Citrullination of TNF-α by peptidylarginine deiminases reduces its capacity to stimulate the production of inflammatory chemokines

• Published in: Cytokine (Philadelphia, Pa.) Vol. 61; no. 1; pp. 161 - 167
• Main Authors: Moelants, Eva A.V., Mortier, Anneleen, Grauwen, Karolien, Ronsse, Isabelle, Van Damme, Jo, Proost, Paul
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2013
• Subjects: Animals; Anti-Inflammatory Agents, Non-Steroidal; Anti-Inflammatory Agents, Non-Steroidal - metabolism; Antibodies, Monoclonal; Antibodies, Monoclonal - metabolism; Apoptosis; arginine; Arthritis, Rheumatoid; Arthritis, Rheumatoid - immunology; Arthritis, Rheumatoid - metabolism; Autoimmune Diseases; Autoimmune Diseases - immunology; Autoimmune Diseases - metabolism; bioactive properties; Cell Line; chemokines; Citrullination; citrulline; Citrulline - metabolism; Cytokine; Female; Fibroblasts; Humans; Hydrolases; Hydrolases - metabolism; IL-1β; immunology; Infliximab; Interleukin-1beta; Interleukin-1beta - metabolism; interleukin-8; Leukocytes, Mononuclear; Leukocytes, Mononuclear - metabolism; metabolism; Mice; necrosis; Neutrophil Activation; neutrophils; Neutrophils - immunology; post-translational modification; Posttranslational modification; Protein Binding; Protein-Arginine Deiminases; proteins; rheumatoid arthritis; sclerosis; TNF; tumor necrosis factor-alpha; Tumor Necrosis Factor-alpha - metabolism; E/S; PTM; FACS; TNF; LPS; TFA; [Cit]TNF-α; Posttranslational modification; DMEM; CHX; FBS; IL-8/CXCL8; HPLC; Citrullination; PBS; TNFR; MS; Cytokine; TMB; i.p; IL-1β; IP-10/CXCL10; Cit; RA; PAD; TNF-α; Arg; MCP-1/CCL2; ELISA
• ISSN: 1043-4666; 1096-0023; 1096-0023
• DOI: 10.1016/j.cyto.2012.09.011

► Citrullination is a cytokine-specific phenomenon. ► Citrullinated TNF-α is less potent to stimulate chemokine production in vitro. ► Citrullinated TNF-α retains its capacity to induce apoptosis/necrosis. ► Binding of TNF-α to the drug Infliximab is not influenced by citrullination. ► TNF-α and [Cit]TNF-α are equally potent to attract neutrophils in vivo. Citrullination, a posttranslational modification (PTM) recently discovered on inflammatory chemokines such as interleukin-8 (IL-8/CXCL8) and interferon-γ-inducible protein-10 (IP-10/CXCL10), seriously influences their biological activity. Citrullination or the deimination of arginine to citrulline is dependent on peptidylarginine deiminases (PADs) and has been linked to autoimmune diseases such as multiple sclerosis (MS) and rheumatoid arthritis (RA). Chemokines are to date the first identified PAD substrates with receptor-mediated biological activity. We investigated whether cytokines that play a crucial role in RA, like interleukin-1β (IL-1β) and tumor necrosis factor-alpha (TNF-α), may be citrullinated by PAD and whether such a PTM influences the biological activity of these cytokines. IL-1β and TNF-α were first incubated with PAD in vitro and the occurrence of citrullination was examined by Edman degradation and a recently developed detection method for citrullinated proteins. Both techniques confirmed that human TNF-α, but not IL-1β, was citrullinated by PAD. Citrullination of TNF-α reduced its potency to stimulate chemokine production in vitro on human primary fibroblasts. Concentrations of the inflammatory chemokines CXCL8, CXCL10 and monocyte chemotactic protein-1 (MCP-1/CCL2) were significantly lower in supernatants of fibroblasts induced with citrullinated TNF-α compared to unmodified TNF-α. However, upon citrullination TNF-α retained its capacity to induce apoptosis/necrosis of mononuclear cells, its binding potency to Infliximab and its ability to recruit neutrophils to the peritoneal cavity of mice.