Role of soluble tumor necrosis factor-related apoptosis-inducing ligand concentrations after stem cell transplantation

Biomarkers of graft-vs-host disease: Understanding and applications for the future

Hematopoietic stem cell transplantation (HSCT) is widely performed as a treatment for malignant blood disorders, such as leukemia. To achieve good clinical outcomes in HSCT, it is necessary to minimize the unfavorable effects of acute graft-vs-host disease (GVHD) and induce the more tolerable, chronic form of the disease. For better management of GVHD, sensitive and specific biomarkers that predict the severity and prognosis of the disease have been intensively investigated using proteomics, transcriptomics, genomics, cytomics, and tandem mass spectrometry methods. Here, I will briefly review the current understanding of GVHD biomarkers and future prospects.

Cytotoxic Pathways in Allogeneic Hematopoietic Cell Transplantation

Allogeneic hematopoietic cell transplantation (allo-HCT) is a potentially curative treatment for hematologic malignancies, and other hematologic and immunologic diseases. Donor-derived immune cells identify and attack cancer cells in the patient producing a unique graft-vs.-tumor (GVT) effect. This beneficial response renders allo-HCT one of the most effective forms of tumor immunotherapy. However, alloreactive donor T cells can damage normal host cells thereby causing graft-vs.-host disease (GVHD), which results in substantial morbidity and mortality. To date, GVHD remains as the major obstacle for more successful application of allo-HCT. Of special significance in this context are a number of cytotoxic pathways that are involved in GVHD and GVT response as well as donor cell engraftment. In this review, we summarize progress in the investigation of these cytotoxic pathways, including Fas/Fas ligand (FasL), perforin/granzyme, and cytokine pathways. Many studies have delineated their distinct operating mechanisms and how they are involved in the complex cellular interactions amongst donor, host, tumor, and infectious pathogens. Driven by progressing elucidation of their contributions in immune reconstitution and regulation, various interventional strategies targeting these pathways have entered translational stages with aims to improve the effectiveness of allo-HCT.

Effects of recombinant thrombomodulin therapy and soluble human leukocyte antigen-G levels during hematopoietic stem cell transplantation

BACKGROUND

Conditioning chemotherapies for hematopoietic stem cell transplantation (HSCT), especially those that include total body irradiation, can result in serious complications such as graft-versus-host disease (GVHD). Human leukocyte antigen G (HLA-G) is a non-classical class I molecule with multiple immunoregulatory functions.

METHODS

We measured interleukin (IL)-10, transforming growth factor (TGF)β₁, and soluble HLA-G (sHLA-G) in HSCT patients and examined the relationship between sHLA-G levels and acute GVHD (aGVHD). Additionally, we investigated the effect of recombinant soluble thrombomodulin (rTM) therapy on sHLA-G levels. Our study cohort included 135 patients who underwent allogeneic HSCT at several institutions in Japan.

RESULTS

Serum levels of IL-10 and TGFβ₁ exhibited no significant changes following HSCT. In contrast, levels of sHLA-G were significantly increased at days 21 and 28 post-HSCT. For patients with confirmed complications, the frequency of aGVHD was significantly lower in those with a > 2.8-fold increase in sHLA-G levels at day 28 relative to day 7 post-HSCT. sHLA-G levels in patients who received rTM therapy were significantly higher at days 21 and 28 post-HSCT compared with those in patients who did not receive rTM therapy.

CONCLUSION

These data suggest that HLA-G/sHLA-G participate in prevention of GVHD, and that rTM may prevent aGVHD following HSCT by promoting elevation of sHLA-G.

Associations between acute GVHD-related biomarkers and endothelial cell activation after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) can cause serious transplant-related complications such as graft-versus-host disease (GVHD). Acute GVHD (aGVHD) has been diagnosed by clinical manifestations, laboratory data and pathological effects until now, but recently the discovery of specific biomarkers such as suppression of tumorigenicity 2 (ST2), elafin and regenerating islet-derived 3α (REG3α) is challenging this approach.

METHODS

We investigated the expression of aGVHD-related markers (regulated on activation normal T-cell expressed and secretes: RANTES, elafin, REG3α and ST2) and endothelial cell activation markers (soluble vascular cell adhesion molecule: sVCAM-1 and plasminogen activator inhibitor: PAI-1) in patients undergoing allogeneic HSCT. Additionally, we studied the effects of recombinant soluble thrombomodulin (rTM) on the expression of these markers. Our study cohort included 225 patients who underwent allogeneic HSCT at several institutions in Japan.

RESULTS

RANTES, sVCAM-1, PAI-1, elafin, REG3α and ST2 exhibited significant increases in patients not receiving rTM after HSCT. When we examined patients with confirmed complications, the frequencies of aGVHD and VOD were significantly lower in the rTM-treated group. In addition, aGVHD-related biomarkers such as elafin, REG3α, and ST2 were elevated significantly in patients with aGVHD.

CONCLUSION

Our findings suggest that endothelial cell activation might be linked to aGVHD, and that rTM might act to prevent aGVHD, at least in part, through its effect on endothelial cells.

Digging more in the genetic risk prediction of hepatitis C virus epidemic in Egypt: Apoptosis genes polymorphisms in the susceptibility of hepatitis C virus and association with viral load

Egypt is confronted with the highest hepatitis C virus (HCV) epidemic. Apoptosis and cellular immune responses are crucial to the clearance or persistence of viral infections. This case-control study was carried out to detect whether apoptosis genes single nucleotide polymorphisms (SNPs) confer risk to HCV in a cohort of Egyptian patients and to explore their association with viral load. One hundred and ninety six blood samples were withdrawn from 96 HCV patients and 100 controls. The Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) -1525G>A and FasL-844T>C SNPs were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Hepatitis C viral load was measured using Real time PCR. Results Genotypes distributions of TRAIL -1525G>A and FasL-844 T>C polymorphisms in controls were in accordance with Hardy-Weinberg equilibrium (p>0.05). The study showed a statistically significant difference in the distribution of the TRAIL -1525G>A polymorphism genotypes and the FasL-844 T>C polymorphism genotypes between the HCV patients and the controls (p=0.001 and 0.02 respectively), with association of the -1525GA genotype and -844 TT genotype with increased risk of HCV infection (OR=2.68, 1.942 respectively, 95% CI=1.482-4.846, 1.1-3.43, respectively). No significant association was detected between TRAIL, FasL and the viral load. Our results suggest that the FasL -844T>C SNP is implicated in the susceptibility to HCV in Egyptian patients and firstly report the involvement of TRAIL gene polymorphism in the risk of the disease. Therefore we recommend national programs to delineate genetic factors that may put individuals at risk for contracting HCV.

Extracellular vesicles and blood diseases

Extracellular vesicles (EVs) are small membrane vesicles released from many different cell types by the exocytic budding of the plasma membrane in response to cellular activation or apoptosis. EVs disseminate various bioactive effectors originating from the parent cells and transfer functional RNA and protein between cells, enabling them to alter vascular function and induce biological responses involved in vascular homeostasis. Although most EVs in human blood originate from platelets, EVs are also released from leukocytes, erythrocytes, endothelial cells, smooth muscle cells, and cancer cells. EVs were initially thought to be small particles with procoagulant activity; however, they can also evoke cellular responses in the immediate microenvironments and transport microRNAs (miRNA) into target cells. In this review, we summarize the recent literature relevant to EVs, including a growing list of clinical disorders that are associated with elevated EV levels. These studies suggest that EVs play roles in various blood diseases.

Clinical significance of procoagulant microparticles

Microparticles (MPs) are small membrane vesicles that are released from many different cell types by exocytic budding of the plasma membrane in response to cellular activation or apoptosis. MPs may also be involved in clinical diseases because they express phospholipids, which function as procoagulants. Although flow cytometry is the most widely used method for studying MPs, some novel assays, such as tissue factor-dependent procoagulant assay or the ELISA method, have been reported. However, the use of quantification of MP as a clinical tool is still controversial. Elevated platelet-derived MP, endothelial cell-derived MP, and monocyte-derived MP concentrations are documented in almost all thrombotic diseases occurring in venous and arterial beds. However, the significance of MPs in various clinical conditions remains controversial. An example of this controversy is that it is unknown if MPs found in peripheral blood vessels cause thrombosis or whether they are the result of thrombosis. Numerous studies have shown that not only the quantity, but also the cellular origin and composition of circulating MPs, are dependent on the type of disease, the disease state, and medical treatment. Additionally, many different functions have been attributed to MPs. Therefore, the number and type of clinical disorders associated with elevated MPs are currently increasing. However, MPs were initially thought to be small particles with procoagulant activity. Taken together, our review suggests that MPs may be a useful biomarker to identify thrombosis.

Early transcriptional responses of bovine chorioallantoic membrane explants to wild type, ΔvirB2 or ΔbtpB Brucella abortus infection

The pathogenesis of the Brucella-induced inflammatory response in the bovine placenta is not completely understood. In this study we evaluated the role of the B. abortus Type IV secretion system and the anti-inflammatory factor BtpB in early interactions with bovine placental tissues. Transcription profiles of chorioallantoic membrane (CAM) explants inoculated with wild type (strain 2308), ΔvirB2 or ΔbtpB Brucella abortus were compared by microarray analysis at 4 hours post infection. Transcripts with significant variation (>2 fold change; P<0.05) were functionally classified, and transcripts related to defense and inflammation were assessed by quantitative real time RT-PCR. Infection with wild type B. abortus resulted in slightly more genes with decreased than increased transcription levels. Conversely, infection of trophoblastic cells with the ΔvirB2 or the ΔbtpB mutant strains, that lack a functional T4SS or that has impaired inhibition of TLR signaling, respectively, induced more upregulated than downregulated genes. Wild type Brucella abortus impaired transcription of host genes related to immune response when compared to ΔvirB and ΔbtpB mutants. Our findings suggest that proinflammatory genes are negatively modulated in bovine trophoblastic cells at early stages of infection. The virB operon and btpB are directly or indirectly related to modulation of these host genes. These results shed light on the early interactions between B. abortus and placental tissue that ultimately culminate in inflammatory pathology and abortion.

Identification of STAT5A and STAT5B target genes in human T cells

Signal transducer and activator of transcription (STAT) comprises a family of universal transcription factors that help cells sense and respond to environmental signals. STAT5 refers to two highly related proteins, STAT5A and STAT5B, with critical function: their complete deficiency is lethal in mice; in humans, STAT5B deficiency alone leads to endocrine and immunological problems, while STAT5A deficiency has not been reported. STAT5A and STAT5B show peptide sequence similarities greater than 90%, but subtle structural differences suggest possible non-redundant roles in gene regulation. However, these roles remain unclear in humans. We applied chromatin immunoprecipitation followed by DNA sequencing using human CD4⁺ T cells to detect candidate genes regulated by STAT5A and/or STAT5B, and quantitative-PCR in STAT5A or STAT5B knock-down (KD) human CD4⁺ T cells to validate the findings. Our data show STAT5A and STAT5B play redundant roles in cell proliferation and apoptosis via SGK1 interaction. Interestingly, we found a novel, unique role for STAT5A in binding to genes involved in neural development and function (NDRG1, DNAJC6, and SSH2), while STAT5B appears to play a distinct role in T cell development and function via DOCK8, SNX9, FOXP3 and IL2RA binding. Our results also suggest that one or more co-activators for STAT5A and/or STAT5B may play important roles in establishing different binding abilities and gene regulation behaviors. The new identification of these genes regulated by STAT5A and/or STAT5B has major implications for understanding the pathophysiology of cancer progression, neural disorders, and immune abnormalities.

TRAIL mRNA expression in peripheral blood mononuclear cells of Egyptian SLE patients

Although the definite etiopathogenesis of systemic lupus erythematosus (SLE) remains unclear, many different mechanisms may contribute to its pathogenesis. Tumor-necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor (TNF) family with pro-apoptotic activity. The accumulation of apoptotic cell debris has been hypothesized to induce the autoimmune inflammation in SLE, and TRAIL may trigger this programmed cell death. We investigated TRAIL mRNA expression levels in peripheral blood mononuclear cells (PBMCs) from 60 SLE patients and 40 controls using quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR), and we studied the association between the results and clinical and laboratory parameters of the patients. Expression levels of TRAIL mRNAs in SLE patients were significantly higher than in controls (p<0.001). A statistically significant association was detected between TRAIL mRNA expression and SLE activity (p=0.001).

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.

Tumor necrosis factor-related apoptosis-inducing ligand is a marker of kidney function and inflammation in heart and kidney transplant recipients

BACKGROUND

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) was originally identified as the third member of the TNF superfamily to induce apoptosis. TRAIL is normally expressed in many human tissues including kidney. Circulating soluble TRAIL is a negative marker for inflammation and is inversely associated with the mortality risk in chronic kidney disease patients. One increasingly prevalent complication in heart transplant recipients appears to be chronic kidney disease.

MATERIALS AND METHODS

The aim of the study was to assess TRAIL concentration in 136 heart transplant recipients and 80 prevalent kidney allograft recipients in relation to kidney function. Complete blood count, urea, serum lipids, fasting glucose, creatinine, NT-proBNP were studied. Soluble TRAIL, hsCR P, interleukin-6 (IL-6), von willebrand factor (vWF) were assayed using commercially available kits.

RESULTS

Heart transplant recipients had significantly higher serum creatinine, urea, cholesterol, triglycerides, fasting glucose, white blood cell count, serum TRAIL and lower estimated glomerular filtration rate than the control group. Similar results were obtained for kidney allograft recipients. Serum TRAIL levels fell, together with decline in glomerular filtration rate in heart transplant patients. Serum TRAIL was related to age, kidney function, erythrocyte count, hemoglobin, NT-proBNP, New York Heart Association class, presence of diabetes, high-density lipoprotein (HDL), IL-6, and ejection fraction. Age and HDL turn out to be predictors of TRAIL in heart transplant recipients. In kidney transplant recipients, TRAIL was related, in univariate analysis, to age, NT-proBNP, time after transplantation, kidney function, and vWF. In multiple regression analysis, predictors of TRAIL were vWF and time after transplantation.

CONCLUSION

TRAIL may represent a surrogate marker of endothelial dysfunction and atherosclerosis as these processes are accelerated in heart and kidney dysfunction.

Idiopathic pneumonia syndrome in mice after allogeneic bone marrow transplantation: association between idiopathic pneumonia syndrome and acute graft-versus-host disease

OBJECTIVE

To explore the association between idiopathic pneumonia syndrome (IPS) and acute graft-versus-host disease (aGVHD) in allogeneic hematopoietic stem cell transplantation.

METHODS

Established acute GVHD model of C57BL/6-->BALB/c mice. Chest computed tomography (CT) scans were dynamically performed in recipient mice after transplant. Lung histopathology and cytokine levels (including TNF-alpha and IFN-gamma) were examined in three experimental groups: mice receiving simple irradiation, syngeneic transplants, and allogeneic transplants.

RESULTS

All allogeneic transplant mice developed aGVHD. On CT, most aGVHD mice had bilateral diffuse lung infiltrates, while syngeneic transplant mice had normal lungs. On histopathology, aGVHD mice had acute pneumonitis. On immunohistochemistry, the infiltrates were mainly CD4+ T cells during aGVHD onset, but CD8+ T cells predominated during aGVHD progression. Lung TNF-alpha and IFN-gamma levels were higher in the three experimental groups than in normal controls on days +3 and +7 post-transplant. On day +7, TNF-alpha levels were higher in allogeneic than in syngeneic transplant mice; IFN-gamma levels were not different. On days +12 and +16, TNF-alpha levels were higher but IFN-gamma levels were lower in allogeneic mice than in syngeneic transplant mice.

CONCLUSIONS

The underlying cause of IPS is aGVHD. T cells and TNF-alpha may play a role in the pathogenesis of aGVHD-induced IPS. IPS progression may be associated with decreasing lung IFN-gamma levels.

Potential prognostic significance of decreased serum levels of TRAIL after acute myocardial infarction

Background

Since soluble TRAIL exhibits anti-inflammatory and anti-atherosclerotic activities both in vitro and in animal models, this study was designed to assess the relationship between the serum levels of TRAIL and clinical outcomes in patients with acute myocardial infarction (AMI).

Methodology/Principal Findings

Levels of TRAIL were measured by ELISA in serial serum samples obtained from 60 patients admitted for AMI, both during hospitalization and in a follow-up of 12 months, as well as in 60 healthy control subjects. Serum levels of TRAIL were significantly decreased in patients with AMI at baseline (within 24 hours from admission), compared with healthy controls, and showed a significant inverse correlation with a series of negative prognostic markers, such as CK, CK-MB and BNP. TRAIL serum levels progressively increased at discharge, but normalized only at 6–12 months after AMI. Of note, low TRAIL levels at the patient discharge were associated with increased incidence of cardiac death and heart failure in the 12-month follow-up, even after adjustment for demographic and clinical risk parameters (hazard ratio [HR] of 0.93 [95% CI, 0.89 to 0.97]; p = 0.001).

Conclusions/Significance

Although the number of patients studied was limited, our findings indicate for the first time that circulating TRAIL might represent an important predictor of cardiovascular events, independent of conventional risk markers.

Gene-expression profiles of peripheral blood mononuclear cell subpopulations in acute graft-vs-host disease following cord blood transplantation

OBJECTIVE

Compared with allogeneic hematopoietic stem cell transplantation using other sources, cord blood (CB) transplantation (CBT) has clinical advantages in terms of incidence and severity of acute graft-vs-host disease (GVHD), despite using allogeneic stem cells with more human leukocyte antigen mismatches. However, detailed pathophysiology of acute GVHD developed after CBT has not yet been elucidated. In this study, we aimed to clarify the molecular mechanism of acute GVHD after CBT.

MATERIALS AND METHODS

We performed microarray expression profiling of immunoregulatory genes on each of four subpopulations (CD4+, CD8+, CD14+, and CD56+) of peripheral blood mononuclear cells (PBMCs), which were taken from eight patients with hematologic malignancies who suffered from acute GVHD after unrelated CBT.

RESULTS

We identified 55 genes, which were differentially expressed during acute GVHD compared to recovery phase. Among them, 22 showed differential expression concurrently in multiple PBMC subpopulations. In particular, five genes (TNFSF10/TRAIL, IL1RN, IFI27, GZMB, and CCR5) were upregulated and three genes (CLK1, TNFAIP3 and BTG1) were downregulated in at least three out of four subpopulations during acute GVHD. In addition, downregulation of antiinflammatory factors, such as TNFAIP3, KLF2, ZFP36, and BTG1, seems to be involved in acceleration of immune response, thus exacerbation of acute GVHD. Meanwhile, differential expression of several genes, such as CCL5, TNFAIP3, KLRB1/CD161, BY55/CD160, and PTGS2/COX2, was assumedly affected by the developmental immaturity of CB-derived cells.

CONCLUSIONS

These results will contribute to the understanding of molecular mechanism underlying the behavior of inflammatory cells during acute GVHD following CBT.