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

Abstract

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.

Keywords: Atopic dermatitis; HLA-DR; IFN-γ; IL-13; IL-22; T cell; cutaneous lymphocyte antigen; endotypes; inducible costimulator molecule.

Conflict of interest statement

Disclosures: Other authors have declared that they have no conflict of interest.

Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1.

A-D) The frequency of CLA+ Tem (CD45RO+CCR7−) and Tcm (CD45RO+CCR7+) in CD4+/CD8+ T cells and (E-L) ICOS+ activation in CLA+/− CD4+/CD8+ Tcm/Tem cells in healthy controls and AD patients across ages (ICOS+CLA+CD45RO+CCR7+/−). Bar plots represent means (black)/medians (red) ± SEMs. AD, Atopic dermatitis; CLA, Cutaneous lymphocyte antigen; SEM, Standard error of the mean/median; Tcm, central memory T-cells; Tem, effector memory T-cells.P-values are designated as ***<0.001, **<0.01, *<0.05, and +<0.1.

Figure 2.

A-D) IFN-γ+, (E-H)IL-13+, and (I-L)IFN-γ+/IL-13+ cytokine frequencies in CLA+, CLA−, CD4+ and CD8+ T-cells in healthy controls and AD patients across ages. The ratio between the % of IFN-γ+CLA+CD4+ (or CD8+) T cells and the % of their IL-13+ counterpart was calculated for each sample but was not multiplied by 100 and is therefore unitless. Bar plots represent means (black)/medians (red) ± SEMs. AD, Atopic dermatitis; CLA, Cutaneous lymphocyte antigen; SEM, Standard error of the mean/median.P-values are designated as ***<0.001, **<0.01, *<0.05, and +<0.1.

Figure 3.

A-D) IL-9+ and (E-H)IL-17+ and (I-L) IL-22+ frequencies in CLA+, CLA−, CD4+ and CD8+ T-cells in healthy controls and AD patients across ages. Bar plots represent means (black)/medians (red) ± SEMs. AD, Atopic dermatitis; CLA, Cutaneous lymphocyte antigen; SEM, Standard error of the mean/median.P-values are designated as ***<0.001, **<0.01, *<0.05, and +<0.1.

Figure 4.

Unsupervised hierarchical clustering heatmap displaying polarized T-cell subsets for control and AD across age groups (red: positive/increase; blue: negative/decrease). Fold-changes (FCHs) of the mean frequencies of AD vs. controls for each age group are listed on the right (stars and plus signs display significance). The green cluster includes subsets that were relatively low and stable among controls, but incrementally increased with age in AD. The pink box shows increased IL-9 frequencies in childhood, which decline in adulthood, particularly in AD. The yellow cluster shows markers that increased in both controls and AD.

Figure 5.. Unsupervised hierarchical clustering of polarized cytokine subset frequencies (%) with AD clinical measures

using Spearman correlation as a similarity metric. CD4+/CD8+ IL-13+, IL-17+ and IL-22+ subsets clustered together (turquoise box). IFN-γ+-producing T-cell subsets grouped together with age and disease duration (yellow box). IL-9+ and some IL-13+ and IL-22+ T-cells (purple box) clustered adjacent to AD clinical measures (green box). The heatmap shows the positive (red) or negative (blue) correlations of all parameters, with color intensity reflecting the strength of the correlation (−1 to +1). Dendrograms are shown as a tree, representing the distance between variables. CLA, Cutaneous lymphocyte antigen. P-values are designated as ***<0.01, **<0.01, *<0.05, and +<0.1.

Figure 6.

Spearman correlation scatter plots (linear regression [red=AD/blue=control line] with their CI [in gray]) for (A-E)SCORAD and (F-L) age versus clinical measures and Tem/Tcm subset frequencies (%). Dots colors in plots A-D, F designate different AD patient ages from infancy to adulthood, as shown in Figure 1. CI, Confidence interval; CLA, Cutaneous lymphocyte antigen; EASI, Eczema area and severity index; LS, Lesional; NL, Non-lesional; SCORAD, SCORing of Atopic Dermatitis; Tcm, Central memory T-cells; Tem, Effector memory T-cells; TEWL, Transepidermal water loss.

Figure 7.

Spearman correlation scatter plots (linear regression [red=AD/blue=control line] with their CI [in gray]) for CD4+/CD8+, CLA+/CLA−(A-D) IFN-γ+/IL-13+ producing T-cell ratio, (E-H) IL-13+, and (I-L)IL-22+ producing T-cell frequencies (%) versus age in AD patients (red dots/line) and controls (blue dots/line). CI, Confidence interval; CLA, Cutaneous lymphocyte antigen.

Figure 8.

Unsupervised clustering of AD patients and healthy controls across all principal components of the blood flow cytometry marker frequencies (%) by k-means. In AD, the frequencies of different markers defined three meaningful age-clusters, aligning along a spectrum. While infants (pink ellipse) clustered on the far left, and adults (green ellipse) on the right, children and adolescents (blue ellipse) clustered together between the other age cohorts. The markers that best distinguished between clusters appear in the boxes between two cohorts (colors of markers parallel the colors of the relative age group). Arrows designate elevated frequencies of a given marker among the specific age group. In healthy controls, clusters did not clearly align patients along an age spectrum. CLA, Cutaneous lymphocyte antigen; ICOS, Inducible co-stimulator molecule; Tregs, T-regulatory cells.