Anti-heat shock protein 70 kDa and 90 kDa antibodies in serum of patients with rheumatoid arthritis

HSP90 Exacerbates Bone Destruction in Rheumatoid Arthritis by Activating TRAF6/NFATc1 Signaling

Rheumatoid arthritis (RA) is an autoimmune disease characterized by a notably high disability rate, primarily attributed to cartilage and bone degradation. The involvement of heat shock protein 90 (HSP90) as a molecular chaperone in the inflammatory response of RA has been established, but its role in bone destruction remains uncertain. In the present study, the expression of HSP90 was augmented in osteoclasts induced by the receptor activator of nuclear factor-κB ligand. Additionaly, it was observed that the outcomes revealed a noteworthy inhibition of osteoclast formation and differentation when triptolide was utilized to hinder the expression of HSP90. Furthermore, the positive influence of HSP90 in osteoclast differentiation was substantiated by overexpressing HSP90 in osteoclast precursor cells. Mechanically, HSP90 significantly activated the TNF receptor-associated factor 6 (TRAF6)/Nuclear factor of activated T cells 1 (NFATc1) signaling axis, accompanied by markedly promoting osteoclast differentiation. This effect was consistently observed in the destructive joint of rats with collagen-induced arthritis, where HSP90 effectively activated osteoclasts and contributed to arthritic bone destruction by activating the TRAF6/NFATc1 signaling. Overall, the findings of this study provide compelling evidence that HSP90 exacerbates bone destruction in RA by promoting osteoclast differentiation through the activation of TRAF6/NFATc1 signaling, and interference with HSP90 may be a promising strategy for the discovery of anti-arthritic bone destruction agents.

Plasma heat shock protein 90 levels in patients with spondyloarthritis and their relation to structural changes: a cross-sectional study

Aim: Heat shock protein 90 (Hsp90) is a molecular chaperone regulating immune response. We aimed to assess systemic Hsp90 as a biomarker for spondyloarthritis (SpA). Materials & methods: Total of 80 axial SpA (axSpA) and 22 psoriatic arthritis patients and a corresponding number of age- and sex-matched healthy controls (HC) were included. Plasma Hsp90 levels were measured by ELISA. Results: Hsp90 was significantly increased in axSpA patients compared with HC (median interquartile range: 15.7 [10.5-19.8] vs 8.3 [6.6-11.8] ng/ml, p < 0.001). Moreover, Hsp90 was superior to C-reactive protein in differentiating axSpA (and both radiographic axSpA [r-axSpA] and nonradiographic-axSpA) from HC. Hsp90 levels correlated with bone marrow edema of sacroiliac joints in r-axSpA patients (r = 0.594, p = 0.019). Conclusion: Hsp90 could become a biomarker for active inflammation in r-axSpA, and can better distinguish axSpA patients from healthy subjects than C-reactive protein.

A Novel Bead-Based Immunoassay for the Measurement of Heat Shock Proteins 27 and 70

Heat shock proteins (HSPs) play an essential role in protecting proteins from denaturation and are implicated in diverse pathophysiological conditions like cardiovascular diseases, cancer, infections, and neurodegenerative diseases. Scientific evidence indicates that if HSP expression falls below a certain level, cells become sensitive to oxidative damage that accelerates protein aggregation diseases. On the other hand, persistently enhanced levels of HSP can lead to inflammatory and oncogenic changes. To date, although techniques for measuring HSPs exist, these assays are limited for use in specific sample types or are time consuming. Therefore, in the present study, we developed a single-molecule assay digital ELISA technology (Single Molecule Array—SIMOA) for the measurement of HSPs, which is time effective and can be adapted to measure multiple analytes simultaneously from a single sample. This technique combines two distinct HSP-specific antibodies that recognize different epitopes on the HSP molecule. A recombinant human HSP protein was used as the standard material. The assay performance characteristics were evaluated by repeated testing of samples spiked with HSP peptide at different levels. The limit of detection was 0.16 and 2 ng/mL for HSP27 and HSP70, respectively. The inter- and intra-assay coefficients of variation were less than 20% in all tested conditions for both HSPs. The HSP levels assayed after serial dilution of samples portrayed dilutional linearity (on average 109%, R² = 0.998, p < 0.001, for HSP27 and 93%, R² = 0.994, p < 0.001, for HSP70). A high linear response was also demonstrated with admixtures of plasma exhibiting relatively very low and high levels of HSP70 (R² = 0.982, p < 0.001). Analyte spike recovery varied between 57% and 95%. Moreover, the relative HSP values obtained using Western blotting correlated significantly with HSP values obtained with the newly developed SIMOA assay (r = 0.815, p < 0.001 and r = 0.895, p < 0.001 for HSP70 and HSP27, respectively), indicating that our method is reliable. In conclusion, the assay demonstrates analytical performance for the accurate assessment of HSPs in various sample types and offers the advantage of a huge range of dilution linearity, indicating that samples with HSP concentration highly above the calibration range can be diluted into range without affecting the precision of the assay.

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.

Is Male Rheumatoid Arthritis an Occupational Disease? A Review

Background:

Rheumatoid arthritis (RA) is a systemic, inflammatory disease with an estimated global prevalence of 0.3–1.0%. An unexplained association exists between low formal education and the development of RA independent of smoking. It is established that RA is initiated in the lungs and that various occupations associated with dust, fume and metal inhalation can increase the risk of RA development.

Objective:

The objective of this review is to evaluate published clinical reports related to occupations associated with RA development. We highlight the concept of a “double-hit” phenomenon involving adsorption of toxic metals from cigarette smoke by dust residing in the lung as a result of various work exposures. We discuss the relevant pathophysiological consequences of these inhalational exposures in relation to RA associated autoantibody production.

Method:

A thorough literature search was performed using available databases including Pubmed, Embase, and Cochrane database to cover all relative reports, using combinations of keywords: rheumatoid arthritis, rheumatoid factor, anti-citrullinated peptide antibody silica, dust, fumes, metals, cadmium, cigarette smoking, asbestos, mining, bronchial associated lymphoid tissue, heat shock protein 70, and adsorption.

Conclusion:

We postulate that the inhalation of dust, metals and fumes is a significant trigger factor for RA development in male patients and that male RA should be considered an occupational disease. To the best of our knowledge, this is the first review of occupations as a risk factor for RA in relation to the potential underlying pathophysiology.

The function of myeloid dendritic cells in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease that causes joint pain, inflammation, and loss of function. Disease pathogenesis involves activation and proliferation of autoreactive pro-inflammatory effector T cells. While the details of RA onset and progression remain controversial, dendritic cell (DC) numbers dramatically increase in the synovial joint tissues of RA patients. Based on their key functions as antigen-presenting cells and inducers of T cell differentiation, DCs may play an important role in the initiation of joint inflammation. Myeloid DC contributions are likely central to the development of RA, as they are more efficient at antigen presentation in comparison with their closely related cousins, plasmacytoid DCs. Synovial fluid in the joints of RA patients is enriched with pro-inflammatory cytokines and chemokines, which may stimulate or result from DC activation. Epidemiological evidence indicates that smoking and periodontal infection are major environmental risk factors for RA development. In this review, factors in the synovial environment that contribute to altered myeloid DC functions in RA and the effects of environmental risk factors on myeloid DCs are described.

The Unmysterious Roles of HSP90: Ovarian Pathology and Autoantibodies

The heat shock proteins (HSPs) are a group of evolutionarily conserved proteins with important physiological functions, whose synthesis is enhanced by elevated temperature or other stresses. HSPs show high sequence homology between different species, from bacteria to humans. Despite the significant degree of evolutionary conservation, HSPs are highly immunogenic. Of the several HSPs, HSP90 is an abundant, constitutively expressed chaperone constituting around 1-2% of total cellular protein under non-stress conditions. This protein from even the most distantly related eukaryotes has 50% amino acid identity, and all have more than 40% identity with the Escherichia coli protein. They are immunodominant antigens for many common microbes, and thus their epitopes are recognized by the immune system. As HSPs are overexpressed at sites of acute and chronic inflammation, individuals are likely to be sensitized during the course of a microbial infection encountered during life. This chapter considers the evidence of a role for HSP90 in autoimmune ovarian failure, where autoantibodies to it have been observed in patients, and has been correlated to infertility.

Analysis of serum heat shock protein 70 (HSPA1A) concentrations for diagnosis and disease activity monitoring in patients with rheumatoid arthritis

Heat shock proteins (HSPs) have been repeatedly implicated in the pathogenesis of rheumatoid arthritis (RA). The authors aimed to study applicability of heat shock protein 70 (HSPA1A) serum levels as a diagnostic factor and a severity indicator in patients with RA and to quantify cut-off point that predicts status of RA with highest specificity. A total of 76 patients with RA and 36 healthy adults were studied in this case-control analysis. Patients had a higher HSPA1A level than the control group (0.78 ± 0.13 vs. 0.12 ± 0.02 ng/mL, p = 0.006), irrespective of presence of absence of rheumatoid factor or anti-citrullinated cyclic peptide. Next, diagnostic accuracy of the HSPA1A in diagnosis of RA was evaluated (area under curve 0.71; p < 0.05). HSPA1A predicted status of having RA in levels above 0.42 ng/mL with more than 90 % specificity. In addition to diagnostic value, HSPA1A can distinguish between high disease activity (1.66 ± 0.75 ng/mL) and low (0.49 ± 0.1 ng/mL), moderate (0.52 ± 0.12 ng/mL), or remission phase (0.48 ± 0.11 ng/mL). Moreover, patients in remission still had a higher HSPA1A level compared to normal subject (0.48 ± 0.11 vs. 0.12 ± 0.02 ng/mL, p < 0.05). Our results showed that serum HSPA1A could be implemented as a specific tool to facilitate diagnosis and monitoring disease activity in patients with rheumatoid arthritis.

The danger model approach to the pathogenesis of the rheumatic diseases

The danger model was proposed by Polly Matzinger as complement to the traditional self-non-self- (SNS-) model to explain the immunoreactivity. The danger model proposes a central role of the tissular cells' discomfort as an element to prime the immune response processes in opposition to the traditional SNS-model where foreignness is a prerequisite. However recent insights in the proteomics of diverse tissular cells have revealed that under stressful conditions they have a significant potential to initiate, coordinate, and perpetuate autoimmune processes, in many cases, ruling over the adaptive immune response cells; this ruling potential can also be confirmed by observations in several genetically manipulated animal models. Here, we review the pathogenesis of rheumatic diseases such as systemic lupus erythematous, rheumatoid arthritis, spondyloarthritis including ankylosing spondylitis, psoriasis, and Crohn's disease and provide realistic approaches based on the logic of the danger model. We assume that tissular dysfunction is a prerequisite for chronic autoimmunity and propose two genetically conferred hypothetical roles for the tissular cells causing the disease: (A) the Impaired cell and (B) the paranoid cell. Both roles are not mutually exclusive. Some examples in human disease and in animal models are provided based on current evidence.

Positive or negative involvement of heat shock proteins in multiple sclerosis pathogenesis: an overview

Multiple sclerosis (MS) is the most diffuse chronic inflammatory disease of the central nervous system. Both immune-mediated and neurodegenerative processes apparently play roles in the pathogenesis of this disease. Heat shock proteins (HSPs) are a family of highly evolutionarily conserved proteins; their expression in the nervous system is induced in a variety of pathologic states, including cerebral ischemia, neurodegenerative diseases, epilepsy, and trauma. To date, investigators have observed protective effects of HSPs in a variety of brain disease models (e.g. of Alzheimer disease and Parkinson disease). In contrast, unequivocal data have been obtained for their roles in MS that depend on the HSP family and particularly on their localization (i.e. intracellular or extracellular). This article reviews our current understanding of the involvement of the principal HSP families in MS.

Moesin and stress-induced phosphoprotein-1 are possible sero-diagnostic markers of psoriasis

To identify diagnostic markers for psoriasis vulgaris and psoriatic arthritis, autoantibodies in sera from psoriasis vulgaris and psoriatic arthritis patients were screened by two-dimensional immunoblotting (2D-IB). Based on 2D-IB and MADLI TOF/TOF-MS analyses, eleven proteins each in psoriasis vulgaris and psoriatic arthritis were identified as autoantigens. Furthermore, serum levels of moesin, keratin 17 (K17), annexin A1 (ANXA1), and stress-induced phophoprotein-1 (STIP1), which were detected as autoantigens, were studied by dot blot analysis with psoriasis patients and healthy controls. The levels of moesin and STIP1 were significantly higher in sera from patients with psoriasis vulgaris than in the controls (moesin: P<0.05, STIP1: P<0.005). The area under the curve (AUC) for moesin and STIP1 between patients with psoraisis vulgaris and controls was 0.747 and 0.792, respectively. STIP1 and K17 levels were significantly higher in sera from patients with psoriatic arthritis than in those with psoriasis vulgaris (P<0.05 each). The AUC for STIP1 and K17 between patients with psoriatic arthritis and psoriasis vulgaris was 0.69 and 0.72, respectively. The STIP1 or moesin, CK17 serum level was not correlated with disease activity of psoriasis patients. These data suggest that STIP1 and moesin may be novel and differential sero-diagnostic markers for psoriasis vulgaris and psoriatic arthritis.

IgG and IgA antibody titers against human heat-shock protein (hsp60) in sera of rheumatoid arthritis and osteoarthritis patients

Abstract To learn whether heat-shock proteins (HSP) are involved in the pathogenesis of rheumatoid arthritis (RA), antirecombinant human heat-shock protein 60 (hsp60) IgG and IgA in sera of RA and osteoarthritis (OA) patients were investigated. Only the anti-hsp60 IgG titer of seropositive (RF-positive) patients was found to be elevated. Although RF titers of the sera of seropositive RA patients were increased, there was no correlation between the individual anti-hsp60 IgG titer and the corresponding RF titer. In contrast, all the anti-hsp60 IgA titers of the sera of OA, seronegative RA, and seropositive RA patients were found to be elevated. Among them, only the serum IgA concentration of seropositive RA patients was increased. Thus, it was suggested that the increased anti-hsp60 IgG reflects the pathogenesis of RA and its activity. It was also suggested that the increased anti-hsp60 IgA response reflects an involvement of hsp60 in the pathogenesis of arthritides rather than the pathogenesis of RA.

Differential humoral responses against heat-shock proteins after autologous stem cell transplantation in multiple myeloma

Heat-shock proteins (HSP) are important molecules in the pathogenesis of multiple myeloma (MM). Their blockages by drugs or cellular immune response have been investigated, and a possible association with the presence of oligoclonal bands (OB) has been postulated in patients with MM after allogenic stem cell transplantation. The aim of the present study was to ascertain the serum antibody levels against three HSP (60, 70 and 90) by ELISA in patients with MM in complete remission after autologous stem cell transplantation (ASCT), with or without OB, and compare them with those patients with stable gammopathy of undetermined significance (MGUS) and healthy controls. Our results in samples after ASCT showed no differential levels of anti-HSP according to the presence or absence of the oligoclonal response. However, higher levels of anti-HSP90 were found in patients with stable MGUS in comparison with MM patients (p = 0.004). In the same line, a longer progression-free survival was observed in those patients who presented higher anti-HSP90 levels after ASCT (p = 0.042). These results suggest, for first time, the potential of anti-HSP90 humoral immune response for long-term control of malignant plasma cell disorders.

Epigenetics of autoantigens: new opportunities for therapy of autoimmune diseases

The field of epigenetics requires that traditional divisions between scientific disciplines give way to cross-fertilization of concepts and ideas from different areas of investigation. Such is the case with research in autoimmunity. Recent discoveries of stimuli that induce autoimmunity reveal that epigenetic marks of autoantigens are recognized by autoreactive B and T cell receptors. Thus, insights into the initiation of autoimmunity, its prevention and therapy will arise from understanding the biochemistry, cell biology and microbiology of autoantigen epigenetics. Here, we highlight potential benefits from the inhibition of a histone modifying enzyme and the administration of a phosphorylated, spliceosome-derived peptide, in the treatment of autoimmunity.

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.

Identification of citrullinated hsp90 isoforms as novel autoantigens in rheumatoid arthritis-associated interstitial lung disease

OBJECTIVE

Subsets of patients with rheumatoid arthritis (RA) develop extraarticular complications that include interstitial lung disease (ILD). Because standardized algorithms for identification of RA patients at risk of developing clinically significant ILD are lacking, the purpose of this study was to elucidate unique serologic markers of RA-associated ILD (RA-ILD).

METHODS

Sera from RA patients with ILD and from RA patients without ILD were used to immunoprecipitate citrullinated and uncitrullinated proteins derived from K562 cell extracts. Mass spectrometry was performed to facilitate identification of citrullinated proteins differentially immunoprecipitated by RA-ILD patient sera. These candidate proteins were then used as substrate antigens in custom enzyme-linked immunosorbent assays (ELISAs) for high-throughput screening of sera obtained from cohorts of patients with RA, RA-ILD mixed connective tissue disease (MCTD), or idiopathic pulmonary fibrosis (IPF).

RESULTS

Differential immunoprecipitation and subsequent mass spectrometric sequencing identified citrullinated Hsp90α and citrullinated Hsp90β as candidate autoantigens in patients with RA-ILD. ELISAs incorporating uncitrullinated and citrullinated isoforms of Hsp90 as substrate antigens demonstrated that sera from patients with RA-ILD preferentially recognized citrullinated versions of Hsp90 with moderate sensitivity (range 20-30%) and great specificity (>95%) relative to sera derived from patients with RA alone (without ILD), patients with MCTD, or patients with IPF.

CONCLUSION

These studies demonstrate the utility of a novel autoantigen discovery method based on differential immunoprecipitation of citrullinated protein extracts. Application of these techniques identified citrullinated versions of Hsp90α and Hsp90β as autoantibody targets distinguishing RA-ILD from RA without ILD, MCTD, and IPF, suggesting that anti-citrullinated Hsp90α/β autoantibodies may serve as effective biomarkers for the potentially devastating pulmonary manifestations of RA-ILD.

Hyperlipidemic versus normal-lipid acute necrotic pancreatitis: proteomic analysis using an animal model

OBJECTIVES

Hyperlipidemia is associated with a variety of pancreatic diseases. However, the underlying pathophysiology and molecular mechanisms between hyperlipidemia and acute pancreatitis remain undefined. Gel electrophoresis and mass spectrometry can be used in proteomic analysis to elucidate these mechanisms.

METHODS

A comparative proteomic analysis was conducted to identify proteins that were altered in pancreases of hyperlipidemic acute necrotic pancreatitis rats compared with those of normal-lipid acute necrotic pancreatitis rats. A comparative proteomic approach using a hyperlipidemic rat model was used.

RESULTS

Thirty-nine differentially expressed proteins were significantly changed in pancreatic samples from hyperlipidemic acute necrotic pancreatitis rats. Differentially expressed proteins in hyperlipidemic pancreatitis include pancreatic proteolytic enzymes, such as lipase, amylase, carboxypolypeptidase, and α-1-antiproteinase; endoplasmic reticulum stress-related proteins; and calcium influx-related proteins including protein disulfide isomerase, calreticulin, annexin A, glucose-regulated protein 78, heat shock protein 60, and peroxiredoxin. Other proteins associated with DNA replication and damage repair, apoptosis, cell metabolism, circulatory dysfunction, and signal transduction were identified in hyperlipidemic pancreatitis.

CONCLUSIONS

Hyperlipidemia intensifies acute necrotic pancreatitis through various ways. These enzymes may be putative biomarkers of hyperlipidemic acute necrotic pancreatitis.

Increased concentrations of antibody against heat shock protein in patients with myeloperoxidase anti-neutrophil cytoplasmic autoantibody positive microscopic polyangiitis

To determine serum antibody against human and bacterial heat shock protein (HSP) 60/70 in myeloperoxidase (MPO)-specific anti-neutrophil cytoplasmic autoantibody (ANCA) positive microscopic polyangiitis (MPA), 58 patients with MPO-ANCA positive MPA, 48 with RA (rheumatoid arthritis) and 40 with SLE (systemic lupus erythematosus) were studied. Serum antibodies against HSP (human HSP 70, human HSP 60, Mycobacterium HSP 70, and Escherichia coli HSP 60) were measured by sandwich ELISA. The frequency of anti-human HSP 60/70 antibody positive patients was significantly greater in MPO-ANCA positive MPA than SLE and healthy controls. Anti-human HSP 60/70 antibody titers in patients with MPO-ANCA positive MPA were significantly higher than those of healthy controls; anti-bacterial HSP 60/70 antibody titers were also higher. There was a significant correlation between titers of anti-human HSP 70 antibody and anti-Mycobacterium HSP 70 antibody. A correlation was also found between titers of anti-human HSP 70 antibody and anti-human HSP 60 antibody. Anti-human and bacterial HSP 60/70 antibody titers changed in parallel with disease activity in patients with antibody positive MPA. The anti-HSP antibody titer was also increased in patients with RA and SLE. These results suggest that an immunological background via anti-HSP 60/70 antibodies might be associated with pathogenesis in MPO-ANCA positive MPA.

Coexposure to mercury increases immunotoxicity of trichloroethylene

We have shown previously that chronic (32 weeks) exposure to occupationally relevant concentrations of the environmental pollutant trichloroethylene (TCE) induced autoimmune hepatitis (AIH) in autoimmune-prone MRL+/+ mice. In real-life, individuals are never exposed to only one chemical such as TCE. However, very little is known about the effects of chemical mixtures on the immune system. The current study examined whether coexposure to another known immunotoxicant, mercuric chloride (HgCl(2)), altered TCE-induced AIH. Female MRL+/+ mice were treated for only 8 weeks with TCE (9.9 or 186.9 mg/kg/day in drinking water) and/or HgCl(2) (260 μg/kg/day, sc). Unlike mice exposed to either TCE or HgCl(2) alone, mice exposed to both toxicants for 8 weeks developed significant liver pathology commensurate with early stages of AIH. Disease development in the coexposed mice was accompanied by a unique pattern of anti-liver and anti-brain antibodies that recognized, among others, a protein of approximately 90 kDa. Subsequent immunoblotting showed that sera from the coexposed mice contained antibodies specific for heat shock proteins, a chaperone protein targeted by antibodies in patients with AIH. Thus, although TCE can promote autoimmune disease following chronic exposure, a shorter exposure to a binary mixture of TCE and HgCl(2) accelerated disease development. Coexposure to TCE and HgCl(2) also generated a unique liver-specific antibody response not found in mice exposed to a single toxicant. This finding stresses the importance of including mixtures in assessments of chemical immunotoxicity.

Anti-HSP90 autoantibodies in sera of infertile women identify a dominant, conserved epitope EP6 (380-389) of HSP90 beta protein

BACKGROUND

We earlier reported a simple specific test for detection of anti-ovarian antibodies in infertile women and identified number of specific molecular and cellular targets of which human heat shock protein 90-beta (HSP90 beta) was found to be the most immunodominant. The present study focuses on prediction and validation of the immunodominant epitope/s of this protein using sera from infertile women having anti-HSP90 autoantibodies.

METHODS

Delineation of the immunodominant epitopes of HSP90 beta was done by using epitope prediction algorithms and 10 peptides (EP1-EP10) were custom synthesized. Their immunoreactivity was measured by ELISA using sera from patients and controls. To determine the most immunodominant epitope, the results were subjected to statistical analysis. The immunoreactivity of the immunodominant peptides were confirmed by dot blots using sera from patients. A rabbit polyclonal antibody against the immunodominant epitope was generated and its immunoreactivity to the parent protein in ovarian extracts as well in oocytes and embryos was investigated.

RESULTS

Experimentally and statistically, peptide EP6 (380-389) seems to be the major antigenic epitope for the serum antibody binding followed by EP1 (1-12) and EP8 (488-498). Predicted 3D structures of these peptides demonstrated that they exist in the loop conformation which is the most mobile part of the protein. Also, analysis of the sequences of HSP90 beta across several species reveals that EP6 peptide forms a part of a well conserved motif. The polyclonal antibody generated to the immunodominant epitope- EP6 confirms similar biochemical and cellular immunoreactivity as seen with the patients' sera having anti-HSP90 autoantibodies.

CONCLUSIONS

The decapeptide EP6 is a major immunogenic epitope of HSP90 followed by EP1 and EP8. Knowledge of binding epitopes on the autoantigen is necessary to understand the subsequent pathologic events. The study might generate new tools for the detection of disease-inducing epitopes and a possible therapeutic intervention.

The auto-antigen repertoire in myasthenia gravis

Myasthenia Gravis (MG) is an antibody-mediated autoimmune disorder affecting the postsynaptic membrane of the neuromuscular junction (NMJ). MG is characterized by an impaired signal transmission between the motor neuron and the skeletal muscle cell, caused by auto-antibodies directed against NMJ proteins. The auto-antibodies target the nicotinic acetylcholine receptor (nAChR) in about 90% of MG patients. In approximately 5% of MG patients, the muscle specific kinase (MuSK) is the auto-antigen. In the remaining 5% of MG patients, however, antibodies against the nAChR or MuSK are not detectable (idiopathic MG, iMG). Although only the anti-nAChR and anti-MuSK auto-antibodies have been demonstrated to be pathogenic, several other antibodies recognizing self-antigens can also be found in MG patients. Various auto-antibodies associated with thymic abnormalities have been reported, as well as many non-MG-specific auto-antibodies. However, their contribution to the cause, pathology and severity of the disease is still poorly understood. Here, we comprehensively review the reported auto-antibodies in MG patients and discuss their role in the pathology of this autoimmune disease.

Genome-wide gene-based analysis of rheumatoid arthritis-associated interaction with PTPN22 and HLA-DRB1

The genes PTPN22 and HLA-DRB1 have been found by a number of studies to confer an increased risk for rheumatoid arthritis (RA), which indicates that both genes play an important role in RA etiology. It is believed that they not only have strong association with RA individually, but also interact with other related genes that have not been found to have predisposing RA mutations. In this paper, we conduct genome-wide searches for RA-associated gene-gene interactions that involve PTPN22 or HLA-DRB1 using the Genetic Analysis Workshop 16 Problem 1 data from the North American Rheumatoid Arthritis Consortium. MGC13017, HSPCAL3, MIA, PTPNS1L, and IGLVI-70, which showed association with RA in previous studies, have been confirmed in our analysis.

The involvement of heat-shock proteins in the pathogenesis of autoimmune arthritis: a critical appraisal

OBJECTIVES

To review the literature on the role of heat-shock proteins (HSPs) in the pathogenesis of autoimmune arthritis in animal models and patients with rheumatoid arthritis (RA).

METHODS

The published literature in Medline (PubMed), including our published work on the cell-mediated as well as humoral immune response to various HSPs, was reviewed. Studies in the preclinical animal models of arthritis as well as RA were examined critically and the data are presented.

RESULTS

In experimental arthritis, disease induction by different arthritogenic stimuli, including an adjuvant, led to immune response to mycobacterial HSP65 (BHSP65). However, attempts to induce arthritis by a purified HSP have not met with success. There are several reports of a significant immune response to HSP65 in RA patients. However, the issue of cause and effect is difficult to address. Nevertheless, several studies in animal models and a couple of clinical trials in RA patients have shown the beneficial effect of HSPs against autoimmune arthritis.

CONCLUSIONS

There is a clear association between immune response to HSPs, particularly HSP65, and the initiation and propagation of autoimmune arthritis in experimental models. The correlation is relatively less convincing in RA patients. In both cases, the ability of HSPs to modulate arthritis offers support, albeit an indirect one, for the involvement of these antigens in the disease process.

Heat shock protein and apoptosis in supraspinatus tendinopathy

Heat shock proteins (HSPs) are often upregulated following oxidative and other forms of stress. Based on reports of excessive apoptosis in torn supraspinatus tendon and mechanically loaded tendon cells, we hypothesized heat shock proteins may be present in rodent and human models of tendinopathy due to their central role in caspase dependent apoptotic cell signaling. We used a running rat supraspinatus tendinopathy overuse model with custom microarrays to investigate the process at a genetic level. Additionally torn supraspinatus tendon and matched intact subscapularis tendon samples were collected from patients undergoing arthroscopic shoulder surgery. Control samples of subscapularis tendon were collected from 10 patients undergoing arthroscopic stabilization surgery and evaluated using semiquantative RT-PCR and immunohistochemistry. We identified substantial upregulation of heat shock proteins and apoptotic genes in the rodent model. We further confirmed increased levels of heat shock protein and apoptotic regulatory genes in human supraspinatus and subscapularis tendon. This finding suggests heat shock proteins play a role in the cascade of stress-activated programmed cell death and degeneration in tendinopathy and may provide a novel target in preventing tendinopathies.

Extracellular heat shock protein 70 inhibits tumour necrosis factor-alpha induced proinflammatory mediator production in fibroblast-like synoviocytes

Introduction

It was recently suggested that heat shock protein (HSP)70, an intracellular protein, is a potential mediator of inflammatory disease when it is released into the extracellular compartment. Although elevated HSP70 levels have been identified in rheumatoid arthritis (RA) synovial tissues and RA synovial fluid compared with patients with osteoarthritis and healthy individuals, it remains unclear what role extracellular HSP70 plays in the pathogenesis of RA. This study was conducted to investigate the effects of extracellular HSP70 on the production of RA-associated cytokines in fibroblast-like synoviocytes from patients with RA and to elucidate the mechanisms involved.

Methods

IL-6, IL-8 and monocyte chemoattractant protein (MCP)-1 levels in culture supernatants were measured using enzyme-linked immunosorbent assays. Activation of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated protein kinases (ERKs), c-Jun amino-terminal kinase (JNK) and p38 MAPK, was detected using Western blotting. Nuclear translocation of nuclear factor-κB (NF-κB) and degradation of the inhibitory protein IκBα were examined using immunohistochemistry and Western blotting.

Results

Human HSP70 downregulated IL-6, IL-8 and MCP-1 production in RA fibroblast-like synoviocytes induced by tumour necrosis factor (TNF)-α in a concentration dependent manner. HSP70 inhibited the activation of ERK, JNK and p38 MAPK in fibroblast-like synoviocytes stimulated by TNF-α. Furthermore, HSP70 also significantly inhibited nuclear translocation of nuclear factor-κB and degradation of IκBα induced by TNF-α.

Conclusion

Extracellular HSP70 has an anti-inflammatory effect on RA by downregulating production of IL-6, IL-8 and MCP-1 in fibroblast-like synoviocytes, which is mediated through inhibited activation of the MAPKs and NF-κB signal pathways.

Prevalence and clinical significance of anticardiolipin, anti-beta2-glycoprotein-1, and anti-heat shock protein-70 autoantibodies in sudden sensorineural hearing loss

Sudden sensorineural hearing loss (SSNHL) is frequently classified as 'idiopathic' since the causative factor responsible for its onset is not identified in most cases. In the present study, we determined whether SSNHL is clinically associated with serum anti-heat shock protein-70 (anti-HSP70) and antiphospholipids (anti-PLs) autoantibodies and whether these autoantibodies have an impact on the prognosis of SSNHL. Sera from 63 patients with SSNHL were screened prospectively for the presence of anti-HSP70 and anti-PLs autoantibodies by an enzyme-linked immunosorbent assay test. Anti-PLs antibodies in this study consisted of anticardiolipin, and anti-beta(2)-glycoprotein-1 antibodies. Serum was assayed for anti-HSP70 IgG antibodies using recombinant human HSP70. Demographic, clinical, and audiometric variables were analyzed to find the possible role of serum autoantibodies in SSNHL patients. Sixteen patients (25.4%) had demonstrable anti-HSP70 antibodies in serum. Twenty-one patients (33.3%) showed a positive result for at least one isotype (IgM or IgG) of anti-PLs. In 19% of the patients, anti-HSP70 and anti-PLs antibodies were positive in two combinations. A statistically significant association was found between anti-HSP70 antibodies and the Siegel recovery grade subgroup. SSNHL patients who were positive for anti-HSP70 antibodies showed a significantly higher rate of complete recovery and incomplete but partial recovery than SSNHL patients without anti-HSP70 antibodies (p = 0.0496). Statistically significant association was found between total anticardiolipin, total anti-beta(2)-glycoprotein-1, total anti-PLs, and anti-PLs in combination with anti-HSP70 antibodies and age (p = 0.0229). The detection of autoantibodies to HSP70 and PLs offers a pliable explanation for the immune-mediated mechanism of SSNHL. The present study confirms and supports previous studies regarding the association between anti-HSP70 and anti-PLs antibodies with SSNHL, and is the first to identify a positive association between anti-HSP70 antibodies and a positive outcome of SSNHL. Further studies are necessary in order to identify and further clarify the immunologic role of the presence of autoantibodies and their impact on the prognosis of SSNHL.

The clinical significance of anti-heat shock cognate protein 71 antibody in myasthenia gravis

Anti-heat shock cognate protein 71 antibody (HSC71 Ab) formation in the sera of myasthenia gravis (MG) patients was measured, and the correlation between HSC71 Ab titers, clinical features and therapy efficacies for MG patients were examined. Clinical evaluations were performed according to the MG Foundation of America (MGFA) clinical classification. Therapy efficacies were measured using the MG activities of daily living (MG-ADL) score. Before treatment, 38 out of 48 serum samples (79%) from MG patients showed positive HSC71 Ab titers. In the "therapy-responsive group", HSC71 Ab titers significantly reduced, along with patient clinical improvements. Conversely, in the "therapy-resistant group", HSC71 Ab titers did not decline. The use of tacrolimus resulted in improvement in clinical manifestations together with a reduction in HSC71 Ab titers in the "therapy-resistant group". Thus, measurement of HSC71 Ab in the sera of MG patients seemed useful, as it appeared to reflect the effectiveness of treatment and allowed prediction of prognosis.

The immunosuppressive and protective ability of glucose-regulated protein 78 for improvement of alloimmunity in beta cell transplantation

An insulinoma cell line, NIT-1, transfected with glucose-regulated protein 78 (GRP78) was established, namely NIT-GRP78, and used to study the immunosuppressive and protective ability of GRP78. In extended cytotoxic T lymphocyte (CTL) killing assay, NIT-1-primed lymphocytes were more cytotoxic in killing beta cells than NIT-GRP78-primed lymphocytes. Severe necrosis was observed only when the NIT-1-primed lymphocytes were cultured with NIT-1 beta cells, but not with NIT-GRP78 cells. In addition, an increase of interleukin (IL)-4 secretion from beta cell-primed splenocytes when GRP78 presence was observed in cytokine enzyme-linked immunosorbent assay (ELISA). Diabetic mice reached normoglycaemia promptly and gained weight after transplantation of either NIT-1 or NIT-GRP78 cells. However, the recipient mice transplanted with NIT-GRP78 cells lived much longer than those recipients transplanted with NIT-1 cells, which was due apparently to prolonged insulin production by the transplanted NIT-GRP78 cells. In fact, we observed a significant increase of insulin concentration after glucose stimulation of diabetic mice received NIT-GRP78 cells at day 7 post-transplantation. From the results we propose that GRP78 could have a dual function in both protecting NIT-1 cells from CTL-mediated lysis and stimulating a population of T helper 2 cells to down-regulate the immune response to the transplanted beta cells.

Heat shock proteins and autoimmunity in patients with carotid atherosclerosis

Studies aimed at elucidating the pathogenetic mechanisms underlying the initiation and progression of human atherosclerosis have emphasized the central role of inflammatory and immune cells. Atherosclerotic plaques are infiltrated by activated macrophages, T and B lymphocytes, plasma cells, and mast cells, releasing inflammatory molecules, which amplify the severity of the disease. Endothelial cells subjected to various stress conditions express increased amounts of heat shock proteins (HSPs), some of the most successfully conserved proteins throughout evolution. Many experimental observations reviewed in this article draw attention to several HSPs targeted by a specific cellular and humoral immune response in patients with atherosclerotic disease. The review also reports preliminary data obtained by our group on the possible role of HSP90 as a candidate autoantigen in carotid atherosclerosis. Our study deals with the presence of specific antibodies and T cells directed against HSP90 in patients with carotid atherosclerotic plaques. In 60% of these subjects' sera but in none of the sera from healthy controls immunoblotting (IB) detected the presence of specific antibodies. Moreover, 20% of peripheral blood mononuclear cells (PBMC) samples from patients but none from healthy subjects proliferated in response to human purified HSP90. In vitro experiments showed an upregulation of HSP90 expression in endothelial cells exposed to oxidative stress by treatment with H(2)O(2) and greater release of soluble HSP90 in culture supernatants from H(2)O(2)-treated cells than from untreated cells.

Heat-Shock Protein 65 Autoantibodies Are Differently Associated with Early Atherosclerosis in Rheumatoid Arthritis and in Healthy Subjects

The aim of this study was to examine whether heat-shock protein (HSP)-65 autoantibodies are associated with early atherosclerosis in rheumatoid arthritis (RA). Intima-media thickness (IMT) was measured in the carotid arteries of 100 RA patients and 69 control subjects. The IMT was evaluated on both carotid arteries in the common carotid, bifurcation, and internal arteries. Every patient underwent anti-HSP-65 antibody evaluation. Anti-HSP-65 antibodies were not more prevalent among patients compared with controls. Among controls, patients having "positive" anti-HSP-65 tended to have increased carotid artery IMT compared with "negative" patients, whereas among RA patients the opposite association was noted, and positive patients had significantly decreased carotid bifurcation IMT than negative patients without elevated levels of anti-HSP-65. As opposed to the association with cardiovascular diseases and atherosclerosis of anti-HSPs in the general population, among RA patients anti-HSP-65 cannot be regarded as associated with early atherosclerosis.

Heat shock protein 70 membrane expression on fibroblast-like synovial cells derived from synovial tissue of patients with rheumatoid and juvenile idiopathic arthritis

OBJECTIVE

To screen fibroblast-like synovial cells derived from synovial tissue of rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA) patients for the membrane expression of the heat shock protein Hsp70.

METHODS

We performed flow cytometric (fluorescence-activated cell sorting, or FACS) analysis on fibroblast-like synovial cells of 15 RA patients and three JIA patients to investigate Hsp70 membrane expression. Skin fibroblasts derived from the operation wound (n = 4) and peripheral blood mononuclear cells (PBMC) of seven RA and three JIA patients were also tested. Peripheral blood lymphocytes (PBL) and skin fibroblasts of 10 healthy individuals were used as negative controls.

RESULTS

A significantly higher percentage of Hsp70 membrane expression was found on fibroblast-like synovial cells derived from arthritis-affected joints in RA patients (mean 47.7%) when compared with autologous skin fibroblasts (mean 9.5%, p < 0.001) and control skin fibroblasts (mean 5.6%, p < 0.001) or autologous PBL (mean CD45/Hsp70-positive 10.4%, p < 0.001) and control PBL (mean CD45/Hsp70-positive 7.7%, p < 0.001). A high percentage of Hsp70 membrane expression was also observed on fibroblast-like synovial cells derived from three patients with JIA (mean 35.2%) when compared with autologous PBL (mean CD45/Hsp70-positive 10.4%). Synovial cells derived from non-affected joints in a patient with RA who underwent synovectomy for trauma showed low expression of Hsp70 (10.9%).

CONCLUSION

Fibroblast-like synovial cells derived from patients with severe course of RA and JIA are strongly positive for membrane-expressed Hsp70.

Strain differences and the role for HSP47 and HSP70 in adjuvant arthritis in rats

Because of high sequence homology between microbial and endogenous heat shock proteins (HSP), immunological cross-reactivity to microbial HSP has been suggested as a possible cause of the development of autoimmune diseases, such as rheumatoid arthritis. The present study aimed to determine a potential role of HSP47, a molecular chaperone involved in the synthesis and assembly of collagen molecules, and microbial HSP71 (mHSP71) in adjuvant arthritis (AA) in two rat strains: Dark Agouti (DA), susceptible to AA induction and Albino Oxford (AO), which is resistant to AA induction. Immunization with complete Freund's adjuvant (CFA) induced an increased expression of HSP47 in joints of DA rats, which exhibited severe clinical signs of AA at the time of disease peak, while this protein was not detectable in joints of AO rats. In contrast, no strain differences in HSP72 (rat analogue of mHSP71) expressions in joints were observed. The increased levels of anti-HSP47 antibodies were detected in sera of DA rats during the AA peak, while the immunization with CFA increased levels of anti-mHSP71 antibodies in sera of AO rats. HSP47 and mHSP71 reduced proliferation of draining inguinal lymph node cells (LNC) in resistant AO rat strain, leading to a hypothesis that both HSP participated in AA control. Finally, mHSP71 potentiated the apoptotic response of LNC in susceptible DA rat strain. In conclusion, our findings indicate involvement of HSP47 in the development of AA in the rat, and point out to the regulatory role for both HSP47 and mHSP71.

Detection of anti-heat shock protein 90 beta (Hsp90beta) antibodies in cerebrospinal fluid

Antibodies against heat shock protein 90 beta (Hsp90beta) recognize the antigen on the cell surface of the oligodendrocyte precursor cells and cause a decrease of oligodendrocyte population in cell cultures. These antibodies have been found in patients with multiple sclerosis (MS). This report describes an original and sensitive method to detect anti-Hsp90beta antibodies in cerebrospinal fluid (CSF) using a western blot procedure. We have developed the method for autoantibody detection using Hsp90beta from cell membrane fraction instead of commercial Hsp90beta as antigen. The presence of anti-Hsp90beta antibodies in CSF of MS patients may play a pathogenic role in MS, and a large-scale study is needed to establish a possible diagnostic value of these antibodies in MS patients.

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.

Anti-heat shock protein 90 is increased in acute mania

OBJECTIVE

The aim of this work was to examine autoantibodies in patients with bipolar disorder.

METHOD

We enrolled 94 patients with acute bipolar mania, with 37 of them medicated and 57 unmedicated at the time of blood sampling. The samples also consisted of 44 patients in the remission state and another 48 normal controls. We first used human glioblastoma (U373 MG) cell lysate to screen the potential autoantibodies present in sera of bipolar mania patients, and anti-heat shock protein (anti-HSP) 60, 70 and 90 autoantibodies were identified. We then examined the serum levels of these autoantibodies by enzyme-linked immunosorbent assay.

RESULTS

The findings of this study showed that serum anti-HSP90 level was significantly higher in bipolar patients in acute mania than those in remission (p = 0.002).

CONCLUSIONS

The data of this study suggest that increased anti-HSP90 might be a state marker for acute mania in patients with bipolar disorder.

Antibrain antibodies in children with autism and their unaffected siblings

Serum autoantibodies to human brain, identified by ELISA and Western immunoblotting, were evaluated in 29 children with autism spectrum disorder (22 with autistic disorder), 9 non-autistic siblings and 13 controls. More autistic subjects than controls had bands at 100 kDa in caudate, putamen and prefrontal cortex (p<0.01) as well as larger peak heights of bands at 73 kDa in the cerebellum and cingulate gyrus. Both autistic disorder subjects and their matched non-autistic siblings had denser bands (peak height and/or area under the curve) at 73 kDa in the cerebellum and cingulate gyrus than did controls (p<0.01). Results suggest that children with autistic disorder and their siblings exhibit differences compared to controls in autoimmune reactivity to specific epitopes located in distinct brain regions.

Detection of antibodies against 60-, 65- and 70-kDa heat shock proteins in paediatric patients with various disorders using Western blotting and ELISA

BACKGROUND

We examined antibodies against 60-, 65- and 70-kDa heat shock proteins (HSPs) in paediatric healthy individuals, patients with juvenile idiopathic arthritis (JIA) and those undergoing allogeneic stem-cell transplantation for various malignant and non-malignant diseases.

METHODS

Western blotting and ELISA were used to examine HSP-directed humoral immune responses.

RESULTS

Using ELISA we detected anti-Hsp60, -Hsp65 and -Hsp70 IgG antibodies in patient sera before, during and after conditioning and at all post-transplant times, as well as in JIA patients and controls. Western blotting showed positivity for anti-Hsp60 and anti-Hsp65 antibodies in all samples with a HSP concentration of 0.5 microg/lane. However, anti-Hsp70 antibodies were not detected at all when both sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE were used, except for one JIA patient, for whom a positive signal was only achieved in native PAGE when Hsp70 was increased to 2 microg/lane and serum dilution decreased to 1:10.

CONCLUSION

Western blotting is convenient for the detection of anti-Hsp60 and anti-Hsp65 antibodies, but it is not sensitive enough for the detection of anti-Hsp70 antibodies. ELISA, which is more sensitive, might be preferentially used to screen anti-Hsp60, -Hsp65 and -Hsp70 antibodies in sera of children with various disorders.

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.

Comparison of two ELISAs for the determination of Hsp70 in serum

We have compared a previously developed in-house Sandwich-ELISA with a commercial kit for the determination of heat shock protein (Hsp) 70 in serum. Samples from 64 participants were tested and there was a significant correlation between results obtained using the two assays (r = 0.807, p < 0.0001). Additionally, when ranking samples on a categorical scale, the agreement was good (72%). In the commercial test system Hsp70 was detectable in 42 (66%) of the sera, compared with 61 (95%) in the in-house ELISA method. The three samples with undetectable levels of Hsp70 in the in-house ELISA were among the 22 samples with undetectable levels of Hsp70 in the commercial ELISA kit. The apparent serum concentrations detected were different in the two systems. This dissimilarity can be ascribed to differences in the matrix used. We conclude that the in-house ELISA is more economical and performs well when measuring physiologically high, as well as low, concentrations of Hsp70.

Anti-heat shock protein 90β antibodies decrease pre-oligodendrocyte population in perinatal and adult cell cultures. Implications for remyelination in multiple sclerosis

Lesions in the CNS of patients with multiple sclerosis (MS) often fail to remyelinate, resulting in neurological dysfunction. A key factor seems to be the inefficiency of oligodendrocyte precursor cells (OPCs). We recently reported antibodies against heat shock protein 90beta (Hsp90beta) in MS patients that recognized the antigen on the OPC surface. This study investigates the mechanism and result of anti-Hsp90beta antibody attack. These antibodies induced OPC death in culture in a complement-dependent fashion. Anti-Hsp90beta antibody-induced, complement-mediated OPC death only operated in these cells and caused a significant reduction in the number of O4-positive pro-oligodendrocytes (pre-oligodendrocytes). Adult cultured OPCs also expressed Hsp90beta on their cell surface and were attacked by anti-Hsp90beta antibodies leading to a significant decrease in the pre-oligodendrocyte population. In the presence of low levels of anti-Hsp90beta antibody--i.e. in the range seen in the CSF of MS patients--the complement concentration was critical to reduce the pre-oligodendrocyte population (via attack to OPCs). Higher concentrations of anti-Hsp90beta antibodies and complement became extinct the pre-oligodendrocytes. Complement 1-esterase inhibitor prevented these effects in the pre-oligodendrocyte population. These findings demonstrate, for the first time in vitro, a feasible mechanism to decrease the production of new oligodendrocytes, thus limiting the possibility of remyelination.