Development of Novel Tetrahydroquinoline Inhibitors of NLRP3 Inflammasome for Potential Treatment of DSS-Induced Mouse Colitis

Abstract

The NLRP3 inflammasome is a critical component of innate immunity, which defends internal and external threats. However, inappropriate activation of the NLRP3 inflammasome induces various human diseases. In this study, we discovered and synthesized a series of tetrahydroquinoline inhibitors of NLRP3 inflammasome. Among these analogues, compound 6 exhibited optimal NLRP3 inhibitory activity. In vitro studies indicated that compound 6 directly bound to the NACHT domain of NLRP3 but not to protein pyrin domain (PYD) or LRR domain, inhibited NLRP3 ATPase activity, and blocked ASC oligomerization, thereby inhibiting NLRP3 inflammasome assembly and activation. Compound 6 specifically inhibited the NLRP3 inflammasome activation, but had no effect on the activation of NLRC4 or AIM2 inflammasomes. Furthermore, in the dextran sulfate sodium (DSS)-induced colitis mouse model, compound 6 exhibited significant anti-inflammatory activity through inhibiting NLRP3 inflammasome in vivo. Therefore, our study provides a potent NLRP3 inflammasome inhibitor, which deserves further structural optimization as a novel therapeutic candidate for NLRP3-driven diseases.

Targeting the NLRP3 Inflammasome as a New Therapeutic Option for Overcoming Cancer

“…Other compounds have been shown to be effective for the treatment of DSS-induced experimental colitis in mice. A novel tetrahydroquinoline inhibitor of NLRP3, compound 6, specifically inhibits NLRP3 activation in vivo and attenuates colitis severity in the DSS mouse model [ 167 ] by directly binding to the NACHT domain of NLRP3, inhibiting its ATPase activity and blocking ASC oligomerization [ 167 ]. 1-Ethyl-5-methyl-2-phenyl-1H-benzo[d]imidazole, a synthetic small molecular compound also named Fc11a-2, was shown to induce beneficial effects in the treatment of DSS-induced experimental colitis in mice by targeting the NLRP3 inflammasome and inhibiting cytokine release [ 168 ].…”

The Role of NLRP3 Inflammasome in Cerebrovascular Diseases Pathology and Possible Therapeutic Targets

“…Numerous of drug studies have observed that inhibition of the upstream NLRP3 inflammasome pathway and IL-1β has a protective effect on NLRP3 inflammasome-mediated diseases, but these drugs are less specific and may evade the target. Currently available clinical therapies for NLRP3-associated diseases include drugs that target IL-1β, such as the recombinant IL-1 receptor antagonist anakinra, the neutralising IL-1β antibody canakinumab, and the soluble decoy IL-1β receptor lilonapil ( Jiang et al., 2017 ; Dai et al., 2021 ). However, the suppression of NLRP3 expression is more efficient and economical.…”

“…MCC950, also known as CP-456773 or CRID3 ( Guzova et al., 2019 ; Kuwar et al., 2019 ), is widely known as the most potent and specific NLRP3 inhibitor ( Dai et al., 2021 ). It is often used as a positive control to compare the efficacy of novel NLRP3 inhibitors; for instance, the discovery of nitrostitu-quinazolin-4 (3H)-one 2 K to inhibit the activation of NLRP3 inflammatory body by occupying the ATP-binding site of NLRP3 protein ( Abdullaha et al., 2019 ).…”

“…Instead of binding to NEK7, MCC950 directly targets an NLRP3 site, in or near the Walker B motifs to block ATP hydrolysis, resulting in the formation of an inactivated NLRP3 structure, thereby preventing the activation of NLRP3 ( Tapia-Abellan et al., 2019 ). In recent years, it has been observed that MCC950 inhibits ASC oligomerization and inhibits the cleavage of caspase-1 (p20) (Chow et al., 2020; Dai et al., 2021 ). Guzova et al.…”

“…Compound 6, a tetrahydroquinoline inhibitor synthesised by Dai et al. (2021) , inhibited NLRP3 inflammasome activity in vivo and in vitro , but did not affect AIM2 and NLRC4 inflammasomes ( Dai et al., 2021 ). Regarding the mechanism of action, compound 6 did not block potassium extravasation and did not bind to the PYD or LRR domain.…”