Induction of HSP27 nuclear immunoreactivity during stress is modulated by vitamin C

Thermal preconditioning can reduce the incidence of intraoperatively acquired pressure injuries

Intraoperatively acquired pressure injuries (IAPIs) occur frequently among patients who undergo surgical procedures that last longer than 3 h. Several studies indicated that heat shock proteins (HSPs) play an important role in the protection of stress-induced damages in skin tissues. Hence, the aim of this study was to investigate the potential preventive effect of thermal preconditioning (TPC) on IAPIs in surgical patients and rats and to identify the differentially expressed HSP genes in response to the above treatment. TPC was performed on one group of hairless rats before the model of pressure injuries was established. Subsequently, the size of skin lesions was measured and the expression levels of mRNA and protein of HSPs of the pressured skin were detected by real-time polymerase chain reaction (RT-PCR), western blot, and immunohistochemical staining. For human studies, 118 surgical patients were randomly divided into the TPC group (n = 59) and the control group (n = 59), respectively. The temperature and pressure of sacral skin, as well as the incidence of pressure injury (PI) were detected and compared. In animal studies, TPC significantly reduced both the size and incidence of PI in rats on the second, third and fourth days post treatment. In addition, the expression levels of both mRNA and protein of HSP27 were increased in the TPC group, compared with the control group. Immunohistochemical staining showed that HSP27 was distributed in various types of dermal cells and increased in basal cells. In human studies, a significant reduction (75%) of IAPIs was observed among the patients in the TPC group. TPC can reduce the incidence of PI in rats and humans, and the upregulation of HSP27 may play an important role in this biological progress. Further studies are warranted to explore the molecular mechanism of the preventive effect in PI mediated by HSP27.

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.

The effects of HSP27 against UVB-induced photoaging in rat skin

Skin photoaging refers to the phenomenon of skin aging or accelerated aging as a result of long-term UV exposure. Ultraviolet radiation can lead to DNA damage, cell apoptosis, cell growth inhibition and carcinogenic effects. Evidence suggests that hsp27 can protect cells from apoptosis induced by various stimuli in vivo and in vitro. However, modulation in hsp27 expression toward skin protection against UVB treatment has not been investigated clearly. In this study, we aimed to investigate the effects of hsp27 against UVB-induced photoaging in rat skin and to explore the underlying mechanisms. In the present study, we identified that the level of hsp27 increased after UVB irradiation induced chronic photoaging rat model. In order to investigate the function of hsp27 in UVB-induced skin photoaging, we used adeno-associated virus (AAV) to specificity reduce the expression of hsp27 in rat skin. In contrast to UVB group, we found that collagen fibers were disorganized and elastic fibers were thickened and twisted in UVB-AAV group. In the UVB-AAV group, reduced hsp27 enhanced the oxidative stress. Aging markers (SA-β-Gal staining and the protein levels of p16, p53, p21) were significantly changed in the hsp27 decreased group. However, in hsp27 deletion group, the expression of antiapoptotic factor bcl-2 was decreased, while the apoptosis factor bax was increased after UVB irradiation. These findings suggested that hsp27 was involved in oxidative stress, aging and apoptosis of skin after UV exposure. Management the expression of hsp27 can be used as a potential intervention method to alleviate UVB-induced skin damage.

Screening of differentially expressed proteins in psoriasis vulgaris by two-dimensional gel electrophoresis and mass spectrometry

The aim of the present study was to elucidate differentially expressed proteins in lesional tissues of psoriasis vulgaris (PV) and normal tissues. Lesional skin tissues were collected from PV patients, along with normal skin tissues from healthy individuals. The protein content of the samples was extracted and then separated by two-dimensional gel electrophoresis (2-DGE). Any proteins that were differentially expressed in the lesional skin of PV patients compared with the healthy controls were analyzed by mass spectrometry and bioinformatics. In the stratum corneum and dermis of PV patients, the total number of proteins identified by 2-DGE was 1,969±21 and 1,928±49, respectively. Of these, 30 proteins were differentially expressed in the PV patients, of which 14 were identified as: Type 1 keratin cytoskeleton proteins (including K1C10, K1C14, K1C15 and K1C16); the type 2 keratin cytoskeleton protein, K2C1; actin-associated proteins (including ARP3, ACTA and ACTBM); prohibitin; heat shock proteins (HSPB1 and CH60); centrosome protein, CP135; and membrane associated proteins (including ANXA4 and ANXA5). The differential expression of protein between PV lesions and normal tissue can be considered as pathological biomarker. Elucidating the abnormal regulation of these proteins can provide mechanism of the development of PV and may contribute to significant approaches for PV treatments.

HSP27 as a biomarker for predicting skin irritation in human skin and reconstructed organotypic skin model

In vitro alternative tests aiming at replacing the traditional animal test for predicting the irritant potential of chemicals have been developed, but the assessing parameters or endpoints are still not sufficient. To discover novel endpoints for skin irritation responses, 2DE-based proteomics was used to analyze the protein expression in human skin exposed to sodium lauryl sulfate (SLS) following the test protocol of the European Centre for the Validation of Alternative Methods (ECVAM) in the present study. HSP27 was up-regulated most significantly among the eight identified proteins, consistent with our previous reports. Acid and basic chemicals were applied on human skin for further validation and results showed that the up-regulated expression of HSP27 was induced in 24h after the exposure. Skin-equivalent constructed with fibroblasts, basement membrane and keratinocytes was used to investigate the potential of HSP27 as a biomarker or additional endpoint for the hazard assessment of skin irritation. Our skin-equivalent (Reconstructed Organotypic Skin Model, ROSM) had excellent epidermal differentiation and was suitable for the skin irritation test. HSP27 also displayed an up-regulated expression in the ROSM in 24h after the irritants exposure for 15min. All these results suggest that HSP27 may represent a potential marker or additional endpoint for the hazard assessment of skin irritation caused by chemical products.

In vitro skin absorption and drug release – A comparison of six commercial prednicarbate preparations for topical use

Reconstructed human epidermis is a useful tool for in vitro skin absorption studies of chemical compounds. If this may hold true also for topical dermatics, we investigated the glucocorticoid prednicarbate applied by two sets (innovator and generic) of cream, ointment and fatty ointment using the commercially available EpiDerm model. Moreover, stability and local tolerability of the preparations as well as drug release were studied, to estimate an influence on prednicarbate absorption and metabolism. While release ranked in the order cream<fatty ointment<ointment for both sets of preparations, prednicarbate penetration and permeation of the EpiDerm model did not. Less PC uptake observed with the generic ointment and fatty ointment appeared to be linked to impaired enzymatic ester cleavage within the tissue. Thus with drugs subject to skin metabolism, cutaneous uptake is not to be derived from drug release studies, yet has to be studied experimentally with viable skin or reconstructed human epidermis.

Skin constructs for replacement of skin tissues for in vitro testing

Reconstructed human skin equivalents as an alternative to animal experimentation offer not only a way to concede to demands of regulatory authorities, animal welfare organizations, consumers and scientists, but also provide a means to improve and extend our knowledge on biological processes in the skin. Presently, various skin reconstructs are available composed either of the epidermal compartment only or of both the epidermal and dermal compartments. Within each compartment various types of cells can be incorporated, including keratinocytes, melanocytes and Langerhans cells in the epidermal, and fibroblasts and endothelial cells in the dermal compartment. The quality of the human skin equivalents has now reached a point that their suitability for skin toxicity testing will make great progress. Next to the field of toxicity and safety standards, skin equivalents offer a well-characterized model for studies of the basic skin biology, wound repair, regulation of melanogenesis, pathogenesis of skin diseases and skin cancer.