Neuronal MCP-1 Expression in Response to Remote Nerve Injury

Experimental autoimmune encephalomyelitis is a T cell-mediated demyelinating disease of the CNS that serves as a model for the human disease multiple sclerosis. Increased expression of the chemokine CCL2 in the CNS has been demonstrated to be important in the development of demyelinating disease presumably by attracting inflammatory cells. However, the mechanism of how CCL2 regulates disease pathogenesis has not been fully elucidated. Using radiation bone marrow chimeric mice we demonstrated that optimum disease was achieved when CCL2 was glia derived. Furthermore, CNS production of CCL2 resulted in the accumulation of iNOS-producing CD11b+CD11c+ dendritic cells and TNF-producing macrophages important for demyelination. Lack of glial-derived CCL2 production did not influence experimental autoimmune encephalomyelitis by altering either Th1 or Th17 cells, as there were no differences in these populations in the CNS or periphery between groups. These results demonstrate that the glial-derived CCL2 is important for the attraction of TNF- and iNOS-producing dendritic cells and effector macrophages to the CNS for development of subsequent autoimmune disease.

Section: Discussionmentioning

confidence: 99%

Production of CCL2 by Central Nervous System Cells Regulates Development of Murine Experimental Autoimmune Encephalomyelitis through the Recruitment of TNF- and iNOS-Expressing Macrophages and Myeloid Dendritic Cells

Dogan

Elhofy

Karpus

2008

“…Because it has been found that neurons express high levels of fractalkine and the corresponding receptor (CX3CR1) is expressed in microglia, a functional role of chemokines in the signaling from neurons to microglia has been suggested (42). Although microglial activation was unchanged in CX3CR1 knockout mice, other neuronal chemokines might contribute to the signaling (43). We have recently shown that damaged neurons in vivo and in vitro rapidly induce the expression of CCL21, and we therefore suggest that CCL21 signals neuronal damage to microglial cells (6).…”

Section: Discussionmentioning

confidence: 99%

Secondary Lymphoid Tissue Chemokine (CCL21) Activates CXCR3 to Trigger a Cl− Current and Chemotaxis in Murine Microglia

Rappert

Biber

Nolte

et al. 2002

141

130

Microglial cells represent the major immunocompetent element of the CNS and are activated by any type of brain injury or disease. A candidate for signaling neuronal injury to microglial cells is the CC chemokine ligand CCL21, given that damaged neurons express CCL21. Investigating microglia in acute slices and in culture, we demonstrate that a local application of CCL21 for 30 s triggered a Cl− conductance with lasted for tens of minutes. This response was sensitive to the Cl− channel blockers 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid and 4-acetamide-4′-isothiocyanatostilbene, 2,2′-disulfonic acid. Moreover, CCL21 triggered a chemotaxis response, which was sensitive to Cl− channel blockers. In microglial cells cultured from CCR7 knockout mice, CCL21 produced the same type of Cl− current as well as a chemotaxis response. In contrast, in microglial cells from CXCR3 knockout mice, CCL21 triggered neither a Cl− conductance nor a chemotaxis response after CCL21 application. We conclude that the CCL21-induced Cl− current is a prerequisite for the chemotaxis response mediated by the activation of CXCR3 but not CCR7 receptors, indicating that in brain CCL21 acts via a different receptor system than in lymphoid organs.

“…Using the ependymal route, described by Martino et al (26), allows vectors to distribute throughout cerebrospinal fluid (CSF) and infect ependymal and leptomeningeal cells, which in turn secrete the product of the transgene into the CSF. This route avoids the traumatic effects of tissue injury associated with intraparenchymal and intracerebroventricular injections, which can include chemokine production and disruption of the blood-brain barrier (27)(28)(29)(30).…”

Section: Ifn-␥-induced Chemokines Synergize With Pertussis Toxin To Pmentioning

confidence: 99%

IFN-γ-Induced Chemokines Synergize with Pertussis Toxin to Promote T Cell Entry to the Central Nervous System

Millward

Caruso

Campbell

et al. 2007

Inflammation of the CNS, which occurs during multiple sclerosis and experimental autoimmune encephalomyelitis, is characterized by increased levels of IFN-γ, a cytokine not normally expressed in the CNS. To investigate the role of IFN-γ in CNS, we used intrathecal injection of a replication-defective adenovirus encoding murine IFN-γ (AdIFNγ) to IFN-γ-deficient (GKO) mice. This method resulted in stable, long-lived expression of IFN-γ that could be detected in cerebrospinal fluid using ELISA and Luminex bead immunoassay. IFN-γ induced expression in the CNS of message and protein for the chemokines CXCL10 and CCL5, to levels comparable to those seen during experimental autoimmune encephalomyelitis. Other chemokines (CXCL2, CCL2, CCL3) were not induced. Mice lacking the IFN-γR showed no response, and a control viral vector did not induce chemokine expression. Chemokine expression was predominantly localized to meningeal and ependymal cells, and was also seen in astrocytes and microglia. IFN-γ-induced chemokine expression did not lead to inflammation. However, when pertussis toxin was given i.p. to mice infected with the IFN-γ vector, there was a dramatic increase in the number of T lymphocytes detected in the CNS by flow cytometry. This increase in blood-derived immune cells in the CNS did not occur with pertussis toxin alone, and did not manifest as histologically detectable inflammatory pathology. These results show that IFN-γ induces a characteristic glial chemokine response that by itself is insufficient to promote inflammation, and that IFN-γ-induced CNS chemoattractant signals can synergize with a peripheral infectious stimulus to drive T cell entry into the CNS.