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J Dermatol Sci. 2013 Mar;69(3):250-8. doi: 10.1016/j.jdermsci.2012.10.010. Epub 2012 Oct 24.

Chemokine receptors CCR2 and CX3CR1 regulate skin fibrosis in the mouse model of cytokine-induced systemic sclerosis.

Author information

1
Department of Dermatology, Kanazawa University Graduate School of Medical Science, Ishikawa, Japan.

Abstract

BACKGROUND:

Skin fibrotic disorders such as systemic sclerosis (SSc) are characterized by an excessive accumulation of extracellular matrix (ECM), and develop under the influence of certain cytokines. We previously established a mouse model of skin fibrosis induced by exogenous application of cytokines. We have revealed that both the number of macrophages and the levels of macrophage chemoattractant protein-1 (MCP-1) mRNA positively correlate with the extent of skin fibrosis. Macrophages can be divided into two subsets, the first expressing CCR2, and the second expressing CX3CR1.

OBJECTIVE:

To elucidate the role of skin infiltrating macrophages based on CCR2 and CX3CR1 in this cytokine-induced murine fibrosis model.

METHODS:

We examined the amounts of collagen deposited in granulation tissues, the numbers of macrophages and the levels of several mRNA in wild type (WT) mice, CCR2(-/-) mice, and CX3CR1(-/-) mice during injections of transforming growth factor-β (TGF-β) followed by injections of connective tissue growth factor (CTGF).

RESULTS:

TGF-β injection increased the expressions of MCP-1, fractalkine, CCR2 and CX3CR1 mRNA in WT mice. The overproduction of collagen induced by TGF-β was significantly reduced by CCR2 deficiency, while collagen contents induced by CTGF were restored to wild-type levels. In contrast, overproduction of collagen in CX3CR1-deficient mice decreased nearly 50% by both TGF-β and CTGF stimulations.

CONCLUSION:

The involvement of CCR2/MCP-1 interaction (CCR2-dependent loop) was during the TGF-β phase. In contrast, the fractalkine/CX3CR1 interaction contributes to the initiation of fibrosis by TGF-β and its maintenance by CTGF. Collectively, two subsets of macrophages both cooperatively and independently play important roles in the development of fibrosis.

PMID:
23142052
DOI:
10.1016/j.jdermsci.2012.10.010
[Indexed for MEDLINE]

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