ABSTRACT
Objective: Species-specific pseudogenization of the CMAH gene during human evolution eliminated common mammalian sialic acid N-glycolylneuraminic acid (Neu5Gc) biosynthesis from its precursor N-acetylneuraminic acid (Neu5Ac). With metabolic nonhuman Neu5Gc incorporation into endothelia from red meat, the major dietary source, anti-Neu5Gc antibodies appeared. Human-like Ldlr-/-Cmah-/- mice on a high-fat diet supplemented with a Neu5Gc-enriched mucin, to mimic human red meat consumption, suffered increased atherosclerosis if human-like anti-Neu5Gc antibodies were elicited. Approach and Results: We now ask whether interventional Neu5Ac feeding attenuates metabolically incorporated Neu5Gc-mediated inflammatory acceleration of atherogenesis in this Cmah-/-Ldlr-/- model system. Switching to a Neu5Gc-free high-fat diet or adding a 5-fold excess of Collocalia mucoid-derived Neu5Ac in high-fat diet protects against accelerated atherosclerosis. Switching completely from a Neu5Gc-rich to a Neu5Ac-rich diet further reduces severity. Remarkably, feeding Neu5Ac-enriched high-fat diet alone has a substantial intrinsic protective effect against atherosclerosis in Ldlr-/- mice even in the absence of dietary Neu5Gc but only in the human-like Cmah-null background. Conclusions: Interventional Neu5Ac feeding can mitigate or prevent the red meat/Neu5Gc-mediated increased risk for atherosclerosis, and has an intrinsic protective effect, even in the absence of Neu5Gc feeding. These findings suggest that similar interventions should be tried in humans and that Neu5Ac-enriched diets alone should also be investigated further.
Subject(s)
Aorta/metabolism , Aortic Diseases/prevention & control , Atherosclerosis/prevention & control , Dietary Supplements , N-Acetylneuraminic Acid/administration & dosage , Neuraminic Acids/administration & dosage , Plaque, Atherosclerotic , Animal Feed , Animals , Antibodies/metabolism , Aorta/pathology , Aortic Diseases/genetics , Aortic Diseases/metabolism , Aortic Diseases/pathology , Atherosclerosis/genetics , Atherosclerosis/metabolism , Atherosclerosis/pathology , Diet, High-Fat , Disease Models, Animal , Foam Cells/metabolism , Foam Cells/pathology , Humans , Male , Mice, Inbred C57BL , Mice, Knockout , Mixed Function Oxygenases/genetics , Mixed Function Oxygenases/metabolism , N-Acetylneuraminic Acid/metabolism , Neuraminic Acids/immunology , Neuraminic Acids/metabolism , Pan troglodytes , Receptors, LDL/genetics , Receptors, LDL/metabolism , Sialadenitis/metabolism , Sialadenitis/pathology , THP-1 CellsABSTRACT
Heparan sulfate glycosaminoglycans (HS GAGs) attached to proteoglycans harbor high affinity binding sites for various growth factors (GFs) and direct their organization and activity across the cell-matrix interface. Here, we describe a mild and efficient method for generating HS-protein conjugates. The two-step process utilizes a "copper-free click" coupling between differentially sulfated heparinoids primed at their reducing end with an azide handle and a bovine serum albumin protein modified with complementary cyclooctyne functionality. When adsorbed on tissue culture substrates, the glycoconjugates served as extracellular matrix proteoglycan models with the ability to sequester FGF2 and influence mesenchymal stem cell proliferation based on the structure of their HS GAG component.