Hu Xiaoling, Lin Yu, Huang Kaiwen, Xu HuiLin, Fu Changmei Huang, Ou Jiayin, Fan Xiude, Li Zhe, Fang Jiansong, Fang Shuhuan
Science and Technology Innovation Center, Guangzhou University of Chinese Medicine, 12 Airport Road, Guangzhou, 510405, China.
Department of general practice in Affiliated Hospital of Guangdong, Medical University, Zhanjiang, 524001, Guangdong, China.
Nutr Metab (Lond). 2025 Jul 11;22(1):75. doi: 10.1186/s12986-025-00960-x.
Recent research has implicated mitochondrial DNA copy number (mtDNA-CN) and Tau protein levels in the blood as potential biomarkers for early Alzheimer's disease (AD) risk assessment, correlating with metabolite profiles. However, intermediary metabolites mediating these associations remain elusive.
Employing a two-sample and a mediation Mendelian randomization (MR) analysis of the IEU OpenGWAS database, involving 383,476 participants from a genome-wide association study (GWAS) and an exome-wide association study (ExWAS), we identified intermediary metabolites linking mtDNA-CN and Tau.Meanwhile, the effects of mediating metabolites on HT22 cell viability and its mitochondrial morphology were also assessed in conjunction with in vitro experiments.
Our study revealed an association of mtDNA-CN on Tau (OR = 3.102, 95% CI: 1.016-9.472, P = 0.047), as well as on other 31 metabolites such as 3-Hydroxybutyrate (3HB), Docosahexaenoic acid (DHA), Acetate, Albumin, Apolipoprotein A-I (APOA1), and so on. Notably, 3HB was further implicated in a relationship with Tau (OR = 6.030, 95% CI: 1.054-34.491, P = 0.043), acting as a mediator between mtDNA-CN and Tau. In vitro experiments demonstrated that 3HB positively sustained HT22 cell viability by MTT assay and mitigated mitochondrial swelling under low glucose conditions, as observed via HIS-SIM. In Western blot (WB) and quantitative real-time PCR (qPCR) assays, phosphorylation levels of Tau at serine 262 (p-Tau262) and serine 396 (p-Tau396) were tended to decline following 3HB intervention. Additionally, a positive correlation was identified between 3HB concentration and mtDNA-CN.
These findings underscore the potential of 3HB as a biomarker and mediator in early AD risk assessment. Moreover, 3HB's ability to enhance cell viability, maintain mitochondrial morphology, decrease phosphorylated Tau protein expression and increase mtDNA-CN under stressful conditions, suggesting its therapeutic potential in improving the imbalance of energy metabolism in the AD brain.
最近的研究表明，血液中的线粒体DNA拷贝数（mtDNA-CN）和Tau蛋白水平可能是早期阿尔茨海默病（AD）风险评估的潜在生物标志物，与代谢物谱相关。然而，介导这些关联的中间代谢物仍然难以捉摸。
利用IEU OpenGWAS数据库的两样本和中介孟德尔随机化（MR）分析，涉及来自全基因组关联研究（GWAS）和外显子组关联研究（ExWAS）的383476名参与者，我们确定了连接mtDNA-CN和Tau的中间代谢物。同时，还结合体外实验评估了介导代谢物对HT22细胞活力及其线粒体形态的影响。
我们的研究揭示了mtDNA-CN与Tau之间的关联（OR = 3.102，95% CI：1.016 - 9.472，P = 0.047），以及与其他31种代谢物的关联，如3-羟基丁酸（3HB）、二十二碳六烯酸（DHA）、乙酸盐、白蛋白、载脂蛋白A-I（APOA1）等。值得注意的是，3HB进一步与Tau存在关联（OR = 6.030，95% CI：1.054 - 34.491，P = 0.043），充当mtDNA-CN和Tau之间的中介。体外实验表明，通过MTT法，3HB能积极维持HT22细胞活力，并且在低葡萄糖条件下通过HIS-SIM观察到可减轻线粒体肿胀。在蛋白质免疫印迹（WB）和定量实时聚合酶链反应（qPCR）分析中，3HB干预后，Tau在丝氨酸262（p-Tau262）和丝氨酸396（p-Tau396）处的磷酸化水平趋于下降。此外，还确定了3HB浓度与mtDNA-CN之间存在正相关。
这些发现强调了3HB作为早期AD风险评估中的生物标志物和中介的潜力。此外，3HB在应激条件下增强细胞活力、维持线粒体形态、降低磷酸化Tau蛋白表达以及增加mtDNA-CN的能力，表明其在改善AD大脑能量代谢失衡方面具有治疗潜力。
