Maillardprodukte/Advanced Glycation End Products (AGEs) und ihre gesundheitlichen Folgen

Da in diesem Forum schon des Öfteren Zweifel daran geäußert wurden, dass das Hitzegaren von Nahrung gesundheitliche Nachteile mit sich bringen würde, obwohl die Schädlichkeit mancher Garmethoden wie Braten und Frittieren unzweideutig erwiesen ist (Acrolein, trans-Fette, Acrylamid etc), möchte ich einen weiteren Beitrag zu dieser Thematik bringen:


Accumulation of Maillard reaction products in skin collagen in diabetes and aging.

To investigate the contribution of glycation and oxidation reactions to the modification of insoluble collagen in aging and diabetes, Maillard reaction products were measured in skin collagen from 39 type 1 diabetic patients and 52 nondiabetic control subjects. Compounds studied included fructoselysine (FL), the initial glycation product, and the glycoxidation products, N epsilon-(carboxymethyl) lysine (CML) and pentosidine, formed during later Maillard reactions. Collagen-linked fluorescence was also studied. In nondiabetic subjects, glycation of collagen (FL content) increased only 33% between 20 and 85 yr of age. In contrast, CML, pentosidine and fluorescence increased five-fold, correlating strongly with age. In diabetic patients, collagen FL was increased threefold compared with nondiabetic subjects, correlating strongly with glycated hemoglobin but not with age. Collagen CML, pentosidine and fluorescence were increased up to twofold in diabetic compared with control patients: this could be explained by the increase in glycation alone, without invoking increased oxidative stress. There were strong correlations among CML, pentosidine and fluorescence in both groups, providing evidence for age-dependent chemical modification of collagen via the Maillard reaction, and acceleration of this process in diabetes. These results support the description of diabetes as a disease characterized by accelerated chemical aging of long-lived tissue proteins.

http://www.ncbi.nlm.nih.gov/pubmed/8514858


Health effects of dietary Maillard reaction products: the results of ICARE and other studies.

In food science the Maillard reaction is well known to cause degradation of amino acids and an overall decrease in the nutritional value of foods that have been subjected to heat in processing. There has been evidence more recently of the endogenous formation of some Maillard reaction products (MRPs) in biological systems and their association with pathophysiological conditions including diabetes, renal disease and cardiovascular disease. Several studies have suggested that dietary MRPs increase the in vivo pool of MRPs after intestinal absorption and contribute to the development of diabetes and related complications. This review focuses on the animal and human studies which have assessed the eventual implications of dietary MRPs on human health, highlighting the different diets tested, the experimental designs and the biomarkers selected to estimate the health effects. The results of these studies are compared to those of the recently published ICARE study. In this latter study an accurate determination of the MRP content of the diets was achieved, allowing the calculation of the contribution of individual food groups to daily MRP intakes in a regular western diet.

http://www.ncbi.nlm.nih.gov/pubmed/20949364


Influence of the maillard reaction to prion protein aggregation.

Prion diseases are fatal neurodegenerative diseases that occur either spontaneously or genetically or are caused by infection. Spontaneously occurring prion diseases are age related. The infectious agents, called prions, are proteinaceous infectious particles, composed mainly of the host-encoded prion protein (PrP) in a misfolded, insoluble, and aggregated isoform. Advanced glycation end products (AGEs) are well known to contribute to protein misfolding, insolubility, and aggregation. Thus, we studied if AGE-modification could influence PrP aggregation. We analyzed PrP preparations immunochemically to determine if they contain AGE-modified PrP. We also studied the influence of AGE modifications on the PrP aggregation process in vitro.

http://www.ncbi.nlm.nih.gov/pubmed/20370497


The pathogenic role of Maillard reaction in the aging eye.

The proteins of the human eye are highly susceptible to the formation of advanced glycation end products (AGEs) from the reaction of sugars and carbonyl compounds. AGEs progressively accumulate in the aging lens and retina and accumulate at a higher rate in diseases that adversely affect vision such as, cataract, diabetic retinopathy and age-related macular degeneration. In the lens AGEs induce irreversible changes in structural proteins, which lead to lens protein aggregation and formation of high-molecular-weight aggregates that scatter light and impede vision. In the retina AGEs modify intra- and extracellular proteins that lead to an increase in oxidative stress and formation of pro-inflammatory cytokines, which promote vascular dysfunction. This review outlines recent advances in AGE research focusing on the mechanisms of their formation and their role in cataract and pathologies of the retina. The therapeutic action and pharmacological strategies of anti-AGE agents that can inhibit or prevent AGE formation in the eye are also discussed.

http://www.ncbi.nlm.nih.gov/pubmed/20963455


Inflammatory effect of advanced glycation end products on human meniscal cells from osteoarthritic knees.

OBJECTIVE:

To investigate the inflammatory effects of advanced glycation end-products (AGEs) through the receptor for AGE in meniscal cells from osteoarthritic knees, and examine effects of hyaluronan (HA) on AGE-induced inflammation.
METHODS:

Meniscal cells from human osteoarthritic knees were cultured with or without glycolaldehyde-AGE-bovine serum albumin and 800 kDa HA. The amount of prostaglandin E(2) (PGE(2)) protein was determined using an enzyme immunoassay system. Expression of cyclooxygenase (COX)-1, COX-2, membrane associated prostaglandin E synthase (mPGES)-1 and cytosolic PGES (cPGES) was analyzed by real-time reverse transcription polymerase chain reaction and western blotting.
RESULTS:

PGE(2) synthesis was significantly increased by AGEs, and AGE-induced PGE(2) production was attenuated by addition of HA. While COX-2 and mPGES-1 expression was significantly upregulated by AGEs, COX-1 and cPGES expression was not affected by AGE. AGE-stimulated COX-2 and mPGES-1 expression was attenuated by HA through CD44 (HA receptor). However, the changes in COX-1 and cPGES expression were almost negligible.
CONCLUSION:

In meniscal cells from osteoarthritic knees, AGEs increased the production of inflammatory mediators, including PGE(2), COX-2 and mPGES-1. Furthermore, HA could decrease AGE-induced production of PGE(2), COX-2 and mPGES-1 through CD44.

http://www.ncbi.nlm.nih.gov/pubmed/21842276

Maillairdprodukte entstehen bei jeder Form der Garung:

Formation of Maillard reaction products during heat treatment of carrots.

As indicators of the early stage of the Maillard reaction in carrots, N-(furoylmethyl) amino acids (FMAAs) formed during acid hydrolysis of the corresponding Amadori products were analyzed using RP-HPLC with UV detection. N(ε)-FM-Lys (furosine), FM-Gly, FM-Ala, FM-Val, FM-Ile, FM-Leu, and FM-GABA were identified using synthesized standard material by means of mass spectrometry. Furthermore, N(ε)-carboxymethyllysine (CML) and pyrraline were analyzed as indicators for advanced stages of glycation. For commercial samples with high water content, the formation of Amadori compounds predominates, whereas the advanced stage of Maillard reaction plays only a minor part. Carrot juices, baby food, and tinned carrots showed quite low rates of amino acid modification up to 5%. For dehydrated carrots, significantly higher values for Amadori products were measured, corresponding to a lysine derivatization of up to 58% and nearly 100% derivatization of GABA. Drying experiments revealed great differences in reactivity between the amino acids studied. Whereas furosine reached constant values quite quickly, some FMAAs showed a continuous increase with heating time, indicating that selected FMAAs can be used as a hallmark for the early Maillard reaction to control processing conditions.

http://www.ncbi.nlm.nih.gov/pubmed/21682346


Immunantwort auf erhitzte Nahrung:

Heating Affects Structure, Enterocyte Adsorption and Signalling, As Well as Immunogenicity of the Peanut Allergen Ara h 2

Previous studies have indicated that specific molecular properties of proteins may determine their allergenicity. Allergen interaction with epithelia as the first contact site could be decisive for a resulting immune response. We investigate here for the major peanut allergen Ara h 2 whether thermal processing results in structural changes which may impact the protein's molecular interactions with enterocytes, subsequent cellular signalling response, and immunogenicity.Ara h 2 was heat processed and analyzed in terms of patient IgE binding, structural alterations, interaction with human enterocytes and associated signalling as well as immunogenicity in a food allergy mouse model.Heating of Ara h 2 led to significantly enhanced binding to Caco-2/TC7 human intestinal epithelial cells. Structural analyses indicated that heating caused persistent structural changes and led to the formation of Ara h 2 oligomers in solution. Heated protein exhibited a significantly higher immunogenic potential in vivo as determined by IgG and IgE serum antibody levels as well as IL-2 and IL-6 release by splenocytes. In human Caco-2/TC7 cells, Ara h 2 incubation led to a response in immune- and stress signalling related pathway components at the RNA level, whereas heated allergen induced a stress-response only.We suggest from this peanut allergen example that food processing may change the molecular immunogenicity and modulate the interaction capacity of food allergens with the intestinal epithelium. Increased binding behaviour to enterocytes and initiation of signalling pathways could trigger the epimmunome and influence the sensitization capacity of food proteins.

http://www.ncbi.nlm.nih.gov/pubmed/22318448


Wiederum: Maillairdprodukte und Entzündungsgeschehen/Alterungsprozess:

Maillard reaction products in food as pro-inflammatory and pro-arteriosclerotic factors of degenerative diseases

Heating of food induces the formation of Maillard reaction products (MRPs) caused by the reaction of reducing sugars with proteins or amino acids. Analogous reactions occur in the human body, eventually forming "Advanced Glycation Endproducts" (AGEs). AGEs accumulate in aging tissues accelerating degenerative-inflammatory and proliferative processes. MRPs present in food can also directly cause inflammatory processes in the intestines and, once absorbed, would support and reinforce any inflammatory and degenerative process occurring in the body. The contribution of AGEs (and additional MRPs) in the development of diabetic complications as well as nephropathy, neuropathy, micro- and macroangiopathies is now well established. Which of the MRPs or AGEs in particular induce these cellular processes is currently unknown. Thus the exact knowledge of the chemical structures of the MRPs could help to minimize the formation of "harmful MRPs" that occur due to heating in food processing. Because MRPs play a decisive role in the successful marketing of edibles due to their characteristics as flavor components, it is important to increase the amount of innocuous and palatable MRPs, and minimize signal active pro-inflammatory MRPs by the use of defined preparation methods. It is practicable to use low-priced immunological methods for the quantitative determination of specific MRPs or AGEs. In the medical area, the knowledge of the signal active MRP/AGE structures provides the opportunity to measure their concentrations in body fluids and tissues and thus determine their influence on inflammatory and age-related degenerative processes (e. g., late diabetic complications, arteriosclerosis, degeneration of neurons). From a clinical perspective, the application of RAGE antagonists after an appropriate chemical diagnosis could be effective in supporting the treatment of affected patient groups, especially older diabetic and dialysis patients.

http://www.ncbi.nlm.nih.gov/pubmed/16244820



Die Wirkung von Glycationsendprodukten auf das Immunsystem, Entzündungsmechanismen und Zellfunktionen:

Advanced Glycation End Products (AGE)

Nonenzymatic modification of proteins by reducing sugars leads to the formation of AGEs in vivo. These reactions take part during aging and substantially accelerate during cancers, diabetes, and atherosclerosis (155). Although the mechanisms are not fully identified, the alterations in glucose and lipid metabolism likely lead to the production of excess aldehydes and formation of AGEs. AGEs act directly or via receptors and participate in the cross-linking proteins of extracellular matrix (155). The receptor for AGE (RAGE) is a member of the immunoglobulin superfamily and is expressed by ECs, SMCs, monocytes, and lymphocytes with enhanced expression in atherosclerotic lesions. Neutralizing AGE by the administration of soluble recombinant RAGE reduced NF-κB induction, VCAM-1 and tissue factor expression, and atherosclerotic lesion burden (156). A critical role for RAGE and its ligands was also demonstrated in RAGE-deficient Apoe−/− mice and in Apoe−/− transgenic mice expressing human dominant-negative RAGE (157). The AGE/RAGE axis has a broad spectrum of effects and elicits oxidative stress, increases endothelial dysfunction, increases production of inflammatory cytokines and tissue factor, elevates expression of adhesion molecules, and, through all these mechanisms, accelerates development of atherosclerosis (155).

aus: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2734407/

Ich kann nur mutmaßen, wieso es keine Reaktionen auf Deinen angefangenen Thread gibt. Ich für meinen Teil diskutiere lieber oberflächlich als mich stundenlang mit medizinischen Texten auf Englisch auseinanderzusetzen.
Und wer sich mit Dir auf eine Diskussion einlässt, kommt da so schnell nicht mehr raus.
Das ist ebennfalls sehr anstrengend.