Cathepsin K is involved in development of psoriasis-like skin lesions through TLR-dependent Th17 activation.

Cathepsins (CTSs) are lysosomal cysteine proteases that play an important role in the turnover of intracellular proteins and extracellular proteins, such as the degradation of extracellular matrices and the processing of antigenic proteins. A CTS inhibitor, NC-2300, not only suppresses bone erosion by inhibition of cathepsin K (CTSK), but also ameliorates paw swelling at inflamed joints in adjuvant-induced arthritis in rats. It has been demonstrated that the amelioration of joint inflammation by NC-2300 is mediated by the downregulation of cytokine expression in dendritic cells, which are essential for Th17 activation. In this work, we studied the role for CTSs in the pathogenesis of psoriasis-like lesion in K5.Stat3C mice, a mouse model of psoriasis, in which Th17 contributes to lesion development similar to psoriasis. Psoriatic lesions expressed increased levels of Ctsk and Ctss mRNA compared with uninvolved skin and normal control skin. Similarly, the epidermis and dermis in K5.Stat3C mice demonstrated increased CTSK activities, which were sensitive to NC-2300. Topical treatment with NC-2300 significantly ameliorated 12-O-tetradecanoylphorbol-13-acetate-induced psoriasis-like lesions in K5.Stat3C mice, and downregulated the expression of IL-12, IL-23, and Th17 cytokines. In vitro experiments revealed that TLR7 activation of bone marrow-derived myeloid dendritic cells led to increase in IL-23 at mRNA and protein levels, which were downregulated by NC-2300. These results suggest that CTSK plays a role in development of psoriatic lesions through TLR7-dependent Th17 polarization.

Imiquimod attenuates the growth of UVB-induced SCC in mice through Th1/Th17 cells.

Imiquimod (IMQ), a Toll-like receptor (TLR) 7/8 agonist, has been used to treat various skin neoplasms, including genital warts, actinic keratoses, and superficial basal cell carcinomas. Although IMQ has been recognized to activate both innate and adaptive immunity, the underlying mechanism(s) by which IMQ exerts its anti-tumor activity in vivo remains largely unknown. In this study, we took advantage of skin cancer-prone mice to characterize the effects of IMQ on ultraviolet irradiation (UV)-induced de novo carcinogenesis. Transgenic mice with keratinocytes expressing constitutively activated Stat3 (K5.Stat3C mice) developed squamous cell carcinomas (SCC in situ) as early as after 14 wk of UVB irradiation, while wild-type mice required much higher doses of UVB with more than 25 wk of UVB irradiation to produce SCC. Topical treatment of K5.Stat3C mice with IMQ attenuated UVB-induced epidermal dysplasia (SCC in situ). In addition, SCC growth due to increased total irradiation doses was significantly attenuated by IMQ treatment. Topical IMQ treatment induced T cell and plasmacytoid dendritic cell infiltrates at the tumor sites, where levels of IL-12/23p40, IL-12p35, IL-23p19, IL-17A, and IFN-γ mRNAs were up-regulated. Immunohistochemistry revealed T cell infiltrates consisting of T1, Th17, and CD8(+) T cells. We speculate that topical IMQ treatment attenuates the de novo growth of UVB-induced SCC through activation of Th17/Th1 cells and cytotoxic T lymphocytes.

Distinct roles of IL-23 and IL-17 in the development of psoriasis-like lesions in a mouse model.

Psoriasis is an inflammatory disease with dynamic interactions between the immune system and the skin. The IL-23/Th17 axis plays an important role in the pathogenesis of psoriasis, although the exact contributions of IL-23 and IL-17 in vivo remain unclear. K5.Stat3C transgenic mice constitutively express activated Stat3 within keratinocytes, and these animals develop skin lesions with histological and cytokine profiles similar to those of human plaque psoriasis. In this study, we characterized the effects of anti-mouse IL-17A, anti-mouse IL-12/23p40, and anti-mouse IL-23p19 Abs on the development of psoriasis-like lesions in K5.Stat3C transgenic mice. Treatment with anti-IL-12/23p40 or anti-IL-23p19 Abs greatly inhibited 12-O-tetradecanoylphorbol-13-acetate-induced epidermal hyperplasia in the ears of K5.Stat3C mice, whereas the inhibitory effect of an anti-IL-17A Ab was relatively less prominent. Treatment with anti-IL-12/23p40 or anti-IL-23p19 Abs markedly lowered transcript levels of Th17 cytokines (e.g., IL-17 and IL-22), ß-defensins, and S100A family members in skin lesions. However, anti-IL-17A Ab treatment did not affect mRNA levels of Th17 cytokines. Crossing IL-17A-deficient mice with K5.Stat3C mice resulted in partial attenuation of 12-O-tetradecanoylphorbol-13-acetate-induced lesions, which were further attenuated by anti-IL-12/23p40 Ab treatment. FACS analysis of skin-draining lymph node cells from mice that were intradermally injected with IL-23 revealed an increase in both IL-22-producing T cells and NK-22 cells. Taken together, this system provides a useful mouse model for psoriasis and demonstrates distinct roles for IL-23 and IL-17.

Combined Bowen disease and extramammary Paget disease.

BACKGROUND: The histological resemblance between extramammary Paget disease and Bowen disease has been described since Bowen's original article was published in 1912. METHODS: We herein describe a case of vulval primary extramammary Paget disease in a 61-year-old women with the histological features of Bowen disease. RESULTS: Histological examination of a biopsy specimen showed acanthosis with full-thickness cellular atypia, focal hyperkeratosis and parakeratosis in the epidermis, and no characteristic Paget cells were observed. However, histological examination of an operative specimen revealed areas characteristic of Paget disease and Bowen disease. Overall, the areas characteristic of Bowen disease and Paget disease occupied 6% and 32% of the total operative specimen, respectively. The two areas were sharply separated. Immunohistochemical findings showed carcinoembryonic antigen to be expressed in areas containing Paget cells, but not in the areas characteristic of Bowen disease. Cytokeratin 7 (CK7) (OV-TL 12/30) and CK8 (35betaH11) were strongly expressed in both of these areas. The staining for high-molecular-weight cytokeratins was negative in both of these areas. CONCLUSIONS: Our findings indicated that primary extramammary Paget disease and squamous cell carcinoma in situ arose multifocally from a common cell in the epidermis.

Neuronal conditions of spinal cord in dermatitis are improved by olopatadine.

Intense pruritus and cutaneous reactivity represent cardinal features of eczema. The resulting scratching behaviors alter neuronal conditions of the spinal dorsal horn where the primary sensory afferent fibers transmit cutaneous stimulation and deteriorate eczematous skin lesions. We investigated the effects of olopatadine hydrochloride (olopatadine) on alteration of neuronal conditions of the spinal dorsal horn and eczematous skin lesions induced by contact dermatitis. Eczematous lesions were induced by repeated application of diphenylcyclopropenone (DCP) in BALB/c mice. Olopatadine suppressed scratching behavior caused by repeated application of DCP in mice. Increased expressions of c-Fos and substance P in the spinal dorsal horn following DCP application were improved by olopatadine. Furthermore, olopatadine diminished the number of infiltrating cells and levels of cytokines in eczematous skin lesions resulting from DCP application. Olopatadine improves neurological conditions in the spinal cord and eczematous skin lesions in a murine contact dermatitis model.

Epicutaneous application of toll-like receptor 7 agonists leads to systemic autoimmunity in wild-type mice: a new model of systemic Lupus erythematosus.

OBJECTIVE: To examine whether topical treatment of wild-type mice with Toll-like receptor 7 (TLR-7) agonists leads to lupus-like autoimmunity. METHODS: Wild-type FVB/N, BALB/c, and C57BL/6 mice were treated with the topical TLR-7 agonist imiquimod or R848 administered to the ear 3 times weekly. During treatment, the mice were monitored for serum autoantibody and creatinine levels as well as histopathology of the kidneys, spleens, livers, hearts, and skin. Immunologic abnormalities were analyzed by immunohistochemistry, quantitative reverse transcription-polymerase chain reaction, and fluorescence-activated cell sorting. The role of plasmacytoid dendritic cells (PDCs) in the development of autoimmune disease was validated by in vivo treatment with an anti-PDC antibody. Diseased mice underwent ultraviolet B irradiation, to evaluate skin photosensitivity. The disease-causing effect of topical application of imiquimod was compared with that of systemic (intraperitoneal) administration. TLR-7- and TLR-9-deficient mice were used to validate the role of TLR-7. RESULTS: Wild-type mice of different genetic backgrounds developed systemic autoimmune disease following 4 weeks of topical treatment with imiquimod or R848, with elevated levels of autoantibodies to double-stranded DNA and multiple organ involvement, including glomerulonephritis, hepatitis, carditis, and photosensitivity. Expression of Ifna and Mx1, the interferon-α-stimulated gene, was up-regulated in the organs of imiquimod-treated mice. However, disease caused by intraperitoneal injection of imiquimod was less severe than that induced by topical application. In vivo depletion of PDCs by a specific antibody protected mice against the autoimmunity induced by topical administration of imiquimod, suggesting a role of PDCs. Furthermore, TLR-7-deficient mice, but not TLR-9-deficient mice, were protected against autoimmunity. CONCLUSION: This protocol provides a novel model of inducible systemic lupus erythematosus in wild-type mice and underscores the skin as the primary organ that allows TLR-7 agonists to induce SLE.