title: Complement activation-related cardiac anaphylaxis in pigs: role of C5a anaphylatoxin and adenosine in liposome-induced abnormalities in ECG and heart function.
abstract: Cardiac anaphylaxis is a severe, life-threatening manifestation of acute hypersensitivity reactions to allergens and drugs. Earlier studies highlighted an amplifying effect of locally applied C5a on the process; however, the role of systemic complement (C) activation with C5a liberation in blood has not been explored to date. In the present study, we used the porcine liposome-induced cardiopulmonary distress model for 1) characterizing and quantifying peripheral C activation-related cardiac dysfunction; 2) exploring the role of C5a in cardiac abnormalities and therapeutic potential of C blockage by soluble C receptor type 1 (sCR1) and an anti-C5a antibody (GS1); and 3) elucidating the role of adenosine and adenosine receptors in paradoxical bradycardia, one of the symptoms observed in this model. Pigs were injected intravenously with different liposomes [Doxil and multilamellar vesicles (MLV)], zymosan, recombinant human (rhu) C5a, and adenosine, and the ensuing hemodynamic and cardiac changes (hypotension, tachy- or bradycardia, arrhythmias, ST-T changes, ventricular fibrillation, and arrest) were quantified by ranking on an arbitrary scale [cardiac abnormality score (CAS)]. There was significant correlation between CAS and C5a production by liposomes in vitro, and the liposome-induced cardiac abnormalities were partially or fully reproduced with zymosan, rhuC5a, adenosine, and the selective adenosine A1 receptor agonist cyclopentyl-adenosine. The use of C nonactivator liposomes or pretreatment of pigs with sCR1 or GS1 attenuated the abnormalities. The selective A1 blocker cyclopentyl-xanthine inhibited bradycardia without influencing hypotension, whereas the A(2) blocker 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM-24135) had no such effect. These data suggest that 1) systemic C activation can underlie cardiac anaphylaxis, 2) C5a plays a causal role in the reaction, 3) adenosine action via A1 receptors may explain paradoxical bradycardia, and 4) inhibition of C5a formation or action or of A1-receptor function may alleviate the acute cardiotoxicity of liposomal drugs and other intravenous agents that activate C.
authors.affiliation: Division of Retrovirology, Department of Vaccine Production and Delivery, United States Military Human Immunodeficiency Virus Research Program, 1600 E. Gude Dr., Rockville, Maryland 20850, USA. jszebeni@hivresearch.org
authors.forename: János
authors.initials: J
authors.lastname: Szebeni
authors.forename: Lajos
authors.initials: L
authors.lastname: Baranyi
authors.forename: Sándor
authors.initials: S
authors.lastname: Sávay
authors.forename: Michael
authors.initials: M
authors.lastname: Bodó
authors.forename: János
authors.initials: J
authors.lastname: Milosevits
authors.forename: Carl R
authors.initials: CR
authors.lastname: Alving
authors.forename: Rolf
authors.initials: R
authors.lastname: Bünger
mesh_terms: D000241:Adenosine; D000707:Anaphylaxis / Q000276:immunology*; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000276:immunology*; D003167:Complement Activation / Q000276:immunology*; D004195:Disease Models, Animal; D004562:Electrocardiography / Q000187:drug effects; D008081:Liposomes; D044087:Receptor, Anaphylatoxin C5a / Q000276:immunology*; D018047:Receptors, Purinergic P1; D013552:Swine; D018487:Ventricular Dysfunction, Left / Q000139:chemically induced / Q000276:immunology*
chemical_list: D008081:Liposomes; D044087:Receptor, Anaphylatoxin C5a; D018047:Receptors, Purinergic P1; D000241:Adenosine