Lipids are essential for maintaining good health. Although lipids are well-known as sources of nutrition and energy, they also carry out a variety of different roles in the body such as acting as materials for biological membranes and as signal molecules. A large number of different lipid molecules exist within the body, and reports have indicated that the level of diversity present may have effects on various vital phenomena. For example, the linoleic acid that vegetable oils contain in large amounts and the arachidonic acid found in meat are both omega-6 fatty acids, while fish oil contains omega-3 fatty acids such as EPA and DHA in large quantities. The ratio of intake of these two types of fatty acids affects fat metabolism balance within the body and is also said to be involved in both metabolic syndrome and arteriosclerosis. With a clear understanding of the relationship of human illness and biological function of these kinds of lipid qualities, it's extremely important for us to be aware of the style and balance of lipid presence in the body. By using a mass spectrometer (MS) to study the fatty acid and phospholipid metabolism within the body through metabolomics both comprehensively and qualitatively, we clarified the lipid metabolism balance changes when inflammation occurred. The results indicated the importance of this balance for inflammation regulation.
On the other hand, the quality of lipids within the body is affected by a variety of factors in addition to the organism itself. One representative example of this is the presence of intestinal bacteria. Intestinal bacteria are organisms that coexist with the digestive tract of their human hosts, and humans typically host 1,000 strains with a total count of 100 trillion bacteria. Intestinal bacteria are considered to play a role in maintaining homeostasis not just for the intestinal tract but all other organs of the body as well. Compounds derived from short-chain fatty acids and linoleic acid such as hydroxy fatty acid HYA which are produced as intestinal bacteria metabolites are known to affect processes throughout the body. As a result, capturing the intestinal bacteria lipid metabolism is an important task for the sake of clarifying the mechanisms for maintaining homeostasis in various bodily systems. However, the intestinal bacteria we host metabolize fatty acids in unique ways that we as mammals cannot replicate, and the complex metabolic reactions created through interrelationships of the numerous varieties of intestinal bacteria in our bodies cannot be comprehensively researched with current technology. For this reason, we used traditional targeted metabolomics and a quadrupole time-of-flight mass spectrometer (Q-TOF MS) for non-targeted lipidomics to analyze the complex lipid metabolism environment of the intestines. Although the traditional targeted analysis measures specific well-known intestinal bacteria fat metabolites such as HYA with high sensitivity, non-targeted analysis can be used not only to investigate a wide range of known molecules but also to detect unexpected molecules and identify structures. Using this comprehensive analysis method, we discovered that there are more than 1,000 different types of lipid molecules present in the intestines, including molecules almost never found in mammals such as glycolipids and oxidated ceramides.
The cutting-edge lipidomics technique we used this time enables a more precise and comprehensive study of fat metabolites in the body, and I think our findings will connect to further understanding of not only intestinal bacteria but also the effects that lipids have on people's health, as well as identification of the action mechanisms of new molecules.
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