New insights on chemically induced animal models of systemic sclerosis

Purpose of review To discuss the most recent published studies on chemical-induced animal models of systemic sclerosis (SSc) and to precise the important signalling pathways that lead to the initiation and progression of the disease in these models. Recent findings Environmental factors undoubtedly contribute to the initiation and the development of SSc. Among those factors, bleomycin has been identified as a possible SSc-inducing substance in mice. The bleomycin model mimics the inflammatory changes observed in the early phase of the disease. This model has been extensively studied and has allowed identification of several key pathways activated in the human disease. More recently, a new chemical-induced model of scleroderma has been developed in mice using daily intradermal injections of a solution generating hypochlorous acid (HOCl)-model. This HOCl-model recapitulates the whole spectrum of the human disease, as fibrosis, inflammation, autoimmunity and vasculopathy can be observed in mice and brought new arguments for a major role of reactive oxygen species in the induction of local and systemic fibrosis. Summary Chemically induced models truly develop a SSc-like disease and argue for a crucial role of ROS in SSc.