Citrullinated vimentin and alpha enolase are expressed at the cell surface of apoptotic human neutrophils

The cytoskeletal vimentin (Vim) and the alpha-enolase (ENO1) proteins are associated with autoimmune and inflammatory diseases. We previously documented that Vim is degraded by caspases and expressed at the cell surface of human apoptotic neutrophils. The aim of the present study was to monitor the expression of Vim, ENO1, and their citrullinated forms (cit-Vim, cit-ENO1) during the regulation of spontaneous human neutrophil apoptosis (SA) by the antiapoptotic cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) and the proapoptotic anti-cancer drug arsenic trioxide (ATO). Although the degradation of Vim during SA was delayed by GM-CSF and accelerated by ATO, no significant degradation of cit-Vim, ENO1, and cit-ENO1 was observed. However, Vim, ENO1, cit-Vim, and cit-ENO1 are expressed at the cell surface of apoptotic neutrophils. These data further support the potential participation of neutrophils in autoimmune and inflammatory diseases as they might be an important source of autoantigens when they undergo apoptosis.