Researchers have discovered a new type of salivary gland cell that could unlock a whole new approach to treating damaged or diseased salivary and tear glands.
A team at the Scripps Research Institute and the National Institute of Dental and Craniofacial Research successfully identified a cell in the salivary glands of mice, and they have reason to believe the cell is also present in humans. The cell in question is a type of ionocyte, which are responsible for managing healthy ion levels in saliva and regulating electrolytes like potassium, calcium and iodine.
This particular ionocyte also secretes a protein called fibroblast growth factor 10. FGF10 is responsible for the early growth and development of salivary glands and potentially involved in maintaining and repairing the glands once they’re developed. The researchers were able to isolate this particular cell by analyzing single cell atlases of gene activity in mice and focused on those involved with FGF10. In the first week of a mouse’s life, the job is actually done by a different kind of cell, but once that role is replaced, the cell they found continues production into adulthood.
“The fact that this cell is the producer of FGF10 in adult salivary glands suggests that it could have a big role in gland maintenance and repair after injury,” said researcher and study co-author Vanessa Delcroix, Ph.D., in a press release.
Ionocytes are rare in human cell tissue and much more common in aquatic creatures, but the FGF10-producing epithelial cells the research team isolated had molecular markers showing that it was an ionocyte. These cells are also involved in the production of cystic fibrosis transmembrane conductance regulator protein, the absence of which causes cystic fibrosis, a finding that echoes research done in the past few years that linked cystic fibrosis to pulmonary ionocytes.
The research team has already found signs of a cell in a protein atlas of human tissue that matches the one they identified in mice and is planning to conduct further studies with human cells to build towards new treatment methods.
While damaged salivary glands seem fairly mild as a health problem, saliva actually plays a very important role in both the digestive and immune systems. It also protects oral health against tooth decay, gum disease and infection. Damaged salivary glands are often the byproduct of autoimmune disorders and radiation therapy, with some causes still unclear.
Beyond just salivary glands, the research team is hoping this discovery could also inform treatments of other similar glands, like tear glands, which maintain healthy eyes and clear vision. The study, publish in the journal Cell Reports April 12, was funded in part by the National Eye Institute. CFTR protein deficiency, the same protein involved in cystic fibrosis, has also been connected to a common condition called Sjögren’s syndrome that causes dry mouth and eyes, further suggesting research on this cell could translate to treatments for eye conditions.