Tyagi Suresh C
Department of Physiology, University of Louisville School of Medicine, Louisville, KY 40202, USA.
Antioxidants (Basel). 2024 Oct 12;13(10):1225. doi: 10.3390/antiox13101225.
Patients with Alzheimer's disease and related dementia (ADRD) are faced with a formidable challenge of focal amyloid deposits and cerebral amyloid angiopathy (CAA). The treatment of amyloid deposits in ADRD by targeting only oxidative stress, inflammation and hyperlipidemia has not yielded significant positive clinical outcomes. The chronic high-fat diet (HFD), or gut dysbiosis, is one of the major contributors of ADRD in part by disrupted transport, epigenetic DNMT1 and the folate 1-carbon metabolism (FOCM) cycle, i.e., rhythmic methylation/de-methylation on DNA, an active part of epigenetic memory during genes turning off and on by the gene writer (DNMT1) and eraser (TET2/FTO) and the transsulfuration pathway by mitochondrial 3-mercaptopyruvate sulfur transferase (3MST)-producing HS. The repeat CAG expansion and mA disorder causes senescence and AD. We aim to target the paradigm-shift pathway of the gut-brain microbiome axis that selectively inhibits amyloid deposits and increases mitochondrial transsulfuration and HS. We have observed an increase in DNMT1 and decreased FTO levels in the cortex of the brain of AD mice. Interestingly, we also observed that probiotic lactobacillus-producing post-biotic folate and lactone/ketone effectively prevented FOCM-associated gut dysbiosis and amyloid deposits. The s-adenosine-methionine (SAM) transporter (SLC25A) was increased by hyperhomocysteinemia (HHcy). Thus, we hypothesize that chronic gut dysbiosis induces SLC25A, the gene writer, and HHcy, and decreases the gene eraser, leading to a decrease in SLC7A and mitochondrial transsulfuration HS production and bioenergetics. Lactobacillus engulfs lipids/cholesterol and a tri-directional post-biotic, folic acid (an antioxidant and inhibitor of beta amyloid deposits; reduces Hcy levels), and the lactate ketone body (fuel for mitochondria) producer increases SLC7A and HS (an antioxidant, potent vasodilator and neurotransmitter gas) production and inhibits amyloid deposits. Therefore, it is important to discuss whether lactobacillus downregulates SLC25A and DNMT1 and upregulates TET2/FTO, inhibiting β-amyloid deposits by lowering homocysteine. It is also important to discuss whether lactobacillus upregulates SLC7A and inhibits β-amyloid deposits by increasing the mitochondrial transsulfuration of HS production.
患有阿尔茨海默病及相关痴呆症(ADRD)的患者面临着局灶性淀粉样蛋白沉积和脑淀粉样血管病(CAA)这一艰巨挑战。仅针对氧化应激、炎症和高脂血症来治疗ADRD中的淀粉样蛋白沉积尚未产生显著的积极临床效果。长期高脂饮食(HFD)或肠道菌群失调是ADRD的主要促成因素之一,部分原因是其扰乱了转运、表观遗传DNA甲基转移酶1(DNMT1)和叶酸一碳代谢(FOCM)循环,即DNA上有节奏的甲基化/去甲基化,这是基因通过基因写入器(DNMT1)和擦除器(TET2/FTO)开启和关闭时表观遗传记忆的一个活跃部分,以及由线粒体3-巯基丙酮酸硫转移酶(3MST)产生硫化氢(HS)的转硫途径。CAG重复扩增和甲基化异常会导致衰老和AD。我们旨在针对肠-脑微生物群轴的范式转变途径,该途径可选择性抑制淀粉样蛋白沉积并增加线粒体转硫作用和HS。我们观察到AD小鼠大脑皮质中DNMT1增加而FTO水平降低。有趣的是,我们还观察到产生后生型叶酸和内酯/酮的益生菌乳酸杆菌有效地预防了与FOCM相关的肠道菌群失调和淀粉样蛋白沉积。高同型半胱氨酸血症(HHcy)会使S-腺苷甲硫氨酸(SAM)转运体(SLC25A)增加。因此,我们假设慢性肠道菌群失调会诱导基因写入器SLC25A和HHcy,并使基因擦除器减少,从而导致SLC7A以及线粒体转硫作用HS生成和生物能量学下降。乳酸杆菌吞噬脂质/胆固醇以及一种三向后生型物质,即叶酸(一种抗氧化剂和β淀粉样蛋白沉积抑制剂;可降低同型半胱氨酸水平),并且产生乳酸酮体(线粒体的燃料)的物质会增加SLC7A和HS(一种抗氧化剂、强效血管舒张剂和神经递质气体)的生成并抑制淀粉样蛋白沉积。因此,讨论乳酸杆菌是否下调SLC25A和DNMT1并上调TET2/FTO,通过降低同型半胱氨酸来抑制β淀粉样蛋白沉积很重要。讨论乳酸杆菌是否通过增加HS生成的线粒体转硫作用来上调SLC7A并抑制β淀粉样蛋白沉积也很重要。