Oxidation products of polyunsaturated fatty acids in infant formulas compared to human milk--a preliminary study

Unveiling thioacetamide-induced toxicity: Multi-organ damage and omitted bone toxicity

Thioacetamide (TAA), a widely employed hepatotoxic substance, has gained significant traction in the induction of liver failure disease models. Upon administration of TAA to experimental animals, the production of potent oxidative derivatives ensues, culminating in the activation of oxidative stress and subsequent infliction of severe damage upon multiple organs via dissemination through the bloodstream. This review summarized the various organ damages and corresponding mechanistic explanations observed in previous studies using TAA in toxicological animal experiments. The principal pathological consequences arising from TAA exposure encompass oxidative stress, inflammation, lipid peroxidation, fibrosis, apoptosis induction, DNA damage, and osteoclast formation. Recent in vivo and in vitro studies on TAA bone toxicity have confirmed that long-term high-dose use of TAA not only induces liver damage in experimental animals but also accompanies bone damage, which was neglected for a long time. By using TAA to model diseases in experimental animals and controlling TAA dosage, duration of use, and animal exposure environment, we can induce various organ injury models. It should be noted that TAA-induced injuries have a time-dependent effect. Finally, in our daily lives, especially for researchers, we should take precautions to minimize TAA exposure and reduce the probability of related organ injuries.

The Gestational Pathologies Effect on the Human Milk Redox Homeostasis: A First Step towards Its Definition

BACKGROUND

Human Milk (HM) is a dynamic nourishment; its composition is influenced by several conditions such as gestational age, maternal diet and ethnicity. It appears important to evaluate the impact that gestational pathologies have on HM components and if their presence, as a source of oxidative stress in the mother, influence milk's redox homeostasis. To assess the effect of Preeclampsia (PE) and Gestational Diabetes Mellitus (GDM) on some aspects of human milk redox homeostasis, we chose to investigate both oxidative and antioxidant aspects, with, respectively, Lipid hydroperoxides (LOOHs) and Glutathione (GSH).

METHODS

Women with PE, GDM and who were healthy were recruited for this study. Colostrum, transitional and mature milk samples were collected. GSH and LOOHs levels were measured using a spectrophotometric test. To investigate the effect of pathology on redox homeostasis, a mixed linear model with unistructural covariance structure was performed.

RESULTS

A total of 120 mothers were recruited. The GSH concentration results were significantly lower in GDM women than in healthy women only in colostrum (p < 0.01). No other differences emerged. LOOHs was not detectable in almost all the samples.

DISCUSSION

Our study is the first to extensively evaluate these components in the HM of women with these gestational pathologies. The main observation is that GDM can alter the GSH level of HM, mainly in colostrum.

Beyond ingredients: Supramolecular structure of lipid droplets in infant formula affects metabolic and brain function in mouse models

Human milk beneficially affects infant growth and brain development. The supramolecular structure of lipid globules in human milk i.e., large lipid globules covered by the milk fat globule membrane, is believed to contribute to this effect, in addition to the supply of functional ingredients. Three preclinical (mouse) experiments were performed to study the effects of infant formula mimicking the supramolecular structure of human milk lipid globules on brain and metabolic health outcomes. From postnatal day 16 to 42, mouse offspring were exposed to a diet containing infant formula with large, phospholipid-coated lipid droplets (structure, STR) or infant formula with the same ingredients but lacking the unique structural properties as observed in human milk (ingredient, ING). Subsequently, in Study 1, the fatty acid composition in liver and brain membranes was measured, and expression of hippocampal molecular markers were analyzed. In Study 2 and 3 adult (Western-style diet-induced) body fat accumulation and cognitive function were evaluated. Animals exposed to STR compared to ING showed improved omega-3 fatty acid accumulation in liver and brain, and higher expression of brain myelin-associated glycoprotein. Early exposure to STR reduced fat mass accumulation in adulthood; the effect was more pronounced in animals exposed to a Western-style diet. Additionally, mice exposed to STR demonstrated better memory performance later in life. In conclusion, early life exposure to infant formula containing large, phospholipid-coated lipid droplets, that are closer to the supramolecular structure of lipid globules in human milk, positively affects adult brain and metabolic health outcomes in pre-clinical animal models.

Response of the Glutathione (GSH) Antioxidant Defense System to Oxidative Injury in Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a neonatal intestinal disease associated with oxidative stress. The targets of peroxidation and the role of the innate intestinal epithelial antioxidant defense system are ill-defined. We hypothesized that oxidative stress in NEC correlates with oxidized GSH redox potentials, lipid peroxidation, and a dysfunctional antioxidant system. Methods: Intestinal samples from infants +/- NEC were generated into enteroids and incubated with lipopolysaccharide (LPS) and hypoxia to induce experimental NEC. HPLC assayed GSH redox potentials. Lipid peroxidation was measured by flow cytometry. Immunoblotting measured glutathione peroxidase 4 (Gpx4) expression. Results: GSH redox potentials were more oxidized in NEC intestinal tissue and enteroids as compared to controls. Lipid radicals in NEC-induced enteroids were significantly increased. Human intestinal tissue with active NEC and treated enteroid cultures revealed decreased levels of Gpx4. Conclusions: The ability of neonatal intestine to mitigate radical accumulation plays a role in its capacity to overcome oxidative stress. Accumulation of lipid radicals is confirmed after treatment of enteroids with NEC-triggering stimuli. Decreased Gpx4 diminishes a cell's ability to effectively neutralize lipid radicals. When lipid peroxidation overwhelms antioxidant machinery, cellular death ensues. Identification of the mechanisms behind GSH-dependent enzyme dysfunction in NEC may provide insights into strategies for reversing radical damage.

Role of ferroptosis in pregnancy related diseases and its therapeutic potential

Ferroptosis is a form of regulated cell death characterized by iron overload, overwhelming lipid peroxidation, and disruption of antioxidant systems. Emerging evidence suggests that ferroptosis is associated with pregnancy related diseases, such as spontaneous abortion, pre-eclampsia, gestational diabetes mellitus, intrahepatic cholestasis of pregnancy, and spontaneous preterm birth. According to these findings, inhibiting ferroptosis might be a potential option to treat pregnancy related diseases. This review summarizes the mechanisms and advances of ferroptosis, the pathogenic role of ferroptosis in pregnancy related diseases and the potential medicines for its treatment.

Ferroptosis in glioma treatment: Current situation, prospects and drug applications

Ferroptosis is a regulatory form of iron-dependent cell death caused by the accumulation of lipid-based reactive oxygen species (ROS) and differs from apoptosis, pyroptosis, and necrosis. Especially in neoplastic diseases, the susceptibility of tumor cells to ferroptosis affects prognosis and is associated with complex effects. Gliomas are the most common primary intracranial tumors, accounting for disease in 81% of patients with malignant brain tumors. An increasing number of studies have revealed the particular characteristics of iron metabolism in glioma cells. Therefore, agents that target a wide range of molecules involved in ferroptosis may regulate this process and enhance glioma treatment. Here, we review the underlying mechanisms of ferroptosis and summarize the potential therapeutic options for targeting ferroptosis in glioma.

Prolonged refrigeration does not alter isoprostanes concentration in human milk

BACKGROUND

The Academy of Breastfeeding Medicine published a clinical protocol for Human Milk storage, recommending refrigeration at a temperature of 4 °C up to 4 d as the optimal conditions for the safety and bactericidal capacity of Human Milk. However, few studies were conducted to evaluate the change in milk composition during this type of refrigeration storage.

AIM

To elucidate some uncertainties regarding the Human Milk composition and prolonged cold storage, we have investigated the effects of storage at 4 °C up to 96 h on an important category of oxidative stress markers: the Isoprostanes (F2-isoprostanes, F4-neuroprostanes and F3-isoprostanes).

MATERIAL AND METHOD

The experiment was repeated 3 times to ensure reproducibility of the results. We enrolled 3 donating healthy mothers for each time (total: 9 mothers). Milk was collected with standard extraction methods. Immediately after collection, each Human Milk sample from each mother was pooled and then divided into 5 aliquots. One aliquot (0 h) was immediately frozen at -80 °C until the analysis. The other aliquots (24 h, 48 h, 72 h, 96 h) were stored in a refrigerator at 4 °C respectively for 24, 48, 72 and 96 h, then immediately frozen at -80 °C until the analysis. Milk samples were then used to determine concentration of Isoprostanes in Liquid Chromatography - Mass Spectrometry and Liquid Chromatography - Tandem Mass Spectrometry.

RESULTS

Isoprostanes were detectable in all Human Milk samples. There was no significant trend of the concentration of the tested analytes over time.

DISCUSSION AND CONCLUSION

This study provides evidence of the presence in human milk of all the tested isoprostanes: in particular, F2-isoprostanes, F4-neuroprostanes and F3-isoprostanes. Refrigeration and storage of fresh Human Milk in controlled conditions for 96 h did not significantly affect its bioactivity and nutritional quality related with these biomarkers.

Lipid profiling and dietary assessment of infant formulas reveal high intakes of major cholesterol oxidative product (7-ketocholesterol)

Approximately two-thirds of US infants receive infant formula (IF) as a primary or sole nutritional source during the first six months of life. IF is available in a variety of commercial presentations; from a manufacturing standpoint, they can be categorized as powder- (PIF) or liquid- (LIF) based formulations. Thirty commercial IFs were analyzed in their oxidative and non-oxidative lipid profiles. We identified 7-ketocholesterol - a major end-product of cholesterol oxidation - as a potential biomarker of IF manufacturing. The statistical analysis allowed a re-classification of IF based on their metabolomic fingerprint, resulting in three groups assigned with low-to-high oxidative status. Finally, we modeled the dietary intake of cholesterol, sterols, and 7-ketocholesterol in the first year of life. The database provided in this study will be instrumental for scientists interested in infant nutrition, to establish bases for epidemiological studies aimed to find connections between nutrition and diet-associated diseases, such as sitosterolemia.

Luminescence imaging of leaf damage induced by lipid peroxidation products and its modulation by β-cyclocitral

Lipid peroxidation is a primary event associated with oxidative stress in plants. This phenomenon secondarily generates bioactive and/or toxic compounds such as reactive carbonyl species (RCS), phytoprostanes, and phytofurans, as confirmed here in Arabidopsis plants exposed to photo-oxidative stress conditions. We analyzed the effects of exogenous applications of secondary lipid oxidation products on Arabidopsis plants by luminescence techniques. Oxidative damage to attached leaves was measured by autoluminescence imaging, using a highly sensitive CCD camera, and the activity of the detoxification pathway, dependent on the transcription regulator SCARECROW-LIKE 14 (SCL14), was monitored with a bioluminescent line expressing the firefly LUCIFERASE (LUC) gene under the control of the ALKENAL REDUCTASE (AER) gene promoter. We identified 4-hydroxynonenal (HNE), and to a lesser extent 4-hydroxyhexenal (HHE), as highly reactive compounds that are harmful to leaves and can trigger AER gene expression, contrary to other RCS (pentenal, hexenal) and to isoprostanoids. Although the levels of HNE and other RCS were enhanced in the SCL14-deficient mutant (scl14), exogenously applied HNE was similarly damaging to this mutant, its wild-type parent and a SCL14-overexpressing transgenic line (OE:SCL14). However, strongly boosting the SCL14 detoxification pathway and AER expression by a pre-treatment of OE:SCL14 with the signaling apocarotenoid β-cyclocitral canceled the damaging effects of HNE. Conversely, in the scl14 mutant, the effects of β-cyclocitral and HNE were additive, leading to enhanced leaf damage. These results indicate that the cellular detoxification pathway induced by the low-toxicity β-cyclocitral targets highly toxic compounds produced during lipid peroxidation, reminiscent of a safener-type mode of action.

Effects of storage practices on long-chain polyunsaturated fatty acids and lipid peroxidation of preterm formula milk

BACKGROUND

Preterm formula milk (FM) is often prepared in advance, potentially affecting nutritional quality. Long-chain polyunsaturated fatty acids (LCPUFAs), important for brain and immune system function, are prone to lipid peroxidation, which correlates with comorbidities of prematurity. The effects of clinical storage practices on LCPUFA content and lipid peroxidation of preterm FM were investigated.

METHODS

UK liquid and powder preterm FM (2017) (from two manufacturers) were subjected to routine storage conditions (liquid: refrigeration ≤10 h; powder: weekly preparation in accordance with the manufacturer's instructions and refrigeration ≤24 h for 4 weeks). LCPUFA content, thiobarbituric acid reactive substances and 4-hydroxy-2-nonenal (HNE) content were analysed.

RESULTS

Storage did not significantly decrease LCPUFA content. The European Society for Paediatric Gastroenterology, Hepatology and Nutrition recommended LCPUFA intake, whereas in utero accretion rates could not be achieved with both FM brands (liquid and powder). Lipid peroxidation was evident on opening, with 6× higher levels in powder. No effect of ≤10-h refrigeration on peroxidation was seen in liquid FM. In powder FM, it increased over refrigeration (HNE opening: 6.5-9.7 µg mL^-1 versus day 28, 24 h: 16.6-36.5 µg mL^-1 ) with a significant interaction between storage time and refrigeration (P = 0.015), with higher HNE at 4 h on days 0, 7, 14 and 21 (all P < 0.05).

CONCLUSIONS

The results suggest that preterm FM and storage conditions do not support in utero accretion rates for LCPUFAs. Although the results suggest different susceptibility of liquid and powder FM to peroxidation upon refrigeration, they are too preliminary to make specific recommendations. We suggest minimising storage time of fresh and prepared powder FM, wherever possible.

4-hydroxy-2-alkenals in foods: a review on risk assessment, analytical methods, formation, occurrence, mitigation and future challenges

Undoubtedly, significant advances were performed concerning 4-hydroxy-2-alkenals research on foods, and their formation by double oxidation of polyunsaturated fatty acids. But further studies are still needed, especially on their occurrence in foods enriched with n-3 and n-6 fatty acids, as well as in foods for infants and processed foods. Major factors concerning the formation of 4-hydroxy-2-alkenals were discussed, namely the influence of fatty acids composition, time/temperature, processing conditions, salt, among others. Regarding mitigation, the most effective strategies are adding phenolic extracts to foods matrices, as well as other antioxidants, such as vitamin E. Exposure assessment studies revealed 4-hydroxy-2-alkenals values that could not be considered a risk for human health. However, these toxic compounds remain unaltered after digestion and can easily reach the systemic circulation. Therefore, it is crucial to develop in vivo research, with the inclusion of the colon phase, as well as, cell membranes of the intestinal epithelium. In conclusion, according to our review it is possible to eliminate or effectively decrease 4-hydroxy-2-alkenals in foods using simple and economic practices.

Lipid Peroxide-Derived Reactive Carbonyl Species as Mediators of Oxidative Stress and Signaling

Oxidation of membrane lipids by reactive oxygen species (ROS) or O₂/lipoxygenase leads to the formation of various bioactive compounds collectively called oxylipins. Reactive carbonyl species (RCS) are a group of oxylipins that have the α,β-unsaturated carbonyl structure, including acrolein and 4-hydroxy-(E)-2-nonenal. RCS provides a missing link between ROS stimuli and cellular responses in plants via their electrophilic modification of proteins. The physiological significance of RCS in plants has been established based on the observations that the RCS-scavenging enzymes that are overexpressed in plants or the RCS-scavenging chemicals added to plants suppress the plants' responses to ROS, i.e., photoinhibition, aluminum-induced root damage, programmed cell death (PCD), senescence, abscisic acid-induced stomata closure, and auxin-induced lateral root formation. The functions of RCS are thus a key to ROS- and redox-signaling in plants. The chemical species involved in distinct RCS signaling/damaging phenomena were recently revealed, based on comprehensive carbonyl determinations. This review presents an overview of the current status of research regarding RCS signaling functions in plants and discusses present challenges for gaining a more complete understanding of the signaling mechanisms.

Two Toxic Lipid Aldehydes, 4-hydroxy-2-hexenal (4-HHE) and 4-hydroxy-2-nonenal (4-HNE), Accumulate in Patients with Chronic Kidney Disease

Lipid aldehydes originating from the peroxidation of n-3 and n-6 polyunsaturated fatty acids are increased in hemodialysis (HD) patients, a process already known to promote oxidative stress. However, data are lacking for patients with chronic kidney disease (CKD) before the initiation of HD. We prospectively evaluated the changes of plasma concentrations of two major lipid aldehydes, 4-HHE and 4-HNE, according to the decrease of glomerular filtration rate (GFR) in 40 CKD and 13 non-CKD participants. GFR was measured by inulin or iohexol clearance. Thus, 4-hydroxy-2-nonenal (4-HNE) and 4-hydroxy-2-hexenal (4-HHE) were quantitated in plasma by gas chromatography coupled with mass spectrometry and their covalent adducts on proteins were quantified by immunoblotting. On the one hand, 4-HHE plasma concentration increased from CKD stage I–II to CKD stage IV–V compared to non-CKD patients (4.5-fold higher in CKD IV–V, p < 0.005). On the other hand, 4-HNE concentration only increased in CKD stage IV–V patients (6.2-fold, p < 0.005). The amount of covalent adducts of 4-HHE on plasma protein was 9.5-fold higher in CKD patients than in controls (p < 0.005), while no difference was observed for 4-HNE protein adducts. Plasma concentrations of 4-HNE and 4-HHE are increased in CKD IV–V patients before the initiation of hemodialysis.

Relationship between redox potential of glutathione and DNA methylation level in liver of newborn guinea pigs

The metabolism of DNA methylation is reported to be sensitive to oxidant molecules or oxidative stress. Hypothesis: early-life oxidative stress characterized by the redox potential of glutathione influences the DNA methylation level. The in vivo study aimed at the impact of modulating redox potential of glutathione on DNA methylation. Newborn guinea pigs received different nutritive modalities for 4 days: oral nutrition, parenteral nutrition including lipid emulsion Intralipid (PN-IL) or SMOFLipid (PN-SF), protected or not from ambient light. Livers were collected for biochemical determinations. Redox potential (p < 0.001) and DNA methylation (p < 0.01) were higher in PN-infused animals and even higher in PN-SF. Their positive correlation was significant (r² = 0.51; p < 0.001). Methylation activity was higher in PN groups (p < 0.01). Protein levels of DNA methyltransferase (DNMT)-1 were lower in PN groups (p < 0.01) while those of both DNMT3a isoforms were increased (p < 0.01) and significantly correlated with redox potential (r² > 0.42; p < 0.001). The ratio of SAM (substrate) to SAH (inhibitor) was positively correlated with the redox potential (r² = 0.36; p < 0.001). In conclusion, early in life, the redox potential value strongly influences the DNA methylation metabolism, resulting in an increase of DNA methylation as a function of increased oxidative stress. These results support the notion that early-life oxidative stress can reprogram the metabolism epigenetically. This study emphasizes once again the importance of improving the quality of parenteral nutrition solutions administered early in life, especially to newborn infants.

Abbreviation of Title: Parenteral nutrition and DNA methylation

Long-Chain Polyunsaturated Fatty Acids and Lipid Peroxidation Products in Donor Human Milk in the United Kingdom: Results From the LIMIT 2-Centre Cross-Sectional Study

BACKGROUND

Donor human milk (DHM) is used as alternative to maternal milk to feed preterm infants; however, it may provide less long-chain (LC) polyunsaturated fatty acids (PUFAs) and more oxidized lipids, which may be detrimental to preterm infant health and development. Levels have not been reported for DHM in the United Kingdom.

METHODS

DHM (n = 19) from 2 neonatal units, preterm milk from a neonatal unit (n = 10), and term milk from the community (n = 11) were analyzed for fatty acids, malondialdehyde, 4-hydroxy-2-nonenal, and hexanal.

STUDY REGISTRATION

NCT03573531.

RESULTS

DHM had significantly lower absolute LCPUFA content than term (P < .001) and significantly lower ω-3 PUFAs than preterm milk (P < .05), although relative LCPUFA composition did not differ. Exclusive DHM feeding leads to significantly lower fat (3.7 vs 6.7 g/d) and LCPUFA (docosahexaenoic acid [DHA]: 10.6 vs 16.8 mg/d; arachidonic acid [ARA]: 17.4 vs 25.2 mg/d) intake than recommended by the European Society for Pediatric Gastroenterology, Hepatology and Nutrition, and provides 17.3% and 43.1% of the in utero accreted ARA and DHA. DHM had the highest proportion of lipid peroxidation.

CONCLUSIONS

This study confirms that DHM in the United Kingdom has insufficient LCPUFAs for preterm infants. It demonstrates for the first time that DHM has the highest level of lipid peroxidation, compared with preterm or term milk. This has important implications for preterm infant nutrition, as exclusive DHM feeding might not be suitable long term and may contribute to the development of major preterm neonatal morbidities.

Reactive Oxygen Species-Induced Lipid Peroxidation in Apoptosis, Autophagy, and Ferroptosis

Reactive oxygen species- (ROS-) induced lipid peroxidation plays a critical role in cell death including apoptosis, autophagy, and ferroptosis. This fundamental and conserved mechanism is based on an excess of ROS which attacks biomembranes, propagates lipid peroxidation chain reactions, and subsequently induces different types of cell death. A highly evolved sophisticated antioxidant system exists that acts to protect the cells from oxidative damage. In this review, we discussed how ROS propagate lipid peroxidation chain reactions and how the products of lipid peroxidation initiate apoptosis and autophagy in current models. We also discussed the mechanism of lipid peroxidation during ferroptosis, and we summarized lipid peroxidation in pathological conditions of critical illness. We aim to bring a more global and integrative sight to know how different ROS-induced lipid peroxidation occurs among apoptosis, autophagy, and ferroptosis.

The effects of storage conditions on long-chain polyunsaturated fatty acids, lipid mediators, and antioxidants in donor human milk - A review

Donor human milk (DHM) is the recommended alternative, if maternal milk is unavailable. However, current human milk banking practices may negatively affect the nutritional quality of DHM. This review summarises the effects of these practices on polyunsaturated fatty acids, lipid mediators and antioxidants of human milk. Overall, there is considerable variation in the reported effects, and further research is needed, particularly with lipid mediators and antioxidants. However, to preserve nutritional quality, DHM should be protected from light exposure and storage at 4 °C minimised, to prevent decreases in vitamin C and endocannabinoids and increases in free fatty acids and lipid peroxidation products. Storage at -20 °C prior to pasteurisation should also be minimised, to prevent free fatty increases and total fat and endocannabinoid decreases. Storage ≤-70 °C is preferable wherever possible, although post-pasteurisation storage at -20 °C for three months appears safe for free fatty acids, lipid peroxidation products, and total fat content.

Antioxidant activity of milk and polyphenol-rich beverages during simulated gastrointestinal digestion of linseed oil emulsions

Polyunsaturated fatty acids (PUFA) are associated with health benefits. However, high PUFA intake increases the risk of lipid oxidation and formation of potentially toxic lipid oxidation species. The objective of this study was to determine the antioxidant activity of milk fractions (whole milk, skim milk, acid whey, ultrafiltration (UF) permeate) and polyphenol-rich beverages (green tea, grape juice) during simulated gastrointestinal digestion. We also determined the effect of milk and polyphenol-rich beverages on the formation of advanced oxidation species during in vitro digestion of PUFA-rich emulsion. Antioxidant activity during digestion of milk fractions emphasized the important role of proteins (more specifically caseins) and the contribution of fat to the antioxidant capacity of milk. In comparison to milk, the antioxidant activity of polyphenol-rich beverages was at least four times higher. During digestion of a PUFA-rich emulsion, the formation of 4-hydroxyhexanal (4-HHE) and 4-hydroxynonenal (4-HNE) in the intestinal phase were respectively reduced by 60% and 75%, in the presence of milk or polyphenol-rich beverages. Further reduction was observed when the emulsion was co-digested with both, milk and polyphenol-rich beverages (89% for 4-HHE and 93% for 4-HNE). These results suggest that the combination of milk and polyphenol-rich beverages increases the antioxidant activity and synergistically reduces the formation of toxic lipid oxidation species during simulated digestion of PUFA-rich foods.

A nanoencapsulation suspension biomimetic of milk structure for enhanced maternal and fetal absorptions of DHA to improve early brain development

Docosahexaenoic acid (DHA) is one ω-3 fatty acid that is essential for the development and function of the brain. However, a large number of clinical trials found that the DHA supplementation showed no advantage on mental and motor skill development in term infants. A strategy based on DHA nanoencapsulation (nano FO) using an edible plant protein, zein, mimicking the milk structure is applied for enhanced maternal and fetal absorptions of DHA to improve early brain development. The nano FO achieved increased absorption in GI tract, enhanced delivery to the maternal, fetal, and offspring brains, and reduced fatty acid accumulation in the fetal liver. In the behavior assessments, the nano FO diet showed enhanced learning and memory improvement compared to the normal FO diet. It indicated that zein nanoencapsulation is with high potential for drug and nutrient deliveries to brain and through placenta to fetus with no toxicity concern.

Donor Human Milk: Effects of Storage and Heat Treatment on Oxidative Stress Markers

Mother's own milk is the first choice for the feeding and nutrition of preterm and term newborns. When mother's own milk is unavailable or in short supply donor human milk (DM) could represent a solution. Heat treatment and cold storage are common practices in Human Milk Banks (HMBs). Currently, Holder pasteurization process is the recommended heat treatment in all international guidelines. This method is thought to lead to a good compromise between the microbiological safety and nutritional/biological quality of DM. Moreover, storage of refrigerated milk is a common practice in HMBs and in NICUs. Depending on the length and on the type of storage, human milk may lose some important nutritional and functional properties. The available data on oxidative stress markers confirm that pasteurization and refrigeration affected this important elements to variable degrees, even though it is rather difficult to quantify the level of deterioration. Nonetheless, clinical practice demonstrates that many beneficial properties of human milk are preserved, even after cold storage and heat treatment. Future studies should be focused on the evaluation of new pasteurization techniques, in order to achieve a better compromise between biological quality and safety of DM.

Skeletal muscle insulin resistance is induced by 4-hydroxy-2-hexenal, a by-product of n-3 fatty acid peroxidation

AIMS/HYPOTHESIS

Oxidative stress is involved in the pathophysiology of insulin resistance and its progression towards type 2 diabetes. The peroxidation of n-3 polyunsaturated fatty acids produces 4-hydroxy-2-hexenal (4-HHE), a lipid aldehyde with potent electrophilic properties able to interfere with many pathophysiological processes. The aim of the present study was to investigate the role of 4-HHE in the development of insulin resistance.

METHODS

4-HHE concentration was measured in plasma from humans and rats by GC-MS. Insulin resistance was estimated in healthy rats after administration of 4-HHE using hyperinsulinaemic-euglycaemic clamps. In muscle cells, glucose uptake was measured using 2-deoxy-D-glucose and signalling pathways were investigated by western blotting. Intracellular glutathione was measured using a fluorimetric assay kit and boosted using 1,2-dithiole-3-thione (D3T).

RESULTS

Circulating levels of 4-HHE in type 2 diabetic humans and a rat model of diabetes (obese Zucker diabetic fatty rats), were twice those in their non-diabetic counterparts (33 vs 14 nmol/l, p < 0.001), and positively correlated with blood glucose levels. During hyperinsulinaemic-euglycaemic clamps in rats, acute intravenous injection of 4-HHE significantly altered whole-body insulin sensitivity and decreased glucose infusion rate (24.2 vs 9.9 mg kg^-1 min^-1, p < 0.001). In vitro, 4-HHE impaired insulin-stimulated glucose uptake and signalling (protein kinase B/Akt and IRS1) in L6 muscle cells. Insulin-induced glucose uptake was reduced from 186 to 141.9 pmol mg^-1 min^-1 (p < 0.05). 4-HHE induced carbonylation of cell proteins and reduced glutathione concentration from 6.3 to 4.5 nmol/mg protein. Increasing intracellular glutathione pools using D3T prevented 4-HHE-induced carbonyl stress and insulin resistance.

CONCLUSIONS/INTERPRETATION

4-HHE is produced in type 2 diabetic humans and Zucker diabetic fatty rats and blunts insulin action in skeletal muscle. 4-HHE therefore plays a causal role in the pathophysiology of type 2 diabetes and might constitute a potential therapeutic target to taper oxidative stress-induced insulin resistance.

Markers of Oxidative Stress in Human Milk do not Differ by Maternal BMI But are Related to Infant Growth Trajectories

Objective Obesity in adults is associated with inflammation and oxidative stress. Whether or not this phenotype is reflected in human milk (HM) composition, or may impact infant growth remains unknown. We investigated whether HM from overweight/obese (OW/Ob) mothers exhibited higher concentrations of inflammatory cytokines and markers of oxidative stress. We also correlated these bioactive components with infant growth patterns. Methods This was an observational cohort of 56 breastfeeding mothers and their infants [33 normal weight (NW) and 23 OW/Ob]. Infants were followed until 6 months of age and HM collected at 2-weeks and 4-months. Results Markers of oxidative stress, 8-hydroxy-deoxyguanosine (8OHdG) and 4-hydroxynonenol (HNE), decreased in HM over time (p < 0.001) and did not differ between NW and OW/Ob women. Concentrations of inflammatory cytokines, IL-6, IL-8, and TNF-α, were all inter-correlated (p < 0.001) but did not differ between NW and OW/Ob women. HM fat, protein, lactose, and total calories did not differ between NW and OW/Ob women. Infant growth patterns did not differ by group. In a model of infant weight-for-length-Z score trajectory, there was a significant interaction between both lactose and 8OHdG with maternal group: HM lactose and 8OHdG concentrations were both positively associated with increases in WLZ trajectory only among infants breastfed by OW/Ob mothers. Conclusions for Practice HM composition was relatively stable between NW and OW/Ob women. In exclusively breastfed infants, HM concentrations of lactose and 8OHdG, a marker of oxidative stress, may contribute to regulation of infant weight gain, especially among infants of OW/Ob women.

Mutagenicity of ω-3 fatty acid peroxidation products in the Ames test

Polyunsaturated fatty acids (PUFA) represent one of the main building blocks of cellular membranes and their varying composition impacts lifespan as well as susceptibility to cancer and other degenerative diseases. Increased intake of ω-3 PUFA is taught to compensate for the abundance of ω-6 PUFA in modern human diet and prevent cardiocirculatory diseases. However, highly unsaturated PUFA of marine and seed origin easily oxidize to aldehydic products which form DNA adducts. With increased PUFA consumption it is prudent to re-evaluate ω-3 PUFA safety and the genotoxic hazards of their metabolites. We have used the standard Ames test to examine the mutagenicity of 2 hexenals derived from lipid peroxidation of the common ω-3 PUFA in human diet and tissues. Both 4-hydroxyhexenal and 2-hexenal derived from the ω-3 docosahexaenoic and α-linolenic acid, respectively, induced base substitutions in the TA104 and TA100 Ames strains in a dose dependent manner. Their mutagenicity was dependent on the Y-family DNA polymerase RI and they did not induce other types of mutations such as the -2 and -1 frameshifts in the TA98 and TA97 strains. Our results expand previous findings about the mutagenicity of related ω-3 peroxidation product 4-oxohexenal and raise alert that overuse of ω-3 rich oils may have adverse effect on genome stability.

Milk fat globule membrane coating of large lipid droplets in the diet of young mice prevents body fat accumulation in adulthood

Epidemiological studies have demonstrated protective effects of breast-feeding on childhood obesity. Differences between human milk and infant milk formula (IMF) in dietary lipid structure may contribute to this effect. In our mouse model, feeding a diet containing large lipid droplets coated with phospholipids (PL) (Nuturis^®; PL of milk fat globule membrane (MFGM) fraction origin) in early life protected against excessive body fat accumulation following a diet challenge in adult life. We now set out to determine the relevance of increased droplet size and/or MFGM lipid droplet coating to the observed anti-obesogenic effects in adult life. From day 16 to 42, male mouse pups were exposed to diets with small (S) or large (L) lipid droplets (0·3 v. 2·9 µm average mode diameter, respectively), either without MFGM or with MFGM coating around the lipid droplet, resulting in four groups: S (control diet), L, S^coating and L^coating (Nuturis^® IMF diet). Mice were subsequently challenged with a Western-style diet until dissection at postnatal day 98. A non-challenged group served as reference (REF). We repeatedly determined body composition between postnatal day 42 and 98. At day 98 plasma and gene expression measurements were performed. Only the Nuturis^® IMF diet (L^coating) in early life containing MFGM-coated large lipid droplets reduced body fat mass to a level comparable with the REF group. These data support the notion that the structural aspects of lipids in human milk, for example, both lipid droplet size as well as the MFGM coating, may contribute to its reported protective effect against obesity in later life.

Nitrite and catalase levels rule oxidative stability and safety properties of milk: a review

This review focuses on recent evidence showing that various types of udder inflammation (mastitis) are associated with increased concentration of NO˙-derived metabolites, nitrite and nitrate, and oxidatively modified organic components under commercial farming and experimental conditions.

N-3 fatty acid enriched eggs and production of egg yolk powders: an increased risk of lipid oxidation?

Lipid oxidation is generally favoured by thermal processing and long-term storage. Oxidised lipids can alter nutritional and sensorial properties of foods. As eggs are widely used in food industries in dried powder form, our aim was to determine whether compositional or processing parameters have an impact on lipid oxidation from the shell eggs up to the dried powders and subsequent storage. Two batches of shell eggs were processed: one issued from hens fed with a standard diet and another receiving a diet enriched in extruded linseed, rich in linolenic acid. The extent of lipid oxidation was evaluated by quantification of conjugated dienes (CD) and malondialdehyde (MDA), but also by assessment of tocopherols, lutein and zeaxanthin losses. Results highlighted the remarkable oxidative stability of control and enriched yolk powders as revealed by a moderate increase of the quantities of CD and MDA, the lack of oxidised cholesterol and small loss of α-tocopherol.

Investigating the effect of black tea consumption during pregnancy on the oxidant/antioxidant status of breastmilk

OBJECTIVE

Black tea is associated with antioxidant properties. The objective of this study was to investigate the effect of the amount of black tea consumption during pregnancy on the oxidant/antioxidant status of breastmilk.

SUBJECTS AND METHODS

Breastmilk was obtained from 30 mothers and analyzed for lipid peroxidation based on levels of malondialdehyde (MDA) and of reduced glutathione (GSH). In a survey completed by all participants, daily black tea consumption during the pregnancy was reported.

RESULTS

No correlation was found between the amount of black tea consumed and levels of MDA (p=0.401) and/or GSH (p=0.473). The results of this study indicate that consumption of varying amounts of black tea does not affect the oxidant/antioxidant status of breastmilk.

CONCLUSIONS

The insensitivity of breastmilk to antioxidant contributions by black tea reflects the capacity of breastmilk to be resistant to the myriad of factors that otherwise affect a pregnant woman.

Effect of prolonged refrigeration on the lipid profile, lipase activity, and oxidative status of human milk

OBJECTIVE

The study was aimed at evaluating the effect of prolonged refrigeration of fresh human milk (HM) on its fatty acid profile, free fatty acid content, lipase activities, and oxidative status.

METHODS

HM from mothers of preterm newborns was collected, pooled, and placed in the neonatal intensive care unit (NICU) refrigerator. Pooled milk was aliquoted and analyzed within 3 hours of collection, and after 24, 48, 72, and 96 hours of storage. The milk samples were analyzed for pH, total and free fatty acid profile, lipase activity at room temperature and at 4°C, lipase activity at room temperature in presence of sodium cholate (bile salt-dependent lipase), total antioxidant capacity, thiobarbituric acid reactive species, malondialdehyde, and conjugated diene concentration. The experiment was replicated in 3 independent trials.

RESULTS

Prolonged refrigeration did not affect the fatty acid composition of breast milk, and preserved both its overall oxidative status and the activity of HM lipolytic enzymes. In particular, bile salt-dependent lipase activity, long-chain polyunsaturated fatty acids, and medium-chain saturated fatty acid concentrations were unaffected for up to 96 hours of refrigerated storage.

CONCLUSIONS

Prolonged refrigeration of fresh HM for 96 hours maintained its overall lipid composition. The limited lipolysis during storage should be ascribed to the activity of lipoprotein lipase, responsible for the decrease in pH. Our study demonstrates that infants who receive expressed milk stored for up to 96 hours receive essentially the same supply of fatty acids and active lipases as do infants fed directly at the breast.

n-3 PUFA added to high-fat diets affect differently adiposity and inflammation when carried by phospholipids or triacylglycerols in mice

Background

Dietary intake of n-3 polyunsaturated fatty acids (PUFA) is primarily recognized to protect against cardiovascular diseases, cognitive dysfunctions and the onset of obesity and associated metabolic disorders. However, some of their properties such as bioavailability can depend on their chemical carriers. The objective of our study was to test the hypothesis that the nature of n-3 PUFA carrier results in different metabolic effects related to adiposity, oxidative stress and inflammation.

Methods

4 groups of C57BL/6 mice were fed for 8 weeks low fat (LF) diet or high-fat (HF, 20%) diets. Two groups of high-fat diets were supplemented with long-chain n-3 PUFA either incorporated in the form of phospholipids (HF-ω3PL) or triacylglycerols (HF-ω3TG).

Results

Both HF-ω3PL and HF-ω3TG diets reduced the plasma concentrations of (i) inflammatory markers such as monocyte chemoattractant protein-1 (MCP-1) and interleukin 6 (IL-6), (ii) leptin and (iii) 4-hydroxy-2-nonenal (4-HNE), a marker of n-6 PUFA-derived oxidative stress compared with the control HF diet. Moreover, in both HF-ω3PL and HF-ω3TG groups, MCP-1 and IL-6 gene expressions were decreased in epididymal adipose tissue and the mRNA level of gastrointestinal glutathione peroxidase GPx2, an antioxidant enzyme, was decreased in the jejunum compared with the control HF diet. The type of n-3 PUFA carrier affected other outcomes. The phospholipid form of n-3 PUFA increased the level of tocopherols in epididymal adipose tissue compared with HF-ω3TG and resulted in smaller adipocytes than the two others HF groups. Adipocytes in the HF-ω3PL and LF groups were similar in size distribution.

Conclusion

Supplementation of mice diet with long-chain n-3 PUFA during long-term consumption of high-fat diets had the same lowering effects on inflammation regardless of triacyglycerol or phospholipid carrier, whereas the location of these fatty acids on a PL carrier had a major effect on decreasing the size of adipocytes that was not observed with the triacyglycerol carrier. Altogether, these results would support the development functional foods containing LC n-3 PUFA in the form of PL in order to prevent some deleterious outcomes associated with the development of obesity.

Dietary oxidized n-3 PUFA induce oxidative stress and inflammation: role of intestinal absorption of 4-HHE and reactivity in intestinal cells

Dietary intake of long-chain n-3 PUFA is now widely advised for public health and in medical practice. However, PUFA are highly prone to oxidation, producing potentially deleterious 4-hydroxy-2-alkenals. Even so, the impact of consuming oxidized n-3 PUFA on metabolic oxidative stress and inflammation is poorly described. We therefore studied such effects and hypothesized the involvement of the intestinal absorption of 4-hydroxy-2-hexenal (4-HHE), an oxidized n-3 PUFA end-product. In vivo, four groups of mice were fed for 8 weeks high-fat diets containing moderately oxidized or unoxidized n-3 PUFA. Other mice were orally administered 4-HHE and euthanized postprandially versus baseline mice. In vitro, human intestinal Caco-2/TC7 cells were incubated with 4-hydroxy-2-alkenals. Oxidized diets increased 4-HHE plasma levels in mice (up to 5-fold, P < 0.01) compared with unoxidized diets. Oxidized diets enhanced plasma inflammatory markers and activation of nuclear factor kappaB (NF-κB) in the small intestine along with decreasing Paneth cell number (up to -19% in the duodenum). Both in vivo and in vitro, intestinal absorption of 4-HHE was associated with formation of 4-HHE-protein adducts and increased expression of glutathione peroxidase 2 (GPx2) and glucose-regulated protein 78 (GRP78). Consumption of oxidized n-3 PUFA results in 4-HHE accumulation in blood after its intestinal absorption and triggers oxidative stress and inflammation in the upper intestine.

The lipid peroxidation by-product 4-hydroxy-2-nonenal (4-HNE) induces insulin resistance in skeletal muscle through both carbonyl and oxidative stress

Numerous oxidants are produced as by-products of aerobic cell metabolism, and there is growing evidence that they play key roles in the pathogenesis of insulin resistance. Under conditions of oxidative stress, lipid peroxidation of ω6-polyunsaturated fatty acids leads to the production of 4-hydroxy-2-nonenal (4-HNE). Several lines of evidence suggest that 4-HNE could be involved in the pathophysiology of metabolic diseases; therefore, in this study we assessed the direct effects of 4-HNE on skeletal muscle insulin sensitivity. Gastrocnemius muscle and L6 muscle cells were treated with 4-HNE. Insulin signaling was measured by Western blotting and glucose uptake using 2-deoxy-d-[3H]glucose. Carbonyl stress, glutathione content, and oxidative stress were assessed as potential mechanisms leading to insulin resistance. Protection of cells was induced by pretreatment with 3H-1,2-dithiole-3-thione, N-acetyl-cysteine, aminoguanidine, or S-adenosyl-methionine. 4-HNE induced a time- and dose-dependent decrease in insulin signaling and insulin-induced glucose uptake in muscle. It induced a state of carbonyl stress through adduction of proteins as well as a depletion in reduced glutathione and production of radical oxygen species. A pharmacological increase in glutathione pools was achieved by 3H-1,2-dithiole-3-thione and protected the cells against all deleterious effects of 4-HNE; furthermore, N-acetylcysteine, aminoguanidine, and S-adenosylmethionine prevented 4-HNE noxious effects. 4-HNE can impair insulin action in muscle cells through oxidative stress and oxidative damage to proteins, eventually leading to insulin resistance. These deleterious effects can be prevented by pretreatment with antioxidants, scavengers, or an increase in intracellular glutathione pools. Use of such molecules could represent a novel strategy to combat insulin resistance and other oxidative stress-associated pathologies.

The mode of administration of total parenteral nutrition and nature of lipid content influence the generation of peroxides and aldehydes

BACKGROUND & AIMS

The absence of light protection of neonatal total parenteral nutrition (PN) contributes to the generation of 4-hydroxynonenal and peroxides. 4-Hydroxynonenal is suspected to be involved in PN-related liver complications.

AIMS

To find a practical modality to reduce 4-hydroxynonenal in PN and assess in vivo the impact of PN containing low 4-hydroxynonenal concentration.

METHODS

Six modalities of delivering PN were compared for the in vitro generation of peroxides and 4-hydroxynonenal: 1) MV-AA-L: light-protected (-L) solution containing multivitamin (MV) mixed with amino acids + dextrose (AA); 2) MV-AA+L: MV-AA without photo-protection (+L); 3) MV-LIP+L: MV mixed with lipid emulsion (LIP). LIP was a) Intralipid20%(®) or b) Omegaven(®). Hepatic markers of oxidative stress (glutathione, F(2α)-isoprostanes, GS-HNE) and inflammation (mRNA of TNF-α and IL-1) were measured in newborn guinea pigs infused during 4-days with MV-AA+L compounded with Intralipid20%(®) or Omegaven(®).

RESULTS

Hydroperoxides and 4-hydroxynonenal were the lowest in MV-AA-L and the highest in MV-LIP+L. MV-AA+L with Omegaven(®) was associated with the lowest levels of markers of oxidative stress and inflammation.

CONCLUSION

Compared to Intralipid20%(®), Omegaven(®) reduces oxidative stress associated with PN and prevents liver inflammation. These findings offer an alternative strategy to light protection of PN, which in the clinical setting is a cumbersome modality.

Liquid chromatography/electrospray ionisation mass spectrometric tracking of 4-hydroxy-2(E)-nonenal biotransformations by mouse colon epithelial cells using [1,2-13C2]-4-hydroxy-2(E)-nonenal as stable isotope tracer

4-Hydroxy-2(E)-nonenal (HNE), a product of lipid peroxidation, has been extensively studied in several areas, including metabolism with radio-isotopes and quantification in various matrices with deuterium-labelled HNE as standard. The aim of this work was to evaluate the relevance of (13)C-labelled HNE in biotransformation studies to discriminate metabolites from endogens by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI-MS). (13)C-Labelled HNE was synthesised in improved overall yield (20%), with the incorporation of two labels in the molecule. Immortalised mouse colon epithelial cells were incubated with 2:3 molar amounts of HNE/(13)C-HNE in order to gain information on the detection of metabolites in complex media. Our results demonstrated that the stable isotope m/z values determined by mass spectrometry were relevant in distinguishing metabolites from endogens, and that metabolite structures could be deduced. Six conjugate metabolites and 4-hydroxy-2(E)-nonenoic acid were identified, together with an incompletely identified metabolite. Stable-isotope-labelled HNE has already been used for quantification purposes. However, this is the first report on the use of (13)C-labelled HNE as a tracer for in vitro metabolism. (13)C-Labelled HNE could also be of benefit for in vivo studies.

French mothers' milk deficient in DHA contains phospholipid species of potential interest for infant development

OBJECTIVES

An insufficient human milk docosahexaenoic acid (DHA) level was reported worldwide, which leads to the question of the sufficiency of the DHA supply for infant development in the French Mediterranean area. Also, among milk lipids, phospholipids may be of high potential interest for infant brain development, being a specific vector of DHA and providing plasmalogens. We aimed to estimate the consumption of such milk compounds by preterm and term infants.

MATERIALS AND METHODS

Milk samples from 22 lactating French women living in a port city, Marseille, were collected in a neonatology department from a single full-breast expression using an electric pump. Amounts of triglycerides, total phospholipids and plasmalogens, and fatty acid profile were determined by gas chromatography, and cholesterol by enzymatic assay.

RESULTS

Depending on the infant dietary guidelines we referred to, 46% or 82% of milk samples were below the recommended DHA level (0.4% or 0.7%), and a majority exhibited high linoleic acid/α-linolenic acid and n-6/n-3 ratios, probably resulting from high linoleic acid together with low fish and seafood products consumption. DHA carried by phospholipids in a majority of specimens met the requirements for brain development for term but not for premature infants. Milk plasmalogen levels ranged from 3.4 to 39.2  mg/L.

CONCLUSIONS

Our results support the recommendation of DHA supplementation to French mothers living in a Mediterranean port city, and of decreased linoleic acid intake, to reach optimal milk composition for infant health. DHA-containing phospholipids including plasmalogen species may represent important bioactive human milk compounds.

Trans-4-hydroxy-2-hexenal, a product of n-3 fatty acid peroxidation: make some room HNE

Lipid peroxidation yields multiple aldehyde species. Of these, trans-4-hydroxy-2-nonenal (HNE), derived from n-6 poly-unsaturated fatty acids (PUFA) is one of the most studied products of lipid peroxidation. On the other hand, oxidative damage to n-3 PUFA, e.g. docosahexaenoic acid (DHA; 22:6, n-3) and eicosapentaenoic acid, is now recognized as an important effector of oxidative stress and is of particular interest in n-3 rich tissues such as brain and retina. Trans-4-hydroxy-2-hexenal (HHE) is a major alpha,beta-unsaturated aldehyde product of n-3 PUFA oxidation and, like HNE, is an active biochemical mediator resulting from lipid peroxidation. HHE adducts are elevated in disease states, in some cases, at higher levels than the corresponding HNE adduct. HHE has properties in common with HNE, but there are important differences particularly with respect to adduction targets and detoxification pathways. In this review, the biochemistry and cell biology of HHE will be discussed. From this review, it is clear that further study is needed to determine the biochemical and physiological roles of HHE and its related aldehyde, trans-4-oxo-2-hexenal.