CRP-Induced NLRP3 Inflammasome Activation Increases LDL Transcytosis Across Endothelial Cells

Abstract

The NLRP3 inflammasome, a multiprotein cytosolic complex that activates the IL-1 family of cytokines, plays an important role in atherosclerosis (AS). High-sensitivity c-reactive protein (hs-CRP) is widely recognized as a major cardiovascular risk predictor and recent studies name NLRP3 as a predictor of CRP levels. Mounting evidence has indicated that subendothelial retention of apolipoprotein B100-containing lipoproteins, such as low-density lipoprotein (LDL), is the initial step of atherogenesis, and is usually termed the “response to retention hypothesis.” We previously reported that CRP promotes AS by directly increasing LDL transcytosis across endothelial cells (ECs). The present study aims to investigate the effects of CRP on NLRP3 inflammasome activation and the role of the NLRP3 inflammasome in CRP-induced LDL transcytosis. We found that CRP upregulated NF-κB activity, the NF-κB inhibitor (BAY-11-7082) and Fcγ receptors (FcγRs) inhibitor (CD32/64Ab) blocked CRP-induced NF-κB activation. CRP also induced expression of pro-IL-1β and NLRP3, while BAY and CD32/64 Ab suppressed CRP-mediated expression of NLRP3 and pro-IL-1β. Moreover, CRP activated the NLRP3 inflammasome in ECs. NADPH oxidase inhibitor, diphenylene iodonium (DPI) and dithiothreitol (DTT), a broad-spectrum P2 receptor inhibitor, oxidized ATP (oATP), and a broad inhibitor of cysteine proteases, E-64d, inhibited CRP-induced NLRP3 inflammasome activation. Furthermore, NLRP3 siRNA and caspase-1 inhibitor blocked CRP-mediated LDL transcytosis across ECs. In conclusion, NLRP3 inflammasome activation was shown to be involved in CRP-mediated LDL transcytosis across ECs. CRP not only increased the expression of pro-IL-1β and NLRP3 via the FcγRs/NF-κB pathway, but also promoted NLRP3 inflammasome activation and IL-1β maturation by upregulation of reactive oxygen species (ROS) levels, purinergic receptor signaling, and activation of cysteine proteases.

C-reactive Protein as a Diagnostic and Prognostic Factor of Endometrial Cancer

“…Therefore, autophagy alteration could be an additional mechanism through which C-reactive protein can possibly promote endometrial cancer development and progression. An interesting study was performed by Bian et al who investigated impact of C-reactive protein on human umbilical cord cells [45]. Western blot analyses revealed CRP induced expression and activation of NLRP3 (NOD-like receptor family, pyrin domain-containing protein 3) and its product, IL-1β, through FcgR/NF-κB (nuclear factor κB) pathway [45].…”

“…An interesting study was performed by Bian et al who investigated impact of C-reactive protein on human umbilical cord cells [45]. Western blot analyses revealed CRP induced expression and activation of NLRP3 (NOD-like receptor family, pyrin domain-containing protein 3) and its product, IL-1β, through FcgR/NF-κB (nuclear factor κB) pathway [45]. Liu et al examined tumour samples of 31 women with endometrial cancer, showing that NLRP3 overexpression is significantly associated with increased proliferation, migration and invasion of EC cells [46].…”

Early Pro-Inflammatory Remodeling of HDL Proteome in a Model of Diet-Induced Obesity: 2H2O-Metabolic Labeling-Based Kinetic Approach

“…Interestingly, the SAA proteins are known to activate the inflammasome in macrophages, neurons, and other cell types [61,62]. Similarly, C-reactive protein activates the inflammasome in the endothelial cells [63]. As a critical component of the inflammatory process, the acute-phase response amplifies tissue inflammation, exacerbates tissue damage, and causes metabolic dysregulation that enhances disease complications.…”

The NLRP3 inflammasome: Multiple activation pathways and its role in primary cells during ventricular remodeling

“…Recently, it was found that CRP can upregulate the activity of NF‐κB in VECs, induce the expression of NLRP3 and pro‐IL‐1β, as well as promote the activation of the NLRP3 inflammasome and IL‐1β maturation by increasing ROS levels. In an in vitro model of trans‐cellular LDL transport, VECs and CRP were incubated for 24 h, and the expression of proteins involved in the NLRP3 inflammasome activation signaling pathway was upregulated, indicating that NLRP3 inflammasome activation is involved in CRP‐mediated trans‐VEC LDL transport, promoting the inflammatory response of VECs (Bian et al, 2019).…”