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

Review of Genetic Variation as a Predictive Biomarker for Chronic Graft-Versus-Host-Disease After Allogeneic Stem Cell Transplantation

Chronic graft-versus-host disease (cGvHD) is one of the major complications of allogeneic stem cell transplantation (HSCT). cGvHD is an autoimmune-like disorder affecting multiple organs and involves a dermatological rash, tissue inflammation and fibrosis. The incidence of cGvHD has been reported to be as high as 30% to 60% and there are currently no reliable tools for predicting the occurrence of cGvHD. There is therefore an important unmet clinical need for predictive biomarkers. The present review summarizes the state of the art for genetic variation as a predictive biomarker for cGvHD. We discuss three different modes of action for genetic variation in transplantation: genetic associations, genetic matching, and pharmacogenetics. The results indicate that currently, there are no genetic polymorphisms or genetic tools that can be reliably used as validated biomarkers for predicting cGvHD. A number of recommendations for future studies can be drawn. The majority of studies to date have been under-powered and included too few patients and genetic markers. Like in all complex multifactorial diseases, large collaborative genome-level studies are now needed to achieve reliable and unbiased results. Some of the candidate genes, in particular, CTLA4, HSPE, IL1R1, CCR6, FGFR1OP, and IL10, and some non-HLA variants in the HLA gene region have been replicated to be associated with cGvHD risk in independent studies. These associations should now be confirmed in large well-characterized cohorts with fine mapping. Some patients develop cGvHD despite very extensive immunosuppression and other treatments, indicating that the current therapeutic regimens may not always be effective enough. Hence, more studies on pharmacogenetics are also required. Moreover, all of these studies should be adjusted for diagnostic and clinical features of cGvHD. We conclude that future studies should focus on modern genome-level tools, such as machine learning, polygenic risk scores and genome-wide association study-transcription meta-analyses, instead of focusing on just single variants. The risk of cGvHD may be related to the summary level of immunogenetic differences, or whole genome histocompatibility between each donor-recipient pair. As the number of genome-wide analyses in HSCT is increasing, we are approaching an era where there will be sufficient data to incorporate these approaches in the near future.

Heat Shock Proteins and their Protective Roles in Stem Cell Biology

Stem cells (SCs) are discovered long back but the idea that SCs possess therapeutic potential came up just a few decades back. In a past decade stem cell therapy is highly emerged and displayed tremendous potential for the treatment of a wide range of diseases and disorders such as blindness and vision impairment, type I diabetes, infertility, HIV, etc. SCs are very susceptible to destruction after transplantation into the host because of the inability to sustain elevated stress conditions inside the damaged tissue/organ. Heat shock proteins (HSPs) are molecular chaperones/stress proteins expressed in response to stress (elevated temperature, harmful chemicals, ischemia, viruses, etc) inside a living cell. HSPs protect the cell from damage by assisting in the proper folding of cellular proteins. This review briefly summarises different types of HSPs, their classification, cellular functions as well as the role of HSPs in regulating SC self-renewal and survival in the transplanted host. Applications of HSP modulated SCs in regenerative medicine and for the treatment of ischemic heart disease, myocardial infarction (MI), osteoarthritis, ischemic stroke, spinocerebellar ataxia type 3 (SCA3), leukemia, hepatic ischemia-reperfusion injury, Graft-versus-host disease (GVHD) and Parkinson's disease (PD) are discussed. In order to provide potential insights in understanding molecular mechanisms related to SCs in vertebrates, correlations between HSPs and SCs in cnidarians and planarians are also reviewed. There is a need to advance research in order to validate the use of HSPs for SC therapy and establish effective treatment strategies.

Anti-heat shock protein 70 levels in gingival crevicular fluid of Japanese patients with chronic periodontitis

Periodontitis is an inflammatory disease involving complex tripartite cross-interactions among bacterial, host and environment factors. Heat shock proteins (Hsps) are a protein family produced in response to stress conditions. Hsps protect cells under adverse circumstances such as infection, inflammation and disease. One of the causes of periodontal disease is thought to be an imbalance in the expression of Hsps and anti-Hsp antibodies. Hsps are classified according to their molecular weight, and one of the major ones is Hsp70. In the present study, enzyme-linked immunosorbent assay was used to measure the levels of anti-Hsp70 antibody in gingival crevicular fluid (GCF) from two gingival sulci in each of nine patients with chronic periodontitis (CP): one healthy control (HC) site with a probing pocket depth (PPD) of ≤3 mm and one CP site with a PPD of >5 mm. Anti-Hsp70 antibody levels in GCF were higher at HC sites than at CP sites. Moreover, the anti-Hsp70 antibody levels were found to increase after initial periodontal therapy at both HC and CP sites. These results suggest an association of anti-Hsp70 antibody with periodontitis.

Antibodies to Heat Shock Proteins 90α and 90β in Psoriasis

One of many hypotheses of psoriasis pathogenesis supposes an overexpression of heat shock proteins (Hsps) in different skin layers and systemic immunologic response to them. Hsp90 is one of the most abundant chaperone in eukaryotic cells. The number of studies concerning the role of Hsp90 and anti-Hsp90 antibodies in etiopathogenesis of various diseases is also constantly expanding. Still, there are not many reports concerning potential involvement of this Hsp family or anti-Hsp90 immunization in pathomechanism of psoriasis. The aim of the study was the estimation of anti-Hsp90α and anti-Hsp90β IgG antibodies in the sera of the psoriatic patients at different phases of disease activity in comparison to the sera of healthy individuals. The study material consisted of sera from psoriasis patients (n = 80) in active phase and in the remission phase and healthy individuals (n = 80). Concentrations of anti-Hsp90α and anti-Hsp90β IgG antibodies were determined using ELISA technique. In the patients with psoriasis (both in the active phase of the disease and in the remission phase) concentrations of anti-Hsp90α antibodies were significantly higher than in healthy individuals and they correlated positively with psoriasis area severity index values. The mean concentrations of anti-Hsp90β antibodies in the psoriatic patients and healthy controls were comparable. The obtained results indicate an existence of increased immunological response to Hsp90α in psoriasis. It may suggest the role of the extracellular form of this chaperone and/or anti-Hsp90α antibodies in etiopathogenesis of this dermatosis. The inhibition of Hsp90α may represent a novel therapeutic approach to treat psoriasis.

Diagnostic, Prognostic, and Therapeutic Value of Non-Coding RNA Expression Profiles in Renal Transplantation

End-stage renal disease is a public health problem responsible for millions of deaths worldwide each year. Although transplantation is the preferred treatment for patients in need of renal replacement therapy, long-term allograft survival remains challenging. Advances in high-throughput methods for large-scale molecular data generation and computational analysis are promising to overcome the current limitations posed by conventional diagnostic and disease classifications post-transplantation. Non-coding RNAs (ncRNAs) are RNA molecules that, despite lacking protein-coding potential, are essential in the regulation of epigenetic, transcriptional, and post-translational mechanisms involved in both health and disease. A large body of evidence suggests that ncRNAs can act as biomarkers of renal injury and graft loss after transplantation. Hence, the focus of this review is to discuss the existing molecular signatures of non-coding transcripts and their value to improve diagnosis, predict the risk of rejection, and guide therapeutic choices post-transplantation.

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.

Danger Signals and Graft-versus-host Disease: Current Understanding and Future Perspectives

Graft-versus-host response after allogeneic hematopoietic stem cell transplantation (allo-HCT) represents one of the most intense inflammatory responses observed in humans. Host conditioning facilitates engraftment of donor cells, but the tissue injury caused from it primes the critical first steps in the development of acute graft-versus-host disease (GVHD). Tissue injuries release pro-inflammatory cytokines (such as TNF-α, IL-1β, and IL-6) through widespread stimulation of pattern recognition receptors (PRRs) by the release of danger stimuli, such as damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs). DAMPs and PAMPs function as potent stimulators for host and donor-derived antigen presenting cells (APCs) that in turn activate and amplify the responses of alloreactive donor T cells. Emerging data also point towards a role for suppression of DAMP induced inflammation by the APCs and donor T cells in mitigating GVHD severity. In this review, we summarize the current understanding on the role of danger stimuli, such as the DAMPs and PAMPs, in GVHD.

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.

Autoantibodies to Heat-Shock Protein, HSPA5, and Epitope Spreading: High-Dose Dexamethasone Therapy Rescues Ovarian Function in Experimental Autoimmune Ovarian Insufficiency Mouse Model

PROBLEM

Role of autoantibodies to heat-shock protein 70 isoform, HSPA5, both alone or in combination with other antigenic peptides in epitope spreading and effect of high-dose dexamethasone to overcome this.

METHOD OF STUDY

Experimental autoimmune premature ovarian insufficiency mouse model generated by immunization with immunodominant epitopes of HSPA5 alone or in combination with other antigenic peptides. Two doses of dexamethasone treatment are given to the latter group. Immunosorbent assay and Western blot analysis were undertaken to detect cross-reactivity. Hormonal estimations, histological evaluation, and fertility studies were performed to assess treatment efficacy.

RESULTS

One of the immunodominant epitopes of HSPA5 led to epitope spreading. Of the two doses, 100 mg was more effective in rescuing fertility.

CONCLUSIONS

We postulate that the shared immunodominant peptide could be included in a peptide array to detect both HSAP5 and HSP90β autoantibodies for early diagnosis or prognosis of aPOI and customized glucocorticoid therapy for such subjects.

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.

Various forms of tissue damage and danger signals following hematopoietic stem-cell transplantation

Hematopoietic stem-cell transplantation (HSCT) is the most potent curative therapy for many malignant and non-malignant disorders. Unfortunately, a major complication of HSCT is graft-versus-host disease (GVHD), which is mediated by tissue damage resulting from the conditioning regimens before the transplantation and the alloreaction of dual immune components (activated donor T-cells and recipient’s antigen-presenting cells). This tissue damage leads to the release of alarmins and the triggering of pathogen-recognition receptors that activate the innate immune system and subsequently the adaptive immune system. Alarmins, which are of endogenous origin, together with the exogenous pathogen-associated molecular patterns (PAMPs) elicit similar responses of danger signals and represent the group of damage-associated molecular patterns (DAMPs). Effector cells of innate and adaptive immunity that are activated by PAMPs or alarmins can secrete other alarmins and amplify the immune responses. These complex interactions and loops between alarmins and PAMPs are particularly potent at inducing and then aggravating the GVHD reaction. In this review, we highlight the role of these tissue damaging molecules and their signaling pathways. Interestingly, some DAMPs and PAMPs are organ specific and GVHD-induced and have been shown to be interesting biomarkers. Some of these molecules may represent potential targets for novel therapeutic approaches.

Microarray analysis of long non-coding RNA expression in human acute rejection biopsy samples following renal transplantation

Rejection is still a major obstacle in long-term allograft survival of renal transplant recipients. Long non‑coding RNAs (lncRNAs) are an important class of pervasive RNAs involved in a variety of biological functions, and which are often found to be differentially expressed between healthy and pathological conditions. The aim of this study was to compare the expression profiles of lncRNAs between samples from acute rejection following kidney transplantation and control samples. Three patients were enrolled, diagnosed by renal biopsy with acute rejection upon kidney transplantation. We used lncRNA microarrays to study the lncRNA expression profiles in the kidney biopsies of these patients and in kidneys from healthy donors. Reverse transcription‑quantitative polymerase chain reaction (RT-qPCR) was used to validate the microarray results. In addition, potential functions of the identified lncRNAs were further explored by searching the UCSC, RNAdb, RefSeq and NRED databases. Five candidate lncRNAs displaying differential expression in acute rejection samples were validated by RT-qPCR. The results were in agreement with the microarray data. Among the identified lncRNAs, certain have been previously identified in relevant conditions, thereby supporting previous evidence, but certain may constitute novel biomarker candidates. This is the first report to date using lncRNA microarrays to identify unique expression signatures of acute rejection in transplant biopsies. Our data indicate that lncRNAs are potentially involved in the pathogenesis of acute rejection. Our results may have important implications in the identification of diagnostic biomarkers, as well as in the understanding and treatment of acute rejection following renal transplantation.

HSPA8/HSC70 chaperone protein: structure, function, and chemical targeting

HSPA8/HSC70 protein is a fascinating chaperone protein. It represents a constitutively expressed, cognate protein of the HSP70 family, which is central in many cellular processes. In particular, its regulatory role in autophagy is decisive. We focused this review on HSC70 structure-function considerations and based on this, we put a particular emphasis on HSC70 targeting by small molecules and peptides in order to develop intervention strategies that deviate some of HSC70 properties for therapeutic purposes. Generating active biomolecules regulating autophagy via its effect on HSC70 can effectively be designed only if we understand the fine relationships between HSC70 structure and functions.

Immune reconstitution and graft-versus-host reactions in rat models of allogeneic hematopoietic cell transplantation

Allogeneic hematopoietic cell transplantation (alloHCT) extends the lives of thousands of patients who would otherwise succumb to hematopoietic malignancies such as leukemias and lymphomas, aplastic anemia, and disorders of the immune system. In alloHCT, different immune cell types mediate beneficial graft-versus-tumor (GvT) effects, regulate detrimental graft-versus-host disease (GvHD), and are required for protection against infections. Today, the “good” (GvT effector cells and memory cells conferring protection) cannot be easily separated from the “bad” (GvHD-causing cells), and alloHCT remains a hazardous medical modality. The transplantation of hematopoietic stem cells into an immunosuppressed patient creates a delicate environment for the reconstitution of donor blood and immune cells in co-existence with host cells. Immunological reconstitution determines to a large extent the immune status of the allo-transplanted host against infections and the recurrence of cancer, and is critical for long-term protection and survival after clinical alloHCT. Animal models continue to be extremely valuable experimental tools that widen our understanding of, for example, the dynamics of post-transplant hematopoiesis and the complexity of immune reconstitution with multiple ways of interaction between host and donor cells. In this review, we discuss the rat as an experimental model of HCT between allogeneic individuals. We summarize our findings on lymphocyte reconstitution in transplanted rats and illustrate the disease pathology of this particular model. We also introduce the rat skin explant assay, a feasible alternative to in vivo transplantation studies. The skin explant assay can be used to elucidate the biology of graft-versus-host reactions, which are known to have a major impact on immune reconstitution, and to perform genome-wide gene expression studies using controlled combinations of minor and major histocompatibility between the donor and the recipient.

Genetics of graft-versus-host disease: the major histocompatibility complex

Graft-versus-host disease (GVHD) is a potentially life-threatening complication of allogeneic hematopoietic cell transplantation. Many genes are presumed to be involved in GVHD, but the best characterized genetic system is that of the human major histocompatibility complex (MHC) located on chromosome 6. Among the hundreds of genes located within the MHC region, the best known and characterized are the classical HLA genes, HLA-A, C, B, DRB1, DQB1, and DPB1. They play a fundamental role in T cell immune responses, and HLA-A, C, and B also function as ligands for the natural killer cell immunoglobulin-like receptors involved in innate immunity. This review highlights the state-of-the art in the field of histocompatibility and immunogenetics of the MHC with respect to genetic risk factors for GVHD.

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.

Patient HSP70-hom TG haplotype is associated with decreased transplant-related mortality and improved survival after sibling HLA-matched hematopoietic stem cell transplantation

Heat shock protein 70-hom (HSP70-hom) plays an important role in protein folding and immune responses. Therefore, HSP70-hom gene polymorphisms may act as important factors in predicting the prognosis of patients receiving allogeneic hematopoietic stem cell transplantation (HSCT). To evaluate the role of HSP70-hom gene polymorphisms in the prognosis of patients receiving sibling human leukocyte antigen (HLA)-matched allogeneic HSCT, the HSP70-hom polymorphisms, T2437C and G2763A, were genotyped in 147 patients receiving sibling HLA-matched allogeneic HSCT. Individual diplotypes were estimated from genotype data of the two HSP70-hom polymorphisms using the expectation maximization algorithm. Patients with the 2763GG or GA genotype showed longer overall survival compared with those with the 2763AA genotype, and patients with a TG haplotype (TG/TA, TG/TG or TG/CG) also showed longer overall survival compared with those with a non-TG haplotype (TA/TA or TA/CG) (both G2763A genotype and diplotype, p<0.01). Moreover, the 2437TT genotype was found to be protective for treatment-related death compared with the 2437TC genotype, and a TG haplotype was found to be very protective for treatment-related death compared with a non-TG haplotype (T2437C genotype, p=0.04; and diplotype, p=0.02). Therefore, our results suggest that HSP70-hom polymorphisms play an important role in the prognosis of patients receiving sibling HLA-matched allogeneic HSCT.

The role of heat shock protein 27 in bronchiolitis obliterans syndrome after lung transplantation

BACKGROUND

Heat shock proteins (Hsps) are a family of evolutionary conserved proteins classified according to their size as small and large Hsps. They have a cytoprotective role and have been shown to be immunogenic molecules. In addition, self-reactivity to Hsps has been implicated in various autoimmune diseases and in the development of alloimmunity. This study examined the relationship of large and small Hsps and anti-Hsp antibodies in lung transplant (LTx) recipients who have bronchiolitis obliterans syndrome (BOS).

METHODS

Anti-Hsp27 and Hsp70 antibodies, and Hsp27, Hsp60, and Hsp70 protein expression levels were evaluated in serum and bronchoalveolar lavage samples collected from 8 LTx recipients with established BOS and 8 recipients without BOS (controls). Serum from 8 healthy individuals was examined for Hsp levels as a comparison.

RESULTS

Elevated serum Hsp27 levels were observed in recipients with BOS compared with controls or healthy individuals, whereas Hsp70 and Hsp60 expression showed no difference. Anti-Hsp27 antibody levels were significantly higher in the BAL of recipients with BOS than in those without BOS. In contrast, anti-Hsp70 antibodies levels in serum or BAL showed no difference between groups.

CONCLUSIONS

These results support the novel concept that Hsp27, but not the classic Hsp60 and Hsp70, may be associated with the development BOS. The expression of anti-Hsp27 antibodies found only in the BAL fluid suggests a local response occurring at the level of the alveoli and terminal airways.

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.

Multidimensional degradomics identifies systemic autoantigens and intracellular matrix proteins as novel gelatinase B/MMP-9 substrates

The action radius of matrix metalloproteinases or MMPs is not restricted to massive extracellular matrix (ECM) degradation, it extends to the proteolysis of numerous secreted and membrane-bound proteins. Although many instances exist in which cells disintegrate, often in conjunction with induction of MMPs, the intracellular MMP substrate repertoire or degradome remains relatively unexplored. We started an unbiased exploration of the proteolytic modification of intracellular proteins by MMPs, using gelatinase B/MMP-9 as a model enzyme. To this end, multidimensional degradomics technology was developed by the integration of broadly available biotechniques. In this way, 100-200 MMP-9 candidate substrates were isolated, of which 69 were identified. Integration of these results with the known biological functions of the substrates revealed many novel MMP-9 substrates from the intracellular matrix (ICM), such as actin, tubulin, gelsolin, moesin, ezrin, Arp2/3 complex subunits, filamin B and stathmin. About 2/3 of the identified candidates were autoantigens described in multiple autoimmune conditions and in cancer (e.g. annexin I, nucleolin, citrate synthase, HMGB1, alpha-enolase, histidyl-tRNA synthetase, HSP27, HSC70, HSP90, snRNP D3). These findings led to the insight that MMPs and other proteases may have novel (immuno)regulatory properties by the clearance of toxic and immunogenic burdens of abundant ICM proteins released after extensive necrosis. In line with the extracellular processing of organ-specific autoantigens, proteolysis might also assist in the generation of immunodominant 'neo-epitopes' from systemic autoantigens. The study of proteolysis of ICM molecules, autoantigens, alarmins and other crucial intracellular molecules may result in the discovery of novel roles for proteolytic modification.

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.

Antibodies to 60, 65 and 70 kDa heat shock proteins in pediatric allogeneic stem cell transplant recipients

Allogeneic SCT remains the only means of cure for many patients with various malignant disorders as well as non-malignant diseases. Infection together with severe aGvHD may result in a significant incidence of transplant-related morbidity and mortality. Current evidence suggests that hSPS represent major immunodominant antigens in many pathogens and therefore might play an important role in the pathogenesis of GvHD. We investigated the levels of total Ig, IgG and IgM isotype antibodies to rh-hsp60, recombinant Mycobacterium bovis hsp65 and stress-inducible rh-hsp70 in sera of pediatric patients undergoing SCT by using ELISA. We studied whether humoral immune responses to hSPS follow transplant-related complications, bacterial and fungal infection. Anti-hsp antibodies were detected in patients' sera before conditioning, over the course of conditioning and all the time post-transplant. We found no correlation between anti-hsp antibodies and the occurrence and severity of GvHD and/or other transplant-related complications like graft failure, hemorrhagic cystitis and capillary leakage syndrome. However, elevated anti-hsp antibodies involving IgM and IgG isotypes were found to be associated with bacterial and fungal infection depending on etiological agents. We demonstrated de novo humoral response to hSPS in a cohort of patients with actual infection caused by Klebsiella pneumoniae (anti-hsp60, anti-hsp65 and anti-hsp70), Pseudomonas aeruginosa (anti-hsp60, anti-hsp70) and Aspergillus fumigatus (anti-hsp65). We conclude that anti-hsp antibodies might be produced after SCT in relation to infection depending on etiological agents; however, transplant-related complications by themselves had a little impact.

Frequency of anti-hsp60, -65 and -70 antibodies in sera of patients with juvenile idiopathic arthritis

Cross-reactivity between microbial and human heat shock proteins (hsps) led to the concept that hsp might be involved in the etiopathogenesis of autoimmune diseases. We investigated antibodies to recombinant human hsp60, recombinant Mycobacterium bovis hsp65 and to stress-inducible recombinant human hsp70 using enzyme-linked immunosorbent assay (ELISA) in sera of 209 juvenile idiopathic arthritis (JIA) patients and 50 healthy controls. Anti-hsp60 antibodies did not exceed the control level in any JIA patient. The numbers of JIA patients (16/209, 7.6%) who raised anti-hsp65 antibodies was equal to healthy controls (4/50, 8%). Elevated levels of antibodies against hsp70 were found in a cohort of patients with JIA (36.8%) when compared with age-matched healthy individuals (2%). These antibodies were predominantly of IgG isotype in systemic disease and IgM isotype in oligoarthritis. In polyarthritis both IgG and IgM antibodies frequently occurred. Significantly higher anti-hsp70 antibody levels were found in RF-positive JIA patients. The levels of anti-hsp70 antibodies correlated with the severity of disease evaluated on the basis of Steinbrocker's functional classification and rtg staging system. No association between anti-hsp70 antibody levels and ANA, HLA B27 and disease duration (less than 2 years x more than 2 years) was observed except IgM anti-hsp70 antibody where significantly higher levels were also detected in HLA B27-positive patients. The prevalence of anti-hsp70 antibodies is much higher in JIA patients when compared with healthy controls, suggesting their possible role in pathological mechanism of the disease.

Antibodies against heat shock proteins in environmental stresses and diseases: friend or foe?

Heat shock proteins (Hsps) can be found in two forms, intracellular and extracellular. The intracellular Hsps are induced as a result of stress and have been found to be cytoprotective in many instances due to their chaperone functions in protein folding and in protein degradation. The origin and role of extracellular Hsps is less clear. Although they were suspected originally to be released from damaged cells (necrosis), their presence in most normal individuals rather suggests that they have regulatory functions in circulation. As immunodominant molecules, Hsps can stimulate the immune system, leading to the production of autoantibodies recognizing epitopes shared by microbial and human Hsps. Thus, extracellular Hsps can influence the inflammatory response as evidenced by the production of inflammatory cytokines. Antibodies to Hsps have been found under normal conditions but seem to be increased in certain stresses and diseases. Such antibodies could regulate the inflammatory response positively or negatively. Here, we review the literature on the findings of antibodies to Hsps in situations of environmental or occupational stress and in a number of diseases and discuss their possible significance for the diagnosis, prognosis, or pathogenesis of these diseases.

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.

Immune restoration following hematopoietic stem cell transplantation: an evolving target

Hematopoietic stem cell transplantation (HSCT) is the definitive cure for many malignant and nonmalignant diseases. However, delays in immune reconstitution (IR) following HSCT significantly limit the success of transplantation and increase the risk for infection and disease relapse in the transplant recipient. Therefore, ways to measure and to manipulate immune recovery following HSCT are emerging and their success depends directly upon an enhanced understanding for the underlying mechanisms responsible for reconstituted immunity and hematopoiesis. Recent discoveries in the activation, function, and regulation of dendritic cell (DC), natural killer (NK) cell, and T-lymphocyte subtypes have been critical in developing immunotherapies used to prevent graft-versus-host disease and to enhance graft-versus-leukemia. For example, regulatory T cells that induce tolerance and NK receptor-tumor ligand disparities that result in tumor lysis are being used to minimize GVHD and tumor burden, respectively. Furthermore, expansion and modulation of immune effector cells are being used to augment hematopoietic and immune recovery and to decrease transplant-related toxicity in the transplant recipient. Specifically, DC expansion and incorporation into antitumor and anti-microbial vaccines is fast approaching application into clinical trials. This paper will review our current understanding for IR following HSCT and the novel ways in which to restore immune function and decrease transplant-related toxicity in the transplant recipient.

Immunological aspects of heat-shock proteins-the optimum stress of life

This review summarizes the complex role of heat-shock proteins (Hsp) in immune reactions, especially the cellular effects of heat-shock proteins during the recognition processes by innate immunity. The role of heat-shock proteins in the pathogenesis of two multifactorial diseases, i.e. inflammatory bowel disease (IBD) and atherosclerosis is highlighted. A new hypothesis on "immunodeficiency burden" is presented. According to this hypothesis, susceptibility to any multifactorial disease in any given subject and in the presence of specific environmental factors is the aggregate effect of polymorphisms resulting in the failure of protective immunity with consequent disease.

Heat shock protein 70: correlation of expression with degree of graft-versus-host response and clinical graft-versus-host disease

BACKGROUND

The heat shock proteins are increasingly becoming associated with immunopathologic phenomena, being induced in response to inflammation. They are highly immunogenic and are postulated as playing a role in both innate and adaptive immunity. Their proposed role in peptide binding and antigen presentation could suggest a potential role in the alloreactive process that leads to graft-versus-host disease (GVHD) after bone marrow transplantation.

METHODS

In this study we examined the expression of the widely studied heat shock protein 70 (hsp70) in an in vitro-generated graft-versus-host reaction in human skin, using streptavidin biotin immunohistochemistry and laser scanning confocal microscopy.

RESULTS

Hsp70 expression was correlated with high graft-versus-host responses (P<0.001) and was confirmed using laser scanning confocal microscopy. Increased expression of hsp70 was further defined due to increases in the inducible form of hsp70. Expression of inducible hsp70 was predictive of both clinical acute GVHD (P=0.001) and incidence of chronic GVHD (P<0.001).

CONCLUSIONS

This investigation has demonstrated for the first time the expression of hsp70 in a human model of GVHD, suggesting involvement in the pathogenesis of the disease and providing the basis for further investigation. Increased expression of inducible hsp70 in the model could provide a biologic marker for the prediction of clinical acute and chronic GVHD.

Type 1 diabetes alters anti-hsp90 autoantibody isotype

The 90-kDa chaperon family includes heat shock protein (hsp) 90 and glucose-regulated protein (grp) 94. These proteins play an important role in normal cellular architecture, in the etiology of some autoimmune and infectious diseases and in antigen presentation to T cells. Owing to its role in autoimmunity, we explored anti-hsp90 autoantibody (hsp90AA) response in the sera of persons with type 1 diabetes, first-degree relatives (FDR) and in normal subjects. Significant high level of hsp90AA was found in FDR, but there was no significant difference between the normal and diabetic persons. The IgG1 and IgG3 isotypes of hsp90AA were higher in persons with type 1 diabetes and FDR than in normal subjects. We found a good correlation between hsp90AA measured by ELISA and RIA. A positive correlation between serum hsp90AA and glutamic acid decarboxylase (GAD65) autoantibody (GAA) was also observed. Hsp90AA positive sera from diabetic persons immunoblotted recombinant hsp90, GAD65 and corresponding proteins in islet lysates. Our study suggests that hsp90AA are present in normal, FDR and diabetic persons. However, there is a higher level of IgG1 and IgG3 isotypes of hsp90AA in FDR and type 1 diabetic subjects. Thus, autoimmunity leading to type 1 diabetes significantly alters the autoantibody isotype to autoantigens, such as hsp90.