Skin barrier immunology from early life to adulthood

Is colloidal oat an effective emollient ingredient for the prevention and treatment of atopic dermatitis in infants?

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin condition characterized by barrier dysfunction and immune dysregulation, often leading to increased allergen penetration, sensitization, and secondary infections. Colloidal oat emollients are widely used in adult AD management, but their role in pediatric AD treatment, prevention, and allergy modulation remains under investigation.

METHODS

A comprehensive literature review evaluated clinical and preclinical studies on colloidal oat-containing emollients in pediatric AD treatment and prevention. Studies assessing skin barrier function, immune modulation, AD prevention, food allergy risk, and healthcare utilization were included.

RESULTS

Colloidal oat emollients improved skin hydration, reduced transepidermal water loss (TEWL), and supported barrier repair, leading to fewer AD flares and reduced reliance on steroid treatments. Studies suggest that early, consistent use of advanced emollient formulations may lower AD incidence in high-risk infants and reduce food sensitization rates. Real-world data indicate that patients using colloidal oat emollients have fewer clinic visits and lower overall healthcare costs. Concerns about oat sensitization remain unsubstantiated in most studies.

CONCLUSION

Colloidal oat emollients are effective, well-tolerated, and cost-efficient for pediatric AD management. Their barrier-restorative and anti-inflammatory properties may reduce AD and allergy risk. Future research should focus on head-to-head emollient comparisons to optimize treatment strategies.

The microbiota shapes the life trajectory of mucosal-associated invariant T cells

Mucosal-associated invariant T (MAIT) cells are innate-like T cells predominantly located in barrier tissues such as the lung, liver, skin, and colon. These cells recognize metabolites derived from the riboflavin biosynthetic pathway, which can rapidly traverse epithelial barriers and be presented during MAIT cell differentiation in the thymus and maturation in peripheral tissues. Furthermore, microbial metabolites significantly influence MAIT cell functions in various conditions, including cancer. This review summarizes how the microbiota shapes the life trajectory of MAIT cells and their antitumor reactivity. Additionally, we discuss the therapeutic implications of manipulating the microbiota as a 'bug-drug' strategy to enhance MAIT cell antitumor immunity, particularly in mucosal cancers, while emphasizing challenges and future directions for integrating microbiota considerations into MAIT cell-based therapies.

Neuro-immuno-endocrinology of the skin: how environment regulates body homeostasis

The skin, including the hypodermis, is the largest organ of the body. The epidermis, the uppermost layer, is in direct contact with the environment and is exposed to environmental stressors, including solar radiation and biological, chemical and physical factors. These environmental factors trigger local responses within the skin that modulate homeostasis on both the cutaneous and systemic levels. Using mediators in common with brain pathways, immune and neuroendocrine systems within the skin regulate these responses to activate various signal transduction pathways and influence the systemic endocrine and immune systems in a context-dependent manner. This skin neuro-immuno-endocrine system is compartmentalized through the formation of epidermal, dermal, hypodermal and adnexal regulatory units. These units can act separately or in concert to preserve skin integrity, allow for adaptation to a changing environment and prevent the development of pathological processes. Through activation of peripheral nerve endings, the release of neurotransmitters, hormones, neuropeptides, and cytokines and/or chemokines into the circulation, or by priming circulating and resident immune cells, this system affects central coordinating centres and global homeostasis, thus adjusting the body's homeostasis and allostasis to optimally respond to the changing environment.

Epithelial and mesenchymal compartments of the developing bladder and urethra display spatially distinct gene expression patterns

The lower urinary tract is comprised of the bladder and urethra and develops from the cloaca, a transient endoderm-derived structure formed from the caudal hindgut. After cloacal septation to form the urogenital sinus and anorectal tract, the bladder gradually develops from the anterior portion of the urogenital sinus while the urethra elongates distally into the genital tubercle. The bladder is a target for regenerative and reconstructive therapies but engineering an impermeable bladder epithelial lining has proven challenging. Urethral epithelial function, including its role as an active immune barrier, is poorly studied and neglected in regenerative therapy. A deeper understanding of epithelial patterning of the urogenital sinus by the surrounding mesenchyme, also accounting for sex-specific differences, can inform regenerative therapies. In this study, we identified spatially distinct genes in the epithelial and mesenchymal compartments of the developing mouse bladder and urethra that could be potential drivers of patterning in the lower urinary tract. Our data revealed spatially restricted domains of transcription factor expression in the epithelium that corresponded with bladder or urethra-specific differentiation. Additionally, we identified the genes Wnt2, Klf4 and Pitx2 that localize to the mesenchyme of the developing bladder and could be potential drivers of bladder differentiation. Our data revealed an increase in the expression of several chemokine genes including Cx3cl1 and Cxcl14 in the developing urethral epithelium that correlated with an increase in epithelial-associated macrophages in the urethra. A survey of sex-specific differences in epithelial and mesenchymal compartments revealed several differentially expressed genes between the male and female urethra but few sex-specific differences in bladder. By comparing spatially distinct gene expression in the developing lower urinary tract, our study provides insights into the divergent differentiation trajectories of the fetal bladder and urethra that establish their adult functions.

Chronological maturation of the skin immune barrier is topographically different

Adult skin varies across regions, with differences in chemical, physical, microbiota, and immune barriers. However, data on topographical immune differences in other age groups are limited. This study aimed to explore the chronological maturation of the immune barrier in various skin regions. A TaqMan low-density array and immunohistochemical and immunofluorescence detection of various immune cells and mediators in sebaceous gland-rich (SGR) and gland-poor (GP) healthy skin were performed in children, adolescents, and adults. The maturation of SGR skin showed a general upward trend in the mRNA levels of most Th17-related molecules with a significant increase in IL-1B from childhood to adulthood, but with only a slight elevation between childhood and adolescence. In addition, T cell, Treg, dendritic cell (DC) counts, as well as the levels of several Th17-related proteins (IL-17, IL-10, IL-23, CCL20, S100A8, sfTSLP, LCN2), increased significantly with age. In GP skin, AHR mRNA levels decreased, while Th17-related protein levels increased, although only moderately. When comparing the two regions, SGR and GP skin were similar in childhood, with differences emerging in adolescence and becoming significant in adulthood, particularly in the IL-17 pathway, mainly produced by Th17 cells. Our results show a similarly directed maturation process in GP and SGR regions, with more pronounced development of the SGR skin immune barrier (with more immune cell infiltration and cytokine production) during and after the adolescence. This is likely to be related to the significant changes in the chemical and microbiota barriers of the SGR skin during adolescence, and may explain the high incidence of inflammatory skin diseases on the SGR skin of adolescents, highlighting the need for targeted skin care in this region.

Electro-responsive hyaluronic acid-based click-hydrogels for wound healing

With the aim of healing challenging skin wounds, electro-responsive click-hydrogels made of hyaluronic acid (clickHA) crosslinked with a modified polyethylene glycol precursor (PEG) were prepared by semi-interpenetrating a conducting polymer, poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PEDOT-MeOH) by oxidative polymerization. The porosity and pore size of the mixed hydrogel, clickHA/PEDOT-MeOH, were both higher than those determined for the hydrogel without PEDOT-MeOH, while a honeycomb-like morphology with PEDOT-MeOH covering the pore walls was observed. Although such PEDOT-MeOH-induced changes did not influence the water absorption capacity of clickHA, they drastically affected the mechanical and electrochemical behavior. More specifically, the semi-interpenetration of PEDOT-MeOH into clickHA resulted in an increase of the Young's modulus, the compressive strength and, especially, the electrochemical activity. The biocompatibility and the potential for skin regeneration of clickHA/PEDOT-MeOH were preliminary assessed using viability and wound-healing assays with epithelial cells. Not only is the conducting hydrogel formulation biocompatible, but also promotes efficient cell migration by electrostimulation using a small voltage (0.5 V) for a short time (15 min). Thus, in just 1 h the wound gap was repaired, and a homogeneous monolayer of migrated cells was formed.

The influence of lifestyle and environmental factors on host resilience through a homeostatic skin microbiota: An EAACI Task Force Report

Human skin is colonized with skin microbiota that includes commensal bacteria, fungi, arthropods, archaea and viruses. The composition of the microbiota varies at different anatomical locations according to changes in body temperature, pH, humidity/hydration or sebum content. A homeostatic skin microbiota is crucial to maintain epithelial barrier functions, to protect from invading pathogens and to interact with the immune system. Therefore, maintaining homeostasis holds promise to be an achievable goal for microbiome-directed treatment strategies as well as a prophylactic strategy to prevent the development of skin diseases, as dysbiosis or disruption of homeostatic skin microbiota is associated with skin inflammation. A healthy skin microbiome is likely modulated by genetic as well as environmental and lifestyle factors. In this review, we aim to provide a complete overview of the lifestyle and environmental factors that can contribute to maintaining the skin microbiome healthy. Awareness of these factors could be the basis for a prophylactic strategy to prevent the development of skin diseases or to be used as a therapeutic approach.

p38α deficiency ameliorates psoriasis development by downregulating STAT3-mediated keratinocyte proliferation and cytokine production

Psoriasis is characterized by keratinocyte (KC) hyperproliferation and inflammatory cell infiltration, but the mechanisms remain unclear. In an imiquimod-induced mouse psoriasiform model, p38 activity is significantly elevated in KCs and p38α specific deletion in KCs ameliorates skin inflammation. p38α signaling promotes KC proliferation and psoriasis-related proinflammatory gene expression during psoriasis development. Mechanistically, p38α enhances KC proliferation and production of inflammatory cytokines and chemokines by activating STAT3. While p38α signaling in KCs does not affect the expression of IL-23 and IL-17, it substantially amplifies the IL-23/IL-17 pathogenic axis in psoriasis. The therapeutic effect of IL-17 neutralization is associated with decreased p38 and STAT3 activities in KCs and targeting the p38α-STAT3 axis in KCs ameliorates the severity of psoriasis. As IL-17 also highly activates p38 and STAT3 in KCs, our findings reveal a sustained signaling circuit important for psoriasis development, highlighting p38α-STAT3 axis as an important target for psoriasis treatment.

Mucosal barrier status in Atlantic salmon fed rapeseed oil and Schizochytrium oil partly or fully replacing fish oil through winter depression

The study was designed to investigate the effects of replacing fish oil by algal oil and rapeseed oil on histomorphology indices of the intestine, skin and gill, mucosal barrier status and immune-related genes of mucin and antimicrobial peptide (AMP) genes in Atlantic salmon (Salmo salar). For these purposes, Atlantic salmon smolts were fed three different diets. The first was a control diet containing fish oil but no Schizochytrium oil. In the second diet, almost 50 % of the fish oil was replaced with algal oil, and in the third diet, fish oil was replaced entirely with algal oil. The algal oil contained mostly docosahexaenoic acid (DHA) and some eicosapentaenoic acid (EPA). The study lasted for 49 days in freshwater (FW), after which some fish from each diet group were transferred to seawater (SW) for a 48-h challenge test at 33 ppt to test their ability to tolerate high salinity. Samples of skin, gills, and mid intestine [both distal (DI) and anterior (AI) portions of the mid intestine] were collected after the feeding trial in FW and after the SW-challenge test to assess the effects of the diets on the structure and immune functions of the mucosal surfaces. The results showed that the 50 % VMO (Veramaris® algal oil) dietary group had improved intestinal, skin, and gill structures. Principal component analysis (PCA) of the histomorphological parameters demonstrated a significant effect of the algal oil on the intestine, skin, and gills. In particular, the mucosal barrier function of the intestine, skin, and gills was enhanced in the VMO 50 % dietary group after the SW challenge, as evidenced by increased mucous cell density. Immunolabelling of heat shock protein 70 (HSP70) in the intestine (both DI and AI) revealed downregulation of the protein expression in the 50 % VMO group and a corresponding upregulation in the 100 % VMO group compared to 0 % VMO. The reactivity of HSP70 in the epithelial cells was higher after the SW challenge compared to the FW phase. Immune-related genes related to mucosal defense, such as mucin genes [muc2, muc5ac1 (DI), muc5ac1 (AI), muc5ac2, muc5b (skin), and muc5ac1 (gills)], and antimicrobial peptide genes [def3 (DI), def3 (AI), and cath1 (skin)] were significantly upregulated in the 50 % VMO group. PCA of gene expression demonstrated the positive influences on gene regulation in the 50 % VMO dietary group. In conclusion, this study demonstrated the positive effect of substituting 50 % of fish oil with algal oil in the diets of Atlantic salmon. The findings of histomorphometry, mucosal mapping, immunohistochemistry, and immune-related genes connected to mucosal responses all support this conclusion.

Beyond Traditional Sunscreens: A Review of Liposomal-Based Systems for Photoprotection

Sunscreen products are essential for shielding the skin from ultraviolet (UV) radiation, a leading cause of skin cancer. While existing products serve this purpose, there is a growing need to enhance their efficacy while minimizing potential systemic absorption of UV filters and associated toxicological risks. Liposomal-based formulations have emerged as a promising approach to address these challenges and develop advanced photoprotective products. These vesicular systems offer versatility in carrying both hydrophilic and lipophilic UV filters, enabling the creation of broad-spectrum sunscreens. Moreover, their composition based on phospholipids, resembling that of the stratum corneum, facilitates adherence to the skin's surface layers, thereby improving photoprotective efficacy. The research discussed in this review underscores the significant advantages of liposomes in photoprotection, including their ability to limit the systemic absorption of UV filters, enhance formulation stability, and augment photoprotective effects. However, despite these benefits, there remains a notable gap between the potential of liposomal systems and their utilization in sunscreen development. Consequently, this review emphasizes the importance of leveraging liposomes and related vesicular systems as innovative tools for crafting novel and more efficient photoprotective formulations.

An Injectable, Self-Healing, Adhesive Multifunctional Hydrogel Promotes Bacteria-Infected Wound Healing

Bacterial infections have a serious impact on public health. It is urgent to develop antibacterial hydrogels with good biocompatibility to reduce the use of antibiotics. In this study, poly(lipoic acid-co-sodium lipoate)-phytic acid (P(LA-SL)-PA) hydrogels are prepared by a simple mixture of the natural small molecules lipoic acid (LA) and phytic acid (PA) in a mild and green reaction environment. The crosslinking network is constructed through the connection of covalent disulfide bonds as well as the hydrogen bonds, which endow the injectable and self-healing properties. The P(LA-SL)-PA hydrogels exhibit an adjustable compression modulus and adhesion. The in vitro agar plates assay indicates that the antibacterial rate of hydrogels against Escherichia coli and Staphylococcus aureus is close to 95%. In the rat-infected wound model, the P(LA-SL)-PA hydrogels adhere closely to the tissue and promote epithelialization and collagen deposition with a significant effect on wound healing. These results prove that the P(LA-SL)-PA hydrogels could act as effective wound dressings for promoting the healing of infected wounds.

Diet and skin health: The good and the bad

The skin protects humans from pathogens, ultraviolet light, chemicals, mechanical, thermal, and physical injuries as well as hazardous substances. Other important roles of the skin include the regulation of several important physiological processes of the body, sensing stimuli, synthesis of vitamin D, and immune surveillance. However, aging, diseases and environmental conditions significantly change the skin's behavior and functioning. The treatment and prevention strategies for various skin diseases especially photoaging usually include topical treatment with medical cosmetology, active ingredients and other physical means of photoprotection. In recent times, however, there is an increasing consciousness about the role of diet and nutrition in skin health with certain dietary components emerging as an adequate alternative approach to alleviate and prevent both endogenous and exogenous aging symptoms. Therefore, this narrative review uniquely discusses the basic structure of the skin and also addresses common dermatological signs of damaged skin, the impacts of unhealthy diet habits on the skin, and the beneficial effects of some healthy diet habits on skin health. The information and data were collated from various literature databases and resources such as Science Direct, PubMed, Wiley, Springer, Taylor and Francis, Inflibnet, Scopus, Google, and Google Scholar using relevant keywords Medical Subject Headings (MeSH). In conclusion, diet and nutrition play essential roles in the optimum functioning of the human body, including the skin. Thus, certain diet habits such as less water intake, high-fat diet, refined sugar, and certain food additives are unhealthy and harmful to the skin while alternative healthy diet habits such as adequate water intake; consumption of antioxidants and polyphenolic-rich fruits, vegetables, nuts, and legumes; a low glycemic index diet; probiotics; and phytoestrogens should be adopted to enhance skin health.

Hurdles in translating science from lab to market in delivery systems for Cosmetics: An industrial perspective

In recent decades, a sweeping technological wave has reshaped the global economic landscape. Fueled by the unceasing forces of digital innovation and venture capital investment, this transformative machine has left a significant mark across numerous economic sectors. More recently, the emergence of 'deep tech' start-ups, focusing on areas such as artificial intelligence, nanotechnology, and biotechnology, has infused a fresh wave of innovation into various sectors, including the pharmaceutical and cosmetic industry. This review explores the significance of innovation within the cosmetics sector, with a particular emphasis on delivery systems. It assesses the crucial process of bridging the gap between research and the market, particularly in the translation of nanotechnology into tangible real-world applications. With the rise of nanotechnology-based beauty ingredients, we can anticipate groundbreaking advancements that promise to surpass consumer expectations, ushering in a new era of unparalleled innovation in beauty products.

Chemical substances and their activities in sea cucumber Apostichopus japonicus: A review

Apostichopus japonicus, also known as Stichopus japonicus, with medicinal and food homologous figures, is a globally recognized precious ingredient with extremely high nutritional value. There is no relevant review available through literature search, so this article selects the research articles through the keywords "sea cucumber" and "Apostichopus japonicus (Stichopus japonicus)" in six professional databases, such as Wiley, PubMed, ScienceDirect, ACS, Springer, and Web of Science, from 2000 to the present, summarizing the extraction, isolation, and purification methods for the four major categories (polysaccharides, proteins and peptides, saponins, and other components) of the A. japonicus chemical substances and 10 effective biological activities of A. japonicus. Included are anticoagulation, anticancer/antitumor activities, hematopoiesis, regulation of gut microbiota, and immune regulatory activities that correspond to traditional efficacy. Literature support is provided for the development of medicines and functional foods and related aspects that play a leading role in future directions.

Enhancing Skin Anti-Aging through Healthy Lifestyle Factors

Lifestyle health has been recognized as an evidence-based innovation that defines how everyday behaviors and routines influence the avoidance and therapy of illness and provides an important adjunctive component to overall health. Specifically, an approach with small changes over time can have a dramatic impact on the health and well-being of individuals not only, in general, but also can be applied to skin health. However, lifestyle health factors to improve skin well-being have not been discussed extensively and/or well promulgated. The narrative for this overview focuses on providing a summary for topic background information, but more importantly, presents four lifestyle factors that can improve dermal health [i.e., factor 1: nutrition—diet; factor 2: rest (sleep); factor 3: movement/physical exercise, and factor 4: social and community associations]. This was accomplished by identifying preceding journal reports/reviews covering especially the last five years (January 2018 to July 2023; 164 out of 205 references cited or 80%) using scientific search databases. The main conclusions of this overview encourage the concept that lifestyle health factors such as nutrition/diet, rest/sleep, movement/physical exercise, and community/social interactions support enhanced skin health and well-being with aging. Plus, social media interventions that aim to promote dietary, sleep and physical activity changes might be an application to improve skin health in the future.

An optimal method for quantifying the facial sebum level and characterizing facial sebum features

BACKGROUND

Evidence suggests that sebum content is important in skin disorders such as acne. However, sebum levels change depending on the external environment, and quantifying skin sebum levels is challenging. Here, we propose an optimal method for quantifying the facial sebum level.

MATERIALS AND METHODS

Four hundred and sixty participants (160 males and 300 females) aged 20-40 were enrolled in this study. A Sebumeter SM 810 was used to measure the sebum level at five facial locations: the forehead, the chin, the left cheek, the right cheek, and the nose. The participants were divided into two groups; one group underwent a one-time measurement (n = 390, male: female = 120: 270), and the other underwent three consecutive measurements (n = 70, male: female = 40: 30). The casual sebum level (CSL) was measured in all patients after a 30-min acclimatization; subsequently, the sebum removal process was conducted, followed by a resting period of 1 h to determine the sebum excretion rate (SER). Spearman's correlation analysis and the Wilcoxon signed-rank test were used to compare the sebum level consistency and differences between the groups.

RESULTS

Although three consecutive measurements better reflected the sebum content, the one-time measurement also represented the relative sebum level. One hour after sebum removal, the sebum level recovered to 70%-90%; thus, this method was applicable for use in SER quantification. Of the five testing points, the sebum content was highest in the nose and lowest in the cheeks (both left and right). In addition, the cheeks were the most stable sites in terms of testing points, testing times, and CSL/SER values. A one-time measurement of the CSL could represent the SER 1 h after the sebum removal. In our cohort, the sebum level of males with oily skin was decreased at age 32-35, and that of males with non-oily skin increased at 28-35. The opposite trend was observed in female participants.

CONCLUSION

Sebum measurement methods were assessed, including testing times, indices (interval of time) and sites in a conditioned external environment. A one-time measurement of the CSL 1 h after sebum removal was sufficient to determine the sebum level and SER, and the cheeks are recommended as the testing site. Sex and skin type differences were observed in sebum level changes with age.