The Mechanism Of Emodin Nanocapsules Regulating Lipid Metabolism Reprogramming Induced Macrophage Polarization

Background: Acute pancreatitis(AP)is pancreatic inflammation caused by excessive activation of trypsin caused by alcohol and cholelithiasis,accompanied by systemic inflammatory response syndrome and multi-organ failure,high mortality rate,and no specific drugs.In clinical practice,fluid rehydration,inhibition of pancreatic enzyme secretion,water fasting and symptomatic treatment are mostly used.Macrophages play an important role in the development and development of acute pancreatitis.It activates in different ways in different internal environments or when stimulated by different conditions.Macrophages present with a pro-inflammatory phenotype(M1 type)or an inflammatory phenotype(M2 type).Stimulated by lipopolysaccharides(LPS),macrophage metabolism shifts from oxidative phosphorylation to glycolysis,called metabolic reprogramming.Similarly,the metabolic mode of intracellular mitochondria is also converted from ATP synthesis to reactive oxygen species production,which is manifested by stimulating macrophages to polarize to M1 type,while M2 polarization is inhibited.Therefore,how to effectively inhibit the polarization of macrophages to M1 type and then inhibit the inflammatory response,and induce the polarization of macrophages to M2 type that inhibits the inflammatory response,is an effective strategy for the treatment of acute pancreatitis.Previous studies in our group confirmed that the preparation of traditional Chinese medicine monomer emodin into emodin nanocapsules can induce macrophages to M2-type polarization(repolarization)for the treatment of acute pancreatitis on the basis of significantly improving the bioavailability of emodin and reducing biotoxicity.Therefore,this study preliminarily explores the possible mechanism of emodin nanocapsules inducing macrophage repolarization from the perspective of metabolic reprogramming.Objective:(1)To investigate the differences in lipid metabolism of macrophages in different polarization states.(2)An attempt was made to explore the role of emodin nanocapsules in regulating macrophage metabolic reprogramming.(3)To investigate the effect of long-chain fatty acid metabolism-related protein carnitine palmitoyltransferase 1(CPT1)on macrophage polarization and the efficacy of emodin nanocapsules.Methods:(1)The lipidomics-oriented method was compared and analyzed by the different lipids of each experimental group,and the main changes in the repolarization process of macrophages were obtained.(2)Combined with literature research,the expression of CPT1 protein in each experimental group was detected by gene knockdown,overexpression,immunofluorescence,Real-time PCR and other methods.(3)A mouse model of acute pancreatitis was established,and emodin nanocapsule treatment was used to verify the above experimental results through in vivo experiments.Results:(1)The lipid metabolites of mouse monocyte macrophage leukemia cells RAW264.7 changed significantly under the stimulation of LPS(1μg/m L),mainly manifested as lipid metabolism species(mainly phosphatidylcholine,phosphatidylethanolamine and sphingomyelin,including glycerophospholipid metabolism,sphingolipid metabolism,etherlipid metabolism,glyceride metabolism,inositol phosphate metabolism,linoleic acid metabolism,α-linolenic acid metabolism and fatty acid metabolism)and their contents decreased.(2)During the metabolic reprogramming of macrophages to M2-type repolarization induced by emodin nanocapsules,the main differential metabolites are enriched in the metabolic pathway of long-chain fatty acids.(3)Using gene knockdown,overexpression and other methods,it was proved that the expression of CPT1 protein was negatively correlated with the M1 polarization of macrophages RAW264.7,and positively correlated with M2 polarization.The use of emodin nanocapsules significantly promoted the expression of CPT1 protein in M1 macrophages,polarizing macrophages from M1 to M2.(4)The expression of CPT1 in the pancreas was significantly increased in the model mice of acute pancreatitis treated with emodin nanocapsules.Conclusion:(1)Emodin nanocapsules induce macrophage lipid metabolism reprogramming during the polarization of macrophages from M1 type to M2 type,and the change of this metabolic mode is mainly achieved by changing the metabolism of long-chain fatty acids.(2)Emodin nanocapsules increase the transport of long-chain fatty acids into mitochondria by promoting the expression of CPT1,and induce the transformation of macrophages from pro-inflammatory phenotype to inflammatory phenotype,thereby treating acute pancreatitis.