Single-cell sequencing delineates T-cell clonality and pathogenesis of the parapsoriasis disease group

BACKGROUND

Mycosis fungoides (MF), the most common cutaneous T-cell lymphoma, is often underdiagnosed in early stages because of similarities with benign dermatoses such as atopic dermatitis (AD). Furthermore, the delineation from what is called "parapsoriasis en plaque", a disease that can appear either in a small- or large-plaque form, is still controversial.

OBJECTIVE

We sought to characterize the parapsoriasis disease spectrum.

METHODS

We performed single-cell RNA sequencing of skin biopsies from patients within the parapsoriasis-to-early-stage MF spectrum, stratified for small and large plaques, and compared them to AD, psoriasis, and healthy control skin.

RESULTS

Six of 8 large-plaque lesions harbored either an expanded alpha/beta or gamma/delta T-cell clone with downregulation of CD7 expression, consistent with a diagnosis of early-stage MF. In contrast, 6 of 7 small-plaque lesions were polyclonal in nature, thereby lacking a lymphomatous phenotype, and also revealed a less inflammatory microenvironment than early-stage MF or AD. Of note, polyclonal small- and large-plaque lesions characteristically harbored a population of NPY+ innate lymphoid cells and displayed a stromal signature of complement upregulation and antimicrobial hyperresponsiveness in fibroblasts and sweat gland cells, respectively. These conditions were clearly distinct from AD or psoriasis, which uniquely harbored CD3+CRTH2+ IL-13 expressing "TH2A" cells, or strong type 17 inflammation, respectively.

CONCLUSION

These data position polyclonal small- and large-plaque parapsoriasis lesions as a separate disease entity that characteristically harbors a so far undescribed innate lymphoid cell population. We thus propose a new term, "polyclonal parapsoriasis en plaque", for this kind of lesion because they can be clearly differentiated from early- and advanced-stage MF, psoriasis, and AD on several cellular and molecular levels.

Single-cell RNA sequencing reveals 2D cytokine assay can model atopic dermatitis more accurately than immune-competent 3D setup

Modelling atopic dermatitis (AD) in vitro is paramount to understand the disease pathophysiology and identify novel treatments. Previous studies have shown that the Th2 cytokines IL-4 and IL-13 induce AD-like features in keratinocytes in vitro. However, it has not been systematically researched whether the addition of Th2 cells, their supernatants or a 3D structure is superior to model AD compared to simple 2D cell culture with cytokines. For the first time, we investigated what in vitro option most closely resembles the disease in vivo based on single-cell RNA sequencing data (scRNA-seq) obtained from skin biopsies in a clinical study and published datasets of healthy and AD donors. In vitro models were generated with primary fibroblasts and keratinocytes, subjected to cytokine treatment or Th2 cell cocultures in 2D/3D. Gene expression changes were assessed using qPCR and Multiplex Immunoassays. Of all cytokines tested, incubation of keratinocytes and fibroblasts with IL-4 and IL-13 induced the closest in vivo-like AD phenotype which was observed in the scRNA-seq data. Addition of Th2 cells to fibroblasts failed to model AD due to the downregulation of ECM-associated genes such as POSTN. While keratinocytes cultured in 3D showed better stratification than in 2D, changes induced with AD triggers did not better resemble AD keratinocyte subtypes observed in vivo. Taken together, our comprehensive study shows that the simple model using IL-4 or IL-13 in 2D most accurately models AD in fibroblasts and keratinocytes in vitro, which may aid the discovery of novel treatment options.

[Molecular diagnosis of hand eczema]

BACKGROUND

Because hand eczema is a diagnostic challenge even for experienced dermatologists, a correct diagnosis is essential to ensure success of specific therapies.

OBJECTIVES

Prerequisites for successful molecular diagnostics in general and in hand eczema in particular are discussed.

MATERIALS AND METHODS

Basic research and opinion statement on new developments in molecular diagnostics are considered with a special focus on hand eczema.

RESULTS

The first molecular classifier to distinguish psoriasis from (hand) eczema signature has been introduced as CE-marked in vitro diagnostics (CE-IVD); many more biomarkers associated with diagnostics, theranostics, or natural course of the disease are currently being investigated.

CONCLUSIONS

Diagnosis of hand eczema will be supported by molecular diagnostics in the near future; we are at the beginning of the molecular era in dermatology.

[Hand eczema or psoriasis: update on the FB 323 study occupational dermatology cohort]

In daily dermatological practice, the distinction between eczema and psoriasis in dermatoses of the hands can be difficult. However, a clear diagnosis is necessary to initiate optimal therapy and management. In recent years, the so-called molecular classifier has been developed for optimized differentiation of eczema and psoriasis. An occupational dermatological cohort has been established at Heidelberg University Hospital since 2020. It is funded by the German Statutory Accident Insurance. The aim is to follow-up patients over 3 years where this new diagnostic method is used and to compare the results with a retrospective occupational dermatological cohort. Recruitment ended in December 2022. The current analysis reports participants' occupational activity, insurance status, disease progression, and number of sick days. A total of 287 patients were included; mean age was 50.4 years and 63.5% (n = 181) were undergoing treatment at the expense of the liable statutory accident insurance at the start of the study. About 50% of the patients worked in health professions, metal industry, or construction. The average duration of occupational dermatosis was 6.5 years. In 38.9% of the patients, the clinical diagnosis had been classified as unclear by the treating dermatologist. By using the molecular classifier, the diagnosis could be clarified in 98% of the cases (eczema vs. psoriasis). The first analyses demonstrate that the molecular classifier contributes to improving therapy by optimizing the diagnosis.

Eczematized psoriasis - a frequent but often neglected variant of plaque psoriasis

Psoriasis is a common chronic inflammatory skin disease that causes systemic inflammation and severely impacts the patient's quality of life. Several highly effective therapeutics for psoriasis have been approved in recent years. However, in real life, a high proportion of patients either do not experience the clinical improvement observed in clinical trials or develop a secondary loss of efficacy. This may be a result of unrecognized endotypes of psoriasis that need to be characterized in greater depth to enable selection of an appropriate therapy. Eczematized psoriasis, which occurs in approximately 5-10% of patients with psoriasis, is an often-neglected variant of psoriasis. The term "eczematized psoriasis" refers to patients developing psoriasis with similarities to eczema. These patients typically present with severe itching, and skin biopsies often reveal eosinophil granulocytes, serum crusts, or spongiosis, which are frequently observed in eczema. From an immunological perspective, additional signaling pathways that are responsible for eczema reactions might be activated in eczematized psoriasis compared to classical plaque psoriasis. This review summarizes the key clinical, histological, and immunological features of eczematized psoriasis, proposes diagnostic criteria, and evaluates the therapeutic options for eczematized psoriasis.

Predictive Value of Nasal Nitric Oxide and Serum NOS2 Levels in the Efficacy of Subcutaneous Immunotherapy in Pediatric Patients with Allergic Rhinitis

Background

Subcutaneous immunotherapy (SCIT) is an effective therapy for allergic rhinitis (AR), but some AR patients still do not benefit from it. Nasal nitric oxide (nNO) and inducible nitric oxide synthase (iNOS/NOS2) act important roles in AR. This study aims to explore the abilities of serum NOS2 and nNO in predicting the clinical efficacy of SCIT in AR patients.

Methods

We recruited 40 healthy controls (HCs) and 120 AR patients in this study. Serum NOS2 and nNO levels were compared between the two groups. In the AR group, patients underwent and finished 1-year of SCIT, and divided into the effective and ineffective groups, and the relationships between serum NOS2 and nNO levels and efficacy of SCIT were evaluated.

Results

The serum NOS2 and nNO levels were higher in AR patients than HCs. In the effective group, the serum NOS2 and nNO levels were increased than the ineffective group. ROC curves presented that a combination of serum NOS2 and nNO exhibited promising predictive ability in predicting the clinical efficacy of SCIT.

Conclusions

Serum NOS2 and nNO levels were enhanced in AR patients and might affect the efficacy of SCIT. The combined use of serum NOS2 and nNO levels could be a reliable and useful method for predicting the clinical efficacy of SCIT.

Cobalt ions induce metabolic stress in synovial fibroblasts and secretion of cytokines/chemokines that may be diagnostic markers for adverse local tissue reactions to hip implants

Adverse local tissue reactions (ALTRs) are a prominent cause of hip implant failure. ALTRs are characterized by aseptic necrosis and leukocyte infiltration of synovial tissue. The prevalence of ALTRs in hips with failing metal implants, with highest rates occurring in patients with metal-on-metal articulations, suggests a role for CoCrMo corrosion in ALTR formation. Although hypersensitivity reactions are the most accepted etiology, the precise cellular mechanism driving ALTR pathogenesis remains enigmatic. Here we show that cobalt ions released by failing hip implants induce mitochondrial stress and cytokine secretion by synovial fibroblasts: the presumptive initiators of ALTR pathogenesis. We found that in-vitro treatment of synovial fibroblasts with cobalt, but not chromium, generated gene expression changes indicative of hypoxia and mitophagy responses also observed in ALTRs biopsies. Inflammatory factors secreted by cobalt-exposed synovial fibroblasts were among those most concentrated in ALTR synovial fluid. Furthermore, both conditioned media from cobalt-exposed synovial fibroblasts, and synovial fluid from ALTRs patients, elicit endothelial activation and monocyte migration. Finally, we identify the IL16/CTACK ratio in synovial fluid as a possible diagnostic marker of ALTRs. Our results provide evidence suggesting that metal ions induce cell stress in synovial fibroblasts that promote an inflammatory response consistent with initiating ALTR formation. STATEMENT OF SIGNIFICANCE: We demonstrate that the cytotoxic effects of cobalt ions on the synovial cells (fibroblast) is sufficient to trigger inflammation on hip joints with metal implants. Cobalt ions affect mitochondrial function, leading to the auto phagocytosis of mitochondria and trigger a hypoxic response. The cell's hypoxic response includes secretion of cytokines that are capable of trigger inflammation by activating blood vessels and enhancing leukocyte migration. Among the secreted cytokines is IL-16, which is highly concentrated in the synovial fluid of the patients with adverse local tissue reactions and could be use as diagnostic marker. In conclusion we define the cells of the hip joint as key players in triggering the adverse reactions to hip implants and providing biomarkers for early diagnosis of adverse reactions to hip implants.

Immune and barrier characterization of atopic dermatitis skin phenotype in Tanzanian patients

BACKGROUND

Atopic dermatitis (AD) is a common disease, with particularly high prevalence found in Africa. It is increasingly recognized that patients with AD of different ethnic backgrounds have unique molecular signatures in the skin, potentially accounting for treatment response variations. Nevertheless, the skin profile of patients with AD from Africa is unknown, hindering development of new treatments targeted to this patient population.

OBJECTIVE

To characterize the skin profile of patients with AD from Africa.

METHODS

Gene expression studies, including RNA sequencing (using threshold of fold change of >2 and false discovery rate of <0.05) and real-time polymerase chain reaction, were performed on skin biopsies of Tanzanian patients with moderate-to-severe AD and controls.

RESULTS

Tanzanian AD skin presented robust up-regulations of multiple key mediators of both T helper 2 (TH2) (interleukin 13 [IL-13], IL-10, IL-4R, CCL13,CCL17,CCL18,CCL26) and TH22 (IL22, S100As) pathways. Markers related to TH17 and IL-23 (IL-17A, IL-23A, IL-12, PI3, DEFB4B) and TH1 (interferon gamma, CXCL9,CXCL10,CXCL11) were also significantly overexpressed in AD tissues (FDR<.05), albeit to a lesser extent. IL-36 isoforms revealed substantial up-regulations in African skin. The barrier fingerprint of Tanzanian AD revealed no suppression of hallmark epidermal barrier differentiation genes, such as filaggrin, loricrin, and periplakin, with robust attenuation of lipid metabolism genes (ie, AWAT1).

CONCLUSION

The skin phenotype of Tanzanian patients with AD is consistent with that of African Americans, exhibiting dominant TH2 and TH22 skewing, minimal dysregulation of terminal differentiation, and even broader attenuation of lipid metabolism-related products. These data highlight the unique characteristic of AD in Black individuals and the need to develop unique treatments targeting patients with AD from these underrepresented populations.

So close, and yet so far away: The dichotomy of the specific immune response and inflammation in psoriasis and atopic dermatitis

Characterization of the complex interplay between cytokines, chemokines and microorganisms has led to a better understanding of the pathogenesis of both psoriasis and AD and resulted in new therapeutics targeting distinct immune responses. Psoriasis and AD share many characteristics: they are highly prevalent, chronic, cause primarily skin inflammation, but are associated with comorbidities, and come with a devastating quality of life due to itch and stigmatization. However, the pathogenesis of psoriasis and AD is opposing - psoriasis is dominated by a Th17 immune response that causes neutrophil migration, induction of innate immunity and exaggerated epithelial metabolism. Leading cytokines of this Th17 immune response are IL-17A and F, IL-22 and TNF-a. AD is characterized by Th2 immunity characterized by the signature cytokines IL-4 and IL-13 leading to an impaired epidermal barrier, dampened innate immunity and eosinophil migration. This review compares genetics, microbiome and T-cell infiltrate and resulting epithelial response in psoriasis and AD. Whilst the antagonistic course of psoriasis and AD is confirmed by response to specific biologics targeting the key cytokines of inflammation in psoriasis and AD, respectively, clinically overlapping phenotypes are challenging in our daily clinical practice. We conclude this review by summarizing what is known about these mixed phenotypes and how the identification of clinically relevant endotypes and molecular-driven decision-making is the next step in the field of dermato-immunology.

Association of the NOS3 Gene Polymorphisms with the Risk of Atopic Dermatitis in Children

We studied association of polymorphic markers Glu298Asp (rs1799983), C774T (rs1549758), and T786C (rs2070744) of the NOS3 gene with the risk of atopic dermatitis. It was found that T786C polymorphic marker of the NOS3 gene is associated with lower risk of erythematosquamous lichenoid atopic dermatitis. A significant association between the homozygous CC genotype in locus 786 of the NOS3 gene and the development of erythematosquamous atopic dermatitis with lichenification was revealed. The homozygous CC genotype can be considered as a risk factor of erythematosquamous atopic dermatitis with lichenification.

[Molecular diagnostics of hand eczema]

BACKGROUND

Using current diagnostic tools for hand eczema, namely clinical picture and histology, differential diagnoses such as psoriasis palmaris usually cannot be ruled out.

OBJECTIVES

Discussion of current diagnostic possibilities for hand eczema; presentation and critical evaluation of proposed biomarkers for molecular diagnostics and outlook how diagnostics in dermatology will change in the near future.

MATERIALS AND METHODS

In this article, we discuss basic research and provide a review of the literature.

RESULTS

Molecular diagnostics has the potential to substantially improve diagnosis of hand eczema; prerequisites are prospective validation of proposed markers and availability of valid and cost-effective diagnostics.

CONCLUSIONS

In the near future, the diagnosis of hand eczema will be complemented by software algorithms and artificial intelligence on the one hand and simple, precise, and economic molecular diagnostic devices on the other.

Contribution of diminished kidney transplant GFR to increased circulating chemokine ligand 27 level

Background

Inflammatory chemokine ligands (CCLs) play an important role in cardiovascular disease and allograft injury. CCLs may independently associate with diminished estimated glomerular filtration rate (eGFR) in stable renal transplant recipients (RTR).

Methods

Plasma levels of 19 CCLs (1, 2, 3, 4, 5, 8, 11, 13, 15, 17, 21, 24, 26, 27, CXCL5, 8, 10, 12 and 13) were measured in a cohort of 101 RTR. The cohort was divided according to CKD-EPI equation into three groups; group 1: eGFR ≥ 60 ml/min, group 2: eGFR 30–59.9 ml/min and group 3 eGFR ≤ 29.9 ml/min. ANOVA, Krusklwallis, Mann- Whitney Spearman correlation and regression analysis tests were used to determine association between reduced eGFR and inflammatory CCLs plasma levels measured by multiplex techniques. 20 healthy subjects with eGFR above 90 ml/min were included as control. Significance was sat at < 0.05.

Results

Levels of CCLs 1, 4, 15, 27, CXCL8 and CXCL10 were significantly different among the four studied groups. Multivariate regression analysis (MVA) between eGFR and all CCLs demonstrated that CCL27 was the only ligand to remain significantly associated with diminished eGFR {P = 0.021 and r = − 0.35,(P = 0.001)}. In a second MVA between CCL 27 and patient’s demographics and laboratory variables, diminished eGFR, and elevated PTH, out of the twenty one available variables remained significantly associated with elevated CCL27levels.

Conclusion

Diminished eGFR in stable RTR is associated with elevated plasma levels of CCL27. This association may explain, at least in part, the independent contribution of reduced eGFR to enhanced inflammation in RTR.

Early-onset pediatric atopic dermatitis is characterized by TH2/TH17/TH22-centered inflammation and lipid alterations

BACKGROUND

Although atopic dermatitis (AD) often starts in early childhood, detailed tissue profiling of early-onset AD in children is lacking, hindering therapeutic development for this patient population with a particularly high unmet need for better treatments.

OBJECTIVE

We sought to globally profile the skin of infants with AD compared with that of adults with AD and healthy control subjects.

METHODS

We performed microarray, RT-PCR, and fluorescence microscopy studies in infants and young children (<5 years old) with early-onset AD (<6 months disease duration) compared with age-matched control subjects and adults with longstanding AD.

RESULTS

Transcriptomic analyses revealed profound differences between pediatric patients with early-onset versus adult patients with longstanding AD in not only lesional but also nonlesional tissues. Although both patient populations harbored TH2-centered inflammation, pediatric AD also showed significant TH17/TH22 skewing but lacked the TH1 upregulation that characterizes adult AD. Pediatric AD exhibited relatively normal expression of epidermal differentiation and cornification products, which is downregulated in adults with AD. Defects in the lipid barrier (eg, ELOVL fatty acid elongase 3 [ELOVL3] and diacylglycerol o-acyltransferase 2 [DGAT2]) and tight junction regulation (eg, claudins 8 and 23) were evident in both groups. However, some lipid-associated mediators (eg, fatty acyl-CoA reductase 2 and fatty acid 2-hydroxylase) showed preferential downregulation in pediatric AD, and lipid barrier genes (FA2H and DGAT2) showed inverse correlations with transepidermal water loss, a functional measure of the epidermal barrier.

CONCLUSIONS

Skin samples from children and adult patients with AD share lipid metabolism and tight junction alterations, but epidermal differentiation complex defects are only present in adult AD, potentially resulting from chronic immune aberration that is not yet present in early-onset disease.

Analysis of anti-tumour necrosis factor-induced skin lesions reveals strong T helper 1 activation with some distinct immunological characteristics

BACKGROUND

Psoriasiform and eczematous eruptions are the most common dermatological adverse reactions linked to anti-tumour necrosis factor (TNF)-α therapy. Yet, a detailed characterization of their immune phenotype is lacking.

OBJECTIVES

To characterize anti-TNF-α-induced inflammatory skin lesions at a histopathological, cellular and molecular level, compared with psoriasis, eczema (atopic dermatitis) and healthy control skin.

METHODS

Histopathological evaluation, gene expression (quantitative real-time polymerase chain reaction) and computer-assisted immunohistological studies (TissueFAXS) were performed on 19 skin biopsies from patients with inflammatory bowel disease (n = 17) and rheumatoid arthritis (n = 2) with new-onset inflammatory skin lesions during anti-TNF-α-therapy.

RESULTS

Although most biopsies showed a psoriasiform and/or spongiotic (eczematous) histopathological architecture, these lesions were inconsistent with either psoriasis or eczema on a molecular level using an established chemokine (C-C motif) ligand 27/inducible nitric oxide synthase classifier. Despite some differences in immune skewing depending on the specific histopathological reaction pattern, all anti-TNF-α-induced lesions showed strong interferon (IFN)-γ activation, at higher levels than in psoriasis or eczema. IFN-γ was most likely produced by CD3/CD4/Tbet-positive T helper 1 lymphocytes.

CONCLUSIONS

New-onset anti-TNF-α-induced eruptions previously classified as psoriasis or spongiotic dermatitis (eczema) exhibit a molecular profile that is different from either of these disorders.

Molecular diagnostics of inflammatory disease: New tools and perspectives

This essay reviews current approaches to establish novel molecular diagnostic tools for inflammatory skin diseases. Moreover, it highlights the importance of stratifying patients according to molecular signatures and revising current outdated disease classification systems to eventually reach the goal of personalized medicine.

The Inflammatory Response in Psoriasis: a Comprehensive Review

Psoriasis is a chronic inflammatory autoimmune disease characterized by an excessively aberrant hyperproliferation of keratinocytes. The pathogenesis of psoriasis is complex and the exact mechanism remains elusive. However, psoriasis is thought to result from a combination of genetic, epigenetic, and environmental influences. Recent studies have identified that epigenetic factors including dysregulated DNA methylation levels, abnormal histone modification and microRNAs expressions are involved in the development of psoriasis. The interplay of immune cells and cytokines is another critical factor in the pathogenesis of psoriasis. These factors or pathways include Th1/Th2 homeostasis, the Th17/Treg balance and the IL-23/Th17 axis. Th17 is believed particularly important in psoriasis due to its pro-inflammatory effects and its involvement in an integrated inflammatory loop with dendritic cells and keratinocytes, contributing to an overproduction of antimicrobial peptides, inflammatory cytokines, and chemokines that leads to amplification of the immune response. In addition, other pathways and signaling molecules have been found to be involved, including Th9, Th22, regulatory T cells, γδ T cells, CD8(+) T cells, and their related cytokines. Understanding the pathogenesis of psoriasis will allow us to develop increasingly efficient targeted treatment by blocking relevant inflammatory signaling pathways and molecules. There is no cure for psoriasis at the present time, and much of the treatment involves managing the symptoms. The biologics, while lacking the adverse effects associated with some of the traditional medications such as corticosteroids and methotrexate, have their own set of side effects, which may include reactivation of latent infections. Significant challenges remain in developing safe and efficacious novel targeted therapies that depend on a better understanding of the immunological dysfunction in psoriasis.

John J, Xavier RJ, Yajnik V, Ananthakrishnan AN. Genetic basis of TNF-α antagonist associated psoriasis in inflammatory bowel diseases: a genotype-phenotype analysis

BACKGROUND

Anti-tumour necrosis factor (anti-TNF) biologic associated psoriasis has been reported in inflammatory bowel disease (IBD) patients. However, little is known regarding its pathogenesis.

AIM

To identify potential genetic predispositions to anti-TNF associated psoriasis in IBD patients.

METHODS

This retrospective chart review included IBD patients enrolled in a prospective registry. Cases of anti-TNF associated psoriasis and idiopathic psoriasis unrelated to anti-TNF exposure were confirmed by an expert dermatologist. All patients were genotyped on the Illumina Immunochip. A weighted genetic risk score ascertaining genetic pre-disposition towards psoriasis was calculated and overall genetic pre-disposition as well as differential distribution of individual polymorphisms was compared across the three groups.

RESULTS

Our study included 724 IBD patients who initiated anti-TNF therapy and did not develop psoriasis, 35 patients with anti-TNF associated psoriasis, and 38 patients with idiopathic psoriasis. Anti-TNF users who developed psoriasis had a modest but statistically significantly greater psoriasis genetic risk score than anti-TNF controls (mean 0.64 vs. 0.61, P = 0.04), and had a similar genetic risk score as those with idiopathic psoriasis (0.64 vs. 0.62, P = 0.22). Two loci associated with NOS2 and ETS1 genes achieved P < 0.05 when comparing anti-TNF associated psoriasis to anti-TNF controls. Three loci were significantly different between anti-TNF associated psoriasis and idiopathic psoriasis including a polymorphism near NOS2 encoding for inducible nitric oxide synthase that is produced by dendritic cells in skin lesions in psoriasis.

CONCLUSION

Patients with anti-TNF associated psoriasis had a modestly greater genetic pre-disposition towards psoriasis but no single causative polymorphism was identified.

Dissecting susceptibility from exogenous triggers: the model of alopecia areata and associated inflammatory skin diseases

BACKGROUND

Alopecia areata (AA) is a T-cell-driven autoimmune disease of the hair follicle and frequently reported to be associated with inflammatory skin diseases (ISD) such as atopic eczema (AE) or psoriasis. Interestingly, AA on the one hand and both AE and psoriasis on the other hand are believed to be driven by mutually antagonistic T-cell subsets.

OBJECTIVE

To characterize AA-specific T-cell profiles and inflammatory pattern by intra-individual comparison of AA and coexistent ISD.

METHODS

112 patients with AA were recruited and investigated for coexisting ISD. In-depth analyses were performed in patients with AA and AE (n = 2), AA and psoriasis (n = 1), AA and psoriasis and AE (n = 1) and AA and lichen planus (n = 1), using histology, immunohistochemistry and cytokine staining of T cells isolated from lesional skin.

RESULTS

Of 112 AA patients investigated, 23 suffered from an ISD. The prevalence of AE, vitiligo, psoriasis and lichen planus was higher in the investigated AA cohort than in the normal population. The clinical as well as histological phenotype of AA the coexistent ISD were unequivocal. In line with this, T-cell infiltrates were found to be disease-characteristics with AA and lichen planus dominated by CD8+ and IFN-γ+ TNF-α+ producing T cells while psoriasis lesions in the same patients were dominated by IL-17+ and AE by IL-4+ T cells.

CONCLUSION

AA patients have a higher incidence of various T-cell-driven inflammatory skin diseases than the normal population, a phenomenon which might relate to over-activation of skin-homing T cells and to specific immune triggers as the primary cause of inflammation. More importantly, we showed that by using AA as a model disease, our approach of intra-individual comparison of distinct inflammatory responses in the same patient is feasible and offers the unique possibility to gain insights into disease pathogenesis independent from genetic susceptibilities.