Alanyl-Glutamine Protects against Lipopolysaccharide-Induced Liver Injury in Mice via Alleviating Oxidative Stress, Inhibiting Inflammation, and Regulating Autophagy

Effects of Alanyl-Glutamine Dipeptide Supplementation on Growth Performance, Nutrient Digestibility, Digestive Enzyme Activity, Immunity, and Antioxidant Status in Growing Laying Hens

Alanyl-glutamine (Aln-Gln), a highly soluble and stable Glutamine-dipeptide, is known to improve the performance of poultry birds. This study aimed to investigate the effect of Aln-Gln during the rearing period on growth performance, nutrient digestibility, digestive enzyme activity, immunity, antioxidant status and relative gene expression of Hy-Line brown hens. A total of 480 healthy day-old Hy-line brown chicks with similar body weights were randomly divided into four dietary groups (8 replicates/group and 15 birds/replicate). Groups A, B, C and D were fed diets containing 0%, 0.1%, 0.2% and 0.3% Aln-Gln, respectively, for 6 weeks. The body weight (BW) and average daily gain (ADG) were higher in hens fed test diets compared with the control (p < 0.05). The feed conversion ratio (FCR) was better in test groups as compared to the control group (p < 0.05). The ADFI showed no significant difference between the groups. Dietary treatments had no effect on dry matter (DM), organic matter (OM) and crude fiber (CF) digestibility. The Aln-Gln also improved gross energy (GE) and crude protein (CP) digestibility (p < 0.05). It has also increased IgG levels in groups C and D. IgM levels were similar to the control in B, C and D. The Aln-Gln increased IL-1 in B and C, IL-2 in C and D, and IL-6 in all test groups (p < 0.05). The supplementation of Aln-Gln had no effect on serum antioxidant indices like CAT, MDA, GSH-PX, GSH, and SOD in 42-day-old growing hens. Aln-Gln supplementation had no significant effect (p > 0.05) on the activity of amylase and lipase, however, a significant improvement (p < 0.05) in the activities of trypsin and chymotrypsin was observed in the test groups. Supplemented Aln-Gln levels in the birds' diets led to an increase in the expression of genes related to growth factors (IGF-1, IGFBP-5), immune markers (IL-1, IL-2, IL-6) and antioxidant status (GSH-Px1), as compared to control group. Aln-Gln supplementation in Hy-Line brown hens during their growing period improved growth, nutrient digestibility, immunity and digestive enzymes activity. These findings suggest that Aln-Gln is a promising dietary additive for enhancing poultry performance.

Multi-omics and chemical profiling approaches to understand the material foundation and pharmacological mechanism of sophorae tonkinensis radix et rhizome-induced liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Sophorae tonkinensis Radix et Rhizoma (STR) is an extensively applied traditional Chinese medicine (TCM) in southwest China. However, its clinical application is relatively limited due to its hepatotoxicity effects.

AIM OF THE STUDY

To understand the material foundation and liver injury mechanism of STR.

MATERIALS AND METHODS

Chemical compositions in STR and its prototypes in mice were profiled by ultra-performance liquid chromatography coupled quadrupole-time of flight mass spectrometry (UPLC-Q/TOF MS). STR-induced liver injury (SILI) was comprehensively evaluated by STR-treated mice mode. The histopathologic and biochemical analyses were performed to evaluate liver injury levels. Subsequently, network pharmacology and multi-omics were used to analyze the potential mechanism of SILI in vivo. And the target genes were further verified by Western blot.

RESULTS

A total of 152 compounds were identified or tentatively characterized in STR, including 29 alkaloids, 21 organic acids, 75 flavonoids, 1 quinone, and 26 other types. Among them, 19 components were presented in STR-medicated serum. The histopathologic and biochemical analysis revealed that hepatic injury occurred after 4 weeks of intragastric administration of STR. Network pharmacology analysis revealed that IL6, TNF, STAT3, etc. were the main core targets, and the bile secretion might play a key role in SILI. The metabolic pathways such as taurine and hypotaurine metabolism, purine metabolism, and vitamin B6 metabolism were identified in the STR exposed groups. Among them, taurine, hypotaurine, hypoxanthine, pyridoxal, and 4-pyridoxate were selected based on their high impact value and potential biological function in the process of liver injury post STR treatment.

CONCLUSIONS

The mechanism and material foundation of SILI were revealed and profiled by a multi-omics strategy combined with network pharmacology and chemical profiling. Meanwhile, new insights were taken into understand the pathological mechanism of SILI.

Glutamine-derived peptides: Current progress and future directions

Glutamine, the most abundant amino acid in the body, plays a critical role in preserving immune function, nitrogen balance, intestinal integrity, and resistance to infection. However, its limited solubility and instability present challenges for its use a functional nutrient. Consequently, there is a preference for utilizing glutamine-derived peptides as an alternative to achieve enhanced functionality. This article aims to review the applications of glutamine monomers in clinical, sports, and enteral nutrition. It compares the functional effectiveness of monomers and glutamine-derived peptides and provides a comprehensive assessment of glutamine-derived peptides in terms of their classification, preparation, mechanism of absorption, and biological activity. Furthermore, this study explores the potential integration of artificial intelligence (AI)-based peptidomics and synthetic biology in the de novo design and large-scale production of these peptides. The findings reveal that glutamine-derived peptides possess significant structure-related bioactivities, with the smaller molecular weight fraction serving as the primary active ingredient. These peptides possess the ability to promote intestinal homeostasis, exert hypotensive and hypoglycemic effects, and display antioxidant properties. However, our understanding of the structure-function relationships of glutamine-derived peptides remains largely exploratory at current stage. The combination of AI based peptidomics and synthetic biology presents an opportunity to explore the untapped resources of glutamine-derived peptides as functional food ingredients. Additionally, the utilization and bioavailability of these peptides can be enhanced through the use of delivery systems in vivo. This review serves as a valuable reference for future investigations of and developments in the discovery, functional validation, and biomanufacturing of glutamine-derived peptides in food science.

Influence of the glutamate-glutamine cycle on valproic acid-associated hepatotoxicity in pediatric patients with epilepsy

INTRODUCTION

Although valproic acid is generally well tolerated, hepatotoxicity is a common side effect in patients receiving long-term treatment. However, the mechanisms underlying valproic acid-associated hepatotoxicity remain elusive.

METHODS

To investigate the mechanisms and explore the potential risk factors for valproic acid-associated hepatotoxicity, 165 age-matched pediatric patients were recruited for laboratory tests and glutamate-glutamine cycle analysis.

RESULTS

The concentration of glutamate in patients with hepatotoxicity was significantly greater than that in control patients, while the concentration of glutamine in patients with hepatotoxicity was significantly lower than that in control patients (P <0.05). In addition, the frequencies of the heterozygous with one mutant allele and homozygous with two mutant alleles genotypes in glutamate-ammonia ligase rs10911021 were significantly higher in the hepatotoxicity group than those in the control group (47.1 percent versus 32.5 percent, P = 0.010; 17.6 percent versus 5.2 percent, P = 0.001, respectively). Moreover, heterozygous carriers with one mutant allele and homozygous carriers with two mutant alleles genotypes of glutamate-ammonia ligase rs10911021 exhibited significant differences in the concentrations of glutamine and glutamate concentrations (P ˂ 0.001 and P = 0.001, respectively) and liver function indicators (activities of aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transferase, P <0.001, respectively). Furthermore, logistic regression analysis indicated that glutamate-ammonia ligase rs10911021 (P = 0.002, odds ratio: 3.027, 95 percent confidence interval, 1.521 - 6.023) and glutamate (P = 0.001, odds ratio: 2.235, 95 percent confidence interval, 1.369 - 3.146) were associated with a greater risk for hepatotoxicity, while glutamine concentrations were negatively associated with hepatotoxicity (P = 0.001, odds ratio: 0.711, 95 percent confidence interval, 0.629 - 0.804).

DISCUSSION

Understanding pharmacogenomic risks for valproic acid induced hepatotoxicity might help direct patient specific care. Limitations of our study include the exclusive use of children from one location and concomitant medication use in many patients.

CONCLUSION

Perturbation of the glutamate-glutamine cycle is associated with valproic acid-associated hepatotoxicity. Moreover, glutamate-ammonia ligase rs10911021, glutamate and glutamine concentrations are potential risk factors for valproic acid-associated hepatotoxicity.

A mixed antioxidant supplement improves cognitive function, and coordination in aged mice

Accumulation of oxidative damage increases the risk of several disorders. To prevent these diseases, people consume supplements. However, there is little evidence of the impact of supplement intake on cognitive function. Recently, frailty and sarcopenia have become serious issues, and these phenomena include a risk of mild cognitive impairment. In this study, aged mice were fed the combination supplement and cognitive and motor functions were measured. Following 1 month of treatment with the supplement, significant improvements in cognitive function and neuromuscular coordination were observed. Following 2 weeks of treadmill training, treatment with the supplement dramatically increased running distance compared to that in untreated normal aged mice. Serum indices such as triglyceride and total cholesterol were significantly decreased in the supplement-treated aged mice compared to untreated aged mice. These results indicate that the combination supplement may play a role in maintaining cognitive function, coordination ability and improving lipid metabolism.

Alanyl-Glutamine Dipeptide Attenuates Non-Alcoholic Fatty Liver Disease Induced by a High-Fat Diet in Mice by Improving Gut Microbiota Dysbiosis

Non-alcoholic fatty liver disease (NAFLD) manifests as a persistent liver ailment marked by the excessive buildup of lipids within the hepatic organ accompanied by inflammatory responses and oxidative stress. Alanyl-glutamine (AG), a dipeptide comprising alanine and glutamine, is commonly employed as a nutritional supplement in clinical settings. This research aims to evaluate the impact of AG on NAFLD triggered by a high-fat diet (HFD), while concurrently delving into the potential mechanisms underlying its effects. The results presented herein demonstrate a notable reduction in the elevated body weight, liver mass, and liver index induced by a HFD upon AG administration. These alterations coincide with the amelioration of liver injury and the attenuation of hepatic histological advancement. Furthermore, AG treatment manifests a discernible diminution in oil-red-O-stained regions and triglyceride (TG) levels within the liver. Noteworthy alterations encompass lowered plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC) concentrations, coupled with elevated high-density lipoprotein cholesterol (HDLC) concentrations. The mitigation of hepatic lipid accumulation resultant from AG administration is aligned with the downregulation of ACC1, SCD1, PPAR-γ, and CD36 expression, in conjunction with the upregulation of FXR and SHP expression. Concomitantly, AG administration leads to a reduction in the accumulation of F4/80-positive macrophages within the liver, likely attributable to the downregulated expression of MCP-1. Furthermore, AG treatment yields a decline in hepatic MDA levels and a concurrent increase in the activities of SOD and GPX. A pivotal observation underscores the effect of AG in rectifying the imbalance of gut microbiota in HFD-fed mice. Consequently, this study sheds light on the protective attributes of AG against HFD-induced NAFLD through the modulation of gut microbiota composition.

Multiplex gene knockout raises Ala-Gln production by Escherichia coli expressing amino acid ester acyltransferase

L-Alanyl-L-Glutamine (Ala-Gln) is a common parenteral nutritional supplement. In our previous study, the recombinant whole-cell catalyst Escherichia coli BL21(DE3) overexpressing α-amino acid ester acyltransferase (BPA) to produce Ala-Gln has high activity and has been applied to large-scale production experiments. However, the degradation of Ala-Gln is detected under prolonged incubation, and endogenous broad-spectrum dipeptidase may be the primary cause. In this study, a CRISPR-Cas9 method was used to target pepA, pepB, pepD, pepN, dpp, and dtp to knock out one or more target genes. The deletion combination was optimized, and a triple knockout strain BL21(DE3)-ΔpepADN was constructed. The degradation performance of the knockout chassis was measured, and the results showed that the degradation rate of Ala-Gln was alleviated by 48% compared with the control. On this basis, B_pADNPA (BPA-ΔpepADN) was built, and the production of Ala-Gln was 129% of the BPA's accumulation, proving that the ΔpepADN knockout conducive to the accumulation of dipeptide. This study will push forward the industrialization process of Ala-Gln production by whole-cell catalyst Escherichia coli expressing α-amino acid ester acyltransferase. KEY POINTS: • Endogenous dipeptidase knockout alleviates the degradation of Ala-Gln by the chassis • The balanced gene knockout combination is pepA, pepD, and pepN • The accumulation of Ala-Gln with B_pADNPA was 129% of the control.

Integrated Analysis of Gut Microbiome and Liver Metabolome to Evaluate the Effects of Fecal Microbiota Transplantation on Lipopolysaccharide/D-galactosamine-Induced Acute Liver Injury in Mice

Acute liver failure (ALF) refers to the occurrence of massive hepatocyte necrosis in a short time, with multiple complications, including inflammatory response, hepatic encephalopathy, and multiple organ failure. Additionally, effective therapies for ALF are lacking. There exists a relationship between the human intestinal microbiota and liver, so intestinal microbiota modulation may be a strategy for therapy of hepatic diseases. In previous studies, fecal microbiota transplantation (FMT) from fit donors has been used to modulate intestinal microbiota widely. Here, we established a mouse model of lipopolysaccharide (LPS)/D-galactosamine (D-gal) induced ALF to explore the preventive and therapeutic effects of FMT, and its mechanism of action. We found that FMT decreased hepatic aminotransferase activity and serum total bilirubin levels, and decreased hepatic pro-inflammatory cytokines in LPS/D-gal challenged mice (p < 0.05). Moreover, FMT gavage ameliorated LPS/D-gal induced liver apoptosis and markedly reduced cleaved caspase-3 levels, and improved histopathological features of the liver. FMT gavage also restored LPS/D-gal-evoked gut microbiota dysbiosis by modifying the colonic microbial composition, improving the abundance of unclassified_o_Bacteroidales (p < 0.001), norank_f_Muribaculaceae (p < 0.001), and Prevotellaceae_UCG-001 (p < 0.001), while reducing that of Lactobacillus (p < 0.05) and unclassified_f_Lachnospiraceae (p < 0.05). Metabolomics analysis revealed that FMT significantly altered LPS/D-gal induced disordered liver metabolites. Pearson's correlation revealed strong correlations between microbiota composition and liver metabolites. Our findings suggest that FMT ameliorate ALF by modulating gut microbiota and liver metabolism, and can used as a potential preventive and therapeutic strategy for ALF.

Alanyl-Glutamine Protects Mice against Methionine- and Choline-Deficient-Diet-Induced Steatohepatitis and Fibrosis by Modulating Oxidative Stress and Inflammation

Nonalcoholic steatohepatitis (NASH) is a common chronic liver disease with increasing prevalence rates over years and is associated with hepatic lipid accumulation, liver injury, oxidative stress, hepatic inflammation, and liver fibrosis and lack of approved pharmacological therapy. Alanyl-glutamine (Ala-Gln) is a recognized gut-trophic nutrient that has multiple pharmacological effects in the prevention of inflammation- and oxidative-stress-associated diseases. Nevertheless, whether Ala-Gln has a protective effect on NASH still lacks evidence. The aim of this study is to explore the influence of Ala-Gln on NASH and its underlying mechanisms. Here, C57BL/6 mice were fed a methionine- and choline-deficient (MCD) diet to establish the model of NASH, and Ala-Gln at doses of 500 and 1500 mg/kg were intraperitoneally administered to mice along with a MCD diet. The results showed that Ala-Gln treatment significantly attenuated MCD-induced hepatic pathological changes, lowered NAFLD activity score, and reduced plasma alanine transaminase (ALT), aspartate transaminase (AST) and lactate dehydrogenase (LDH) levels. Ala-Gln dramatically alleviated lipid accumulation in liver through modulating the expression levels of fatty acid translocase (FAT/CD36) and farnesoid X receptor (FXR). In addition, Ala-Gln exerted an anti-oxidant effect by elevating the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX). Moreover, Ala-Gln exhibited an anti-inflammatory effect via decreasing the accumulation of activated macrophages and suppressing the production of proinflammatory mediators. Notably, Ala-Gln suppressed the development of liver fibrosis in MCD-diet-fed mice, which may be due to the inhibition of hepatic stellate cells activation. In conclusion, these findings revealed that Ala-Gln prevents the progression of NASH through the modulation of oxidative stress and inflammation and provided the proof that Ala-Gln might be an effective pharmacological agent to treat NASH.