Expression of filaggrin-2 protein in the epidermis of human skin diseases: a comparative analysis with filaggrin.

Filaggrin-2 is a member of the S100 fused-type protein family, and the structural features and expression of filaggrin-2 are similar to those of profilaggrin, a protein essential for keratinization. In the present study, we investigated the expression profile of filaggrin-2 in patients with skin diseases using antibodies against the repetitive region of filaggrin-2. In tissue samples from patients with skin diseases which are associated with a decrease in filaggrin, including ichthyosis vulgaris, atopic dermatitis and psoriasis vulgaris, the expression level of filaggrin-2 was markedly decreased compared to that in normal skin samples. In contrast, the expression of filaggrin-2 increased in parallel with that of filaggrin in samples of tissue from patients with skin diseases associated with hyperkeratosis, such as lichen planus and epidermolytic ichthyosis. Interestingly, filaggrin-2 signals were observed in slightly higher layers of the epidermis in comparison to those of filaggrin. Similarly, the expression of filaggrin-2 proteins was induced slightly later than filaggrin in the cultured keratinocytes. These findings suggest that filaggrin-2 may play an overlapping role with filaggrin in epithelial cornification; however, it may also have a partially distinct role in the molecular processes of cornification.

Successful treatment of lichen amyloidosis using a CO2 surgical laser.

Lichen amyloidosis (LA) is a type of primary localized cutaneous amyloidosis characterized by multiple pruritic discrete hyperkeratotic papules with amyloid deposition in the papillary dermis. Two patients with LA had been treated with topical corticosteroids, but with no effect on the eruptions. The present authors then started treating the affected area by superficial ablation using a CO2 surgical laser (LASER 30C, Lumenis Inc., Yokneum, Israel) at a setting of 10-15 watts with a 0.12-second pulse duration, 0.36-second rest duration, and 5-mm laser spot size. The present authors treated the patients twice a month with the CO2 laser. The papules on the legs had flattened in both patients, with a great improvement in the severe itching after 6 months in Case 1 and after 10 months in Case 2. These cases indicate that the CO2 laser led to a good response in terms of the clinical manifestations, and may be useful for the treatment of LA.

Trichohyalin-like 1 protein, a member of fused S100 proteins, is expressed in normal and pathologic human skin.

Trichohyalin-like 1 (TCHHL1) protein is a novel member of the fused-type S100 protein gene family. The deduced amino acid sequence of TCHHL1 contains an EF-hand domain in the N-terminus, one trans-membrane domain and a nuclear localization signal. We generated specific antibodies against the C-terminus of the TCHHL1 protein and examined the expression of TCHHL1 proteins in normal and pathological human skin. An immunohistochemical study showed that TCHHL1 proteins were expressed in the basal layer of the normal epidermis. In addition, signals of TCHHL1 proteins were observed around the nuclei of cultured growing keratinocytes. Accordingly, TCHHL1 mRNA has been detected in normal skin and cultured growing keratinocytes. Furthermore, TCHHL1 proteins were strongly expressed in the peripheral areas of tumor nests in basal cell carcinomas and squamous cell carcinomas. A dramatic increase in the number of Ki67 positive cells was observed in TCHHL1-expressing areas. The expression of TCHHL1 proteins also increased in non-cancerous hyperproliferative epidermal tissues such as those of psoriasis vulgaris and lichen planus. These findings highlight the possibility that TCHHL1 proteins are expressed in growing keratinocytes of the epidermis and might be associated with the proliferation of keratinocytes.

Involvement of serine protease and proteinase-activated receptor 2 in dermatophyte-associated itch in mice.

We investigated the involvement of serine protease and proteinase-activated receptor 2 (PAR(2)) in dermatophyte-induced itch in mice. An intradermal injection of an extract of the dermatophyte Arthroderma vanbreuseghemii (ADV) induced hind-paw scratching, an itch-related behavior. ADV extract-induced scratching was inhibited by the opioid receptor antagonists naloxone and naltrexone, the serine protease inhibitor nafamostat mesylate, and the PAR(2) receptor antagonist FSLLRY-NH(2). ADV extract-induced scratching was not inhibited by the H(1) histamine receptor antagonist terfenadine or by mast cell deficiency. Heat pretreatment of the ADV extract markedly reduced the scratch-inducing and serine protease activities. Proteolytic cleavage within the extracellular N terminus of the PAR(2) receptor exposes a sequence that serves as a tethered ligand for the receptor. The ADV extract as well as tryptase and trypsin cleaved a synthetic N-terminal peptide of the PAR(2) receptor. The present results suggest that serine protease secreted by dermatophytes causes itching through activation of the PAR(2) receptors, which may be a causal mechanism of dernatophytosis itch.

UV-B radiation induces macrophage migration inhibitory factor-mediated melanogenesis through activation of protease-activated receptor-2 and stem cell factor in keratinocytes.

UV radiation indirectly regulates melanogenesis in melanocytes through a paracrine regulatory mechanism involving keratinocytes. Protease-activated receptor (PAR)-2 activation induces melanosome transfer by increasing phagocytosis of melanosomes by keratinocytes. This study demonstrated that macrophage migration inhibitory factor (MIF) stimulated PAR-2 expression in human keratinocytes. In addition, we showed that MIF stimulated stem cell factor (SCF) release in keratinocytes; however, MIF had no effect on the release of endothelin-1 or prostaglandin E2 in keratinocytes. In addition, MIF had no direct effect on melanin and tyrosinase synthesis in cultured human melanocytes. The effect of MIF on melanogenesis was also examined using a three-dimensional reconstituted human epidermal culture model, which is a novel, commercially available, cultured human epidermis containing functional melanocytes. Migration inhibitory factor induced an increase in melanin content in the epidermis after a 9-day culture period. Moreover, melanin synthesis induced by UV-B stimulation was significantly down-regulated by anti-MIF antibody treatment. An in vivo study showed that the back skin of MIF transgenic mice had a higher melanin content than that of wild-type mice after 12 weeks of UV-B exposure. Therefore, MIF-mediated melanogenesis occurs mainly through the activation of PAR-2 and SCF expression in keratinocytes after exposure to UV-B radiation.

Ultraviolet B irradiation induces the expression of hornerin in xenotransplanted human skin.

Ultraviolet (UV) irradiation exerts numerous effects on the skin. Exposure of human skin to UVB at doses that induce mild sunburn reactions causes epidermal hyperproliferation and alterations in the expression of several epidermal differentiation markers. This study investigated the effects of UVB irradiation on the expression of hornerin, a member of the S100 fused-type protein family, using the xenotransplantation of normal human skin onto nude mice. Hornerin mRNA was detected in the UVB-irradiated skin on day 2 using RT-PCR. In accordance with the results of the RT-PCR, the expression of hornerin was induced in the granular layers of the UVB-exposed skin beginning two days after UVB irradiation and occurred in parallel with the expressions of cytokeratin 6 and Ki67. This finding suggests that hornerin induction in UVB-irradiated skin might be associated with epidermal hyperproliferation. This study demonstrated that hornerin is a protein whose expression is changed by UVB irradiation and suggests that the expression of hornerin might be a useful marker of acute UV damage in skin.

Efficacy of chlorhexidine gluconate ointment (Oronine H(®)) for experimentally-induced comedones.

BACKGROUND: Oronine H(®) ointment, which contains chlorhexidine gluconate as its active component, is a well known disinfectant, and has been widely used for treatment of acne in Japan. In this study, we investigated the inhibitory effect of this ointment on the formation of comedones induced by application of 50% oleic acid on the orifices of the external auditory canals of rabbits. METHODS: The application sites were observed with a dermatoscope, and the area of the hair pores was measured using an Image analysis software program. RESULTS: The chlorhexidine gluconate ointment inhibited comedone formation significantly more effectively than the liquid paraffin used as a control (P < 0.001). We also investigated the therapeutic effect of this ointment on comedones. After starting application of chlorhexidine gluconate ointment or liquid paraffin on the comedone area, the hair pore size was gradually decreased in the group treated with chlorhexidine gluconate ointment compared with the hair pore size at baseline. CONCLUSION: These results suggest that chlorhexidine gluconate ointment is effective for inhibiting comedone formation as well as for treating already formed comedones. Chlorhexidine gluconate ointment is a useful topical medicine for the treatment of early-stage acne and for preventing acne.