Common food additive can weaken defenses against flu

Research in mice suggests that tert-butylhydroquinone (tBHQ), a food additive found in many common products, from frozen meat to crackers and fried foods, suppresses the immune response that body focuses when it fights the flu. In addition to increasing the severity of flu symptoms, the study found that tBHQ exposure could reduce the effectiveness of influenza vaccine through its effects on T cells, a vital component of the immune system.

Researchers say this link could help explain why seasonal flu continues to pose a major health threat to the world. Approximately 290,000 to 650,000 people worldwide die each year from respiratory problems related to influenza.

"Our studies showed that the immune response to influenza infection was weakened in tBHQ-treated mice," said Robert Freeborn, who holds a fourth-year doctorate. candidate at Michigan State University. "In our mouse model, tBHQ suppressed the function of two types of T cells, helper T cells and killer T cells." In the end, this resulted in more severe symptoms during an influenza infection higher. "

Freeborn will present the research at the annual meeting of the American Society for Pharmacology and Experimental Therapeutics at the 2019 Experimental Biology Meeting, held April 6-9 in Orlando, Florida.

When a person is infected with the flu virus, helper T cells direct other parts of the immune system and help coordinate an appropriate response, while killer T cells track infected cells and eliminate them. from the body. In their experiments, the researchers found that mice with a tBHQ-enriched diet activated both T helper cells and killer T cells at a slower rate, slowing the clearance of the virus.

"At the present time, my main hypothesis is that tBHQ causes these effects by upregulating certain proteins that are known to suppress the immune system," said Freeborn. "The expression of these proteins, CTLA-4 and IL-10, has been upregulated in two different models that we use in the laboratory.However, further work is needed to determine if the upregulation of these suppressor proteins is actually responsible for the effects of tBHQ during influenza infection. "

In addition, when the mice were re-infected with a different but related strain of influenza, those in the tBHQ diet experienced a longer illness and lost more weight. This suggests that tBHQ has altered the "memory response" that usually causes the immune system to fight a second infection, said Freeborn. Since the memory response is essential for the functioning of vaccines, a deficiency of this function could potentially reduce the effectiveness of the influenza vaccine.

Because T cells are involved in the immune response to various diseases, tBHQ may also play a role in other types of infectious diseases, said Freeborn.

TBHQ is an additive used to prevent spoilage, with a maximum allowable concentration of 200 parts per million in food products. It is not known how many people are exposed to tBHQ, although estimates based on diet models suggest that some US consumers consume nearly double the maximum allowed amount of tBHQ suggested by the Joint FAO / WHO Expert Committee. on food additives and that the inhabitants of other regions of the world. the world can consume up to 11 times the maximum allowed amount. The level of exposure to tBHQ in Freeborn's studies lies in the estimates of human exposure.

"It can be hard to know if you're consuming tBHQ, because that's not always indicated on ingredient labels," Freeborn said, adding that it was often the case when tBHQ is used in food preparation, as in the oil used to fry a flea. "The best way to limit exposure to tBHQ is to consider food choices." Since tBHQ is widely used to stabilize fat, a low-fat diet and reduced number of processed snacks will help reduce its consumption. "

Freeborn pointed out that the annual flu vaccine remains the best way to prevent influenza infection. Although it is possible to contract the flu after receiving the vaccine, it has been proven that vaccination significantly reduces the duration and severity of the disease.

Based on their studies conducted in mice, the researchers plan to use human blood samples to further study the incidence of tBHQ on T cell activity.

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Experimental Biology