L-Cysteine metabolism and its nutritional implications

Effects of dietary methionine on productivity, reproductive performance, antioxidant capacity, ovalbumin and antioxidant-related gene expression in laying duck breeders

The study investigated whether dietary methionine (Met) affects egg weight and antioxidant status through regulating gene expression of ovalbumin (OVAL), nuclear factor erythroid 2 like 2 (Nrf2) and haem oxygenase 1 (HO-1) in laying duck breeders. Longyan duck breeders (n 540, 19 weeks) were randomly assigned to six treatments with six replicates of fifteen birds each. Breeders were fed diets with six Met levels (2·00, 2·75, 3·50, 4·25, 5·00 and 5·75 g/kg) for 24 weeks. The egg weight (g), egg mass (g/d), feed conversion ratio, hatchability, 1-d duckling weight, albumen weight, albumen proportion and OVAL mRNA level improved with dietary Met levels, whereas yolk proportion decreased (P<0·05). The weight of total large yellow follicles increased linearly (P<0·001) and quadratically (P<0·05) with dietary Met concentration, and their weight relative to ovarian weight showed a linear (P<0·05) effect. Dietary Met level had a linear (P<0·05) and quadratic (P<0·001) effect on the gene expression of glutathione peroxidase (GPX1), HO-1 and Nrf2, and quadratically (P<0·05) increased contents of GPX and total antioxidant capacity (T-AOC) in liver of duck breeders. In addition, maternal dietary Met enhanced gene expression of GPX1, HO-1 and Nrf2, increased contents of GPX and T-AOC and reduced carbonylated protein in the brains of hatchlings. Overall, dietary Met concentration affected egg weight and albumen weight in laying duck breeders, which was partly due to gene expression of OVAL in oviduct magnum. A diet containing 4·0 g Met/kg would achieve optimal hepatic GPX1 and Nrf2 expression, maximise the activity of GPX and minimise lipid peroxidation.

Early Supplementation of d-Cysteine or l-Cysteine Prevents Hypertension and Kidney Damage in Spontaneously Hypertensive Rats Exposed to High-Salt Intake

SCOPE

We investigate whether early supplementation of precursors of hydrogen sulfide (H₂ S), d- or l-cysteine can prevent hypertension and kidney damage in spontaneously hypertensive rats (SHR) treated with high-salt.

METHODS AND RESULTS

We examine 12-week-old male SHRs from four groups: SHR, high salt SHR (SHRs received 1% NaCl in drinking water for 8 weeks), high salt SHR+d (SHRs received high salt and d-cysteine), and high salt SHR+l (SHRs received high salt and l-cysteine). d- or l-cysteine was supplemented at 8 mmol kg^-1 body weight/day between 4 and 6 weeks of ages. High salt intake exacerbate hypertension and kidney damage in SHRs, which is prevented by d- or l-cysteine supplementation. d- or l-Cysteine supplementation reduce the degree of high salt-induced oxidative stress damage. Renal 3-mercaptopyruvate sulphurtransferase (3MST) protein levels and activity are reduced by d- or l-cysteine supplementation. Additionally, d- or l-Cysteine supplementation reduce renal angiotensin I and angiotensin II concentrations, decrease mRNA expression of Ren, and increase protein levels of type 2 angiotensin II receptor.

CONCLUSION

Early supplementation of d- or l-cysteine before hypertension becomes evident and may protect against hypertension and kidney damage in adult SHRs exposed to high salt consumption via regulation of oxidative stress, renin-angiotensin system, and H₂ S-generating pathways.

Physicochemical stable standard all-in-one parenteral nutrition admixtures for infants and children in accordance with the ESPGHAN/ESPEN guidelines

OBJECTIVE

Because there are almost no standard all-in-one parenteral nutrition admixtures available for infants and children, the aim was to develop standard two-compartment parenteral nutrition bags for different weight categories based on the ESPGHAN/ESPEN (European Society of Paediatric Gastroenterology, Hepatology and Nutrition/European Society for Clinical Nutrition and Metabolism) guidelines. The 1 g/kg/d lipid version for the 3 to 10 kg weight category (PED1) was assessed for short- and long-term physicochemical stability with the ability to add additional electrolytes (PED1+E).

METHODS

The lipid compartment A and the all-in-one admixture of A + B + vitamins + trace elements were assessed physically by visual inspection, Sudan red test, pH measurement, and lipid droplet size distribution. Chemical stability for compartment A was evaluated by quantitative analyses of non-esterified fatty acids and peroxide content. The glucose-amino acid-electrolyte compartment B was evaluated physically by visual inspection, measuring particle contamination and pH. Chemical stability was assessed by discoloration, quantitative analyses of glucose, and the amino acids L-cysteine, L-tyrosine, and L-tryptophan.

RESULTS

No phase separation or coalescence occurred, and the mean droplet size diameter did not exceed 0.5 µm. Peroxide content and non-esterified fatty acids concentration of compartment A remained well below the limit of acceptation. No precipitation was detected for compartment B; only a slight yellow discoloration was noted at 80 d. Concentrations of glucose, L-tyrosine, and L-tryptophan remained stable; only L-cysteine decreased significantly from its initial concentration.

CONCLUSION

The two-compartment PED1 and PED1+E admixtures are stable up to 80 d 2° to 8°C + 24 h room temperature (RT) with an additional 7 d 2° to 8°C + 48 h RT after mixing and addition of vitamins and trace elements.

Effects of Lysine deficiency and Lys-Lys dipeptide on cellular apoptosis and amino acids metabolism

SCOPE

Lysine (Lys) is a common limiting amino acids (AA) for humans and animals and plays an important role in cell proliferation and metabolism, while metabolism of Lys deficiency and its dipeptide is still obscure. Thus, this study mainly investigated the effects of Lys deficiency and Lys-Lys dipeptide on apoptosis and AA metabolism in vitro and in vivo models.

METHODS AND RESULTS

Lys deficiency induced cell-cycle arrest and apoptosis and upregulated Lys transporters in vitro and in vivo. SLC7A11, a cystine-glutamate antiporter, was markedly upregulated by Lys deficiency and then further mediated cystine uptake and glutamate release, which was negatively regulated by cystine and glutamate transporters. Meanwhile, Lys deprivation upregulated pept1 expression, which might improve Lys-Lys dipeptide absorption to compensate for the reduced Lys availability. Lys-Lys dipeptide alleviated Lys deficiency induced cell-cycle arrest and apoptosis and influenced AA metabolism. Furthermore, the mammalian target of rapamycin signal might be involved in sensing cellular Lys starvation and Lys-Lys dipeptide.

CONCLUSIONS

Altogether, these studies suggest that Lys deficiency impairs AA metabolism and causes apoptosis. Lys-Lys dipeptide serves as a Lys source and alleviates Lys deficiency induced cellular imbalance.

Associations between Specific Redox Biomarkers and Age in a Large European Cohort: The MARK-AGE Project

Oxidative stress and antioxidants play a role in age-related diseases and in the aging process. We here present data on protein carbonyls, 3-nitrotyrosine, malondialdehyde, and cellular and plasma antioxidants (glutathione, cysteine, ascorbic acid, uric acid, α-tocopherol, and lycopene) and their relation with age in the European multicenter study MARK-AGE. To avoid confounding, only data from countries which recruited subjects from all three study groups (five of eight centers) and only participants aged ≥55 years were selected resulting in data from 1559 participants. These included subjects from (1) the general population, (2) members from long-living families, and (3) their spouses. In addition, 683 middle-aged reference participants (35–54 years) served as a control. After adjustment for age, BMI, smoking status, gender, and country, there were differences in protein carbonyls, malondialdehyde, 3-nitrotyrosine, α-tocopherol, cysteine, and glutathione between the 3 study groups. Protein carbonyls and 3-nitrotyrosine as well as cysteine, uric acid, and lycopene were identified as independent biomarkers with the highest correlation with age. Interestingly, from all antioxidants measured, only lycopene was lower in all aged groups and from the oxidative stress biomarkers, only 3-nitrotyrosine was increased in the descendants from long-living families compared to the middle-aged control group. We conclude that both lifestyle and genetics may be important contributors to redox biomarkers in an aging population.

Comparisons of l-cysteine and d-cysteine toxicity in 4-week repeated-dose toxicity studies of rats receiving daily oral administration

Two 4-week repeated-dose toxicity studies were conducted to evaluate the potential toxicity of l-cysteine and d-cysteine. In one study, three groups of 6 male rats were each administered l-cysteine once daily by gavage at doses of 500, 1,000, or 2,000 mg/kg/day for 28 consecutive days. The control group was administered a 0.5% methylcellulose vehicle solution. The other study followed a similar protocol except that the experimental groups received d-cysteine. Toxicological observations showed that the l-cysteine-treated groups exhibited renal injuries such as basophilic tubules with eosinophilic material in the lumen, and there were increased numbers of basophilic tubules in all treated groups. In 1,000 or 2,000 mg/kg/day-treated groups, salivation and necropsy findings indicative of focal erosion in the stomach mucosa were found. Increases in reticulocyte counts were observed in the 2,000 mg/kg/day-treated group. Toxicological findings obtained for the d-cysteine-treated groups included anemia and renal injuries such as basophilic tubules with eosinophilic material in the lumen, increased numbers of basophilic tubules, and crystal deposition in the medulla in the 2,000 mg/kg/day-treated group. Additional findings included sperm granuloma in the epididymis, necropsy findings suggestive of focal erosion in the stomach mucosa, and salivation in the 1,000 or 2,000 mg/kg/day-treated groups. One rat in the 2,000 mg/kg/day-treated group died due to renal failure. In conclusion, the no-observed-adverse-effect levels (NOAELs) were estimated to be less than 500 mg/kg/day for l-cysteine and 500 mg/kg/day for d-cysteine under our study conditions. The toxicological profiles were similar for l-cysteine and d-cysteine; however, there were slight differences in the dose responses. The mechanisms underlying these differences remain to be determined.

Magnolol pretreatment attenuates heat stress-induced IEC-6 cell injury

OBJECTIVE

Heat stress (HS) is an important environmental stressor that adversely influences livestock during the summer. The aim of this study was to investigate whether magnolol protects against HS-induced intestinal epithelial cell injury.

MATERIALS AND METHODS

An intestinal epithelial cell line (IEC-6) was subjected to HS at 42 °C, with and without magnolol pretreatment. Cell injury was detected by monitoring lactate dehydrogenase (LDH) release. MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay was used to assess cell proliferation and viability, including identifying effective concentrations of magnolol. Flow cytometry confirmed G1-phase cell-cycle arrest and its alleviation by magnolol. Active DNA synthesis was measured by incorporation of nucleic acid 5-ethynyl-2'-deoxyuridine (EdU). G1-phase cell-cycle-related gene expression was assessed by real-time reverse transcription polymerase chain reaction (RT-PCR) and levels of G1-phase-related proteins by Western blotting.

RESULTS

HS induced IEC-6 cell injury and decreased cell viability, as demonstrated by data from LDH and MTS assays, respectively. Based on a number of criteria, IEC-6 cells subjected to HS were arrested in the G1 phase of the cell cycle. Magnolol pretreatment decreased HS-induced cell injury through relief of this cell-cycle arrest.

CONCLUSIONS

Magnolol pretreatment attenuates HS-induced injury in IEC-6 cells. Magnolol is potentially promising as a protective strategy for HS in livestock.

Dietary soy isoflavones alleviate dextran sulfate sodium-induced inflammation and oxidative stress in mice

It has been hypothesized that soy isoflavones exhibit anti-oxidative and anti-inflammatory functions, however, the effects of soy isoflavones on inflammatory bowel diseases remain unknown. Therefore, the present study aimed to investigate the effect and underlying mechanism of dietary soy isoflavones on dextran sulfate sodium (DSS)-induced colitis. Mice were administered DSS and soy isoflavones, and histomorphometry, oxidative stress, inflammation and intestinal tight junctions were determined. The current study demonstrated that dietary soy isoflavones alleviated DSS-induced growth suppression, colonic inflammatory response, oxidative stress and colonic barrier dysfunction. DSS treatment was indicated to activate Toll-like receptor 4 (TRL4) and myeloid differentiation protein 88 (MyD88) in mice, whereas dietary soy isoflavones inhibited Myd88 expression in DSS-challenged mice. In conclusion, dietary soy isoflavones alleviate DSS-induced inflammation in mice, which may be associated with enhancing antioxidant function and inhibiting the TLR4/MyD88 signal.

Thiol trapping and metabolic redistribution of sulfur metabolites enable cells to overcome cysteine overload

Cysteine is an essential requirement in living organisms. However, due to its reactive thiol side chain, elevated levels of intracellular cysteine can be toxic and therefore need to be rapidly eliminated from the cellular milieu. In mammals and many other organisms, excess cysteine is believed to be primarily eliminated by the cysteine dioxygenase dependent oxidative degradation of cysteine, followed by the removal of the oxidative products. However, other mechanisms of tackling excess cysteine are also likely to exist, but have not thus far been explored. In this study, we use Saccharomyces cerevisiae, which naturally lacks a cysteine dioxygenase, to investigate mechanisms for tackling cysteine overload. Overexpressing the high affinity cysteine transporter, YCT1, enabled yeast cells to rapidly accumulate high levels of intracellular cysteine. Using targeted metabolite analysis, we observe that cysteine is initially rapidly interconverted to non-reactive cystine in vivo. A time course revealed that cells systematically convert excess cysteine to inert thiol forms; initially to cystine, and subsequently to cystathionine, S-Adenosyl-L-homocysteine (SAH) and S-Adenosyl L-methionine (SAM), in addition to eventually accumulating glutathione (GSH) and polyamines. Microarray based gene expression studies revealed the upregulation of arginine/ornithine biosynthesis a few hours after the cysteine overload, and suggest that the non-toxic, non-reactive thiol based metabolic products are eventually utilized for amino acid and polyamine biogenesis, thereby enabling cell growth. Thus, cells can handle potentially toxic amounts of cysteine by a combination of thiol trapping, metabolic redistribution to non-reactive thiols and subsequent consumption for anabolism.

Effects of feeding frequency on meat quality traits and Longissimus muscle proteome in finishing pigs

Sixty-four barrows with an initial body weight of 59.8 ± 2.1 kg were allocated to one of the two feeding frequency regimes (had free access to diet and fed two meals per day). Pigs had free access (FA) to feed were fed on an ad libitum basis during the 8-week experimental period. Pigs fed twice daily (M2) were allowed to consume their meals in 2 h. Pigs fed twice daily had lower average daily feed intake (p < 0.01) and average daily gain (p < 0.1), but a greater G:F (p < 0.05) than FA pigs. Lower perirenal fat deposition, hot carcass weight, intramuscular fat content (p < 0.05) and dressing percentage (p < 0.1) were found in M2 pigs compared with FA pigs. Activities of citrate synthase, β-hydroxylacyl-CoA dehydrogenase and lactate dehydrogenase were greater in the Longissimus muscle (LM) of M2 pigs compared with FA pigs (p < 0.05). Proteomic analysis revealed that expression abundances of proteins involved in glucose metabolism, energy production and lipid utilization were upregulated, but expression levels of proteins participating in protein and amino acid metabolism, stress response and redox homeostasis were downregulated in the LM of M2 pigs than those in FA pigs (p < 0.05). In conclusion, the less meal frequency impairs growth rate, has marginal effects on carcass and meat quality traits and affects expression abundances of proteins in the LM of finishing pigs.

An oxidized/reduced state of plasma albumin reflects malnutrition due to an insufficient diet in rats

We examined whether protein- and food-intake restrictions modulate the oxidized/reduced state of plasma albumin in Sprague-Dawley rats. Rats were fed a 3%, 5%, 10% or 20% casein diet for 2 weeks. The plasma albumin concentration significantly decreased with decreasing protein intake. However, no significant difference in plasma albumin concentration was seen between rats fed the 5% or 10% casein diet. In rats fed the 5% casein diet, the percentage of mercaptalbumin within total plasma albumin was significantly lower and that of nonmercaptalbumin-1 was significantly higher than in rats fed the 10% casein diet. In experiments with food-intake restriction for 2 weeks, rats were fed 50% or 75% of the amount of a 20% casein diet consumed by control rats. The percentage of mercaptalbumin was significantly lower and that of nonmercaptalbumin-2 was significantly higher in rats with food-intake restriction than in control rats. When rats with malnutrition were refed with the 20% casein diet ad libitum, the percentage of mercaptalbumin rapidly increased. The change in the percentage of mercaptalbumin was correlated with the plasma transthyretin concentration. These results indicate that the oxidized/reduced state of plasma albumin may be applied as a sensitive marker of nutritional status reflecting dietary pattern.

Downregulation of miR-150 Expression by DNA Hypermethylation Is Associated with High 2-Hydroxy-(4-methylthio)butanoic Acid-Induced Hepatic Cholesterol Accumulation in Nursery Piglets

Excess 2-hydroxy-(4-methylthio)butanoic acid (HMB) supplementation induces hyperhomocysteinemia, which contributes to hepatic cholesterol accumulation. However, it is unclear whether and how high levels of HMB break hepatic cholesterol homeostasis in nursery piglets. In this study, HMB oversupplementation suppressed food intake and decreased body weight in nursery piglets. Hyperhomocysteinemia and higher hepatic cholesterol accumulation were observed in HMB groups. Accordingly, HMB significantly increased the protein content of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and glycine N-methyltransferase (GNMT) but decreased that of acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1). Significant downregulation of miR-150, miR-181d-5p, and miR-296-3p targeting the 3'-untranslated regions (UTRs) of GNMT and HMGCR was detected in the liver of HMB-treated piglets, and their functional validation was confirmed by dual-luciferase reporter assay. Furthermore, hypermethylation of miR-150 promoter was detected in association with suppressed miR-150 expression in the livers of HMB-treated piglets. This study indicated a new mechanism of hepatic cholesterol unhomeostasis by dietary methyl donor supplementation.

Improved cryotolerance and developmental potential of in vitro and in vivo matured mouse oocytes by supplementing with a glutathione donor prior to vitrification

STUDY QUESTION

Can supplementation of media with a glutathione (GSH) donor, glutathione ethyl ester (GEE), prior to vitrification protect the mouse oocyte from oxidative damage and critical changes in redox homeostasis, and thereby improve cryotolerance?

SUMMARY ANSWER

GEE supplementation supported redox regulation, rapid recovery of spindle and chromosome alignment after vitrification/warming and improved preimplantation development of mouse metaphase II (MII) oocytes.

WHAT IS KNOWN ALREADY

Cryopreservation may affect mitochondrial functionality, induce oxidative stress, and thereby affect spindle integrity, chromosome segregation and the quality of mammalian oocytes. GEE is a membrane permeable GSH donor that promoted fertilization and early embryonic development of macaque and bovine oocytes after IVM.

STUDY DESIGN, SIZE, DURATION

Two experimental groups consisted of (i) denuded mouse germinal vesicle (GV) oocytes that were matured in vitro in the presence or absence of 1 mM GEE (IVM group 1) and (ii) in vivo ovulated (IVO) MII oocytes that were isolated from the ampullae and exposed to 1 mM GEE for 1 h prior to vitrification (IVO group 2). Recovery of oocytes from both groups was followed after CryoTop vitrification/warming for up to 2 h and parthenogenetic activation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Reactive oxygen species (ROS), spindle morphology and chromosome alignment were analyzed by confocal laser scanning microscopy (CLSM) and polarization microscopy in control and GEE-supplemented MII oocytes. The relative overall intra-oocyte GSH content was assessed by analysis of monochlorobimane (MBC)-GSH adduct fluorescence in IVM MII oocytes. The GSH-dependent intra-mitochondrial redox potential (E^m_GSH) of IVM MII oocytes was determined after microinjection with specific mRNA at the GV stage to express a redox-sensitive probe within mitochondria (mito-Grx1-roGFP2). The absolute negative redox capacity (in millivolts) was determined by analysis of fluorescence of the oxidized versus the reduced form of sensor by CLSM and quantification according to Nernst equation. Proteome analysis was performed by quantitative 2D saturation gel electrophoresis (2D DIGE). Since microinjection and expression of redox sensor mRNA required removal of cumulus cells, and IVM of denuded mouse oocytes in group 1 induces zona hardening, the development to blastocysts was not assessed after IVF but instead after parthenogenetic activation of vitrified/warmed MII oocytes from both experimental groups.

MAIN RESULTS AND ROLE OF CHANCE

IVM of denuded mouse oocytes in the presence of 1 mM GEE significantly increased intra-oocyte GSH content. ROS was not increased by CryoTop vitrification but was significantly lower in the IVM GEE group compared to IVM without GEE before vitrification and after recovery from vitrification/warming (P < 0.001). Vitrification alone significantly increased the GSH-dependent intra-mitochondrial redox capacity after warming (E^m_GSH, P < 0.001) in IVM oocytes, presumably by diffusion/uptake of cytoplasmic GSH into mitochondria. The presence of 1 mM GEE during IVM increased the redox capacity before vitrification and there was no further increase after vitrification/warming. None of the reproducibly detected 1492 spots of 2D DIGE separated proteins were significantly altered by vitrification or GEE supplementation. However, IVM of denuded oocytes significantly affected spindle integrity and chromosome alignment right after warming from vitrification (0 h) in group 1 and spindle integrity in group 2 (P < 0.05). GEE improved recovery in IVM group as numbers of oocytes with unaligned chromosomes and aberrant spindles was not significantly increased compared to unvitrified controls. The supplementation with GEE for 1 h before vitrification also supported more rapid recovery of spindle birefringence. GEE improved significantly development to the 2-cell stage for MII oocytes that were activated directly after vitrification/warming in both experimental groups, and also the blastocyst rate in the IVO GEE-supplemented group compared to the controls (P < 0.05).

LARGE SCALE DATA

None LIMITATIONS, REASONS FOR CAUTION: The studies were carried out in a mouse model, in IVM denuded rather than cumulus-enclosed oocytes, and in activated rather than IVF MII oocytes. Whether the increased GSH-dependent intra-mitochondrial redox capacity also improves male pronuclear formation needs to be studied further experimentally. The influence of GEE supplementation requires also further examination and optimization in human oocytes before it can be considered for clinical ART.

WIDER IMPLICATIONS OF THE FINDINGS

Although GEE supplementation did not alter the proteome at MII, the GSH donor may support cellular homeostasis and redox regulation and, thus, increase developmental competence. While human MII oocyte vitrification is an established procedure, GEE might be particularly beneficial for oocytes that suffer from oxidative stress and reduced redox capacity (e.g. aged oocytes) or possess low GSH due to a reduced supply of GSH from cumulus. It might also be of relevance for immature human oocytes that develop without cumulus to MII in vitro (e.g. in ICSI cycles) for ART.

STUDY FUNDING AND COMPETING INTERESTS

The study has been supported by the German Research Foundation (DFG FOR 1041; EI 199/3-2). There are no conflict of interests.

The cytotoxicity and protective effects of Astragalus membranaceus extracts and butylated hydroxyanisole on hydroxyl radical-induced apoptosis in fish erythrocytes

Erythrocytes play an essential role in transporting O₂ and CO₂ for respiration in fish. However, erythrocytes continuously suffer from reactive oxygen species (ROS) -induced oxidative stress and apoptosis. Thus, it is essential to expand our knowledge of how to protect erythrocytes against ROS-induced oxidative stress and apoptosis in fish. In this study, we explored the cytotoxicity and the effects of butylated hydroxyanisole (BHA), ethyl ether extracts, ethyl acetate extracts, acetone extracts (AE), ethanol extracts, and aqueous extracts of Astragalus membranaceus (EAm) on hydroxyl radical (•OH)-induced apoptosis in carp erythrocytes. The rat hepatocytes and carp erythrocytes were incubated with different concentrations of BHA or EAm(0.125 to 1 mg/mL). The toxicity in rat hepatocytes and carp erythrocytes was then measured using a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and a haemolysis assay, respectively. The carp erythrocytes were treated with BHA or EAm in the presence of 40 μmol/L FeSO₄ and 20 μmol/L H₂O₂ at 37 °C, except for the control group. Oxidative stress and apoptosis parameters in the carp erythrocytes were then evaluated using the commercial kit. The results indicated that at high concentrations, BHA and EAm could induce toxicity in rat hepatocytes and fish erythrocytes. However, BHA was more toxic than EAm at the same concentrations. Moreover, the toxicity order of BHA and EAm in the fish erythrocytes approximately agreed with that for the rat hepatocytes. Butylated hydroxyanisole and EAm suppressed the •OH-induced phosphatidylserine exposure and DNA fragmentation (the biomarkers of apoptosis) by decreasing the generation of ROS, inhibiting the oxidation of cellular components, and restoring the activities of antioxidants in carp erythrocytes. Of all of the examined EAm, the AE showed the strongest effects. The effects of AE on superoxide anion, H₂O₂, met-haemoglobin and reduced glutathione levels, as well as glutathione reductase activity and apoptosis were equivalent to or stronger than those of BHA. These results revealed that the AE of Astragalus membranaceus could be used as a potential natural antioxidant or apoptosis inhibitor in fish erythrocytes.

Hydrogen sulfide improves colonic barrier integrity in DSS-induced inflammation in Caco-2 cells and mice

Intestinal barrier involves in the pathogeny of inflammatory bowel disease (IBD) and hydrogen sulfide (H2S) has been reported to improve intestinal barrier integrity. Thus, this study investigated the effects of GYY4137, a slow-release H2S donor, on DSS-induced inflammation and intestinal dysfunction. In vitro model, cellular permeability was significantly increased and expression of tight junctions (ZO-1, Cauldin4, and Occludin) was downregulated in Caco-2 cells. GYY4137 treatment markedly attenuated DSS-induced inflammation and barrier dysfunction. Cystathionine β-synthase (CBS)-siRNA transfection further demonstrated that endogenous H2S system involves in DSS-induced inflammation and mediates barrier function. In vivo model, DSS exposure caused colonic inflammation and injury in mice and GYY4137 injection alleviated inflammatory response and improved intestinal barrier via reducing intestinal permeability and upregulating of tight junctions. In conclusion, endogenous H2S system involves in DSS-induced inflammation and H2S addition alleviated inflammation and intestinal dysfunction in vitro and in vivo.

Inhibition of lipid oxidation in foods and feeds and hydroxyl radical-treated fish erythrocytes: A comparative study of Ginkgo biloba leaves extracts and synthetic antioxidants

This study explored the effects of butylated hydroxytoluene (BHT) and ethoxyquin (EQ) and ethyl ether extracts, ethyl acetate extracts (EAE), acetone extracts, ethanol extracts and aqueous extracts of Ginkgo biloba leaves (EGbs) on lipid oxidation in a linoleic acid emulsion, fish flesh and fish feed and in hydroxyl radical (·OH)-treated carp erythrocytes. The linoleic acid, fish flesh and fish feed were incubated with BHT, EQ and EGbs at 45°C for 8 d, respectively, except for the control group. The lipid oxidation in the linoleic acid emulsion, fish flesh and fish feed was then measured by the ferric thiocyanate method or thiobarbituric acid method. The carp erythrocytes were treated with BHT, EQ or EGbs in the presence of 40 μmol/L FeSO₄ and 20 μmol/L H₂O₂ at 37°C for 6 h, except for the control group. Oxidative stress and apoptosis parameters in carp erythrocytes were then evaluated by the commercial kit. The results showed that BHT, EQ and EGbs inhibited lipid oxidation in the linoleic acid emulsion, fish flesh and fish feed and ·OH-induced phosphatidylserine exposure and DNA fragmentation (the biomarkers of apoptosis) in carp erythrocytes. Furthermore, BHT, EQ and EGbs decreased the generation of reactive oxygen species (ROS), inhibited the oxidation of cellular components and restored the activities of enzymatic antioxidants in ·OH-treated carp erythrocytes. Of all examined EGbs, EAE showed the strongest effects. The effects of EAE on lipid oxidation in the linoleic acid emulsion and on superoxide anion and malonaldehyde levels, catalase activity and apoptosis in ·OH-treated carp erythrocytes were equivalent to or stronger than those of BHT. Moreover, these results indicated that the inhibition order of EGbs on the generation of ROS and oxidation of cellular components in fish erythrocytes approximately agreed with that for the food and feed materials tested above. And, the antioxidative and anti-apoptotic effects of EGbs were positively correlated with their flavonoid content. Taken together, these results revealed that the fish erythrocyte system can be used as an experimental model to evaluate lipid oxidation in food and feed ingredients. The EAE can be used as a potential natural antioxidant or apoptosis inhibitor. The inhibition effects of EGbs on lipid oxidation and apoptosis may be due to the presence of flavonoid compounds.

NaHS inhibits NF-κB signal against inflammation and oxidative stress in post-infectious irritable bowel syndrome

In this study, the alleviating role of hydrogen sulfide (H₂S) was investigated in a Post-Infectious Irritable Bowel Syndrome (PI-IBS) murine model and Caco-2 cells.

Pyruvate Kinase Isoform Switching and Hepatic Metabolic Reprogramming by the Environmental Contaminant 2,3,7,8-Tetrachlorodibenzo-p-Dioxin

The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) elicits dose-dependent hepatotoxicity that includes fat accumulation, inflammation, and fibrosis that may progress to hepatocellular carcinoma. To further investigate these effects, RNA-Seq data were integrated with computationally identified putative dioxin response elements, and complementary targeted metabolomic and aryl hydrocarbon receptor (AhR) ChIP-Seq data from female C57BL/6 mice gavaged with TCDD every 4 days for 28 days. Data integration using CytoKEGG with manual curation identified dose-dependent alterations in central carbon and amino acid metabolism. More specifically, TCDD increased pyruvate kinase isoform M2 (PKM2) gene and protein expression. PKM2 has lower catalytic activity resulting in decreased glycolytic flux and the accumulation of upstream intermediates that were redirected to the pentose phosphate pathway and serine/folate biosynthesis, 2 important NADPH producing pathways stemming from glycolysis. In addition, the GAC:KGA glutaminase (GLS1) protein isoform ratio was increased, consistent with increases in glutaminolysis which serves an anaplerotic role for the TCA cycle and compensates for the reduced glycolytic flux. Collectively, gene expression, protein, and metabolite changes were indicative of increases in NADPH production in support of cytochrome P450 activity and ROS defenses. This AhR-mediated metabolic reprogramming is similar to the Warburg effect and represents a novel advantageous defense mechanism to increase anti-oxidant capacity in normal differentiated hepatocytes.

Preinduction of heat shock protein 70 protects mice against post-infection irritable bowel syndrome via NF-κB and NOS/NO signaling pathways

This study aimed to investigate the protective effects of preinduction of heat shock protein 70 (HSP70) on Trichinella spiralis infection-induced post-infectious irritable bowel syndrome (PI-IBS) in mice. Trichinella spiralis infection significantly reduced HSP70 abundance, ileal villus height and crypt depth, expression of tight junctions, serum lysine and arginine concentrations, and ileal SCL7A6 and SCL7A7 mRNA levels, induced inflammatory response, and activated NF-κB signaling pathway. Meanwhile, the heat treatment upregulated HSP70 expression, and then reversed intestinal dysfunction and inflammatory response. Preinduction of HSP70 enhanced serum arginine and intestinal SCL7A7 expression and inhibited NF-κB activation compared with PI-IBS model. Treatment with pyrrolidine dithiocarbamate (PDTC, an NF-κB inhibitor) and N-nitro-L-arginine methyl ester hydrochloride (L-NAME, a nitric oxide synthase inhibitor, NOS) further demonstrated that preinduction of HSP70 might inhibit NF-κB and activated NOS/nitric oxide (NO) signaling pathways. In conclusion, preinduction of HSP70 by heat treatment may confer beneficial effects on Trichinella spiralis infection-induced PI-IBS in mice, and the protective effect of HSP70 may be associated with inhibition of NF-κB and stimulation of NOS/NO signaling pathways.

Arginyl-glutamine dipeptide attenuates experimental colitis by enhancing antioxidant function and inhibiting nuclear factor-kappaB

This study aimed to investigate the effect and underlying mechanism of Arginyl-glutamine (AG) dipeptide on dextran sulfate sodium (DSS)-induced colitis byin vivoandin vitromodels.