Nervous system might play a key role in severe allergic shock

A key feature of the severe allergic reaction known as anaphylaxis is an abrupt drop in blood pressure and body temperature, causing people to faint and, if untreated, potentially die.

That response has long been attributed to a sudden dilation and leakage of blood vessels. But in a study using mice, Duke Health researchers have found that this response, especially body temperature drop, requires an additional mechanism - the nervous system.

Appearing in the journal Science Immunology, the study could point to new targets for therapies to prevent or treat anaphylactic shock, which occurs in up to 5% of people in the U.S. annually in response to food allergies or bites from insects or venomous animals.

The researchers found that one of the chemicals mast cells unleash when they are activated is an enzyme that interacts with sensory neurons, notably those involved in the body’s thermoregulatory neural network.

When stimulated as part of an allergic reaction, this neural network gets the signal to immediately shut down the body’s heat generators in the brown fat tissue, causing hypothermia. The activation of this network also causes a sudden drop in blood pressure.

The researchers validated their findings by showing that depriving mice of the specific mast cell enzyme protected them against hypothermia, whereas directly activating the heat sensing neurons in mice induced anaphylactic reactions such as hypothermia and hypotension.

Reference:

Key role identified for nervous system in severe allergic shock; Science Immunology.