Researchers at Imperial College London have identified a previously unknown way by which hair follicles contribute to the sense of touch, suggesting a role in conditions like eczema that involve skin inflammation.
The team from Imperial College London have elucidated a novel process within hair follicles that contributes to our tactile perception.
Until this research, the prevailing understanding was that the sensation of touch was primarily mediated through nerve endings located in the skin and near hair follicles. However, this latest study discloses that cells within the hair follicles—the structures that encapsulate individual hair strands—also have the ability to detect touch in cell cultures.
In addition, the scientists found that these particular cells within the hair follicles release neurotransmitters, specifically histamine and serotonin, in response to tactile stimuli. This discovery could pave the way for new insights into the role of histamine in skin conditions characterized by inflammation, such as eczema.
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The Unforeseen Function of Hair Follicles
Dr. Claire Higgins, the lead author from the Department of Bioengineering at Imperial College London, commented, “This revelation is unexpected, as the precise reason why hair follicle cells are implicated in light touch sensing is still not clear. Given that numerous sensory nerve endings are contained within the follicle, we now aim to ascertain whether the hair follicle activates particular types of sensory nerves through an as-yet unidentified unique mechanism.”
Complexities of Tactile Perception
Human tactile perception is facilitated through various mechanisms: sensory nerve endings in the skin detect touch and transmit signals to the brain; hair follicles rich in nerve supply detect hair fiber movement; and a type of sensory nerves known as C-LTMRs, exclusive to hairy skin, process emotionally rewarding or ‘feel-good’ touch.
In their study, the researchers utilized single-cell RNA sequencing data from human skin and hair follicles. They discovered that the cells in hair follicles contained a greater proportion of touch-sensitive receptors compared to their counterparts in the skin.
By establishing co-cultures of human hair follicle cells and sensory nerves, and then mechanically stimulating the hair follicle cells, they noted that this led to the activation of adjacent sensory nerves.
Neurotransmitter Release in Tactile Sensing
To investigate how the cells within hair follicles communicate with sensory nerves, the researchers adapted a method known as fast scan cyclic voltammetry. They found that these cells released serotonin and histamine when mechanically stimulated. Upon blocking the receptor for these neurotransmitters in the sensory neurons, the neurons ceased to respond to the stimulation by hair follicle cells. Similarly, when the synaptic vesicle production in hair follicle cells was inhibited, these cells lost their ability to signal to sensory nerves.
The team also conducted analogous experiments using skin cells rather than hair follicle cells. The skin cells released histamine in response to light touch but did not release serotonin.
Dr. Higgins stated, “This finding is noteworthy because histamine in the skin contributes to inflammatory conditions such as eczema. It was previously assumed that only immune cells released histamine. Our research identifies a new role for skin cells in histamine release, offering potential avenues for eczema research.”
Future Directions
The scientists point out that their findings are based on cell cultures and thus require validation through studies involving living organisms. They are also interested in investigating whether hair follicles activate specific types of sensory nerves, especially since C-LTMRs are only found in hairy skin.
Funding and Citation
This research was supported by the Engineering and Physical Research Council (EPSRC, a division of UKRI), Proctor & Gamble, the Wellcome Trust, and the Biotechnology and Biological Sciences Research Council (BBSRC, also a division of UKRI).
Reference: “Mechanical stimulation of human hair follicle outer root sheath cultures activates adjacent sensory neurons” by Julià Agramunt, Brenna Parke, Sergio Mena, Victor Ubels, Francisco Jimenez, Greg Williams, Anna DY Rhodes, Summik Limbu, Melissa Hexter, Leigh Knight, Parastoo Hashemi, Andriy S. Kozlov and Claire A. Higgins, published on 27 October 2023 in Science Advances. DOI: 10.1126/sciadv.adh3273
Frequently Asked Questions (FAQs) about Tactile Sensing Mechanism in Hair Follicles
What institution conducted the research on tactile sensing in hair follicles?
The research was conducted by a team of scientists at Imperial College London.
What is the new discovery related to the sense of touch?
The researchers have discovered a previously unknown mechanism within hair follicles that contributes to our sense of touch. Cells within these follicles can detect touch and release neurotransmitters like histamine and serotonin in response.
How might this research contribute to the understanding of skin conditions like eczema?
The study has uncovered that hair follicle cells release histamine and serotonin in response to tactile stimuli. This could offer new insights into the role of histamine in inflammatory skin conditions like eczema.
Who is the lead author of the research paper?
The lead author of the research paper is Dr. Claire Higgins, who is part of the Department of Bioengineering at Imperial College London.
What methodologies were employed in the study?
The researchers used single-cell RNA sequencing to analyze human skin and hair follicles. They also established co-cultures of human hair follicle cells and sensory nerves, and mechanically stimulated the hair follicle cells to observe the activation of adjacent sensory nerves.
What neurotransmitters were found to be released by hair follicle cells in response to touch?
The hair follicle cells were found to release the neurotransmitters serotonin and histamine when subjected to mechanical stimulation or touch.
Were experiments performed on living organisms?
No, the research was primarily conducted using cell cultures. The researchers note that future studies on living organisms are needed to validate their findings.
Is this research funded and if so, by whom?
Yes, this research received funding from the Engineering and Physical Research Council (EPSRC, part of UKRI), Proctor & Gamble, the Wellcome Trust, and the Biotechnology and Biological Sciences Research Council (BBSRC, also part of UKRI).
What are the future directions for this research?
The scientists intend to validate their findings through studies involving living organisms. They are also keen to explore whether hair follicles activate specific types of sensory nerves, especially since C-LTMRs are only found in hairy skin.
Where can the research paper be accessed?
The research paper is published in Science Advances and can be accessed through its DOI: 10.1126/sciadv.adh3273.
More about Tactile Sensing Mechanism in Hair Follicles
- Imperial College London Official Website
- Science Advances Journal
- Engineering and Physical Research Council (EPSRC)
- Wellcome Trust
- Biotechnology and Biological Sciences Research Council (BBSRC)
- Department of Bioengineering at Imperial College London
- PubMed: Role of Histamine in Inflammatory Skin Conditions
- Eczema and Skin Conditions: Research Overview
- Understanding Tactile Sensing
- Mechanoreceptors and Tactile Sensation
6 comments
What an intricate study. Could be a game changer for sensory neuroscience. It’s about time we understood more about touch and how our skin reacts!
Amazing how much we still don’t know about our own bodies! Also, props to Imperial College London for the thorough research. Looking forward to see how this plays out in practical applications.
Always thought it was jst the skin that did all the touch sensing. gotta say, this is intriguing. Makes you think, huh?
i’m curious how this could be used for skin conditions. if histamine is also involved in eczema, could this research actually make a difference?
So the funding comes from a variety of sources, including big names like Proctor & Gamble and Wellcome Trust. Means the study must be pretty legit, I guess.
Wow, never thought hair follicles had that much to do with touch. This is groundbreaking stuff. Seriously, what’s next?