Sebaceous gland secretion is a major physiologic route of vitamin E delivery to skin

A review of sebum in mammals in relation to skin diseases, skin function, and the skin microbiome

Diseases vary among and within species but the causes of this variation can be unclear. Immune responses are an important driver of disease variation, but mechanisms on how the body resists pathogen establishment before activation of immune responses are understudied. Skin surfaces of mammals are the first line of defense against abiotic stressors and pathogens, and skin attributes such as pH, microbiomes, and lipids influence disease outcomes. Sebaceous glands produce sebum composed of multiple types of lipids with species-specific compositions. Sebum affects skin barrier function by contributing to minimizing water loss, supporting thermoregulation, protecting against pathogens, and preventing UV-induced damage. Sebum also affects skin microbiome composition both via its antimicrobial properties, and by providing potential nutrient sources. Intra- and interspecific variation in sebum composition influences skin disease outcomes in humans and domestic mammal species but is not well-characterized in wildlife. We synthesized knowledge on sebum function in mammals in relation to skin diseases and the skin microbiome. We found that sebum composition was described for only 29 live, wild mammalian species. Sebum is important in dermatophilosis, various forms of dermatitis, demodicosis, and potentially white-nose syndrome. Sebum composition likely affects disease susceptibility, as lipid components can have antimicrobial functions against specific pathogens. It is unclear why sebum composition is species-specific, but both phylogeny and environmental effects may drive differences. Our review illustrates the role of mammal sebum function and influence on skin microbes in the context of skin diseases, providing a baseline for future studies to elucidate mechanisms of disease resistance beyond immune responses.

Modulatory role of vitamins A, B3, C, D, and E on skin health, immunity, microbiome, and diseases

Disruption of the skin barrier and immunity has been associated with several skin diseases, namely atopic dermatitis (AD), psoriasis, and acne. Resident and non-resident immune cells and the barrier system of the skin are integral to innate immunity. Recent advances in understanding skin microbiota have opened the scope of further understanding the various communications between these microbiota and skin immune cells. Vitamins, being one of the important micronutrients, have been reported to exert antioxidant, anti-inflammatory, and anti-microbial effects. The immunomodulatory action of vitamins can halt the progression of skin diseases, and thus, understanding the immuno-pharmacology of these vitamins, especially for skin diseases can pave the way for their therapeutic potential. At the same time, molecular and cellular markers modulated with these vitamins and their derivatives need to be explored. The present review is focused on significant vitamins (vitamins A, B3, C, D, and E) consumed as nutritional supplements to discuss the outcomes and scope of studies related to skin immunity, health, and diseases.

Matricellular Proteins in the Homeostasis, Regeneration, and Aging of Skin

Matricellular proteins are secreted extracellular proteins that bear no primary structural functions but play crucial roles in tissue remodeling during development, homeostasis, and aging. Despite their low expression after birth, matricellular proteins within skin compartments support the structural function of many extracellular matrix proteins, such as collagens. In this review, we summarize the function of matricellular proteins in skin stem cell niches that influence stem cells' fate and self-renewal ability. In the epidermal stem cell niche, fibulin 7 promotes epidermal stem cells' heterogeneity and fitness into old age, and the transforming growth factor-β-induced protein ig-h3 (TGFBI)-enhances epidermal stem cell growth and wound healing. In the hair follicle stem cell niche, matricellular proteins such as periostin, tenascin C, SPARC, fibulin 1, CCN2, and R-Spondin 2 and 3 modulate stem cell activity during the hair cycle and may stabilize arrector pili muscle attachment to the hair follicle during piloerections (goosebumps). In skin wound healing, matricellular proteins are upregulated, and their functions have been examined in various gain-and-loss-of-function studies. However, much remains unknown concerning whether these proteins modulate skin stem cell behavior, plasticity, or cell-cell communications during wound healing and aging, leaving a new avenue for future studies.

Photothermal Controlled-Release Immunomodulatory Nanoplatform for Restoring Nerve Structure and Mechanical Nociception in Infectious Diabetic Ulcers

Infectious diabetic ulcers (IDU) require anti-infection, angiogenesis, and nerve regeneration therapy; however, the latter has received comparatively less research attention than the former two. In particular, there have been few reports on the recovery of mechanical nociception. In this study, a photothermal controlled-release immunomodulatory hydrogel nanoplatform is tailored for the treatment of IDU. Due to a thermal-sensitive interaction between polydopamine-reduced graphene oxide (pGO) and the antibiotic mupirocin, excellent antibacterial efficacy is achieved through customized release kinetics. In addition, Trem2+ macrophages recruited by pGO regulate collagen remodeling and restore skin adnexal structures to alter the fate of scar formation, promote angiogenesis, accompanied by the regeneration of neural networks, which ensures the recovery of mechanical nociception and may prevent the recurrence of IDU at the source. In all, a full-stage strategy from antibacterial, immune regulation, angiogenesis, and neurogenesis to the recovery of mechanical nociception, an indispensable neural function of skin, is introduced to IDU treatment, which opens up an effective and comprehensive therapy for refractory IDU.

Environmental Air Pollutants Affecting Skin Functions with Systemic Implications

The increase in air pollution worldwide represents an environmental risk factor that has global implications for the health of humans worldwide. The skin of billions of people is exposed to a mixture of harmful air pollutants, which can affect its physiology and are responsible for cutaneous damage. Some polycyclic aromatic hydrocarbons are photoreactive and could be activated by ultraviolet radiation (UVR). Therefore, such UVR exposure would enhance their deleterious effects on the skin. Air pollution also affects vitamin D synthesis by reducing UVB radiation, which is essential for the production of vitamin D3, tachysterol, and lumisterol derivatives. Ambient air pollutants, photopollution, blue-light pollution, and cigarette smoke compromise cutaneous structural integrity, can interact with human skin microbiota, and trigger or exacerbate a range of skin diseases through various mechanisms. Generally, air pollution elicits an oxidative stress response on the skin that can activate the inflammatory responses. The aryl hydrocarbon receptor (AhR) can act as a sensor for small molecules such as air pollutants and plays a crucial role in responses to (photo)pollution. On the other hand, targeting AhR/Nrf2 is emerging as a novel treatment option for air pollutants that induce or exacerbate inflammatory skin diseases. Therefore, AhR with downstream regulatory pathways would represent a crucial signaling system regulating the skin phenotype in a Yin and Yang fashion defined by the chemical nature of the activating factor and the cellular and tissue context.

Antioxidants for improved skin appearance: Intracellular mechanism, challenges and future strategies

Recent advances in molecular and biochemical processes relevant to the skincare field have led to the development of novel ingredients based on antioxidants that can improve skin health and youthfulness. Considering the plethora of such antioxidants and the many implications for the skin's appearance, this review focuses on describing the critical aspects of antioxidants, including cosmetic functions, intracellular mechanisms and challenges. In particular, specialized substances are suggested for the treatment of each skin condition, such as skin ageing, skin dehydration and skin hyperpigmentation, which treatments can maximize effectiveness and avoid side effects during skin care processes. In addition, this review proposes advanced strategies that either already exists in the cosmetic market or should be developed to improve and optimize cosmetic' beneficial effects.

Oleic acid-induced interleukin-36γ: A possible link between facial skin redness and sebum

BACKGROUND

Redness of the facial skin is an important cosmetic concern. Although qualitative and quantitative modifications of sebum on the skin surface are major pathogenic factors of chronic inflammatory skin conditions, the relationship between skin redness, sebum, and mild inflammation on the cheeks of healthy subjects remains elusive.

AIMS

We aimed to explore the correlation between cheek redness and sebum and inflammatory cytokines in the stratum corneum (SC) of healthy subjects. We also examined the effects of representative sebum lipids on the gene expression of inflammatory cytokines in cultured keratinocytes.

PATIENTS/METHODS

This study included 198 healthy participants. Skin sebum was analyzed using flow injection analysis, and skin redness was assessed using a spectrophotometer. Inflammatory cytokines in tape-stripped SC were measured using enzyme-linked immunosorbent assay.

RESULTS

Cheek redness parameters positively correlated with the amount of skin sebum and the proportion of monounsaturated free fatty acids (C16:1 and C18:1) in the sebum. They also positively correlated with the interleukin (IL)-36γ/IL-37 ratio in the SC. Among the representative sebum lipids examined, oleic acid (C18:1, cis-9) dose- and time-dependently regulated the mRNA expression of IL-36γ and IL-37 in cultured keratinocytes, and this effect was attenuated by the N-methyl-D-aspartate (NMDA)-type glutamate receptor antagonist, MK801.

CONCLUSIONS

Skin surface sebum may be related to cheek redness in healthy subjects, and oleic acid-induced IL-36γ through NMDA-type glutamate receptors may be a link between them. Our study provides a possible skincare strategy for mitigating unfavorable increase in skin redness by targeting the facial skin sebum, particularly oleic acid.

The effect of the ketogenic diet on Acne: Could it be a therapeutic tool?

Acne is a chronic inflammatory disease of the pilosebaceous unit resulting from androgen-induced increased sebum production, altered keratinization, inflammation, and bacterial colonization of the hair follicles of the face, neck, chest and back by Propionibacterium acnes. Overall, inflammation and immune responses are strongly implicated in the pathogenesis of acne. Although early colonization with Propionibacterium acnes and family history may play an important role in the disease, it remains unclear exactly what triggers acne and how treatment affects disease progression. The influence of diet on acne disease is a growing research topic, yet few studies have examined the effects of diet on the development and clinical severity of acne disease, and the results have often been contradictory. Interestingly, very low-calorie ketogenic diet (VLCKD) has been associated with both significant reductions in body weight and inflammatory status through the production of ketone bodies and thus it has been expected to reduce the exacerbation of clinical manifestations or even block the trigger of acne disease. Given the paucity of studies regarding the implementation of VLCKD in the management of acne, this review aims to provide evidence from the available scientific literature to support the speculative use of VLCKD in the treatment of acne.

Reactive Oxygen Species and Antioxidant System in Selected Skin Disorders

The skin has a solid protective system that includes the stratum corneum as the primary barrier and a complete antioxidant defence system to maintain the skin's normal redox homeostasis. The epidermal and dermal cells are continuously exposed to physiological levels of reactive oxygen species (ROS) originating from cellular metabolic activities. Environmental insults, such as ultraviolet (UV) rays and air pollutants, also generate ROS that can contribute to structural damage of the skin. The antioxidant defence system ensures that the ROS level remains within the safe limit. In certain skin disorders, oxidative stress plays an important role, and there is an established interplay between oxidative stress and inflammation in the development of the condition. Lower levels of skin antioxidants indicate that oxidative stress may mediate the pathogenesis of the disorder. Accordingly, the total antioxidant level was also found to be lower in individuals with skin disorders in individuals with normal skin conditions. This review attempts to summarise the skin oxidant sources and antioxidant system. In addition, both skin and total antioxidant status of individuals with psoriasis, acne vulgaris, vitiligo and atopic dermatitis (AD), as well as their associations with the progression of these disorders will be reviewed.

On the Potential Role of the Antioxidant Couple Vitamin E/Selenium Taken by the Oral Route in Skin and Hair Health

The relationship between oxidative stress and skin aging/disorders is well established. Many topical and oral antioxidants (vitamins C and E, carotenoids, polyphenols) have been proposed to protect the skin against the deleterious effect induced by increased reactive oxygen species production, particularly in the context of sun exposure. In this review, we focused on the combination of vitamin E and selenium taken in supplements since both molecules act in synergy either by non-enzymatic and enzymatic pathways to eliminate skin lipids peroxides, which are strongly implicated in skin and hair disorders.

Nontargeted metabolomics to characterize the effects of isotretinoin on skin metabolism in rabbit with acne

Background: Acne vulgaris is a chronic inflammatory disease of the pilosebaceous unit. This study aimed to explore the pathogenesis of acne and the therapeutic mechanism of isotretinoin from the metabolic perspective in coal tar-induced acne in rabbits. Methods: Ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC-qTOF-MS) based metabolomics was used to identify skin metabolites in groups C (blank control), M (model group) and T (isotretinoin group). Multivariate statistical analysis was used to process the metabolomics data. Results: 98 differential metabolites in group C and group M were identified. The highest proportion of differential metabolites were organic acids and derivatives, lipid metabolites, organic heterocyclic compounds, and nucleoside metabolites. The most significant metabolic pathways included protein digestion and absorption, central carbon metabolism in cancer, ABC transporters, aminoacyl-tRNA biosynthesis, biosynthesis of amino acids, and sphingolipid signaling pathway. Isotretinoin treatment normalized eight of these metabolites. Conclusions: Our study will help to further elucidate the pathogenesis of acne, the mechanism of isotretinoin at the metabolite level, and identify new therapeutic targets for treating acne.

Carotenoids in Human SkinIn Vivo: Antioxidant and Photo-Protectant Role against External and Internal Stressors

The antioxidant system of the human body plays a crucial role in maintaining redox homeostasis and has an important protective function. Carotenoids have pronounced antioxidant properties in the neutralization of free radicals. In human skin, carotenoids have a high concentration in the stratum corneum (SC)-the horny outermost layer of the epidermis, where they accumulate within lipid lamellae. Resonance Raman spectroscopy and diffuse reflectance spectroscopy are optical methods that are used to non-invasively determine the carotenoid concentration in the human SC in vivo. It was shown by electron paramagnetic resonance spectroscopy that carotenoids support the entire antioxidant status of the human SC in vivo by neutralizing free radicals and thus, counteracting the development of oxidative stress. This review is devoted to assembling the kinetics of the carotenoids in the human SC in vivo using non-invasive optical and spectroscopic methods. Factors contributing to the changes of the carotenoid concentration in the human SC and their influence on the antioxidant status of the SC in vivo are summarized. The effect of chemotherapy on the carotenoid concentration of the SC in cancer patients is presented. A potential antioxidant-based pathomechanism of chemotherapy-induced hand-foot syndrome and a method to reduce its frequency and severity are discussed.

Effects of golden tomato extract on skin appearance-outlook into gene expression in cultured dermal fibroblasts and on trans-epidermal water loss and skin barrier in human subjects

SCOPE

Two experiments were performed to test the effects of rich tomato extract (Golden Tomato Extract, GTE) on human skin. In one experiment, the effects of this extract on gene expression in cultured human dermal fibroblasts were examined. In a second experiment, human subjects consumed the extract and trans-epidermal water loss (TEWL), and aspects of skin appearance were monitored.

METHODS AND RESULTS

Primary human dermal fibroblasts in culture were treated with the extract. After six hours, RNA was extracted, and gene expression was examined using Affymetrix Human Clariom D array processing. For the clinical study, 65 human subjects consumed a capsule once a day for 16 weeks, and various skin parameters were assessed at predetermined time intervals. Among the genes upregulated by GTE are genes that augment innate immunity, enhance DNA repair, and the ability to detoxify xenobiotics. GTE significantly reduced TEWL in subjects who had high TEWL at baseline, but it had no effect on TEWL in subjects who had lower TEWL at baseline.

CONCLUSIONS

Golden tomato extract may provide benefits to the skin by enhancing innate immunity and other defense mechanisms in the dermis and by providing antioxidants to the skin surface to optimize TEWL and the appearance of the skin.

Percutaneous egression: What do we know?

BACKGROUND

The process by which drugs leave the bloodstream to enter the skin compartments is important in determining appropriate routes of delivery and developing more efficacious medications. We conducted a general literature review on percutaneous egression mechanisms.

SUMMARY

Studies demonstrate that the stratum corneum (SC) is a compartment for systemically delivered drugs. Upon reviewing the available literature, it became apparent that there may be multiple mechanisms of percutaneous egression dependent upon drug physiochemical properties. These mechanisms include, but are not limited to, desquamation, sebum secretion, sweat transport and passive diffusion. While drugs often utilize one major pathway, it is possible that all mechanisms may play a role to varying extents.

KEY MESSAGES

Available literature suggests that hydrophilic substances tended to travel from blood to the upper layers of the skin via sweat, whereas lipophilic substances utilized sebum secretion to reach the SC. Upon reaching the skin surface, the drugs spread laterally before penetrating back into the skin as if they were topically administered. More data are warranted to identify additional percutaneous egression mechanisms, precise drug action sites and accelerate drug development.

Molecular Mapping of Sebaceous Squalene by Ambient Mass Spectrometry

Squalene (SQ), a highly unsaturated sebaceous lipid, plays an important role in protecting human skin. To better understand the role of SQ in clinical medicine, an efficient analytical approach is needed to comprehensively study the distribution of SQ on different parts of the skin. In this study, sebaceous lipids were collected from different epidermal areas of a volunteer with sampling probes. Thermal desorption-electrospray ionization/mass spectrometry (TD-ESI/MS) was then used to characterize the lipid species on the probes, and each TD-ESI/MS analysis was completed within a few seconds without any sample pretreatment. The molecular mapping of epidermal squalene on whole-body skin was rendered by scaling the peak area of the extracted ion current (EIC) of SQ based on a temperature color gradient, where colors were assigned to the 1357 sampling locations on a 3D map of the volunteer. The image showed a higher SQ distribution on the face than any other area of the body, indicating the role of SQ in protecting facial skin. The results were in agreement with previous studies using SQ as a marker to explore sebaceous activity. The novelty and significance of this work are concluded as two points: (1) direct and rapid detection of all major classes of sebaceous lipids, including the unsaturated hydrocarbons (SQ) and nonpolar lipids (e.g., cholesterol). The results are unique compared to other conventional and ambient ionization mass spectrometry methods and (2) this is the first study to analyze SQ distribution on the whole-body skin by a high-throughput approach.

Deleterious side effects of nutritional supplements

Vitamin and mineral supplement consumption is widespread. They are taken for a variety of conditions, including dermatologic disorders. Although consumers often assume these supplements are safe, excessive consumption of supplements may have deleterious effects. Such vitamin supplements include vitamin A, niacin, biotin, vitamin D, and vitamin E, and specific mineral supplements include zinc, copper, and iron. These supplements may have a number of potential adverse effects.

Estrogen regulates the expression of retinoic acid synthesis enzymes and binding proteins in mouse skin

Topical 17-beta-estradiol (E2) regulates the hair cycle, hair shaft differentiation, and sebum production. Vitamin A also regulates sebum production. Vitamin A metabolism proteins localized to the pilosebaceous unit (PSU; hair follicle and sebaceous gland); and were regulated by E2 in other tissues. This study tests the hypothesis that E2 also regulates vitamin A metabolism in the PSU. First, aromatase and estrogen receptors localized to similar sites as retinoid metabolism proteins during mid-anagen. Next, female and male wax stripped C57BL/6J mice were topically treated with E2, the estrogen receptor antagonist ICI 182,780 (ICI), letrozole, E2 plus letrozole, or vehicle control (acetone) during mid-anagen. E2 or one of its inhibitors regulated most of the vitamin A metabolism genes and proteins examined in a sex-dependent manner. Most components were higher in females and reduced with ICI in females. ICI reductions occurred in the premedulla, sebaceous gland, and epidermis. Reduced E2 also reduced RA receptors in the sebaceous gland and bulge in females. However, reduced E2 increased the number of retinal dehydrogenase 2 positive hair follicle associated dermal dendritic cells in males. These results suggest that estrogen regulates vitamin A metabolism in the skin. Interactions between E2 and vitamin A have implications in acne treatment, hair loss, and skin immunity.

Roles of plant-based ingredients and phytonutrients in canine nutrition and health

Dogs possess the ability to obtain essential nutrients, established by the Association of American Feed Control Officials (AAFCO), from both animal‐ and plant‐based ingredients. There has been a recent increase in the popularity of diets that limit or completely exclude certain plant‐based ingredients. Examples of these diets include ‘ancestral’ or ‘evolutionary’ diets, raw meat‐based diets and grain‐free diets. As compared to animal sources, plant‐derived ingredients (including vegetables, fruits, grains, legumes, nuts and seeds) provide many non‐essential phytonutrients with some data suggesting they confer health benefits. This review aims to assess the strength of current evidence on the relationship between the consumption of plant‐based foods and phytonutrients (such as plant‐derived carotenoids, polyphenols and phytosterols) and biomarkers of health and diseases (such as body weight/condition, gastrointestinal health, immune health, cardiovascular health, visual function and cognitive function) from clinical trials and epidemiological studies. This review highlights the potential nutritional and health benefits of including plant‐based ingredients as a part of balanced canine diets. We also highlight current research gaps in existing studies and provide future research directions to inform the impact of incorporating plant‐based ingredients in commercial or home‐prepared diets.

Tri-Model Therapy: Combining Macrocyclic Lactone, Piperazine Derivative and Herbal Preparation in Treating Humpsore in Cattle

Stephanofilariasis or humpsore is a chronic parasitic dermatitis of cattle. Various treatment regimens were attempted in the past but were found to be partially effective. Here, we claim a successful treatment regime using an FDA-approved macrocyclic lactone, a piperazine derivative, and an herbal preparation. Twenty-four cattle (18 affected and 6 unaffected) were selected and divided into Gr 1: positive control (infected without treatment; n = 6), Gr 2: treatment group (infected with treatment with ivermectin; n = 6), Gr 3: treatment group (infected with treatment with tri-model therapy including ivermectin, diethylcarbamazine citrate, and an herbal ointment, n = 6), and Gr 4: negative control (non-infected animals; n = 6). In Gr 2 and Gr 3, treatment to the ailing animals were given for 30 days. Lesion was significantly reduced in day 15 of post-treatment and completely healed on day 30 of post-treatment in Gr 3. Tri-model therapy recorded significant improvement in the surface area of the sore as compared to ivermectin administration alone. Antioxidants were increased and malondialdehyde (MDA) and cortisol concentrations were decreased significantly (p < 0.05) in Gr 3 than in untreated control group at day 14, 21 and 28. Histopathological changes in infected animals were characterized by parakeratotic hyperkeratosis along with presence of nucleated keratinocytes. There were infiltrations of polymorphonuclear cells specially eosinophils along with a few monomorphonuclear cells. Microfilarial organism was observed beneath the epidermis, which was surrounded by fibrocytes and infiltrated cells. In the tri-model-treated animal after recovery, the skin revived a normal architecture. Therefore, tri-model therapy has the potential to cure humpsore.

Seasonal variations in the skin parameters of Caucasian women from Central Europe

BACKGROUND

The human skin is greatly affected by external factors such as UV radiation (UVR), ambient temperature (T), and air humidity. These factors oscillate during the year giving rise to the seasonal variations in the skin properties. The aim of this study was to evaluate the effect of seasons, environmental T, relative and absolute humidity on the skin parameters of Caucasian women, perform a literature review and discuss the possible factors lying behind the found changes.

MATERIALS AND METHODS

We measured stratum corneum (SC) hydration, transepidermal water loss (TEWL), sebum level, erythema index, and elasticity parameters R2 and R7 on the forehead and the cheek of Caucasian women from the Czech Republic throughout the year. We also performed a non-systematic literature review focused on the seasonal variations in these skin parameters.

RESULTS

We confirmed a well-documented low SC hydration and sebum production in winter. In spring, we found the lowest TEWL (on the forehead) and the highest SC hydration but also the highest erythema index and the lowest elasticity presumably indicating skin photodamage. For most of the skin parameters, the seasonal variations probably arise due to a complex action of different factors as we extensively discussed.

CONCLUSION

The data about the seasonal variations in the skin parameters are still highly inconsistent and further studies are needed for better understanding of the normal skin changes throughout the year.

Skin Health from the Inside Out

The skin is the main interface between the body and the environment, providing a biological barrier against an array of chemical and physical pollutants (e.g., ultraviolet light, ozone, etc.). Exposure of the skin to these outdoor stressors generates reactive oxygen species (ROS), which can overwhelm the skin's endogenous defense systems (e.g., catalase, vitamins C and E, etc.), resulting in premature skin aging due to the induction of DNA damage, mitochondrial damage, lipid peroxidation, activation of inflammatory signaling pathways, and formation of protein adducts. In this review, we discuss how topical application of antioxidants, including vitamins C and E, carotenoids, resveratrol, and pycnogenol, can be combined with dietary supplementation of these antioxidant compounds in addition to probiotics and essential minerals to protect against outdoor stressor-induced skin damage, including the damage associated with aging.

Regeneration of skin appendages and nerves: current status and further challenges

Tissue-engineered skin (TES), as an analogue of native skin, is promising for wound repair and regeneration. However, a major drawback of TES products is a lack of skin appendages and nerves to enhance skin healing, structural integrity and skin vitality. Skin appendages and nerves are important constituents for fully functional skin. To date, many studies have yielded remarkable results in the field of skin appendages reconstruction and nerve regeneration. However, patients often complain about a loss of skin sensation and even cutaneous chronic pain. Restoration of pain, temperature, and touch perceptions should now be a major challenge to solve in order to improve patients’ quality of life. Current strategies to create skin appendages and sensory nerve regeneration are mainly based on different types of seeding cells, scaffold materials, bioactive factors and involved signaling pathways. This article provides a comprehensive overview of different strategies for, and advances in, skin appendages and sensory nerve regeneration, which is an important issue in the field of tissue engineering and regenerative medicine.

Why do humans get acne? A hypothesis

Acne is a disease unique to humans and is associated with sebaceous glands that are found at high density on the scalp, forehead and face. Despite being a near universal problem in adolescence, the reason why such troublesome sebaceous glands exist at all is not well understood. Some interesting theories have been postulated including roles for skin maintenance, immunological function and perhaps even pheromones, but pre-pubertal skin which has sebaceous glands that are largely inactive, is healthy. Dystocia, obstructed labour, is unique to humans and no other animal has as much trouble giving birth. This is thought to reflect the relatively large human foetal head and proportionally small maternal pelvis. Noting the high density of sebaceous glands on the face, chest and back; these are exactly the same structures that pose the greatest obstruction during childbirth. Sebaceous glands develop after the fourth month of gestation and are large and well-developed at birth. Sebum production is also relatively high at birth. Having extra lubrication at these sites would help make the baby more slippery for birth conferring a selective advantage to successful delivery, as does the presence of the vernix caseosa, a white creamy substance, unique to humans that coats new-born infants. It is proposed that the sebaceous glands that cause acne are present on the face and forehead as they confer a selective advantage by 'lubricating' the widest parts of the new born baby to ease the passage of childbirth. Later in life, sebaceous glands may be inappropriately and pathologically primed, driven by a combination of hormones, diet and lifestyle to create acne.

Biology of the vernix caseosa: A review

The vernix caseosa is a complex membranous structure comprising 80% water, 10% protein, and 10% lipids including barrier lipids such as ceramides, free fatty acids, phospholipids and cholesterol, synthesized partly by fetal sebaceous glands during the last trimester of pregnancy in an antero-posterior and dorsoventral manner. Because of its lipid content, vernix is hydrophobic and protects the skin from excessive water exposure during the development of the stratum corneum. The vernix caseosa has various functions during fetal transition from an intrauterine to an extrauterine environment, including lubrication of the birth canal during parturition, barrier function to prevent water loss, temperature regulation, for innate immunity and for intestinal development. This review discusses the evidence supporting the prenatal and postnatal functions of vernix caseosa, along with its structure, composition, and physical and biological characteristics. Understanding the biology of the vernix may facilitate improved care of preterm infants immediately post-partum.

Architecture of antimicrobial skin defense

The skin is the largest and the most exposed organ in the body and its defense is regulated at several anatomical levels. Here, we explore how skin layers, including the epidermis, dermis, adipose tissue, and skin appendages, as well as cutaneous microbiota, contribute to the function of skin antimicrobial defense. We highlight recent studies that reveal the differential and complementary responses of skin layers to bacterial, viral, and fungal infection. In particular, we focus on key soluble mediators in the layered skin defense, such as antimicrobial peptides, as well as on lipid antimicrobials, cytokines, chemokines, and barrier-maintaining molecules. We include our own evaluative analyses of transcriptomic datasets of human skin to map the involvement of antimicrobial peptides in skin protection under both steady state and infectious conditions. Furthermore, we explore the versatility of the mechanisms underlying skin defense by highlighting the role of the immune and nervous systems in their interaction with cutaneous microbes, and by illustrating the multifunctionality of selected antimicrobial peptides in skin protection.

Exposure Assessment For Air-To-Skin Uptake of Semivolatile Organic Compounds (SVOCs) Indoors

Semivolatile organic compounds (SVOCs) are ubiquitous in the indoor environment and a priority for exposure assessment because of the environmental health concerns that they pose. Direct air-to-skin dermal uptake has been shown to be comparable to the inhalation intake for compounds with certain chemical properties. In this study, we aim to further understand the transport of these types of chemicals through the skin, specifically through the stratum corneum (SC). Our assessment is based on collecting three sequential forehead skin wipes, each hypothesized to remove pollutants from successively deeper skin layers, and using these wipe analyses to determine the skin concentration profiles. The removal of SVOCs with repeated wipes reveals the concentration profiles with depth and provides a way to characterize penetration efficiency and potential transfer to blood circulation. We used a diffusion model applied to surface skin to simulate concentration profiles of SVOCs and compared them with the measured values. We found that two phthalates, dimethyl and diethyl phthalates, penetrate deeper into skin with similar exposure compared to other phthalates and targeted SVOCs, an observation supported by the model results as well. We also report the presence of statistically significant declining patterns with skin depth for most SVOCs, indicating that their diffusion through the SC is relevant and eventually can reach the blood vessels in the vascularized dermis. Finally, using a nontarget approach, we identified skin oxidation products, linked to respiratory irritation symptoms, formed from the reaction between ozone and squalene.

Efficacy and possible mechanisms of botulinum toxin treatment of oily skin

BACKGROUND

Oily skin is one of the most common dermatological complaints. Oily skin may be accompanied by enlarged pores, acne, and seborrheic dermatitis. Moreover, oily skin has negative effects on self-perception. Most therapeutic approaches used to treat oily skin have had varying degrees of efficacy and include topical treatments, such as photodynamic therapy and lasers. However, certain of these therapies for oily skin may lead to severe side effects. With the expanding use and high safety profile of botulinum toxin type A (BoNT-A), its use in the treatment of oily skin has caused significant concerns; moreover, relevant reports have gradually accumulated to address the efficacy of BoNT-A and explore its mechanisms of action.

AIMS

The objective of this article was to review the efficacy and possible treatment mechanisms of BoNT-A on oily skin.

METHODS

A retrospective review of the published data was conducted.

RESULTS

Most studies have suggested that the intradermal injection of BoNT-A decreased sebum production and pore size. Furthermore, this treatment attained high patient satisfaction without significant side effects. BoNT-A effectively decreased sebum production and excretion, which was in keeping with previous studies, possibly via its blockade of cholinergic signaling and its neuromodulatory effects.

CONCLUSIONS

Intradermal BoNT-A injection may represent a promising new treatment for oily skin and other relevant dermatological problems, such as enlarged pores, acne, and seborrheic dermatitis. Further study is still needed to determine the specific mechanisms of BoNT-A and the optimal injection techniques and doses for oily skin and other relevant cosmetic concerns.

Gender- and age-related differences in facial sebaceous glands in Asian skin, as observed by non-invasive analysis using three-dimensional ultrasound microscopy

BACKGROUND

While determining sebaceous gland morphology is useful in the treatment of skin disorders such as acne, a non-invasive assessment method has not been developed. Since age and gender affect sebum level, differences in sebaceous gland morphology according to these factors were investigated.

METHODS

Facial skin was measured using a high-frequency three-dimensional ultrasound microscope. First, the ultrasound images were compared with skin sections. Next, we assessed sebaceous gland morphology. Images of sebaceous gland in the cheeks of young male, young female and elderly female subjects were obtained using ultrasound microscopy, and en face images were processed to measure the sebaceous gland area.

RESULTS

In the ultrasound images, sebaceous glands and also thin collagen fibers, which surrounded the glands, could be detected as low-intensity regions. We called them sebaceous units. In young male subjects, the sebaceous unit areas 900-μm beneath the skin surface were larger than those at 700 μm. In contrast, depth-dependent differences in sebaceous unit area were not observed in young female subjects, indicating that males had cauliflower-shaped sebaceous glands while young females had somewhat more cylindrical and smaller sebaceous glands than the young males. Regarding age, the areas of sebaceous units at 900 μm were diminished and the depth of maximum area was shallower in elderly female subjects compared to young female subjects. Hence, sebaceous glands are considered to shrink with age.

CONCLUSION

Differences in facial sebaceous unit morphology between genders as well as by age groups could be observed using high-frequency ultrasound microscopy.

Development of new 3D human ex vivo models to study sebaceous gland lipid metabolism and modulations

OBJECTIVES

Sebaceous glands maintain skin homeostasis by producing sebum. Low production can induce hair loss and fragile skin. Overproduction provokes seborrhoea and may lead to acne and inflammatory events. To better study sebaceous gland maintenance, sebocyte maturation, lipid production and ageing or inflammatory processes, we developed innovative 3D ex vivo models for human sebaceous glands.

MATERIALS AND METHODS

Culture conditions and analytical methods optimized on sebocyte monolayers were validated on extracted sebaceous glands and allowed the development of two 3D models: (a) "air-liquid" interface and (b) human fibronectin-coated "sandwich" method. Lipid production was assessed with microscopy, fluorometry or flow cytometry analysis after Nile Red staining. Specific lipids (particularly squalene and peroxidized squalene) were measured by Gas or liquid Chromatography and Mass spectrometry.

RESULTS

This study allowed us to select appropriate conditions and design Seb4Gln culture medium inducing sebocyte proliferation and neutral lipid production. The "air-liquid" model was appropriate to induce sebocyte isolation. The "sandwich" model enabled sebaceous gland maintenance up to 42 days. A treatment with Insulin Growth Factor-1 allowed validation of the model as we succeeded in mimicking dynamic lipid overproduction.

CONCLUSION

Functional sebocyte maturation and physiological maintenance were preserved up to 6 weeks in our models. Associated with functional assays, they provide a powerful platform to mimic physiological skin lipid metabolism and to screen for active ingredients modulating sebum production.

Oxidation of squalene by singlet oxygen and free radicals results in different compositions of squalene monohydroperoxide isomers

Oxidation of squalene (SQ) causes a decline in the nutritional value of SQ in foods, as well as an accumulation of SQ oxidation products in skin lipids which lead to adverse skin conditions. However, mechanistic insights as to how SQ is oxidized by different oxidation mechanisms have been limited, and thus effective measures towards the prevention of SQ oxidation have not been identified. In this study, we oxidized SQ by either singlet oxygen oxidation or free radical oxidation, and monitored the formation of the six SQ monohydroperoxide (SQOOH) isomers, the primary oxidation products of SQ, at the isomeric level. While singlet oxygen oxidation of SQ resulted in the formation of similar amounts of the six SQOOH isomers, free radical oxidation of SQ mainly formed two types of isomers, 2-OOH-SQ and 3-OOH-SQ. The addition of β-carotene during singlet oxygen oxidation, and the addition of α-tocopherol during free radical oxidation lead to a dose-dependent decrease in the formation of SQOOH isomers. Such results suggest that the analysis of SQOOH at the isomeric level allows for the determination of the cause of SQ oxidation in various samples, and provides a foothold for future studies concerning the prevention of SQ oxidation.

Tocotrienols: the unsaturated sidekick shifting new paradigms in vitamin E therapeutics

Vitamin E family members: tocotrienols and tocopherols are widely known for their health benefits. Decades of research on tocotrienols have shown they have diverse biological activities such as antioxidant, anti-inflammatory, anticancer, neuroprotective and skin protection benefits, as well as improved cognition, bone health, longevity and reduction of cholesterol levels in plasma. Tocotrienols also modulate several intracellular molecular targets and, most importantly, have been shown to improve lipid profiles, reduce total cholesterol and reduce the volume of white matter lesions in human clinical trials. This review provides a comprehensive update on the little-known therapeutic potentials of tocotrienols, which tocopherols lack in a variety of inflammation-driven diseases.

SRB1 as a new redox target of cigarette smoke in human sebocytes

For its critical location, the skin represents the major interface between the body and the environment, therefore is one of the major biological barriers against the outdoor environmental stressors. Among the several oxidative environmental stressors, cigarette smoke (CS) has been associated with the development and worsening of many skin pathologies such as acne, dermatitis, delayed wound healing, aging and skin cancer. In our previous work we have demonstrated that CS is able to affect genes involved in skin cholesterol trafficking, among which SRB1, a receptor involved in the uptake of cholesterol from HDL, seems to be very susceptible to the oxidative stress induced by CS. In the present work we wanted to investigate the presence of SRB1 in human sebocytes and whether CS can affect cholesterol cellular uptake via the redox modulation of SRB1. By using a co-culture system of keratinocytes/sebocytes, we found that CS exposure induced a SRB1 protein loss without affecting sebocytes viability. The decrease of SRB1 levels was a consequence of SRB1/HNE adducts formation that leads to SRB1 ubiquitination and degradation. Moreover, the CS-induced loss of SRB1 induced an alteration of sebocytes lipid content, also demonstrated by cholesterol quantification in SRB1 siRNA experiments. In conclusion, exposure to CS, induced SRB1 post-translational modifications in sebocytes and this might affect sebocytes/skin functionality.

Pharmacokinetics of ivermectin applied topically by whole-body bathing method in healthy volunteers

As a novel administration method of ivermectin (IVM) for scabies treatment, we proposed a "whole-body bathing method (WBBM)". In this method, the patients would bathe themselves in a bathing fluid containing IVM at an effective concentration. Previously, we demonstrated that WBBM could deliver IVM to the skin but not to the plasma in rats. In the present study, to assess the clinical validity of the method an arm bathing examination (first trial) and a whole-body bathing examination (second trial) were conducted in healthy volunteers. In both the first and second trials, after bathing in fluid containing IVM, the exposure in the stratum corneum was higher compared with that after taking IVM p.o. as reported previously. IVM was not detected in plasma at any sampling point after the whole-body bathing in the second trial. Furthermore no serious adverse events were found. These results in both trials suggest that WBBM can deliver IVM to the human stratum corneum without systemic exposure or serious adverse effects in healthy volunteers, and at concentrations that would be adequate for scabies treatment.

Assessment of a new biological complex efficacy on dysseborrhea, inflammation, and Propionibacterium acnes proliferation

INTRODUCTION

Acne vulgaris is a common chronic inflammatory disease of the pilosebaceous unit triggered by Propionibacterium acnes. A bakuchiol, Ginkgo biloba extract, and mannitol (BGM) complex has been developed to provide patients with acne with a specific dermocosmetic to be used adjunctively with conventional treatments.

OBJECTIVE

The aim of these studies was to assess the antibacterial, anti-inflammatory, and antioxidative potential of BGM complex and its individual compounds as well as its impact on sebum composition.

METHODS

The antibacterial, anti-inflammatory, and antioxidative potential of BGM complex and its compounds was assessed through in vitro, ex vivo, and clinical studies. The clinical benefit of BGM complex formulated in a cream was assessed in subjects prone to acne through sebum composition analysis and photometric assessments.

RESULTS

Results from the studies showed that the BGM complex has significant antibacterial, anti-inflammatory, and antioxidative properties. At similar concentrations, bakuchiol has up to twice the antioxidative potential than vitamin E. In subjects, BGM complex regulated the sebum composition in acne patients by increasing the level of sapienic and linolenic acid and reducing the level of oleic acid. The reduced number of porphyrins on the skin surface showed that it is also effective against P. acnes.

CONCLUSION

BGM complex provides a complete adjunctive care in patients with acne by targeting etiopathogenic factors of acne: dysseborrhea, inflammation, and P. acnes proliferation.

Skin aging: are adipocytes the next target?

Dermal white adipose tissue (dWAT) is increasingly appreciated as a special fat depot. The adipocytes in this depot exert a variety of unique effects on their surrounding cells and can undergo massive phenotypic changes. Significant modulation of dWAT content can be observed both in intrinsically and extrinsically aged skin. Specifically, skin that has been chronically photo-damaged displays a reduction of the dWAT volume, caused by the replacement of adipocytes by fibrotic structures. This is likely to be caused by the recently uncovered process described as "adipocyte-myofibroblast transition" (AMT). In addition, contributions of dermal adipocytes to the skin aging processes are also indirectly supported by spatial correlations between the prevalence of hypertrophic scarring and the appearance of signs of skin aging in different ethnic groups. These observations could elevate dermal adipocytes to prime targets in strategies aimed at counteracting skin aging.

Lrig1 Expression in Human Sebaceous Gland Tumors

Background

Sebaceous glands contribute significantly to the barrier functions of the skin. However, little is known about their homeostasis and tumorigenesis. Recently, increased expression of stem cell marker Lrig1 has been reported in sebaceous carcinoma-like tumors of K14ΔNLef1 transgenic mice. In this study, we analyzed the Lrig1 expression in human sebaceous tumors.

Methods

Twenty-eight formalin-fixed paraffin-embedded sebaceous tumor specimens (7 sebaceous hyperplasias, 7 sebaceous adenomas, 10 sebaceomas and 4 sebaceous carcinomas) were stained with anti-Lrig1, anti-CD44v3 and anti-Ki67 antibody.

Results

Four (100%) sebaceous carcinomas, 8 (80%) sebaceomas, 3 (43%) sebaceous adenomas and no sebaceous hyperplasia showed Lrig1 overexpression.

Discussion and Conclusion

Lrig1 is a known tumor suppressor gene and is usually considered to be an indicator of poorly aggressive tumors. In human sebaceous tumors, the stronger Lrig1 staining in sebaceous carcinoma compared to other sebaceous tumors might be a feature of an advanced stage in tumorigenesis and a bad prognosis. In our study, 100% of sebaceous carcinomas revealed Lrig1 overexpression. We propose that Lrig1 may be used as a possible new marker of poorly differentiated sebaceous carcinoma.

Effect of high-fat meal intake on the pharmacokinetic profile of ivermectin in Japanese patients with scabies

Ivermectin (IVM) is used as an anthelmintic agent in many countries. To evaluate the effect of high-fat (HF) meal intake on the pharmacokinetics of IVM, a clinical trial was conducted in Japanese patients with scabies. The patients were administrated Stromectol(®) tablets in the fasted state, and after 1 week they were also administrated it after a HF meal (fed state). After the administration, IVM concentrations in plasma and the stratum corneum were determined. The geometric mean of fed/fasted ratio of area under IVM concentration-time curve (AUC) in plasma was 1.25 (90% confidence interval, 1.09-1.43), suggesting the tendency to increased absorption after a HF meal. The fed/fasted ratio of the maximum IVM concentration in the stratum corneum was well correlated with that in plasma. In addition, no serious adverse events were observed during the trial, while a mild increase of aspartate aminotransferase and alanine aminotransferase activity in plasma was observed under the fed state in two patients. The mean AUC of IVM in plasma of those two patients were approximately threefold higher than that of the other patients at that time. On the other hand, the treatment success rate was 76.9% at 7 days after the second administration, which was comparable with the expected level. The present study not only demonstrates that HF meal intake increases the IVM concentration in plasma and the stratum corneum in Japanese patients with scabies, but also suggests the possibility that HF meals increase the risk of hepatic dysfunction by the increased exposure of IVM.

Skin Antiageing and Systemic Redox Effects of Supplementation with Marine Collagen Peptides and Plant-Derived Antioxidants: A Single-Blind Case-Control Clinical Study

Recently, development and research of nutraceuticals based on marine collagen peptides (MCPs) have been growing due to their high homology with human collagens, safety, bioavailability through gut, and numerous bioactivities. The major concern regarding safety of MCPs intake relates to increased risk of oxidative stress connected with collagen synthesis (likewise in fibrosis) and to ROS production by MCPs-stimulated phagocytes. In this clinical-laboratory study, fish skin MCPs combined with plant-derived skin-targeting antioxidants (AO) (coenzyme Q10 + grape-skin extract + luteolin + selenium) were administered to volunteers (n = 41). Skin properties (moisture, elasticity, sebum production, and biological age) and ultrasonic markers (epidermal/dermal thickness and acoustic density) were measured thrice (2 months before treatment and before and after cessation of 2-month oral intake). The supplementation remarkably improved skin elasticity, sebum production, and dermal ultrasonic markers. Metabolic data showed significant increase of plasma hydroxyproline and ATP storage in erythrocytes. Redox parameters, GSH/coenzyme Q10 content, and GPx/GST activities were unchanged, while NO and MDA were moderately increased within, however, normal range of values. Conclusions. A combination of MCPs with skin-targeting AOs could be effective and safe supplement to improve skin properties without risk of oxidative damage.

Mechanism for transport of ivermectin to the stratum corneum in rats

Ivermectin (IVM) is used as an oral medication for scabies, a skin infection caused by a mite, sarcoptes scabiei, which parasitizes in the stratum corneum. After oral administration IVM is absorbed from the intestine, and finally distributed to the stratum corneum to eliminate the mites. However its transport mechanism remains unclear. A pharmacokinetic study was performed using hairless Wistar Yagi (HWY) rats, which have no or atrophied sebaceous glands, and Wistar rats as a reference. After oral administration of IVM to both groups, the area under the concentration-time curve of IVM in the dermis and epidermis (dermis-epidermis) of HWY rats were about 60% lower than that of Wistar rats, even though the plasma concentration profiles were comparable in both groups. In addition at 12 h after the administration, IVM concentration in the outer stratum corneum, the shallower layer of the dermis-epidermis, was higher compared to that in the deeper layer. In the dermis-epidermis of the skin from various locations, the concentrations of IVM and squalene, the latter of which is secreted to the skin surface via the sebaceous gland, were positively well correlated. Those results suggest that IVM is transported to the stratum corneum via the sebaceous glands.

Oxidization of squalene, a human skin lipid: a new and reliable marker of environmental pollution studies

A review of the oxidization of squalene, a specific human compound produced by the sebaceous gland, is proposed. Such chemical transformation induces important consequences at various levels. Squalene by-products, mostly under peroxidized forms, lead to comedogenesis, contribute to the development of inflammatory acne and possibly modify the skin relief (wrinkling). Experimental conditions of oxidation and/or photo-oxidation mechanisms are exposed, suggesting that they could possibly be bio-markers of atmospheric pollution upon skin. Ozone, long UVA rays, cigarette smoke… are shown powerful oxidizing agents of squalene. Some in vitro, ex vivo and in vivo testings are proposed as examples, aiming at studying ingredients or products capable of boosting or counteracting such chemical changes that, globally, bring adverse effects to various cutaneous compartments.

Human sebum extract induces barrier disruption and cytokine expression in murine epidermis

BACKGROUND

Previous studies have shown that human sebum may play a role in barrier function but with much debate.

OBJECTIVE

To elucidate the effects of human sebum on skin barrier function.

METHODS

We used hairless mouse skin to study the functional and morphological alternation of epidermis after the application of human sebum.

RESULTS

The results showed a significant increase in transepidermal water loss and erythema value, and a decrease in skin hydration, accompanied by epidermal hyperplasia with parakeratosis following sebum application. Nile red staining together with electron microscopic examination confirmed the underlying mechanisms for sebum-induced barrier disruption are related directly to the interaction of sebum with the intracellular lipid lamellae of the SC, thereby leading to the increase in the fluidity of SC intracellular lipids as demonstrated by ATR-FTIR measurement. An inflammatory reaction characterized by an enhanced cytokine cascade, including up-regulation of TNF-α, IL-1α and IL-6, was also observed. On the other hand, there were insignificant expression of thymic stromal lymphopoietin and unchanged serum levels of IgE, suggesting non-immunogenic stimulation by sebum treatment.

CONCLUSION

It may be concluded that inflammation induced by excess amount of sebum is more likely an irritant contact dermatitis rather than an allergic one. Moreover, these findings implicated possible relationships between sebum, irritant contact dermatitis, and seborrheic dermatitis.

Pharmacological stimulation of Edar signaling in the adult enhances sebaceous gland size and function

Impaired Ectodysplasin A (EDA) – EDA receptor (EDAR) signaling affects ectodermally derived structures including teeth, hair follicles and cutaneous glands. X-linked hypohidrotic ectodermal dysplasia (XLHED), resulting from EDA deficiency, can be rescued with lifelong benefits in animal models by stimulation of ectodermal appendage development with EDAR agonists. Treatments initiated later in the developmental period restore progressively fewer of the affected structures. It is unknown whether EDAR stimulation in adults with XLHED might have beneficial effects. In adult Eda mutant mice treated for several weeks with agonist anti-EDAR antibodies, we find that sebaceous glands size and function can be restored to wild type levels. This effect is maintained upon chronic treatment but reverses slowly upon cessation of treatment. Sebaceous glands in all skin regions respond to treatment, though to varying degrees, and this is accompanied in both Eda mutant and wild type mice by sebum secretion to levels higher than those observed in untreated controls. Edar is expressed at the periphery of the glands, suggesting a direct homeostatic effect of Edar stimulation on the sebaceous gland. Sebaceous gland size and sebum production may serve as biomarkers for EDAR stimulation, and EDAR agonists may improve skin dryness and eczema frequently observed in XLHED.

Vitamin E supplementation in canine atopic dermatitis: improvement of clinical signs and effects on oxidative stress markers

Low levels of plasma vitamin E concentrations were found in canine atopic dermatitis (CAD). The present study was aimed at determining the effect of an eight-week vitamin E supplementation on clinical response (Canine Atopic Dermatitis Extent and Severity Index (CADESI-03) scores and pruritus intensity) in dogs with atopic dermatitis. Levels of oxidative stress markers (plasma malondialdehyde and total antioxidant capacity (TAC), blood glutathione peroxidase and erythrocyte superoxide dismutase, plasma and skin vitamin E concentrations) were also determined. Twenty-nine dogs with CAD were included in the study. Fourteen received vitamin E (8.1 IU/kg once daily, orally) and 15 received mineral oil as placebo (orally). All dogs were treated with antihistamine fexofenadine. Levels of oxidative stress markers (with the exception of skin vitamin E), CADESI-03 and pruritus intensity were determined at the beginning, then every two weeks. Skin vitamin E was determined at the beginning and at the end of the treatment. Significantly higher plasma levels of vitamin E and TAC were observed in the vitamin E group than in the placebo group. CADESI-03 scores determined throughout the treatment in the vitamin E group were significantly lower than in the placebo group. The findings of this study support the supplementation of vitamin E in dogs with atopic dermatitis.

Monitoring of selected skin-borne volatile markers of entrapped humans by selective reagent ionization time of flight mass spectrometry in NO+ mode

Selective reagent ionization time-of-flight mass spectrometry with NO(+) as the reagent ion (SRI-TOF-MS (NO(+))) was applied for near real-time monitoring of selected skin-borne constituents which are potential markers of human presence. The experimental protocol involved a group of 10 healthy volunteers enclosed in a body plethysmography chamber mimicking the entrapment environment. A total of 12 preselected omnipresent in human scent volatiles were quantitatively monitored. Among them there were six aldehydes (n-propanal, n-hexanal, n-heptanal, n-octanal, n-nonanal, and 2 methyl 2-propenal), four ketones (acetone, 2-butanone, 3-buten-2-one, and 6-methyl-5-hepten-2-one), one hydrocarbon (2-methyl 2-pentene), and one terpene (DL-limonene). The observed median emission rates ranged from 0.28 to 44.8 nmol × person(-1) × min(-1) (16-1530 fmol × cm(-2) × min(-1)). Within the compounds under study, ketones in general and acetone in particular exhibited the highest abundances. The findings of this study provide invaluable information about formation and evolution of a human-specific chemical fingerprint, which could be used for the early location of entrapped victims during urban search and rescue operations (USaR).

Bioelectrocatalytic sensor for triglycerides in human skin sebum based on enzymatic cascade reaction of lipase, glycerol kinase and glycerophosphate oxidase

We report the development of an electrochemical biosensor for the quantification of triglycerides in human skin sebum, based on a multienzyme cascade reaction. The presence of excessive triglycerides in human sebum is one of the leading causes of various skin ailments. However, to the best of our knowledge, no bioelectrocatalytic approach for the quantification of sebum triglycerides has been made. In order to develop triglyceride biosensor, we fabricated a multienzyme-associated electrode incorporating lipase, glycerol kinase, and glycerophosphate oxidase. Enzymes were deposited by electrostatic force and further stabilized via crosslinking between enzymes and polymer matrices. The enzyme-modified biosensing electrode maintained its bioelectrocatalytic activity for five days. An additional constraint was the limited solubility of sebum triglycerides in aqueous electrolytes, impeding the analysis. To address this issue, triglyceride samples were prepared in the form of micelles, enabling efficient sample preparation for biosensor signaling. Calibration tests revealed that the designed assay had a detection range of 15-200mg/dL of micellar triglyceride, which covered the required determination range. The developed biosensing approach was successfully used to determine triglyceride concentrations in real sebum samples of unknown triglyceride content.