Presence of human 65 kD heat shock protein (hsp) in inflamed joints and subcutaneous nodules of RA patients

Infectious agents breaking the immunological tolerance: The holy grail in rheumatoid arthritis (RA) reconsidered

Multiple Sclerosis (MS) has been shown to be linked to Epstein Barr Virus (EBV) infection, a virus that infects B cells inside the CNS. The seminal study raises a key interest into the infectious origin of several other autoimmune inflammatory diseases.We will discuss here the infectious agents that have been studied over the years in Rheumatoid Arthritis (RA), a crippling arthritis that was treated a century ago with gold salts (anti mycobacterial agent), with chloroquine (anti malarial agent), or sulphasalazine (an antibacterial-antiinflammatory agent). Several infectious agents have been taken into consideration i.e. Streptococcus group A, Proteus, Mycobacterium tuberculosis-MTB, Parvovirus B19, Epstein Barr virus, Porphyromonas gengivalis-Pg, Aggregatibacter actinomycetescomitans, and finally Haemophilus -Glaesserella parasuis-Hps. Of these agents only three satisfy the Witebski's criteria as possible pathogenetic causes of an autoimmune disease, MTB, Pg, Hps. We will discuss here how the immune tolerance might be broken, which could be the neoantigen or autoantigen involved, how the infectious agent was studied as a trigger capable of inducing arthritis in animal models. The preventive measures that should be adopted to lessen the impact of the infections, to prevent the burden and the severity of the illness are described.

Inhibition of NF-κB signaling and HSP70/HSP90 proteins by newly synthesized hydrazide derivatives in arthritis model

In the current study, the N-benzylidene-4-((2-hydroxynaphthalene-1-yl) diazenyl) hydrazides (NCHDH and NTHDH) were evaluated against the Carrageenan- and CFA-induced models. During the preliminary investigation, the NCHDH and NTHDH treatment showed marked anti-inflammatory and analgesic activity against the Carrageenan-induced acute model. Once the anti-inflammatory activity was established against acute Carrageenan model, the NCHDH and NTHDH were evaluated against the chronic CFA-induced arthritis model. The NCHDH and NTHDH treatment markedly attenuated the inflammatory and analgesic parameters compared to CFA-treated group. Furthermore, the increase in the oxidative stress and attenuation of antioxidant enzymes has been reported following CFA administration. However, NCHDH and NTHDH treatment significantly induced the antioxidants and attenuated the oxidative stress markers. The CFA administration showed marked tailing of DNA; however, the NCHDH- and NTHDH-treated group preserved DNA integrity. Furthermore, the histological studies showed marked alteration in the CFA-treated group; however, the NCHDH and NTHDH treatment markedly improved the histological features. The Western blot, immunohistology, and ELISA assay revealed marked increase in the Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), Jun N-terminal Kinase (JNK), TNF-α, and COX-2 levels; however, the NCHDH and NTHDH attenuated their expressions significantly. Similarly, the NCHDH and NTHDH significantly induced the mRNA expression levels of heat shock proteins. The computational analysis showed significant binding interaction with various protein targets via multiple hydrogens, and hydrophobic bonds. The in vivo pharmacokinetic study was also performed to assess the various pharmacokinetic parameters. In conclusion, the NCHDH and NTHDH treatment showed significant anti-arthritic activity against Carrageenan and CFA models.

Soluble Vascular Biomarkers in Rheumatoid Arthritis and Ankylosing Spondylitis: Effects of 1-year Antitumor Necrosis Factor-α Therapy

OBJECTIVE

Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) have been associated with cardiovascular disease. The treatment of arthritis by tumor necrosis factor-α (TNF-α) inhibitors may decrease the serum concentrations of vascular biomarkers. We determined circulating levels of oxidized low-density lipoprotein (oxLDL)/β₂ glycoprotein I (β₂-GPI) complexes, antibodies to 60 kDa heat shock protein (anti-Hsp60), soluble urokinase plasminogen activator receptor (suPAR), and B-type natriuretic peptide (BNP) fragment in sera of RA and AS patients undergoing anti-TNF treatment.

METHODS

Fifty-three patients with RA/AS were treated with etanercept or certolizumab pegol for 1 year. Circulating oxLDL/β₂-GPI complex (AtherOx), anti-Hsp60 IgG, and BNP8-29 fragment levels were assessed by ELISA. suPAR levels were determined by suPARnostic Quick Triage test. Flow-mediated vasodilation (FMD), carotid intima-media thickness (CIMT), and arterial pulse wave velocity (PWV) were determined by ultrasound.

RESULTS

One-year anti-TNF treatment significantly decreased oxLDL/β₂-GPI levels, as well as suPAR levels in patients with critically high suPAR levels at baseline. In RA, BNP levels were higher in seropositive vs seronegative patients. Serum levels of these vascular biomarkers variably correlated with lipids, anticitrullinated protein antibodies, rheumatoid factor, and C-reactive protein. CIMT positively correlated with BNP, and PWV with suPAR and anti-Hsp60, whereas FMD inversely associated with anti-Hsp60. In repeated measures ANOVA analysis, disease activity supported the effects of anti-TNF treatment on 12-month changes in oxLDL/β₂-GPI. CIMT supported the effects of therapy on changes in anti-Hsp60 and suPAR.

CONCLUSION

These biomarkers may be involved in the pathogenesis of atherosclerosis underlying RA/AS. TNF inhibition variably affects the serum levels of oxLDL/β₂-GPI, suPAR, and BNP.

Vaccination with endosomal unknown epitopes produces therapeutic response in rheumatoid arthritis patients and modulates adjuvant arthritis of rats

Background

Our previous results showed that intrasynovial Rifamycin SV caused the lysis of synoviocites and freed the autoantigens which in turn stimulated the immunoregulatory rather than autoreactive T cell response in rheumatoid patients. Here, we hypothesize that disruption in vitro of peripheral blood mononuclear cells, by freeze/thawing or by lytic action of Rifamycin SV, would induce the release of endosomal pathogenic autoantigens from APCs present in the circulation, which could then be isolated from degrading enzymes by ultrafiltration.

Methods

The preparation of the ultrafiltrates are based on the rupture of PBMCs (5 × 10⁶ cells/mL) by the addition of Rifamycin SV in culture (250 μg/mL), which causes the lysis of 90 % of the cells in 3 h, or by three cycles of freeze/thawing of the PBMC, from −80 °C to room temperature. The lysate and the fragmented cells were then centrifuged and ultrafiltered by passage through a filtration device with a cut-off of 10 kDa. Also the synovial fluid was subjected to ultrafiltration.

Results and conclusions

At clinical monitoring of the 30th day, 22/58 (38 %) patients subcutaneously treated with the autologous ultrafiltrate prepared by the freeze/thawing of PBMCs reached an ACR20. Comparable results were obtained with the other two ultrafiltrates.

Cell cultures The addition of ultrafiltrates to rheumatoid PBMCs cultures led to the upregulation of a marker for T-regulatory cells, and downregulation of a cell proliferation marker; changes that together have the meaning of a global immunomodulatory response and that only a specific antigen (ultrafiltrate UF-f/t) might induce in the rheumatoid patient, probably by activating pre-existing protective network.

Experimental arthritis All the ultrafiltrates except that prepared by Rifamycin SV were able to modulate the adjuvant arthritis in rats. In particular, longlasting synovial fluid induced a significant reduction of the severity of subsequent arthritis (p < 0.01) while SF from recent RA effusion (5–10 days after a previous complete extraction) and knee osteoarthrosis were ineffective. It is reasonable to assume there are at least two unknown endosomal immunoactive epitopes; one developing its immunotherapeutic property in RA, and the other, related to the molecule of HSP60, reduces the severity of oncoming arthritis. Both epitopes are present in humans, have a molecular weight of ≤10 kDa and do not appear to be bystander antigens. Please see Additional file 1 for the abstract in Italian.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-0908-7) contains supplementary material, which is available to authorized users.

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.

Activating and inhibitory receptors on synovial fluid natural killer cells of arthritis patients: role of CD94/NKG2A in control of cytokine secretion

Natural killer (NK) cells are activated early during inflammatory events and contribute to the shaping of the ensuing adaptive immune response. To further understand the role for NK cells in inflammation, we investigated the phenotype and function of synovial fluid (SF) NK cells from patients with chronic joint inflammation, as well as from patients with transient inflammation of the knee following trauma. We confirm that synovial NK cells are similar to the well-characterized CD56(bright) peripheral blood (PB) NK-cell subset present in healthy individuals. However, compared to this PB subset the synovial NK cells express a higher degree of activation markers including CD69 and NKp44, the latter being up-regulated also on CD56(bright) NK cells in the PB of patients. Activated synovial NK cells produced interferon-gamma and tumour necrosis factor, and the production was further up-regulated by antibody masking of CD94/NKG2A, and down-regulated by target cells expressing human leucocyte antigen-E in complex with peptides known to engage CD94/NKG2A. We conclude that synovial NK cells have an activated phenotype and that CD94/NKG2A is a key regulator of synovial NK-cell cytokine synthesis.

NF-kappaB protects macrophages from lipopolysaccharide-induced cell death: the role of caspase 8 and receptor-interacting protein

Macrophages play a pivotal role in the pathogenesis of a variety of diseases. These studies were performed to characterize the mechanisms by which Toll-like receptor 4 (TLR4)-mediated NF-kappaB activation promotes resistance to cell death in macrophages. When NF-kappaB activation was inhibited by a super-repressor, IkappaBalpha, the TLR4 ligand lipopolysaccharide induced the activation of caspase 8, the loss of mitochondrial transmembrane potential (DeltaPsim), and apoptotic cell death in macrophages. The inhibition of caspase 8 activation suppressed DNA fragmentation but failed to protect macrophages against the loss of DeltaPsim and resulted in necrotic cell death. In contrast, the reduction of receptor-interacting protein 1 suppressed the loss of DeltaPsim and inhibited apoptotic cell death. Further, when caspase 8 activation was suppressed, the knock down of receptor-interacting protein inhibited the loss of DeltaPsim and necrotic cell death. These observations demonstrate that following TLR4 ligation by lipopolysaccharide, NF-kappaB is a critical determinant of macrophage life or death, whereas caspase 8 determines the pathway employed.

Effects of Helium-Neon Laser on Levels of Stress Protein and Arthritic Histopathology in Experimental Osteoarthritis

OBJECTIVE

To investigate the effect of low-power laser therapy on levels of stress proteins (SPs) in experimental arthritis and their relation to the bioeffects on arthritic cartilage repair.

DESIGN

A total of 42 rats with similar degrees of induced arthritis evaluated by means of bone scan were divided randomly into two groups. In the treated group, 21 rats received helium-neon laser treatment; in the control group, 21 rats received sham laser treatment. The changes in chondrocytes of SPs were measured by electrophoresis of proteins extracted from chondrocytes of arthritic cartilage at various time periods. The histopathologic changes and the presence of SP of arthritic cartilage were identified by hematoxylin and eosin stain and by immunostains of SP72 antibody individually from frozen sections of arthritic cartilage.

RESULTS

SP density increased markedly in rats after laser treatment and was closely related to the repair of arthritic cartilage. Furthermore, the pathohistology of arthritic cartilage improved significantly with the decline of SP levels in the follow-up period.

CONCLUSION

Helium-neon (632 nm) low-power laser can enhance SP production in arthritic chondrocytes. The extragenic production of SP is well correlated with the therapeutic effect of low-power laser in preserving chondrocytes and the repair of arthritic cartilage in rats.

The T cells specific for the carboxyl-terminal determinants of self (rat) heat-shock protein 65 escape tolerance induction and are involved in regulation of autoimmune arthritis

Immunization of Lewis rats with heat-killed Mycobacterium tuberculosis H37Ra leads to development of polyarthritis (adjuvant-induced arthritis; AA) that shares several features with human rheumatoid arthritis (RA). Immune response to the 65-kDa mycobacterial heat-shock protein (Bhsp65) is believed to be involved in induction of AA as well as in experimental modulation of this disease. However, the understanding of several critical aspects of the pathogenesis of AA in the Lewis rat has severely been hampered by the lack of information both regarding the level as well as epitope specificity of tolerance to the mammalian self (rat) homologue of Bhsp65, 65-kDa rat heat-shock protein (Rhsp65), and about the functional attributes of the T cell repertoire specific for this self protein. In this study, we established that tolerance to Rhsp65 in the Lewis rat is incomplete, and that the residual T cells primed upon challenge with this self hsp65 are disease regulating in nature. We also have defined the T cell epitopes in the C-terminal region within Rhsp65 that contribute predominantly to the immune reactivity as well as the AA-protective effect of this self protein. Furthermore, the T cells primed by peptides comprising these C-terminal determinants can be efficiently restimulated by the naturally generated epitopes from endogenous Rhsp65, suggesting that self hsp65 might also be involved in natural remission from acute AA. These novel first experimental insights into the self hsp65-directed regulatory T cell repertoire in AA would help develop better immunotherapeutic approaches for autoimmune arthritis.

Immunohistochemical analysis of TNF-alpha and HSP-60 in women with tubal factor infertility associated with Chlamydia trachomatis

To explore the roles of tumor necrosis factor-alpha (TNF-alpha) and heat shock protein 60 (HSP-60) in women with tubal factor infertility (TFI) associated with Chlamydia trachomatis, and to determine the mechanisms of fallopian adhesions in Chlamydia trachomatis (CT) infections, the expressions of TNF-alpha and HSP-60 were quantitatively determined in 60 cases of TFI and 30 controls by immunohistochemical technique. The patients with TFI were further divided into group A and group B according to the CT-DNA of cervical specimens of PCR. The quantitative analysis was conducted by employing computerized image analysis system. It is found that the expressions of TNF-alpha and HSP-60 were much higher in TFI patients than those of controls. Among CT-HSP responders, a stronger expression was correlated with more severe salpingeal pathology. It is concluded that TNF-alpha and HSP-60 play very important roles in fallopian tube adhesion and occlusion in TFI due to CT infection.

A comparative study of localization of heat shock protein 27 and heat shock protein 72 in the developmental and degenerative intervertebral discs

STUDY DESIGN

The lumbar intervertebral discs of 135 subjects after autopsy were immunostained with antihuman heat shock protein 27 (HSP27) monoclonal antibody and antihuman heat shock protein 72 (HSP72) polyclonal antibody.

OBJECTIVES

To present the data on metabolic changes that occurred in the chondrocytes of intervertebral discs during development and aging.

SUMMARY OF BACKGROUND DATA

Heat shock proteins have been implicated in the progressive degeneration of articular cartilage in joint disease, such as rheumatoid arthritis and osteoarthritis. However, the role and expression of heat shock proteins in human intervertebral discs have received little study.

METHODS

One hundred thirty-five specimens of human intervertebral discs were stained with hematoxylin and eosin, alcian blue, and Masson's trichrome and were immunostained with HSP27 and HSP72 by an indirect immunoperoxidase method. The relative amounts of HSP27 and HSP72 deposition were graded according to a semiquantitative scoring system.

RESULTS

Heat shock protein 72 accumulated in the cytoplasm of the chondrocytes of both endplate cartilage and nucleus pulposus during gestation and thereafter decreased with aging (age, </=60 years), and HSP72 immunoreactivity increased in the chondrocytes of degenerative discs. In addition, HSP72 was located in the nuclei of certain chondrocytes of the degenerated nucleus pulposus and anulus fibrosus, was highly expressed in the chondrocytes of endplate cartilage during gestation and childhood, and thereafter decreased with aging. Furthermore, with the progressive degeneration of the endplate cartilage, HSP27 immunoreactivity increased. The degree of HSP27 immunoreactivity did not change significantly according to age in either the nucleus pulposus or the anulus fibrosus.

CONCLUSIONS

Heat shock protein 27 and HSP72 are thus considered to be useful molecular indicators for degenerative change in intervertebral discs. Both HSP27 and HSP72 are presumed to play a role in cell protection from stress that is induced by mechanical and biologic factors causing intervertebral disc degeneration.

The human endoplasmic reticulum molecular chaperone BiP is an autoantigen for rheumatoid arthritis and prevents the induction of experimental arthritis

Rheumatoid arthritis (RA) is the most common, crippling human autoimmune disease. Using Western blotting and tandem mass spectroscopy, we have identified the endoplasmic reticulum chaperone BiP, a 78-kDa glucose-regulated protein, as a possible autoantigen. It preferentially stimulated increased proliferation of synovial T cells from patients with RA but not from patients with other arthritides. Mice with established collagen- or pristane-induced arthritis developed IgG Abs to BiP. Although BiP injected in CFA failed to induce arthritis in several strains of rats and mice, including HLA-DR4(+/-)- and HLA-DR1(+/+)-transgenic animals, it completely inhibited the development of arthritis when given i.v. 1 wk before the injection of type II collagen arthritis. Preimmunization with BiP suppressed the development of adjuvant arthritis in Lewis rats in a similar manner. This is the first report of a mammalian chaperone that is an autoantigen in human RA and in experimental arthritis and that can also prevent the induction of experimental arthritis. These findings may stimulate the development of new immunotherapies for the treatment of RA.

The stressed synovium

This review focuses on the mechanisms of stress response in the synovial tissue of rheumatoid arthritis. The major stress factors, such as heat stress, shear stress, proinflammatory cytokines and oxidative stress, are discussed and reviewed, focusing on their potential to induce a stress response in the synovial tissue. Several pathways of stress signalling molecules are found to be activated in the synovial membrane of rheumatoid arthritis; of these the most important examples are heat shock proteins, mitogen-activated protein kinases, stress-activated protein kinases and molecules involved in the oxidative stress pathways. The expression of these pathways in vitro and in vivo as well as the consequences of stress signalling in the rheumatoid synovium are discussed. Stress signalling is part of a cellular response to potentially harmful stimuli and thus is essentially involved in the process of synovitis. Stress signalling pathways are therefore new and promising targets of future anti-rheumatic therapies.

Highly autoproliferative T cells specific for 60-kDa heat shock protein produce IL-4/IL-10 and IFN-gamma and are protective in adjuvant arthritis

Previously we have shown that T cell responses to the mycobacterial 60-kDa heat shock protein (hsp60) peptide M256-270 mediated protection against adjuvant arthritis in Lewis rats. We have demonstrated now that M256-270-primed T cells become highly reactive to naive syngeneic APC upon repetitive restimulation in vitro with peptide M256-265, comprising the conserved core of peptide M256-270. These autoproliferative responses in the absence of added Ag were MHC class II restricted and resulted in the production of IL-4/IL-10 and IFN-gamma. Enhanced autoproliferation and expression of the cell surface molecule B7.2 by these T cells were observed in response to syngeneic heat-shocked APC, which indicated that the autoproliferation and expression of B7.2 resulted from the recognition of endogenously expressed and processed hsp. Despite their strong autoreactivity, upon transfer such T cells were found to induce a significant disease reduction in adjuvant arthritis. In contrast, T cells both primed and restimulated with peptide M256-270 became unresponsive toward syngeneic APC as well as toward the conserved core peptide M256-265, and they were devoid of protective capacity. This study demonstrates that the loss of self-tolerance toward hsp60 does not necessarily lead to autoimmune disease, but that hsp60-specific self-reactive and autoproliferative T cells may mediate T cell regulation in arthritis.

Antibodies against mycobacterial antigens in the synovial fluid of patients with temporomandibular disorders

In the absence of active pulmonary disease, mycobacterial infection frequently causes arthritis and can be considered to initiate autoimmune diseases such as rheumatoid arthritis. Temporomandibular disorder (TMD) is a disease in which pain and impaired mandibular movement appear to arise directly from degenerative or inflammatory changes within the temporomandibular joint, but its precise pathogeny has not been elucidated. Here we examined whether mycobacterial infection is related to the pathology of TMD. The antibody levels against mycobacterial antigen in the synovial fluid (SF) of patients with TMD were assessed by enzyme-linked immunosorbent assay (ELISA). Six of 17 TMD patients (35%) were found to possess mycobacterial antigen-specific immunoglobulin (Ig) G but not IgM, while the six healthy volunteers possessed neither. Western-blot analysis was used to isolate the reacted antigen, and the IgG reacted strongly to 44-kDa antigen. The first 14 N-terminal amino acid sequences were determined, and computer analysis revealed that it was homologous to translational elongation factor Tu (EF-Tu) of Mycobacterium tuberculosis, which was a major target antigen for these antibodies. The 44-kDa protein of Mycobacterium bovis BCG (BCG) was identical with the EF-Tu of M. tuberculosis. We cloned the gene encoding the EF-Tu of BCG by using the synthesized oligonucleotide primers by means of polymerase chain-reaction. The gene was expressed in Escherichia coli. The protein was purified, and the antibody levels against this recombinant protein in the SF of TMD patients were assessed by ELISA. Our findings suggest that some cases of TMD are concerned with the synovial IgG against the EF-Tu of M. tuberculosis, and that the existence of the antibody is a clinical indication of TMD.

A self-hsp60 peptide acts as a partial agonist inducing expression of B7-2 on mycobacterial hsp60-specific T cells: a possible mechanism for inhibitory T cell regulation of adjuvant arthritis?

We previously reported that resistance to the induction of adjuvant arthritis after preimmunization with mycobacterial hsp60 was mediated by T cells recognizing a conserved epitope (M256-270) of mycobacterial hsp60. These T cells were cross-reactive with the homologous rat hsp60 peptide sequence and the natural self-epitope on stressed antigen-presenting cells. Recognition of peptide M256-265, the conserved core of peptide M256-270, was shown to be essential for the generation of self-reactive T cells. The rat homologue of peptide M256-265, peptide R256-265, differs with three conservative amino acid substitutions from the mycobacterial core peptide. Thus peptide R256-265 could act as an altered peptide ligand with the potential of inducing a different functional phenotype in M256-270-specific T cells. We now show that peptide R256-265 was recognized by M256-270-specific T cells as a partial agonist, inducing TCR down-regulation and up-regulation of activation/adhesion molecules in the absence of proliferative responses. Peptide R256-265 did not induce anergy but induced B7-2 (but not B7-1) expression on M256-270-specific T cells, as opposed to the mycobacterial peptide, which preferentially induced B7-1. These effects were more pronounced at low peptide concentrations. Therefore also in vivo at the more relevant low physiological level of expression, the self-hsp could induce such phenotype. It is discussed how this selective up-regulation of B7-2 expression on (self-hsp60) autoreactive T cells might be a way by which destructive autoimmune responses are controlled.

Ultrasound effect on level of stress proteins and arthritic histology in experimental arthritis

OBJECTIVE

To investigate the effect of ultrasound on the levels of stress protein in experimental arthritis and their relation to the therapeutic effects on arthritic cartilage repair.

METHODS

Thirty-six rats with similar degree of early arthritis were divided at random into two groups. In group s, 18 rats received sonication; in group c, 18 control rats received sham sonication. The severity of induced arthritis was evaluated from bone scan with technetium-99m. The presence and changes of stress protein were identified from immunostain of SP72 antibody from frozen sections of arthritic cartilage and from electrophoresis of proteins extracted from chondrocytes of arthritic cartilage. The severity index, density of immunostained chondrocytes, and histopathologic changes at various periods were also studied in each group.

RESULTS

The density of stress protein was increased markedly in treated rats after sonication and it was closely related to the repair of arthritic cartilage. Once the pathohistology of arthritic cartilage improved, stress protein declined significantly in the follow-up period.

CONCLUSION

Therapeutic ultrasound can enhance stress protein production in arthritic chondrocytes. The extragenic production of stress protein was well correlated with the therapeutic effect of ultrasound to preserve chondrocytes and bring about the repair of arthritic cartilage.

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

OBJECTIVES

Stress proteins (HSPs) are highly conserved immunodominant antigens found in various species. The purpose of this study was to assess the prevalence and prognostic significance of antibodies to HSC 70 kDa and HSP 90 kDa in three groups of patients with longstanding rheumatoid arthritis (RA) defined based on the severity of articular erosions.

METHODS

73 patients with longstanding (> 6 years) RA whose HLA-DR genotype was known were divided in three groups according to Larsen's score and compared with 47 recent onset (<1 year) RA patients and with control groups composed of patients with other inflammatory diseases (n=137) or of normal controls (n=48). IgGs and IgMs to HSC 70 kDa and HSP 90 kDa were determined using an ELISA with purified bovine HSC 70kDa or HSP 90 kDa.

RESULTS

Concentrations of IgGs and IgMs to HSC 70 were significantly increased in 41.1% and 42.5% of longstanding RA patients, respectively. Corresponding figures for IgGs and IgMs to HSP 90 were 39.7% and 56%. IgMs to HSC 70 and HSP 90 were less frequent in recent onset RA (19% and 13% respectively). Among the groups with other inflammatory diseases, only the MCTD group exhibited high frequencies of IgGs to HSC 70 (80%) and HSP 90 (85%). DRB1*0401 positive RA patients (n=23) were not more likely to have increased concentrations of antibodies to HSC 70 kDa or HSP 90 kDa than other RA patients (DR4 positive but DRB1*0401 negative, or DR1 positive, n=31; or negative for both DR4 and DR1, n=14). IgGs to HSP 90 kDa were significantly more frequent (p<0.05) in longstanding RA patients whose Larsen's score was 4 or more (57%) than in those whose Larsen's score was 2 or 3 (39.4%) or less than 2 (16%). No associations were found between Larsen's score and IgGs or IgMs to HSC 70 kDa or IgMs to HSP 90 kDa. A significant correlation was demonstrated between IgGs to HSP 90 kDa and two other serological markers for RA, rheumatoid factor, and anti-Sa antibody; there were no correlations with antikeratin antibody, antiperinuclear factor, or anti-RA 33.

CONCLUSION

IgGs to HSP 90 kDa are most common in longstanding RA patients with articular erosions, suggesting that they may be related to the articular prognosis in RA

The arthritogenic properties of microbial antigens. Their implications in disease states

The sharing of antigenic determinants between host and microbe is a common event and new microbial-tissue cross-reactions are being recognized each year. Almost every human organ has been implicated as a possible target. The purpose of this article is to examine the arthritogenic properties of these microbial antigens and to explore the mechanisms by which they induce pathologic damage and disease.

An Immunodominant Epitope from Mycobacterial 65-kDa Heat Shock Protein Protects Against Pristane-Induced Arthritis

Previous studies showed that mice with pristane-induced arthritis (PIA) and those protected from the disease by preimmunization with mycobacterial 65-kDa heat shock protein (hsp65) possess raised immune responses to hsp65. Additionally, T cells from hsp65-protected mice, but not from pristane-injected or normal mice, produced the Th2-associated cytokines IL-4, IL-5, and IL-10 in response to stimulation with hsp65. Here we demonstrate that the specificity of the immune response to hsp65 and related heat shock protein (hsps) differs between protected and PIA mice. T cells from hsp65-protected mice respond to the bacterial hsps tested but not to the mammalian homologue, hsp58. Similarly, they exhibit high serum titers of anti-hsp65 Abs, yet they have virtually undetectable levels of anti-hsp58 IgG. By contrast, both cellular and humoral immune responses are detectable to bacterial and mammalian hsps in mice with PIA. An immunodominant T cell epitope has been identified in hsp65-protected mice corresponding to amino acids 261–271 from hsp65. Immunization of mice, either before or after the induction of arthritis, with this bacterial peptide, but not its mammalian homologue, protects mice from the development of PIA, and protection is associated with the production of Th2-type cytokines. Other experiments revealed that T cells primed with bacterial 261–271 or the mammalian homologue do not cross-react at the proliferative or cytokine level. These results demonstrate that an hsp65 peptide-specific Th2 response confers protection from PIA but do not support the idea that protection is mediated by a cross-reaction with self hsp58 in the joints.

Stimulation of suppressive T cell responses by human but not bacterial 60-kD heat-shock protein in synovial fluid of patients with rheumatoid arthritis

In several animal models of rheumatoid arthritis (RA), T cell responses to self 60-kD heat-shock protein 60 (hsp60) protect against the induction of arthritis. The nature of this suppressive T cell activity induced by self hsp60 is not clear. In the present study, T cell responses to human (self) hsp60 in RA in terms of type 1 (T1) and type 2 (T2) T cell activity were assessed. The results show that human and not bacterial hsp60-reactive synovial fluid (SF) T cells of patients with RA proliferate in the presence of the T2 cell growth factor IL-4. SF T cells stimulated with human hsp60 produced significantly lower amounts of IFN-gamma and higher amounts of IL-4 than SF T cells stimulated with bacterial hsp60 (P </= 0.002 and 0.05, respectively), and consequently a lower T1/T2 cell cytokine ratio was observed for human versus bacterial hsp60 (P </= 0.004). Additionally, human and not mycobacterial hsp60-specific T cell lines suppressed TNF-alpha production. Together, our results suggest that human hsp60, as overexpressed in inflamed synovium of patients with RA, can contribute to suppression of arthritis by the stimulation of regulatory suppressive T cell activity.

Specific and long-lasting suppression of rat adjuvant arthritis by low-dose Mycobacterium butyricum

We have tested the therapeutic effect of intraperitoneal injections of Mycobacterium butyricum on the development of adjuvant arthritis in rats and we have explored the specificity and the duration of effectivity of this treatment. Rats with induced arthritis were injected intraperitoneally with the causative antigen, Mycobacterium butyricum, at concentrations 10 times lower than the inducing one, on the 3rd and 10th day after arthritis induction. The severity of the disease was assessed on the basis of physical (arthritis index, paw swelling) and biochemical (serum interleukin-6) parameters. The treatment with Mycobacterium butyricum led to a significant suppression of adjuvant-induced arthritis. This therapeutic effect was both antigen-specific, because intraperitoneal aspecific inflammation did not prevent the disease, and long-lasting. The results obtained in this model confirm the possibility of modulating the autoimmune process even when the immunological response is already triggered, suggesting new therapeutic strategies, more suitable than preventive vaccination, in human autoimmune diseases.

Clonal expansion of mycobacterial heat-shock protein-reactive T lymphocytes in the synovial fluid and blood of rheumatoid arthritis patients

OBJECTIVE

To examine the reactivity pattern and T cell receptor (TCR) characteristics of mycobacterial heat-shock protein 65 (hsp65)-reactive T cells generated from paired synovial fluid (SF) and peripheral blood (PB) samples obtained from rheumatoid arthritis (RA) patients and from healthy subjects.

METHODS

The reactivity pattern of hsp65-reactive T cell clones generated under limiting-dilution conditions was analyzed in 3H-thymidine incorporation assays. The TCR variable regions of these hsp65-reactive T cells were characterized by polymerase chain reaction with TCR AV- and BV-specific primers and by DNA sequence analysis of the third complementarity-determining region (CDR3).

RESULTS

The hsp65-reactive T cells derived both from RA patients and controls preferentially recognized the 1-170 and 303-540 regions of hsp65 and did not cross-react with human hsp60. The hsp65-reactive T cell clones derived from RA patients displayed a restricted TCR AV and BV gene usage, which can be attributed to the limited clonal origin(s) of the independent T cell clones, as evidenced by CDR3 sequence analysis. These clonally expanded T cells were found in both PB and SF and in different inflamed joints of RA patients.

CONCLUSION

Our study suggests that there is in vivo clonal activation and expansion of mycobacterial hsp65-reactive T cells in patients with RA.

Cytokine and adhesion molecule expression in human monocytes and endothelial cells stimulated with bacterial heat shock proteins

Bacterial heat shock proteins (HSPs) from Escherichia coli (GroES, GroEL, and DNAk) were tested for their ability to induce by themselves the expression and release of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-alpha), and granulocyte-monocyte colony-stimulating factor (GM-CSF) by human monocytes and GM-CSF, IL-6, E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) by human umbilical vein endothelial cells (HUVEC). Our study demonstrated that treatment of monocytes with DNAk increased IL-6, TNF-alpha, and GM-CSF release in a dose-dependent manner. The same effect was elicited by GroEL but at a lower rate. Treatment of HUVEC cultures with DNAk and GroEL also increased GM-CSF, IL-6, E-selectin, ICAM-1, and VCAM-1 release in a dose-dependent fashion. In any case, the greatest release was obtained by using DNAk and GroEL at a concentration of 1 microg/ml. DNAk and GroEL were also able to up-regulate the surface expression of E-selectin, ICAM-1, and VCAM-1. As detected by reverse transcription-PCR analysis, DNAk and GroEL also increased the steady-state levels of cytokines and adhesion molecules in human monocytes and endothelial cells. In our study GroES showed a significant activity only on the release, surface expression, and mRNA transcription of E-selectin. Adhesion molecule expression seems to be a direct effect of HSPs and not via cytokines. Furthermore, these effects are due to HSPs properties because they are inhibited by specific monoclonal antibodies. These findings support the potential role of HSPs in modulating cell interactions during immunological and inflammatory responses.

TNF-alpha, IL-1 alpha, IL-6 and ICAM-1 expression in human keratinocytes stimulated in vitro with Escherichia coli heat-shock proteins

Bacterial heat-shock proteins (HSPs) from Escherichia coli (GroES, GroEL and DnaK) were studied for their ability to induce by themselves the expression and release of tumour necrosis factor-alpha (TNF-alpha), interleukin-1 alpha (IL-1 alpha), interleukin-6 (IL-6) and intercellular adhesion molecule-1 (ICAM-1) by cultured human keratinocytes. The surface expression of ICAM-1 was also investigated. In the supernatants of untreated cells none or a minimal amount of these molecules was found. After 48 h of stimulation with GroEL significant amounts of TNF-alpha, IL-1 alpha, IL-6 and soluble ICAM-1 were detected, reaching maximum concentrations at 1 microgram ml-1. The same effect was elicited by DnaK but to a lesser extent. Treatment of keratinocytes with GroEL and DnaK also increased TNF-alpha, IL-1 alpha, IL-6 and ICAM-1 mRNA levels. GroES showed significant activity only on the expression and release of IL-6. GroEL and DnaK were also able to up-regulate the surface expression of ICAM-1 on keratinocytes. The effects on ICAM-1 expression seemed to be directly due to HSPs and not mediated via cytokines. Furthermore, these effects were due to the properties of HSPs because they were inhibited by specific monoclonal antibodies. These findings support the potential role of HSPs in modulating cell interactions during immunological and inflammatory responses in the skin.

Induction of heat shock protein 60 expression in human monocytic cell lines infected with Mycobacterium leprae

Monocytic cell lines (HL-60 and THP-1) were infected with viable Mycobacterium leprae. Levels of human hsp60 were estimated by Western blot (immunoblot) assay and a sandwich enzyme-linked immunosorbent assay. The results showed that infection of both of the cell lines induced the synthesis of human hsp60, which may be of significance in relation to autoimmune manifestations associated with mycobacterial infections.

Effects of adjuvant on neuropeptide-like immunoreactivity in experimentally induced temporomandibular arthritis in rats

Substance P (SP)-, neurokinin A (NKA)-, calcitonin gene-related peptide (CGRP)- and neuropeptide Y (NPY)-like immunoreactivities (-LI) were examined in cerebrospinal fluid (CSF), plasma and temporomandibular joint (TMJ) perfusates in rats 1 and 12 h after inoculation at the base of the tail (0.05 ml) or injection into the right TMJ (0.01 ml) of heat-killed Mycobacterium butyricum in paraffin oil. In the rats inoculated at the base of the tail (polyarthritic rats), there was a significant increase of CGRP-LI and NKA-LI. The changes in neuropeptide-LI were not as marked in the CSF of rats injected with adjuvant in one TMJ (monoarthritic rats) as in the polyarthritic group. Instead, the most significant changes in the monoarthritic rats were seen in the perfusates of both TMJs. The increases in SP-, NKA-, CGRP- and NPY-LI were significant for both TMJs and more pronounced than in the polyarthritic rats. The results show that inoculation of adjuvant at the base of the tail induces significant changes of neuropeptide-LI predominantly in CSF, whilst an intra-articular injection induces bilateral changes in neuropeptide-LI in joint perfusate. Therefore, two different neural mechanisms may be involved early in adjuvant-induced poly- and monoarthritis.

Induction of heat shock protein in monocytic cells by oxidized low density lipoprotein

The atherosclerotic lesion may be characterized as a chronic inflammatory process, and oxidized LDL is believed to be a key event in the development of atherosclerosis, though the mechanisms by which oxidized LDL exerts its proatherogenic properties are largely unknown. Heat shock proteins (hsp) are a group of proteins with a highly conserved structure and of these, hsp60 has been suggested to play a role in autoimmunity due to T lymphocyte crossreactivity between bacterial and human hsp60. The present study was designed to investigate the effects of oxidized LDL on the expression of hsp60 using the monocytic cell lines U937 and HL60 as models. The expression of hsp60 was determined by using monoclonal antibodies to hsp60 in FACScan, Western blot, and a sandwich ELISA. The results show that hsp60 is induced in both cell types after 2 h exposure to oxidized LDL, with a maximal effect at 20 micrograms/ml for U937 cells and 5 micrograms/ml for HL60 cells. A close to 3-fold increase in the expression of hsp60 was seen after culturing oxidized LDL (20 micrograms/ml) treated U937 cells for a period of 24 h. Interleukin 1-beta had similar effects on hsp60 expression to oxidized LDL. The results indicate that expression of hsp60 by monocytes in the vascular wall may be enhanced by oxidized LDL. It is thus possible that the chronic inflammatory process characterizing atherosclerosis is perpetuated by autoreactive T cells, which recognize hsp60 expressed by monocytes, induced by oxidized LDL.

Anti-Hsp65 antibodies recognize M proteins of group A streptococci

Group A streptococcal M protein and the mycobacterial heat shock protein, hsp65, are strong bacterial immunogens that have been linked to arthritis and autoimmunity. Recent evidence has shown that streptococcal arthritis and adjuvant arthritis may be related to epitopes shared between group A streptococci and hsp65. We investigated the possibility that immunological similarities were shared between streptococcal M protein and hsp65. Antibodies against the 65-kDa heat shock protein of Mycobacterium tuberculosis were tested for reactivity with group A streptococci and purified recombinant M proteins (rM5 and rM6). Rabbit polyclonal anti-hsp65 serum was highly reactive with M type 5 Streptococcus pyogenes and rM5 and rM6 proteins in an enzyme-linked immunosorbent assay (ELISA). A mouse anti-hsp65 monoclonal antibody (MAb), IIC8, reacted with streptococcal M types 5, 6, 19, 24, and 49 in an ELISA but showed no reactivity with an isogenic streptococcal mutant which did not express M protein. Anti-hsp65 MAb IIC8 recognized rM5 and rM6 proteins in the ELISA, and MAbs IIC8 and IIH9 reacted strongly with rM6 protein in Western immunoblots. The binding of M protein by anti-hsp65 MAbs was shown to be inhibited by both hsp65 and M protein. These data show that anti-hsp65 antibodies recognize streptococcal M proteins.

Biliary expression of heat shock protein: a non-specific feature of chronic cholestatic liver diseases

AIM

To analyse the expression of heat shock protein (HSP) 60 in biliary epithelium in auto-immune liver conditions and also in chronic cholestatic and other liver diseases.

METHODS

Hepatic expression of HSP-60 in frozen liver biopsy specimens from patients with primary sclerosing cholangitis (PSC), primary biliary cirrhosis (PBC), auto-immune hepatitis (AIH), obstructive jaundice (LDO), alcoholic liver disease (ALD), and from normal controls was studied by immunohistochemistry using the APAAP technique and confocal laser scanning microscopy.

RESULTS

Increased expression of HSP-60 was demonstrated in the biliary epithelium of patients with PBC, LDO and, to a lesser extent, with PSC. Focal, weaker, biliary epithelial expression of HSP-60 was observed in AIH, ALD and normal liver tissue. Increased expression was also seen on Kupffer cells in LDO and in hepatocytes in areas of piecemeal necrosis in AIH.

CONCLUSION

Enhanced biliary expression of HSP-60 is a common feature of chronic biliary disease irrespective of aetiology and is not specific to auto-immune diseases.

High expression of heat shock protein 60 in follicular cells of Hashimoto's thyroiditis

Heat shock protein 60 expression in the thyrocytes of Hashimoto's thyroiditis and Graves' disease was studied immunohistochemically. Thyrocytes of Hashimoto's thyroiditis showed high expression of heat shock protein 60 not only in tall eosinophilic-cells but also in low and flattened cells, although the former was stained with moderate to strong staining intensity and the latter weakly to moderately. Follicular cells around lymphoid cell follicles were stained more intensely, whereas cells apart from lymphoid cell follicles were stained weakly to moderately. In Graves' disease, only follicular cells around lymphoid cell follicles were stained with varying intensities. Since the pattern in all positive staining was granular, it was thought that heat shock protein 60 overexpressed in thyrocytes located on mitochondria. To investigate the immunological role of overexpression of self heat shock protein 60 in the thyrocytes of Hashimoto's thyroiditis, gamma delta TCR+ T-cells in the tissue and the IgG class of anti-self heat shock protein 60 antibodies were studied. gamma delta TCR+ T-cells were detected among lymphoid cells scattered in interfollicular connective tissue. No difference in antibody level was seen among subjects with Hashimoto's thyroiditis, Graves' disease and normal subjects. Self heat shock protein 60 overexpression in the thyrocytes of Hashimoto's thyroiditis may play a disease-modifying role, although it does not influence the anti-self heat shock protein 60 antibody level.

Detection of antibodies to 65 KD heat shock protein and to human superoxide dismutase in autoimmune hepatitis-molecular mimicry between 65 KD heat shock protein and superoxide dismutase

The antibody to 65 KD mycobacterial heat shock protein (HSP65) and antibody to human superoxide dismutase (H-SOD) were measured by ELISA in patients with autoimmune hepatitis (AIH), and results were compared with those of patients with chronic active hepatitis C (CAH-C) or systemic lupus erythematosus (SLE) and normal subjects (NS). Patients with AIH had significantly higher OD values of anti-HSP65 antibody and anti-H-SOD antibody compared with those of patients with CAH-C or SLE and NS. OD values of anti-HSP65 antibody were correlated with those of anti-SOD antibody. Affinity-purified anti-SOD antibody reacted with HSP65. Analysis of the amino acid sequence of human SOD showed that 7 segments, corresponding to r to 25 amino acid residues, exhibited 50 to 71% homology with that of my mycobacterial HSP65.

Autoantibody against 70 kD heat shock protein in patients with autoimmune liver diseases

BACKGROUND/AIMS

It has recently been suggested that heat shock proteins are implicated in the pathogenesis and teh pathophysiology of various immunological disorders, and the presence of antibodies against heat shock proteins has been reported in several autoimmune diseases.

METHODS

We investigated autoantibodies against the two major human heat shock proteins (hsp70 and hsp90) in sera from patients with primary biliary cirrhosis and autoimmune hepatitis, the two major autoimmune liver disease. Reactivity with human heat shock proteins obtained from phytohemagglutinin stimulated cells was investigated by immunoblots with sera at 1:20 dilution.

RESULTS

Reactivity with human hsp90 was not found in any sera from patients or normal controls. In contrast, reactivity with human hsp70 was found in 16 of 35 (45.7%) primary biliary cirrhosis patients and in 9 of 17 (52.9%) autoimmune hepatitis patients, but similar reactivity was found in only 2 of 15 patients with chronic hepatitis B and 1 of 13 patients with chronic hepatitis C. All the normal controls showed a negative reaction. Two-dimensional immunoblots and immunoabsorption experiments established that the autoantibody recognized only human hsc70 (73 kD/pI 5.5), a constitutive form of the hsp70 family.

CONCLUSIONS

Although the pathological significance of the autoantibody against hsc70 in these autoimmune liver diseases remains unknown, the serum autoantibody detected in primary biliary cirrhosis patients is closely related to clinical variables including serum total bilirubin, alanine aminotransferase, IgG, IgM, titers of antimitochondrial antibodies, and major symptoms (pruritus and/or icterus). These observations may suggest that the anti-hsc70 antibody is an indicator for the disease activity of primary biliary cirrhosis.

Immunopathogenesis and immunotherapy in rheumatoid arthritis: an area in transition

In years to come, new therapeutic modalities for the treatment of chronic arthritis will be launched for general clinical use. These therapies, until today only used in clinical studies, are based on knowledge obtained from animal models of chronic arthritis. This knowledge not only ushers therapeutic use in humans: in many settings, the animal studies have proven to be irreplacable tools to get insights into the pathogenesis of chronic arthritis. Rheumatoid arthritis (RA) shows a strong linkage of susceptibility to a certain epitope common to some HLA-DR beta chains; this immunogenetic linkage is the strongest evidence for specific, T-cell dependent immunity in the pathogenesis of the disease. Despite intense efforts, no unequivocal proofs of T-cell specificity or oligoclonality have been found in RA. Therapeutic efforts directed against T-cells or T-cell functions have also at the best showed partial effects. As compared to the local production of T-cell cytokines in the joint, monokine production is abundant. Therapies aimed at neutralizing the effects of the cartilage-devastating monokine TNF-a have showed remarkable results in small clinical trials. The possibility of increasing the presence of the regulatory cytokines IL-4, IL-10 and TGF-beta has also been explored, but only in animal studies. Immunology has also shed light on the mode of action of the commonly used 'disease modifying' drugs, and combinations of such drugs have shown increased potentials in recent clinical studies. The possibility of combining traditional anti-arthritic drugs with recent immunological tools seem promising for the future. This review discusses recent advances in the understanding of pathogenesis and delineate new therapeutic approaches for chronic arthritis from the point of view of the immunologically oriented clinician.

Mycobacterial 65-kilodalton heat shock protein induces tumor necrosis factor alpha and interleukin 6, reactive nitrogen intermediates, and toxoplasmastatic activity in murine peritoneal macrophages

The 65-kDa heat shock protein (Hsp65) is supposed to play a role in host defense against infections with various microbial pathogens and in autoimmune inflammatory disorders. These effects are thought to result mainly from an Hsp65-specific T-lymphocyte-mediated immune response that recognizes conserved epitopes. The aim of the present study was to assess whether mycobacterial Hsp65 has a direct effect on resident murine peritoneal macrophages, independent of Hsp65-sensitized T lymphocytes. Exposure of peritoneal macrophages from naive C57BL/6 mice to the mycobacterial Hsp65 in vitro induced an enhanced release of tumor necrosis factor alpha (TNF-alpha) and interleukin 6. These cells also produced large amounts of reactive nitrogen intermediates (RNI) and inhibited the intracellular proliferation of Toxoplasma gondii. Small amounts of gamma interferon acted synergistically with Hsp65. Thus, exposure of murine macrophages to Hsp65 results in activation of these cells. The acquisition of these characteristics by peritoneal macrophages occurred in the absence of sensitized T lymphocytes. Addition of anti-TNF-alpha antiserum resulted in an attenuation of the Hsp65-induced release of RNI and toxoplasmastatic activity, indicating that endogenous TNF-alpha is involved in the Hsp65-induced macrophage activation. The conclusion of this study is that in vitro exposure of peritoneal macrophages to the mycobacterial Hsp65 induces the release of proinflammatory cytokines and RNI and results in inhibition of the intracellular proliferation of T. gondii. These effects on murine macrophages occur independently of Hsp65-specific T lymphocytes. The proinflammatory effect of Hsp65 demonstrated in this study suggests that this heat shock protein may play a role in the initiation of inflammation that adds to a non-species-specific resistance in the early stages of infections.

Genetic background and environment contribute synergistically to the onset of autoimmune diseases

Autoimmune diseases result from the breakdown of "self" tolerance. Environmental factors appear to be responsible for triggering this errant immune response, directed against self-tissue determinants, only when a susceptible genetic background is present in an individual. Autoimmune diseases, normally characterized by their association with certain HLA alleles, also share other features: the presence of autoantibodies, autoreactive T lymphocytes, and an intermittent clinical course of exacerbations and remissions. In cases of organ-specific diseases, as well as in cases of multi-system autoimmune diseases, viruses are increasingly implicated as such environmental triggers. Current molecular biology techniques have permitted a fine dissection of the genetic background of susceptible individuals and have enabled a more complete characterization of the immunocompetent cells involved in this autoaggression. Molecular approaches will soon allow us to pinpoint the characteristics of the environmental stimuli, so that protective strategies could be formulated to spare susceptible individuals from their ill effects.

Activation of T cells recognizing self 60-kD heat shock protein can protect against experimental arthritis

Lewis rats are susceptible to several forms of experimental arthritis-induced using heat-killed Mycobacterium tuberculosis (adjuvant arthritis, or AA), streptococcal cell walls, collagen type II, and the lipoidal amine CP20961. Prior immunization with the mycobacterial 65-kD heat shock protein (hsp65) was reported to protect against AA, and other athritis models not using M. tuberculosis, via a T cell-mediated mechanism. Hsp65 shares 48% amino acid identity with mammalian hsp60, which is expressed at elevated levels in inflamed synovia. Several studies have reported cross-reactive T cell recognition of mycobacterial hsp65 and self hsp60 in arthritic and normal individuals. We previously described nine major histocompatibility complex class II-restricted epitopes in mycobacterial hsp65 recognized by Lewis rat T cells. Of these only one, covering the 256-270 sequence, primed for cross-reactive T cell responses to the corresponding region of rat hsp60. Here we have tested each hsp65 epitope for protective activity by immunizing rats with synthetic peptides. A peptide containing the 256-270 epitope, which induced cross-reactive T cells, was the only one able to confer protection against AA. Similarly, administration of a T cell line specific for this epitope protected against AA. Preimmunization with the 256-270 epitope induced T cells that responded to heat-shocked syngeneic antigen-presenting cells, and also protected against CP20961-induced arthritis, indicating that activation of T cells, recognizing an epitope in self hsp60 can protect against arthritis induced without mycobacteria. Therefore, in contrast to the accepted concept that cross-reactive T cell recognition of foreign and self antigens might induce aggressive autoimmune disease, we propose that cross-reactivity between bacterial and self hsp60 might also be used to maintain a protective self-reactive T cell population. This discovery might have important implications for understanding T cell-mediated regulation of inflammation.

Mucosal expression by B7-positive cells of the 60-kilodalton heat-shock protein in inflammatory bowel disease

BACKGROUND/AIMS

Heat-shock protein (Hsp) 60 is an immunodominant antigen of mycobacteria and other microorganisms that is highly homologous to its human counterpart. Hsp60 may provide a link between immunity to invading microorganisms and autoimmune diseases.

METHODS

Expression of Hsp60 was studied by immunohistochemistry in gut resection specimens of patients with Crohn's disease (n = 14), ulcerative colitis (n = 7), acute self-limited colitis (infective type) (n = 5), and controls (n = 9) using the monoclonal antibodies LK1 and LK2.

RESULTS

A strong staining positivity for Hsp60 was observed in numerous mononuclear cells of the mucosa and submucosa in ileum and colon tissue biopsy specimens of patients with Crohn's disease from inflamed and healthy areas. In ulcerative colitis, Hsp60 expression was limited to the mucosa. In biopsy specimens from patients with acute self-limited colitis and controls, Hsp60-positive cells were absent or only present in low numbers and staining intensity was weak. Differentiation between mammalian and bacterial Hsp60 showed expression of the human homologue. Double staining for B7 and Hsp60 showed that Hsp60 was expressed by B7-positive cells.

CONCLUSIONS

Human Hsp60 is strongly expressed by B7-positive antigen-presenting mononuclear cells in the mucosa of patients with inflammatory bowel disease and might play a role in the initiation or maintenance of the inflammatory process.

Joint-derived T cells in rheumatoid arthritis proliferate to antigens present in autologous synovial fluid

The histopathological features of rheumatoid joint-inflammation suggest that an antigen-driven activation of T cells plays a central role in the onset and/or perpetuation of the inflammatory process. However, the disease-associated antigens responsible for the activation of T cells in the joint are unknown. In this project we study the response of IL-2 expanded T-cell lines from the synovial fluid (SF) of rheumatoid arthritis (RA) patients against autologous SF in a proliferation assay. Sixteen out of 32 RA patients were found to have CD4+ T cells that proliferate in response to autologous SF. The presence of T cells able to respond to SF antigens in inflamed joints suggests that these T cells play an active role in the pathogenesis of RA. T cell clones reactive to autologous SF were isolated from SF-derived T-cell lines of two RA patients. All clones were of the CD4+, CD8-, alpha/beta+ phenotype. SF-reactivity of T-cell clones from the DR4/DR12-positive RA patient was restricted via the Dw4 subtype of DR4. SF reactivity of T cells of the DR12/DR15 patient was DP-restricted. Some of the T-cell clones responded specifically to autologous and not to allogeneic SF, whereas others revealed responsiveness against a limited number of allogeneic SF samples. The (restricted) specificity of T cells towards autologous SF antigens is indicative for heterogeneity of the epitopes recognized and argues against ubiquitous nonpolymorphic joint constituents as the relevant antigens recognized by the SF-autoreactive T cells.

Inflamed joints of patients with rheumatoid arthritis contain T cells that display in vitro proliferation to antigens present in autologous synovial fluid. Functional analysis on the basis of synovial-fluid-reactive T-cell clones and lines

The immunopathology of inflamed joints in patients with RA is thought to result from an antigen-driven T-cell response. The antigen(s) responsible for the activation of synovial T cells, however, are as yet unidentified. In this study, we tested SF as a potential source of (auto)antigen(s). Five of 15 IL-2-expanded T-cell lines generated from SF cells of RA patients displayed a proliferative response to autologous SF. Five CD4+CD8-alpha beta TCR+SF-reactive T-cell clones obtained from responder T-cell lines were studied in more detail. Three T-cell clones from one RA patient were found to recognize epitopes in autologous SF in the context of DR4(Dw4), and two T-cell clones of another RA patient responded to autologous SF in the context of the HLA-DPB1*0401 gene product. The two DP-restricted clones and one of the DR-restricted clones did not proliferate to 50 SF samples of other RA patients, whereas the remaining DR-restricted clones responded to one allogeneic sample. Sequence analysis demonstrated that the latter clones expressed identical V beta 6.9 + TCR beta chains. This was also found for the (V beta 19+) DP-restricted clones. Proliferation of SF-reactive T cells was not only obtained with SF of the joint that had contained the T cells, but also with autologous SF of other affected joints. Together, these findings indicate that epitopes able to stimulate synovial T cells differ among RA patients, but may be similar within multiple joints of an individual patient. The presence of T cells able to respond to SF antigens in inflamed joints suggests that these T cells play an active role in the pathogenesis of RA.

Antibodies to 65Kd heat-shock protein were elevated in rheumatoid arthritis

Antibodies to 65Kd heat-shock protein (hsp) of mycobacterium leprae were measured by enzyme-linked immunosorbent assay (ELISA) in the three immunoglobulin classes in paired sera and synovial fluids of patients with rheumatoid arthritis (RA). Titers of anti-hsp antibody were expressed by optical density (OD) values for sera or indexes (OD values divided by amounts of immunoglobulin in each class) for synovial fluids and for their paired sera. Indexes of anti-hsp antibody were higher in synovial fluids than those in sera at 15/18 for IgG, 17/18 for IgA and 16/18 for IgM class. These results suggest the participation of anti-hsp antibodies to synovitis in RA.

T-cell antigen receptors in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic disease of unknown etiology characterized by chronic inflammation mainly in the joints. Several lines of evidence suggest that T cells are involved in the pathogenesis of the disease. RA is associated with certain HLA-DR alleles. Studies analyzing T-cell receptor transcripts in RA have found biased or preferential usage of certain V alpha and/or V beta gene segments by T cells infiltrating the synovial membrane or extravasating into the synovial fluid compared to peripheral blood. In certain patients few T-cell antigen receptor (TCR) clones dominated the infiltrating T cells, suggesting that T cells from the synovial membrane or the synovial fluid comprise oligoclonal populations of T cells. However, other studies have found a polyclonal population of T cells. In interpreting these results the phase of the disease (early vs. late RA), the source of T cells and the limitations of the methods used in these studies should be taken into consideration. However, it appears that synovial T cells comprise oligoclonal populations of T cells and that there is a bias towards particular TCR gene segments, although a specific TCR gene segment in RA has not emerged.

Intestinal expression and cellular immune responses to human heat-shock protein 60 in Crohn's disease

Changes in the intestinal expression of the endogenous human 60-kDa heat-shock protein (HSP60) were investigated in patients with Crohn's disease. HSP60 immunoreactivity was detected in epithelial cells, vascular smooth muscle, and nerve cell bodies of both small and large bowel from patients with Crohn's disease. However, control tissue showed a similar pattern of HSP60 expression. Western blot analysis confirmed that the HSP60 immunoreactivity detected in the intestine corresponded to the 60-kDa HSP. The proliferative response of peripheral blood lymphocytes (PBL) and intestinal intraepithelial lymphocytes (IEL) to recombinant human HSP60 was examined. The results indicate that there was no significant difference in responses between patients with Crohn's disease and controls. Furthermore, there was no increase in the proportion of gamma/delta T cell receptor-bearing T cells in PBL from patients with Crohn's disease cultured for six days in the presence of human HSP60 as compared to control patients. These results suggest that endogenous human HSP60 is unlikely to be a target for an autoimmune response in patients with Crohn's disease.

TCR1+ large granular lymphocyte proliferation in rheumatoid arthritis

The T gamma-lymphoproliferative syndrome is characterized by a proliferation of large granular lymphocytes (LGL). It is often associated with neutropenia, and in 30% of cases with rheumatoid arthritis (RA). Phenotypic analysis has demonstrated that in most cases of RA with T gamma-proliferative disease, the LGL represent T cells with a clonal rearrangement of the alpha/beta T cell receptor (TCR2). Here, three patients with gamma/delta TCR1+ LGL proliferation suffering from long-standing arthritis and neutropenia are described. The first patient with RA showed an expansion of a heterogeneous CD2+ CD16+ CD56- LGL population, of which 30% coexpressed TCR1 with V delta 1 rearrangement. The second patient with ankylosing spondylitis and RA was suffering from proliferation of TCR1+ (V gamma 9-, V delta 1-), CD2+ CD16- CD56- LGL with low coexpression of CD8. The third patient with RA was suffering from a proliferation of TCR1+ (V delta 1+, V gamma 9-) CD4- CD8- CD16- CD56- lymphocytes. On the basis of these unusual findings, the pathogenetic role of TCR1+ T cells in RA is discussed.

IgG3 reactive rheumatoid factor in rheumatoid arthritis: etiologic and pathogenic considerations

Rheumatoid factor (RF) is a polyclonal autoantibody directed against the Fc portion of IgG. Although the role of RF in patients with rheumatoid arthritis (RA) is unclear, immune complexes that form between RF and IgG can activate the classical complement (C) pathway, leading to pathogenic outcomes involving inflammatory events and tissue damage. The specificity of serum RF and RF produced by rheumatoid synovial cells (RSC) is different. Serum RF has specificity for rabbit IgG and human IgG subclasses IgG1, 2, and 4, but binds poorly to IgG3. The affinity of serum RF for IgG Fc is low, having an association constant of 10(4)-10(5) M-1. RSC RF, however, has specificity for human IgG and high avidity for IgG3. Because of this greater specificity and avidity for IgG3, and because RSC RF may be pathogenically more important than serum RF, an important role for IgG3-reactive RF in RA may exist. Binding of RF to IgG may be dependent on the allotype and glycosylation of IgG. Infectious agents present in RA patients may directly or indirectly induce the production of certain RF. In this communication, we review and expand on several observations examining the role of IgG3-reactive RF in RA including: 1) binding differences between RF derived from RSC and serum; 2) glycosylation characteristics of IgG and its interaction with RF; 3) apparent allotype dependent binding of IgG3-reactive RF; and 4) possible relationship between infectious agents and the production of IgG3-reactive RF. Taken together, these observations suggest an important role for IgG3-reactive RF in better understanding the etiology and pathogenesis of RA.

A constitutive 65 kDa chondrocyte protein as a target antigen in adjuvant arthritis in Lewis rats

The autoantigen in adjuvant arthritis in Lewis rats is still unknown despite the knowledge that the 65 kDa mycobacterial heat-shock protein (hsp) is involved in the disease process. T cells and antibodies obtained from rats with adjuvant arthritis respond to chondrocyte membrane antigen(s). In Western blots a 65 kDa chondrocyte membrane protein (CH65) is stained by sera from arthritic rats. In addition, spleen cells from rats with adjuvant arthritis proliferate in vitro to chondrocyte membranes and CH65 as antigens. Furthermore, pretreatment of rats with CH65 or mycobacterial hsp65 but not human hsp60, induces a significant retardation of the onset of adjuvant arthritis in Lewis rats. The data suggest that CH65 is a potential autoantigen involved in the pathogenesis of adjuvant arthritis in Lewis rats.

Induced expression of heat-shock protein on biliary epithelium in patients with primary sclerosing cholangitis and primary biliary cirrhosis

In both primary sclerosing cholangitis and primary biliary cirrhosis it is supposed that immunological mechanisms are involved in the progressive destruction of the bile ducts. The aberrant expression of human leukocyte antigen-DR in the bile ducts of patients with these disorders enables the biliary epithelium to present putative antigens to the surrounding lymphocytes; however, no such antigen has been identified. Heat-shock proteins have been implicated in the pathogenesis of various immunological destructive disorders. Liver biopsy specimens from patients with primary biliary cirrhosis (n = 10) and primary sclerosing cholangitis (n = 13) were compared with those from patients with chronic hepatitis C infection (n = 5) and alcoholic cirrhosis (n = 4) and from normal controls (n = 6). Liver sections were investigated by means of immunohistochemical study using a mouse monoclonal antibody, ML30, directed against the 65-kD heat-shock protein of Mycobacterium, with monoclonal antibody against human leukocyte antigen-DR and with the monoclonal antibody Identi-Tr TCR delta 1, which recognizes a determinant on the delta-chain of the gamma/delta form of the human T-cell receptor. Human leukocyte antigen-DR expression was found on the biliary epithelium of all primary sclerosing cholangitis and primary biliary cirrhosis patients but not on bile ducts from patients with alcoholic cirrhosis or chronic hepatitis C infection or those from normal controls. The biliary epithelium reacted with ML30 in 9 of 10 primary biliary cirrhosis patients and in all primary sclerosing cholangitis patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Lactoferrin triggers in vitro proliferation of T cells of Lewis rats submitted to mycobacteria-induced adjuvant arthritis

We have recently reported antigenic (B-cell) cross-reactivity between the mycobacterial 65 kDa heat shock protein (hsp65) and human lactoferrin (LF) and we suggested that this cross-reactivity might have a role in mycobacteria-associated autoimmune disease. Here, we have searched for anti-LF T-cell reactivity in Lewis rats submitted to a mycobacteria-triggered autoaggressive disorder (adjuvant arthritis, AA), an autoimmune disorder characterized by high anti-hsp65 reactivity. We have quantified the in vitro proliferative response to LF of lymph node and spleen cells of Lewis rats killed 9, 14 and 21 days after the immunization with the AA-triggering, mycobacteria-containing adjuvant (complete Freund's adjuvant, CFA). We found that LF induced significant proliferation of lymph node T cells of rats undergoing AA. This T-cell proliferation was not as marked as the one provoked by hsp65; it was, nevertheless, significantly higher (P < 0.05) than that produced by a non-arthritogenic antigen (i.e. albumin). T cells from naive or mineral oil (incomplete Freund's adjuvant, IFA) injected rats did not respond to LF or hsp65. These data indicate that LF may work as an accessory stimulatory factor of the T-cell autoreactivity associated with mycobacteria-induced arthritis.

Expression of the 60 kDa heat shock protein in normal and inflamed liver

The 60 kDa heat shock proteins (HSP 60) have been well conserved throughout evolution and are highly immunogenic. Cross-reactivity between bacterial and mammalian HSP 60 is considered a likely mechanism in the pathogenesis of autoimmune diseases. T cell and B cell reactivity to HSP 60 is found in patients with rheumatoid or juvenile arthritis, and the expression of HSP 60 in the inflamed joint is found to be increased. In this study the presence of HSP 60 was demonstrated in normal and inflamed lives. HSP 60 was found to be predominantly expressed in hepatocytes and Kupffer cells, and mainly localized in mitochondria. Heat stress in the form of a 1 h incubation at 42 degrees C increased HSP 60 expression. The expression of HSP 60 in chronic active hepatitis was found to be markedly increased, with predominant expression in areas of inflammatory infiltrates. This increased expression in the inflamed liver was found both in viral and autoimmune hepatitis. High expression of HSP 60 in chronic active hepatitis was entirely due to self (i.e. human) HSP 60; no additional bacterial HSP 60 could be detected. Increased expression of HSP 60 in chronic active hepatitis suggests that immune reactions to HSP 60 may play a role in the immunopathogenesis and perpetuation of chronic inflammatory liver disease.