Complement C5 Contributes to Brain Injury After Subarachnoid Hemorrhage

Abstract

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 compared to controls. The complement component 5 (C5) SNP correlated with C5a plasma levels and poor disease outcome. Serial measurements in CSF revealed that C5a was > 1400-fold increased 1 day after aneurysmal SAH and then gradually decreased. C5a in plasma was 2-fold increased at days 3-10 after aneurysmal SAH. In the SAH mouse model, we observed a ≈ 40% reduction in both microglia activation and cell death in mice lacking the C5a receptor, and in mice treated with C5-specific antibodies. These data show that C5 contributes to brain injury after experimental SAH, and support further study of C5-specific antibodies as novel treatment option to reduce brain injury and improve prognosis after aneurysmal SAH.

CompLement C5 Antibodies for decreasing brain injury after aneurysmal Subarachnoid Hemorrhage (CLASH): study protocol for a randomized controlled phase II clinical trial

“…[1,[3][4][5] In experimental SAH studies, treatment with complement C5 antibodies shortly after SAH reduced brain injury with approximately 40%. [13] Complement component C5 may be an important target to reduce brain injury and hereby improve outcome after aSAH. The CLASH trial is the rst phase II trial to investigate the pharmacodynamic e cacy and safety of eculizumab in aSAH patients.…”

“…We decided on repeated drug administration with a high dose of eculizumab to prevent a wash-out effect and because the C5a concentration in the cerebrospinal uid (CSF) of aSAH patients is >1400 times increased one day after ictus compared to the C5a concentration in CSF from patients with unruptured intracranial aneurysms. [13] To decrease the risk of (meningococcal) infection due to eculizumab treatment, patients in the intervention group receive prophylactic treatment with cipro oxacin during the rst 4 weeks after ictus. During the recruitment phase, after inclusion of the 6th patient, we changed our protocol based on a serious adverse event (SAE) that occurred (cerebral fungal infection in patient with external ventricular shunt).…”

“…[1,12] C5 speci c antibodies, which prevent the formation of C5a, have been shown to reduce microglia activation and cell death by 40% in an SAH mouse model. [13] C5 antibodies (eculizumab) are already used for other in ammatory diseases such as neuromyelitis optica and Anti-AChR Antibody-Positive generalized Anti-AChR Antibody-Positive generalized myasthenia gravis. [14,15] The aim of this trial is to investigate the pharmacodynamic e cacy (proof-of-concept) and safety of eculizumab in patients with aSAH.…”

CompLement C5 Antibodies for decreasing brain injury after aneurysmal Subarachnoid Haemorrhage (CLASH): study protocol for a randomised controlled phase II clinical trial

“…Complement components C3a and C5a are proinflammatory anaphylatoxins that can induce vasoconstriction and activate coagulation [9][10][11], processes that have been implicated in the pathophysiology of early brain injury and delayed cerebral ischaemia [1,12]. C5specific antibodies, which prevent the formation of C5a, have been shown to reduce microglia activation and cell death by 40% in an SAH mouse model [13]. C5 antibodies (eculizumab) are already used for other inflammatory diseases such as neuromyelitis optica and myasthenia gravis [14,15].…”

CompLement C5 Antibodies for decreasing brain injury after aneurysmal Subarachnoid Haemorrhage (CLASH): study protocol for a randomized controlled phase II clinical trial

“…As this is the rst trial to investigate the use of eculizumab in aSAH patients, the effective dosing regimen for aSAH patients is unknown. In our previous study, we found that the C5a concentration in cerebrospinal uid (CSF) of aSAH patients is highly increased (>1400 times) compared to the C5a concentration in CSF from patients with unruptured intracranial aneurysms [13]. We therefore decided upon administration of a high dose of eculizumab (1200 mg) with repeated drug administration to prevent a wash-out effect.…”