The transcriptome of hand eczema assessed by tape stripping

RNA-sequencing of paired tape-strips and skin biopsies in atopic dermatitis reveals key differences

BACKGROUND

Skin tape-strips and biopsies are widely used methods for investigating the skin in atopic dermatitis (AD). Biopsies are more commonly used but can cause scarring and pain, whereas tape-strips are noninvasive but sample less tissue. The study evaluated the performance of skin tape-strips and biopsies for studying AD.

METHODS

Whole-transcriptome RNA-sequencing was performed on paired tape-strips and biopsies collected from lesional and non-lesional skin from AD patients (n = 7) and non-AD controls (n = 5). RNA yield, mapping efficiency, and differentially expressed genes (DEGs) for the two methods (tape-strip/biopsy) and presence of AD (AD/non-AD) were compared.

RESULTS

Tape-strips demonstrated a lower RNA yield (22 vs. 4596 ng) and mapping efficiency to known genes (28% vs. 93%) than biopsies. Gene-expression profiles of paired tape-strips and biopsies demonstrated a medium correlation (R2 = 0.431). Tape-strips and biopsies demonstrated systematic differences in measured expression levels of 6483 genes across both AD and non-AD samples. Tape-strips preferentially detected many itch (CCL3/CCL4/OSM) and immune-response (CXCL8/IL4/IL5/IL22) genes as well as markers of epidermal dendritic cells (CD1a/CD207), while certain cytokines (IL18/IL37), skin-barrier genes (KRT2/FLG2), and dermal fibroblasts markers (COL1A/COL3A) were preferentially detected by biopsies. Tape-strips identified more DEGs between AD and non-AD (3157 DEGs) then biopsies (44 DEGs). Tape-strips also detected higher levels of bacterial mRNA than biopsies.

CONCLUSIONS

This study concludes that tape-strips and biopsies each demonstrate respective advantages for measuring gene-expression changes in AD. Thus, the specific skin layers and genes of interest should be considered before selecting either method.

Inflammatory plasma signature of chronic hand eczema: Associations with aetiological and clinical subtypes

BACKGROUND

Chronic hand eczema (CHE) is a highly prevalent, heterogeneous, skin disease that encompasses different aetiological and clinical subtypes. Severe CHE without atopic dermatitis has been associated with systemic inflammation; yet it remains unknown if specific CHE subtypes leave distinct, systemic, molecular signatures.

OBJECTIVES

To characterize the inflammatory plasma signature of different aetiological and clinical CHE subtypes.

METHODS

We assessed expression levels of 266 inflammatory and cardiovascular disease risk plasma proteins as well as filaggrin gene mutation status in 51 well-characterized CHE patients without concomitant atopic dermatitis and 40 healthy controls. Plasma protein expression was compared between aetiological and clinical CHE subgroups and controls both overall and according to clinical CHE severity. Correlation analyses for biomarkers, clinical and self-reported variables were performed.

RESULTS

Very severe, chronic allergic contact dermatitis (ACD) on the hands was associated with a mixed Type 1/Type 2 systemic immune activation as compared with controls. Circulating levels of Type 1/Type 2 inflammatory biomarkers correlated positively with clinical disease severity among CHE patients with ACD. No biomarkers were found, that could discriminate between aetiological subtypes, for example, between ACD and irritant contact dermatitis. Hyperkeratotic CHE showed a distinct, non-atopic dermatitis-like, systemic footprint with upregulation of markers associated with Type 1 inflammation and tumour necrosis factor alpha, but not Type 2 inflammation. Increased levels of CCL19 and CXCL9/10 could discriminate hyperkeratotic CHE from both vesicular and chronic fissured CHE, whereas no difference was found between the latter two subtypes.

CONCLUSION

Profiling of systemic biomarkers showed potential for identifying certain CHE subtypes. Peripheral blood levels of inflammatory biomarkers were associated and correlated with the clinical disease severity of chronic ACD on the hands, underlining that this is a systemic disease. We question whether hyperkeratotic CHE should be classified as eczema.

Epidermal biomarkers of the skin barrier in atopic and contact dermatitis

Dysfunction of the skin barrier plays a critical role in the initiation and progression of inflammatory skin diseases, such as atopic dermatitis and contact dermatitis. Epidermal biomarkers can aid in evaluating the functionality of the skin barrier and understanding the mechanisms that underlay its impairment. This narrative review provides an overview of recent studies on epidermal biomarkers associated with the function and integrity of the skin barrier, and their application in research on atopic dermatitis and contact dermatitis. The reviewed studies encompass a wide spectrum of molecular, morphological and biophysical biomarkers, mainly obtained from stratum corneum tape strips and biopsies. Lipids, natural moisturizing factors, and structural proteins are the most frequently reported molecular biomarkers. Additionally, corneocyte surface topography and elasticity show potential as biomarkers for assessing the physical barrier of the skin. In contact dermatitis studies, biomarkers are commonly employed to evaluate skin irritation and differentiate between irritant and allergic contact dermatitis. In atopic dermatitis, biomarkers are primarily utilized to identify differences between atopic and healthy skin, for predictive purposes, and monitoring response to therapies. While this overview identifies potential biomarkers for the skin barrier, their validation as epidermal biomarkers for atopic dermatitis and contact dermatitis has yet to be established.

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.

Assessment of Treatment-Relevant Immune Biomarkers in Psoriasis and Atopic Dermatitis: Toward Personalized Medicine in Dermatology

Immunologically targeted therapies have revolutionized the treatment of inflammatory dermatoses, including atopic dermatitis and psoriasis. Although immunologic biomarkers hold great promise for personalized classification of skin disease and tailored therapy selection, there are no approved or widely used approaches for this in dermatology. This review summarizes the translational immunologic approaches to measuring treatment-relevant biomarkers in inflammatory skin conditions. Tape strip profiling, microneedle-based biomarker patches, molecular profiling from epidermal curettage, RNA in situ hybridization tissue staining, and single-cell RNA sequencing have been described. We discuss the advantages and limitations of each and open questions for the future of personalized medicine in inflammatory skin disease.

Circulating biomarkers are associated with disease severity of chronic hand eczema and atopic dermatitis

BACKGROUND

Although chronic hand eczema (CHE) is a highly prevalent and disabling skin disease, it is currently unknown if CHE is associated with systemic inflammation.

OBJECTIVES

To characterize the plasma inflammatory signature of CHE.

METHODS

Using Proximity Extension Assay technology, we assessed 266 inflammatory and cardiovascular disease risk proteins in the plasma of 40 healthy controls, 57 patients with atopic dermatitis (AD) with active lesions, 11 with CHE and a history of AD (CHEPREVIOUS_AD), and 40 with CHE and no history of AD (CHENO_AD). Filaggrin gene mutation status was also assessed. Protein expression was compared between groups and according to disease severity. Correlation analyses for biomarkers, and clinical- and self-reported variables, were performed.

RESULTS

Very severe CHENO_AD was associated with systemic inflammation when compared with controls. Levels of T helper (Th)2- and Th1-, general inflammation and eosinophil activation markers increased with severity of CHENO_AD, primarily being significantly increased in very severe disease. Significant, positive correlations were found between markers from these pathways and severity of CHENO_AD. Moderate-to-severe but not mild AD displayed systemic inflammation. The Th2 markers C-C motif chemokine (CCL)17 and CCL13 (also known as monocyte chemotactic protein 4) were the top differentially expressed proteins in both very severe CHENO_AD and moderate-to-severe AD, showing a higher fold change and significance in AD. CCL17 and CCL13 levels further correlated positively with disease severity in both CHENO_AD and AD.

CONCLUSIONS

Systemic Th2-driven inflammation is shared between very severe CHE with no history of AD, and moderate-to-severe AD, suggesting that Th2 cell targeting could be effective in several CHE subtypes.

[New guideline and treatment options for hand eczema]

Due to its high prevalence and associated socioeconomic consequences, hand eczema is a burden for those affected and for society. The various hand eczema subtypes must be differentiated from each other through structured anamnesis and diagnostics in order to initiate cause-related preventive measures in addition to symptomatic therapy. There are new developments in the diagnosis, prevention, and treatment of hand eczema. The diagnostic possibilities are being expanded through molecular methods. Modern topical and systemic therapies offer promising treatment options for patients with atopic but also chronic hand eczema regardless of the underlying etiology.

The proteome of hand eczema assessed by tape stripping

Hand eczema (HE) is a prevalent skin disease. However, classification of HE into different subtypes remains challenging. Limited number of prior studies have employed invasive biopsy-based strategies; yet, studies of the HE proteome using non-invasive tape stripping methodology have not been reported. In this study, we wanted to assess whether global proteomic analysis of skin tape strip samples can be used for sub-classification of HE patients. Tape strips were collected from patients with HE and healthy skin. Liquid chromatography-mass spectrometry (LC/MS) proteomics was performed, and the global protein expression was analyzed. We identified 2,919 proteins in stratum corneum-derived skin cells from tape strip samples. Compared to healthy skin, the lesional samples from HE patients exhibited increased expression of immune-related markers and a decreased expression of structural barrier proteins. The difference between HE subtypes was restricted to the lesional skin areas, and included an increased expression of skin barrier-related proteins independently of the concurrent AD. In conclusion we found, that the non-invasive tape strip method used in combination with LC/MS proteomics can be used for analysis of skin protein expression in HE patients. Thus, the method shows potential for assessing the proteomic differences between subtypes of HE, and biomarker discovery.

Detection of cutaneous malignant melanoma using RNA sampled by tape strips: A study protocol

Background

Cutaneous malignant melanoma (CMM) is curable if detected in its early stages. However, the clinical recognition of CMM is challenging. An American research group has shown promising results in detecting CMM based on RNA profiles sampled from suspicious lesions with tape strips. We aim to further develop this technique and validate if RNA profiles sampled with tape strips can detect CMM.

Methods

This prospective cohort study will include approximately 200 lesions clinically suspected of CMM requiring surgical removal. Tape stripping of the lesions will be performed just before surgical excision. Subsequently, RNA on the tape strips is analyzed using quantitative real-time polymerase chain reaction with TaqMan technology. The results are combined into a binary outcome where positive indicates CMM and negative indicates no CMM. The histopathological diagnosis of the lesions will be used as the gold standard. The main outcome is the results of the RNA test and the histopathological diagnosis, which, combined, provide the sensitivity and specificity of the test.

Discussion

The accuracy of the clinical examination in CMM diagnostics is limited. This clinical trial will explore the ability to use RNA analysis to improve the management of suspicious lesions by enhancing early diagnostic accuracy. Hopefully, it can reduce the number of benign lesions being surgically removed to rule out CMM and decrease patient morbidity.

Trial registration

The project was approved by The Committee on Health Research Ethics of the Capital Region of Denmark (H-15010559) and registered at the Danish Data Protection Agency (BFH-2015-065).

Profiling the Atopic Dermatitis Epidermal Transcriptome by Tape Stripping and BRB-seq

Tape stripping is a non-invasive skin sampling technique, which has recently gained use for the study of the transcriptome of atopic dermatitis (AD), a common inflammatory skin disorder characterized by a defective epidermal barrier and perturbated immune response. Here, we performed BRB-seq—a low cost, multiplex-based, transcriptomic profiling technique—on tape-stripped skin from 30 AD patients and 30 healthy controls to evaluate the methods’ ability to assess the epidermal AD transcriptome. An AD signature consisting of 91 differentially expressed genes, specific for skin barrier and inflammatory response, was identified. The gene expression in the outermost layers, stratum corneum and stratum granulosum, of the skin showed highest correlation between tape-stripped skin and matched full-thickness punch biopsies. However, we observed that low and highly variable transcript counts, probably due to low RNA yield and RNA degradation in the tape-stripped skin samples, were a limiting factor for epidermal transcriptome profiling as compared to punch biopsies. We conclude that deep BRB-seq of tape-stripped skin is needed to counteract large between-sample RNA yield variation and highly zero-inflated data in order to apply this protocol for population-wide screening of the epidermal transcriptome in inflammatory skin diseases.