The most common marker of a severe allergic reaction is anaphylaxis, which strikes within minutes of exposure to allergens and is potentially life-threatening. At its onset, the body’s blood pressure levels suddenly drop, causing one to have difficulty breathing and faint.
For years, doctors have linked anaphylaxis with a sudden dilation and leakage of blood vessels, but a recent study showed the nervous system also plays a key role in this condition. The findings of the study on mice were published Friday in the journal Science Immunology.
As per an earlier study published in the Journal of Allergy and Clinical Immunology (JACI), anaphylaxis is common in the U.S., affecting almost one in 50 Americans, who come down with the said symptoms in response to food allergies, some medications, insect or animal venom.
Scientists believe the latest research will open up new possibilities to prevent or cure anaphylactic shock, which can potentially be life-threatening if not addressed on time.
“This finding for the first time identifies the nervous system as a key player in the anaphylactic response,” the study author Soman Abraham, Ph.D., professor in the departments of Pathology, Immunology, and Molecular Genetics and Microbiology at Duke University School of Medicine said in the media release. “The sensory nerves involved in thermal regulation–especially the nerves that sense high environmental temperatures–send the brain a false signal during anaphylaxis that the body is exposed to high temperatures even though it is not the case. This causes a rapid drop in body temperature as well as blood pressure.”
The allergens make the first contact with the body’s immune cells, which then causes chemical reactions, leading to swelling, difficulty breathing, itchiness, low blood pressure, and hypothermia.
During one of the chemical reactions, the immune cells release an enzyme, which interacts with sensory neurons, predominantly those involved in the body’s thermoregulatory neural network, Medical Express reported, citing the study. When the allergic reaction stimulates the neural network, it immediately shuts down the body’s heat generators, leading to hypothermia. The abrupt drop in blood pressure is also linked to the activation of the network.
Experts found that restricting the flow of the immune cell enzymes in the mice’s bodies prevented the prospect of hypothermia. On the contrary, directly activating the heat-sensing neurons in mice induced anaphylactic reactions that led to 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,” the study co-author, Chunjing “Evangeline” Bao, a Ph.D. candidate in Abraham’s lab at Duke, said. “This finding could also be important for other conditions, including septic shock, and we are undertaking those studies.”