Abstract
Activation of the immune response during injury is a critical early event that determines whether the outcome of tissue restoration is regeneration or replacement of the damaged tissue with a scar. The mechanisms by which immune signals control these fundamentally different regenerative pathways are largely unknown. We have demonstrated that, during skin repair in mice, interleukin-4 receptor α (IL-4Rα)-dependent macrophage activation controlled collagen fibril assembly and that this process was important for effective repair while having adverse pro-fibrotic effects. We identified Relm-α as one important player in the pathway from IL-4Rα signaling in macrophages to the induction of lysyl hydroxylase 2 (LH2), an enzyme that directs persistent pro-fibrotic collagen cross-links, in fibroblasts. Notably, Relm-β induced LH2 in human fibroblasts, and expression of both factors was increased in lipodermatosclerosis, a condition of excessive human skin fibrosis. Collectively, our findings provide mechanistic insights into the link between type 2 immunity and initiation of pro-fibrotic pathways.
Copyright © 2015 Elsevier Inc. All rights reserved.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Cicatrix / etiology*
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Cicatrix / metabolism
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Cicatrix / pathology
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Coculture Techniques
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Collagen / metabolism*
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Dermatitis / metabolism
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Dermatitis / pathology
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Fibroblasts / metabolism
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Humans
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Intercellular Signaling Peptides and Proteins / deficiency
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Intercellular Signaling Peptides and Proteins / physiology*
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Interleukins / physiology
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Macrophages / metabolism*
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Mice
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Mice, Inbred BALB C
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Mice, Knockout
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Microfibrils / metabolism
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Microfibrils / ultrastructure
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Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase / biosynthesis
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Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase / genetics
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Receptors, Cell Surface / deficiency
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Receptors, Cell Surface / physiology*
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Scleroderma, Localized / metabolism
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Scleroderma, Localized / pathology
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Signal Transduction / physiology*
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Skin / injuries
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Skin / metabolism
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Skin / pathology
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Wound Healing / physiology*
Substances
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Il4ra protein, mouse
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Intercellular Signaling Peptides and Proteins
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Interleukins
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RETNLB protein, human
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Receptors, Cell Surface
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Retnla protein, mouse
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Collagen
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PLOD2 protein, human
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Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase
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lysyl hydroxylase 2, mouse