Differential expression of heat shock protein 70 (HSP70) and heat shock cognate protein 70 (HSC70) in human epidermis

Etiopathogenesis of Psoriasis: Integration of Proposed Theories

Psoriasis is a chronic inflammatory disease characterized by squamous and erythematous plaques on the skin and the involvement of the immune system. Global prevalence for psoriasis has been reported around 1-3% with a higher incidence in adults and similar proportions between men and women. The risk factors associated with psoriasis are both extrinsic and intrinsic, out of which a polygenic predisposition is a highlight out of the latter. Psoriasis etiology is not yet fully described, but several hypothesis have been proposed: 1) the autoimmunity hypothesis is based on the over-expression of antimicrobial peptides such as LL-37, the proteins ADAMTSL5, K17, and hsp27, or lipids synthesized by the PLA2G4D enzyme, all of which may serve as autoantigens to promote the differentiation of autoreactive lymphocytes T and unleash a chronic inflammatory response; 2) dysbiosis of skin microbiota hypothesis in psoriasis has gained relevance due to the observations of a loss of diversity and the participation of pathogenic bacteria such as Streptococcus spp. or Staphylococcus spp. the fungi Malassezia spp. or Candida spp. and the virus HPV, HCV, or HIV in psoriatic plaques; 3) the oxidative stress hypothesis, the most recent one, describes that the cell injury and the release of proinflammatory mediators and antimicrobial peptides that leads to activate of the Th1/Th17 axis observed in psoriasis is caused by a higher release of reactive oxygen species and the imbalance between oxidant and antioxidant mechanisms. This review aims to describe the mechanisms involved in the three hypotheses on the etiopathogeneses of psoriasis.

Damage-Associated Molecular Patterns, a Class of Potential Psoriasis Drug Targets

Psoriasis is a chronic skin disorder that involves both innate and adaptive immune responses in its pathogenesis. Local tissue damage is a hallmark feature of psoriasis and other autoimmune diseases. In psoriasis, damage-associated molecular patterns (DAMPs) released by damaged local tissue act as danger signals and trigger inflammatory responses by recruiting and activating immune cells. They also stimulate the release of pro-inflammatory cytokines and chemokines, which exacerbate the inflammatory response and contribute to disease progression. Recent studies have highlighted the role of DAMPs as key regulators of immune responses involved in the initiation and maintenance of psoriatic inflammation. This review summarizes the current understanding of the immune mechanism of psoriasis, focusing on several important DAMPs and their mechanisms of action. We also discussed the potential of DAMPs as diagnostic and therapeutic targets for psoriasis, offering new insights into the development of more effective treatments for this challenging skin disease.

Heat shock proteins in the physiology and pathophysiology of epidermal keratinocytes

Heat shock proteins (HSPs), a large group of highly evolutionary conserved proteins, are considered to be main elements of the cellular proteoprotection system. HSPs are encoded by genes activated during the exposure of cells to proteotoxic factors, as well as by genes that are expressed constitutively under physiological conditions. HSPs, having properties of molecular chaperones, are involved in controlling/modulation of multiple cellular and physiological processes. In the presented review, we summarize the current knowledge on HSPs in the biology of epidermis, the outer skin layer composed of stratified squamous epithelium. This tissue has a vital barrier function preventing from dehydratation due to passive diffusion of water out of the skin, and protecting from infection and other environmental insults. We focused on HSPB1 (HSP27), HSPA1 (HSP70), HSPA2, and HSPC (HSP90), because only these HSPs have been studied in the context of physiology and pathophysiology of the epidermis. The analysis of literature data shows that HSPB1 plays a role in the regulation of final steps of keratinization; HSPA1 is involved in the cytoprotection, HSPA2 contributes to the early steps of keratinocyte differentiation, while HSPC is essential in the re-epithelialization process. Since HSPs have diverse functions in various types of somatic tissues, in spite of multiple investigations, open questions still remain about detailed roles of a particular HSP isoform in the biology of epidermal keratinocytes.

Heat-shock protein 70 expression in the equine cornea

OBJECTIVE

Expression of the 70-kDa heat-shock protein (HSP70) has been demonstrated in normal canine corneal epithelium, and inducible expression has been suggested to facilitate wound resolution through organized migration, proliferation, and adhesion of the corneal epithelial cells. Diminished expression of HSP70 may therefore contribute to prolonged healing in the pathologic cornea of other companion animal species, including the horse.

ANIMAL STUDIED

Normal and pathologic equine cornea was evaluated to determine whether the expression of HSP70 is correlated with appropriate corneal epithelial wound healing.

PROCEDURES

Paraffin-embedded tissue from normal equine cornea and therapeutic keratectomies of sterile keratopathies was subject to routine immunohistochemistry for HSP70.

RESULTS

Normal equine corneas exhibited the baseline expression of HSP70 in the nuclei of all epithelial cells as well as the cytoplasm of the basal epithelium. Expression of HSP70 in suspected immune-mediated keratitis was localized to the cytoplasm of basal epithelial cells and nuclei of all epithelial cells, similar to the normal equine cornea. Expression in indolent ulcers was diminished; weak, diffuse staining was noted in the cytoplasm of all epithelial cells.

CONCLUSIONS

These findings suggest the expression of HSP70 is induced in the normal equine cornea during re-epithelialization and may be altered in sterile keratopathies.

p53 acts as a co-repressor to regulate keratin 14 expression during epidermal cell differentiation

During epidermal cell differentiation, keratin 14 (K14) expression is down-regulated, p53 expression varies, and the expression of the p53 target genes, p21 and 14-3-3σ, increases. These trends suggest that the relative transcriptional activity of p53 is increased during epidermal cell differentiation. To determine the relationship between K14 and p53, we constructed K14 promoters of various sizes and found that wild-type p53 could repress the promoter activity of all of the K14 promoter constructs in H1299 cells. K14-p160 contains an SP1 binding site mutation that prevents p53 from repressing K14 expression. Using a DNA affinity precipitation assay, we confirmed that p53 forms a complex with SP1 at the SP1 binding site between nucleotides -48 and -43 on the K14 promoter. Thus, our data indicate that p53 acts as a co-repressor to down-regulate K14 expression by binding to SP1. Next, we used a 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced epidermal cell differentiation model to examine the inhibition of K14 expression caused by increased p53 activity. Human ovarian teratocarcinoma C9 cells were treated with TPA to induce differentiation. Over-expression of the dominant negative p53 mutant ΔTAp53, which inhibits p53 activity, prevented the TPA-induced K14 down-regulation in C9 cells. Furthermore, treatment of normal primary human foreskin keratinocytes (PHFK) with the p53 inhibitor pifithrin-α (PFT-α) showed that the inhibition of p53 activity relieves K14 repression during epidermal cell differentiation. Finally, we found that TPA induces the phosphorylation of p53 at residue 378, which enhances the affinity of p53 to bind to Sp1 and repress K14 expression.

Ezrin, maspin, peroxiredoxin 2, and heat shock protein 27: potential targets of a streptococcal-induced autoimmune response in psoriasis

Psoriasis is an HLA-Cw6-associated T cell-mediated autoimmune disease of the skin that is often triggered by streptococcal angina. To identify keratinocyte proteins, which may become psoriatic autoantigens as the result of an immune response against streptococci, rabbits were immunized with heat-killed Streptococcus pyogenes. Streptococcal immunization induced Ab formation against various human keratinocyte proteins. Sera from psoriasis patients reacted against several of these proteins as well. Common serologic reactivities of rabbits and patients included the proteins ezrin, maspin, peroxiredoxin 2 (PRDX2), heat shock protein (hsp)27, and keratin 6. When used for stimulation of blood lymphocytes, ezrin, maspin, PRDX2, and hsp27 induced increased T cell activation in psoriasis patients, which was particularly evident for HLA-Cw6(+) individuals. Ag-specific T cell lines generated with these proteins consisted predominantly of CD8(+) T cells and used TCR beta-chain rearrangements, which were highly homologous to those expanded within the corresponding skin lesion. Several immunodominant epitopes on the different proteins could be defined according to sequence alignments with the whole genome of S. pyogenes. Our data indicate that maspin, ezrin, PRDX2, hsp27, and potentially keratin 6 could act as autoantigens of a streptococcal-induced autoimmune response and represent targets of the exaggerated T cell response in psoriasis. Additionally, ezrin and hsp27 might constitute antigenic links between psoriasis and inflammatory bowel disease, uveitis, or arteriosclerosis, which are clinically associated.

Evaluation of the skin irritation using a DNA microarray on a reconstructed human epidermal model

To avoid the need to use animals to test the skin irritancy potential of chemicals and cosmetics, it is important to establish an in vitro method based on the reconstructed human epidermal model. To evaluate skin irritancy efficiently and sensitively, we determined the gene expression induced by a topically-applied mild irritant sodium dodecyl sulfate (SDS) in a reconstructed human epidermal model LabCyte EPI-MODEL (LabCyte) using a DNA microarray carrying genes that were related to inflammation, immunity, stress and housekeeping. The expression and secretion of IL-1alpha in reconstructed human epidermal culture is known to be induced by irritation. We detected the induction of IL-1alpha expression and its secretion into the cell culture medium by treatment with 0.075% SDS for 18 h in LabCyte culture using DNA microarray, quantitative reverse-transcription polymerase chain reaction (RT-PCR) and ELISA. DNA microarray analysis indicated that the expression of 10 of the 205 genes carried on the DNA microarray was significantly induced in a LabCyte culture by 0.05% or 0.075% SDS irritation for 18 h. RT-PCR analysis confirmed that SDS treatment significantly induced the expressions of interleukin-1 receptor antagonist (IL-1RN), FOS-like antigen 1 (FOSL1), heat shock 70 kDa protein 1A (HSPA1) and myeloid differentiation primary response gene (88) (MYD88), as well as the known marker genes for irritation IL-1beta and IL-8 in a LabCyte culture. Our results showed that a DNA microarray is a useful tool for efficiently evaluating mild skin irritation using a reconstructed human epidermal model.

Human skin cell stress response to GSM-900 mobile phone signals. In vitro study on isolated primary cells and reconstructed epidermis

In recent years, possible health hazards due to radiofrequency radiation (RFR) emitted by mobile phones have been investigated. Because several publications have suggested that RFR is stressful, we explored the potential biological effects of Global System for Mobile phone communication at 900 MHz (GSM-900) exposure on cultures of isolated human skin cells and human reconstructed epidermis (hRE) using human keratinocytes. As cell stress markers, we studied Hsc70, Hsp27 and Hsp70 heat shock protein (HSP) expression and epidermis thickness, as well as cell proliferation and apoptosis. Cells were exposed to GSM-900 under optimal culture conditions, for 48 h, using a specific absorption rate (SAR) of 2 W x kg(-1). This SAR level represents the recommended limit for local exposure to a mobile phone. The various biological parameters were analysed immediately after exposure. Apoptosis was not induced in isolated cells and there was no alteration in hRE thickness or proliferation. No change in HSP expression was observed in isolated keratinocytes. By contrast, a slight but significant increase in Hsp70 expression was observed in hREs after 3 and 5 weeks of culture. Moreover, fibroblasts showed a significant decrease in Hsc70, depending on the culture conditions. These results suggest that adaptive cell behaviour in response to RFR exposure, depending on the cell type and culture conditions, is unlikely to have deleterious effects at the skin level.

Activation of dendritic antigen-presenting cells expressing common heat shock protein receptor CD91 during induction of psoriasis

BACKGROUND

Psoriasis is a common and chronic relapsing inflammatory skin disorder. Although a role for T cells in mediating the induction and maintenance of psoriatic lesions is well established, mechanisms responsible for activation of T cells by antigen-presenting cells (APCs) during disease relapse are poorly understood.

OBJECTIVES

(i) To determine whether expression of the common heat shock protein (HSP) receptor CD91 correlated with development of psoriasis in a mouse model of psoriasis, (ii) to characterize the lesional cells on which CD91 was expressed, and (iii) to investigate whether CD91+ cells in psoriasis showed signs of activation.

METHODS

Two systems were used in order to study the above-mentioned objectives: (i) skin biopsies taken directly from patients with psoriasis (either psoriatic plaques or symptomless prepsoriatic skin) or from healthy donors, respectively, or (ii) (human) skin biopsies collected during development of psoriasis using a novel xenograft mouse model of psoriasis. The skin samples were then either processed for analysis by light microscopy, or labelled with fluorochrome-conjugated antibodies and analysed by confocal laser scanning microscopy.

RESULTS

We observed a markedly increased number of CD91+ cells which paralleled development of new psoriatic lesions in the psoriasis mouse model and in established psoriatic plaques compared with symptomless prepsoriatic or healthy skin. Morphology as well as cell-specific markers showed that CD91 was predominantly expressed by dermal dendritic APCs characterized by activation of nuclear factor-kappaB signalling and the presence of tumour necrosis factor-alpha, an important proinflammatory cytokine in the immunopathogenesis of psoriasis. In addition, HSP70, a ligand for CD91, was increased in keratinocytes in close vicinity to CD91-bearing APCs in psoriatic lesions.

CONCLUSIONS

These findings indicate massive presence of CD91+ dendritic cells juxtaposed to lesional keratinocytes expressing HSP70, and suggest a novel pathophysiological pathway and therapeutic target for this chronic inflammatory skin disease.

Possible role of Malassezia furfur in psoriasis: modulation of TGF-beta1, integrin, and HSP70 expression in human keratinocytes and in the skin of psoriasis-affected patients

BACKGROUND

Psoriasis is a disease characterized by an abnormal pattern of keratinocyte growth and differentiation. Malassezia furfur forms part of the normal human skin flora. It may also be involved in the pathogenesis of psoriasis. To define the role of M. furfur in the pathogenesis of psoriasis, we investigated how M. furfur regulates molecules involved in cell migration and proliferation. The experiments were performed using human keratinocytes and skin biopsies from M. furfur-positive and -negative psoriasis-affected patients. In addition, we examined the signal transduction mechanisms involved.

MATERIALS AND METHODS

Western blot analysis was performed on human keratinocytes lysates treated or untreated with M. furfur and on biopsies from healthy and psoriasis patients. Signal transduction mechanisms involved were evaluated by electrophoretic mobility shift assay using the AP-1 inhibitor curcumin.

RESULTS

We found that M. furfur up-regulates transforming growth factor-beta1 (TGF-beta1), integrin chain, and HSP70 expression in human keratinocytes via AP-1-dependent mechanism. In the biopsies of M. furfur-positive psoriasis-affected patients, an increase in TGF-beta1, integrin chains, and HSP70 expression was found.

CONCLUSION

Our data suggest that M. furfur can induce the overproduction of molecules involved in cell migration and hyperproliferation, thereby favoring the exacerbation of psoriasis.

Heat Shock Proteins (HSPs) 27, 72 and 73 in Normal and Pre-ulcerative Mucosa of the Gastric Pars Oesophagea in Swine

Heat shock proteins (HSPs), known to play a key role in cellular homeostasis, may also play a role in the defensive mechanisms of gastric mucosa. By means of appropriate immunohistochemical and immunobiochemical techniques, the expression of HSP27, HSP72 and HSP73 within the epithelium of normal and pre-ulcerative (hyperkeratinized) mucosa of the pars oesophagea of abattoir pigs was assessed. In normal mucosa, HSP72 and HSP73 expression was mainly limited to the basal epithelial cell layer, whereas HSP27 expression was consistently detected within the superficial epithelial cell layers. In hyperkeratinized mucosa, HSP72 and HSP73 immunoreactivity appeared to be more widespread, becoming very intense within epithelial cells affected by hydropic degeneration. Hyperkeratinized mucosa also showed HSP27 immunoreactivity, which was particularly intense in epithelial areas affected by hydropic degeneration. Western blot analysis confirmed HSP27, HSP72 and HSP73 expression in normal and in pre-ulcerative mucosa of the pars oesophagea. Semi-quantitative analysis showed that for all three HSPs the immunoreactivity was more intense in pre-ulcerative mucosa than in normal mucosa. The different expression patterns observed may have functional significance; further studies are needed, however, to define the role of HSPs in swine oesophagogastric lesions, the aetiology and pathogenesis of which are largely unknown.

Continuous enhanced expression of Hsc70 but not Hsp70 in rheumatoid arthritis synovial tissue

OBJECTIVE

To investigate the expression of constitutive and inducible members of the Hsp70 protein family in synovial tissue of patients with rheumatoid arthritis (RA) or osteoarthritis (OA).

METHODS

Frozen sections of synovial tissue and isolated synovial adherent cells obtained from 17 RA patients, 5 OA patients, and 1 patient with carpal tunnel syndrome (CTS) were analyzed with specific monoclonal antibodies, by immunohistochemistry, immunocytochemistry, and immunoblotting.

RESULTS

Expression of the constitutive chaperone Hsc70 was increased in synovial tissue from 9 of 9 patients with RA, but was faint or undetectable in 3 of 3 samples from patients with OA. In RA samples, cells mainly of the synovial lining stained intensely for Hsc70 as well as for HLA-DR, CD14, and CD68. Also, in vitro-cultured synovial adherent cells from 8 of 9 RA patients overexpressed Hsc70 (specimens from 1 RA patient were used in both the immunochemistry and the in vitro culture studies). On immunoblots of protein extracts, the synovial and HeLa cell molecules appeared identical in size. The inducible chaperone Hsp70 was not detected in samples from any of the same 17 RA patients, except for rare, isolated cells in 3. Samples from 4 of 5 OA patients also were negative for the inducible chaperone Hsp70, and the fifth was very weakly positive. In addition, tissue from 1 patient with CTS was analyzed 10 months before diagnosis of RA. Synovial tissue from this patient showed extreme overexpression of both Hsc70 and Hsp70.

CONCLUSION

In RA, synovial lining cells continuously overexpress Hsc70 but not Hsp70. Hsc70 may be up-regulated due to the high activity of these cells in several respects, including antigen processing and presentation.

Wuchereria bancrofti: cloning and characterization of heat shock protein 70 from the human lymphatic filarial parasite

Heat shock protein 70 (HSP70) was identified as an immunodominant antigen by screening a Wuchereria bancrofti (Wb) microfilarial cDNA library with pooled Wb-infected sera, with 28% of the immunopositive clones coding for Wb-HSP70. The deduced amino acid sequence showed greater than 97 and 85% identity with HSP70 from filarial nematodes and humans, respectively. Recombinant HSP70 (74 kDa) and a recombinant protein from the C-terminal portion (43 kDa) also reacted with pooled Wb-infected sera, suggesting that the C-terminal region of HSP70 contains at least one antibody epitope. Brugia malayi L3 larvae showed increasing levels of HSP70 with increasing temperatures. Further, a polyclonal mouse anti-Wb-HSP70 antibody had reactivity to the HSP70 of cattle filarial parasite Settaria digitata and to human HSP70 derived from a Hep-2 cell line. Immune reactivity to Wb-HSP70 was strong, with uninfected non-endemic normal sera showing significantly greater reactions than sera from filaria-infected individuals. Both immunodominant self-HSP70 and HSP70 from other microbial infections may be primary targets for developing autoantibodies naturally.

Heat shock protein 70: correlation of expression with degree of graft-versus-host response and clinical graft-versus-host disease

BACKGROUND

The heat shock proteins are increasingly becoming associated with immunopathologic phenomena, being induced in response to inflammation. They are highly immunogenic and are postulated as playing a role in both innate and adaptive immunity. Their proposed role in peptide binding and antigen presentation could suggest a potential role in the alloreactive process that leads to graft-versus-host disease (GVHD) after bone marrow transplantation.

METHODS

In this study we examined the expression of the widely studied heat shock protein 70 (hsp70) in an in vitro-generated graft-versus-host reaction in human skin, using streptavidin biotin immunohistochemistry and laser scanning confocal microscopy.

RESULTS

Hsp70 expression was correlated with high graft-versus-host responses (P<0.001) and was confirmed using laser scanning confocal microscopy. Increased expression of hsp70 was further defined due to increases in the inducible form of hsp70. Expression of inducible hsp70 was predictive of both clinical acute GVHD (P=0.001) and incidence of chronic GVHD (P<0.001).

CONCLUSIONS

This investigation has demonstrated for the first time the expression of hsp70 in a human model of GVHD, suggesting involvement in the pathogenesis of the disease and providing the basis for further investigation. Increased expression of inducible hsp70 in the model could provide a biologic marker for the prediction of clinical acute and chronic GVHD.

Induction of stress proteins and MMP-9 by 0.8 ppm of ozone in murine skin

Ozone (O(3)) is among the most reactive environmental oxidant pollutants to which cutaneous tissues are exposed. O(3) exposure has been shown to induce antioxidant depletion as well as the oxidation of lipids and proteins within the outermost skin layer, the stratum corneum. However, relatively little is known regarding the potential effects of O(3) on the cellular constituents of the underlying skin epidermis and dermis. In the present study, hairless mice exposed for 6 h to 0.8 ppm O(3) showed increases in lipid peroxidation, as quantitated by increases in 4-hydroxynonenal-protein adducts. O(3) exposure caused an induction of the stress proteins HSP27 and heme oxygenase-1 (HO-1), starting at 6 h and increasing up to 18 h after O(3) exposure. This was accompanied by an increase in matrix metalloproteinase-9 (MMP-9) mRNA and activity levels, indicative of possible injurious-reparative processes. Collectively, our data demonstrate that skin exposure to O(3) not only affects antioxidant levels and oxidation markers in the outermost stratum corneum layer, but also induces cellular stress responses in the deeper cellular layers of the skin.

IMPLICATION OF RESPONSES TO BACTERIAL HEAT SHOCK PROTEINS, CHRONIC MICROBIAL INFECTIONS, AND DENTAL METAL ALLERGY IN PATIENTS WITH PUSTULOSIS PALMARIS ET PLANTARIS

Pustulosis palmaris et plantaris (PPP) is a chronic relapsing skin disease characterized by sterile intraepidermal pustules and, usually, by scaly erythematous skin on the palm, soles, or both. To determine the primary pathogenic factors involved in the onset of PPP, we analyzed the implications of heat shock proteins (HSPs), which are highly conserved immunogenic proteins, chronic microbial infections including marginal and periapical periodontitis, and delayed type hypersensitivity (DTH) against dental metals examined by patch tests. We found that the titers of IgG against HSPs of Escherichia coli GroEL and Actinobacillus actinomycetemcomitans DnaJ in the sera from PPP patients were higher than those in the control group (GroEL; p < 0.05). Two patients with PPP had more than 1,000 ng/ml serum IgE level. We found that the average serum IgG antibody level against human cytomegalovirus (HCMV) in the PPP patient group was higher than that of the healthy group (p < 0.05). DTH against dental metal was found in eight of 22 PPP patients. Six of eight patients reacted against more than two metals. Replacement of dental metal with resin in these patients resulted in the disappearance or remission of PPP. These findings suggest that the immune responses to HSPs produced by oral bacteria, HCMV infection, dental metal allergy, and their combinations are etiological factors for PPP. We concluded that various kinds of examinations, including oral cavity conditions and chronic infections, are essential to determine the major etiologic factors of PPP.

Ozone exposure activates oxidative stress responses in murine skin

Ozone (O(3)) is among the most reactive environmental oxidant to which skin is exposed. O(3) exposure has previously been shown to induce antioxidant depletion as well as lipid and protein oxidation in the outermost skin layer, the stratum corneum (SC), but little is known regarding the potential effects of O(3) on the skin epidermis and dermis. To evaluate such skin responses to O(3), SKH-1 hairless mice were exposed for 2 h to 8.0 ppm O(3) or to ambient air. O(3) exposure caused a significant increase in skin carbonyls (28%) compared to the skin of air exposed control animals. An evident increase in 4-hydroxynonenal-protein adducts was detected after O(3) exposure. O(3) exposure caused a rapid up-regulation of HSP27 (20-fold), and more delayed induction of HSP70 (2.8-fold) and heme oxygenase-1 (5-fold). O(3) exposure also led to the induction of nitric oxide synthase (iNOS) 6-12 h following O(3) exposure. We conclude that skin exposure to high levels of O(3) not only affects antioxidant levels and oxidation markers in the SC, but also induces stress responses in the active layers of the skin, most likely by indirect mechanisms, since it is unlikely that O(3) itself penetrates the protective SC layers.

Subcorneal colocalization of the small heat shock protein, hsp27, with keratins and proteins of the cornified cell envelope

BACKGROUND

hsp27 is a member of the small heat shock protein family. Its expression in epidermal keratinocytes in situ and in tissue culture correlates with differentiation. Experimental evidence points to the fact that hsp27 is a molecular chaperone and is involved in the regulation of cell growth and differentiation.

OBJECTIVES

To investigate whether epidermal hsp27 through its chaperone function plays a role in the assembly of keratin filaments and the cornified cell envelope.

METHODS

We performed double staining immunofluorescence and immunogold microscopy on normal human skin (n = 15). We analysed the colocalization of hsp27 with actin, keratins and proteins of the cornified cell envelope (loricrin, filaggrin, transglutaminase 1).

RESULTS

Actin staining did not reveal detectable colocalization with hsp27. For keratins, transglutaminase, loricrin and filaggrin colocalization was found in more than 60% of the samples. Colocalization was confined to a narrow subcorneal layer with varying patterns of expression. Electron microscopy revealed that loricrin and filaggrin colocalize with hsp27 indirectly through binding to intermediate filaments.

CONCLUSIONS

These results provide morphological evidence that in normal human skin hsp27 might act as a chaperone of cornification. Investigations of the molecular hsp27 interactions with the proteins of the cornified cell envelope are necessary to gain further insight into terminal keratinocyte differentiation and disorders of keratinization.

Nickel-induced proteins in human HaCaT keratinocytes: annexin II and phosphoglycerate kinase

It has been established in previous in vitro experiments with human HaCaT keratinocytes that nickel becomes cytotoxic at concentrations higher than 100 microM and that it is accumulated mainly in the cytosolic fraction (Ermolli et al., 2000). The aim of this work was to search possible biomarkers of metal insult, i.e. nickel-binding proteins or proteins differentially expressed in the cytosolic fraction of nickel-exposed cells (up to 1 mM nickel) as compared to controls. Cytosolic proteins were studied by isoelectric focusing (IEF) and two-dimensional gel electrophoresis (2-DE). Separation by IEF revealed nickel-induced changes in the abundance of cytosolic proteins as visualised with nickel-nitrilo-triacetic-alkaline phosphatase (Ni-NTA-AP) in blots. The cytosolic fraction of cells incubated with nickel, at concentrations over 100 microM, showed nickel binding components which were absent or present in significantly lower amounts in control cells. These proteins had isoelectric points (pIs) 6.9, 7.7 and 8.5. After 2-DE silver- and protein staining significantly increased abundance of four proteins was observed. Their pI values corresponded to those of the nickel binding ones seen after IEF. A protein with pI 6.9 had a molecular weight estimated to 38 kDa, two proteins with pI around 7.7 showed molecular weights of 57 and 22 kDa, respectively and another protein with pI of 8.5 had a molecular weight of 33 kDa. The increased abundance of these components, both in IEF experiments and in 2-DE, correlated with the nickel concentration in the culture media. N-terminal amino acid sequencing and database search allowed identification of one a protein as phosphoglycerate kinase and another one as annexin II. The involvement of these proteins in cellular functions and their possible implications in the mechanism of nickel toxicity in keratinocytes are discussed. Some of these proteins may be biomarker candidates for effects of nickel exposure in human keratinocytes.

Prognostic significance of heat shock proteins 27 and 70 in patients with squamous cell carcinoma of the esophagus

BACKGROUND

Heat shock proteins (HSPs) first were defined as proteins induced by heat shock and other environmental and pathophysiologic stresses and are implicated in protein-protein interactions such as folding, translocation, and prevention of inappropriate protein aggregation. Many of their functions suggest that they play important roles in cancer.

METHODS

Immunohistochemical study for HSP 27 and HSP 70 was performed on buffered formalin fixed, paraffin embedded sections of 102 esophageal squamous cell carcinoma specimens using monoclonal anti-HSP 27 antibody and anti-HSP 70 antibody.

RESULTS

Normal squamous cells expressed both HSP 27 and HSP 70 with the exception of the basal layer. In cancerous tissue, expression of HSP 27 was evaluated as positive (+) (39 cases; 38%), reduced (+/-) (53 cases; 52%), or negative (-) (10 cases; 10%) and expression of HSP 70 was evaluated as (+) (14 cases; 14%), (+/-) (57 cases; 56%), or (-) (31 cases; 30%). There was a strong correlation between the expression of HSP 27 and HSP 70 (P < 0.0001). When compared with clinicopathologic features, expression of both HSP 27 and HSP 70 correlated negatively with lymph node metastases (P < 0.05), but not with depth of invasion or histologic grade. The reduction of the HSPs was associated significantly with poor postoperative survival (P < 0.0001). In addition, multivariate analysis revealed that HSP 27 (-) was the strongest prognostic factor among the clinicopathologic features.

CONCLUSIONS

This study suggests that the expression of HSP 27 and HSP 70 frequently is reduced in patients with esophageal squamous cell carcinoma and therefore should be considered an independent prognostic factor of this disease.

Prognostic significance of heat shock proteins 27 and 70 in patients with squamous cell carcinoma of the esophagus

BACKGROUND

Heat shock proteins (HSPs) first were defined as proteins induced by heat shock and other environmental and pathophysiologic stresses and are implicated in protein-protein interactions such as folding, translocation, and prevention of inappropriate protein aggregation. Many of their functions suggest that they play important roles in cancer.

METHODS

Immunohistochemical study for HSP 27 and HSP 70 was performed on buffered formalin fixed, paraffin embedded sections of 102 esophageal squamous cell carcinoma specimens using monoclonal anti-HSP 27 antibody and anti-HSP 70 antibody.

RESULTS

Normal squamous cells expressed both HSP 27 and HSP 70 with the exception of the basal layer. In cancerous tissue, expression of HSP 27 was evaluated as positive (+) (39 cases; 38%), reduced (+/-) (53 cases; 52%), or negative (-) (10 cases; 10%) and expression of HSP 70 was evaluated as (+) (14 cases; 14%), (+/-) (57 cases; 56%), or (-) (31 cases; 30%). There was a strong correlation between the expression of HSP 27 and HSP 70 (P < 0.0001). When compared with clinicopathologic features, expression of both HSP 27 and HSP 70 correlated negatively with lymph node metastases (P < 0.05), but not with depth of invasion or histologic grade. The reduction of the HSPs was associated significantly with poor postoperative survival (P < 0.0001). In addition, multivariate analysis revealed that HSP 27 (-) was the strongest prognostic factor among the clinicopathologic features.

CONCLUSIONS

This study suggests that the expression of HSP 27 and HSP 70 frequently is reduced in patients with esophageal squamous cell carcinoma and therefore should be considered an independent prognostic factor of this disease.

Expression of heat shock proteins in mouse skin during wound healing

Wound healing conditions generate a stressful environment for the cells involved in the regeneration process and are therefore postulated to influence the expression of heat shock proteins (Hsps). We have examined the expression of four Hsps (Hsp27, Hsp60, Hsp70 and Hsp90) and a keratin (keratin 6) by immunohistochemistry during cutaneous wound repair from Day 1 to Day 21 after wounding in the mouse. Hsps were constitutively expressed in normal mouse epidermis and their patterns of expression were modified during the healing process. The changes were not directly linked to the time course of the healing process but rather were dependent on the location of cells in the regenerating epidermis. In the thickened epidermis, Hsp60 was induced in basal and low suprabasal cells, Hsp70 showed a reduced expression, and Hsp90 and Hsp27 preserved a suprabasal pattern with an induction in basal and low suprabasal cells. All Hsps had a uniform pattern of expression in the migrating epithelial tongue. These observations suggest that the expression of Hsps in the neoepidermis is related to the proliferation, the migration, and the differentiation states of keratinocytes within the wound.