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J Immunol. 2013 Nov 15;191(10):5182-95. doi: 10.4049/jimmunol.1201819. Epub 2013 Oct 11.

Wnt6 is expressed in granulomatous lesions of Mycobacterium tuberculosis-infected mice and is involved in macrophage differentiation and proliferation.

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1
Division of Microbial Interface Biology, Research Center Borstel, Leibniz Center for Medicine and Biosciences, 23845 Borstel, Germany;

Abstract

The Wnt signaling network, an ancient signaling system governing ontogeny and homeostatic processes, has recently been identified to exert immunoregulatory functions in a variety of inflammatory and infectious disease settings including tuberculosis. In this study, we show that Wnt6 is expressed in granulomatous lesions in the lung of Mycobacterium tuberculosis-infected mice. We identified foamy macrophage-like cells as the primary source of Wnt6 in the infected lung and uncovered a TLR-MyD88-NF-κB-dependent mode of induction in bone marrow-derived macrophages. Analysis of Wnt6-induced signal transduction revealed a pertussis toxin-sensitive, ERK-mediated, but β-catenin-independent induction of c-Myc, a master regulator of cell proliferation. Increased Ki-67 mRNA expression levels and enhanced thymidine incorporation in Wnt6-treated macrophage cultures demonstrate a proliferation-promoting effect on murine macrophages. Further functional studies in M. tuberculosis-infected macrophages using Wnt6 conditioned medium and Wnt6-deficient macrophages uncovered a Wnt6-dependent induction of macrophage Arginase-1 and downregulation of TNF-α. This identifies Wnt6 as a novel factor driving macrophage polarization toward an M2-like phenotype. Taken together, these findings point to an unexpected role for Wnt6 in macrophage differentiation in the M. tuberculosis-infected lung.

PMID:
24123681
DOI:
10.4049/jimmunol.1201819
[Indexed for MEDLINE]
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