Nicardipine Inhibits Priming of the NLRP3 Inflammasome via Suppressing LPS-Induced TLR4 Expression

• Published in: Inflammation 2020-08, Vol.43 (4), p.1375-1386
• Main Authors: Chang, Ya-Ying, Jean, Wei-Horng, Lu, Cheng-Wei, Shieh, Jiann-Shing, Chen, Mao-Liang, Lin, Tzu-Yu
• Format: Article
• Language: English
• Subjects: Antagonists; Antihypertensives; Apoptosis; Biomedical and Life Sciences; Biomedicine; Calcium antagonists; Calcium channels (L-type); Calcium signalling; Caspase-1; Cell differentiation; Enzyme-linked immunosorbent assay; Flow cytometry; IL-1β; Immunoblotting; Immunofluorescence; Immunology; Inflammasomes; Inflammation; Interleukin 1; Internal Medicine; Lipopolysaccharides; NF-κB protein; Nuclear transport; Oligomerization; Original Article; Pathology; Pharmacology/Toxicology; Phosphorylation; Polymerase chain reaction; Proteins; Pyroptosis; Rheumatology; TLR4 protein; Toll-like receptors; Verapamil
• ISSN: 0360-3997; 1573-2576
• DOI: 10.1007/s10753-020-01215-y

The Nod-like receptor protein 3 (NLRP3) inflammasome is a multi-protein complex composed of NLRP3, pro-caspase-1, and apoptosis-associated speck-like protein that contains a caspase recruitment domain (ASC). After NLRP3 priming by lipopolysaccharide (LPS), the ligand of toll-like receptor 4 (TLR4), activation of the NLRP3 inflammasome triggers caspase-1 maturation, leading to pyroptosis and release of interleukin-1beta (IL-1beta). Expression of TLR4 modulates LPS-triggered inflammatory cascades as well as the NLRP3 signaling. L-type calcium channel antagonists are widely used as anti-hypertensive drugs and also exert anti-inflammatory effects through inhibiting release of cytokines including IL-1beta. However, few studies reveal effects of L-type calcium channel antagonists on the NLRP3 inflammasome. In this study, we investigated the effects of nicardipine and verapamil, both L-type calcium channel antagonists, on the NLRP3 inflammasome using differentiated THP-1 cells. Pyroptosis or levels of IL-1beta and caspase-1 were assayed by flow cytometry or enzyme-linked immunosorbent assay, respectively. ASC oligomerization was assayed by immunofluorescence microscopy. Expression of NLRP3 or TLR4 was assayed by polymerase chain reaction and immunoblotting. Nuclear factor-kappaB (NF-kappaB) pathway was also studied. Our results showed that pyroptosis and IL-1beta release were attenuated by nicardipine, but not verapamil. Nicardipine also mitigated caspase-1 activation, inhibited ASC oligomerization, and reduced NLRP3 expression. Furthermore, nicardipine downregulated phosphorylation or nuclear translocation of NF-kappaB p65, consistent with the inhibitory effect of nicardipine on LPS-induced TLR4 expression. In conclusion, nicardipine exerted anti-inflammatory effects through inhibiting NLRP3 inflammasome pathway. Nicardipine may mitigate NLRP3 priming via inhibiting NF-kappaB activation, mediated by suppressing LPS-induced TLR4 expression.