Relationship between disease severity and responses by blood mononuclear cells from patients with rheumatoid arthritis to human heat-shock protein 60

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.

Opposing roles for heat and heat shock proteins in macrophage functions during inflammation: a function of cell activation state?

Macrophages function both under normothermia and during periods of body temperature elevation (fever). Whether macrophages sense and respond to thermal signals in a manner which regulates their function in a specific manner is still not clear. In this brief review, we highlight recent studies which have analyzed the effects of mild heating on macrophage cytokine production, and summarize thermally sensitive molecular mechanisms, such as heat shock protein (HSP) expression, which have been identified. Mild, physiologically achievable, hyperthermia has been shown to have both pro- and anti-inflammatory effects on macrophage inflammatory cytokine production and overall it is not clear how hyperthermia or HSPs can exert opposing roles on macrophage function. We propose here that the stage of activation of macrophages predicts how they respond to mild heating and the specific manner in which HSPs function. Continuing research in this area is needed which will help us to better understand the immunological role of body temperature shifts. Such studies could provide a scientific basis for the use of heat in treatment of inflammatory diseases.

A signature of aberrant immune responsiveness identifies myocardial dysfunction in rheumatoid arthritis

OBJECTIVE

Heart failure is an important cause of death in patients with rheumatoid arthritis (RA). Evidence suggests that immune mechanisms contribute to myocardial injury and fibrosis, leading to left ventricular diastolic dysfunction (LVDD). The purpose of this study was to identify a signature of LVDD in patients with RA by analyzing the responsiveness of the innate and adaptive immune systems to stimulation ex vivo.

METHODS

RA patients (n=212) enrolled prospectively in a population-based cohort underwent echocardiography, and LV function was classified as normal, mild LVDD, or moderate-to-severe LVDD. The release of 17 cytokines by blood mononuclear cells in response to stimulation with a panel of 7 stimuli or in media alone was analyzed using multiplex immunoassays. Logistic regression models were used to test for associations between a multicytokine immune response score and LVDD, after adjusting for clinical covariates.

RESULTS

An 11-cytokine profile effectively differentiated patients with moderate-to-severe LVDD from those with normal LV function. An immune response score (range 0-100) was strongly associated with moderate-to-severe LVDD (odds ratio per 10 units 1.5 [95% confidence interval 1.2-2.1]) after adjusting for serum interleukin-6 levels, brain natriuretic peptide values, and glucocorticoid use, as well as other RA characteristics and LVDD risk factors.

CONCLUSION

The major finding of this study was that aberrant systemic immune responsiveness is associated with advanced myocardial dysfunction in patients with RA. The unique information added by the immune response score concerning the likelihood of LVDD warrants future longitudinal studies of its value in predicting future deterioration in myocardial function.

Analysis of complex biomarkers for human immune-mediated disorders based on cytokine responsiveness of peripheral blood cells

The advent of improved biomarkers promises to enhance the clinical care for patients with rheumatoid arthritis (RA) and other immune-mediated disorders. We have developed an innovative approach to broadly assess the cytokine responsiveness of human PBMCs using a multistimulant panel and multiplexed immunoassays. The objective of this study was to demonstrate this concept by determining whether cytokine profiles could discriminate RA patients according to disease stage (early versus late) or severity. A 10-cytokine profile, consisting of IL-12, CCL4, TNF-alpha, IL-4, and IL-10 release in response to stimulation with anti-CD3/anti-CD28, CXCL8 and IL-6 in response to CMV and EBV lysate, and IL-17A, GM-CSF, and CCL2 in response to human heat shock protein 60, easily discriminated the early RA group from controls. These data were used to create an immune response score, which performed well in distinguishing the early RA patients from controls and also correlated with several markers of disease severity among the patients with late RA. In contrast, the same 10-cytokine profile assessed in serum was far less effective in discriminating the groups. Thus, our approach lays the foundation for the development of immunologic "signatures" that could be useful in predicting disease course and monitoring the outcomes of therapy among patients with immune-mediated diseases.

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.

Self heat-shock protein 65-mediated regulation of autoimmune arthritis

Heat-shock proteins (Hsps) have been invoked in the pathogenesis of a variety of autoimmune diseases. The mycobacterial heat-shock protein 65 (Bhsp65) has been studied extensively as one of the antigenic triggers of autoimmunity in experimental models of, as well as patients with, rheumatoid arthritis. As Hsps are highly conserved and immunogenic, it is generally anticipated that self Hsps might serve as the endogenous targets of the immune response initiated by the homologous foreign Hsps. Contrary to this expectation, studies in the rat adjuvant arthritis (AA) model have revealed that priming of the self (rat) hsp65 (Rhsp65)-directed T cells in the Lewis rat leads to protection against AA instead of disease induction or aggravation. The arthritis-protective attribute of the self hsp65 is also evident following spontaneous priming of the anti-Rhsp65 T cells during the natural course of AA. Furthermore, immunization of rats with human hsp60, or with Bhsp65 peptides that are crossreactive with the corresponding self hsp65 peptides, leads to protection against AA. Importantly, high levels of T cell reactivity against self hsp60 in patients with juvenile idiopathic arthritis positively correlate with a favorable outcome of the disease. Thus, immune response against self hsp65 in autoimmune arthritis is protective rather than being pathogenic.

Pan-DR-binding Hsp60 self epitopes induce an interleukin-10-mediated immune response in rheumatoid arthritis

OBJECTIVE

Human Hsp60 is expressed in the joints of patients with rheumatoid arthritis (RA) and can elicit a regulatory T cell response in the peripheral blood and synovial fluid. However, Hsp60 can also trigger strong proinflammatory pathways. Thus, to understand the nature of these Hsp60-directed responses in RA, it is necessary to study such responses at the molecular, epitope-specific level. This study was undertaken to characterize the disease specificity and function of pan-DR-binding Hsp60-derived epitopes as possible modulators of autoimmune inflammation in RA.

METHODS

Lymphocyte proliferation assays (using (3)H-thymidine incorporation and carboxyfluorescein diacetate succinimidyl ester [CFSE] staining) and measurement of cytokine production (using multiplex immunoassay and intracellular staining) were performed after in vitro activation of peripheral blood mononuclear cells from patients with RA, compared with healthy controls.

RESULTS

A disease (RA)-specific immune recognition, characterized by T cell proliferation as well as increased production of tumor necrosis factor alpha (TNFalpha), interleukin-1beta (IL-1beta), and IL-10, was found for 3 of the 8 selected peptides in patients with RA as compared with healthy controls (P < 0.05). Intracellular cytokine staining and CFSE labeling showed that CD4+ T cells were the subset primarily responsible for both the T cell proliferation and the cytokine production in RA. Interestingly, the human peptides had a remarkably different phenotype, with a 5-10-fold higher IL-10:TNFalpha ratio, compared with that of the microbial peptides.

CONCLUSION

These results suggest a disease-specific immune-modulatory role of epitope-specific T cells in the inflammatory processes of RA. Therefore, these pan-DR-binding epitopes could be used as a tool to study the autoreactive T cell response in RA and might be suitable candidates for use in immunotherapy.

Inhibition of experimental Sjögren's syndrome through immunization with HSP60 and its peptide amino acids 437-460

OBJECTIVE

To investigate a potential immunomodulatory effect of the 60-kd heat-shock protein (Hsp60) on experimental spontaneous Sjögren's syndrome (SS).

METHODS

Seven-week-old nonobese diabetic (NOD) mice were immunized with eukaryotic Hsp60 or an Hsp60-derived peptide (amino acid residue [aa] 437-460). At 21 weeks of age, nondiabetic mice were investigated for salivary gland inflammation, exocrine function, and extraglandular disease manifestations. In addition, biomarker profiles comprising 87 analytes in serum and 75 in saliva were analyzed.

RESULTS

In mice immunized with Hsp60 and aa 437-460, SS-related histopathologic features were significantly reduced compared with NOD controls. In addition, 50% of Hsp60-injected mice and 33% of aa 437-460-injected mice retained normal exocrine function. Both treatments induced similar changes in biomarker profiles. Notably, levels of circulating interferon-gamma-inducible 10-kd protein (IP-10) and eotaxin were decreased significantly after treatment. Anti-type 3 muscarinic acetylcholine receptor (anti-M3R) IgG1, interleukin-10, and leptin discriminated best between the different treatment groups. Successful prevention of hyposalivation was accompanied by quantitative alterations in 36 biomarkers, of which 19 mediators of inflammation declined to levels comparable with those found in BALB/c mice. Low secreted vascular endothelial growth factor A was the most accurate predictor of successful prevention of hyposalivation. Low salivary granulocyte chemotactic protein 2 was identified as the best predictor of normal secretory function across the strains.

CONCLUSION

Immunization with Hsp60 and its peptide aa 437-460 led to inhibition of SS in NOD mice. Comprehensive analyses revealed specific biomarker signatures capable of predicting treatment group and treatment outcome. Molecules involved in inflammatory chemotaxis, neovascularization, and regulatory pathways caused the differences displayed by the biomarker profiles.

Proteomic analysis of peripheral blood mononuclear cells: selective protein processing observed in patients with rheumatoid arthritis

In a comparative proteome analysis of peripheral blood mononuclear cells (PBMCs), we analyzed 130 two-dimensional gels obtained from 33 healthy control individuals and 32 patients diagnosed with rheumatoid arthritis (RA). We found 16 protein spots that are deregulated in patients with RA and, using peptide mass fingerprinting and Western blot analyses, identified these spots as belonging to 9 distinct proteins. A hierarchical clustering procedure organizes the study subjects into two main clusters based on the expression of these 16 protein spots, one that contains mostly healthy control individuals and the other mostly RA patients. The majority of the proteins differentially expressed in RA patients when compared with healthy controls can be detected as protein fragments in PBMCs obtained from RA patients. This set of deregulated proteins includes several factors that have been shown to be autoantigens in autoimmune diseases.

Short-term hyperthermia prevents activation of proinflammatory genes in fibroblast-like synoviocytes by blocking the activation of the transcription factor NF-κB

Fibroblast-like synoviocytes (FLS) play a key role in the genesis of rheumatoid arthritis (RA). FLS are among the most versatile cells with the potential to activate an array of genes that are able to initiate and propagate inflammation in RA-affected joints. Controlling activation of FLS might hold the key to restraining inflammation in RA-affected joints. In this study, we investigate the effect and mechanisms of short-term hyperthermia on a series of proinflammatory genes in FLS. In vitro experiments demonstrate that exposure of FLS to elevated temperatures for the duration of 30 min prevents activation of a series of genes with proinflammatory properties. Exposure to hyperthermia reduces IL-1beta-induced prostaglandin E2 release, suppresses activation of the adhesion molecules VCAM-1, ICAM-1, the cytokines TNFalpha, IL-1alpha, IL-1beta, IL-8 as well as COX-2 protein synthesis. Real time reverse transcriptase-polymerase chain reaction showed that hyperthermia altered gene expression at the transcriptional level. The amount and the duration of inhibition is gene-specific and lasts for up to 25 h. As to the mechanism of inhibition, electrophoretic mobility shift assay experiments demonstrated that exposure of FLS to hyperthermia prevents IL-1beta-induced NF-kappaB translocation and subsequent DNA binding. Many mechanisms have been shown to be involved in hyperthermia-mediated effects on NF-kappaB-DNA interactions. We demonstrate by Western blot experiments that in FLS, hyperthermia prevents the phosphorylation and subsequent degradation of IkappaBalpha, therefore retaining the NF-kappaB complex in the cytoplasm. Carefully controlled in vivo tests are certainly needed before one can take full advantage of those phenomena; however, the ease by which the temperature in joints can be modulated might offer an opportunity for manipulating inflammatory processes in joints by simple balneological means.

Heat shock proteins: new keys to the development of cytoprotective therapies

All cells, from bacterial to human, have a common, intricate response to stress that protects them from injury. Heat shock proteins (Hsps), also known as stress proteins and molecular chaperones, play a central role in protecting cellular homeostatic processes from environmental and physiologic insult by preserving the structure of normal proteins and repairing or removing damaged ones. An understanding of the interplay between Hsps and cell stress tolerance will provide new tools for treatment and drug design that maximise preservation or restoration of health. For example, the increased vulnerability of tissues to injury in some conditions, such as ageing, diabetes mellitus and menopause, or with the use of certain drugs,, such as some antihypertensive medications, is associated with an impaired Hsp response. Additionally, diseases that are associated with tissue oxidation, free radical formation, disorders of protein folding, or inflammation, may be improved therapeutically by elevated expression of Hsps. The accumulation of Hsps, whether induced physiologically, pharmacologically, genetically, or by direct administration of the proteins, is known to protect the organism from a great variety of pathological conditions, including myocardial infarction, stroke, sepsis, viral infection, trauma, neurodegenerative diseases, retinal damage, congestive heart failure, arthritis, sunburn, colitis, gastric ulcer, diabetic complications and transplanted organ failure. Conversely, lowering Hsps in cancer tissues can amplify the effectiveness of chemo- or radiotherapy. Treatments and agents that induce Hsps include hyperthermia, heavy metals (zinc and tin), salicylates, dexamethasone, cocaine, nicotine, alcohol, alpha-adrenergic agonists, PPAR-gamma agonists, bimoclomol, geldanamycin, geranylgeranylacetone and cyclopentenone prostanoids. Compounds that suppress Hsps include quercetin (a bioflavinoid), 15-deoxyspergualin (an immunosuppressive agent) and retinoic acid. Researchers who are cognisant of the Hsp-related effects of these and other agents will be able to use them to develop new therapeutic paradigms.

Heat-shock proteins induce T-cell regulation of chronic inflammation

Immune responses to certain heat-shock proteins (HSPs) develop in almost all inflammatory diseases; however, the significance of such responses is only now becoming clear. In experimental disease models, HSPs can prevent or arrest inflammatory damage, and in initial clinical trials in patients with chronic inflammatory disease, HSP-derived peptides have been shown to promote the production of anti-inflammatory cytokines, indicating that HSPs have immunoregulatory potential. In this Review, we discuss the unique characteristics of HSPs that endow them with these immunoregulatory qualities.

DNA vaccines coding for heat-shock proteins (HSPs): tools for the activation of HSP-specific regulatory T cells

Heat-shock proteins (HSPs) perform opposing functions in autoimmune arthritis. HSP-specific T cells drive the progression of adjuvant arthritis (AA), an experimental model of autoimmune arthritis. However, HSP-specific T cells can also have a regulatory phenotype, controlling arthritogenic T cells and inhibiting AA progression. This manuscript reviews the use of DNA vaccines coding for HSPs to analyse the role of these proteins in the regulation of arthritis. Recent studies suggest that HSPs participate in the control of pathological autoimmunity. Indeed, DNA vaccines coding for HSPs can be used to activate these HSP-specific built-in regulatory mechanisms. Thus, DNA vaccines coding for HSPs may serve not only as tools for the dissection of immunoregulatory mechanisms, but also as agents for the treatment of autoimmune disorders.

Exacerbation of rheumatoid arthritis following Helicobacter pylori eradication: disruption of established oral tolerance against heat shock protein?

A 62-year-old Japanese woman with RA received an eradication therapy against Helicobacter pylori in November 1999. Eight weeks later, successful eradication was confirmed by negative results for rapid urease test, pathologic findings, and a fall in anti-H. pylori IgG antibody titer. During the course, parameters for RA activity were exacerbated: C-reactive protein 1.1-4.2 mg/dL, rheumatoid arthritis precipitation antigen 2560-5120 dils., erythrocyte sedimentation rate 52-123 mm/h, and complements CH50 50 to over 60 U/mL. Lansbury index increased from 70% to 105%. Two more weeks later, the patient noticed right shoulder pain. She also complained of bilateral gonalgia two months later, and physical examination revealed increased fluid in the knee joints. Prednisolone was required to control the disease activity. The results of this case suggested that RA patients might experience a deleterious effect on the disease activity following H. pylori eradication possibly through disruption of the established oral tolerance against stress protein such as mycobacterial heat shock protein 65.

Stress cytokines: pivotal proteins in immune regulatory networks; Opinion

Stress proteins have three immunological regulatory functions: within the cell, on the cell membrane as signalling receptors, and in the extracellular environment as stress cytokines. They can activate the immune system by providing danger signals or they may downregulate immune and inflammatory responses. In addition, they can modulate immune responses by acting as chaperones for antigenic peptides while they themselves are processed and presented to T cells as self-peptides. We predict that the exploitation of the downregulatory properties of stress cytokines will have therapeutic applications in the treatment of human chronic inflammatory diseases, such as rheumatoid arthritis.

Inhibition of adjuvant-induced arthritis by DNA vaccination with the 70-kd or the 90-kd human heat-shock protein: immune cross-regulation with the 60-kd heat-shock protein

OBJECTIVE

Adjuvant arthritis can be induced in Lewis rats by immunization with Mycobacterium tuberculosis (Mt). The mycobacterial 65-kd heat-shock protein (Hsp65) is targeted by arthritogenic T cells. However, Hsp65 and the mycobacterial 71-kd heat-shock protein are also recognized by T cells that can down-regulate adjuvant-induced arthritis (AIA). We have recently demonstrated that vaccination with human Hsp60 DNA inhibits AIA. The present study was undertaken to analyze the role of the T cell responses to self HSP molecules other than Hsp60 in the control of AIA.

METHODS

Lewis rats were immunized with DNA vaccines coding for human Hsp70 or Hsp90 (Hsp70 plasmid [pHsp70] or pHsp90), and AIA was induced. The T cell response to Mt, Hsp60, Hsp70, and Hsp90 (proliferation and cytokine release) was studied, and the T cell response to Hsp60 was mapped with overlapping peptides.

RESULTS

The Hsp70 or Hsp90 DNA vaccines shifted the arthritogenic T cell response from a Th1 to a Th2/3 phenotype and inhibited AIA. We detected immune crosstalk between Hsp70/90 and Hsp60: both the Hsp70 and Hsp90 DNA vaccines induced Hsp60-specific T cell responses. Similarly, DNA vaccination with Hsp60 induced Hsp70-specific T cell immunity. Epitope mapping studies revealed that Hsp60-specific T cells induced by pHsp70 vaccination reacted with known regulatory Hsp60 epitopes.

CONCLUSION

T cell immunity to Hsp70 and to Hsp90, like Hsp60-specific immunity, can modulate the arthritogenic response in AIA. In addition, our results suggest that the regulatory mechanisms induced by Hsp60, Hsp70, and Hsp90 are reinforced by an immune network that connects their reactivities.

A pattern of protein expression in peripheral blood mononuclear cells distinguishes rheumatoid arthritis patients from healthy individuals

We compared the expression levels of proteins in peripheral blood mononuclear cells (PBMCs) of healthy control individuals to those of patients diagnosed with rheumatoid arthritis (RA) using a proteomics approach. Using two-dimensional electrophoresis we identified 18 proteins that were 2-fold or more highly expressed in patients than in controls, and 11 proteins that were 2-fold or more highly expressed in controls than in patients. Some of these differentially expressed proteins, identified by MALDI-TOF spectrometry, have previously been shown to play a potential role in the pathogenesis of RA. Hierarchical cluster analyses of the data segregated the samples into two groups, one which contained only controls and the other which contained only patients, and was used to compare the expression pattern of these 29 proteins in individual samples with the median expression pattern determined in the healthy control and in the RA patient groups. This analyses was able to predict whether a sample was derived from a rheumatoid arthritis patient or from a healthy individual, suggesting that a comparison of such protein expression patterns may be of diagnostic value.

DNA fragments of the human 60-kDa heat shock protein (HSP60) vaccinate against adjuvant arthritis: identification of a regulatory HSP60 peptide

Adjuvant arthritis (AA) is induced by immunizing Lewis rats with Mycobacterium tuberculosis suspended in adjuvant. The mycobacterial 65-kDa heat shock protein (HSP65) contains at least one epitope associated with the pathogenesis of AA: T cell clones that recognize an epitope formed by aa 180-188 of HSP65 react with self-cartilage and can adoptively transfer AA. Nevertheless, vaccination with HSP65 or some of its T cell epitopes can prevent AA by a mechanism that seems to involve cross-reactivity with the self-60-kDa HSP60. We recently demonstrated that DNA vaccination with the human hsp60 gene can inhibit AA. In the present work, we searched for regulatory epitopes using DNA vaccination with HSP60 gene fragments. We now report that specific HSP60 DNA fragments can serve as effective vaccines. Using overlapping HSP60 peptides, we identified a regulatory peptide (Hu3) that was specifically recognized by the T cells of DNA-vaccinated rats. Vaccination with Hu3, or transfer of splenocytes from Hu3-vaccinated rats, inhibited the development of AA. Vaccination with the mycobacterial homologue of Hu3 had no effect. Effective DNA or peptide vaccination was associated with enhanced T cell proliferation to a variety of disease-associated Ags, along with a Th2/3-like shift (down-regulation of IFN-gamma secretion and enhanced secretion of IL-10 and/or tumor growth factor beta1) in response to peptide Mt176-190 (the 180-188 epitope of HSP65). The regulatory response to HSP60 or its Hu3 epitope included both Th1 (IFN-gamma) and Th2/3 (IL-10/tumor growth factor beta1) secretors. These results show that regulatory mechanisms can be activated by immunization with relevant self-HSP60 epitopes.

Facets of heat shock protein 70 show immunotherapeutic potential

Amongst the families of intracellular molecules that chaperone and assist with the trafficking of other proteins, notably during conditions of cellular stress, heat shock protein (hsp) 70 is one of the most studied. Although its name suggests that expression is exclusively induced during cellular hyperthermia, members of the hsp70 family of proteins can be constitutively expressed and/or induced by a range of other cellular insults. The ubiquitous presence of hsp70 in eukaryotic and prokaryotic cells, combined with its high degree of sequence homology and intrinsic immunogenicity, have prompted the suggestion that inappropriate immune reactivity to hsp70 might lead to pro-inflammatory responses and the development of autoimmune disease. Indeed, hsp70 has been shown to be a potent activator of innate immunity and aberrant expression of hsp70 in certain organs promotes immunopathology. However, studies also suggest that hsp70 might have immunotherapeutic potential, as hsp70 purified from malignant and virally infected cells can transfer and deliver antigenic peptides to antigen-presenting cells to elicit peptide-specific immunity and, in contrast to its reported pro-inflammatory effects, the administration of recombinant hsp70 can attenuate experimental autoimmune disease. This review focuses on the immunoregulatory capacity of hsp70 and its potential therapeutic value.

Heat shock proteins as regulators of the immune response

Until recently, heat shock proteins (also known as heat stress proteins) have mostly been regarded as intracellular molecules that mediate a range of essential housekeeping and cytoprotective functions. However, interest in their role as intercellular signalling molecules has been fuelled by the observations that these molecules can be released and are present in the extracellular environment under physiological conditions. They can elicit cytokine production by, and adhesion molecule expression of, a range of cell types, and they can deliver maturation signals and peptides to antigen presenting cells through receptor-mediated interactions. These functions suggest that heat shock proteins could be immunoregulatory agents with potent and widely-applicable therapeutic uses. Furthermore, the induction of self heat shock protein immune reactivity can attenuate autoimmunity and delay transplant rejection, and heat shock proteins derived from tumours and pathogens can elicit specific, protective immunity. This review will focus on this rapidly evolving area of heat shock protein biology.

Increased seroreactivity in tic disorder patients to a 60 kDa protein band from a neuronal cell line

In tic disorders, increased seroreactivity against neuronal antigens has been demonstrated, without performing molecular characterization of antigens. Here, unselected patients with a tic disorder were compared with healthy controls, autistic disorder (AD), and obsessive-compulsive disorder (OCD) patients. Seroreactivity against neuroblastoma cells was analyzed by Western blot. Anti-60 kDa binding occurred significantly more frequently in tic disorder patients (67.1%) than in AD (40.0%), OCD (40.0%) and healthy controls (41.9%). Sequence analysis of the 60 kDa protein band identified this as a ubiquitous heat shock protein. However, the involvement of other autoantigens with a molecular weight of 60 kDa cannot be excluded.

Accumulation of human heat shock protein 60-reactive T cells in the gingival tissues of periodontitis patients

Heat shock protein 60s (hsp60) are remarkably immunogenic, and both T-cell and antibody responses to hsp60 have been reported in various inflammatory conditions. To clarify the role of hsp60 in T-cell responses in periodontitis, we examined the proliferative response of peripheral blood mononuclear cells (PBMC), as well as the cytokine profile and T-cell clonality, for periodontitis patients and controls following stimulation with recombinant human hsp60 and Porphyromonas gingivalis GroEL. To confirm the infiltration of hsp60-reactive T-cell clones into periodontitis lesions, nucleotide sequences within complementarity-determining region 3 of the T-cell receptor (TCR) beta-chain were compared between hsp60-reactive peripheral blood T cells and periodontitis lesion-infiltrating T cells. Periodontitis patients demonstrated significantly higher proliferative responses of PBMC to human hsp60, but not to P. gingivalis GroEL, than control subjects. The response was inhibited by anti-major histocompatibility complex class II antibodies. Analysis of the nucleotide sequences of the TCR demonstrated that human hsp60-reactive T-cell clones and periodontitis lesion-infiltrating T cells have the same receptors, suggesting that hsp60-reactive T cells accumulate in periodontitis lesions. Analysis of the cytokine profile demonstrated that hsp60-reactive PBMC produced significant levels of gamma interferon (IFN-gamma) in periodontitis patients, whereas P. gingivalis GroEL did not induce any skewing toward a type1 or type2 cytokine profile. In control subjects no significant expression of IFN-gamma or interleukin 4 was induced. These results suggest that periodontitis patients have human hsp60-reactive T cells with a type 1 cytokine profile in their peripheral blood T-cell pools.

Signal transduction in rheumatoid arthritis

Extracellular signals are transduced intracellularly by multiple pathways, resulting in alterations in the transcription and translation of specific proteins. The end result of some of these signalling pathways is the production of proteins, including cytokines and matrix metalloproteinases, that are implicated in the pathogenesis of rheumatoid arthritis. This chapter includes a discussion of these signal transduction pathways, including tumour necrosis factor receptor signalling, interleukin-1, -4, and -6 receptor signalling, stress- and mitogen-activated protein kinase pathways, CD14 and Toll-like receptor signalling, and T cell signal transduction. The known effects of currently available rheumatoid arthritis (RA) therapeutics on these signalling pathways are also reviewed. In addition, potential future targets for therapeutic intervention in RA are discussed.

Shift toward T helper 1 cytokines by type II collagen-reactive T cells in patients with rheumatoid arthritis

OBJECTIVE

To investigate the impact of type II collagen (CII)-reactive T cells on the Th1/Th2 cytokine balance in patients with rheumatoid arthritis (RA).

METHODS

T cell proliferative responses to bovine CII were examined in synovial fluid mononuclear cells (SFMC) and peripheral blood mononuclear cells (PBMC) by mixed lymphocyte culture. CII-reactive T cell lines were generated from the SFMC and PBMC. Interferon-gamma (IFNgamma), interleukin-12 (IL-12), and IL-4 were measured by enzyme-linked immunosorbent assay in the SF, sera, and culture supernatants of PBMC and SFMC that had been stimulated with CII.

RESULTS

The frequency of CII-reactive T cells was higher in the PBMC from RA patients than in that from osteoarthritis patients and healthy control subjects. In RA patients, CII-reactive T cells were more prevalent in SFMC than in PBMC. The mean level of IFNgamma and the ratio of IFNgamma to IL-4 were significantly higher in the culture supernatants of T cells stimulated with CII; these differences were more prominent in SFMC. Levels of IL-12 in the culture supernatants of SFMC and PBMC stimulated with CII were significantly higher than those in unstimulated supernatants. T cell responsiveness correlated well with the level of type 1 cytokines in culture supernatants from RA T cells stimulated with CII. In the CII-reactive cell lines, the increased production of IFNgamma was consistent with clonal expansion.

CONCLUSION

CII-reactive T cells are more abundant in SFMC than in PBMC and are strongly associated with a shift toward Thl cytokine in the inflamed joints of RA patients. Our results suggest that a skewing toward type 1 cytokines by CII-reactive T cells may play an important role in the chronic inflammatory process of RA.