Angiogenic transforming capacity of IgG purified from plasma of type 1 diabetic patients.
We previously demonstrated that plasma of type 1 diabetic patients contains antibodies complexed irreversibly with Grp94 that also display proteolytic activity. In this work, we wanted to test whether antibodies obtained from diabetic plasma may convey an inflammatory risk on vascular cells. To this aim, IgG were purified on the Protein-G column from individual plasma of eight type 1 diabetic patients, and then tested on HUVECs to measure effects on cell growth and morphologic changes at different incubation times. The purified fractions of IgG contained a significant amount of Fab/(Fab)(2), both free and in big aggregates, and anti-Grp94 antibodies, mostly irreversibly linked with, but also free of Grp94. The purified fractions of both Fab/(Fab)(2) and whole IgG stimulated the proliferation and sustained the angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) at sub-nanomolar concentrations. IgG from normal plasma neither stimulated the cell growth nor induced any differentiation of HUVECs. The maximum cell growth stimulation occurred at 6-9 hrs and associated with the strong activation of the ERK1/2 pathway, whereas angiogenic transformation was completed later when the ERK1/2 activation was silenced and cell growth stimulation significantly reduced. Neither proteolytic activity of MMP-9 nor VEGF were apparently involved in mediating the angiogenic differentiation of HUVECs that mostly correlated with an increased expression of HSP70 closely coupled with cell membrane-bound inactive species of MMP-9. Results indicate that effects displayed on HUVECs by antibodies purified from diabetic plasma are likely sustained by immune complexes with Grp94 that may thus predict an increased risk of angiogenic transformation in vivo.
Tramentozzi
Elisa
E
Department of Pharmacology and Anesthesiology, University of Padova, Padova, Italy.
Pagetta
Andrea
A
Frasson
Martina
M
Brunati
Anna Maria
AM
Montopoli
Monica
M
Finotti
Paola
P
D000293:Adolescent; D000328:Adult; D000941:Antigens / Q000276:immunology; D002454:Cell Differentiation; D049109:Cell Proliferation; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000276:immunology*; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood* / Q000302:isolation & purification*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000276:immunology*; D011499:Protein Processing, Post-Translational; D013997:Time Factors; D014471:Umbilical Veins / Q000166:cytology
D000941:Antigens; D018840:HSP70 Heat-Shock Proteins; D007140:Immunoglobulin Fab Fragments; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; C053387:endoplasmin; D048049:Extracellular Signal-Regulated MAP Kinases; D020780:Matrix Metalloproteinase 9