Skin Barrier Dysfunction Research Articles

An OX-Tra'Ordinary Tale: The Role of OX40 and OX40L in Atopic Dermatitis.

The transmembrane glycoprotein OX40 receptor (OX40) and its ligand, OX40L, are instrumental modulators of the adaptive immune response in humans. OX40 functions as a costimulatory molecule that promotes T cell activation, differentiation, and survival through ligation with OX40L. T cells play an integral role in the pathogenesis of several inflammatory skin conditions, including atopic dermatitis (AD). In particular, T helper 2 (TH2) cells strongly contribute to AD pathogenesis via the production of cytokines associated with type 2 inflammation (e.g., IL-4, IL-5, IL-13, and IL-31) that lead to skin barrier dysfunction and pruritus. The OX40-OX40L interaction also promotes the activation and proliferation of other T helper cell populations (e.g., TH1, TH22, and TH17), and AD patients have demonstrated higher levels of OX40 expression on peripheral blood mononuclear cells than healthy controls. As such, the OX40-OX40L pathway is a potential target for AD treatment. Novel therapies targeting the OX40 pathway are currently in development, several of which have demonstrated promising safety and efficacy results in patients with moderate-to-severe AD. Herein, we review the function of OX40 and the OX40-OX40L signaling pathway, their role in AD pathogenesis, and emerging therapies targeting OX40-OX40L that may offer insights into the future of AD management.

Risk factors of skin barrier dysfunction in older adults: A systematic review.

Skin barrier dysfunction can trigger various skin disorders in older adults. Skin barrier assessment is essential for nurses and caregivers to prevent skin disorders; however, the evidence available for clinical assessment is limited. This systematic review aimed to clarify the risk factors of skin barrier dysfunction in older adults. This review adhered to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The four databases were searched using multiple terms related to "aged" and "skin barrier." The search was initially run on April 19, 2023, and rerun on October 12, 2023. Peer-reviewed quantitative studies in English were included, with no publication time limit being set. Two reviewers assessed the risk of bias in a blinded and independent manner using JBI tools. Owing to the heterogeneity of the results, a narrative synthesis was performed. Among the database-identified 4833 studies, 20 studies were included. The extracted factors were categorized as demographic characteristics, functional characteristics, chronic diseases, nutritional status, skin condition, and environmental factors. However, owing to high risk of bias and inconsistent results across studies, only chronic kidney disease and dry skin were considered risk factors for skin barrier dysfunction in older adults. Assessment of chronic kidney disease and dry skin in daily skin care may guide the development of personalized skincare programs to maintain skin integrity in older adults. Furthermore, cohort studies that consider confounding factors and the reliability of measurements are needed for an in-depth investigation into skin barrier dysfunction and more risk factors.

Sweat Protects against Contact Hypersensitivity: Transient Sweat Suppression Compromises Skin Barrier Function in Mice

Although subtle barrier defects may facilitate allergen penetration, thereby enabling allergic sensitization, the relationship between sweating disturbance and skin barrier function is unknown. However, many studies on contact hypersensitivity in mice examined ear skin, which does not sweat, instead of the footpad, where sweating is uniquely present. In this study, we assessed whether sweat suppression in the footpad before hapten application provoked a skin barrier abnormality and reduced inflammatory thresholds to topical haptens. Mice without any genetic skin barrier dysfunction displayed markedly reduced inflammatory thresholds to haptens under transient sweat suppression before hapten application. Epicutaneously applied haptens penetrated the skin more robustly in the presence of sweat suppression compared with that in its absence, although this increase was abolished by exposure to high-humidity conditions. These mice displayed a subtle atopic dermatitis-like inflammation mediated by type 2 response-dominant inflammation and increased IgE responses, mimicking some events occurring in nonlesional atopic dermatitis skin in humans and in murine models. These lesions were dramatically attenuated by exposure to high-humidity conditions. In our model, hapten sensitization does not require mechanical injury, explaining why sensitization occurs through nonlesional atopic dermatitis skin. Awareness of the importance of preserving sweating responses is essential to prevent occupational contact dermatitis and atopic dermatitis.

Associations between interleukin-13, interleukin-4 and their receptor gene polymorphisms and susceptibility to atopic dermatitis in a Chinese Han population.

Background Atopic dermatitis (AD) is a common skin condition that occurs due to a combined effect of immune dysregulation, skin barrier dysfunction, changes in the cutaneous microbiome, and genetic factors. Recent data from both clinical trials and real-world studies indicate that dupilumab, a biological agent that inhibits interleukin 4 receptor-α is an effective drug in the treatment of AD, which further suggests the important role of IL-13 and IL-4 in the pathogenesis of AD. Objectives To assess the association between gene polymorphisms of IL-13, IL-13 receptor, IL-4, and IL-4 receptor and susceptibility to AD. Methods The single nucleotide polymorphisms (SNPs) of the above-mentioned genes were detected by single base extension (SNaPshot) assay. The association between these SNPs and AD risk was analysed using SPSS software. Results Two hundred and seventy-one subjects including 130 patients with AD and 141 healthy controls were enrolled. There were statistical differences between AD patients and controls in genotype distribution at rs2265753, rs6646259, and rs2254672 of the IL-13 receptor gene (P all < 0.001). Subjects with CG at rs2265753, AG at rs6646259 and TG at rs2254672 had increased risks for AD (P all < 0.001), and subjects with GG at rs2265753, rs6646259, and rs2254672 had reduced risks for AD (P all < 0.001). Limitation This was a single-centre and single-race study, with a relatively small sample size. Conclusions Findings from this study show that rs2265753, rs6646259 and rs2254672 of the IL-13 receptor gene are associated with susceptibility to AD.

Topical steroids or emollients: does order matter?

Topical corticosteroids, topical steroid-sparing agents, and emollients are all used to treat atopic dermatitis. However, there are no formal guidelines dictating the order and timing in which these topical modalities should be applied. Additionally, the order of application may change drug absorption, efficacy, and distribution. This is especially important for patients with atopic dermatitis. These patients have a dysfunctional skin barrier, which can lead to greater systemic absorption of drugs. Moreover, children already have an increased rate of systemic absorption due to a higher ratio of body surface area to body weight. Thus, the order of application of topical regimens is of the utmost importance in pediatric dermatology. This manuscript presents an updated review of the literature with a focus on guiding clinicians toward the best practices from the available resources.

The Role of Extracellular Vesicles in Atopic Dermatitis.

Atopic dermatitis, or eczema, is the most common chronic skin disorder, characterized by red and pruritic lesions. Its etiology is multifaceted, involving an interplay of factors, such as the allergic immune response, skin barrier dysfunction, and dysbiosis of the skin microbiota. Recent studies have explored the role of extracellular vesicles (EVs), which are lipid bilayer-delimitated particles released by all cells, in atopic dermatitis. Examination of the available literature identified that most studies investigated EVs released by Staphylococcus aureus, which were found to impact the skin barrier and promote the release of cytokines that contribute to atopic dermatitis development. In addition, EVs released by the skin fungus, Malassezia sympodialis, were found to contain allergens, suggesting a potential contribution to allergic sensitization via the skin. The final major finding was the role of EVs released by mast cells, which were capable of activating various immune cells and attenuating the allergic response. While research in this area is still in its infancy, the studies examined in this review provide encouraging insights into how EVs released from a variety of cells play a role in both contributing to and protecting against atopic dermatitis.

Oral Administration of Apple Pectin Solution Improves Atopic Dermatitis in a Mouse Model.

The development of atopic dermatitis (AD) involves multiple factors. Three such factors are particularly important in AD onset: immune abnormalities, skin barrier dysfunction, and itching. Many studies report that an imbalance between helper T (Th)1 and Th2 cells causes AD. Apple pectin, a prebiotic, has preventative effects in other allergic diseases (e.g., bronchial asthma and AD), but its potential benefits in AD are unclear. In this study, we investigated the effect of oral apple pectin administration on skin inflammation in an AD mouse model and examined changes in T cells involved in AD. To induce AD, a picryl chloride solution was applied to the shaved back skin of male NC/Nga mice. AD mice then received an oral apple pectin solution (0.4% or 4%) for 35 d. Compared with untreated AD mice, mice in both apple pectin-treated groups showed improvement in AD-induced inflammation and skin symptoms. Histological evaluation showed that apple pectin treatment attenuated epidermal thickening and decreased the number of mast cells and CD4+ cells in AD-induced mice. Apple pectin treatment also reduced serum IgE concentration, as well as expression of the inflammation indicator cyclooxygenase-2 and the Th2-related factors thymic stromal lymphopoietin, interleukin-4, and GATA3. Additionally, increased mRNA expression of the genes that encode interferon-γ and T-bet, which are Th1-related factors, and forkhead box protein P3, were observed in the apple pectin-treated groups. Our findings suggest that apple pectin treatment ameliorates AD by increasing regulatory T cells and improving the Th1/Th2 balance in the skin of AD model mice.

Pyromeconic acid-enriched Erigeron annuus water extract as a cosmetic ingredient for itch relief and anti-inflammatory activity

Erigeron annuus (EA), traditionally used to treat disorders such as diabetes and enteritis, contains a variety of chemicals, including caffeic acid, flavonoids, and coumarins, providing antifungal and antioxidative benefits. However, the ingredients of each part of the EA vary widely, and there are few reports on the functionality of water extracts in skin inflammation and barrier protection. We assessed the therapeutic properties of the extract of EA without roots (EEA) and its primary ingredient, pyromeconic acid (PA), focusing on their antihistamine, anti-inflammatory, and antioxidative capabilities using HMC-1(human mast cells) and human keratinocytes (HaCaT cells). Our findings revealed that histamine secretion, which is closely related to itching, was notably reduced in HMC-1 cells following pretreatment with EEA (0.1% and 0.2%) and PA (corresponding concentration, 4.7 of 9.4 µg/mL). Similarly, they led to a marked decrease in the levels of pro-inflammatory cytokines, including IL-1β, IL-8, IL-6, and IFN-γ. Furthermore, EA and PA enhanced antioxidant enzymes, such as superoxide dismutase (SOD) and catalase (CAT), reduced malondialdehyde (MDA) production, and showed reactive oxygen species (ROS) scavenging activity in HaCaT cells. Moreover, at the molecular level, elevated levels of the pro-inflammatory cytokines IL-1β, IL-6, TARC, and MDC induced by TNF-α/IFN-γ in HaCaT cells were mitigated by treatment with EEA and PA. We also revealed the protective effects of EEA and PA against SDS-induced skin barrier dysfunction in HaCaT cells by enhancing the expression of barrier-related proteins. Using NanoString technology, a comprehensive analysis of gene expression changes indicated significant modulation of autoimmune and inflammatory genes by EEA and PA. In summary, this study suggests that EEA and the corresponding concentration of PA as an active ingredient have functional cosmetic applications to alleviate itching and improve skin health.

Investigating genomic diversity of Staphylococcus aureus associated with pediatric atopic dermatitis in South Africa.

Staphylococcus aureus frequently colonizes the skin and nose of patients with atopic dermatitis (AD), a disease associated with skin barrier dysfunction and chronic cutaneous inflammation. Published genomic studies on AD-associated S. aureus in pediatric populations in sub-Saharan Africa are limited. To investigate the phenotypic and genomic diversity of S. aureus in children with and without AD during early childhood. A cross-sectional study of 220 children (aged 9-38 months) with AD (cases) and without AD (controls) from Cape Town and Umtata, South Africa. S. aureus phenotypic and genomic diversity were investigated using whole-genome sequencing, antibiotic susceptibility testing and biofilm microtiter assay. Of the 124 S. aureus isolates recovered from 220 children, 96 isolates (79 cases and 17 controls) with high-quality sequences were analyzed. Isolates from cases showed greater phenotypic resistance to gentamicin (10%), rifampicin (4%), chloramphenicol (4%), and exhibited multidrug resistance (9%) than in controls. Furthermore, the isolates from cases formed stronger biofilms than those from controls (76% vs. 35%, p = 0.001), but showed no dominance of any virulence factor gene or mobile genetic elements. There was no significant difference in the distribution of immune evasion cluster types between cases and controls. However, IEC type G was identified only among cases. AD-associated S. aureus has phenotypic and genetic features that are important for successful pathogenic colonization and survival. Further studies are needed to assess the pathological implications of colonization of various S. aureus lineages in vivo to elucidate their pathological contribution to AD pathogenesis and pathophysiology.

Suppressive effect of Yokukansan on glutamate released from canine keratinocytes.

Canine atopic dermatitis (CAD) is caused by skin barrier dysfunction due to allergen exposure. Excessive glutamate release in the skin is associated with delayed skin barrier function recovery and epidermal thickening and lichenification. Treatment with Yokukansan (YKS), a traditional Japanese medicine, reduces dermatitis severity and scratching behavior in NC/Nga mice by decreasing epidermal glutamate levels. However, the association between canine keratinocytes and glutamate and the mechanism by which YKS inhibits glutamate release from keratinocytes remains unknown. We aimed to investigate glutamate release from canine progenitor epidermal keratinocytes (CPEKs) and the inhibitory effect of YKS on this release. We also explored the underlying mechanism of YKS to enable its application in CAD treatment. Glutamate produced from CPEKs in the medium at 24 hours was measured. The measurement conditions varied in terms of cell density and YKS concentration. CPEKs were treated with a glutamate receptor antagonist (MK-801), a glutamate transporter antagonist (THA), and a glutamate dehydrogenase inhibitor (epigallocatechin gallate; EGCG), and the inhibitory effect of YKS, YKS + THA, MK-801, and EGCG on this release was determined. MK-801 and glutamate dehydrogenase inhibitor were tested alone, and THA was tested in combination with YKS. Finally, glutamine incorporated into CPEKs at 24 hours was measured using radioisotope labeling. CPEKs released glutamate in a cell density-dependent manner, inhibited by YKS in a concentration-dependent manner. Moreover, YKS reduced the intracellular uptake of radioisotope-labeled glutamine in a concentration-dependent manner. No involvement of glutamate receptor antagonism or activation of glutamate transporters was found, as suggested by previous studies. In addition, EGCG could inhibit glutamate release from CPEKs. Our findings indicated that glutamate release from CPEKs could be effectively inhibited by YKS, suggesting the utility of YKS in maintaining skin barrier function during CAD. In addition, CPEKs are appropriate for analyzing the mechanism of YKS. However, we found that the mechanism of action of YKS differs from that reported in previous studies, suggesting that it may have had a similar effect to EGCG in this study. Further research is warranted to understand the exact mechanism and clinical efficacy in treating CAD.

Contact sensitization in pediatric patients with atopic dermatitis: a purpose for a new patch testing series for the Portuguese population.

Background. Atopic dermatitis is a prevalent condition in the pediatric population, with affected children exhibiting a susceptibility to cutaneous sensitization due to skin barrier dysfunction and immune dysregulation. Recent studies have highlighted an increased prevalence of certain allergens, which identifi-cation may be clinically relevant, with direct implications for the management of atopic dermatitis. Methods. We retrospective reviewed pediatric patients patch tested due to suspected contact dermatitis. Patients were divided according the diagnosis of AD, with subsequent comparison of positive results for both groups. Results. A total of 145 pediatric patch testing were analyzed, 44.1% (n = 63) with the diagnosis of atopic dermatitis. There were notable differences in sensitization rates of relevant allergens between groups and when compared to other European studies. Based on the most prevalent and relevant allergens, we proposed an adapted hapten series for assessing portuguese pediatric patients with AD and suspicion of concomitant allergic contact dermatitis. Conclusions. Our findings confirmed the geograph-ic sensitization variability and emphasize the need for pediatric adaptation and "individualized baseline series".

Rosacea pathogenesis and therapeutics: current treatments and a look at future targets.

Rosacea is a chronic inflammatory skin condition associated with a significant health and economic burden from costs and loss of productivity due to seeking medical treatment. The disease encompasses multiple phenotypic manifestations involving a complex and multi-variate pathogenesis. Although the pathophysiology of rosacea is not completely understood, ongoing research is continually elucidating its mechanisms. In this review, current concepts of rosacea pathogenesis will be addressed which involve skin barrier and permeability dysfunction, the innate and adaptive immune systems, and the neurovascular system. More specifically, the cathelicidin pathway, transient potential receptor channels, mast cells, and the NLRP3 inflammasome pathway are various targets of current pharmacologic regimens. Future therapies may seek different mechanisms to act on current treatment targets, like the potential use of JAK/STAT inhibitors in ameliorating skin barrier dysfunction or TLR antagonists in alleviating cathelicidin mediated inflammation. Other potential treatments aim for entirely different molecular targets such as microvesicle particle mediated local and systemic inflammation. Ultimately rosacea is associated with a significant health and economic burden which warrants deeper research into its pathogenesis and resultant new treatment discovery.

Dupilumab normalizes correlates of lysosomal function in atopic dermatitis

AbstractBackgroundAtopic dermatitis (AD) is characterized by skin barrier dysfunction and immune dysregulation. Autophagy, which is important for the epidermal differentiation, is impaired in AD. The treatment with dupilumab, an interleukin (IL)‐4/IL‐13 receptor blocker, has been shown to reduce skin inflammation and restore the skin barrier.ObjectivesThis study aimed to investigate the effect of dupilumab on the expression of key proteins involved in autophagy and lysosomal degradation.MethodsWe performed immunofluorescence staining and microscopic analyses of skin specimens of AD patients, taken before and under (6–10 weeks) therapy with dupilumab, to investigate the expression of autophagy‐related (ATG) 5 and ATG7 proteins, beclin‐1, microtubule‐associated protein light chain 3 (LC3B), sequestosome‐1 (p62), lysosomal proteases (cathepsins B, D and L), serine protease inhibitors (SERPINB3, SERPINB4) as well as IL‐33 and thymic stromal lymphopoietin (TSLP).ResultsThe expression of LC3B and p62 as well as SERPINB3 and SERPINB4 was highly increased in untreated AD skin compared to non‐lesional skin and normal skin and decreased upon dupilumab therapy. In contrast, the AD‐associated increased expression of both ATG5 and ATG7 further increased under therapy. Before therapy, cathepsin D and L expression levels were significantly lower compared to normal skin, but increased following the initiation of dupilumab therapy. The increased expression of IL‐33 and TSLP in the epidermis of AD patients correlated with that of LC3B and p62.ConclusionsOur study provides further evidence that autophagy is inhibited in lesional AD skin owing to lysosomal dysfunction. Upon dupilumab therapy, a restoration of dysregulated key players of autophagy is observed.

Formylpeptide receptor 1 contributes to epidermal barrier dysfunction-induced skin inflammation through NOD-like receptor C4-dependent keratinocyte activation.

Skin barrier dysfunction may both initiate and aggravate skin inflammation. However, the mechanisms involved in the inflammation process remain largely unknown. We sought to determine how skin barrier dysfunction enhances skin inflammation and molecular mechanisms. Skin barrier defect mice were established by tape stripping or topical use of acetone on wildtype mice, or filaggrin deficiency. RNA-Seq was employed to analyse the differentially expressed genes in mice with skin barrier defects. Primary human keratinocytes were transfected with formylpeptide receptor (FPR)1 or protein kinase R-like endoplasmic reticulum (ER) kinase (PERK) small interfering RNA to examine the effects of these gene targets. The expressions of inflammasome NOD-like receptor (NLR)C4, epidermal barrier genes and inflammatory mediators were evaluated. Mechanical (tape stripping), chemical (acetone) or genetic (filaggrin deficiency) barrier disruption in mice amplified the expression of proinflammatory genes, with transcriptomic profiling revealing overexpression of formylpeptide receptor (Fpr1) in the epidermis. Treatment with the FPR1 agonist fMLP in keratinocytes upregulated the expression of the NLRC4 inflammasome and increased interleukin-1β secretion through modulation of ER stress via the PERK-eIF2α-C/EBP homologous protein pathway. The activation of the FPR1-NLRC4 axis was also observed in skin specimens from old healthy individuals with skin barrier defect or elderly mice. Conversely, topical administration with a FPR1 antagonist, or Nlrc4 silencing, led to the normalization of barrier dysfunction and alleviation of inflammatory skin responses in vivo. In summary, our findings show that the FPR1-NLRC4 inflammasome axis is activated upon skin barrier disruption and may explain exaggerated inflammatory responses that are observed in disease states characterized by epidermal dysfunction. Pharmacological inhibition of FPR1 or NLRC4 represents a potential therapeutic target.

Exosomes derived from human dermal fibroblasts (HDFn-Ex) alleviate DNCB-induced atopic dermatitis (AD) via PPARα.

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Skin barrier dysfunction is the initial step in the development of AD. Recently, exosomes have been considered as potential cell-free medicine for skin defects such as aging, psoriasis and wounds. The aim of this study was to investigate the effects of human dermal fibroblast-neonatal-derived exosome (HDFn-Ex) on AD. HDFn-Ex increased the expression of peroxisome proliferator activated receptor α (PPARα) and alleviated the 1-chloro-2,4-dinitrobenzene (DNCB)-mediated downregulation of filaggrin, involucrin, loricrin, hyaluronic acid synthase 1 (HAS1) and HAS2 in human keratinocyte HaCaT cells. However, these effects were inhibited by the PPARα antagonist GW6471. In the artificial skin model, HDFn-Ex significantly inhibited DNCB-induced epidermal hyperplasia and the decrease in filaggrin and HAS1 levels via a PPARα. In the DNCB-induced AD-like mouse model, HDFn-Ex administration reduced epidermis thickening and mast cell infiltration into the dermis compared to DNCB treatment. Moreover, the decreases in PPARα, filaggrin and HAS1 expression, as well as the increases in IgE and IL4 levels induced by DNCB treatment were reversed by HDFn-Ex. These effects were blocked by pre-treatment with GW6471. Furthermore, HDFn-Ex exhibited an anti-inflammatory effect by inhibiting the DNCB-induced increases in IκBα phosphorylation and TNF-α expression. Collectively, HDFn-Ex exhibited a protective effect on AD. Notably, these effects were regulated by PPARα. Based on our results, we suggest that HDFn-Ex is a potential candidate for treating AD by recovering skin barrier dysfunction and exhibiting anti-inflammatory activity.

Lesional skin of seborrheic dermatitis patients is characterized by skin barrier dysfunction and correlating alterations in the stratum corneum ceramide composition.

Seborrheic dermatitis (SD) is a chronic inflammatory skin disease characterized by erythematous papulosquamous lesions in sebum rich areas such as the face and scalp. Its pathogenesis appears multifactorial with a disbalanced immune system, Malassezia driven microbial involvement and skin barrier perturbations. Microbial involvement has been well described in SD, but skin barrier involvement remains to be properly elucidated. To determine whether barrier impairment is a critical factor of inflammation in SD alongside microbial dysbiosis, a cross-sectional study was performed in 37 patients with mild-to-moderate facial SD. Their lesional and non-lesional skin was comprehensively and non-invasively assessed with standardized 2D-photography, optical coherence tomography (OCT), microbial profiling including Malassezia species identification, functional skin barrier assessments and ceramide profiling. The presence of inflammation was established through significant increases in erythema, epidermal thickness, vascularization and superficial roughness in lesional skin compared to non-lesional skin. Lesional skin showed a perturbed skin barrier with an underlying skewed ceramide subclass composition, impaired chain elongation and increased chain unsaturation. Changes in ceramide composition correlated with barrier impairment indicating interdependency of the functional barrier and ceramide composition. Lesional skin showed significantly increased Staphylococcus and decreased Cutibacterium abundances but similar Malassezia abundances and mycobial composition compared to non-lesional skin. Principal component analysis highlighted barrier properties as main discriminating features. To conclude, SD is associated with skin barrier dysfunction and changes in the ceramide composition. No significant differences in the abundance of Malassezia were observed. Restoring the cutaneous barrier might be a valid therapeutic approach in the treatment of facial SD.

WASP: Wearable Analytical Skin Probe for Dynamic Monitoring of Transepidermal Water Loss.

Early diagnosis of skin barrier dysfunction helps provide timely preventive care against diseases such as atopic dermatitis, psoriasis, food allergies, and other atopic skin disorders. Skin barrier function is commonly evaluated by measuring the transepidermal water loss (TEWL) through stratum corneum due to its noninvasive characteristics. However, existing commercial TEWL devices are significantly affected by many factors, such as ambient temperature, humidity, air flow, water accumulation, initial water contents on the skin surface, bulky sizes, high costs, and requirements for well-controlled environments. Here, we developed a wearable closed-chamber hygrometer-based TEWL device (Wearable Analytical Skin Probe, WASP) and the related algorithm for accurate and continuous monitoring of skin water vapor flux. The WASP uses short dry air purges to dry the skin surface and chamber before each water vapor flux measurement. Its design ensures a highly controlled local environment, such as consistent initial dry conditions for the skin surface and the chamber. We further applied WASP to measure the water vapor flux from six different locations of a small group of human participants. It is found that the WASP can not only measure and distinguish between insensible sweating (i.e., TEWL) and sensible sweating (i.e., thermal sweating) but also track skin dehydration-rehydration cycles. Comparisons with a commercial TEWL device, AquaFlux, show that the results obtained by both devices agree well. The WASP will be broadly applicable to clinical, cosmetic, and biomedical research.

Association between skin barrier development and early-onset atopic dermatitis: A longitudinal birth cohort study

A diagnosis of atopic dermatitis (AD) is common during infancy; however, it is unclear whether differential skin barrier development defines this period and signals disease onset in predisposed individuals. We sought to study (NCT03143504) and assess the feasibility of remote skin testing from birth to monitor skin barrier maturation and model association with an AD diagnosis by age 12 months. Biophysical testing and infrared spectroscopy were conducted at the maternity ward and family home. Tape stripping collected samples for desquamatory protease and natural moisturizing factor analysis. The 4 common European filaggrin risk alleles were screened. A total of 128 infants completed the study, with 20% developing mild disease. Significant changes in permeability barrier function, desquamatory protease activity, and molecular composition assessed spectroscopically were observed longitudinally, but only subtle evidence of differential skin barrier development was noted between infant subgroups. Common filaggrin risk alleles were strongly associated with early-onset disease and conferred a significant reduction in natural moisturizing factor and water content by age 4 weeks. Accounting for a family history of atopy, these parameters alongside a greater lipid/protein ratio and reduced chymotrypsin-like activity at birth were associated with AD. Measured in ambient conditions, transepidermal water loss did not signal disease risk at any stage. Skin barrier dysfunction lacked an acquired modality but was considered proportional to cohort severity and suggests that a portfolio of tests used in a community setting has the potential to improve current AD risk evaluations from birth.

Cutibacterium acnes in Atopic Dermatitis: Roles and Potential Therapeutic Applications

Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disease. Skin microbiota disorder, skin barrier dysfunction, and predominantly elevated type 2 immune responses are core initiate mechanisms of AD. Cutibacterium acnes (C. acnes) is a commensal bacterium that is ubiquitous and predominant in healthy skin, with intraspecific subtype diversity. The abundance of C. acnes is closely related to the sebum secreted by sebaceous glands. C. acnes has long been considered a pro-inflammatory skin bacteria that drives the development of acne vulgaris. Growing evidence supports C. acnes promotes the skin microbiota homeostasis and skin barrier maintenance, while the potential role of C. acnes in AD remains largely unexamined. This review provides the latest information on the distribution of C. acnes and its phylotypes in healthy skin and AD, meanwhile offering an overview of the possible role of C. acnes in the pathophysiological pathways underlying AD. Additionally, the review focuses on new evidence regarding the protective functions of C. acnes and its metabolites in AD, with the potential for therapeutic applications.

Abrocitinib: First Globally Approved Selective Janus Kinase-1 Inhibitor for the Treatment of Atopic Dermatitis.

Atopic dermatitis is epidermal hyperplasia, skin barrier dysfunction, and the aberrant activation of immune cells. Janus kinase (JAK) is a family of cytoplasmic nonreceptor tyrosine kinases that consists of four members, such as JAK1, JAK2, JAK3, and TYK2. The JAK signaling pathway plays a critical role in a wide range of autoimmune and inflammatory diseases, including atopic dermatitis. Abrocitinib is an orally bioavailable and selective JAK1 inhibitor, and it was approved in January, 2022, for the treatment of atopic dermatitis. The chemical structure and physical properties of abrocitinib, its synthesis, mechanism of action, and pharmacokinetic profile are summarized.