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PubMed2004

Expression of heat shock protein in broiler embryo tissues after acute cold or heat stress.

This study evaluated the expression of heat shock protein 70 kD (hsp70) in broiler chicken embryos subjected to cold (Experiment I) or high incubation temperature (Experiment II). In each experiment, fertile eggs were distributed in three incubators kept at 37.8 degrees C. At day 13 (D13), D16, and D19 of incubation, the embryos were subjected to acute cold (32 degrees C) or heat (40 degrees C) for 4-6 hr. Immediately after cold or heat exposure, samples from the liver, heart, breast muscle, brain, and lungs of 40 embryos were taken per age and treatment (control or stressed embryos). A tissue pool from 10 embryos was used as 1 replication. The levels of hsp70 in each tissue sample was quantified by Western blot analysis. The data were analyzed in a 3 x 2 factorial arrangement of treatments with four replications. hsp70 was detected in all embryo tissues, and the brain contained 2- to 5-times more hsp70 protein compared to the other tissues in either cold or heat stressed embryos. hsp70 increases were observed in the heart and breast muscle of cold stressed embryos at D16 and D19, respectively. Heat stressed embryos showed an increase of hsp70 in the heart at D13 and D19, and in the lung at D19 of incubation. Younger embryos had higher hsp70 synthesis than older embryos, irrespective of the type of thermal stressor. The results indicate that the expression of hsp70 in broiler chicken embryos is affected by cold and heat distress, and is tissue- and age-dependent.

Animals↗
PubMed2005

Role of trehalose and heat in the structure of the C-terminal activation domain of the heat shock transcription factor.

The heat shock transcription factor (HSF) is the primary transcriptional regulator of the heat shock response in eukaryotes. Saccharomyces cerevisiae HSF1 has two functional transcriptional activation domains, located N- and C-terminal to the central core of the protein. These activation domains have a low level of transcriptional activity prior to stress, but they acquire a high level of transcriptional activity in response to stresses such as heat. Previous studies on the N-terminal activation domain have shown that it can be completely disordered. In contrast, we show that the C-terminal activation domain of S. cerevisiae HSF1 does contain a certain amount of secondary structure as measured by circular dichroism (CD) and protease resistance. The alpha-helical content of the domain can be increased by the addition of the disaccharide trehalose but not by sucrose. Trehalose, but not sucrose, causes a blue shift in the fluorescence emission spectra, which is suggestive of an increase in tertiary structure. Trehalose, which is known to be a chemical chaperone, also increases proteases' resistance and promotes heat-induced increases in alpha-helicity. The latter is particularly intriguing because of the physiological role of trehalose in yeast. Trehalose levels are increased dramatically after heat shock, and this is thought to protect protein structure prior to the increase of heat shock protein levels. Our results suggest that the dramatic changes in S. cerevisiae HSF1 transcriptional activity in response to stress might be linked to the combined effects of trehalose and elevated temperatures in modifying the overall structure of HSF1's C-terminal activation domain.

Animals↗
PubMed2001

Mutation of amino acids 566-572 (KKKVLDK) inhibits nuclear accumulation of heat shock protein 72 after heat shock.

Heat shock protein (HSP) 72 translocates from the cytoplasm to the nucleus in response to a wide variety of stresses, including heat shock and tissue ischemia. It is thought that this concentration of HSP72 in the nucleus with stress is part of the protein's protective response. Therefore, further understanding of the regulation of this response would be of interest. The signals regulating HSP72's nuclear localization have not been completely defined. Previously, we observed that mutation of amino acids 246-251 (KRKHKK) reduced nuclear accumulation of HSP72 and that a KRKHKK-EGFP (enhanced green fluorescent protein) fusion protein concentrated in the nucleoli. In examining HSP72 for other potential nuclear localization signals, we identified an additional sequence, KKKVLDK, amino acids 566-572, that might effect nuclear accumulation. We now report that mutation of KKKVLDK inhibited nuclear concentration of HSP72 following heat shock, and the fusion protein KKKVLDK-EGFP concentrated in the nucleus. Cells overexpressing the KKKVLDK mutant showed reduced resistance to heat shock. Mutation of KKKVLDK and KRKHKK abolished nuclear accumulation of HSP72 and reduced cell viability following heat shock to a greater extent than mutation of either site alone. These findings suggest that these two sequences, KRKHKK and KKKVLDK, have complementary function(s) in cellular protection after heat shock.

Adenosine Triphosphate↗
PubMed1999

Mutations in the Schizosaccharomyces pombe heat shock factor that differentially affect responses to heat and cadmium stress.

Heat shock factor (hsf) is the transcriptional activator that governs the transcriptional response of eukaryotic cells to stressful conditions. The structure and regulation of hsf is highly conserved. We describe deletion mutations in hsf+ that alter the ability of Schizosaccharomyces pombe to respond to different stressful conditions. One mutation causes increased sensitivity to cadmium while maintaining near normal sensitivity to heat stress, while another mutation confers increased sensitivity to heat stress but retains normal sensitivity to cadmium. Despite the differential sensitivity of these two strains to cadmium and heat stress, the mutant hsf proteins in each strain were activated by both cadmium and heat. However, we found that these mutations differentially affected the ability of hsf to activate different promoters: one mutated hsf activated the ssp1+ gene better than the wis2+ gene following either stress, while the other mutated hsf activated wis2+ better than ssp1+. We propose that the differential ability of strains that contain these mutant hsfs to survive cadmium and heat stress is not caused by differences in activation of hsf, but is caused instead by differential abilities of the mutant hsfs to activate the appropriate sets of genes needed for survival.

Binding Sites↗
PubMed1997

Defective herpes simplex virus vectors expressing the rat brain stress-inducible heat shock protein 72 protect cultured neurons from severe heat shock.

Recently, preinduction of the heat shock response has been shown to protect CNS neurons undergoing various stressful insults, e.g., heat, ischemia, or exposure to excitotoxins. However, it is not known which of the proteins induced by the heat shock response mediate the protective effects. Previous correlative evidence points to a role for the highly stress-induced 72-kDa heat shock protein (hsp72). However, it is not known whether hsp72 expression alone can protect against a range of acute neuronal insults. We constructed a herpes simplex virus-1 vector carrying the rat brain stress-inducible hsp72 gene and the Escherichia coli lacZ (marker) gene. Infection with the vector caused hippocampal neurons to coexpress hsp72 and beta-galactosidase. Infection with a control vector led to marker gene expression only. Overexpression of hsp72 protected cultured hippocampal neurons against a heat shock but not against the metabolic toxin 3-nitropropionic acid or the excitotoxin glutamate. This is the first published report of protection following heat shock protein transfection in CNS neurons.

Animals↗
PubMed1995

Heat-inducible DNA binding of purified heat shock transcription factor 1.

The heat-induced expression of heat shock proteins, called the cellular stress response, is mediated by heat shock transcription factor 1 (HSF1). HSF1 exists in unstressed cells in an inactive form, which is converted to the DNA binding from upon exposure of cells to elevated temperature. We have developed a protocol for isolation of the non-DNA binding form of recombinant mouse HSF1, involving expression and affinity purification of HSF1 as a fusion with the glutathione S-transferase protein in Escherichia coli, followed by specific protease cleavage to release pure HSF1 protein. We report here that the purified inactive HSF1 can be converted to the DNA binding form by heat treatment in vitro. Chemical cross-linking analysis demonstrates that this conversion is accompanied by oligomerization of HSF1 from a monomeric to a trimeric native structure, similar to that observed for HSF1 in heat-shocked cells. These results indicate that elements residing in the HSF1 polypeptide are sufficient both for maintenance of this factor in the non-DNA binding from and for its heat-induced conversion to the DNA binding form and support a role for HSF1 as the "molecular thermostat" in eukaryotic cells, which senses adverse environmental conditions and activates the cellular stress response.

Animals↗
PubMed2002

Gene expression of 70 kDa heat shock protein of Candida albicans: transcriptional activation and response to heat shock.

CaHSP70 (70 kDa heat shock protein) is a highly immunogenic protein of Candida albicans. We have studied heat shock-induced expression of the CaHSP70 gene under germ tube-inductive and non-inductive conditions. The CaHSP70 upstream regulatory region was cloned and sequenced. It contains at least three heat shock elements (HSEs), specific DNA sequences that are bound by the heat shock transcription factor (HSF), and one stress response element (STRE), which is an upstream activator sequence (UAS) that causes transcription activation under stress. The binding of HSF to HSE in the CaHSP70 promoter region is constitutive, although the mobility of protein/DNA complexes is altered after heat shock. The CaHSP70 promoter was cloned into a lacZ reporter plasmid, and was able to respond to heat shock in C. albicans as well as in Saccharomyces cerevisiae.

Amino Acid Sequence↗
PubMed2001

Roles of the heat shock transcription factors in regulation of the heat shock response and beyond.

The heat shock response, characterized by increased expression of heat shock proteins (Hsps) is induced by exposure of cells and tissues to extreme conditions that cause acute or chronic stress. Hsps function as molecular chaperones in regulating cellular homeostasis and promoting survival. If the stress is too severe, a signal that leads to programmed cell death, apoptosis, is activated, thereby providing a finely tuned balance between survival and death. In addition to extracellular stimuli, several nonstressful conditions induce Hsps during normal cellular growth and development. The enhanced heat shock gene expression in response to various stimuli is regulated by heat shock transcription factors (HSFs). After the discovery of the family of HSFs (i.e., murine and human HSF1, 2, and 4 and a unique avian HSF3), the functional relevance of distinct HSFs is now emerging. HSF1, an HSF prototype, and HSF3 are responsible for heat-induced Hsp expression, whereas HSF2 is refractory to classical stressors. HSF4 is expressed in a tissue-specific manner; similar to HSF1 and HSF2, alternatively spliced isoforms add further complexity to its regulation. Recently developed powerful genetic models have provided evidence for both cooperative and specific functions of HSFs that expand beyond the heat shock response. Certain specialized functions of HSFs may even include regulation of novel target genes in response to distinct stimuli.

Amino Acid Sequence↗
PubMed2002

Circulating heat shock protein and heat shock protein antibody levels in established hypertension.

OBJECTIVE: Serum Hsp60 and anti-Hsp65 antibody levels are raised in subjects with borderline hypertension, and there is an association between circulating Hsp60 levels and early atherosclerosis. Given the recognized relationship between hypertension and atherosclerosis, this study determined heat shock protein and heat shock protein antibody levels in subjects with established hypertension. METHODS: Samples from 111 men with hypertension were obtained from the European Lacidipine study on Atherosclerosis and samples from 75 normotensive controls were taken from a population-screening programme (diastolic pressure, 95 and 80 mmHg, respectively). Hsp60, Hsp70 and anti-human Hsp60, anti-human Hsp70 and anti-mycobacterial Hsp65 antibody levels were measured by enzyme immunoassay. Intima-media thickness (I-M) and the presence of carotid atherosclerosis were determined by ultrasonography. RESULTS: Hsp60, Hsp70 and anti-Hsp60 antibody levels in hypertension were similar to those in normotensive controls, whereas anti-Hsp70 and anti-Hsp65 antibody levels were elevated ( 0.001). Hsp60 levels and atherosclerosis were not associated. Anti-Hsp70 and anti-Hsp65 antibody levels were both associated with hypertension, independently of age, smoking habits and blood lipids. CONCLUSIONS: This study demonstrates elevated levels of selected heat shock protein antibodies in subjects with hypertension. Although the association between heat shock protein antibody levels and human cardiovascular stress/disease appears to be robust, the relationship of the latter with heat shock protein levels is more complex. Further studies are required before the factors inducing, and the clinical significance of, circulating heat shock proteins can be evaluated.

Antibodies↗
PubMed2002

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.

Adult↗
PubMed1994

Structural organization of the spinach endoplasmic reticulum-luminal 70-kilodalton heat-shock cognate gene and expression of 70-kilodalton heat-shock genes during cold acclimation.

The 70-kD heat-shock proteins (HSP70s) are encoded by a multigene family in eukaryotes. In plants, the 70-kD heat-shock cognate (HSC70) proteins are located in organellar and cytosolic compartments of cells in most tissues. Previous work has indicated that HSC70 proteins of spinach (Spinacia oleracea) are actively synthesized during cold-acclimating conditions. We have isolated, sequenced, and characterized cDNA and genomic clones for the endoplasmic reticulum (ER) luminal HSC70 protein (immunoglobulin heavy chain-binding protein; BiP) of spinach. The spinach ER-luminal HSC70 is a constitutively expressed gene consisting of eight exons. Spinach BiP mRNA appears to be up-regulated during cold acclimation but is not expressed during water stress or heat shock. In contrast to the differential regulation of mRNA, the ER-luminal HSC70 protein levels remain constant in response to various environmental stresses. Two other members of the spinach 70-kD heat-shock (HS70) multigene family also show differential expression in response to a variety of environmental stresses. A constitutively expressed cytosolic HSC70 protein in spinach appears also to be up-regulated in response to both cold-acclimating and heat-shock treatments. Spinach also contains a cold-shock-induced HS70 gene that is not expressed during heat shock or water stress. Since HSP70s are considered to be involved with the chaperoning and folding of proteins, the data further support the concept that they may be important for maintaining cellular homeostasis and proper protein biogenesis during cold acclimation of spinach.

Acclimatization↗
PubMed1993

Activation of human heat shock genes is accompanied by oligomerization, modification, and rapid translocation of heat shock transcription factor HSF1.

Transcriptional activity of heat shock (hsp) genes is controlled by a heat-activated, group-specific transcription factor(s) recognizing arrays of inverted repeats of the element NGAAN. To date genes for two human factors, HSF1 and HSF2, have been isolated. To define their properties as well as the changes they undergo during heat stress activation, we prepared polyclonal antibodies to these factors. Using these tools, we have shown that human HeLa cells constitutively synthesize HSF1, but we were unable to detect HSF2. In unstressed cells HSF1 is present mainly in complexes with an apparent molecular mass of about 200 kDa, unable to bind to DNA. Heat treatment induces a shift in the apparent molecular mass of HSF1 to about 700 kDa, concomitant with the acquisition of DNA-binding ability. Cross-linking experiments suggest that this change in complex size may reflect the trimerization of monomeric HSF1. Human HSF1 expressed in Xenopus oocytes does not bind DNA, but derepression of DNA-binding activity, as well as oligomerization of HSF1, occurs during heat treatment at the same temperature at which hsp gene expression is induced in this organism, suggesting that a conserved Xenopus protein(s) plays a role in this regulation. Inactive HSF1 resides in the cytoplasm of human cells; on activation it rapidly translocates to a soluble nuclear fraction, and shortly thereafter it becomes associated with the nuclear pellet. On heat shock, activatable HSF1, which might already have been posttranslationally modified in the unstressed cell, undergoes further modification. These different process provide multiple points of regulation of hsp gene expression.

Animals↗
PubMed2002

Thermal acclimation changes DNA-binding activity of heat shock factor 1 (HSF1) in the goby Gillichthys mirabilis: implications for plasticity in the heat-shock response in natural populations.

The intracellular build-up of thermally damaged proteins following exposure to heat stress results in the synthesis of a family of evolutionarily conserved proteins called heat shock proteins (Hsps) that act as molecular chaperones, protecting the cell against the aggregation of denatured proteins. The transcriptional regulation of heat shock genes by heat shock factor 1 (HSF1) has been extensively studied in model systems, but little research has focused on the role HSF1 plays in Hsp gene expression in eurythermal organisms from broadly fluctuating thermal environments. The threshold temperature for Hsp induction in these organisms shifts with the recent thermal history of the individual but the mechanism by which this plasticity in Hsp induction temperature is achieved is unknown. We examined the effect of thermal acclimation on the heat-activation of HSF1 in the eurythermal teleost Gillichthys mirabilis. After a 5-week acclimation period (at 13, 21 or 28 degrees C) the temperature of HSF1 activation was positively correlated with acclimation temperature. HSF1 activation peaked at 27 degrees C in fish acclimated to 13 degrees C, at 33 degrees C in the 21 degrees C group, and at 36 degrees C in the 28 degrees C group. Concentrations of both HSF1 and Hsp70 in the 28 degrees C group were significantly higher than in the colder acclimated fish. Plasticity in HSF1 activation may be important to the adjustable nature of the heat shock response in eurythermal organisms and the environmental control of Hsp gene expression.

Acclimatization↗
PubMed1998

Involvement of heat shock elements and basal transcription elements in the differential induction of the 70-kDa heat shock protein and its cognate by cadmium chloride in 9L rat brain tumor cells.

Exposure of 9L rat brain tumor cells to 40-100 microM CdCl2 for 2 h leads to an induction of a wide spectrum of heat shock proteins (HSPs). We have demonstrated that induction of the 70-kDa HSP (HSP70) and enhanced expression of its cognate (HSC70) by cadmium are concentration dependent and that the induction kinetics of these HSP70s are different. The increased synthesis of the HSP70s is accompanied by the increase in hsp70 and hsc70 mRNA levels, indicative of transcriptional regulation of the heat shock genes. Electrophoretic mobility shift assay (EMSA) using probes encompassing heat shock element (HSE), TATA, GC, and CCAAT boxes derived from the promoter regions of the heat shock genes shows distinguished binding patterns between hsp70 and hsc70 genes in both control and cadmium-treated cells. The results indicate that, in addition to the HSEs, the basal transcription elements are important in the regulation of the heat shock genes. The binding patterns of the corresponding transcription factors of these elements are examined by EMSA by using extended promoter fragments from respective heat shock genes with sequential addition of excess oligonucleotides encompassing individual transcription elements. Taken together, our results show that the differential induction of hsp70 and hsc70 involves multiple transcription factors that interact with HSE, TATA, GC, and CCAAT boxes.

Animals↗
PubMed1998

Cultured skin fibroblasts isolated from mice devoid of the prion protein gene express major heat shock proteins in response to heat stress.

Recent evidence has suggested that molecular chaperones participate in the conformational change between the normal cellular prion protein (PrPC) and its scrapie isoform (PrPSc). To study a role of PrPC in the regulation of expression of heat shock proteins (HSPs), a group of molecular chaperones, heat-induced expression of major HSPs (HSP105, HSP90alpha, HSP72, HSC70, HSP60, and HSP25) was investigated in cultured skin fibroblasts isolated from the mice homogeneous for a disrupted PrP gene (PrP-/- mice) by Western blot analysis and immunocytochemistry. Two lines of fibroblasts were established and designated SFK derived from the PrP-/- mice and SFH derived from the PrP+/+ mice, respectively. In both SFK and SFH cells, HSP105, HSP72, and HSP25 were expressed at low levels under unstressed conditions but they were induced markedly following exposure to heat stress (43 degreesC/20 min) at 3-72 h postrecovery. In both cell types, HSC70 and HSP60 were expressed at high levels under unstressed conditions and their levels remained unchanged after heat shock treatment. HSP90alpha was undetectable in both cell types under any conditions examined. The pattern of expression, induction, and subcellular location of HSP105, HSP72, HSC70, HSP60, and HSP25 was not significantly different between SFK and SFH cells under unstressed and heat-stressed conditions. Furthermore, the levels of constitutive expression of HSP105, HSC70, HSP60, and HSP25 were similar between the brain tissues isolated from the PrP-/- and PrP+/+ mice. These results indicate that HSP induction is not affected by either the existence or the absence of PrPC in the cells.

Animals↗
PubMed2004

Heat stress-induced localization of small heat shock proteins in mouse myoblasts: intranuclear lamin A/C speckles as target for alphaB-crystallin and Hsp25.

We examined the effect of heat stress on localization of two sHsps, alphaB-crystallin and Hsp25, and of Hsc70, a member of a different class of heat shock proteins (Hsps), in both undifferentiated and differentiated mouse C2C12 cells. Under normal conditions, alphaB-crystallin and Hsp25 are found in the cytoplasm; only alphaB-crystallin is also found in the nucleus, distributed in a speckled pattern. Hsc70 is found to be homogeneously distributed throughout the cell. On heat stress, all these proteins translocate almost entirely into the nucleus and upon recovery relocate to the cytoplasm. Dual staining experiments using C2C12 myoblasts show that alphaB-crystallin and Hsp25, but not Hsc70, colocalize with the intranuclear lamin A/C and the splicing factor SC-35, suggesting interactions of sHsps and intranuclear lamin A/C. Interestingly, none of these proteins are found in the myotube nuclei. Upon heat stress, only Hsc70 translocates into the myotube nuclei. This differential entry of alphaB-crystallin and Hsp25 into the nuclei of myoblasts and myotubes upon heat stress may have functional role in the development and/or in the maintenance of muscle cells. Our study therefore suggests that these sHsps may be a part of the intranuclear lamin A/C network or stabilizing this specific network.

Animals↗
PubMed1998

Regulation of heat shock protein 27 expression of prostatic cells in response to heat treatment.

BACKGROUND: The clinical value of heat-induced coagulation of prostatic tissue is evaluated as a minimally invasive treatment for patients with benign prostatic hyperplasia (BPH) and, more recently, localized prostate cancer (PC). To obtain a more detailed insight on the effect of heat on prostatic cells, heat shock protein (HSP) 27 expression of normal and malignant prostatic cells was studied. METHODS: In vitro, HSP27 expression of prostatic stromal cells and the human prostate cancer cell line LNCaP was studied by Western blotting when cultured at 37 degrees C. Subsequently, the effect of a sublethal heat shock from 43-49 degrees C for 60 min on HSP27 expression of LNCaP was determined. In vivo, HSP27 expression pattern of nine human prostates, which were treated in vivo by thermoablation with transrectal high-intensity focused ultrasound (HIFU) 3 hr-8 days prior to surgical removal, was analyzed by immunohistochemistry. Untreated BPH (n = 10) and PC (n = 7) specimens served as controls. RESULTS: Under physiologic conditions (37 degrees C), LNCaP and prostatic stromal cells expressed a 27-kD and 56-kD anti-HSP27 reactive molecule. Following sublethal cell heating, HSP27 (27 kD) expression of LNCaP increased by 3-4-fold in a temperature-dependent manner. In untreated BPH specimens (n = 10), muscle cells stained HSP27-positive in all samples, while epithelial cells (EC) were negative in 6 out of 10 specimens. At the border of the high-intensity focused ultrasound (HIFU) necrosis, increased HSP27 expression was consistently demonstrable (n = 9). HSP27 upregulation was strongest 2-3 hr after HIFU but still demonstrable after 5-8 days. In this border zone, basal and secretory EC as well as muscle cells stained strongly for HSP27. CONCLUSIONS: Benign and malignant human prostatic cells respond to heat by increased expression of HSP27 in vitro and in vivo. Transrectal HIFU therapy induces intraprostatic thermonecrosis surrounded by a zone characterized by a massive upregulation of HSP27 expression.

Cells, Cultured↗
PubMed1991

Synovial fluid-derived Yersinia-reactive T cells responding to human 65-kDa heat-shock protein and heat-stressed antigen-presenting cells.

Humoral and cellular immune reactions to heat-shock proteins have been implicated in the pathogenesis of arthritis. Heat-shock proteins occur in bacteria as well as all eukaryotes and have been highly conserved during evolution. Cross-reactivity between bacterial and human heat-shock proteins induced at the site of inflammation may underlie the pathogenesis of some forms of arthritis. In order to test this hypothesis, we raised and cloned a Yersinia-specific T cell line from the synovial fluid lymphocytes of a patient with Yersinia-induced reactive arthritis. From this line we obtained a CD4+ T cell clone that proliferated in response to Yersinia antigens and both to the mycobacterial and the human 65-kDa heat-shock protein. This T cell clone also proliferated in response to autologous heat-stressed antigen-presenting cells as well as to synovial fluid mononuclear cells from the inflamed joint, thus showing true autoreactivity against endogenously synthetized self-antigen. These results demonstrate the induction of an autoimmune T cell response by a natural bacterial infection and support the important role of heat-shock proteins in the pathogenesis of immune-mediated arthritis.

Adult↗