Allergic contact dermatitis: From pathophysiology to development of new preventive strategies

Prevalence and trends of contact sensitization in patients with psoriasis in Lithuania

Background

Psoriasis and allergic contact dermatitis are 2 very common dermatoses. The relationship between them has not yet been fully understood. Contact dermatitis can be an additional cause of epidermal disruption in psoriasis patients, resulting in poor management of the disease.

Objective

To analyze the tendencies of contact sensitization in a cohort of psoriasis patients with suspected allergic contact dermatitis.

Methods

Psoriasis patients (n = 85) with suspected contact dermatitis underwent patch testing with European Baseline allergen series S-1000 in Vilnius University Hospital Santaros Klinikos Centre of Dermatovenereology from August 2020 to August 2021. Their results are presented in this study.

Results

The patch test was positive in 43.5% (n = 37) of patients. Contact sensitization was more prevalent in patients with mild psoriasis, as characterized by Psoriasis Area Surface Index scores ≤10, compared to those with moderate-to-severe psoriasis (P < .05). Generalized psoriasis and nail involvement were more common among nonsensitized patients (P < .05). Most common contact allergens among sensitized patients were nickel (II) sulfate, formaldehyde, and potassium dichromate.

Conclusion

An inverse trend was observed between psoriasis severity and contact sensitization. Extended psoriatic involvement was uncommon in sensitized patients.

Rodent models of dermatological disorders

To assess the possible beneficial effects of drugs and drug candidates, different dermatological disease models are available in rodents. These models are able to mimic one or more characteristic features of the disorders, but not completely recapitulate the pathogenesis of the human skin diseases. Therefore, to improve the technology many new models have been developed both by genetic engineering and by chemical or physical induction. Currently the in vivo rodent models provide the physiologically most relevant approach to produce the pathology related to the majority of dermatological diseases. In this short review some widely used animal techniques (psoriasis, allergic contact dermatitis, atopic dermatitis, wound healing, melanoma and non-melanoma type skin cancers and UV erythema) are shown which are currently applied in pharmacological, pharmacokinetic, pharmaceutical and dermatological research. First the main points of the human pathomechanism are shown and afterwards the rodent models are briefly discussed. Finally critical evaluation is provided by the authors. However, according to the 3R rule the number of experimental animals is strongly suggested to be reduced, therefore the advanced in vitro and ex vivo techniques become more and more important contrary to in vivo preclinical methods also in dermatological research. As it is described in the outlook section, although the 2D/3D in vitro and skin on-a-chip techniques are promising and have many advantages they are not able to completely substitute the animal models in their vascular, immunological, secretory and neural complexity.

Inhibition of macrophage MAPK/NF-κB pathway and Th2 axis by mangiferin ameliorates MC903-induced atopic dermatitis

Available online Atopic dermatitis (AD) is a chronic, persistent inflammatory skin disease characterized by eczema-like lesions and itching. Although topical steroids have been reported for treating AD, they are associated with adverse effects. Thus, safer medications are needed for those who cannot tolerate these agents for long periods. Mangiferin (MAN) is a flavonoid widely found in many herbs, with significant anti-inflammatory and immunomodulatory activities. However, the potential modulatory effects and mechanisms of MAN in treating Th2 inflammation in AD are unknown. In the present study, we reported that MAN could reduce inflammatory cell infiltration and scratching at the lesion site by decreasing MC903-induced levels of Th2-type cytokines, Histamine, thymic stromal lymphopoietin, Leukotriene B4, and immunoglobulin E. The mechanism may be related to reductions in MAPK and NF-κB-associated protein phosphorylation by macrophages. The results suggested that MAN may be a promising therapeutic agent for AD.

Contact sensitization and self-reported eczema in Swedish painters with occupational exposure to isothiazolinones

BACKGROUND

Due to an increasing occupational usage of isothiazolinone (IT)-containing preservatives, and their potential to cause skin sensitization and allergic contact dermatitis, that is, chronic disease, there is a need for more knowledge on how highly exposed workers are affected.

OBJECTIVES

The overall objective was to explore dermatological symptoms of potentially long-lasting or chronic character in Swedish painters.

METHODS

Building painters from western and southern Sweden were initially invited to perform a questionnaire on occurrence of skin symptoms. Participants with affirmative responses, and the right inclusion criteria, were further invited to patch testing with four different ITs: benzisothiazolinone (BIT), methylisothiazolinone, methylchloroisothiazolinone and octylisothiazolinone.

RESULTS

There was a tendency towards higher occurrence of positive patch test reactions among the painters compared with occupationally unexposed registry patients; however, not statistically significant differences. BIT was the substance most frequently causing positive test results in both groups. The occurrence of adult-onset eczema was higher in painters than in the control group of electricians, and just shy of statistical significance concerning any of several skin locations (face/legs/arms/hands).

CONCLUSION

Building painters present with positive patch test reactions to common paint preservatives (ITs), and they report adult-onset eczema more often than do less occupationally exposed groups.

Patch testing while immunosuppressed: potential risks and benefits

INTRODUCTION

Allergic contact dermatitis (ACD) is a common cutaneous inflammatory skin disorder that is diagnosed via epicutaneous patch testing (PT). ACD may also coexist with other systemic inflammatory conditions such as atopic dermatitis and psoriasis. Many of the treatments used to manage severe ACD, along with other systemic conditions, interact with and suppress the immune system, thereby potentially interfering with the mechanism of PT. There is uncertainty in the literature regarding the effects of immunosuppression on the results of PT.

METHODS

A comprehensive literature review was conducted using PubMed and Google Scholar to identify articles relevant to the topic of this review. Only articles available in English were included.

AREAS COVERED

This review discusses the impact of immunomodulating therapies on the results of PT. We summarize the available evidence and provide updated recommendations for several immunomodulating drugs commonly used in patients undergoing PT.

EXPERT OPINION

In general, the results of PT are most reliable when performed without immunosuppression. If this is not feasible, it is best to have patients on as low a dose of immunosuppression as possible, but it may not be necessary to stop or change an immunomodulating drug prior to PT.

CD1a and skin T cells: a pathway for therapeutic intervention

The CD1 and MR1 protein families present lipid antigens and small molecules to T cells, complementing well-studied major histocompatibility complex-peptide mechanisms. The CD1a subtype is highly and continuously expressed within the skin, most notably on Langerhans cells, and has been demonstrated to present self and foreign lipids to T cells, highlighting its cutaneous sentinel role. Alteration of CD1a-dependent T-cell responses has recently been discovered to contribute to the pathogenesis of several inflammatory skin diseases. In this review, we overview the structure and role of CD1a and outline the current evidence implicating CD1a in the development of psoriasis, atopic dermatitis and allergic contact dermatitis.

The Involvement of Cysteine-X-Cysteine Motif Chemokine Receptors in Skin Homeostasis and the Pathogenesis of Allergic Contact Dermatitis and Psoriasis

Members of the C-X-C motif chemokine receptor (CXCR) superfamily play central roles in initiating the innate immune response in mammalian cells by orchestrating selective cell migration and immune cell activation. With its multilayered structure, the skin, which is the largest organ in the body, performs a crucial defense function, protecting the human body from harmful environmental threats and pathogens. CXCRs contribute to primary immunological defense; these receptors are differentially expressed by different types of skin cells and act as key players in initiating downstream innate immune responses. While the initiation of inflammatory responses by CXCRs is essential for pathogen elimination and tissue healing, overactivation of these receptors can enhance T-cell-mediated autoimmune responses, resulting in excessive inflammation and the development of several skin disorders, including psoriasis, atopic dermatitis, allergic contact dermatitis, vitiligo, autoimmune diseases, and skin cancers. In summary, CXCRs serve as critical links that connect innate immunity and adaptive immunity. In this article, we present the current knowledge about the functions of CXCRs in the homeostasis function of the skin and their contributions to the pathogenesis of allergic contact dermatitis and psoriasis. Furthermore, we will examine the research progress and efficacy of therapeutic approaches that target CXCRs.

Systemic allergic contact dermatitis to palladium, platinum, and titanium: mechanisms, clinical manifestations, prevalence, and therapeutic approaches

Contact dermatitis (CD) is an inflammatory skin disease of eczema that is elicited by chemicals or metal ions that have toxic effects without eliciting a T-cell response (contact elicitation) or by small reactive chemicals that modify proteins and induce innate and adaptive immune responses (contact allergens). The clinical condition is characterized by localized skin rash, pruritus, redness, swelling, and lesions, which are mainly detected by patch tests and lymphocyte stimulation. Heavy metals such as palladium (Pd), platinum (Pt), and titanium (Ti) are ubiquitous in our environment. These heavy metals have shown CD effects as allergic agents. Immunological responses result from the interaction of cytokines and T cells. Occupational metal CD accounts for most cases of work-related cutaneous disorders. In this systematic review, the allergic effects of heavy metals, including Pd, Pt, and Ti, and the mechanisms, clinical manifestations, prevalence, and therapeutic approaches are discussed in detail. Furthermore, the therapeutic approaches introduced to treat CD, including corticosteroids, topical calcineurin inhibitors, systemic immunosuppressive agents, phototherapy, and antihistamines, can be effective in the treatment of these diseases in the future. Ultimately, the insights identified could lead to improved therapeutic and diagnostic pathways.

Dimethylglycine, a methionine metabolite, participates in the suppressive effect of methionine on 1-fluoro-2,4-dinitrobenzene-induced dermatitis

Allergic contact dermatitis (ACD) is a common skin disorder caused by contact with allergens. The optimal treatment for ACD is to avoid contact with allergens. However, in some cases, avoiding exposure is not possible when the allergens are unknown. Therefore, establishing treatment methods other than allergen avoidance is important. We previously reported that the continuous administration of methionine, an essential amino acid, in a mouse model of atopic dermatitis alleviated its symptoms. In the present study, we investigated the effect of methionine on a mouse model of ACD caused by 1-fluoro-2,4-dinitrobenzene (DNFB). Differences in the effect of methionine were observed in DNFB-induced ACD model mice based on the mouse strain used. This difference was attributed to the suppression of hepatic dimethylglycine (DMG) production, which is associated with the suppression of hepatic betaine-homocysteine methyltransferase (Bhmt) expression by ACD. Although we did not reveal the mechanism underlying DMG suppression, our study suggests the presence of interactions between the liver and skin in dermatitis, such as the regulation of hepatic metabolic enzyme expression in dermatitis and the alleviation of dermatitis symptoms by the hepatic metabolism status of DMG.

TRPA1 is involved in the inhibitory effect of Ke-teng-zi on allergic contact dermatitis via MAPK and JAK/STAT3 signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

The seeds of Entada phaseoloides (Linn.) Merr. commonly named "Ke-teng-zi" is a traditional Chinese folk medicine and reported to treat dermatitis, spasm, and headache. However, the exact effect and the mechanism of Ke-teng-zi on the treatment of dermatitis is unclear.

AIM OF THE STUDY

To elucidate the antipruritic effect and molecular mechanisms of Ke-teng-zi on the treatment of allergic contact dermatitis (ACD).

MATERIALS AND METHODS

The main components of the n-butanol fraction of 70% ethanol extract from Ke-teng-zi (abbreviated as KB) were analyzed by HPLC. The chloroquine (CQ)-induced acute itch and squaraine dibutyl ester (SADBE)-induced ACD chronic itch in mice was established, and the TNF-α/IFN-γ stimulated Human keratinocytes (HaCaT) were used to evaluate the antipruritic and anti-inflammatory effects of KB. Behavioral tests, lesion scoring, and histology were also examined. The expression levels of molecules in MAPK and JAK/STAT3 pathways, the mRNA levels of chemokines and cytokines in both the skin of ACD mice and the HaCaT cells were detected by western blot and qPCR. Furthermore, whole-cell patch-clamp recordings in TRPA1-tranfected HEK293T cells were used to elucidate the effect of KB on TRPA1 channels. TRPA1 siRNA was used to evaluate the role of TRPA1 in the anti-inflammatory effect of KB in keratinocytes.

RESULTS

The main compounds in KB could bind to the active sites of TRPA1 mainly through hydrogen bond and hydrophobic bond interactions. KB could inhibit the scratching behavior in CQ-induced acute itch, and the inhibitory effect of KB was blocked by TRPA1 inhibitor HC-030031. In addition, KB significantly decreased the scratching bouts of ACD mice, reduced the skin lesion scores, mast cells degranulation, and epidermal thickening, inhibited the production of inflammatory chemokines/cytokines and CGRP, and down-regulated the levels of p-ERK1/2, p-p38, and p-STAT3, compared to the ACD mice. Moreover, continuous application of KB induced the desensitization of TRPA1 channels. Also, KB inhibited the expression of p-ERK1/2, p-p38, and p-STAT3, and down-regulated the expression of inflammatory chemokines and cytokines in vitro, which were reversed by the TRPA1 siRNA.

CONCLUSIONS

KB alleviated the pruritus and skin inflammation in ACD mice through TRPA1 channels desensitization and down-regulation of intracellular MAPK and JAK/STAT3 signaling pathways. Our results suggested that Ke-teng-zi is a potential drug for the treatment of inflammatory skin diseases such as ACD.

A Hydrophilic Sulfated Resveratrol Derivative for Topical Application: Sensitization and Anti-Allergic Potential

Resveratrol (RSV), a naturally occurring metabolite, is widely used in skincare products, but its hydrophobicity impairs its own incorporation into cosmetic formulations. RSV-GS is a synthetic hydrophilic sulfated glycosylated derivative inspired by marine natural products that present a lower cytotoxicity than RSV while exhibiting similar levels of bioactivity. Herein, we predict the skin sensitization potential of this new compound using an in vitro approach based on the OECD 442E guideline. Furthermore, the anti-allergic potential of RSV-GS was also disclosed. The monocyte THP-1 cell line was stimulated with RSV and RSV-GS in the presence or absence of the extreme skin allergen 1-fluoro-2,4-dinitrobenzene (DNFB). The results demonstrated that RSV-GS alone (500 µM) evoked a relative fluorescence index (RFI) lower than the thresholds established by the OECD guideline for CD54 (200%) and CD86 (150%), indicating the absence of a skin sensitization potential. Interestingly, in the presence of the skin allergen DNFB, RSV-GS exhibited the ability to rescue the DNFB-induced maturation of THP-1 cells, with RFI values lower than those for RSV, suggesting the potential of RSV-GS to mitigate skin sensitization evoked by allergens and, consequently, allergic contact dermatitis. These results open new avenues for the use of RSV-GS as a safe and anti-allergic active cosmetic ingredient.

Allergic Contact Dermatitis in Refractory Brick Production Worker: A Case Report

In this study, we investigated a 42-year-old man working in a refractory brick (RB) production line who had allergic contact dermatitis (ACD) due to skin exposure to chromium (Cr). He had visited a dermatologist several times over a five-month period and although he had been medically treated, the symptoms reappeared after he returned to work and resumed exposure. Finally, with the announcement of the definite diagnosis of ACD through a patch test, it was decided to exclude him from exposure, and after 20 days, the symptoms went through the recovery process. No new recurring episodes were reported during the six-month follow-up period.

A Retrospective Analysis to Investigate Contact Sensitization in Greek Population Using Classic and Machine Learning Techniques

Allergic contact dermatitis (ACD) is an inflammatory reaction affecting all age groups and both sexes. ACD is characterized by a delayed-type hypersensitivity reaction IV caused by skin contact with haptens. Chronic exposure typically leads to a decrease in erythema accompanied by lichenification (thickening and hardening of the skin) and persistent itching. The current study aims to investigate the patterns of contact sensitization in the Greek population using patch test data analysis. Patch test data from 240 patients (120 Males/120 Females) with allergic contact dermatitis were collected at the Laboratory for Patch Testing, National Reference Center for Occupational Dermatoses "Andreas Syggros" Hospital in Athens Greece. The contact allergic reactions were caused by ethylenediamine dihydrochloride 1%, thimerosal 0.5%, and methyldibromo-glutaronitrile 0.1% from the European baseline series of allergens; information was also collected for ICDRG evaluation, an extended MOAHLFA index and patient-reported outcomes (daily routine questionnaire). The chi-square test for independence and Spearman's rank were used to evaluate the association and correlation, respectively, between patient characteristics and ACD-related factors. Multiple correspondence analysis (MCA), which is a data analysis approach, was used to find and depict underlying structures in the data collection for nominal categorical data. Statistically significant associations were found between the following pairs of characteristics: eczema triggers and gender and eczema triggers and hand dermatitis. The results from MCA showed that there is correlation between allergic contact dermatitis onset, allergens, and demographic variables.

Melittin and diclofenac synergistically promote wound healing in a pathway involving TGF-β1

A dysregulation of the wound healing process can lead to the development of various intractable ulcers or excessive scar formation. Therefore it is essential to identify novel pharmacological strategies to promote wound healing and restore the mechanical integrity of injured tissue. The goal of the present study was to formulate a nano-complex containing melittin (MEL) and diclofenac (DCL) with the aim to evaluate their synergism and preclinical efficacy in an in vivo model of acute wound. After its preparation and characterization, the therapeutic potential of the combined nano-complexes was evaluated. MEL-DCL nano-complexes exhibited better regenerated epithelium, keratinization, epidermal proliferation, and granulation tissue formation, which in turn showed better wound healing activity compared to MEL, DCL, or positive control. The nano-complexes also showed significantly enhanced antioxidant activity. Treatment of wounded skin with MEL-DCL nano-complexes showed significant reduction of interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α (TNF-α) pro-inflammatory markers that was paralleled by a substantial increase in mRNA expression levels of collagen, type I, alpha 1 (Col1A1) and collagen, type IV, alpha 1 (Col4A1), and hydroxyproline content as compared to individual drugs. Additionally, MEL-DCL nano-complexes were able to significantly increase hypoxia-inducible factor 1-alpha (HIF-1α) and transforming growth factor beta 1 (TGF-β1) proteins expression compared to single drugs or negative control group. SB431542, a selective inhibitor of type-1 TGF-β receptor, significantly prevented in our in vitro assay the wound healing process induced by the MEL-DCL nano-complexes, suggesting a key role of TGF-β1 in the wound closure. In conclusion, the nano-complex of MEL-DCL represents a novel pharmacological tool that can be topically applied to improve wound healing.

Itch in Allergic Contact Dermatitis

Contact dermatitis is a continuous growing environmental and occupational health problem. It results in high costs for health care systems and the economy due to productivity loss. Moreover, it has a huge impact on the quality of life of patients. The immune response to contact allergy is very complex and not totally elucidated. Recently unique pathways preferentially activated by different allergens were identified. As for a lot of chronic itch disorders, antihistamines are ineffective for allergic contact dermatitis, suggesting a non-histaminergic itch. The precise mechanisms that underlie the development of itch in ACD remain poorly defined. This short review addresses the most recent insights in pruritus in ACD, opening perspectives for future therapies.