Niclosamide Prevents Systemic Sclerosis in a Reactive Oxygen Species–Induced Mouse Model

Systemic sclerosis (SSc) is a connective tissue disorder characterized by fibrosis of the skin and inner organs, vasculopathy, and immunological abnormalities. Recent insights on the implication of STAT3, AKT, and Wnt/β-catenin in fibrosis have prompted us to investigate, in a mouse model of ROS-induced SSc, the effects of niclosamide, an antihelmintic drug that inhibits both of these signaling pathways. SSc was induced in BALB/c mice by daily s.c. injections of hypochlorous acid (HOCl). Mice were treated or not every other day, 5 d a week, for 6 wk, by niclosamide. Skin and lung fibrosis as well as immunological features were studied. Mice exposed to HOCl developed a diffuse cutaneous SSc with pulmonary fibrosis and anti-DNA topoisomerase 1 autoantibodies. STAT3, AKT, and Wnt/β-catenin pathways were hyperactivated in the skin and the lungs of diseased mice. Niclosamide reversed fibrosis of the skin and the lungs. Beneficial immunological effects were also observed because niclosamide decreased the activation of CD4 + and CD8 + T cells, autoimmune B cell activation, as well as IL-4 and IL-13 production in the skin. The improvement permitted by niclosamide in the mouse model of HOCl-induced SSc as well as the well-documented safety profile of this drug provide a rationale for the evaluation of niclosamide in the management of patients affected by this disease.