NET Proteomic Profiling reveals new pathways potentially implicated in dendritic cell‐mediated inflammation in DADA2 patients

Purpose: Adenosine deaminase 2 Deficiency (DADA2) is an autoinflammatory disease characterized by systemic vasculopathy, strokes and mild immunodeficiency. Recently NETosis has been implicated in the pathogenesis of Deficiency of Adenosine Deaminase 2. To deep investigate the possible effects of NETs on the immune system we characterized proteomic profile of NETs from DADA2 as compared to HD and Polyarteritis Nodosa (PAN) patients. To determine if NETs contain possibly immunogenic antigens we study functional aspects on Dendritic Cells after in vitro stimulation with NETs. Methods: Twenty-three DADA2 patients were enrolled. We analyzed NETosis by Imaging Flow Citometry. We evaluated NETs remnants and DNAse in the plasma samples by ELISA assay whereas DNAse activity by DNA digestion. We used quantitative proteomics approach and network analysis to identify NET proteins and pathways in 6 DADA2, 7 PAN and 7 HD. We analyzed circulating and monocyte-derived dendritic cells by flow cytometry. Results: Neutrophils from DADA2 patients show a significant increased suicidal NETosis. DNAse enzymes were not normal in the level or activity. By proteomic analysis we identified 1356 proteins among which a hundred of proteins were significantly up or down-modulated in DADA2 NETs as compared to normal and disease control NETs in resting condition and after stimulation with PMA, Adenosine and TNFα. DADA2 NETs are significantly more efficient than normal NETs in stimulating patients’ monocyte-derived dendritic cells. Conclusion: We identified different pathways significantly modulated in DADA2 NETs versus PAN/HD NETs. This peculiar protein profile could contribute in activating inflammatory pathways in Dendritic cells in DADA2