Flavonoids interfere with NLRP3 inflammasome activation.

Area of Science:

• Immunology
• Molecular Biology
• Pharmacology

Background:

• The NOD-like receptor (NLR) family, pyrin domain-containing 3 (NLRP3) inflammasome is crucial for innate immunity, producing IL-1β and IL-18.
• The precise mechanisms by which flavonoids modulate inflammasome pathways remain largely unknown.

Purpose of the Study:

• To investigate the effects of various flavonoids on the NLRP3 inflammasome pathway.
• To determine the structure-activity relationships of flavonoids in NLRP3 inflammasome activation.
• To elucidate the cellular mechanisms underlying flavonoid inhibition of NLRP3 inflammasome.

Main Methods:

• Differentiated THP-1 cells were treated with monosodium urate (MSU) crystals to activate the NLRP3 inflammasome.
• Levels of IL-1β, NLRP3 components, and ASC oligomerization were measured.
• Flavonoid effects on AIM2 and NLRC4 inflammasomes, and Syk/Pyk2 signaling were assessed.
• In vivo efficacy was evaluated using an MSU-induced peritonitis mouse model.

Main Results:

• Five flavonoids, including apigenin, kaempferol, and quercetin, significantly inhibited IL-1β production.
• Apigenin, kaempferol, and 3',4'-dichloroflavone suppressed ASC oligomerization.
• Apigenin demonstrated inhibitory effects on AIM2 inflammasome and Syk/Pyk2 phosphorylation, and reduced inflammatory cell infiltration in mice.

Conclusions:

• This study establishes structure-activity profiles for flavonoids targeting the NLRP3 inflammasome.
• Apigenin's anti-inflammatory action involves inhibiting Syk/Pyk2 signaling.
• Flavonoids, particularly apigenin, show promise for managing autoinflammatory conditions driven by NLRP3 inflammasome activation.