ATM and systemic sclerosis: IgG from ATA+patients inhibited TOPO-I in vitro, and we previously showed that IgG ATA+induced profibrotic profiles in normal dermal fibroblasts.5 45 Pathogenic mechanisms of ANA in SSc such as interaction between immune complexes or Aab are suspected.46 47 Nevertheless, the capacity of ANA to directly interact with their intracellular antigens remains largely unknown.2