Inflammasome Activation In Diseases Research Articles

Glibenclamide-Loaded Nanoparticles Reduce NLRP3 Inflammasome Activation and Modulate miR-223-3p/miR-7-1-5p Expression in THP-1 Cells.

The anti-hyperglycemic drug glibenclamide (Glb) might represent an interesting therapeutic option in human neurodegenerative diseases because of its anti-inflammatory activity and its ability to downregulate activation of the NLRP3 inflammasome. Bi-functionalized liposomes that can cross the blood-brain barrier (BBB) may be used to release Glb into the central nervous system (CNS), overcoming its poor solubility and bioavailability. Here, we analyzed in vitro the effect of Glb-loaded nanovectors (GNVs) and Glb itself on NLRP3 inflammasome activation using a lipopolysaccharide- and nigericine-activated THP-1 cell model. Apoptosis-associated speck-like protein containing a CARD (ASC) aggregation and NLRP3-related cytokine (IL-1β, caspase 1, and IL-18) production and gene expression, as well as the concentration of miR-223-3p and miR-7-1-5p, known to modulate the NLRP3 inflammasome, were evaluated in all conditions. Results showed that both GNVs and Glb reduced significantly ASC-speck oligomerization, transcription and translation of NLRP3, as well as the secretion of caspase 1 and IL-1β (p < 0.05 for all). Unexpectedly, GNVs/Glb significantly suppressed miR-223-3p and upregulated miR-7-1-5p expression (p < 0.01). These preliminary results thus suggest that GNVs, similarly to Glb, are able to dampen NLRP3 inflammasome activation, inflammatory cytokine release, and modulate miR-223-3p/miR-7-1-5p. Although the mechanisms underlying the complex relation among these elements remain to be further investigated, these results can open new roads to the use of GNVs as a novel strategy to reduce inflammasome activation in disease and rehabilitation.

Critical role for extracellular-regulated kinase signaling in endotoxin priming of human monocyte NLRP3 inflammasome (IRM5P.705)

Abstract Inflammasomes play key roles in the innate immune response to pathogens and tissue injury. Inflammasome assembly involves two distinct steps; priming and activation, which together trigger caspase-1 to process and release IL-1β, IL-18 and in some settings to induce pyroptosis. Current understanding suggests that priming is the de novo synthesis of proIL-1β and the up-regulation of NLRP3. However, since proIL-18 is constitutively present in monocytes, we studied the mechanisms and timing of endotoxin induced priming events that precede new protein synthesis. Within 15 min of endotoxin priming, exogenous ATP induces caspase-1-dependent mature IL-18 release. This priming is not impaired by inhibition of gene transcription or protein translation. Knockdown of NLRP3 supports a role for constitutive NLRP3 in this rapid IL-18 processing. To dissect the early signaling events we investigated upstream signaling pathways. Interestingly, ERK phosphorylation was found to be essential for priming as proven by chemical inhibition and knockdown approaches. Scavenging of reactive oxygen species blocked both priming and ERK phosphorylation. These findings suggest that priming involves ERK-mediated posttranslational modifications which license the NLRP3 inflammasome to respond to a second, activation signal. Thus, understanding what these modifications are may provide new opportunities to modulate inflammasome activation in disease.