José C. E. Serrano

Pathological aspects of lipid peroxidation.

Abstract Lipid peroxidation (LPO) product accumulation in human tissues is a major cause of tissular and cellular dysfunction that plays a major role in ageing and most age-related and oxidative stress-related diseases. The current evidence for the implication of LPO in pathological processes is discussed in this review. New data and literature review are provided evaluating the role of LPO in the pathophysiology of ageing and classically oxidative stress-linked diseases, such as neurodegenerative diseases, diabetes and atherosclerosis (the main cause of cardiovascular complications). Striking evidences implicating LPO in foetal vascular dysfunction occurring in pre-eclampsia, in renal and liver diseases, as well as their role as cause and consequence to cancer development are addressed.

Cellular Dysfunction in Diabetes as Maladaptive Response to Mitochondrial Oxidative Stress

Oxidative stress has been implicated in diabetes long-term complications. In this paper, we summarize the growing evidence suggesting that hyperglycemia-induced overproduction of superoxide by mitochondrial electron transport chain triggers a maladaptive response by affecting several metabolic and signaling pathways involved in the pathophysiology of cellular dysfunction and diabetic complications. In particular, it is our goal to describe physiological mechanisms underlying the mitochondrial free radical production and regulation to explain the oxidative stress derived from a high intracellular glucose concentration and the resulting maladaptive response that leads to a cellular dysfunction and pathological state. Finally, we outline potential therapies for diabetes focused to the prevention of mitochondrial oxidative damage.

Lipidomic and metabolomic analyses reveal potential plasma biomarkers of early atheromatous plaque formation in hamsters

AIMS Atherosclerosis is the main pathological process contributing to cardiovascular disease, with diet being the most important factor involved. Although the lipidome of atheromatous plaque has been studied previously, the use of comparative lipidomics and metabolomics in plasma in early atherogenesis could lead to the discovery of plasma biomarkers that allow not only disease prediction but also measurement of disease progression. METHODS AND RESULTS High-throughput techniques, such as liquid chromatography/mass spectrometry, allowed us to compare the circulating and aortic lipidome and plasma metabolome in order to look for new molecular targets involved in atherogenesis. To achieve this objective, we chose the hamster (Mesocricetus auratus) as the best small animal model for diet-induced early atherosclerosis, because its lipoprotein metabolism is similar to that of humans. The results revealed the existence of several, previously unreported, changes in lipid and amino-acid metabolism, the peroxisome proliferator-activated receptor γ pathway, and oxidative and endoplasmic reticulum stress, also involving cell senescence. Furthermore, as a proof of concept in the modelling of dietary influences in atherogenesis, we have measured the effect of a potential anti-atherogenic polyphenol extract on the reported pathways. Our results support a previously unknown role for taurocholic acid as a potential plasma biomarker of early atheromatous plaque formation. CONCLUSION The use of comparative liquid chromatography/mass spectrometry-based lipidomics and metabolomics allows the discovery of novel pathways in atherogenesis, as well as new potential plasma biomarkers, which could allow us to predict disease in its early stages and measure its progression.

Lipidome analysis in multiple sclerosis reveals protein lipoxidative damage as a potential pathogenic mechanism

Metabolomic and lipidomic analyses have been used for the profiling of neurodegenerative processes, both in targeted and untargeted approaches. In this work we have applied these techniques to the study of CSF samples of multiple sclerosis (MS) patients (n = 9), compared with samples of non‐MS individuals (n = 9) using mass‐spectrometry. We have used western‐blot and analyzed cell culture to confirm pathogenic pathways suggested by mass‐spectrometric measurements. The results of the untargeted approach of metabolomics and lipidomics suggest the existence of several metabolites and lipids discriminating both populations. Applying targeted lipidomic analyses focused to a pathogenic pathway in MS, oxidative stress, reveal that the lipid peroxidation marker 8‐iso‐prostaglandin F2α is increased in CSF from MS patients. Furthermore, as lipid peroxidation exerts its pathogenical effects through protein modification, we studied the incidence of protein lipoxidation, revealing specific increases in carboxymethylated, neuroketal and malondialdehyde‐mediated protein modifications in proteins of CSF from MS patients, despite the absence of their precursors glyoxal and methylglyoxal. Finally, we report that the level of neuroketal‐modified proteins correlated with a hitherto unknown increased amount of autoantibodies against lipid peroxidation‐modified proteins in CSF, without compensation by signaling induced by lipid peroxidation via peroxisome proliferator‐activated receptor γ (PPARγ). The results, despite the limitation of being obtained in a small population, strongly suggest that autoimmunity against in situ produced epitopes derived from lipid peroxidation can be a relevant pathogenic factor in MS.

Multicompartmental LC-Q-TOF-based metabonomics as an exploratory tool to identify novel pathways affected by polyphenol-rich diets in mice.

Metabonomics has recently been used to study the physiological response to a given nutritional intervention, but such studies have usually been restricted to changes in either plasma or urine. In the present study, we demonstrate that the use of LC-Q-TOF-based metabolome analyses (foodstuff, plasma, urine, and caecal content metabolomes) in mice offer higher order information, including intra- and intercompartment relationships. To illustrate this, we performed an intervention study with three different phenolic-rich extracts in mice over 3 weeks. Both unsupervised (PCA) and supervised (PLS-DA) multivariate analyses used for pattern recognition revealed marked effects of diet in each compartment (plasma, urine, and caecal contents). Specifically, dietary intake of phenolic-rich extract affects pathways such as bile acid and taurine metabolism. Q-TOF-based metabonomics demonstrated that the number of correlations is higher in caecal contents and urine than in plasma. Moreover, intercompartment correlations showed that caecal contents-plasma correlations are the most frequent in mice, followed by plasma-urine ones. The number of inter- and intracompartment correlations is significantly affected by diet. These analyses reveal the complexity of interorgan metabolic relationships and their sensitivity to dietary changes.

Dietary antioxidants interfere with Amplex Red-coupled-fluorescence assays.

Oxidation of Amplex Red by hydrogen peroxide in the presence of horseradish peroxidase (HRP) gives rise to an intensely colour product, resorufin. This reaction has been frequently employed for measurements based on enzyme-coupled reactions that detect hydrogen peroxide as a final reaction product. In the current study, we show that the presence of dietary antioxidants at biological concentrations in the reaction medium produced interferences in the Amplex Red/HRP catalyzed reaction that result in an over quantification of the hydrogen peroxide produced. The interference observed showed a dose-dependent manner, and a possible mechanism of interaction of dietary antioxidants with HRP in the Amplex Red-coupled-fluorescent assay is proposed.

Dietary intake of green tea polyphenols regulates insulin sensitivity with an increase in AMP‐activated protein kinase α content and changes in mitochondrial respiratory complexes

SCOPE The intake of food rich in polyphenols is related to a lower incidence in almost all chronic degenerative diseases. However, relatively little is known about the molecular mechanisms involved in its antioxidant properties. The aim of this study was to determine whether the mechanism of action of polyphenols could be related to a modulation in energy uptake and metabolism, and further induced mitochondrial changes. METHODS AND RESULTS For this purpose, male C57BL6 mice were fed during 3 months with a tea-based beverage rich in polyphenols. Insulin sensitivity, tissue oxidative damage biomarkers, as well as energy-related signaling pathways were determined to evaluate its mechanism of action. As a result, a tissue- and protein-specific subtle reduction in oxidative damage was observed. Skeletal muscle showed mitochondrial changes in respiratory complexes and an increase in AMP-activated protein kinase α levels, suggesting reduced energy availability. These changes were also associated with adipose tissue cellular metabolism. This was confirmed by a decline in the potential of energy uptake, evidenced by a diminished intestinal and systemic absorption of carbohydrates together with an inhibition of insulin sensitivity. CONCLUSIONS Our results suggest that the mechanisms of action of green tea polyphenols may be related to their ability to modulate energy uptake leading to mitochondrial adaptations possibly responsible for the changes in protein oxidative damage.

Biofortification of crops with nutrients: factors affecting utilization and storage

Biofortification is an effective and economical method to improve the micronutrient content of crops, particularly staples that sustain human populations in developing countries. Whereas conventional fortification requires artificial additives, biofortification involves the synthesis or accumulation of nutrients by plants at source. Little is known about the relative merits of biofortification and artificial fortification in terms of nutrient bioaccessibility and bioavailability, and much depends on the biochemical nature of the nutrient, which can promote or delay uptake, and determine how efficiently different nutrients are transported through the blood, stored, and utilized. Data from the first plants biofortified with minerals and vitamins provide evidence that the way in which nutrients are presented can affect how they are processed and utilized in the human body. The latest studies on the effects of the food matrix, processing and storage on nutrient transfer from biofortified crops are reviewed, as well as current knowledge about nutrient absorption and utilization.

Effects of consuming diets containing Agave tequilana dietary fibre and jamaica calyces on body weight gain and redox status in hypercholesterolemic rats.

Dietary fibre (DF) obtained from Agave tequilana, which is rich in fructans and insoluble DF, and jamaica calyces (Hibiscus sabdariffa), which is rich in DF and phenolic compounds, were assessed as new potential functional ingredients using the hypercholesterolemic animal model. Wistar rats (200-250 g) were divided into 3 groups (n=8) and fed with cholesterol-rich diets supplemented with cellulose (CC, control), agave DF (ADF) or ADF with jamaica calyces (ADF-JC). After consuming the test diets for 5 weeks, weight gain in the ADF-JC group was significantly lower than in the other groups. The ADF and ADF-JC groups had a reduced concentration of cholesterol transporters in the caecum tissue, although no changes were observed in the plasma lipid profile. Both treatments improved the redox status by reducing the malondialdehyde serum levels and protein oxidative damage, compared to the CC group. DF from A. tequilana alone, or in combination with jamaica calyces, shows promising potential as a bioactive ingredient.

The distribution of carotenoids in hens fed on biofortified maize is influenced by feed composition, absorption, resource allocation and storage

Carotenoids are important dietary nutrients with health-promoting effects. The biofortification of staple foods with carotenoids provides an efficient delivery strategy but little is known about the fate and distribution of carotenoids supplied in this manner. The chicken provides a good model of human carotenoid metabolism so we supplemented the diets of laying hens using two biofortified maize varieties with distinct carotenoid profiles and compared the fate of the different carotenoids in terms of distribution in the feed, the hen’s livers and the eggs. We found that after a period of depletion, pro-vitamin A (PVA) carotenoids were preferentially diverted to the liver and relatively depleted in the eggs, whereas other carotenoids were transported to the eggs even when the liver remained depleted. When retinol was included in the diet, it accumulated more in the eggs than the livers, whereas PVA carotenoids showed the opposite profile. Our data suggest that a transport nexus from the intestinal lumen to the eggs introduces bottlenecks that cause chemically-distinct classes of carotenoids to be partitioned in different ways. This nexus model will allow us to optimize animal feed and human diets to ensure that the health benefits of carotenoids are delivered in the most effective manner.