IgG from patients with systemic sclerosis bind to DNA antitopoisomerase 1 in normal human fibroblasts extracts

Mathieu C Tamby¹, Amélie Servettaz¹, Nicolas Tamas¹, Joseph Reinbolt², Frédéric Caux³, Olivier Meyer⁴, Yannick Allanore⁵, André Kahan⁵, Loïc Guillevin⁶, Luc Mouthon^1,6

¹Paris-Descartes University, Faculty of Medicine, UPRES-EA 4058, Paris, France; ²UPR 9002, Centre National de la Recherche Scientifique, Strasbourg, France; ³UPRES EA 2436, Paris-Nord University, Bobigny, France; ⁴Rheumatology Department, Bichat Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France; ⁵Rheumatology A Department, Cochin Hospital, AP-HP; ⁶Paris-Descartes University, Faculty of Medicine, Department of Internal Medicine and French Reference Center for Necrotizing Vasculitides and Systemic Sclerosis, Cochin Hospital, AP-HP, Paris, France

Abstract: By using a semi-quantitative immunoblotting technique, we have analyzed serum immunoglobulin G (IgG) reactivities of patients with limited cutaneous systemic sclerosis and anticentromere antibodies, patients with diffuse systemic sclerosis and antitopoisomerase 1 antibodies, patients with diffuse systemic sclerosis without antitopoisomerase 1 or anticentromere antibodies and age- and gender-matched healthy controls with normal human skin fibroblasts and HEp-2 cells antigens. Serum IgG reactivities of patients with diffuse systemic sclerosis and antitopoisomerase 1 antibodies differed significantly from those of healthy controls or systemic sclerosis patients in other groups for reactivity with fibroblast proteins. IgG from patients with antitopoisomerase 1 antibodies bound to a 90 kDa fibroblast band and to a 100 kDa protein band in a HEp-2 cell protein extract. These two bands were further identified as DNA topoisomerase 1. Our results indicate that IgG from patients with diffuse systemic sclerosis bind DNA topoisomerase 1 in normal human fibroblasts extracts.

Keywords: systemic sclerosis, autoantibodies, IgG, fibroblast, DNA topoisomerase 1