Mechanism Of Food-derived Dityrosine Mediated Myocardial Tissue Damage And Intervention Studies

During food processing and storage,various physical,chemical and biological factors such as heat,radiation,acidity and alkalinity and peroxides are very likely to cause oxidative modifications such as amino acid side chain modifications,polypeptide chain breaks and protein cross-linking,resulting in structural changes of food proteins and affecting the textural properties and nutritional functions of foods.Dityrosine(DT)is a signature product of food protein oxidation and is widely found in high-protein processed foods.In recent years,the health hazards of DT have attracted widespread attention and focus in the academic community.The digestive and absorption characteristics and tissue accumulation of DT were clarified through various in vivo and in vitro experiments.The potential biological hazards of DT include elevated tissue free radicals,accumulation of oxidized protein products and abnormal energy metabolism.It is important to further elucidate the mechanisms of DT-induced oxidative damage and to develop effective dietary intervention strategies to improve the theory of food protein nutrition,to improve food processing technology and to improve the health quality of the population.First,this study was based on a meta-analysis of the correlation between serum advanced oxidation protein products(AOPPs)and major energy metabolism substrates and hormone levels in patients with metabolic diseases.The meta-analysis showed that patients with metabolic diseases had a large accumulation of serum AOPPs accompanied by high levels of fasting glucose,insulin,total cholesterol(TC)and total triglycerides(TG).In particular,fasting glucose and TG increased significantly with the increase of AOPPs concentration at serum AOPPs in the range of 0-120μmol/L,suggesting that the elevation of blood glucose and lipids caused by the accumulation of AOPPs is closely related to the disorder of energy metabolism of the body.Secondly,DT-mediated myocardial tissue injury and functional factor intervention in mice were investigated.Sixty-four 4-week-old C57BL/6J male mice were randomly divided into eight groups:control group(Con),DT group(DT),low/high dose puerarin group(PUR),low/high dose lycopene group(LYC),and low/high doseγ-aminobutyric acid group(GABA),sampled and analyzed after 35 days of continuous gavage.The results showed that DT gavage led to a significant accumulation of myocardial tissue protein oxidation products(AOPPs,DT)and free fatty acids,causing myocardial enzyme(LDH and CK)efflux and myocardial hypertrophy in mice compared to the Con group.At the same time,the level of reactive oxygen radicals(ROS)was significantly increased,and the total antioxidant capacity(T-AOC),antioxidant enzymes(SOD,GSH-Px,Mn-SOD)activity and non-enzymatic antioxidants(GSH/GSSG)content were significantly decreased.DT disrupted myocardial energy metabolism and mitochondrial function,as evidenced by decreased levels the energy substrate acetyl Co A,NADH/NAD~+ratio,abnormal mitochondrial ultrastructure,disorganized cristae structure,and significantly reduced ATP production.Intervention of the three functional factors alleviated myocardial injury and mitochondrial dysfunction in the DT group of mice to different degrees.Compared with puerarin andγ-aminobutyric acid,lycopene was more effective in enhancing ATP production and improving myocardial redox imbalance and abnormal mitochondrial energy metabolism.Finally,the molecular mechanism of DT-induced oxidative damage and lycopene intervention was further investigated by establishing a DT injury model for H9c2cardiomyocytes.The results showed that 10μM DT incubation for 72 h resulted in reduced cell survival,imbalance of cardiac enzyme efflux and redox homeostasis;disruption of mitochondrial membrane potential,causing blocked acetyl Co A utilization and insufficient ATP production;RNA-seq sequencing analysis revealed that DT mainly affected lipid metabolism and energy metabolism pathways,accelerating free fatty acid accumulation by enhancing fatty acid uptake and expression of key genes for fatty acid synthesis,while inhibiting peroxisomalβ-oxidation and interfering with oxidative phosphorylation processes and mitochondrial biosynthesis.Especially,the significant reduction of complex I,III and V activities was the main cause of insufficient myocardial ATP production.Incubation with 5μM lycopene significantly increased cell survival and reduced ROS levels;promoted Nrf2 entry into the nucleus and alleviated DT-mediated oxidative stress by inhibiting GSK-3βprotein phosphorylation levels;and restored mitochondrial and peroxisomal-oxidation gene expression levels,promoting fatty acid catabolism and reducing intracellular accumulation;KEGG and GO pathway enrichment analysis showed that the differentially expressed genes affected by lycopene were mainly focused on oxidative phosphorylation and myocardial contraction;they not only effectively restored the reduced energy substrate utilization caused by DT,but also significantly increased complex I and IV activities,which play a key role in maintaining mitochondrial membrane potential and ATP production.In conclusion,DT-mediated imbalance of redox homeostasis,mitochondrial dysfunction and energy metabolism disorders are the main factors leading to myocardial tissue damage.Lycopene effectively maintained myocardial redox homeostasis and mitochondrial function,enhanced complex I and IV activity,restored ATP synthesis and reduced intracellular fatty acid accumulation,and could be subsequently applied in dietary intervention strategies to reduce the health hazards of food oxidative proteins.