TY - JOUR T1 - Neutrophil Extracellular Traps Profiles in Patients with Incident Systemic Lupus Erythematosus and Lupus Nephritis JF - The Journal of Rheumatology JO - J Rheumatol DO - 10.3899/jrheum.181232 SP - jrheum.181232 AU - Maurizio Bruschi AU - Alice Bonanni AU - Andrea Petretto AU - Augusto Vaglio AU - Federico Pratesi AU - Laura Santucci AU - Paola Migliorini AU - Roberta Bertelli AU - Maricla Galetti AU - Silvana Belletti AU - Lorenzo Cavagna AU - Gabriella Moroni AU - Franco Franceschini AU - Micaela Fredi AU - Giulia Pazzola AU - Landino Allegri AU - Renato Alberto Sinico AU - Giampaola Pesce AU - Marcello Bagnasco AU - Angelo Manfredi AU - Giuseppe A. Ramirez AU - Paola Ramoino AU - Paolo Bianchini AU - Francesco Puppo AU - Francesca Pupo AU - Simone Negrini AU - Federico Mattana AU - Giacomo Emmi AU - Giacomo Garibotto AU - Domenico Santoro AU - Francesco Scolari AU - Angelo Ravelli AU - Angela Tincani AU - Paolo Cravedi AU - Stefano Volpi AU - Giovanni Candiano AU - Gian Marco Ghiggeri Y1 - 2019/05/15 UR - http://www.jrheum.org/content/early/2019/11/25/jrheum.181232.abstract N2 - Objective Neutrophil extracellular traps (NET) expose modified antigens for autoantibodies in vasculitis. Little is known about levels and removal pathways of NET in systemic lupus erythematosus (SLE), especially in lupus nephritis (LN). We determined circulating levels and defined NET removal in large subsets of patients with incident SLE (iSLE), some of whom had new-onset nephritis. Methods Serum levels of NET (ELISA), DNase1/DNase1L3 (ELISA), and DNase activity (functional assay) were determined in 216 patients with iSLE [103 had incident LN (iLN)], in 50 patients with other primary glomerulonephritis, and in healthy controls. Ex vivo NET production by neutrophils purified from a random selection of patients was quantified as elastase/DNA release and by immunofluorescence techniques. Results Serum NET levels were very high in iSLE/iLN compared to all groups of controls and correlated with anti-dsDNA, C3–C4, and proteinuria; iLN had the highest levels. DNase activity was decreased in iLN compared to SLE (20% had one-half DNase activity) despite similar serum levels of DNase1/DNase1L3. In these cases, pretreatment of serum with protein A restored DNase efficiency; 1 patient was homozygous for a c.289_290delAC variant of DNASE1L3. Ex vivo NET production by neutrophils purified from LN, SLE, and normal controls was similar in all cases. Conclusion Patients with iLN have increased circulating NET and reduced DNase activity, the latter being explained by the presence of inhibitory substances in circulation and/or by rare DNase1L3 mutations. Accumulation of NET derives from a multifactorial mechanism, and is associated and may contribute to disease severity in SLE, in particular to renal lesions. (Clinical trial registration: The Zeus study was registered at ClinicalTrials.gov, study number NCT02403115). ER -