An Atypical Autoinflammatory Disease Due to an LRR Domain NLRP3 Mutation Enhancing Binding to NEK7.

ABSTRACT

The NLRP3 inflammasome is a vital mediator of innate immune responses. There are numerous NLRP3 mutations that cause NLRP3-associated autoinflammatory diseases (NLRP3-AIDs), mostly in or around the NACHT domain. Here, we present a patient with a rare leucine-rich repeat (LRR) domain mutation, p.Arg920Gln (p.R920Q), associated with an atypical NLRP3-AID with recurrent episodes of sore throat and extensive oropharyngeal ulceration. Unlike previously reported patients, who responded well to anakinra, her oral ulcers did not significantly improve until the PDE4 inhibitor, apremilast, was added to her treatment regimen. Here, we show that this mutation enhances interactions between NLRP3 and its endogenous inhibitor, NIMA-related kinase 7 (NEK7), by affecting charge complementarity between the two proteins. We also demonstrate that additional inflammatory mediators, including the NF-кB and IL-17 signalling pathways and IL-8 chemokine, are upregulated in the patient's macrophages and may be directly involved in disease pathogenesis. These results highlight the role of the NLRP3 LRR domain in NLRP3-AIDs and demonstrate that the p.R920Q mutation can cause diverse phenotypes between families.