NLRP1 and rheumatoid arthritis: The mRNA expression levels of NLRP3, NLRC4, AIM2, caspase-1 and IL-1beta in the RA group were markedly increased (Fig. 1A-E), but the levels of NLRP1, NLRP2 and NLRC5 were notably decreased in comparison with those in the HC group (Fig. 1F-H).