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Activated immune cells can be sent through specific food components to a specific location in the body, such as the upper respiratory tract or the skin. All About Feed covers current research that extends these findings and proves the hypothesis that immune cells can be directed towards certain organs or body parts.

The research project ‘Nutrition-based gastro-intestinal health promotion in agricultural animal husbandry’ began in 2014. It was headed by Huub Savelkoul, professor and head of the Cell Biology and Immunology group of the department of Animal ­Sciences of Wageningen University.

More to feed than just nutrition

Last year Prof Savelkoul and colleagues published findings in the prestigious global scientific journal Mucosal Immunology. “Our study is based on extensive studies of food allergies in humans that evolved into a research programme called ‘Immune modulation through diet’,” said Prof Savelkoul.

“Immunomodulation by food and feed provides the industry with a new concept. So, since then we have been actively communicating to the food industry and compound feed industry that there could be more to their feed than just nutrition. The relationship between gut, nutrition and resilience to infection, and therefore general health, is of relevance for humans and animals alike.

“Maintenance of health and prevention of infectious disease in the respiratory and the gastro-intestinal tracts are critically dependent on proper functioning of the immune system in relation to intestinal homeostasis.

“Therefore, when this homeostasis is compromised by the presence of infectious organisms, toxic compounds, bacterial dysbiosis, stress-related conditions, and exposure to particular dietary components, the health status of the individual is at risk. Often this condition will not directly result in overt clinical disease. However, it will result in the development of a chronic low-grade, subclinical inflammation, which can result in chronic diseases,” said Prof Savelkoul.

Directing immune cells

During a meeting with the Dutch compound feed company MulderAgro from Kollumerzwaag, the model of natural disease resistance and immune modulation by feed was presented for the first time. “What we communicated was mainly based on literature studies and some of our own research,” explained Prof Savelkoul.

After the publication of two dissertations in 2018 by Dr Marloes van Splunter and Dr Olaf Perdijk, it became clear that in (raw) milk for example the immunity can be held by this immunomodulation. “We found out how to positively change the immunity-promoting activity in milk with a particular treatment,” said Prof Savelkoul. The research proposal for immune modulation was approved and Prof Savelkoul could launch his research activities.

He is currently investigating immunomodulation in poultry and pigs and performs specific research into diet-induced alterations in intestinal bacteria. The results of this research will be presented to the sector through scientific publications. It will also be presented in courses provided by Wageningen Academy called ‘Gut health in pigs and poultry’.

During Gut Health 2019 held earlier this year, Prof Savelkoul spoke about the remarkable results. “We have discovered that we can send immune cells, activated by interaction with infections or vaccines, through specific food components to a particular place in the body, such as into the airways or to the skin.

“We can programme some nutritional components with proven immunomodulatory activity, such as vitamin A and certain fatty acids, to stay in the intestines. With a precise dosage of vitamin D3 we can send them to the skin or, with just a slightly different vitamin A to D ratio, to the upper airways.”

Clearly measurable

But that’s not all, the researchers were also able to ensure that the activated immune cells stayed in the intestine to fight infection. That occurred by administering a particular vitamin A in a very precise dose. “So, now we know exactly how we can send the activated immune cells to a specific part of the body and measure it,” explained Prof Savelkoul.

According to him, the immune system of humans and animals can be much more efficient. This means it can respond faster and more effectively by providing precise doses of selected nutritional compounds that possess immunomodulatory activity.

When the activated immune cells cannot reach the right spot in time, valuable energy is wasted. This is especially true for adequate protection against upper respiratory infections in young animals. “This new knowledge is therefore crucial,” said Prof Savelkoul.

Another discovery that he has great expectations for is the positive effect of probiotics on immune competence by poultry and pigs. As the research on underlying immune mechanisms is still ongoing, it will take some time before the fruit can be harvested in practice. However, given its influence on the immune system the interest in this probiotic will be greatly intensified.

Genetic imprinting

According to Prof Savelkoul, the influence of the immune system by immune modulation is based on another important concept, namely genetic imprinting. “Transgenerational changes in the genetics of the animal run through epigenetic changes rather than through mutation in coding sequences in the DNA.

“A big advantage of this genetic imprinting is that we can temporarily change the transcriptional rate of coding genes, resulting in a more optimised immune competence. Because of our discoveries we can precisely adjust the husbandry conditions, such as infection pressure, breeding and feeding. This will lead to animals that are more resilient or robust during every generation.” – Dick van Doorn, All About Feed