In a new study, mice whose immune systems were trained against the microbial protein flagellin did not experience the usual detrimental effects of ingesting emulsifying food additives, pointing to a possible new way to combat various chronic inflammatory diseases.
Dietary emulsifiers are substances added to processed foods to prevent mixed ingredients from separating. Previous research has suggested that consumption of certain emulsifiers may alter the gut microbiome in such a way that it increases the ability of some microbes to invade the protective mucosal lining of the gut, and may lead to chronic intestinal inflammation.
Flagellin, a protein expressed by many bacteria that forms their whip-shaped flagella, allowing them to swim and therefore conferring motility, may play a key role in promoting such inflammation.
Training the gut’s immune system to attack flagellin
Building on that earlier research, Melissa Kordahi and Benoit Chassaing, researchers at Inserm, Institut Cochin and Université Paris Cité, France, and their colleagues hypothesized that training the gut’s immune system to attack flagellin, immunizing it against it, could help protect against the harmful consequences of consuming food emulsifiers.
To test this idea, they immunized mice against flagellin for several weeks and then fed them food containing two common food emulsifiers, carboxymethylcellulose (E466) and polysorbate 80 (E433). .
They observed that immunized mice did not experience invasion of microbes into their mucosa after ingesting emulsifiers. Furthermore, immunization also appeared to protect against chronic intestinal inflammation and metabolic deregulations normally observed after ingestion of emulsifiers.
The researchers also note that, after eating foods with emulsifiers, mice immunized with flagellin continued to experience changes in the proportions of several species of microbes that make up their gut microbiomes.
This suggests that the protective effects of flagellin immunization may be related to its effects on microbial function and movement and not solely to an effect on microbiota composition.
They note that more research will be needed to further understand the potential use of flagellin immunization and the extent to which these findings could translate to humans in the future, but this study suggests that flagellin immunization could be a potential new strategy. to protect against inflammatory conditions that may be promoted by alterations in the host-microbiota interaction, such as inflammatory bowel disease, obesity and type 2 diabetes.
Preventing chronic inflammatory conditions
“This study suggests that selective modulation of the gut microbiota may be an effective way to prevent various chronic inflammatory conditions, such as metabolic deregulations that occur during the consumption of commonly used food additives,” concludes Chassaing.