Novel compound L22 potently inhibits NLRP3 inflammasome, alleviating ulcerative colitis in animal model

The NLRP3 inflammasome is a crucial multi-protein complex in the innate immune system, driving inflammatory processes. Its dysregulated activation is implicated in numerous inflammatory diseases, making it a highly promising therapeutic target. Current treatments often lack specificity or have significant side effects, highlighting the need for novel, potent, and safe inhibitors. This study builds upon preliminary findings that istradefylline, an anti-Parkinsonian agent, exhibits moderate NLRP3 inhibitory activity, aiming to optimize its structure for enhanced potency.

Researchers designed and synthesized a series of novel thieno[2,3-d]pyrimidin-4(3H)-one-based compounds, optimizing the structure of istradefylline. They evaluated their NLRP3 inhibitory activity using in vitro assays, identifying L22 as the most potent candidate. The direct binding of L22 to the NLRP3 NACHT domain was confirmed. Its oral bioavailability was assessed, and its efficacy was tested in a DSS-induced ulcerative colitis model. Additionally, acute and subacute toxicity studies were conducted to evaluate the safety profile of L22.

Compound L22 demonstrated the most potent NLRP3 inhibitory activity among the synthesized series, achieving an IC50 of 0.16 μM. This represents a 10-fold stronger inhibition compared to istradefylline's IC50 of 1.81 μM. Mechanistically, L22 directly bound to the NLRP3 NACHT domain with a dissociation constant (KD) of 357.8 nM, effectively inhibiting inflammasome assembly and activation. In vivo, orally bioavailable L22 significantly alleviated symptoms in a DSS-induced ulcerative colitis model. Acute and subacute toxicity studies further indicated that L22 possesses a favorable safety profile.

L22 exhibited an IC50 of 0.16 μM for NLRP3 inhibition, making it 10-fold more potent than istradefylline.