Rubimainllin targets NLRP3 to suppress inflammasome activation and attenuate NLRP3-driven inflammatory diseases

Background: The NLR family pyrin domain-containing 3 (NLRP3) inflammasome hyper-activation is a shared pathogenic driver of multiple inflammatory, metabolic and neurodegenerative disorders, yet clinically approved inhibitors remain lacking. Purpose: To investigate whether Rubimainllin (Rub), a naphthoquinone isolated from Rubia cordifolia L., selectively inhibits NLRP3 inflammasome activation and exert therapeutic effects in relevant disease models. Methods: Macrophages and microglia were primed with Lipopolysaccharide (LPS) for 3 h, then stimulated with Nigericin (Nig) (2 h) or ATP (40 min) to induce NLRP3 inflammasome assembly and pyroptosis; caspase-1 activation, ASC speck formation, IL-1β release, and LDH secretion were quantified. The therapeutic potential of Rubimainllin was assessed in murine models of NLRP3-driven inflammation. Animals received intraperitoneal Rub (5 or 10 mg mg/kg) or vehicle in models of (i) LPS-induced peritonitis, (ii) monosodium urate crystal (MSU)-induced gouty arthritis (RA), and (iii) hippocampal Aβ 1-42-induced Alzheimer's disease (AD). Diseases severity was evaluated by histopathology, cytokine profiling, and behavioral tests. Results: Rub dose-dependently suppressed NLRP3-mediated pyroptosis and IL-1β secretion in macrophages and microglia without affecting AIM2 or NLRC4 pathways. Mechanistically, Rub directly bound NLRP3, blocked ASC oligomerization and NLRP3 oligomer formation, thereby preventing caspase-1 activation and [gasdermin D](https://www.sciencedirect.com/topics/immunology-and-microbiology/gasdermin-d) (GSDMD) cleavage. In vivo, Rub prolonged survival and attenuated lung injury in LPS-sepsis, reduced paw swelling and bone erosion in MSU-gout, and ameliorated cognitive deficits and neuroinflammation in Aβ-induced Alzheimer's disease (AD) mice. Conclusion: Rub selectively targets NLRP3 and constitutes a promising natural lead compound for the treatment of NLRP3-driven inflammatory diseases including sepsis, gout and Alzheimer's disease.