음식의 miRNA가 섭취자에게 주는 영향

https://www.nature.com/articles/d41586-020-01767-x

Zempleni, a molecular nutritionist at the University of Nebraska–Lincoln, like many others in the field, was struck by the findings of an astonishing study published in Cell Research suggesting that food could provide something other than nutrients — information from ingested plants could switch mammalian genes on and off1. In the study, researchers reported that microRNAs (miRNAs) — very short fragments of non-coding RNA molecules — originating from plants such as rice had been found in the bloodstream of mice, cows and humans.

But misgivings about the Cell Research study soon began to surface. Not only were Witwer and several others unable to reproduce the findings, but some of its basic premises were also called into question. Scientists doubted that diet-derived miRNAs could make it into the systemic circulation of animal hosts at sufficient levels to have a meaningful impact. Follow-up work also revealed the strong possibility that the ‘diet-derived’ miRNAs were actually the result of contamination.

Zempleni wondered whether the miRNAs in milk go beyond the gastrointestinal tract. But he quickly encountered a problem: the miRNA molecules themselves rapidly degraded in the gut. “We realized what matters is really not just the miRNAs,” Zempleni says. “What’s at least equally important is the shell in which these miRNAs are packaged.” This shell is a bubble-like vessel called an exosome. “In order for miRNAs to be bioavailable and to be absorbed from the gut, they have to be encapsulated in these exosomes,” Zempleni says. As others had shown, fragile miRNAs need to be protected in these containers to be transported from cell to cell.

Zempleni and his colleagues devised a method for labelling the miRNAs contained in cow’s milk exosomes with fluorescent compounds. These could then be tracked in animal models. “This technology confirmed that these microRNAs, if encapsulated in exosomes, accumulate in various tissues,” he says — mainly the brain, liver and intestinal mucosa

This established that the miRNAs could reach not just local sites (the gut wall), but also distant ones. Turning, then, to the question of how the miRNA-containing exosomes were affecting host health, Zempleni carried out various experiments in which he gave mice a diet deficient in both free miRNAs and miRNA-containing exosomes, and compared them with other mice consuming a diet that had normal levels of each. He found a range of effects, including a decrease in the cognitive performance of mice receiving the depleted diet, a decrease in fecundity and changes in muscular growth

Some of Zempleni’s animal-model work is based on the idea that exosomes interact with the gut microbiota — the community of microorganisms involved in the health effects conferred by a host’s diet. This led to the hypothesis that the gut microbiota might mediate cell-to-cell communication between milk exosomes and mammalian hosts.

Zhang hopes that, by learning which host cells (in the gut and elsewhere) preferentially take up different plant-derived exosome-like nanoparticles, researchers could assemble new nanoparticles for use as drug-delivery vehicles to very specific cell types in the body.

 

exosome 형태로 miRNA가 있다면, 그것을 섭취하는 host에게 영향을 줄 수 있다는 내용이다. 

확실한 것은 아니지만, 가능성들이 제시되고 있다.