title: Effects of scleroderma antibodies and pooled human immunoglobulin on anal sphincter and colonic smooth muscle function.
abstract: OBJECTIVE
  Patients with systemic sclerosis (SSc) have impairments in gastrointestinal smooth muscle function. The disorder has been associated with circulating antibodies to cholinergic muscarinic the type-3 receptor (M(3)-R). We investigated whether it is possible to neutralize these antibodies with pooled human IgGs (pooledhIgG).
  
  
  METHODS
  We studied the effects of IgGs purified from patients with SSc (SScIgGs) on cholinergic nerve stimulation in rat colon tissues. We also examined the effects of SScIgGs on M(3)-R activation by bethanechol (BeCh), M(3)-R occupancy, and receptor binding using immunofluorescence, immunoblot, and enzyme-linked immunosorbent analyses of human internal anal sphincter (IAS) smooth muscle cells, before and after administration of pooledhIgG. Functional displacement of M(3)-R occupancy by the SScIgGs was compared with that of other IgGs during the sustained phase of BeCh-induced contraction of intact smooth muscles from rats.
  
  
  RESULTS
  SScIgG significantly attenuated neurally mediated contraction and acetylcholine release in rat colon as well as BeCh-induced sustained contraction of the IAS smooth muscle. In immunofluorescence analysis, SScIgG co-localized with M(3)-R. In immunoblot and enzyme-linked immunosorbent analyses, M(3)-R loop-2 peptide and human IAS SMC membrane lysates bound significant amounts of SScIgG, compared with IgGs from healthy individuals and pooledhIgG. Binding was attenuated significantly by application of pooledhIgG, which by itself had no significant effect. Incubation of samples with pooledhIgG, or mixing pooledhIgG with SScIgG before administration to tissues, significantly reduced binding of SScIgG, indicating that pooledhIgG prevents SScIgG blockade of M(3)-R.
  
  
  CONCLUSIONS
  In studies of rat and human tissues, pooled human IgG prevent and reverses the cholinergic dysfunction associated with the progressive gastrointestinal manifestations of SSc by neutralizing functional M(3)-R antibodies present in the circulation of patients with SSc.
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Jagmohan
authors.initials: J
authors.lastname: Singh
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Sidney
authors.initials: S
authors.lastname: Cohen
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Vaibhav
authors.initials: V
authors.lastname: Mehendiratta
authors.affiliation: Jefferson Institute of Molecular Medicine and Scleroderma Center, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Fabian
authors.initials: F
authors.lastname: Mendoza
authors.affiliation: Jefferson Institute of Molecular Medicine and Scleroderma Center, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Jimenez
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Dimarino
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Thomas Jefferson University, Philadelphia, Pennsylvania. Electronic address: satish.rattan@jefferson.edu.
authors.forename: Satish
authors.initials: S
authors.lastname: Rattan
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D001003:Anal Canal / Q000187:drug effects* / Q000503:physiopathology; D000818:Animals; D001323:Autoantibodies / Q000494:pharmacology; D018723:Bethanechol / Q000494:pharmacology; D003106:Colon / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D009197:Myenteric Plexus / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D043587:Receptor, Muscarinic M3 / Q000187:drug effects* / Q000276:immunology* / Q000378:metabolism; D012595:Scleroderma, Systemic / Q000276:immunology* / Q000503:physiopathology
chemical_list: D001323:Autoantibodies; D007074:Immunoglobulin G; D008565:Membrane Proteins; D010455:Peptides; D043587:Receptor, Muscarinic M3; D018723:Bethanechol; D000109:Acetylcholine