The small intestine is central to digesting and absorbing dietary fat, and good fat‑use efficiency is tightly linked to intestinal health in young piglets.

A research team by Academician YIN Yulong from the Institute of Subtropical Agriculture (ISA) Chinese Academy of Sciences (CAS) reveals a new role of gut microbiota-derived extracellular vesicles in lipid metabolism.

The new study was published in Journal of Extracellular Vesicles Sept 28.

Prior studies mostly focused on bacterial metabolites to explain microbiota‑host crosstalk in fat processing. This work shifts attention to tiny membrane‑wrapped packages known as extracellular vesicles released by gut microbes. Based on divergent crude‑fat digestibility among weaned piglets, the team found piglets with superior fat utilization harbored less Clostridium butyricum in ileal mucosa.

Animal trials verified that this bacterium suppresses intestinal fat absorption and oxidation. Rather than its well‑known metabolite butyrate, its secreted extracellular vesicles act as core messengers. These vesicles enter gut epithelial cells and deliver bacterial milRNAs. Of these molecules, milRNA‑3020179 targets host key genes PPARα and Rxra to modulate lipid‑related signaling pathways.

In high‑fat‑diet mouse models, both live bacteria and purified vesicles mitigated excess lipid accumulation and metabolic disturbances. When milRNA‑3020179 was knocked out in intestinal organoid tests, the bacterium largely lost its lipid‑inhibiting function, confirming the vital role of this vesicle‑loaded small RNA in bacteria‑host metabolic crosstalk.

This study expands our knowledge regarding C. butyricum function and constructs a regulatory framework for interactions between bacteria, extracellular vesicles, small RNAs and the host. It further provides new practical paths to develop microbiota‑based strategies for improving fat utilization and gut health in pig farming.

Contact: ZHOU Xihong

E-mail: xhzhou@isa.ac.cn

Graphic Abstract(Imaged by ZHOU Xihong)