Osteoclasts Modulate Bone Erosion in Cholesteatoma via RANKL Signaling.

Cholesteatoma starts as a retraction of the tympanic membrane and expands into the middle ear, eroding the surrounding bone and causing hearing loss and other serious complications such as brain abscess and meningitis. Currently, the only effective treatment is complete surgical removal, but the recurrence rate is relatively high. In rheumatoid arthritis (RA), osteoclasts are known to be responsible for bone erosion and undergo differentiation and activation by receptor activator of NF-κB ligand (RANKL), which is secreted by synovial fibroblasts, T cells, and B cells. On the other hand, the mechanism of bone erosion in cholesteatoma is still controversial. In this study, we found that a significantly larger number of osteoclasts were observed on the eroded bone adjacent to cholesteatomas than in unaffected areas, and that fibroblasts in the cholesteatoma perimatrix expressed RANKL. We also investigated upstream transcription factors of RANKL using RNA sequencing results obtained via Ingenuity Pathways Analysis, a tool that identifies relevant targets in molecular biology systems. The concentrations of four candidate factors, namely interleukin-1ß, interleukin-6, tumor necrosis factor α, and prostaglandin E2, were increased in cholesteatomas compared with normal skin. Furthermore, interleukin-1ß was expressed in infiltrating inflammatory cells in the cholesteatoma perimatrix. This is the first report demonstrating that a larger-than-normal number of osteoclasts are present in cholesteatoma, and that the disease involves upregulation of factors related to osteoclast activation. Our study elucidates the molecular basis underlying bone erosion in cholesteatoma.

Local cortisol activation is involved in EGF-induced immunosuppression.

The major effects of the epidermal growth factor receptor (EGFR) signalling pathway on keratinocytes are cell proliferation, cell differentiation, and wound healing. In addition to these effects, an immunosuppressive effect of EGFR signalling has been reported. However, the precise mechanism of immunosuppression by EGFR signalling is not well understood. In this study, we clarified the involvement of increased local cortisol activation in EGFR signalling-induced immunosuppression in keratinocytes. EGF treatment up-regulated the expression of 11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1) and supernatant cortisol levels in a dose-dependent manner in keratinocytes. 11ß-HSD1 is an enzyme that catalyses the conversion of cellular hormonally inactive cortisone into active cortisol. qRT-PCR and ELISA assays indicated that EGF significantly decreased tumour necrosis factor α (TNF- α)-induced interleukin-6 (IL-6) expression in keratinocytes. Similarly, 11ß-HSD1 overexpression significantly decreased TNF-α-induced IL-6 expression. We evaluated the role of 11ß-HSD1 in immunosuppression through EGFR signalling. Blockade of 11ß-HSD1 via 11ß-HSD1 inhibitor reversed both the expression and production of TNF-α-induced IL-6, which was decreased by EGF in keratinocytes. Therefore, increased local cortisol activation by 11ß-HSD1 is involved in EGFR signalling-induced immunosuppression in keratinocytes. Finally, we evaluated whether EGFR inhibition by cetuximab affects the expression of 11ß-HSD1. We found that 0.1 µg cetuximab decreased 11ß-HSD1 transcript levels in keratinocytes. The changes in 11ß-HSD1 were more apparent in TNF-α-treated cells. As 11ß-HSD1 expression in keratinocytes is associated with inflammation and cell proliferation, this mechanism may be associated with adverse skin reactions observed in patients treated with EGFR inhibitors.

Local cortisol/corticosterone activation in skin physiology and pathology.

Cortisol and corticosterone are the endogenous glucocorticoids (GCs) in humans and rodents, respectively. Systemic GC is released through the hypothalamic-pituitary-adrenal (HPA) axis in response to various stressors. Over the last decade, extra-adrenal production/activation of cortisol/corticosterone has been reported in many tissues. The enzyme that catalyzes the conversion of hormonally inactive cortisone/11-dehydrocorticosterone (11-DHC) into active cortisol/corticosterone in cells is 11ß-hydroxysteroid dehydrogenase (11ß-HSD). The 11ß-HSD1 isoform is predominantly a reductase, which catalyzes nicotinamide adenine dinucleotide phosphate hydrogen-dependent conversion of cortisone/11-DHC to cortisol/corticosterone, and is widely expressed and present at the highest levels in the liver, lungs, adipose tissues, ovaries, and central nervous system. The 11ß-HSD2 isoform, which catalyzes nicotinamide adenine dinucleotide+-dependent inactivation of cortisol/corticosterone to cortisone/11-DHC, is highly expressed in distal nephrons, the colon, sweat glands, and the placenta. In healthy skin, 11ß-HSD1 is expressed in the epidermis and in dermal fibroblasts. On the other hand, 11ß-HSD2 is expressed in sweat glands but not in the epidermis. The role of 11ß-HSD in skin physiology and pathology has been reported recently. In this review, we summarize the recently reported role of 11ß-HSD in the skin, focusing on its function in cell proliferation, wound healing, inflammation, and aging.

Th2 cytokines enhance TrkA expression, upregulate proliferation, and downregulate differentiation of keratinocytes.

BACKGROUND: Nerve growth factor (NGF), a neurotrophin that plays a critical role in developmental neurobiology, is released by proliferating keratinocytes and induces proliferation. OBJECTIVE: The aim of this study was to investigate the role of tyrosine kinase receptor A (TrkA), a high-affinity receptor of NGF, in human keratinocytes. METHODS: Expression of TrkA and NGF in skin diseases was investigated by immunohistochemistry. Expression of TrkA in cells was examined by Western blotting and RT-PCR. Cell proliferation was assessed by BrdU assay. RESULTS: We first determined the expression of TrkA and NGF in skin samples from patients with atopic dermatitis, prurigo nodularis, psoriasis vulgaris, and seborrheic keratosis. TrkA was only expressed in proliferating basal cells, and its expression was enhanced in atopic dermatitis samples. NGF expression was enhanced in atopic dermatitis and prurigo nodularis samples and in some samples from seborrheic keratosis patients. Investigation of the role of TrkA in vitro using normal human epidermal keratinocytes (NHEK) revealed that TrkA was significantly enhanced by the T helper type 2 (Th2) cytokines interleukin (IL)-4 and IL-13 but not by other inflammatory cytokines, such as IL-1ß, tumor necrosis factor α, interferon γ, or epidermal growth factor. On the other hand, expression of NGF was not altered by Th2 cytokines. Notably, inhibition of TrkA significantly reversed the effects of IL-4 on proliferation and differentiation. Furthermore, overexpression of TrkA enhanced proliferation of NHEK. These results indicate that IL-4-induced TrkA expression in keratinocytes modulates proliferation and differentiation of these cells. CONCLUSION: Increased TrkA expression in keratinocytes in atopic dermatitis may contribute to the observed epidermal hyperproliferation in these patients.

Oligosaccharide modification by N-acetylglucosaminyltransferase-V in macrophages are involved in pathogenesis of bleomycin-induced scleroderma.

Oligosaccharide modification by N-acetylglucosaminyltransferase-V (GnT-V), which catalyses the formation of ß1,6 GlcNAc (N-acetylglucosamine) branches on N-glycans, is associated with various pathologies, such as cancer metastasis, multiple sclerosis and liver fibrosis. In this study, we demonstrated the involvement of GnT-V in the pathophysiology of scleroderma. High expression of GnT-V was observed in infiltrating cells in skin section samples from systemic and localized patients with scleroderma. Most of the infiltrating cells were T cells and macrophages, most of which were CD163(+) M2 macrophages. To determine the role of GnT-V in scleroderma, we next investigated skin sclerosis in GnT-V knockout (MGAT5(-/-) ) mice. Expression of GnT-V was also elevated in bleomycin (BLM)-injected sclerotic skin, and MGAT5(-/-) mice were resistant to BLM-induced skin sclerosis with reduced collagen type 1 α1 content, suggesting the biological significance of GnT-V in skin sclerosis. Furthermore, the number of CD163(+) M2 macrophages and CD3-positive T cells in BLM-induced skin sclerosis was significantly fewer in MGAT5(-/-) mice. In bone marrow-derived macrophages (BMDMs), IL-4-induced expressions of Fizz1 and Ym1 were significantly reduced in MGAT5(-/-) mice-derived BMDMs. Taken together, these results suggest the induction of GnT-V in skin sclerosis progression is possibly dependent on increased numbers of M2 macrophages in the skin, which are important for tissue fibrosis and remodelling.

T helper 2 polarization in senile erythroderma with elevated levels of TARC and IgE.

BACKGROUND: Some cases of senile erythroderma tend to be diagnosed as senile atopic dermatitis (AD) based on elevated levels of immunoglobulin E (IgE) and thymus and activation-regulated chemokine (TARC). However, there are few studies that describe the detailed characteristics of senile erythroderma and senile AD. OBJECTIVE: We examined the association of erythroderma with AD. METHODS: In this retrospective observational study, 68 patients over 65 years of age who presented with erythroderma at Osaka University Hospital were enrolled. Patient data were collected through medical records and descriptive statistics. RESULTS: 47% of the patients were classified as having idiopathic erythroderma and 53% as having secondary erythroderma. In both idiopathic and secondary senile erythroderma patients, serum IgE and TARC levels were elevated. 84% of idiopathic erythroderma patients fulfilled the Japanese Dermatological Associations criteria for AD; however, only 4 patients were finally definitely diagnosed with senile AD. CONCLUSION: Many senile erythroderma patients showed AD-like symptoms due to T helper 2 polarization.

IFN-γ or IFN-α ameliorates chronic proliferative dermatitis by inducing expression of linear ubiquitin chain assembly complex.

The linear ubiquitin chain assembly complex (LUBAC) ubiquitin ligase complex, composed of HOIL-1L-interacting protein (HOIP), heme-oxidized IRP2 ubiquitin ligase-1L (HOIL-1L), and SHANK-associated RH domain protein, specifically generates linear polyubiquitin chains and is involved in NF-κB activation. Lack of SHANK-associated RH domain protein, which drastically reduces the amount of HOIP and HOIL-1L, causes chronic proliferative dermatitis (cpdm) in mice. Impaired NF-κB activation and augmented apoptosis have been implicated in the pathogenesis of cpdm in mice. In this study, we found that IFN-γ increased the amount of LUBAC by inducing HOIP and HOIL-1L mRNA transcription and enhanced the signal-induced NF-κB activation in embryonic fibroblasts, keratinocytes, and bone marrow-derived macrophages from wild-type and/or cpdm mice; however, IFN-γ failed to augment NF-κB activation in mouse embryonic fibroblasts lacking linear polyubiquitination activity of LUBAC. Moreover, s.c. injection of IFN-γ for 3 wk into the skin of cpdm mice increased the amount of HOIP, suppressed apoptosis, and ameliorated the dermatitis. Inhibition of keratinocyte apoptosis by IFN-γ injection suppressed neutrophil, macrophage, and mast cell infiltration and the amount of TNF-α in the skin of cpdm mice. Similarly, IFN-α also enhanced the amount of HOIP as well as NF-κB activation, inhibited apoptosis, and ameliorated cpdm dermatitis. These results indicate that the IFNs enhance NF-κB activation and ameliorate cpdm dermatitis by augmenting expression of HOIP and HOIL-1L and linear polyubiquitination activity of LUBAC.

11ß-hydroxysteroid dehydrogenase 1 specific inhibitor increased dermal collagen content and promotes fibroblast proliferation.

Glucocorticoids (GCs) are one of the most effective anti-inflammatory drugs for treating acute and chronic inflammatory diseases. However, several studies have shown that GCs alter collagen metabolism in the skin and induce skin atrophy. Cortisol is the endogenous GC that is released in response to various stressors. Over the last decade, extraadrenal cortisol production in various tissues has been reported. Skin also synthesizes cortisol through a de novo pathway and through an activating enzyme. 11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1) is the enzyme that catalyzes the conversion of hormonally inactive cortisone to active cortisol in cells. We previously found that 11ß-HSD1 negatively regulates proliferation of keratinocytes. To determine the function of 11ß-HSD1 in dermal fibroblasts and collagen metabolism, the effect of a selective 11ß-HSD1 inhibitor was studied in mouse tissues and dermal fibroblasts. The expression of 11ß-HSD1 increased with age in mouse skin. Subcutaneous injection of a selective 11ß-HSD1 inhibitor increased dermal thickness and collagen content in the mouse skin. In vitro, proliferation of dermal fibroblasts derived from 11ß-HSD1 null mice (Hsd11b1(-/-) mice) was significantly increased compared with fibroblasts from wild-type mice. However, in vivo, dermal thickness of Hsd11b1(-/-) mice was not altered in 3-month-old and 1-year-old mouse skin compared with wild-type mouse skin. These in vivo findings suggest the presence of compensatory mechanisms in Hsd11b1(-/-) mice. Our findings suggest that 11ß-HSD1 inhibition may reverse the decreased collagen content observed in intrinsically and extrinsically aged skin and in skin atrophy that is induced by GC treatment.

11ß-Hydroxysteroid dehydrogenase 1 contributes to the pro-inflammatory response of keratinocytes.

The endogenous glucocorticoid, cortisol, is released from the adrenal gland in response to various stress stimuli. Extra-adrenal cortisol production has recently been reported to occur in various tissues. Skin is known to synthesize cortisol through a de novo pathway and through an activating enzyme. The enzyme that catalyzes the intracellular conversion of hormonally-inactive cortisone into active cortisol is 11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1). We recently reported that 11ß-HSD1 is expressed in normal human epidermal keratinocytes (NHEKs) and negatively regulates proliferation of NHEKs. In this study, we investigated the role of 11ß-HSD1 in skin inflammation. Expression of 11ß-HSD1 was induced by UV-B irradiation and in response to the pro-inflammatory cytokines, IL-1ß and TNFα. Increased cortisol concentrations in culture media also increased in response to these stimuli. To investigate the function of increased 11ß-HSD1 in response to pro-inflammatory cytokines, we knocked down 11ß-HSD1 by transfecting siRNA. Production of IL-6 and IL-8 in response to IL-1ß or TNFα stimulation was attenuated in NHEKs transfected with si11ß-HSD1 compared with control cells. In addition, IL-1ß-induced IL-6 production was enhanced in cultures containing 1 × 10(-13) M cortisol, whereas 1 × 10(-5) M cortisol attenuated production of IL-6. Thus, cortisol showed immunostimulatory and immunosuppressive activities depending on its concentration. Our results indicate that 11ß-HSD1 expression is increased by various stimuli. Thus, regulation of cytosolic cortisol concentrations by 11ß-HSD1 appears to modulate expression of inflammatory cytokines in NHEKs.

Expression profiles of cortisol-inactivating enzyme, 11ß-hydroxysteroid dehydrogenase-2, in human epidermal tumors and its role in keratinocyte proliferation.

The enzyme 11ß-hydroxysteroid dehydrogenase (11ß-HSD) catalyzes the interconversion between hormonally active cortisol and inactive cortisone within cells. There are two isozymes: 11ß-HSD1 activates cortisol from cortisone and 11ß-HSD2 inactivates cortisol to cortisone. 11ß-HSD1 was recently discovered in skin, and we subsequently found that the enzyme negatively regulates keratinocyte proliferation. We verified 11ß-HSD1 and 11ß-HSD2 expression in benign and malignant skin tumors and investigated the role of 11ß-HSD in skin tumor pathogenesis. Randomly selected formalin-fixed sections of skin lesions of seborrheic keratosis (SK), squamous cell carcinoma (SCC), and basal cell carcinoma (BCC) were stained with 11ß-HSD1 and 11ß-HSD2 antibodies, and 11ß-HSD expression was also evaluated in murine epidermis in which hyperproliferation was induced by 12-O-tetradecanoylphorbol-13 acetate (TPA). We observed that 11ß-HSD1 expression was decreased in all SK, SCC, and BCC lesions compared with unaffected skin. Conversely, 11ß-HSD2 expression was increased in SK and BCC but not in SCC. Overexpression of 11ß-HSD2 in keratinocytes increased cell proliferation. In the murine model, 11ß-HSD1 expression was decreased in TPA-treated hyperproliferative skin. Our findings suggest that 11ß-HSD1 expression is decreased in keratinocyte proliferative conditions, and 11ß-HSD2 expression is increased in basal cell proliferating conditions, such as BCC and SK. Assessing 11ß-HSD1 and 11ß-HSD2 expression could be a useful tool for diagnosing and characterizing skin tumors.

Generalized lichen nitidus in Russell-Silver syndrome.

Generalized lichen nitidus is a rare disease, and there are only a few reports associating it with a genetic disorder. Here we report a case of generalized lichen nitidus in Russell-Silver syndrome.

Physiological roles of N-acetylglucosaminyltransferase V(GnT-V) in mice.

Oligosaccharide modification by N-acetylglucosaminyltransferase- V (GnT-V), a glycosyltransferase encoded by the Mgat5 gene that catalyzes the formation of ß1,6GlcNAc (N-acetylglucosamine) branches on N-glycans, is thought to be associated with cancer growth and metastasis. Overexpression of GnT-V in cancer cells enhances the signaling of growth factors such as epidermal growth factor by increasing galectin-3 binding to polylactosamine structures on receptor N-glycans. In contrast, GnT-V deficient mice are born healthy and lack ß1,6GlcNAc branches on N-glycans, but develop immunological disorders due to T-cell dysfunction at 12-20 months of age. We have developed Mgat5 transgenic (Tg) mice (GnT-V Tg mice) using a ß-actin promoter and found characteristic phenotypes in skin, liver, and T cells in the mice. Although the GnT-V Tg mice do not develop spontaneous cancers in any organs, there are differences in the response to external stimuli between wild-type and GnT-V Tg mice. These changes are similar to those seen in cancer progression but are unexpected in some aspects. In this review, we summarize what is known about GnT-V functions in skin and liver cells as a means to understand the physiological roles of GnT-V in mice.

Periostin facilitates skin sclerosis via PI3K/Akt dependent mechanism in a mouse model of scleroderma.

OBJECTIVE: Periostin, a novel matricellular protein, is recently reported to play a crucial role in tissue remodeling and is highly expressed under fibrotic conditions. This study was undertaken to assess the role of periostin in scleroderma. METHODS: Using skin from patients and healthy donors, the expression of periostin was assessed by immunohistochemistry and immunoblotting analyses. Furthermore, we investigated periostin(-/-) (PN(-/-)) and wild-type (WT) mice to elucidate the role of periostin in scleroderma. To induce murine cutaneous sclerosis, mice were subcutaneously injected with bleomycin, while untreated control groups were injected with phosphate-buffered saline. Bleomycin-induced fibrotic changes were compared in PN(-/-) and WT mice by histological analysis as well as by measurements of profibrotic cytokine and extracellular matrix protein expression levels in vivo and in vitro. To determine the downstream pathway involved in periostin signaling, receptor neutralizing antibody and signal transduction inhibitors were used in vitro. RESULTS: Elevated expression of periostin was observed in the lesional skin of patients with scleroderma compared with healthy donors. Although WT mice showed marked cutaneous sclerosis with increased expression of periostin and increased numbers of myofibroblasts after bleomycin treatment, PN(-/-) mice showed resistance to these changes. In vitro, dermal fibroblasts from PN(-/-) mice showed reduced transcript expression of alpha smooth actin and procollagen type-I alpha 1 (Col1α1) induced by transforming growth factor beta 1 (TGFß1). Furthermore, recombinant mouse periostin directly induced Col1α1 expression in vitro, and this effect was inhibited by blocking the αv integrin-mediated PI3K/Akt signaling either with anti-αv functional blocking antibody or with the PI3K/Akt kinase inhibitor LY294002. CONCLUSION: Periostin plays an essential role in the pathogenesis of Bleomycin-induced scleroderma in mice. Periostin may represent a potential therapeutic target for human scleroderma.

Artemin causes hypersensitivity to warm sensation, mimicking warmth-provoked pruritus in atopic dermatitis.

BACKGROUND: Itch impairs the quality of life for many patients with dermatoses, especially atopic dermatitis (AD), and is frequently induced by a warm environment. OBJECTIVE: To determine the mechanism underlying itch induction by warmth, we focused on artemin, a member of glial cell line-derived neurotrophic factors (GDNFs). METHODS: A gene array assay revealed that artemin was expressed in substance P-treated dermal fibroblasts. The expression of artemin in healthy and AD-lesional skin was evaluated with immunohistochemistry and in situ hybridization. The impact of fibroblast-derived artemin on the proliferation and morphology of neural cell was investigated in vitro. To confirm the involvement of artemin in skin sensibility, wild-type and GDNF family receptor α3 knockout mice were employed for sensory examination. RESULTS: Artemin-expressing fibroblasts accumulated in skin lesions of patients with AD. Artemin induced cell proliferation of a neuroblastoma cell line in vitro, and intradermal injection of artemin in mice resulted in peripheral nerve sprouting and thermal hyperalgesia. Artemin-treated mice demonstrated scratching behavior in a warm environment, but mice deficient for GDNF family receptor α3, a potent artemin receptor, did not show this behavior. Furthermore, the escaping response to heat stimulus was attenuated in GDNF family receptor α3 knockout mice, suggesting that artemin may contribute to sensitivity to heat. CONCLUSION: These data suggest that dermal fibroblasts secrete artemin in response to substance P, leading to abnormal peripheral innvervation and thermal hyperalgesia. We hypothesize that artemin lowers the threshold of temperature-dependent itch sensation and might therefore be a novel therapeutic target for treating pruritic skin disorders, including AD.

Upregulation of N-acetylglucosaminyltransferase-V by heparin-binding EGF-like growth factor induces keratinocyte proliferation and epidermal hyperplasia.

Oligosaccharide modification by N-acetylglucosaminyltransferase-V (GnT-V), a glycosyltransferase encoded by the Mgat5 gene that catalyses the formation of ß1,6 GlcNAc (N-acetylglucosamine) branches on N-glycans, is thought to be associated with cancer growth and metastasis. Overexpression of GnT-V in cancer cells enhances the signalling of growth factors such as epidermal growth factor (EGF) and transforming growth factor-ß by increasing galectin-3 binding to polylactosamine structures on receptor N-glycans. We previously demonstrated that transgenic mice overexpressing GnT-V fail to develop spontaneous tumors in any organs, but phenotypes reminiscent of epithelial-to-mesenchymal transition were observed in their skin. However, the biological function of GnT-V in normal skin remained unknown. In this study, we examined the role of GnT-V in keratinocyte proliferation using GnT-V-deficient mice. Proliferation of human keratinocytes was suppressed by treatment with GnT-V siRNA. Mgat5(-/-) mouse keratinocytes also showed impaired cell proliferation through the reduction in EGF receptors on the cell surface. Although the skin of Mgat5(-/-) mice appeared normal, epidermal hyperplasia and proliferation of keratinocytes induced by the phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) were downregulated in these mutants. Moreover, a dramatic increase in GnT-V expression was observed by treatment with TPA or heparin-binding EGF-like growth factor (HB-EGF) in normal human epidermal keratinocytes. This increase was inhibited by an EGF receptor inhibitor. These results indicate that a high expression of GnT-V in keratinocytes contributes to HB-EGF-mediated epidermal hyperproliferation by inhibiting endocytosis of EGF receptors bearing ß1,6 GlcNAc on their N-glycans. Our findings demonstrate a novel role for GnT-V in epidermal homoeostasis, particularly in hyperproliferative conditions.

Fucosylation is a promising target for cancer diagnosis and therapy.

Oligosaccharides, sequences of carbohydrates conjugated to proteins and lipids, are arguably the most abundant and structurally diverse class of molecules. Fucosylation is one of the most important oligosaccharide modifications involved in cancer and inflammation. Recent advances in glycomics have identified several types of glyco-biomarkers containing fucosylation that are linked to certain types of cancer. Fucosylated alpha-fetoprotein (AFP) is widely used in the diagnosis of hepatocellular carcinoma because it is more specific than alpha-fetoprotein. High levels of fucosylated haptoglobin have also been found in sera of patients with various carcinomas. We have recently established a simple lectin-antibody ELISA to measure fucosylated haptoglobin and to investigate its clinical use. Cellular fucosylation is dependent upon fucosyltransferase activity and the level of its donor substrate, guanosine diphosphate (GDP)-fucose. GDP-mannose-4,6-dehydratase (GMDS) is a key enzyme involved in the synthesis of GDP-fucose. Mutations of GMDS found in colon cancer cells induced a malignant phenotype, leading to rapid growth in athymic mice resistant to natural killer cells. This review describes the role of fucosylated haptoglobin as a cancer biomarker, and discusses the possible biological role of fucosylation in cancer development.

Blockade of interleukin-6 receptor alleviates disease in mouse model of scleroderma.

Activation of fibroblasts by interleukin-6 (IL-6) is implicated in the pathogenesis of scleroderma, suggesting that the inhibition of fibroblast activation may be a promising scleroderma treatment. In this study, we used an IL-6 blocking antibody (Ab) and Il-6 knockout (Il-6KO) mice to examine the role of IL-6 in the bleomycin (BLM)-induced mouse model of scleroderma. BLM was administered to C57BL/6 and Il-6KO mice to induce dermal sclerosis. BLM-treated and control phosphate-buffered saline-treated mice were treated with anti-mouse IL-6 receptor monoclonal Ab (MR16-1). Disease severity was evaluated by measuring dermal thickness and skin hardness, by counting the numbers of α-smooth muscle actin-positive cells and mast cells, and by examining the cutaneous draining lymph nodes. C57BL/6 mice with BLM induced scleroderma had elevated serum IL-6 levels and more severe dermal sclerosis than Il-6KO mice. Weekly administration of MR16-1, but not control Ab, prevented and improved dermal sclerosis, and also attenuated swelling of the draining lymph nodes. MR16-1 suppressed α-smooth muscle actin induction in IL-6-stimulated Il-6KO fibroblasts. Our results indicate that IL-6 contributes to BLM induced dermal sclerosis and that IL-6 receptor-specific monoclonal Ab may improve the symptoms of scleroderma by suppressing fibroblast activation.

11ß-Hydroxysteroid dehydrogenase-1 is a novel regulator of skin homeostasis and a candidate target for promoting tissue repair.

11ß-Hydroxysteroid dehydrogenase 1 (11ß-HSD1) catalyzes the interconversion of cortisone and cortisol within the endoplasmic reticulum. 11ß-HSD1 is expressed widely, most notably in the liver, adipose tissue, and central nervous system. It has been studied intensely over the last 10 years because its activity is reported to be increased in visceral adipose tissue of obese people. Epidermal keratinocytes and dermal fibroblasts also express 11ß-HSD1. However, the function of the enzymatic activity 11ß-HSD1 in skin is not known. We found that 11ß-HSD1 was expressed in human and murine epidermis, and this expression increased as keratinocytes differentiate. The expression of 11ß-HSD1 by normal human epidermal keratinocytes (NHEKs) was increased by starvation or calcium-induced differentiation in vitro. A selective inhibitor of 11ß-HSD1 promoted proliferation of NHEKs and normal human dermal fibroblasts, but did not alter the differentiation of NHEKs. Topical application of selective 11ß-HSD1 inhibitor to the dorsal skin of hairless mice caused proliferation of keratinocytes. Taken together, these data suggest that 11ß-HSD1 is involved in tissue remodeling of the skin. This hypothesis was further supported by the observation that topical application of the selective 11ß-HSD1 inhibitor enhanced cutaneous wound healing in C57BL/6 mice and ob/ob mice. Collectively, we conclude that 11ß-HSD1 is negatively regulating the proliferation of keratinocytes and fibroblasts, and cutaneous wound healing. Hence, 11ß-HSD1 might maintain skin homeostasis by regulating the proliferation of keratinocytes and dermal fibroblasts. Thus 11ß-HSD1 is a novel candidate target for the design of skin disease treatments.

Enhanced epithelial-mesenchymal transition-like phenotype in N-acetylglucosaminyltransferase V transgenic mouse skin promotes wound healing.

N-Acetylglucosaminyltransferase V (GnT-V) catalyzes the ß1,6 branching of N-acetylglucosamine on N-glycans. GnT-V expression is elevated during malignant transformation in various types of cancer. However, the mechanism by which GnT-V promotes cancer progression is unclear. To characterize the biological significance of GnT-V, we established GnT-V transgenic (Tg) mice, in which GnT-V is regulated by a ß-actin promoter. No spontaneous cancer was detected in any organs of the GnT-V Tg mice. However, GnT-V expression was up-regulated in GnT-V Tg mouse skin, and cultured keratinocytes derived from these mice showed enhanced migration, which was associated with changes in E-cadherin localization and epithelial-mesenchymal transition (EMT). Further, EMT-associated factors snail, twist, and N-cadherin were up-regulated, and cutaneous wound healing was accelerated in vivo. We further investigated the detailed mechanisms of EMT by assessing EGF signaling and found up-regulated EGF receptor signaling in GnT-V Tg mouse keratinocytes. These findings indicate that GnT-V overexpression promotes EMT and keratinocyte migration in part through enhanced EGF receptor signaling.