CLA+ memory T cells in atopic dermatitis: CLA+ T cells and atopic dermatitis.

Circulating skin-homing cutaneous lymphocyte-associated antigen (CLA)+ T cells constitute a small subset of human memory T cells involved in several aspects of atopic dermatitis: Staphylococcus aureus related mechanisms, the abnormal Th2 immune response, biomarkers, clinical aspects of the patients, pruritus, and the mechanism of action of targeted therapies. Superantigens, IL-13, IL-31, pruritus, CCL17 and early effects on dupilumab-treated patients have in common that they are associated with the CLA+ T cell mechanisms in atopic dermatitis patients. The function of CLA+ T cells corresponds with the role of T cells belonging to the skin-associated lymphoid tissue and could be a reason why they reflect different mechanisms of atopic dermatitis and many other T cell mediated skin diseases. The goal of this review is to gather all this translational information of atopic dermatitis pathology.

The erythema Q-score, an imaging biomarker for redness in skin inflammation.

Physician rating of cutaneous erythema is central to clinical dermatological assessment as well as quantification of outcome measures in clinical trials in a number of dermatologic conditions. However, issues with inter-rater reliability and variability in the setting of higher Fitzpatrick skin types make visual erythema assessment unreliable. We developed and validated a computer-assisted image-processing algorithm (EQscore) to reliably quantify erythema (across a range of skin types) in the dermatology clinical setting. Our image processing algorithm evaluated erythema based upon green light suppression differentials between affected and unaffected skin. A group of four dermatologists used a 4-point Likert scale as a human evaluation of similar erythematous patch tests. The algorithm and dermatologist scores were compared across 164 positive patch test reactions. The intra-class correlation coefficient of groups and the correlation coefficient between groups were calculated. The EQscore was validated on and independent image set of psoriasis, minimal erythema dose testing and steroid-induced blanching images. The reliability of the erythema quantification method produced an intra-class correlation coefficient of 0.84 for the algorithm and 0.67 for dermatologists. The correlation coefficient between groups was 0.85. The EQscore demonstrated high agreement with clinical scoring and superior reliability compared with clinical scoring, avoiding the pitfalls of erythema underrating in the setting of pigmentation. The EQscore is easily accessible (http://lab.rockefeller.edu/krueger/EQscore), user-friendly, and may allow dermatologists to more readily and accurately rate the severity of dermatological conditions and the response to therapeutic treatments.

High-dimensional analysis defines multicytokine T-cell subsets and supports a role for IL-21 in atopic dermatitis.

BACKGROUND: Flow cytometry is a well-accepted approach for immune profiling; however, its value is restricted by the limited number of markers that can be analyzed simultaneously. Mass cytometry/CyTOF offers broad-scale immune characterization integrating large number of parameters. While partial blood phenotyping was reported in atopic dermatitis (AD), patients' comprehensive profiling, critical for leveraging new targeted treatments, is not available. IL-21 may be involved in inflammatory skin diseases but its role in AD is not well established. METHODS: We studied T-cell polarization in the blood of 20 moderate-to-severe AD and 15 controls. Using CyTOF and an unsupervised analysis, we measured the frequencies and mean metal intensities of activated polar CD4+ /CD8+ T-cell subsets. Immunohistochemistry, immunofluorescence, and qRT-PCR were used to analyze skin samples. RESULTS: Examining 24 surface, intracellular markers, and transcription factors, we identified six CD4+ and five CD8+ T-cell metaclusters. A CD4+ skin-homing IL-13+ monocytokine and a novel IL-13+ IL-21+ multicytokine metaclusters were increased in AD vs. controls (p < .01). While IL-13 signature characterized both clusters, levels were significantly higher in the IL-21+ group. Both clusters correlated with AD severity (r = 0.49, p = .029). Manual gating corroborated these results and identified additional multicytokine subsets in AD. Immunohistochemistry and immunofluorescence, validated by mRNA expression, displayed significantly increasedIL-21 counts and colocalization with IL-13/IL-4R in AD skin. CONCLUSION: A multicytokine signature characterizes moderate-to-severe AD, possibly explaining partial therapeutic responses to one cytokine targeting, particularly in severe patients. Prominent IL-21 signature in blood and skin hints for a potential pathogenic role of IL-21 in AD.

Evolution of pathologic T-cell subsets in patients with atopic dermatitis from infancy to adulthood.

BACKGROUND: The circulating immune phenotype was defined in adults and young children with early atopic dermatitis (AD), but chronologic changes in the blood of infants and children with AD through adolescence have not been explored. OBJECTIVE: We sought to compare immune activation and cytokine polarization in the blood of 0- to 5-year-old (n = 39), 6- to 11-year-old (n = 26), 12- to 17-year-old (n = 21) and 18-year-old or older (n = 43) patients with AD versus age-matched control subjects. METHODS: Flow cytometry was used to measure IFN-γ, IL-9, IL-13, IL-17, and IL-22 cytokine levels in CD4+/CD8+ T cells, with inducible costimulator molecule and HLA-DR defining midterm and long-term T-cell activation, respectively, within skin-homing/cutaneous lymphocyte antigen (CLA)+ versus systemic/CLA- T cells. Unsupervised clustering differentiated patients based on their blood biomarker frequencies. RESULTS: Although CLA+ TH1 frequencies were significantly lower in infants with AD versus all older patients (P < .01), frequencies of CLA+ TH2 T cells were similarly expanded across all AD age groups compared with control subjects (P < .05). After infancy, CLA- TH2 frequencies were increased in patients with AD in all age groups, suggesting systemic immune activation with disease chronicity. IL-22 frequencies serially increased from normal levels in infants to highly significant levels in adolescents and adults compared with levels in respective control subjects (P < .01). Unsupervised clustering aligned the AD profiles along an age-related spectrum from infancy to adulthood (eg, inducible costimulator molecule and IL-22). CONCLUSIONS: The adult AD phenotype is achieved only in adulthood. Unique cytokine signatures characterizing individual pediatric endotypes might require age-specific therapies. Future longitudinal studies, comparing the profile of patients with cleared versus persistent pediatric AD, might define age-specific changes that predict AD clearance.

Atopic dermatitis endotypes and implications for targeted therapeutics.

Recent research advancements indicate that atopic dermatitis (AD) is a complex disease characterized by different subtypes/phenotypes based on age, disease chronicity, ethnicity, filaggrin and IgE status, and underlying molecular mechanisms/endotypes. This heterogeneity advocates against the traditional "one-size-fits-all" therapeutic approaches still used to manage AD. Precision medicine approaches, striving for targeted, tailored, endotype-driven disease prevention and treatment, rely on detailed definitions of the disease's variability across different phenotypes. Studies have shown that AD harbors different endotypes across different age groups and ethnicities and according to IgE levels and filaggrin mutation status. These include European American versus Asian patients, children versus adults, intrinsic versus extrinsic (IgE status) disease, and patients with and without filaggrin mutations. Therapies targeting different cytokine axes and other mechanisms involved in disease pathogenesis, which are currently being tested for patients with AD across the disease spectrum, will expand our ability to dissect the relative contribution of each of these pathways to disease perpetuation.

Ichthyosis molecular fingerprinting shows profound TH17 skewing and a unique barrier genomic signature.

BACKGROUND: Ichthyoses are a group of rare skin disorders lacking effective treatments. Although genetic mutations are progressively delineated, comprehensive molecular phenotyping of ichthyotic skin could suggest much-needed pathogenesis-based therapy. OBJECTIVE: We sought to profile the molecular fingerprint of the most common orphan ichthyoses. METHODS: Gene, protein, and serum studies were performed on skin and blood samples from 29 patients (congenital ichthyosiform erythroderma, n = 9; lamellar ichthyosis, n = 8; epidermolytic ichthyosis, n = 8; and Netherton syndrome, n = 4), as well as age-matched healthy control subjects (n = 14), patients with psoriasis (n = 30), and patients with atopic dermatitis (AD; n = 16). RESULTS: Using criteria of a fold change of greater than 2 and a false discovery rate of less than 0.05, 132 differentially expressed genes were shared commonly among all ichthyoses, including many IL-17 and TNF-α-coregulated genes, which are considered hallmarks of psoriasis (defensin beta 4A, kynureninase, and vanin 3). Although striking upregulation of TH17 pathway genes (IL17F and IL36B/G) resembling that seen in patients with psoriasis was common to all patients with ichthyoses in a severity-related manner, patients with Netherton syndrome showed the greatest T-cell activation (inducible costimulator [ICOS]) and a broader immune phenotype with TH1/IFN-γ, OASL, and TH2/IL-4 receptor/IL-5 skewing, although less than seen in patients with AD (all P < .05). Ichthyoses lacked the epidermal differentiation and tight junction alterations of patients with AD (loricrin, filaggrin, and claudin 1) but showed characteristic alterations in lipid metabolism genes (ELOVL fatty acid elongase 3 and galanin), with parallel reductions in extracellular lipids and corneocyte compaction in all ichthyoses except epidermolytic ichthyosis, suggesting phenotypic variations. Transepidermal water loss, a functional barrier measure, significantly correlated with IL-17-regulated gene expression (IL17F and IL36A/IL36B/IL36G). CONCLUSION: Similar to patients with AD and psoriasis, in whom cytokine dysregulation and barrier impairment orchestrate disease phenotypes, psoriasis-like immune dysregulation and lipid alterations characterize the ichthyoses. These data support the testing of IL-17/IL-36-targeted therapeutics for patients with ichthyosis similar to those used in patients with psoriasis.

Blood endotyping distinguishes the profile of vitiligo from that of other inflammatory and autoimmune skin diseases.

BACKGROUND: Peripheral blood skin-homing/cutaneous lymphocyte antigen (CLA)+ T cells emerge as biomarkers of cutaneous immune activation in patients with inflammatory skin diseases (atopic dermatitis [AD] and alopecia areata [AA]). However, blood phenotyping across these subsets is not yet available in patients with vitiligo. OBJECTIVE: We sought to measure cytokine production by circulating skin-homing (CLA+) versus systemic (CLA-) "polar" CD4+/CD8+ ratio and activated T-cell subsets in patients with vitiligo compared with patients with AA, AD, or psoriasis and control subjects. METHODS: Flow cytometry was used to measure levels of the cytokines IFN-γ, IL-13, IL-9, IL-17, and IL-22 in CD4+/CD8+ T cells in the blood of 19 patients with moderate-to-severe nonsegmental/generalized vitiligo, moderate-to-severe AA (n = 32), psoriasis (n = 24), or AD (n = 43) and control subjects (n = 30). Unsupervised clustering differentiated subjects into groups based on cellular frequencies. RESULTS: Patients with Vitiligo showed the highest CLA+/CLA- TH1/type 1 cytotoxic T-cell polarization, with parallel TH2/TH9/TH17/TH22 level increases to levels often greater than those seen in patients with AA, AD, or psoriasis (P < .05). Total regulatory T-cell counts were lower in patients with vitiligo than in control subjects and patients with AD or psoriasis (P < .001). Vitiligo severity correlated with levels of multiple cytokines (P < .1), whereas duration was linked with IFN-γ and IL-17 levels (P < .04). Patients and control subjects grouped into separate clusters based on blood biomarkers. CONCLUSIONS: Vitiligo is characterized by a multicytokine polarization among circulating skin-homing and systemic subsets, which differentiates it from other inflammatory/autoimmune skin diseases. Future targeted therapies should delineate the relative contribution of each cytokine axis to disease perpetuation.

Distinct transcriptomic profiles of early-onset atopic dermatitis in blood and skin of pediatric patients.

BACKGROUND: Atopic dermatitis (AD) predominantly affects young children, but our understanding of AD pathogenesis is based on skin and blood samples from long-standing adult AD. Genomic biopsy profiling from early pediatric AD showed significant Th2 and Th17/Th22-skewing, without the characteristic adult Th1 up-regulation. Because obtaining pediatric biopsies is difficult, blood gene expression profiling may provide a surrogate for the pediatric skin signature. OBJECTIVE: To define the blood profile and associated biomarkers of early moderate-to-severe pediatric AD. METHODS: We compared microarrays and reverse transcription polymerase chain reaction (RT-PCR) of blood cells from 28 AD children (<5 years and within 6 months of disease onset) to healthy control blood cells. Differentially expressed genes (DEGs) in blood (fold change [FCH] > 1.2 and false discovery rate [FDR] < 0.05) were then compared with skin DEGs. RESULTS: Eosinophil and Th2 markers (IL5RA, IL1RL1/ST2, HRH4, CCR3, SIGLEC8, PRSS33, CLC from gene arrays; IL13/IL4/CCL22 from RT-PCR) were up-regulated in early pediatric AD blood, whereas IFNG/Th1 was decreased. Th1 markers were negatively correlated with clinical severity (EASI, pruritus, transepidermal water loss [TEWL]), whereas Th2/Th17-induced interleukin (IL)-19 was positively correlated with SCORAD. Although a few RT-PCR-defined immune markers (IL-13/CCL22) were increased in blood, as previously also reported for skin, minimal overlap based on gene array DEGs was seen. CONCLUSION: The whole blood signature of early moderate-to-severe pediatric AD blood cells show predominantly a Th2/eosinophil profile; however, markers largely differ from the skin profile. Given their complementarity, pooling of biomarkers from blood and skin may improve profiling and predictions, providing insight regarding disease course, allergic comorbidity development, and response to systemic medications.

The blood proteomic signature of early-onset pediatric atopic dermatitis shows systemic inflammation and is distinct from adult long-standing disease.

BACKGROUND: Despite increasing evidence that adults with long-standing atopic dermatitis (AD) have systemic inflammation, little is known about systemic inflammation in recent-onset early pediatric AD. OBJECTIVE: To analyze blood inflammatory proteins of early pediatric AD. METHODS: Using high-throughput proteomics (proximity extension assay), we assessed 257 inflammatory and cardiovascular risk proteins in the blood of 30 children with moderate to severe AD younger than 5 years of age (within 6 months of onset) compared with age-matched pediatric control individuals and adult patients with AD. RESULTS: In pediatric AD blood, T helper (Th) type 2 (CCL13, CCL22) and Th17 (peptidase inhibitor-3/elafin) markers were increased, together with markers of tissue remodeling (matrix metalloproteinases 3/9/10, urokinase receptor), endothelial activation (E-selectin), T-cell activation (IL2RA), neutrophil activation (myeloperoxidase), lipid metabolism (FABP4), and growth factors (FGF21, transforming growth factor-α). Total numbers of dysregulated proteins were smaller in pediatric AD (n = 22) than in adult AD (n = 61). Clinical severity scores were positively correlated with receptors for interleukins 33 and 36 and inversely correlated with some Th1 markers (interferon gamma, CXCL11). LIMITATIONS: Different baseline expression levels in healthy pediatric vs adult samples. CONCLUSIONS: Within months of pediatric AD onset, systemic immune activation is present, with Th2/Th17 skewing but otherwise different proteomic patterns from adult AD. Future correlation of proteomic patterns with disease course, comorbidity development, and drug response may yield predictive biomarkers.

Effect of short-term liver X receptor activation on epidermal barrier features in mild to moderate atopic dermatitis: A randomized controlled trial.

BACKGROUND: Liver X receptors (LXRs) are involved in maintaining epidermal barrier and suppressing inflammatory responses in model systems. The LXR agonist VTP-38543 showed promising results in improving barrier function and inflammatory responses in model systems. OBJECTIVE: To assess the safety, tolerability, cellular and molecular changes, and clinical efficacy of the topical VTP-38543 in adults with mild to moderate atopic dermatitis (AD). METHODS: A total of 104 ambulatory patients with mild to moderate AD were enrolled in this randomized, double-blind, vehicle-controlled trial between December 2015 and September 2016. VTP-38543 cream in 3 concentrations (0.05%, 0.15%, and 1.0%) or placebo was applied twice daily for 28 days. Pretreatment and posttreatment skin biopsy specimens were obtained from a subset of 33 patients. Changes in SCORing of Atopic Dermatitis, Eczema Area and Severity Index, Investigator's Global Assessment, and tissue biomarkers (by real-time polymerase chain reaction and immunostaining) were evaluated. RESULTS: Topical VTP-38543 was safe and well tolerated. VTP-38543 significantly increased messenger RNA (mRNA) expression of epidermal barrier differentiation (loricrin and filaggrin, P = .02) and lipid (adenosine triphosphate-binding cassette subfamily G member 1 and sterol regulatory element binding protein 1c, P < .01) measures and reduced epidermal hyperplasia markers (thickness, keratin 16 mRNA). VTP-38543 nonsignificantly suppressed cellular infiltrates and down-regulated mRNA expression of several TH17/TH22-related (phosphatidylinositol 3, S100 calcium-binding protein A12) and innate immunity (interleukin 6) markers. CONCLUSION: Topical VTP-38543 is safe and well tolerated. Its application led to improvement in barrier differentiation and lipids. Longer-term studies are needed to clarify whether a barrier-based approach can induce meaningful suppression of immune abnormalities. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT02655679.

The spectrum of manifestations in desmoplakin gene (DSP) spectrin repeat 6 domain mutations: Immunophenotyping and response to ustekinumab.

BACKGROUND: The immune abnormalities underlying the ichthyoses are poorly understood. OBJECTIVE: To determine the immunophenotype of an ichthyosis resulting from mutations in the spectrin repeat 6 (SR6) domain of desmoplakin gene (DSP) and target therapy on the basis of molecular pathogenesis. METHODS: Immunophenotyping was performed by using the blood and skin of a girl with SR6 region DSP mutations causing erythroderma/ichthyosis and cardiomyopathy. RESULTS: On the basis of the discovery of T helper 1 and T helper 17/interleukin 23 skewing in the skin and T helper 17/interleukin 22 skewing in blood, ustekinumab therapy was initiated. Ustekinumab was also administered to a boy with an SR6 region DSP mutation and ichthyosis without cardiomyopathy. Both children responded despite previous poor responses to immunosuppressants and retinoids. LIMITATIONS: Small number of patients and immunophenotyping in only 1 patient. CONCLUSION: An understanding of the molecular basis of inflammation in rare cutaneous disorders can lead to targeted therapy, which promises to be more beneficial than broad immunosuppressants.

Novel concepts of prevention and treatment of atopic dermatitis through barrier and immune manipulations with implications for the atopic march.

Skin barrier abnormalities have been suggested to play an essential role in initiation of early atopic dermatitis (AD). Antigen penetration through a compromised barrier likely leads to increased innate immune responses, antigen-presenting cell stimulation, and priming of overt cutaneous disease. In a TH2-promoting environment, T-cell/B-cell interactions occurring in regional lymph nodes lead to excessive IgE switch. Concurrent redistribution of memory T cells into the circulation not only leads to exacerbation of AD through T-cell skin infiltration but also spreads beyond the skin to initiate the atopic march, which includes food allergy, asthma, and allergic rhinitis. Possible primary interventions to prevent AD are focusing on improving skin barrier integrity, including supplementing barrier function with moisturizers. As for secondary prophylaxis in children with established AD, this can be stratified into prevention of disease exacerbations by using proactive approaches (with either topical corticosteroids or topical calcineurin inhibitors) in mild AD cases or the prevention of other atopic disorders that will probably mandate systemic immunosuppression in severe AD cases.

Alterations in B-cell subsets in pediatric patients with early atopic dermatitis.

BACKGROUND: B cells undergo maturation and class-switching in response to antigen exposure and T-cell help. Early B-cell differentiation has not been defined in patients with early-onset atopic dermatitis (AD). OBJECTIVE: We sought to define the frequency of B-cell subsets associated with progressive B-cell maturation and IgE class-switching. METHODS: We studied 27 children and 34 adults with moderate-to-severe AD (mean SCORAD score, 55 and 65, respectively) and age-matched control subjects (15 children and 27 adults). IgD/CD27 and CD24/CD38 core gating systems and an 11-color flow cytometric panel were used to determine the frequencies of circulating B-cell subsets. Serum total and allergen-specific IgE (sIgE) levels were measured by using ImmunoCAP. RESULTS: Compared with adults, children showed T-cell predominance in the skin. Circulating CD19+CD20+ B-cell counts were lower in patients with pediatric AD than in control subjects (24% vs 33%, P = .04), whereas CD3+ T-cell counts were higher (62% vs 52%, P = .05). A decreased B-cell/T-cell lymphocyte ratio with age was observed only in pediatric control subjects (r = -0.48, P = .07). In pediatric patients with AD, a positive correlation was observed between B-cell/T-cell ratio and nonswitched memory B-cell counts (r = 0.42, P = .03). Higher frequencies of positive sIgE levels were seen in pediatric patients with AD (P < .0001). Diverse sIgE levels correlated with SCORAD scores and age of pediatric patients with AD (P < .01). Positive correlations were observed between activated B-cell and memory T-cell counts (P < .02). In patients with AD, IgE sensitization to most allergens clustered with age, TH1, TH2, total IgE levels, and B-cell memory subsets. CONCLUSIONS: Peripheral B and T cells are altered in pediatric patients with early AD, but T cells predominate in skin lesions.

Diverse activation and differentiation of multiple B-cell subsets in patients with atopic dermatitis but not in patients with psoriasis.

BACKGROUND: Atopic dermatitis (AD) and psoriasis pathogeneses involve skin barrier impairment and immune dysregulation; however, the contribution of B-cell imbalances to these diseases has not yet been determined. OBJECTIVE: We sought to quantify B-cell populations and antibody-secreting cells in the blood of patients with AD, patients with psoriasis, and control subjects. METHODS: We studied 34 adults with moderate-to-severe AD (mean SCORAD score, 65), 24 patients with psoriasis (mean Psoriasis Area and Severity Index score, 16), and 27 healthy subjects using an 11-color flow cytometric antibody panel. IgD/CD27 and CD24/CD38 core gating systems were used to determine frequencies of plasmablasts and naive, memory, transitional, and activated B cells. RESULTS: We measured increased CD19(+)CD20(+) B-cell counts in the skin and blood of patients with AD (P < .01). Significantly higher frequencies of chronically activated CD27(+) memory and nonswitched memory B cells were observed in patients with AD (P < .05), with lower values of double-negative populations (4% for patients with AD vs. 7% for patients with psoriasis [P = .001] and 6% for control subjects [P = .02]). CD23 expression was highest in patients with AD and correlated with IgE levels (P < .01) and disease severity (r = 0.6, P = .0002). Plasmablast frequencies and IgE expression were highest in all memory subsets of patients with AD (P < .01). Finally, CD19(+)CD24(++)CD38(++) transitional and CD19(+)CD24(-)CD38(-) new memory B-cell counts were higher in patients with AD versus those in patients with psoriasis (2.8% vs. 1.4% [P = .001] and 9.2% vs. 5.7% [P = .02], respectively). CONCLUSIONS: AD is accompanied by systemic expansion of transitional and chronically activated CD27(+) memory, plasmablast, and IgE-expressing memory subsets. These data create a critical basis for the future understanding of this debilitating skin disease.

Petrolatum: Barrier repair and antimicrobial responses underlying this "inert" moisturizer.

BACKGROUND: Petrolatum is a common moisturizer often used in the prevention of skin infections after ambulatory surgeries and as a maintenance therapy of atopic dermatitis (AD). However, the molecular responses induced by petrolatum in the skin have never been assessed. OBJECTIVE: We sought to define the cutaneous molecular and structural effects induced by petrolatum. METHODS: Thirty-six healthy subjects and 13 patients with moderate AD (mean SCORAD score, 39) were studied by using RT-PCR, gene arrays, immunohistochemistry, and immunofluorescence performed on control skin, petrolatum-occluded skin, and skin occluded with a Finn chamber only. RESULTS: Significant upregulations of antimicrobial peptides (S100A8/fold change [FCH], 13.04; S100A9/FCH, 11.28; CCL20/FCH, 8.36; PI3 [elafin]/FCH, 15.40; lipocalin 2/FCH, 6.94, human ß-defensin 2 [DEFB4A]/FCH, 4.96; P < .001 for all) and innate immune genes (IL6, IL8, and IL1B; P < .01) were observed in petrolatum-occluded skin compared with expression in both control and occluded-only skin. Application of petrolatum also induced expression of key barrier differentiation markers (filaggrin and loricrin), increased stratum corneum thickness, and significantly reduced T-cell infiltrates in the setting of "normal-appearing" or nonlesional AD skin, which is known to harbor barrier and immune defects. CONCLUSIONS: Petrolatum robustly modulates antimicrobials and epidermal differentiation barrier measures. These data shed light on the beneficial molecular responses of petrolatum in barrier-defective states, such as AD and postoperative wound care.

Early-onset pediatric atopic dermatitis is TH2 but also TH17 polarized in skin.

BACKGROUND: Atopic dermatitis (AD) affects 15% to 25% of children and 4% to 7% of adults. Paradigm-shifting discoveries about AD have been based on adult biomarkers, reflecting decades of disease activity, although 85% of cases begin by 5 years. Blood phenotyping shows only TH2 skewing in patients with early-onset pediatric AD, but alterations in early pediatric skin lesions are unknown, limiting advancement of targeted therapies. OBJECTIVE: We sought to characterize the early pediatric AD skin phenotype and its differences from pediatric control subjects and adults with AD. METHODS: Using immunohistochemistry and quantitative real-time PCR, we assessed biopsy specimens from 19 children with AD younger than 5 years within 6 months of disease onset in comparison with adults with AD or psoriasis and pediatric and adult control subjects. RESULTS: In lesional skin children showed comparable or greater epidermal hyperplasia (thickness and keratin 16) and cellular infiltration (CD3+, CD11c+, and FcεRI+) than adults with AD. Similar to adults, strong activation of the TH2 (IL-13, IL-31, and CCL17) and TH22 (IL-22 and S100As) axes and some TH1 skewing (IFN-γ and CXCL10) were present. Children showed significantly higher induction of TH17-related cytokines and antimicrobials (IL-17A, IL-19, CCL20, LL37, and peptidase inhibitor 3/elafin), TH9/IL-9, IL-33, and innate markers (IL-8) than adults (P < .02). Despite the characteristic downregulation in adult patients with AD, filaggrin expression was similar in children with AD and healthy children. Nonlesional skin in pediatric patients with AD showed higher levels of inflammation (particularly IL-17A and the related molecules IL-19 and LL37) and epidermal proliferation (keratin 16 and S100As) markers (P < .001). CONCLUSION: The skin phenotype of new-onset pediatric AD is substantially different from that of adult AD. Although excess TH2 activation characterizes both, TH9 and TH17 are highly activated at disease initiation. Increases in IL-19 levels might link TH2 and TH17 activation.

Early pediatric atopic dermatitis shows only a cutaneous lymphocyte antigen (CLA)(+) TH2/TH1 cell imbalance, whereas adults acquire CLA(+) TH22/TC22 cell subsets.

BACKGROUND: Identifying differences and similarities between cutaneous lymphocyte antigen (CLA)(+) polarized T-cell subsets in children versus adults with atopic dermatitis (AD) is critical for directing new treatments toward children. OBJECTIVE: We sought to compare activation markers and frequencies of skin-homing (CLA(+)) versus systemic (CLA(-)) "polar" CD4 and CD8 T-cell subsets in patients with early pediatric AD, adults with AD, and control subjects. METHODS: Flow cytometry was used to measure CD69/inducible costimulator/HLA-DR frequency in memory cell subsets, as well as IFN-γ, IL-13, IL-9, IL-17, and IL-22 cytokines, defining TH1/cytotoxic T (TC) 1, TH2/TC2, TH9/TC9, TH17/TC17, and TH22/TC22 populations in CD4 and CD8 cells, respectively. We compared peripheral blood from 19 children less than 5 years old and 42 adults with well-characterized moderate-to-severe AD, as well as age-matched control subjects (17 children and 25 adults). RESULTS: Selective inducible costimulator activation (P < .001) was seen in children. CLA(+) TH2 T cells were markedly expanded in both children and adults with AD compared with those in control subjects, but decreases in CLA(+) TH1 T-cell numbers were greater in children with AD (17% vs 7.4%, P = .007). Unlike in adults, no imbalances were detected in CLA(-) T cells from pediatric patients with AD nor were there altered frequencies of TH22 T cells within the CLA(+) or CLA(-) compartments. Adults with AD had increased frequencies of IL-22-producing CD4 and CD8 T cells within the skin-homing population, compared with controls (9.5% vs 4.5% and 8.6% vs 2.4%, respectively; P < .001), as well as increased HLA-DR activation (P < .01). CONCLUSIONS: These data suggest that TH2 activation within skin-homing T cells might drive AD in children and that reduced counterregulation by TH1 T cells might contribute to excess TH2 activation. TH22 "spreading" of AD is not seen in young children and might be influenced by immune development, disease chronicity, or recurrent skin infections.

Severe atopic dermatitis is characterized by selective expansion of circulating TH2/TC2 and TH22/TC22, but not TH17/TC17, cells within the skin-homing T-cell population.

BACKGROUND: Past studies of blood T-cell phenotyping in patients with atopic dermatitis (AD) have provided controversial results and were mostly performed before the identification of TH9, TH17, and TH22 T-cell populations in human subjects. OBJECTIVE: We sought to quantify TH1, TH2, TH9, TH17, and TH22 T-cell populations and corresponding CD8(+) T-cell subsets in both cutaneous lymphocyte antigen (CLA)-positive and CLA(-) T-cell subsets in patients with AD and control subjects. METHODS: We studied 42 adults with severe AD (mean SCORAD score, 65) and 25 healthy subjects using an 11-color flow cytometric antibody panel. Frequencies of IFN-γ-, IL-22-, IL-13-, IL-17-, and IL-9-producing CD4(+) and CD8(+) T cells were compared in CLA(-) and CLA(+) populations. RESULTS: We measured increased TH2/TC2/IL-13(+) and TH22/TC22/IL-22(+) populations (P < .1) in patients with severe AD versus control subjects, with significant differences in CLA(+) T-cell numbers (P < .01). A significantly lower frequency of CLA(+) IFN-γ-producing cells was observed in patients with AD, with no significant differences in CLA(-) T-cell numbers. The CLA(+) TH1/TH2 and TC1/TC2 ratio was highly imbalanced in patients with AD (10 vs 3 [P = .005] and 19 vs 7 [P < .001], respectively). Positive correlations were found between frequencies of IL-13- and IL-22-producing CD4(+) and CD8(+) T cells (r = 0.5 and 0.8, respectively; P < .0001), and frequencies of IL-13-producing CLA(+) cells were also correlated with IgE levels and SCORAD scores. Patients with AD with skin infections had higher CD4(+) IL-22(+) and IL-17(+) cell frequencies, which were highly significant among CLA(-) cells (IL-22: 3.7 vs 1.7 [P < .001] and IL-17: 1.7 vs 0.6 [P < .001]), with less significant effects among CLA(+) T cells (IL-22: 11 vs 7.5, P = .04). CONCLUSIONS: Severe AD is accompanied by expansion of skin-homing TH2/TC2 and TH22/TC22 subsets with lower TH1/TC1 frequencies. These data create a critical basis for studying alterations in immune activation in adults and pediatric patients with AD.

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.

Molecular profiling of contact dermatitis skin identifies allergen-dependent differences in immune response.

BACKGROUND: Allergic contact dermatitis (ACD) is the most common occupational disease. Although murine contact hypersensitivity provides a framework for understanding ACD, it carries important differences from its human counterpart. Unlike the contact hypersensitivity model, which is induced by potent sensitizers (ie, dinitrofluorobenzene), human ACD is induced by weak-to-moderate sensitizers (ie, nickel), which cannot induce reactions in mice. Distinct hapten-specific immune-polarizing responses to potent inducers were suggested in mice, with unclear relevance to human ACD. OBJECTIVE: We explored the possibility of distinct T-cell polarization responses in skin to common clinically relevant ACD allergens. METHODS: Gene-expression and cellular studies were performed on common allergens (ie, nickel, fragrance, and rubber) compared with petrolatum-occluded skin, using RT-PCR, gene arrays, and immunohistochemistry. RESULTS: Despite similar clinical reactions in all allergen groups, distinct immune polarizations characterized different allergens. Although the common ACD transcriptome consisted of 149 differentially expressed genes across all allergens versus petrolatum, a much larger gene set was uniquely altered by individual allergens. Nickel demonstrated the highest immune activation, with potent inductions of innate immunity, TH1/TH17 and a TH22 component. Fragrance, and to a lesser extent rubber, demonstrated a strong TH2 bias, some TH22 polarization, and smaller TH1/TH17 contributions. CONCLUSIONS: Our study offers new insights into the pathogenesis of ACD, expanding the understanding of T-cell activation and associated cytokines in allergen-reactive tissues. It is the first study that defines the common transcriptome of clinically relevant sensitizers in human skin and identifies unique pathways preferentially activated by different allergens, suggesting that ACD cannot be considered a single entity.