title: Mechanism of alternative complement pathway dysregulation by a phosphorothioate oligonucleotide in monkey and human serum.
abstract: The species sensitivity and mechanism of complement pathway activation by a phosphorothioate oligonucleotide were investigated in monkey and human serum. Increasing concentrations of a phosphorothioate oligonucleotide, ISIS 2302, were incubated in either monkey or human serum. Complement activation in monkey serum was selective for the alternative pathway and occurred at concentrations ≥ 50 μg/mL ISIS 2302. By comparison, complement activation in human serum was absent. A similar difference in sensitivity for activation was also observed for a representative 2'-methoxyethyl (MOE)-modified oligonucleotide. The absence of oligonucleotide-induced complement activation was also observed in dogs. Protein binding with ISIS 2302 and enzyme competition studies suggested that factor H was important in oligonucleotide-mediated complement activation process, and addition of factor H to serum effectively prevented the activation in monkey serum. Furthermore, based on the immunoassay for factor H, there was an apparent decrease in factor H concentration as the ISIS 2302 concentration increased. This result suggests that ISIS 2302 binds to factor H and interferes with the factor H antibody from the immunoassay. Factor H is a regulatory protein that limits alternative pathway activation. Disruption of factor H interaction with C3 convertase by oligonucleotide could promote activation in this pathway.
authors.affiliation: 1 Isis Pharmaceuticals, Inc. , Carlsbad, California.
authors.forename: Scott P
authors.initials: SP
authors.lastname: Henry
authors.forename: Mark A
authors.initials: MA
authors.lastname: Jagels
authors.forename: Tony E
authors.initials: TE
authors.lastname: Hugli
authors.forename: Sheri
authors.initials: S
authors.lastname: Manalili
authors.forename: Richard S
authors.initials: RS
authors.lastname: Geary
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Giclas
authors.forename: Arthur A
authors.initials: AA
authors.lastname: Levin
mesh_terms: D000818:Animals; D003167:Complement Activation / Q000187:drug effects*; D050577:Complement C3-C5 Convertases / Q000737:chemistry / Q000378:metabolism; D017242:Complement Factor H / Q000737:chemistry / Q000378:metabolism*; D003170:Complement Pathway, Alternative / Q000187:drug effects; D004285:Dogs; D005765:Gastrointestinal Agents / Q000097:blood* / Q000276:immunology / Q000493:pharmacokinetics; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood* / Q000276:immunology / Q000493:pharmacokinetics; D007275:Injections, Intravenous; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008297:Male; D020319:Oligodeoxyribonucleotides, Antisense / Q000097:blood* / Q000276:immunology / Q000493:pharmacokinetics; D054735:Phosphorothioate Oligonucleotides / Q000097:blood* / Q000276:immunology / Q000493:pharmacokinetics; D011485:Protein Binding; D013045:Species Specificity
chemical_list: D005765:Gastrointestinal Agents; D007166:Immunosuppressive Agents; D020319:Oligodeoxyribonucleotides, Antisense; D054735:Phosphorothioate Oligonucleotides; D017242:Complement Factor H; D050577:Complement C3-C5 Convertases; C089753:alicaforsen