Yang Qingfan, Diao Na, Ma Fei, Huang Zicheng, Lin Minzhi, Liu Xinyu, Guo Qin, Li Pan, Tang Jian, Gao Xiang, Chao Kang
Department of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
Biomedical Innovation Center, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
Cell Death Dis. 2024 Dec 20;15(12):923. doi: 10.1038/s41419-024-07276-3.
Lipid metabolism disorder is a critical feature of Crohn's disease (CD). Phosphatidylinositol (PI) and its derivative, phosphatidylinositol bisphosphate (PIP2), are associated with CD. The mechanisms underlying such association remain unknown. In this study, we explored the role played by the major PI derivative, phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2], in CD pathogenesis. The relationship between CD activity and PI or PIP2 was analyzed via lipidomics. The mucosal expression of PI(4,5)P2 in patients with CD was measured using immunofluorescence. The function and mechanism of PI(4,5)P2 were examined in dextran sulfate sodium (DSS)-induced colitis mice and lipopolysaccharide (LPS)-induced Caco-2 cell models, along with MeRIP and mRNA sequencing. The results suggested lipid PI and PIP2 were substantially negatively associated with disease activity and high-sensitivity C-reactive protein. PI(4,5)P2 was substantially downregulated in the inflamed mucosa of patients with CD. PI(4,5)P2 alleviated mouse colitis, with improvements in survival rate, colon length, weight, and disease activity index. PI(4,5)P2 also alleviated DSS-induced tissue damage, tight junction loss, and intestinal epithelial cell (IEC) pyroptosis. In the in vitro LPS-induced cell model, PI(4,5)P2 inhibited pyroptosis, as well as NLRP3, and caspase-1 expression, in addition to reducing interleukin (IL)-18, IL-1β, and lactate dehydrogenase (LDH) secretion. PI(4,5)P2 mediated NNMT upregulation in mice and Caco-2 cells and suppressed pyroptosis in IECs. NNMT knockdown restricted the inhibitory effect of PI(4,5)P2 on IEC pyroptosis. NNMT inhibited the stability of RBP4 mRNA via m6A modification, thereby preventing pyroptosis following PI(4,5)P2 treatment. Significant correlations were also observed between PI(4,5)P2 and NNMT, NNMT and RBP4, and RBP4 and GSDMD expression in the intestinal tissues from patients with CD. Our results indicated that PI(4,5)P2 ameliorates colitis by inhibiting IEC pyroptosis via NNMT-mediated RBP4 m6A modification. Thus, PI(4,5)P2 shows potential as a therapeutic target in CD.
脂质代谢紊乱是克罗恩病（CD）的一个关键特征。磷脂酰肌醇（PI）及其衍生物磷脂酰肌醇二磷酸（PIP2）与CD相关。这种关联背后的机制尚不清楚。在本研究中，我们探讨了主要的PI衍生物磷脂酰肌醇4,5-二磷酸[PI(4,5)P2]在CD发病机制中所起的作用。通过脂质组学分析了CD活动与PI或PIP2之间的关系。使用免疫荧光法检测了CD患者中PI(4,5)P2的黏膜表达。在葡聚糖硫酸钠（DSS）诱导的结肠炎小鼠和脂多糖（LPS）诱导的Caco-2细胞模型中，结合MeRIP和mRNA测序研究了PI(4,5)P2的功能和机制。结果表明，脂质PI和PIP2与疾病活动和高敏C反应蛋白显著负相关。PI(4,5)P2在CD患者的炎症黏膜中显著下调。PI(4,5)P2减轻了小鼠结肠炎，提高了存活率、结肠长度、体重和疾病活动指数。PI(4,5)P2还减轻了DSS诱导的组织损伤、紧密连接丧失和肠上皮细胞（IEC）焦亡。在体外LPS诱导的细胞模型中，PI(4,5)P2除了减少白细胞介素（IL）-18、IL-1β和乳酸脱氢酶（LDH）分泌外，还抑制了焦亡以及NLRP3和半胱天冬酶-1的表达。PI(4,5)P2介导了小鼠和Caco-2细胞中NNMT的上调，并抑制了IEC中的焦亡。敲低NNMT限制了PI(4,5)P2对IEC焦亡的抑制作用。NNMT通过m6A修饰抑制RBP4 mRNA的稳定性，从而防止PI(4,5)P2处理后的焦亡。在CD患者的肠道组织中，PI(4,5)P2与NNMT、NNMT与RBP4以及RBP4与GSDMD表达之间也观察到显著相关性。我们的结果表明，PI(4,5)P2通过NNMT介导的RBP4 m6A修饰抑制IEC焦亡来改善结肠炎。因此，PI(4,5)P2显示出作为CD治疗靶点的潜力。
