Synergistic neuroprotective effects of C3a and C5a receptor blockade following intracerebral hemorrhage.
BACKGROUND
Intracerebral hemorrhage (ICH) is associated with neurological injury that may be ameliorated by a neuroprotective strategy targeting the complement cascade. We investigated the role of C5a-receptor antagonist (C5aRA) solely and in combination with C3a-receptor antagonist (C3aRA) following ICH in mice.


METHODS
Adult male C57BL/6J mice were randomized to receive vehicle, C5aRA alone or C3aRA and C5aRA 6 and 12 h after ICH, and every 12 h thereafter. A double injection technique was used to infuse 30 microL of autologous whole blood into the right striatum. A final group of mice received a sham procedure consisting only of needle insertion followed by vehicle injections. Brain water content and flow cytometry analysis for leukocyte and microglia infiltration and activation in both hemispheres were measured on day 3 post ICH. Neurological dysfunction was assessed using a Morris water-maze (MWM), a 28-point scale, and a corner test at 6, 12, 24, 48 and 72 h after ICH induction.


RESULTS
Neurological deficits were present and comparable in all three cohorts 6 h after ICH. Animals treated with C5aRA and animals treated with combined C3aRA/C5aRA demonstrated significant improvements in neurological function assessed by both the corner turn test and a 28-point neurological scale at 24, 48 and 72 h relative to vehicle-treated animals. Similarly, C5aRA and C3aRA/C5aRA-treated mice demonstrated better spatial memory retention in the Morris water-maze test compared with vehicle-treated animals (C3aRA/C5aRA: 23.4+/-2.0 s p< or =0.0001 versus vehicle: 10.0+/-1.7 s). Relative to vehicle-treated mice, the brain water content in C3aRA/C5aRA-treated mice was significantly decreased in the ipsilateral cortex and ipsilateral striatum (ipsilateral cortex: C3aRA/C5aRA: 0.755403+/-0.008 versus 0.773327+/-0.003 p=0.01 striatum: 0.752273+/-0.007 versus 0.771163+/-0.0036 p=0.02). C5aRA-treated mice and C3aRA/C5aRA-treated mice had a decreased ratio of granulocytes (CD45(+)/CD11b(+)/Ly-6G(+)) in the hemorrhagic versus non-hemorrhagic hemispheres relative to vehicle-treated animals (C5aRA: 1.78+/-0.36 p=0.02 C3aRA/C5aRA: 1.59+/-0.22 p=0.005 versus vehicle: 3.01).


CONCLUSIONS
While administration of C5aRA alone provided neuroprotection, combined C3aRA/C5aRA therapy led to synergistic improvements in neurofunctional outcome while reducing inflammatory cell infiltration and brain edema. The results of this study indicate that simultaneous blockade of the C3a and C5a receptors represents a promising neuroprotective strategy in hemorrhagic stroke.
Garrett
Matthew C
MC
Department of Neurological Surgery, Columbia University, 710 West 168th Street, New York, NY 10032, USA.
Otten
Marc L
ML
Starke
Robert M
RM
Komotar
Ricardo J
RJ
Magotti
Paola
P
Lambris
John D
JD
Rynkowski
Michal A
MA
Connolly
E Sander
ES
D000704:Analysis of Variance; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects; D001559:Benzhydryl Compounds / Q000494:pharmacology; D001834:Body Water / Q000187:drug effects; D001921:Brain / Q000187:drug effects; D001923:Brain Chemistry / Q000187:drug effects; D002543:Cerebral Hemorrhage / Q000188:drug therapy* / Q000503:physiopathology; D019610:Cytoprotection / Q000187:drug effects*; D004357:Drug Synergism; D005106:Exploratory Behavior / Q000187:drug effects; D005434:Flow Cytometry; D006098:Granulocytes / Q000187:drug effects*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D018696:Neuroprotective Agents / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D011897:Random Allocation; D044087:Receptor, Anaphylatoxin C5a / Q000037:antagonists & inhibitors*; D011951:Receptors, Complement / Q000037:antagonists & inhibitors*; D013037:Spatial Behavior / Q000187:drug effects; D013997:Time Factors
C438957:AcPhe(ornithine-Pro-cyclohexylamine-Trp-Arg); D001559:Benzhydryl Compounds; D018696:Neuroprotective Agents; D010456:Peptides, Cyclic; D044087:Receptor, Anaphylatoxin C5a; D011951:Receptors, Complement; C431907:SB 290157; D001120:Arginine