Dilated Cardiomyopathy Defines Serum Autoantibodies Against G-Protein-Coupled Cardiovascular Receptors

Abstract

In ordcr furthcr to identify thc prcvalcncc of anti-rcccptor autoantibodics in thc scra of paticnts with dilated cardiomyopathy (DCM), we attcmptcd to dctcct autoantibodics against a scrics of G-protcin-coupled cardiovascular receptors in a wcll-defined population of DCM paticnts from Japan. Pcptidcs corresponding to the sequences of thc sccond cxtraccllular loops of thc human P,and P2 adrcnoccptors, a, adrcnoccptors, M2 muscarinic acctylcholinc rcccptors and angiotcnsin 11-1 (ATI) rcccptors wcrc used as antigens in an cnzymc imrnunoassay to scrccn the scra from patients with DCM (n = 28). Ninc scra from patients with DCM (32%) and 2 scra from hcalthy subjects (9%) rccognizcd thc PI adrcnoccptor pcptidc. Tcn scra from paticnts (36%) and 3 scra from hcalthy subjects (I 3%)) rccognizcd the M2 rcccptor pcptidc. Thirty-six pcr ccnt of the patients with autoantibody against thc PI adrcnoccptor had autoantibody against thc M2 rcccptor. Howcvcr, no significantly high frequencies of autoantibodies against the P2 adrcnoccptor, a, adrcnoccptor and AT1 rcccptor wcrc found in DCM patients. Our results dcmonstratc that a subgroup of paticnts with DCM have a spccific spcctrum of autoantibodics which arc spccifically dircctcd against thc second cxtraccllular loops of thc PI adrcnoccptors and M2 muscarinic rcccptors rather than othcr cardiovascular rcccptors.

Key Words:

• Dilated cardiomyopathy
• autoimmunity
• G-protcin-coupled rcccptors
• cnzymc immunoassay