Sonic Hedgehog signaling limits atopic dermatitis via Gli2-driven immune regulation
Eleftheria Papaioannou, … , Ryan F. L. O’Shaughnessy, Tessa Crompton
Eleftheria Papaioannou, … , Ryan F. L. O’Shaughnessy, Tessa Crompton
Published August 1, 2019; First published July 2, 2019
Citation Information: J Clin Invest. 2019;129(8):3153-3170. https://doi.org/10.1172/JCI125170.
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Research Article Immunology Inflammation

Sonic Hedgehog signaling limits atopic dermatitis via Gli2-driven immune regulation

Abstract

Hedgehog (Hh) proteins regulate development and tissue homeostasis, but their role in atopic dermatitis (AD) remains unknown. We found that on induction of mouse AD, Sonic Hedgehog (Shh) expression in skin and Hh pathway action in skin T cells were increased. Shh signaling reduced AD pathology and the levels of Shh expression determined disease severity. Hh-mediated transcription in skin T cells in AD-induced mice increased Treg populations and their suppressive function through increased active transforming growth factor–β (TGF-β) in Treg signaling to skin T effector populations to reduce disease progression and pathology. RNA sequencing of skin CD4+ T cells from AD-induced mice demonstrated that Hh signaling increased expression of immunoregulatory genes and reduced expression of inflammatory and chemokine genes. Addition of recombinant Shh to cultures of naive human CD4+ T cells in iTreg culture conditions increased FOXP3 expression. Our findings establish an important role for Shh upregulation in preventing AD, by increased Gli-driven, Treg cell–mediated immune suppression, paving the way for a potential new therapeutic strategy.

Authors

Eleftheria Papaioannou, Diana C. Yánez, Susan Ross, Ching-In Lau, Anisha Solanki, Mira Manilal Chawda, Alex Virasami, Ismael Ranz, Masahiro Ono, Ryan F. L. O’Shaughnessy, Tessa Crompton

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Figure 8

Hh signaling promotes immune-regulatory function through TGF-β.

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Hh signaling promotes immune-regulatory function through TGF-β. Hedgehog...
Hedgehog signaling and human AD. (A–E) Two independent experiments with at least 6 mice per group. (A) Percentage of LAP+ cells, gated on CD45+CD3– and CD4+CD25– (non-Treg) from skin of Oxa-treated Gli2ΔN2 (black), WT (red), and Gli2ΔC2 (blue) mice. (B) Representative histograms show anti-LAP staining on skin Tregs from Oxa-treated littermates. Plots show number of LAP+ Tregs in WT (black) littermates and Gli2ΔN2 (red) (left) or Gli2ΔC2 (red) (right). (C) Active TGF-β concentration (ELISA) in culture supernatants. CD4+CD25– splenocytes from WT (black) and Gli2ΔC2 (red) mice, cultured alone (left). WT CD4+ T cells cultured 1:1 with FACS-sorted Tregs (CD4+CD25+) from Oxa-treated WT (black) and Gli2ΔC2 (red) mice (right). (D and E) Representative FACS plots show pSmad2/3 expression in skin (D) CD4+ and (E) CD8+ (gated on CD45+CD3+γδTCR–) from Oxa-treated WT and Gli2ΔC2 mice (left); and WT and Gli2ΔN2 mice (right). Plots show MFI of anti-pSmad2/3 in skin CD4+ (left) and CD8+ (right) from Gli2ΔN2 (black), WT (red), and Gli2ΔC2 (blue) Oxa-treated groups (1-way ANOVA). (F) Naive CD4+ cells from 4 randomly selected unknown leukocyte-cone donors cultured for 5 days under iTreg conditions in presence or absence of rShh (labeled iTregs). Dot-plot shows representative CD4 and CD25 expression. Histogram shows representative icFOXP3 expression, gated on CD4+CD25+ and giving percentage of cells in marker shown. Scatter plot shows percentage of FOXP3+ cells gated on CD4+CD25+ from cultures from 4 independent donors; 2-tailed paired t test. (G) Scatter plots show expression (RPKM) from publicly available RNA-seq data sets (GEO GSE32924) from human healthy skin (red, n = 8), and nonlesional (blue) and lesional (green) skin from AD patients (n = 12). Expression of genes encoding Hh pathway components and regulators in healthy skin and nonlesional skin from AD patients (left). Expression of Hh target genes in nonlesional and lesional skin from AD patients (2-tailed paired t test) (right). Two-tailed unpaired Student’s t test unless stated otherwise; plots are mean ± SEM, each symbol represents a different individual. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.