Tetsuya Koga

Cytokines and chemokines in the epidermis

Keratinocytes (KC) produce a vast repertoire of cytokines, including interleukins, growth factors, colony stimulating factors, and chemokines. Under normal conditions, most of them are not synthesized or remain in the cytoplasm, but external stimuli, such as trauma, bacterial infections, chemical substances, or ultraviolet irradiation induce the production and release of these cytokines from KC. KC-derived cytokines regulate the immune and inflammatory responses through their receptors on KC, Langerhans cells, dermal fibroblasts and endothelial cells, and infiltrating T-cells.

Clinical dose and adverse effects of topical steroids in daily management of atopic dermatitis

Backgroundu2003 Topical steroids are used as the first‐line therapy for atopic dermatitis.

Propionibacterium acnes-induced IL-8 production may be mediated by NF-κB activation in human monocytes

Propionibacterium acnes (P. acnes) causes an inflammatory acne that is characterized by massive neutrophilic infiltration. IL-8 is thought to play an important role in the pathophysiology of P. acnes, although the mechanisms by which P. acnes up-regulates the release of IL-8, a neutrophilic chemokine, from target cells is not well understood. In this study, we investigated the mechanisms through which heat-killed P. acnes induces IL-8 production in THP-1 cells (a human monocytic cell line). We found that P. acnes is able to directly induce IL-8 production and IL-8 mRNA expression in human monocytic cells in a dose- and time-dependent manner through a mechanism requiring transcription factor NF-kappaB activation. Additionally, P. acnes-induced IL-8 secretion was inhibited by roxithromycin, a macrolide antibiotic, and its inhibitory effect seemed to be partially associated with the inhibition of P. acnes-induced NF-kappaB activation. This is the first study to show that NF-kappaB activation is involved in the IL-8 production of monocytic cells stimulated by P. acnes.

Histamine-induced IL-6 and IL-8 production are differentially modulated by IFN-γ and IL-4 in human keratinocytes

It is known that large amounts of histamine are stored in mast cells located in the superficial dermis of the skin and can be released upon appropriate stimulation. However, the effects of histamine on keratinocyte function have not been well characterized. We therefore examined the capacity of histamine to modulate the production of interleukin (IL)-6 and IL-8 by keratinocytes. We found that histamine significantly augmented the production of IL-6 and IL-8 in a dose- and time-dependent manner. The enhancing effects of histamine were completely inhibited by a potent H1 receptor (H1R) antagonist, emedastine difumarate. Pyrilamine (a much weaker H1R antagonist) and cimetidine (an H2R antagonist) only partially inhibited the enhancing effects of histamine. The histamine-induced up-regulation of IL-6 and IL-8 production, however, was completely abrogated by a combination of pyrilamine and cimetidine. The IL-6 production was significantly enhanced by interferon (IFN)-gamma. Interestingly, IFN-gamma and IL-4 both significantly augmented the histamine-induced IL-6 production. On the other hand, the production of IL-8 was inhibited by IFN-gamma, and IFN-gamma and IL-4 both completely abrogated the histamine-induced IL-8 production. These results suggest that the histamine-induced IL-6 production and IL-8 production are differentially regulated by IFN-gamma and IL-4. Histamine may be an important modulator of cytokine production in epidermal milieu.

Clinicopathological features of cutaneous lesions of adult T-cell leukaemia/ lymphoma.

Backgroundu2002 Adult T‐cell leukaemia/lymphoma (ATLL) is a human malignancy associated with human T‐cell leukaemia virus type I (HTLV‐I). ATLL frequently involves the skin.

Interleukin-8-positive neutrophils in psoriasis

We performed an immunohistochemical study to try to determine the cellular source of interleukin-8 (IL-8) in psoriatic skin lesions. IL-8 was positively stained in the vast majority of neutrophils but not in the mononuclear cells, macrophages, or keratinocytes. IL-8-positive neutrophils were seen both in Munros microabcesses in cases of psoriasis vulgaris and in a small spongiform pustule and much larger macropustules of Kogoj in cases of pustular psoriasis. Some IL-8-positive neutrophils were observed in the upper dermis of pustular psoriasis. The staining was considered to be specific because it could be completely blocked by preabsorption with recombinant IL-8. In addition, stimulation of human neutrophils with lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) for 18 h induced IL-8 production in vitro. In our study, IL-8 was expressed in the neutrophils of psoriasis, suggesting that neutrophils are one of the sources of IL-8 in psoriasis. The expression of IL-8 and the influx of neutrophils led us to speculate that the IL-8 autocrine and/or paracrine system functions in the formation of the microabcesses and pustules in proriasis.

Therapeutic Approaches to Subcutaneous Mycoses

Subcutaneous mycoses, which are much less common than superficial fungal infections, are characterized by a heterogeneous group of infections that often result from direct penetration of the fungus into the dermis and subcutaneous tissue through traumatic injury. The fungus spreads by local deep tissue invasion from the inoculation site. The disease usually remains localized and then slowly spreads to adjacent tissue and eventually to the lymphatics. More rarely, hematogenous dissemination is observed. There are usually various clinical features and thus a broad range of differential diagnoses. The common subcutaneous mycoses are sporotrichosis, chromoblastomycosis, phaeohyphomycosis, eumycotic mycetoma, and hyalohyphomycosis. Many subcutaneous mycoses are confined to the tropical and subtropical regions, but some, such as sporotrichosis, are also prevalent in temperate regions. Subcutaneous mycoses can occur in healthy individuals. In immunocompromised individuals, these infections can disseminate widely.Treatment usually involves use of antifungal agents and/or surgical excision. Treatment of some serious subcutaneous mycoses remains unresolved, and there have been reports of relapses or progression during therapy and problems with lack of tolerability of antifungal drugs. Identification of the etiologic agent by culture is essential for prognostic and management considerations, since some fungi are more frequently associated with dissemination. Results of antifungal susceptibility tests may provide valuable information for deciding the appropriate method of treatment. Development of new antifungal agents and combination therapies may result in improvement in the management of subcutaneous mycoses in the future.

Differential regulation of thymus- and activation-regulated chemokine induced by IL-4, IL-13, TNF-α and IFN-γ in human keratinocyte and fibroblast

Abstract The CC chemokine thymus- and activation-regulated chemokine (TARC/CCL17) acts on CC chemokine receptor 4 (CCR4), which is known to be selectively expressed in Th2 cells. In order to compare the regulatory profiles of TARC production by tumor necrosis factor-α (TNF-α), IFN-γ, interleukin-4 (IL-4) and IL-13 in keratinocytes and fibroblasts, HaCaT cells, a human keratinocyte cell line, and NG1RGB cells, a human skin fibroblast cell line, were used. The expression of TARC protein was measured using enzyme-linked immunosorbent assay (ELISA), and the mRNA level was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The spontaneous expression of TARC protein and mRNA levels were augmented by TNF-α and IFN-γ and were inhibited by IL-4 and IL-13 in the keratinocytes. The fibroblasts expressed the TARC protein and mRNA only in the presence of IL-4+TNF-α or IL-13+TNF-α stimulation. IFN-γ further enhanced the IL-4+TNF-α or IL-13+TNF-α-induced TARC production in the fibroblasts. Thus, TNF-α and IFN-γ -induced TARC production was differentially regulated by IL-4 and IL-13 in human keratinocytes and fibroblasts.

Dosage and Adverse Effects of Topical Tacrolimus and Steroids in Daily Management of Atopic Dermatitis

Since 1999, combination therapy with tacrolimus and topical steroids has been widely used for the treatment of adolescent/adult‐type atopic dermatitis. In order to determine the clinical doses of topical tacrolimus and steroids for daily treatment of atopic dermatitis and to elucidate their beneficial and adverse effects, we analyzed the clinical data from 215 patients with atopic dermatitis who were more than 16 years old. Less than 70g of tacrolimus and less than 15 g of steroids were applied to 90% of the patients on the face and neck, and less than 75.8 g of tacrolimus and less than 322 g of steroids were applied to 90% of the patients on the trunk and extremities during the six‐month treatment period. Topical tacrolimus is much more frequently used on face and neck lesions (99.1%); in only 39.5% of cases was it used on the trunk and extremities. The majority of patients improved after six months of the combination topical therapy; however, atopic dermatitis was not controlled in 6% of the patients. The combination therapy did not seem to increase the risk of cutaneous infections; however, the incidence of herpes simplex infection on the face and neck was 2.8% at pre‐treatment and slightly increased to 4.7% during the therapy. The incidence of all steroid‐induced adverse effects was reduced both in frequency and intensity with a decrease in the dose of topical steroids through simultaneous tacrolimus application. Combination therapy with topical tacrolimus and steroids is useful for treating atopic dermatitis, but a small percentage of the patients still cannot be satisfactorily treated. For such patients, adjustments of the dose and rank of topical steroids and tacrolimus and other therapeutic adjuncts are necessary.

Intermittent topical corticosteroid/tacrolimus sequential therapy improves lichenification and chronic papules more efficiently than intermittent topical corticosteroid/emollient sequential therapy in patients with atopic dermatitis.

Atopic dermatitis (AD) is a common, chronic, relapsing, severely pruritic, eczematous skin disease. Topical steroids are the mainstay of treatment. However, the adverse effects of steroids on hormonal function are the major obstacle for their use as long‐term topical therapy. Intermittent dosing with potent topical steroids and/or combination therapy with steroid and tacrolimus have been frequently used in the daily management of AD to overcome the problems accompanying the long term use of steroids. We compared the clinical effects of topical steroid/tacrolimus and steroid/emollient combination treatments in 17 patients with AD. An intermittent topical betamethasone butyrate propionate/tacrolimus sequential therapy improved lichenification and chronic papules of patients with AD more efficiently than an intermittent topical betamethasone butyrate propionate/emollient sequential therapy after four weeks of treatment. Only one out of 17 patients complained of a mild, but temporary, burning sensation after tacrolimus application. The intermittent topical steroid/tacrolimus sequential therapy may be a useful adjunctive treatment for AD.