Matrix metalloproteinases (MMPs) are zinc-containing endopeptidases with an extensive range of substrate specificities. Collectively, these enzymes are able to degrade various components of extracellular matrix (ECM) proteins. Based on their structure and substrate specificity, they can be categorized into five main subgroups, namely (1) collagenases (MMP-1, MMP-8 and MMP-13); (2) gelatinases (MMP-2 and MMP-9); (3) stromelysins (MMP-3, MMP-10 and MMP-11); (4) matrilysins (MMP-7 and MMP-26); and (5) membrane-type (MT) MMPs (MMP-14, MMP-15, and MMP-16). The alterations made to the ECM by MMPs might contribute in skin wrinkling, a characteristic of premature skin aging. In photocarcinogenesis, degradation of ECM is the initial step towards tumor cell invasion, to invade both the basement membrane and the surrounding stroma that mainly comprises fibrillar collagens. Additionally, MMPs are involved in angiogenesis, which promotes cancer cell growth and migration. In this review, we focus on the present knowledge about premature skin aging and skin cancers such as basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma, with our main focus on members of the MMP family and their functions.

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Psoriasis is an immune-mediated genetic skin disease. The underlying pathomechanisms involve complex interaction between the innate and adaptive immune system. T cells interact with dendritic cells, macrophages, and keratinocytes, which can be mediated by their secreted cytokines. In the past decade, biologics targeting tumor necrosis factor-α, interleukin (IL)-23, and IL-17 have been developed and approved for the treatment of psoriasis. These biologics have dramatically changed the treatment and management of psoriasis. In contrast, various triggering factors can elicit the disease in genetically predisposed individuals. Recent studies suggest that the exacerbation of psoriasis can lead to systemic inflammation and cardiovascular comorbidity. In addition, psoriasis may be associated with other auto-inflammatory and auto-immune diseases. In this review, we summarize the risk factors, which can be divided into two groups (namely, extrinsic and intrinsic risk factors), responsible for the onset and exacerbation of psoriasis in order to facilitate its prevention.

Atopic dermatitis (AD) is a chronic relapsing eczematous skin disease characterized by pruritus and inflammation and accompanied by cutaneous physiological dysfunction (dry and barrier-disrupted skin). Most of the patients have atopic diathesis. A standard guideline for the management (diagnosis, severity classification and therapy) of AD has been established. In our guideline, the necessity of dermatological training is emphasized in order to assure diagnostic skill and to enable evaluation of the severity of AD. The definitive diagnosis of AD requires the presence of all three features: (i) pruritus; (ii) typical morphology and distribution; and (iii) chronic and chronically relapsing course. For the severity classification of AD, three elements of eruption (erythema ⁄ acute papules, exudation ⁄ crusts and chronic papules ⁄ nodules ⁄ lichenification) are evaluated in the most severely affected part of each of the five body regions (head ⁄ neck, anterior trunk, posterior trunk, upper limbs and lower limbs). The areas of eruption on the five body regions are also evaluated, and both scores are totaled (maximum 60 points). The present standard therapies for AD consist of the use of topical corticosteroids and tacrolimus ointment as the main treatment for the inflammation, topical application of emollients to treat the cutaneous physiological dysfunction, systemic antihistamines and anti-allergic drugs as adjunctive treatments for pruritus, avoidance of apparent exacerbating factors, psychological counseling and advice about daily life. Tacrolimus ointment (0.1%) and its low-density ointment (0.03%) are available for adult patients and 2-15-year-old patients, respectively. The importance of the correct selection of topical corticosteroids according to the severity of the eruption is also emphasized. Furthermore, deliberate use of oral cyclosporine for severe recalcitrant adult AD is referred.

Generalized pustular psoriasis (GPP) is a severe inflammatory skin disease characterized by the presence of sterile pustules covering almost the entire body and systemic symptoms such as fever. Secukinumab, a fully human-recombinant anti-interleukin-17A monoclonal antibody was indicated for psoriasis vulgaris and psoriatic arthritis in Japan but is not yet investigated for GPP. In this phase III, open-label multicenter single arm study, the efficacy and safety of secukinumab as monotherapy or with co-medication was evaluated in 12 Japanese patients with GPP. All the patients received secukinumab 150 mg s.c. at baseline, week 1, 2, 3 and 4, and then every 4 weeks. Two non-responders were up-titrated to 300 mg. Change in GPP severity from baseline was evaluated by clinical global impression (CGI) categorized as "worsened", "no change", "minimally improved", "much improved" or "very much improved". Treatment success was achieved by 83.3% (n = 10) of patients at week 16 (primary end-point) with CGI evaluated as "very much improved" (n = 9) and "much improved" (n = 1). Moreover, the area of erythema with pustules improved as early as week 1 and resolved by week 16 in most of the patients. The improvements were sustained throughout 52 weeks. Over the 52-week treatment period, secukinumab was well tolerated with no unexpected safety signals. Nasopharyngitis, urticaria, diabetes mellitus and arthralgia were the frequent adverse events reported. The data from this study shows that secukinumab can become one of the potent treatment options for GPP.

IFN-λ 1, -λ 2 and -λ 3 have been discovered as the latest members of the class II cytokine family and shown to possess antiviral activity. Murine B16 melanoma and Colon26 cancer cells were transduced with mouse IFN-λ to determine whether IFN-λ possesses antitumor activity. Overexpression of IFN-λ induced cell surface MHC class I expression and Fas/CD95 Ag, induced significant caspase-3/7 activity, and increased p21Waf1/Cip1 and dephosphorylated Rb (Ser780) in B16 cells in vitro. IFN-λ expression in tumor cell lines markedly inhibited s.c. and metastatic tumor formation in vivo compared with mock transfections (p < 0.05). Moreover, IFN-λ expression induced lymphocytic infiltrates, and an Ab-mediated immune cell depletion assay showed that NK cells were critical to IFN-λ-mediated tumor growth inhibition. Hydrodynamic injection of IFN-λ cDNA successfully targeted liver metastatic foci of Colon26 cells, and moderately decreased the mortality of mice with tumors. IFN-λ overexpression in the liver increased NK/NKT cells and enhanced their tumor-killing activity, and suggested the activation of innate immune responses. Thus, IFN-λ induced both tumor apoptosis and NK cell-mediated immunological tumor destruction through innate immune responses. These findings suggested that local delivery of IFN-λ might prove a useful adjunctive strategy in the clinical treatment of human malignancies.

Incidence of psoriasis vulgaris in Asians is estimated at 0.05-0.3%. Studies in North America and Europe demonstrated that adalimumab, a fully human, recombinant, immunoglobulin G 1 monoclonal antibody, was efficacious and well-tolerated in patients with chronic plaque psoriasis. This 24-week, placebo-controlled study evaluated the efficacy and safety of three different dosing regimens of adalimumab in Japanese patients with moderate to severe chronic plaque psoriasis (n = 169). Patients were randomized to receive adalimumab 40 mg every other week (eow), adalimumab 80-mg loading dose at week 0 followed by adalimumab 40 mg eow starting at week 2, adalimumab 80 mg eow, or placebo eow given as s.c. injections. The primary efficacy endpoint was the percentage of patients achieving a 75% or greater improvement in Psoriasis Area and Severity Index (PASI 75) score at week 16. At week 16, PASI 75 response rates were significantly greater for all three adalimumab groups (40 mg eow: 57.9%, P < 0.001; 40 mg eow plus loading dose: 62.8%, P < 0.001; 80 mg eow: 81.0%, P < 0.001) versus placebo (4.3%). As early as week 4, the 40-mg eow plus loading dose and 80-mg eow groups achieved significantly greater PASI 75 response rates compared with placebo. Injection-site reactions and hepatic events occurred in greater percentages of adalimumab-treated patients compared with placebo. Adalimumab therapy demonstrated efficacy and safety at all three dosage regimens. Rapid response rate in patients receiving 40 mg eow plus loading dose supports using an 80-mg loading dose in the treatment of psoriasis.

Epidermal inUury results in activation of keratinocytes which produce and respond to growth factors and cytokines and become migratory. Activated keratinocytes express a specific pair of keratin proteins, K6 and K16, distinct from the keratins in the healthy epidermis. Keratinocytes can be activated, for example, by binding ofthe appropriate ligands to the epidermal growth factor receptor (EGFR). We have analyzed the effects of EGFR activation on keratin gene transcription by transfecting DNAs containing keratin promoters linked to a reporter gene into primary cultures of human epidermal keratinocytes in the presence or absence of EGF or transforming growth factor a (TGFa), two growth factors that activate EGFR. The activation of EGFR had no effect on the promoters of simple epithelial, basal-layer-specific, or differentiation-specific keratins. In contrast, the expression of K6 and K16 was strongly and specifically induced. A 20-bp DNA segment of the K16 gene promoter conveyed the EGF regulation, functioned in a heterologous construct, and therefore constituted an EGF-responsive element. A nuclear protein specifically bound to this element and to the analogous sequence of the K6 promoter. Thus, EGF specifically induces K6 and K16, markers of activated keratinocytes, via nuclear proteins that bind to EGF-responsive elements in the promoters of these keratin genes.