Importance of Stratum Corneum Acidification to Restore Skin Barrier Function in Eczematous Diseases.

Skin barrier function relies on three essential components: stratum corneum (SC) lipids, natural moisturizing factors (NMFs), and the acidic pH of the SC surface. Three endogenous pathways contribute to acidity: free fatty acids from phospholipids, trans-urocanic acid from filaggrin (FLG), and the sodium-proton antiporter (NHE1) activity. An acidic SC environment boosts the activity of enzymes to produce ceramides, which are vital for skin health. Conversely, an elevated pH can lead to increased skin infections, reduced lipid-processing enzyme activity, impaired permeability barrier recovery, and compromised integrity and cohesion of the SC due to increased serine protease (SP) activity. Elevated SC pH is observed in neonatal, aged, and inflamed skin. In atopic dermatitis (AD), it results from decreased NMF due to reduced FLG degradation, decreased fatty acids from reduced lamellar body secretion, and reduced lactic acid due to decreased sweating. Moreover, the imbalance between SP and SP inhibitors disrupts barrier homeostasis. However, acidifying the SC can help restore balance and reduce SP activity. Acidic water bathing has been found to be safe and effective for AD. In three different AD murine models, SC acidification prevented the progression of AD to respiratory allergies. In aging skin, a decrease in NHE1 leads to an increased skin pH. Mild acidic skin care products or moisturizers containing NHE1 activators can normalize skin pH and improve barrier function. In conclusion, maintaining the acidity of the SC is crucial for healthy skin barrier function, leading to significant benefits for various skin conditions, such as AD and aging-related skin issues.

The Impact of Intervention Design on User Engagement in Digital Therapeutics Research: Factorial Experiment With a Mixed Methods Study.

BACKGROUND: User engagement is crucial for digital therapeutics (DTx) effectiveness; due to variations in the conceptualization of engagement and intervention design, assessment and retention of engagement remain challenging. OBJECTIVE: We investigated the influence of the perceived acceptability of experimental intervention components and satisfaction with core intervention components in DTx on user engagement, while also identifying potential barriers and facilitators to user engagement. METHODS: We conducted a mixed methods study with a 2 × 2 factorial design, involving 12 outpatients with atopic dermatitis. Participants were randomized into 4 experimental groups based on push notification ("basic" or "advanced") and human coach ("on" or "off") experimental intervention components. All participants engaged in self-monitoring and learning courses as core intervention components within an app-based intervention over 8 weeks. Data were collected through in-app behavioral data, physician- and self-reported questionnaires, and semistructured interviews assessed at baseline, 4 weeks, and 8 weeks. Descriptive statistics and thematic analysis were used to evaluate user engagement, perceived acceptability of experimental intervention components (ie, push notification and human coach), satisfaction with core intervention components (ie, self-monitoring and learning courses), and intervention effectiveness through clinical outcomes. RESULTS: The primary outcome indicated that group 4, provided with "advanced-level push notifications" and a "human coach," showed higher completion rates for self-monitoring forms and learning courses compared to the predetermined threshold of clinical significance. Qualitative data analysis revealed three key themes: (1) perceived acceptability of the experimental intervention components, (2) satisfaction with the core intervention components, and (3) suggestions for improvement in the overall intervention program. Regarding clinical outcomes, the Perceived Stress Scale and Dermatology Life Quality Index scores presented the highest improvement in group 4. CONCLUSIONS: These findings will help refine the intervention and inform the design of a subsequent randomized trial to test its effectiveness. Furthermore, this design may serve as a model for broadly examining and optimizing overall engagement in DTx and for future investigation into the complex relationship between engagement and clinical outcomes. TRIAL REGISTRATION: Clinical Research Information Service KCT0007675; http://tinyurl.com/2m8rjrmv.

Comparing the diagnostic accuracy of PCR-reverse blot hybridization assay and conventional fungus study in superficial fungal infection of the skin: A systematic review.

BACKGROUND: In superficial fungal infections, prompt diagnosis and treatment are essential to prevent the spread of infection and minimise the impact on patients' quality of life. Traditional diagnostic methods, such as KOH smear and fungal culture, have limitations in terms of sensitivity and turnaround time. Recently, the PCR-reverse blot hybridization assay (PCR-REBA) has been developed for the direct detection of dermatophyte DNA. However, there is a lack of information assessing the diagnostic accuracy of PCR-REBA. OBJECTIVES: This systematic review aimed to evaluate the diagnostic accuracy of PCR-REBA in superficial fungal infections compared to conventional and molecular methods. METHODS: The comprehensive search containing Ovid MEDLINE and Embase databases was conducted on 7 August 2022. Two reviewers independently reviewed the included articles. Quality assessment was performed using the Newcastle-Ottawa Scale tool. RESULTS: The included studies were conducted in Korea (five studies) and the Netherlands (two studies), all of which were conducted in a single institution. The quality assessment of these studies indicated low risk of bias. When compared to the potassium hydroxide (KOH) smear and fungus culture, the sensitivity of PCR-REBA ranged from 85% to 100%, and the positive predictive values ranged from 58.9% to 100%. When compared to the RT-PCR, the sensitivity of PCR-REBA ranged from 93.3% to 100%, and the positive and negative predictive values were 91.6%-99.6% and 81.0%-89.1%, respectively. CONCLUSIONS: The PCR-REBA shows promise as a valuable diagnostic tool for dermatophytosis, offering practical and cost-effective benefits.

Barrier Abnormalities in Type 1 Diabetes Mellitus: The Roles of Inflammation and Ceramide Metabolism.

Xerosis is a common sign of both type 1 and type 2 diabetes mellitus (DM), and patients with DM and mouse models for DM show a compromised epidermal permeability barrier. Barrier defects then allow the entry of foreign substances into the skin, triggering inflammation, infection, and worsening skin symptoms. Characterizing how barrier abnormalities develop in DM could suggest treatments for xerosis and other skin disease traits. Because the proper ratio, as well as proper bulk amounts, of heterogeneous ceramide species are keys to forming a competent barrier, we investigated how ceramide metabolism is affected in type 1 DM using a mouse model (induced by streptozotocin). Chronic inflammation, evident in the skin of mice with DM, leads to (i) decreased de novo ceramide production through serine racemase activation-mediated attenuation of serine palmitoyl transferase activity by D-serine; (ii) changes in ceramide synthase activities and expression that modify the ratio of ceramide molecular species; and (iii) increased ceramide-1-phosphate, a proinflammatory lipid mediator, that stimulates inflammatory cytokine expression (TNFα and IFN-γ). Together, chronic inflammation affects ceramide metabolism, which attenuates epidermal permeability barrier formation, and ceramide-1-phosphate could amplify this inflammation. Alleviation of chronic inflammation is a credible approach for normalizing barrier function and ameliorating diverse skin abnormalities in DM.

A Refractory Livedoid Vasculopathy Accompanied by Methylene Tetrahydrofolate Reductase Gene Polymorphism Successfully Treated with Hyperbaric Oxygen Therapy.

Livedoid vasculopathy (LV) is a chronic coagulation disorder characterized by recurrent, painful ulcers on the lower extremities. Methylene tetrahydrofolate reductase (MTHFR) gene polymorphism is associated with coagulopathy. Therapeutic options usually include anti-inflammatory or immunosuppressive agents. However, the condition is still highly challenging to manage and no consensus over the first-line treatment for LV exists. Furthermore, when LV is accompanied with MTHFR gene polymorphism, clinical presentations could be more severe and resistant to treatment. We report a case of refractory LV accompanied by MTHFR gene polymorphism, which was successfully treated with hyperbaric oxygen therapy (HBOT). A 63-year-old female patient presented with multiple painful ulcers, atrophie blanches, and retiform purpura on both lower legs and feet. Histopathologic findings were compatible with LV. LV was diagnosed based on these clinicopathological findings. Following the diagnosis, we treated the patient with pentoxifylline, aspirin, systemic corticosteroid, antihistamine, and antibiotics. In spite of six-month treatment, the skin lesions did not improve; hence, HBOT was performed. It was performed at 2.0 absolute atmosphere for 120 minutes each time, three times a week. After 4 sessions, the ulcers began to heal and after 13 sessions, the skin lesions almost healed. During the eight-month follow-up period, the skin ulcers did not recur and the symptoms remained stable. Additionally, it was confirmed that she had MTHFR gene polymorphism after a genetic test. In conclusion, we wish to provide evidence regarding the effectiveness of HBOT and suggest that HBOT might be a considerable treatment option in refractory LV.

Hyperglycemia-activated 11ß-hydroxysteroid dehydrogenase type 1 increases endoplasmic reticulum stress and skin barrier dysfunction.

The diabetes mellitus (DM) skin shows skin barrier dysfunction and skin lipid abnormality, similar to conditions induced by systemic or local glucocorticoid excess and aged skin. Inactive glucocorticoid (GC) is converted into active glucocorticoid by 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1). Hyperglycemia in DM and excessive GC are known to increase endoplasmic reticulum (ER) stress. We hypothesized that hyperglycemia affects systemic GC homeostasis and that the action of skin 11ß-HSD1 and GC contributes to increased ER stress and barrier defects in DM. We compared 11ß-HSD1, active GC, and ER stress between hyperglycemic and normoglycemic conditions in normal human keratinocytes and db/db mice. 11ß-HSD1 and cortisol increased with time in keratinocyte culture under hyperglycemic conditions. 11ß-HSD1 siRNA-transfected cells did not induce cortisol elevation in hyperglycemic condition. The production of 11ß-HSD1 and cortisol was suppressed in cell culture treated with an ER stress-inhibitor. The 14-week-old db/db mice showed higher stratum corneum (SC) corticosterone, and skin 11ß-HSD1 levels than 8-week-old db/db mice. Topical 11ß-HSD1 inhibitor application in db/db mice decreased SC corticosterone levels and improved skin barrier function. Hyperglycemia in DM may affect systemic GC homeostasis, activate skin 11ß-HSD1, and induce local GC excess, which increases ER stress and adversely affects skin barrier function.

Erratum: Assessment of Disease Severity and Quality of Life in Patients with Atopic Dermatitis from South Korea.

This corrects the article on p. 419 in vol. 34, PMID: 36478424.

Assessment of Disease Severity and Quality of Life in Patients with Atopic Dermatitis from South Korea.

BACKGROUND: Data illustrating the impact of atopic dermatitis (AD) on lives of adults with AD in South Korea are limited. OBJECTIVE: To assess the AD disease severity and its impact on quality of life (QoL) in patients with AD from South Korea. METHODS: Patients with AD utilizing the specialist dermatology services of major hospitals in South Korea were assessed for disease severity using Eczema Area and Severity Index (EASI) score, for QoL using Dermatology Life Quality Index (DLQI) (for QoL), and for comorbidities and treatment experience via retrospective review of 12-month medical records. Clinical and sociodemographic characteristics were also measured. RESULTS: Of the 1,163 patients, 695 (59.8%) were men (mean age [years]±standard deviation: 31.6±12.1). Overall, 52.9% (n=615) patients had moderate-to-severe disease (EASI>7). The QoL of 72.3% (n=840) patients was affected moderately-to-severely (DLQI score: 6~30). Systemic immunosuppressants were used ≥1 over past 12 months in 51.9% (n=603) patients, and the most commonly used were cyclosporines (45.7%, n=531) and systemic corticosteroids (40.5%, n=471). Approximately, 10.8% (n=126) patients consulted or received treatment for AD-related eye problem. Of these, 40% (n=50) patients reported poor, very poor, or completely blind status; approximately, 16.7% patients (n=192) reported having depression or anxiety; and 35.5% (n=410) reported suicidal ideation or suicidal attempt. CONCLUSION: A large proportion of patients had moderate-to-severe AD, a compromised QoL, and ocular or mental health comorbidities, indicating a high disease burden despite systemic treatment. These findings highlight the importance of a holistic approach for the evaluation and treatment of patients with AD.

Rosmarinic Acid, as an NHE1 Activator, Decreases Skin Surface pH and Improves the Skin Barrier Function.

Stratum corneum (SC) pH regulates skin barrier functions and elevated SC pH is an important factor in various inflammatory skin diseases. Acidic topical formulas have emerged as treatments for impaired skin barriers. Sodium proton exchanger 1 (NHE1) is an important factor in SC acidification. We investigated whether topical applications containing an NHE1 activator could improve skin barrier functions. We screened plant extracts to identify NHE1 activators in vitro and found Melissa officinalis leaf extract. Rosmarinic acid, a component of Melissa officinalis leaf extract, significantly increased NHE1 mRNA expression levels and NHE1 production. Immunofluorescence staining of NHE1 in 3D-cultured skin revealed greater upregulation of NHE1 expression by NHE1 activator cream, compared to vehicle cream. Epidermal lipid analysis revealed that the ceramide level was significantly higher upon application of the NHE1 activator cream on 3D-cultured skin, compared to application of a vehicle cream. In a clinical study of 50-60-year-old adult females (n = 21), application of the NHE1 activator-containing cream significantly improved skin barrier functions by reducing skin surface pH and transepidermal water loss and increasing skin hydration, compared to patients who applied vehicle cream and those receiving no treatment. Thus, creams containing NHE1 activators, such as rosmarinic acid, could help maintain or recover skin barrier functions.

Increased prevalence of transfusion-transmitted diseases among people with tattoos: A systematic review and meta-analysis.

Whether having a tattoo increases the risk of transfusion-transmitted diseases (TTDs) is controversial. Although a few studies have suggested a strong association between having tattoos and TTDs, other studies have not shown the significance of the association. In addition, previous studies mainly focused only on hepatitis C viral infections. The objective of our study was to identify the prevalence and risk of TTDs in people with tattoos as compared with the non-tattooed population. A systematic review of the studies published before January 22, 2021, was performed using the Pubmed, Embase, and Web of Science databases. Observational studies on hepatitis C virus (HCV), hepatitis B virus (HBV), human immunodeficiency virus (HIV), and syphilis infections in people with and without tattoos were included. Studies that reported disease status without serological confirmation were excluded. A total of 121 studies were quantitatively analyzed. HCV (odds ratio [OR], 2.37; 95% confidence interval [CI], 2.04-2.76), HBV (OR, 1.55; 95% CI, 1.31-1.83), and HIV infections (OR, 3.55; 95% CI, 2.34-5.39) were more prevalent in the tattooed population. In subgroup analyses, the prevalence of HCV infection was significantly elevated in the general population, hospital patient, blood donor, intravenous (IV) drug user, and prisoner groups. IV drug users and prisoners showed high prevalence rates of HBV infection. The prevalence of HIV infection was significantly increased in the general population and prisoner groups. Having a tattoo is associated with an increased prevalence of TTDs. Our approach clarifies in-depth and supports a guideline for TTD screening in the tattooed population.

A Lipid Mixture Enriched by Ceramide NP with Fatty Acids of Diverse Chain Lengths Contributes to Restore the Skin Barrier Function Impaired by Topical Corticosteroid.

INTRODUCTION: The stratum corneum (SC) is a skin barrier that consists of corneocytes, intercellular lipids, and corneodesmosomes. Ceramides are composed of sphingoid bases linked with various types of fatty acids (FAs), and they are an essential constituent of SC intercellular lipids. Among their subtypes, ceramide NP with a phytosphingosine base is especially important. Most of the previous studies on barrier recovery have focused on a specific ceramide with a single chain FA, not with diverse chain lengths. Skin barrier function is impaired by various factors, including topical corticosteroid. OBJECTIVE: We evaluated whether a lipid mixture enriched by ceramide NP with FAs of diverse chain lengths (CER [NP]*) can restore the skin barrier function impaired by topical corticosteroid. METHODS: Twenty-seven healthy adult male volunteers were recruited. Topical corticosteroid was applied on both volar forearms of volunteers. Then, the test cream containing a lipid mixture with CER (NP)* was applied on the left forearm, and a vehicle cream without a lipid mixture was applied on the right forearm of each subject. The functional parameters of the skin barrier were compared before and after the treatment. Epidermal differentiation markers, hyaluronic acid synthase 3 (HAS3), cytokine levels, and the lipid profiles in the SC were analyzed. RESULTS: The functional parameters of the skin barrier, such as barrier recovery rate, SC integrity, and SC hydration were significantly improved in the test cream-applied site compared to the vehicle cream-applied sites. Filaggrin and HAS3 levels were significantly higher in the sites applied with the test cream. Interleukin (IL)-1α levels were also significantly increased in these sites. IL-2, IL-6, IL-10, and IL-13 levels were significantly decreased in the test cream-applied sites. Lipid analyses showed that C18, C20, and total ceramide NP levels significantly increased in the sites where the test cream was applied. Also, C16, C18, C20, C24, and total ceramide NP levels were significantly elevated in the test cream-applied sites after acute barrier disruption. CONCLUSION: Our results demonstrate that a lipid mixture enriched by CER (NP)* could recover the barrier function impaired by topical corticosteroid.

Skin atrophy caused by topical glucocorticoids is less common in patients with atopic dermatitis than in those with psoriasis.

Although the long-term use of topical glucocorticoids (TGC) may induce skin atrophy including striae distensae (SD), patients with atopic dermatitis (AD) appear to have lesser degree of skin atrophy than those with psoriasis (PSO). Periostin, encoded by POSTN, is involved in tissue remodelling processes of chronic AD lesions. This study was designed to investigate the difference in the occurrence of skin atrophy in patients with AD or PSO when treated with TGC and to elucidate the association between skin atrophy and periostin. Big data analysis using Korean Health Claims Database was performed to determine the prevalence of SD in AD and PSO patients. Blood and skin eosinophils count and dermal fibrosis between AD and PSO patients were compared, and immunohistochemistry for periostin and mRNA sequencing in the dermis were performed. Animal experiments using AD and PSO murine model were conducted. Big data analysis revealed that patients with AD have significantly lesser degree of SD than patients with PSO. The ratio of the dermal fibrous tissues and eosinophil counts were significantly higher in AD patients. In AD skin, periostin was more widely distributed in the entire dermis and POSTN mRNAs were significantly upregulated. Dermal thickness and fibrosis were significantly higher in AD mice even after TGC treatment. A significant positive correlation was observed between dermal fibrosis and tissue eosinophil counts. Lesser skin atrophy in AD patients even after long-term TGC application could be resulted from skin fibrosis caused by increased tissue eosinophils and periostin deposition.

Consensus Update for Systemic Treatment of Atopic Dermatitis.

BACKGROUND: In 2015, the Korean Atopic Dermatitis Association (KADA) working group published consensus guidelines for treating atopic dermatitis (AD). OBJECTIVE: We aimed to provide updated consensus recommendations for systemic treatment of AD in South Korea based on recent evidence and experience. METHODS: We compiled a database of references from relevant systematic reviews and guidelines on the systemic management of AD. Evidence for each statement was graded and classified based on thestrength of the recommendation. Forty-two council members from the KADA participated in three rounds of voting to establish a consensus on expert recommendations. RESULTS: We do not recommend long-term treatment with systemic steroids forpatients with moderate-to-severe AD due to the risk of adverse effects. We recommend treatment with cyclosporine or dupilumab and selective treatment with methotrexate or azathioprine for patients with moderate-to-severe AD. We suggest treatment with antihistamines as an option for alleviating clinical symptoms of AD. We recommend selective treatment with narrowband ultraviolet B for patients with chronic moderate-to-severe AD. We do not recommend treatment with oral antibiotics for patients with moderate-to-severe AD but who have no signs of infection. We did not reach a consensus on recommendations for treatment with allergen-specific immunotherapy, probiotics, evening primrose oil, orvitamin D for patients with moderate-to-severe AD. We also recommend educational interventions and counselling for patients with AD and caregivers to improve the treatment success rate. CONCLUSION: We look forward to implementing a new and updated consensus of systemic therapy in controlling patients with moderate-to-severe AD.

Increased Expression of 11ß-Hydroxysteroid Dehydrogenase Type 1 Contributes to Epidermal Permeability Barrier Dysfunction in Aged Skin.

Inactive cortisone is converted into active cortisol by 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1). Excessive levels of active glucocorticoids could deteriorate skin barrier function; barrier impairment is also observed in aged skin. In this study, we aimed to determine whether permeability barrier impairment in the aged skin could be related to increased 11ß-HSD1 expression. Aged humans (n = 10) showed increased cortisol in the stratum corneum (SC) and oral epithelium, compared to young subjects (n = 10). 11ß-HSD1 expression (as assessed via immunohistochemical staining) was higher in the aged murine skin. Aged hairless mice (56-week-old, n = 5) manifested greater transepidermal water loss, lower SC hydration, and higher levels of serum inflammatory cytokines than the young mice (8-week-old, n = 5). Aged 11ß-HSD1 knockout mice (n = 11), 11ß-HSD1 inhibitor (INHI)-treated aged wild type (WT) mice (n = 5) and young WT mice (n = 10) exhibited reduced SC corticosterone level. Corneodesmosome density was low in WT aged mice (n = 5), but high in aged 11ß-HSD1 knockout and aged INHI-treated WT mice. Aged mice exhibited lower SC lipid levels; this effect was reversed by INHI treatment. Therefore, upregulation of 11ß-HSD1 in the aged skin increases the active-glucocorticoid levels; this suppresses SC lipid biosynthesis, leading to impaired epidermal permeability barrier.

A novel mineralocorticoid receptor antagonist, 7,3',4'-trihydroxyisoflavone improves skin barrier function impaired by endogenous or exogenous glucocorticoids.

Excess glucocorticoids (GCs) with either endogenous or exogenous origins deteriorate skin barrier function. GCs bind to mineralocorticoid and GC receptors (MRs and GRs) in normal human epidermal keratinocytes (NHEKs). Inappropriate MR activation by GCs mediates various GC-induced cutaneous adverse events. We examined whether MR antagonists can ameliorate GC-mediated skin barrier dysfunction in NHEKs, reconstructed human epidermis (RHE), and subjects under psychological stress (PS). In a preliminary clinical investigation, topical MR antagonists improved skin barrier function in topical GC-treated subjects. In NHEKs, cortisol induced nuclear translocation of GR and MR, and GR and MR antagonists inhibited cortisol-induced reductions of keratinocyte differentiation. We identified 7,3',4'-trihydroxyisoflavone (7,3',4'-THIF) as a novel compound that inhibits MR transcriptional activity by screening 30 cosmetic compounds. 7,3',4'-THIF ameliorated the cortisol effect which decreases keratinocyte differentiation in NHEKs and RHE. In a clinical study on PS subjects, 7,3',4'-THIF (0.1%)-containing cream improved skin barrier function, including skin surface pH, barrier recovery rate, and stratum corneum lipids. In conclusion, skin barrier dysfunction owing to excess GC is mediated by MR and GR; thus, it could be prevented by treatment with MR antagonists. Therefore, topical MR antagonists are a promising therapeutic option for skin barrier dysfunction after topical GC treatment or PS.

Role of 11ß-hydroxysteroid dehydrogenase type 1 in the development of atopic dermatitis.

Glucocorticoids (GCs) are potent anti-inflammatory drugs, the secretion of which is mediated and controlled by the hypothalamic-pituitary-adrenal axis. However, they are also secreted de novo by peripheral tissues for local use. Several tissues express 11ß-hydroxysteroid dehydrogenase 1 (11ß-HSD1), including the skin. The inactive GC cortisone is converted by 11ß-HSD1 to active GC cortisol, which is responsible for delayed wound healing during a systemic excess of GC. However, the role of 11ß-HSD1 in inflammation is unclear. We assessed whether 11ß-HSD1 affects the development of atopic dermatitis (AD) in vitro and in vivo. The expression of 11ß-HSD1 in the epidermis of AD lesions was higher than that in the epidermis of healthy controls. Knockdown of 11ß-HSD1 in human epidermal keratinocytes increased the production of thymic stromal lymphopoietin. In an oxazolone-induced mouse model of AD, localized inhibition of 11ß-HSD1 aggravated the development of AD and increased serum cytokine levels associated with AD. Mice with whole-body knockout (KO) of 11ß-HSD1 developed significantly worse AD upon induction by oxazolone. We propose that 11ß-HSD1 is a major factor affecting AD pathophysiology via suppression of atopic inflammation due to the modulation of active GC in the skin.

Identification of Mycobacterium tuberculosis and non-tuberculous mycobacteria from cutaneous sarcoidosis lesions by reverse blot hybridization assay.

While the etiology of sarcoidosis remains uncertain, mycobacteria have been suggested as a causative infectious agent. To investigate the causal relationship between mycobacteria and sarcoidosis, we performed a reverse blot hybridization assay (REBA) to identify mycobacteria from the skin samples of nine patients with sarcoidosis. Six of the nine samples were shown to be positive for mycobacteria by REBA, including Mycobacterium tuberculosis and non-tuberculous mycobacteria. This is the first study to identify mycobacteria from the skin samples of sarcoidosis patients using REBA, and our results could strengthen the etiologic association between mycobacteria and sarcoidosis.

Aging of the skin barrier.

The skin barrier is mainly present in the stratum corneum (SC), composed of corneocytes surrounded by intercellular lipid lamellae, and attached by corneodesmosome. The tight junction attached to the lateral walls of keratinocytes in the upper part of the stratum granulosum is also included in the skin barrier. During aging, the following structures and functions of the skin barrier are changed or disturbed: (1) skin barrier structure, (2) permeability barrier function, (3) epidermal calcium gradient, (4) epidermal lipid synthesis and SC lipid processing, (5) cytokine production and response after insults, (6) SC acidity, (7) SC hydration, and (8) antimicrobial barrier. Patients with diabetes also show changes in the skin barrier similar to those in aged skin, and the characteristics of the skin barrier are very similar. Understanding the pathogenic mechanisms of the skin barrier in aging will permit us to develop therapeutic strategies for aged or diabetic skin.