Schwann cells key to touch and pain

Schwann cells key to touch and pain

summary: Schwann cells, previously known for their role as insulators around nerve fibers, are actively involved in detecting sensory stimuli such as touch and pain. This pioneering study reveals that certain types of Schwann cells form a network just below the surface of the skin, connecting directly to nerve endings responsible for sensing mechanical stress.

Using optogenetics to manipulate these cells in mice, the team demonstrated the critical role of Schwann cells in transmitting pain sensations and their potential as a new target for pain treatment. This discovery not only challenges the current understanding of sensory perception, but also offers promising new directions for the treatment of pain and tactile dysfunction.

Key facts:

  1. Schwann cells play an essential role in detecting sensory stimuli, working alongside sensory neurons to transmit pain and touch sensations to the brain.
  2. The study used optogenetics to show that activating Schwann cells can stimulate pain sensations, and blocking them reduces stimulus transmission by at least half.
  3. This research highlights Schwann cells as a viable target for the development of new pain treatments, given their important role in detecting triggers and their accessibility for treatment.

source: Movement for Democratic Change

Special receptor cells located under the skin enable us to feel pain and touch. But Schwann cells also play a key role in detecting such stimuli, researchers at the Max Delbrück Center report in Nature Communications. This discovery opens new horizons for pain treatment.

The skin contains a large number of sensory receptor endings that detect touch, heat and cold, but it also contains potential dangers such as harmful mechanical and chemical stimuli. These sensory cells then send a corresponding signal to the spinal cord and brain. Scientists previously believed that sensory neurons alone were responsible for this task.

This indicates the hand.
Schwann cells are known to act as an insulating layer around nerve fibers. They protect and provide nutrients to neurons. Credit: Neuroscience News

However, Schwann cells have also been shown to play a vital role, as the groups of Professor Gary Lewin and Professor James Bullitt from the Max Delbrück Center, along with an international research team, have now reported in the journal. “Nature Communications.”

Schwann cells are known to act as an insulating layer around nerve fibers. They protect and provide nutrients to neurons. However, new research has shown that certain types of Schwann cells are also actively involved in detecting sensory stimuli. These Schwann cells form a grid-like structure just a few micrometers beneath the epidermis, and are linked to the free nerve endings of sensory receptors that detect mechanical pressure.

“We were surprised by the extent to which Schwann cells are involved in stimulus detection,” says Gary Lewin, head of the Laboratory for the Molecular Physiology of Somatosensation at the Max Delbrück Center.

The first indications of the importance of Schwann cells in pain perception (nociception) came from previous studies by Lewin’s Swedish collaborators. This prompted Julia Ojeda Alonso from the Lewin Lab and the Boule Lab to collaborate with international colleagues – such as Dr. Laura Calvo Enrique from the Karolinska Institutet in Stockholm – in order to get to the heart of the matter. Using a technique called optogenetics, the researchers bred mice in which they could turn different types of Schwann cells on and off with different colors of light.

Without Schwann cells, the mice were unable to sense vibrations

All it takes to transmit pain sensations to the brain is to activate Schwann cells with a light stimulus. It was not necessary to stimulate the actual pain receptors. When Schwann cells were blocked, the transmission of stimuli by nociceptors was reduced by at least half.

“We hypothesize that technical limitations prevent us from being able to fully map the role of Schwann cells, and that in some cases they actually perform most of the stimulus detection,” Lewin says.

The team then conducted experiments with tactile stimuli. They focused on Meissner corpuscles, vibration receptors in the skin that are closely linked to Schwann cells. The team, led by James Pollitt, who heads the Laboratory of Neural Circuits and Behavior at the Max Delbrück Center, trained mice to sense small vibrations with their front paws and report the detection of these stimuli.

“When the Schwann cells were turned off, it was very difficult for the mice to do this,” Boulet explains. After the optogenetic blockade was removed, their ability to sense small skin vibrations returned.

New methods of treating pain

The researchers showed that Schwann cells primarily affect the transmission of mechanical stimuli, but not heat or cold stimuli. “It is likely that multimodal nociceptors, which react to mechanical, thermal and chemical stimuli, function properly only with the help of Schwann cells,” Lewin says.

The findings open new horizons for understanding and treating pain and impaired tactile perception. “Schwann cells just below the surface of the skin are easily accessible to therapeutic agents,” Lewin says. “This makes them an attractive target to address the problem at its roots.”

About this pain research news

author: Jana Schlueter
source: Movement for Democratic Change
communication: Jana Schlüter – Movement for Democratic Change
picture: Image credited to Neuroscience News

Original search: Open access.
“Sensory Schwann cells set perceptual thresholds for touch and selectively regulate mechanical pain perception” by Gary Lewin et al. Nature Communications

a summary

Sensory Schwann cells set perceptual thresholds for touch and selectively regulate mechanical perception

Previous work has identified nociceptive Schwann cells that can cause pain. Consistent with the presence of mechanosensory Schwann cells in nature, we found that in mice, the mechanosensory function of almost all nociceptors, including those that signal rapid pain, was dependent on mechanosensory Schwann cells.

In multimodal nociceptors, sensory Schwann cells signal mechanical pain, but not cold or thermal pain. Terminal Schwann cells also surround mechanoreceptor nerve endings within the Meissner corpuscle and in the shaft endings of hair follicles that both signal vibratory touch.

Within Meissner corpuscles, two molecularly and functionally distinct sensory Schwann cells positive for Sox10 and Sox2 differentially modulate rapidly adapting mechanoreceptor function. Using optogenetics, we show that Meissner corpuscle Schwann cells are essential for the perception of low-threshold vibratory stimuli.

These results show that sensory Schwann cells within diverse neuroglial mechanosensory end organs are sensors of mechanical pain as well as essential for touch perception.

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