RESUMEN
Rheumatoid arthritis is associated with the development of autoantibodies to citrullinated self-proteins. Citrullinated synovial proteins, which are generated via the actions of the protein arginine deiminases (PADs), are known to develop in the murine collagen-induced arthritis (CIA) model of inflammatory arthritis. Given these findings, we evaluated whether N-α-benzoyl-N5-(2-chloro-1-iminoethyl)-L-ornithine amide (Cl-amidine), a recently described pan-PAD inhibitor, could affect the development of arthritis and autoimmunity by treating mice in the CIA model with Cl-amidine on days 0-35. Cl-amidine treatment reduced total synovial and serum citrullination, decreased clinical disease activity by â¼50%, and significantly decreased IgG2a anti-mouse type II collagen Abs. Additionally, histopathology scores and total complement C3 deposition were significantly lower in Cl-amidine-treated mice compared with vehicle controls. Synovial microarray analyses demonstrated decreased IgG reactivity to several native and citrullinated epitopes compared with vehicle controls. Cl-amidine treatment had no ameliorative effect on collagen Ab-induced arthritis, suggesting its primary protective mechanism was not mediated through effector pathways. Reduced levels of citrullinated synovial proteins observed in mice treated with Cl-amidine are consistent with the notion that Cl-amidine derives its efficacy from its ability to inhibit the deiminating activity of PADs. In total, these results suggested that PADs are necessary participants in the autoimmune and subsequent inflammatory processes in CIA. Cl-amidine may represent a novel class of disease-modifying agents that modulate aberrant citrullination, and perhaps other immune processes, necessary for the development of inflammatory arthritis.
Asunto(s)
Amidinas/uso terapéutico , Artritis Experimental/tratamiento farmacológico , Artritis Experimental/inmunología , Inhibidores Enzimáticos/uso terapéutico , Hidrolasas/antagonistas & inhibidores , Inmunosupresores/uso terapéutico , Ornitina/análogos & derivados , Animales , Artritis Experimental/patología , Artritis Reumatoide/tratamiento farmacológico , Artritis Reumatoide/inmunología , Artritis Reumatoide/patología , Autoanticuerpos/biosíntesis , Autoanticuerpos/toxicidad , Citrulina/metabolismo , Colágeno Tipo II/antagonistas & inhibidores , Colágeno Tipo II/inmunología , Hidrolasas/toxicidad , Masculino , Ratones , Ratones Endogámicos DBA , Ornitina/uso terapéutico , Péptidos Cíclicos/inmunología , Péptidos Cíclicos/metabolismo , Desiminasas de la Arginina Proteica , Índice de Severidad de la Enfermedad , Membrana Sinovial/inmunología , Membrana Sinovial/metabolismo , Membrana Sinovial/patologíaRESUMEN
Protein Arginine Deiminase (PAD) activity is dysregulated in numerous diseases, e.g., Rheumatoid Arthritis. Herein we describe the development of a fluorescence polarization-Activity Based Protein Profiling (fluopol-ABPP) based high throughput screening assay that can be used to identify PAD-selective inhibitors. Using this assay, streptonigrin was identified as a potent, selective, and irreversible PAD4 inactivator.