Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Daniela Trejo-Zambrano
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Paride Fenaroli
Nephrology Unit, Parma University Hospital, Department of Medicine and Surgery, Parma, Italy; Johns Hopkins University School of Medicine, Division of Pathology, Baltimore, United States
Avi Rosenberg
Johns Hopkins University School of Medicine, Division of Pathology, Baltimore, United States
Alan Baer
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Archit Garg
Johns Hopkins University School of Medicine, Department of Biophysics and Biophysical Chemistry, Baltimore, United States
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States; Johns Hopkins University School of Medicine, Department of Biophysics and Biophysical Chemistry, Baltimore, United States
Jessica Li
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Michelle Petri
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Daniel W Goldman
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Christopher Mecoli
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States
Antony Rosen
Johns Hopkins University School of Medicine, Division of Rheumatology, Baltimore, United States; Johns Hopkins University School of Medicine, Division of Pathology, Baltimore, United States
Background: Nucleic acid binding proteins are frequently targeted as autoantigens in systemic lupus erythematosus (SLE) and other interferon (IFN)-linked rheumatic diseases. The AIM-like receptors (ALRs) are IFN-inducible innate sensors that form supramolecular assemblies along double-stranded (ds)DNA of various origins. Here, we investigate the ALR absent in melanoma 2 (AIM2) as a novel autoantigen in SLE, with similar properties to the established ALR autoantigen interferon-inducible protein 16 (IFI16). We examined neutrophil extracellular traps (NETs) as DNA scaffolds on which these antigens might interact in a pro-immune context. Methods: AIM2 autoantibodies were measured by immunoprecipitation in SLE and control subjects. Neutrophil extracellular traps were induced in control neutrophils and combined with purified ALR proteins in immunofluorescence and DNase protection assays. SLE renal tissues were examined for ALR-containing NETs by confocal microscopy. Results: AIM2 autoantibodies were detected in 41/131 (31.3%) SLE patients and 2/49 (4.1%) controls. Our SLE cohort revealed a frequent co-occurrence of anti-AIM2, anti-IFI16, and anti-DNA antibodies, and higher clinical measures of disease activity in patients positive for antibodies against these ALRs. We found that both ALRs bind NETs in vitro and in SLE renal tissues. We demonstrate that ALR binding causes NETs to resist degradation by DNase I, suggesting a mechanism whereby extracellular ALR-NET interactions may promote sustained IFN signaling. Conclusions: Our work suggests that extracellular ALRs bind NETs, leading to DNase resistant nucleoprotein fibers that are targeted as autoantigens in SLE. Funding: These studies were funded by NIH R01 DE12354 (AR), P30 AR070254, R01 GM 129342 (JS), K23AR075898 (CM), K08AR077100 (BA), the Jerome L. Greene Foundation and the Rheumatology Research Foundation. Dr. Antiochos and Dr. Mecoli are Jerome L. Greene Scholars. The Hopkins Lupus Cohort is supported by NIH grant R01 AR069572. Confocal imaging performed at the Johns Hopkins Microscopy Facility was supported by NIH Grant S10 OD016374.
