Background/Purpose: Genetically defined IL-1 mediated autoinflammatory diseases are caused by monogenic defects that regulate inflammasome activity. By whole exome sequencing (WES) analysis we identified one de novo mutation in DYSF, encoding dysferlin, in 2 unrelated patients (pts.) with systemic inflammation and sterile pulmonary abscesses. Unlike dysferlin mutations that cause muscular dystrophies, the patients have no muscle disease. A robust clinical response to IL-1 blockade suggested a link to overproduction of IL-1. We studied monocytes and neutrophils to assess the mechanism of the IL-1 dependent inflammation. The aim of our study is to understand the role of DYSF on the upregulation of IL-1 production and the development of lung abscesses.

Methods: Flowcytometry, ELISA, cytokine array, survival assay and immunofluorescence techniques were used to study monocyte and neutrophil function in patients and controls.

Results: Lipopolysaccharides (LPS) and ATP-stimulated IL-1 production in monocyte and monocyte-derived macrophages (MDM) was significantly higher in the DYSF pts. compared to IL-1 production in NOMID pts. (p=0.029) and healthy controls (HC) (p=0.038). Dysferlin colocalizes with NLRP3 and expression of Asc, and caspase-1 were increased in the DYSF pts. compared to healthy controls, which is linked to higher IL-1β production. Our data confirmed NLRP3 and Caspase-1 co-localization in patient monocytes as well. The development of sterile neutrophilic abscesses in the lung raised questions of the role of dysferlin in neutrophil activation and clearance. In contrast to MDMs, IL-1 was not upregulated in patient neutrophils, however MIF (5 fold) and IL-16 (2-3 fold) were significantly upregulated compare to HC and NOMID but not in monocytes or macrophages. Neutrophils had a higher survival rate and lower LDH release compared to healthy controls upon stimulation with LPS and ATP. Elevated MIF and IL-16 release may prevent neutrophil apoptosis and enhance persistence of sterile neutrophils in the lung. Mechanistic studies to explore these pathways are ongoing.

Conclusion: Consistent with clinical responses of IL-1 blocking treatment, our in vitro results confirm mutant monocytes and MDMs as the source for the high IL-1 production in two patient with a de novo mutation in dysferlin. Moreover, the upregulation of MIF and IL-16 in neutrophils from dysferlin patients but not NOMID patients or healthy controls and the impairment of neutrophil apoptosis may provide a mechanism to explain the development of sterile abscesses in the patients’ lungs. This is the first report that links dysferlin to the regulation of the NLRP3 inflammasome and to neutrophil survival and adds to a number of intracellular pathways that control inflammasome activation and suggest novel targets for treatment.

Acknowledgements: This work was supported by the NIH IRP of NIAID

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-novel-il-1-mediated-autoinflammatory-disease-caused-by-a-specific-gain-of-function-mutation-in-dysferlin/