Interactions of IgG and beta-VLDL with aortic valve endothelium from hypercholesterolemic rabbits.

The adhesion of immunoglobulins (IgG) and beta-migrating very low density lipoproteins (beta-VLDL) to aortic valve cusps from normolipidemic and hypercholesterolemic rabbits is associated with cytochemical changes in the endothelial glycocalyx. Endothelial surface changes are characterized by (1) enzymatic degradations with neuraminidase (NEU), chondroitinase ABC (CABC) or AC, and heparitinase (HPT); and (2) affinity cytochemistry with avidin-ferritin, protein A-HRP, and beta-VLDL-colloidal gold. NEU facilitated IgG deposition on cells from normolipid animals; however, tandem treatment with NEU and CABC increased beta-VLDL but prevented IgG interactions. The addition of HPT was required to eliminate beta-VLDL activity. The cells lining the arterial surfaces of cusps from hypercholesterolemic animals were reactive for endogenous IgG and beta-VLDL-gold. CABC enhanced the binding of the latter but removed most of the IgG. All reactivity was prevented by CABC and HPT. These findings suggest that the reduction of sialic acid residues and exposure of deeper lying glycosaminoglycans in the endothelial glycocalyx favor the interaction of blood-borne elements at natural sites of disturbed blood flow in dietary hypercholesterolemia.