Scientists Discover The Hidden Neurons That Trigger Eczema Itching

For years, scientists have tried to understand why a simple touch on the skin can trigger an almost impossible-to-ignore itch. Now, new research has identified specific neurons responsible for this process, a discovery that could pave the way for revolutionary treatments against eczema and other diseases that cause chronic itching.

Itching is one of the most bothersome symptoms of various skin diseases, especially eczema. For many people, the sensation goes far beyond simple discomfort: it can interfere with sleep, concentration, mental health, and quality of life.

Although scientists already know a great deal about the chemical mechanisms involved in itching, many questions remain about how simple physical stimuli, such as a light touch on the skin or contact with clothing, can trigger an intense urge to scratch. Now, new research may have taken an important step toward answering this question.

The researchers started with a curious observation. Not all skin hairs are the same. In mice, there are some rare types of extremely fine and little-studied hairs, located mainly behind the ears and on the hind paws. Scientists suspected that these hairs might play a specific sensory role, acting as tiny antennae capable of detecting very subtle mechanical stimuli from the environment.

To investigate this hypothesis, the team used a combination of advanced neuroscience techniques. First, they meticulously mapped which neurons were connected to these special hairs. They discovered that a very specific group of nerve cells surrounded the base of these hairs, forming specialized structures to detect minute movements and deformations.

Next, the researchers used genetic tools to precisely identify these cells and track their activity in real time.

The next step was to discover if these neurons actually participated in the sensation of itching. To do this, the scientists selectively deactivated these nerve cells in some animals, while in others they remained functioning normally. Then, they applied extremely light stimuli to the skin, similar to the contacts that occur naturally in everyday life.

The result was surprising: the animals that had these neurons deactivated practically ceased to exhibit itching behaviors triggered by touch. This indicated that these cells play a fundamental role in the transmission of this specific type of sensation.

The researchers also performed the reverse experiment. Instead of blocking the neurons, they artificially activated them using light, a technique known as optogenetics. Even without a real physical stimulus on the skin, the activation of these cells was sufficient to trigger typical itching behaviors.

This result provided very strong evidence that these neurons not only participate in the process, but may be able to initiate the itch signal on their own.

Finally, the team investigated how these cells detect mechanical stimuli. They discovered that a protein present in the neuron membrane functions as a kind of molecular sensor capable of transforming pressure, touch, or movement into electrical signals sent to the brain. 

When this protein was genetically removed, the ability to transmit the sensation of mechanical itching was drastically reduced. The results reveal a previously unknown neural circuit responsible for transforming mild physical stimuli into itching sensations.

The discovery opens new possibilities for the development of more effective treatments for diseases such as eczema and chronic dermatitis, offering hope to millions of people who live daily with persistent and difficult-to-control itching.

READ MORE:

A Specialized Population of Hair Afferents Dedicated to Transmitting Mechanical Itch

Mahar Fatima, Hankyu Lee, Hwayeon Cha, Chia Chun Hor, Feng Wang, Jingyi Liu, Jonathan Damblon, Wenwen Zhang, Katie Qu, Yumena Nagai, Abbey Dinh, Ziyan Wu, Ranveer Ajimal, Ailin Emily Xiong, Madeleine Chai, Alyssa Asmar, Wei Cai, Xiaowei Zhou, Anuraag Balaji, Haili Pan, Lorraine Horwitz, Lam C. Tsoi, Hongzhen Hu, X. Z. Shawn Xu, Yves De Koninck, and Bo Duan. 

Neuron. June 4, 2026

DOI:10.1016/j.neuron.2026.05.017

Abstract: 

Hairs serve as sensory structures that are crucial for perceiving environmental cues through interactions with sensory endings. Depigmented and demedullated atypical hairs exhibit a limited distribution on mammalian skin and have not been extensively studied. In this study, we identify a specific type of hair, termed vellus-like hairs (VLHs), which are enriched in the postauricular region and on the hindpaws of mice. These hairs are innervated by Aβ low-threshold mechanoreceptors (LTMRs) that co-express Toll-like receptor 5 and Calbindin1 (TLR5Calb1). Genetic ablation or silencing of these hair afferents eliminated mechanical itch generated by gentle VLH stroking or indentation under both physiological and pathological conditions. Conversely, optogenetic activation of TLR5Calb1 hair afferents evoked itch behaviors. Mechanosensitive Piezo2 channels in TLR5Calb1 Aβ-LTMRs function as key mechanotransducers for mechanical itch signaling. Our study sheds light on the previously poorly understood somatosensory physiology of unique hairs, emphasizing the significant role of TLR5Calb1 Aβ-LTMRs in itch transmission.