Neuropharmacology

Biography

Biography: Atsuyoshi Shimada

Abstract

The immune system modulates higher functions of the brain under non-inflammatory conditions. However, how immune cells interact with brain parenchymal cells remains to be determined. Using bone marrow chimeric mice in which the recipients’ immune system was reconstituted by marrow cells derived from GFP-transgenic mice by syngeneic intra-bone marrow-bone marrow transplantation (IBM-BMT), we examined the distribution, density and differentiation of donor-derived marrow cells in the brain parenchyma 2 weeks and 1, 4 and 8 months after IBM-BMT. Marrow-derived cells started to populate discrete brain regions from 1 to 4 months after IBM-BMT, exhibited ramified morphology and expressed Iba-1, indicating the myeloid lineage. Most of these discrete regions were adjacent to the attachments of choroid plexus that comprised thinned brain parenchyma consisting of astrocytic processes in the narrow channel between the ependyma and pia. These specific portions of astrocytic processes expressed CX3CL1, a myeloid cell-attracting chemokine. In the choroid plexus stroma, not only Iba-1-immunopositive myeloid cells but also non-myeloid CXCL12-expressing cells were of bone marrow-origin. Transcripts of CX3CL1, CXCL12 and their related molecules such as CX3CR1, ADAM10 and CXCR4 were detected in the tissue consisting of the choroid plexus, the attachments and adjacent brain parenchyma. Thus, bone marrow cells selectively enter the discrete brain regions via the attachments of choroid plexus and differentiate into ramified myeloid cells. CX3CL1 in the attachments of choroid plexus and CXCL12 in the choroid plexus stroma may be involved in these brain-immune interactions.