美国宾夕法尼亚大学Joseph A. Baur团队阐明烟酰胺腺嘌呤二核苷酸(NAD)前体在宿主组织和肠道微生物群之间循环。该研究于2022年12月6日发表于国际一流学术期刊《细胞—代谢》杂志上。

他们使用同位素示踪来研究小鼠肠道微生物组中支持NAD合成的前体。他们发现，饮食中的NAD前体在胃肠道的近端被吸收，而远端肠道的微生物则无法获得。相反，循环的宿主烟酰胺进入肠腔并支持微生物NAD的合成。微生物组将宿主来源的烟酰胺转化为烟酸，用于宿主组织中NAD的合成，即使在没有饮食摄入的情况下也能维持循环烟酸水平。

此外，从口服烟酰胺核苷(一种广泛使用的营养药物)到宿主NAD的主要途径是通过肠道微生物组转化为烟酸。因此，他们建立了循环宿主微量营养素喂养肠道微生物群的能力，并反过来以增强宿主代谢灵活性的方式进行转化。

据了解，NAD是哺乳动物和微生物体内重要的氧化还原辅因子。

附：英文原文

Title: NAD precursors cycle between host tissues and the gut microbiome

Author: Karthikeyani Chellappa, Melanie R. McReynolds, Wenyun Lu, Xianfeng Zeng, Mikhail Makarov, Faisal Hayat, Sarmistha Mukherjee, Yashaswini R. Bhat, Siddharth R. Lingala, Rafaella T. Shima, Hélène C. Descamps, Timothy Cox, Lixin Ji, Connor Jankowski, Qingwei Chu, Shawn M. Davidson, Christoph A. Thaiss, Marie E. Migaud, Joshua D. Rabinowitz, Joseph A. Baur

Issue&Volume: 2022/12/06

Abstract: Nicotinamide adenine dinucleotide (NAD) is an essential redox cofactor in mammals and microbes. Here we use isotope tracing to investigate the precursors supporting NAD synthesis in the gut microbiome of mice. We find that dietary NAD precursors are absorbed in the proximal part of the gastrointestinal tract and not available to microbes in the distal gut. Instead, circulating host nicotinamide enters the gut lumen and supports microbial NAD synthesis. The microbiome converts host-derived nicotinamide into nicotinic acid, which is used for NAD synthesis in host tissues and maintains circulating nicotinic acid levels even in the absence of dietary consumption. Moreover, the main route from oral nicotinamide riboside, a widely used nutraceutical, to host NAD is via conversion into nicotinic acid by the gut microbiome. Thus, we establish the capacity for circulating host micronutrients to feed the gut microbiome, and in turn be transformed in a manner that enhances host metabolic flexibility.

DOI: 10.1016/j.cmet.2022.11.004

Source: https://www.cell.com/cell-metabolism/fulltext/S1550-4131(22)00495-8