Chinese scientists discover 'bacterial diplomat' that boosts gut immunity

(ECNS) — Chinese researchers have discovered a protein that helps regulate gut immunity by facilitating cooperation between intestinal cells and specific bacteria, according to a study published Wednesday in the journal Nature.

The study found that intestinal epithelial cells in mice secrete a protein called APOL9, which corresponds to APOL2 in humans. Rather than directly killing bacteria, the protein helps trigger the release of outer membrane vesicles (OMVs) from certain bacteria. These vesicles can activate immune responses and enhance the body's defense against harmful microbes.

Researchers compared APOL9 to a "bacterial diplomat" that enables precise communication and cooperation between the host and gut microbiota, helping maintain immune balance.

The gut is home to trillions of microorganisms. While some are beneficial, others may be harmful. The human body uses the intestinal epithelial barrier to manage this microbial ecosystem through mucus layers and antimicrobial proteins.

The research was conducted by Qian Youcun's team at the Shanghai Institute of Nutrition and Health under the Chinese Academy of Sciences (CAS), in collaboration with Song Xinyang's team at the CAS Center for Excellence in Molecular Cell Science.

The study took more than 11 years to complete.

"This discovery shows that the host is not passively tolerating microbes, but actively engaging in molecular dialogue to maintain microbial balance," said Qian. He added that the team will further explore the function of human APOL2 and its potential in strengthening gut immunity.

Song noted that Chinese labs remain at the forefront of global research on symbiotic microorganisms and have the potential to catch up with and even surpass leading international efforts in the field.

(By Zhao Li)