Intracerebral hemorrhage in complement C3-deficient mice

Journal of Cerebral Blood Flow & Metabolism, 2006

Activation of the complement cascade contributes to brain injury after intracerebral hemorrhage (ICH). However, a recent study found that complement C5 deficient mice had enhanced ICH-induced brain injury. The present study, therefore, investigated the role of complement C3 (which is upstream from C5) in ICH. Male complement C3 deficient and sufficient mice had an intracerebral infusion of 30-lL autologous whole blood. The mice were killed and the brains were sampled for edema, Western blotting, immunohistochemistry and histologic analysis. Behavioral tests including forelimb use asymmetry test and corner turn were also performed before and after ICH. Compared to complement C3 sufficient mice, C3 deficient mice had less brain edema, lower hemeoxygenase-1 levels, less microglia activation and neutrophil infiltration around the clot after ICH. In addition, the C3-deficient mice had less ICH-induced forelimb use asymmetry deficits compared with C3sufficient mice. These results suggest complement activation may affect heme metabolism and the inflammatory response after ICH suggesting that complement C3 is an important factor causing ICHinduced brain injury.

Stroke, 2001

Background and Purpose-The complement cascade is activated after experimental intracerebral hemorrhage (ICH). It remains unclear, however, whether depleting the complement system will improve injury resulting from ICH. This study investigated the effects of systemic complement depletion on brain edema formation after ICH. Methods-Fifty-six pentobarbital-anesthetized Sprague-Dawley rats were used. Treatment animals were complementdepleted with cobra venom factor (CVF) (intraperitoneally). Control rats received an equal volume of saline injection (intraperitoneally). In both treatment and control rats, autologous blood (100 L) was infused stereotaxically into the right basal ganglia. Rats were killed 2, 24, or 72 hours later for brain water, ion, and tumor necrosis factor-␣ (TNF-␣) measurements, for Western blot analysis, and for immunohistochemical studies. Brain edema was quantitated by wet/dry weight. TNF-␣ levels were measured by enzyme-linked immunosorbent assay. Western blot analysis was applied for C9 semiquantification. Immunohistochemistry was used to detect complement C3d, C5a, C9, and myeloperoxidase. Results-Perihematomal brain edema was reduced by systemic complement depletion at 24 hours (78.8Ϯ0.6% versus 81.5Ϯ0.8% in control, PϽ0.01) and 72 hours (81.5Ϯ1.5% versus 83.6Ϯ0.9% in control, PϽ0.05), while cerebellar water content was unaffected (78.2Ϯ0.3% versus 78.0Ϯ0.1%). Complement depletion reduced TNF-␣ production 2 hours after ICH. Immunocytochemistry showed that complement depletion significantly reduced perihematomal C9 deposition, C3d production, and the number of C5a-and myeloperoxidase-positive cells. Conclusions-Complement depletion by CVF attenuates brain edema in ICH, indicating that complement activation plays an important role in ICH-induced brain edema. Preventing complement activation may be effective in the treatment of ICH. (Stroke. 2001;32:162-167.)

Journal of Cerebral Blood Flow & Metabolism, 2007

Complement component C4 mediates C3-dependent tissue damage after systemic ischemiareperfusion injury. Activation of C3 also contributes to the pathogenesis of experimental and human traumatic brain injury (TBI); however, few data exist regarding the specific pathways (classic, alternative, and lectin) involved. Using complement knockout mice and a controlled cortical impact (CCI) model, we tested the hypothesis that the classic pathway mediates secondary damage after TBI. After CCI, C4c and C3d immunostaining were detected in cortical vascular endothelial cells in wild-type (WT) mice; however, C4c and C3d immunostaining were also detected in C1q À/À mice, and C3d immunostaining was detected in C4 À/À mice. After CCI, WT and C1q À/À mice had similar motor deficits, Morris water maze performance, and brain lesion size. Naive C4 À/À and WT mice did not differ in baseline motor performance, but C4 À/À mice had reduced postinjury motor deficits (days 1 to 7, P < 0.05) and decreased brain tissue damage (days 14 and 35, P < 0.05) versus WT. Reconstitution of C4 À/À mice with human C4 (hC4) reversed their protection against postinjury motor deficits (P < 0.05 versus vehicle), but administration of hC4 did not impair postinjury motor performance (versus vehicle) in WT mice. The protective effects of C4 À/À were functionally distinct from the classic pathway and terminal complement, as C1q À/À and C3 À/À mice had postinjury tissue damage and motor dysfunction similar to WT. Thus, C4 contributes to motor deficits and brain tissue damage after CCI by mechanism(s) fundamentally different from those involved in experimental systemic ischemia-reperfusion injury.

Experimental Neurology, 2006

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 preservedto a similar extent as in "sham"-operated miceby 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.

The FASEB Journal, 2013

Here, we examined the role of complement-derived peptide C3a in unilateral hypoxia-ischemia (HI), a model of neonatal HI encephalopathy. HI injury was induced at postnatal day 9 (P9), and loss of hippocampal tissue was determined on P31. We compared WT mice with transgenic mice expressing C3a under the control of glial fibrillary acidic protein promoter, which express biologically active C3a only in CNS and without the requirement of a priori complement activation. Further, we injected C3a peptide into the lateral cerebral ventricle of mice lacking the C3a receptor (C3aR) and WT mice and assessed HI-induced memory impairment 41 d later. We found that HI-induced tissue loss in C3a overexpressing mice was reduced by 50% compared with WT mice. C3a peptide injected 1 h after HI protected WT but not C3aR-deficient mice against HI-induced memory impairment. Thus, C3a acting through its canonical receptor ameliorates behavioral deficits after HI injury, and C3aR is a novel therapeutic target for the treatment of neonatal HI encephalopathy.-Järlestedt, K., Rousset, C. I., Ståhlberg, A., Sourkova, H., Atkins, A. L., Thornton, C., Barnum, S. R., Wetsel, R. A., Dragunow, M., Pekny, M., Mallard, C., Hagberg, H., Pekna, M. Receptor for complement peptide C3a: a therapeutic target for neonatal hypoxicischemic brain injury. FASEB J. 27, 3797-3804 (2013

Journal of neuroinflammation, 2014

Complement activation at the C3 convertase level has been associated with acute neuroinflammation and secondary brain injury after severe head trauma. The present study was designed to test the hypothesis that Cr2-/- mice, which lack the receptors CR2/CD21 and CR1/CD35 for complement C3-derived activation fragments, are protected from adverse sequelae of experimental closed head injury. Adult wild-type mice and Cr2-/- mice on a C57BL/6 genetic background were subjected to focal closed head injury using a standardized weight-drop device. Head-injured Cr2-/- mice showed significantly improved neurological outcomes for up to 72 hours after trauma and a significantly decreased post-injury mortality when compared to wild-type mice. In addition, the Cr2-/- genotype was associated with a decreased extent of neuronal cell death at seven days post-injury. Western blot analysis revealed that complement C3 levels were reduced in the injured brain hemispheres of Cr2-/- mice, whereas plasma C3 l...

Translational Stroke Research

Previous studies showed that complement activation is associated with poor functional outcome after aneurysmal subarachnoid hemorrhage (SAH). We investigated whether complement activation is underlying brain injury after aneurysmal SAH (n = 7) and if it is an appropriate treatment target. We investigated complement expression in brain tissue of aneurysmal SAH patients (n = 930) and studied the role of common genetic variants in C3 and C5 genes in outcome. We analyzed plasma levels (n = 229) to identify the functionality of a single nucleotide polymorphism (SNP) associated with outcome. The time course of C5a levels was measured in plasma (n = 31) and CSF (n = 10). In an SAH mouse model, we studied the extent of microglia activation and cell death in wild-type mice, mice lacking the C5a receptor, and in mice treated with C5-specific antibodies (n = 15 per group). Brain sections from aneurysmal SAH patients showed increased presence of complement components C1q and C3/C3b/iC3B compare...

Aging and disease, 2019

The complement system is an essential part of innate immunity, typically conferring protection via eliminating pathogens and accumulating debris. However, the defensive function of the complement system can exacerbate immune, inflammatory, and degenerative responses in various pathological conditions. Cumulative evidence indicates that the complement system plays a critical role in the pathogenesis of ischemic brain injury, as the depletion of certain complement components or the inhibition of complement activation could reduce ischemic brain injury. Although multiple candidates modulating or inhibiting complement activation show massive potential for the treatment of ischemic stroke, the clinical availability of complement inhibitors remains limited. The complement system is also involved in neural plasticity and neurogenesis during cerebral ischemia. Thus, unexpected side effects could be induced if the systemic complement system is inhibited. In this review, we highlighted the recent concepts and discoveries of the roles of different kinds of complement components, such as C3a, C5a, and their receptors, in both normal brain physiology and the pathophysiology of brain ischemia. In addition, we comprehensively reviewed the current development of complement-targeted therapy for ischemic stroke and discussed the challenges of bringing these therapies into the clinic. The design of future experiments was also discussed to better characterize the role of complement in both tissue injury and recovery after cerebral ischemia. More studies are needed to elucidate the molecular and cellular mechanisms of how complement components exert their functions in different stages of ischemic stroke to optimize the intervention of targeting the complement system.

Frontiers in Immunology, 2015

Neurochemical Research

Ischemic stroke is a major cause of disability. No efficient therapy is currently available, except for the removal of the occluding blood clot during the first hours after symptom onset. Loss of function after stroke is due to cell death in the infarcted tissue, cell dysfunction in the peri-infarct region, as well as dysfunction and neurodegeneration in remote brain areas. Plasticity responses in spared brain regions are a major contributor to functional recovery, while secondary neurodegeneration in remote regions is associated with depression and impedes the long-term outcome after stroke. Hypoxic-ischemic encephalopathy due to birth asphyxia is the leading cause of neurological disability resulting from birth complications. Despite major progress in neonatal care, approximately 50% of survivors develop complications such as mental retardation, cerebral palsy or epilepsy. The C3a receptor (C3aR) is expressed by many cell types including neurons and glia. While there is a body of ...