Calmodulin‐like skin protein level increases in the differentiated epidermal layers in atopic dermatitis

In atopic dermatitis (AD), the skin barrier is disturbed, and the expression of calcium‐dependent S100 proteins and the calcium gradient is also altered in the epidermis. The calmodulin‐like skin protein (CLSP), which is expressed in the differentiated epidermis, is believed to modulate the function of calcium‐dependent proteins involved in barrier formation and is significantly increased in the epidermis of psoriatic patients. We, therefore, investigated the CLSP level in skin biopsies taken from patients with acute exacerbated and non‐exacerbated AD as well as from healthy control subjects. Immunohistochemical, Western blot and ELISA analyses showed significant increases (P < 0.03) in CLSP level in the epidermis from patients with acute exacerbated AD as compared to that from patients with non‐exacerbated AD and from control subjects. Such increased expression of CLSP may help re‐establish a functional epidermal barrier in acute AD.     

Superiority of a vitamin B12‐barrier cream compared with standard glycerol‐petrolatum‐based emollient cream in the treatment of atopic dermatitis: A randomized,left‐to‐right comparative trial

Atopic dermatitis (AD) is a result of complex genetic, epigenetic, environmental, and immunological interactions with an overlapping epidermal barrier defect. The study evaluates the efficacy and tolerability of topical Vitamin B12‐barrier cream (MB12) compared with standard glycerol‐petrolatum‐based emollient cream (GPC) used three times a day for mild AD. The study was conducted as a on one hemi‐body randomized, controlled, single‐blind, intra‐patient left‐to‐right comparative trial by patients with clinical diagnosis of mild AD measured with total SCORAD index over 4 months. MB12 was compared on one hemi‐body treated (GPC). The comparisons of score values were performed primarily by using non‐parametric procedures: Mann–Whitney‐U test (for independent samples) and Wilcoxon test (for dependent samples). All 22 patients were randomized (left or right side treated with MB12 or GPC). At week 12 a reduction from baseline in SCORAD index was assessed in both body sites with 77.6% SCORAD index reduction in the MB12 treated body sites versus 33.5% in the GPC treated body sites. These results suggest that MB12 could represent a new option in the treatment of mild AD.     

富含亚油酸-神经酰胺的保湿剂在特应性皮炎鼠模型中的作用研究

目的：明确外用富含亚油酸-神经酰胺（Linoleic acid-ceramide, LA-Cer）的保湿剂对特应性皮炎（AD）鼠模型皮肤炎症和屏障的影响。方法：将18只BALB/c小鼠分为疾病组、治疗组和对照组,每组6只。疾病组以卡泊三醇（MC903）涂抹小鼠耳朵2周,诱导特应性皮炎模型;治疗组在诱导特应性皮炎的同时外用富含LA-Cer的保湿剂;对照组以无水乙醇外涂小鼠耳朵。比较各组间临床表型、组织病理、皮肤水含量的改变,通过实时荧光定量PCR检测炎症相关因子（TSLP,IL-4,IL-10,IL-1β,IL-33,IFNγ）的表达。结果：卡泊三醇诱导出较典型的小鼠AD模型。治疗组的鼠耳厚度（0.375±0.015）cm较疾病组（0.510±0.035）cm改善,治疗组皮肤含水量（22.500±2.081）au较疾病组（6.750±1.258）au高。与疾病组比较,治疗组皮损中炎症因子TSLP和IL-1β的表达含量明显降低。结论：外用富含LA-Cer的保湿剂可以减轻卡泊三醇诱导的特应性皮炎小鼠模型皮肤炎症,修护皮肤屏障。     

Effect of pedunculagin investigated by non‐invasive evaluation on atopic‐like dermatitis in NC/Nga mice

Background/purpose: Atopic dermatitis (AD) is a chronic relapsing inflammatory skin disorder that is becoming increasingly prevalent. Experimental animal models have been an indispensable tool for studying its pathological mechanisms and for in vivo testing of novel therapeutic approaches. AD‐like lesions can be induced experimentally in NC/Nga mice. Pedunculagin, an ellagitannin purified from the Manchurian alder, Alnus hirsuta var. microphylla, Betulaceae, is a novel immunomodulator. To evaluate the effect of pedunculagin for AD‐like lesions in NC/Nga mice, using clinical and non‐invasive methods. Methods: AD‐like lesions were induced in NC/Nga mice using 2,4,6‐trinitrochlorobenzene (TNCB). A cream containing 0.1% or 0.5% pedunculagin was applied to the positive treatment group, and the base cream without pedunculagin was applied to the negative treatment group. The control group did not receive any kind of topical agents. We evaluated the therapeutic efficacy of pedunculagin for AD by statistical evaluation of the clinical severity score using non‐invasive biomedical engineering tools before treatment, and 1 day, 3 days, 1 week, 2 weeks and 4 weeks afterwards. Results: An AD‐like skin rash was successfully induced using TNCB in NC/Nga mice. The group receiving higher concentrations of pedunculagin showed faster and greater improvement. Conclusion: Our results suggest that remedies made from natural materials like pedunculagin are now showing promise for medical applications, and many new studies are expected to explore this potential.     

Cannabinoid receptors 1 and 2 oppositely regulate epidermal permeability barrier status and differentiation

Cannabinoid receptors (CBR) 1 and 2 have been implicated in keratinocyte differentiation/proliferation. How CB receptors affect epidermal permeability barrier and stratum corneum structure and function remains unclear. Permeability barrier abrogation was induced by sequential tape-stripping of the SC and assessed in both CB1R and CB2R knockout (-/-) mice in comparison with wild-type (+/+) littermates. Absence of CB1R delays permeability barrier recovery, while the latter was found to be accelerated in CB2R -/- mice. While increased lamellar body (LB) secretion is observed in CB2R -/- mice accounting for the enhanced recovery, CB1R -/- animals display strong alterations in lipid bilayer structures. Markers for epidermal differentiation (i.e. filaggrin, loricrin and involucrin) and terminal differentiation (i.e. TUNEL assay and caspase-14 activation) were respectively decreased and increased in CB1R and CB2R -/- mice. Surprisingly, CB1R agonist treatment of human cultured keratinocytes increases mRNA of p21 and cytokeratin 1 and 10 and decreases cyclin D1 but protein levels remained unchanged. Such paradox could partially be explained by the increase in non-phosphorylated-4E-BP1, an inhibitor of mRNA translation, following CB1R agonist treatment. Altogether, these observations put forward the importance and the complexity of cannabinoid signalling for the regulation of permeability barrier and epidermal differentiation.     

TLR2 and TLR4 expression in atopic dermatitis,contact dermatitis and psoriasis

The aim of the study was to investigate the expression of Toll‐like receptors (TLRs) 2 and 4 on keratinocytes in atopic dermatitis, contact dermatitis, and psoriasis by PCR and by immunohistochemistry including confocal microscopy. Confocal microscopy revealed a granular intra‐cellular expression pattern for TLR 2 and a homogenous intra‐cellular expression pattern for TLR 4 in normal and diseased skin. TLR 2 was constitutively expressed in the suprabasal layers in normal skin, but limited to the basal epidermis in diseased skin. TLR 4 expression was concentrated to the basal layers in normal skin, whereas it was pronounced in upper layers in diseased skin. The shift in the TLR expression may be related to the disturbed skin barrier and a need for enhanced immune surveillance because of invading microbes. Also, there must be a balance between sufficient immune response and overstimulation.     

Effector pathways during eczematous dermatitis: where inflammation meets cell death

Abstract:  During eczematous skin inflammation, the main constituents of the skin, keratinocytes (KC), play an important role in inducing and shaping the immunological response to environmental stimuli. This review focuses on the epidermal inflammation caused by keratinocyte-T cell interactions arising from a disturbed barrier function of the skin. In eczematous dermatitis, activated dermis- and epidermis-infiltrating T cells target KC for apoptosis. In turn, damaged KC respond by secreting inflammatory mediators, thus effecting further recruitment of immunocytes to inflamed skin. Further advances will come from identification of the immunoregulatory mechanisms involved in the pathogenesis of eczematous dermatitis. Potential therapeutic interventions are discussed.     

Deficiency of n‐6 polyunsaturated fatty acids is mainly responsible for atopic dermatitis‐like pruritic skin inflammation in special diet‐fed hairless mice

Hairless mice fed a special diet, HR‐AD, develop atopic dermatitis (AD)‐like skin inflammation with skin barrier defects and itch‐related scratching; however, the ingredient(s) causing the dermatitis remains unclear. In this study, we examined whether deficiency of certain polyunsaturated fatty acids (PUFAs) is involved in HR‐AD‐induced AD. High‐purity PUFAs were given to HR‐AD‐fed mice by dietary supplementation or gavage. Fatty acid levels in the serum and skin were determined by using gas chromatography–mass spectrometry. In serum from HR‐AD‐fed mice, linoleic acid (LA, 18:2n‐6) and α‐linolenic acid (ALA, 18:3n‐3), as well as their metabolites, were markedly decreased. When mice were fed HR‐AD supplemented with LA or ALA in an amount equal to that contained in a normal diet, the development of AD‐like symptoms was completely prevented by supplementation with LA but not with ALA. Relatively high dose of ALA slightly alleviated skin barrier defects, but did neither itch‐related scratching nor skin inflammation. On the other hand, gavage administration of LA metabolites, such as γ‐linolenic acid and arachidonic acid (AA), significantly ameliorated established dermatitis without increasing LA in the serum and skin. Moreover, AA‐induced amelioration of dermatitis was not affected by pharmacological blockade of 5‐lipoxygenase (5‐LOX) and cyclooxygenase (COX), suggesting no involvement of 5‐LOX‐ or COX‐mediated AA metabolites in the amelioration. In conclusion, our results indicate that deficiency of n‐6 PUFAs is mainly responsible for AD‐like symptoms by HR‐AD feeding. Thus, this model could be useful for studying the pathomechanisms associated with deficiency of n‐6 PUFAs in AD.     

Therapeutic potential of topically administered γ‐AlOOH on 2,4‐dinitrochlorobenzene‐induced atopic dermatitis‐like lesions in Balb/c mice

Boehmite (γ‐AlOOH) has a wide range of applications in a variety of industrial and biological fields. However, little is known about its potential roles in skin diseases. The current study investigated its effect on atopic dermatitis (AD). Following characterization, cytotoxicity, pro‐inflammatory response and oxidative stress associated with boehmite were assessed, using TNF‐α‐induced keratinocytes and mast cells. In addition, therapeutic effects of boehmite, topically administered to Balb/c mice induced by 2,4‐dinitrochlorobenzene (DNCB), were evaluated. Expression of cytokines (TLSP, IL‐25 and IL‐33) and the generation of ROS from keratinocytes induced by TNF‐α were significantly inhibited by boehmite without affecting cell viability. MAPKs (ERK, JNK and p38) required for cytokine expression were suppressed by boehmite treatment. Up‐regulation of cytokines (TSLP, IL‐4, IL‐5, IL‐13, RANTES) in human mast cells treated with phorbol 12‐myristate 13‐acetate and calcium ionophore was also suppressed by boehmite. Boehmite improved the AD severity score, epidermal hyperplasia and transepidermal water loss in DNCB‐induced AD‐like lesions. Moreover, Th2‐mediated cytokine expression, mast cell hyperplasia and destruction of the skin barrier were improved by boehmite treatment. Overall, we demonstrated that boehmite may potentially protect against AD.     

The benefit of a ceramide‐linoleic acid‐containing moisturizer as an adjunctive therapy for a set of xerotic dermatoses

Atopic dermatitis (AD), chronic eczema, and pruritus hiemalis are a set of prevalent chronic xerotic skin disorders that share clinical features such as dryness, scales, and pruritus. A ceramide deficiency and defective epidermal functions are common in these diseases. This study was designed to assess the effect of ceramide‐linoleic acid (LA‐Cer)–containing moisturizer as an adjunctive therapy in the treatment of AD, chronic eczema, and pruritus hiemalis. In a 2‐month study, patients with one of these three diseases were divided into two groups. The control group was treated with mometasone furoate (0.1%) cream (MF), whereas the treatment group received 0.1% MF in combination with an LA‐Cer‐containing moisturizer. Capacitance and transepidermal water loss were measured in normal and lesional skin, along with Eczema Assessment Severity Index and pruritus scores at Weeks 0, 2, 4, and 8. The results showed that tropical applications of an LA‐Cer‐containing moisturizer in combination with a topical glucocorticoid accelerated the reestablishment of epidermal permeability barrier and the amelioration of pruritus in patients with AD and pruritus hiemalis. However, it did not provide the same effect for chronic eczema. Thus, the efficacy of this combination therapy for this set of xerotic disorders requires further evaluation.     

Transepidermal water loss in adhesive tape induced dermatitis

As an index of skin barrier function, transepidermal water loss (TEW) was investigated in subjects reactive to adhesive tapes. Tape reactive subjects showed no difference in TEW in untreated skin when compared to non-reactive subjects. Plastic tape and transparent tape produced varying degrees of dermatitis in reactive subjects; the TEW was increased up to 40-fold of the baseline values correlating with the degree of dermatitis. Paper tape and plastic film without adhesive did not produce dermatitis and increased water loss. Regeneration of skin damage was accompanied by a decrease of TEW values. The general problem of tape reactors and tape irritation is discussed.     

Amelioration of atopic‐like skin conditions in NC/Tnd mice by topical application with distilled Alpinia intermedia Gagnep extracts

Alpinia intermedia, a perennial plant that belongs to the Zingiberaceae family, has been used in folk medicine for a long time in the southern region of Japan. Because skin care is an effective approach that enables patients to manage their atopic dermatitis (AD), various herbal ingredients with few adverse effects have been evaluated for use in AD patients in recent years. In this study, we examined whether distilled extracts obtained from A. intermedia were beneficial for AD‐like skin conditions in NC/Tnd mice. Topical application with the A. intermedia extracts significantly reduced the severity of AD, transepidermal water loss and scratching behavior in the mice. Supplementation of the extracts to cell cultures suppressed the expression of Tslp mRNA in PAM212 keratinocytes, degranulation in bone marrow‐derived cultured mast cells (BMCMC), and neurite outgrowth in PC12 cells and dorsal root ganglia. In addition, the component analysis revealed that β‐pinene was a major constituent of the A. intermedia extracts. The inhibitory effects of β‐pinene both in vivo and in vitro were also demonstrated. These results indicate that topical application with the A. intermedia extract to the skin of NC/Tnd mice improved the condition of the skin by suppressing multiple inflammatory responses. The extracts may become novel skin‐care remedies for AD patients.     

Cannabinoid system in the skin – a possible target for future therapies in dermatology

Abstract:  Cannabinoids and their derivatives are group of more than 60 biologically active chemical agents, which have been used in natural medicine for centuries. The major agent of exogenous cannabinoids is Δ⁹-tetrahydrocannabinol (Δ⁹-THC), natural psychoactive ingredient of marijuana. However, psychoactive properties of these substances limited their use as approved medicines. Recent discoveries of endogenous cannabinoids (e.g. arachidonoylethanolamide, 2-arachidonoylglycerol or palmithyloethanolamide) and their receptors initiated discussion on the role of cannabinoid system in physiological conditions as well as in various diseases. Based on the current knowledge, it could be stated that cannabinoids are important mediators in the skin, however their role have not been well elucidated yet. In our review, we summarized the current knowledge about the significant role of the cannabinoid system in the cutaneous physiology and pathology, pointing out possible future therapeutic targets.