Quantification and detection of DcR3, a decoy receptor in TNFR family

Decoy receptor 3 as a prognostic biomarker for sepsis and septic shock according to the Sepsis-3 definitions

Objectives

The present study was conducted to reappraise the prognostic value of decoy receptor 3 (DcR3) for patients with sepsis and septic shock according to the latest Sepsis-3 definitions.

Methods

Subjects suffering from sepsis or septic shock were enrolled within 6 h of admission. The Sequential Organ Failure Assessment (SOFA) score and the plasma levels of DcR3, C-reactive protein, procalcitonin, and interleukin-6 were measured. Group comparisons were made based on the survival status on day 28 after onset. Predictors of mortality were assessed using the Cox proportional hazard models, and survival curves were plotted with the Kaplan-Meier method. Discriminative performances of single and combined indicators were evaluated via the areas under receiver operating characteristic curves.

Results

Among 143 eligible sepsis cases, 77 developed septic shock, and the 28-day mortality rates were 32.2% and 45.5%, respectively. Regardless of the population (all sepsis or septic shock), non-survivors exhibited significantly higher DcR3 levels compared to survivors (median 4.19 vs. 2.64 ng/mL and 4.37 vs. 3.18 ng/mL, respectively; p < 0.001 and p = 0.002, respectively). DcR3 levels were most correlated with organ dysfunction presented by SOFA scores (correlation coefficient = 0.347 and 0.308, respectively; p = 0.001 and 0.016, respectively) but did not differ among the various pathogenic microbes of infection. Multivariate Cox regression identified DcR3 as an independent predictor of mortality [hazard ratio (95% confidence interval): 1.570 (1.048-2.352) and 1.828 (1.047-3.194), respectively; p = 0.029 and 0.034, respectively]. Kaplan-Meier analysis showed that elevated DcR3 concentrations were associated with significantly lower survival rates (p = 0.001 and 0.013, respectively). The areas under receiver operating characteristic curves of DcR3 alone for predicting outcome were superior to that of the other three biomarkers (0.731 and 0.711, respectively) and could be further improved when coupled with SOFA scores (0.803 and 0.784, respectively).

Conclusions

DcR3 is a valuable prognostic biomarker for sepsis and septic shock, offering the potential to predict 28-day mortality in clinical settings.

Hypomethylation of Tumor necrosis factor-like cytokine 1A(TL1A) and its decoy receptor 3 expressive level increase has diagnostic value in HBV-associated cirrhosis

For patients with cirrhosis, early diagnosis is the key to delaying the development of liver fibrosis and improving prognosis. This study aimed to investigate the clinical significance of TL1A, which is a susceptibility gene for hepatic fibrosis, and DR3 in the development of cirrhosis and fibrosis. We analyzed the expression of TL1A, DR3, and other inflammatory cytokines associated with liver fibrosis in serum and PBMCs in 200 patients.TL1A methylation level was lower in patients with HBV-associated LC than in the other groups. In addition, the mRNA level and serum of TL1A and DR3 expression levels were found to increase in the LC. Hypomethylation of the TL1A promoter is present in HBV-associated LC, and TL1A and DR3 are highly expressed in HBV-associated cirrhosis. These results indicate that TL1A and DR3 may play an important role in the pathogenesis of LC and TL1A methylation levels may serve as a noninvasive biomarker for early diagnosis and progression of LC.

Level of Decoy Receptor 3 for Monitoring Clinical Progression of Severe Burn Patients

The clinical value of Decoy receptor 3 (DcR3) in severe burn is investigated. Ten patients with severe burns were monitored for DcR3, PCT, CRP, IL6, SOFA score, white blood cell (WBC), and platelet. The correlations were analyzed. DcR3 increased on day 1. The nonsurvivors had a steady high level of DcR3 while the survivors had a relatively low level of DcR3. The peak magnitude of DcR3 was high in five nonsurvivors and low in five survivors without overlap. Three patients had a continuously increasing DcR3 level and then died. In the other two nonsurvivors, DcR3 reached the peak and then decreased before death. DcR3 correlated well with PCT (ρ = 0.4469, P < .0001), less with CRP, platelet, IL6, SOFA score and WBC (ρ = 0.4369, 0.4078, 0.3995, 0.2631, 0.1504, respectively, all P < .001). To explore the mechanisms, the HaCaT or THP-1 cells were stimulated by the plasma of burn patients, 45°C, LPS or stimulators of TLRs or NOD2 (PGN, CL264, MDP, iE-DAP, Gardiquimod), and their DcR3 was increased, which could be reduced by GDC-0941 or BEZ235 (inhibitors of PI3K and mTOR). The levels of DcR3 appeared to be a useful biomarker for monitoring the clinical severity and a predictor of mortality of severe burns.

Role of prognostic biomarker decoy receptor 3 and immunomodulation in kidney diseases

Decoy receptor 3 (DcR3), also known as tumor necrosis factor receptor superfamily member 6b (TNFRSF6B), was recently identified as a novel biomarker for predicting progression of kidney diseases with potential immune modulation. The purpose of this review is to discuss the current evidence related to DcR3 in kidney diseases and to compare the differences between human and animal studies both in vivo and in vitro. High serum DcR3 predicts the occurrence of peritonitis in patients receiving chronic peritoneal dialysis and is positively correlated with inflammatory markers such as interleukin-6, high-sensitivity C-reactive protein, and adhesion molecules in patients on maintenance hemodialysis (HD). Higher serum DcR3 levels not only independently predict cardiovascular and all-cause mortality in HD patients but also identify older adults on HD at risk of protein-energy wasting in combination with a low geriatric nutritional risk index. Recently, renal tubular epithelial cells (RTECs) expressing DcR3 have also been used to predict progression of chronic kidney disease. Expression of DcR3 was correlated with a 2-fold increase in serum creatinine or failure of kidney allograft. DcR3 could protect renal myofibroblasts against Fas-induced apoptosis and subsequently lead to renal fibrosis. Locally expressed DcR3 in the RTECs may suppress the FasL-Fas-mediated apoptosis of T cells, resulting in an accumulation of allo-reactive T cells. In addition to traditional biological functions, recombinant DcR3.Fc and cytomegalovirus promoter-driven human DcR3 plasmid are able to modulate the activation and differentiation of dendritic cells and macrophages via "non-decoy" action. Both progressive IgA nephropathy and autoimmune crescentic glomerulonephritis in mice can be suppressed after hydrodynamics-based gene delivery of DcR3 plasmid. DcR3-mediated effects in vitro could be surveyed via over-expressing DcR3 or addition of recombinant DcR3.Fc, and CD68-driven DcR3 transgenic mice are suitable for investigating systemic effect in vivo. Inhibition of DcR3 expression in human may be a promising approach for pathomechanism.

Expression and Clinical Significance of Decoy Receptor 3 in Acute-on-Chronic Liver Failure

AIMS

To explore the expression level and clinical significance of decoy receptor 3 (DcR3) in patients with acute-on-chronic liver failure (ACLF).

METHODS

Serum DcR3 levels were measured by enzyme-linked immunosorbent assay (ELISA) in 76 patients with ACLF and 41 non-ACLF patients with chronic liver disease. Blood routine and liver functions were accessed for their correlations with DcR3.

RESULTS

Serum DcR3 in ACLF patients was significantly higher than that in non-ACLF patients. It was positively correlated with neutrophilic granulocyte, aspartate aminotransferase, prothrombin time, and international standardized ratio, but negatively correlated with platelet and serum albumin. At the early stage, the level of DcR3 was not significantly different between the survival and nonsurvival group of ACLF. However, at the late stage, DcR3 increased in nonsurvival and gradually decreased in survivals. The baseline DcR3 could not sufficiently predict the outcome of ACLF, while the change of DcR3 within the first week displayed a better predictive value than model for end-stage liver disease (MELD) score.

CONCLUSIONS

DcR3 was highly expressed in patients with ACLF and correlated with several clinical indices. Dynamic change of DcR3 might predict the prognosis of ACLF.

Lymphotoxin expression in human and murine renal allografts

The kidney is the most frequently transplanted solid organ. Recruitment of inflammatory cells, ranging from diffuse to nodular accumulations with defined microarchitecture, is a hallmark of acute and chronic renal allograft injury. Lymphotoxins (LTs) mediate the communication of lymphocytes and stromal cells and play a pivotal role in chronic inflammation and formation of lymphoid tissue. The aim of this study was to assess the expression of members of the LT system in acute rejection (AR) and chronic renal allograft injury such as transplant glomerulopathy (TG) and interstitial fibrosis/tubular atrophy (IFTA). We investigated differentially regulated components in transcriptomes of human renal allograft biopsies. By microarray analysis, we found the upregulation of LTβ, LIGHT, HVEM and TNF receptors 1 and 2 in AR and IFTA in human renal allograft biopsies. In addition, there was clear evidence for the activation of the NFκB pathway, most likely a consequence of LTβ receptor stimulation. In human renal allograft biopsies with transplant glomerulopathy (TG) two distinct transcriptional patterns of LT activation were revealed. By quantitative RT-PCR robust upregulation of LTα, LTβ and LIGHT was shown in biopsies with borderline lesions and AR. Immunohistochemistry revealed expression of LTβ in tubular epithelial cells and inflammatory infiltrates in transplant biopsies with AR and IFTA. Finally, activation of LT signaling was reproduced in a murine model of renal transplantation with AR. In summary, our results indicate a potential role of the LT system in acute renal allograft rejection and chronic transplant injury. Activation of the LT system in allograft rejection in rodents indicates a species independent mechanism. The functional role of the LT system in acute renal allograft rejection and chronic injury remains to be determined.

DcR3, a new biomarker for sepsis, correlates with infection severity and procalcitonin

Early diagnosis of sepsis is critical for successful treatment. The clinical value of DcR3 in early diagnosis of sepsis was determined in a dynamic follow-up study. Alterations in plasma levels of DcR3, PCT, CRP, and IL-6 were measured by ELISA and compared among patients with sepsis (n = 134), SIRS (n = 60) and normal adults (n = 50). Correlations and dynamic patterns among the biomarkers, APACHE II scores, clinical outcomes, and pathogens were also examined. Plasma DcR3 was significantly increased in sepsis compared to SIRS and normal adults (median 3.87 vs. 1.28 and 0.17 ng/ml). The elevated DcR3 could be detected in 97.60% sepsis patients 1–2 days prior to the result of blood culture reported. For diagnosis of sepsis, the sensitivity was 97.69% and specificity 98.04%; and for differential diagnosis of sepsis from SIRS, the sensitivity was 90.77% and specificity 98.40%. DcR3 level was positively correlated with severity of sepsis (r_s = 0.82). In 41 patients who died of sepsis, DcR3 elevated as early as 1–2 days before blood culture and peaked on day 3 after blood culture performed. In 90% of sepsis patients, the dynamic alteration pattern of DcR3 was identical to that of PCT, while pattern of 10% patients differed in which clinical data was consistent with DcR3. In 13% sepsis patients, while PCT remained normal, DcR3 levels were at a high level. DcR3 levels had no difference among various pathogens infected. DcR3, a new biomarker, will aid in early diagnosis of sepsis and monitoring its outcome, especially when sepsis patients were PCT negative.

Decoy receptor 3 down-regulates centrosomal protein 70 kDa specifically in rheumatoid synovial fibroblasts

OBJECTIVES

Decoy receptor 3 (DcR3) competitively binds to Fas ligand, lymphotoxin-related inducible ligand that competes for glycoprotein D binding to herpes virus entry mediator on T cells (LIGHT) and TNF-like ligand 1A (TL1A), thereby preventing their effects. Using a microarray assay, we previously newly identified centrosomal protein 70 kDa (CEP70) as one of the genes whose expression in fibroblast-like synoviocytes from patients with rheumatoid arthritis (RA-FLS) is reduced by DcR3. Here, we investigated the significance of DcR3 regulation of CEP70 for RA-FLS.

METHODS

Synovial samples were obtained from RA patients who had never been treated with biologics and from osteoarthritis (OA) patients. CEP70 mRNA expression was quantified using RT-qPCR analysis. CEP70 protein expression was assessed using immunohistochemical and western blot analyses.

RESULTS

CEP70 was expressed predominantly in the superficial lining layer in RA synovial tissue. CEP70 expression was dose-dependently downregulated by DcR3-Fc in RA-FLS but was not downregulated in OA-FLS. TL1A antibody prevented the DcR3-Fc inhibitory effects on CEP70 expression in RA-FLS.

CONCLUSIONS

These results indicated that DcR3 reduces CEP70 expression in RA-FLS by binding to membrane-bound TL1A and may suppress RA-FLS proliferation. The reduction in CEP70 expression by DcR3/TL1A signaling may control the hyperplasia of RA synovium.

Elevated Serum Levels of the Antiapoptotic Protein Decoy-Receptor 3 Are Associated with Advanced Liver Disease

Background. Decoy-receptor 3 (DcR3) exerts antiapoptotic and immunomodulatory function and is overexpressed in neoplastic and inflammatory conditions. Serum DcR3 (sDcR3) levels during the chronic hepatitis/cirrhosis/hepatocellular carcinoma (HCC) sequence have not been explored. Objective. To assess the levels and significance of sDcR3 protein in various stages of chronic liver disease. Methods. We compared sDcR3 levels between healthy controls and patients with chronic viral hepatitis (CVH), decompensated cirrhosis (DC), and HCC. Correlations between sDcR3 levels and various patient- and disease-related factors were analyzed. Results. sDcR3 levels were significantly higher in patients with CVH than in controls (P < 0.01). sDcR3 levels were elevated in DC and HCC, being significantly higher compared not only to controls (P < 0.001 for both) but to CVH patients as well (P < 0.001 for both). In addition, DcR3 protein was detected in large quantities in the ascitic fluid of cirrhotics. In patients with CVH, sDcR3 significantly correlated to fibrosis severity, as estimated by Ishak score (P = 0.019) or by liver stiffness measured with elastography (Spearman r = 0.698, P < 0.001). In cirrhotic patients, significant positive correlations were observed between sDcR3 levels and markers of severity of hepatic impairment, including MELD score (r = 0.653, P < 0.001). Conclusions. Circulating levels of DcR3 are elevated during chronic liver disease and correlate with severity of liver damage. sDcR3 may serve as marker for liver fibrosis severity and progression to end-stage liver disease.

Interleukin‑12B is upregulated by decoy receptor 3 in rheumatoid synovial fibroblasts

Decoy receptor 3 (DcR3) competitively binds to three ligands, Fas ligand, lymphotoxin‑related inducible ligand that competes for glycoprotein D binding to herpesvirus entry mediator on T cells and tumor necrosis factor‑like ligand 1A (TL1A), to prevent their effects. Recent studies have suggested that DcR3 directly affects cells as a ligand. Using a microarray assay, our group newly identified interleukin (IL)‑12B, which encodes the p40 subunit common to IL‑12 and IL‑23, as one of the genes for which expression in fibroblast‑like synoviocytes from patients with rheumatoid arthritis (RA‑FLS) is induced by DcR3. The present study demonstrated that IL‑12B mRNA expression was upregulated by DcR3‑Fc in RA‑FLS in a dose‑dependent manner, but not in OA‑FLS. IL‑12B p40 protein in RA‑FLS was increased when stimulated with DcR3‑Fc. Pre‑treatment with anti‑TL1A antibody suppressed the upregulation of IL‑12B mRNA in RA‑FLS stimulated with DcR3‑Fc. DcR3 mRNA expression in RA‑FLS was induced by IL‑23, but not by IL‑12. These results indicated that DcR3 may increase IL‑12 or IL‑23 by inducing IL‑12B p40 expression via membrane‑bound TL1A on RA‑FLS and that IL‑23 reciprocally induces DcR3 expression in RA‑FLS. DcR3 and IL‑23 may interact in a feedback loop that aggravates local inflammation in patients with RA.

Usefulness of Circulating Decoy Receptor 3 in Predicting Coronary Artery Disease Severity and Future Major Adverse Cardiovascular Events in Patients With Multivessel Coronary Artery Disease

Decoy receptor 3 (DcR3), a member of the tumor necrosis factor receptor superfamily, is an antiapoptotic soluble receptor considered to play an important role in immune modulation and has pro-inflammatory functions. This study was designed to test whether circulating DcR3 levels are associated with coronary artery disease (CAD) severity and predict future major adverse cardiovascular events (MACEs) in patients with CAD. Circulating DcR3 levels and the Syntax score (SXscore) were determined in patients with multivessel CAD. The primary end point was the MACE within 12 months. In total, 152 consecutive patients with angiographically confirmed multivessel CAD who had received percutaneous coronary intervention were enrolled and were divided into 3 groups according to CAD lesion severity. Group 1 was defined as low SXscore (≤13), group 2 as intermediate SXscore (>13 and ≤22), and group 3 as high SXscore (>22). DcR3 levels were significantly higher in the high SXscore group than the other 2 groups (13,602 ± 7,256 vs 8,025 ± 7,789 vs 4,637 ± 4,403 pg/ml, p <0.001). By multivariate analysis, circulating DcR3 levels were identified as an independent predictor for high SXscore (adjusted odds ratio 1.15, 95% confidence interval 1.09 to 1.21; p <0.001). The Kaplan-Meier analysis showed that increased circulating DcR3 levels are associated with enhanced 1-year MACE in patients with multivessel CAD (log-rank p <0.001). In conclusion, increased circulating DcR3 levels are associated with CAD severity and predict future MACE in patients with multivessel CAD.

Expression of decoy receptor 3 in kidneys is associated with allograft survival after kidney transplant rejection

Decoy receptor 3 (DcR3) expression in kidneys has been shown to predict progression of chronic kidney disease. We prospectively investigated a cohort comprising 96 renal transplant recipients (RTRs) undergoing graft kidney biopsies. Computer-assisted quantitative immunohistochemical staining value of DcR3 in renal tubular epithelial cells (RTECs) was used to determine the predictive role of DcR3 in kidney disease progression. The primary end point was doubling of serum creatinine and/or graft failure. A multivariate Cox proportional hazards model was used to assess the risk of DcR3 expression in rejected kidney grafts toward the renal end point. In total, RTRs with kidney allograft rejection were evaluated and the median follow-up was 30.9 months. The greater expression of DcR3 immunoreactivity in RTECs was correlated with a higher rate of the histopathological concordance of acute T cell-mediated rejection. Compared with 65 non-progressors, 31 progressors had higher DcR3 expression (HDE) regardless of the traditional risk factors. Cox regression analysis showed HDE was significantly associated with the risk of renal end point with a hazard ratio of 3.19 (95% confidence interval, 1.40 to 7.27; P = 0.006) after adjusting for other variables. In repetitive biopsies, HDE in tissue showed rapid kidney disease progression due to persistent inflammation.

Absolute quantification of DcR3 and GDF15 from human serum by LC-ESI MS

Biomarkers are widely used in clinical diagnosis, prognosis and therapy monitoring. Here, we developed a protocol for the efficient and selective enrichment of small and low concentrated biomarkers from human serum, involving a 95% effective depletion of high-abundant serum proteins by partial denaturation and enrichment of low-abundant biomarkers by size exclusion chromatography. The recovery of low-abundance biomarkers was above 97%. Using this protocol, we quantified the tumour markers DcR3 and growth/differentiation factor (GDF)15 from 100 μl human serum by isotope dilution mass spectrometry, using ¹⁵N metabolically labelled and concatamerized fingerprint peptides for the both proteins. Analysis of three different fingerprint peptides for each protein by liquid chromatography electrospray ionization mass spectrometry resulted in comparable concentrations in three healthy human serum samples (DcR3: 27.23 ± 2.49 fmol/ml; GDF15: 98.11 ± 0.49 fmol/ml). In contrast, serum levels were significantly elevated in tumour patients for DcR3 (116.94 ± 57.37 fmol/ml) and GDF15 (164.44 ± 79.31 fmol/ml). Obtained data were in good agreement with ELISA and qPCR measurements, as well as with literature data. In summary, our protocol allows the reliable quantification of biomarkers, shows a higher resolution at low biomarker concentrations than antibody-based strategies, and offers the possibility of multiplexing. Our proof-of-principle studies in patient sera encourage the future analysis of the prognostic value of DcR3 and GDF15 for colon cancer patients in larger patient cohorts.

Interaction between geriatric nutritional risk index and decoy receptor 3 predicts mortality in chronic hemodialysis patients

BACKGROUND

Protein-energy wasting (PEW) is common and associated with poor outcome in hemodialysis patients. In hemodialysis patients, geriatric nutritional risk index (GNRI) and decoy receptor 3 (DcR3) have been shown as the nutritional and inflammatory markers, respectively. The present study aimed to assess the predictive ability of GNRI and DcR3 for PEW status and long-term outcomes in chronic hemodialysis patients.

METHODS

A prospective cohort of 318 hemodialysis patients was conducted with a median follow-up of 54 months. Malnutrition-inflammation score (MIS) was used as the reference standard for the presence of PEW. Endpoints were cardiovascular and all-cause mortality.

RESULTS

Baseline GNRI had a strong negative correlation with DcR3 and MIS score. For patients with age < or ≥60, high DcR3 and low GNRI were independent predictors for the presence of PEW at baseline. At the end of the study, 81 patients died (27 cardiovascular deaths). The adjusted hazard ratios (95% confidence intervals) of low GNRI and high DcR3 were 1.93 (1.1-4.8) and 2.53 (1.2-5.5) for cardiovascular mortality and 1.85 (1.1-3.2) and 2.37 (1.5-3.7) for all-cause mortality, respectively. While integrated into a model of conventional risk factors, GNRI together with DcR3 further significantly improved the predictability for overall mortality (c statistic, 0.823).

CONCLUSIONS

Low GNRI and high DcR3 were the alternatives for identifying hemodialysis patients at risk of PEW and overall mortality. Further studies are needed to verify whether timely recognition of hemodialysis patients with a high malnutrition-inflammation risk could reduce their mortality by appropriate interventional strategies.

Systemic and local expression levels of TNF-like ligand 1A and its decoy receptor 3 are increased in primary biliary cirrhosis

BACKGROUND & AIMS

Through a genome-wide association study of a Japanese population, we recently identified TNFSF15, a gene encoding TNF-like ligand 1A (TL1A), as a susceptibility gene for primary biliary cirrhosis (PBC). We investigated the clinical significance of TL1A and one of its receptors, decoy receptor 3 (DcR3), in PBC.

METHODS

We analysed the systemic and local expression of TL1A and DcR3 in 110 PBC patients and 46 healthy controls using enzyme-linked immunosorbent assay, quantitative polymerase chain reaction and immunohistochemical staining.

RESULTS

Serum TL1A levels were significantly increased in PBC patients at both early and late stages as compared with healthy controls, and its levels were significantly decreased in early-stage PBC patients after ursodeoxycholic acid (UDCA) treatment. TL1A was immunohistochemically localized to biliary epithelial cells, Kupffer cells, blood vessels and infiltrating mononuclear cells in the PBC liver. In addition, TL1A messenger RNA expression was increased in the PBC liver as compared with the non-diseased liver. Serum DcR3 levels were also significantly increased in PBC patients, and were significantly decreased after UDCA treatment in early-stage PBC patients.

CONCLUSIONS

These results indicate that TL1A and DcR3 may play an important role in the pathogenesis of PBC.

Serum decoy receptor 3 is a useful predictor for the active status of chronic hepatitis B in hepatitis B e antigen-negative patients

Hepatitis B virus (HBV) infection is a global public health problem, because patients with chronic hepatitis B (CHB) may progress to liver cirrhosis and eventually evolve into hepatocellular carcinoma. Decoy receptor 3 (DcR3) is a soluble receptor of the tumor necrosis factor receptor superfamily, and has been implicated in anti-apoptotic and anti-inflammatory pathways. In this study, we explored the clinical value of serum DcR3 in predicting the active status of CHB in hepatitis B e antigen-negative patients (active HBeAg (-) CHB), which was determined with ELISA. The serum level of DcR3 in active HBeAg (-) CHB patients (1.92 ± 0.68 ng/ml) was higher than that in healthy controls (0.80 ± 0.25 ng/ml, p < 0.0001) and that in inactive status of HBeAg (-) CHB (inactive hepatitis B surface antigen carrier, HBsAg-IaC) patients (0.95 ± 0.26 ng/ml, p < 0.0001). DcR3 level was correlated with HBV DNA level (r = 0.819, p < 0.0001) and alanine transaminase level (ALT, r = 0.704, p < 0.0001) in active HBeAg (-) CHB patients. The area under the Receiver Operating Characteristics curve of DcR3 for detecting the active status of HBeAg (-) CHB patients was 0.914 (95% confidence interval, 0.851-0.977). The optimal cut-off value for DcR3 to predict active HBeAg (-) CHB was 1.22 ng/ml, which had a sensitivity of 87.5% and a specificity of 84.4%. These results suggest that serum DcR3 level may be useful for detecting HBeAg (-) CHB in the active stage, which requires medical treatment.

The role of TL1A and DR3 in autoimmune and inflammatory diseases

TNF-like ligand 1A (TL1A), which binds its cognate receptor DR3 and the decoy receptor DcR3, is an identified member of the TNF superfamily. TL1A exerts pleiotropic effects on cell proliferation, activation, and differentiation of immune cells, including helper T cells and regulatory T cells. TL1A and its two receptors expression is increased in both serum and inflamed tissues in autoimmune diseases such as inflammatory bowel disease (IBD), rheumatoid arthritis (RA), and ankylosing spondylitis (AS). Polymorphisms of the TNFSF15 gene that encodes TL1A are associated with the pathogenesis of irritable bowel syndrome, leprosy, and autoimmune diseases, including IBD, AS, and primary biliary cirrhosis (PBC). In mice, blocking of TL1A-DR3 interaction by either antagonistic antibodies or deletion of the DR3 gene attenuates the severity of multiple autoimmune diseases, whereas sustained TL1A expression on T cells or dendritic cells induces IL-13-dependent small intestinal inflammation. This suggests that modulation of TL1A-DR3 interaction may be a potential therapeutic target in several autoimmune diseases, including IBD, RA, AS, and PBC.

Reduction of decoy receptor 3 enhances TRAIL-mediated apoptosis in pancreatic cancer

Most human pancreatic cancer cells are resistant to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. However, the mechanisms by which pancreatic cancer cells utilize their extracellular molecules to counteract the proapoptotic signaling mediated by the TNF family are largely unknown. In this study, we demonstrate for the first time that DcR3, a secreted decoy receptor that malignant pancreatic cancer cells express at a high level, acts as an extracellular antiapoptotic molecule by binding to TRAIL and counteracting its death-promoting function. The reduction of DcR3 with siRNA unmasked TRAIL and greatly enhanced TRAIL-induced apoptosis. Gemcitabine, a first-line drug for pancreatic cancer, also reduced the level of DcR3. The addition of DcR3 siRNA further enhanced gemcitabine-induced apoptosis. Notably, our in vivo study demonstrated that the therapeutic effect of gemcitabine could be enhanced via further reduction of DcR3, suggesting that downregulation of DcR3 in tumor cells could tip the balance of pancreatic cells towards apoptosis and potentially serve as a new strategy for pancreatic cancer therapy.

DcR3 regulates the growth and metastatic potential of SW480 colon cancer cells

Decoy receptor 3 (DcR3) is considered to have anti‑apoptotic and pro-metastatic functions, suggesting it might be a therapeutic target. We examined the role and mechanisms of DcR3 on growth and the metastatic ability of SW480 colon cancer cells to provide therapeutic information for targeting DcR3 by RNA interference (RNAi) technology. Growth and the metastatic ability were inhibited, apoptosis was induced and cell cycle profile was changed after decreasing DcR3 expression, with lower levels of vascular endothelial growth factors (VEGFs) and matrix metalloproteinases (MMPs) expression. Our results implied the therapeutic potential of silencing DcR3 expression by RNAi in colon cancer.

Expression of TNFRSF6B in kidneys is a novel predictor for progression of chronic kidney disease

TNFRSF6B overexpression in tumors is a novel predictor for poor prognosis in various cancers; however, whether TNFRSF6B could be expressed in kidney tissues of patients with chronic kidney disease is unknown. Current established risk factors cannot fully predict the progression of chronic kidney disease, and, therefore, it is mandatory to develop a newer marker for predicting disease progression. We conducted a prospective cohort study comprised 167 patients with chronic kidney disease undergoing renal biopsy at a tertiary hospital with median follow-up of 30.5 months. Computer-assisted quantitative immunohistochemical staining analysis of TNFRSF6B in kidney tissues, the expression of α-smooth muscle actin and percentage of fibrosis in renal interstitium, estimated glomerular filtration rate, and urinary protein excretion rate were investigated. Study endpoint was a doubling of serum creatinine and/or end-stage renal failure requiring renal replacement therapy. We found that TNFRSF6B was predominantly expressed in the tubular epithelial cells of renal cortex. The higher the expression of TNFRSF6B, the more the expression of α-smooth muscle actin and fibrosis in interstitium (P<0.001). Forty patients reaching endpoint had lower baseline estimated glomerular filtration rate and higher expression of TNFRSF6B in renal tubular epithelial cells. Multivariate Cox regression analysis showed that high expression of TNFRSF6B independently predicted the risk toward the renal endpoint with a hazard ratio of 3.46 (95% confidence interval (CI) 1.76-6.80, P<0.001) by adjusting for clinical and pathologic variables. While added to a model of estimated glomerular filtration rate, proteinuria and other conventional risk factors, TNFRSF6B further significantly improved the model predictability for progression of chronic kidney disease (area under the curve, 0.82). In conclusion, TNFRSF6B is associated with renal fibrosis and high expression of TNFRSF6B is a novel biomarker for predicting the progression of chronic kidney disease.

The serologic decoy receptor 3 (DcR3) levels are associated with slower disease progression in HIV-1/AIDS patients

BACKGROUND/PURPOSE

The decoy receptor 3 (DcR3) is a member of the tumor necrosis factor receptor (TNFR) super-family. It counteracts the biological effects of Fas ligands and inhibits apoptosis. The goals of this study were to understand the associations between serologic DcR3 (sDcR3) levels and different human immunodeficiency virus type 1 (HIV-1) subtypes, as well as the AIDS disease progression.

METHODS

Serum samples from 61 HIV/AIDS patients, who had been followed up every 6 months for 3 years, were collected. sDcR3 levels were quantified using an enzyme immunoassay (EIA).

RESULTS

The sDcR3 levels in patients with HIV-1 subtype B were significantly higher than those in patients infected with subtype CRF01_AE (p < 0.001). In addition, multivariable linear mixed model analysis demonstrated that HIV-1 subtype B and slow disease progression were associated with higher levels of sDcR3, adjusting for potential predictors (p = 0.0008 and 0.0455, respectively).

CONCLUSION

HIV-1-infected cells may gain a survival advantage by activating DcR3, which prevents infected cell detection by the host immune system. These data indicate that the sDcR3 level is a biomarker for AIDS disease progression.

Triptolide triggers the apoptosis of pancreatic cancer cells via the downregulation of Decoy receptor 3 expression

PURPOSE

Triptolide (TPL) is a diterpenoid triepoxide that effectively induces apoptosis in a wide variety of cancer cells. However, the detailed mechanism by which TPL activates caspase cascade remains elusive. This study aimed to examine the antitumor effects of TPL against pancreatic cancer and investigate the underlying mechanism.

METHODS

Cell proliferation was evaluated by sulforhodamine B assay. The apoptosis was evaluated by caspase activity assay, Western blot and flow cytometry. DcR3 level was measured by ELISA. AsPC-1 xenografts were established to compare the in vivo antitumor effects of TPL and Gemcitabine.

RESULTS

TPL inhibited the proliferation and induced the apoptosis of pancreatic cancer cells in a dose- and time-dependent manner. TPL also inhibited DcR3 expression in a dose- and time-dependent manner. siRNA-mediated DcR3 knockdown sensitized pancreatic cancer cells to TPL-induced apoptosis. In vivo, DcR3 siRNA significantly enhanced TPL-induced apoptosis and tumor growth inhibition. Moreover, TPL showed less toxicity compared to Gemcitabine in mice model.

CONCLUSIONS

TPL induces the apoptosis of pancreatic cancer cells via the downregulation of DcR3 expression and has the potential as an effective agent against pancreatic cancer.

Specific elevation of DcR3 in sera of sepsis patients and its potential role as a clinically important biomarker of sepsis

Because of its potentially important role in the pathogenesis of sepsis, the expression of soluble decoy receptor 3 (DcR3) was investigated in sera of sepsis patients. The serum levels of DcR3 and its tumor necrosis factor-like ligand TL1A and homologous decoy receptor OPG were quantified by ELISA. The values of DcR3 to diagnose sepsis were analyzed by receiver-operating characteristic (ROC) curves. The results showed that DcR3 was significantly elevated in sepsis compared to systemic inflammatory response syndrome (SIRS), a condition similar to sepsis but resulting from noninfectious insults. DcR3 showed superior area under the ROC curve (AUC, 0.958) compared to poor AUCs of TL1A and OPG. At a cut-off of 3.24 ng/mL, DcR3 predicted sepsis from SIRS with 96% sensitivity and 82.6% specificity. DcR3 also predicted sepsis from cancer and inflammatory bowel disease with equally excellent values. Therefore, DcR3 serum level has the potential to serve as a reliable biomarker of sepsis.

Decoy receptor 3, a novel inflammatory marker, and mortality in hemodialysis patients

BACKGROUND AND OBJECTIVES

Inflammation is closely associated with cardiovascular disease, the leading cause of mortality in patients with CKD. Serum decoy receptor 3 (DcR3) is a member of the TNF receptor superfamily. CKD patients have higher levels of DcR3 than the general population, but whether DcR3 predicts mortality in CKD patients on hemodialysis has not been explored.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

DcR3 levels were measured in 316 prevalent hemodialysis patients who were followed up from November 1, 2004, to June 30, 2009, for cardiovascular and all-cause mortality.

RESULTS

The baseline DcR3 concentration showed a strong positive correlation with inflammatory markers including high-sensitivity C-reactive protein, IL-6, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1). During a follow-up period of 54 months, 90 patients died (34 cardiovascular deaths). Kaplan-Meier survival analysis showed higher cardiovascular and all-cause mortality in patients with higher DcR3 levels. The hazard ratios (95% confidence intervals) of the highest versus lowest tertiles of DcR3 were 2.8 (1.1-7.3; P for trend=0.04) for cardiovascular mortality and 2.1 (1.1-3.7; P for trend=0.02) for all-cause mortality, respectively. Based on the minimal increase in the area under the receiver operating characteristic curve from 0.79 to 0.80, the addition of DcR3 to established risk factors including VCAM-1, albumin, and IL-6 does not improve the prediction of mortality.

CONCLUSIONS

Higher DcR3 levels strongly correlate with inflammation and independently predict cardiovascular and all-cause mortality in CKD patients on hemodialysis.

Serum decoy receptor 3, a potential new biomarker for sepsis

BACKGROUND

Sepsis, a common deadly systemic infection caused by a variety of pathogens, has some clinical symptoms similar to the systemic inflammatory response syndrome (SIRS), a whole-body non-infectious inflammatory reaction to severe insults, such as burn, trauma, hypotensive shock and so on. Treatment of sepsis depends mainly on anti-microbial, while remedy for SIRS might require steroids that could possibly enhance the spread of microbes. Unfortunately, it is very difficult to distinguish these two completely different serious conditions without blood culture, which takes days to grow and identify causative pathogens. We examined a biomarker, serum decoy receptor 3 (DcR3), was evaluated for its utility in the differential diagnosis between sepsis and SIRS.

METHODS

Serum DcR3 level in 118 healthy controls, 24 sepsis patients and 43 SIRS patients, was quantitatively measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

The serum DcR3 was significantly increased in sepsis patients compared with SIRS patients and healthy controls (6.11±2.58 ng/ml vs 2.62±1.46 ng/ml, and 0.91±0.56 ng/ml, respectively, p<0.001). The areas under the receiver operating characteristic curve of DcR3 for the normal vs. SIRS, normal vs. sepsis and SIRS vs. sepsis were 0.910 (0.870-0.950), 0.992 (0.984-1.000) and 0.896 (0.820-0.973), respectively. In addition, the DcR3 exhibited a positive correlation coefficient with APACHE II score, a most commonly used index for the severity of sepsis (r=0.556, p=0.005).

CONCLUSION

The serum DcR3 has a potential to serve as a new biomarker for sepsis with its high specificity and sensitivity.

Decoy receptor 3: a pleiotropic immunomodulator and biomarker for inflammatory diseases, autoimmune diseases and cancer

Recently, several decoy molecules belonging to tumor necrosis factor receptor superfamily (TNFRSF) have been identified, including decoy receptor 1 (DcR1), decoy receptor 2 (DcR2), and decoy receptor 3 (DcR3). One of the tumor necrosis factor superfamily (TNFSF) members, TNF-related apoptosis-inducing ligand (TRAIL), binds to DcR1 and DcR2, which are membranous receptors with a truncated cytoplasmic domain, thus unable to transduce TRAIL-mediated signaling. In contrast to DcR1 and DcR2, DcR3 is a soluble receptor capable of neutralizing the biological effects of three other TNFSF members: Fas ligand (FasL/TNFSF6/CD95L), LIGHT (TNFSF14) and TNF-like molecule 1A (TL1A/TNFSF15). Since FasL is a potent apoptosis- and inflammation-inducing factor, LIGHT is involved in apoptosis and inflammation, and TL1A is a T cell costimulator and is involved in gut inflammation, DcR3 can be defined as an immunomodulator on the basis of its neutralizing effects on FasL, LIGHT, and TL1A. Initial studies demonstrated that DcR3 expression is elevated in tumors cells; however, later work showed that DcR3 expression is also upregulated in inflammatory diseases, where serum DcR3 levels correlate with disease progression. In addition to its neutralizing effect, DcR3 also acts as an effector molecule to modulate cell function via 'non-decoy' activities. This review focuses on the immunomodulatory effects of DcR3 via 'decoy' and 'non-decoy' functions, and discusses the potential of DcR3 as a biomarker to predict cancer invasion and inflammation progression. We also discuss the possible utility of recombinant DcR3 as a therapeutic agent to control autoimmune diseases, as well as the potential to attenuate tumor progression by inhibiting DcR3 expression.

Detection of two different influenza A viruses using a nitrocellulose membrane and a magnetic biosensor

Here we describe a new analytical method for the detection of two influenza A viruses by nitrocellulose membrane and magnetic sensors that employ a special frequency mixing technique. The combination of the nitrocellulose membrane and magnetic bead detection permits a rapid assay procedure and excludes two steps (the development of color and the stop reaction) required for usual immunochemical detection methods such as ELISA. Quantitative virus detection was performed using magnetic beads conjugated with secondary antibody. The results were compared with conventional assay methods and with a dot-blot assay with fluorescence compound (FITC). Under optimum conditions, our new assay procedure is capable of detecting picograms of virus per well. This new method combining the nitrocellulose membrane and magnetic bead detection reduces analytical time and allows stable and repeatable analyses of samples in point-of-care applications.

Significance of increased expression of decoy receptor 3 in chronic liver disease

BACKGROUND/AIMS

Considerable evidence has indicated that apoptosis plays an important role in hepatocyte death in chronic liver disease. However, the cellular and molecular mechanisms underlying liver regeneration in these diseases are largely unknown. Plausibly, certain molecules expressed to counteract apoptosis might provide survival advantage of certain liver cells. Therefore, we investigated a possible expression of decoy receptor 3 of the tumour necrosis factor receptor family in chronic liver diseases since decoy receptor 3 is known to inhibit apoptosis mediated by pro-apoptotic tumour necrosis factor family ligands including Fas ligand.

METHODS

A series of liver biopsies from patients with different stages of fibrosis were subjected to immunohistochemistry and in situ hybridization.

RESULTS

Both decoy receptor 3 protein and mRNA were mainly expressed in biliary epithelial cells and infiltrating lymphocytes in the diseased livers. Most noticeably, intense decoy receptor 3 expression was observed in newly developing biliary ductules in regenerative nodules as well as dysplastic nodules of cirrhotic livers. In addition, decoy receptor 3 secretion in hepatocellular carcinoma cells in culture was via the activation of mitogen-activated protein kinases.

CONCLUSION

Decoy receptor 3 was specifically expressed in chronic liver diseases and hepatocellular carcinoma cells, and decoy receptor 3 might facilitate the survival of liver cells by exerting its anti-apoptotic activity during the progression of liver cirrhosis and hepatocarcinogenesis.

Decoy receptor 3 levels in peripheral blood predict outcomes of acute respiratory distress syndrome

RATIONALE

Acute respiratory distress syndrome (ARDS), a serious inflammatory reaction to acute lung injury, is associated with high mortality rates. Decoy receptor (DcR) 3 is a soluble protein with immunomodulatory effects. Biomarkers that reliably predict outcomes in ARDS are not currently available.

OBJECTIVES

Comparing DcR3 with the Acute Physiology and Chronic Health Evaluation (APACHE) II scores and three other plasma markers to explore the association of DcR3 and the clinical outcome in ARDS.

METHODS

Eighty-eight patients with ARDS were studied. Baseline APACHE II scores and clinical data were recorded. Plasma levels of DcR3, soluble triggering receptor expressed on myeloid cells (sTREM)-1, tumor necrosis factor (TNF)-alpha, and IL-6 were measured on Day 1 and later time points, and correlated with the survival status on Day 28 after the onset of ARDS. For validation, 59 patients with ARDS from another medical center were studied.

MEASUREMENTS AND MAIN RESULTS

Among the biomarkers evaluated, only DcR3 discriminated the survivors and nonsurvivors at all time points in the first week of ARDS. DcR3 independently associated with and best predicted the 28-day mortality of patients with ARDS. Plasma DcR3 levels most correlated to multiple-organ dysfunction and ventilator dependence. Compared with survivors, the nonsurvivors had higher DcR3 levels regardless of the APACHE II scores. Kaplan-Meier survival analysis showed higher mortality in patients with ARDS with higher DcR3 levels. The outcome prediction of patients with ARDS by plasma DcR3 levels was recapitulated by the validation cohort.

CONCLUSIONS

High plasma DcR3 levels correlate with development of multiple-organ dysfunction and independently predict the 28-day mortality in patients with ARDS.

Targeting lymphocyte activation through the lymphotoxin and LIGHT pathways

SUMMARY

Cytokines mediate key communication pathways essential for regulation of immune responses. Full activation of antigen-responding lymphocytes requires cooperating signals from the tumor necrosis factor (TNF)-related cytokines and their specific receptors. LIGHT, a lymphotoxin-beta (LTbeta)-related TNF family member, modulates T-cell activation through two receptors, the herpesvirus entry mediator (HVEM) and indirectly through the LT-beta receptor. An unexpected finding revealed a non-canonical binding site on HVEM for the immunoglobulin superfamily member, B and T lymphocyte attenuator (BTLA), and an inhibitory signaling protein suppressing T-cell activation. Thus, HVEM can act as a molecular switch between proinflammatory and inhibitory signaling. The non-canonical HVEM-BTLA pathway also acts to counter LTbetaR signaling that promotes the proliferation of antigen-presenting dendritic cells (DCs) within lymphoid tissue microenvironments. These results indicate LTbeta receptor and HVEM-BTLA pathways form an integrated signaling circuit. Targeting these cytokine pathways with specific antagonists (antibody or decoy receptor) can alter lymphocyte differentiation and activation. Alternately, agonists directed at their cell surface receptors can restore homeostasis and potentially reset immune and inflammatory processes, which may be useful in treating autoimmune and infectious diseases and cancer.

Decoy receptor 3, upregulated by Epstein-Barr virus latent membrane protein 1, enhances nasopharyngeal carcinoma cell migration and invasion

Decoy receptor 3 (DcR3), a member of tumor necrosis factor receptor superfamily, has been implicated in tumorigenesis through its abilities to modulate immune responses and induce angiogenesis. Epstein-Barr virus (EBV), a ubiquitous gamma-herpesvirus, is associated with malignancies including nasopharyngeal carcinoma (NPC). Previous studies show that DcR3 is overexpressed in EBV-positive lymphomas and Rta, an EBV transcription activator, can upregulate DcR3 in Burkitt lymphoma cell lines. However, DcR3 expression has not been demonstrated in EBV-associated NPC nor have there been any EBV latent genes linked to DcR3 upregulation. Here, we showed DcR3 was overexpressed in NPC. Higher DcR3 expression score and DcR3-positive rate were found in metastatic NPC than in primary NPC tissues, suggesting DcR3 may enhance cell metastatic potential. This hypothesis is supported by our observation that NPC HONE-1 cells overexpressing DcR3 exhibited significant higher migration and invasion abilities in vitro. We found besides Rta, EBV latent membrane protein (LMP) 1 can upregulate DcR3 via nuclear factor-kappaB and phosphatidylinositol 3-kinase-signaling events. Approximate 75% of LMP1-positive NPC tissues overexpressed DcR3, suggesting LMP1 may enhance DcR3 expression in vivo. Data herein suggested that increasing DcR3 expression by LMP1 not only helps EBV-associated cancer cells gain survival advantage by preventing host immune detection but also increases the chance of cancer metastasis by enhancing cell migration and invasion. All these DcR3-mediated events facilitate normal cells to gain cancer hallmarks.

Decoy receptor 3 is a prognostic factor in renal cell cancer

BACKGROUND

Decoy receptor 3 (DcR3) is a soluble protein that binds to and inactivates the death ligand CD95L. Here, we studied a possible association between DcR3 expression and prognosis in patients with renal cell carcinomas (RCCs).

METHODS

A tissue microarray containing RCC tumor tissue samples and corresponding normal tissue samples was generated. Decoy receptor 3 expression in tumors of 560 patients was examined by immunohistochemistry. The effect of DcR3 expression on disease-specific survival and progression-free survival was assessed using univariate analysis and multivariate Cox regression analysis. Decoy receptor 3 serum levels were determined by ELISA.

FINDINGS

High DcR3 expression was associated with high-grade (P = .005) and high-stage (P = .048) RCCs. The incidence of distant metastasis (P = .03) and lymph node metastasis (P = .002) was significantly higher in the group with high DcR3 expression. Decoy receptor 3 expression correlated negatively with disease-specific survival (P < .001) and progression-free survival (P < .001) in univariate analyses. A multivariate Cox regression analysis retained DcR3 expression as an independent prognostic factor that outperformed the Karnofsky performance status. In patients with high-stage RCCs expressing DcR3, the 2-year survival probability was 25%, whereas in patients with DcR3-negative tumors, the survival probability was 65% (P < .001). Moreover, DcR3 serum levels were significantly higher in patients with high-stage localized disease (P = .007) and metastatic disease (P = .001).

INTERPRETATION

DcR3 expression is an independent prognostic factor of RCC progression and mortality. Therefore, the assessment of DcR3 expression levels offers valuable prognostic information that could be used to select patients for adjuvant therapy studies.

Ascites from epithelial ovarian cancer contain high levels of functional decoy receptor 3 (DcR3) and is associated with platinum resistance

OBJECTIVE

Decoy receptor 3 (DcR3), a soluble tumor necrosis factor receptor is a known binding partner of multiple apoptotic ligands inhibiting apoptosis. The expression of DcR3 by cancers has been reported in gastrointestinal cancers yet it has not been described in ovarian cancer. Abnormalities in apoptosis pathways are seen in ovarian cancer and we theorized that the presence of DcR3 is a component of the dysregulation.

METHODS

Ascites samples from 44 women with advanced ovarian cancer were tested for DcR3 by ELISA. The ability of ascites to inhibit Fas-ligand mediated apoptosis was determined by chromium release assays using cell surface or soluble Fas-ligand. Clinical parameters including, response to platinum and progression free and overall survival were compared between patients with high or low levels of DcR3.

RESULTS

DcR3 was found in all 44 cases by ELISA. Ascites fluid significantly inhibited Fas-ligand mediate apoptosis using both surface Fas-ligand (KFL-9 cells) and soluble Fas-ligand. Blocking DcR3 with antibodies restores the cytolytic effects in both assays. HIGH DcR3 level was associated with stage IV disease and more than double the incidence of platinum resistant disease. In this modest sample size Low DcR3 cases had longer PFI and overall survival however neither difference was statistically significant.

CONCLUSIONS

DcR3 is expressed by epithelial ovarian cancers, concentrated in ascites and inhibits Fas-ligand mediated apoptosis. Together with a trend toward poor patient outcome these results indicate that expression of DcR3 by ovarian cancers is worthy of further investigation in a larger population to allow multivariate analysis.

Molecular cloning and preliminary expression analysis of banded dogfish (Triakis scyllia) TNF decoy receptor 3 (TNFRSF6B)

Decoy receptor 3 (DcR3), a member of TNF receptor superfamily, is a soluble receptor without death domain and cytoplasmic domain, and secreted by cells and binds with FasL, LIGHT and TL1A. The principal function of DcR3 is the inhibition of apoptosis by the binding cytotoxic ligands. Expression of DcR3 has been reported in a wide array of normal human tissues as well as tumors and tumor cell lines. Recently, DcR3 was reported to modulate a variety of immune responses in mammals. TNFR or DcR3 has been identified in some teleost fishes. However, DcR3 is not reported in cartilaginous fish which is the lowest vertebrate possessing the adaptive immune system. Here we identified DcR3 cDNA in shark (Trsc-DcR3) from an SSH library prepared from peripheral white blood cells stimulated with PMA. Four cysteine-rich domains (CRDs) in common with TNF receptor family members are present in the Trsc-DcR3 sequence. The deduced amino acid sequence of Trsc-DcR3 showed highest identity with the chicken (50.4%), followed by human (46.8%) and rainbow trout (36.5%) DcR3. In a phylogenetic tree of known TNFRSF sequences, the Trsc-DcR3 grouped with the chicken and human DcR3. Trsc-DcR3 mRNA was detected strongly in the gill, moderately in the brain, and weakly in the kidney, thymus and leydig. These data strongly suggest that the gene encoding Trsc-DcR3 in banded dogfish is a homolog of the human gene. mRNA expression of Trsc-DcR3 in the thymus and leydig suggests that DcR3 may act as a modulator in the immune system even at the phylogenetic level of cartilaginous fish.

Purification and crystallization of recombinant human TNF-like ligand TL1A

TL1A is a recently discovered TNF-like ligand. Because of the interests in the structural basis of the specificity of the bindings of the TNF ligands to the TNF receptors, we sought to crystallize the mature soluble form of human TL1A. To prepare recombinant human TL1A, the coding sequence for mature human soluble TL1A (aa72-aa251) was cloned into Escherichia coli expression vector pDEST14 and the protein was purified in a succession of immobilized metal affinity, hydrophobic interaction, ion exchange and size exclusion chromatography, indicating that mature TL1A may have a metal ligand. The functional activity of recombinant TL1A was confirmed by its ability to bind to DcR3, a soluble decoy receptor of the TNF receptor family that has been previously reported to bind to TL1A. Single crystals of TL1A were obtained in a screen with a crystal screen kit using the hanging-drop vapor diffusion method. Diffraction quality crystals were grown after optimization. TL1A crystals belong to the tetragonal space group P4(1)2(1)2, with unit cell parameter of a=b=116.734, c=118.927A. The TL1A crystals diffracted to at least 3.2A. Self-rotation functions showed that there are three molecules in the asymmetry unit. Assuming an average partial specific volume of 0.74cm(3)g(-1) for proteins, the water content of the crystal is 62.8%. A preliminary molecular replacement solution was obtained with three TL1A molecules in the asymmetric unit. The three protomers are related by a non-crystallographic 3-fold axis, like those of other TNF ligand family members.

Decoy receptor 3 expressed in rheumatoid synovial fibroblasts protects the cells against Fas-induced apoptosis

OBJECTIVE

Decoy receptor 3 (DcR3), a newly identified member of the tumor necrosis factor receptor (TNFR) superfamily, is a soluble receptor that binds to members of the TNF family, including FasL, LIGHT, and TNF-like molecule 1A. DcR3 is mostly expressed in tumor cells, and it competitively inhibits binding of TNF to TNFRs. The present study was undertaken to investigate DcR3 expression in fibroblast-like synoviocytes (FLS) from patients with rheumatoid arthritis (RA) and osteoarthritis (OA), and to analyze the effects of DcR3 on Fas-induced apoptosis in RA FLS.

METHODS

Expression of DcR3 in FLS was measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. FLS were incubated with DcR3-Fc chimera protein or transfected with DcR3 small interfering RNA (siRNA) using the lipofection method, before induction of apoptosis. Apoptosis induced by Fas in FLS was detected with TUNEL staining and Western blotting of caspase 8 and poly(ADP-ribose) polymerase. Finally, FLS were incubated with TNFalpha prior to Fas-induced apoptosis, expression of DcR3 was analyzed by quantitative RT-PCR, and apoptosis was measured.

RESULTS

DcR3 was expressed in both RA FLS and OA FLS. DcR3-Fc protein inhibited Fas-induced apoptosis in FLS. Down-regulation of DcR3 in FLS by siRNA increased Fas-induced apoptosis. TNFalpha increased DcR3 expression and inhibited Fas-induced apoptosis in RA FLS, but not in OA FLS.

CONCLUSION

DcR3 expressed in RA FLS is increased by TNFalpha and protects the cells against Fas-induced apoptosis. These findings indicate that DcR3 may be a possible therapeutic target in RA.

Evaluation of the novel serum markers B7-H4, Spondin 2, and DcR3 for diagnosis and early detection of ovarian cancer

OBJECTIVE

Early detection through regular screening could significantly reduce mortality from ovarian cancer. Advances in biomarkers and imaging continue to improve the sensitivity and specificity of cancer detection, but further improvements are still needed. In this study, we identified and evaluated three new serum biomarkers that may be used to improve detection of ovarian cancer.

METHODS

Through genomic analysis, we identified B7-H4, Spondin 2, and DcR3 as over-expressed genes in ovarian cancer tissues. Sensitive sandwich ELISAs were developed to analyze the level of these novel markers in 68 serum samples from patients with ovarian cancer (16 early stage, 52 late stage) and 108 control samples, and 20 healthy women from which two serum samples were collected 1 year apart. CA125 levels were measured in all samples.

RESULTS

Markers were evaluated for their ability to identify clinical disease. The three novel markers and CA125 were elevated in serum of ovarian cancer patients as compared to normal controls. B7-H4 showed the highest specificity, with the lowest frequency of elevation in all control groups. When all cases were compared against all controls, CA125, Spondin 2, B7-H4, and DcR3 showed areas under the ROC curve of 0.87, 0.78, 0.74, and 0.71, respectively. CA125 and B7-H4 showed the best diagnostic performance for early-stage, with AUCs of 0.90 and 0.80, respectively.

CONCLUSION

This study demonstrates that B7-H4, Spondin 2, and DcR3 are promising new ovarian cancer markers that may improve early detection of cancer when used in combination with traditional diagnostic tests.

Vascular endothelial growth inhibitor (VEGI), an endogenous negative regulator of angiogenesis

Vascular endothelial growth inhibitor (VEGI; TNFSF-15) is a new member of the tumor necrosis factor family. VEGI is predominantly an endothelial cell-specific gene, and recombinant VEGI is a potent inhibitor of endothelial cell proliferation, angiogenesis and tumor growth. VEGI exerts two activities on endothelial cells: early G1 arrest of G0/G1-cells responding to growth stimuli, and programmed death of proliferating cells. These activities are highly specific to endothelial cells. There are three VEGI isoforms identified thus far. One of the isoforms, VEGI-251, is a secreted protein. The gene products apparently play a role in normal vasculature, as the transcripts are found in normal adult tissues and some fetal tissues. VEGI gene expression is subject to regulation by inflammatory cytokines. VEGI is also able to regulate the expression of several important genes involved in angiogenesis. These findings are consistent with the view that VEGI functions as an autocrine cytokine to inhibit angiogenesis and stabilize the vasculature.

Overexpression of decoy receptor 3 in hepatocellular carcinoma and its association with resistance to Fas ligand-mediated apoptosis

AIM

To characterize the expression and genomic amplification of decoy receptor 3 (DcR3) in hepatocellular carcinoma (HCC) and to evaluate the role of DcR3 in apoptosis.

METHODS

We examined 48 cases of HCC for DcR3 expression by RT-PCR and DcR3 gene amplification by quantitative genomic PCR. DcR3 protein was detected by immunohistochemistry. Terminal deoxynucleotidyl transferase-mediated dUTP digoxigenin nick and labeling (TUNEL) was used to identify the apoptosis cells in tissues. Primary hepatoma cell culture and MTT test were used to evaluate the protection against FasL- and chemical-induced apoptosis by DcR3 expression.

RESULTS

DcR3 mRNA overexpression was detected in 60% HCC (29/48) patients. The occurrence of HCC was not associated with amplification of the gene. One sample base substitution was found in three sites as sequence in Genbank. The expression of DcR3 in HCC was the associatied with the apoptotic index (0.067+/-0.04 vs 0.209+/-0.12, P<0.01), size of mass, stage and infiltration or metastasis (41.2% vs 71.0%, 40% vs 75%, 51.8% vs 84.6%, P<0.05). DcR3 expression could be protect hepatoma cells against apoptosis induced by FasL, but not by chemicals.

CONCLUSION

These data suggest that in addition to gene amplification there may be another mechanism underlying DcR3 overexpression. The effect of overexpression of DcR3 on the apoptosis of cancer cells may have direct therapeutic implications for the management of HCC.

Identification of naturally secreted soluble form of TL1A, a TNF-like cytokine

TL1A, a TNF-like ligand, mediates signaling via its cognate receptor DR3, a death receptor whose activation was known to induce both death and survival factors. TL1A, like TNF, is also presumed to circulate as a homotrimeric soluble form. To identify soluble TL1A in the immune system, we have developed a quantitative ELISA by pairing a monoclonal antibody (MAb) with a biotinylated anti-TL1A polyclonal antibody (PAb) as capture and detection antibodies, respectively. The assay had a detection limit of 32 pg/ml. Overnight culture of human umbilical vein endothelial cells (HUVEC) expressed up to 160 pg/ml of TL1A, and that proinflammatory cytokines, IL-1 and TNF, significantly increased TL1A mRNA and soluble protein up to several folds in contrast to IL-6 and IL-11, which induced neither protein nor mRNA in the cells. IL-1 appeared to be a better stimulator of TL1A than TNF-alpha, and the induction of soluble TL1A in HUVEC in response to IL-1 was dose and time-dependent. We have also purified soluble TL1A from a large volume of IL-1 stimulated HUVEC conditioned medium using an anti-TL1A PAb-coupled affinity column. The protein eluted from the column was further reacted with anti-TL1A MAbs in Western blot: 30-kDa and 32-kDa under non-reducing and reducing conditions, respectively. Taken together, our results indicated that ELISA might be useful in studying soluble TL1A regulation in certain inflammatory conditions.