Mechnism Study Of Arsenic Exposure On Vascular Endothelial Homeostasis

BACKGROUND:Arsenic contamination in drinking water is a well-known environmental problem,which can lead to several severe health disorders.Epidemiological studies showed that chronical arsenic exposure at low levels correlates with atherosclerosis,but the molecular mechanisms remained unclear.Recent studies indicated that calpains?CAPNs?were activated during arsenic exposure.Considering the potential roles of arsenic and CAPNs in endothelial cell functions,we hypothesized that endothelial dysfunction induced by arsenic exposure may be mediated by CAPN activation.OBJECTIVES:1)Three different arsenicals were used to evaluate the effects of arsenic exposure on endothelial dysfunction using mouse models or cultured endothelial cell monolayers.2)Effects of arsenic exposure on total arsenic,arsenic species,CAPN activity and expression levels of CAPNs in aortas and endothelial cells were detected.3)Membrane translocation of CAPN-1,association of CAPN-1 with calpastatin?CAST?and proteolysis of VE-cadherin were also detected to study the mechanisms.RESULTS:1)Aortas of mice exposed to ATO?10 ppb of arsenic?exhibited higher vascular permeability to Evans blue and FITC labeled-bovine serum albumin?FITC-BSA?,and cultured endothelial cells monolayers treated with ATO?0.13?M of arsenic?exhibited greater intracellular gaps and permeability to low density lipoprotein or THP-1 cells.2)Total arsenic accumulated in aortas of ATO treated-mice and ATO treated-cells,and i As?III?was the major arsenic metabolite.3)Both aortas of ATO treated-mice and ATO treated-cells exhibited higher levels of CAPN activity and expression levels of CAPN-1,as well as a rapid increase in intracellular calcium([Ca²⁺]i).4)Although CAST showed a stronger interaction with CAPN-1,higher levels of CAPN-1 in the plasma membrane and the proteolytic disorganization of VE-cadherin were detected.Additionally,endothelial cell dysfunction and the proteolytic disorganization of VE-cadherin were partially rescued by treatment with a CAPN-1inhibitor?ALLM?.CONCLUSIONS:1)ATO existed as i As?III?in endothelial cells and aortas after being uptook,and led to vascular endothelial dysfunction assiciated with CAPN-1 activation.This increased activity was associated with a rapid rise in[Ca²⁺]i,increased CAPN-1 levels and membrane localization of CAPN-1,which further led to increased proteolytic disorganization of VE-cadherin.2)The findings presented herein suggested that ATO induced vascular endothelial dysfunction involved hyperactivation of the CAPN proteolytic system.ALLM treatment may prevent the vascular endothelial dysfunction associated with arsenic exposure.