Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Miklukho-Maklaya 16/10, Moscow, 117997, Russian Federation.
Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Malaya Pirogovskaya 1a, Moscow, 119435, Russian Federation.
BMC Biol. 2024 Aug 26;22(1):178. doi: 10.1186/s12915-024-01975-1.
The previously underestimated effects of commensal gut microbiota on the human body are increasingly being investigated using omics. The discovery of active molecules of interaction between the microbiota and the host may be an important step towards elucidating the mechanisms of symbiosis.
Here, we show that in the bloodstream of healthy people, there are over 900 peptides that are fragments of proteins from microorganisms which naturally inhabit human biotopes, including the intestinal microbiota. Absolute quantitation by multiple reaction monitoring has confirmed the presence of bacterial peptides in the blood plasma and serum in the range of approximately 0.1 nM to 1 μM. The abundance of microbiota peptides reaches its maximum about 5 h after a meal. Most of the peptides correlate with the bacterial composition of the small intestine and are likely obtained by hydrolysis of membrane proteins with trypsin, chymotrypsin and pepsin - the main proteases of the gastrointestinal tract. The peptides have physicochemical properties that likely allow them to selectively pass the intestinal mucosal barrier and resist fibrinolysis.
The proposed approach to the identification of microbiota peptides in the blood, after additional validation, may be useful for determining the microbiota composition of hard-to-reach intestinal areas and monitoring the permeability of the intestinal mucosal barrier.
共生肠道微生物群对人体的先前被低估的影响，正越来越多地通过组学来进行研究。发现微生物群与宿主之间相互作用的活性分子可能是阐明共生机制的重要步骤。
在这里，我们表明在健康人的血液中，有超过 900 种肽段是天然栖息于人体生物区系（包括肠道微生物群）的微生物蛋白的片段。通过多重反应监测的绝对定量已经证实了血液血浆和血清中细菌肽的存在，其范围约为 0.1 nM 至 1 μM。微生物肽的丰度在进食后约 5 小时达到最大值。大多数肽与小肠的细菌组成相关，并且可能通过用胰蛋白酶、糜蛋白酶和胃蛋白酶（胃肠道的主要蛋白酶）水解膜蛋白获得。这些肽具有可能允许它们选择性地通过肠黏膜屏障并抵抗纤维蛋白溶解的物理化学性质。
在进一步验证后，提议的用于鉴定血液中微生物群肽的方法，可能有助于确定难以到达的肠道区域的微生物群组成并监测肠黏膜屏障的通透性。
