Serum from patients with type 2 diabetes with neuropathy induces complement-independent, calcium-dependent apoptosis in cultured neuronal cells.
We hypothesized that sera from type 2 diabetic patients with neuropathy contains an autoimmune immunoglobulin that promotes complement-independent, calcium-dependent apoptosis in neuronal cell lines. Neuronal cells were cultured in the presence of complement-inactivated sera obtained from patients with type 2 diabetes with and without neuropathy and healthy adult control patients. Serum from diabetic patients with neuropathy was associated with a significantly greater induction of apoptosis, compared to serum from diabetic patients without neuropathy and controls. In the presence of calcium channel antagonists, induction of apoptosis was reduced by approximately 50%. Pretreatment of neuronal cells with serum from diabetic patients with neuropathy was associated with a significant increase in elevated K+-evoked cytosolic calcium concentration. Serum-induced enhancement in cytosolic calcium and calcium current density was blocked by treatment with trypsin and filtration of the serum using a 100,000-kd molecular weight filter. Treatment with an anti-human IgG antibody was associated with intense fluorescence on the surface of neuronal cells exposed to sera from patients with type 2 diabetes mellitus with neuropathy. We conclude that sera from type 2 diabetic patients with neuropathy contains an autoimmune immunoglobulin that induces complement-independent, calcium-dependent apoptosis in neuronal cells.
Srinivasan
S
S
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical Center and the Ann Arbor Veterans Affairs Medical Center, Ann Arbor, Michigan 48105, USA.
Stevens
M J
MJ
Sheng
H
H
Hall
K E
KE
Wiley
J W
JW
D000328:Adult; D000368:Aged; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000502:physiology; D003470:Culture Media; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology; D003929:Diabetic Neuropathies / Q000097:blood* / Q000503:physiopathology; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology; D006339:Heart Rate; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D008875:Middle Aged; D009414:Nerve Growth Factors / Q000494:pharmacology; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D014407:Tumor Cells, Cultured
D002121:Calcium Channel Blockers; D003470:Culture Media; D009414:Nerve Growth Factors; D003165:Complement System Proteins; D002118:Calcium