UK researchers unveil a new mechanism inside hair follicles that allows us to feel touch, according to a study published in Science Advances.
Until now, touch was thought to be detected only by nerve endings in the skin and around hair follicles. A study from Imperial College London has noticed that cells inside the follicles can also sense movement in cell cultures. These hair follicle cells can release histamine and serotonin neurotransmitters in response to touch. The authors believe this knowledge may help us understand histamine’s role in inflammatory skin diseases like eczema in the future.
“This is a surprising finding as we don’t yet know why hair follicle cells have this role in processing light touch. Since the follicle contains many sensory nerve endings, we now want to determine if the hair follicle is activating specific types of sensory nerves for an unknown but unique mechanism,” said the lead author of the paper, Dr Claire Higgins, from Imperial’s Department of Bioengineering.
We feel touch thanks to several mechanisms: sensory endings in the skin detect touch and send signals to the brain; hair follicles can also see movement of hair fibers, and sensory nerves found in the skinning process “feel good” touch.
To add to this list, UK researchers have uncovered a new mechanism. The team analyzed single-cell RNA sequencing data from human skin and hair follicles and found a higher percentage of touch-sensitive receptors in hair follicles than in skin. Using a technique known as fast-scan cyclic voltammetry to analyze cells in culture, the researchers found that the hair follicle cells were also capable of releasing the neurotransmitters serotonin and histamine in response to touch. Similar experiments with cells from the skin instead of the hair follicle showed that these cells can release histamine but not serotonin in response to touch.
“This is interesting as histamine in the skin contributes to inflammatory skin conditions such as eczema, and it has always been presumed that immune cells release all the histamine. Our work uncovers a new role for skin cells in releasing histamine, with potential applications for eczema research,” said Dr Higgins.
It’s important to note that research was performed in cell cultures and will need to be replicated in living organisms to confirm the findings, but these results are promising.
Agramunt J et al. (2023) Mechanical stimulation of human hair follicle outer root sheath cultures activates adjacent sensory neurons. Sci. Adv. 9, 3273, 10.1126/sciadv.adh3273