Benjamin Ungar

The Asian atopic dermatitis phenotype combines features of atopic dermatitis and psoriasis with increased TH17 polarization

BACKGROUND Atopic dermatitis (AD) shows very high prevalence in Asia, with a large unmet need for effective therapeutics. Direct comparisons between European American (EA) and Asian patients with AD are unavailable, but earlier blood studies detected increased IL-17(+)-producing cell counts in Asian patients with AD. OBJECTIVE We sought to characterize the Asian AD skin phenotype and compare it with the EA AD skin phenotype. METHODS We performed genomic profiling (real-time PCR) and immunohistochemistry on lesional and nonlesional biopsy specimens from 52 patients with AD (25 EAs and 27 Asians), 10 patients with psoriasis (all EAs), and 27 healthy subjects (12 EAs and 15 Asians). RESULTS Although disease severity/SCORAD scores were similar between the AD groups (58.0 vs 56.7, P = .77), greater acanthosis, higher Ki67 counts, and frequent parakeratosis were characteristics of lesional epidermis from Asian patients with AD (P < .05). Most (24/27) Asian patients had high IgE levels. A principal component analysis using real-time PCR data clustered the Asian AD phenotype between the EA AD and psoriasis phenotypes. TH2 skewing characterized both Asian and EA patients with AD but not patients with psoriasis. Significantly higher TH17 and TH22 (IL17A, IL19, and S100A12 in lesional and IL-22 in nonlesional skin; P < .05) and lower TH1/interferon (CXCL9, CXCL10, MX1, and IFNG in nonlesional skin; P < .05) gene induction typified AD skin in Asian patients. CONCLUSION The Asian AD phenotype presents (even in the presence of increased IgE levels) a blended phenotype between that of EA patients with AD and those with psoriasis, including increased hyperplasia, parakeratosis, higher TH17 activation, and a strong TH2 component. The relative pathogenic contributions of the TH17 and TH2 axes in creating the Asian AD phenotype need to be tested in future clinical trials with appropriate targeted therapeutics.

Identification of novel immune and barrier genes in atopic dermatitis by means of laser capture microdissection

BACKGROUND The molecular signature of atopic dermatitis (AD) lesions is associated with TH2 and TH22 activation and epidermal alterations. However, the epidermal and dermal AD transcriptomes and their respective contributions to abnormalities in respective immune and barrier phenotypes are unknown. OBJECTIVE We sought to establish the genomic profile of the epidermal and dermal compartments of lesional and nonlesional AD skin compared with normal skin. METHODS Laser capture microdissection was performed to separate the epidermis and dermis of lesional and nonlesional skin from patients with AD and normal skin from healthy volunteers, followed by gene expression (microarrays and real-time PCR) and immunostaining studies. RESULTS Our study identified novel immune and barrier genes, including the IL-34 cytokine and claudins 4 and 8, and showed increased detection of key AD genes usually undetectable on arrays (ie, IL22, thymic stromal lymphopoietin [TSLP], CCL22, and CCL26). Overall, the combined epidermal and dermal transcriptomes enlarged the AD transcriptome, adding 674 upregulated and 405 downregulated differentially expressed genes between lesional and nonlesional skin to the AD transcriptome. We were also able to localize individual transcripts as primarily epidermal (defensin, beta 4A [DEFB4A]) or dermal (IL22, cytotoxic T-lymphocyte antigen 4 [CTLA4], and CCR7) and link their expressions to possible cellular sources. CONCLUSIONS This is the first report that establishes robust epidermal and dermal genomic signatures of lesional and nonlesional AD skin and normal skin compared with whole tissues. These data establish the utility of laser capture microdissection to separate different compartments and cellular subsets in patients with AD, allowing localization of key barrier or immune molecules and enabling detection of gene products usually not detected on arrays.

Alopecia areata profiling shows TH1, TH2, and IL-23 cytokine activation without parallel TH17/TH22 skewing

BACKGROUND Alopecia areata (AA) is a common T cell-mediated disorder with limited therapeutics. A molecular profile of cytokine pathways in AA tissues is lacking. Although studies have focused on TH1/IFN-γ responses, several observations support a shared genetic background between AA and atopy. OBJECTIVE We sought to define the AA scalp transcriptome and associated biomarkers with comparisons with atopic dermatitis (AD) and psoriasis. METHODS We performed microarray and RT-PCR profiling of 27 lesional and 17 nonlesional scalp samples from patients with AA for comparison with normal scalp samples (n = 6). AA gene expression was also compared with samples from patients with lesional or nonlesional AD and those with psoriasis. A fold change of greater than 1.5 and a false discovery rate of less than 0.05 were used for differentially expressed genes (DEGs). RESULTS We established the AA transcriptomes (lesional vs nonlesional: 734 DEGs [297 upregulated and 437 downregulated]; lesional vs normal: 4230 DEGs [1980 upregulated and 2250 downregulated]), including many upregulated immune and downregulated hair keratin genes. Equally impressive as upregulation in TH1/interferon markers (IFNG and CXCL10/CXCL9) were those noted in TH2 (IL13, CCL18, CCL26, thymic stromal lymphopoietin, and periostin), TH9/IL-9, IL-23 (p40 and p19), and IL-16 mediators (all P < .05). There were no increases in TH17/TH22 markers. Hair keratin (KRT) expressions (ie, KRT86 and KRT85) were significantly suppressed in lesional skin. Greater scalp involvement (>25%) was associated with greater immune and keratin dysregulation and larger abnormalities in nonlesional scalp samples (ie, CXCL10 and KRT85). CONCLUSIONS Our data associate the AA signature with TH2, TH1, IL-23, and IL-9/TH9 cytokine activation, suggesting consideration of anti-TH2, anti-TH1, and anti-IL-23 targeting strategies. Similar to psoriasis and AD, clinical trials with selective antagonists are required to dissect key pathogenic pathways.

Drug evaluation review: dupilumab in atopic dermatitis

Atopic dermatitis (AD) is characterized by type 2 helper T (Th2) cell-driven inflammation. Dupilumab is a fully human monoclonal antibody directed against the IL-4 receptor α subunit that blocks the signaling of IL-4 and IL-13, both key cytokines in Th2-mediated pathways. In Phase I and II studies of adults with moderate-to-severe AD, dupilumab administered as monotherapy or with topical corticosteroids resulted in rapid, significant improvements in clinical efficacy, patient-reported outcomes, and Th2-related serum and tissue biomarkers, and shifted the RNA expression profile of lesional skin to a more nonlesional signature. In all clinical studies to date, dupilumab has shown a favorable safety profile with no dose-limiting toxicity. The robust effects of dupilumab on skin inflammation and pruritus confirm the pathogenic role of IL-4 and IL-13 signaling in adult AD, and further support the application of Th2 cytokine antagonists in the treatment of this disease.

An Integrated Model of Atopic Dermatitis Biomarkers Highlights the Systemic Nature of the Disease

Current atopic dermatitis (AD) models link epidermal abnormalities in lesional skin to cytokine activation. However, there is evolving evidence of systemic immune activation and detectable abnormalities in nonlesional skin. Because some of the best single correlations with severity (Scoring of AD, or SCORAD) are detected not only in lesional but also nonlesional skin and blood, more complex biomarker models of AD are needed. We thus performed extensive biomarker measures in these compartments using univariate and multivariate approaches to correlate disease biomarkers with SCORAD and with a combined hyperplasia score [thickness and keratin 16 (K16) mRNA] at baseline and after cyclosporine A treatment in 25 moderate to severe AD patients. Increases in serum cytokines and chemokines (IL-13, IL-22, CCL17) were found in AD versus healthy individuals and were reduced with treatment. SCORAD correlated with immune (IL-13, IL-22) and epidermal (thickness, K16) measures in lesional and, even more strongly, in nonlesional AD. Serum cytokines also had higher correlations with nonlesional markers at baseline and with treatment. Multivariate U statistics improved baseline and treatment-response SCORAD correlations. Nonlesional models showed the strongest correlations, with further improvement upon integration of serum markers. Even better correlations were obtained between biomarkers and the hyperplasia score. Larger cohorts are needed to confirm these preliminary data.

Patients with atopic dermatitis have attenuated and distinct contact hypersensitivity responses to common allergens in skin

BACKGROUND Atopic dermatitis (AD) is the most common inflammatory disease. The prevalence of allergic contact dermatitis to allergens (eg, fragrance) is higher in patients with AD, despite a trend toward weaker clinical allergic contact dermatitis reactions. The role of the AD skin phenotype in modulating allergic sensitization to common sensitizers has not been evaluated. OBJECTIVE We sought to investigate whether patients with AD have altered tissue immune responses on allergen challenge. METHODS Gene expression and immunohistochemistry studies were performed on biopsy specimens from 10 patients with AD and 14 patients without AD patch tested with common contact allergens (nickel, fragrance, and rubber). RESULTS Although 1085 differentially expressed genes (DEGs) were commonly modulated in patch-tested skin from patients with AD and patients without AD versus control skin, 1185 DEGs were uniquely altered in skin from patients without AD, and only 246 DEGs were altered in skin from patients with AD. Although many inflammatory products (ie, matrix metalloproteinase 12/matrix metalloproteinase 1/S100A9) were upregulated in both groups, higher-magnitude changes and upregulation of interferon responses were evident only in the non-AD group. Stratification by allergen showed decreased expression of immune, TH1-subset, and TH2-subset genes in nickel-related AD responses, with increased TH17/IL-23 skewing. Rubber/fragrance showed similar trends of lesser magnitude. Negative regulators showed higher expression in patients with AD. CONCLUSIONS Through contact sensitization, our study offers new insights into AD. Allergic immune reactions were globally attenuated and differentially polarized in patients with AD, with significant decreases in levels of TH1 products, some increases in levels of TH17 products, and inconsistent upregulation in levels of TH2 products. The overall hyporesponsiveness in skin from patients with background AD might be explained by baseline immune abnormalities, such as increased TH2, TH17, and negative regulator levels compared with those seen in non-AD skin.

An IL-17–dominant immune profile is shared across the major orphan forms of ichthyosis

Background: The ichthyoses are rare genetic disorders associated with generalized scaling, erythema, and epidermal barrier impairment. Pathogenesis‐based therapy is largely lacking because the underlying molecular basis is poorly understood. Objective: We sought to characterize molecularly cutaneous inflammation and its correlation with clinical and barrier characteristics. Methods: We analyzed biopsy specimens from 21 genotyped patients with ichthyosis (congenital ichthyosiform erythroderma, n = 6; lamellar ichthyosis, n = 7; epidermolytic ichthyosis, n = 5; and Netherton syndrome, n = 3) using immunohistochemistry and RT‐PCR and compared them with specimens from healthy control subjects, patients with atopic dermatitis (AD), and patients with psoriasis. Clinical measures included the Ichthyosis Area Severity Index (IASI), which integrates erythema (IASI‐E) and scaling (IASI‐S); transepidermal water loss; and pruritus. Results: Ichthyosis samples showed increased epidermal hyperplasia (increased thickness and keratin 16 expression) and T‐cell and dendritic cell infiltrates. Increases of general inflammatory (IL‐2), innate (IL‐1&bgr;), and some TH1/interferon (IFN‐&ggr;) markers in patients with ichthyosis were comparable with those in patients with psoriasis or AD. TNF‐&agr; levels in patients with ichthyosis were increased only in those with Netherton syndrome but were much lower than in patients with psoriasis and those with AD. Expression of TH2 cytokines (IL‐13 and IL‐31) was similar to that seen in control subjects. The striking induction of IL‐17–related genes or markers synergistically induced by IL‐17 and TNF‐&agr; (IL‐17A/C, IL‐19, CXCL1, PI3, CCL20, and IL36G; P < .05) in patients with ichthyosis was similar to that seen in patients with psoriasis. IASI and IASI‐E scores strongly correlated with IL‐17A (r = 0.74, P < .001) and IL‐17/TNF–synergistic/additive gene expression. These markers also significantly correlated with transepidermal water loss, suggesting a link between the barrier defect and inflammation in patients with ichthyosis. Conclusion: Our data associate a shared TH17/IL‐23 immune fingerprint with the major orphan forms of ichthyosis and raise the possibility of IL‐17–targeting strategies.

Dust mite induces multiple polar T cell axes in human skin

House dust mite/HDM atopy patch test/APT elicits positive reactions in a high fraction of atopic dermatitis/AD and healthy individuals. Experimental systems for new‐onset/chronic AD are needed to support rapid therapeutic development, particularly since animal models representing human AD are lacking. While HDM APT has been considered to simulate AD, its suitability to model ADs emerging Th2/Th22 phenotype with Th1 and Th17 components is unknown.

Dupilumab progressively improves systemic and cutaneous abnormalities in atopic dermatitis patients

Background: Dupilumab is an IL‐4 receptor &agr; mAb inhibiting signaling of IL‐4 and IL‐13, key drivers of type 2–driven inflammation, as demonstrated by its efficacy in patients with atopic/allergic diseases. Objective: This placebo‐controlled, double‐blind trial (NCT01979016) evaluated the efficacy, safety, and effects of dupilumab on molecular/cellular lesional and nonlesional skin phenotypes and systemic type 2 biomarkers of patients with moderate‐to‐severe atopic dermatitis (AD). Methods: Skin biopsy specimens and blood were evaluated from 54 patients randomized 1:1 to weekly subcutaneous doses of 200 mg of dupilumab or placebo for 16 weeks. Results: Dupilumab (vs placebo) significantly improved clinical signs and symptoms of AD, was well tolerated, and progressively shifted the lesional transcriptome toward a nonlesional phenotype (weeks 4–16). Mean improvements in a meta‐analysis–derived AD transcriptome (genes differentially expressed between lesional and nonlesional skin) were 68.8% and 110.8% with dupilumab and −10.5% and 55.0% with placebo (weeks 4 and 16, respectively; P < .001). Dupilumab significantly reduced expression of genes involved in type 2 inflammation (IL13, IL31, CCL17, CCL18, and CCL26), epidermal hyperplasia (keratin 16 [K16] and MKi67), T cells, dendritic cells (ICOS, CD11c, and CTLA4), and TH17/TH22 activity (IL17A, IL‐22, and S100As) and concurrently increased expression of epidermal differentiation, barrier, and lipid metabolism genes (filaggrin [FLG], loricrin [LOR], claudins, and ELOVL3). Dupilumab reduced lesional epidermal thickness versus placebo (week 4, P = .001; week 16, P = .0002). Improvements in clinical and histologic measures correlated significantly with modulation of gene expression. Dupilumab also significantly suppressed type 2 serum biomarkers, including CCL17, CCL18, periostin, and total and allergen‐specific IgEs. Conclusion: Dupilumab‐mediated inhibition of IL‐4/IL‐13 signaling through IL‐4 receptor &agr; blockade significantly and progressively improved disease activity, suppressed cellular/molecular cutaneous markers of inflammation and systemic measures of type 2 inflammation, and reversed AD‐associated epidermal abnormalities.