ABSTRACT
The complement system represents an important mediator of neuroinflammation in traumatic brain injury. We have previously shown that transgenic mice with central nervous system-targeted overexpression of Crry, a potent murine complement inhibitor at the level of C3 convertases, are protected from complement-mediated neuropathological sequelae in brain-injured mice. This knowledge was expanded in the present study to a pharmacological approach by the use of a recombinant Crry molecule (termed Crry-Ig) which was recently made available in a chimeric form fused to the non-complement fixing mouse IgG1 Fc region. In a standardized model of closed head injury in mice, the systemic injection of 1 mg Crry-Ig at 1 h and 24 h after trauma resulted in a significant neurological improvement for up to 7 days, as compared to vehicle-injected control mice (P < 0.05, repeated measures ANOVA). Furthermore, the extensive neuronal destruction seen in the hippocampal CA3/CA4 sublayers in head-injured mice with vehicle injection only was shown to be preserved - to a similar extent as in "sham"-operated mice - by the posttraumatic injection of Crry-Ig. Real-time RT-PCR analysis revealed that the post-treatment with Crry-Ig resulted in a significant up-regulation of candidate neuroprotective genes in the injured hemisphere (Bcl-2, C1-Inh, CD55, CD59), as compared to the vehicle control group (P < 0.01, unpaired Student's t test). Increased intracerebral Bcl-2 expression by Crry-Ig treatment was furthermore confirmed at the protein level by Western blot analysis. These data suggest that pharmacological complement inhibition represents a promising approach for attenuation of neuroinflammation and secondary neurodegeneration after head injury.
