The Anatomy of Anaphylaxis: How a Severe Allergic Reaction Can Trigger a Medical Emergency And A Potential Cure Just Revealed By A New Study.

A study by Duke Health researchers has found that the nervous system plays a crucial role in anaphylactic shock, which can cause a sudden drop in blood pressure and body temperature.

This discovery could lead to new targets for therapies to prevent or treat anaphylactic shock caused by food allergies or bites from insects or venomous animals. Learn more about the findings in this article.

The severe allergic reaction called anaphylaxis is characterized by a sudden decrease in blood pressure and body temperature, which can lead to fainting and, if not treated promptly, even death.

For a long time, the severe allergic reaction known as anaphylaxis was thought to be caused by a sudden dilation and leakage of blood vessels.

However, a recent study conducted on mice by Duke Health researchers has revealed that the nervous system plays an additional role, particularly in causing a drop in body temperature.

The study, which was published in the journal Science Immunology today, could potentially identify new targets for therapies to prevent or treat anaphylactic shock. This severe reaction affects up to 5% of individuals in the United States every year, often triggered by food allergies or bites from insects or venomous animals.

According to Soman Abraham, Ph.D., a professor in the departments of Pathology, Immunology, and Molecular Genetics and Microbiology at Duke University School of Medicine, “this finding for the first time identifies the nervous system as a key player in the anaphylactic response.”

The sensory nerves that are responsible for thermal regulation, particularly those that detect high environmental temperatures, send misleading signals to the brain during anaphylaxis, creating the impression that the body is exposed to high temperatures even when it is not. This results in a sudden decrease in both body temperature and blood pressure.

In their study, Abraham and colleagues, including first author Chunjing “Evangeline” Bao, a Ph.D. candidate in Abraham’s lab at Duke University, investigated the sequence of events triggered by allergens that activate mast cells, the immune cells that initiate the chemical reactions that lead to swelling, difficulty breathing, itchiness, low blood pressure, and hypothermia.

The researchers discovered that one of the chemicals released by mast cells when they are activated is an enzyme that interacts with sensory neurons, particularly those involved in the body’s neural network for regulating temperature.

During an allergic reaction, this neural network receives a signal to immediately halt the production of heat in the body’s brown fat tissue, resulting in hypothermia. The activation of this network also leads to a sudden drop in blood pressure.

To validate their results, the researchers deprived mice of the specific mast cell enzyme, which protected them against hypothermia. Conversely, directly activating the heat sensing neurons in mice caused anaphylactic reactions, such as hypothermia and hypotension.

“By demonstrating that the nervous system is a key player – not just the immune cells – we now have potential targets for prevention or therapy,” Bao adds. “This finding could also be important for other conditions, including septic shock, and we are undertaking those studies.”

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