Evolving Concepts of Pathogenesis in Atopic Dermatitis and Other Eczemas

A placebo-controlled, double-blind study evaluating the effect of orally administered polyunsaturated fatty acids on the oclacitinib dose for atopic dogs

BACKGROUND

Supplementation of polyunsaturated fatty acids (PUFA) enables dose reduction of prednisolone and ciclosporin in canine atopic dermatitis (cAD).

OBJECTIVE

To determine if oral administration of PUFA reduces the dose of oclacitinib in cAD.

ANIMALS

Twenty-two client-owned dogs with cAD receiving oclacitinib.

MATERIALS AND METHODS

Dogs received a fish oil product (PUFA) or paraffin oil (placebo) for 16 weeks. Owners adjusted the oclacitinib dose according to daily pruritus assessments. On Day (D)0, D56 and D112, Canine Atopic Dermatitis Extent and Severity Index, fourth iteration (CADESI-04), pruritus Visual Analog Scale (PVAS), quality-of-life score (QoL), Global Assessment (GA), quality-of-coat (QoC) and adverse events were recorded.

RESULTS

Mean daily oclacitinib dose was significantly reduced in the PUFA group from 0.51 ± 0.20 mg/kg/24 h (D0) to 0.19 ± 0.14 mg/kg/24 h (D85-112; p < 0.00001) and not in the placebo group (D0: 0.70 ± 0.33 mg/kg/24 h; D85-112: 0.53 ± 0.35 mg/kg/24 h, p = 0.5422). CADESI-04 did not change over time or differ between groups. PVAS was significantly lower in the PUFA group (2.8 ± 1.5) compared to placebo (4.2 ± 1.6) at D112 (p = 0.0375). QoL and QoC improved only in the PUFA group (QoL: D0: 20 ± 7, D112: 12 ± 5, p = 0.0057; QoC: D0: 0 ± 0.5, D112: 1 ± 0.5, p = 0.0410). GA on D112 was higher in the PUFA group (p = 0.008). No adverse events were observed.

CONCLUSION

Oral supplementation of PUFA allowed dose reduction of oclacitinib and improved PVAS, QoL, QoC and GA. The use of PUFA is recommended and was safe in the atopic study dogs receiving oclacitinib.

Cymbaria daurica L.: A Mongolian herbal medicine for treating eczema via natural killer cell-mediated cytotoxicity pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Cymbaria daurica L. (C. daurica) is a perennial herb known commonly as "Xinba" (Chinese) and "Kanba-Arong" (Mongolian). In Mongolia, it is used as a traditional medicine to treat eczema and other skin diseases due to its anti-swelling, anti-inflammatory, anti-hemorrhagic, and anti-itching properties. However, the potential mechanism of action for eczema treatment has not been reported.

AIM OF THE STUDY

To investigate the effect of C. daurica on 1-chloro-2,4-dinitrobenzene (DNCB)-induced eczema in rats and the associated action mechanism.

MATERIALS AND METHODS

Qualitative analysis of C. daurica was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on information obtained from compound identification and relevant literature, the possible targets of C. daurica against eczema were analyzed using network pharmacology and molecular docking methods. The DNCB-induced eczema rat models were treated with different dosages of C. daurica extract (10, 50, and 250 mg/mL per day), and the therapeutic effects subsequently evaluated based on the degree of skin inflammation, spleen index, and hematoxylin and eosin staining (H&E staining). Enzyme-linked immunosorbent assay (ELISA), reverse transcription quantitative polymerase chain reaction (RT-qPCR), and western blotting were used to analyze the relevant target effects. The C. daurica mechanism of action on eczema was verified by animal experiments. High-performance liquid chromatography (HPLC) was carried out to determine the content of active ingredients in C. daurica. In addition, the physicochemical properties of the extract were evaluated.

RESULTS

Our analysis of the 173 targets included in the protein-protein interaction (PPI) network identified tumor necrosis factor (TNF) and interleukin 2 (IL-2) as key targets involved in the treatment of eczema with C. daurica extract. Furthermore, the 173 targets were associated with the natural killer cell-mediated cytotoxicity pathway. Our results showed that C. daurica significantly reduced IL-2 and TNF-α serum levels in eczema rat models (P < 0.0001); thus, playing an important role in the anti-inflammatory response. Furthermore, according to the p-value, RT-qPCR and western blotting showed that the expression of Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1), Vav guanine nucleotide exchange factor (Vav), and growth factor receptor-bound protein 2 (Grb2) changed in the skin of the eczema model rats after treatment with the C. daurica extract.

CONCLUSION

Our study confirms that C. daurica can inhibit SHP-1, Vav, and Grb2 expression; thereby, inhibiting the natural killer cell-mediated cytotoxicity pathway. These results provide insight into the mechanism of C. daurica in treating eczema.

Ichthyosis vulgaris: An updated review

Ichthyosis vulgaris is an inherited, non-syndromic form of ichthyosis that presents with skin problems. Making up more than 95% cases of ichthyosis, ichthyosis vulgaris is caused by heterozygous loss-of-function mutation of the filaggrin gene, raising the fragility and permeability of the stratum corneum. It typically presents in infancy as xerosis, skin lesions, keratosis pilaris, palmoplantar hyper linearity, scaly dermatosis, and erythroderma, clearly identifiable by age 5. Although majority of patients have a normal lifespan, possible complications include a vitamin D deficiency and auditory problems due to scaling in the ears, besides a drop in quality of life due to dermatological changes. Urea-based creams with 10% urea, ceramides, and other ceramides are often the first line therapy in ichthyosis vulgaris. There is no known curative treatment for ichthyosis vulgaris, but lifelong treatment can alleviate the symptoms. Urea-based creams are highly therapeutic, whereas ammonium lactate 12% lotion with a physiological lipid-based repair cream can help with scaling and dryness. There is also evidence in favour of propylene glycol solutions. Risankizumab, an anti-interleukin-23 drug, and enhancement of natural moisturizing factors are also two highly promising solutions that require additional research. This review aims to provide updates on the manifestation, evaluation, and treatment of ichthyosis vulgaris.

Mesenchymal Stem Cells Profile in Adult Atopic Dermatitis and Effect of IL4-IL13 Inflammatory Pathway Inhibition In Vivo: Prospective Case-Control Study

Atopic dermatitis (AD) is an inflammatory disease that typically begins in childhood and may persist into adulthood, becoming a lifelong condition. The major inflammatory mediators of AD are known to be interleukin IL4 and IL13, so Dupilumab, which is able to inhibit both interleukins by blocking the shared IL4Rα subunit, has become an attractive option for treating AD. Mesenchymal stem cells (MSCs) are involved in the onset and development of AD by secreting specific interleukins. The aim of this study was to isolate MSCs from healthy controls (C-MSCs) and patients with AD before (AD-MSCs T0) and after 16 weeks of treatment with Dupilumab (AD-MSCs T16); to evaluate the expression mainly of IL4 and IL13 and of other inflammatory cytokines in C-MSCs, AD-MSCs at T0 and at T16; and to evaluate the efficacy of Dupilumab on MSCs immunobiology. C- and AD-MSCs (T0, T16) were isolated from skin specimens and characterized; the expression/secretion of IL4 and IL13 was evaluated using immuno-cytochemistry (ICC), indirect immune-fluorescence (IIF) and an ELISA test; secretion of IL2, IL4, IL5, IL6, IL10, IL12, IL13, IL17A, Interferon gamma (IFNγ), Tumor necrosis factor alpha (TNFα), Granulocyte Colony-Stimulating Factor (G-CSF), and Transforming Growth Factor beta1 (TGFβ1) were measured with ELISA. IL13 and IL6 were over-expressed, while IL4 was down-regulated in AD-MSCs at T0 compared to C-MSCs. IL6 and IL13 expression was restored after 16 weeks of Dupilumab treatment, while no significant effects on IL4 expression were noted. Finally, IL2, IL5, IL10, IL12, IL17A, INFγ, TNFα, G-CSF, and TGFβ1 were similarly secreted by C- and AD-MSCs. Although Dupilumab blocks the IL4Rα subunit shared by IL4 and IL13, it is evident that its real target is IL13, and its ability to target IL13 in MSCs reinforces the evidence, already known in differentiated cells, of the central role IL13 rather than IL4 in the development of AD. The inflammatory cascade in AD begins at the mesenchymal level, so an upstream therapeutic intervention, able to modify the immunobiology of atopic MSCs, could potentially change the natural history of the disease.

Mechanisms and Implications of Bacterial Invasion across the Human Skin Barrier

Atopic dermatitis (AD) is associated with a deficiency of skin lipids, increased populations of Staphylococcus aureus in the microbiome, and structural defects in the stratum corneum (SC), the outermost layer of human skin. However, the pathogenesis of AD is ambiguous, as it is unclear whether observed changes are the result of AD or contribute to the pathogenesis of the disease. Previous studies have shown that S. aureus is capable of permeating across isolated human SC tissue when lipids are depleted to levels consistent with AD conditions. In this study, we expand upon this discovery to determine the mechanisms and implications of bacterial penetration into the SC barrier. Specifically, we establish if bacteria are permeating intercellularly or employing a combination of both inter- and intracellular travel. The mechanical implications of bacterial invasion, lipid depletion, and media immersion are also evaluated using a newly developed, physiologically relevant, temperature-controlled drip chamber. Results reveal for the first time that S. aureus can be internalized by corneocytes, indicating transcellular movement through the tissue during permeation, consistent with previous theoretical models. S. aureus also degrades the mechanical integrity of human SC, particularly when the tissue is partially depleted of lipids. These observed mechanical changes are likely the cause of broken or ruptured tissue seen as exudative lesions in AD flares. This work further highlights the necessity of lipids in skin microbial barrier function.

IMPORTANCE Millions of people suffer from the chronic inflammatory skin disease atopic dermatitis (AD), whose symptoms are associated with a deficiency of skin lipids that exhibit antimicrobial functions and increased populations of the opportunistic pathogen Staphylococcus aureus. However, the pathogenesis of AD is ambiguous, and it remains unclear if these observed changes are merely the result of AD or contribute to the pathogenesis of the disease. In this article, we demonstrate the necessity of skin lipids in preventing S. aureus from penetrating the outermost barrier of human skin, thereby causing a degradation in tissue integrity. This bacterial permeation into the viable epidermis could act as an inflammatory trigger of the disease. When coupled with delipidated AD tissue conditions, bacterial permeation can also explain increased tissue fragility, potentially causing lesion formation in AD patients that results in further enhancing bacterial permeability across the stratum corneum and the development of chronic conditions.

Methodological Considerations for Lipid and Polar Component Analyses in Human Skin Stratum Corneum

Collection of skin very top layer, called stratum corneum, by tape stripping and the analysis of stratum corneum components by mass spectrometry provides multiple advantages for clinical studies that aim to understand the origins of allergic skin diseases and food allergy. However, such a methodology has multiple challenges on the way of complex stratum corneum analysis when molecules of different polarity are needed to be analyzed from minimal amount of skin tape strips. This review provides an overview of current knowledge about lipid and polar molecules in the skin, discusses challenging aspects of sample processing when dealing with skin tape strips, and provides some guidance towards approaches that generate complex, quantitative, normalized to total sample protein data that fit best the purpose of analysis of stratum corneum components for the purpose of clinical trials.

Dupilumab shows slow, steady effectiveness for intractable prurigo in patients with atopic dermatitis

Prurigo lesions in atopic dermatitis are intractable. This single-center, retrospective study examined dupilumab's clinical effects on intractable prurigo. Twenty adult atopic dermatitis patients (12 with prurigo, eight without) were administrated dupilumab. Its effects on itching and disease severity were examined with Numerical Rating Scale-Itch (NRS-I), Eczema Area and Severity Index (EASI), and Investigator Global Assessment (IGA) scores; body surface areas (BSA); and thymus- and activation-regulated chemokine (TARC), total immunoglobulin (Ig)E, and eosinophil levels. NRS-I scores, EASI scores, TARC levels, and total IgE levels before dupilumab treatment were not statistically different between the prurigo and non-prurigo groups. With dupilumab treatment, NRS-I scores, EASI scores, IGA scores, BSA, TARC levels, and total IgE levels were significantly reduced from baseline in both groups at 1-2 months and onward, but skin symptom improvement in the prurigo group was slower than in the non-prurigo group, as evidenced by significantly higher EASI scores, BSA, and TARC levels at several time points during the 12 months of dupilumab treatment. Prurigo patients were slower in EASI-50 achievement and significantly lower in EASI-90 achievement at 12 months than non-prurigo patients. Adherence to dupilumab was not different, but total equivalent amounts of concomitant therapeutic agents (corticosteroids and tacrolimus) used during dupilumab treatment were significantly higher in the prurigo group (median, 56.2 g/week) than in the non-prurigo group (median, 33.7 g/week). There were 2.2 adverse events per patient on average; ocular complaints were most frequent. Dupilumab was effective in treating intractable prurigo, but despite significantly greater concomitant therapeutic agent use, skin symptom improvement was slower in prurigo patients than in non-prurigo patients.

Effects of Particulate Matter in a Mouse Model of Oxazolone-Induced Atopic Dermatitis

BACKGROUND

Recent epidemiological studies have demonstrated that air pollution is associated with the inflammatory response and may aggravate inflammatory skin diseases such as atopic dermatitis (AD). However, it is unclear whether particulate matter (PM) aggravates AD symptoms.

OBJECTIVE

The aim of this study was to investigate whether PM exposure affects the skin barrier dysfunction and aggravates AD symptoms using human keratinocytes (HaCaT) cells and a mouse model of oxazolone-induced AD-like skin.

METHODS

Standard reference material (SRM) 1649b, which mainly comprises polycyclic aromatic hydrocarbons, was used as the reference PM. HaCaT cells and mouse model of oxazolone-induced AD-like skin were treated with PM. The mRNA or protein expression levels of stratum corneum (SC) and tight junction (TJ) proteins, inflammatory cytokines, as well as clinical and histological changes of the AD-like skin of mouse model were evaluated. The expression of genes and proteins was analyzed by real-time polymerase chain reaction and Western blotting. Levels of inflammatory cytokines were measured by enzyme-linked immunosorbent assay.

RESULTS

The results revealed that PM downregulates the expression levels of several SC and TJ-related proteins in the mouse model with AD-like skin. Clinically, epidermal and dermal thickness was significantly increased and dermal inflammation was prominent in PM treated AD-like skin.

CONCLUSION

In conclusion, we found that PM aggravates skin barrier dysfunction, clinically augmenting epidermal and dermal thickening with dermal inflammation in AD-like skin. These results suggest that PM may trigger the exacerbation of AD symptoms via skin barrier dysfunction-related mechanisms.

Relationship of primary immune thrombocytopenic purpura and atopia among children: a case control study

Atopic dermatitis (AD) is a chronic disease affecting 10–30% of children and 2–10% of adults worldwide. It is manifested by the pruritus eczema lesions on the skin. Immune thrombocytopenic purpura (ITP) is the most common cause of acute onset of thrombocytopenia in childhood. The aim of this study was association of primary immune thrombocytopenic purpura and atopia among children. This case control study was performed on patients with acute and chronic ITP who were confirmed by a hematologist. The control group was also selected from the siblings of the patients who were healthy and almost matched by age and sex with the patient group. Data were entered into a questionnaire under the SPSS-20 program, and demographic data were analyzed descriptively. In the present study, 120 patients were enrolled, 60 of whom were in the patient group and 60 in the control group. Mean age was 95 and 98 months for patients and control. This study showed a significant association of ITP with allergic rhinitis (P = 0.02), atopic dermatitis (P = 0.004), itching (P = 0.042), and dry skin (P = 0.015). However, no significant relationship was found between ITP and asthma (P-value = 0.18). This study does not reveal the causality between atopy and ITP but clearly shows the association between atopy and ITP disease, so the prevalence of atopy in ITP patients is higher than the normal population. According to the results of this study, it is necessary to investigate the cause of atopy and ITP and to find other immunological and possibly genetic commonalities.

Lipid depletion enables permeation of Staphylococcus aureus bacteria through human stratum corneum

Atopic dermatitis (AD) is a chronic inflammatory disease that affects approximately 2-5% of adults worldwide. The pathogenesis of AD continues to be a well-debated point of conjecture, with numerous hypotheses having been proposed. AD conditions are associated with increased populations of Staphylococcus aureus and reduced skin lipids. In this study, we evaluate the ability of S. aureus to permeate across human stratum corneum (SC) exhibiting both normal and depleted lipid conditions consistent with AD. This permeation would enable bacteria to interact with underlying viable epidermal cells, which could serve as a trigger for inflammation and disease onset. Our results indicate that permeation of S. aureus through SC exhibiting normal lipid conditions is not statistically significant. However, bacteria can readily permeate through lipid depleted tissue over a 9-d period. These findings suggest that S. aureus may potentially act as the mechanistic cause, rather than merely the result of AD.

ABBREVIATIONS

AD: Atopic dermatitis; SC: Stratum Corneum; AMP: Antimicrobial peptide; DIW: Deionized water; PDMS: Polydimethylsiloxane; GFP: Green fluorescent protein; BHI: Brain heart infusion medium.

Pathophysiology of Atopic Dermatitis and Psoriasis: Implications for Management in Children

Atopic dermatitis (AD) and psoriasis are chronic inflammatory skin diseases associated with a significant cutaneous and systemic burden of disease as well as a poor health-related quality of life. Here, we review the complex pathophysiology of both AD and psoriasis and discuss the implications for treatment with current state-of-the-art and emerging topical and systemic therapies. Both AD and psoriasis are caused by a complex combination of immune dysregulation, skin-barrier disruption, genetic factors, and environmental influences. Previous treatments for both diseases were limited to anti-inflammatory agents that broadly suppress inflammation. Emerging insights into relevant pathways, including recognition of the role of T-helper type 2 driven inflammation in AD and T-helper 1 and 17 driven inflammation in psoriasis, have led to a therapeutic revolution. There are a number of novel treatment options available for AD and psoriasis with many more currently under investigation.

A20 and ABIN1 Suppression of a Keratinocyte Inflammatory Program with a Shared Single-Cell Expression Signature in Diverse Human Rashes

Genetic variation in the NF-κB inhibitors, ABIN1 and A20, increase risk for psoriasis. While critical for hematopoietic immune cell function, these genes are believed to additionally inhibit psoriasis by dampening inflammatory signaling in keratinocytes. We dissected ABIN1 and A20's regulatory role in human keratinocyte inflammation using an RNA sequencing-based comparative genomic approach. Here we show subsets of the IL-17 and tumor necrosis factor-α signaling pathways are robustly restricted by A20 overexpression. In contrast, ABIN1 overexpression inhibits these genes more modestly for IL-17, and weakly for tumor necrosis factor-α. Our genome-scale analysis also indicates that inflammatory program suppression appears to be the major transcriptional influence of A20/ABIN1 overexpression, without obvious influence on keratinocyte viability genes. Our findings thus enable dissection of the differing anti-inflammatory mechanisms of two distinct psoriasis modifiers, which may be directly exploited for therapeutic purposes. Importantly, we report that IL-17-induced targets of A20 show similar aberrant epidermal layer-specific transcriptional upregulation in keratinocytes from diseases as diverse as psoriasis, atopic dermatitis, and erythrokeratodermia variabilis, suggesting a contributory role for epidermal inflammation in a broad spectrum of rashes.

Eczema and Urticaria in the Adult Population in Portugal: A Prevalence Study

BACKGROUND AND AIMS

Eczema and urticaria are both inflammatory skin diseases. The prevalence of both diseases varies worldwide and the reasons are unknown. We aimed to investigate the eczema and urticaria prevalence in the Portuguese adult (≥16 years-old) population.

MATERIALS AND METHODS

A telephone interview survey was performed in the last quarter of 2017. To calculate the prevalences, subjects should have been previously diagnosed with eczema/urticaria by a health professional, be aged ≥16 years-old, and reside in Portugal. The sample had a proportion that was approximately representative by population, region, gender, and age group. Odds ratios were performed to measure associations with prevalences. SPSS statistics and values of p<0.05 with 95% confidence intervals were considered statistically significant.

RESULTS

5,000 phone calls were analysed. The prevalence of eczema and urticaria in Portugal is 4.4% and 3.4%, respectively. Algarve is the region with the highest prevalence for both diseases. Being a female is the factor that most influenced these diseases with an OR=1.99 (p<0.001; CI 1.49-2.66) for eczema and 1.73 (p=0.001; CI 1.25 - 2.40) for urticaria, with also higher prevalences (5.7% and 4.2%, respectively).

CONCLUSIONS

The prevalences found are higher than in previous studies in Portugal and comparable to results from other countries. Comparisons among prevalence of eczema are affected by several obstacles. Regarding urticaria, our results seem to be in the same line as others. Being female with eczema and urticaria is more common and represents a higher risk factor than male subjects. According to Harrop et al., 2007, in Europe, atopic eczema is 0.14-0.60% of general eczema. In this way, we can estimate that prevalence of atopic eczema in Portugal is around 0.61-2.64%.

Visualization of dendritic cells' responses in atopic dermatitis: Preventing effect of emollient

Atopic dermatitis (AD) is a chronic and multifactorial inflammatory skin disease involving various dendritic cells such as epidermal Langerhans cells (LC) and inflammatory dendritic epidermal cells (IDECs). Most of the clinical studies was performed on isolated cells, and thus, it would be useful to characterize directly on the human epidermal tissue the first cellular events occurred during the AD. The suction blister method was used to obtain whole epidermis samples and interstitial cutaneous fluids. Employing multiphoton microscopy, we analyzed the early dynamic behavior of inflammatory cells using Dermatophagoides pteronyssinus atopy patch test (Derp-APT) and evaluated the effects of emollient pre-application. Derp-APT application provoked rapid and strong infiltration of IDECs, and proliferation and activation of LC in the AD subjects' epidermis. Moreover, emollient pre-application strengthened the defective skin barrier and had positive effects on inflammatory cells' behavior, characterized by the complete inhibition of IDEC influx and the presence of immature LC.

Activation of the HMGB1‑TLR4‑NF‑κB pathway may occur in patients with atopic eczema

High mobility group protein B1 (HMGB1) has been reported to serve important roles in various pathological conditions. Toll‑like receptor 4 (TLR4), as one of the HMGB1 receptors, has been reported to be involved in the development of certain inflammatory diseases by activating nuclear factor NF‑κ‑B (NF‑κB). However, there are few studies investigating the effects of HMGB1, TLR4 and NF‑κB on human inflammatory dermatoses. In the present study, the distribution and characteristics of HMGB1, TLR4 and NF‑κB p65 expression in psoriasis and atopic eczema (AE) were investigated. In addition, immunohistochemical analysis was performed to evaluate their expression and distribution in normal skin, and in patients with AE or psoria-sis. Spearman's correlation analysis was used to predicate their relevancy. The present study identified that the p65 level in epithelial nuclei in AE skin was increased compared with normal and psoriasis skin (P<0.01). The level of extracellular HMGB1 in AE skin was also increased compared with normal and psoriasis skin (P<0.01). Meanwhile, TLR4 expression on the epithelial membranes of AE skin was increased compared with psoriasis skin (P<0.01). Furthermore, the level of extracellular HMGB1 was positively correlated with epithelial membrane TLR4 (r=0.3856; P<0.05) and epithelial nuclear p65 (r=0.5894; P<0.01) in AE skin. These results indicated that the HMGB1‑TLR4‑NF‑κB signaling pathway is activated in AE and may account for its pathogenesis, but not in psoriasis. Therefore, HMGB1, TLR4 and NF‑κB p65 have the potential to be targets for the treatment of human inflammatory dermatoses, including AE.

The Role of Interleukins 4 and/or 13 in the Pathophysiology and Treatment of Atopic Dermatitis

Moderate to severe atopic dermatitis (AD) can be debilitating and often requires use of systemic immunosuppressant therapy to achieve adequate disease control. There are currently no US Food and Drug Administration-approved systemic agents for the long-term treatment of AD. Recent insight has identified the T helper 2 cytokines, interleukins 4 and 13, as playing a major role in the pathogenesis of AD. There are multiple novel biologic agents in development that target interleukins 4 and/or 13 for the treatment of moderate to severe AD. The age of targeted biologics for AD has arrived.

Current and emerging concepts in atopic dermatitis pathogenesis

Atopic dermatitis is a common skin disorder with a complex, evolving pathogenesis. Research on the pathogenesis has shifted from focusing primarily on generalized immune system abnormalities in T helper 1/T helper 2 (T_h1/T_h2) activity to more targeted immune and skin barrier abnormalities contributing to the overall phenotype. Specific signaling pathways recently implicated in atopic dermatitis include production of interleukin (IL) 4 and IL-13, which promote immunoglobulin E production, T_h17 and T_h22 cells, and production of cytokines. Barrier defect abnormalities, such as a shared filaggrin mutation noted in ichthyosis vulgaris and atopic dermatitis, as well as reduced structural proteins and lipids (eg, ceramides), have been discovered as well. These alterations contribute to increased transepidermal water loss in addition to increased allergen exposure, resulting in debate over the "inside out" versus "outside in" theories-that is, the concept that immunity triggers barrier breakdown versus barrier abnormalities triggering immunologic alteration toward atopy. In fact, it is likely that all of these contribute to pathogenesis, with some individuals initially experiencing immunologic abnormalities more strongly than barrier defects and vice versa. Genetic analyses have continued to advance, leading to the discovery of potential candidate genes relating both to the impaired skin barrier and the altered immune system pathways. This review outlines the evolution of the field of current pathogenesis of atopic dermatitis, highlighting the most pertinent recent findings.

Trp channels and itch

Itch is a unique sensation associated with the scratch reflex. Although the scratch reflex plays a protective role in daily life by removing irritants, chronic itch remains a clinical challenge. Despite urgent clinical need, itch has received relatively little research attention and its mechanisms have remained poorly understood until recently. The goal of the present review is to summarize our current understanding of the mechanisms of acute as well as chronic itch and classifications of the primary itch populations in relationship to transient receptor potential (Trp) channels, which play pivotal roles in multiple somatosensations. The convergent involvement of Trp channels in diverse itch signaling pathways suggests that Trp channels may serve as promising targets for chronic itch treatments.

Lactobacillus plantarum NCIMB8826 ameliorates inflammation of colon and skin in human APOC1 transgenic mice

Genetic predisposition and environmental factors, including the gut microbiota, have been suggested as major factors in the development and progression of atopic dermatitis. Hyperlipidemic human APOC1+/+ transgenic mice display many features of human atopic dermatitis, such as scaling, lichenification, excoriations, and pruritus, along with a disturbed skin barrier function. Cytokine analysis of serum shows an increase of various pro-inflammatory cytokines, including interleukin (IL)-12p40, IL-6, and IL-1α, but lower levels of interferon-γ. These mice also display aspects of colitis evident from macroscopic and histological abnormalities. Genome-wide transcriptome analysis of the intestine shows up-regulation of several genes associated with mast cells and eosinophils and this observation was confirmed by demonstrating increased numbers of IgE+ and FcRε+ mast cells in the colon and in the skin. Oral treatment with Lactobacillus plantarum NCIMB8826 resulted in decreased numbers of mast cells in the colon. Moreover, this L. plantarum strain ameliorated skin pathology, evident from improved skin barrier integrity, absence of skin thickening, and less excoriations. These results suggest that modulation of intestinal immune homeostasis contributes to the suppression of atopic dermatitis.

Food Allergy in Atopic Dermatitis

Food allergy in atopic dermatitis (AD) is debatable from decades. Role of diet in the cause and treatment of AD is controversial and is not well-defined. Allergists and pediatricians are convinced about the food allergy in AD whereas many dermatologists are contrary for this. However, there are studies in the Indian and western literature supporting the evidence that elimination diet may improve the severe type of AD. There is increasing awareness and lot of misconception among caregivers about food allergy and hence careful understanding about this concept is necessary to counsel parents. Recent evidence-based literature suggests avoidance of proven food allergens in AD could be beneficial in moderate to severe type of AD.

Differential expression of inflammation-related genes in IL-4 transgenic mice before and after the onset of atopic dermatitis skin lesions

IL-4 plays an important role in the pathogenesis of atopic dermatitis (AD), a common chronic inflammatory skin disease. We have generated IL-4 transgenic (Tg) mice by over-expressing IL-4 in the epidermis. These mice spontaneously develop chronic pruritic inflammatory skin lesions, which meet the clinical and histological diagnostic criteria for human AD. Systemic survey of immune-related genes in this mouse model, however, has not been performed. In this study, we utilize PCR array technique to examine hundreds of inflammation-related genes in the IL-4 Tg mice before and after the onset of skin lesions as well as in their wild type (WT) littermates. Only those genes with at least 2-fold up-regulation or down-regulation and with a P-value of less than 0.05 in comparison to WT controls were identified and analyzed. In the skin lesions, many chemokines, pro-inflammatory cytokines, and other AD-related factors are dysregulated compared to the wild type mice. Particularly, CXCL5, IL-1β, IL-24, IL-6, oncostatin M, PTGS2, FPR1 and REG3γ are up-regulated several hundred-fold. In the pre-lesional group that shows no obvious skin abnormality on clinical observation, 30 dysregulated genes are nevertheless identified though the fold changes are much less than that of the lesional group, including CCL6, CCL8, CCL11, CCL17, CXCL13, CXCL14, CXCR3 and IL-12Rβ2. Finally using ELISA, we demonstrate that 4 most dramatically up-regulated factors in the skin are also elevated in the peripheral blood of the IL-4 Tg mice. Taken together, our data have identified hundreds of dysregulated factors in the IL-4 Tg mice before and after the onset of skin lesions. Future detailed examination of these factors will shed light on our understanding of the development and progression of AD and help to discover important biomarkers for clinical AD diagnosis and treatment.

Prevalence of Atopic Dermatitis in Korean Children Based on Data From the 2008-2011 Korean National Health and Nutrition Examination Survey

Population-based studies of atopic dermatitis (AD) in Korean children are lacking. Thus, the purpose of this study was to determine the prevalence, geographic distribution, and risk factors of AD in the Korean pediatric population. We examined AD prevalence using data from the 2008-2011 Korea National Health and Nutrition Examination Survey (KNHANES), which was a cross-sectional survey of 8,947 children up to age 18 throughout the country. Overall, 13.50% of children reported a diagnosis of AD. The age-standardized prevalence ranged from 9.13% to 17.67% between cities and provinces, with the highest prevalence-observed in many of the larger cities at low latitudes, as well as Jeju-do. After adjusting for confounders, high economic status was found to be a significant factor for predicting increased prevalence of AD, with an odds ratio of 1.35 (95% confidence interval of 1.02-1.79, P=0.0034). Urban living (odds ratio 1.24, 95% confidence interval of 1.00-1.53, P=0.0526) was also associated with a higher prevalence of AD. In this first large scale, nationwide study in Korean children, we found that the overall prevalence of AD depends on age, household income, and geographic distribution.

Transient receptor potential channels and itch: how deep should we scratch?

Over the past 30 years, transient receptor potential (TRP) channels have evolved from a somewhat obscure observation on how fruit flies detect light to become the center of drug discovery efforts, triggering a heated debate about their potential as targets for therapeutic applications in humans. In this review, we describe our current understanding of the diverse mechanism of action of TRP channels in the itch pathway from the skin to the brain with focus on the peripheral detection of stimuli that elicit the desire to scratch and spinal itch processing and sensitization. We predict that the compelling basic research findings on TRP channels and pruritus will be translated into the development of novel, clinically useful itch medications.

Filaggrin loss-of-function mutations are associated with food allergy in childhood and adolescence

BACKGROUND

Filaggrin is an epidermal protein that has a role in skin barrier function. Filaggrin loss-of-function (FLG-LOF) mutations are a significant risk factor for eczema and atopy, but their association with food allergy (FA) is less clear.

OBJECTIVE

We explored the longitudinal relationship between 3 common FLG-LOF mutations and FA using the Isle of Wight birth cohort.

METHODS

FA diagnosis was based on recognized allergic reactions within 4 hours after exposure to known food allergens. Food allergen sensitization (FAS) was identified by using skin prick tests conducted between 1 and 18 years of age to a range of food allergens. Three FLG mutations were genotyped in 1150 (79%) of 1456 children. The temporal relationships between FA, FAS, and eczema in children with FLG mutations were explored by using path analysis with total, direct, and indirect effect models.

RESULTS

There was a significant total effect of FLG-LOF mutations on the risk of FA in later childhood at the ages of 10 (odds ratio, 31.46; 95% CI, 2.86 to >100) and 18 (odds ratio, 4.25; 95% CI, 1.55-11.61) years. Path analysis showed that there was no direct effect of FLG-LOF mutations on FA at any age; however, an indirect effect was found on FA at all ages through eczema and FAS in the earlier years.

CONCLUSION

FLG-LOF mutations are associated with FA in older children through eczema and FAS during early childhood. Our results highlight a biologically plausible pathway, which suggests that skin barrier function is important in the development and persistence of FA.

Metabolomics approach in allergic and rheumatic diseases

Metabolomics is the analysis of the concentration profiles of low molecular weight compounds present in biological fluids. Metabolites are nonpeptide molecules representing the end products of cellular activity. Therefore, changes in metabolite concentrations reveal the range of biochemical effects induced by a disease or its therapeutic intervention. Metabolomics has recently become feasible with the accessibility of new technologies, including mass spectrometry and high-resolution proton nuclear magnetic resonance, and has already been applied to several disorders. Indeed, it has the advantage of being a nontargeted approach for identifying potential biomarkers, which means that it does not require a preliminary knowledge of the substances to be studied. In this review, we summarize the main studies in which metabolomic approach was used in some allergic (asthma, atopic dermatitis) and rheumatic diseases (rheumatoid arthritis, systemic lupus erythematosus) to explore the feasibility of this technique as a novel diagnostic tool in these complex disorders.

Role of neuromediators in the development of skin inflammation in patients with atopic dermatitis

Neurotransmitters such as neuropeptides and neurotrophins can have an effect on the development of a skin inflammatory reaction and itching as well as condition of nerve fibers. Goal. To assess the expression of neuropeptides and neurotrophins in the skin of patients with atopic dermatitis. Materials and methods. Expression of neuropeptides of substance P and SP-R receptor, calcitonin gene-related peptide (CGRP) and CGRP-R receptor, neurotrophin (nerve growth factor) and TrkA receptor as well as amphiregulin enhancing the growth of nerve fibers and semaphorin-3A terminating the growth of nerve fibers was determined in the skin of patients with atopic dermatitis based on the immunohistochemistry analysis method. Expression of protein PGP9.5 being a marker of nerve fibers was also determined. Results. The authors discovered penetration of nerve fibers expressing substance P and CGRP into the epidermis in patients with atopic dermatitis. Expression of the nerve growth factor and amphiregulin was discovered in epidermis but no expression of semaphorin-3A was discovered. Conclusion. Nerve fibers expressing neuropeptides such as substance P and CGRP can penetrate into the epidermis in patients with atopic dermatitis, which can maintain the inflammatory reaction and itching in such patients. Expression of the growth factors (nerve growth factor and amphiregulin) can contribute to the growth of nerve fibers and their penetration into epidermis against the background of the absence of any expression of semaphorin-3A inhibiting their growth.

Atopic dermatitis in pregnancy: current status and challenges

Atopic dermatitis (AD) is the most common pregnancy dermatosis. This evidence-based review article provides an evaluation of AD in gestation. Our literature search revealed 4 epidemiologic studies on AD in pregnancy, and a total of 55 articles that provide the basis for this review. The limitations of epidemiologic studies included herein are critically reviewed. The management of AD in gestation is reviewed with an emphasis on drug safety. Further studies are required to determine whether it is the intrinsic ("nonallergic" or "atopiform dermatitis") and/or extrinsic (IgE-associated) AD that is affected by pregnancy, and to establish the postpartum prognosis of "new atopic dermatitis" (AD presenting for the first time in pregnancy). A revision of the diagnostic criteria will allow a more accurate confirmation of the prevalence of AD, and especially "new atopic dermatitis," in pregnancy as well as differentiation of AD from specific dermatoses of pregnancy, such as prurigo and pruritic folliculitis. Addressing the above issues and unraveling the etiopathogenesis of AD in pregnancy will help clarify a suggested overlap with the above specific dermatoses.

Skin microbiome: looking back to move forward

Trillions of bacteria, fungi, viruses, archaea and small arthropods colonize the skin surface, collectively comprising the skin microbiome. Generations of researchers have classified these microbes as transient versus resident, beneficial versus pathogenic, collaborators versus adversaries. Culturing and direct sequencing of microbial inhabitants identified distinct populations present at skin surface sites. Herein, we explore the history of this field, describe findings from the current molecular sequencing era, and consider the future of investigating how microbes and antimicrobial therapy contribute to human health.

The relationship of rhinitis and asthma, sinusitis, food allergy, and eczema

Epidemiologic, genetic, immunologic, and clinical studies show a close relationship between allergic rhinitis and asthma, food allergy, and atopic dermatitis. Rhinitis and sinusitis often coexist and are commonly referred to with the term rhinosinusitis. These conditions are also linked in the so-called atopic march, which is the sequential appearance of atopic manifestations starting with atopic dermatitis and later followed by food allergy, allergic rhinitis, and asthma. Allergic rhinitis and asthma are now increasingly being approached diagnostically and therapeutically as the one-airway concept.

Epidemiology of atopic dermatitis and atopic march in children

Atopic dermatitis (AD) is one of the most common chronic childhood skin diseases affecting up to 17% of children in the United States. The point prevalence of AD has increased based on validated questionnaires in the most recent update of the International Study of Asthma and Allergies in Childhood. However, the increases are primarily in developing countries, whereas the rates have stabilized in countries with higher incomes. AD starts in early childhood with 65% of children affected by 18 months of age. Furthermore, less than half of the patients with AD have complete resolution by 7 years of age and only 60% have resolution by adulthood, indicating the chronic nature of AD. AD is a major risk factor for the development of asthma, with an increased odds ratio in children with AD in several longitudinal studies compared with children without AD, and about 30% of patients with AD develop asthma. Patients with atopic sensitization along with eczema are at a higher risk for progressing in the atopic march to asthma. The main risk factors for progression and persistence of asthma are early onset and severity of AD.

Loss-of-function variants in the filaggrin gene are a significant risk factor for peanut allergy

BACKGROUND

IgE-mediated peanut allergy is a complex trait with strong heritability, but its genetic basis is currently unknown. Loss-of-function mutations within the filaggrin gene are associated with atopic dermatitis and other atopic diseases; therefore, filaggrin is a candidate gene in the etiology of peanut allergy.

OBJECTIVE

To investigate the association between filaggrin loss-of-function mutations and peanut allergy.

METHODS

Case-control study of 71 English, Dutch, and Irish oral food challenge-positive patients with peanut allergy and 1000 non peanut-sensitized English population controls. Replication was tested in 390 white Canadian patients with peanut allergy (defined by food challenge, or clinical history and skin prick test wheal to peanut ≥ 8 mm and/or peanut-specific IgE ≥ 15 kUL(-1)) and 891 white Canadian population controls. The most prevalent filaggrin loss-of-function mutations were assayed in each population: R501X and 2282del4 in the Europeans, and R501X, 2282del4, R2447X, and S3247X in the Canadians. The Fisher exact test and logistic regression were used to test for association; covariate analysis controlled for coexistent atopic dermatitis.

RESULTS

Filaggrin loss-of-function mutations showed a strong and significant association with peanut allergy in the food challenge-positive patients (P = 3.0 × 10(-6); odds ratio, 5.3; 95% CI, 2.8-10.2), and this association was replicated in the Canadian study (P = 5.4 × 10(-5); odds ratio, 1.9; 95% CI, 1.4-2.6). The association of filaggrin mutations with peanut allergy remains significant (P = .0008) after controlling for coexistent atopic dermatitis.

CONCLUSION

Filaggrin mutations represent a significant risk factor for IgE-mediated peanut allergy, indicating a role for epithelial barrier dysfunction in the pathogenesis of this disease.

Eczema prevalence in the United States: data from the 2003 National Survey of Children's Health

Using the 2003 National Survey of Children's Health sponsored by the federal Maternal and Child Health Bureau, we calculated prevalence estimates of eczema nationally and for each state among a nationally representative sample of 102,353 children 17 years of age and under. Our objective was to determine the national prevalence of eczema/atopic dermatitis in the US pediatric population and to further examine geographic and demographic associations previously reported in other countries. Overall, 10.7% of children were reported to have a diagnosis of eczema in the past 12 months. Prevalence ranged from 8.7 to 18.1% between states and districts, with the highest prevalence reported in many of the East Coast states, as well as in Nevada, Utah, and Idaho. After adjusting for confounders, metropolitan living was found to be a significant factor in predicting a higher disease prevalence with an odds ratio of 1.67 (95% confidence interval of 1.19-2.35, P=0.008). Black race (odds ratio 1.70, P=0.005) and education level in the household greater than high school (odds ratio 1.61, P=0.004) were also significantly associated with a higher prevalence of eczema. The wide range of prevalence suggests that social or environmental factors may influence disease expression.