Differential effects of topical corticosteroid and calcineurin inhibitor on the epidermal tight junction

Short-term effect of a moderate-potency topical corticosteroid on epidermal biophysical parameters in patients with mild-to-moderate atopic dermatitis: A randomised controlled study

Introduction

Skin barrier dysfunction is an important component of atopic dermatitis (AD) pathophysiology. Topical corticosteroids (TCSs) are the mainstay therapy, but steroid phobia is emerging due to potential side effects. We aimed to determine the short-term effect of clobetasone butyrate on patients with AD.

Methods

This investigator-blinded, randomised, moisturiser-controlled study evaluated patients with stable mild-to-moderate AD. Clobetasone butyrate ointment plus aqueous cream (Aq) or Aq alone was applied on randomised sites twice daily for 6 weeks. The itch score, modified Eczema Area and Severity Index (M-EASI) and epidermal biophysical parameters were assessed at baseline and 1 h, 3 h, 2 weeks and 6 weeks after application.

Results

Sixteen patients, among whom 14 (87.5%) were women and two (12.5%) were men, participated in the study. There were no significant differences in pH, transepidermal water loss (TEWL) and hydration between TCS + Aq and Aq from 1 h to 6 weeks. A non-significant trend of pH increment was observed with TCS + Aq from baseline to 6 weeks. TEWL and hydration improved at 6 weeks for both treatment arms. The difference in TEWL from baseline was significant with Aq (P=0.01). The M-EASI at 6 weeks was comparable between the two arms. TCS + Aq improved itch and erythema better than Aq (P=0.02). No cutaneous adverse effects were observed at both sites.

Conclusion

Short-term application of clobetasone butyrate with Aq is safe with no significant changes in epidermal biophysical parameters while controlling the symptoms and signs of eczema faster than Aq alone.

Targeting Skin Barrier Function in Atopic Dermatitis

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease in the general population. Skin barrier dysfunction is the central abnormality leading to AD. The cause of skin barrier dysfunction is complex and rooted in genetic mutations, interactions between the immune pathway activation and epithelial cells, altered host defense mechanisms, as well as environmental influences that cause epithelial cell activation and release of alarmins (such as thymic stromal lymphopoietin) that can activate the type 2 immune pathway, including generation of interleukins 4 and 13, which induces defects in the skin barrier and increased allergic inflammation. These inflammatory pathways are further influenced by environmental factors including the microbiome (especially Staphylococcus aureus), air pollution, stress, and other factors. As such, AD is a syndrome involving multiple phenotypes, all of which have in common skin barrier dysfunction as a key contributing factor. Understanding mechanisms leading to skin barrier dysfunction in AD is pointing to the development of new topical and systemic treatments in AD that helps keep skin borders secure and effectively treat the disease.

The Effects of Mucopolysaccharide Polysulfate on Steroid-Induced Tight Junction Barrier Dysfunction in Human Epidermal Keratinocytes and a 3D Skin Model

INTRODUCTION

The long-term use of topical corticosteroids (TCS) is associated with side effects such as skin atrophy and barrier deterioration. Moisturizers, such as mucopolysaccharide polysulfate (MPS), have been reported to prevent relapses in atopic dermatitis (AD) when used in combination with TCS. However, the mechanisms underlying the positive effects of MPS in combination with TCS in AD are poorly understood. In the present study, we investigated the effects of MPS in combination with clobetasol 17-propionate (CP) on tight junction (TJ) barrier function in human epidermal keratinocytes (HEKa) and 3D skin models.

METHODS

The expression of claudin-1, which is crucial for TJ barrier function in keratinocytes, and transepithelial electrical resistance (TEER) was measured in CP-treated human keratinocytes incubated with and without MPS. A TJ permeability assay, using Sulfo-NHS-Biotin as a tracer, was also conducted in a 3D skin model.

RESULTS

CP reduced claudin-1 expression and TEER in human keratinocytes, whereas MPS inhibited these CP-induced effects. Moreover, MPS inhibited the increase in CP-induced TJ permeability in a 3D skin model.

CONCLUSION

The present study demonstrated that MPS improved TJ barrier impairment induced by CP. The improvement of TJ barrier function may partially be responsible for the delayed relapse of AD induced by the combination of MPS and TCS.

The Role of Tight Junctions in Atopic Dermatitis: A Systematic Review

BACKGROUND

Tight junctions are transmembrane proteins that regulate the permeability of water, solutes including ions, and water-soluble molecules. The objective of this systematic review is to focus on the current knowledge regarding the role of tight junctions in atopic dermatitis and the possible impact on their therapeutic potential.

METHODS

A literature search was performed in PubMed, Google Scholar, and Cochrane library between 2009 and 2022. After evaluation of the literature and taking into consideration their content, 55 articles were finally included.

RESULTS

TJs' role in atopic dermatitis extends from a microscopic scale to having macroscopic effects, such as increased susceptibility to pathogens and infections and worsening of atopic dermatitis features. Impaired TJ barrier function and skin permeability in AD lesions is correlated with cldn-1 levels. Th2 inflammation inhibits the expression of cldn-1 and cldn-23. Scratching has also been reported to decrease cldn-1 expression. Dysfunctional TJs' interaction with Langerhans cells could increase allergen penetration. Susceptibility to cutaneous infections in AD patients could also be affected by TJ cohesion.

CONCLUSIONS

Dysfunction of TJs and their components, especially claudins, have a significant role in the pathogenesis and vicious circle of inflammation in AD. Discovering more basic science data regarding TJ functionality may be the key for the use of specific/targeted therapies in order to improve epidermal barrier function in AD.

Lithospermum erythrorhizon Alleviates Atopic Dermatitis-like Skin Lesions by Restoring Immune Balance and Skin Barrier Function in 2.4-Dinitrochlorobenzene-Induced NC/Nga Mice

The incidence of atopic dermatitis (AD), a disease characterized by an abnormal immune balance and skin barrier function, has increased rapidly in developed countries. This study investigated the anti-atopic effect of Lithospermum erythrorhizon (LE) using NC/Nga mice induced by 2,4-dinitrochlorobenzene. LE reduced AD clinical symptoms, including inflammatory cell infiltration, epidermal thickness, ear thickness, and scratching behavior, in the mice. Additionally, LE reduced serum IgE and histamine levels, and restored the T helper (Th) 1/Th2 immune balance through regulation of the IgG1/IgG2a ratio. LE also reduced the levels of AD-related cytokines and chemokines, including interleukin (IL)-1β, IL-4, IL-6, tumor necrosis factor-α (TNF-α), thymic stromal lymphopoietin, thymus and activation-regulated chemokine, macrophage-derived chemokine, regulated on activation, normal T cell expressed and secreted, and monocyte chemoattractant protein-1 in the serum. Moreover, LE modulated AD-related cytokines and chemokines expressed and secreted by Th1, Th2, Th17, and Th22 cells in the dorsal skin and splenocytes. Furthermore, LE restored skin barrier function by increasing pro-filaggrin gene expression and levels of skin barrier-related proteins filaggrin, involucrin, loricrin, occludin, and zonula occludens-1. These results suggest that LE is a potential therapeutic agent that can alleviate AD by modulating Th1/Th2 immune balance and restoring skin barrier function.

Topical therapy of atopic dermatitis with a focus on pimecrolimus

Atopic dermatitis (AD) is a chronic and relapsing, inflammatory skin disease characterized by impaired skin barrier function and immune system dysregulation that results in dryness, skin microbiome dysbiosis and intense pruritus. It is highly heterogeneous, and its management is demanding. Patients with AD are at greater risk of comorbidities such as attention-deficit hyperactivity disorder as well as other atopic diseases. Early-onset AD cases typically improve or resolve in late childhood; however, it is proposed that the prevalence of persistent or adult-onset AD is higher than previously thought. Basic therapy consists of emollient application and trigger avoidance, and when insufficient, topical corticosteroids (TCS) are the first-line treatment. However, corticophobia/steroid aversion and TCS side-effects, particularly on sensitive skin areas, lead to low compliance and insufficient disease control. Several long- and short-term randomized controlled and daily practice studies have demonstrated that topical calcineurin inhibitors, such as pimecrolimus, have similar anti-inflammatory effects to low-to-medium strength TCS, reduce pruritus and improve the quality of life of patients. In addition, pimecrolimus does not cause skin atrophy, is steroid-sparing and has a good safety profile, with no evidence for an increased risk of malignancies or skin infections. In general, pimecrolimus cream is well-accepted and well-tolerated, encouraging patient adherence and leading to its use by many physicians as a preferred therapy for children and sensitive skin areas.

Effects of Delgocitinib Ointment 0.5% on the Normal Mouse Skin and Epidermal Tight Junction Proteins in Comparison With Topical Corticosteroids

Delgocitinib ointment 0.5% is the world's first topical Janus kinase inhibitor product and was approved for treatment of atopic dermatitis (AD) in Japan. Although topical corticosteroids (TCSs) have been the mainstay of pharmacotherapy in AD over the past decades, long-term use of TCSs causes skin atrophy and alteration of the epidermal tight junction (TJ) leading to epidermal barrier dysfunction. In this study, delgocitinib ointment 0.5% or representative TCSs of different potencies were applied dermally once daily to the ear pinna of normal ICR mice for 14 days, and ear pinna thickness, histopathology, and immunohistochemistry for epidermal TJ proteins claudin-1 and -4 were evaluated. All the TCSs caused decreases in ear pinna thickness with epidermal thinning, sebaceous gland atrophy, and atrophy/decreased number of the subcutaneous adipocytes and decreased immunohistochemical staining intensity for epidermal claudins. In contrast, delgocitinib ointment 0.5% did not cause any of those changes. In conclusion, once daily topical delgocitinib ointment 0.5% for 14 days did not cause skin atrophy or decreased immunohistochemical staining of epidermal claudins, which are common safety concerns associated with TCSs. These characteristics suggest that delgocitinib ointment 0.5% has an improved safety profile over currently available TCS therapies particular for the long-term AD treatment.

Atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disease, clinically characterized by recurrent eczematous lesions and intense itching, leading to excoriations and susceptibility to cutaneous infections. Although it is considered a pediatric disorder, mainly starting in infancy, it is also very common in adults. Etiology of AD is complex and multifactorial: interaction between genetic susceptibility and environment, but also cutaneous barrier impairment, change in microbiome composition and innate and adaptive immune dysregulation are the main factors involved in the pathogenesis of the disease. Originally, the disorder was considered mediated by an imbalance towards a T-helper 2 response and excessive IgE production to allergens, but now it is recognized as a lifelong disposition with variable clinical expressivity, where dysfunctions of the epidermal barrier, immune system and microbiome play a central role. AD leads to a substantial psycho-social burden on patients and their relatives and increases the risk of other allergic and non allergic disorders. The real economic impact of AD is difficult to measure due to the broad spectrum of disease severity and the multiple direct and indirect costs, but the overall medical expenses seem to be very high and similar to those of other diseases such as diabetes. Currently, a multiple therapeutic approach is aimed only at improving the skin state, reducing itching and keeping a stable condition. New safety and curative treatments may be developed only after enhancing our understanding on the pathogenesis of AD and the heterogeneity of its clinical manifestations. (www.actabiomedica.it)

Prurigo nodularis as a sweat gland/duct-related disorder: resolution associated with restoration of sweating disturbance

Little attention has been given to the involvement of sweat glands/ducts in the pathogenesis of prurigo nodularis (PN). According to recent studies, PN is likely to develop under conditions characterized by dry skin, such as atopic dermatitis (AD), suggesting a strong impact of skin dryness on PN development. No therapeutic modalities produced complete resolution of PN without exacerbations. We previously reported that increases in skin dryness by sweating disturbance could initiate the development of AD. We investigated whether sweating responses were impaired in refractory PN lesions; and, if so, we asked whether the PN lesions could resolve by restoring sweating disturbance. Using the impression mold technique, which allows an accurate quantification of individual sweat gland/duct activity, we examined basal sweating under quiescent conditions and inducible sweating responses to thermal stimulus in PN lesions and normal-appearing skin in the same patients before and after treatment with a moisturizer or topical corticosteroids. Sweating disturbance, either basal or inducible, was most profoundly detected in the "hub" structure corresponding to the center of PN papule before the treatment. This sweating disturbance was immunohistochemically associated with the leakage of sweat into the dermis. This disturbance was restored by treatment with a moisturizer. Our limitations include a relatively small patient cohort and lack of blinding. Sweating disturbance could be one of the aggravating factors of PN development. Refractory PN with low skin hydration may resolve by restoring sweating disturbance.

Current therapeutic paradigm in pediatric atopic dermatitis: Practical guidance from a national expert panel

INTRODUCTION AND OBJECTIVES

Atopic dermatitis (AD) is the most common cutaneous inflammatory disease in both adults and children. Although emerging therapeutic approaches are being investigated for the management of pediatric AD, it still needs to be managed with conventional treatments. This consensus document is aimed at providing an update on general management and therapies of pediatric AD, defining practical recommendations for using both topical and systemic agents.

MATERIAL AND METHODS

A panel of experts consisting of dermatologists and pediatricians were convened in order to define statements, through a Delphi process, standardizing the management of AD in pediatric subjects in a real-world setting.

RESULTS

A set of practical recommendations obtaining an at least 75% agreement was presented.

CONCLUSIONS

This set of practical recommendations represents a simple and fast snapshot on the pediatric use of common anti-AD therapeutics.

Impact of topical anti-inflammatory therapy on morpho-functional characteristics of epidermal barrier. Optimization of atopic dermatitis treatment schedules

In this literature review data regarding impact of topical therapy with topical corticosteroids (TCS) and tacrolimus ointment on morpho-functional characteristics of epidermal barrier is analyzed. Whereas TCS has profound negative impact on nearly all epidermal barrier parameters, including epidermal structure and thickness, integrity and cohesion of stratum corneum, protease activity, hydration, pH, differentiation, lipid lamellae structure etc., tacrolimus ointment (Protopic®) exerts positive effect on the majority of the aforementioned parameters, thus allowing to compensate deleterious effect of TCS. These data allow defining recommendations upon optimization of topical therapy of atopic dermatitis with stepwise switching from TCS to Protopic® ointment.

Potential and future scope of nanoemulgel formulation for topical delivery of lipophilic drugs

The Nanoemulgel drug delivery system is a formulation related intervention to improve the systemic delivery and therapeutic profile of lipophilic drugs. Nanoemulgel is an amalgamated formulation of two different systems in which nanoemulsion containing drug is incorporated into a gel base. The fusion of the two systems makes this formulation advantageous in several ways. Lipophilic drugs can be easily incorporated and the skin permeability of the incorporated drugs can be enhanced in several folds due to the finely distributed droplets of nanoemulsion phase. As a result, the pharmacokinetic and pharmacodynamic profiles of the lipophilic drugs are improved significantly. An increasing trend in topical nanoemulgel use in recent years has been noticed because of the better acceptability of the preparation to the patients due to their noninvasive delivery, avoidance of gastrointestinal side effects, easier applicability and good therapeutic and safety profile. Despite of having few limitations, nanoemulgel formulation can be considered as a potential and promising candidates for topical delivery of lipophilic drugs in the future. The aim of this review is to evaluate and report the current potential and future scope of nanoemulgel formulation for becoming an effective delivery system for poorly water soluble drugs. In this review, we have summarized and discussed the outcome of different studies on permeability, pharmacokinetic, pharmacodynamic and safety profile of the drugs delivered topically through nanoemulgel. Rationality of use along with the major challenges to overcome for nanoemulgel formulation has been discussed.

Differences in therapeutic effects of topically applied corticosteroid and tacrolimus on atopic dermatitis-like symptoms in NC/Nga mice

BACKGROUND

Topical corticosteroid and calcineurin inhibitor have similar therapeutic benefits in atopic dermatitis (AD), but the differences in therapeutic mechanisms of action of these agents against AD symptoms are not fully understood.

OBJECTIVE

This study was performed to examine the different effects of topical betamethasone valerate (BMV), clobetasol propionate (CBP), and tacrolimus (TAC) on itch-related behavior and dermatitis in NC/Nga mice with AD-like symptoms.

METHODS

AD-like dermatitis was induced in the dorsal skin of NC/Nga mice by repeated topical application of Dermatophagoides farinae body (Dfb) ointment twice weekly for three weeks. Mice with dermatitis scores over 5 were divided into five groups with equal dermatitis scores and treated with BMV, CBP, TAC, or Vaseline (Vas) once daily for two consecutive days, or were not treated (NT). Scratching behavior was analyzed using a SCLABA^®-Real system. Transepidermal water loss (TEWL) before and after treatment was measured using a Tewameter^® TM210. Skin collected from each group was analyzed histologically.

RESULTS

After the second treatment, dermatitis showed significantly greater improvement in the CBP and TAC-treated groups than in the Vas-treated and NT groups. The numbers of scratching bouts were significantly lower in CBP and TAC-treated mice than in Vas-treated mice. TEWL was significantly lower in TAC-, but not in CBP-, treated mice than in Vas-treated mice. Immunohistochemical examination showed that BMV, CBP and TAC did not reduce the increased densities of epidermal protein gene product 9.5- and substance P-immunoreactive fibers. The numbers of dermal CD4-immunoreactive T cells were significantly lower in BMV and CBP-treated mice than in Vas-treated and NT mice. The numbers of dermal eosinophils were significantly lower in BMV, CBP and TAC-treated mice than in Vas-treated and NT mice, with CBP showing the strongest effect. CBP significantly reduced epidermal thickness compared with Vas and NT. There were no significant differences in the numbers of interleukin-31-immunoreactive cells and mast cells, or in expression of epidermal thymic stromal lymphopoietin among all five groups.

CONCLUSION

The therapeutic potency of TAC against AD-like symptoms, including pruritus, is equal to that of the corticosteroid CBP. Epidermal innervation of sensory nerves itself might not be related to the therapeutic effects of topical tacrolimus and corticosteroids in its early phase.

UVB induces epidermal 11β-hydroxysteroid dehydrogenase type 1 activity in vivo

Detrimental consequences of ultraviolet radiation (UVR) in skin include photoageing, immunosuppression and photocarcinogenesis, processes also significantly regulated by local glucocorticoid (GC) availability. In man, the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) generates the active GC cortisol from cortisone (or corticosterone from 11-dehydrocorticosterone in rodents). 11β-HSD1 oxo-reductase activity requires the cofactor NADPH, generated by hexose-6-phosphate dehydrogenase. We previously demonstrated increased 11β-HSD1 levels in skin obtained from photoexposed versus photoprotected anatomical regions. However, the direct effect of UVR on 11β-HSD1 expression remains to be elucidated. To investigate the cutaneous regulation of 11β-HSD1 following UVR in vivo, the dorsal skin of female SKH1 mice was irradiated with 50, 100, 200 and 400 mJ/cm(2) UVB. Measurement of transepidermal water loss, 11β-HSD1 activity, mRNA/protein expression and histological studies was taken at 1, 3 and 7 days postexposure. 11β-HSD1 and hexose-6-phosphate dehydrogenase mRNA expression peaked 1 day postexposure to 400 mJ/cm(2) UVB before subsequently declining (days 3 and 7). Corresponding increases in 11β-HSD1 protein and enzyme activity were observed 3 days postexposure coinciding with reduced GC receptor mRNA expression. Immunofluorescence studies revealed 11β-HSD1 localization to hyperproliferative epidermal keratinocytes in UVB-exposed skin. 11β-HSD1 expression and activity were also induced by 200 and 100 (but not 50) mJ/cm(2) UVB and correlated with increased transepidermal water loss (indicative of barrier disruption). UVB-induced 11β-HSD1 activation represents a novel mechanism that may contribute to the regulation of cutaneous responses to UVR exposure.

Wheat germ agglutinin as a counterstain for immunofluorescence studies of equine hoof lamellae

Equine laminitis is a common, painful, debilitating condition of the hoof that is a leading cause of disability in horses, often necessitating euthanasia. The equine hoof represents an extreme evolutionary adaptation of an epidermal structure homologous to the human or murine nail units. Immunohistochemistry is frequently utilized in the study of the pathophysiology of laminitis. The complex, multilayered, extensively interdigitated epidermal-dermal lamellar interface renders precise interpretation of immunofluorescence localization difficult, especially when effective technique and reagents render non-reactive tissues completely dark. Fluorescent-conjugated wheat germ agglutinin (WGA) selectively labels dermal extracellular matrix fibres and epidermal cell membranes in tissue sections of horse hoof lamellae, is compatible with indirect immunofluorescence and augments interpretation of indirect immunofluorescence antigen localization. The current report details the use of WGA as a rapid, simple, economical counterstain for immunofluorescence studies of the equine hoof and may have application to other complex epidermal tissue structures.

Nanomiemgel--a novel drug delivery system for topical application--in vitro and in vivo evaluation

Aim

The objective of this study was to formulate and evaluate a unique matrix mixture (nanomiemgel) of nanomicelle and nanoemulsion containing aceclofenac and capsaicin using in vitro and in vivo analyses and to compare it to a marketed formulation (Aceproxyvon).

Methods

Nanomicelles were prepared using Vitamin E TPGS by solvent evaporation method and nanoemulsion was prepared by high-pressure homogenization method. In vitro drug release and human skin permeation studies were performed and analyzed using HPLC. The efficiency of nanomiemgel as a delivery system was investigated using an imiquimod-induced psoriatic like plaque model developed in C57BL/6 mice.

Results

Atomic Force Microscopy images of the samples exhibited a globular morphology with an average diameter of 200, 250 and 220 nm for NMI, NEM and NMG, respectively. Nanomiemgel demonstrated a controlled release drug pattern and induced 2.02 and 1.97-fold more permeation of aceclofenac and capsaicin, respectively than Aceproxyvon through dermatomed human skin. Nanomiemgel also showed 2.94 and 2.09-fold greater Cmax of aceclofenac and capsaicin, respectively than Aceproxyvon in skin microdialysis study in rats. The PASI score, ear thickness and spleen weight of the imiquimod-induced psoriatic-like plaque model were significantly (p<0.05) reduced in NMG treated mice compared to free drug, NEM, NMI & Aceproxyvon.

Conclusion

Using a new combination of two different drug delivery systems (NEM+NMI), the absorption of the combined system (NMG) was found to be better than either of the individual drug delivery systems due to the utilization of the maximum possible paths of absorption available for that particular drug.

Intestinal barrier function and the brain-gut axis

The luminal-mucosal interface of the intestinal tract is the first relevant location where microorganism-derived antigens and all other potentially immunogenic particles face the scrutiny of the powerful mammalian immune system. Upon regular functioning conditions, the intestinal barrier is able to effectively prevent most environmental and external antigens to interact openly with the numerous and versatile elements that compose the mucosal-associated immune system. This evolutionary super system is capable of processing an astonishing amount of antigens and non-immunogenic particles, approximately 100 tons in one individual lifetime, only considering food-derived components. Most important, to develop oral tolerance and proper active immune responses needed to prevent disease and inflammation, this giant immunogenic load has to be managed in a way that physiological inflammatory balance is constantly preserved. Adequate functioning of the intestinal barrier involves local and distant regulatory networks integrating the so-called brain-gut axis. Along this complex axis both brain and gut structures participate in the processing and execution of response signals to external and internal changes coming from the digestive tract, using multidirectional pathways to communicate. Dysfunction of brain-gut axis facilitates malfunctioning of the intestinal barrier, and vice versa, increasing the risk of uncontrolled immunological reactions that may trigger mucosal and brain low-grade inflammation, a putative first step to the initiation of more permanent gut disorders. In this chapter, we describe the structure, function and interactions of intestinal barrier, microbiota and brain-gut axis in both healthy and pathological conditions.