Li Yuqian, Hou Lijingzhe, Cheng Kang, He Guangbo, Hong Jau-Shyong, Li Sheng, Zhao Jie, Guo Yanjie
Department of Pathogen Biology and Microecology, Pathogen Biology Laboratory, School of Basic Medical Science, Dalian Medical University, Dalian, 116044, China.
Neurobiology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, Durham, NC, 27709, USA.
Free Radic Biol Med. 2025 Nov;239:189-201. doi: 10.1016/j.freeradbiomed.2025.07.044. Epub 2025 Jul 29.
Inflammatory bowel disease (IBD), including Crohn's disease and ulcerative colitis, is a chronic inflammatory condition of the gastrointestinal tract with limited treatment options and no definitive cure. Emerging evidence implicates NADPH oxidase (Nox) in IBD pathogenesis, but the specific subtype involved and its therapeutic potential remain unclear. To assess the efficacy of dextromethorphan (DM), a potent Nox2 inhibitor, we employed a dextran sulfate sodium (DSS)-induced chronic colitis model in mice. Mice exposed to intermittent DSS for 34 days developed IBD-like symptoms, including weight loss, elevated disease activity index (DAI), colon shortening, and epithelial barrier disruption. DM exhibited a bimodal protective effect: both standard-dose DM (10 mg/kg/day) and ultralow-dose DM (ULDM, 10 ng/kg/day) significantly reduced colitis severity, with ULDM proving more effective and selected for further studies. Notably, ULDM remained effective when post-administered after DSS exposure. Histological analyses revealed that ULDM reduced immune cell infiltration, crypt damage, and tissue disruption. It also suppressed pro-inflammatory cytokine expression (MCP-1, IL-6, IL-1β, TNF-α) and oxidative stress markers (myeloperoxidase, malondialdehyde, 8-hydroxydeoxyguanosine), while enhancing anti-inflammatory cytokines (IL-4, IL-10) and antioxidant enzymes (catalase, superoxide dismutase). Importantly, ULDM protected Nox1 KO but not Nox2 KO mice, indicating a Nox2-dependent mechanism. In vitro, ULDM inhibited Nox2 activation in primary macrophages and RAW 264.7 cells by blocking the membrane translocation of p47. Furthermore, our study suggested a feed-forward inflammatory cycle between epithelial cell death and macrophage overactivation that exacerbated colitis. Together, these findings demonstrated that Nox2 played a central role in DSS-induced chronic colitis and identified ultralow-dose dextromethorphan as a promising, mechanism-based therapeutic candidate for IBD.
炎症性肠病（IBD），包括克罗恩病和溃疡性结肠炎，是一种胃肠道的慢性炎症性疾病，治疗选择有限且无法根治。新出现的证据表明NADPH氧化酶（Nox）参与了IBD的发病机制，但所涉及的具体亚型及其治疗潜力仍不清楚。为了评估强效Nox2抑制剂右美沙芬（DM）的疗效，我们在小鼠中采用了葡聚糖硫酸钠（DSS）诱导的慢性结肠炎模型。暴露于间歇性DSS 34天的小鼠出现了IBD样症状，包括体重减轻、疾病活动指数（DAI）升高、结肠缩短和上皮屏障破坏。DM表现出双峰保护作用：标准剂量DM（10毫克/千克/天）和超低剂量DM（ULDM，10纳克/千克/天）均显著降低了结肠炎的严重程度，其中ULDM被证明更有效并被选用于进一步研究。值得注意的是，在DSS暴露后给予ULDM仍然有效。组织学分析显示，ULDM减少了免疫细胞浸润、隐窝损伤和组织破坏。它还抑制了促炎细胞因子表达（MCP-1、IL-6、IL-1β、TNF-α）和氧化应激标志物（髓过氧化物酶、丙二醛、8-羟基脱氧鸟苷），同时增强了抗炎细胞因子（IL-4、IL-10）和抗氧化酶（过氧化氢酶、超氧化物歧化酶）。重要的是，ULDM保护Nox1基因敲除小鼠但不保护Nox2基因敲除小鼠，表明其机制依赖于Nox2。在体外，ULDM通过阻断p47的膜转位抑制原代巨噬细胞和RAW 264.7细胞中的Nox2激活。此外，我们的研究提示了上皮细胞死亡和巨噬细胞过度激活之间的前馈炎症循环，这加剧了结肠炎。总之，这些发现表明Nox2在DSS诱导的慢性结肠炎中起核心作用，并确定超低剂量右美沙芬是一种有前景的、基于机制的IBD治疗候选药物。
