Improvement of androgenic alopecia by extracellular vesicles secreted from hyaluronic acid-stimulated induced mesenchymal stem cells.

BACKGROUND: Androgenetic alopecia (AGA) is a common form of hair loss. Androgens, such as testosterone and dihydrotestosterone, are the main causes of AGA. Extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) can reduce AGA. However, preparing therapeutic doses of MSCs for clinical use is challenging. Induced pluripotent stem cell-derived MSCs (iMSCs) are homogenous and easily expandable, enabling scalable production of EVs. Hyaluronic acid (HA) can exert various functions including free radical scavenging, immune regulation, and cell migration. Herein, we examined whether hyaluronic acid (HA) stimulation of iMSCs could produce EVs with enhanced therapeutic outcomes for AGA. METHODS: EVs were collected from iMSCs primed with HA (HA-iMSC-EVs) or without HA (iMSC-EVs). The characteristics of EVs were examined using dynamic light scattering, cryo-transmission electron microscopy, immunoblotting, flow cytometry, and proteomic analysis. In vitro, we compared the potential of EVs in stimulating the survival of hair follicle dermal papilla cells undergoing testosterone-mediated AGA. Additionally, the expression of androgen receptor (AR) and relevant growth factors as well as key proteins of Wnt/ß-catenin signaling pathway (ß-catenin and phosphorylated GSK3ß) was analyzed. Subsequently, AGA was induced in male C57/BL6 mice by testosterone administration, followed by repeated injections of iMSC-EVs, HA-iMSC-EVs, finasteride, or vehicle. Several parameters including hair growth, anagen phase ratio, reactivation of Wnt/ß-catenin pathway, and AR expression was examined using qPCR, immunoblotting, and immunofluorescence analysis. RESULTS: Both types of EVs showed typical characteristics for EVs, such as size distribution, markers, and surface protein expression. In hair follicle dermal papilla cells, the mRNA levels of AR, TGF-ß, and IL-6 increased by testosterone was blocked by HA-iMSC-EVs, which also contributed to the augmented expression of trophic genes related to hair regrowth. However, no notable changes were observed in the iMSC-EVs. Re-activation of Wnt/ß-catenin was observed in HA-iMSC-EVs but not in iMSC-EVs, as shown by ß-catenin stabilization and an increase in phosphorylated GSK3ß. Restoration of hair growth was more significant in HA-iMSC-EVs than in iMSC-EVs, and was comparable to that in mice treated with finasteride. Consistently, the decreased anagen ratio induced by testosterone was reversed by HA-iMSC-EVs, but not by iMSC-EVs. An increased expression of hair follicular ß-catenin protein, as well as the reduction of AR was observed in the skin tissue of AGA mice receiving HA-iMSC-EVs, but not in those treated with iMSC-EVs. CONCLUSIONS: Our results suggest that HA-iMSC-EVs have potential to improve AGA by regulating growth factors/cytokines and stimulating AR-related Wnt/ß-catenin signaling.

Extracellular vesicles from IFN-γ-primed mesenchymal stem cells repress atopic dermatitis in mice.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by immune dysregulation, pruritus, and abnormal epidermal barrier function. Compared with conventional mesenchymal stem cell (MSC), induced pluripotent stem cell (iPSC)-derived mesenchymal stem cell (iMSC) is recognized as a unique source for producing extracellular vesicles (EVs) because it can be obtained in a scalable manner with an enhanced homogeneity. Stimulation of iMSCs with inflammatory cytokines can improve the immune-regulatory, anti-inflammatory, and tissue-repairing potential of iMSC-derived EVs. RESULTS: Proteome analysis showed that IFN-γ-iMSC-EVs are enriched with protein sets that are involved in regulating interferon responses and inflammatory pathways. In AD mice, expression of interleukin receptors for Th2 cytokines (IL-4Rα/13Rα1/31Rα) and activation of their corresponding intracellular signaling molecules was reduced. IFN-γ-iMSC-EVs decreased itching, which was supported by reduced inflammatory cell infiltration and mast cells in AD mouse skin; reduced IgE receptor expression and thymic stromal lymphopoietin and NF-kB activation; and recovered impaired skin barrier, as evidenced by upregulation of key genes of epidermal differentiation and lipid synthesis. CONCLUSIONS: IFN-γ-iMSC-EVs inhibit Th2-induced immune responses, suppress inflammation, and facilitate skin barrier restoration, contributing to AD improvement.

Association between Parental Cotinine-verified Smoking Status and Childhood Asthma: a Population-based Nationally Representative Analysis.

BACKGROUND: Environmental tobacco smoke exposure due to parents is a modifiable risk factor for childhood asthma, but many studies have evaluated parental smoking using self-reported data. Therefore, we aimed to analyze the relationship between parental cotinine-verified smoking status and asthma in their children. METHODS: This population-based cross-sectional study used data from the Korean National Health and Nutrition Examination Survey from 2014 to 2017. Participants aged 0 to 18 years with complete self-reported physician-diagnosed childhood asthma and measurement of their parental urinary cotinine levels were included. Parental urinary cotinine-verified smoking status was defined using both urinary cotinine levels and self-report, as active, passive, and non-smoker. Sample weights were applied to all statistical analyses because of a complex, multistage and clustered survey design. Logistic regression model was used to analyze the relationship between childhood asthma and parental smoking. RESULTS: A total of 5,264 subjects aged < 19 years were included. The prevalence of asthma was 3.4%. The proportions of paternal and maternal urinary cotinine-verified active smokers during the study period were 50.4% and 16.9%, respectively. When parental urinary cotinine level increased, the proportion of parental low household income was increased (P < 0.001). There was no significant association between the parental urinary cotinine-verified smoking group and childhood asthma group. However, the adjusted odds ratios of childhood asthma in the middle and highest tertile of paternal urinary cotinine levels compared with those in lowest tertile were 1.95 (95% confidence interval [CI], 0.98-3.89) and 2.34 (95% CI, 1.21-4.54), respectively. CONCLUSION: There seems to be a dose-related association between paternal urinary cotinine levels and the risk of childhood asthma. Because of the high rate of paternal smoking, further studies are needed to develop a targeted strategy to reduce parental smoking for childhood asthma.

Development of safety and usability guideline for clinical information system.

ABSTRACT: Clinical information systems (CISs) that do not consider usability and safety could lead to harmful events. Therefore, we aimed to develop a safety and usability guideline of CISs that is comprehensive for both users and developers. And the guideline was categorized to apply actual clinical workflow and work environment.The guideline components were extracted through a systematic review of the articles published between 2000 and 2015, and existing CIS safety and/or usability design guidelines. The guideline components were categorized according to clinical workflow and types of user interface (UI). The contents of the guideline were evaluated and validated by experts with 3 specialties: medical informatics, patient safety, and human engineering.Total 1276 guideline components were extracted through article and guideline review. Of these, 464 guideline components were categorized according to 5 divisions of the clinical workflow: "Data identification and selection," "Document entry," "Order entry," "Clinical decision support and alert," and "Management". While 521 guideline components were categorized according to 4 divisions of UI: UIs related to information process steps, "Perception," "Recognition," "Control," and "Feedback". We developed a guideline draft with 219 detailed guidance for clinical task and 70 for UI. Overall appropriateness and comprehensiveness were proven to achieve more than 90% in experts' survey. However, there were significant differences among the groups of specialties in the judgment of appropriateness (P < .001) and comprehensiveness (P = .038).We developed and verified a safety and usability guideline for CIS that qualifies the requirements of both clinical workflows and usability issues. The developed guideline can be a practical tool to enhance the usability and safety of CISs. Further validation is required by applying the guideline for designing the actual CIS.

Age-Specific Distribution of Diagnosis and Outcomes of Children Admitted to ICUs: A Population-Based Cohort Study.

OBJECTIVES: Although several studies have reported outcome data on critically ill children, detailed reports by age are not available. We aimed to evaluate the age-specific estimates of trends in causes of diagnosis, procedures, and outcomes of pediatric admissions to ICUs in a national representative sample. DESIGN: A population-based retrospective cohort study. SETTING: Three hundred forty-four hospitals in South Korea. PATIENTS: All pediatric admissions to ICUs in Korea from August 1, 2009, to September 30, 2014, were covered by the Korean National Health Insurance Corporation, with virtually complete coverage of the pediatric population in Korea. Patients less than 18 years with at least one ICUs admission between August 1, 2009, and September 30, 2014. We excluded neonatal admissions (< 28 days), neonatal ICUs, and admissions for health status other than a disease or injury. The final sample size was 38,684 admissions from 32,443 pediatric patients. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The overall age-standardized admission rate for pediatric patients was 75.9 admissions per 100,000 person-years. The most common primary diagnosis of admissions was congenital malformation (10,897 admissions, 28.2%), with marked differences by age at admission (5,712 admissions [54.8%] in infants, 3,994 admissions [24.6%] in children, and 1,191 admissions [9.9%] in adolescents). Injury was the most common primary diagnosis in adolescents (3,248 admissions, 27.1%). The overall in-hospital mortality was 2,234 (5.8%) with relatively minor variations across age. Neoplasms and circulatory and neurologic diseases had both high frequency of admissions and high in-hospital mortality. CONCLUSIONS: Admission patterns, diagnosis, management, and outcomes of pediatric patients admitted to ICUs varied by age groups. Strategies to improve critical care qualities of pediatric patients need to be based on the differences of age and may need to be targeted at specific age groups.

Clinical characteristics and etiologies of bronchiectasis in Korean children: A multicenter retrospective study.

BACKGROUND: Bronchiectasis is a chronic pulmonary disease characterized by progressive and irreversible bronchial dilatation. The aim of the present study was to investigate the etiologies and clinical features of bronchiectasis in Korean children. METHODS: We performed a retrospective review of the medical records for children diagnosed with bronchiectasis between 2000 and 2017 at 28 secondary or tertiary hospitals in South Korea. RESULTS: A total of 387 cases were enrolled. The mean age at diagnosis was 9.2 ±â€¯5.1 years and 53.5% of the patients were boys. The most common underlying cause of bronchiectasis was preexisting respiratory infection (55.3%), post-infectious bronchiolitis obliterans (14.3%), pulmonary tuberculosis (12.3%), and heart diseases (5.6%). Common initial presenting symptoms included chronic cough (68.0%), recurrent pneumonia (36.4%), fever (31.1%), and dyspnea (19.7%). The most predominantly involved lesions were left lower lobe (53.9%), right lower lobe (47.1%) and right middle lobe (40.2%). No significant difference was observed in the distribution of these involved lesions by etiology. The forced expiratory volume in 1 s (FEV1) levels were lowest in cases with interstitial lung disease-associated bronchiectasis, followed by those with recurrent aspiration and primary immunodeficiency. CONCLUSIONS: Bronchiectasis should be strongly considered in children with chronic cough and recurrent pneumonia. Long-term follow-up studies on pediatric bronchiectasis are needed to further clarify the prognosis and reduce the disease burden in these patients.

The Effect of Rhus verniciflua Stokes Extracts on Photo-Aged Mouse Skin.

BACKGROUND: Rhus verniciflua Stokes (RV) has traditionally been used in Korea as an indigenous food (Rhus chicken soup) and as an herbal medicinal plant. While the anticancer, antimicrobial, and anti-inflammatory properties of RV have been actively studied in the medical field, its antioxidant effects in the skin that resist the reactive oxygen species in keratinocytes and fibroblasts is less understood. OBJECTIVE: We designed to evaluate the effects of R. verniciflua Stokes extract (RVE) on the photo-aged skin by an in vitro experiment using human fibroblasts and an in vivo experiment using a photo-aged murine model. METHODS: For the in vitro experiments, human fibroblasts irradiated with ultraviolet (UV) B were treated with RVE or vehicle, and the growth levels and the expression level of type 1 procollagen were compared. For the in vivo experiment, photo-aged mice irradiated with UVB and UVA were administered drinking water with or without RVE, and histological changes and the expression level of type 1 procollagen and matrix metalloprotease (MMP)-13 were compared. RESULTS: In vitro experiments using fibroblasts irradiated with UVB showed that RVE promoted growth and significantly increased the expression of type 1 procollagen as compared to the control group. In the photo-aged mice, RVE increased collagen content in the dermis and promoted the synthesis of type 1 procollagen without any visible decrease in MMP-13 as compared to control group. CONCLUSION: In addition to the previously reported antioxidant effects of RVE, oral intake of RVE effectively inhibited photo-aging in hairless mice by enhancing collagen synthesis.

Validation of the Pediatric Index of Mortality 3 in a Single Pediatric Intensive Care Unit in Korea.

To compare mortality rate, the adjustment of case-mix variables is needed. The Pediatric Index of Mortality (PIM) 3 score is a widely used case-mix adjustment system of a pediatric intensive care unit (ICU), but there has been no validation study of it in Korea. We aim to validate the PIM3 in a Korean pediatric ICU, and extend the validation of the score from those aged 0-16 to 0-18 years, as patients aged 16-18 years are admitted to pediatric ICU in Korea. A retrospective cohort study of 1,710 patients was conducted in a tertiary pediatric ICU. To validate the score, the discriminatory power was assessed by calculating the area under the receiver-operating characteristic (ROC) curve, and calibration was evaluated by the Hosmer-Lemeshow goodness-of-fit (GOF) test. The observed mortality rate was 8.47%, and the predicted mortality rate was 6.57%. For patients aged < 18 years, the discrimination was acceptable (c-index = 0.76) and the calibration was good, with a χ² of 9.4 in the GOF test (P = 0.313). The observed mortality rate in the hemato-oncological subgroup was high (18.73%), as compared to the predicted mortality rate (7.13%), and the discrimination was unacceptable (c-index = 0.66). In conclusion, the PIM3 performed well in a Korean pediatric ICU. However, the application of the PIM3 to a hemato-oncological subgroup needs to be cautioned. Further studies on the performance of PIM3 in pediatric patients in adult ICUs and pediatric ICUs of primary and secondary hospitals are needed.

Protective Effect of Topical Vitamin D3 against Photocarcinogenesis in a Murine Model.

BACKGROUND: Although the incidence of non-melanoma skin cancer is increasing, there are no effective practical preventive measures other than avoiding sun exposure. OBJECTIVE: To elucidate the protective effect of topical application of biologically active vitamin D3 (calcitriol) on skin cancer development caused by exposure to ultraviolet (UV). METHODS: Groups of hairless mice were topically treated with either calcitriol or vehicle immediately after exposure to UVB and UVA three times weekly for the initial 20 weeks, and without UV exposure in the following 6 weeks. Tumor number was counted and biopsies were done for histopathologic analysis. The changes of cyclobutane pyrimidine dimer (CPD) were evaluated 1 hour and 11 hours after short term of UV exposure and application of calcitriol. For safety evaluation, blood test and body weights were evaluated at 23rd and 25th week. RESULTS: Total tumor count and number of tumors less than 3 mm in size tended to be fewer in calcitriol group, and tumors more than 3 mm in size showed significantly lower tumor formation rate in calcitriol group. Single application of calcitriol reduced CPD at 1 hour and 11 hours after UV exposure. Histopathologic analysis showed tumors with lower grade malignancy in calcitriol group which suggested a delay in tumor progression. However, serum levels of calcium and phosphate in calcitriol group were above normal range, and weight loss was found. CONCLUSION: Topical calcitriol may suppress the formation and progression of UV-induced non-melanoma skin cancer by enhancing the repair mechanism of UV damage.

The effect of rat bone marrow derived mesenchymal stem cells transplantation for restoration of olfactory disorder.

The purpose of the study was to investigate the effect of bone marrow-derived mesenchymal stem cells (BMSCs) transplantation on olfactory epithelium (OE) of morphologic and functional restoration following neural Sensorineural Disorder in rats. Except the Normal group, twenty-one rats underwent Triton X-100 (TX-100) irrigation to induce degeneration of OE, and then BMSCs and PBS were treated from the both medial canthus to the rear part of the both nasal cavity into the experimental group and then were observed for restoration according to time point. At two and four weeks after transplantation with BMSCs, restoration of OE was observed with olfactory marker protein (OMP) and behavioral test. And we observed the expression of OMP, nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). After TX-100 irrigation, the OE almost disappeared in 3 days. At four weeks after transplantation with BMSCs, the thickness and cellular composition of OE was considerably restored to normal group and expression of OMP was markedly increased when compared with PBS group and reduced the searching time in the behavioral test. Furthermore at two weeks after treatment with BMSCs, expression of NGF and BDNF was greatly increased when compared with PBS group. However at four weeks after treatment with BMSCs, expression of NGF and BDNF was slightly decreased. Our results suggest the BMSCs transplantation affect restoration of OE and olfaction, most likely via regulation of the neurotrophic factor expression, especially the expression of NGF and BDNF and has a possibility of a new therapeutic strategy for the treatment of olfactory disorder caused by the degeneration of OE.

Pyrrolidone carboxylic acid levels or caspase-14 expression in the corneocytes of lesional skin correlates with clinical severity, skin barrier function and lesional inflammation in atopic dermatitis.

BACKGROUND: Dry skin in atopic dermatitis (AD) mainly results from barrier impairment due to deficiency of ceramide and natural moisturizing factors including pyrrolidone carboxylic acid (PCA) in stratum corneum (SC). Caspase-14 cleaves filaggrin monomers to free amino acids and their derivatives such as PCA, contributing natural moisturizing factors. Cytokines in the corneocytes represent cutaneous inflammation severity of AD patients. OBJECT: To analyze the correlations of PCA, caspase-14 and cytokines in corneocytes with clinical severity, barrier function and skin inflammation, those were quantitated. METHODS: A total of 73 persons were enrolled: 21 patients with mild AD, 21 with moderate-to-severe AD, 13 with X-linked ichthyosis (XLI) as a negative control for filaggrin gene (FLG) mutation, and 18 healthy controls. Skin barrier functions such as basal transepidermal water loss (TEWL), stratum corneum (SC) hydration and skin surface pH were measured. To collect corneocytes, stripping with D-squame discs was done on lesional and non-lesional skin. And then PCA was isolated from D-squame discs and quantitated by LC-MS/MS. Cytokine assays were performed. RESULTS: The quantity of PCA and caspase-14 was decreased in inflammatory lesions compared to non-lesion in AD patients. And the amounts of PCA and caspase-14 in the lesion of AD patients correlated with clinical severity as determined by eczema area and severity index score and the skin barrier functions. Also, the expressions of TNF-α and IL-13 inversely correlated with PCA quantity. CONCLUSION: The quantity of PCA or caspase-14 in the corneocytes of the lesional skin of AD patients reflects the clinical severity, skin barrier function and the degree of lesional inflammation.

Intractable hiccup as the presenting symptom of cavernous hemangioma in the medulla oblongata: a case report and literature review.

A case of intractable hiccup developed by cavernous hemangioma in the medulla oblongata is reported. There have been only five previously reported cases of medullary cavernoma that triggered intractable hiccup. The patient was a 28-year-old man who was presented with intractable hiccup for 15 days. It developed suddenly, then aggravated progressively and did not respond to any types of medication. On magnetic resonance images, a well-demarcated and non-enhancing mass with hemorrhagic changes was noted in the left medulla oblongata. Intraoperative findings showed that the lesion was fully embedded within the brain stem and pathology confirmed the diagnosis of cavernous hemangioma. The hiccup resolved completely after the operation. Based on the presumption that the medullary cavernoma may trigger intractable hiccup by displacing or compression the hiccup arc of the dorsolateral medulla, surgical excision can eliminate the symptoms, even in the case totally buried in brainstem.

Cerebral aspergillosis with multiple enhancing nodules in the right cerebral hemisphere in the immune-competent patient.

Aspergillosis in the central nervous system (CNS) is a very rare disease in immune-competent patients. There was a case of a healthy man without a history of immune-compromised disease who had invasive aspergillosis with unusual radiologic findings. A 48-year-old healthy man with diabetes mellitus, presented with complaints of blurred vision that persisted for one month. Brain magnetic resonance imaging (MRI) showed multiple nodular enhancing lesions on the right cerebral hemisphere. The diffusion image appeared in a high-signal intensity in these areas. Cerebrospinal fluid examination did not show any infection signs. An open biopsy was done and intraoperative findings showed grayish inflammatory and necrotic tissue without a definitive mass lesion. The pathologic result was a brain abscess caused by fungal infection, morphologically aspergillus. Antifungal agents (Amphotericin B, Ambisome and Voriconazole) were used for treatment for 3 months. The visual symptoms improved. There was no recurrence or abscess pocket, but the remaining focal enhanced lesions were visible in the right temporal and occipital area at a one year follow-up MRI. This immune-competent patient showed multiple enhancing CNS aspergillosis in the cerebral hemisphere, which had a good outcome with antifungal agents.

Indeterminate pleural metastasis on contrast-enhanced chest CT in non-small cell lung cancer: improved differential diagnosis with (18)F-FDG PET/CT.

PURPOSE: To evaluate the diagnostic performance of (18)F-fluorodeoxyglucose (FDG) PET/CT (PET/CT) for determining the presence of pleural metastasis in patients with indeterminate findings on a contrast-enhanced chest CT (CECT) for non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: This is a retrospective study. NSCLC patients (n = 63) who underwent thoracentesis and/or pleural biopsy were enrolled. CECT and PET/CT reports of pleural metastasis were analyzed based on comparison with cytological or histological confirmation. Negative cytologic results were re-confirmed with follow-up study prior to cancer-related therapy. CECT results were classified into 3 categories: negative, indeterminate, and positive for pleural metastasis. PET/CT results were classified into 2 categories (negative and positive for pleural metastasis) based on FDG uptake visual grading. The level of max SUV of pleura was also analyzed. ROC analysis was done for establishing the max SUV cut-off value. RESULT: PET/CT could differentiate pleural metastasis with 70.8% diagnostic accuracy when the CECT finding was indeterminate (n = 24). Optimal cut-off value to predict pleural metastasis was 2.8 for max SUV. Diagnosis by max SUV 2.8 had lower sensitivity (86.3 vs. 92.2%), but higher specificity (66.7 vs. 58.3%) than PET/CT by FDG visual grading criteria. CONCLUSION: PET/CT showed better diagnostic performance than CECT for detecting pleural metastasis in NSCLC patients. When the finding of CECT is controversial, PET/CT can differentiate the metastatic pleural lesion. Both FDG uptake visual grading and max SUG cut-off value can be used as diagnostic criteria for pleural metastasis.

Adipose-derived stem cells as a new therapeutic modality for ageing skin.

Stem cells are undifferentiated cells, which have the important properties of self-renewal and differentiation. Adipose-derived stem cells (ADSC) have relative advantages in accessibility and abundance compared to other kinds of stem cells. Regeneration therapy using ADSC has received attention in the treatment of various dermatologic diseases. In previous studies, ADSC were shown to have antioxidant, whitening and wound-healing effects in the skin through secretion of growth factors and by activating fibroblasts. In this study, we investigated whether ADSC could be used as an anti-ageing therapy, especially by dermal collagen synthesis and angiogenesis. Subcutaneous injection of ADSC significantly increased collagen synthesis in hairless mice, and dermal thickness, collagen density and fibroblast number also increased. In addition, procollagen type I protein and mRNA expression increased, which accounts for the increased dermal collagen density. Angiogenesis, which was visualized by CD31 and NG2 immunofluorescence stains, also increased in ADSC-treated skin. Our results suggest that ADSC therapy may be useful in ageing skin. Its effects are mainly mediated by stimulating collagen synthesis in dermal fibroblasts and increasing angiogenesis.

Biopositive effects of low-dose UVB on epidermis: coordinate upregulation of antimicrobial peptides and permeability barrier reinforcement.

Whereas high-dose ultraviolet B (UVB) is detrimental to the epidermal permeability barrier, suberythemal doses of UVB are used to treat atopic dermatitis (AD), which is characterized by defective permeability barrier and antimicrobial function. As epidermal permeability barrier and antimicrobial peptide (AMP) expression are coregulated and interdependent functions, we hypothesized that suberythemal doses of UVB exposure could regulate AMP expression in parallel with permeability barrier function. Hairless mice were exposed to 40 mJ cm(-2) UVB (about 1/2 minimal erythema dose) daily for 1 or 3 days. Twenty-four hours after the last exposure, epidermal barrier function was assessed and skin specimens were taken for western blotting, immunohistochemistry, and quantitative reverse transcription-PCR for mouse beta-defensin (mBD)-2, mBD3 and cathelin-related antimicrobial peptide (CRAMP). mRNA levels of the vitamin D receptor (VDR), 1alpha-hydroxylase and key epidermal lipid synthetic enzymes were also quantified. After 3 days of UVB exposure, acceleration of barrier recovery and augmentation in expression of epidermal differentiation markers (for example, involucrin and filaggrin) occurred in parallel with increased mBD2, mBD3, and CRAMP expression at both the mRNA and protein level. VDR, 1alpha-hydroxylase, and the major epidermal lipid synthetic enzymes were also upregulated. When an inhibitor of 1alpha, 25 dihydroxyvitamin D(3) formation, ketoconazole, was applied immediately after UVB exposure, the cutaneous vitamin D system was inhibited, which in turn blocked epidermal lipid synthesis, AMP expression, and permeability barrier homeostasis, suggesting that the beneficial effect of low-dose UVB depends, at least in part, on activation of the cutaneous vitamin D system. Our results provide new insights into the mechanisms whereby low-dose UVB comprises effective therapy for AD.