Ascorbylperoxide contaminating parenteral nutrition perturbs the lipid metabolism in newborn guinea pig

Disturbances of the Lung Glutathione System in Adult Guinea Pigs Following Neonatal Vitamin C or Cysteine Deficiency

In premature infants receiving parenteral nutrition, oxidative stress is a trigger for the development of bronchopulmonary dysplasia, which is an important factor in the development of adult lung diseases. Neonatal vitamin C and glutathione deficiency is suspected to induce permanent modification of redox metabolism favoring the development of neonatal and adult lung diseases. A total of 64 3-day-old guinea pigs were fed an oral diet that was either complete or deficient in vitamin C (VCD), cysteine (CD) (glutathione-limiting substrate) or both (DD) for 4 days. At 1 week of age, half of the animals were sacrificed while the other started a complete diet until 12 weeks of age. At 1 week, the decrease in lung GSH in all deficient groups was partially explained by the oxidation of liver methionine-adenosyltransferase. mRNA levels of kelch-like ECH-associated protein 1 (Keap1), glutathione-reductase (Gsr) and glutaredoxin-1 (Glrx) were significantly lower only in CD but not in DD. At 12 weeks, glutathione levels were increased in VCD and CD. Keap1, Gsr and Glrx mRNA were increased, while glutathione-reductase and glutaredoxin proteins were lower in CD, favoring a higher glutathionylation status. Both neonatal deficiencies result in a long-term change in glutathione metabolism that could contribute to lung diseases' development.

Role of animal models in biomedical research: a review

The animal model deals with the species other than the human, as it can imitate the disease progression, its’ diagnosis as well as a treatment similar to human. Discovery of a drug and/or component, equipment, their toxicological studies, dose, side effects are in vivo studied for future use in humans considering its’ ethical issues. Here lies the importance of the animal model for its enormous use in biomedical research. Animal models have many facets that mimic various disease conditions in humans like systemic autoimmune diseases, rheumatoid arthritis, epilepsy, Alzheimer’s disease, cardiovascular diseases, Atherosclerosis, diabetes, etc., and many more. Besides, the model has tremendous importance in drug development, development of medical devices, tissue engineering, wound healing, and bone and cartilage regeneration studies, as a model in vascular surgeries as well as the model for vertebral disc regeneration surgery. Though, all the models have some advantages as well as challenges, but, present review has emphasized the importance of various small and large animal models in pharmaceutical drug development, transgenic animal models, models for medical device developments, studies for various human diseases, bone and cartilage regeneration model, diabetic and burn wound model as well as surgical models like vascular surgeries and surgeries for intervertebral disc degeneration considering all the ethical issues of that specific animal model. Despite, the process of using the animal model has facilitated researchers to carry out the researches that would have been impossible to accomplish in human considering the ethical prohibitions.

Neonatal Vitamin C and Cysteine Deficiencies Program Adult Hepatic Glutathione and Specific Activities of Glucokinase, Phosphofructokinase, and Acetyl-CoA Carboxylase in Guinea Pigs' Livers

Premature neonates are submitted to an early-life oxidative stress from parenteral nutrition, which is vitamin C (VC) deficient and induces low endogenous levels of glutathione. The oxidative stress caused by these deficiencies may permanently affect liver glycolysis and lipogenesis. This study evaluates the short- and long-term effects of neonatal VC and cysteine deficient diets on redox and energy metabolism. Three-day-old Hartley guinea pigs from both sexes were given a regular or a deficient diet (VC, cysteine, or both) until week 1 of life. Half of the animals were sacrificed at this age, while the other half ate a complete diet until 12 weeks. Liver glutathione and the activity and protein levels of glucokinase, phosphofructokinase, and acetyl-CoA-carboxylase were measured. Statistics: factorial ANOVA (5% threshold). At 1 week, all deficient diets decreased glutathione and the protein levels of glucokinase and phosphofructokinase, while cysteine deficiency decreased acetyl-CoA-carboxylase levels. A similar enzyme level was observed in control animals at 12 weeks. At this age, VC deficiency decreased glutathione, while cysteine increased it. Acetyl-CoA-carboxylase protein levels were increased, which decreased its specific activity. Early-life VC and cysteine deficiencies induce neonatal oxidative stress and an adult-like metabolism, while predisposing to increased lipogenic rates during adulthood.

Neonatal parenteral nutrition affects the metabolic flow of glucose in newborn and adult male Hartley guinea pigs' liver

Extremely premature birth is associated with a permanent disruption of energy metabolism. The underlying mechanisms are poorly understood. The oxidative stress induced by parenteral nutrition (PN) during the first week of life is suspected to reprogram energy metabolism in the liver. Full-term male Hartley guinea pigs (to isolate PN from prematurity) receiving PN enriched or not with glutathione (to isolate PN effects from PN-induced oxidative stress effects) or an Oral Nutrition (ON) during the first week of life were used. At 1 week (neonatal) and 16 weeks (adult), measurements of liver glutathione (GSH and GSSG) and activities of three key enzymes of energy metabolism (glucokinase (GCK), phosphofructokinase (PFK), and acetyl-CoA carboxylase (ACC)) were performed. Differences between groups were reported if p ≤ 0.05 (Analysis of Variance). At 1 week, compared to ON, PN induced higher GSSG (oxidative stress), higher GCK activity, and lower PFK and ACC activity, the glutathione supplement prevented all PN effects. At 16 weeks, early PN induced lower GSSG (reductive stress) and lower GCK activity, which was prevented by added glutathione, and higher ACC activity independent of glutathione supplement. ACC was negatively associated (r2 = 0.33) with GSSG. Increased nicotinamide adenine dinucleotide phosphate levels confirmed the glucose-6-phosphate accumulation at 1 week, whereas our protocol failed to document lipid accumulation at 16 weeks. In adult male guinea pigs, neonatal exposure to PN affected glutathione metabolism leading to reductive stress (lower GSSG) and an altered metabolic flow of glucose. Partial prevention with glutathione supplementation suggests that, in addition to peroxides, other factors of PN are involved.

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

Parenteral nutrition and oxidant stress in the newborn: A narrative review

There is strong evidence that oxidant molecules from various sources contaminate solutions of parenteral nutrition following interactions between the mixture of nutrients and some of the environmental conditions encountered in clinical practice. The continuous infusion of these organic and nonorganic peroxides provided us with a unique opportunity to study in cells, in vascular and animal models, the mechanisms involved in the deleterious reactions of oxidation in premature infants. Potential clinical impacts of peroxides infused with TPN include: a redox imbalance, vasoactive responses, thrombosis of intravenous catheters, TPN-related hepatobiliary complications, bronchopulmonary dysplasia and mortality. This is a narrative review of published data.

Redox Regulation of Hexokinases

SIGNIFICANCE

Hexokinases are key enzymes that are responsible for the first reaction of glycolysis, but they also moonlight other cellular processes, including mitochondrial redox signaling regulation. Modulation of hexokinase activity and spatiotemporal location by reactive oxygen and nitrogen species as well as other gasotransmitters serves as the basis for a unique, underexplored method of tight and flexible regulation of these fundamental enzymes. Recent Advances: Redox modifications of thiols serve as a molecular code that enables the precise and complex regulation of hexokinases. Redox regulation of hexokinases is also used by multiple parasites to cause widespread and severe diseases, including malaria, Chagas disease, and sleeping sickness. Redox-active molecules affect each other, and the moonlighting activity of hexokinases provides another feedback loop that affects the cellular redox status and is hijacked in malignantly transformed cells.

CRITICAL ISSUES

Several compounds affect the redox status of hexokinases in vivo. These include the dehydroascorbic acid (oxidized form of vitamin C), pyrrolidinium porrolidine-1-carbodithioate (contraceptive), peroxynitrite (product of ethanol metabolism), alloxan (a glucose analog), and isobenzothiazolinone ebselen. However, very limited information is available regarding which amino acid residues in hexokinases are affected by redox signaling. Except in cases of monogenic diabetes, direct evidence is absent for disease phenotypes that are associated with variations within motifs that are susceptible to redox signaling.

FUTURE DIRECTIONS

Further studies should address the propensity of hexokinases and their disease-associated variants to participate in redox regulation. Robust and straightforward proteomic methods are needed to understand the context and consequences of hexokinase-mediated redox regulation in health and disease.

Adult Consequences of Extremely Preterm Birth: Cardiovascular and Metabolic Diseases Risk Factors, Mechanisms, and Prevention Avenues

Extremely preterm babies are exposed to various sources of injury during critical stages of development. The extremely preterm infant faces premature transition to ex utero physiology and undergoes adaptive mechanisms that may be deleterious in the long term because of permanent alterations in organ structure and function. Perinatal events can also directly cause structural injury. These disturbances induce morphologic and functional changes in their organ systems that might heighten their risks for later adult chronic diseases. This review examines the pathophysiology of programming of long-term health and diseases after preterm birth and associated perinatal risk factors.

Impact of glutathione supplementation of parenteral nutrition on hepatic methionine adenosyltransferase activity

Background

The oxidation of the methionine adenosyltransferase (MAT) by the combined impact of peroxides contaminating parenteral nutrition (PN) and oxidized redox potential of glutathione is suspected to explain its inhibition observed in animals. A modification of MAT activity is suspected to be at origin of the PN-associated liver disease as observed in newborns. We hypothesized that the correction of redox potential of glutathione by adding glutathione in PN protects the MAT activity.

Aim

To investigate whether the addition of glutathione to PN can reverse the inhibition of MAT observed in animal on PN.

Methods

Three days old guinea pigs received through a jugular vein catheter 2 series of solutions. First with methionine supplement, (1) Sham (no infusion); (2) PN: amino acids, dextrose, lipids and vitamins; (3) PN-GSSG: PN+10 μM GSSG. Second without methionine, (4) D: dextrose; (5) D+180 μM ascorbylperoxide; (6) D+350 μM H₂O₂. Four days later, liver was sampled for determination of redox potential of glutathione and MAT activity in the presence or absence of 1 mM DTT. Data were compared by ANOVA, p<0.05.

Results

MAT activity was 45±4% lower in animal infused with PN and 23±7% with peroxides generated in PN. The inhibition by peroxides was associated with oxidized redox potential and was reversible by DTT. Correction of redox potential (PN+GSSG) or DTT was without effect on the inhibition of MAT by PN. The slope of the linear relation between MAT activity and redox potential was two fold lower in animal infused with PN than in others groups.

Conclusion

The present study suggests that prevention of peroxide generation in PN and/or correction of the redox potential by adding glutathione in PN are not sufficient, at least in newborn guinea pigs, to restore normal MAT activity.

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Methionine adenosyltransferase (MAT) is essential for healthy liver.

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Parenteral nutrition (PN) inhibits hepatic MAT.

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The inhibition is caused by intrinsic peroxides and by unknown component of PN.

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Adding glutathione in PN is not sufficient to prevent PN-associated liver diseases.

Adding glutathione to parenteral nutrition prevents alveolar loss in newborn Guinea pig

Bronchopulmonary dysplasia, a main complication of prematurity, is characterized by an alveolar hypoplasia. Oxidative stress is suspected to be a trigger event in this population who has a low level of glutathione, a main endogenous antioxidant, and who receives high oxidative load, particularly ascorbylperoxide from their parenteral nutrition.

HYPOTHESIS

the addition of glutathione (GSSG) in parenteral nutrition improves detoxification of ascorbylperoxide by glutathione peroxidase and therefore prevents exaggerated apoptosis and loss of alveoli.

METHODS

Ascorbylperoxide is assessed as substrate for glutathione peroxidase in Michaelis-Menten kinetics. Three-days old guinea pig pups were divided in 6 groups to receive, through a catheter in jugular vein, the following solutions: 1) Sham (no infusion); 2) PN(-L): parenteral nutrition protected against light (low ascorbylperoxide); 3) PN(+L): PN without photo-protection (high ascorbylperoxide); 4) 180 μM ascorbylperoxide; 5) PN(+L)+10 μM GSSG; 6) ascorbylperoxyde+10 μM GSSG. After 4 days, lungs were sampled and prepared for histology and biochemical determinations. Data were analysed by ANOVA, p < 0.05 RESULTS: The Km of ascorbylperoxide for glutathione peroxidase was 126 ± 6 μM and Vmax was 38.4 ± 2.5 nmol/min/ U. The presence of GSSG in intravenous solution has prevented the high GSSG, oxidized redox potential of glutathione, activation of caspase-3 (apoptosis marker) and loss of alveoli induced by PN(+L) or ascorbylperoxide.

CONCLUSION

A correction of the low glutathione levels observed in newborn animal on parenteral nutrition, protects lungs from toxic effect of ascorbylperoxide. Premature infants having a low level of glutathione, this finding is of high importance because it provides hope in a possible prevention of bronchopulmonary dysplasia.

Ascorbylperoxide from parenteral nutrition induces an increase of redox potential of glutathione and loss of alveoli in newborn guinea pig lungs

Background

Bronchopulmonary dysplasia is one of the main complications associated with extreme prematurity. Oxidative stress is suspected to be a trigger event of this lung disease, which is characterized by impaired alveolar development. Peroxides, mainly ascorbylperoxide and H₂O₂, are known contaminant of parenteral nutrition. We hypothesize that these oxidant molecules induce bronchopulmonary dysplasia development. The aim was to determine if the infusion of ascorbylperoxide, whether in presence or absence of H₂O₂, is associated with oxidative stress, apoptosis and loss of alveoli in the lungs of newborn guinea pigs.

Method

Three-day-old guinea pigs received parenteral solutions containing 0, 20, 60 or 180 µM ascorbylperoxide in the presence or not of 350 µM H₂O₂ (concentrations similar to those measured in parenteral nutrition). After 4 days, the lungs were collected for determination of glutathione's redox potential, caspase-3 activation (an apoptosis marker), alveolarization index (by histology), activation of Nrf2 and NF?B (biological markers of oxidative stress), and IL-6 and PGJ₂ levels (markers of NF?B activation). Groups were compared by ANOVA, p < 0.05.

Results

Loss of alveoli was associated with ascorbylperoxide in a dose-dependent manner, without an influence of H₂O₂. The dose-dependent activation of caspase-3 by ascorbylperoxide was lower in the presence of H₂O₂. Ascorbylperoxide induced an increase of redox potential in a dose-dependent manner, which reached a plateau in presence of H₂O₂. Nrf2 and NF?B were activated by H₂O₂ but not by ascorbylperoxide.

Conclusion

Results suggest that ascorbylperoxide, generated in parenteral nutrition, is involved in the development of bronchopulmonary dysplasia, independently of the increase of the redox potential. This study underlines the importance of developing a safer formulation of parenteral nutrition.

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Oxidative stress is suspected to induce bronchopulmonary dysplasia.

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We investigate the role of ascorbylperoxide contaminating parenteral nutrition.

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This molecule induces oxidation of redox potential, apoptosis and loss of alveoli.

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The alveolar loss is independent of the redox potential.