Diabetes mellitus is a well-known cause of gastrointestinal dysmotility. The pathogenesis of diabetic gastroenteropathy is mainly considered to be a neuropathy, but the cause of dysmotility remains unknown. Interstitial cells of Cajal (ICC), which express c-kit receptor tyrosine kinase (KIT), are considered to be pacemaker cells for the gastrointestinal movement. Therefore, we investigated a possible involvement of ICC in the pathogenesis of diabetic gastroenteropathy in humans.
The KIT-positive cells in the proper muscle layer of the colon were detected by immunohistochemistry in patients with diabetes mellitus and normal control subjects. Mast cells, which are also known to express KIT, were detected by staining with Alcian blue. The numbers of KIT-positive cells and Alcian blue-positive cells in the proper muscle layer were counted under the microscope and the number of KIT-positive cells apart from Alcian blue-positive cells was calculated.
In the normal control subjects, KIT-positive cells were located at the myenteric plexus region and in the circular muscle layer of the colon. Their distribution pattern was similar to that of ICC. The average number of KIT-positive cells, apart from mast cells (which reflects the number of ICC), in patients with diabetes mellitus was approximately 40% of that found in normal subjects.
Deficiency of ICC might be related to the pathogenesis of diabetic gastroenteropathy in humans.