Loss-of-function mutations in the filaggrin gene lead to reduced level of natural moisturizing factor in the stratum corneum. J Invest Dermatol. 2008;128:2117-2119. [PMID: 18305568 DOI: 10.1038/jid.2008.29]

Research progress on the mechanism of common inflammatory pathways in the pathogenesis and development of lymphoma

In recent years, the incidence and mortality rates of lymphoma have gradually increased worldwide. Tumorigenesis and drug resistance are closely related to intracellular inflammatory pathways in lymphoma. Therefore, understanding the biological role of inflammatory pathways and their abnormal activation in relation to the development of lymphoma and their selective modulation may open new avenues for targeted therapy of lymphoma. The biological functions of inflammatory pathways are extensive, and they are central hubs for regulating inflammatory responses, immune responses, and the tumour immune microenvironment. However, limited studies have investigated the role of inflammatory pathways in lymphoma development. This review summarizes the relationship between abnormal activation of common inflammatory pathways and lymphoma development to identify precise and efficient targeted therapeutic options for patients with advanced, drug-resistant lymphoma.

Topically Applied Therapies for the Treatment of Skin Disease: Past, Present, and Future

The purpose of this review is to summarize essential biological, pharmaceutical, and clinical aspects in the field of topically applied medicines that may help scientists when trying to develop new topical medicines. After a brief history of topical drug delivery, a review of the structure and function of the skin and routes of drug absorption and their limitations is provided. The most prevalent diseases and current topical treatment approaches are then detailed, the organization of which reflects the key disease categories of autoimmune and inflammatory diseases, microbial infections, skin cancers, and genetic skin diseases. The complexity of topical product development through to large-scale manufacturing along with recommended risk mitigation approaches are then highlighted. As such topical treatments are applied externally, patient preferences along with the challenges they invoke are then described, and finally the future of this field of drug delivery is discussed, with an emphasis on areas that are more likely to yield significant improvements over the topical medicines in current use or would expand the range of medicines and diseases treatable by this route of administration. SIGNIFICANCE STATEMENT: This review of the key aspects of the skin and its associated diseases and current treatments along with the intricacies of topical formulation development should be helpful in making judicious decisions about the development of new or improved topical medicines. These aspects include the choices of the active ingredients, formulations, the target patient population's preferences, limitations, and the future with regard to new skin diseases and topical medicine approaches.

Tapinarof validates the aryl hydrocarbon receptor as a therapeutic target: A clinical review

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that has wide-ranging roles, including regulation of inflammation and homeostasis. AhR is not a cell surface receptor; rather, it exists in a cytoplasmic complex that responds to a wide variety of structurally dissimilar endogenous, microbial, and environmental ligands. The ubiquitous expression of AhR, its ability to be activated by a wide range of ligands, and its capacity to act as a master regulator for gene expression and homeostasis make it a promising new therapeutic target. Clinical trials of tapinarof cream have now validated AhR agonism as a therapeutic approach that can deliver significant efficacy for treating inflammatory skin diseases, including psoriasis and atopic dermatitis. Tapinarof 1% cream is a first-in-class, nonsteroidal, topical, AhR agonist with a pharmacokinetic profile that results in localized exposure at sites of disease, avoiding systemic safety concerns, drug interactions, or off-target effects. Psoriasis and atopic dermatitis both involve epidermal inflammation, cellular immune responses, dysregulation of skin barrier protein expression, and oxidative stress. On the basis of the clinical effectiveness of tapinarof cream for treating inflammatory skin diseases, we review how targeting AhR may offer a significant opportunity in other conditions that share key aspects of pathogenesis, including asthma, inflammatory bowel disease, eosinophilic esophagitis, ophthalmic, and nervous system diseases.

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.

Epidermal barrier function in dry, flaky and sensitive skin: A narrative review

The stratum corneum (SC)-the outermost layer of the epidermis-is the principal permeability and protective barrier of the skin. Different components of the SC, including corneocytes, natural moisturizing factor, a variety of enzymes and their inhibitors, antimicrobial peptides and lipids, work interactively to maintain barrier function. The main barrier properties of the SC are the limitation of water loss and the prevention of infection and contact with potentially harmful exogenous factors. Although the SC functions consistently as a protective barrier throughout the body, variations in functions and morphology occur across body sites with age and skin type. Healthy SC function also depends on the interplay between the chemosensory barrier, the skin's microbiome and the innate immune system. Dysregulation of SC barrier function can lead to the development of skin disorders, such as dry, flaky or sensitive skin, but the complete underlying pathophysiology of these are not fully understood. This review provides insight into the current literature and emerging themes related to epidermal barrier changes that occur in the context of dry, flaky and sensitive skin. Additional studies are needed to further elucidate the underlying aetiology of dry, flaky and sensitive skin and to provide tailored treatment.

Atopic Dermatitis in Children

Atopic dermatitis (AD) is extremely common in the pediatric population, and most children with AD will first present to their primary care provider (PCP). The PCP can recognize AD by its clinical features, including itch, a chronic relapsing course, and the characteristic eruption. The cornerstone of AD therapy is dry skin care, typically a short daily bath/shower followed by an emollient applied to all skin. Most children with AD will also require topical medications, such as topical corticosteroids and/or topical nonsteroidal therapies. For children with more severe disease, systemic agents, including several novel therapies, may be required. In managing AD, the clinician must monitor for side effects of medications as well as complications of the AD itself, the most common of which is secondary infection. An understanding of the pathogenesis, treatments, and complications of AD is essential for the PCP, as untreated (or undertreated) AD has a significant impact on the quality of life of affected children and their caregivers. [Pediatr Ann. 2024;53(4):e121-e128.].

Involvement and repair of epithelial barrier dysfunction in allergic diseases

The epithelial barrier serves as a critical defense mechanism separating the human body from the external environment, fulfilling both physical and immune functions. This barrier plays a pivotal role in shielding the body from environmental risk factors such as allergens, pathogens, and pollutants. However, since the 19th century, the escalating threats posed by environmental pollution, global warming, heightened usage of industrial chemical products, and alterations in biodiversity have contributed to a noteworthy surge in allergic disease incidences. Notably, allergic diseases frequently exhibit dysfunction in the epithelial barrier. The proposed epithelial barrier hypothesis introduces a novel avenue for the prevention and treatment of allergic diseases. Despite increased attention to the role of barrier dysfunction in allergic disease development, numerous questions persist regarding the mechanisms underlying the disruption of normal barrier function. Consequently, this review aims to provide a comprehensive overview of the epithelial barrier's role in allergic diseases, encompassing influencing factors, assessment techniques, and repair methodologies. By doing so, it seeks to present innovative strategies for the prevention and treatment of allergic diseases.

The Potential of Campanula takesimana Callus Extract to Enhance Skin Barrier Function

Atopic dermatitis (AD) is a prevalent inflammatory skin disease characterized by epidermal barrier dysfunction and Th2-skewed inflammation. Campanula takesimana (C. takesimana), a Korean endemic plant grown on Ulleng Island, has long been associated with a traditional alternative medicine for asthma, tonsillitis, and sore throat. In this study, we reported the effect of C. takesimana callus extract on upregulating epidermal barrier-related proteins dysregulated by Th2 cytokines. C. takesimana callus extract induced the expression of skin barrier proteins, such as filaggrin, claudin-1, and zonula occludens-1, in both human primary keratinocytes and Th2-induced AD-like skin-equivalent models. Additionally, RNA sequencing analysis demonstrated that C. takesimana callus extract partially restored Th2 cytokine-induced dysregulation of the epidermal development and lipid metabolic pathways. Considering the advantages of callus as a sustainable eco-friendly source of bioactive substances, and its effect on skin barrier proteins and lipid metabolic pathways, C. takesimana callus extracts can possibly be utilized to improve the integrity of the skin barrier.

Atopic Dermatitis: Molecular Alterations between Lesional and Non-Lesional Skin Determined Noninvasively by In Vivo Confocal Raman Microspectroscopy

Atopic dermatitis (AD)/atopic eczema is a chronic relapsing inflammatory skin disease affecting nearly 14% of the adult population. An important pathogenetic pillar in AD is the disrupted skin barrier function (SBF). The atopic stratum corneum (SC) has been examined using several methods, including Raman microspectroscopy, yet so far, there is no depth-dependent analysis over the entire SC thickness. Therefore, we recruited 21 AD patients (9 female, 12 male) and compared the lesional (LAS) with non-lesional atopic skin (nLAS) in vivo with confocal Raman microspectroscopy. Our results demonstrated decreased total intercellular lipid and carotenoid concentrations, as well as a shift towards decreased orthorhombic lateral lipid organisation in LAS. Further, we observed a lower concentration of natural moisturising factor (NMF) and a trend towards increased strongly bound and decreased weakly bound water in LAS. Finally, LAS showed an altered secondary and tertiary keratin structure, demonstrating a more folded keratin state than nLAS. The obtained results are discussed in comparison with healthy skin and yield detailed insights into the atopic SC structure. LAS clearly shows molecular alterations at certain SC depths compared with nLAS which imply a reduced SBF. A thorough understanding of these alterations provides useful information on the aetiology of AD and for the development/control of targeted topical therapies.

Genomic, Epigenomic, Transcriptomic, Proteomic and Metabolomic Approaches in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a high prevalence in the developed countries. It is associated with atopic and non-atopic diseases, and its close correlation with atopic comorbidities has been genetically demonstrated. One of the main roles of genetic studies is to comprehend the defects of the cutaneous barrier due to filaggrin deficit and epidermal spongiosis. Recently, epigenetic studies started to analyze the influence of the environmental factors on gene expression. The epigenome is considered to be a superior second code that controls the genome, which includes alterations of the chromatin. The epigenetic changes do not alter the genetic code, however, changes in the chromatin structure could activate or inhibit the transcription process of certain genes and consequently, the translation process of the new mRNA into a polypeptide chain. In-depth analysis of the transcriptomic, metabolomic and proteomic studies allow to unravel detailed mechanisms that cause AD. The extracellular space and lipid metabolism are associated with AD that is independent of the filaggrin expression. On the other hand, around 45 proteins are considered as the principal components in the atopic skin. Moreover, genetic studies based on the disrupted cutaneous barrier can lead to the development of new treatments targeting the cutaneous barrier or cutaneous inflammation. Unfortunately, at present, there are no target therapies that focus on the epigenetic process of AD. However, in the future, miR-143 could be an important objective for new therapies, as it targets the miR-335:SOX axis, thereby restoring the miR-335 expression, and repairing the cutaneous barrier defects.

From Coffee Waste to Active Ingredient for Cosmetic Applications

Coffee silverskin (CS) is the thin epidermis covering and protecting the coffee bean and it represents the main by-product of the coffee roasting process. CS has recently gained attention due to its high content in bioactive molecules and the growing interest in valuable reutilization of waste products. Drawing inspiration from its biological function, here its potential in cosmetic applications was investigated. CS was recovered from one of the largest coffee roasters located in Switzerland and processed through supercritical CO₂ extraction, thereby generating coffee silverskin extract. Chemical profiling of this extract revealed the presence of potent molecules, among which cafestol and kahweol fatty acid esters, as well as acylglycerols, β-sitosterol and caffeine. The CS extract was then dissolved in organic shea butter, yielding the cosmetic active ingredient SLVR'Coffee™. In vitro gene expression studies performed on keratinocytes showed an upregulation of genes involved in oxidative stress responses and skin-barrier functionality upon treatment with the coffee silverskin extract. In vivo, our active protected the skin against Sodium Lauryl Sulfate (SLS)-induced irritation and accelerated its recovery. Furthermore, this active extract improved measured as well as perceived skin hydration in female volunteers, making it an innovative, bioinspired ingredient that comforts the skin and benefits the environment.

Targeting Skin Barrier Function in Atopic Dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease in the general population. Skin barrier dysfunction is the central abnormality leading to AD. The cause of skin barrier dysfunction is complex and rooted in genetic mutations, interactions between the immune pathway activation and epithelial cells, altered host defense mechanisms, as well as environmental influences that cause epithelial cell activation and release of alarmins (such as thymic stromal lymphopoietin) that can activate the type 2 immune pathway, including generation of interleukins 4 and 13, which induces defects in the skin barrier and increased allergic inflammation. These inflammatory pathways are further influenced by environmental factors including the microbiome (especially Staphylococcus aureus), air pollution, stress, and other factors. As such, AD is a syndrome involving multiple phenotypes, all of which have in common skin barrier dysfunction as a key contributing factor. Understanding mechanisms leading to skin barrier dysfunction in AD is pointing to the development of new topical and systemic treatments in AD that helps keep skin borders secure and effectively treat the disease.

Extracellular epimorphin impairs expression and processing of profilaggrin in HaCaT keratinocytes

The expression and processing of filaggrin, a filament-associated protein in the skin epidermis, is closely associated with keratinocyte cornification. The large precursor profilaggrin (Pro-FLG) is initially detected at the granular layer in keratohyalin granules, subsequently processed into 10 to 12 filaggrin monomers (mFLGs) for keratin assembly, and ultimately degraded into smaller peptides that behave as natural moisturizing factor (NMF) at the outermost epidermis. We previously reported that epimorphin (EPM) extruded upon external stimuli severely perturbs epidermal terminal differentiation. Using HaCaT keratinocytes with inducible expression and recombinant EPM and FLG, we investigated the effect of extracellular EPM on the expression profile of filaggrin. As expression and processing of Pro-FLG in primary keratinocytes are accompanied with apoptotic cell death, we employed HaCaT keratinocytes that grow and express filaggrin mRNA in standard culture medium. In response to ectopic stimulation with extracellular EPM, Pro-FLG expression decreased with elimination of keratohyalin granules in the cells, with filaggrin mRNA remained constant and profilaggrin processing was not accelerated. Additionally, using a recombinant form of mFLG engineered for intracellular localization, we found that extracellular EPM hindered proteolytic cleavage of mFLG for production of NMF. Taken together, extracellularly extruded EPM, an epidermal cornification blocker, not only decreases Pro-FLG expression but also reduces the production of NMF in HaCaT keratinocytes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-022-00566-8.

RELEVANCE OF CODING VARIATION IN FILAGGRIN AND DOCK8 IN FINNISH PEDIATRIC PATIENTS WITH EARLY-ONSET MODERATE-TO-SEVERE ATOPIC DERMATITIS

Early-onset, persistent atopic dermatitis (AD) is proposed as a distinct subgroup that may have specific genotypic features. FLG gene loss-of-function variants are the best known genetic factors contributing to epidermal barrier impairment and eczema severity. In a cohort of 140 Finnish children with early-onset moderate-to-severe AD, we investigated the effect of coding variation in FLG and 13 other genes with epidermal barrier or immune function through the use of targeted amplicon sequencing and genotyping. A FLG loss-of-function variant (Arg501Ter, Ser761fs, Arg2447Ter, or Ser3247Ter) was identified in 20 of 140 patients showing higher transepidermal water loss values than patients without these variants. Total FLG loss-of-function variant frequency (7.14%) was significantly higher than in the general Finnish population (2.34%). When tested separately, only Arg2447Ter showed a significant association with AD (P = 0.003104). In addition, a modest association with moderate-to-severe pediatric AD was seen for rs12730241 and rs6587667 (FLG2:Gly137Glu). Loss-of-function variants, previously reported pathogenic variants, or statistically significant enrichment of nonsynonymous coding region variants were not found in the 13 candidate genes studied by amplicon sequencing. However, higher IgE and eosinophil counts were found in carriers of potentially pathogenic DOCK8 missense variants, suggesting that the role of DOCK8 variation in AD should be further investigated in larger cohorts.

Investigations into the filaggrin null phenotype: showcasing the methodology for CRISPR/Cas9 editing of human keratinocytes

Ever since the association between filaggrin (FLG) loss-of-function mutations and ichthyosis vulgaris and atopic dermatitis disease onset was identified, filaggrins function has been under investigation. Intra-individual genomic predisposition, immunological confounders, and environmental interactions complicate the comparison between FLG genotypes and related causal effects. Using CRISPR/Cas9, we generated human FLG knockout (ΔFLG) N/TERT-2G keratinocytes. Filaggrin deficiency was demonstrated by immunohistochemistry of human epidermal equivalent (HEE) cultures. Next to (partial) loss of structural proteins (IVL, HRNR, KRT2, and TGM1), the stratum corneum was more dense and lacked the typical basket weave appearance. In addition, electrical impedance spectroscopy and transepidermal water loss analyses highlighted a compromised epidermal barrier in ΔFLG-HEEs. Correction of FLG reinstated the presence of keratohyalin granules in the stratum granulosum, filaggrin protein expression, and expression of aforementioned proteins. The beneficial effects on stratum corneum formation were reflected by normalization of EIS and TEWL. This study demonstrates the causal phenotypical and functional consequences of filaggrin deficiency, indicating filaggrin is not only central in epidermal barrier function but also vital for epidermal differentiation by orchestrating the expression of other important epidermal proteins. These observations pave the way to fundamental investigations into the exact role of filaggrin in skin biology and disease.

Skin biomarkers predict development of atopic dermatitis in infancy

BACKGROUND

There is currently no insight into biomarkers that can predict the onset of pediatric atopic dermatitis (AD).

METHODS

Nested in a prospective birth cohort study that examined the occurrence of physician-diagnosed AD in 300 children, 44 random children with onset of AD in the first year of life were matched on sex and season of birth with 44 children who did not develop AD. Natural moisturizing factor (NMF), corneocyte surface protrusions, cytokines, free sphingoid bases (SBs) of different chain lengths and their ceramides were analyzed from tape strips collected at 2 months of age before onset of AD using liquid chromatography, atomic force microscopy, multiplex immunoassay, and liquid chromatography mass spectrometry, respectively.

RESULTS

Significant alterations were observed for four lipid markers, with phytosphingosine ([P]) levels being significantly lower in children who developed AD compared with children who did not (median 240 pmol/mg vs. 540 pmol/mg, p < 0.001). The two groups of children differed in the relative amounts of SB of different chain lengths (C17, C18 and C20). Thymus- and activation-regulated chemokine (TARC/CCL17) was slightly higher in children who developed AD, whereas NMF and corneocyte surface texture were similar. AD severity assessed by the eczema area and severity index (EASI) at disease onset was 4.2 (2.0;7.2). [P] had the highest prediction accuracy among the biomarkers (75.6%), whereas the combination of 5 lipid ratios gave an accuracy of 89.4%.

CONCLUSION

This study showed that levels and SB chain length were altered in infants who later developed AD, and that TARC/CCL17 levels were higher.

Epicutaneous Sensitization and Food Allergy: Preventive Strategies Targeting Skin Barrier Repair-Facts and Challenges

Food allergy represents a growing public health and socio-economic problem with an increasing prevalence over the last two decades. Despite its substantial impact on the quality of life, current treatment options for food allergy are limited to strict allergen avoidance and emergency management, creating an urgent need for effective preventive strategies. Advances in the understanding of the food allergy pathogenesis allow to develop more precise approaches targeting specific pathophysiological pathways. Recently, the skin has become an important target for food allergy prevention strategies, as it has been hypothesized that allergen exposure through the impaired skin barrier might induce an immune response resulting in subsequent development of food allergy. This review aims to discuss current evidence supporting this complex interplay between the skin barrier dysfunction and food allergy by highlighting the crucial role of epicutaneous sensitization in the causality pathway leading to food allergen sensitization and progression to clinical food allergy. We also summarize recently studied prophylactic and therapeutic interventions targeting the skin barrier repair as an emerging food allergy prevention strategy and discuss current evidence controversies and future challenges. Further studies are needed before these promising strategies can be routinely implemented as prevention advice for the general population.

Computational modelling predicts impaired barrier function and higher sensitivity to skin inflammation following pH elevation

Skin surface pH has been identified as a key regulator of the epidermal homeostasis through its action on serine protease activity. These enzymes, like kallikreins (KLK), are responsible for the degradation of corneodesmosomes, the protein structures linking together corneocytes, and are regulated by Lympho-Epithelial Kazal-Type-related Inhibitor (LEKTI). KLK activity increases at pH levels higher than physiological. An increase in skin surface pH has been observed in patients suffering from skin diseases characterized by impaired barrier function, like atopic dermatitis. In this work, we introduce an agent-based model of the epidermis to study the impact of a change in skin surface pH on the structural and physiological properties of the epidermis, through the LEKTI-KLK mechanism. We demonstrate that a less acidic pH, compared to the slightly acidic pH observed in healthy skin, is sufficient to significantly affect the water loss at the surface and the amount of irritant permeating through the epidermis. This weakening of the skin barrier function eventually results in a more intense skin inflammation following exposure to an external irritant. This work provides additional evidence that skin surface pH and serine proteases can be therapeutic targets to improve skin barrier integrity.

Malignant T cells induce skin barrier defects through cytokine-mediated JAK/STAT signaling in cutaneous T-cell lymphoma

Cutaneous T-cell lymphoma (CTCL) is a devastating lymphoid malignancy characterized by the accumulation of malignant T cells in the dermis and epidermis. Skin lesions cause serious symptoms that hamper quality of life and are entry sites for bacterial infection, a major cause of morbidity and mortality in advanced diseases. The mechanism driving the pathological processes that compromise the skin barrier remains unknown. Here, we report increased transepidermal water loss and compromised expression of the skin barrier proteins filaggrin and filaggrin-2 in areas adjacent to TOX-positive T cells in CTCL skin lesions. Malignant T cells secrete mediators (including cytokines such as interleukin 13 [IL-13], IL-22, and oncostatin M) that activate STAT3 signaling and downregulate filaggrin and filaggrin-2 expression in human keratinocytes and reconstructed human epithelium. Consequently, the repression of filaggrins can be counteracted by a cocktail of antibodies targeting these cytokines/receptors, small interfering RNA-mediated knockdown of JAK1/STAT3, and JAK1 inhibitors. Notably, we show that treatment with a clinically approved JAK inhibitor, tofacitinib, increases filaggrin expression in lesional skin from patients with mycosis fungoides. Taken together, these findings indicate that malignant T cells secrete cytokines that induce skin barrier defects via a JAK1/STAT3-dependent mechanism. As clinical grade JAK inhibitors largely abrogate the negative effect of malignant T cells on skin barrier proteins, our findings suggest that such inhibitors provide novel treatment options for patients with CTCL with advanced disease and a compromised skin barrier.

Innovations in Therapeutic Improvement of the Cutaneous Microbiome in Children with Atopic Dermatitis

Biofilm is the dominant form of skin microbiota organization that provides adhesion and preservation of microorganisms in the skin micro-environment. It is necessary to ensure epidermal barrier function and local immunomodulation. Staphylococcus aureus becomes the major colonizer of skin lesions in case of atopic dermatitis exacerbation, and it also can form the biofilms. S. aureus growth and biofilm formation due to other microbial commensals on the skin of patients with atopic dermatitis leads to chronic output of pro-inflammatory cytokines and later to abnormalities in healthy skin microbiome. The role of microbial biofilm in human’s health makes the skin microbiota an attractive target for therapeutic intervention in various skin diseases.

Dupilumab significantly improves skin barrier function in patients with moderate-to-severe atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is characterized by abnormal skin lipids that are largely driven by hyperactivated type 2 immune responses. The antibody to the α-subunit of interleukin (IL)-4 receptor, dupilumab, was recently approved to treat AD and demonstrated strong efficacy. However, the role of dupilumab therapy in the regulation of skin barrier structure and function has not been fully explored.

METHODS

We have evaluated the content of lipids and transepidermal water loss (TEWL) in lesional and non-lesional skin of adults and adolescents with moderate-to-severe AD over the course of 16-week treatment with dupilumab and compared those values with that of matched healthy volunteers.

RESULTS

Dupilumab treatment provided a significant decrease in TEWL in AD lesions, lowering it almost to the levels seen in the skin of healthy subjects. Blocking IL-4/IL-13 signaling with dupilumab normalized lipid composition (decreased levels of ceramides with non-hydroxy fatty acids and C18-sphingosine and increased the level of esterified omega-hydroxy fatty acid-containing ceramides) and increased ceramide chain length in lesional as well as non-lesional stratum corneum of AD patients. Partial changes for these parameters were already observed after 2 weeks, with a full response achieved after 8 weeks of dupilumab treatment.

CONCLUSIONS

Inhibition of IL-4/IL-13 signaling by dupilumab allows restoration of skin lipid composition and barrier function in patients with moderate-to-severe AD.

Potential Beneficial Effects of Sargassum spp. in Skin Aging

Seaweeds are receiving much attention as a rich source of bioactive compounds with cosmeceutical potential. Recent studies have revealed that Sargassum spp., a genus of brown algae in the family Sargassaceae, has multiple functions in preventing and improving skin aging. Sargassum spp. contains many bioactive compounds, such as fucoidan, fucoxanthin, terpenoids, flavonoids, and meroterpenoids. These Sargassum spp. extracts and derivative compounds have excellent potential for skincare, as they exhibit skin health-promoting properties, including antioxidants, anti-inflammation, whitening, skin barrier repair, and moisturizing. Therefore, searching for bioactive compounds in marine resources such as Sargassum spp. could be an attractive approach to preventing and improving skin aging. The current review focused on the various biological abilities of Sargassum extracts or derived compounds for anti-skin aging.

Unmet Medical Needs in Chronic, Non-communicable Inflammatory Skin Diseases

An estimated 20-25% of the population is affected by chronic, non-communicable inflammatory skin diseases. Chronic skin inflammation has many causes. Among the most frequent chronic inflammatory skin diseases are atopic dermatitis, psoriasis, urticaria, lichen planus, and hidradenitis suppurativa, driven by a complex interplay of genetics and environmental factors. Autoimmunity is another important cause of chronic skin inflammation. The autoimmune response may be mainly T cell driven, such as in alopecia areata or vitiligo, or B cell driven in chronic spontaneous urticaria, pemphigus and pemphigoid diseases. Rare causes of chronic skin inflammation are autoinflammatory diseases, or rheumatic diseases, such as cutaneous lupus erythematosus or dermatomyositis. Whilst we have seen a significant improvement in diagnosis and treatment, several challenges remain. Especially for rarer causes of chronic skin inflammation, early diagnosis is often missed because of low awareness and lack of diagnostics. Systemic immunosuppression is the treatment of choice for almost all of these diseases. Adverse events due to immunosuppression, insufficient therapeutic responses and relapses remain a challenge. For atopic dermatitis and psoriasis, a broad spectrum of innovative treatments has been developed. However, treatment responses cannot be predicted so far. Hence, development of (bio)markers allowing selection of specific medications for individual patients is needed. Given the encouraging developments during the past years, we envision that many of these challenges in the diagnosis and treatment of chronic inflammatory skin diseases will be thoroughly addressed in the future.

Revisiting the Roles of Filaggrin in Atopic Dermatitis

The discovery in 2006 that loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and can predispose to atopic dermatitis (AD) galvanized the dermatology research community and shed new light on a skin protein that was first identified in 1981. However, although outstanding work has uncovered several key functions of filaggrin in epidermal homeostasis, a comprehensive understanding of how filaggrin deficiency contributes to AD is still incomplete, including details of the upstream factors that lead to the reduced amounts of filaggrin, regardless of genotype. In this review, we re-evaluate data focusing on the roles of filaggrin in the epidermis, as well as in AD. Filaggrin is important for alignment of keratin intermediate filaments, control of keratinocyte shape, and maintenance of epidermal texture via production of water-retaining molecules. Moreover, filaggrin deficiency leads to cellular abnormalities in keratinocytes and induces subtle epidermal barrier impairment that is sufficient enough to facilitate the ingress of certain exogenous molecules into the epidermis. However, although FLG null mutations regulate skin moisture in non-lesional AD skin, filaggrin deficiency per se does not lead to the neutralization of skin surface pH or to excessive transepidermal water loss in atopic skin. Separating facts from chaff regarding the functions of filaggrin in the epidermis is necessary for the design efficacious therapies to treat dry and atopic skin.

Targeting therapeutic approaches and highlighting the potential role of nanotechnology in atopic dermatitis

Atopic dermatitis is a chronic as well as widespread skin disease which has significant influence on the life attributes of affected people and their families. Systemic immunosuppressive drugs can be utilised for effective care of disease, although they are often prescribed for rigorous disruption or disease that is complicated to manage. Therefore, topical applications of corticosteroids are considered the primary pharmacologic therapies for atopic dermatitis, and research recommends that these medications might be helpful in preventing disease flare-ups. However, topical medicine administration to deeper layers of skin is challenging because of the skin anatomic barrier that restricts deeper drug permeation, and also due to barrier function abnormalities in atopic dermatitis skin, which might result in systemic drug absorption, provoking systemic consequences. Hence, effective management of atopic dermatitis needs new, effective, safe and targeted treatments. Therefore, nanotechnology-based topical therapeutics have attracted much interest nowadays because of their tendency to increase drug diffusion and bioavailability along with enormous drug targeting potential to affected cells, and, thereby, reducing the adverse effects of medications. In this review, we mention different symptoms of atopic dermatitis, and provide an overview of the different triggering factors causing atopic dermatitis, with emphasis on its epidemiology, pathophysiology, clinical features and diagnostic, and preventive measures. This review discusses existing therapeutics for treating atopic dermatitis, and the newer approaches as well as the current classical pharmacotherapy of atopic dermatitis against new nanoparticle skin delivery systems. This review has also briefly summarised the recent patents and clinical status of therapeutic modalities for atopic dermatitis.

Type 2 Inflammation Contributes to Skin Barrier Dysfunction in Atopic Dermatitis

Skin barrier dysfunction, a defining feature of atopic dermatitis (AD), arises from multiple interacting systems. In AD, skin inflammation is caused by host-environment interactions involving keratinocytes as well as tissue-resident immune cells such as type 2 innate lymphoid cells, basophils, mast cells, and T helper type 2 cells, which produce type 2 cytokines, including IL-4, IL-5, IL-13, and IL-31. Type 2 inflammation broadly impacts the expression of genes relevant for barrier function, such as intracellular structural proteins, extracellular lipids, and junctional proteins, and enhances Staphylococcus aureus skin colonization. Systemic anti‒type 2 inflammation therapies may improve dysfunctional skin barrier in AD.

The Discovery and Function of Filaggrin

Keratohyalin granules were discovered in the mid-19th century in cells that terminally differentiate to form the outer, cornified layer of the epidermis. The first indications of the composition of these structures emerged in the 1960s from a histochemical stain for histidine, followed by radioautographic evidence of a high incidence of histidine incorporation into newly synthesized proteins in cells containing the granules. Research during the next three decades revealed the structure and function of a major protein in these granules, which was initially called the ‘histidine-rich protein’. Steinert and Dale named the protein ‘filaggrin’ in 1981 because of its ability to aggregate keratin intermediate filaments. The human gene for the precursor, ‘profilaggrin,’ was reported in 1991 to encode 10, 11 or 12 nearly identical repeats. Remarkably, the mouse and rat genes encode up to 20 repeats. The lifetime of filaggrin is the time required for keratinocytes in the granular layer to move into the inner cornified layer. During this transition, filaggrin facilitates the collapse of corneocytes into ‘building blocks’ that become an impermeable surface barrier. The subsequent degradation of filaggrin is as remarkable as its synthesis, and the end-products aid in maintaining moisture in the cornified layer. It was apparent that ichthyosis vulgaris and atopic dermatitis were associated with the absence of this protein. McLean’s team in 2006 identified the cause of these diseases by discovering loss-of-function mutations in the profilaggrin gene, which led to dysfunction of the surface barrier. This story illustrates the complexity in maintaining a healthy, functional epidermis.

Depth-dependent hydration dynamics in human skin: Vehicle-controlled efficacy assessment of a functional 10% urea plus NMF moisturizer by near-infrared confocal spectroscopic imaging (KOSIM IR) and capacitance method complemented by volunteer perception

BACKGROUND

Stratum corneum (SC) hydration is vital for the optimal maintenance and appearance of healthy skin. In this context, we evaluated the efficacy of an NMF-enriched moisturizer containing 10% urea on different aspects of SC hydration of dry skin.

MATERIAL AND METHODS

In two clinical studies, the hydration efficacy of the moisturizer in comparison to its vehicle was investigated. In the first study, 42 subjects applied the moisturizer and the vehicle to one lower leg each. Thirty minutes and 24 h after this single treatment, SC hydration was measured by corneometry. Volunteers also rated skin moisturization and evaluated product properties. In the second study, 27 subjects each treated one forearm twice daily for 2 weeks with the moisturizer and the vehicle. Then, depth-resolved water-absorption spectra were measured by near-infrared confocal spectroscopic imaging (KOSIM IR).

RESULTS

The moisturizer exerted a superior hydrating effect compared to the vehicle. KOSIM IR measurements show that, compared to the vehicle, the moisturizer significantly improved the water gradient in the SC from the surface to a depth of 15 μm. Moreover, the moisturizer received high acceptance ratings from the volunteers and was preferred to the vehicle.

CONCLUSION

The humectants applied in the investigated moisturizer improved SC water content in total and as a function of depth. The combination of depth-resolved data (KOSIM IR) with classical corneometry provides an integrated concept in the measurement of skin hydration, rendering both methods complementary. These findings were in line with the volunteers` self-assessments of the moisturizer properties that are relevant to treatment adherence.

Ni2+-Assisted Hydrolysis May Affect the Human Proteome; Filaggrin Degradation Ex Vivo as an Example of Possible Consequences

Deficiency in a principal epidermal barrier protein, filaggrin (FLG), is associated with multiple allergic manifestations, including atopic dermatitis and contact allergy to nickel. Toxicity caused by dermal and respiratory exposures of the general population to nickel-containing objects and particles is a deleterious side effect of modern technologies. Its molecular mechanism may include the peptide bond hydrolysis in X₁-S/T-c/p-H-c-X₂ motifs by released Ni²⁺ ions. The goal of the study was to analyse the distribution of such cleavable motifs in the human proteome and examine FLG vulnerability of nickel hydrolysis. We performed a general bioinformatic study followed by biochemical and biological analysis of a single case, the FLG protein. FLG model peptides, the recombinant monomer domain human keratinocytes in vitro and human epidermis ex vivo were used. We also investigated if the products of filaggrin Ni²⁺-hydrolysis affect the activation profile of Langerhans cells. We found X₁-S/T-c/p-H-c-X₂ motifs in 40% of human proteins, with the highest abundance in those involved in the epidermal barrier function, including FLG. We confirmed the hydrolytic vulnerability and pH-dependent Ni²⁺-assisted cleavage of FLG-derived peptides and FLG monomer, using in vitro cell culture and ex-vivo epidermal sheets; the hydrolysis contributed to the pronounced reduction in FLG in all of the models studied. We also postulated that Ni-hydrolysis might dysregulate important immune responses. Ni²⁺-assisted cleavage of barrier proteins, including FLG, may contribute to clinical disease associated with nickel exposure.

Barrier Impairment and Type 2 Inflammation in Allergic Diseases: The Pediatric Perspective

Allergic diseases represent a global burden. Although the patho-physiological mechanisms are still poorly understood, epithelial barrier dysfunction and Th2 inflammatory response play a pivotal role. Barrier dysfunction, characterized by a loss of differentiation, reduced junctional integrity, and altered innate defence, underpins the pathogenesis of allergic diseases. Epithelial barrier impairment may be a potential therapeutic target for new treatment strategies Up now, monoclonal antibodies and new molecules targeting specific pathways of the immune response have been developed, and others are under investigation, both for adult and paediatric populations, which are affected by atopic dermatitis (AD), asthma, allergic rhinitis (AR), chronic rhinosinusitis with nasal polyps (CRSwNP), or eosinophilic esophagitis (EoE). In children affected by severe asthma biologics targeting IgE, IL-5 and against IL-4 and IL-13 receptors are already available, and they have also been applied in CRSwNP. In severe AD Dupilumab, a biologic which inhibits both IL-4 and IL-13, the most important cytokines involved in inflammation response, has been approved for treatment of patients over 12 years. While a biological approach has already shown great efficacy on the treatment of severe atopic conditions, early intervention to restore epithelial barrier integrity, and function may prevent the inflammatory response and the development of the atopic march.

Dermatology for the internist: optimal diagnosis and management of atopic dermatitis

Internists are front-line health care providers that commonly provide the first encounter to patients for dermatological conditions, especially atopic dermatitis (AD). Internists need to be comfortable with managing mild-moderate AD in their practices. Criteria and guidelines established in dermatology literature are available to help the general practitioner diagnose and treat AD. AD is a systemic disease associated with multiple cutaneous and extra-cutaneous comorbidities that warrant screening by internists, especially mental health conditions. Environmental factors may play a role in the development or worsening of AD; however, there is currently no strong evidence to guide specific population- or clinic-based interventions for their avoidance. While food allergies are common in AD patients, the role of food allergens as an exacerbating factor for AD is controversial. Before starting any dietary modifications, careful evaluation should be performed by an allergist. If the patient is not well-controlled despite adequate topical therapies or is experiencing severe/worsening disease, early referral to dermatology is warranted to rule out confounding diagnoses and/or escalation to systemic therapies. Finally, it is important to recognise the racial disparities present in AD and address these when formulating treatment plans.Key messages:Confounding dermatoses, either instead of or in addition to AD, should be considered in treatment-refractory AD, and the appropriate workup may be initiated while awaiting dermatology referral.AD patients have multiple cutaneous and extra-cutaneous comorbidities that warrant screening by internists, especially mental health conditions.

Filaggrin mutations in relation to skin barrier and atopic dermatitis in early infancy

BACKGROUND

Loss-of-function mutations in the skin barrier gene filaggrin (FLG) increase the risk of atopic dermatitis (AD), but their role in skin barrier function, dry skin and eczema in infancy is unclear.

OBJECTIVES

To determine the role of FLG mutations for impaired skin barrier function, dry skin, eczema and AD at three months of age and through infancy.

METHODS

FLG mutations were analyzed in 1836 infants in the Scandinavian population-based PreventADALL study. Transepidermal water loss (TEWL), dry skin, eczema and AD were assessed at three, six and 12 months of age.

RESULTS

Filaggrin mutations were observed in 166 (9%) infants. At three months, carrying FLG mutations was not associated with impaired skin barrier function (TEWL > 11.3 g/m² /h) or dry skin, but with eczema (OR(95%CI): 2.76 (1.81, 4.23), p < 0.001). At six months, mutation carriers had significantly higher TEWL than non-mutation carriers (mean (95%CI) 9.68 (8.69, 10.68) vs. 8.24 (7.97, 8.15), p < 0.01) and at three and six months an increased risk of dry skin on truncus (OR: 1.87 (1.25, 2.80), p = 0.002; 2.44 (1.51, 3.95), p < 0.001) or extensor limb surfaces (1.52 (1.04, 2.22), p = 0.028; 1.74 (1.17, 2.57), p = 0.005). FLG mutations were associated with eczema and AD in infancy.

CONCLUSION

Filaggrin mutations were not associated with impaired skin barrier function or dry skin in general at three months of age, but increased the risk for eczema, as well as for dry skin on truncus and extensors at three and six months.

A Biomimetic Combination of Actives Enhances Skin Hydration and Barrier Function via Modulation of Gene Expression: Results of Two Double-Blind, Vehicle-Controlled Clinical Studies

INTRODUCTION

Xerosis cutis is characterized by a decreased stratum corneum (SC) hydration and an impaired skin barrier function. Urea, the most prevalent natural moisturizing factor (NMF), is currently considered the gold standard. Its efficacy can further be increased by combining urea with other NMF and skin barrier lipids (SBLs).

OBJECTIVE

We set out to evaluate physiological effects of a novel functional moisturizer containing 10% urea, additional NMF components, and a combination of SBLs on skin hydration and skin barrier integrity on a cellular and phenotypic level in female volunteers suffering from xerosis.

METHODS

Two double-blind, vehicle-controlled clinical studies were conducted. In the first study, 44 female subjects having very dry body skin applied the moisturizer or its vehicle twice daily to their volar forearms. Twenty-four hours after a single product application as well as 24 h after 2 weeks of treatment, SC hydration was measured by corneometry. Skin barrier function was assessed by transepidermal water loss 24 h and 48 h after 2 weeks of regular use. Twenty-four hours after 2 weeks of application, skin tape stripping was performed, and urea content was determined in the 3rd strip by means of high-performance liquid chromatography/tandem mass spectrometry. In the second study, 22 women with self-reported very dry skin applied the moisturizer or vehicle twice daily to their volar forearms for 2 weeks. Then, suction blister samples were obtained for gene expression analysis using RT-PCR.

RESULTS

Application of the actives led to significantly improved skin hydration and barrier function at all points in time. Compared to the vehicle, application of the moisturizer for 2 weeks resulted in a significant increase in SC urea content. Relative gene expression data revealed significant upregulation of genes associated with skin barrier function, hydration, differentiation, and lipid metabolism compared to the vehicle-treated area.

CONCLUSIONS

Overall, our data demonstrate that the functional moisturizer provides an adequate bioavailability of urea and a beneficial biophysical impact on xerotic skin. Topical treatment with a combination of urea and additional NMF as well as SBL can modify mRNA expression of important epidermal genes stimulating cellular processes and functions. The well-tolerated novel functional moisturizer stimulates molecular mechanisms involved in skin hydration and barrier function and is a profoundly effective treatment option for xerosis cutis.

Partially Hydrolysed Whey-Based Infant Formula Improves Skin Barrier Function

Specific partially hydrolysed whey-based infant formulas (pHF-W) have been shown to decrease the risk of atopic dermatitis (AD) in infants. Historically, AD has been associated primarily with milk allergy; however, defective skin barrier function can be a primary cause of AD. We aimed to ascertain whether oral supplementation with pHF-W can improve skin barrier function. The effect of pHF-W was assessed on transepidermal water loss (TEWL) and antibody productions in mice epicutaneously exposed to Aspergillus fumigatus. Human primary keratinocytes were stimulated in vitro, and the expression of genes related to skin barrier function was measured. Supplementation with pHF-W in neonatal mice led to a significant decrease in TEWL and total IgE, but not in allergen-specific antibody levels. The whey hydrolysate was sufficient to decrease both TEWL and total IgE. Aquaporin-3 gene expression, linked with skin hydration, was modulated in the skin of mice and human primary keratinocytes following protein hydrolysate exposure. Skin barrier improvement may be an additional mechanism by which pHF-W may potentially reduce the risk of AD development in infants. Further human studies are warranted to confirm the clinical efficacy of these observations.

Filaggrin-gene mutation has minimal effect on the disease severity in the lesions of atopic dermatitis

Loss-of-function mutations of filaggrin (FLG) gene (FLG) are the strongest known genetic risk factor for atopic dermatitis (AD). It is still debatable how FLG gene mutations and the resulting abnormal amount of FLG protein contribute to skin barrier function and symptoms of AD. In this study, we examined the effects of loss-of-function mutations of FLG gene on the severity of skin lesions and skin barrier function in 55 patients with AD by evaluating eight patients with AD with FLG gene mutations and 47 patients with AD without mutations. The results showed that the FLG gene mutation did not affect the duration of AD, severity of AD, degree of local inflammatory symptoms, skin water content and trans-epidermal water loss of the lesions. Next, in these eight mutation carriers and the 47 non-carriers, stratum corneum was collected from the three site of skin lesions using tape-stripping method, and the amounts of FLG protein and total amino acid contained in the stratum corneum was measured to investigate the effect of the FLG gene mutation on the amount of FLG gene product in the local lesion. FLG abnormalities had little effect on FLG protein and total amino acid content in the stratum corneum in the lesional skin. The amount of the FLG products, especially amino acids derived from FLG, in the stratum corneum of AD lesional skin is influenced by development of dermatitis. The results obtained from this study supports that the activation of Th2-dominant inflammatory cells, together with FLG abnormality, plays a role in suppressing the production of FLG in skin lesions.

Edible Bird's Nest, an Asian Health Food Supplement, Possesses Moisturizing Effect by Regulating Expression of Filaggrin in Skin Keratinocyte

Edible bird's nest (EBN) has been consumed as a Chinese delicacy for hundreds of years; the functions of which have been proposed to prevent lung disease, strengthen immune response, and restore skin youthfulness. To support the skin function of EBN, the water extract and the enzymatic digest of EBN with enriched digested peptides were tested in cultured keratinocyte, HaCaT cell line. The effects of EBN extract and digest in inducing proteins crucial for skin moisturizing were determined in both in vitro and ex vivo models. In cultured keratinocytes, the expressions of S100-fused type proteins contributing to skin barrier function in the stratum corneum, e.g. filaggrin and filaggrin-2, were determined in both mRNA and protein levels, which were markedly induced in the treatment of EBN extract or digest. The EBN-induced gene transcriptions of filaggrin and filaggrin-2 were mediated by activation of p38 MAPK pathway and various transcription factors, e.g. GATA3, PPARα, PPARβ, and PPARγ: these transcriptional factors were markedly activated by the digested products of EBN, as compared to the extract, in cultured keratinocytes. By using atomic force microscopy (AFM), the EBN-treated keratinocyte was shown to have more liquid-like morphology, as compared to a control cell. The EBN digest showed better induction on these moisturizing effects as compared to the extract. These lines of evidence therefore suggested the water moisturizing effect of EBN in skin function.

New Treatments for Atopic Dermatitis Targeting Skin Barrier Repair via the Regulation of FLG Expression

Atopic dermatitis (AD) is one of the most common chronic, inflammatory skin disorders with a complex etiology and a broad spectrum of clinical phenotypes. Despite its high prevalence and effect on the quality of life, safe and effective systemic therapies approved for long-term management of AD are limited. A better understanding of the pathogenesis of atopic dermatitis in recent years has contributed to the development of new therapeutic approaches that target specific pathophysiological pathways. Skin barrier dysfunction and immunological abnormalities are critical in the pathogenesis of AD. Recently, the importance of the downregulation of epidermal differentiation complex (EDC) molecules caused by external and internal stimuli has been extensively emphasized. The purpose of this review is to discuss the innovations in the therapy of atopic dermatitis, including biologics, small molecule therapies, and other drugs by highlighting regulatory mechanisms of skin barrier-related molecules, such as filaggrin (FLG) as a crucial pathway implicated in AD pathogenesis.

Dominant atopy risk mutations identified by mouse forward genetic analysis

BACKGROUND

Atopy, the overall tendency to become sensitized to an allergen, is heritable but seldom ascribed to mutations within specific genes. Atopic individuals develop abnormally elevated IgE responses to immunization with potential allergens. To gain insight into the genetic causes of atopy, we carried out a forward genetic screen for atopy in mice.

METHODS

We screened mice carrying homozygous and heterozygous N-ethyl-N-nitrosourea (ENU)-induced germline mutations for aberrant antigen-specific IgE and IgG1 production in response to immunization with the model allergen papain. Candidate genes were validated by independent gene mutation.

RESULTS

Of 31 candidate genes selected for investigation, the effects of mutations in 23 genes on papain-specific IgE or IgG1 were verified. Among the 20 verified genes influencing the IgE response, eight were necessary for the response, while 12 repressed IgE. Nine genes were not previously implicated in the IgE response. Fifteen genes encoded proteins contributing to IgE class switch recombination or B-cell receptor signaling. The precise roles of the five remaining genes (Flcn, Map1lc3b, Me2, Prkd2, and Scarb2) remain to be determined. Loss-of-function mutations in nine of the 12 genes limiting the IgE response were dominant or semi-dominant for the IgE phenotype but did not cause immunodeficiency in the heterozygous state. Using damaging allele frequencies for the corresponding human genes and in silico simulations (Monte Carlo) of undiscovered atopy mutations, we estimated the percentage of humans with heterozygous atopy risk mutations.

CONCLUSIONS

Up to 37% of individuals may be heterozygous carriers for at least one dominant atopy risk mutation.

Staphylococcal Communities on Skin Are Associated with Atopic Dermatitis and Disease Severity

The skin microbiota of atopic dermatitis (AD) patients is characterized by increased Staphylococcus aureus colonization, which exacerbates disease symptoms and has been linked to reduced bacterial diversity. Skin bacterial communities in AD patients have mostly been described at family and genus levels, while species-level characterization has been limited. In this study, we investigated the role of the bacteria belonging to the Staphylococcus genus using targeted sequencing of the tuf gene with genus-specific primers. We compared staphylococcal communities on lesional and non-lesional skin of AD patients, as well as AD patients with healthy controls, and determined the absolute abundance of bacteria present at each site. We observed that the staphylococcal community, bacterial alpha diversity, and bacterial densities were similar on lesional and non-lesional skin, whereas AD severity was associated with significant changes in staphylococcal composition. Increased S. aureus, Staphylococcus capitis, and Staphylococcus lugdunensis abundances were correlated with increased severity. Conversely, Staphylococcus hominis abundance was negatively correlated with severity. Furthermore, S. hominis relative abundance was reduced on AD skin compared to healthy skin. In conclusion, various staphylococcal species appear to be important for skin health.

Atopic dermatitis epidemiology and unmet need in the United Kingdom

Atopic dermatitis (AD), also known as atopic eczema, is a chronic inflammatory skin condition associated with a significant health-related and socioeconomic burden, and is characterized by intense itch, disruption of the skin barrier, and upregulation of type 2-mediated immune responses. The United Kingdom (UK) has a high prevalence of AD, affecting 11-20% of children and 5-10% of adults. Approximately 2% of all cases of childhood AD in the UK are severe. Despite this, most AD treatments are performed at home, with little contact with healthcare providers or services. Here, we discuss the course of AD, treatment practices, and unmet need in the UK. Although the underlying etiology of the disease is still emerging, AD is currently attributed to skin barrier dysfunction and altered inflammatory responses. Management of AD focuses on avoiding triggers, improving skin hydration, managing exacerbating factors, and reducing inflammation through topical and systemic immunosuppressants. However, there is a significant unmet need to improve the overall management of AD and help patients gain control of their disease through safe and effective treatments. Approaches that target individual inflammatory pathways (e.g. dupilumab, anti-interleukin (IL)-4 receptor α) are emerging and likely to provide further therapeutic opportunities for patient benefit.

Mutations of filament-aggregating protein gene in Romanian children diagnosed with atopic dermatitis

Association of atopic dermatitis (AD) and several mutations of various genes of the immune system, in particular filament-aggregating protein gene (FLG) has been investigated in many studies. The association between defective FLG and AD in the Romanian population has not been assessed or published. The present study focused on the genetic background of AD, aiming to assess the prevalence of FLG mutations in Romanian patients with AD. Genetic background of AD was tested for common FLG-mutations: R501X, 2282del4, S3247X and R2447X. The study involved 48 Romanian Caucasian children aged between two months and six years diagnosed with AD, and 48 healthy volunteers; DNA extraction involved 50% of the patients to give samples by using buccal swabs and 50% by collection of whole blood samples. Genetic predisposition was evaluated based on family history, atopy history and profilaggrin genotyping. DNA extracted from blood samples was adequate to study FLG mutations, although no mutation was identified. Genetic factors do not have a unique critical role in AD; therefore, environmental factors unquestionably play an important role in this disease, but the clear-cut part that these factors trigger toward increasing the risk of AD in childhood is still obscure.

Role of Antimicrobial Peptides in Skin Barrier Repair in Individuals with Atopic Dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease that exhibits a complex interplay of skin barrier disruption and immune dysregulation. Patients with AD are susceptible to cutaneous infections that may progress to complications, including staphylococcal septicemia. Although most studies have focused on filaggrin mutations, the physical barrier and antimicrobial barrier also play critical roles in the pathogenesis of AD. Within the physical barrier, the stratum corneum and tight junctions play the most important roles. The tight junction barrier is involved in the pathogenesis of AD, as structural and functional defects in tight junctions not only disrupt the physical barrier but also contribute to immunological impairments. Furthermore, antimicrobial peptides, such as LL-37, human b-defensins, and S100A7, improve tight junction barrier function. Recent studies elucidating the pathogenesis of AD have led to the development of barrier repair therapy for skin barrier defects in patients with this disease. This review analyzes the association between skin barrier disruption in patients with AD and antimicrobial peptides to determine the effect of these peptides on skin barrier repair and to consider employing antimicrobial peptides in barrier repair strategies as an additional approach for AD management.

Research Progress in Atopic March

The incidence of allergic diseases continues to rise. Cross-sectional and longitudinal studies have indicated that allergic diseases occur in a time-based order: from atopic dermatitis and food allergy in infancy to gradual development into allergic asthma and allergic rhinitis in childhood. This phenomenon is defined as the "atopic march". Some scholars have suggested that the atopic march does not progress completely in a temporal pattern with genetic and environmental factors. Also, the mechanisms underlying the atopic march are incompletely understood. Nevertheless, the concept of the atopic march provides a new perspective for the mechanistic research, prediction, prevention, and treatment of atopic diseases. Here, we review the epidemiology, related diseases, mechanistic studies, and treatment strategies for the atopic march.

Stratum Corneum Biomarkers in Atopic Dermatitis: Biological and Spatial Variability

Background:

Atopic dermatitis is a highly heterogeneous skin disease, mainly affecting children. Introduction of biological therapies has urged the development of biomarkers to facilitate personalized therapy. Stratum corneum biomarkers emerged as a promising non-invasive alternative to skin biopsy, yet validation of spatial and biological variability is essential for their application in clinical research.

Objective:

To assess spatial and biological variability of stratum corneum biomarkers for atopic dermatitis.

Methods:

Stratum corneum was collected from 17 atopic dermatitis patients by consecutive application of eight adhesive tapes to a lesional skin site and 2 cm and 4 cm from the lesion. Two non-lesional sites at a 2 cm distance from the same lesion were collected to determine biological variability. Filaggrin degradation products (NMF) were determined by liquid chromatography and thirteen cytokines (IL-4, IL-13, IL-18, IL-31, IL-33, CCL17, CCL22, CCL27, CXCL8, IL-1α, IL-RA, IL-18, IL-22) by multiplex immunoassay.

Results:

Biomarker levels showed gradual changes from lesional to non-lesional skin sites at 2 cm and 4 cm; magnitude and direction of change were biomarker-specific. Intra-subject variability ranged from 17.3% (NMF) to 85.1% (CXCL8). Biomarker levels from two stratum corneum depths were highly correlated; several biomarkers showed significant depth dependence.

Conclusion:

Stratum corneum enables non-invasive collection of relevant immune and epidermal biomarkers, but biomarker-specific spatial and biological variability emphasizes the importance of standardized procedures for stratum corneum collection.