Article

Deficient CX3CR1 Signaling Promotes Recovery after Mouse Spinal Cord Injury by Limiting the Recruitment and Activation of Ly6C(lo)/iNOS(+) Macrophages

Center for Brain and Spinal Cord Repair, The Ohio State University, Columbus, Ohio 43210, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.75). 07/2011; 31(27):9910-22. DOI: 10.1523/JNEUROSCI.2114-11.2011
Source: PubMed

ABSTRACT Macrophages exert divergent effects in the injured CNS, causing either neurotoxicity or regeneration. The mechanisms regulating these divergent functions are not understood but can be attributed to the recruitment of distinct macrophage subsets and the activation of specific intracellular signaling pathways. Here, we show that impaired signaling via the chemokine receptor CX3CR1 promotes recovery after traumatic spinal cord injury (SCI) in mice. Deficient CX3CR1 signaling in intraspinal microglia and monocyte-derived macrophages (MDMs) attenuates their ability to synthesize and release inflammatory cytokines and oxidative metabolites. Also, impaired CX3CR1 signaling abrogates the recruitment or maturation of MDMs with presumed neurotoxic effects after SCI. Indeed, in wild-type mice, Ly6C(lo)/iNOS(+)/MHCII(+)/CD11c(-) MDMs dominate the lesion site, whereas CCR2(+)/Ly6C(hi)/MHCII(-)/CD11c(+) monocytes predominate in the injured spinal cord of CX3CR1-deficient mice. Replacement of wild-type MDMs with those unable to signal via CX3CR1 resulted in anatomical and functional improvements after SCI. Thus, blockade of CX3CR1 signaling represents a selective anti-inflammatory therapy that is able to promote neuroprotection, in part by reducing inflammatory signaling in microglia and MDMs and recruitment of a novel monocyte subset.

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Available from: Kristina A Kigerl, Feb 03, 2014
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    • "Monocyte trafficking to the brain is usually observed in association with substantial CNS-related tissue pathology and inflammation, e.g., multiple sclerosis, traumatic injury, stroke, Alzheimer's disease, or infection (Hafler et al., 2005; Gate et al., 2010; Donnelly et al., 2011; Hawthorne and Popovich, 2011; McGavern and Kang, 2011; de Vries et al., 2012). Therefore, the possibility that RSD could induce monocyte trafficking to the brain was intriguing because it would occur in the absence of CNS tissue pathology (Wohleb et al., 2013). "
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