Substance P, a peptide released by our sensory neurons, is thought to be the cause of the chain reaction that causes the itching in allergies. By managing to block the process at the level of the sensory neurons, the allergic reaction does not occur, which represents great hope for future treatments.
-1604073361.jpg "We finally know why allergies cause itching")
- Allergy-related itching is caused by a neuropeptide, substance P.
- When confronted with an allergen, sensory neurons release substance P, which creates a chain reaction that causes the itch.
- By blocking the sensory neurons, the itching does not occur. This gives hope for future treatments.
Why do pollen, dust mites or animal hair cause itching in some people? Because our skin defends itself against what it considers an enemy. Researchers from Massachusetts General Hospital (USA) have understood why allergies make us itchy. When it detects allergens, our skin releases a neuropeptide, called substance P. This amino acid, essential in the development of the immune response to counter the allergen, is thought to be the cause of the itching sensation. The results of this study were published on October 23, 2020 in the journal Immunity.
A skin defense system
Until now, the scientific community could not explain why only certain allergens are detected by our immune system. The most likely explanation would be that dendritic cells, those responsible for the adaptive immune response, play a major role both in allergies and in protection against pathogens.
An explanation supported by the team of Caroline Sokol, lead author of the study and researcher at the Center for Immunology and Inflammatory Diseases at Massachusetts General Hospital. “We now know that sensory nerves link allergen exposure to immune activation. Dendritic cells that trigger allergy are located next to allergen-sensitive neurons in the skin. We discovered that when exposed to an allergen, these neurons release substance P.” This substance P induces the migration of dendritic cells to the lymph nodes, where they in turn activate the T lymphocytes, which will then go to the allergen.
Interrupt the allergic process
In their experience, carried out in vitro but also on mice, the team showed that sensory neurons detect allergens. By blocking these sensory neurons, it is possible to interrupt the activation of the allergic response.
This discovery will not only broaden the understanding of how the immune system works, but also lead to the development of new methods of treating and preventing allergies. “This neuron-dependent sensory pathway, and substance P, are needed to trigger an immune response to allergensassures Caroline Sokol. If we can interrupt it, we can eventually shut down the allergic immune response.”
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