title: Candidate inhibitors of porcine complement.
abstract: Therapeutic complement inhibition is a promising strategy for treatment of a number of diseases as judged from rodent studies. The species distance from rodents to humans may limit the clinical relevance of these studies. The pig is an alternative animal for studies of human diseases like sepsis and ischemia/reperfusion injury. However, available complement inhibitors for use in pigs are scarce. The aim of the present study was to investigate and compare the efficacy of selected candidate inhibitors of porcine complement in vitro for possible future application in vivo. Sera from three different pigs were each incubated with three different activators of the complement system (zymosan, heat-aggregated immunoglobulin G (HAIGG) and Escherichia coli). Three groups of complement inhibitor candidates were tested: serine protease inhibitors (FUT-175 and C1-inhibitor), monoclonal antibodies (anti-factor B (fB) and anti-factor D (fD)) and a recombinant regulatory protein (vaccinia virus complement control protein (VCP)). Read-out was the terminal C5b-9 complement complex (TCC). The serine protease inhibitors FUT-175 and C1-inhibitor dose-dependently inhibited TCC formation in zymosan-, HAIGG- and E. coli-activated porcine sera, but with different efficacy. Complete inhibition of TCC was obtained using 0.2 mg/mL FUT-175, but required 16 mg/mL of C1-inhibitor. The monoclonal anti-fB and -fD antibodies both inhibited TCC formation dose-dependently, but in different ways. Anti-fB at high dose (1 mg/mL) completely inhibited TCC formation in sera activated with zymosan and virtually completely in sera activated with HAIGG, but not in sera activated with E. coli. Anti-fD inhibited all three activators at low dose (0.05 mg/mL), and approximately 50% TCC reduction was obtained. The recombinant complement regulatory protein VCP efficiently and dose-dependently inhibited TCC formation with a complete inhibition found at 0.05 mg/mL for all three activators. All candidates tested inhibited porcine complement activation, but in different ways and to different degrees. Of the complement-specific candidates, VCP inhibited all activators completely at low doses.
authors.affiliation: Institute of Immunology, Rikshospitalet-Radiumhospitalet Medical Center and University of Oslo, N-0027 Oslo, Norway. ebbebt@medisin.uio.no
authors.forename: Ebbe B
authors.initials: EB
authors.lastname: Thorgersen
authors.forename: Yohannes T
authors.initials: YT
authors.lastname: Ghebremariam
authors.forename: Joshua M
authors.initials: JM
authors.lastname: Thurman
authors.forename: Michael
authors.initials: M
authors.lastname: Fung
authors.forename: Erik Waage
authors.initials: EW
authors.lastname: Nielsen
authors.forename: V Michael
authors.initials: VM
authors.lastname: Holers
authors.forename: Girish J
authors.initials: GJ
authors.lastname: Kotwal
authors.forename: Tom Eirik
authors.initials: TE
authors.lastname: Mollnes
mesh_terms: D000818:Animals; D003167:Complement Activation / Q000187:drug effects*; D051056:Complement Inactivating Agents / Q000737:chemistry / Q000494:pharmacology*; D015938:Complement Membrane Attack Complex / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D012377:Rodentia; D013552:Swine
chemical_list: D051056:Complement Inactivating Agents; D015938:Complement Membrane Attack Complex