Effects of Different Methionine Sources on Methionine Metabolism in the IPEC-J2 Cells

Mapping the gut microbial structural variations in healthy aging within the Chinese population

Mapping gut microbial structural variants (SVs) during human aging may provide fundamental knowledge and mechanistic understanding of the gut microbiome's relationship with healthy aging. We characterize gut microbial SVs from 3,230 Chinese participants, identifying key SVs associated with aging, healthy aging, and age-related chronic diseases. Our findings reveal a pattern of copy number loss in aging-related SVs, with 35 core SVs consistently detected. Additionally, eight SVs distinguish healthy from unhealthy aging, regardless of age. Notably, a 3-kbp deletion SV of Bifidobacterium pseudocatenulatum, encoding plant polysaccharide degradation, is regulated by plant-based diet and contributes to healthy aging through bile acid metabolism. Our analysis also connects SVs to age-related diseases, such as chronic kidney disease, via genes in the methionine-homocysteine pathway. This study deepens our understanding of the gut microbiome's role in aging and could inform future efforts to enhance lifespan and healthspan.

Methionine Source and Level Modulate Gut pH, Amino Acid Transporters and Metabolism Related Genes in Broiler Chickens

This study determined the effects of two methionine (Met) sources at three total sulfur amino acids (TSAA) to lysine ratios (TSAA/Lys) on gut pH, digestive enzyme activity, amino acid transporter expression, and Met metabolism of broilers. The birds were randomly assigned to a 2 × 3 factorial arrangement with Met sources (dl-Met and dl-2-hydroxy-4-(methylthio)-butanoic acid (OH-Met)) and TSAA/Lys (0.58, 0.73, and 0.88) from 1 to 21 days. The results demonstrated that dl-Met and OH-Met supported the same growth performance, but high TSAA/Lys ratio reduced the feed intake and body weight (P < 0.05). OH-Met reduced the crop chyme pH and enhanced the jejunal lipase activity (P < 0.05). ATB0,+ expression decreased with increased dl-Met levels in the duodenum; the low TSAA/Lys ratio induced a stronger mRNA expression of basolateral Met transporters. OH-Met resulted in an increase of cystathionine β-synthase expression in the liver and a decrease in serum homocysteine levels at middle TSAA/Lys ratio compared with dl-Met treatment (P < 0.05). In conclusion, two Met sources support the same growth, but OH-Met acidified the crop chyme. The investigated transporter transcripts differed significantly along the small intestine. At the middle TSAA/Lys ratio, OH-Met showed a higher metabolic tendency of the trans-sulfuration pathway compared with dl-Met.

Effects of Methionine Restriction from Different Sources on Sperm Quality in Aging Mice

Decreased sperm quality causing poor pregnancy outcomes in aging males is a common problem. The aim of this study was to investigate the ameliorative effect of methionine restriction on sperm quality in aging mice, using methionine or 2-hydroxy-4-(methylthio)butanoate (HMTBA) as the methionine source, with a view to providing nutritional strategies to mitigate the decline in sperm quality in aging livestock. Fifty-one 6-week-old male mice were randomly divided into four groups: the non-aging group (NA, 0.86% methionine), the control diet group (CD, 0.86% methionine), the methionine-restricted group (MR, 0.17% methionine) and the HMTBA-restricted group (HR, 0.17% methionine). The mice in the CD, MR and HR groups were injected with a daily dose of 0.25 mL/20 g body weight of 10% D-galactose to establish an aging model. The test period was 42 days. The results showed that aging mice in the CD group had impaired testicular morphology and significantly decreased sperm quality compared to those in the NA group. Aging mice in the MR and HR groups showed attenuated impaired testicular morphology and improved sperm quality, especially sperm acrosomal integrity and membrane integrity, compared to mice in the CD group. In addition, mice in the MR and HR groups had reduced testicular inflammation and oxidative stress, increased spermidine levels, and reduced sperm RNA N6-methyladenosine (m6A) and DNA 5-methylcytosine (5mC) levels. Spermidine levels were positively correlated, whereas sperm RNA m6A and DNA 5mC levels were negatively correlated with sperm quality parameters. Our study suggests that methionine restriction alleviates the decline in sperm quality in aging mice, which may be related to changes in methionine metabolism and inhibition of sperm DNA and RNA methylation.

Supramolecular Pd@methioine-EDTA-chitosan nanocomposite: an effective and recyclable bio-based and eco-friendly catalyst for the green Heck cross-coupling reaction under mild conditions

Supramolecular palladium(ii) supported on modified chitosan by dl-methionine using an ethylenediaminetetraacetic acid linker (Pd@MET-EDTA-CS) was designed and prepared through a simple procedure. The structure of this novel supramolecular nanocomposite was characterized by different spectroscopic, microscopic and analytical techniques including FTIR, EDX, XRD, FESEM, TGA, DRS, TEM, AA, and BET. The obtained bio-based nanomaterial was successfully investigated, as a highly efficient and green heterogeneous catalyst, in the Heck cross-coupling reaction (HCR) for the synthesis of various valuable biologically active cinnamic acid ester derivatives from the corresponding aryl halides using several acrylates. Indeed, aryl halides containing I or Br survived very well under optimized conditions to afford the corresponding products compared to the substrates with Cl. The prepared Pd@MET-EDTA-CS nanocatalyst promoted the HCR in high to excellent yields and short reaction times with minimum Pd loading (0.0027 mol%) on its structure as well as without any leaching occurring during the process. The recovery of the catalyst was performed by simple filtration and the catalytic activity remained approximately constant after five runs for the model reaction.

A systematic review of metabolism of methionine sources in animals: One parameter does not convey a comprehensive story

The goal of this review article, based on a systematic literature search, is to critically assess the state of knowledge and experimental methodologies used to delineate the conversion and metabolism of the 2 methionine (Met) sources DL-methionine (DL-Met) and DL-2-hydroxy-4-(methylthio) butanoic acid (HMTBa). The difference in the chemical structures of HMTBa and DL-Met indicates that these molecules are absorbed and metabolized differently in animals. This review explores the methodologies used to describe the 2-step enzymatic conversion of the 3 enantiomers (D-HMTBa, L-HMTBa and D-Met) to L-Met, as well as the site of conversion at the organ and tissue levels. Extensive work was published documenting the conversion of HMTBa and D-Met into L-Met and, consequently, the incorporation into protein using a variety of in vitro techniques, such as tissue homogenates, cell lines, primary cell lines, and everted gut sacs of individual tissues. These studies illustrated the role of the liver, kidney, and intestine in the conversion of Met precursors into L-Met. A combination of in vivo studies using stable isotopes and infusions provided evidence of the wide conversion of HMTBa to L-Met by all tissues and how some tissues are net users of HMTBa, whereas others are net secreters of L-Met derived from HMTBa. Conversion of D-Met to L-Met in organs other than the liver and kidney is poorly documented. The methodology cited in the literature to determine conversion efficiency ranged from measurements of urinary, fecal, and respiratory excretion to plasma concentration and tissue incorporation of isotopes after intraperitoneal and oral infusions. Differences observed between these methodologies reflect differences in the metabolism of Met sources rather than differences in conversion efficiency. The factors affecting conversion efficiency are explored in this paper and are mostly associated with extreme dietary conditions, such as noncommercial crystalline diets that are very deficient in total sulfur amino acids with respect to requirements. Implications in the diversion of the 2 Met sources toward transsulfuration over transmethylation pathways are discussed. The strengths and weaknesses of some methodologies used are discussed in this review. From this review, it can be concluded that due to the inherent differences in conversion and metabolism of the 2 Met sources, the experimental methodologies (e.g., selecting different organs at different time points or using diets severely deficient in Met and cysteine) can impact the conclusions of the study and may explain the apparent divergences of conclusion found in the literature. It is recommended when conducting studies or reviewing the literature to properly select the experimental models that allow for differences in how the 2 Met precursors are converted to L-Met and metabolized by the animal to enable a proper comparison of their bioefficacy.

Dietary Isoleucine and Valine: Effects on Lipid Metabolism and Ureagenesis in Pigs Fed with Protein Restricted Diets

A mixture of valine (Val) and isoleucine (Ile) not only decreases the negative impact of very low protein (VLP) diets on the growth of pigs, but also influences the nitrogen (N) balance and lipid metabolism; however, the underlying pathways are not well understood. This study aimed to investigate the effect of dietary Val and Ile on lipogenesis, lipolysis, and ureagenesis under protein restriction. After one week of acclimation, forty three-week-old pigs were randomly assigned to following dietary treatments (n = 8/group) for 5 weeks: positive control (PC): normal protein diet; negative control (NC): VLP diet; HV: NC supplemented with Val; HI: NC supplemented with Ile; and HVI: NC supplemented with both Val and Ile. HVI partially improved the body weight and completely recovered the feed intake (FI) of pigs fed with NC. HVI increased thermal radiation and improved the glucose clearance. HVI had a lower blood triglyceride than PC and blood urea N than NC. NC and HV promoted lipogenesis by increasing the transcript of fatty acid synthase (FAS) in the liver and lipoprotein lipase (LPL) in adipose tissue but reducing hormone-sensitive lipase (HSL) in the liver. HVI reduced the increased rate of lipogenesis induced by the NC group through normalizing the mRNA abundance of hepatic FAS, sterol regulatory element binding transcription factor 1, and HSL and LPL in adipose tissue. NC, HV, HI, and HVI reduced the ureagenesis by decreasing the protein abundance of carbamoyl phosphate synthetase I, ornithine transcarboxylase, and arginosuccinate lyase in the liver. Overall, HVI improved the growth, FI, and glucose clearance, and decreased the rate of lipogenesis induced by VLP diets.

How Different Dietary Methionine Sources Could Modulate the Hepatic Metabolism in Rainbow Trout?

In aquafeeds in which plant proteins are used to replace fishmeal, exogenous methionine (Met) sources are demanded to balance the amino acid composition of diets and meet the metabolic fish requirements. Nonetheless, since different synthetic Met sources are commercially available, it is important to determine their bioavailability and efficacy. To address this issue, we conducted a two-month feeding trial with rainbow trout (Oncorhynchus mykiss), which were fed diets supplemented with five different forms of Met: Met-Met, L-Met, HMTBa, DL-Met, and Co DL-Met. No differences in growth performance were found in trout fed with different Met forms, but changes in the whole-body composition were found. In particular, Met-Met and L-Met promoted a significant body lipid reduction, whereas the protein retention was significantly increased in fish fed with HMTBa and Co DL-Met. The latter affected the hepatic Met metabolism promoting the trans-sulfuration pathway through the upregulation of CBS gene expression. Similarly, the L-Met enhanced the remethylation pathway through an increase in BHMT gene expression to maintain the cellular demand for Met. Altogether, our findings suggest an optimal dietary intake of all tested Met sources with similar promoting effects on fish growth and hepatic Met metabolism. Nevertheless, the mechanisms underlying these effects warrant further investigation.

Effects on the Cell Barrier Function of L-Met and DL-HMTBA Is Related to Metabolic Characteristics and m6A Modification

Methionine is a substrate for protein synthesis and participates in many other biological events via its metabolism. We have previously demonstrated significant differences in the metabolism of L-methionine (L-Met) and its precursor DL-2-hydroxy-4-methylthiobutyric acid (DL-HMTBA) in IPEC-J2 cells. When DL–HMTBA is added to the diet, intracellular methionine (Met) sources also contain the natural form of L-Met. Then, what is the effect on Met metabolism when these two Met sources exist simultaneously? Moreover, the effects of metabolic differences on cell function remain unclear. In this study, it was found that when the proportion of L-Met to DL–HMTBA was ≤ 40%:60%, Met transmethylation was promoted and when the proportion of L-Met to DL-HMTBA was ≤ 85%:15%, Met trans-sulfuration and regeneration were improved. In addition, DL-HMTBA improved the cell barrier function when the ratio of L-Met to DL-HMTBA was ≤ 40%:60%. This finding may be due to the decrease in the proportion of S-adenosylmethionine to S-adenosylhomocysteine and mRNA N⁶-methyladenosine (m⁶A) levels, which increase the mRNA stability and protein expression of tight junction zona occludens-1. To sum up, the effects of L-Met and DL–HMTBA on Met metabolism, especially transmethylation, suggest that DL–HMTBA has the potential to influence the intestinal barrier function of animals through epigenetic processes.

Effect of gestation dietary methionine-to-lysine ratio on methionine metabolism and antioxidant ability of high-prolific sows

The uptake and metabolism of methionine (Met) are critical for epigenetic regulation, redox homeostasis, and embryo development. Our previous study showed that appropriate supplementation of dietary Met promoted the birth weight and placental angiogenesis of high-prolific sows. To further explore the metabolic effect of Met on pregnant sows, we have evaluated the influence of dietary Met level on Met metabolism, and the relationship between metabolites of Met and reproductive performance, antioxidant ability, and placental angiogenesis throughout the gestation of high-prolific sows. Sixty sows (the 3rd parity, Large White) were randomly divided into 5 groups that were fed diets with standardized ileal digestible (SID) methionine-to-lysine (Met:Lys) ratios of 0.27 (control), 0.32, 0.37, 0.42, and 0.47 from the mating day (gestational d 0, G0d) until the farrowing day. HPLC-MS/MS analysis was used to simultaneously evaluate the metabolites related to Met, e.g. S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), homocysteine (Hcy), cysteine (Cys), and glutathione (GSH). The concentration of SAM and SAH in plasma had significant fluctuations, especially in late pregnancy. Increasing dietary Met supplementation significantly improved the plasma SAM and methylation potential (SAM-to-SAH ratio) at d 114 of pregnancy (G114d). Moreover, a positive association of the plasma SAM concentration at G114d was observed with the litter weight of born alive (P < 0.05; R 2 = 0.58). Furthermore, Hcy concentration in plasma was at the lowest level for 0.37 ratio group at G114d. However, it significantly increased during late pregnancy. Moreover, there were negative correlations between plasma Hcy concentration at G114d (P < 0.05) and the placental vascular density in the fold and stroma (P < 0.05). Compared with the control group, the expression of vascular endothelial growth factor-A (VEGF-A) in the placenta tissue of 0.37 ratio group increased significantly (P < 0.05). Collectively, these findings indicate that dietary Met:Lys ratio (0.37 to 0.57) in the pregnant diet dose not influence the antioxidant ability of the high-prolific sows; however, the improvement of fetal development and placental angiogenesis of high-prolific sows by supplementation of Met are closely associated to the key Met-related metabolite of SAM and Hcy, respectively.

Dietary Tryptophan Supplementation Alters Fat and Glucose Metabolism in a Low-Birthweight Piglet Model

Low birthweight (LBW) is associated with metabolic complications, such as glucose and lipid metabolism disturbances in early life. The objective of this study was to assess: (1) the effect of dietary tryptophan (Trp) on glucose and fat metabolism in an LBW piglet model, and (2) the role peripheral 5-hydroxytryptamine type 3 (5HT3) receptors in regulating the feeding behavior in LBW piglets fed with Trp-supplemented diets. Seven-day-old piglets were assigned to 4 treatments: normal birthweight-0%Trp (NBW-T0), LBW-0%Trp (LBW-T0), LBW-0.4%Trp (LBW-T0.4), and LBW-0.8%Trp (LBW-T0.8) for 3 weeks. Compared to LBW-T0, the blood glucose was decreased in LBW-T0.8 at 60 min following the meal test, and the triglycerides were lower in LBW-T0.4 and LBW-T0.8. Relative to LBW-T0, LBW-T0.8 had a lower transcript and protein abundance of hepatic glucose transporter-2, a higher mRNA abundance of glucokinase, and a lower transcript of phosphoenolpyruvate carboxykinase. LBW-T0.4 tended to have a lower protein abundance of sodium-glucose co-transporter 1 in the jejunum. In comparison with LBW-T0, LBW-T0.4 and LBW-T0.8 had a lower transcript of hepatic acetyl-CoA carboxylase, and LBW-T0.4 had a higher transcript of 3-hydroxyacyl-CoA dehydrogenase. Blocking 5-HT3 receptors with ondansetron reduced the feed intake in all groups, with a transient effect on LBW-T0, but more persistent effect on LBW-T0.8 and NBW-T0. In conclusion, Trp supplementation reduced the hepatic lipogenesis and gluconeogenesis, but increased the glycolysis in LBW piglets. Peripheral serotonin is likely involved in the regulation of feeding behavior, particularly in LBW piglets fed diets supplemented with a higher dose of Trp.

Relationship between serum concentration, functional parameters and cell bioenergetics in IPEC-J2 cell line

The foetal bovine serum (FBS) concentration could influence functional parameters of IPEC-J2 cells. IPEC-J2 is a non-transformed continuous epithelial cell line that represents an established in vitro model to study porcine gut inflammation and alterations of intestinal integrity. This cell line also represents a good translational model thanks to the high similitudes between pig and human gastrointestinal tract. With the aim to assess if the FBS-dependent functional variations are linked to the bioenergetic aspects, the addition of 5% and 10% FBS in the IPEC-J2 culture medium were tested. Doubling time and TEER measurement indicated that cells cultured at higher FBS dose grow faster and as a more compact monolayer. 10% FBS increases ATP production and mitochondrial oxidative phosphorylation (OxPhos) and does not affect glycolysis. Both at 5% and 10% FBS ATP production mainly comes from OxPhos and FBS concentration does not affect the cell respiration bioenergetic parameters. Noteworthy, IPEC-J2 treated with 5% and 10% FBS have a metabolic potential since both OxPhos and glycolysis increase by > 100% and < 50%, respectively in comparison with baseline metabolism. Moreover, glucose, fatty acids and glutamine constitute the preferred metabolic fuel for mitochondrial respiration at both FBS conditions tested. Accordingly, the cells flexibility to oxidize these substrates shows that IPEC-J2 mitochondria cannot maintain the basal ATP production without oxidizing all the substrates available irrespective of FBS concentration. To sum up, in IPEC-J2 cells OxPhos increases with the FBS-stimulated functional physiological parameters to fulfil ATP requirements.

MTHFR polymorphisms (rs1801133) and systemic lupus erythematosus risk: A meta-analysis

BACKGROUND

The relationship between MTHFR (5, 10-methylene tetrahydrofolate reductase) gene polymorphisms and Systemic Lupus Erythematosus (SLE) has been wildly studied, but the results are still conflicting. Therefore, the purpose of this meta and pooled analysis was to identify the role of the MTHFR SNP (single nucleotide polymorphism, rs1801133) in SLE in a large sample of subjects and to assess the risk of SLE.

METHODS

Data were collected from EMBASE, PubMed and China National Knowledge Infrastructure from inception to August, 2019. Summary odds ratio (OR) with 95% confidence interval (CI) was applied to assess the association. Subgroup and sensitivity analysis were performed to assess the potential sources of heterogeneity of the pooled estimation.

RESULTS

We identified seven eligible studies involving 882 cases and 991 controls. MTHFR rs1801133 T carrier was significantly associated with increased risk of SLE when comparing to C allele [ORs were 1.766 (1.014-3.075) for T carrier vs CC, P = .04]. Furthermore, the results of the subgroup analysis by genotyping methods suggested that T allele significantly contributed to the risk of SLE for both by polymerase chain reaction-TaqMan (PCR-TaqMan) [10.111 (2.634-38.813) for TT vs CC, 3.467 (1.324-9.078) for CT vs CC and 3.744 (1.143-12.264) for TT vs C carrier]. Also the results of the subgroup analysis by ethnicity suggested that T allele significantly contributed to the risk of SLE for Asians [9.679 (4.444-21.082) for TT vs CC, 5.866 (3.021-11.389) for T carrier vs CC and 8.052 (3.861-16.795) for TT vs C carrier].

CONCLUSION

This cumulative meta-analysis showed that the MTHFR SNP (rs1801133) contributed to susceptibility of SLE. However, more multicentre well-designed case-control studies and larger sample sizes are exceedingly required to validate our findings in the future.