A sharp drop in blood pressure and body temperature is a key feature of the severe allergic reaction known as anaphylaxis, causing fainting and, if untreated, potentially death. This response has long been attributed to the dilation and leakage of blood vessels. However, Duke Health researchers found in a mouse study that this response, specifically the drop in body temperature, requires an additional mechanism: the nervous system.
Findings published in the journal Science Immunology, the study could point to new targets for therapies aimed at preventing or treating anaphylactic shock, which occurs each year in up to 5% of people in the United States in response to food allergies or bites from poisonous insects or animals. . “This discovery identifies for the first time the nervous system as a key player in the anaphylactic response,” said lead author Soman Abraham, Ph.D., a professor in the departments of pathology, immunology, molecular genetics and microbiology at Duke University School. of Medicine.
“Sensory nerves involved in thermal regulation – specifically nerves that detect high environmental temperatures – send the brain a false signal during anaphylaxis that the body is exposed to high temperatures even though it is not.” , Abraham said. “This causes a rapid drop in body temperature as well as blood pressure.” Abraham and his colleagues, including first author Chunjing “Evangeline” Bao, who holds a Ph.D. candidate in Abraham’s lab at Duke, followed the sequence of events when allergens activate mast cells – the immune cells that trigger the chemical reactions leading to swelling, difficulty breathing, itching, low blood pressure and hypothermia .
Researchers have found that one of the chemicals that mast cells release when activated is an enzyme that interacts with sensory neurons, including those involved in the body’s thermoregulatory neural network. When stimulated as part of an allergic reaction, this neural network receives the signal to immediately shut down the body’s heat generators in brown adipose tissue, causing hypothermia. Activation of this network also causes a sharp drop in blood pressure.
The researchers validated their findings by showing that depriving mice of the mast cell-specific enzyme protected them against hypothermia, while direct activation of heat-sensitive neurons in mice induced anaphylactic reactions such as hypothermia. and hypotension. “By demonstrating that the nervous system is a key player – not just immune cells – we now have potential targets for prevention or therapy,” Bao said. “This finding could also be important for other conditions, including septic shock, and we are undertaking these studies.” (ANI)
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