Reduced levels of Hsp70 result in a therapeutic effect of 15-deoxyspergualin on acute graft-versus-host disease in (DA x LEW)F1 rats

Characterization of monocyte subtypes regarding their phenotype and development in the context of graft-versus-host disease

Graft-versus-host disease (GvHD) is a major cause of morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT). In this study, monocyte subtypes were characterized regarding cytokine expression pattern and development in the context of GvHD. Using inflammatory S100 proteins for monocyte stimulation, it could be demonstrated that intermediate monocytes are the main producers of inflammatory cytokines such as IL-6 and TNFα known to be involved in the development of Th17 cells pointing towards an inflammatory phenotype of this monocyte subtype. Furthermore, novel aspects regarding monocyte subtype development were found. Our data reveal that prednisolone promotes the induction of intermediate monocytes from classical monocytes which correlates with HSP70 expression levels. However, 1α,25-Dihydroxyvitamin D3 treatment results in the abrogation of the prednisolone-mediated induction of this inflammatory monocyte subset and low HSP70 expression levels. Treatment of classical monocytes with pifithrin-μ, a specific HSP70 inhibitor, also leads to an inhibited induction of intermediate monocytes in the presence of prednisolone. These data point towards a predominant role of HSP70 in the development of intermediate monocytes. Thus, HSP70 might be a promising target for GvHD therapy, especially in combination with glucocorticoids, in order to decrease intermediate monocyte subset levels.

B-Cell-Based and Soluble Biomarkers in Body Liquids for Predicting Acute/Chronic Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the main curative therapy for hematological malignancy such as leukemias, lymphomas, or multiple myelomas and some other hematological disorders. In this therapy, cure of hematological diseases relies on graft-versus-malignancy effects by allogenic immune cells. However, severe posttransplant treatment-associated complications such as acute graft-versus-host disease (aGvHD) and chronic graft-versus-host disease (cGvHD) limit this approach. Most research into GvHD has concentrated on the aGvHD, while the more complex and multifaceted chronic form has been largely poorly investigated. cGvHD is a multi-organ autoimmune disorder and is the major cause of non-relapse morbidity and mortality following allo-HSCT, occurring in about 50% of patients, or 13,000–15,000 patients per year worldwide. Therefore, there is a high medical need for an early prediction of these therapy-associated toxicities. Biomarkers have gained importance over the last decade in diagnosis, in prognosis, and in prediction of pending diseases or side effects. Biomarkers can be cells, factors isolated from target tissues, or soluble factors that can be detected in body fluids. In this review, we aim to summarize some of the recent developments of biomarkers in the field of allo-HSCT. We will focus on cell-based biomarkers (B-cell subsets) for cGvHD and soluble factors including microRNA (miRNA), which are excreted into serum/plasma and urine. We also discuss the potential role of cytosolic and extracellular 70 kDa heat shock proteins (HSP70) as potential biomarkers for aGvHD and their role in preclinical models. Proteomic biomarkers in the blood have been used as predictors of treatment responses in patients with aGvHD for many years. More recently, miRNAs have been found to serve as a biomarker to diagnose aGvHD in the plasma. Another development relates to urine-based biomarkers that are usually detected by capillary electrophoresis and mass spectrometry. These biomarkers have the potential to predict the development of severe aGvHD (grades III–IV), overall mortality, and the pending development of cGvHD in patients posttransplant.

The role of danger signals and ectonucleotidases in acute graft-versus-host disease

Allogeneic hematopoietic cell transplantation (allo-HCT) represents the only curative treatment approach for many patients with benign or malignant diseases of the hematopoietic system. However, post-transplant morbidity and mortality are significantly increased by the development of acute graft-versus-host disease (GvHD). While alloreactive T cells act as the main cellular mediator of the GvH reaction, recent evidence suggests a critical role of the innate immune system in the early stages of GvHD initiation. Danger-associated molecular patterns released from the intracellular space as well as from the extracellular matrix activate antigen-presenting cells and set pro-inflammatory pathways in motion. This review gives an overview about danger signals representing therapeutic targets with a clinical perspective with a particular focus on extracellular nucleotides and ectonucleotidases.

Elevated level of HSPA1L mRNA correlates with graft-versus-host disease

Graft-versus-host disease (GVHD) can be a fatal complication of allogeneic stem cell transplantation (allo-HSCT). GVHD can be classified as acute (aGVHD: up to 100 days) or chronic (cGVHD: after 100 days) based on the time-point of disease occurrence. At present there are a limited number of biomarkers available for use in the clinic. Thus, the aim of this research was to evaluate the biomarker potential of the extensively studied Heat Shock Protein 70 family members (HSPA1A/HSPA1B and HSPA1L) at the messenger RNA (mRNA) level in acute and cGVHD patient cohorts. In the skin biopsies, HSPA1L mRNA expression was lower in patients with severe aGVHD (grades II-III) when compared to those with none or low grade aGVHD (grades 0-I) and normal controls. In whole blood, HSPA1L mRNA expression level was significantly (p = 0.008) up-regulated at 28 days post-transplant in cGVHD patients with a significant area under the curve (AUC = 0.773). In addition, HSPA1B expression in whole blood was significantly higher at 3 months post-transplant in both the aGVHD grade II-III (p = 0.012) and cGVHD (p = 0.027) patients. Our initial results in this small cohort show that quantifying HSPA1L mRNA expression in the whole blood of allo-HSCT patients at day 28 post-allo-HSCT may be a useful predictive biomarker for cGVHD.

Genomic studies of GVHD-lessons learned thus far

GVHD remains the most significant complication of hematopoietic SCT, despite advances in HLA matching and the identification of risk various factors. To account for the variation in the incidence and severity of this disease, many genetic association studies have been performed in order to explore the role of immunoregulatory gene polymorphisms. These genes include those that encode cytokines, chemokines, and costimulatory molecules. Polymorphisms in other classes of genes such as those involved in drug metabolism, protein folding, and DNA replication have also been studied. In this review, we address the current knowledge of the role of genetic polymorphisms in GVHD. We also discuss the potential pitfalls inherent in genetic association testing and alternative strategies to address these problems.

Immunoregulatory gene polymorphisms and graft-versus-host disease

Graft-versus-host disease (GVHD) remains a significant complication that greatly enhances morbidity and mortality associated with hematopoietic stem cell transplantation. Key immunoregulatory molecules have been implicated in the pathogenesis of GVHD, but the mechanisms by which these molecules affect the incidence and severity of GVHD have not been fully elucidated. The effects of genetic polymorphisms in immunoregulatory molecules, including cytokines, costimulatory and adhesion molecules, pharmacogenes and growth factors, have been shown to play a central role in GVHD. The results of these polymorphism studies contribute to the identification of predictive risk factors for GVHD based on individual polymorphism makeup. This review summarizes investigations of genetic polymorphisms in immunoregulatory molecules significantly associated with GVHD over the last 5 years.

Investigating cellular stress responses--a multidisciplinary approach from basic science to therapeutics--report on the EuroSciCon (European Scientific Conferences) meeting

The meeting on "Investigating cellular stress responses--a multidisciplinary approach from basic science to therapeutics" was held in London on 13 October 2006. The purpose of this 1-day meeting was to bring together European scientists investigating the immune biology of stress proteins and their potential clinical applications. The main topics included: the role of heat shock proteins (Hsps) in bacterial infections; the role of Hsps with a molecular mass of about 70 kDa in cancer therapy and in prediction of the clinical outcome following allogeneic hematopoietic stem cell transplantation; the quality and duration of stress as a danger signal for the initiation of a stress response; the mechanism of Hsp-protein interaction; and Hsp export from tumor cells in secretory granules.

HSP70-hom gene polymorphism in allogeneic hematopoietic stem-cell transplant recipients correlates with the development of acute graft-versus-host disease

BACKGROUND

A number of genetic polymorphisms have been shown to be associated with the outcome after allogeneic hematopoietic stem-cell transplantation (HSCT). In the present study, HSP70-hom polymorphism (+2763 G/A) was analyzed in the patients and donors of allogeneic HSCT in relation to transplantation outcome, susceptibility for generation of severe toxic lesions, and acute (a) graft-versus-host disease (GVHD).

METHODS

One hundred thirty-three recipients of allogeneic hematopoietic stem cells and 64 haploidentical and matched unrelated donors were investigated. All these individuals were typed for dimorphism within the HSP70-hom gene (+2763 G/A) with the use of amplification refractory mutation system technique. RESULTS.: Patients with the HSP-AA homozygous genotype presented more frequently with grade II to IV toxic lesions (12 of 14 vs. 61 of 105, P = 0.039) and aGVHD (12 of 16 vs. 56 of 114, P = 0.045). Conversely, DRB1*11 was associated with a lower risk of aGVHD manifestation (10 of 31 vs. 58 of 99, P = 0.009). These contrary associations of HSP-AA and DRB1*11 with the risk of aGVHD were confirmed using logistic regression modeling in multivariable analysis (HSP-AA, odds ratio [OR] = 3.833, P = 0.004; DRB1*11, OR = 0.224, P = 0.048). None of donor HSP genotypes or patient-donor incompatibility within HSP alleles was associated with susceptibility to toxic complications or aGVHD.

CONCLUSIONS

Polymorphism of the HSP70-hom gene is associated with the development of posttransplant complications. Recipient HSP-AA homozygous genotype is a risk factor for aGVHD.

The molecular basis of salivary gland involvement in graft--vs.--host disease

During the past two decades, the involvement of salivary glands in graft vs. host disease (GVHD) had been intensively researched and published. GVHD occurs in 40-70% of patients treated with bone marrow and peripheral blood stem cell transplantation (PBSCT), and improved survival rates have led to a continuously increasing number of GVHD patients suffering from induced salivary insult. Limited studies suggest that a large percentage of GVHD patients is affected and that the induced salivary dysfunction occurs rapidly following the transplantation. It affects both major and minor salivary glands and reflects the severity of the disease. Moreover, profound sialochemical alterations may be diagnostic of GVHD. An additional reason for this vast research is that GVHD, as an autoimmune-like disease, seemed to be an appropriate model for studying a much more prevalent and well-known and well-studied autoimmune disease involving salivary glands: Sjögren's syndrome. The purpose of the current review-which is, to the best of our knowledge, the first of its kind-is to describe the GVHD-related sialometric and sialochemical data published in the past two decades for both major and minor salivary glands and to discuss the pathogenesis and molecular basis of the disease.

LF15-0195 generates tolerogenic dendritic cells by suppression of NF-kappaB signaling through inhibition of IKK activity

LF15-0195 (LF) is a potent, less toxic analog of the immunosuppressant 15-deoxyspergualine, which we previously reported to prevent graft rejection and to induce permanent tolerance in a murine cardiac transplantation model. However, the underlying mechanism of action of LF required elucidation. In this study, dendritic cells (DC) treated with LF before activation with tumor necrosis factor alpha (TNF-alpha)/lipopolysaccharide (LPS) failed to express maturation markers (major histocompatibility complex II, CD40, CD86) and interleukin-12. LF prevented, in a concentration-dependent manner, the activation and nuclear translocation of nuclear factor-kappaB (NF-kappaB) in DC following addition of TNF-alpha/LPS. Yet-activated and active IkappaB kinases (IKKs) were inhibited in cells pretreated with LF, thereby preventing the phosphorylation of IkappaB and release of NF-kappaB, a key regulator of genes associated with the maturation of DC. LF-induced inhibition of IKK activity was reversed in a dose-dependent manner by the overexpression of IKK. The T helper cell type 2 (Th2) differentiation of naïve T cells promoted by LF-treated DC in vitro correlates with Th2 polarization observed in transplant recipients made tolerant by LF. These data demonstrated that LF-induced blockade of NF-kappaB signaling at the level of IKK promoted the generation of tolerogenic DC that inhibited Th1 polarization and increased Th2 polarization in vitro and in vivo.

In vivo administration of 15-deoxyspergulin inhibits antigen-presenting cell stimulation of T cells and NF-kappaB activation

15-Deoxyspergulin (DSG), a synthetic derivative of spergulin, was initially characterized for its antibiotic and antitumor effects. Recent studies have described the immunosuppressive properties of this molecule, but its mechanism of action is not clearly understood. In the study reported here, mice were treated in vivo with DSG prior to the measurement of IL-2 production and proliferation in an in vitro antigen presentation assay. At suboptimal antigen concentrations, elicited peritoneal macrophages or percoll isolated B cells from DSG-treated mice showed a 50-96% reduction in their ability to present chicken ovalbumin (cOva), cOva peptide, or superantigen (SAg) to MHC class II-matched antigen-specific primary T cells. No significant changes could be found in the cell surface expression of CD80, CD86, MHC I, MHC II, CD18, CD11b, CD40, CD25, and CD54 in antigen-presenting cells (APC) from control or DSG-treated animals. Activation with SAg of macrophages or splenocytes from DSG-treated mice revealed that there was a significant reduction in nuclear NF-kappaB levels compared to cells from untreated animals. Additionally, analysis of cytokines showed that production of TNF-alpha and IL-1beta was inhibited in cultures where macrophages from DSG-mice were used to present cOva to T cells. These results indicate that the effects of DSG in mice are not simply due to altered antigen processing or from any marked changes in cell surface antigen expression. Rather, the immunosuppression may arise from alterations in the release of one or more soluble factor from DSG-treated APC, which prevents effective antigen presentation and T cell activation.

Antibodies to 70 kD and 90 kD heat shock proteins are associated with graft-versus-host disease in peripheral blood stem cell transplant recipients

The development of graft-versus-host disease (GVHD) can be modified by non-MHC factors. Based on our previous studies that showed an involvement of 70kD heat shock protein (hsp70) in the pathology of acute GVHD in a rat model, we determined serum levels of antibodies to hsp70, hsp90 and hsp60 in human recipients after allogeneic peripheral blood stem cell transplantation (PBSCT). Serum levels of these antibodies were correlated with GVHD status in the recipients. Twenty-nine recipients with high-risk haematological malignances, who received G-CSF mobilized allogeneic PBSCT from HLA matched family donors, were evaluated between 30 and 960 days after transplantation. Two recipients had no GVHD, 18 developed acute followed by chronic GVHD and nine developed only chronic GVHD. Patients with acute GVHD had a significant increase in IgM anti-hsp70 and/or anti-hsp90 early (30-90 days) after transplantation. In addition, an increase in IgM anti-hsp70 and/or anti-hsp90 antibodies preceded or accompanied chronic GVHD. Antibody levels returned to normal within the next 400 days in the majority of patients. Anti-hsp60 antibody levels were not different from control levels regardless of GVHD status. This study implies that the development of acute and/or chronic GVHD in humans is accompanied by an increase in anti-hsp70 and anti-hsp90 antibodies. Monitoring levels of anti-hsp70 and anti-hsp90 antibodies in stem cell transplant recipients may serve as a diagnostic tool and help to predict the onset of GVHD.