Mechanism and diagnosis of protein contact dermatitis

Gene profiling in active dermatitis lesions strengthens the diagnosis of allergic contact dermatitis

BACKGROUND

Distinguishing between allergic and nonallergic forms of Contact Dermatitis (CD) is challenging and requires investigations based on patch-testing. Early detection of allergy biomarkers in active CD lesions could refine and simplify the management of CD patients.

OBJECTIVE

To characterize the molecular signatures of active CD lesions.

METHODS

We studied the expression of 12 allergy biomarkers by qRT-PCR in active lesions of 38 CD patients. Allergic CD (ACD) was diagnosed based on patch test (PT) results and exposure assessment. Molecular signatures of active lesions, as well as positive PT reactions, were compared with those of reference chemical allergens and irritants.

RESULTS

Nineteen of the 38 CD patients reacted positively upon patch-testing and exposure assessment confirmed ACD diagnosis for 17 of them. Gene profiling of active CD lesions revealed 2 distinct molecular patterns: patients harboring signatures similar to reference allergens (n = 23) or irritants (n = 15). Among the 23 patients with an "allergy signature," we found the 17 patients with confirmed ACD, while no culprit allergen was identified for the 6 other patients. Interestingly, the 15 patients without biomarker induction had negative PT, suggesting that they developed nonallergic CD reactions.

CONCLUSION

Molecular signatures from active skin lesions may help to stratify CD patients and predict those suffering from ACD.

S2k-Leitlinie Diagnostik, Prävention und Therapie des Handekzems: S2k guideline diagnosis, prevention and therapy of hand eczema

Die S2k‐Leitlinie „Diagnostik, Prävention und Therapie des Handekzems (HE)“ gibt auf der Grundlage eines evidenz‐ und konsensbasierten Ansatzes konkrete Handlungsanweisungen und Empfehlungen für die Diagnostik, Prävention und Therapie des HE. Die Leitlinie wurde auf der Grundlage der deutschen Leitlinie „Management von Handekzemen“ aus dem Jahr 2009 und der aktuellen Leitlinie der European Society of Contact Dermatitis (ESCD) „Guidelines for diagnosis, prevention and treatment of hand eczema“ aus dem Jahr 2022 erstellt. Allgemeines Ziel der Leitlinie ist es, Dermatologen und Allergologen in der Praxis und Klinik eine akzeptierte, evidenzbasierte Entscheidungshilfe für die Auswahl sowie Durchführung einer geeigneten und suffizienten Therapie für Patienten mit Handekzemen zur Verfügung zu stellen. Die Leitlinie basiert auf zwei Cochrane‐Reviews zu therapeutischen und präventiven Interventionen beim HE. Die übrigen Kapitel wurden überwiegend basierend auf nicht systematischen Literaturrecherchen durch die Expertengruppe erarbeitet und konsentiert. Die Expertenkommission bestand aus Mitgliedern von allergologischen und berufsdermatologischen Fachgesellschaften und Arbeitsgruppen, einer Patientenvertretung und Methodikern. Im Rahmen einer Konsensuskonferenz am 15.09.2022 wurden die Vorschläge für die Empfehlungen und Kernaussagen unter Verwendung eines nominalen Gruppenprozesses konsentiert. Der strukturierte Konsensfindungsprozess wurde professionell moderiert. Die vorliegende Leitlinie hat eine Gültigkeit bis zum 22.02.2028.

S2k guideline diagnosis, prevention, and therapy of hand eczema

The consensus-based guideline "Diagnosis, prevention, and treatment of hand eczema (HE)" provides concrete instructions and recommendations for diagnosis, prevention, and therapy of HE based on an evidence- and consensus-based approach. The guideline was created based on the German guideline "Management von Handekzemen" from 2009 and the current guideline of the European Society of Contact Dermatitis (ESCD) "Guidelines for diagnosis, prevention, and treatment of hand eczema" from 2022. The general goal of the guideline is to provide dermatologists and allergologists in practice and clinics with an accepted, evidence-based decision-making tool for selecting and conducting suitable and sufficient therapy for patients with hand eczema. The guideline is based on two Cochrane reviews of therapeutic and preventive interventions for HE. The remaining chapters were mainly developed and consented based on non-systematic literature research by the expert group. The expert group consisted of members of allergological and occupational dermatological professional associations and working groups, a patient representative, and methodologists. The proposals for recommendations and key statements were consented by using a nominal group process during a consensus conference on September 15, 2022. The structured consensus-building process was professionally moderated. This guideline is valid until February 22, 2028.

Diseases from the Spectrum of Dermatitis and Eczema: Can "Omics" Sciences Help with Better Systematics and More Accurate Differential Diagnosis?

Researchers active in the field of inflammatory skin diseases from the spectrum of dermatitis and eczema are well aware of a considerable overlap in the clinical pictures and proposed sets of diagnostic criteria for these diseases, which can hardly be overcome through the clinical or epidemiological research. In effect, patients are included in studies based on vague and overlapping criteria, while heterogeneous study populations may, in turn, lead to non-representative outcomes and continued confusion. In this narrative review, a systematics of diseases from the spectrum of dermatitis and eczema is proposed based on the origins of causative factors and the pathomechanisms involved. Difficulties in differentiating between these diseases are discussed, and the extent to which advances in the "omics" sciences might help to overcome them is considered. Of all the "omics" research in this field, more than 90% of the published papers were devoted to atopic dermatitis, with a striking underrepresentation of other diseases from the spectrum of dermatitis and eczema, conditions which collectively exceed the rates of atopic dermatitis by far. A greater "omics" research effort is urgently needed to tackle other dermatitides, like allergic, irritant and protein contact dermatitis, as well as radiation, seborrheic, stasis or autoimmune dermatitis. Atopic dermatitis findings should be validated not only against healthy donors but also other dermatitides. A clinic-oriented approach is proposed for future "omics" studies in the field of dermatitis and eczema.

Contact Urticaria Syndrome: a Comprehensive Review

Purpose of Review

Contact urticaria syndrome includes contact urticaria and protein contact dermatitis. Underreport, underdiagnosis, or misdiagnosis of entities within the contact urticaria syndrome is believed to be common, especially in the occupational setting. This review provides a structured overview of the entities comprised in this syndrome as well as the diagnostic work-up and management strategies.

Recent Findings

Contact urticaria syndrome has been increasingly described due to personal protective equipment and hand sanitizers in the context of the COVID-19 pandemic. The use of legal cannabis products has led to a rise in occupational cases of contact urticaria to cannabis. A declining trend in the evolution of contact urticaria has been described for natural rubber latex allergy due to the use of synthetic gloves. Prick test has been proposed as a screening method, particularly if multiple products are to be tested, instead of the classical sequential scheme.

Summary

Physicians should be aware of the growing number of culprit agents leading to contact urticaria syndrome. Clinical presentation may be challenging since it includes immediate urticaria and/or eczema and even more generalized reactions. Diagnosis requires a high degree of suspicion, detailed occupational history, and complementary tests, including skin testing. The best treatment is to avoid contact with the culprit agent and to implement preventive measures.

Topical non-pharmacological treatment of eczema: an Italian consensus

Eczematous diseases (contact dermatitis, atopic dermatitis, hand eczema) are among the most frequent findings in dermatological clinical practice. A large body of evidence exists on structural and functional skin barrier damage in eczematous diseases, and on the importance of interventions aimed to repair such damage. While there is substantial agreement on pharmacological treatment, more sparse data are available on role, indications and usefulness of topical non-pharmacological treatments, despite significant research and progress in the composition and technology of emollients, cleansers and barrier creams significantly changed and expanded the functional activities of these products. This often leads to inadequate prescription and/or use, which increase individual and social costs of the disease and make the products useless or, in some cases, even counterproductive. This consensus document, discussed and compiled in a series of meetings by a group of Italian dermatologists experienced in the field of eczematous diseases, summarizes epidemiology and clinical features of the nosological entities of the "eczema family", illustrates the chemical/biochemical structure of emollients, cleansers and barrier creams, and aims to help physicians to exploit the full potential of available products, by providing a detailed but practical guide on characteristics, indications and correct use of non-pharmacological treatments currently available for eczematous diseases.

Proteolytic activity accelerates the TH17/TH22 recall response to an epicutaneous protein allergen-induced TH2 response

Epicutaneous exposure to protein allergens, such as papain, house dust mite (HDM), and ovalbumin (OVA), represents an important mode of sensitization for skin diseases including protein contact dermatitis, immunologic contact urticaria, and atopic dermatitis. These diseases are inducible by re-exposure to an allergen at both original skin sensitization and distant skin sites. In this study, we examined the serum IgE/IgG₁ response, differentiation of T-helper (T_H) cells, and epicutaneous T_H recall response in mice pre-sensitized with protein allergens through the back skin and subsequently challenged on the ear skin. Repeated epicutaneous sensitization with allergenic proteins including papain, HDM, OVA, and protease inhibitor-treated papain, but not bovine serum albumin, induced serum allergen-specific antibody production, passive cutaneous anaphylaxis responses, and T_H2 differentiation in the skin draining lymph node (DLN) cells. Sensitization with papain or HDM, which have protease activity, resulted in the differentiation of T_H17 as well as T_H2. In papain- or HDM-sensitized mice, a subsequent single challenge on the ear skin induced the expression of T_H2 and T_H17/T_H22 cytokines. These results suggest that allergenic proteins induce the differentiation of T_H2 in skin DLN cells and an antibody response. These findings may be useful for identifying proteins of high and low allergenic potential. Moreover, allergenic proteins containing protease activity may also differentiate T_H17 and induce T_H2 and T_H17/T_H22 recall responses at epicutaneous challenge sites. This suggests that allergen protease activity accelerates the onset of skin diseases caused by protein allergens.

Novel insights into contact dermatitis

Contact dermatitis is a common disease, caused by repeated skin contact to contact allergens or irritants, resulting in allergic contact dermatitis (ACD) and/or irritant contact dermatitis. Attempts have been made to identify biomarkers to distinguish irritant and allergic patch test reactions, which could aid diagnosis. Some promising candidates have recently been identified, but verification and validation in clinical cases still need to be done. New causes of ACD are constantly recognized. In this review, 10 new contact allergens from recent years, were identified, several relating to anti-age products. Frequent allergens causing considerable morbidity in the population such as the preservative methylisothiazolinone (MI) have been regulated in EU. A significant drop in cases has been seen, while high rates are still occurring in other areas such as North America. Other frequent causes are fragrance allergens especially widely used terpenes and acrylates used in medical devises for control of diabetes. These represent unsolved problems. Recent advances in immunology have opened for a better understanding of the complexity of contact dermatitis, especially ACD. The disease may be more heterogenous that previous understood with several subtypes. With the rapidly evolving molecular understanding of the disease, the potential for development of new drugs for personalized treatment of contact dermatitis is considerable.

Enzymes and sensitization via skin exposure: A critical analysis

Some proteins, including enzymes, can induce allergic sensitization of various types, including allergic sensitization of the respiratory tract. There is now an increased understanding of the role that the skin plays in the development of IgE-mediated allergy and this prompts the question whether topical exposure to enzymes used widely in consumer cleaning products could result in allergic sensitization. Here, the evidence that proteins can interact with the skin immune system and the way they do so is reviewed, together with a consideration of the experience gained over decades of the use of enzymes in laundry and cleaning products. The conclusion drawn is that although transcutaneous sensitization to proteins can occur (typically through compromised skin) resulting in IgE antibody-mediated allergy, in practice such skin contact with enzymes used in laundry and cleaning products does not appear to pose a significant risk of allergic disease. Further, the evidence summarized in this publication support the view that proteins do not pose a risk of allergic contact dermatitis.

Qualitative and quantitative analysis of Arnebiae Radix and Dictamni Cortex and efficacy study of herbal extracts on allergic contact dermatitis using 3D human reconstructed epidermis

Objective

To evaluate the quality of Arnebiae Radix (AR) and Dictamni Cortex (DC) and study the efficacy of herbal extracts of these two herbs on the treatment of allergic contact dermatitis (ACD).

Methods

Qualitative and quantitative analysis of effective components was performed using High Performance Thin Layer Chromatography (HPTLC), High Performance Liquid Chromatography (HPLC), and HPLC-Quadrupole Time of Flight-Mass Spectrometry (HPLC-QTOF-MS). In vitro allergic ACD 3D model was established by incubating 3D reconstructed human epidermis (RHE) with skin sensitizer, potassium dichromate. A total of 65 gene expression that were associated with ACD, which included 24 antioxidant responsive element (ARE) and 41 SENS-IS genes were quantified by qRT-PCR. More than or equal to 10 ARE genes and 18 SENN-IS genes were induced by 1.3-fold, demonstrating the successful establishment of in vitro ACD model. Oil extracts of AR and DC were applied on the in vitro ACD model to study the efficacy.

Results

Batch 3 of AR and batch 2 of DC showed presence of all active ingredients with the highest concentrations. Active ingredients of the herbs were extracted using a special oil and formulated into herbal oil extracts. The herbal oil extracts were able to down regulate the induced genes in the in-vitro ACD skin model, bringing the tissue back to homeostatic status.

Conclusion

The oil extracts showed the potent efficacy of using AR and DC in ACD treatment. The combination study will be done to optimize the formulation ratio which will be developed into a topical cream.

Epicutaneous challenge with protease allergen requires its protease activity to recall TH2 and TH17/TH22 responses in mice pre-sensitized via distant skin

Epicutaneous exposure to allergenic proteins is an important sensitization route for skin diseases like protein contact dermatitis, immunologic contact urticaria, and atopic dermatitis. Environmental allergen sources such as house dust mites contain proteases, which are frequent allergens themselves. Here, the dependency of T-helper (T_H) cell recall responses on allergen protease activity in the elicitation phase in mice pre-sensitized via distant skin was investigated. Repeated epicutaneous administration of a model protease allergen, i.e. papain, to the back skin of hairless mice induced skin inflammation, serum papain-specific IgE and T_H2 and T_H17 cytokine responses in the sensitization sites, and antigen-restimulated draining lymph node cells. In the papain-sensitized but not vehicle-treated mice, subsequent single challenge on the ear skin with papain, but not with protease inhibitor-treated papain, up-regulated the gene expression of T_H2 and T_H17/T_H22 cytokines along with cytokines promoting these T_H cytokine responses (TSLP, IL-33, IL-17C, and IL-23p19). Up-regulation of IL-17A gene expression and cells expressing RORγt occurred in the ear skin of the presensitized mice even before the challenge. In a reconstructed epidermal model with a three-dimensional culture of human keratinocytes, papain but not protease inhibitor-treated papain exhibited increasing transdermal permeability and stimulating the gene expression of TSLP, IL-17C, and IL-23p19. This study demonstrated that allergen protease activity contributed to the onset of cutaneous T_H2 and T_H17/T_H22 recall responses on allergen re-encounter at sites distant from the original epicutaneous sensitization exposures. This finding suggested the contribution of protease-dependent barrier disruption and induction of keratinocyte-derived cytokines to the recall responses.

Protein Causes of Urticaria and Dermatitis

Protein contact dermatitis is a cutaneous hypersensitivity reaction after chronic, recurrent exposure or chronic irritation to animal or plant protein. Although the pathophysiological mechanisms underlying protein contact dermatitis are not well characterized, protein contact dermatitis is thought to be caused by combined type I/IV-mediated, type-1 mediated, or a Langerhans cell immunoglobulin E-mediated delayed hypersensitivity reaction. This chapter reviews the epidemiology, pathogenesis, clinical features, common protein allergens, diagnostic process, treatment options, and prognosis of protein contact dermatitis.

Contact dermatitis

Contact dermatitis (CD) is among the most common inflammatory dermatological conditions and includes allergic CD, photoallergic CD, irritant CD, photoirritant CD (also called phototoxic CD) and protein CD. Occupational CD can be of any type and is the most prevalent occupational skin disease. Each CD type is characterized by different immunological mechanisms and/or requisite exposures. Clinical manifestations of CD vary widely and multiple subtypes may occur simultaneously. The diagnosis relies on clinical presentation, thorough exposure assessment and evaluation with techniques such as patch testing and skin-prick testing. Management is based on patient education, avoidance strategies of specific substances, and topical treatments; in severe or recalcitrant cases, which can negatively affect the quality of life of patients, systemic medications may be needed.

Total dose defines the incidence of percutaneous IgE/IgG1 mediated immediate-type hypersensitivity caused by papain

Assessment of human health risk requires an understanding of antigen dose metrics associated with toxicity. Whereas assessment of the human health risk for delayed-type hypersensitivity is understood, the metrics remain unclear for percutaneous immediate-type hypersensitivity (ITH) mediated by IgE/IgG1. In this work, we aimed to investigate the dose metric for percutaneous ITH mediated by IgE/IgG1 responses. Papain, which causes ITH via percutaneous sensitization in humans, was used to sensitize guinea pigs and mice. The total dose per animal or dose per unit area was adjusted to understand the drivers of sensitization. Passive cutaneous anaphylaxis (PCA) and enzyme-linked immunosorbent assay (ELISA) for papain-specific IgG1 enabled quantification of the response in guinea pigs. In mice, the number of antigen-bearing B cells in the draining lymph nodes (DLN) was calculated using flow cytometry papain-specific IgG1 and IgE levels were quantified by ELISA. PCA positive test rates and the amounts of antigen-specific antibody corresponded with total dose per animal, not dose per unit area. Furthermore, the number of B cells taking up antigen within DLN also correlated with total dose. These findings indicate that the total antigen dose is the important metric for percutaneous IgE/IgG1-mediated ITH.