Skin - a vast organ with immunological function (Review)

Universal optimal design in the vertebrate limb pattern and lessons for bioinspired design

This paper broadly summarizes the variation of design features found in vertebrate limbs and analyses the resultant versatility and multifunctionality in order to make recommendations for bioinspired robotics. The vertebrate limb pattern (e.g. shoulder, elbow, wrist and digits) has been proven to be very successful in many different applications in the animal kingdom. However, the actual level of optimality of the limb for each animal application is not clear because for some cases (e.g. whale flippers and bird wings), the basic skeletal layout is assumed to be highly constrained by evolutionary ancestry. This paper addresses this important and fundamental question of optimality by analysing six limbs with contrasting functions: human arm, whale flipper, bird wing, human leg, feline hindlimb and frog hindlimb. A central finding of this study is that the vertebrate limb pattern is highly versatile and optimal not just for arms and legs but also for flippers and wings. One key design feature of the vertebrate limb pattern is that of networks of segmented bones that enable smooth morphing of shapes as well as multifunctioning structures. Another key design feature is that of linkage mechanisms that fine-tune motions and mechanical advantage. A total of 52 biomechanical design features of the vertebrate limb are identified and tabulated for these applications. These tables can be a helpful reference for designers of bioinspired robotic and prosthetic limbs. The vertebrate limb has significant potential for the bioinspired design of robotic and prosthetic limbs, especially because of progress in the development of soft actuators.

Compromised skin barrier induced by prolonged face mask usage during the COVID-19 pandemic and its remedy with proper moisturization

BACKGROUND

Prolonged face mask usage, a daily practice for the public due to the COVID-19 pandemic, creates high levels of humidity underneath the mask, which may cause unexpected skin concerns.

OBJECTIVE

To investigate the impact of repeated mask usage on the face by comparing skin properties inside and outside of the mask-covered areas.

METHODS

A double-blinded, randomized, split-face clinical study was conducted with 21 healthy female participants who wore face masks at least 6 h every day for 1 week, with one side of their face treated with a moisturizer three times daily. On day 8, after 5 h of wearing the mask, skin properties (sebum, hydration, and trans-epidermal water loss [TEWL]) were evaluated at 15, 60, and 120 min post-mask removal, followed by barrier disruption and recovery assessment.

RESULTS

Mask usage weakened stratum corneum (SC) on facial skin compared to uncovered areas, including reduced SC hydration (p < 0.02 at 15 min) and increased TEWL in response to tape stripping challenge (p < 0.03 after stripping). In addition, sebum production also increased after mask removal (p < 0.01 at 15 min). Notably, a daily moisturizer mitigated these effects by increasing SC hydration (p < 0.001) and improving SC resilience against barrier disruption.

CONCLUSION

Daily prolonged usage of a facial mask, essential due to the COVID-19 situation, generated a high-humidity microenvironment and led to compromised SC, which was revealed by a barrier challenge technique. Moreover, proper facial moisturization may help to maintain skin homeostasis and prevent the barrier impairment caused by repeated mask usage.

Chemopreventive Effects of Oral Pterostilbene in Multistage Carcinogenesis of Skin Squamous Cell Carcinoma Mouse Model Induced by DMBA/TPA

Skin squamous cell carcinoma (SCC) is a type of non-melanoma skin cancer. Pterostilbene is a natural compound proven to exhibit various pharmacological properties, including chemo-preventive effects. This study aimed to explore the chemo-preventive effect of oral pterostilbene during initiation, promotion or continuous on multistage skin SCC mouse models induced by 7,12-Dimethylbenz(a)anthracene (DMBA)/12-O-Tetradecanoylphorbol-13-acetate (TPA). The experimental design consists of five groups of female Institute of Cancer Research (ICR) mice, with two control groups of vehicle and cancer. Three oral pterostilbene groups consisted of orally administered pterostilbene during initiation, promotion, or continuously. Oral pterostilbene significantly reduced the number and volume of tumours. Oral pterostilbene demonstrated less severe skin histology changes compared to the cancer control group, with less pleomorphic in the cells and nuclei, and the basement membrane remained intact. Our results showed fewer invasive tumours in oral PT-treated groups than in cancer groups that displayed mitotic bodies, highly pleomorphic cells and nuclei, and basement membrane invasion. The cell proliferation marker (Ki-67) was reduced in oral pterostilbene-treated groups. Overall, oral pterostilbene is a promising chemo-preventive intervention due to its anti-initiation and anti-promotion on skin carcinogenesis. Thus, the potential molecular mechanisms of oral pterostilbene chemo-prevention agent should be explored.

The family of kallikrein-related peptidases and kinin peptides as modulators of epidermal homeostasis

The epidermis is the outermost skin layer and is part of one of the largest organs in the body; it is supported by the dermis, a network of fibrils, blood vessels, pilosebaceous units, sweat glands, nerves, and cells. The skin as a whole is a protective shield against numerous noxious agents, including microorganisms and chemical and physical factors. These functions rely on the activity of multiple growth factors, peptide hormones, proteases, and specific signaling pathways that are triggered by the activation of distinct types of receptors sited in the cell membranes of the various cell types present in the skin. The human kallikrein family comprises a large group of 15 serine proteases synthesized and secreted by different types of epithelial cells throughout the body, including the skin. At this site, they initiate a proteolytic cascade that generates the active forms of the proteases, some of which regulate skin desquamation, activation of cytokines, and antimicrobial peptides. Kinin peptides are formed by the action of plasma and tissue kallikreins on kininogens, two plasma proteins produced in the liver and other organs. Although kinins are well known for their proinflammatory abilities, in the skin they are also considered important modulators of keratinocyte differentiation. In this review, we summarize the contributions of the kallikreins and kallikrein-related peptidases family and those of kinins and their receptors in skin homeostasis, with special emphasis on their pathophysiological role.

Non-Pharmacological Treatments of Psoriasis in Persian Medicine a Narrative Review

Psoriasis is a chronic disease that has no definitive cure. In this review study, the main sources of Persian Medicine (PM) such as the Canon of Medicine (by Avicenna) and Al-Havi (by Rhazes) were assessed to identify non-pharmacological treatments for psoriasis. Several treatments that are recommended for this disease include nutritional advice, lifestyle modifications, and manipulation therapy such as wet cupping (Hijamah), leech therapy, and phlebotomy (Fasd). These recommendations may help to prevent recurrence and be useful in improving psoriasis. The efficacy of PM recommendations to improve psoriasis should be evaluated in future studies.

Mucocutaneous lesions associated with SARS‑CoV‑2 infection (Review)

The ongoing COVID-19 pandemic, declared by the World Health Organisation in March 2020, with the emergence of new, possibly more contagious and more virulent strains, remains a research subject, with the complex systemic involvement better described and understood, but also with a variety of skin and mucosal lesions described in the literature. Mucocutaneous lesions associated with SARS-CoV-2 infection are still under investigation, due to their polymorphic clinical aspect and incompletely understood pathogenic mechanism. The cutaneous inflammatory, exanthematous and purpuric rashes, erythemato-purpuric enanthems, oral ulcers, lichenoid oral lesions, conjunctivitis, conjunctival pseudomembranes, or corneal lesions have been described in patients with COVID-19. Several classifications have been proposed based on the clinical pattern, histological findings, and possible pathogenic mechanisms. The pathogenic mechanism, the diagnostic criteria, the prognostic importance of these lesions are still being debated. The diverse clinical aspects of dermatological manifestations render the diagnosis difficult. However, several clinical patterns strongly associated with COVID-19, such as chilblains, papulovesicular exanthems, and febrile rash require increased awareness and changes to the investigation protocols for these conditions, to include testing for SARS-CoV-2. In the present review, the mucocutaneous findings associated with the novel coronavirus infection, reported thus far in the literature, was provided.

Metabolic comorbidities of psoriasis (Review)

Psoriasis is a chronic inflammatory and immune-mediated condition, which is no longer considered as being limited to the skin, but may affect the entire body. Epidemiological studies have shown that certain disorders, including obesity, diabetes, liver abnormalities, elevated lipid levels in the blood and metabolic syndrome, may occur more frequently in patients with psoriasis compared with the general population. As psoriasis is a chronic disease, the frequently associated comorbidities must be identified early to ensure timely treatment and, possibly, their prevention. Comorbidities often manifest clinically 1-2 years after the onset of psoriasis and are commonly seen in patients with severe forms of the disease. The association between psoriasis and its comorbidities is not coincidental, but rather based on common pathophysiological mechanisms and risk factors that underlie the increased frequency of comorbidities in patients with psoriasis. The aim of the present review was to emphasize the important role of dermatologists in the early recognition of comorbidities in patients with psoriasis, with a focus on metabolic comorbidities, precisely because the dermatologists are usually the first medical contact due to the predominance of skin lesions. Therefore, these specialists have the responsibility to inform patients on the association between psoriasis and possible multiple comorbidities, devise prevention and treatment plans, or even redirect patients to other specialists.

Cardiovascular comorbidities in psoriasis (Review)

Long considered a skin-limited condition, psoriasis is currently defined as a chronic, immune-mediated inflammatory disease, presenting, besides the skin changes, important systemic manifestations, the most common being: psoriatic arthritis, cardiovascular disease, metabolic syndrome, diabetes, inflammatory bowel disease and nonalcoholic steatohepatitis. It is a disease with a strong psycho-emotional and social impact, both through skin changes such as pruritic, scaly erythematous plaques, and through the association of comorbidities that influence morbidity and mortality. It has been shown that psoriasis is an independent cardiovascular risk factor, with patients developing ischemic heart disease/acute coronary syndrome, hypertension, peripheral arterial disease, or stroke. The chronic inflammatory status of psoriasis and the production of specific cytokines may be the etiopathogenic link to atherosclerosis and cardiovascular disease. Biological therapy may affect atherosclerosis, leading to the arrest of the evolution or even regressing the changes in the atheromatous plaque. The aim of this review was to re-evaluate the current knowledge regarding the cardiovascular comorbidities associated with psoriasis for optimal management of the patients.

Immunomodulatory Properties of Host Defence Peptides in Skin Wound Healing

Cutaneous wound healing is a vital biological process that aids skin regeneration upon injury. Wound healing failure results from persistent inflammatory conditions observed in diabetes, or autoimmune diseases like psoriasis. Chronic wounds are incurable due to factors like poor oxygenation, aberrant function of peripheral sensory nervature, inadequate nutrients and blood tissue supply. The most significant hallmark of chronic wounds is heavily aberrant immune skin function. The immune response in humans relies on a large network of signalling molecules and their interactions. Research studies have reported on the dual role of host defence peptides (HDPs), which are also often called antimicrobial peptides (AMPs). Their duality reflects their potential for acting as antibacterial peptides, and as immunodulators that assist in modulating several biological signalling pathways related to processes such as wound healing, autoimmune disease, and others. HDPs may differentially control gene regulation and alter the behaviour of epithelial and immune cells, resulting in modulation of immune responses. In this review, we shed light on the understanding and most recent advances related to molecular mechanisms and immune modulatory features of host defence peptides in human skin wound healing. Understanding their functional role in skin immunity may further inspire topical treatments for chronic wounds.

Skin endometriosis: A case report and review of the literature

Skin endometriosis is a rare disease with variable clinical and histopathological characteristics that depend on hormonal stimuli. The skin is not a common location, as most cases of endometriosis involve pelvic sites, such as the ovaries, peritoneum and bowel. However, the most common extrapelvic site affected is the abdominal wall and this location of the disease is frequently associated with obstetric and gynecologic surgery. Here we report a case of skin endometriosis emerged as a painful subcutaneous nodule located near to the left side of an obstetrical surgery procedure scar. The patient affected was a woman in her reproductive age, with a history of right ovary endometriotic cyst laparoscopically removed and histologically confirmed as a primary endometriosis. Dermatologists should be aware of this condition in any woman with a painful lump located in the proximity of a pelvic surgery-induced scar. Its non-specific clinical appearance may confuse the clinician and may delay the diagnosis and management.

Physicochemical Characterization of Finasteride Nanosystem for Enhanced Topical Delivery

INTRODUCTION

The current work aimed to formulate a novel chitosan-based finasteride nanosystem (FNS-NS) for skin delivery to optimize the drug availability in skin for a longer time and enhance ex vivo performance of finasteride against androgenic alopecia.

METHODS

Both undecorated and chitosan decorated FNS-NSs were synthesized by a high energy emulsification technique. All the prepared nanosystems were further subjected to physicochemical characterizations like pH, viscosity, encapsulation efficiency, surface morphology and in vitro drug release behavior. The influence of the nanosystem on the drug permeation and retention in rat skin was examined using Franz diffusion cell apparatus.

RESULTS

The droplet size of developed nanosystems ranged from 41 to 864 nm with a low polydispersity index. The zeta potential of the nanosystems was between -10 mV and +56 mV. This chitosan decorated nanosystem exhibited controlled drug release, ie about 78-97% in 24 h. Among all the nanosystems, our chitosan decorated formulation (F5) had low drug permeation (16.35 µg/cm2) and higher drug retention (10.81 µg/cm2).

CONCLUSION

The abovementioned results demonstrate satisfactory in vitro drug release, skin retention profiles and ex vivo performance with chitosan decorated FNS-NS (F5). This optimized formulation could increase drug availability in skin and could become a promising carrier for topical delivery to treat androgenic alopecia.