The Effect And Mechanism Of Isoxanthohumol On Inflammatory Factor Secretion And Lipid Accumulation In Macrophages

[Background and Objective]: Atherosclerosis(AS)is a chronic disease of the arterial wall.It is the common pathological basis of cardiovascular and cerebrovascular diseases such as coronary heart disease,cerebral infarction and peripheral vascular disease.Its main mechanism of action is vascular wall lipid accumulation and inflammatory reaction.Macrophages,as key cell types in the AS process,play an important role in inflammation and lipid accumulation.Studies have shown that macrophage-derived lipoprotein lipase(LPL)promotes the formation of foam cells by increasing the uptake of lipids,while macrophage-derived LPL also promotes the secretion of inflammatory factors,which play the role of promoting AS.In recent years,studies have found that flavonoids play an important role in the process of atherosclerosis.Isoxanthohumol is a prenyl flavonoid extracted from hops.Studies have found that isoxanthohumol has effects on anti-inflammatory,anti-oxidant and lipid metabolism,but its specificmechanism on AS is unclear.Peroxisome proliferators-activated receptorγ(PPARγ)is a ligand-activated receptor in the nuclear hormone receptor family and plays a role in lipid metabolism and inflammatory responses.Study indicates that PPARγ can promote LPL expression in macrophages.At the same time,it has been found that isoxanthohumol can inhibit PPARγ.The ramamycin target of rapamycin(m TOR)plays an important role in the AS process.The m TOR inhibitor rapamycin reduces fat cell lipid accumulation by inhibiting PPARγ expression.Sestrin2 is a negative feedback regulator of m TOR,and down-regulation of Sestrin2 can increase the area of ? ? atherosclerotic plaque in mice.The aim of this study was to investigate the effects of isoxanthohumol on the expression of LPL and its mediated inflammatory factor secretion and lipid accumulation in macrophages and the underlying molecular mechanisms.Our results indicate that isoxanthohumol may inhibit macrophage inflammatory response and lipid accumulation by increasing Sestrin2 inhibition of m TOR-PPARγ pathway and down-regulating LPL expression in macrophages.These data suggest that isoxanthohumol may provide new ideas for the prevention and treatment of atherosclerosis.[Methods]:THP-1 derived foam cells were treated with different concentrations(0,5,10,20,40 μM)of isoxanthohumol for 24 hours.The expression of LPL m RNA and protein in macrophages was detected by q PCR and Western Blotting,respectively.The cells were treated with 20μM isoxanthohumol for different time(0,6,12,24,48 h),q PCR and Western Blotting were used to detect the expression of LPL in macrophages;cells treated with 20 μM isoxanthohumol for 24 hours,q PCR and Western Blotting was used to detect the expression of m TOR and PPARγ m RNA and protein.Then,the cells were treated with m TOR agonist leucine and PPARγ agonist rosiglitazone to detect the expression of PPARγ and LPL.The cells were treated with 20 μM isoxanthohumol for 24 hours,the expression of Sestrin2 m RNA and protein was detected by q PCR and Western Blotting.The expression of m TOR,PPARγ and LPL was detected by transfecting Sestrin2 si RNA.The cells were overexpressed with LPL and the proinflammatory cytokines IL-6 and IL-1β,MCP-1,TNF-α and anti-inflammatory factor IL-10 levels were detected by ELISA,high phase liquid chromatography(HPLC)for detection of total cholesterol(TC)Free cholesterol(free cholesterol,FC)and cholesterol esters(cholesterol ester,CE)content.[Results]:Isoxanthohumol down-regulates the expression of LPL m RNA and protein in macrophages in a concentration-and time-dependent manner.Isoxanthohumol inhibits the expression of PPARγ;Rosiglitazone,which is PPARγ agonist can reverse the down-regulation of LPL expression by isoxanthohumol;isoxanthohumol inhibits m TOR expression,while m TOR agonist leucine can alleviate the inhibitory effect of isoxanthohumol on PPARγ and LPL expression;isoxanthohumol increased the expression level of Sestrin2,and the expression of m TOR,PPARγ and LPL was restored after transfection of Sestrin2 si RNA.Isoxanthohumol can significantly reduce the levels of pro-inflammatory factors IL-6,IL-1β,TNF-α and MCP-1 in macrophages,increase the level of anti-inflammatory factor IL-10,and reduce the levels of TC,FC and CE in cells.However,after overexpression of LPL,the levels of pro-inflammatory factors and intracellular lipids increased significantly,and the levels of anti-inflammatory factors were significantly reduced.[Conclusion] : Isoxanthohumol inhibits LPL expression by increasing Sestrin2 and inhibiting the m TOR-PPARγ pathway in macrophage,thereby reducing macrophage inflammatory response and lipid accumulation.