PYCARD and primary progressive multiple sclerosis: Taken together, our results suggest that in PPMS patients a possibly prolonged and chronic stimulation would result in the upregulation of mRNA expression of NLRP3, ASC, caspase-8, and IL-18 genes and of NLRP3, caspase-8, ASC-speck, and IL-18 pro-inflammatory cytokine; this could be justified by the observation that hyperuricemia is present in PPMS patients.