Author(s): Rankin AL, Mumm JB, Murphy E, Turner S, Yu N,
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Abstract IL-33 is constitutively expressed in epithelial barrier tissues, such as skin. Although increased expression of IL-33/IL-33R has been correlated with fibrotic disorders, such as scleroderma and progressive systemic sclerosis, the direct consequences of IL-33 release in skin has not been reported. To determine the effects of dysregulated IL-33 signaling in skin, we administered IL-33 s.c. and monitored its effects at the injection site. Administration of IL-33 resulted in IL-33R-dependent accumulation of eosinophils, CD3(+) lymphocytes, F4/80(+) mononuclear cells, increased expression of IL-13 mRNA, and the development of cutaneous fibrosis. Consistent with extensive cutaneous tissue remodeling, IL-33 resulted in significant modulation of a number of extracellular matrix-associated genes, including collagen VI, collagen III, and tissue inhibitor of metalloproteases-1. We establish that IL-33-induced fibrosis requires IL-13 using IL-13 knockout mice and eosinophils using Delta dblGATA mice. We show that bone marrow-derived eosinophils secrete IL-13 in response to IL-33 stimulation, suggesting that eosinophil-derived IL-13 may promote IL-33-induced cutaneous fibrosis. Collectively, our results identify IL-33 as a previously unrecognized profibrotic mediator in skin and highlight the cellular and molecular pathways by which this pathology develops.
This article was published in J Immunol
and referenced in Journal of Clinical & Cellular Immunology