Linarin alleviates dextran sulfate sodium-induced colitis in C57BL/6J mice by suppressing the NADPH oxidase 1/ROS/NLRP3 inflammasome signaling axis.

Abnormal activation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, driven by reactive oxygen species (ROS) overproduction, is considered a critical event in the pathogenesis of ulcerative colitis (UC). Linarin (LN), a naturally occurring flavonoid glycoside, exhibits antioxidant and anti-inflammatory activities; however, the host signaling mechanism underlying its protective effect against colitis remains incompletely understood. In the present study, forty male C57BL/6J mice were randomly assigned to normal control, dextran sulfate sodium (DSS), LN plus DSS, and 2-acetylphenothiazine (ML171) plus DSS groups. Colitis severity and mechanism were evaluated by body weight change, disease activity index (DAI), colon length, histopathology, ROS detection, Caspase-1 activity, immunofluorescence, real-time quantitative polymerase chain reaction (RT-qPCR), and western blot analysis. Mechanistic validation was further performed in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and DSS-challenged Caco-2 cells. LN significantly attenuated DSS-induced colitis, as evidenced by reduced body weight loss, lower DAI scores, prevention of colon shortening, and improved histopathological injury and mucin depletion. Mechanistically, LN suppressed NADPH oxidase 1 (NOX1) overexpression and ROS accumulation, thereby inhibiting the assembly and activation of the NLRP3 inflammasome and subsequent interleukin (IL)-1β secretion. Furthermore, LN rebalanced the inflammatory cytokine profile by decreasing IL-6, tumor necrosis factor-α (TNFα), interferon-γ (IFN-γ), and IL-1β mRNA expression, while increasing IL-10 expression. LN also restored the expression of tight junction proteins Zonula occludens-1 (ZO-1), Occludin, and Claudin-1. The NOX1-specific inhibitor ML171 produced largely similar effects, supporting the mechanistic relevance of NOX1 suppression. In summary, LN alleviates experimental colitis by inhibiting the NOX1/ROS/NLRP3 inflammasome signaling axis, thereby attenuating inflammatory responses and restoring intestinal epithelial barrier integrity. These findings highlight LN as a promising preclinical candidate for the prevention or early intervention of UC.