Role of ASM/Cer/TXNIP signaling module in the NLRP3 inflammasome activation

Abstract

Background: This study aimed to explore the effects of ceramide (Cer) on NLRP3 inflammasome activation and their underlying mechanisms.Methods: Lipopolysaccharide (LPS)/adenosine triphosphate (ATP)-induced NLRP3 inflammasome activation in J774A.1 cells and THP-1 macrophages was used as an in vitro model of inflammation. Western blotting and real-time PCR (RT-PCR) were used to detect the protein and mRNA levels, respectively. IL-1β and IL-18 levels were measured by ELISA. ASM assay kit and immunofluorescence were used to detect ASM activity and Cer content.Results: Imipramine, a well-known inhibitor of ASM, significantly inhibited LPS/ATP-induced activity of ASM and the consequent accumulation of Cer. Additionally, imipramine suppressed the LPS/ATP-induced expression of thioredoxin interacting protein (TXNIP), NLRP3, caspase-1, IL-1β, and IL-18 at the protein and mRNA level. Interestingly verapamil, a TXNIP inhibitor, suppressed LPS/ATP-induced activation of TXNIP/NLRP3 inflammasome but did not affect LPS/ATP-induced ASM activation and Cer formation. TXNIP siRNA and verapamil inhibited C2-Cer-induced upregulation of TXNIP and activation of the NLRP3 inflammasome. In addition, the pretreatment of cells with sulfo-N-succinimidyl oleate (SSO), an irreversible inhibitor of the scavenger receptor CD36, blocked Cer-induced upregulation of nuclear factor-κB (NF-κB) activity, TXNIP expression, and NLRP3 inflammasome activation. Inhibition of NF-κB activation by SN50 prevented Cer-induced upregulation of TXNIP and activation of the NLRP3 inflammasome but did not affect CD36 expression.Conclusion: This study demonstrated that the ASM/Cer/TXNIP signaling pathway is involved in NLRP3 inflammasome activation. The results documented that the CD36-dependent NF-κB-TXNIP signaling pathway plays an essential role in the Cer-induced activation of NLRP3 inflammasomes in macrophages.

Epicardial Adipose Tissue Ceramides Are Related to Lipoprotein Lipase Activity in Coronary Artery Disease: Unfolding a Missing Link

“…Some ceramides present neutral or benign forms, while others are harmful species related to increased cardiovascular risk. Among these, direct impact on inflammation, promoting inflammasome activation and IL (interleukin)-1β release, 36 have been described; they also disrupt insulin signaling, 37 promote monocyte adhesion, 38 and LDL oxidation 39 and are associated with the formation of coronary plaques 40 among many other deleterious vascular effects. However, the source of these ceramides to the plaques is still a matter of discussion, being plasma LDL, 41 arterial wall cells 40,41 or human blood monocyte-derived macrophages among some of the proposed sources.…”