Bioavailability Of Resveratrol And The Mechanism Of Its Anti-inflammatory Effect In The Vascular Endothelial Cells

Cardiovascular disease has become the leading cause of human death, atherosclerosis(AS) is the main pathology of cardiovascular disease. Unhealthy lifestyle and unreasonabledietary structure are closely related to AS. AS is a multi-factor and multi-stage complexpathological process, whose pathogenesis has not been fully elucidated. Oxidative damageand the inflammatory response doctrine is the most recognized theory to explain thepathogenesis of AS. The theory demonstrates that oxidative stress damage in vascularendothelial cells is the iniative step of AS, and the inflammatory response is an importantfactor in promoting the pathological process of AS. Therefore，attenuating the inflammatoryinjury of vascular endothelial cells has become an important way for the prevention andtreatment of AS. A large number of studies have found that plant food intake was negativelycorrelated with a variety of chronic metabolic diseases, and the major effective compositionwas phytochemicals. There are many kinds of phytochemicals including polyphenols,carotenoids, saponins, sulfur compounds, among which the most studied one is polyphenols.Resveratrol (RSV) is an important polyphenolic compound, and epidemiological studies havefound that dietary intake of RSV is in a signiifcant negative correlation to the incidence ofcardiovascular disease. However, the relevant mechanisms are not yet fully elucidated. On theone hand, metabolism and bioavailability study found that RSV is mainly absorbed in thesmall intestine with high eiffciency but very low bioavailability in humans, due to rapidmetabolism in vivo. And the physiological effects of dietary RSV appeared to be in strikingcontrast to its poor bioavailability, unless attributable to yet unidentiifed uptake and utilizationin vascular endothelial cells or vessel wall and targeted organizations distribution. On theother hand, recently, studies have shown that autophagy plays a key role in the inhibition ofcertain inlfammatory injuries to maintain cellular homeostasis in endothelial cells. However,whether RSV is able to inhibit endothelial inflammation by inducing autophagy and the exactintracellular targets and mechanisms remain to be further exploration. In the current study, depending on the spontaneous fluorescence characteristics of RSV,we used lfuorescence spectrophotometer, HPLC，LC-MS，laser scanning confocal，RNAimethods to investigate the uptake and cellular distribution of RSV in vascular endothelialcells，and analysised the time, concentration, and temperature-dependent characteristics of theuptake, thereby to explore the role of serum proteins and SGLT1in the transmembranetransporte of RSV in endothelial cells. Furthermore, endothelial inflammation an importantincentive for AS development was also studied. In order to construct a model of endothelialinflammation in vitro, we used TNF-a to treat endothelial cells at different concentrations.Thereafter, we used a variety of inhibitors, agonists, RNAi, plasmid transfection and westernblot to observe the effect of RSV on autophagy and further clarify the impact of RSV oncAMP-PKA-AMPK-SIRT1signaling pathways, to reveal the underlying mechanism ofRSV’s anti-inlfammatory effect in endothelial cells.The main results and conclusions of this study are as follows:(1)RSV could be absorbed by vascular endothelial cells and mainly distributed in thecytoplasm, and was permanently available in blood vessels in vivo.(2)RSV penetrated into endothelial cells through both passive diffusion and activetransport. The passive diffusion was affected by serum proteins especially albumin, and theactive transport was partially relied on SGLT1receptor.(3)RSV could signiifcantly attenuated TNF-a-induced endothelial inlfammation,through inhibiting inflammatory cytokines release and inflammatory mediators expression.(4)Autophagy was important for the inhibitive effect of RSV on TNF-a-inducedendothelial inlfammation. RSV could increase autophagy in a dose-and time-dependentmanner in endothelial cells. When autophagy was suppressed, the anti-inflammatory effect ofRSV was significantly weakened.(5)SIRT1-related signaling pathway plays an important role in RSV-induced autophagyin endothelial cells. RSV could increase the camp levels in endothelial cells，therebypromoting the expression of PKA and AMPK activation, leading to an increase of SIRT1expression. In the presence of inhibitors of AC，PKA, AMPK, or SIRT1，as well as AC，PKA,AMPK, and SIRT1saran trans feet ion，RSV-induced autophagy was signiifcantly abolished.These results indicate that cAMP-PKA-AMPK-SIRTl signaling pathway plays an importantrole in mediating RSV-induced autophagy. In summary, RSV could be effectively absorbed by vascular endothelial cells and waspermanently available in blood vessels in vivo. As well，RSV could attenuate endothelialinflammation through the activation of SIRT1/autophagy-related signaling pathway.The effects of phytochemicals on health promotion have become a hotspot in theresearch ifeld of nutrition and chronic metabolic diseases, which might become leadcompounds in drug design. The results of this study are important for understanding themechanisms of cardiovascular protective effects of RSV and designing more effective drugsfor the prevention and treatment of cardiovascular disease.