Heat shock proteins and skin diseases

Role of epidermal dendritic cells in drug-induced cutaneous adverse reactions

Drug-induced adverse reactions (ADR) include any undesirable pharmacological effect that occurs following drug administration at therapeutic doses. The appearance of ADR significantly limits the use of drugs in as much as their clinical symptoms may range from very mild discomfort such as cutaneous rash, up to very severe, or even fatal tissue necrolysis such as the Stevens Johnson syndrome.One of the most frequently involved organ during ADR is the skin. Drug-induced cutaneous reactions (CDR) incidence is variable but they may appear in 2-3% of ambulatory patients, and it may increase to 10-15% when patients are hospitalized, or even be as high as 60% when co morbidity includes the presence of virus, bacteria, or parasites.Due to the fact that skin is one of the organs most frequently involved in ADR, in this work we analyze and propose a mechanism by which epidermal dendritic cells operating as the sentinels of the skin neuro-immune-endocrine system may contribute to CDR via either immunogenic or tolerogenic immune responses towards drugs, whenever they are administered topic or systemically.

Comparison of expression of heat-shock protein 60, Toll-like receptors 2 and 4, and T-cell receptor gammadelta in plaque and guttate psoriasis

BACKGROUND

Psoriasis is a chronic skin disease that appears to be autoimmune in nature. Recently, it is thought that microbial pathogens of skin can affect the pathogenesis of psoriasis by inducing autoimmunity. Heat-shock proteins (HSPs) are known to play an important role in immune and inflammatory responses of the skin including psoriasis. Recent studies have suggested that Toll-like receptors (TLR) 2, 4 and gammadelta T-cell receptors (TCR-gammadelta) may recognize HSP60 as a ligand and consequently activate the immune system.

METHODS

The biopsy specimens of 12 of guttate psoriasis, 12 of plaque psoriasis and five of normal skin were studied using immunohistochemical staining. The expressions of HSP60, TLR2 and TLR4 were evaluated using an immunostaining-intensity-distribution (IID) index and TCR-gammadelta positive cells were counted.

RESULTS

The expression of HSP60 was significantly higher in guttate and plaque psoriasis than in normal skin. The expression of TLR4 was higher in guttate psoriasis than in plaque psoriasis and normal skin. The expression of TCR-gammadelta was higher in guttate and plaque psoriasis than in normal skin, but there was no correlation found between the expression of HSP60 and TLRs 2 and 4, or between that of HSP60 and TCR-gammadelta.

CONCLUSIONS

HSP60 may be related to the pathogenesis of both guttate and plaque psoriasis and TLR4 may be related to the pathogenesis of guttate psoriasis.

Effect of arylhydroxylamine metabolites of sulfamethoxazole and dapsone on stress signal expression in human keratinocytes

The initiation of an immune response to small molecules is believed to require the release of stress/danger signals that activate resident dendritic cells, presumably secondary to the formation of reactive metabolites. We hypothesized that exposure to arylhydroxylamine metabolites of dapsone and sulfamethoxazole lead to the expression/release of numerous stress signals in the skin. To test this hypothesis, we examined the effect of these metabolites on the expression of selected heat shock proteins, uric acid, cytokines, adhesion molecules, and costimulatory molecules in normal human epidermal keratinocytes (NHEKs). NHEKs showed a time-dependent up-regulation of heat shock protein 70 and translocation of heat shock protein 27 when exposed to the arylhydroxylamine metabolites. In addition, the secretion of several proinflammatory cytokines was increased upon incubation of these cells with metabolite. In contrast, the uric acid concentration was not altered. Moreover, intercellular adhesion molecule-1, CD80, and CD86 expressions did not change when NHEKs were exposed to these reactive metabolites. Our data suggest that NHEKs selectively up-regulate certain danger signals when exposed to arylhydroxylamine metabolites. These signals may subsequently activate dendritic cells and initiate an immune response within skin.

Odontogenic focal infection could be partly involved in the pathogenesis of atopic dermatitis as exacerbating factor

BACKGROUND

A focal infection has been reported to be associated with the pathogenesis of various skin diseases, but, to date, not atopic dermatitis (AD). The objective of the study was to clarify whether the odontogenic focal infection (OFI) could be recognized as one of the exacerbating factors in AD.

METHODS

Forty-three patients with AD whose skin conditions were resistant to conventional therapy were examined. An OFI was evaluated by using radiographs. Serum IgE/sCD30 levels were also examined. Skin condition was evaluated by the eczema area and severity index (EASI).

RESULTS

Odontogenic focal infection was detected in 13 patients (30%) and this incidence was higher than in the normal population. Moreover, a 3-month therapy including dental care improved the skin conditions of patients with OFI better than those without OFI.

CONCLUSION

The study concluded that OFI could be involved in the pathogenesis of some types of AD as exacerbating factors.

Koebner phenomenon in lupus erythematosus with special consideration of clinical findings

The isomorphic response of Koebner can be observed not only in psoriasis, but also in other diseases, such as lichen planus and some systemic diseases including LE (lupus erythematosus) or sarcoidosis. Several clinical findings in LE skin were presented and discussed in this review. The mutually-interactive-, negative-, and internal-Koebner phenomena were introduced and discussed with some speculative views. Many forms of environmental stress on the skin were reported as provocating factors of the Koebner phenomenon, including trauma, scratching, UV-exposure, and various types of dermatitis. Clinical observations of the nature, localization, and movement of lesions should be carefully made. The pathophysiology of the Koebner phenomenon may be classified into two steps. A first non-specific inflammatory step and a second disease-specific step. The inflammatory products released from the first step would be targeted in the second step. In the first step, there could be many substances including cytokines, stress proteins, adhesion molecules, or autoantigens translocated from intra-cellular areas. In the second step after latent periods, there may be disease-specific reactions, including ones by T-cells, B-cells, autoantibodies, and immune deposits, under the restriction of genetic backgrounds. The Koebner phenomenon may prove useful in understanding the pathophysiology of diseases of unknown origin.

Heat shock proteins 60 and 70 expression of cutaneous lichen planus: comparison with normal skin and psoriasis vulgaris*

BACKGROUND

Heat shock proteins (HSPs) are expressed by most living cells and play fundamental roles in many biological processes. Their synthesis increases by a variety of stresses in order to enable cellular survival. Although it is known that they play an important role in immune and inflammatory responses of the skin, the role of HSPs in the pathogenesis of skin diseases has been studied in only limited skin diseases. Lichen planus (LP) is a relatively common papulosquamous dermatosis, and cell-mediated immunity plays an important role in its pathogenesis. Although an altered expression of certain HSPs was reported in oral LP lesions, the expression of HSPs in cutaneous lesions of LP has not been investigated. In this immunohistochemical study, we aimed at investigating the role of HSPs in the pathogenesis of LP by studying whether there is any difference in HSP expression in cutaneous lesions of LP when compared to normal skin and psoriasis vulgaris (PV).

METHODS

Formalin-fixed paraffin-embedded skin biopsy specimen blocks from LP patients (n = 39), patients with psoriasis (n = 20), and normal skin controls (n = 20) were used in the study. Antibodies to HSPs 60 and 70 were applied immunohistochemically by using streptavidin-biotin-horseradish peroxidase complex. An immunoreactivity intensity distribution index (IRIDI) was calculated to express the proportion of the immunoreactive cells as well as the staining intensity in different layers of the epidermis.

RESULTS

The mean IRIDI scores for HSP60 expression in the basal, suprabasal, and superficial epidermal layers of cutaneous LP were moderately higher than those of normal skin, but not different from those of PV skin. These scores for HSP70 in lesions of LP were moderately lower than those for normal skin in the basal layer, but not significantly different from normal in the other two layers. Scores for HSP70 in PV lesions were markedly lower in all three layers. In the cells of the inflammatory infiltrates (mostly lymphocytes), HSP60 scores for LP were moderately higher, compared to those for PV, whereas scores for HSP70 were much lower for LP and very much lower for PV.

CONCLUSIONS

Significantly altered levels of HSP proteins were found in cutaneous LP lesions in comparison with normal skin and psoriasis, suggesting the role of HSPs in the pathogenesis of LP.