Background: CCR10 and CCL27 make up the most skin-specific chemokine receptor/ligand pair implicated in skin allergy and inflammatory diseases, including atopic dermatitis and psoriasis. This pair is thought to regulate the migration, maintenance, or both of skin T cells and is suggested to be therapeutic targets for treatment of skin diseases. However, the functional importance of CCR10/CCL27 in vivo remains elusive.
Objective: We sought to determine the expression and function of CCR10 in different subsets of skin T cells under both homeostatic and inflammatory conditions to gain a mechanistic insight into the potential roles of CCR10 during skin inflammation.
Methods: Using heterozygous and homozygous CCR10 knockout/enhanced green fluorescent protein knockin mice, we assessed the expression of CCR10 on regulatory and effector T cells of healthy and inflamed skin induced by chemicals, pathogens, and autoreactive T cells. In addition, we assessed the effect of CCR10 knockout on the maintenance and functions of different T cells and inflammatory status in the skin during different phases of the immune response.
Results: CCR10 expression is preferentially induced on memory-like skin-resident T cells and their progenitors for their maintenance in homeostatic skin but not expressed on most skin-infiltrating effector T cells during inflammation. In CCR10 knockout mice the imbalanced presence and dysregulated function of resident regulatory and effector T cells result in over-reactive and prolonged innate and memory responses in the skin, leading to increased clearance of Leishmania species infection in the skin.
Conclusion: CCR10 is a critical regulator of skin immune homeostasis.
Keywords: Chemokine receptor CCR10; Leishmania species; allergy; dermatitis; immune homeostasis; inflammation; maintenance; migration; regulatory T cells; skin infection; skin-resident T cells.
Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.