Benefits of topical natural ingredients in epidermal permeability barrier

Because of the crucial role of epidermal permeability barrier in regulation of cutaneous and extracutaneous functions, great efforts have been made to identify and develop the regimens that can improve epidermal permeability barrier function. Studies have demonstrated that oral administration of natural ingredients can improve epidermal permeability barrier in various skin conditions, including inflammatory dermatoses and UV-irradiation. Moreover, topical applications of some natural ingredients can also accelerate the repair of epidermal permeability barrier after acute barrier disruption and lower transepidermal water loss in the intact skin. Natural ingredient-induced improvements in epidermal permeability barrier function can be attributable to upregulation of keratinocyte differentiation, lipid production, antioxidant, hyaluronic acid production, expression of aquaporin 3 and sodium-hydrogen exchanger 1. In this review, we summarize the benefits of topical natural ingredients in epidermal permeability barrier in normal skin with or without acute barrier disruption and the underlying mechanisms.

Association of Epidermal Biophysical Properties with Obesity and Its Implications

BACKGROUND

Obesity is a condition defined by an excess amount of body fat, with body mass index (BMI) of 30 and higher. It is associated with a number of other medical conditions, including insulin resistance, diabetes mellitus, and cardiovascular diseases, as well as dyslipidemia, and it is also associated with several cutaneous disorders such as atopic dermatitis, psoriasis, intertriginous dermatitis, acanthosis nigricans and skin infections.

SUMMARY

Evidence suggests a link between obesity and epidermal dysfunction. Generally, individuals with obesity display higher transepidermal water loss rate and lower stratum corneum hydration levels, although no association of obesity with epidermal dysfunction has been documented. Results of skin surface pH are controversial. But study demonstrated a positive correlation of BMI with skin surface pH on both the forearm and the shin in males, suggesting that the changes in epidermal function vary with gender in individuals with obesity.

KEY MESSAGES

This review summarizes the association between obesity and epidermal function, and discusses possible underlying mechanisms. Individuals with obesity exhibit poor epidermal permeability barrier and lower stratum corneum hydration levels. Because of the pathogenic role of compromised epidermal function in inflammation, which is also linked to obesity, improvement in epidermal function could benefit individuals with obesity, particularly those with abnormalities in epidermal function.

Role of Resveratrol in Regulating Cutaneous Functions

Protective role of the skin is against external insults and maintenance of electrolyte homeostasis of the body. Cutaneous dysfunction can account for the development of both cutaneous and systemic disorders. Thus, improvements in cutaneous functions can benefit a number of extracutaneous and cutaneous functions. Resveratrol, a natural ingredient, displays multiple benefits for various systems/organs, including the skin. The benefits of resveratrol for cutaneous functions include stimulation of keratinocyte differentiation and antimicrobial peptide expression, inhibition of keratinocyte proliferation and cutaneous inflammation, UV protection, anticancer, antiaging, and inhibition of melanogenesis. The mechanisms of action of resveratrol include activation of sirtuin 1 and nuclear factor erythroid 2-related factor 2, and inhibition of mitogen-activated protein kinase signaling. Evidence suggests that topical resveratrol could be a valuable alternative not only for daily skin care, but also for the prevention and treatment of various cutaneous disorders. This review summarizes the benefits of resveratrol for cutaneous functions.

A topical heparinoid-containing product improves epidermal permeability barrier homeostasis in mice

Because of the importance of epidermal functions, including stratum corneum hydration and maintenance of permeability barrier homeostasis, in the pathogenesis of a variety of cutaneous and systemic disorders, a wide range of products has been developed to improve epidermal functions. However, the underlying mechanisms whereby certain products, including heparinoid-containing product, are far little understood. In the present study, we assessed the impact of a heparinoid-containing product, Hirudoid^® cream, on epidermal permeability barrier function and expression levels of a panel of epidermal mRNA related to the formation/maintenance of the permeability barrier in mouse skin. Our results showed that while the baseline levels of transepidermal water rates remained unchanged, treatment with Hirudoid^® cream twice daily for 7 days significantly accelerated permeability barrier recovery and increased stratum corneum hydration. In parallel, expression levels of epidermal mRNA for certain differentiation marker-related proteins, lipid synthetic enzymes, keratinocyte proliferation and antimicrobial peptides also increased significantly. Together, these results provide the underlying mechanisms by which topical Hirudoid^® cream improves epidermal permeability barrier and antimicrobial function. Because of its benefits for epidermal functions, heparinoid-containing product could be more useful in the management of skin conditions, characterized by abnormal permeability barrier and antimicrobial function.

Nanoparticles for transcutaneous vaccination

The living epidermis and dermis are rich in antigen presenting cells (APCs). Their activation can elicit a strong humoral and cellular immune response as well as mucosal immunity. Therefore, the skin is a very attractive site for vaccination, and an intradermal application of antigen may be much more effective than a subcutaneous or intramuscular injection. However, the stratum corneum (SC) is a most effective barrier against the invasion of topically applied vaccines. Products which have reached the stage of clinical testing, avoid this problem by injecting the nano‐vaccine intradermally or by employing a barrier disrupting method and applying the vaccine to a relatively large skin area. Needle‐free vaccination is desirable from a number of aspects: ease of application, improved patient acceptance and less risk of infection among them. Nanocarriers can be designed in a way that they can overcome the SC. Also incorporation into nanocarriers protects instable antigen from degradation, improves uptake and processing by APCs, and facilitates endosomal escape and nuclear delivery of DNA vaccines. In addition, sustained release systems may build a depot in the tissue gradually releasing antigen which may avoid booster doses. Therefore, nanoformulations of vaccines for transcutaneous immunization are currently a very dynamic field of research. Among the huge variety of nanocarrier systems that are investigated hopes lie on ultra‐flexible liposomes, superfine rigid nanoparticles and nanocarriers, which are taken up by hair follicles. The potential and pitfalls associated with these three classes of carriers will be discussed.

Incontinence in the aged: contact dermatitis and other cutaneous consequences

Urinary and faecal incontinence affects a significant portion of the elderly population. The increase in the incidence of incontinence is not only dependent on age but also on the onset of concomitant ageing issues such as infection, polypharmacy, and decreased cognitive function. If incontinence is left untreated, a host of dermatological complications can occur, including incontinence dermatitis, dermatological infections, intertrigo, vulvar folliculitis, and pruritus ani. The presence of chronic incontinence can produce a vicious cycle of skin damage and inflammation because of the loss of cutaneous integrity. Minimizing skin damage caused by incontinence is dependent on successful control of excess hydration, maintenance of proper pH, minimization of interaction between urine and faeces, and prevention of secondary infection. Even though incontinence is common in the aged, it is not an inevitable consequence of ageing but a disorder that can and should be treated. Appropriate clinical management of incontinence can help seniors continue to lead vital active lives as well as avoid the cutaneous sequelae of incontinence.

Culture of human epidermal Langerhans cells in a skin equivalent

Langerhans cells (LCs) have been cultured in a skin equivalent (SE). Seventy-two SEs were produced by inserting skin biopsies from nine subjects into dermal equivalents consisting of fibroblasts in a collagen matrix. The SEs were cultured in a serum-free medium containing 2-mercaptoethanol with or without 5 ng/mL granulocyte-monocyte colony-stimulating factor (GM-CSF). The SEs were cultured for 12 or 15 days. In the latter case, 0, 1 or 10 microg/mL cyclosporin A (CyA) was added for the last 3 days. The SEs were then snap frozen for immunohistochemistry. The migration of LCs was evaluated by measuring the distances from the inserted skin biopsy in the SEs to the HLA-DR + and CD1a+ dendritic cells localized at the longest distance from the biopsy in the epidermal outgrowth on both sides of the biopsy. The density of these cells was estimated in 15-day-old SEs by counting them on both sides of the inserted skin biopsy and dividing the number of positive cells by the migrated distances. All epidermal outgrowths (range 0.6-3.7 mm) were well differentiated and displayed HLA-DR+, CD1a+ and Lag+ dendritic cells. Only occasionally were CD83+ cells observed. In the 15-day-old SEs cultured with GM-CSF, a few CD86+ cells were seen in the epidermal outgrowths and occasionally CD80+ cells. The median (n = 4) density of CD1a+ and HLA-DR+ cells in the epidermal outgrowths at day 15 was 5.2 and 9.1 cells/mm, respectively. GM-CSF did not influence migration in 12-day-old SEs, but there was a tendency to increased migration of HLA-DR+ dendritic cells in 15-day-old SEs. CyA did not affect migration or density. We conclude that LCs can be cultured with an in vivo-like density in a SE. They express the phenotype of immature antigen-presenting cells efficient in capturing and processing antigen. This model may be suitable for studies of the initial phase of contact allergic reactions.