Tumor-necrosis-factor-related apoptosis-inducing ligand and the regulation of hematopoiesis

Hypoplastic Myelodysplastic Syndromes: Just an Overlap Syndrome?

Simple Summary

Hypoplastic myelodysplastic syndromes (hMDS) represent a diagnostic conundrum. They share morphologic and clinical features of both MDS (dysplasia, genetic lesions and cytopenias) and aplastic anemia (AA; i.e., hypocellularity and autoimmunity) and are not comprised in the last WHO classification. In this review we recapitulate the main clinical, pathogenic and therapeutic aspects of hypo-MDS and discuss why they deserve to be distinguished from normo/hypercellular MDS and AA. We conclude that hMDS may present in two phenotypes: one more proinflammatory and autoimmune, more similar to AA, responding to immunosuppression; and one MDS-like dominated by genetic lesions, suppression of immune surveillance, and tumor escape, more prone to leukemic evolution.

Abstract

Myelodysplasias with hypocellular bone marrow (hMDS) represent about 10–15% of MDS and are defined by reduced bone marrow cellularity (i.e., <25% or an inappropriately reduced cellularity for their age in young patients). Their diagnosis is still an object of debate and has not been clearly established in the recent WHO classification. Clinical and morphological overlaps with both normo/hypercellular MDS and aplastic anemia include cytopenias, the presence of marrow hypocellularity and dysplasia, and cytogenetic and molecular alterations. Activation of the immune system against the hematopoietic precursors, typical of aplastic anemia, is reckoned even in hMDS and may account for the response to immunosuppressive treatment. Finally, the hMDS outcome seems more favorable than that of normo/hypercellular MDS patients. In this review, we analyze the available literature on hMDS, focusing on clinical, immunological, and molecular features. We show that hMDS pathogenesis and clinical presentation are peculiar, albeit in-between aplastic anemia (AA) and normo/hypercellular MDS. Two different hMDS phenotypes may be encountered: one featured by inflammation and immune activation, with increased cytotoxic T cells, increased T and B regulatory cells, and better response to immunosuppression; and the other, resembling MDS, where T and B regulatory/suppressor cells prevail, leading to genetic clonal selection and an increased risk of leukemic evolution. The identification of the prevailing hMDS phenotype might assist treatment choice, inform prognosis, and suggest personalized monitoring.

Immunomodulatory activities of polysaccharides from Ganoderma on immune effector cells

Polysaccharides are the most abundant bioactive compounds in Ganoderma and have been widely used as dietary supplements in traditional Chinese medicine for thousands of years. Polysaccharides from Ganoderma exhibit unique biological properties, including anti-tumor, anti-inflammatory, and immunomodulatory activities. Herein, the sources and structures of polysaccharides from Ganoderma were presented. This work also reviews the immunomodulatory activities and possible mechanisms of polysaccharides from Ganoderma on different immune effector cells, including lymphocytes and myeloid cells. As an available adjunctive remedy, polysaccharides from Ganoderma can potentially be applied for the modulation of the host immune system, namely the innate immunity, the cellular immunity, and the humoral immunity.

Therapeutic Effects of Synthetic Antimicrobial Peptides, TRAIL and NRP1 Blocking Peptides in Psoriatic Keratinocytes

Psoriasis is a chronic, recurrent, heterogeneous, cutaneous inflammatory skin disease for which there is no cure. It affects approximately 7.5 million people in the United States. Currently, several biologic agents that target different molecules implicated in the pathogenic processes of psoriasis are being assessed in diverse clinical studies. However, relapse usually occurs within weeks or months, meaning there is currently no cure for psoriasis. Therefore, recent studies have discovered diverse new potential treatments for psoriasis: inhibitors of bacteria such as Staphylococcus aureus, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and neuropilin 1 (NRP1). A promising approach that has recently been described involves modifying antimicrobial peptides to develop new cutaneous anti-bacterial agents that target inflammatory skin disease induced by Staphylococcus. Increased expression of TRAIL and its death receptors DR4 and DR5 has been implicated in the pathogenesis of plaque psoriasis. In addition, TRAIL has the ability to inhibit angiogenesis by inducing endothelial cell death and by negative regulation of VEGF-induced angiogenesis via caspase-8-mediated enzymatic and non-enzymatic functions. Since NRP1 regulates angiogenesis induced by multiple signals, including VEGF, ECM and semaphorins, and also initiates proliferation of keratinocytes through NF-κB signaling pathway in involved psoriatic skin, targeting NRP1 pathways may offer numerous windows for intervention in psoriasis. In this review, we will focus on the current knowledge about the emerging role of synthetic antimicrobial peptides, TRAIL and NRP1 blocking peptides in the pathogenesis and treatment of psoriasis.

MiR-942 decreased before 20 weeks gestation in women with preeclampsia and was associated with the pathophysiology of preeclampsia in vitro

OBJECTIVE

To investigate the possible relationship between miR-942 levels and the pathogenesis of preeclampsia using in vitro assays and to investigate circulating miR-942 levels in the early phase of mid-of pregnancy in women who later developed preeclampsia and in women with uncomplicated pregnancies.

METHODS

Plasma samples were collected from pregnant women between 12 and 20 weeks of gestation. MiR-942 levels were determined by stem-loop real-time PCR for 26 cases who subsequently developed preeclampsia as well as for 52 controls. Bioinformatics software was used to predict the target genes of miR-942, and a dual-luciferase reporter system was utilized to validate target gene regulation. Finally, MTT proliferation assays, transwell invasion assays, and endothelial cell tube formation assays were performed to further explore the function of miR-942 using a human extravillous trophoblast cell line (TEV-1).

RESULT

Circulating miR-942 levels were significantly lower in mid-pregnancy (12-20 weeks gestation) in women who later developed preeclampsia compared with those with an uncomplicated pregnancy (p < 0.05). Endoglin (ENG) is an miR-942 target gene. MiR-942 had a sensitivity of 0.673, a specificity of 0.875, and an area under the receiver operating characteristic curve (AUC) of 0.718 [95% CI, 0.594-0.822] for the possible screening of preeclampsia. In vitro, decreased miR-942 expression decreased the invasive ability of TEV-1 cells, and inhibited the HUVEC angiogenesis assay, both effects that are similar to what is observed in preeclampsia (both p <0.05).

CONCLUSION

MiR-942 may be involved in the pathogenesis of preeclampsia via the regulation of its target gene ENG. Multicenter studies must be performed and a greater number of samples must be analyzed to ascertain whether circulating miR-942 levels can serve as a novel early diagnostic marker for preeclampsia.

Circulating levels of TNF-related apoptosis inducing-ligand are decreased in patients with large adult-type granulosa cell tumors-implications for therapeutic potential

Targeted treatments are needed for advanced adult-type granulosa cell tumors (AGCTs). We set out to assess tumor tissue and circulating levels of TNF-related apoptosis-inducing ligand (TRAIL), a promising anti-cancer cytokine, in patients affected by AGCT. We analyzed tissue expression of TRAIL in 127 AGCTs using immunohistochemistry or RT-PCR. Soluble TRAIL was measured by means of ELISA from 141 AGCT patient serum samples, as well as the conditioned media of 15 AGCT patient-derived primary cell cultures, and the KGN cell line. Tissue and serum TRAIL levels were analyzed in relationship with clinical parameters, and serum estradiol, FSH, and LH levels. We found that AGCT samples expressed TRAIL mRNA and protein at levels comparable to normal granulosa cells. AGCT cells did not release soluble TRAIL. TRAIL protein levels were decreased in tumors over 10 cm in diameter (p = 0.04). Consistently, circulating TRAIL levels correlated negatively to tumor dimension (p = 0.01). Circulating TRAIL levels negatively associated with serum estradiol levels. In multiple regression analysis, tumor size was an independent factor contributing to the decreased levels of soluble TRAIL in AGCT patients. AGCTs associate with significantly decreased tumor tissue and serum TRAIL levels in patients with a large tumor mass. These findings encourage further study of agonistic TRAIL treatments in patients with advanced or recurrent AGCT.

Clinical perspectives of TRAIL: insights into central nervous system disorders

The TNF-related apoptosis inducing ligand TRAIL is a member of the TNF superfamily that has been firstly studied and evaluated for its anti-cancer activity, and the insights into its biology have already led to the identification of several TRAIL-based anticancer strategies with strong clinical therapeutic potentials. Nonetheless, the TRAIL system is far more complex and it can lead to a wider range of biological effects other than the ability of inducing apoptosis in cancer cells. By virtue of the different receptors and the different signalling pathways involved, TRAIL plays indeed a role in the regulation of different processes of the innate and adaptive immune system and this feature makes it an intriguing molecule under consideration in the development/progression/treatment of several immunological disorders. In this context, central nervous system represents a peculiar anatomic site where, despite its "status" of immune-privileged site, both innate and adaptive inflammatory responses occur and are involved in several pathological conditions. A number of studies have evaluated the role of TRAIL and of TRAIL-related pathways as pro-inflammatory or protective stimuli, depending on the specific pathological condition, confirming a twofold nature of this molecule. In this light, the aim of this review is to summarize the main preclinical evidences of the potential/involvement of TRAIL molecule and TRAIL pathways for the treatment of central nervous system disorders and the key suggestions coming from their assessment in preclinical models as proof of concept for future clinical studies.

The anti-leukemic activity of sodium dichloroacetate in p53mutated/null cells is mediated by a p53-independent ILF3/p21 pathway

B-chronic lymphocytic leukemia (B-CLL) patients harboring p53 mutations are invariably refractory to therapies based on purine analogues and have limited treatment options and poor survival. Having recently demonstrated that the mitochondria-targeting small molecule sodium dichloroacetate (DCA) exhibits anti-leukemic activity in p53^wild-type B-CLL cells, the aim of this study was to evaluate the effect of DCA in p53^mutated B-CLL cells and in p53^mutated/null leukemic cell lines. DCA exhibited comparable cytotoxicity in p53^wild-type and p53^mutated B-CLL patient cell cultures, as well as in p53^mutated B leukemic cell lines (MAVER, MEC-1, MEC-2). At the molecular level, DCA promoted the transcriptional induction of p21 in all leukemic cell types investigated, including p53^null HL-60. By using a proteomic approach, we demonstrated that DCA up-regulated the ILF3 transcription factor, which is a known regulator of p21 expression. The role of the ILF3/p21 axis in mediating the DCA anti-leukemic activity was underscored by knocking-down experiments. Indeed, transfection with ILF3 and p21 siRNAs significantly decreased both the DCA-induced p21 expression and the DCA-mediated cytotoxicity. Taken together, our results emphasize that DCA is a small molecule that merits further evaluation as a therapeutic agent also for p53^mutated leukemic cells, by acting through the induction of a p53-independent pathway.

The p53 transcriptional pathway is preserved in ATMmutated and NOTCH1mutated chronic lymphocytic leukemias

By using next generation sequencing, we have analyzed 108 B chronic lymphocytic leukemia (B-CLL) patients. Among genes involved in the TP53 pathway, we found frequent mutations in ATM (n=18), TP53 (n=10) and NOTCH1 (n=10) genes, rare mutations of NOTCH2 (n=2) and CDKN1A/p21 (n=1) and no mutations in BAX, MDM2, TNFRSF10A and TNFRSF10B genes. The in vitro treatment of primary B-CLL cells with the activator of p53 Nutlin-3 induced the transcription of p53 target genes, without significant differences between the B-CLL without mutations and those harboring either ATM or NOTCH1 mutations. On the other hand, the subgroup of TP53^mutated B-CLL exhibited a significantly lower induction of the p53 target genes in response to Nutlin-3 as compared to the other B-CLL samples. However, among the TP53^mutated B-CLL, those showing mutations in the high hot spot region of the DNA binding domain [273-280 aa] maintained a significantly higher p53-dependent transcriptional activity as compared to the other TP53^mutated B-CLL samples. Since the ability to elicit a p53-dependent transcriptional activity in vitro has a positive prognostic significance, our data suggest that ATM^mutated, NOTCH1^mutated and surprisingly, also a subset of TP53^mutated B-CLL patients might benefit from therapeutic combinations including small molecule activator of the p53 pathway.

Kinetic Profiles of Inflammatory Mediators in the Conjunctival Sac Fluid of Patients upon Photorefractive Keratectomy

Photorefractive keratectomy (PRK) represents a therapeutic option to remodel corneal stroma and to compensate refractive errors, which involves inflammatory and/or regenerative processes. In this context, the modulation of cytokines/chemokines in the conjunctival sac fluid and their role in the maintenance of the corneal microenvironment during the healing process upon refractive procedures has not been deeply investigated. In this study, serial samples of conjunctival sac fluid of patients (n = 25) undergoing PRK were harvested before and at different time points after surgery. The levels of 29 cytokines/chemokines/growth factors involved in inflammatory/immune processes were measured with a multiplex array system. The results have firstly highlighted the different pattern of cytokine expression between the microenvironment at the anterior surface of the eye and the systemic circulation. More importantly, the kinetic of modulation of cytokines/chemokines at the conjunctival level following PRK revealed that while the majority of cytokines/chemokines showed a significant decrease, MCP-1 emerged in light of its pronounced and significant increase soon after PRK and during the follow-up. This methodological approach has highlighted the role of MCP-1 in the healing process following PRK and has shown a potential for the identification of expression/modulation of soluble factors for biomarker profiling in ocular surface diseases.

Surviving apoptosis: life-death signaling in single cells

Tissue development and homeostasis are regulated by opposing pro-survival and pro-death signals. An interesting feature of the Tumor Necrosis Factor (TNF) family of ligands is that they simultaneously activate opposing signals within a single cell via the same ligand-receptor complex. The magnitude of pro-death events such as caspase activation and pro-survival events such as Nuclear Factor (NF)-κB activation vary not only from one cell type to the next but also among individual cells of the same type due to intrinsic and extrinsic noise. The molecules involved in these pro-survival and/or pro-death pathways, and the different phenotypes that result from their activities, have been recently reviewed. Here we focus on the impact of cell-to-cell variability in the strength of these opposing signals on shaping cell fate decisions.

Sodium dichloroacetate exhibits anti-leukemic activity in B-chronic lymphocytic leukemia (B-CLL) and synergizes with the p53 activator Nutlin-3

The anti-leukemic activity of the mitochondria-targeting small molecule sodium dichloroacetate (DCA), used alone and in association with the small molecule inhibitor of the p53/MDM2 interaction Nutlin-3, was analyzed in primary B-chronic lymphocytic leukemia (B-CLL) samples (n=22), normal peripheral blood cells (n=10) and in p53wild-type EHEB, JVM-2, JVM-3 B lymphoblastoid cell lines. DCA exhibited a dose-dependent anti-leukemic activity in both primary B-CLL and B leukemic cell lines with a functional p53 status and showed a synergistic cytotoxic activity when used in combination with Nutlin-3. At the molecular level, DCA positively regulated p53 activity, as documented by post-transcriptional modifications of p53 protein and synergized with Nutlin-3 in increasing the expression of the p53-target genes MDM2, PUMA, TIGAR and in particular p21. The potential role of p21 in mediating the DCA+Nutlin-3 anti-leukemic activity was underscored in knocking-down experiments. Indeed, transfection of leukemic cells with p21 siRNAs significantly decreased the DCA+Nutlin-3-induced cytotoxicity. Taken together, our data emphasize that DCA is a molecule that merits to be further evaluated as a chemotherapeutic agent for B-CLL, likely in combination with other therapeutic compounds.

Potential role of circulating microRNAs as early markers of preeclampsia

OBJECTIVE

To identify microRNAs (miRNAs) differentially expressed at early stages of gestation (12-14 weeks) in the serum of pregnant women, who later developed severe preeclampsia (sPE) in the third trimester of pregnancy (n = 24) compared to women with normal pregnancy (n = 24).

MATERIALS AND METHODS

Sera from 12-14-week-gestation whole blood were subjected to microarray analysis with TaqMan Low Density Array chips (human microRNA panel V3.0), and to quantitative real-time polymerase chain reaction.

RESULTS

By using the TaqMan Low Density Array chip technology, 19 mature miRNAs appeared differentially expressed in the group of women who later developed sPE as compared to normal women. The expression of four miRNAs (miR-1233, miR-520, miR-210, miR-144) was validated by quantitative real-time polymerase chain reaction analysis. MiR-1233 was the most overexpressed in the serum of women who later developed sPE.

CONCLUSION

Circulating miRNAs deserve further investigation in order to explore their potential role in the pathogenesis of preeclampsia. In particular, miR-1233 might represent a potential marker of early sPE.

TNF-α -308 G>A polymorphism and risk of bone marrow failure syndrome: A meta-analysis

The influence of the TNF-α -308 G>A polymorphism on bone marrow failure syndrome susceptibility is unclear. We have conducted a meta-analysis of all relevant published studies. We searched PubMed, Chinese Biomedical Literature and China National Knowledge Infrastructure databases up to February 2015. Odds ratios (ORs) with 95% confidence intervals (CIs) were applied to assess the strength of associations. Eleven case-control studies with a total sample size of 909 cases and 1803 controls were eligible to assess the association between the TNF-α -308 G>A polymorphism and susceptibility to bone marrow failure syndrome. Overall, the TNF-α -308 G>A polymorphism was significantly associated with an increased risk of bone marrow failure syndrome in any genetic model. In stratified analysis by disease type, there was a significant association between the TNF-α -308 G>A polymorphism and increased risk of aplastic anemia but no significant association with myelodysplastic syndrome (AA vs. GG: OR=2.23, 95% CI=1.23-4.05, P=0.006; recessive model: OR=3.52, 95% CI=1.30-9.53, P=0.010). In subgroup analysis by ethnicity, there were significant associations between the TNF-α -308 G>A polymorphism and increased risk of bone marrow failure syndrome for Caucasians in two models, but not in Asian populations (AA vs. GG: OR=2.66, 95% CI=1.36-5.21, P=0.003; recessive model: OR=2.68, 95% CI=1.37-5.24, P=0.002). In conclusion, our meta-analysis suggests that the TNF-α -308 G>A polymorphism may contribute to the risk of bone marrow failure syndrome, particularly among Caucasian and aplastic anemia patients. Further investigations are needed to clarify the role of the TNF-α -308 G>A polymorphism in bone marrow failure syndrome.

TNF-related apoptosis inducing ligand in ocular cancers and ocular diabetic complications

TNF-related apoptosis inducing ligand (TRAIL) is an intensively studied cytokine, in particular for its anticancer activity. The discovery that conjunctival sac fluid contains extremely high levels of soluble TRAIL as compared to other body fluids suggested important implications in the context of the immunological surveillance of the eye, in particular of the anterior surface. In this review, we discuss the potential physiopathologic and therapeutic role of the TRAIL/TRAIL receptor system in a variety of ocular cancers. Moreover, since an increasing amount of data has indicated the important biological activities of the TRAIL/TRAIL receptor systems also in a completely different pathologic context such as diabetes mellitus, in the second part of this review we summarize the currently available data on the involvement of TRAIL in the ocular complications of diabetes mellitus as modulator of the inflammatory and angiogenic response in the eye.

Two-dimensional gel electrophoresis analysis of the leiomyoma interstitial fluid reveals altered protein expression with a possible involvement in pathogenesis

Uterine leiomyoma is the most common smooth benign neoplasm. In the present study, we analyzed the global interstitial fluid (IF) profile of leiomyoma vs. normal myometrium to identify protein dysregulation involved in leiomyoma pathogenesis. Two-dimensional gel electrophoresis and mass spectrometry were used to generate and compare the global interstitial fluid profiles of the leiomyoma and of the normal tissue. Two proteins were validated by immunohistochemistry. By comparing the interstitial fluid profile of the leiomyoma with that of the normal myometrium, the levels of seven proteins were found to be significantly different: four structural organization proteins (desmin, prelamin-A/C, transgelin and α-actinin-1), an inflammatory response (α1-antitrypsin), a response to oxidative stress (peroxiredoxin-2), and a folding protein (heat shock 70 kDa protein 1A/1B). Desmin, α1-antitrypsin and peroxiredoxin-2 were upregulated in the leiomyoma, whereas heat shock 70 kDa protein 1A/1B, α-actinin-1, prelamin-A/C and transgelin were downregulated. Desmin and α1-antitrypsin were further validated by immunohistochemistry. By identifying proteins with altered expression levels compared to the myometrium from several pathways of the leiomyoma pathogenesis, we found the leiomyoma interstitial fluid to have a characteristic proteomic profile. A better appreciation of the pathophysiology of the disease can be useful in the development of conservative treatments that serve as viable alternatives to hysterectomy.

STAT-6 mediates TRAIL induced RANK ligand expression in stromal/preosteoblast cells

Receptor activator of nuclear factor kappa-B ligand (RANKL) is a critical osteoclastogenic factor expressed in bone marrow stromal/osteoblast lineage cells. Tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL) levels are elevated in pathologic conditions such as multiple myeloma and inflammatory arthritis, and have been positively correlated with osteolytic markers. Osteoprotegerin (OPG) which inhibits osteoclastogenesis is a decoy receptor for RANKL and also known to interact with TRAIL. Herein, we show that TRAIL increases DR5 and DcR1 receptors but no change in the levels of DR4 and DcR2 expression in human bone marrow derived stromal/preosteoblast (SAKA-T) cell line. We further demonstrated that TRAIL treatment significantly decreased OPG mRNA expression. Interestingly, TRAIL treatment induced RANKL mRNA expression in these cells. In addition, TRAIL significantly increased NF-kB and c-Jun N-terminal kinase (JNK) activity. Human transcription factor array screening by real-time RT-PCR identified TRAIL up-regulation of the signal transducers and activators of the transcription (STAT)-6 expression in SAKA-T cells. TRAIL stimulation induced p-STAT-6 expression in human bone marrow derived primary stromal/preosteoblast cells. Confocal microscopy analysis further revealed p-STAT-6 nuclear localization in SAKA-T cells. Chromatin immunoprecipitation (ChIP) assay confirmed p-STAT-6 binding to the hRANKL gene distal promoter region. In addition, siRNA suppression of STAT-6 expression inhibits TRAIL increased hRANKL gene promoter activity. Thus, our results suggest that TRAIL induces RANKL expression through a STAT-6 dependent transcriptional regulatory mechanism in bone marrow stromal/preosteoblast cells.

Intranasal administration of recombinant TRAIL down-regulates CXCL-1/KC in an ovalbumin-induced airway inflammation murine model

Ovalbumin (OVA)-sensitized BALB/c mice were i.n. instilled with recombinant TNF-related apoptosis inducing ligand (TRAIL) 24 hours before OVA challenge. The total number of leukocytes and the levels of the chemokine CXCL-1/KC significantly increased in the bronchoalveolar lavage (BAL) fluids of allergic animals with respect to control littermates, but not in the BAL of mice i.n. pretreated with recombinant TRAIL before OVA challenge. In particular, TRAIL pretreatment significantly reduced the BAL percentage of both eosinophils and neutrophils. On the other hand, when TRAIL was administrated simultaneously to OVA challenge its effect on BAL infiltration was attenuated. Overall, the results show that the i.n. pretreatment with TRAIL down-modulated allergic airway inflammation.

Levels of circulating TNF-related apoptosis-inducing ligand in celiac disease

It has previously been demonstrated that the circulating levels of TNF-related apoptosis-inducing ligand (TRAIL) are significantly lower in patients with type 1 diabetes (T1D) than in normal age- and gender-matched controls. Since celiac disease (CD) is often associated with T1D, a retrospective study was performed to analyze the sera of a cohort of pediatric subjects: i) patients with CD at onset (n=100); ii) patients with potential CD (n=45); iii) patients with CD associated with other auto-immune diseases (n=17); and iv) patients with eosinophilic esophagitis (n=15). Among the patients with CD, 49 were also analyzed after six months on a gluten-free diet, while data were also available for 13 patients after one year on a gluten-free diet. No significant differences were found in the circulating levels of TRAIL between the patients with CD and the patients with either eosinophilic esophagitis or potential CD. Patients with CD associated with other auto-immune diseases showed significantly lower levels of TRAIL when compared with patients with CD alone. The gluten-free diet did not significantly modify the levels of circulating TRAIL at 6 or 12 months. Thus, although T1D and CD share common immunological features, the circulating levels of TRAIL show a significant difference between the two pathologies, and do not appear to be modulated in CD.

Soluble TRAIL is present at high concentrations in seminal plasma and promotes spermatozoa survival

The expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL(TNFSF10)) and of its receptors (TRAILR1, TRAILR2, TRAILR3, and TRAILR4) have been documented in testis, but the presence of soluble TRAIL in seminal fluid, as well as the potential physiopathological role of the TRAIL/TRAILR system in spermatozoa, has not been previously investigated. Male donors (n=123) among couples presenting for infertility evaluation were consecutively enrolled in this study. The presence of soluble TRAIL was analyzed in seminal samples by ELISA, while the surface expression of TRAIL receptors was investigated by flow cytometry. High levels of soluble TRAIL were detected in seminal plasma (median, 11 621 pg/ml and mean±s.d., 13 371±8367 pg/ml) and flow cytometric analysis revealed a variable expression of TRAIL receptors in the sperm cellular fraction among different subjects. In addition, the effect of physiologically relevant concentrations of recombinant TRAIL was investigated on survival and motility of spermatozoa. Of interest, the in vitro exposure of capacitated spermatozoa to recombinant TRAIL (10 ng/ml) significantly preserved their overall survival. Therefore, the present study demonstrates for the first time the presence of elevated levels of the anti-inflammatory cytokine TRAIL in seminal fluids. Moreover, the demonstration that recombinant TRAIL promotes spermatozoa survival after capacitation suggests potential therapeutic implications.

NF-κB pathways in hematological malignancies

The nuclear factor κB or NF-κB transcription factor family plays a key role in several cellular functions, i.e. inflammation, apoptosis, cell survival, proliferation, angiogenesis, and innate and acquired immunity. The constitutive activation of NF-κB is typical of most malignancies and plays a major role in tumorigenesis. In this review, we describe NF-κB and its two pathways: the canonical pathway (RelA/p50) and the non-canonical pathway (RelB/p50 or RelB/p52). We then consider the role of the NF-κB subunits in the development and functional activity of B cells, T cells, macrophages and dendritic cells, which are the targets of hematological malignancies. The relevance of the two pathways is described in normal B and T cells and in hematological malignancies, acute and chronic leukemias (ALL, AML, CLL, CML), B lymphomas (DLBCLs, Hodgkin's lymphoma), T lymphomas (ATLL, ALCL) and multiple myeloma. We describe the interaction of NF-κB with the apoptotic pathways induced by TRAIL and the transcription factor p53. Finally, we discuss therapeutic anti-tumoral approaches as mono-therapies or combination therapies aimed to block NF-κB activity and to induce apoptosis (PARAs and Nutlin-3).

The levels of circulating TRAIL at the onset of type 1 diabetes are markedly decreased in patients with ketoacidosis and with the highest insulin requirement

Experimental evidence in animal models suggests that TNF-related apoptosis-inducing ligand (TRAIL), a member of the TNF superfamily, might play an important role in type 1 diabetes (T1D). We have performed a retrospective study by analyzing the sera of a cohort of pediatric subjects (age ≤18 years; n = 507) consisting of (1) patients diagnosed with T1D (n = 387), (2) healthy individuals (n = 98, considered as controls), and (3) healthy autoantibody-positive subjects (n = 22). Patients with T1D exhibited significantly decreased levels of circulating TRAIL with respect to the control healthy subjects, as well as to the healthy autoantibody-positive subjects. Within the T1D group, no differences in the levels of circulating TRAIL were observed between patients with or without other concomitant autoimmune pathologies. Of note, the levels of TRAIL were significantly lower in the T1D patients analyzed at onset, although reduction in TRAIL levels persisted also in patients analyzed after disease onset (>1 year from diagnosis). In particular, T1D patients who exhibited ketoacidosis at onset showed significantly lower levels of circulating TRAIL with respect to patients without ketoacidosis at onset. Moreover, the levels of TRAIL at diagnosis correlated inversely with the insulin requirement up to 21 months of follow-up. This is the first study demonstrating that the levels of circulating TRAIL are significantly decreased in T1D, with the lowest levels of TRAIL being observed in patients with ketoacidosis at the onset and with the highest insulin requirement.

Modulation of circulating cytokine-chemokine profile in patients affected by chronic venous insufficiency undergoing surgical hemodynamic correction

The expression of proinflammatory cytokines/chemokines has been reported in in vitro/ex vivo settings of chronic venous insufficiency (CVI), but the identification of circulating mediators that might be associated with altered hemodynamic forces or might represent innovative biomarkers is still missing. In this study, the circulating levels of 31 cytokines/chemokines involved in inflammatory/angiogenic processes were analysed in (i) CVI patients at baseline before surgical hemody namic correction, (ii) healthy subjects, and (iii) CVI patients after surgery. In a subgroup of CVI patients, in whom the baseline levels of cytokines/chemokines were analyzed in paired blood samples obtained from varicose vein and forearm vein, EGF, PDGF, and RANTES were increased at the varicose vein site as compared to the general circulation. Moreover, while at baseline, CVI patients showed increased levels of 14 cytokines/chemokines as compared to healthy subjects, 6 months after surgery, 11 cytokines/chemokines levels were significantly reduced in the treated CVI patients as compared to the CVI patients before surgery. Of note, a patient who exhibited recurrence of the disease 6 months after surgery, showed higher levels of EGF, PDGF, and RANTES compared to nonrecurrent patients, highlighting the potential role of the EGF/PDGF/RANTES triad as sensitive biomarkers in the context of CVI.

GM-CSF exhibits anti-inflammatory activity on endothelial cells derived from chronic venous disease patients

Twenty patients affected by chronic venous disease (CVD) in tertiary venous network and/or saphenous vein were analyzed before surgical ablation by echo-color-doppler for the hemodynamic parameters reflux time (RT) and resistance index (RI), a negative and a positive prognostic factor, respectively. RT and RI were next correlated with relevant in vitro parameters of venous endothelial cells (VEC) obtained from surgical specimens, such as cell migration in response to serum gradient, proliferation index, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 expression, as well as cytokines release. Of interest, ICAM-1 expression in patient-derived VEC cultures correlated positively with RT and negatively with RI. Moreover, RT showed a positive correlation with the baseline osteoprotegerin (OPG) expression by VEC and an inverse correlation with VEC proliferation index. On the other hand, RI correlated positively with TNF-related apoptosis inducing ligand (TRAIL) expression. Among the cytokines released by VEC, GM-CSF showed a positive correlation with VEC proliferation and TRAIL expression and a negative correlation with OPG, ICAM-1 and VCAM-1 expression. Since in vitro recombinant GM-CSF induced VEC proliferation and counteracted the induction of ICAM-1, VCAM-1 and OPG upon exposure to TNF-α, our data suggest an anti-inflammatory activity of GM-CSF on venous endothelial cells.

Levels of TNF-related apoptosis-inducing ligand (TRAIL) show a long-term stability in the breast milk of mothers of preterm infants

BACKGROUND

The immune modulator TNF-related apoptosis-inducing ligand (TRAIL) has been found at extremely high levels in human milk of women with normal gestation at day 5 after delivery.

OBJECTIVE

To investigate the presence and the levels of soluble TRAIL in human milk of women with preterm delivery at different time points post-partum (32, 34, and 36 weeks from conception).

METHODS

The levels of soluble TRAIL were analyzed by ELISA in the breast milk of a group of 25 women with preterm delivery at different gestational ages.

RESULTS

Soluble TRAIL was present at high levels in human milk since early post-conceptional ages (32 weeks). No significant differences in TRAIL levels were noticed with respect to different gestational ages, or with respect to time of collection when comparing, in a selected group of patients, samples obtained between 15 and 26 days with those obtained 27 and 40 days after birth.

CONCLUSION

Due to the key immunoregulatory role of human soluble TRAIL, the presence of high levels of TRAIL in the milk of women with preterm delivery and its maintenance at high levels up to 72 days after birth support the importance of breastfeeding the preterm newborn.

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

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

AML1/ETO sensitizes via TRAIL acute myeloid leukemia cells to the pro-apoptotic effects of hypoxia

We determined the effects of severe hypoxia (∼0.1% O₂) on acute myeloid leukemia cells expressing the AML1/ETO oncogene. Incubation of Kasumi-1 cells in hypoxia induced growth arrest, apoptosis and reduction of AML1/ETO protein expression. The conditional expression of AML1/ETO in U937-A/E cells showed that hypoxia induces marked apoptosis in AML1/ETO-expressing cells only, pointing to AML1/ETO as a factor predisposing cells to hypoxia-induced apoptosis. In AML1/ETO-expressing cells, hypoxia enhanced TRAIL expression and its proapoptotic effects. AML1/ETO was found to bind TRAIL promoter and induce TRAIL transcription, although TRAIL expression was restrained by a concomitant relative transcription block. In hypoxia, such a TRAIL repression was removed and an increase of TRAIL expression was induced. Finally, blocking anti-TRAIL antibodies markedly reduced (Kasumi-1 cells) or completely inhibited (U937-A/E cells) hypoxia-induced apoptosis. Taken together, these results indicated that hypoxia induces apoptosis in AML1/ETO-expressing cells via a TRAIL/caspase 8-dependent autocrine loop and that TRAIL is a key regulator of hypoxia-induced apoptosis in these cells.

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

PURPOSE

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

EXPERIMENTAL DESIGN

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

RESULTS

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

CONCLUSIONS

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

Presence of CTAK/CCL27, MCP-3/CCL7 and LIF in human colostrum and breast milk

Human colostrum and breast milk are known to contain high levels of cytokines and chemokines, which are thought to contribute to the development of the newborn. The aim of this study was to investigate the difference in the presence and levels of 21 soluble cytokines and chemokines in paired samples of human colostrum (day 2 after delivery) and breast milk (day 4-5 after delivery) by using the multiplex technology. Of the 21 cytokine investigated in 10 pairs of samples, only β-NGF was absent in both colostrum and milk, while INF-α2, SCF and TNF-β were present in colostrum but not in human milk. As a general rule, colostrum contained higher concentrations of cytokines and chemokines with respect to breast milk. The majority of cytokines, detected in colostrum alone or in colostrum and human milk (IL-1α, IL-2Rα, IL-3, IL-16, IL-18, GRO-α, HGF, IFN-α2, M-CSF, MIF, MIG, TNF-β, SDF-1α, TRAIL) have been described in previous studies, while for the first time we describe the presence of additional cytokines either in colostrum alone (SCF) or in both colostrum and breast milk (CTAK/CCL27, MCP-3/CCL7, LIF). Our data confirm and expand previous studies showing that some cytokines/chemokines, which might contribute to the development of the gastro-intestinal and nervous systems, are overexpressed in human colostrum and breast milk, and might contribute to the development of these systems.

TNF-related apoptosis-inducing ligand significantly attenuates metabolic abnormalities in high-fat-fed mice reducing adiposity and systemic inflammation

TRAIL [TNF (tumour necrosis factor)-related apoptosis-inducing ligand] has recently been shown to ameliorate the natural history of DM (diabetes mellitus). It has not been determined yet whether systemic TRAIL delivery would prevent the metabolic abnormalities due to an HFD [HF (high-fat) diet]. For this purpose, 27 male C57bl6 mice aged 8 weeks were randomly fed on a standard diet, HFD or HFD+TRAIL for 12 weeks. TRAIL was delivered weekly by intraperitoneal injection. Body composition was evaluated; indirect calorimetry studies, GTT (glucose tolerance test) and ITT (insulin tolerance test) were performed. Pro-inflammatory cytokines, together with adipose tissue gene expression and apoptosis, were measured. TRAIL treatment reduced significantly the increased adiposity associated with an HFD. Moreover, it reduced significantly hyperglycaemia and hyperinsulinaemia during a GTT and it improved significantly the peripheral response to insulin. TRAIL reversed the changes in substrate utilization induced by the HFD and ameliorated skeletal muscle non-esterified fatty acids oxidation rate. This was associated with a significant reduction of pro-inflammatory cytokines together with a modulation of adipose tissue gene expression and apoptosis. These findings shed light on the possible anti-adipogenic and anti-inflammatory effects of TRAIL and open new therapeutic possibilities against obesity, systemic inflammation and T2DM (Type 2 DM).

Soluble TRAIL is elevated in recurrent miscarriage and inhibits the in vitro adhesion and migration of HTR8 trophoblastic cells

STUDY QUESTION

What is the potential physiopathological role of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) in recurrent miscarriage (RM), characterized by at least three consecutive pregnancy losses.

SUMMARY ANSWER

The levels of serum TRAIL immediately after miscarriage in RM patients are significantly elevated with respect to that in first-trimester normal pregnant women, and recombinant TRAIL inhibits the adhesion and migration of HTR8 trophoblastic cells in vitro.

WHAT IS KNOWN ALREADY

Both TRAIL and its trans-membrane receptors (TRAIL-R1, TRAIL-R2, TRAIL-R3 and TRAIL-R4) have been documented in the placenta, but their physiopathological role is incompletely understood.

STUDY DESIGN, SIZE, DURATION

The study populations consisted of RM patients (n = 80) and first-trimester normal pregnant women (n = 80). Blood samples were obtained within 24 h after abortion (RM) or at gestational 12-week (normal pregnant women). As additional controls, third-trimester normal pregnant women (n = 28) were examined before (within 72 h) and after (within 24 h) partum.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The concentrations of TRAIL were analysed in serum samples by ELISA. In parallel, the effect of soluble recombinant TRAIL (0.1-1000 ng/ml) was analysed on the survival of primary extravillus trophoblasts (EVTs) and on the survival, proliferation, adhesion and migration of trophoblastic HTR8 cells.

MAIN RESULTS AND THE ROLE OF CHANCE

The circulating levels of TRAIL in RM women (median: 52.5 pg/ml; mean and SD: 55.5 ± 24.4 pg/ml) were significantly higher with respect to first-trimester normal pregnant women (median: 44.9 pg/ml; mean and SD: 47 ± 15.1 pg/ml) and third-trimester normal pregnant women, as assessed before (median: 45.1 pg/ml; mean and SD: 46 ± 12.4 pg/ml) and after partum (median: 35.4 pg/ml; mean and SD: 38 + 17.5 pg/ml). Both primary EVT and HTR8 cells expressed detectable levels of TRAIL death receptors, but exposure to soluble recombinant TRAIL did not induce cell death of trophoblastic cells. On the other hand, TRAIL dose-dependently inhibited the adhesion of HTR8 cells to decidual endothelial cells (DEC) as well as the migration of HTR8 in transwell assays using either fibronectin or DEC.

LIMITATIONS, REASONS FOR CAUTION

Although this study suggests that TRAIL might have a pathogenic role in RM by inhibiting both the adhesion and migration capabilities of first trimester trophoblastic cells, there is a possibility that the elevated serum levels of TRAIL in RM are not cause but rather the result of RM.

WIDER IMPLICATIONS OF THE FINDINGS

Our current findings together with data of other authors suggest that circulating TRAIL should be further analysed as a potential important biomarker in different physiopathological settings.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by FIRB projects (RBAP11Z4Z9_002 to Giorgio Zauli and RBAP10447J_002 to Paola Secchiero). The authors have no competing interests to declare.

TRAIL administration down-modulated the acute systemic inflammatory response induced in a mouse model by muramyldipeptide or lipopolysaccharide

The potent inducer of apoptosis TRAIL/Apo2 ligand is now under considerations in clinical trials for the treatment of different types of cancer. Since the natural history of cancer is often characterized by microbial infections, we have investigated the effect of recombinant human TRAIL in a mouse model of systemic acute inflammation of microbial origin represented by BALB/c mice treated with either bacterial muramyldipeptide (MDP) or lipopolysaccharide (LPS). When administered intraperitoneally (i.p.), these inflammatory bacterial compounds triggered a severe systemic inflammatory response within 2h, represented by body temperature elevation, increase of circulating serum amyloid-A (SAA) and of the number of leukocytes in the peritoneal cavity. Moreover, both MDP and LPS induced a significant elevation of the circulating levels of several inflammatory cytokines and chemokines. Noteworthy, pre-treatment with recombinant human TRAIL 48 and 72 h before administration of either MDP or LPS, significantly counteracted all acute inflammatory responses, including the elevation of key pro-inflammatory cytokines/chemokines such as IL-1α, IL-6, G-CSF, MCP-1. These data demonstrate for the first time that TRAIL has a potent anti-inflammatory activity, which might be beneficial for the anti-tumoral activity of TRAIL.

Type 1 interferons suppress accelerated osteoclastogenesis and prevent loss of bone mass during systemic inflammatory responses to Pneumocystis lung infection

HIV infection causes loss of CD4(+) T cells and type 1 interferon (IFN)-producing and IFN-responsive dendritic cells, resulting in immunodeficiencies and susceptibility to opportunistic infections, such as Pneumocystis. Osteoporosis and bone marrow failure are additional unexplained complications in HIV-positive patients and patients with AIDS, respectively. We recently demonstrated that mice that lack lymphocytes and IFN a/b receptor (IFrag(-/-)) develop bone marrow failure after Pneumocystis lung infection, whereas lymphocyte-deficient, IFN α/β receptor-competent mice (RAG(-/-)) had normal hematopoiesis. Interestingly, infected IFrag(-/-) mice also exhibited bone fragility, suggesting loss of bone mass. We quantified bone changes and evaluated the potential connection between progressing bone fragility and bone marrow failure after Pneumocystis lung infection in IFrag(-/-) mice. We found that Pneumocystis infection accelerated osteoclastogenesis as bone marrow failure progressed. This finding was consistent with induction of osteoclastogenic factors, including receptor-activated nuclear factor-κB ligand and the proapoptotic factor tumor necrosis factor-related apoptosis-inducing ligand, in conjunction with their shared decoy receptor osteoprotegerin, in the bone marrow of infected IFrag(-/-) mice. Deregulation of this axis has also been observed in HIV-positive individuals. Biphosphonate treatment of IFrag(-/-) mice prevented bone loss and protected loss of hematopoietic precursor cells that maintained activity in vitro but did not prevent loss of mature neutrophils. Together, these data show that bone loss and bone marrow failure are partially linked, which suggests that the deregulation of the receptor-activated nuclear factor-κB ligand/osteoprotegerin/tumor necrosis factor-related apoptosis-inducing ligand axis may connect the two phenotypes in our model.

Inhibition of TACE activity enhances the susceptibility of myeloma cells to TRAIL

BACKGROUND

TNF-related apoptosis-inducing ligand/Apo2 ligand (TRAIL/Apo2L) selectively induces apoptosis in various cancer cells including myeloma (MM) cells. However, the susceptibility of MM cells to TRAIL is largely low in most of MM cells by yet largely unknown mechanisms. Because TNF-α converting enzyme (TACE) can cleave some TNF receptor family members, in the present study we explored the roles of proteolytic modulation by TACE in TRAIL receptor expression and TRAIL-mediated cytotoxicity in MM cells.

METHODOLOGY/PRINCIPAL FINDINGS

MM cells preferentially expressed death receptor 4 (DR4) but not DR5 on their surface along with TACE. Conditioned media from RPMI8226 and U266 cells contained a soluble form of DR4. The DR4 levels in these conditioned media were reduced by TACE inhibition by the TACE inhibitor TAPI-0 as well as TACE siRNA. Conversely, the TACE inhibition restored surface levels of DR4 but not DR5 in these cells without affecting DR4 mRNA levels. The TACE inhibition was able to restore cell surface DR4 expression in MM cells even in the presence of bone marrow stromal cells or osteoclasts, and enhanced the cytotoxic effects of recombinant TRAIL and an agonistic antibody against DR4 on MM cells.

CONCLUSIONS/SIGNIFICANCE

These results demonstrate that MM cells post-translationally down-modulate the cell surface expression of DR4 through ectodomain shedding by endogenous TACE, and that TACE inhibition is able to restore cell surface DR4 levels and the susceptibility of MM cells to TRAIL or an agonistic antibody against DR4. Thus, TACE may protect MM cells from TRAIL-mediated death through down-modulation of cell-surface DR4. It can be envisaged that TACE inhibition augments clinical efficacy of TRAIL-based immunotherapy against MM, which eventually becomes resistant to the present therapeutic modalities.

Creating a tumor-resistant microenvironment: cell-mediated delivery of TNFα completely prevents breast cancer tumor formation in vivo

Here, we provide the necessary proof of concept, that it is possible to metabolically create a non-permissive or "hostile" stromal microenvironment, which actively prevents tumor engraftment in vivo. We developed a novel genetically engineered fibroblast cell line that completely prevents tumor formation in mice, with a 100% protection rate. No host side effects were apparent. This could represent a viable cellular strategy for preventing and treating a variety of human cancers. More specifically, we examined the autocrine and paracrine effects of the cellular delivery of TNFα on breast cancer tumor growth and cancer metabolism. For this purpose, we recombinantly overexpressed TNFα in human breast cancer cells (MDA-MB-231) or human immortalized fibroblasts (hTERT-BJ1). Our results directly show that TNFα functions as a potent tumor suppressor. Remarkably, TNFα-expressing breast cancer cells were viable, without any significant increases in their basal apoptotic rate. However, after 4 weeks post-implantation, TNFα-expressing breast cancer cells failed to form any tumors in xenografted mice (0 tumors/10 injections), ultimately conferring 100% protection against tumorigenesis. Similarly, TNFα-overexpressing fibroblasts were also viable, without any increases in apoptosis. Significantly, complete tumor suppression was obtained by co-injecting TNFα expressing stromal fibroblasts with human breast cancer cells, indicating that paracrine cell-mediated delivery of TNFα can also prevent tumor engraftment and growth (0 tumors/10 injections). Mechanistically, TNFα induced autophagy and mitochondrial dysfunction in both epithelial cancer cells and stromal fibroblasts, preventing energy transfer from the tumor microenvironment, likely "starving" the cancer cells to death. In addition, via qRT-PCR analysis of MDA-MB-231 cells, we observed that TNFα mediated the upregulation of gene transcripts associated with inflammation and senescence [IL-1-β, IL-6, IL-8, MCP-1, COX-2, p21(WAF1/CIP1)] and downregulated known tumor-promoting genes (collagen VI and MMP2). Recombinant overexpression of TNFα receptor(s) in MDA-MB-231 cells also significantly reduced tumor growth, but was not as effective as the TNFα ligand itself in preventing tumor growth. Thus, we propose that stromal cell-mediated delivery of TNFα to human tumors [using transfected fibroblasts or mesenchymal stem cells (hMSCs)] may be a novel and effective strategy for the prevention and treatment of human cancers.

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

Background

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

Methods/Principal Findings

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

Conclusions

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

Trail down-regulates the release of osteoprotegerin (OPG) by primary stromal cells

The soluble member of the TNF-R superfamily osteoprotegerin (OPG) is abundantly released under basal conditions by both mesenchymal stem cells (MSC) and fibroblasts and by endothelial cells upon stimulation with inflammatory cytokines. Since MSC, fibroblasts and endothelial cells represent key elements of the normal and tumor microenvironment and express detectable levels of surface TRAIL receptors, we investigated the effect of TRAIL on OPG release. Unexpectedly, recombinant TRAIL decreased the spontaneous OPG release in all cell types examined. Moreover, TRAIL decreased OPG release also in stromal cells co-cultured with lymphoma cells and counteracted the OPG induction by TN-alpha in HUVEC and MSC. Such down-regulation was not due to a masking effect in the ELISA quantification of the OPG released in the culture supernatants due to binding of OPG to its ligands (TRAIL and RANKL), as demonstrated by competition experiments with recombinant TRAIL and by the lack of RANKL release/induction. In addition, OPG down-regulation was not due to induction of cytotoxic effects by TRAIL, since the degree of apoptosis in response to TRAIL was negligible in all primary cell types. With regards to the possible molecular mechanism accounting for the down-regulation of OPG release by TRAIL, we found that treatment of MSC with TRAIL significantly decreased the phosphorylation levels of p38/MAPK. There is a suggestion that this pathway is involved in the stabilization of OPG mRNA. In this respect, the ability of TRAIL to decrease the release of OPG, in the absence of cell cytotoxicity, was mimicked by the p38/MAPK inhibitor SB203580.

Pegylated TRAIL retains anti-leukemic cytotoxicity and exhibits improved signal transduction activity with respect to TRAIL

To improve the pharmacokinetic profile of tumor necrosis factor-related apoptosis inducing ligand (TRAIL) an N-terminal specific pegylation was performed to generate pegylated TRAIL (PEG-TRAIL). In in vitro experiments, we found that although PEG-TRAIL was slightly less efficient than recombinant TRAIL in promoting leukemic cell apoptosis, it showed an improved ability to promote migration of bone-marrow mesenchymal stem cells and to elicit the ERK1/2 intracellular signal transduction pathway. Overall, these data suggest that TRAIL pegylation retains, or even enhances, the biological activities of TRAIL relevant for its therapeutic applications.

In vivo anti-lymphoma activity of an agonistic human recombinant anti-TRAIL-R2 minibody

A new single-chain fragment variable (scFv) to TRAIL-R2 receptor produced as minibody (MB2.23) was characterized for anti-lymphoma activity in vivo. For this purpose, a disseminated lymphoma model was generated by intraperitoneal inoculation of BJAB cells in severe combined immunodeficiency mice. Two weekly injections with MB2.23 (10 mg/kg) were able to significantly increase the median survival time of lymphoma-bearing animals with respect to the vehicle-treated control mice, providing a rationale for further investigating the use of MB2.23 in anticancer therapy.

Regulatory functions of TRAIL in hematopoietic progenitors: human umbilical cord blood and murine bone marrow transplantation

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) signaling pathway has selective toxicity to malignant cells. The TRAIL receptors DR4 and DR5 are expressed at low levels in human umbilical cord blood cells (3-15%) and are upregulated by incubation with the cognate ligand, triggering apoptosis in 70-80% of receptor-positive cells (P<0.001). Apoptosis is not induced in hematopoietic progenitors, as determined from sustained severe combined immunodeficiency reconstituting potential and clonogenic activity. Furthermore, elimination of dead cells after incubation with TRAIL for 72 h results in a threefold enrichment in myeloid progenitors. Exposure to TRAIL in semisolid cultures showed synergistic activity of DR4 and granulocyte/macrophage colony-stimulating factor in recruiting lineage-negative (lin(-)) and CD34(+) progenitors and in promoting the formation of large colonies. In murine bone marrow, approximately 30% of lin(-) cells express TRAIL-R2 (the only murine receptor), and the receptor is upregulated after transplantation in cycling and differentiating donor cells that home to the host marrow. However, this receptor is almost ubiquitously expressed in the most primitive (lin(-)SCA-1(+)c-kit(+)) progenitors, and stimulates the clonogenic activity of lin(-) cells (P<0.001), suggesting a tropic function after transplantation. It is concluded that TRAIL does not trigger apoptosis in hematopoietic progenitors, and upregulation of its cognate receptors under stress conditions mediates tropic signaling that supports recovery from hypoplasia.

Control of death receptor ligand activity by posttranslational modifications

The death receptor ligands are involved in many physiological and pathological processes involving triggering of apoptosis, inflammation, proliferation, and activation. The expression of these molecules is reported to be tightly regulated at the transcriptional level. However, over the last few years, an increasing number of data demonstrated that the control of transcription is only one of the mechanisms that manage the expression of the death receptor ligands. Thus, this review is focused on posttranslational regulation of the three main members of this family, namely FasL, TNF-alpha, and TRAIL. We discuss here the importance of distribution, storage, and degranulation of these molecules, as well as their shedding by proteases on the control of death receptor ligands expression and activity.

Activation of PKC-ε counteracts maturation and apoptosis of HL-60 myeloid leukemic cells in response to TNF family members

Protein kinase C (PKC)-ε, a component of the serine/threo-nine PKC family, has been shown to influence the survival and differentiation pathways of normal hematopoietic cells. Here, we have modulated the activity of PKC-ε with specific small molecule activator or inhibitor peptides. PKC-ε inhibitor and activator peptides showed modest effects on HL-60 maturation when added alone, but PKC-ε activator peptide significantly counteracted the pro-maturative activity of tumor necrosis factor (TNF)-α towards the monocytic/macrophagic lineage, as evaluated in terms of CD14 surface expression and morphological analyses. Moreover, while PKC-ε inhibitor peptide showed a reproducible increase of TNF-related apoptosis inducing ligand (TRAIL)-induced apoptosis, PKC-ε activator peptide potently counteracted the pro-apoptotic activity of TRAIL. Taken together, the anti-maturative and anti-apoptotic activities of PKC-ε envision a potentially important proleukemic role of this PKC family member.

Growth suppressive cytokines and the AKT/mTOR pathway

The mTOR signaling pathway plays a very important role in the transmission of signals for initiation of mRNA translation and protein expression in mammalian cells. mTOR activates various downstream effectors to promote initiation of cap-dependent mRNA translation and mediate pro-mitogenic and pro-survival signals. Recent evidence has implicated effectors of this signaling cascade in mRNA translation for interferon stimulated genes (ISGs). In addition, it was recently shown that AKT/mTOR-mediated signals play important roles in the generation of IFN-dependent antiviral and growth inhibitory responses, suggesting that mTOR and its effectors can mediate diverse biological responses, depending on the cellular context and the triggering stimuli. In this review, the regulatory effects of various growth suppressive cytokines on the mTOR pathway are summarized and the emerging new functions of mTOR are discussed.

Non-canonical role for the TRAIL receptor DR5/FADD/caspase pathway in the regulation of MyoD expression and skeletal myoblast differentiation

We report herein that the TRAIL receptor DR5/FADD/caspase pathway plays a role in skeletal myoblast differentiation through modulation of the expression of the muscle regulatory transcription factor MyoD. Specifically, treatment with the selective caspase 3 inhibitor DEVD-fmk or the selective caspase 8 inhibitor IETD-fmk in growth media (GM), prior to culture in differentiation media (DM), inhibited differentiation. Further, this treatment resulted in decreased levels of MyoD message and protein. We next explored a role for the TRAIL receptor DR5/FADD pathway. We found that expression of either dominant negative (dn) FADD or dominant negative (dn) DR5 also resulted in decreased levels of MyoD mRNA and protein and blocked differentiation. This decreased level of MyoD mRNA was not a consequence of altered stability. Treatment with TSA, an inhibitor of histone deacetylases (HDACs), allowed MyoD expression in myoblasts expressing dnDR5. Finally, acetylation of histones associated with the distal regulatory region (DRR) enhancer of MyoD was decreased in myoblasts expressing dnDR5. Thus, our data suggests a non-canonical role for the TRAIL receptor/FADD pathway in the regulation of MyoD expression and skeletal myoblast differentiation.