Local Glucocorticoid Activation by 11ß-Hydroxysteroid Dehydrogenase 1 in Keratinocytes: The Role in Hapten-Induced Dermatitis.

Over the past decade, extra-adrenal cortisol production was reported in various tissues. The enzyme that catalyzes the conversion of hormonally inactive cortisone into active cortisol in cells is 11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1). We recently reported that 11ß-HSD1 is also expressed in keratinocytes and regulates inflammation and keratinocyte proliferation. To investigate the function of 11ß-HSD1 in keratinocytes during inflammation in vivo, we created keratinocyte-specific 11ß-HSD1 knockout (K5-Hsd11b1-KO) mice and analyzed the inflammatory response in models of hapten-induced contact irritant dermatitis. K5-Hsd11b1-KO mice showed enhanced ear swelling in low-dose oxazolone-, 2,4,6-trinitro-1-chlorobenzene (TNCB)-, and 2,4-dinitrofluorobenzene-induced irritant dermatitis associated with increased inflammatory cell infiltration. Topical application of corticosterone dose dependently suppressed TNCB-induced ear swelling and cytokine expression. Similarly in mouse keratinocytes in vitro, corticosterone dose dependently suppressed 2,4,6-trinitrobenzenesulfonic acid-induced IL-1α and IL-1ß expression. The effect of 11-dehydrocorticosterone was attenuated in TNCB-induced irritant dermatitis in K5-Hsd11b1-KO mice compared with wild-type mice. In human samples, 11ß-HSD1 expression was decreased in epidermis of psoriasis vulgaris compared with healthy skin. Taken together, these data suggest that corticosterone activation by 11ß-HSD1 in keratinocytes suppresses hapten-induced irritant dermatitis through suppression of expression of cytokines, such as IL-1α and IL-1ß, in keratinocytes.

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.

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.

Topical cholesterol treatment ameliorates hapten-evoked cutaneous hypersensitivity by sustaining expression of 11ß-HSD1 in epidermis.

Changes in the stratum corneum extracellular matrix impair epidermal barrier function and may cause dermatoses. The aim of this study was to examine the effect of exogenous cholesterol application on skin barrier function and cutaneous inflammation. Skin barrier-disrupted or hapten-stimulated mice were treated with topical cholesterol. The effect of topical cholesterol application on an oxazolone (OXA)-induced hypersensitivity reaction was evaluated. Topical application of cholesterol efficiently decreased transepidermal water loss in areas of barrier-disrupted skin and ameliorated OXA-induced cutaneous hypersensitivity. These favourable effects may have resulted from sustained expression of 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) in the cholesterol-treated skin. As 11ß-HSD1 is known to produce active cortisol, topical cholesterol may attenuate contact hypersensitivity by normalizing secretion of hormonally active cortisol from the skin.

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.

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.

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.

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.

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.

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.

Beneficial effects of foot care nursing for people with diabetes mellitus: an uncontrolled before and after intervention study.

AIM: The aim of this study was to assess the effectiveness of a preventative foot care nursing programme for diabetic patients. BACKGROUND: Foot complications are common in diabetic patients and prevention of such complications requires foot care. However, there is little information on the effectiveness of foot care nursing on the incidence and recurrence of diabetic foot. METHODS: We developed a diabetic foot care programme based on the International Working Group on the Diabetic Foot. We studied 88 patients who attended our foot care programme for 2 years, and collected data from April 2005 to March 2009. Patients were divided into four groups according to the risk classification, and received foot care. We evaluated the incidence of foot ulceration or recurrence and non-ulcerated foot condition. Characteristics of the patients were analysed using the paired t-test and McNemar's test, and changes in severity of tinea pedis and grade of callus were analysed using Wilcoxon's signed rank sum test. RESULTS: The programme reduced the severity score of tinea pedis (P < 0·001) and improved callus grade (P < 0·001). All these were evaluated by Wilcoxon's signed rank sum test. None of the patients of risk-group-3 (history of foot ulceration) showed recurrence of callus-related foot ulcers. Six high-risk patients developed foot ulceration during the programme because of minor injury, but the ulcers healed without development of gangrene. CONCLUSION: A nurse-based foot care programme is effective in preventing diabetic foot in diabetic patients.

Two cases of refractory discoid lupus erythematosus successfully treated with topical tocoretinate.

Discoid lupus erythematosus (DLE), the most common lupus erythematosus (LE)-specific chronic manifestation of the skin, is often resistant to therapy. Atrophy, scarring, and pigmentation are often observed. In this study, we report two cases of DLE that were successfully treated with tocoretinate, a compound containing a mixture of retinoic acid and tocopherol. Atrophy and pigmentation improved in both cases. The mechanism of action of tocoretinate is discussed.

Tumor necrosis factor-alpha processing inhibitor-1 inhibits skin fibrosis in a bleomycin-induced murine model of scleroderma.

Elevated serum concentration of soluble tumor necrosis factor receptor p55 (sTNFRp55) is known to correlate with the severity of systemic sclerosis (SSc). However, it has not been verified whether this increase contributes to the pathogenesis of SSc. In this study, we found that sTNFRp55 also is increased in the bleomycin (BLM)-induced murine model of SSc. Therefore, we examined the effect of tumor necrosis factor-alpha processing inhibitor-1 (TAPI-1), the inhibitor of TNFRp55 sheddase, in this model. TAPI-1 was administered weekly to mice with skin fibrosis induced by daily BLM injections. TAPI-1 significantly suppressed BLM-induced skin thickness and the number of myofibroblasts. It also inhibited the increase of serum sTNFRp55 after 3 weeks of BLM injections. The mRNA expression of collagen type I alpha1, transforming growth factor-beta1 and alpha smooth muscle actin were decreased by TAPI-1 administration. Taken together, these findings indicate that targeting the TNFalpha converting enzyme might be a new type of therapy for patients with SSc.

Impact of sedative and non-sedative antihistamines on the impaired productivity and quality of life in patients with pruritic skin diseases.

BACKGROUND: The impairment that pruritic skin diseases have on patient productivity at work, in the classroom, and in daily activities is substantial and needs to be characterized. The objective of this study was to determine how pruritic skin diseases impact patient productivity and quality of life (QOL), in order to improve the measurement of these endpoints to allow the influence of treatment options including sedative and non-sedative antihistamines to be analyzed. METHODS: The impact of pruritic skin diseases and the effect of antihistamine therapy on work, classroom, and daily productivity were evaluated using the Work Productivity Assessment Index-Allergy Specific Questionnaire. The intensity of itch and patient QOL were assessed using a visual analogue scale and Skindex-16, respectively. RESULTS: Pruritic skin diseases resulted in significant impairment of work, classroom, and daily productivity. The severity of overall work impairment in atopic dermatitis (AD), urticaria, and prurigo was higher than for other diseases analyzed. However, classroom activity was more adversely affected in patients with urticaria relative to other diseases. All pruritic diseases in this study negatively impacted daily activity to a similar degree. Impaired productivity was significantly improved in patients taking non-sedative antihistamines for 1 month, and the improvements correlated with the alleviation of itch and improved QOL. CONCLUSIONS: These results indicate that pruritic skin diseases reduce patient productivity at work, in the classroom, and during daily activities, and that non-sedative antihistamines may offer an advantage over sedative antihistamines for alleviating certain negative consequences of these skin diseases.

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.

Attenuated Activation of Homeostatic Glucocorticoid in Keratinocytes Induces Alloknesis via Aberrant Artemin Production.

Intense chronic itch significantly reduces quality of life for atopic dermatitis patients, impairing daily activity. Although abnormal itch sensation can be induced by innocuous stimuli, known as alloknesis, the mechanisms driving this process remain obscure. Psychological and environmental stimuli are known to aggravate atopic dermatitis symptoms. Recently, the enzyme 11ß-hydroxysteroid dehydrogenase-1 (HSD11ß1), which is expressed in keratinocytes, has been implicated in maintaining homeostasis against environmental stimuli by activating endogenous glucocorticoids. To investigate the role of HSD11ß1 in keratinocytes, we generated keratinocyte-specific Hsd11b1-knockout (Hsd11b1KC-/-) mice and analyzed skin phenotype. Hsd11b1KC-/- mice exhibited abnormal cutaneous innervation and skin sensitivity, including light mechanical stimulus-evoked itch (i.e., alloknesis). Attenuated endogenous glucocorticoid activation induced by aberrant artemin production in keratinocytes was involved in alloknesis in Hsd11b1KC-/- mice. Finally, we observed a significant negative correlation between expression of HSD11ß1 and artemin in human skin with and without AD. These results suggest that endogenous glucocorticoids that maintain skin homeostasis in the epidermis affect both skin innervation and cutaneous sensation. Modulation of HSD11ß1 activation could be a therapeutic target for sensitive or itchy skin.

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.