Autophagy in the posterior interosseous nerve of patients with type 1 and type 2 diabetes mellitus: an ultrastructural study

• Published in: Diabetologia Vol. 58; no. 3; pp. 625 - 632
• Main Authors: Osman, Ayman A. M., Dahlin, Lars B., Thomsen, Niels O. B., Mohseni, Simin
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-03-2015; Springer Nature B.V
• Subjects: Adult; Aged; Autophagy; Autophagy - physiology; Carpal tunnel syndrome; Clinical Medicine; Diabetes; Diabetes Mellitus, Type 1 - metabolism; Diabetes Mellitus, Type 1 - pathology; Diabetes Mellitus, Type 2 - metabolism; Diabetes Mellitus, Type 2 - pathology; Electron microscopes; Electron microscopy; Endocrinology and Diabetes; Endokrinologi och diabetes; Female; Hand surgery; Human; Human Physiology; Humans; In Vitro Techniques; Insulin; Internal Medicine; Klinisk medicin; Male; Medical and Health Sciences; Medicin och hälsovetenskap; Medicine; Medicine & Public Health; Metabolic Diseases; Microscopy; Middle Aged; nerve; Nervous system; Neuropathy; Peripheral; Peripheral Nerves - metabolism; Peripheral Nerves - pathology; Peripheral Nerves - ultrastructure; Peripheral neuropathy; United States > US; Sweden; Human; Peripheral nerve; Diabetes; Neuropathy; Electron microscopy; Autophagy
• ISSN: 0012-186X; 1432-0428; 1432-0428
• DOI: 10.1007/s00125-014-3477-4

Aims/hypothesis
We addressed the question of whether the autophagy pathway occurs in human peripheral nerves and whether this pathway is associated with peripheral neuropathy in diabetes mellitus.
Methods
By using electron microscopy, we evaluated the presence of autophagy-related structures and neuropathy in the posterior interosseous nerve of patients who had undergone carpal tunnel release and had type 1 or type 2 diabetes mellitus, and in patients with no diabetes (controls).
Results
Autophagy-related ultrastructures were observed in the samples taken from all patients of the three groups. The number of autophagy-associated structures was significantly higher (
p
 < 0.05) in the nerves of patients with type 1 than type 2 diabetes. Qualitative and quantitative evaluations of fascicle area, diameter of myelinated and unmyelinated nerve fibres, the density of myelinated and unmyelinated fibres and the g-ratio of myelinated fibres were performed. We found degeneration and regeneration of a few myelinated axons in controls, and a well-developed neuropathy with the loss of large myelinated axons and the presence of many small ones in patients with diabetes. The pathology in type 1 diabetes was more extensive than in type 2 diabetes.
Conclusions/interpretation
The results of this study show that the human peripheral nerves have access to the autophagy machinery, and this pathway may be regulated differently in type 1 and type 2 diabetes; insulin, presence of extensive neuropathy, and/or other factors such as duration of diabetes and HbA
1c
level may underlie this differential regulation.