POS0234 P.E148Q POTENTIATES PYRIN INFLAMMASOME ACTIVATION

Background The p.E148Q variant in pyrin is present different populations at a frequency up to 29%[1], and has been associated with inflammatory diseases including vasculitis familial Mediterranean fever (FMF)[2,3]. pathogenicity of FMF unclear, highly debated the literature especially when observed cis or trans single, typically recessive, mutation. If it could modify expressivity pathogenic allele acts as risk factor for not known. Objectives We Interrogated Australian Autoinflammatory Disease RegistrY (AADRY) find candidate inheritance patterns pyrin. then performed functional validation determine whether increases ability form an active inflammasome complex cell lines. Finaly, increase effect known mutation was assessed. Methods patients auto-inflammatory their families AADRY Different combinations were tested HEK293T cells stably expressing adaptor protein apoptosis-associated speck-like (ASC) which analysed by flow cytometry visualise formation, without stimulation Clostridium difficile toxin B (TcdB). Inflammasome dependent cytokine secretion also quantified ELISA supernatants from THP-1 transduced lentiviral expression vectors. Results In AADRY, we individuals autoinflammatory alone conjunction other variants. Two harbored p.M694I-E148Q dominant heritability. vitro, spontaneously potentiate increased IL-1β IL-18 secretion. classical mutations provided significant potentiation formation. Conclusion potentiates activation vitro. , this additive mutations. These observations may help explain association diseases. References [1]K. J. Karczewski, L. C. Francioli, G. Tiao, B. Cummings, Alföldi, Q. Wang, et al. mutational constraint spectrum variation 141,456 humans. Nature 2020 Vol. 581 Issue 7809 Pages 434-443. [2]D. Cattan, MEFV carriers than fever: proved non-proved associations; putative biological advantage, Curr Drug Targets Inflamm Allergy 2005 4 1 105-12. [3]I. Touitou, Familial Fever (FMF) mutations, Eur J Hum Genet 2001 9 7 473-83. Figure 1. Heterozygous p. M694I p.M694I response TcdB ASC EGFP transiently co-transfected mCherry tagged WT pyrin, p.E148Q-M694I stimulated TcdB. FACS analysis revealed statistically speck formation compared co-expressing (E148Q M694I) (M694I heterozygous). Data are pooled independent experiments. Error bars represent mean +/- SEM. Statistics used paired Student t-test. **P<0.01, ns; non-significant. Het.=heterozygous, Hom.=homozygous. Acknowledgements would like first thank involved AADRY. grateful all members Masters laboratory support. WEHI flowcytometry facility (Simon Monard) excellent technical Disclosure Interests Thomas Reygaerts: None declared, Pawat Laohamonthonkul: Katja Hrovat-Schaale: Fiona Moghaddas: Paul Baker: Gray: Seth Consultant of: Scientific Advisor Odyssey Therapeutics., Employee VP Discovery Biology NRG Therapeutics.