Amyloidogenic Medin Impairs Endothelial Cell Autophagy and Viability that is Reversed by Monosialoganglioside Nanoliposomes
Authors: Karamanova Nina , Truran Seth , Weissig Volkmar , Madine Jillian , Davies Hannah , Guzman‐Villanueva Diana , Migrino Raymond 
Published: June 2021

BackgroundMedin peptides form the most common human amyloid proteins that accumulate in the vasculature with aging and are thus implicated as potential etiologic agents in the phenotypic changes associated with vascular aging. We previously showed that med in impairs endothelium‐mediated dilator response in human microvessels and induces pro‐inflammatory signaling. Impaired autophagy has been implicated in cellular aging and endothelial dysfunction and could be a mechanism by which med in links aging and vascular dysfunction. We also previously showed that monosialoganglioside nanoliposomes (NLGM1), phospholipids containing 5% monosialoganglioside, 70% phosphatidylcholine and 25% cholesterol, protect against endothelial dysfunction induced by amyloidogenic light chain proteins.AimTo test the hypothesis that med in impairs human endothelial cell autophagy and reduces cell viability and that NLGM1 will reverse these effects.MethodsHuman primary umbilical vein endothelial cells(HUVECs) were exposed to vehicle or medin (5 μM) for 20 hours without or with co‐treatment with NLGM1 (300 μM) or spermidine (3 mM), an agent known to stimulate endothelial cell autophagy and microtubule‐associated protein 1A/1B‐light chain 3 (LC3) was measured using Western blot, specifically the ratio of the conjugated form (LC3 II) to the cytosolic form (LC3 I) (LC3 II/I), a measure of autophagy. HUVECs were also exposed for 20 hours to vehicle or medin without or with co‐treatment of NLGM1 or NLGM1 and chloroquine (10 μM), an inhibitor of autophagy and cell viability was assessed using calcein‐acetoxymethyl (10 nmol/L) fluorescence by flow cytometry.ResultsHUVECs exposed to medin for 20 hours showed reduced LC3 II/I relative to vehicle control and reduced endothelial cell viability (see Figure). Co‐treatment of medin and spermidine restored LC3 II/I(1.55±0.06x control) and viability (0.86±0.08x control) (both p<0.05 vs. medin alone). Co‐treatment of medin with NLGM1 restored LC3II/I and cell viability. The protective effect of NLGM1 on cell viability with medin treatment was abolished when co‐treated with autophagy‐inhibitor chloroquine (0.65±0.12xcontrol, p<0.05 vs. medin+NLGM1).ConclusionsAmyloidogenic medin causes decreased endothelial cell viability that is likely related, at least in part, to reduced autophagy. Co‐treatment with NLGM1 restored endothelial cell autophagy and viability. Medin‐induced endothelial dysfunction through impaired autophagy is a novel mechanism of vascular injury that may be relevant in vascular aging. Nanoliposomes represent a potential new therapeutic class against amyloid‐mediated vascular injury.Support or Funding InformationVA Merit (BX‐003767/BX007080), British Heart Foundation (FS/12/61/29877), National Institutes of Health (NIAR21AG044723), US Department of Defense (AZ160056) and Midwestern UniversityThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.