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Maillard Reaction Products Improve Antioxidant Defense Leading to Increases in Stress Tolerance in Cardiac Cells
Transcript of Maillard Reaction Products Improve Antioxidant Defense Leading to Increases in Stress Tolerance in Cardiac Cells
AGEs are products of the Maillard Reaction.
They are chemical modifications found on proteins, lipids, and nucleic acids.
Associated with Alzheimer's disease, fibrosis, and diabetes. Introduction: BCE (bread crust extract) Preparation Methods BCE pretreatment may mitigate effects of further oxidative stress in MCF Cell Culture and Treatments Results Bread crust extract influence on viability of cells, cell cycle, and proliferation decrease in cell death
elevated number of cells
increases in number of cells in the s-phase
no impairment of proliferation over seven days Oxidative stress simulation with hydrogen peroxide
over period of 24 hours
80% cell death in non-BCE group
reduction of 50% in BCE group gel electrophoresis results
BCE treated cells show moderate increase in prooxidative enzyme systems
Much more prominent activations of antioxidant enzymes and proteins Mn-SOD - primary free radical defense
highly increased production Prepared using a mixture of rye flour, water, and sourdough starter culture then incubated overnight at 26 degrees Celsius
Rye flour, wheat flour, water, sourdough, baker's yeast, and NaCl kneaded to make a mixture of rye/wheat dough
Baked in 2 baking tins for 24 mins at 260 degrees Celsius
Brown bread crust separated using kitchen knife
Crust and crumb frozen in liquid nitrogen then ground in a mill
BCE prepared by 15 mins sonification followed by centrifugation Cardiac fibroblast cell line (MCF) established from male mice
Adult cardiomyocytes were isolated from 8-10 week old male Wistar rats
Fibroblasts were grown to confluence, synchronized by cultivation in DMEM (0.1% calf serum) for 48 hours followed by treatment with a water-soluble BCE Cell Proliferation and Cycle Analysis Cells were seeded into 12-well dishes in DMEM containing 5% CS
After 5 hours, cells were treated with 10 mg/mL of BCE
Cells were detached using trypsin
Number of proliferating cells was determined using MultiCycle software Activity of signaling molecules disturbed.
rigidity of extracellular matrix strongly enhanced.
AGE crosslinks increase cardiac stiffness in aging individuals. AGE modification causes structural alterations on macromolecules, especially proteins. Performed with 3 weeks old nude mice
4 animals per group were fed for 14 days
Sacrificed by cervical dislocation for organ and blood sampling
All animal treatments were approved by local animal care and use committee Animal Feeding Experiments 1) One of the leading causes of death in the elderly.
2) Cardiomyocytes are subjected to nutrient and oxygen deprivation resulting in acidosis.
3) After reperfusion, huge flux of ions and ROS are observed.
4) This triggers reperfusion injury, causing apoptotic and necrotic cell death.
Ischemic pre- and postconditioning or antioxidants can have beneficial effects. Cardiac Fibroblasts: major cell type responsible for homeostatic maintenance of the extracellular matrix. Cardiac Tissue: Activated after myocardial infarction.
Involved in the development of fibrosis. -AGEs have been linked to a multitude of diseases such as diabetes, fibrosis and alzheimers.
-Meerwaldt et al. showed with diabetic patients that AGE associated skin autofluorescence was strongly linked to cardiac mortality
-Endogenous AGEs from a high fat diet also have been linked to cardiac inflammation and fibrosis.
-AGE rich diets linked to shortened life spans During aging and diseases such as diabetes and end stage renal disease, increasing amounts of AGE modified proteins, especially in the extracellular matrix have been detected and are involved in the development of several degenerative diseases. For example, Meerwaldt, could show in a five year study with diabetic patients that AGE associated skin autofluorescence was strongly linked to cardiac mortality. Endogenous AGEs resulting from a high fat diet have also been shown to lead to cardiac inflammation and fibrosis. Mice that are fed an AGE rich diet for long periods of time also experienced shortened life spans in general. ROS -Rise in Ros after stimulation of cardiac fibroblasts with BCE can be sufficient to trigger map kinases.
-Change in the signaling of these proteins by BCE limits their effects and influences fewer genes.
-As a result, these signals expression of oxidative and antioxidative enzyme systems was altered. This resulted in protection against severe oxidative stress in the MCFs as well as in cardiomyocytes. Discussion Gene Expression Pattern -The gene expression pattern shows SODs, ceruloplasmin, and vanins to be responsible for the increased tolerance towards oxidative stress.
-Increase in antioxidant GSH further contributes to antioxidant defense Multiple Mechanisms Involved The involvement of Ros and the signaling protein kinases
shows that the activation of antioxidant defense by BCE
depends upon overlapping mechanisms as the response to
ishemic conditioning. Conclusion -Nutritional preconditioning is an interesting
possibility to improve the resistance of cardiac
cells to ROS resulting from reperfusion.
-It has been shown in previous studies(Cai et al 2007) that chronic feeding with an AGE reduced diet seemed to extend the lifespan of mice, but because AGEs represent a large range of chemicals compounds it is not clear if long term feeding is beneficial. Nevertheless, this study puts up solid evidence that the model of AGEs always being harmful needs to be reassessed Intracellular Oxidative Stress Assay Formation of ROS determined by using 2’,7’ –dichlorofluorescin-diacetate
Determined dead cells by adding propidium iodide immediately before analysis Statistical Analysis Used 2-sided unpaired t-test
In case of multiple data, used one-way ANOVA test Robbie, Tyler, Daniel, Melyssa Activation of these receptors cause:
Activation of P38(MAPK): stress kinase
Activation of P42/44(MAPK): proliferation AGEs interact with binding proteins & AGE receptors on cells. Myocardial Infarction: Used a cardiac fibroblast cell line as model system.
to analyze food AGEs effect on oxidative stress
Oxidative and antioxidative enzyme systems
preconditioning against oxidative stress
Additional feeding experiments with mice were conducted to examine the relevance in an animal system.