Selective Oxidation of DNA Topoisomerase 1 Induces Systemic Sclerosis in the Mouse

Abstract

Systemic sclerosis (SSc) is a connective tissue disorder of great clinical heterogeneity. Its pathophysiology remains unclear. Our aim was to evaluate the relative roles of reactive oxygen species (ROS) and of the immune system using an original model of SSc. BALB/c and immunodeficient BALB/c SCID mice were injected s.c. with prooxidative agents (hydroxyl radicals, hypochlorous acid, peroxynitrites, superoxide anions), bleomycin, or PBS everyday for 6 wk. Skin and lung fibrosis were assessed by histological and biochemical methods. Autoantibodies were detected by ELISA. The effects of mouse sera on H 2 O 2 production by endothelial cells and on fibroblast proliferation, and serum concentrations in advanced oxidation protein products (AOPP) were compared with sera from patients with limited or diffuse SSc. We observed that s.c. peroxynitrites induced skin fibrosis and serum anti-CENP-B Abs that characterize limited SSc, whereas hypochlorite or hydroxyl radicals induced cutaneous and lung fibrosis and anti-DNA topoisomerase 1 autoantibodies that characterize human diffuse SSc. Sera from hypochlorite-or hydroxyl radical-treated mice and of patients with diffuse SSc contained high levels of AOPP that triggered endothelial production of H 2 O 2 and fibroblast hyperproliferation. Oxidized topoisomerase 1 recapitulated the effects of whole serum AOPP. SCID mice developed an attenuated form of SSc, demonstrating the synergistic role of the immune system with AOPP in disease propagation. We demonstrate a direct role for ROS in SSc and show that the nature of the ROS dictates the form of SSc. Moreover, this demonstration is the first that shows the specific oxidation of an autoantigen directly participates in the pathogenesis of an autoimmune disease. The Journal of Immunology, 2009, 182: 5855-5864. S ystemic sclerosis (SSc)4 is a connective tissue disorder of unknown etiology characterized by vascular hyperreactivity, fibrosis of skin and visceral organs, and immunological alterations, including a distinct pattern of autoantibodies in the sera (1). The mechanisms that determine the clinical manifestations of the disease remain unclear (2). Several reports have suggested that reactive oxygen species (ROS) are involved in the pathogenesis of SSc (3-9). Indeed, skin fibroblasts from SSc patients spontaneously produce large amounts of ROS that trigger collagen synthesis (7, 10). In addition, autoantibodies found in SSc patients against the platelet-derived growth factor receptor expressed on fibroblasts also induce the production of ROS (11). Recently, we have demonstrated that sera from patients with SSc could induce not only the production of ROS by endothelial cells but also the hyperproliferation of fibroblasts (6).However, no direct proof for the involvement of oxidative stress in SSc pathogenesis has been brought forth to date. Moreover, the origin and nature of the oxidative stress remain to be elucidated. Environmental factors, and in particular silica dust, may be involved, which generate hydroxyl radicals (OH⅐) (12...

CROSSTALK BETWEEN Nrf2 AND NOTCH SIGNALING

“…In these mice, skin fibrosis is induced by intradermal generation of HOCl that oxidizes skin proteins. This stress leads to the stimulation and proliferation of fibroblasts and to the overproduction of collagen and then to fibrosis [96]. The Keap1-Nrf2-ARE pathway likely contributes to this process.…”

Increasing levels of serum antioxidant status, total antioxidant power, in systemic sclerosis

“…Furthermore, recent study demonstrated the direct role for ROS in the pathogenesis of SSc including autoantibody and collagen production in mouse model and human skin [20]. These results suggest that oxidative stress plays a role for development of SSc.…”

Up-regulation of Gr1+CD11b+ cell population in the spleen of NaClO-administered mice works to repair skin wounds

“…Servettaz et al developed the murine model of dermal sclerosis by repeated injection of ROS-inducing agents, including NaClO [23]. We have also reported that the ROS-producing agent Bleomycin induces systemic sclerosis [24], although Servettaz et al and our group have not examined the contribution of neutrophils to disease progression.…”