epidermal-growth-factor and Dermatitis--Atopic

Atopic dermatitis (AD) remains a highly heterogenous disorder with a multifactorial aetiology. Whilst keratinocytes are known to play a fundamental role in AD, their contribution to the overall immune landscape in moderate-to-severe AD is still poorly understood. In order to design new therapeutics, further investigation is needed into common disease pathways at the molecular level. We used publicly available whole-tissue RNAseq data (4 studies) and single-cell RNAseq keratinocyte data to identify genes/pathways that are involved in keratinocyte responses in AD and after dupilumab treatment. Transcripts present in both keratinocytes (single-cell) and whole-tissue, referred to as the keratinocyte-enriched lesional skin (KELS) genes, were analysed using functional/pathway analysis. Following statistical testing, 2049 genes (16.8%) were differentially expressed in KELS. Enrichment analyses predicted increases in not only type-1/type-2 immune signalling and chemoattraction, but also in EGF-dominated growth factor signalling. We identified complex crosstalk between keratinocytes and immune cells involving a dominant EGF family signature which converges on keratinocytes with potential immunomodulatory and chemotaxis-promoting consequences. Although keratinocytes express the IL4R, we observed no change in EGF signalling in KELS after three-month treatment with dupilumab, indicating that this pathway is not modulated by dupilumab immunotherapy. EGF family signalling is significantly dysregulated in AD lesions but is not associated with keratinocyte proliferation. EGF signalling pathways in AD require further study.

Topics: Cell Proliferation; Dermatitis, Atopic; Epidermal Growth Factor; Humans; Keratinocytes; Signal Transduction; Skin

Atopic dermatitis (AD) is a common inflammatory skin disease characterized by a complex, heterogeneous pathogenesis including skin barrier dysfunction, immunology, and pruritus. Although epidermal growth factor (EGF) is essential for epithelial homeostasis and wound healing, the effect of EGF on AD remains to be explored. To develop a new therapy for AD, the anti-AD potential of EGF was investigated by inducing AD-like skin lesions in NC/Nga mice using 2,4-dinitrochlorobenzene (DNCB). EGF was administrated to NC/Nga mice to evaluate its therapeutic effect on DNCB-induced AD. EGF treatment improved dermatitis score, ear thickness, epidermal hyperplasia, serum total immunoglobulin E level, and transepidermal water loss in NC/Nga mice with DNCB-induced AD. In addition, levels of skin barrier-related proteins such as filaggrin, involucrin, loricrin, occludin, and zonula occludens-1 (ZO-1) were increased by EGF treatment. These beneficial effects of EGF on AD may be mediated by EGF regulation of Th1/Th2-mediated cytokines, mast cell hyperplasia, and protease activated receptor-2 (PAR-2) and thymic stromal lymphopoietin (TSLP), which are triggers of AD. Taken together, our findings suggest that EGF may potentially protect against AD lesional skin via regulation of skin barrier function and immune response.

Topics: Administration, Topical; Animals; Cytokines; Dermatitis, Atopic; Dinitrochlorobenzene; Epidermal Growth Factor; Filaggrin Proteins; Intermediate Filament Proteins; Male; Mast Cells; Mice; Protective Agents; Receptor, PAR-2; Skin; Thymic Stromal Lymphopoietin; Zonula Occludens-1 Protein

Despite the important role for epidermal growth factor (EGF) in epithelial homeostasis and wound healing, it has not been investigated in atopic dermatitis (AD). We used AD animal models to explore the role of EGF in AD. In an acute AD model, skin transepidermal water loss was significantly attenuated in EGF-treated mice. Blockade of EGFR signaling genetically or pharmacologically confirms a protective role for EGFR signaling in AD. In a chronic/relapsing AD model, EGF treatment of mice with established AD resulted in an attenuation of AD exacerbation (skin epithelial thickness, cutaneous inflammation, and total and allergen specific IgE) following cutaneous allergen rechallenge. EGF treatment did not alter expression of skin barrier junction proteins or antimicrobial peptides in the AD model. However, EGF treatment attenuated allergen-induced expression of IL-17A, CXCL1, and CXCL2 and neutrophil accumulation in AD skin following cutaneous allergen exposure. IL-17A production was decreased in the in vitro restimulated skin-draining lymph node cells from the EGF-treated mice. Similarly, IL-17A was increased in waved-2 mice skin following allergen exposure. Whereas IL-6 and IL-1β expression was attenuated in the skin of EGF-treated mice, EGF treatment also suppressed allergen-induced IL-6 production by keratinocytes. Given the central role of IL-6 in priming Th17 differentiation in the skin, this effect of EGF on keratinocytes may contribute to the protective roles for EGFR in AD pathogenesis. In conclusion, our study provides evidence for a previously unrecognized protective role for EGF in AD and a new role for EGF in modulating IL-17 responses in the skin.

Topics: Administration, Cutaneous; Allergens; Animals; Cells, Cultured; Chemokine CXCL1; Chemokine CXCL2; Dermatitis, Atopic; Disease Progression; Epidermal Growth Factor; ErbB Receptors; Erlotinib Hydrochloride; Gene Expression Regulation; Humans; Interleukin-17; Interleukin-1beta; Interleukin-22; Interleukin-6; Interleukins; Keratinocytes; Lymph Nodes; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Mice, Mutant Strains; Quinazolines; Recurrence; Signal Transduction; Skin; Specific Pathogen-Free Organisms; Th17 Cells