Epidermal permeability barrier defects and barrier repair therapy in atopic dermatitis

Vinpocetine, a phosphodiesterase 1 inhibitor, mitigates atopic dermatitis-like skin inflammation

Atopic dermatitis (AD) is the most common inflammatory pruritic skin disease worldwide, characterized by the infiltration of multiple pathogenic T lymphocytes and histological symptoms such as epidermal and dermal thickening. This study aims to investigate the effect of vinpocetine (Vinp; a phosphodiesterase 1 inhibitor) on a 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD-like model. DNCB (1%) was administered on day 1 in the AD model. Subsequently, from day 14 onward, mice in each group (Vinp-treated groups: 1 mg/kg and 2 mg/kg and dexamethasone- treated group: 2 mg/kg) were administered 100 µl of a specific drug daily, whereas 0.2% DNCB was administered every other day for 30 min over 14 days. The Vinp-treated groups showed improved Eczema Area and Severity Index scores and trans-epidermal water loss, indicating the efficacy of Vinp in improving AD and enhancing skin barrier function. Histological analysis further confirmed the reduction in hyperplasia of the epidermis and the infiltration of inflammatory cells, including macrophages, eosinophils, and mast cells, with Vinp treatment. Moreover, Vinp reduced serum concentrations of IgE, interleukin (IL)-6, IL-13, and monocyte chemotactic protein-1. The mRNA levels of IL-1β, IL-6, Thymic stromal lymphopoietin, and transforming growth factor-beta (TGF-β) were reduced by Vinp treatment. Reduction of TGF-β protein by Vinp in skin tissue was also observed. Collectively, our results underscore the effectiveness of Vinp in mitigating DNCB-induced AD by modulating the expression of various biomarkers. Consequently, Vinp is a promising therapeutic candidate for treating AD.

A systematic review and meta-analysis of nutritional and dietary interventions in randomized controlled trials for skin symptoms in children with atopic dermatitis and without food allergy: An EAACI task force report

This systematic review and meta-analysis aimed to consolidate evidence on dietary interventions for atopic eczema/dermatitis (AD) skin symptoms in children without food allergies, following PRISMA 2020 guidelines. Systematic review updates were conducted in May 2022 and June 2023, focusing on randomized placebo-controlled trials (RCTs) involving children with AD but without food allergies. Specific diets or supplements, such as vitamins, minerals, probiotics, prebiotics, symbiotics, or postbiotics, were explored in these trials. Exclusions comprised descriptive studies, systematic reviews, meta-analyses, letters, case reports, studies involving elimination diets, and those reporting on food allergens in children and adolescents. Additionally, studies assessing exacerbation of AD due to food allergy/sensitization and those evaluating elimination diets' effects on AD were excluded. Nutritional supplementation studies were eligible regardless of sensitization profile. Evaluation of their impact on AD clinical expression was performed using SCORAD scores, and a meta-analysis of SCORAD outcomes was conducted using random-effect models (CRD42022328702). The review encompassed 27 RCTs examining prebiotics, Vitamin D, evening primrose oil, and substituting cow's milk formula with partially hydrolyzed whey milk formula. A meta-analysis of 20 RCTs assessing probiotics, alone or combined with prebiotics, revealed a significant reduction in SCORAD scores, suggesting a consistent trend in alleviating AD symptoms in children without food allergies. Nonetheless, evidence for other dietary interventions remains limited, underscoring the necessity for well-designed intervention studies targeting multiple factors to understand etiological interactions and propose reliable manipulation strategies.

Skin Barrier in Atopic Dermatitis

A compromised permeability barrier is a hallmark of atopic dermatitis (AD). Localized to the outermost skin layer, the stratum corneum (SC) is critically dependent on terminal differentiation of epidermal keratinocytes, which transform into protein-rich corneocytes surrounded by extracellular lamellae of unique epidermal lipids, conferring permeability barrier function. These structures are disrupted in AD. A leaky barrier is prone to environmental insult, which in AD elicits type 2-dominant inflammation, in turn resulting in a vicious cycle further impairing the SC structure. Therapies directed at enforcing SC structure and anti-inflammatory strategies administered by topical and systemic route as well as UV therapy have differential effects on the permeability barrier. The expanding armamentarium of therapeutic modalities for AD treatment warrants optimization of their effects on permeability barrier function.

Ozonated Sunflower Oil (OSO) Alleviates Inflammatory Responses in Oxazolone-Induced Atopic Dermatitis (AD)-Like Mice and LPS-Treated RAW 264.7 Cells

Ozone, a highly reactive oxidant molecule, is widely used as a complementary therapy for various skin diseases, including wound healing, pressure ulcers, diabetic foot, and infections. However, there is limited research on the effectiveness of ozone for atopic dermatitis (AD). Ozonated sunflower oil (OSO) is an active ingredient obtained from partially ozonated sunflower oil (SO). OSO markedly reduced the LPS-induced increase in IL-1β and nitric oxide (NO) levels in RAW 264.7 mouse macrophage cells. Oxazolone (OXZ) was applied to hairless mice to induce AD-like skin symptoms and immune response. OSO significantly alleviated the OXZ-induced increases in the number of infiltrating mast cells, epidermal thickness, AD symptoms, thymic stromal lymphopoietin (TSLP), and filaggrin, as well as the serum levels of NO, IgE, IL-1β, and TNF-α. Furthermore, OSO inhibited the IL-4/STAT3/MAPK pathway and the expression of NF-κB. Our results suggest that OSO treatment could relieve AD-mediated skin damage through its anti-inflammatory and antioxidant activities. Therefore, it can be used as a therapeutic agent against AD-related skin diseases.

Distinct T cell signatures are associated with Staphylococcus aureus skin infection in pediatric atopic dermatitis

Atopic dermatitis (AD) is an inflammatory skin condition with a childhood prevalence of up to 25%. Microbial dysbiosis is characteristic of AD, with Staphylococcus aureus the most frequent pathogen associated with disease flares and increasingly implicated in disease pathogenesis. Therapeutics to mitigate the effects of S. aureus have had limited efficacy and S. aureus-associated temporal disease flares are synonymous with AD. An alternative approach is an anti-S. aureus vaccine, tailored to AD. Experimental vaccines have highlighted the importance of T cells in conferring protective anti-S. aureus responses; however, correlates of T cell immunity against S. aureus in AD have not been identified. We identify a systemic and cutaneous immunological signature associated with S. aureus skin infection (ADS.aureus) in a pediatric AD cohort, using a combined Bayesian multinomial analysis. ADS.aureus was most highly associated with elevated cutaneous chemokines IP10 and TARC, which preferentially direct Th1 and Th2 cells to skin. Systemic CD4+ and CD8+ T cells, except for Th2 cells, were suppressed in ADS.aureus, particularly circulating Th1, memory IL-10+ T cells, and skin-homing memory Th17 cells. Systemic γδ T cell expansion in ADS.aureus was also observed. This study suggests that augmentation of protective T cell subsets is a potential therapeutic strategy in the management of S. aureus in AD.

Antihistamine and Wound Healing Potential of Gold Nanoparticles Synthesized Using Bulbine frutescens (L.) Willd

Background

Atopic dermatitis (eczema) is an inflammatory skin condition with synthetic treatments that induce adverse effects and are ineffective. One of the proposed causes for the development of the condition is the outside-in hypothesis, which states that eczema is caused by a disruption in the skin barrier. These disruptions include developing dry cracked skin, which promotes the production of histamine. Bulbine frutescens (BF) is traditionally used to treat wounds and eczema; however, limited research has been conducted to scientifically validate this. Furthermore, gold nanoparticles (AuNPs) have been used to repair damaged skin; however, no research has been conducted on AuNPs synthesized using BF.

Purpose

The study aimed to determine whether BF alleviated skin damage through wound healing, reducing the production of histamine and investigate whether AuNPs synthesized using BF would enhance biological activity.

Methods

Four extracts and four synthesized AuNPs were prepared using BF and their antiproliferative and wound healing properties against human keratinocyte cells (HaCaT) were evaluated. Thereafter, the selected samples antiproliferative activity and antihistamine activity against phorbol 12-myristate 13-acetate (PMA) stimulated granulocytes were evaluated.

Results

Of the eight samples, the freeze-dried leaf juice (BFE; p < 0.01) extract and its AuNPs (BFEAuNPs; p < 0.05) displayed significant wound closure at 100 µg/mL and were further evaluated. The selected samples displayed a fifty percent inhibitory concentration (IC50) of >200 µg/mL against PMA stimulated granulocytes. Compared to the untreated (media with PMA) control (0.30 ± 0.02 ng/mL), BFEAuNPs significantly inhibited histamine production at a concentration of 100 (p < 0.01) and 50 µg/mL (p < 0.001).

Conclusion

BFE and BFEAuNPs stimulated wound closure, while BFEAuNPs significantly inhibited histamine production. Further investigation into BFEAuNPs in vivo wound healing activity and whether it can target histamine-associated receptors on mast cells as a potential mechanism of action should be considered.

Moderate to severe atopic dermatitis in children: focus on systemic Th2 cytokine receptor antagonists and Janus kinase inhibitors

Atopic dermatitis (AD) is a lifelong disease that markedly impairs quality of life. AD is considered a starting point of the "atopic march," which begins at a young age and may progress to systemic allergic diseases. Moreover, it is strongly associated with comorbid allergic and inflammatory diseases including arthritis and inflammatory bowel disease. Understanding the pathogenesis of AD is essential for the development of targeted therapies. Epidermal barrier dysfunction, immune deviation toward a T helper 2 proinflammatory profile, and microbiome dysbiosis play important roles via complex interactions. The systemic involvement of type 2 inflammation, wheather acute or chronic, and whether extrinsic or intrinsic, is evident in any type of AD. Studies on AD endotypes with unique biological mechanisms have been conducted according to clinical phenotypes, such as race or age, but the endotype for each phenotype, or endophenotype, has not yet been clearly identified. Therefore, AD is still being treated according to severity rather than endotype. Infancy-onset and severe AD are known risk factors leading to atopic march. In addition, up to 40% of adult AD are cases of infancy-onset AD that persist into adulthood, and these are often accompanied by other allergic diseases. Therefore, early intervention strategies to identify high-risk infants and young children, repair an impaired skin barrier, and control systemic inflamation may improve long-term outcomes in AD patients. However, to the best of our knowledge, no study has evaluated the effectiveness of early intervention on atopic march using systemic therapy in high-risk infants. This narrative review addresses the latest knowledge of systemic treatment, including Th2 cytokine receptor antagonists and Janus kinase inhibitors, for children with moderate to severe AD that is refractory to topical treatment.

A Review of Anti-Inflammatory Phytoconstituents Used in Herbal Cosmeceuticals for the Treatment of Atopic Dermatitis

Skin diseases such as atopic dermatitis affect babies, children, and adults and are characterized by red skin/spots, severe itching that appears on the face, head, legs, neck, and hands, and various causes of illness caused by various external and internal factors. AD is a type IIgE-mediated hypersensitivity reaction. Herbal preparations treat various dermatological diseases like dry skin, melasma, acne, and eczema. Cosmeceuticals are the connection between cosmetics and medicine, one of the world's most used forms of medicine. Cosmeceuticals products are beneficial in treating AD. Herbal cosmetics play a major role in curing various skin diseases. Today, various herbs used in cosmeceuticals have anti-inflammatory, antioxidant, antibacterial, and antiseptic effects. Compared to synthetic preparations, herbal preparations have fewer side effects. This review paper introduces Atopic dermatitis, cosmeceutical, and various phytoconstituents like gallic acid, ferulic acid, boswellic acid, quercetin, and naringenin tetra hydroxyl flavanol glycoside, glycyrrhizic acid, epigallocatechin gallate, etc., used in atopic dermatitis.

Effects of Magnoliae Flos on Atopic Dermatitis-Like Inflammation Evaluated via Extracellular Signal-regulated Kinase or Signal Transducers and Activators of Transcription 1/3 Signalling Pathways

Atopic dermatitis is a chronic inflammatory skin  disease. Skin is the largest organ and plays a pivotal role in protecting the body. Not only does the skin act as a physical barrier against the external environment, but it also has its own immune system. Atopic dermatitis is caused by prolonged excessive inflammatory responses that worsen under imbalanced cutaneous immune system skin conditions. Although the prevalence and burden of atopic dermatitis is increasing, the standard therapeutic agents remain unclear due to  the complicated pathophysiology of the condition. The objective of this study is to examine the use of Magnoliae flos, the dried flower bud of Magnolia biondii or  related plants. The effects and underlying mechanism of  action of aqueous extract of the buds of Magnoliae flos (MF) were evaluated. Immortalized human keratinocytes (HaCaT) stimulated with tumour necrosis factor-α and interferon-γ mixture and NC/Nga mice stimulated with 2,4-dinitrochlorobenzene were used as atopic dermatitis models, in vitro and in vivo, respectively. The effects of MF were determined by measuring the suppression of pro-inflammatory signalling pathways, such as extracellular signal-regulated kinase or signal transducers and activators of transcription 1/3 and restoring skin barrier molecules. In conclusion, MF is a potential therapeutic alternative for the treatment of atopic dermatitis through repressing inflammatory pathways.

Partial Loss of Function ABCA12 Mutations Generate Reduced Deposition of Glucosyl-Ceramide, Leading to Patchy Ichthyosis and Erythrodermia Resembling Erythrokeratodermia Variabilis et Progressiva (EKVP)

Ichthyoses are genetically determined cornification disorders of the epidermis characterized by the presence of different degrees of scaling, hyperkeratosis, and erythroderma often associated with palmoplantar keratoderma. Different classifications of these diseases have been proposed, often based upon the involved genes and/or the clinical presentation. The clinical features of these diseases present some overlap of phenotypes among distinct genetic entities, depending mainly on the penetrance of mutations. In this study, using a clinical, genetic, and molecular approach, we analyzed a family with two affected members who had clinical and histological features resembling erythrokeratodermia variabilis (EKV) or a type of erythrodermic hyperkeratosis with palmoplantar keratoderma. Despite of the clinical presentation, we demonstrated that the affected patients were genetically double heterozygous for two different mutations in the ABCA12 gene, known to be responsible for harlequin ichthyosis. To explain the mild phenotype of our patients, we performed a molecular characterization of the skin. In the upper layers of the epidermis, the results showed a patchy presence of the glucosyl-ceramides (GlcCer), which is the lipid transported by ABCA12, fundamental in contributing to skin impermeability. Indeed, the two mutations detected do not completely abolish ABCA12 activity, indicating that the mild phenotype is due to a partial loss of function of the enzyme, thus giving rise to an intermediate phenotype resembling EKVP, due to a partial depletion of GlcCer deposition.

ZFP750 affects the cutaneous barrier through regulating lipid metabolism

An essential function of the epidermis is to provide a physical barrier that prevents the loss of water. Essential mediators of this barrier function include ceramides, cholesterol, and very long chain fatty acids, and their alteration causes human pathologies, including psoriasis and atopic dermatitis. A frameshift mutation in the human ZNF750 gene, which encodes a zinc finger transcription factor, has been shown to cause a seborrhea-like dermatitis. Here, we show that genetic deletion of the mouse homolog ZFP750 results in loss of epidermal barrier function, which is associated with a substantial reduction of ceramides, nonpolar lipids. The alteration of epidermal lipid homeostasis is directly linked to the transcriptional activity of ZFP750. ZFP750 directly and/or indirectly regulates the expression of crucial enzymes primarily involved in the biosynthesis of ceramides. Overall, our study identifies the transcription factor ZFP750 as a master regulator epidermal homeostasis through lipid biosynthesis and thus contributing to our understanding of the pathogenesis of several human skin diseases.

Prinsepia utilis Royle leaf extract: Ameliorative effects on allergic inflammation and skin lesions in allergic contact dermatitis and polyphenolic profiling through UPLC-MS/MS coupled to chemometric analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Allergic contact dermatitis (ACD) is a common allergic inflammatory disease that is concomitant with skin swelling, redness, dry itching, and relapses. Prinsepia utilis Royle, a Chinese and Indian folk medicine, is rich in polyphenols with potential anti-inflammatory and skin-protective activities. However, the underlying mechanism of P. utilis leaf (PUL) in the treatment of ACD and its functional basis remains unclear.

AIM OF THE STUDY

This study is aimed to explore and reveal the active substances and mechanism of PUL against ACD.

MATERIALS AND METHODS

Hyaluronidase inhibitory assay and fluorescein isothiocyanate (FITC)-induced ACD mouse model were performed to assess the antiallergic effects of PUL in vitro and in vivo. Different solvents were applied to obtain multiple PUL extracts. The extracts were further tested for total phenolic content (TPC) and total flavonoid content (TFC) by using spectrophotometric assays. Polyphenolic profiles were analyzed by using ultrahigh-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-QTOF-MS/MS), and a simultaneous quantification method was established using UPLC-QTrap-MS/MS through multiple reaction monitoring (MRM) and applied to analyze the pharmacokinetics of the multiple major polyphenols of PUL in mice.

RESULTS

The water extract of PUL with the highest TPC/TFC exhibited the strongest antihyaluronidase effect (IC₅₀ = 231.93 μg/mL). In vivo assays indicated that the oral administration of PUL water extract dose-dependently attenuated ACD-like symptoms by decreased interleukin (IL)-4, IL-5, IL-13, IL-33, thymic stromal lymphopoietin, and IgE production, suppressed eosinophil and basophil secretion, and increasing the expression of tight junction (TJ) proteins (claudin-1 [CLDN-1] and occludin). Concomitantly, UPLC-QTOF-MS/MS analysis enabled the identification of 60 polyphenols and the pharmacokinetic parameters of seven quantified constituents of PUL were characterized. Four compounds, trans-p-coumaric acid 4-O-β-D-glucopyranoside (11), vicenin-2 (21), isoschaftoside (31), and kaempferol 3-O-(2″,6″-di-O-α-L-rhamnopyransoyl)-β-D-glucopyranoside (38) which displayed satisfactory pharmacokinetic features, were considered as potential effective substances in PUL.

CONCLUSIONS

PUL water extract ameliorated the allergic inflammation of ACD by repairing the epithelial barrier and alleviating Th2-type allergic inflammation. The anti-allergic effect of PUL is closely related to its phenolic substances, and compounds 11, 21, 31, and 38 were the active substances of PUL. It revealed that P. utilis could be developed as a new source of antiallergic agents for ACD therapy.

Interactions between Malassezia and New Therapeutic Agents in Atopic Dermatitis Affecting Skin Barrier and Inflammation in Recombinant Human Epidermis Model

Several studies have reported the pathogenic role of Malassezia in atopic dermatitis (AD); the significance of Malassezia’s influence on AD needs to be further investigated. Dupilumab, a monoclonal antibody to anti-Interleukin (IL) 4Rα, and ruxolitinib, a Janus kinase (JAK)1/2 inhibitor, are the first approved biologics and inhibitors widely used for AD treatment. In this study, we aimed to investigate how Malassezia Restricta (M. restricta) affects the skin barrier and inflammation in AD and interacts with the AD therapeutic agents ruxolitinib and anti-IL4Rα. To induce an in vitro AD model, a reconstructed human epidermis (RHE) was treated with IL-4 and IL-13. M. restricta was inoculated on the surface of RHE, and anti-IL4Rα or ruxolitinib was supplemented to model treated AD lesions. Histological and molecular analyses were performed. Skin barrier and ceramide-related molecules were downregulated by M. restricta and reverted by anti-IL4Rα and ruxolitinib. Antimicrobial peptides, VEGF, Th2-related, and JAK/STAT pathway molecules were upregulated by M. restricta and suppressed by anti-IL4Rα and ruxolitinib. These findings show that M. restricta aggravated skin barrier function and Th2 inflammation and decreased the efficacy of anti-IL4Rα and ruxolitinib.

New Data on the Features of Skin Barrier in Hidradenitis Suppurativa

Hidradenitis suppurativa (HS) is a Th1/17-driven inflammatory skin disease of the apocrine gland-rich (AGR) skin regions, where keratinocytes seem to be the crucial drivers of the initial pathogenic steps. However, the possible role of permeability barrier alteration in activating keratinocytes during HS development has not been clarified. We compared the major permeability barrier elements of non-lesional HS (HS-NL; n = 10) and lesional HS (HS-L; n = 10) skin with healthy AGR regions (n = 10) via RT-qPCR and immunohistochemistry. Stratum corneum components related to cornified envelope formation, corneocyte desquamation and (corneo)desmosome organization were analyzed along with tight junction molecules and barrier alarmins. The permeability barrier function was also investigated with transepidermal water loss (TEWL) measurements (n = 16). Junction structures were also visualized using confocal microscopy. At the gene level, none of the investigated molecules were significantly altered in HS-NL skin, while 11 molecules changed significantly in HS-L skin versus control. At the protein level, the investigated molecules were similarly expressed in HS-NL and AGR skin. In HS-L skin, only slight changes were detected; however, differences did not show a unidirectional alteration, as KRT1 and KLK5 were detected in decreased levels, and KLK7, KRT6 and DSG1 in increased levels. No significant differences in TEWL or the expression of junction structures were assessed. Our findings suggest that the permeability barrier is not significantly damaged in HS skin and permeability barrier alterations are not the driver factors of keratinocyte activation in this disease.

Skin Microbiome, Metabolome and Skin Phenome, from the Perspectives of Skin as an Ecosystem

Skin is a complex ecosystem colonized by millions of microorganisms, including bacteria, fungi, and viruses. Skin microbiota is believed to exert critical functions in maintaining host skin health. Profiling the structure of skin microbial community is the first step to overview the ecosystem. However, the community composition is highly individualized and extremely complex. To explore the fundamental factors driving the complexity of the ecosystem, namely the selection pressures, we review the present studies on skin microbiome from the perspectives of ecology. This review summarizes the following: (1) the composition of substances/nutrients in the cutaneous ecological environment that are derived from the host and the environment, highlighting their proposed function on skin microbiota; (2) the features of dominant skin commensals to occupy ecological niches, through self-adaptation and microbe-microbe interactions; (3) how skin microbes, by their structures or bioactive molecules, reshape host skin phenotypes, including skin immunity, maintenance of skin physiology such as pH and hydration, ultraviolet (UV) protection, odor production, and wound healing. This review aims to re-examine the host-microbe interactions from the ecological perspectives and hopefully to give new inspiration to this field.

Natural products in cosmetics

The global cosmetics market reached US$500 billion in 2017 and is expected to exceed US$800 billion by 2023, at around a 7% annual growth rate. The cosmetics industry is emerging as one of the fastest-growing industries of the past decade. Data shows that the Chinese cosmetics market was US$60 billion in 2021. It is expected to be the world's number one consumer cosmetics market by 2050, with a size of approximately US$450 billion. The influence of social media and the internet has raised awareness of the risks associated with the usage of many chemicals in cosmetics and the health benefits of natural products derived from plants and other natural resources. As a result, the cosmetic industry is now paying more attention to natural products. The present review focus on the possible applications of natural products from various biological sources in skin care cosmetics, including topical care products, fragrances, moisturizers, UV protective, and anti-wrinkle products. In addition, the mechanisms of targets for evaluation of active ingredients in cosmetics and the possible benefits of these bioactive compounds in rejuvenation and health, and their potential role in cosmetics are also discussed.

Effects of Oral Administration of Lactiplantibacillus Plantarum APsulloc 331261 (GTB1TM) Isolated from Green Tea on Atopic Dermatitis (AD)-like Skin Lesion Mouse Models

Background

Probiotics are known to improve atopic dermatitis (AD) by inhibiting T helper 2 (Th2)-related reactions, restoring the Th2/T helper1 (Th1) cytokine ratio. The most popular probiotic is Lactiplantibacillus plantarum (L. plantarum), which is widely used in the food and pharmaceutical industries. L. plantarum APsulloc 331261 (GTB1) used in this study was isolated from green tea.

Materials and Methods

The effectiveness of oral GTB1 administration in improving AD was evaluated by visual evaluation, comparison of the lymph node sizes and spleen weights, histological evaluation, RT-qPCR, ELISA, and IHC analysis in the mouse model.

Results

GTB1 improved AD symptoms, reduced epidermal thickness and mast cell numbers, decreased lymph node size and the spleen weight, increased filaggrin and loricrin protein levels, downregulated Th2 expression, and upregulated Th1 expression in a colony-forming unit-dependent manner.

Conclusion

Oral administration of GTB1 isolated from green tea (Camellia sinensis) improved the AD symptoms, reduced hypersensitivity reaction, and increased the skin barrier function. Finally, it is involved in AD improvement by restoring the Th2/Th1 cytokine balance.

Dissolvable Microneedle Patch Increases the Therapeutic Effect of Jawoongo on DNCB-Induced Atopic Dermatitis in Mice

BACKGROUND

Jawoongo (JW) is a topical herbal ointment that has been used as an alternative treatment option for atopic dermatitis. Topical ointments are known to have less bioavailability because the stratum corneum allows only lipophilic and low molecular weight drugs to pass across it. This study aimed to investigate whether applying microneedle patches (MNP) increases the therapeutic effect of 2,4-dinitrochlorobenzene (DNCB)+JW for atopic dermatitis by enhancing transdermal delivery.

METHODS

Atopic dermatitis was induced by DNCB in BALB/c mice. The combination treatment of JW and MNP was estimated to study the effect of MNP in improving transdermal delivery. Histological analysis, quantitative real-time PCR (qPCR), and immunofluorescence were performed to verify the effect of MNP in enhancing the therapeutic effects of DNCB+JW on atopic dermatitis in mice.

RESULTS

Both combination treatment and DNCB+JW treatment ameliorated histological alterations and reduced skin thickness and infiltration of CD4+ T cells in atopic dermatitis-like skin lesions in DNCB-exposed BALB/c mice. However, the improvement of histological alterations was better in the combination treatment, which was almost normal. Furthermore, the combination treatment exhibited a larger decrease in mRNA levels of IL-4, IL-6, IL-13, iNOS, and TNF-α, compared to DNCB+JW only. In addition, skin thickness and infiltration of CD4+ T cells in the sensitized skin were significantly lower using the combination treatment than using DNCB+JW only.

CONCLUSION

Combination treatment with JW and MNP further decreased skin thickness and several inflammatory cytokines in atopic dermatitis like skin lesions compared to treatment using JW alone. These findings suggest that applying a dissolvable MNP after JW application could be useful for treating atopic dermatitis.

Atopic dermatitis: molecular, cellular, and clinical aspects

Atopic dermatitis (AD) is a complicated, inflammatory skin disease, which numerous genetic and environmental factors play roles in its development. AD is categorized into different phenotypes and stages, although they are mostly similar in their pathophysiological aspects. Immune response alterations and structural distortions of the skin-barrier layer are evident in AD patients. Genetic makeup, lifestyle, and environment are also significantly involved in contextual factors. Genes involved in AD-susceptibility, including filaggrin and natural moisturizing, cause considerable structural modifications in the skin's lipid bilayer and cornified envelope. Additionally, the skin's decreased integrity and altered structure are accompanied by biochemical changes in the normal skin microflora's dysbiosis. The dynamic immunological responses, genetic susceptibilities, and structural modifications associated with AD's pathophysiology will be extensively discussed in this review, each according to the latest achievements and findings.

Osthole Inhibits Expression of Genes Associated with Toll-like Receptor 2 Signaling Pathway in an Organotypic 3D Skin Model of Human Epidermis with Atopic Dermatitis

The Toll-like receptor (TLR) family signature has been linked to the etiopathology of atopic dermatitis (AD), a chronic inflammatory skin disease associated with skin barrier dysfunction and immune system imbalance. We aimed to investigate whether osthole (a plant-derived compound) can inhibit the genetic profile of key genes associated with TLR2 signaling (TIRAP, MyD88, IRAK1, TRAF6, IκBα, NFκB) after stimulation with LPS or histamine in a 3D in vitro model of AD. Overexpression of the aforementioned genes may directly increase the secretion of proinflammatory cytokines (CKs) and chemokines (ChKs), which may exacerbate the symptoms of AD. Relative gene expressions were quantified by qPCR and secretion of CKs and ChKs was evaluated by ELISA assay. LPS and histamine increased the relative expression of genes related to the TLR2 pathway, and osthole successfully reduced it. In summary, our results show that osthole inhibits the expression of genes associated with the TLR signaling pathway in a skin model of AD. Moreover, the secretion of CKs and ChKs after treatment of AD with osthole in a 3D skin model in vitro suggests the potential of osthole as a novel compound for the treatment of AD.

Either transepidermal water loss rates or stratum corneum hydration levels can predict quality of life in children with atopic dermatitis

IMPORTANCE

Patients with atopic dermatitis (AD) display compromised epidermal barrier and suffer from poor quality of life. We hypothesized that quality of life could reflect in the changes in the epidermal barrier function.

OBJECTIVE

To determine whether the epidermal barrier function correlates with the severity of pruritus and/or life quality in children with AD.

METHODS

A total of 120 children, aged 0-12 years, with moderate AD were enrolled. Children were topically treated with topical corticosteroids (TCS) and an emollient for 2 weeks. The Eczema Area and Severity Index (EASI), visual analogue scale (VAS) for pruritus severity, the Infant's Dermatitis Quality of Life Index (IDQOL) and the Children's Dermatology Life Quality Index (CDLQI) were evaluated. Transepidermal water loss (TEWL) rates, stratum corneum (SC) hydration, and skin surface pH were measured. Correlations of epidermal barrier function with pruritus, life quality, and EASI were determined.

RESULTS

Following 2-week treatments, significant improvements were observed in EASI, TEWL, SC hydration, the VAS of pruritus, as well as DQOL (P < 0.001 for all). TEWL positively, while SC hydration negatively correlated with VAS pruritus, DQOL, and EASI (P < 0.001).

INTERPRETATION

Both TEWL and SC hydration levels can serve as indicators of the severity of pruritus and quality of life in children with AD.

Sarsasapogenin and fluticasone combination improves DNFB induced atopic dermatitis lesions in BALB/c mice

OBJECTIVE

Atopic dermatitis (AD) is a pruritic, chronic, relapsing inflammatory skin disease. The research aims to study the effects of Sarsasapogenin and its combination with Fluticasone in 2, 4-Dinitrofluorobenzene (DNFB) induced atopic dermatitis in BALB/c mice.

MATERIAL AND METHODS

Thirty male Balb/c mice were divided into 5 groups: (i) Normal control (NC), (ii) Disease control (DNFB), (iii) Sarsasapogenin (SG) (50 µg/mice), (iv) Fluticasone (FC) (50 µg/mice), (v) Sarsasapogenin + Fluticasone (SG + FC) combination (25 µg/mice). Dermatitis was induced by repeated application of DNFB in Balb/c mice. On topical application of SG, FC, and SG + FC combination on the ear and skin lesions, body weight, ear weight, ear thickness, erythema score, spleen weight, cytokines, immunoglobulin E (IgE) levels, nitric oxide (NO) level, hematological parameters, and oxidative stress markers were evaluated. Histological analysis of the ear tissue was also done.

RESULTS

The results stated that SG and SG + FC treatment to mice considerably decrease the ear weight, ear thickness, spleen weight, serum IgE, cytokines, NO levels, and restoration of antioxidant stress markers with elevation in the hematological parameters. The observations were further confirmed by histopathological analysis of ear tissue.

CONCLUSION

These data specify that SG has been demonstrated as a probable therapy for the treatment of allergic skin diseases in combination with FC by decreasing its dose from 50 to 25 µg/mice to avoid the chronic side effects of FC. Hence, it can be concluded that SG and SG + FC combination significantly improved the AD-like symptoms in the DNFB sensitized mice through mitigating the production of proinflammatory mediators and restoration of oxidative stress markers.

Current Insights into Immunology and Novel Therapeutics of Atopic Dermatitis

Atopic dermatitis (AD) is one of the most prevalent inflammatory disease among non-fatal skin diseases, affecting up to one fifth of the population in developed countries. AD is characterized by recurrent pruritic and localized eczema with seasonal fluctuations. AD initializes the phenomenon of atopic march, during which infant AD patients are predisposed to progressive secondary allergies such as allergic rhinitis, asthma, and food allergies. The pathophysiology of AD is complex; onset of the disease is caused by several factors, including strong genetic predisposition, disrupted epidermal barrier, and immune dysregulation. AD was initially characterized by defects in the innate immune system and a vigorous skewed adaptive Th2 response to environmental agents; there are compelling evidences that the disorder involves multiple immune pathways. Symptomatic palliative treatment is the only strategy to manage the disease and restore skin integrity. Researchers are trying to more precisely define the contribution of different AD genotypes and elucidate the role of various immune axes. In this review, we have summarized the current knowledge about the roles of innate and adaptive immune responsive cells in AD. In addition, current and novel treatment strategies for the management of AD are comprehensively described, including some ongoing clinical trials and promising therapeutic agents. This information will provide an asset towards identifying personalized targets for better therapeutic outcomes.

Effects of mineral complex material treatment on 2,4- dinitrochlorobenzene-induced atopic dermatitis like-skin lesions in mice model

Background

Atopic dermatitis (AD) is a chronic allergic inflammatory skin disease characterized by complex pathogenesis including skin barrier dysfunction, immune-redox disturbances, and pruritus. Prolonged topical treatment with medications such as corticosteroids, calcineurin inhibitors, and T-cell inhibitors may have some potential side-effects. To this end, many researchers have explored numerous alternative therapies using natural products and mineral compounds with antioxidant or immunomodulatory effects to minimize toxicity and adverse-effects. In the current study, we investigated the effects of mineral complex material (MCM) treatment on 2, 4-dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in SKH-1 hairless mice.

Methods

Animals were divided into four groups; normal control (NC), negative control treated with DNCB only (DNCB only), positive control treated with DNCB and tacrolimus ointment (PC) and experimental group treated with DNCB and MCM patch (MCM). Skin inflammation and lesion severity were investigated through analyses of skin parameters (barrier score and strength, moisture and trans-epidermal water loss level), histopathology, immunoglobulin E, and cytokines. In addition, reactive oxygen species (ROS), nitric oxide (NO), glutathione peroxidase (GPx), and catalase (CAT) levels were measured in both serum and skin lysate.

Results

Our results demonstrates that MCM patch improved the progression of AD-like skin lesions by significantly increasing skin barrier strength and decreasing trans-epidermal water loss. Additionally, dermal administration of MCM patch significantly reduced epidermal thickness, ROS, and NO levels in skin lysate. Furthermore, we found that MCM suppressed the levels of AD-involved (Th₁ and Th₂) cytokines such as IL-2, IFN-γ, and IL-4 in blood. In addition, the levels of other Th_1, and Th₂ and inflammatory cytokines such as IL-1β, TNF-α, IL-6, IL-12(p70) and IL-10 were found lowest in the MCM group than in the DNCB only and PC groups. Moreover, we found total serum IgE level significantly increased after DNCB treatment, but decreased in the PC and MCM groups.

Conclusion

Taken together, our findings suggest that MCM application may have beneficial effects either systemic or regional on DNCB-induced AD lesional skin via regulation of the skin barrier function and immune-redox response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12906-021-03259-5.

Impressic Acid Ameliorates Atopic Dermatitis-Like Skin Lesions by Inhibiting ERK1/2-Mediated Phosphorylation of NF-κB and STAT1

Impressic acid (IPA), a lupane-type triterpenoid from Acanthopanax koreanum, has many pharmacological activities, including the attenuation of vascular endothelium dysfunction, cartilage destruction, and inflammatory diseases, but its influence on atopic dermatitis (AD)-like skin lesions is unknown. Therefore, we investigated the suppressive effect of IPA on 2,4-dinitrochlorobenzene (DNCB)-induced AD-like skin symptoms in mice and the underlying mechanisms in cells. IPA attenuated the DNCB-induced increase in the serum concentrations of IgE and thymic stromal lymphopoietin (TSLP), and in the mRNA levels of thymus and activation regulated chemokine (TARC), macrophage derived chemokine (MDC), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-13 (IL-13), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) in mice. Histopathological analysis showed that IPA reduced the epidermal/dermal thickness and inflammatory and mast cell infiltration of ear tissue. In addition, IPA attenuated the phosphorylation of NF-κB and IκBα, and the degradation of IκBα in ear lesions. Furthermore, IPA treatment suppressed TNF-α/IFN-γ-induced TARC expression by inhibiting the NF-κB activation in cells. Phosphorylation of extracellular signal-regulated protein kinase (ERK1/2) and the signal transducer and activator of transcription 1 (STAT1), the upstream signaling proteins, was reduced by IPA treatment in HaCaT cells. In conclusion, IPA ameliorated AD-like skin symptoms by regulating cytokine and chemokine production and so has therapeutic potential for AD-like skin lesions.

Derma-Hc, a New Developed Herbal Formula, Ameliorates Cutaneous Lichenification in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic cutaneous disorder that is characterized by severe eczematous inflammation, swelling, and lichenification. Activation of T helper (Th)-22 cells by allergens leads to epidermal hyperplasia with hyperkeratosis at the chronic phase of AD. Derma-Hc is composed of five natural herbs with anti-AD effects, such as Astragalus membranaceus BUNGE, Schizonepeta tenuifolia Briq., Cryptotympana pustulata Fabr., Angelica sinensis Diels, Arctium lappa L. In this study, the ameliorative effect of Derma-Hc on cutaneous lichenification in 2,4-dinitrochlorobenzne (DNCB)-induced AD was investigated. The dorsal skin of mice was sensitized with DNCB to induce AD-like skin lesions. The dermatitis score and frequency of scratching were evaluated. Thickness of epidermis and dermis was measured by staining with H&E. In addition, infiltration of the mast cell was observed by staining with toluidine blue. Then, desmosomal cadherin, DSC1 was examined by immunofluorescence. Pathological mechanisms involved in lichenification were analyzed in AD-like skin lesions and TNF-α + IFN-γ-treated with human keratinocytes including keratinocyte differentiation genes and JAK1-STAT3 signaling pathway with IL-22 by RT-PCR and western blotting. Topical treatment of Derma-Hc improved AD-like symptoms such as dryness, edema and lichenefication and decreased the number of scratches. Histopathological analysis demonstrated that Derma-Hc significantly inhibited epidermal hyperplasia, hyperkeratosis, and mast cells infiltration. In addition, the level of DSC1 was highly expressed in the epidermis by Derma-Hc. Moreover, mRNA expression level of FLG, an epidermal differentiation complex gene, was recovered by Derma-Hc treatment. KLK5 and KLK7 were markedly reduced to normalize keratinocyte differentiation in dorsal skin tissues and human keratinocytes. On the other hand, Derma-Hc restored expression level of SPINK5. In addition, Derma-Hc inhibited IL-22 via the blockade of JAK1-STAT3 signal pathway. Taken together, Derma-Hc, a natural herbal formula, regulated keratinocyte differentiation and inhibited epidermal hyperplasia with hyperkeratosis. Therefore, Derma-Hc could be a promising candidate for treating chronic AD through modulating signaling of IL-22-associated skin lichenification.

Poly-γ-Glutamate microneedles as transdermal immunomodulators for ameliorating atopic dermatitis-like skin lesions in Nc/Nga mice

Atopic dermatitis (AD), a common, relapsing, inflammatory disorder of the skin, is associated with T helper type 2 (Th2)-biased immune responses. Despite the efficacy of existing drugs for AD treatment, their safety and side effects cause concern. The present study describes the use of dissolvable poly-γ-glutamate (γ-PGA) microneedles (MNs) with immunomodulatory effects for effectively relieving AD-like symptoms in Nc/Nga mice. γ-PGA MNs can easily penetrate the epidermis and release γ-PGA into the dendritic cell-rich dermis to interact with dendritic cells for modulating immune responses. Transdermal administration of high-molecular-weight (HMW, 1100 kDa) γ-PGA MNs significantly reduced clinical dermatitis scores, epidermal thickness, and mast cell infiltration in mice by downregulating immunoglobulin (Ig)E and IgG1 levels (Th2-associated antibodies) compared with the AD control group. However, low-molecular-weight (200-400 kDa) γ-PGA MNs ameliorated AD-like skin lesions less effectively than HMW γ-PGA MNs, thus indicating that the MW of γ-PGA may affect its immunomodulatory properties. Notably, the mouse skin quickly recovered its barrier function within 4 h after MN application. No weight loss or abnormality was observed in the MN-treated mice during the 8-week treatment period. These results suggest that the γ-PGA MNs represent an innovative, safe, and reliable therapeutic strategy for AD management. STATEMENT OF SIGNIFICANCE: This study is the first to explore the feasibility of using poly-γ-glutamate (γ-PGA) microneedles (MNs) as transdermal immunomodulators for improving atopic dermatitis (AD) symptoms and to evaluate their immunomodulatory effect in mice with spontaneously developed AD. Transdermal administration of γ-PGA MNs enables the γ-PGA to localize in the skin for activation of dermal dendritic cells, thus modulating immune responses. We demonstrate that high-molecular-weight γ-PGA MNs can be retained in the skin for at least 6 days and effectively suppress AD-like skin lesions in mice by reducing infiltration of mast cells and downregulating Th2-associated antibody production (IgE and IgG1). The developed MN device has the potential to replace conventional therapy and to become an innovative treatment strategy for AD.

Carbon dioxide ameliorates reduced desquamation in dry scaly skin via protease activation

OBJECTIVE

Scaling, a phenomenon showing an abnormal detachment of the stratum corneum (SC) owing to desquamation dysfunction, is commonly observed in various skin diseases or xerotic skin due to ageing and low humidity. Therefore, it is considered that ameliorating the disturbed desquamatory process of the SC leads to improvement in scaling. Carbon dioxide (CO₂ ) is known to be good for some skin diseases; however, the effect of CO₂ on scaling and its mechanism are not sufficiently clear. We aimed to elucidate the effect of transepidermal application of CO₂ on scaling and its mechanism of action.

METHODS

Twenty healthy men with mild scaling on the cheeks were recruited for a double-blind, placebo-controlled, split-face study. They applied the formulation containing CO₂ twice daily for 1 week. After the study, the SC was collected by tape stripping to analyse desquamatory protease activities and degradation of extracellular corneodesmosomes. Furthermore, the contribution of pH to proteolysis of the corneodesmosome by CO₂ was evaluated using three-dimensional (3D) cultured epidermal models.

RESULTS

The spectroscopic absorbance of tape strips, used as scaling indicators, was decreased, concomitantly with the amelioration of incomplete degradation of desmoglein-1, one of the main corneodesmosomal proteins, and activation of trypsin-like protease in the SC by transepidermal application of CO₂ . Experiments using 3D cultured epidermis showed that pH in the epidermal tissue was lowered by CO₂ , whereas a pH change was not observed with the application of the formulation containing hydrochloric acid, which was added to equalize the pH to that of the CO₂ formulation.

CONCLUSION

The transcutaneous application of CO₂ ameliorates reduced desquamatory process in xerotic skin, with concomitant mild acidification of the SC, thereby leading to improvement in scaling. Thus, CO₂ may have an advantage of efficiently and safely counteracting scaling of various skin disorders.

A Phytocomplex Consisting of Tropaeolum majus L. and Salvia officinalis L. Extracts Alleviates the Inflammatory Response of Dermal Fibroblasts to Bacterial Lipopolysaccharides

Background

The antimicrobial activity and effects of a phytocomplex consisting of Tropaeolum flos (T) and Salviae folium (S) extracts on the cytokine levels and transcription factors on dermal fibroblast BJ exposed to bacterial lipopolysaccharides were examined.

Methods

In order to select the most optimal combination ratio of the two extracts for using in vitro, the physicochemical characterization of vegetal extract mixtures was performed and the antioxidant and antibacterial activities were evaluated on five different formulations of T : S, namely, 1 : 1, 1 : 2, 2 : 1, 3 : 1, and 1 : 3. The best combination of bioactive compounds with regard to antioxidant and antibacterial activities (T : S 1 : 2) was selected for in vitro evaluation of the anti-inflammatory effect. Human dermal fibroblast BJ cells were treated with two doses of the extract mixture and then exposed to bacterial lipopolysaccharides (LPS). The levels of the cytokines involved in inflammatory response, namely, interleukin- (IL-) 6, tumor necrosis factor- (TNF-) α, IL-31, and IL-33, were quantified by ELISA, and the expression of transcription factors, namely, signal transducer and activator of transcription (STAT) 3, nuclear factor kappa B (NFκB), and phosphorylated NFκB (pNFκB), were evaluated by western blot analysis.

Results

The results have shown that the mixture of T : S 1 : 2 exhibited significant antibacterial effects on Staphylococcus aureus ATCC 25923. LPS exposure increased the cytokine levels in BJ cells and enhanced the NFκB expression. The pretreatment of BF cells exposed to LPS with the two doses of the extract mixture markedly inhibited the increase of IL-33 and TNF-α levels and amplified the NFκB expression and its activation, especially with the high dose. The low doses of the extract reduced NFκB expression but increased its activation.

Conclusions

These experimental findings suggest that the mixture of T : S 1 : 2 can exert some protection against bacterial infections and inflammation induced by LPS in BJ cells being a good therapeutic option in related conditions associated with inflammation.

Knockdown of sodium channel Nax reduces dermatitis symptoms in rabbit skin

The skin plays a critical role in maintenance of water homeostasis. Dysfunction of the skin barrier causes not only delayed wound healing and hypertrophic scarring, but it also contributes to the development of various skin diseases. Dermatitis is a chronic inflammatory skin disorder that has several different subtypes. Skin of contact dermatitis and atopic dermatitis (AD) show epidermal barrier dysfunction. Na_x is a sodium channel that regulates inflammatory gene expression in response to perturbation of barrier function of the skin. We found that in vivo knockdown of Na_x using RNAi reduced hyperkeratosis and keratinocyte hyperproliferation in rabbit ear dermatitic skin. Increased infiltration of inflammatory cells (mast cells, eosinophils, T cells, and macrophages), a characteristic of dermatitis, was reduced by Na_x knockdown. Upregulation of PAR-2 and thymic stromal lymphopoietin (TSLP), which induce Th2-mediated allergic responses, was inhibited by Na_x knockdown. In addition, expression of COX-2, IL-1β, IL-8, and S100A9, which are downstream genes of Na_x and are involved in dermatitis pathogenesis, were also decreased by Na_x knockdown. Our data show that knockdown of Na_x relieved dermatitis symptoms in vivo and indicate that Na_x is a novel therapeutic target for dermatitis, which currently has limited therapeutic options.

The innate immune perspective of autoimmune and autoinflammatory conditions

Innate immunity is one of two immune defence system arms. It is present at birth and does not require 'learning' through exposure to foreign organisms. It activates various mechanisms collectively to eliminate pathogens and hold an infection until the adaptive response are mounted. The innate immune system consists of four elements: the epithelial barrier, cells (e.g. macrophages, NK cells), plasma proteins (e.g. complement) and cytokines. These components act in concert to induce complex processes, as well as recruitment, activation and differentiation of adaptive responses. The innate response is more than just the 'first line of defence', as it essentially withholds the vast majority of any intruder, has a complex interplay with the adaptive arm and is crucial for survival of the host. Finally, yet importantly, a myriad of diseases has been linked with innate immune dysregulation. In this mini-review we will shed some light on these conditions, particularly regarding autoinflammatory ones.

Treatment with Docosahexaenoic Acid Improves Epidermal Keratinocyte Differentiation and Ameliorates Inflammation in Human Keratinocytes and Reconstructed Human Epidermis Models

Atopic dermatitis (AD) is a chronic inflammatory skin disease that can cause skin barrier function damage. Although co-incubation with docosahexaenoic acid (DHA) exerts a positive effect on deficient skin models, no studies have investigated the effects of topical treatment with DHA in an inflammatory reconstructed human epidermis (RHE) model. The effects of DHA on monolayer normal human epidermal keratinocyte (NHEK) cells were evaluated using cell counting kit-8 (CCK-8), real-time quantitative polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay (ELISA). The skin-related barrier function was assessed using hematoxylin–eosin (HE) staining, Western blot (WB), immunohistofluorescence (IF), and ELISA in normal and inflammatory RHE models. Docosahexaenoic acid upregulated filaggrin and loricrin expression at mRNA levels in addition to suppressing overexpression of tumor necrosis factor-α (TNF-α), interleukin-α (IL-1α), and interleukin-6 (IL-6) stimulated by polyinosinic–polycytidylic acid (poly I:C) plus lipopolysaccharide (LPS) (stimulation cocktail) in cultured NHEK cells. After topical treatment with DHA, cocktail-induced inflammatory characteristics of skin diseases, including barrier morphology, differentiation proteins, and thymic stromal lymphopoietin (TSLP) secretion, were alleviated in RHE models. Supplementation with DHA can improve related barrier function and have anti-inflammation effects in monolayer keratinocytes and RHE models, which indicates that DHA may have potential value for the treatment of inflammation-associated skin diseases.

Childhood atopic dermatitis: current developments, treatment approaches, and future expectations

Atopic dermatitis (AD) is the most common chronic inflammatory skin disorder of childhood. Underlying factors that contribute to AD are impaired epithelial barrier, alterations in the lipid composition of the skin, immunological imbalance including increased Th2/Th1 ratio, proinflammatory cytokines, decreased T regulatory cells, genetic mutations, and epigenetic alterations. Atopic dermatitis is a multifactorial disease with a particularly complicated pathophysiology. Discoveries to date may be considered the tip of the iceberg, and the increasing number of studies in this field indicate that there are many points to be elucidated in AD pathophysiology. In this review, we aimed to illustrate the current understanding of the underlying pathogenic mechanisms in AD, to evaluate available treatment options with a focus on recently discovered therapeutic agents, and to determine the personal, familial, and economic burdens of the disease, which are frequently neglected issues in AD. Currently available therapies only provide transient solutions and cannot fully cure the disease. However, advances in the understanding of the pathogenic mechanisms of the disease have led to the production of new treatment options, while ongoing drug trials also have had promising results.

Potential Therapeutic Applications of Bee Venom on Skin Disease and Its Mechanisms: A Literature Review

Skin is larger than any other organ in humans. Like other organs, various bacterial, viral, and inflammatory diseases, as well as cancer, affect the skin. Skin diseases like acne, atopic dermatitis, and psoriasis often reduce the quality of life seriously. Therefore, effective treatment of skin disorders is important despite them not being life-threatening. Conventional medicines for skin diseases include corticosteroids and antimicrobial drugs, which are effective in treating many inflammatory and infectious skin diseases; however, there are growing concerns about the side effects of these therapies, especially during long-term use in relapsing or intractable diseases. Hence, many researchers are trying to develop alternative treatments, especially from natural sources, to resolve these limitations. Bee venom (BV) is an attractive candidate because many experimental and clinical reports show that BV exhibits anti-inflammatory, anti-apoptotic, anti-fibrotic, antibacterial, antiviral, antifungal, and anticancer effects. Here, we review the therapeutic applications of BV in skin diseases, including acne, alopecia, atopic dermatitis, melanoma, morphea, photoaging, psoriasis, wounds, wrinkles, and vitiligo. Moreover, we explore the therapeutic mechanisms of BV in the treatment of skin diseases and killing effects of BV on skin disease-causing pathogens, including bacteria, fungi and viruses.

Safety and efficacy of hydroxytyrosol-based formulation on skin inflammation: in vitro evaluation on reconstructed human epidermis model

BACKGROUND

Atopic dermatitis is a multifactorial immune-mediated skin disorder characterized by an alteration of epidermal barrier function and onset of skin lesions, which range from mild erythema to severe lichenification. Treatment consists in hydration with possible use of topical or immunomodulatory corticosteroids, which, however sometimes showed side effects. Recently, the interest in natural compounds has grown significantly and among these, hydroxytyrosol (HT) plays a pivotal role due to its strong and well-known anti-inflammatory activity.

OBJECTIVES

The aim of this study was to investigate the safety and efficacy of Fenolia® Eudermal Cream 15 (HT-based formulation) on epidermal barrier impaired as consequence of skin injury.

METHODS

Whit this purpose, morphologic and structural as well as anti-inflammatory evaluations, after treatment with pro-inflammatory mediators (PBS 1 X and LPS) and HT-based formulation on reconstructed human epidermis (RHE) were carried out by qualitative (hematoxylin/eosin- and immunostaining) and quantitative (MTT assay, IL-1α and IL-8 release by ELISA) techniques. Furthermore, HT absorption through the epidermal barrier was evaluated by RP-LC-DAD analysis.

RESULTS

A rise in the thickness of the epidermis as well as an appropriate maturation and protein expression (Loricrin, Fillagrin, E-Cadherin and Cytokeratins 5&6) were detected in treated RHE samples. In particular, the HT-based formulation was found to stimulate cell proliferation, as evidenced by the significant increase in Ki67 expression, which suggests the involvement of repair mechanisms, increasing epithelial regeneration and differentiation and improving the epidermal barrier effect. Furthermore, HT-based formulation showed a statistically significant anti-inflammatory activity by reducing both IL-1α and IL-8 release by RHE tissues, greater than the reference drug dexamethasone. Finally, excellent transcutaneous absorption values were found for HT, demonstrating how this new formulation increases the availability of the bioactive compound.

CONCLUSIONS

In light of these results, Fenolia® Eudermal Cream 15 could be an effective agent to counteract atopic dermatitis. Graphical abstract Safety and efficacy of hydroxytyrosol-based formulation on skin inflammation: in vitro evaluation on reconstructed human epidermis model.

Biophysical and ultrasonographic changes in lichen planus compared with uninvolved skin

BACKGROUND

Lichen planus (LP) is a chronic inflammatory disease of the skin. Currently, noninvasive techniques are used to evaluate biophysical properties of the skin in vivo.

OBJECTIVE

In this study, we aimed to evaluate skin biophysical properties in patients with LP and make a comparison between involved and uninvolved skin to provide a better understanding of the pathogenesis of LP.

METHODS

The stratum corneum hydration, transepidermal water loss, pH, erythema, melanin, sebum, friction, temperature, elasticity parameters (R0, R2, R5), and thickness and echo-density of the epidermis, dermis, and subepidermal low echogenic band were measured on lesions of classic LP in 21 patients and compared with the average of perilesional and symmetrical uninvolved skin (as control) with a paired t test.

RESULTS

Stratum corneum hydration (p = .002), sebum (p = .04), R0 (p = .005), and echo-density of the dermis (p = .005) were significantly lower, but pH (p = .007), melanin content (p < .001), erythema (p < .001), temperature (p = .01), thickness of dermis (p = .02), and subepidermal low echogenic band (p < .001) were significantly higher in LP lesions.

CONCLUSION

An evaluation of its biophysical, biomechanical, and ultrasonographic characteristics showed that the skin is an objective, noninvasive, and quantitative measuring tool that can be used to provide valuable information about skin changes in classic LP.

Effect of Topically Applied Wikstroemia dolichantha Diels on the Development of Atopic Dermatitis-Like Skin Symptoms in Mice

Plants of the genus Wikstroemia are traditionally used to treat inflammatory diseases like bronchitis and rheumatoid arthritis. In the present study, the anti-atopic effects of an EtOH extract of Wikstroemia dolichantha (WDE) on oxazolone- and DNCB (2,4-dinitrochlorobenzene)-induced dermatitis in mice were investigated. Both ears of BALB/c mice were exposed to oxazolone, and dorsal skins of SKH-1 hairless mice were sensitized with DNCB to induce acute eczematous atopic skin lesions. 1% WDE was applied daily to oxazolone- and DNCB-induced AD mice for two or three weeks, respectively. Total IL-4 and IgE concentrations in serum, transepidermal water loss (TEWL) and skin hydration were assessed. High-performance liquid chromatography/mass spectrometry (HPLC/MS) was used to determine the composition of WDE. Dermal application of 1% WDE grossly and histopathologically improved oxazolone- and DNCB-induced AD skin symptoms. Epidermal thickness and mast cell infiltration were significantly lower in animals treated with WDE than in vehicle controls. Furthermore, in addition to reducing DNCB-induced increases in serum IL-4 (interleukin 4) and IgE (immunoglobulin E) levels, WDE also decreased TEWL and increased skin hydration (indicative of improved skin barrier function). The four flavonoids taxifolin, aromadendrin, padmatin and chamaejasmine were tentatively identified in WDE by HPLC-DAD/QTOF-MS. The above results show WDE protected against oxazolone- and DNCB-induced AD in mice by down-regulating the T_H2-associated cytokine IL-4 and improving skin barrier function and suggest WDE might be useful for the management of atopic dermatitis.

Multifunctional chitosan-coated poly(lactic-co-glycolic acid) nanoparticles for spatiotemporally controlled codelivery of ceramide and C-phycocyanin to treat atopic dermatitis

Atopic dermatitis is an inflammatory disease associated with defective skin barrier. The co-administration of a lipid-enhancing skin barrier composed of ceramide with an anti-inflammatory agent is required to effectively treat atopic dermatitis. As atopic dermatitis treatment is affected by the dosage and frequency of medication, the development of nanoparticles that have long-term efficacy with a single dose would be advantageous. In this study, skin-sensitive chitosan nanoparticles codelivering ceramide and C-phycocyanin were developed to provide anti-inflammatory effects with no cytotoxicity, and their effect on stratum corneum formation in a rat atopic dermatitis model was examined. Analysis of the messenger RNA expression of keratinization factors demonstrated that the stratum corneum–formation effect of poly(lactic-co-glycolic acid) nanoparticles containing ceramide was similar to or higher than that of ceramide alone. Compared to the nanoparticles without C-phycocyanin, nanoparticles coated with C-phycocyanin and chitosan attenuated histamine release. In addition, despite frequent washing, the nanoparticles were well fixed to the epidermis after their administration. The results suggest that a single treatment with the combination of lipid therapy/anti-inflammatory nanoparticles is a convenient and high-efficiency means to increase stratum corneum formation in atopic dermatitis patients.

Biophysical Measurements and Ultrasonographic Findings in Chronic Dermatitis in Comparison with Uninvolved Skin

Background:

Nowadays noninvasive techniques are performed to evaluate the biophysical properties of skin in vivo.

Aims:

The aim of this study was to evaluate the biophysical and ultrasonographic properties of skin in chronic contact or atopic dermatitis to provide better insight into pathogenesis, diagnosis, and treatment response.

Materials and Methods:

The stratum corneum hydration, transepidermal water loss (TEWL), pH, erythema, melanin, sebum, friction, temperature, elasticity parameters (R0, R2, and R5), the thickness and echo-density of epidermis, dermis, and subepidermal low-echogenic band (SLEB) were measured on lesional, perilesional, and symmetrical skin of 22 chronic dermatitis patients. The average of perilesional and symmetrical skin values (control) was compared with lesional values.

Results:

Stratum corneum hydration (P<0.001), friction (P=0.02), sebum (P=0.01), and R0 (P<0.001) were significantly lower in lesion, TEWL (P=0.03), pH (P=0.001), erythema (P=0.004), and temperature (P=0.04) were significantly higher in lesion. The thickness of epidermis (P=0.002), dermis (P=0.034), and SLEB (P<0.001) were significantly higher in lesion; and the echo-density of dermis (P<0.001) and SLEB (P<0.001) was significantly lower in lesion.

Conclusion:

Chronic contact and atopic dermatitis are characterized by certain changes in biophysical and biomechanical properties of the skin. The evaluation of these parameters might be useful in the early diagnosis and assessment of treatment response.

Therapeutic effects of bee venom and its major component, melittin, on atopic dermatitis in vivo and in vitro

BACKGROUND AND PURPOSE

Atopic dermatitis (AD) is a multifactorial skin condition with complex interactions of innate and adaptive immune responses. There are several existing therapies for AD, including topical glucocorticosteroids, emollients, phototherapies, calcineurin inhibitors and immunosuppressants, such as cyclosporine A. Although these therapies reduce inflammation, they also cause serious side effects. Therefore, it is necessary to develop new therapeutic approaches for AD treatment without side effects. There are several studies on natural materials or toxins, such as herbs, ginseng extract and snake venom, for AD treatment. However, treatment of AD with bee venom and its major component, melittin has rarely been studied.

EXPERIMENTAL APPROACH

Effects of bee venom and melittin were studied in a model of AD in vivo induced by 1-chloro-2,4-dinitrobenzene (DNCB) in female Balb/c mice and in cultures of human keratinocytes, stimulated by TNF-α/IFN-γ. The potential pharmacological effects of bee venom and melittin on these in vivo and in vitro AD-like skin disease models were studied.

KEY RESULTS

Bee venom and melittin exhibited potent anti-atopic activities, shown by decreased AD-like skin lesions, induced by DNCB in mice. In vitro studies using TNF-α/IFN-γ-stimulated human keratinocytes showed that bee venom and melittin inhibited the increased expression of chemokines, such as CCL17 and CCL22, and pro-inflammatory cytokines, including IL-1β, IL-6 and IFN-γ, through the blockade of the NF-κB and STAT signalling pathways.

CONCLUSIONS AND IMPLICATIONS

Our results suggest that bee venom and melittin would be suitable for epicutaneous application, as topical administration is often appropriate for the treatment of AD.

Topical administration of EGF suppresses immune response and protects skin barrier in DNCB-induced atopic dermatitis in NC/Nga mice

Atopic dermatitis (AD) is a common inflammatory skin disease characterized by a complex, heterogeneous pathogenesis including skin barrier dysfunction, immunology, and pruritus. Although epidermal growth factor (EGF) is essential for epithelial homeostasis and wound healing, the effect of EGF on AD remains to be explored. To develop a new therapy for AD, the anti-AD potential of EGF was investigated by inducing AD-like skin lesions in NC/Nga mice using 2,4-dinitrochlorobenzene (DNCB). EGF was administrated to NC/Nga mice to evaluate its therapeutic effect on DNCB-induced AD. EGF treatment improved dermatitis score, ear thickness, epidermal hyperplasia, serum total immunoglobulin E level, and transepidermal water loss in NC/Nga mice with DNCB-induced AD. In addition, levels of skin barrier-related proteins such as filaggrin, involucrin, loricrin, occludin, and zonula occludens-1 (ZO-1) were increased by EGF treatment. These beneficial effects of EGF on AD may be mediated by EGF regulation of Th1/Th2-mediated cytokines, mast cell hyperplasia, and protease activated receptor-2 (PAR-2) and thymic stromal lymphopoietin (TSLP), which are triggers of AD. Taken together, our findings suggest that EGF may potentially protect against AD lesional skin via regulation of skin barrier function and immune response.

Calycosin alleviates allergic contact dermatitis by repairing epithelial tight junctions via down-regulating HIF-1α

Calycosin, a bioactive component derived from Astragali Radix (AR; Huang Qi), has been shown to have an effect of anti‐allergic dermatitis with unknown mechanism. This study aims to investigate the mechanism of calycosin related to tight junctions (TJs) and HIF‐1α both in FITC‐induced mice allergic contact dermatitis and in IL‐1β stimulated HaCaT keratinocytes. Th2 cytokines (IL‐4, IL‐5 and IL‐13) were detected by ELISA. The epithelial TJ proteins (occludin, CLDN1 and ZO‐1), initiative key cytokines (TSLP and IL‐33) and HIF‐1α were assessed by Western blot, real‐time PCR, immunohistochemistry or immunofluorescence. Herein, we have demonstrated that allergic inflammation and the Th2 cytokines in ACD mice were reduced significantly by calycosin treatment. Meanwhile, calycosin obviously decreased the expression of HIF‐1α and repaired TJs both in vivo and in vitro. In HaCaT keratinocytes, we noted that IL‐1β induced the deterioration of TJs, as well as the increased levels of TSLP and IL‐33, which could be reversed by silencing HIF‐1α. In addition, administration of 2‐methoxyestradiolin (2‐ME), a HIF‐1α inhibitor,significantly repaired the TJs and alleviated the allergic inflammation in vivo. Furthermore, TJs were destroyed by DMOG or by overexpressing HIF‐1α in HaCaT keratinocytes, and simultaneously, calycosin down‐regulated the expression of HIF‐1α and repaired the TJs in this process. These results revealed that calycosin may act as a potential anti‐allergy and barrier‐repair agent via regulating HIF‐1α in AD and suggested that HIF‐1α and TJs might be possible therapy targets for allergic dermatitis.

Epithelial barrier dysfunctions in atopic dermatitis: a skin-gut-lung model linking microbiome alteration and immune dysregulation

BACKGROUND

Atopic dermatitis is a systemic disorder characterized by abnormal barrier function across multiple organ sites. Causes of epidermal barrier breakdown are complex and driven by a combination of structural, genetic, environmental and immunological factors. In addition, alteration in microflora diversity can influence disease severity, duration, and response to treatment. Clinically, atopic dermatitis can progress from skin disease to food allergy, allergic rhinitis, and later asthma, a phenomenon commonly known as the atopic march. The mechanism by which atopic dermatitis progresses towards gastrointestinal or airway disease remains to be elucidated.

OBJECTIVES

This review addresses how epithelial dysfunction linking microbiome alteration and immune dysregulation can predispose to the development of the atopic march.

METHODS

A literature search was conducted using the PubMed database for relevant articles with the keywords 'atopic dermatitis', 'epithelial barrier', 'skin', 'gut', 'lung', 'microbiome' and 'immune dysregulation'.

RESULTS

Initial disruption in the skin epidermal barrier permits allergen sensitization and colonization by pathogens. This induces a T helper 2 inflammatory response and a thymic stromal lymphopoietin-mediated pathway that further promotes barrier breakdown at distant sites, including the intestinal and respiratory tract.

CONCLUSIONS

As there are no immediate cures for food allergy or asthma, early intervention aimed at protecting the skin barrier and effective control of local and systemic inflammation may improve long-term outcomes and reduce allergen sensitization in the airway and gut.

Structure-based drug design to overcome species differences in kallikrein 7 inhibition of 1,3,6-trisubstituted 1,4-diazepan-7-ones

A series of 1,3,6-trisubstituted 1,4-diazepan-7-ones were prepared as kallikrein 7 (KLK7, stratum corneum chymotryptic enzyme) inhibitors. Previously reported compounds 1-3 were potent human KLK7 inhibitors; however, they did not exhibit inhibitory activity against mouse KLK7. Comparison of the human and mouse KLK7 structures reveals the cause of this species differences; therefore, compounds that could inhibit both KLK7s were designed, synthesized, and evaluated. Through this structure-based drug design, compound 22g was identified as an inhibitor against human and mouse KLK7, and only one of the enantiomers, (-)-22g, exhibited potent inhibitory activity. Furthermore, the crystal structure of mouse KLK7 complexed with 22g enabled the elucidation of structure-activity relationships and justified 22g as a valuable compound to overcome the species differences.

Epidermal Growth Factor Relieves Inflammatory Signals in Staphylococcus aureus-Treated Human Epidermal Keratinocytes and Atopic Dermatitis-Like Skin Lesions in Nc/Nga Mice

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a defective immunologic barrier, which is aggravated by Staphylococcus aureus (S. aureus). Epidermal growth factor (EGF) suppresses inflammation and EGF receptor inhibitors increased S. aureus colonization. Thus, we investigated the potential roles of EGF in AD, which is often aggravated by S. aureus. We determined how EGF affects the expression of inflammatory cytokines and antimicrobial peptides (AMPs) in human epidermal keratinocytes (HEKs) treated with heat-inactivated S. aureus (HKSA) in vitro and 2,4-dinitrochlorobenzene-induced AD-like skin lesions in Nc/Nga mice. HKSA increased IL-6 and NFκB expression; EGF treatment had the opposite effect. EGF increased human β defensin-2 expression in HEKs and murine β defensin-3 in mice. In mice, both EGF and pimecrolimus groups showed less erythema with significantly reduced inflammation and decreased expression of thymic stromal lymphopoietin. EGF relieved S. aureus-induced inflammation and AD-like skin lesions in Nc/Nga mice. Therefore, EGF could be a potential topical treatment for AD.

Significance of Skin Barrier Dysfunction in Atopic Dermatitis

The epidermis contains epithelial cells, immune cells, and microbes which provides a physical and functional barrier to the protection of human skin. It plays critical roles in preventing environmental allergen penetration into the human body and responsing to microbial pathogens. Atopic dermatitis (AD) is the most common, complex chronic inflammatory skin disease. Skin barrier dysfunction is the initial step in the development of AD. Multiple factors, including immune dysregulation, filaggrin mutations, deficiency of antimicrobial peptides, and skin dysbiosis contribute to skin barrier defects. In the initial phase of AD, treatment with moisturizers improves skin barrier function and prevents the development of AD. With the progression of AD, effective topical and systemic therapies are needed to reduce immune pathway activation and general inflammation. Targeted microbiome therapy is also being developed to correct skin dysbiosis associated with AD. Improved identification and characterization of AD phenotypes and endotypes are required to optimize the precision medicine approach to AD.