TY - JOUR
T1 - CX3CR1 deficiency exacerbates neuronal loss and impairs early regenerative responses in the target-ablated olfactory epithelium
AU - Blomster, Linda V.
AU - Vukovic, Jana
AU - Hendrickx, Debbie A.E.
AU - Jung, Steffen
AU - Harvey, Alan R.
AU - Filgueira, Luis
AU - Ruitenberg, Marc J.
N1 - Australian Research Council (ARC) [DP0774113]; School of Biomedical Sciences at The University of Queensland; office of the DVC(R) of The University of Queensland; Australian GovernmentThe authors are grateful to Dr. Peter Mark and Mr. Greg Cozens (UWA) for assistance with quantitative PCR experiments. Work in the laboratory of M.J.R. was financially supported by the Australian Research Council (Discovery Grant DP0774113 to M.J.R.), The School of Biomedical Sciences at The University of Queensland and an Enabling Grant from the office of the DVC(R) of The University of Queensland (to M.J.R.). M.J.R. was additional supported by an ARC Postdoctoral Fellowship (2007-2009; DP0774113) and L.V.B. by an International Postgraduate Research Scholarship of the Australian Government.
PY - 2011/11
Y1 - 2011/11
N2 - The olfactory epithelium is a site of sustained adult neurogenesis where olfactory sensory neurons are continuously replaced from endogenous stem/progenitor cells. Epithelial macrophages have been implicated in the phagocytosis of degenerating cells but the molecular mechanisms allowing for their recruitment and activation while maintaining a neurogenic microenvironment are poorly understood. We have previously shown that the chemokine fractalkine (CX3CL1) is expressed by olfactory sensory neurons and ensheathing cells in the olfactory epithelium. In turn, the fractalkine receptor, CX3CR1, is expressed on macrophages and dendritic cells within the olfactory epithelium. We report that a selective cell death of olfactory sensory neurons in the epithelium of CX3CR1-deficient mice via target ablation (i.e. olfactory bulbectomy) results in an exacerbated loss of olfactory sensory neurons compared to wild-type mice. In addition, reduced proliferation of intraepithelial stem/progenitor cells was observed in lesioned CX3CR1-deficient mice, suggesting an impaired regenerative response. Importantly, a lack of CX3CL1-signaling caused increased recruitment of macrophages into the olfactory epithelium, which in turn contained higher levels of pro-inflammatory cytokines (e.g. TNF-α and IL-6) as determined by qPCR. We also present novel data showing that, relative to wild-type, CX3CR1-deficient macrophages have diminished phagocytic activity following stimulation with CX3CL1. Collectively, our data indicate that signaling through the CX3CR1 receptor modulates macrophage activity, resulting in an environment conducive to olfactory sensory neuron clearance and targeted replacement from endogenous stem/progenitor cells.
AB - The olfactory epithelium is a site of sustained adult neurogenesis where olfactory sensory neurons are continuously replaced from endogenous stem/progenitor cells. Epithelial macrophages have been implicated in the phagocytosis of degenerating cells but the molecular mechanisms allowing for their recruitment and activation while maintaining a neurogenic microenvironment are poorly understood. We have previously shown that the chemokine fractalkine (CX3CL1) is expressed by olfactory sensory neurons and ensheathing cells in the olfactory epithelium. In turn, the fractalkine receptor, CX3CR1, is expressed on macrophages and dendritic cells within the olfactory epithelium. We report that a selective cell death of olfactory sensory neurons in the epithelium of CX3CR1-deficient mice via target ablation (i.e. olfactory bulbectomy) results in an exacerbated loss of olfactory sensory neurons compared to wild-type mice. In addition, reduced proliferation of intraepithelial stem/progenitor cells was observed in lesioned CX3CR1-deficient mice, suggesting an impaired regenerative response. Importantly, a lack of CX3CL1-signaling caused increased recruitment of macrophages into the olfactory epithelium, which in turn contained higher levels of pro-inflammatory cytokines (e.g. TNF-α and IL-6) as determined by qPCR. We also present novel data showing that, relative to wild-type, CX3CR1-deficient macrophages have diminished phagocytic activity following stimulation with CX3CL1. Collectively, our data indicate that signaling through the CX3CR1 receptor modulates macrophage activity, resulting in an environment conducive to olfactory sensory neuron clearance and targeted replacement from endogenous stem/progenitor cells.
UR - http://www.scopus.com/inward/record.url?scp=80053384283&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/j.mcn.2011.08.004
DO - https://doi.org/10.1016/j.mcn.2011.08.004
M3 - مقالة
SN - 1044-7431
VL - 48
SP - 236
EP - 245
JO - Molecular and Cellular Neuroscience
JF - Molecular and Cellular Neuroscience
IS - 3
ER -