Hypersensitivity of diabetic human platelets to platelet activating factor

Area of Science:

• Biochemistry
• Hematology
• Metabolic Disorders

Background:

• Platelet activating factor (PAF) is a potent mediator of platelet aggregation and inflammation.
• Diabetic patients exhibit altered platelet function, but the specific response to PAF is not fully understood.

Purpose of the Study:

• To compare PAF-stimulated platelet aggregation and phosphatidic acid (PA) production in normal and diabetic individuals.
• To investigate the role of the PAF receptor and its relation to glycemic control (HbA1c) in diabetic platelet function.

Main Methods:

• Platelet-rich plasma from normal and diabetic subjects was used to measure PAF-induced aggregation.
• Phosphatidic acid (PA) production, a marker of phospholipase C activity, was quantified using radioactive labeling ([32P]).
• PAF receptor antagonists (SRI-63441, SRI-63675) were used to assess receptor mediation.
• Correlation between PAF response and glycosylated hemoglobin (HbA1c) levels was analyzed.

Main Results:

• Diabetic platelets exhibited significantly lower EC50 for PAF-induced aggregation (8 nM) compared to normal platelets (50 nM), indicating hypersensitivity.
• PAF-stimulated [32P]-PA production was significantly greater in diabetic platelets.
• Both aggregation and PA production were inhibited by PAF receptor antagonists, confirming receptor mediation.
• A significant positive correlation was found between HbA1c levels and PAF-stimulated [32P]-PA production.

Conclusions:

• Diabetic human platelets demonstrate hypersensitivity to PAF regarding both aggregation and PA production.
• This PAF hypersensitivity is receptor-mediated and linked to altered phospholipid turnover.
• The correlation with HbA1c suggests that insulin deficiency and poor glycemic control contribute to these enhanced platelet responses in diabetes.