viral load but increased viral release into supernatants. Further, recombinant TRAIL enhanced the expression of interferon-β and interferon-λ induced by E-juice exposure in IAV-infected PCLS. Our results suggest that EC exposure in human distal lungs amplifies viral infection and TRAIL release, and that TRAIL may serve as a mechanism to regulate viral infection. Appropriate levels of TRAIL may be important to control IAV infection in EC users.

TRAIL inhibition by soluble death receptor 5 protects against acute myocardial infarction in rats.

Acute myocardial infarction (AMI) is associated with high morbidity and mortality. An effective therapeutic strategy is to rescue cardiomyocytes from death. Apoptosis is a key reason of cardiomyocyte death that can be prevented. In this study, we investigated the role of TNF-related apoptosis-inducing ligand (TRAIL) in initiating apoptosis by binding to death receptor 5 (DR5), and this procession is inhibited by soluble DR5 (sDR5) in rats after AMI. First, we found that the level of TRAIL in serum was down-regulated in AMI patients. Then, TRAIL and DR5 expression was analysed in the myocardium of rats after AMI, and their expression was up-regulated. sDR5 treatment reduced the myocardial infarct size and the levels of CK-MB and cTn-I in serum. The expression of caspase 3 and PARP is decreased, but the anti-apoptotic factor Bcl-2 was increased in sDR5 treatment rats after AMI. DR5 expression was also analysed after sDR5 treatment and it was down-regulated, and a low level of DR5 expression seemed to be beneficial for the myocardium. Overall, our findings indicated that sDR5 decreases myocardial damage by inhibiting apoptosis in rat after AMI. We expect to observe the potential therapeutic effects of sDR5 on AMI in the future.

TRAIL-R3 Expression on Myeloid Leukemic Blasts Is Related to a Shortened Overall Survival.

Since chemotherapy and transplantation can cure only around 35% of patients with acute myeloid leukemia (AML), there is still need for complementary and targeted treatment modalities. One of them could be the use of TNF-related apoptosis-inducing ligand (TRAIL). TRAIL is expressed by effector T cells and induces apoptosis via the death receptor intrinsic pathway. Activation of this pathway in addition to the mitochondrial pathway (by chemotherapy) has synergistic effects in vitro. In human, 4 membrane bound receptors have been identified: two of them (R1 and R2) contain a functional death domain and are capable of starting the apoptotic cascade, and two others (R3 and R4) lack a functional death domain and function as decoy receptors. Most normal cells express R3 and R4, where many tumor cells express R1 and R2. This makes soluble recombinant TRAIL an attractive candidate for targeted therapy; phase 1 clinical studies for solid tumors are launched. Until now, sparse data on TRAIL sensitivity of myeloid leukemic cells have demonstrated low TRAIL sensitivity. We investigated blood and bone-marrow samples of 113 patients with AML for TRAIL receptor expression by flow-cytometry. In contrast with published data, we found presumably (pro-apoptotic) R1 and R2 expression (mean percentage positive cells 16% and 34%, range 0–79% and 0–97% respectively) versus R3 and R4 expression (mean 9% and 10%, range 0–71% an 0–45%) indicating a TRAIL sensitive profile for myeloid blasts. Surprisingly, the expression of the anti-apoptotic R3 strongly correlated to survival. Expression of > 25% blasts positive for R3 resulted in shortened overall survival (p=0.0051), see figure 1. In multivariate analysis R3 expression remained a significant prognostic factor next to cytogenetics (p=0.03 and p= 0.015 respectively). In vitro studies on 4 myeloid leukemic cell lines confirmed TRAIL sensitivity in cell lines that expressed R1 and R2. Furthermore, simultaneous expression of R3 clearly reduced the amount of apoptosis, suggesting that TRAIL effects are inhibited by binding to R3. TRAIL induction studies on fresh leukemic samples are currently underway in our laboratory.In conclusion, our data suggest that, in contrast to earlier reports, there might be a role for TRAIL in apoptosis induction of AML blasts. R3 expression is a strong predictor for overall survival and modulation of R3 might yield additional new therapeutic options for AML patients. [Display omitted]

TRAIL mediates and sustains constitutive NF-κB activation in LGL leukemia

AbstractLarge granular lymphocyte (LGL) leukemia results from clonal expansion of CD3+ cytotoxic T lymphocytes or CD3− natural killer (NK) cells. Chronic antigen stimulation is postulated to promote long-term survival of LGL leukemia cells through constitutive activation of multiple survival pathways, resulting in global dysregulation of apoptosis and resistance to activation-induced cell death. We reported previously that nuclear factor κB (NF-κB) is a central regulator of the survival network for leukemic LGL. However, the mechanisms that trigger constitutive activation of NF-κB in LGL leukemia remain undefined. Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is known to induce apoptosis in tumor cells but can also activate NF-κB through interaction with TRAIL receptors 1, 2, and 4 (also known as DR4, DR5, and DcR2, respectively). The role of TRAIL has not been studied in LGL leukemia. In this study, we hypothesized that TRAIL interaction with DcR2 contributes to NF-κB activation in LGL leukemia. We observed upregulated TRAIL messenger RNA and protein expression in LGL leukemia cells with elevated levels of soluble TRAIL protein in LGL leukemia patient sera. We also found that DcR2 is the predominant TRAIL receptor in LGL leukemia cells. We demonstrated that TRAIL-induced activation of DcR2 led to increased NF-κB activation in leukemic LGL. Conversely, interruption of TRAIL-DcR2 signaling led to decreased NF-κB activation. Finally, a potential therapeutic application of proteasome inhibitors (bortezomib and ixazomib), which are known to inhibit NF-κB, was identified through their ability to decrease proliferation and increase apoptosis in LGL leukemia cell lines and primary patient cells.

The role of TRAIL in fatigue induced by repeated stress from radiotherapy

Fatigue is one of the most common and debilitating side effects of cancer and cancer treatment, and yet its etiology remains elusive. The goal of this study is to understand the role of chronic inflammation in fatigue following repeated stress from radiotherapy. Fatigue and non-fatigue categories were assessed using ≥ 3-point change in Functional Assessment of Cancer Therapy-Fatigue questionnaire (FACT-F) administered to participants at baseline/before radiotherapy and one year post-radiotherapy. Whole genome microarray and cytokine multiplex panel were used to examine fatigue-related transcriptome and serum cytokine changes, respectively. The study included 86 subjects (discovery phase n = 40, validation phase n = 46). The sample in the discovery phase included men with prostate cancer scheduled to receive external-beam radiotherapy. A panel of 48 cytokines were measured and the significantly changed cytokine found in the discovery phase was validated using sera from a separate cohort of men two years after completing radiotherapy for prostate cancer at a different institution. Effects of the significantly changed cytokine on cell viability was quantified using the MTT assay. During the discovery phase, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and TRAIL decoy receptor, TNFRSF10C (TRAIL-R3), were significantly upregulated in fatigued (≥3-point decrease from baseline to 1yr-post radiotherapy) subjects (n = 15). In the validation phase, TRAIL correlated with fatigue scores 2yrs post-radiotherapy. TRAIL caused selective cytotoxicity in neuronal cells, but not in microglial and muscle cells, in vitro. Late-onset inflammation directed by TRAIL may play a role in fatigue pathogenesis post-repeated stress from irradiation.

Low Circulating TRAIL Levels Are Associated with Increase of Resistin and Lipocalin-2/ngal Adipokines in Postmenopausal Women.

Objective Tumor necrosis factor- (TNF-) related apoptosis-inducing ligand (TRAIL) is attracting attention for its role in the physiopathology of metabolic disease/diabetes. Evidence suggests that it might protect against metabolic abnormalities driven by obesity-induced dysregulated secretion of adipokines, but this role of TRAIL has not yet been fully established. On this basis, we aimed to investigate the potential association between TRAIL and adipokine levels in a cohort of subjects in which age/gender/hormonal interferences were excluded. Methods Serum levels of TRAIL and a panel of adipokines were measured in postmenopausal women (n = 147) stratified according to waist circumference measures as normal, overweight, or obese. The panel of adipokines included interleukin- (IL-) 6, IL-8, IL-1β, adipsin, lipocalin-2/neutrophil gelatinase-associated lipocalin (ngal), TNF-alpha, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, hepatocyte growth factor, resistin, leptin, adiponectin, and nerve growth factor. Results Low serum TRAIL concentration (deciles I–IV) was significantly and inversely correlated with resistin and lipocalin 2/ngal levels (r = −0.502 and p < 0.001 and r = −0.360 and p < 0.01, resp.). Both associations retained their statistical significance after adjustment for confounding factors, such as waist circumference and age. Conclusions Our data indicate a link between low circulating levels of TRAIL and markers of obesity-induced diseases (resistin and lipocalin-2/ngal), highlighting a new potential axis of TRAIL functions.

Roles and Clinical Applications of Biomarkers in Cardiovascular Disease

Due to the high rates of mortality and morbidity caused by Cardiovascular and Peripheral Vascular Disease (CPVD), great efforts have been made in order to improve diagnosis and primary and secondary prevention and treatment, even by discovering and using related biomarkers. As such, the articles contained in the present issue include both reviews and research articles focused on characterizing several biomarkers in order to evaluate their role in the field of CPVD. The review by S. de Franciscis et al. considers the current evidences of novel biomarkers with clear implications in the risk assessment, prevention strategies, and medical decision making in the main fields of CPVD, such as Hypertension, Coronary Heart Disease, Arterial Aneurysms, Carotid Artery Disease, Peripheral Artery Disease, Chronic Venous Disease, and Venous Thromboembolism. The study by Y. Hao et al. shows multiple metabolites that associated with risk of developing Hypertension (HYT). Specifically, low amino acid levels and gut microbiome seem to play an important role in the pathogenesis of this disease. J. Xu et al. confirm the already known association of genetic polymorphisms of ATP2B1 with the susceptibility to HYT in the Han Chinese population, particularly in the females, and found that the interaction of high BMI and ATP2B1 variants increased even more the susceptibility to Hypertension. Acute heart failure (AHF) is the most common reason of hospitalization in patients aged 65 and older, with mortality rate up to 30–40% within one year, and, in this context, Y. Wang et al. show that sequential monitoring of changes of N-terminal probrain natriuretic peptide (NT-proBNP) within the first days after acute heart failure (AHF) may be helpful for guiding clinical management of AHF patients. In ST-elevation myocardial infarction (STEMI) patients, it is pivotal to prevent AHF and recurrent thrombosis, and, in this context, M. Marinsek and A. Sinkovic show the beneficial effects of Ramipril and Losartan associated with dual antiplatelet therapy (DAPT) in respect to DAPT alone, by means of measuring the level of several biomarkers such as NT-proBNP, ejection fraction (EF), plasminogen-activator-inhibitor type 1 (PAI-1), and platelet aggregation by closure times (CT). As atherosclerosis and vascular calcification are dynamic processes, T.-L. Chuang et al. studied the association between the bony microarchitecture score (trabecular bone score, TBS) and coronary artery calcification (CAC) in adult subjects undergoing health exams and they found that advanced age was significantly associated with high CAC, while increased TBS was associated with moderate CAC, independent of age and other risk factors, and they concluded that further evidences were needed to confirm their data. Osteoprotegerin (OPG) and its ligands, receptor activator of nuclear factor κB ligand (RANKL) and TNF-related apoptosis-inducing ligand (TRAIL), are known players in osteoblastogenesis and osteoclastogenesis. In fact, they now represent also new biomarkers in the atherosclerosis and vascular calcification fields, as described by S. Bernardi et al. with evidences pointing towards a proatherogenic role for OPG and an antiatherogenic role for TRAIL. Misdiagnosis in Pulmonary Embolism (PE) may increase the related high mortality, and E. Gul et al. investigated the role of serum adiponectin levels and they found that adiponectin levels were significantly low in the patient group with PE compared to patients without PE, and they concluded that these findings may have important implications in the diagnosis of PE. The current literature abundantly describes that microRNAs (miRNAs) and long noncoding RNAs are potential new biomarkers for most pathophysiological processes, including cardiovascular diseases and metabolic disorders. In this special issue, L. Louvet et al. show, using a human in vitro model of vascular smooth muscle cells, that several miRNAs are implicated in the preventive role of magnesium towards vascular calcifications. A. Carino et al. show that the levels of several circulating miRNAs are altered during the switch from clopidogrel to ticagrelor. Their results hint at the possibility of using miRNAs as noninvading biomarkers to determine primary end points in the CPVD field, although further work will be necessary to clearly establish that. Finally, the very recent discovery of long noncoding RNAs, defined as non-protein coding transcripts longer than 200 nucleotides, opens new horizons in the CPVD field, as evidenced by the paper of Y. Yan et al., that shows that the circulating level of the long noncoding RNA UCA1 is altered during AHF. We hope that this special issue would throw light on the major issues in the area of biomarkers in CPVD and would attract the interest of scientific community in order to pursue further investigations leading to the discovery of novel biomarkers and to their rapid implementation into clinical practice. Stefano de Franciscis Laurent Metzinger Raffaele Serra

A pathogenic role for tumor necrosis factor-related apoptosis-inducing ligand in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a life-threatening inflammatory respiratory disorder, often induced by cigarette smoke (CS) exposure. The development of effective therapies is impaired by a lack of understanding of the underlining mechanisms. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytokine with inflammatory and apoptotic properties. We interrogated a mouse model of CS-induced experimental COPD and human tissues to identify a novel role for TRAIL in COPD pathogenesis. CS exposure of wild-type mice increased TRAIL and its receptor messenger RNA (mRNA) expression and protein levels, as well as the number of TRAIL(+)CD11b(+) monocytes in the lung. TRAIL and its receptor mRNA were also increased in human COPD. CS-exposed TRAIL-deficient mice had decreased pulmonary inflammation, pro-inflammatory mediators, emphysema-like alveolar enlargement, and improved lung function. TRAIL-deficient mice also developed spontaneous small airway changes with increased epithelial cell thickness and collagen deposition, independent of CS exposure. Importantly, therapeutic neutralization of TRAIL, after the establishment of early-stage experimental COPD, reduced pulmonary inflammation, emphysema-like alveolar enlargement, and small airway changes. These data provide further evidence for TRAIL being a pivotal inflammatory factor in respiratory diseases, and the first preclinical evidence to suggest that therapeutic agents that target TRAIL may be effective in COPD therapy.

Abstract A28: TRAIL mediated reduction of an immunogenic cell death protein, heat shock protein 70, in glioblastoma

Abstract There are various Damage-Associated Molecular Patterns (DAMPs) that are recognizable by the immune system in the cancer microenvironment. DAMPs are revealed under a specific type of cell death termed immunogenic cell death in which stimuli force the cancer cells to die and leave antigen traces such as heat shock proteins that can be used against the disease. The stimulus of interest in this study was recombinant human Tumor-necrosis factor-related apoptosis-inducing ligand (TRAIL) which was known to selectively kill cancer cells such as glioblastoma cells. This study examined the role of TRAIL in immunogenic cell death for brain cancer. High density T98G glioblastoma cells were cultured with or without 50 ng/ml recombinant human TRAIL for four days. The trypan blue exclusion assay revealed that the average death rate for the TRAIL treated glioblastoma cells was 42%. Furthermore, western blot analysis showed that TRAIL treated cells had a reduction in heat shock protein 70 expression. Previous studies in the literature showed heat shock protein 70 mediated apoptosis resistance in cancer cells. The current study suggests that, even in the absence of any other inhibitors, heat shock protein 70 down-regulation via TRAIL may cause the chemoresistant glioblastoma cells to become susceptible to TRAIL-mediated cell death. Future studies will further investigate the relationship between DAMPs and TRAIL and the extent to which TRAIL generates sufficient apoptotic glioblastoma cells that would serve as the antigenic source for T cell immunotherapy regimens. Disclaimer: This research was supported in part by the James A. Haley Veterans' Hospital. The contents of this publication do not represent the views of the Department of Veterans Affairs or the United States Government. Citation Format: Andrea N. McCray. TRAIL mediated reduction of an immunogenic cell death protein, heat shock protein 70, in glioblastoma. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr A28.

Tumour necrosis factor-related apoptosis inducing ligand promotes the development of experimental chronic obstructive pulmonary disease (MUC1P.905)

Abstract Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide and causes significant healthcare and economic burden. Cigarette smoking is a major risk factor. There is a lack of effective treatments for COPD due to the poor understanding of the underlining mechanisms. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is implicated in respiratory diseases such as asthma and pulmonary fibrosis. However, the role of TRAIL in the pathogenesis of COPD is unknown. In this study, TRAIL mRNA expression and/or protein levels in the lung (airway and parenchyma) and serum were increased in a mouse model of cigarette smoke-induced experimental COPD. Genetic deletion of TRAIL significantly reduced cigarette smoke-induced pulmonary inflammation, expression of key pro-inflammatory mediators, emphysema-like alveolar enlargement and improved lung function in experimental COPD. Interestingly, genetic deletion of TRAIL led to spontaneous small airway remodelling characterized by increased airway epithelial cell thickness and collagen deposition. Importantly, antibody-mediated neutralization of TRAIL reduced cigarette smoke-induced pulmonary inflammation, emphysema-like alveolar enlargement and small airway remodelling. Our study is the first to show that TRAIL plays an important role in the pathogenesis of COPD and provides further evidence for TRAIL being a pivotal inflammatory cytokine in respiratory diseases.

Role and Potential Therapeutic Use of TRAIL in Diabetes

TNF-related apoptosis-inducing ligand (TRAIL) is a TNF superfamily member, defined by its high homology to CD95L/FasL and TNF-alpha. It is known for its strong selective apoptotic effect on many transformed cell lines and tumor cells but not in most normal cell types. TRAIL appears to be a more complex molecule than predicted, with a higher therapeutic potential than previously anticipated. This is mainly because it has 5 different receptors that it can bind to in contrast to other TNF family members with one or two receptors; it is expressed widely in human tissues; and it has anti-inflammatory effects. For instance, type 1 diabetes (T1D) development was exacarbated in non-obese diabetic (NOD) mice when TRAIL function was blocked, and TRAIL -/- C57BL/6 mice developed T1D at a much earlier stage following streptozotocin (STZ) injection, compared to mice which displayed normal TRAIL expression. Furthermore, TRAIL displayed a pro-angiogenic effect in primary human vascular endothelial cells. It also induced survival against the apoptosis triggered by pro-inflammatory cytokines in vascular smooth muscle cells, as well as promoting migration and proliferation. Results from studies aiming to clear out the role of TRAIL in diabetes development suggest a protective role for this molecule on beta cells. TRAIL generally does not induce beta cell apoptosis, plays a protective role in these cells against the apoptotic effects of cytokines such as FasL and TNF-alpha, and its receptors are expressed at a significant level in the pancreatic islets. While TRAIL’s role or potential use in diabetes is investigated in various cell and animal systems by many reasearch groups including ours, it is still not clearly identified. Our previous and current results, which mainly support a protective role for TRAIL, will be discussed comparatively with similar and contradictory results of other groups.

Abstract 18060: TRAIL Promotes Angiogenesis and Ischemia-Induced Neovascularisation via NOX4, H2O2 and Nitric Oxide-Dependent Mechanisms

Background: Angiogenesis and neovascularization are essential processes that follow ischemia insults. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) not only induces endothelial cell (EC) death and inhibits angiogenesis, but also promotes EC migration, invasion and proliferation in vitro . These seemingly opposite effects make its role in angiogenesis in vivo unclear. Using TRAIL -/- and wild-type mice, we sought to determine the role of TRAIL in angiogenesis and neovascularisation. We also sought mechanisms in vitro . Methods and Results: Reduced vascularisation assessed by real-time in vivo 3D Vevo ultrasound imaging and CD31 staining was observed in TRAIL -/- mice 28 d after hindlimb ischemia. Moreover, reduced capillary formation and increased apoptosis was evident in TRAIL -/- muscles even at 3 d after ischemic surgery. We have previously shown that fibroblast growth factor-2 (FGF-2), a potent angiogenic factor, regulates TRAIL gene expression in vascular smooth muscle cells. Indeed, FGF-2 also regulates TRAIL expression in ECs, and FGF-2-inducible proliferation, migration and tubule formation was inhibited with siRNA targeting TRAIL. Notably, both FGF-2 and TRAIL significantly increased NOX4 expression. TRAIL-inducible angiogenic activity in ECs was inhibited with siRNAs targeting NOX4, and consistent with these, NOX4 mRNA was reduced in 3 d ischemic hindlimbs of TRAIL -/- mice. TRAIL stimulated intracellular H 2 O 2 levels in ECs, and TRAIL-inducible proliferation, migration and tubule formation was inhibited with not only PEG-catalase, a H 2 O 2 scavenger, but also blocked with L-NAME, a nitric oxide synthase inhibitor. Conclusions: This is the first demonstration showing that TRAIL promotes angiogenesis in vivo . We show for the first time that the TRAIL stimulates NOX4 expression to mediate nitric oxide-dependent angiogenic effects. This has significant therapeutic implications such that TRAIL may improve the angiogenic response to ischemia and increase perfusion recovery in patients with CVD and diabetes.

TRAIL protects against endothelium injury in diabetes via Akt-eNOS signaling

Objective: Although some studies have suggested that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) might be involved in atherosclerosis, its potential role in endothelial dysfunction and apoptosis has not been investigated. The aim of this study was to evaluate the impact of TRAIL on endothelium injury in diabetes and the underlying mechanism involved. Methods: Experimental diabetes was induced using streptozotocin in rats. Cohorts of diabetic rats received an intraperitoneal injection of recombinant TRAIL (rTRAIL) 20 μg per rat weekly for 6 weeks. Endothelial function was assessed by acetylcholine (Ach)-induced endothelium-dependent vasorelaxation using aortic rings. The antiapoptotic effects of TRAIL and its possible mechanisms were investigated in cultured human umbilical vein endothelial cells (HUVECs). Results: Experimental diabetes attenuated endothelial function, which was significantly improved by rTRAIL treatment (63.5 ± 4.62% vs. 78.4 ± 2.79%, P < 0.01). In cultured HUVECs, TRAIL suppressed high glucose-induced reactive oxygen species (ROS) production and cellular apoptosis, as well as the production of NADPH oxidase. Furthermore, the antiapoptotic actions of TRAIL were accompanied by Akt and endothelial nitric oxide synthase (eNOS) phosphorylation, as well as increased NO production. Conclusions: These findings indicate a novel role of TRAIL in the protection against vascular injury in diabetes. The protective effects of TRAIL are dependent on the activation of Akt-dependent eNOS signaling.

Trail Overexpression Inversely Correlates with Histological Differentiation in Intestinal-Type Sinonasal Adenocarcinoma

Introduction. Despite their histological resemblance to colorectal adenocarcinoma, there is some information about the molecular events involved in the pathogenesis of intestinal-type sinonasal adenocarcinomas (ITACs). To evaluate the possible role of TNF-related apoptosis-inducing ligand (TRAIL) gene defects in ITAC, by investigating the immunohistochemical expression of TRAIL gene product in a group of ethmoidal ITACs associated with occupational exposure. Material and Methods. Retrospective study on 23 patients with pathological diagnosis of primary ethmoidal ITAC. Representative formalin-fixed, paraffin-embedded block from each case was selected for immunohistochemical studies using the antibody against TRAIL. Clinicopathological data were also correlated with the staining results. Results. The immunohistochemical examination demonstrated that poorly differentiated cases showed a higher percentage of TRAIL expressing cells compared to well-differentiated cases. No correlation was found with other clinicopathological parameters, including T, stage and relapses. Conclusion. The relationship between upregulation of TRAIL and poorly differentiated ethmoidal adenocarcinomas suggests that the mutation of this gene, in combination with additional genetic events, could play a role in the pathogenesis of ITAC.

Blockade of Death Ligand TRAIL Inhibits Renal Ischemia Reperfusion Injury

Renal ischemia-reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI). Many investigators have reported that cell death via apoptosis significantly contributed to the pathophysiology of renal IRI. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor superfamily, and induces apoptosis and inflammation. However, the role of TRAIL in renal IRI is unclear. Here, we investigated whether TRAIL contributes to renal IRI and whether TRAIL blockade could attenuate renal IRI. AKI was induced by unilateral clamping of the renal pedicle for 60 min in male FVB/N mice. We found that the expression of TRAIL and its receptors were highly upregulated in renal tubular cells in renal IRI. Neutralizing anti-TRAIL antibody or its control IgG was given 24 hr before ischemia and a half-dose booster injection was administered into the peritoneal cavity immediately after reperfusion. We found that TRAIL blockade inhibited tubular apoptosis and reduced the accumulation of neutrophils and macrophages. Furthermore, TRAIL blockade attenuated renal fibrosis and atrophy after IRI. In conclusion, our study suggests that TRAIL is a critical pathogenic factor in renal IRI, and that TRAIL could be a new therapeutic target for the prevention of renal IRI.

Role of TNF-related apoptosis-inducing ligand (TRAIL) in the pathogenesis of varicocele-induced testicular dysfunction

The higher frequency of varicocele in men with infertility has drawn attention and resulted in increased research at the molecular level towards treatments. The aim of this study was to investigate the role of tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) and its receptors in varicocele-induced testicular dysfunction in an experimental rat model. The rats were divided into three groups: control, sham and varicocele. Varicoceles in rats were induced by partial ligation of the left renal vein and left testes. The rats were analyzed 13 weeks after surgery. The degree of DNA fragmentation within cells in the testis was determined using terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling (TUNEL) assay. Tubule degeneration was evaluated using the Johnsen score. The expression of TRAIL and its receptors was detected by immunohistochemical and Western blotting techniques. The apoptotic index, Johnsen score and the expression of TRAIL and TRAIL receptors were examined. The data are presented as the mean±s.d. and were analyzed using computer software. The Kruskal-Wallis and Dunn's multiple comparison tests were used in the statistical analyses. The germ cell apoptotic index was increased in rats with varicoceles when compared with the sham and control groups (P=0.0031). The Johnsen score was significantly decreased in the varicocele group when compared with the sham and control groups (P<0.0001). Immunohistochemical and Western blotting analyses showed that after varicocele induction, the expression of TRAIL-R1 and TRAIL-R4 in germ cells was increased and the expression of TRAIL-R2 was decreased. There are no significant differences among the groups in terms of TRAIL and TRAIL-R3 receptor expression. The results of this study indicate that TRAIL and its receptors may have a potential role in the pathogenesis of varicocele-induced testicular dysfunction.

TNF-related apoptosis-inducing ligand levels in rheumatoid arthritis, osteoarthritis, and spondyloarthritis

Abstract Introduction Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a tumor necrosis factor (TNF) family member capable of inducing apoptosis in many cell types. Data suggest that TRAIL/TRAIL receptor expression profiles on Tcells might be important in rheumatoid arthritis (RA) pathogenesis. Objectives To characterize the role of TNF-related apoptosis-inducing ligand (TRAIL) in rheumatoid arthritis (RA) and to explore whether TRAIL investigated in serum and synovial fluid were associated with clinical, laboratory, and radiological variables of RA disease activity and severity. Methods Circulating levels of TRAIL were measured by ELISA in serum samples obtained from 50 patients with RA (during activity and quiescence), 20 patients with osteoarthritis, 15 patients with spondyloarthritis, and 50 normal healthy individuals serving as controls. Results The median serum TRAIL concentrations were increasingly higher across the following groups: healthy controls (185pg/ml), and RA patients with active disease (1625 pg/ml; P=0.0001 vs. controls) and inactive disease (1750 pg/ml; P=0.0001 vs. controls) (inactive vs. active RA; P = 0.07). It is noteworthy that RA patients had significant higher median TRAIL concentrations as compared with osteoarthritis patients whether during activity or during quiescence. However, the median levels of TRAIL were statistically comparable in RA and spondyloarthritis patients. The median and mean ± SD synovial fluid TRAIL concentrations were 2100 and 1765.8 ± 752 pg/ml, respectively. The levels of TRAIL in synovial fluid from the patients were higher than those in sera from both the patients and the healthy individuals. TRAIL concentrations in paired sera and synovial fluid samples could be related to each other. Serum and synovial concentrations of TRAIL were correlated positively with the total number of joints with active arthritis and with the overall articular severity score. Patients with Larsen index and total radiographic score of at least 1 had significantly higher serum TRAIL levels than patients with indices and scores 1 or less. Conclusion Upregulated expression of TRAIL might be somewhat useful for the evaluation of RA disease activity and progression, although its increment is not disease specific.

Potential Role of TRAIL in the Management of Autoimmune Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is an autoimmune disease, due to the immune-mediated destruction of pancreatic β-cells, whose incidence has been steadily increasing during the last decades. Insulin replacement therapy can treat T1DM, which, however, is still associated with substantial morbidity and mortality. For this reason, great effort is being put into developing strategies that could eventually prevent and/or cure this disease. These strategies are mainly focused on blocking the immune system from attacking β-cells together with functional islet restoration either by regeneration or transplantation. Recent experimental evidences suggest that TNFrelated apoptosis-inducing ligand (TRAIL), which is an immune system modulator protein, could represent an interesting candidate for the cure for T1DM and/or its complications. Here we review the evidences on the potential role of TRAIL in the management of T1DM.