Trafficking of cholesterol to the ER is required for NLRP3 inflammasome activation

“…Reciprocally, lipopolysaccharides-primed macrophages treated with acetylated LDL and sphingomyelinase, which liberates membrane cholesterol for movement to the ER, showed increased IL-1B and inflammasome activation markers. These studies are in line with other work showing, in a Niemann-Pick disease, type C1 deletion model, that ER cholesterol trafficking impacts NLRP3 activity ( 8 ). To reinforce the idea that plasma membrane to ER cholesterol content can drive inflammasome activation, the authors use an RNA interference approach targeting a key transporter of cholesterol movement.…”

“…However, we found that culturing RAW 264.7 MF in media containing lipoprotein-deficient serum significantly reduced U18666A-dependent lysosomal cholesterol accumulation but did not impact significantly upon inhibition of LA-stimulated ProIL-1b expression, indicating that impairment of NLRP3 priming was unlikely to be the result of storage of cholesterol. It is interesting to note that our findings of reduced NLRP3dependent generation of IL-1b has been reported in a different model of NPC 50 . In contrast to the studies shown here in which primary MF obtained from an authentic mouse model of the storage disease were analyzed in vitro and in vivo, the published investigation focused primarily on the use of an immortalized BMMF cell line in which mutations in Npc1 had been engineered by CRISPR-cas9 technology.…”

“…In agreement we formulated the idea that the similarity between AOH and cholesterol could be a key to understand the immunomodulatory potential of the mycotoxin, and its mechanism of action at membrane level (Figure 7C). Cholesterol plays also an essential role in the activation of the NLRP3 inflammasome activation [79], as well as in transducing lipid peroxidation signals in macrophages [23]. In agreement, the effects of AOH on the immunodetection of caveolin-1 (Figure 6), and of the cytokine MIF (Supplementary Figures S5 and S7), were reduced by the cholesterol deprivation with MβCD, exactly like the membrane fluidity response (Figure 2).…”