Glucose-induced loss of glycosyl-phosphatidylinositol-anchored membrane regulators of complement activation (CD59, CD55) by in vitro cultured human umbilical vein endothelial cells

Abstract

Several lines of evidence suggest that one of the primary events in the course of diabetic vascular pathology is an alteration affecting the endothelial cell function, including abnormalities of vessel tone and permeability, coagulation, blood flow, basement membrane synthesis and turnover and the appearance of specific adhesive glycoproteins promoting the binding and migration of mononuclear cells [1,2]. Hyperglycaemia and immunological factors could trigger the development of these abnormalities [3,4].Many findings show that activation of a complement system occurs in diabetic patients. Complement Diabetologia (2000) 43: 1039±1047Glucose-induced loss of glycosyl-phosphatidylinositol-anchored membrane regulators of complement activation (CD59, CD55) by in vitro cultured human umbilical vein endothelial cells Abstract Aims/hypothesis. This study examines whether increased glucose concentrations are responsible for a decreased expression of membrane regulators of complement activation molecules. The effect of high glucose in determining an increase in membrane attack complex deposition on endothelial cells was also investigated. Methods. Endothelial cells were isolated from umbilical cord tissue, cultured in the presence of increased concentrations of glucose, and the expression of CD46, CD55, and CD59 was detected by ELISA (enzyme-linked immunosorbent assay) and by flow cytometry. Glucose-treated endothelial cells were also incubated with antiendothelial cell antibodies and fresh complement to assess the amount of membrane attack complex formation. Results. High concentrations of glucose decreased the expression of CD59 and CD55 by endothelial cells in a time-dependent and glucose concentration-dependent manner without affecting CD46 expression. High concentrations of soluble CD59 were found in the supernatants of cells treated with high glucose. The decrease in CD59 expression induced by high glucose concentrations was reversed by coincubation of cells with a calcium channel blocking agent (Verapamil). All of these effects were not reproduced by osmotic control media. Cells treated with concentrations of high glucose were more susceptible to complement activation and membrane attack complex formation after exposure to antiendothelial cell antibodies. Conclusion/Interpretation. We speculate that hyperglycaemia could directly contribute to a loss of CD59 and CD55 molecules through a calcium-dependent phosphoinositol-specific phospholipase C activation and subsequent regulation of cell wall expression of GPI-anchored proteins. This phenomenon could facilitate the activation of a complement pathway and could play a part in the aetiology of endothelial dysfunction in diabetes. [Diabetologia (2000

Redistribution of Glycolipid Raft Domain Components Induces Insulin-Mimetic Signaling in Rat Adipocytes

“…In vivo, PIG molecules as a putative physiological signal may be generated by lipolytic cleavage of GPI proteins at the outer face of the plasma membrane, which, in fact, has been reported for primary and cultured adipose, muscle, and endothelial cells in response to a number of hormones and growth factors, such as insulin and nerve growth factor (38,39), glucose (1,39), and the drug glimepiride (38,39). Alternatively, degradation products of free GPI lipids concentrated in DIG-caveolae may act in a similar fashion as the synthetic PIG used in the present study.…”

Elevated Properdin and Enhanced Complement Activation in First-Degree Relatives of South Asian Subjects With Type 2 Diabetes

“…Factor H, the major fluid-phase inhibitor of alternative C3 convertases, did not differ between relatives and control subjects, suggesting impaired alternative pathway inhibition does not contribute significantly to increased SC5b-9. CD55 and CD59 are membrane-bound inhibitors of C3/C5 convertases and C5b-9 insertion into cell membranes, respectively, are decreased on peripheral blood leukocytes of patients with type 2 diabetes (22) and in retinal vessels of patients with diabetic retinopathy (23), and decrease in response to elevated glucose in vitro (24). These studies suggest that reduced CD55 and CD59 may arise as a consequence of hyperglycemia and lead to complement-induced vascular complications.…”

Acquired Loss of Erythrocyte Complement Receptor Type 1 in Patients with Diabetic Nephropathy Undergoing Hemodialysis

“…We found that the HD patients with DMN had significantly lower levels of E-CR1, E-DAF and E-CD59 than the non-DMN HD patients. Accardo-Palumbo et al [29] reported that a high glucose level induced loss of DAF and CD59 from the surface of cultured human umbilical vein endothelial cells in vitro. Zhang et al [30] reported that the levels of DAF and CD59 in the retina were reduced in human and experimental diabetic retinopathy.…”