Researchers have identified a new sensory structure within the skin involved in the pain response to hazardous environmental stimulation. The structure, described in a paper published in Science (Aug. 16, 2019; 365(6454):695–699), is comprised of glia cells with multiple long protrusions and which collectively form a mesh-like structure in the subepidermal border within the skin. This structure is sensitive to painful mechanical damage such as pricks and pressure.
These illustrations depict the newly identified structure from the side and from above. Illustrator: Mattias Karlén. Reprinted with permission from Abdo et al, Science, Vol. 365, Issue 6454, pp. 695-699 (2019).
In the paper, the authors explain how they demonstrate a direct excitatory functional connection from the structure to sensory neurons. In particular, the glial cells are intimately associated with unmyelinated nociceptive nerves, are inherently mechanosensitive and transmit nociceptive information to the nerve. Blocking the structure experimentally resulted in a decreased ability to feel mechanical pain. “Our study shows that sensitivity to pain does not occur only in the skin’s nerve fibres, but also in this recently-discovered pain-sensitive organ,” said lead author Patrik Ernfors, PhD, in a press release. “The discovery changes our understanding of the cellular mechanisms of physical sensation and it may be of significance in the understanding of chronic pain.” Dr. Ernfors is a professor at Karolinska Institutet’s department of medical biochemistry and biophysics in Solna, Sweden.