Heat shock proteins in autoimmune disease. From causative antigen to specific therapy?

Effects of oral and subcutaneous administration of HSP60 on myeloid-derived suppressor cells and atherosclerosis in ApoE-/- mice

HSP60 has been proved to be closely related to atherosclerosis due to its antigenicity. To determine this antigenicity effect, the ApoE-/- mice were fed with western-type diet and HSP60 was administrated orally or subcutaneously (SC) for potential vaccine against atherosclerosis. Here, we observed the ApoE-/- mice with oral HSP60 administration group showed a significant reduction in plaque size at the aortic root; accompanied by increased MSDCs (CD11b⁺Gr1⁺) in peripheral blood and spleen which was mostly composed of M-MDSCs (CD11b⁺LY6G^-LY6C^high), and increased plasma IL-10 and splenic Foxp3, Arg1, iNOS mRNA as well as decreased plasma IFN-γ and splenic T-bet mRNA compared to control group. Surprisingly, ApoE-/- mice with subcutaneous HSP60 administration group showed contrary results and their MDSCs were mostly composed of G-MDSCs (CD11b⁺LY6G⁺LY6C^low). As expected, both PBS-oral and PBS-SC groups showed no significant effects on both the immune response and atherosclerotic plaque formation. In contrast, subcutaneous administration of HSP60 causes the opposite response. Thus, we propose the proper method for administering HSP60 as a new immunologic agent for prevention and treatment of atherosclerosis.

The possible role of HSPs on Behçet's disease: a bioinformatic approach

Current evidence lends increasing support to immunoinflammatory mechanisms as one of the prime pathogenic processes involved in the development and progression of Behçet's disease (BD). It has been observed that most human beings have cellular and humoral reactions against microbial heat shock proteins (HSPs). The observation that eukaryotic and prokaryotic HSPs have high sequence similarity promoted the hypothesis that HSPs might be potential candidates for molecular mimicry and could act as potentially dangerous autoantigens. In this study, using bioinformatics tools, we examined the hypothesis that HSPs (evolutionarily conserved proteins), which are present in pathogenic and commensal organisms and their hosts, provide the stimulus that initiates BD in susceptible individuals. In this regards, the nucleotide and amino acid sequences of the human HSP 60 kDa and bacterial HSP 60 kDa deposited in the NCBI and PDB databases were subjected to analysis using bioinformatics tools, including The CLC Sequence Viewer and MEGA softwares. These data showed that the sequence homology between bacterial and self HSPs (leading to cross-reactivity and molecular mimicry phenomenon) may be associated with the development of the disease; and suggesting that microbial HSPs, which cross-react with host tissues and elicit significant immune responses are possible pathogenetic agents involved in the development and progression of BD.

Effects of parental effort on blood stress protein HSP60 and immunoglobulins in female blue tits: a brood size manipulation experiment

1. Physiological stress in animals may impose a limit for investment in current reproduction in the wild. A brood manipulation experiment was conducted in a population of blue tits Cyanistes caeruleus to study the effect of parental effort on changes in two types of proteins related with stress: the blood stress protein HSP60 and the plasma immunoglobulins. 2. Levels of HSP60 were reduced across the experiment for females attending reduced broods, and females attending enlarged broods experienced a reduction of immunoglobulin levels. Moreover, the overall changes in the levels of both proteins were positively related. 3. By controlling for the change in immunoglobulin levels we found an increase in HSP60 for females in the enlarged treatment, presumably to offset deleterious effects derived from increased effort. 4. Maternal effort was able to partially compensate for the effect of treatment as nestlings did not differ in mass and levels of immunoglobulins and HSP60 among treatments. 5. Physiological stress as reflected in stress and immunoglobulin proteins may limit maternal effort in breeding blue tits.

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

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

Helicobacter pylori infection in connective tissue disorders is associated with high levels of antibodies to mycobacterial hsp65 but not to human hsp60

BACKGROUND

To investigate whether the Helicobacter pylori status influences levels of antibodies against mycobacterial heat shock protein (hsp) 65 and human hsp60 in systemic autoimmune diseases and to study the concentration of anti-H. pylori antibodies in autoimmune patients and healthy controls.

MATERIALS AND METHODS

Antibodies against human heat-shock protein hsp60, mycobacterial heat-shock protein hsp65 were analyzed by ELISA. Anti-Helicobacter antibodies were determined by enzyme immunoassay.

RESULTS

There was a markedly higher prevalence of H. pylori infection in undifferentiated connective tissue disease (82%) (n = 33) and systemic sclerosis (78%) (n = 55) but not in systemic lupus erythematosus (n = 49), polymyositis/dermatomyositis (n = 14), rheumatoid arthritis (n = 21) or primary Raynaud's syndrome (n = 26) compared with controls (59%) (n = 349). In autoimmune diseases H. pylori infection was associated with elevated levels of antihsp65 (p =.008) but not of antihsp60. Anti-hsp65 levels were significantly higher in H. pylori-infected (n = 129) than in uninfected patients (n = 69) (p =.0007).

CONCLUSIONS

These findings indicate that in autoimmune diseases the infection with the H. pylori bacterium is associated with increased concentration of antimycobacterial hsp65.

The identification of a common pathogen-specific HLA class I A*0201-restricted cytotoxic T cell epitope encoded within the heat shock protein 65

Bacterial antigens recognized by CD8(+) T cells in the context of MHC class I are thought to play a crucial role in protection against pathogenic intracellular bacteria. Here, we demonstrate the induction of HLA-A*0201-restricted CD8(+) T cell responses against six new high-affinity HLA-A*0201-binding CTL epitopes, encoded within an immunodominant and highly conserved antigen of Mycobacteria, the heat shock protein 65 (hsp65). One of these epitopes, Mhsp65(9(369)), is identical in a large number of pathogenic bacteria, and is recognized in a CD8-independent fashion. Mhsp65(9(369)) could be presented by either mycobacterial hsp65-pulsed target cells or BCG-infected macrophages. Interestingly, T cells specific for this epitope did not recognize the corresponding human hsp65 homologue, probably due to structural differences as revealed by modeling studies. Furthermore, in vitro proteasome digestion analyses show that, whereas the mycobacterial hsp65 epitope is efficiently generated, the human hsp65 homologue is not, thus avoiding the induction of autoreactivity. Collectively, these findings describe high-affinity HLA class I-binding epitopes that are naturally processed and are recognized efficiently by MHC class I-restricted CD8(+) T cells, providing a rational basis for the development of subunit vaccine strategies against tuberculosis and other intracellular infectious diseases.

Humoral immune response directed against LEDGF in patients with VKH

Vogt-Koyanagi-Harada disease is an autoimmune systemic disorder. In Vogt-Koyanagi-Harada disease, inflammatory disorders occur in multiple organs containing melanocytes, including uvea (resulting in acute bilateral panuveitis), skin (resulting in vitiligo and alopecia), central nervous system (resulting in meningitis) and inner ears (resulting in hearing loss and tinnitus). These inflammatory aspects are attributed to the destruction of melanocytes through immunological mechanisms. Studies have been carried out to elucidate the exact etiology and target autoantigen in Vogt-Koyanagi-Harada disease, but much remains to be investigated. Identification of target autoantigen is important to understand the etiology of autoimmune diseases, and for development of antigen-specific immuno-modulation therapy. To identify the target autoantigens in Vogt-Koyanagi-Harada disease, we made use of an immunoscreening of a bovine uveal cDNA expression library with serum samples obtained from patients with Vogt-Koyanagi-Harada disease. We identified an immunoreactive cDNA clone that encodes bovine lens epithelium derived growth factor. mRNA of human lens epithelium derived growth factor was determined by reverse transcription-polymerase chain reaction and it was expressed in human uvea, retina and melanocytes. Immunoglobulin G (IgG) autoantibodies were quantitated in an enzyme-linked immunosorbent assay, using recombinant human lens epithelium derived growth factor. The prevalence of IgG anti-lens epithelium derived growth factor autoantibodies in patients with Vogt-Koyanagi-Harada disease was significantly higher than that in healthy controls (66.7% versus 21.6%, P<0.001). On the other hand, the prevalence of the autoantibody in patients with panuveitis of other etiology, Behçet's disease and sarcoidosis, was almost same as that in healthy controls. These results suggest that the humoral immune response agonist lens epithelium derived growth factor is not a mere secondary phenomena caused by uveal tissue damage.

Physiological and haematological consequences of a novel parasite on the red-rumped swallow Hirundo daurica

Parasite virulence has been hypothesised to increase with the degree of host sociality because highly social hosts have a greater probability of encountering horizontal transmission of parasites and experiencing infections with multiple strains of the same parasites than do solitary hosts. As compared with the defences of closely related social host species, we predicted that solitary hosts should have relatively weak defences against parasites, thus being relatively more affected when parasitised by a novel parasite. We tested this prediction by either experimentally infesting 12 nests of the solitarily nesting red-rumped swallow Hirundo daurica with 50 individuals of the generalist martin bug Oeciacus hirundinis or by fumigation of nine nests. Nestlings 13 days old from the parasite addition group experienced increased mortality, attained lower body mass and tended to have shorter tarsi compared to nestlings from fumigated nests. Surprisingly, nestlings from the parasite addition group had higher packed cell volume (cellular fraction of blood) and lower levels of heat shock proteins (HSP60) than nestlings from the fumigation group. A measure of immunocompetence was not significantly affected by treatment, but its magnitude was positively related to packed cell volume and negatively related to level of HSP60. Solitary hosts like the red-rumped swallow have weak immune responses and low levels of heat shock proteins when infested with ectoparasites while highly social hosts have strong immune responses and high levels of heat shock proteins when infested. These findings partially support the hypothesis that potential host species with weak defences are more susceptible to infection and the deleterious effects of evolving parasites than potential hosts with strong defences.

Identification of a novel autoantigen UACA in patients with panuveitis

To identify the target autoantigens in Vogt-Koyanagi-Harada disease, we made use of an immunoscreening of a bovine uveal cDNA expression library with serum samples obtained from patients with Vogt-Koyanagi-Harada disease. We identified a novel bovine antigen and homologous human autoantigen and designated it as UACA (uveal autoantigen with coiled coil domains and ankyrin repeats). mRNA of human UACA is expressed most abundantly in skeletal muscles and in various human tissues, including choroid, retina, and epidermal melanocytes. IgG autoantibodies were quantitated in an ELISA, using recombinant C-terminal 18.0% fragment of human UACA. The prevalence of IgG anti-UACA autoantibodies in patients with panuveitis (Vogt-Koyanagi-Harada disease, Behçet's disease, sarcoidosis) was significantly higher than that in healthy controls (19.6-28.1% vs 0%, P < 0.05) indicating that autoimmunity directed against UACA is a common phenomenon in these diseases.

Distribution of heat shock proteins in eutopic and ectopic endometrium in endometriosis and adenomyosis

OBJECTIVE

To evaluate the pathophysiologic role of heat shock proteins and to examine the effect of danazol on these proteins in patients with endometriosis and adenomyosis.

DESIGN

Immunohistochemical identification of human heat shock proteins 27, 60, and 70 in endometrial glandular cells identified using monoclonal antibodies.

SETTING

Department of obstetrics and gynecology in a university hospital.

PATIENT(S)

Subjects were 119 women with documented endometriosis or adenomyosis. The subjects were divided into three groups: fertile control (n = 38), with 14 in the proliferative phase and 24 in the secretory phase; endometriosis (n = 38); and adenomyosis (n = 43), including 33 who underwent hysterectomy and 10 treated with danazol.

MAIN OUTCOME MEASURE(S)

Staining of glandular cells by semiquantitative immunostaining (evaluation nomogram) score.

RESULT(S)

Significantly increased expression of heat shock protein 27 was noted in eutopic endometrium from patients with endometriosis and adenomyosis as compared with controls, regardless of the menstrual phase. The scores for heat shock protein 27 and heat shock protein 70 in the ectopic endometrium of patients with endometriosis were low compared with those in eutopic endometrium, whereas in adenomyosis, the scores were similar to those of eutopic endometrium. After treatment with danazol, the expression of heat shock proteins returned to control levels.

CONCLUSION(S)

We suggest that abnormally increased expression of heat shock proteins plays a role in the pathophysiology of endometriosis and adenomyosis.

A T helper cell 2 (Th2) immune response against non-self antigens modifies the cytokine profile of autoimmune T cells and protects against experimental allergic encephalomyelitis

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease of the central nervous system (CNS), and the most commonly used experimental model for multiple sclerosis. It is mediated by autoreactive T cell clones exhibiting a T helper cell (Th) 1 cytokine profile. Nonencephalitogenic T lymphocytes specific for self or exogenous antigens have been found to suppress encephalitogenic T cell responses and to protect against autoimmune disease. The mechanisms by which exogenous antigens modulate autoimmunity are not fully understood. In this study, we tested the hypothesis that a Th2-type immune response against an exogenous, nonself antigen, keyhole limpet hemocyanin (KLH), by releasing IL-4 in the microenvironment, could shift the cytokine profile of encephalitogenic T cells from an inflammatory Th1 to a protective Th2 type. SJL/J mice were preimmunized with the KLH in incomplete Freund's adjuvant to induce a population of Th2 memory cells that would be expected to release Th2 cytokines when activated by the specific antigen at the time of EAE induction. Four weeks later, mice received an encephalitogenic challenge containing guinea pig myelin in complete Freund's adjuvant with or without KLH. All KLH primed animals not receiving the exogenous antigen at the time of EAE induction developed a severe clinical disease indistinguishable from control mice not KLH primed. In contrast, animals preimmunized and challenged with the encephalitogenic inoculum containing KLH showed either no, or markedly reduced, clinical signs. Enzyme-linked immunospot analysis demonstrated that KLH-specific T cells in the primed mice were producing IL-4 characteristic of Th2 cells. In the KLH-primed and restimulated mice, the cytokine profile of the autoreactive, myelin basic protein-specific T cells was shifted from an inflammatory Th1 towards a protective Th2 type. We infer that the presence of IL-4 secreted by KLH-specific memory Th2 cells in the lymphoid system microenvironment in which the autoreactive T cells were engaged by the encephalitogenic stimulus were able to bias their cytokine profile towards a protective Th2 phenotype. This interpretation is supported by the observation that the protective effect of preimmunization with KLH was overcome by rm-IL-12, which inhibited the production of IL-4 by the Th1 cells and biased the autoimmune response to a predominantly Th1 type. Since IL-4 mRNA could not be detected by reverse transcriptase PCR in the CNS, the protective effect was inferred to be mediated by Th2 cells in the lymphoid system, and not the target organ. We conclude that exogenous, nonself antigens that can induce Th2 responses, can modify the cytokine environment sufficiently to alter the cytokine phenotype of inflammatory, autoreactive T cell clones, and ultimately, to provide significant protection against EAE and possibly other T cell-mediated autoimmune diseases.

Comparison of anti-heat shock protein 70 (anti-hsp70) and anti-68-kDa inner ear protein in the sera of patients with Meniere's disease

The 68-kDa antigen detected in the sera of patients with autoimmune inner ear disease is known to represent the highly inducible heat shock protein 70 (hsp70). To evaluate the existence of anti-hsp70 in the sera of patients with Meniere's disease and to develop a more reliable method to detect this antibody, the sera of patients and controls were examined. Bovine kidney (MDBK) cells were cultured and some of them were heat shocked. Proteins in the cells were separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Sera were reacted simultaneously with the blots of non-heat-shocked cells and heat-shocked cells. The serum was considered positive if the band in the 70-kDa location was denser in the lane with heat-shocked cells relative to non-heat-shocked cells. Presence of the antibody against the 68-kDa protein was compared with the result of immunoblotting with MDBK cells. In immunoblotting with MDBK cells, 33.3% of patients with Meniere's disease had anti-hsp70, while in the control group, only 5% had this antibody. Of the 60 cases, 13 were positive against both hsp70 and the 68-kDa protein, whereas 7 were positive only against hsp70 and 6 only against the 68-kDa protein. These differences appeared to result from the greater sensitivity of the differential anti-hsp assay and from difficulties in interpreting the results in blots with bovine inner ear extracts because of faint, broad, or overlapping multiple bands. Quite a number of patients with Meniere's disease have anti-hsp70, and it may be indicative of an immune etiology of the disease. The Western blot using heat-shocked and non-heat-shocked cells could be a reliable method to detect this antibody.

Imogen 38: a novel 38-kD islet mitochondrial autoantigen recognized by T cells from a newly diagnosed type 1 diabetic patient

Cell-mediated autoimmune attack directed against islet proteins of approximately 38 kD in size has been associated with type 1 diabetes. A novel murine cDNA encoding an antigen of this size was cloned using a screening procedure based on the proliferative response of a human diabetic T cell clone (1C6) to a recombinant antigen epitope library. Membrane preparations from COS 7 cells transfected with the full-length 1,267-bp cDNA elicited a proliferative response from the reporter T cells comparable to that of the defined peptide epitope and native insulinoma antigen. In vitro translation and transfection experiments suggested that the protein is initially synthesized as a 44-kD protein and then processed to the native 38-kD form through the proteolytic removal of a 54-aa NH2-terminal mitochondrial targeting sequence. Differential centrifugation, Percoll density gradient centrifugation, and immunofluorescence studies confirmed localization of the antigen to mitochondria. Northern blot, Western blot, and 1C6 T cell proliferation assays showed that, although imogen 38 was more highly expressed in beta cell than alpha cell lines, it was also present in other tissues. It is concluded that imogen 38 may be a target for bystander autoimmune attack in diabetes rather than a primary autoantigen.

Infection, autoimmunity and autoimmune disease

Studies of the immune response of mammals to infectious agents have revealed that members of the hsp60 and hsp 70 family are highly immunodominant. Given their high conservation during evolution this was surprising, because of the apparent risk of triggering of autoimmunity and autoimmune disease during the defense of a mammal against infection. However, detailed studies of the immune responses to HSP in models of autoimmune diseases in animals resulted in a change of the view that autoimmunity necessarily leads to autoimmune disease. It has been found that modulation of autoimmunity to HSP is one way to prevent autoimmune disease. At least in some cases even treatment of autoimmune diseases by immunization with heat shock protein appears feasible. This was shown in adjuvant arthritis in Lewis rats and insulin dependent diabetes in NOD mice. Hsp60 and hsp70 are ubiquitous proteins. Their involvement in regulatory loops of autoimmunity may serve as basis for the development of strategies, to prevent and/or treat autoimmune diseases even without knowledge of the causative (auto-)antigen.

Elevated levels of heat-shock protein 70 (HSP70) in the mononuclear cells of patients with non-insulin-dependent diabetes mellitus

Increased free radicals and reduced levels of antioxidants have been reported in diabetes mellitus. Since heat-shock protein 70 (HSP70) is a stress-induced protein and is suggested to play a protective role against oxidative stress, we have investigated whether HSP7O acts as one of the defense systems against this stress. We separated mononuclear cells from diabetic patients (N=12) and age- and sex-matched healthy controls (N =12), and detected HSP70 by western blot analysis. The results were expressed by the ratio of the density determined by laser densitometry, to that of 10 mu g of purified HSP70. HSP70 levels in the mononuclear cells of diabetic patients (0.78 + or- 0.56) were significantly high, compared with healthy subjects (0.43 + or - 0.23) (P < 0.05). No correlation was found between HSP7O and hemoglobin A1c, fasting plasma glucose, duration of diabetes or diabetic complications except age. A negative correlation was found between HSP70 and age (r = -0.658, P < 0.05). These results suggest that HSP70 levels in the mononuclear cells are elevated reflecting increased oxidative stress in patients with diabetes.

Self and non-self antigen in diabetic autoimmunity: molecules and mechanisms

In this article, we have summarized current facts, models and views of the autoimmunity that leads to destruction of insulin-producing beta-cells and consequent Type 1 (insulin-dependent) diabetes mellitus. The presence of strong susceptibility and resistance gene loci distinguishes this condition from other autoimmune disorders, but environmental disease factors must conspire to produce disease. The mapping of most of the genetic risk (or disease resistance) to specific alleles in the major histocompatibility locus (MHC class II) has direct functional implications for our understanding of autoimmunity in diabetes and directly implies that presentation of a likely narrow set of peptides is critical to the development of diabetic autoimmunity. While many core scientific questions remain to be answered, current insight into the disease process is beginning to have direct clinical impact with concerted efforts towards disease prevention or intervention by immunological means. In this process, identification of the critical antigenic epitopes recognized by diabetes-associated T cells has achieved highest priority.

Immuno-gold electron microscopical detection of heat shock protein 60 (hsp60) in mitochondria of rat hepatocytes and myocardiocytes

We characterize the specificity of a polyclonal antibody against heat shock protein 60 (hsp60) and present an application for ultrastructural localization studies of this protein. The antibody was obtained from an IgG fraction (AB 121) originally raised against the calcium binding protein calsequestrin by immunoabsorption on isolated rat liver hsp60. As shown by partial N-terminal amino acid sequence analysis of immunoprecipitated proteins AB 121 contained reactivities against hsp60, calsequestrin and the glycoprotein fetuin. In rat heart AB 121 recognized calsequestrin and hsp60. In human and rat liver the only reacting protein was hsp60. In rat erythrocytes the antibody bound to 61 kDa and 58 kDa isoforms of fetuin. According to published data no amino acid sequence homologies nor common motifs are found between calsequestrin, hsp60 and fetuin. As the first application the anti-hsp60 antibody was used for immuno-gold electron microscopical localization of hsp60: in myocardiocytes and hepatocytes of the rat strong labelling was obtained exclusively in mitochondria. No extramitochondrial structures were labelled. The specificity of the antibody and its ability to be visualized by immuno-gold electron microscopy offers the possibility to study the expression of this protein in the liver and in other organs. Possible clinical applications of these studies are discussed, since hsp60 could be a target antigen of autoantibodies in diseases such as autoimmune hepatitis, primary sclerosing cholangitis or primary biliary cirrhosis.

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.

Bacterial shock responses

Bacteria, very early in their history, developed protective 'shock responses', triggered when the organism was exposed to some acute environmental stress. At the heart of each response was the accelerated synthesis of both general and stimulus-specified intracellular proteins. So successful was this strategy that its basic mechanism and several of its components were highly conserved throughout the course of evolution. This was particularly true of heat shock proteins whose universal distribution has both good and bad consequences for man.