Immune-to-brain signalling: the role of cerebral CD163-positive macrophages.
Systemic inflammation induces cytokine synthesis within the central nervous system. This results in sickness behaviour and may exacerbate ongoing neuroinflammatory disease. The precise mechanisms underlying the relay of signal from the periphery to the central nervous system are not entirely understood. CD163-positive macrophages occupy a unique position at the blood-brain barrier and upregulate prostaglandin-synthesizing enzymes in response to systemic inflammation. This finding suggests that they might play a role in signalling inflammation to the central nervous system. However, here we demonstrate that de novo brain cytokine transcription during systemic endotoxaemia may be prostaglandin-independent. We therefore set out to interrogate more directly the role of CD163-positive macrophages in immune-to-brain signalling. Intracerebroventricular injections of clodronate liposomes were used to selectively deplete CD163-positive macrophages. We show that de novo brain cytokine synthesis during systemic endotoxaemia persists in the absence of CD163-positive macrophages. Cerebral endothelial cells outnumber CD163-positive macrophages and are arguably better situated to signal circulating inflammatory stimuli to the brain.
CNS Inflammation Group, School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK. I.Galea@soton.ac.uk
Ian
I
Galea
Leigh M
LM
Felton
Sara
S
Waters
Nico
N
van Rooijen
V Hugh
VH
Perry
Tracey A
TA
Newman
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism*; D001831:Body Temperature / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000494:pharmacology; D002540:Cerebral Cortex / Q000166:cytology*; D004002:Clodronic Acid / Q000494:pharmacology; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D007276:Injections, Intraventricular / Q000379:methods; D008081:Liposomes / Q000008:administration & dosage; D008264:Macrophages / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013997:Time Factors; D000098902:CD163 Antigen
D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D050071:Bone Density Conservation Agents; D000098902:CD163 Antigen; D016207:Cytokines; D008081:Liposomes; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D004002:Clodronic Acid