Are pruritus and scratching the cough of the skin?

Pruritus is not the equivalent of the cough of the skin, but itch and scratch can certainly be defined as such. In physiological conditions, they share the same function: to exclude a foreign body. Itch/scratching and cough could be selective responses for the same diseases, mainly atopic diseases, and their pathophysiology is similar (role of C fibers and mast cells; role of histamine, substance P and tachykinins). This is an intriguing analogy rather than a pathophysiological identity. It may be inappropriate for many disease settings. Itch and cough can be triggered or enhanced by stress. This similarity is very interesting because it could give rise to many new research ideas.     

Validation of Dermaphot® for the assessment of steroid-induced skin atrophy

Currently, there are no accurate and simple methods available to measure this risk of atrophy in patients treated with topical glucocorticosteroids. In the present clinical trial, we validated a new score (Dermaphot^® score) to assess the atrophogenic potential of glucocorticosteroids. 36 healthy adult volunteers were included in an investigator-initiated, blinded, randomized, intra-individual comparison, vehicle controlled multi-centre study. Subjects were treated in a randomized manner for 3 weeks with pimecrolimus cream 1 %, mometasone furoate (1 mg/g), clobetasol propionate 0.05 % and vehicle. In addition, ultrasound examination for skin thickness was performed. Data demonstrated a direct correlation of the achieved Dermaphot^® score and the ultrasound thickness measurements. Our study shows that the Dermaphot^® score can be used as a simple method to evaluate the atrophogenic potential of glucocorticosteroids. Respectively, we showed that the new score is an easy, valid and sensitive new tool for early detecting and quantifying even subclinical glucocorticosteroid-induced skin damage. We demonstrated that the score is able to differentiate the extent of skin atrophy (damage) after 3 weeks of topical glucocorticosteroid application with different levels of skin transparency and levels of telangiectasia.     

Optimising the design of a broad‐band light source for the treatment of skin

Phototherapy has become a treatment of choice in many areas of medicine. Light can be used to deliver energy to tissue selectively targeting specific structures in order to induce the desired therapeutic outcome. The choice of optical parameters for a specific application is not simple. Wavelength, energy, exposure time and fluence can be varied and induce a wide range of tissue effects. The treatment of the skin with light is probably the one phototherapy application that is most developed in terms of technology and market maturity. White light systems are extensively used to address a range of skin conditions. However, different conditions have different physiology and hence require differing optical parameters. The technology standard is based upon systems, which have a number of different optical filters allowing the output to be tailored to the specific application. This paper discusses the advantages of a diferent type of system, namely the iPulse i300 (Cyden Ltd, Swansea, UK), which uses a single dichroic reflectance filter and whose optical output is changed by varying other parameters in a carefully controlled manner.     

Uneven Distribution of M. leprae in the skin of LL patients

In LL patients, the skin-slit smear examination from earlobe, forehead, elbow, wrist, thigh and ankIe revealed that the BI and count per field of M. leprae gradually decreased from earlobe to the ankle. Such uneven distribution is more evident at the beginning of the disease, Nose might act as a 'reserve pool' from where the M. leprae might migrate to different parts of the body. Lymph and blood might not be playing any role in transporting M. leprae from the nose to different sites of the skin. It is suggested that no carrier perhaps is involved in transporting M. leprae to different sites in the epidermis, but they might get thrusted mechanically from nose to other parts of the body i.e. from the site of higher density to neighbouring sites.     

What is the biological basis of pattern formation of skin lesions?

Pattern recognition is at the heart of clinical dermatology and dermatopathology. Yet, while every practitioner of the art of dermatological diagnosis recognizes the supreme value of diagnostic cues provided by defined patterns of 'efflorescences', few contemplate on the biological basis of pattern formation in and of skin lesions. Vice versa, developmental and theoretical biologists, who would be best prepared to study skin lesion patterns, are lamentably slow to discover this field as a uniquely instructive testing ground for probing theoretical concepts on pattern generation in the human system. As a result, we have at best scraped the surface of understanding the biological basis of pattern formation of skin lesions, and widely open questions dominate over definitive answer. As a symmetry-breaking force, pattern formation represents one of the most fundamental principles that nature enlists for system organization. Thus, the peculiar and often characteristic arrangements that skin lesions display provide a unique opportunity to reflect upon--and to experimentally dissect--the powerful organizing principles at the crossroads of developmental, skin and theoretical biology, genetics, and clinical dermatology that underlie these--increasingly less enigmatic--phenomena. The current 'Controversies' feature offers a range of different perspectives on how pattern formation of skin lesions can be approached. With this, we hope to encourage more systematic interdisciplinary research efforts geared at unraveling the many unsolved, yet utterly fascinating mysteries of dermatological pattern formation. In short: never a dull pattern!     

Homocysteine may accelerate skin aging: a new chapter in the biology of skin senescence?

Skin aging has received tremendous attention in recent years by both scientists and the lay public. This article reviews the evidence that homocysteine, an intermediary sulfhydryl-containing amino acid implicated in atherosclerosis, can accelerate skin aging and the aging of internal organs (universal aging).     

Structure and function of the skin. Are there differences between black and white skin?

In concluding my remarks on structure and function of the skin, I wish to make one additional observation. Most dermatologists have acknowledged the role of the skin and its ability to protect the human organism from invasion by pathogenic organisms. There is good scientific evidence that skin plays an important protective role. Although an intact epidermis is of utmost importance as a protective unit, the contribution of the "acid mantle" is of considerable magnitude. The acidity or alkalinity and stability of this mantle is contributed to, in large measure, by the presence of eccrine gland secretions and sebaceous gland secretions. It is then not logical to assume that if black skin contains larger numbers of large and overly active adnexal glands, it would have a most effective mechanism for control of bacterial, viral, and other infections? That this is not the situation becomes apparent in the discussions that follow on cutaneous infections in black skin.     

Barrier function of the skin: "la raison d'être" of the epidermis

The primary function of the epidermis is to produce the protective, semi-permeable stratum corneum that permits terrestrial life. The barrier function of the stratum corneum is provided by patterned lipid lamellae localized to the extracellular spaces between corneocytes. Anucleate corneocytes contain keratin filaments bound to a peripheral cornified envelope composed of cross-linked proteins. The many layers of these specialized cells in the stratum corneum provide a tough and resilient framework for the intercellular lipid lamellae. The lamellae are derived from disk-like lipid membranes extruded from lamellar granules into the intercellular spaces of the upper granular layer. Lysosomal and other enzymes present in the extracellular compartment are responsible for the lipid remodeling required to generate the barrier lamellae as well as for the reactions that result in desquamation. Lamellar granules likely originate from the Golgi apparatus and are currently thought to be elements of the tubulo-vesicular trans-Golgi network. The regulation of barrier lipid synthesis has been studied in a variety of models, with induction of several enzymes demonstrated during fetal development and keratinocyte differentiation, but an understanding of this process at the molecular genetic level awaits further study. Certain genetic defects in lipid metabolism or in the protein components of the stratum corneum produce scaly or ichthyotic skin with abnormal barrier lipid structure and function. The inflammatory skin diseases psoriasis and atopic dermatitis also show decreased barrier function, but the underlying mechanisms remain under investigation. Topically applied "moisturizers" work by acting as humectants or by providing an artificial barrier to trans-epidermal water loss; current work has focused on developing a more physiologic mix of lipids for topical application to skin. Recent studies in genetically engineered mice have suggested an unexpected role for tight junctions in epidermal barrier function and further developments in this area are expected. Ultimately, more sophisticated understanding of epidermal barrier function will lead to more rational therapy of a host of skin conditions in which the barrier is impaired.     

What is the role of mitochondrial dysfunction in skin photoaging?

Skin ageing is a complex process involving both internal and external factors, which leads to a progressive loss of cutaneous function and structure. Solar radiation is the primary environmental factor implicated in the development of skin ageing, and the term photoaging describes the distinct clinical, histological and structural features of chronically sun‐exposed skin. The changes that accompany photoaging are undesirable for aesthetic reasons and can compromise the skin and make it more susceptible to a number of dermatological disorders. As a result, skin ageing is a topic that is of growing interest and concern to the general population, illustrated by the increased demand for effective interventions that can prevent or ameliorate the clinical changes associated with aged skin. In this viewpoint essay, we explore the role that mitochondria play in the process of skin photoaging. There is continuing evidence supporting the proposal that mitochondrial dysfunction and oxidative stress are important contributing factors in the development of skin photoaging. Further skin‐directed mitochondrial research is warranted to fully understand the impact of mitochondrial status and function in skin health. A greater understanding of the ageing process and the regulatory mechanisms involved could lead to the development of novel preventative interventions for skin ageing.     

Can increasing the viscosity of formulations be used to reduce the human skin penetration of the sunscreen oxybenzone?

The effect of adding thickening agents on the penetration of a sunscreen benzophenone-3 through epidermal and a high-density polyethylene membrane was studied using both very thick (infinite dose) and thin (in use) applications. Contradictory results were obtained. Thickening agents retard skin penetration, in a manner consistent with a diffusional resistance in the formulation, when applied as an infinite dose. In contrast, when applied as in thin (in use) doses, thickening agents promote penetration, most likely through greater stratum corneum diffusivity arising from an enhanced hydration by the thicker formulations. The two key implications from this work are (i) a recognition of the danger in the potential extrapolation of infinite dosing to in use situations, and (ii) to recognize that thicker formulations may sometimes enhance the penetration of other topical agents when applied "in use".     

How does the type of vehicle influence the in vitro skin absorption and elimination kinetics of terpenes?

Terpenes are widely used in the topical dermal preparations, cosmetics and toiletries and also in the experimental dermopharmacy, as penetration enhancers. Terpenes do not need to penetrate into viable skin tissue and this event is not even desired. The aim of this study was to investigate skin absorption and elimination kinetics of two terpenes, namely linalool and terpinen-4-ol, incorporated in three different dermatological vehicles: oily solution, hydrogel and o/w emulsion. The preparations were applied onto the human skin in vitro, and after 1–4 h the content of terpenes in the stratum corneum layers and in the epidermis/dermis was determined using GC. Similarly, the amounts of terpenes in the skin were analysed during 4 h elimination process following 1 h absorption. The highest skin absorption was observed when terpenes were applied in hydrogel — their total content in the skin after 4 h was 385 and 705 μg/cm² for linalool and terpinen-4-ol, respectively. After 1 h of the elimination process about 10–20% drop of the total content of both terpenes in the skin was noted for all formulations. The skin penetration of both terpenes from the vehicles is increasing in the following order: emulsion < oily solution < hydrogel, while the elimination phase is relatively slower for terpenes applied in hydrogel.     

Sebaceous gland: Milestones of 30-year modelling research dedicated to the “brain of the skin”

In 2018, Schneider and Zouboulis analysed the available tools for studying sebaceous gland pathophysiology in vitro. Since then, the interest in this field remains unbroken, as demonstrated by recent reviews on sebaceous gland physiology, endocrinology and neurobiology, the role of sebaceous glands beyond acne, and several original works on different areas of sebaceous gland function, including sebaceous lipogenesis. Landmark developments in the first part of the 30-year modelling research dedicated to the sebaceous gland, which is considered by several scientists as the brain of the skin, were the short-term culture of human sebaceous glands, the culture of human sebaceous gland cells and the development of immortalized sebaceous gland cell lines exhibiting characteristics of normal sebocytes. On the other hand, current developments represent the establishment of sebaceous gland spheroids, the 3D-SeboSkin model of viable skin explants ex vivo, the combination of culture-expanded epidermal stem cells of mice and adult humans to form de novo hair follicles and sebaceous glands, when they are transplanted into excisional wounds in mice, and 3D-printed scaffolds coated with decellularized matrix of adipose-derived mesenchymal stromal cells and SZ95 sebocytes. These novel tools may become useful platforms for better understanding of cellular and molecular mechanisms governing sebocyte biology and sebaceous gland homeostasis, such as the changes in sebum synthesis and composition, the infundibular differentiation and the influence of the innate immunity and the cutaneous microbiome and for identifying potential therapeutic targets of skin diseases affecting the sebaceous glands.     

Validity of skin blot examination for albumin and nerve growth factor β to detect itching of the skin in Indonesian older adults

AimItching, a common skin disorder, impacts the quality of life of individuals. Itchy skin occurs more with increasing age and the prediction of itchy skin prognosis is necessary to provide good skincare. This study validated biomarkers in skin blotting to identify and measure itching sensation as well as conventional methods to measure skin barrier function.Materials and methodsFrom a cross-sectional study conducted in Long-term Care (LTC) facilities in Indonesia itching symptoms were obtained through a questionnaire. Skin conditions were assessed using photographs, stratum corneum (SC) hydration, skin pH, and skin blotting for biomarkers: albumin, interleukin 2 (IL2), nerve growth factor β (NGFβ), and thymic stromal lymphopoietin (TSLP). Association of skin measurements with the presence of skin blotting and trends analysis were conducted.ResultsAltogether, 564 LTC residents (average age, 70 years) participated. The SC hydration, skin pH, albumin, and NGFβ were associated with the presence of itch (p value= <0.001, <0.001, <0.001, and <0.001, respectively). The signal levels of skin blotting biomarkers were higher in itch group than in the non-itch group. Additionally, the higher quantile of SC hydration was significantly associated with a lower intensity level of NGFβ and TSLP (p value = 0.005, 0.003, respectively). The lower quantile of skin pH (better skin condition) was significantly associated with lower albumin, NGFβ, and TSLP (p value = 0.048, 0.035, and <0.001, respectively).ConclusionThe albumin, NGFβ, and TSLP could be a candidate for measurement of itchy skin among older adult with disrupted skin barrier function and local skin inflammation.     

Chemotherapeutical treatment of basal cell carcinoma with bleomycin via microinfusion of the drug into the skin (MMP®)

BackgroundBleomycin is a chemotherapeutical drug used to treat several neoplasias, including non-melanoma skin cancer; it is effective in the treatment of basal cell carcinoma (BCC) via intralesional infiltration. Transdermal drug delivery, which includes technologies such as CO₂ Laser, Dermapen, Dermaroller and MMP®, delivers the desired medication to treat skin neoplasias and also acts in skin rejuvenation.ObjectiveTo treat BCC lesions using bleomycin via MMP®.MethodsNinety-eight BCC lesions in different anatomical areas were treated using MMP® technology to administer and uniformly distribute bleomycin throughout the lesion and in the established safety margin.ResultsThe cure rate after six months was 96.94%; and recurrences were not associated with lesion size and/or depth. Adverse effects were the expected ones.Study limitationsThe follow-up time was only six months.ConclusionThis therapeutic route showed to be promising and effective.     

Q‐switched ruby laser irradiation on spotty pigmentation in the skin of the hairless dog

OBJECTIVE: To investigate macroscopically and histopathologically the dermatological changes after Q‐switched ruby laser (QRL) irradiation with different exposure doses in UVB‐induced pigmentation in hairless dogs.

METHODS: QRL irradiation with 3.0, 5.0 and 7.0?J/cm² was carried out on the UVB‐induced spotty pigmentation in the skin of the hairless dog. Gross appearance was observed daily throughout this study. Histopathological examination was performed 1 day before QRL irradiation and 1 and 3 days and 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14 and 16 weeks after QRL irradiation.

RESULTS: Immediately after QRL irradiation, spotty pigmentation was removed. One week after QRL irradiation, re‐epithelialization started from the margin of the irradiated sites. between 5 and 10 weeks after QRL irradiation, the skin color returned to normal and some portions showed recurrence of hyperpigmentation. Histopathologically, spotty pigmentation had a heavy deposition of melanin granules in the stratum basale, spinosum and corneum. One day after QRL irradiation, the skin showed destruction of melanin granules. Seven days after QRL irradiation, re‐epithelialization began from the surroundings of the QRL‐irradiated sites and the pilosebaceous units. The delayed process of re‐epithelialization was dependent on the incident exposure dose with QRL. The repaired epidermis was devoid of melanin granules. By 5 weeks after QRL irradiation with 3.0 and 5.0?J/cm², the stratum basale and spinosum revealed a redistribution of melanin granules. In the sites of recurrent hyperpigmentation, the bases of the remaining hair follicles showed a notable increase in the reproduction of melanin granules. Melanin granules abundantly aggregated in the bottom portion of the nucleus in each epidermal cell.

CONCLUSION: These results revealed that hairless dogs were invaluable laboratory animals, which developed spotty pigmentation after successive UVB irradiation. In addition, UVB‐induced spotty pigmentation in hairless dogs is useful for investigating the process of depigmentory treatment with QRL irradiation and recurrence of this lesion.