Scientists talked about the effect of nutrition on immune memory

Even short-term dietary changes can affect the functioning of the immune system. The scientists found that several days of a high-fat diet increased the inflammatory response in mice, and the effect persisted even after returning to a regular diet. Upon repeated contact with the irritant, the tissues reacted even more strongly. About why short—term dietary changes can leave a mark on the immune system, see the Izvestia article.

Four days have changed the reaction

The study is published in the journal Nature. Scientists from the University of California, San Francisco, studied how a high-fat diet affects inflammation regardless of body weight. For the experiment, mice were given an ear cream that causes an inflammatory skin reaction.

First, the researchers compared animals that had been receiving regular low-fat food and a high-fat diet for a long time. The inflammation was more pronounced in obese mice. However, then scientists found out that it was not necessary to gain extra weight to enhance the reaction: even a short-term change in diet led to a similar result.

When normal-weight mice were given high-fat food for four days during the period of inflammation, their response to the stimulus became significantly stronger. In contrast, in obese animals that were switched to a regular diet four days before exposure, inflammation was noticeably weaker.

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The immune system has preserved its memory

The most unexpected result was what happened after the experiment was completed. When the inflammation passed, the mice returned to a low-fat diet. However, a few weeks later, the researchers reapplied the irritating cream on the same ear. The reaction turned out to be much stronger than at the first exposure.

Scientists found that a high—fat diet promoted the influx of neutrophils into the skin, immune cells involved in a rapid inflammatory response. After the acute inflammation subsided, memory T cells remained in the tissues. They retained information about the previous inflammatory process and could enhance the response upon repeated contact with the stimulus.

Thus, a short-term change in nutrition during the onset of inflammation was able to influence the subsequent tissue response. In this case, we are not talking about the constant strengthening of immunity, but about the formation of local immune memory, which in this experiment led to more pronounced inflammation.

A similar effect was found in the lungs

The researchers tested whether the discovered mechanism is limited to the skin. In a separate experiment, they studied the inflammatory response in the lungs of mice after short-term consumption of high-fat feed. There was also an increase in inflammation associated with the work of neutrophils and certain T cells.

The authors suggest that nutrition can influence immune responses in different tissues, especially if a change in diet coincides with the onset of the inflammatory process. However, after returning to a normal diet, scientists have studied stable immune memory in detail using a model of skin inflammation. Therefore, the results of the lung experiment cannot be considered evidence of a similar long-term effect.

According to Bapat, breakfast, lunch, and dinner can have a huge and rapid effect on the immune system. The researcher emphasized that the work shows how quickly the body is able to respond to dietary changes.

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What does this mean for people?

Scientists emphasize that the results cannot yet be directly transferred to humans. Experiments were conducted on mice, and a special cream was used to provoke inflammation. In addition, the laboratory diet with a high fat content does not fully correspond to the usual diet of people.

The authors believe that further study of the relationship between nutrition and immune memory will help to better understand why inflammatory diseases occur differently in different people and what factors can influence their recurrence. However, so far the work does not give grounds to assert that a few days of eating fatty foods will cause similar consequences in humans.