Neutrophil Extracellular Traps in Systemic Sclerosis

Overview

Systemic sclerosis (SSC) is a systemic disease characterized by limited or diffuse cutaneous sclerosis, microangiopathy, overproduction of autoantibodies and variable organ damage due to vasculopathy and/or fibrosis. The loss of self-tolerance is believed to be caused by the dysregulation of both innate and adaptive immune systems and may involve reactive oxygen species (ROS). Neutrophils are potent producers of ROS and may play a role in endothelial cells and fibrobasts dysfunction, as in autoantibodies generation. However, their role in SSC pathogenesis remains to be determined. Recent studies discovered abnormal regulation of neutrophil extracellular traps (NETs) in other auto-immune diseases such as systemic lupus erythematosus (SLE). NETs are web-like structures composed of chromatin backbones and granular molecules. They are released by activated neutrophils through a process called "NETosis". Nets were first described in 2004 as a novel host defense mechanism to trap and kill foreign pathogens. Recent evidence shows that NETs also participate in the pathogenesis of a variety of inflammatory and autoimmune diseases, including SLE. We hypothesis that this phenomenon could be dysregulated in SSC as in SLE and could play a prominent role in the induction of autoimmunity, as well as in the induction and perpetuation of organ damages.

This study is designed to assess the role of neutrophil extracellular traps (NETs) in systemic sclerosis as well as to evaluate the correlation between NETs production and NETs composition and the different complications and phenotypes observed in SSC. 30 SSC patients, 30 SLE patients and 60 healthy subjects will be recruited. Blood samples will be collected to obtain plasma, serum and polynuclear neutrophils by negative selection. 1. The main aim of the study is to evaluate the quantity of NETs induced by serum from SSc patients on neutrophils from either healthy or SSC patients in vitro. The quantity of NETs produced by different populations of neutrophils in contact with sera from SSC will be compared with those produced by the same different populations of neutrophils in contact with sera from SLE, and healthy subjects (two control populations). 2. Other objectives: * To assess the composition of the NETs produced by different populations of neutrophils exposed to serum from SSC, SLE and healthy subjects. * To correlate the quantity and the composition of NETS with clinical phenotype in SSc * To assess the role of serum cytokines in Nets production in SSC.