Complement receptor 2 is up regulated in the spinal cord following nerve root injury and modulates the spinal cord response.
BACKGROUND
Activation of the complement system has been implicated in both acute and chronic states of neurodegeneration. However, a detailed understanding of this complex network of interacting components is still lacking.


METHODS
Large-scale global expression profiling in a rat F2(DAxPVG) intercross identified a strong cis-regulatory influence on the local expression of complement receptor 2 (Cr2) in the spinal cord after ventral root avulsion (VRA). Expression of Cr2 in the spinal cord was studied in a separate cohort of DA and PVG rats at different time-points after VRA, and also following sciatic nerve transection (SNT) in the same strains. Consequently, Cr2 (-/-) mice and Wt controls were used to further explore the role of Cr2 in the spinal cord following SNT. The in vivo experiments were complemented by astrocyte and microglia cell cultures.


RESULTS
Expression of Cr2 in naïve spinal cord was low but strongly up regulated at 5-7 days after both VRA and SNT. Levels of Cr2 expression, as well as astrocyte activation, was higher in PVG rats than DA rats following both VRA and SNT. Subsequent in vitro studies proposed astrocytes as the main source of Cr2 expression. A functional role for Cr2 is suggested by the finding that transgenic mice lacking Cr2 displayed increased loss of synaptic nerve terminals following nerve injury. We also detected increased levels of soluble CR2 (sCR2) in the cerebrospinal fluid of rats following VRA.


CONCLUSIONS
These results demonstrate that local expression of Cr2 in the central nervous system is part of the axotomy reaction and is suggested to modulate subsequent complement mediated effects.
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden. rickard.lindblom@ki.se.|Department of Cardiothoracic Surgery and Anaesthesia, Uppsala University Hospital, Uppsala, Sweden. rickard.lindblom@ki.se.|Neuroimmunology Unit L8:04 CMM, Karolinska University Hospital, 171 76, Stockholm, Sweden. rickard.lindblom@ki.se.
Rickard P F
RP
Lindblom
Department of Neuroscience, Division of Neuronal Regeneration, Karolinska Institutet, Stockholm, Sweden.
Alexander
A
Berg
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Mikael
M
Ström
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Shahin
S
Aeinehband
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Cecilia A
CA
Dominguez
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Faiez
F
Al Nimer
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Nada
N
Abdelmagid
Experimental Genetics of Cardiovascular Diseases, Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
Matthias
M
Heinig
Department of Neuroscience, Division of Neuronal Regeneration, Karolinska Institutet, Stockholm, Sweden.
Johan
J
Zelano
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Karin
K
Harnesk
Experimental Genetics of Cardiovascular Diseases, Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
Norbert
N
Hübner
Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
Bo
B
Nilsson
Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala, Sweden.
Kristina Nilsson
KN
Ekdahl
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Margarita
M
Diez
Department of Neuroscience, Division of Neuronal Regeneration, Karolinska Institutet, Stockholm, Sweden.
Staffan
S
Cullheim
Department of Clinical Neuroscience, Neuroimmunology Unit, Karolinska Institutet, Stockholm, Sweden.
Fredrik
F
Piehl
D000704:Analysis of Variance; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism; D039481:CD11b Antigen / Q000378:metabolism; D002478:Cells, Cultured; D007839:Functional Laterality; D053263:Gene Regulatory Networks; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008822:Mice, Transgenic; D046228:Microarray Analysis; D017628:Microglia / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017464:Receptors, Complement 3d / Q000235:genetics / Q000378:metabolism*; D020426:Sciatic Neuropathy / Q000378:metabolism / Q000473:pathology; D013116:Spinal Cord / Q000378:metabolism*; D013126:Spinal Nerve Roots / Q000293:injuries* / Q000473:pathology*; D016708:Synaptophysin / Q000378:metabolism; D015854:Up-Regulation / Q000502:physiology*
D015703:Antigens, CD; D039481:CD11b Antigen; D005904:Glial Fibrillary Acidic Protein; D012333:RNA, Messenger; D017464:Receptors, Complement 3d; D016708:Synaptophysin