AN AGONIST ANTIBODY OF THE NICOTINIC CHOLINERGIC RECEPTORS ??-7 SUBUNIT IMPROVES SURVIVAL IN MURINE ENDOTOXEMIA

Abstract

Stimulation of α7 subunit of nicotinic acetylcholine receptors (α7nAChR) can suppress inflammatory mediator release from macrophages. Nicotine, a non-specific agonist of nicotinic acetylcholine receptors, inhibits the release of TNF and HMGB1 and prevents lethality in experimental sepsis (Nat Med, 2004, 10:1216). Objective: To more specifically determine the effect of activation of the α7 subunit on proinflammatory cytokine release, we developed a rabbit polyclonal antibody (Ab1918), which acts as an α7nAChR agonist. Results: In vitro, Ab1918 dose-dependently inhibited the release of TNF, inhibited nuclear HMGB1 translocation and suppressed HMGB1 levels in the cell culture supernatant following endotoxin stimulation of murine macrophage-like RAW264.7 cells. Ab1918 prevented activation of the NF-κB pathway and inhibited the secretion of TNF via an α7nAChR-dependent pathway. Intraperitoneal (i.p.) injection of Ab1918 (7.2 mg/kg), 12h before endotoxin infusion (7.0mg/kg, i.p.), significantly reduced TNF in spleen and reduced serum TNF levels in endotoxemic mice. To study the efficacy of Ab1918 in murine sepsis, mice were subjected to the cecal ligation and puncture (CLP) technique and treated (i.p.) with Ab1918 twice daily, for 3 days, beginning 24 h after surgery. Ab1918 significantly improved survival in this preclinical model of sepsis (control IgG survival: 7.1%; vs. Ab1918 (7.2mg/kg) survival: 53.3%, P < 0.005). The protective effect was associated with lower serum levels of HMGB1 in Ab1918-treated mice. Conclusion: Our results demonstrate the potential efficacy of an α7nAChR agonist antibody in the treatment of sepsis. This study was funded in part by NIH/NIGMS, DARPA, GCRCGrant# M01 RR018535