Background: Familial Mediterranean fever (FMF) is an IL-1β–dependent autoinflammatory disease caused by mutations of Mediterranean fever (MEFV) encoding pyrin and characterized by inflammatory attacks induced by physical or psychological stress. Objective: We investigated the underlying mechanism that links stress-induced inflammatory attacks with neutrophil activation and release of IL-1β–bearing neutrophil extracellular traps (NETs) in patients with FMF. Methods: RNA sequencing was performed in peripheral neutrophils from 3 patients with FMF isolated both during attacks and remission, 8 patients in remission, and 8 healthy subjects. NET formation and proteins were analyzed by using confocal immunofluorescence microscopy, immunoblotting, myeloperoxidase-DNA complex ELISA, and flow cytometry. Samples from patients with Still's disease and bacterial infections were used also. Results: The stress-related protein regulated in development and DNA damage responses 1 (REDD1) is significantly overexpressed during FMF attacks. Neutrophils from patients with FMF during remission are resistant to autophagy-mediated NET release, which can be overcome through REDD1 induction. Stress-related mediators (eg, epinephrine) decrease this threshold, leading to autophagy-driven NET release, whereas the synchronous inflammatory environment of FMF attack leads to intracellular production of IL-1β and its release through NETs. REDD1 in autolysosomes colocalizes with pyrin and nucleotide-binding domain, leucine-rich repeat/pyrin domain-containing 3. Mutated pyrin prohibits this colocalization, leading to higher IL-1β levels on NETs. Conclusions: This study provides a link between stress and initiation of inflammatory attacks in patients with FMF. REDD1 emerges as a regulator of neutrophil function upstream to pyrin, is involved in NET release and regulation of IL-1β and might constitute an important piece in the IL-1β–mediated inflammation puzzle.
Skendros, P., Chrysanthopoulou, A., Rousset, F., Kambas, K., Arampatzioglou, A., Mitsios, A., … Ritis, K. (2017). Regulated in development and DNA damage responses 1 (REDD1) links stress with IL-1β–mediated familial Mediterranean fever attack through autophagy-driven neutrophil extracellular traps. Journal of Allergy and Clinical Immunology, 140(5), 1378-1387.e13. https://doi.org/10.1016/j.jaci.2017.02.021