The probiotic E. coli Nissle and the dietary fiber β-glucan stimulate immune cells of pigs in petri dishes. This makes them promising candidates to stimulate the immune system of pigs via feed and making the animals more resistant to infections. That was found in a joint study of Wageningen University & Research and Utrecht University
Piglets run a high risk of infections during the first weeks of their life. Especially on farms, where piglets are separated from their mothers in their fourth week. This induces stress and therefore a weakened immune system. Scientists discovered that a well-known probiotic, E. coli Nissle, and the dietary fiber, β-glucan, boosts immune cells in pigs.
Production of new immune cells
“By exposing the immune cells to the dietary fiber β-glucan and the probiotic E. coli Nissle, we give the immune system a little poke,” says Mirelle Geervliet, first author of the paper and PhD candidate at the Cell Biology and Immunology chair group. That poke alerts the immune system. That way, it should react more quickly to actual pathogens. Geervliet and her colleagues published their results in the scientific journal Plos One.
The researchers studied immune cells that form the body's first line of defense, the so-called dendritic cells. “These cells and their response are only a small piece of a very complicated puzzle,” says Geervliet. “The immune system of pigs and humans is extremely complex and we are looking at the first link in that network”. Dendritic cells act as a kind of guard: when an unknown micro-organism or substance enters the body, they register it. They then project that intruder on their surface to warn other immune cells.
When the researchers added the β-glucan or the probiotic to the immune cells, something similar happened: the immune cells registered their presence. Whether they actually projected the "foreign" substances, the scientists have yet to determine. "The idea is that such projecting cells become more alert by a stimulus of β-glucan or the probiotic," explains Geervliet. Scientists hope that this will help the immune system to react more quickly to pathogens.
In the past, many studies were conducted on the health effects of the dietary fiber β-glucan, which is for example present in oats. Researchers found that β-glucan lowers cholesterol levels in the body.Because of the health claims, farmers add this fiber to the feed of pigs. Some studies indicate that pigs receiving β-glucan in their feed have less diarrhea. Other studies find minimal or no effects.
“I am convinced that β-glucans have an effect on the immune system,” says Geervliet. The problem with nutritional studies is that nutritional components only provide a small stimulus, especially in adult pigs with a fully developed immune system. The effect of nutrition is then diluted, which explains the variation between measurements and studies, Geervliet thinks.
Follow-up study in piglets
That is also the problem when it comes to stimulating the immune system through feed: it has only minimal influence. But Geervliet expects it to be different for young piglets. “Their immune system is still underdeveloped and we can therefore shape it fairly easily with nutritional components”. It is however important to start this as soon as possible after birth.
In a follow-up study, Geervliet and her colleagues will investigate whether the immune system of young piglets is indeed easier to tweak. During this study they will feed β-glucan and E. coli Nissle in solution to young piglets as supplementary feed. “Little research has yet been done into controlling immune systems in the early life stages of pigs,” says Geervliet. “We hope to gain more clarity about this with the follow-up study”.