Age-related changes in metabolites in young donor livers and old recipient sera after liver transplantation from young to old rats

Molecular mechanisms of aging and anti-aging strategies

Aging is a complex and multifaceted process involving a variety of interrelated molecular mechanisms and cellular systems. Phenotypically, the biological aging process is accompanied by a gradual loss of cellular function and the systemic deterioration of multiple tissues, resulting in susceptibility to aging-related diseases. Emerging evidence suggests that aging is closely associated with telomere attrition, DNA damage, mitochondrial dysfunction, loss of nicotinamide adenine dinucleotide levels, impaired macro-autophagy, stem cell exhaustion, inflammation, loss of protein balance, deregulated nutrient sensing, altered intercellular communication, and dysbiosis. These age-related changes may be alleviated by intervention strategies, such as calorie restriction, improved sleep quality, enhanced physical activity, and targeted longevity genes. In this review, we summarise the key historical progress in the exploration of important causes of aging and anti-aging strategies in recent decades, which provides a basis for further understanding of the reversibility of aging phenotypes, the application prospect of synthetic biotechnology in anti-aging therapy is also prospected.

Arachidonic acid in aging: New roles for old players

BACKGROUND

Arachidonic acid (AA), one of the most ubiquitous polyunsaturated fatty acids (PUFAs), provides fluidity to mammalian cell membranes. It is derived from linoleic acid (LA) and can be transformed into various bioactive metabolites, including prostaglandins (PGs), thromboxanes (TXs), lipoxins (LXs), hydroxy-eicosatetraenoic acids (HETEs), leukotrienes (LTs), and epoxyeicosatrienoic acids (EETs), by different pathways. All these processes are involved in AA metabolism. Currently, in the context of an increasingly visible aging world population, several scholars have revealed the essential role of AA metabolism in osteoporosis, chronic obstructive pulmonary disease, and many other aging diseases.

AIM OF REVIEW

Although there are some reviews describing the role of AA in some specific diseases, there seems to be no or little information on the role of AA metabolism in aging tissues or organs. This review scrutinizes and highlights the role of AA metabolism in aging and provides a new idea for strategies for treating aging-related diseases.

KEY SCIENTIFIC CONCEPTS OF REVIEW

As a member of lipid metabolism, AA metabolism regulates the important lipids that interfere with the aging in several ways. We present a comprehensivereviewofthe role ofAA metabolism in aging, with the aim of relieving the extreme suffering of families and the heavy economic burden on society caused by age-related diseases. We also collected and summarized data on anti-aging therapies associated with AA metabolism, with the expectation of identifying a novel and efficient way to protect against aging.

The biological mechanism and emerging therapeutic interventions of liver aging

Research on liver aging has become prominent and has attracted considerable interest in uncovering the mechanism and therapeutic targets of aging to expand lifespan. In addition, multi-omics studies are widely used to perform further mechanistic investigations on liver aging. In this review, we illustrate the changes that occur with aging in the liver, present the current models of liver aging, and emphasize existing multi-omics studies on liver aging. We integrated the multi-omics data of enrolled studies and reanalyzed them to identify key pathways and targets of liver aging. The results indicated that C-X-C motif chemokine ligand 9 (Cxcl9) was a regulator of liver aging. In addition, we provide a flowchart for liver aging research using multi-omics analysis and molecular experiments to help researchers conduct further research. Finally, we present emerging therapeutic treatments that prolong lifespan. In summary, using cells and animal models of liver aging, we can apply a multi-omics approach to find key metabolic pathways and target genes to mitigate the adverse effects of liver aging.

Untargeted metabolomics reveals dynamic changes in metabolic profiles of rat supraspinatus tendon at three different time points after diabetes induction

Objective

To investigate the dynamic changes of metabolite composition in rat supraspinatus tendons at different stages of diabetes by untargeted metabolomics analysis.

Methods

A total of 80 Sprague-Dawley rats were randomly divided into normal (NG, n = 20) and type 2 diabetes mellitus groups (T2DM, n = 60) and subdivided into three groups according to the duration of diabetes: T2DM-4w, T2DM-12w, and T2DM-24w groups; the duration was calculated from the time point of T2DM rat model establishment. The three comparison groups were set up in this study, T2DM-4w group vs. NG, T2DM-12w group vs. T2DM-4w group, and T2DM-24w group vs. T2DM-12w group. The metabolite profiles of supraspinatus tendon were obtained using tandem mass spectrometry. Metabolomics multivariate statistics were used for metabolic data analysis and differential metabolite (DEM) determination. The intersection of the three comparison groups' DEMs was defined as key metabolites that changed consistently in the supraspinatus tendon after diabetes induction; then, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed.

Results

T2DM-4w group vs. NG, T2DM-12w group vs. T2DM-4w group, and T2DM-24w group vs. T2DM-12w group detected 94 (86 up-regulated and 8 down-regulated), 36 (13 up-regulated and 23 down-regulated) and 86 (24 up-regulated and 62 down-regulated) DEMs, respectively. Seven key metabolites of sustained changes in the supraspinatus tendon following induction of diabetes include D-Lactic acid, xanthine, O-acetyl-L-carnitine, isoleucylproline, propoxycarbazone, uric acid, and cytidine, which are the first identified biomarkers of the supraspinatus tendon as it progresses through the course of diabetes. The results of KEGG pathway enrichment analysis showed that the main pathway of supraspinatus metabolism affected by diabetes (p < 0.05) was purine metabolism. The results of the KEGG metabolic pathway vs. DEMs correlation network graph revealed that uric acid and xanthine play a role in more metabolic pathways.

Conclusion

Untargeted metabolomics revealed the dynamic changes of metabolite composition in rat supraspinatus tendons at different stages of diabetes, and the newly discovered seven metabolites, especially uric acid and xanthine, may provide novel research to elucidate the mechanism of diabetes-induced tendinopathy.

Comparative plasma and urine metabolomics analysis of juvenile and adult canines

Background and aims

The metabolomic profile of a biofluid can be affected by age, and thus provides detailed information about the metabolic alterations in biological processes and reflects the in trinsic rule regulating the growth and developmental processes.

Methods

To systemically investigate the characteristics of multiple metabolic profiles associated with canine growth, we analyzed the metabolomics in the plasma and urine samples from 15 young and 15 adult beagle dogs via UHPLC-Q-TOFMS-based metabolomics. Blood routine and serum biochemical analyses were also performed on fasting blood samples.

Results

The metabolomics results showed remarkable differences in metabolite fingerprints both in plasma and urine between the young and adult groups. The most obvious age-related metabolite alterations include decreased serumlevels of oxoglutaric acid and essential amino acids and derivatives but increased levels of urine levels of O-acetylserine. These changes primarily involved in amino acid metabolism and bile secretion pathways. We also found that the levels of glutamine were consistently higher in both serum and urine of adults, while N-acetylhistamine and uracil concentrations were much lower in the adult group compared to younger ones.

Conclusion

Our study provides a whole metabolic profile of serum and urine characteristics of young and adult canines, identifying several metabolites that were significantly associated with age change, which provides theoretical support for the nutrition-related research and age-related homeostasis maintenance in dogs.

Metabolomics Study of Shaoyao Plants Decoction on the Proximal and Distal Colon in Mice with Dextran Sulfate Sodium-Induced Colitis by UPLC-Q-TOF-MS

Purpose

Shaoyao decoction (SYD) is a traditional Chinese medicine used to treat ulcerative colitis (UC). The exact mechanism of action of SYD in UC treatment is still unclear. Here, we examined the therapeutic effects of SYD in mice with dextran sulfate sodium (DSS)-induced colitis and explored the underlying mechanism.

Methods

The experimental group was divided into normal control, UC, and SYD treatment groups. The UC model of C57BL/6 mice was induced using 3% (w/v) DSS for 7 days. SYD was orally administered for 7 days. The proximal and distal colonic metabolic profiles were detected using quadrupole-time-of-flight mass spectrometry-based untargeted metabolomics.

Results

SYD significantly increased weight, reduced disease activity index scores, and ameliorated colon length shortening and pathological damage in mice. In the distal colon, SYD increased the abundance of phosphatidic acid and lysophosphatidylethanolamine and decreased the abundance of lactosylceramide, erythrodiol 3-palmitate, and lysophosphatidylcholine. In the proximal colon, SYD increased the abundance of palmitic acid, cyclonormammein, monoacylglyceride, 13S-hydroxyoctadecadienoic acid, and ceanothine C and decreased the abundance of tetracosahexaenoic acid, phosphatidylserine, and diglyceride.

Conclusion

Our findings revealed that SYD could alleviate UC by regulating metabolic dysfunction, which provides a reference for further studies on SYD.

Mitochondrial Autophagy in Ischemic Aged Livers

Mitochondrial autophagy (mitophagy) is a central catabolic event for mitochondrial quality control. Defective or insufficient mitophagy, thus, can result in mitochondrial dysfunction, and ultimately cell death. There is a strong causal relationship between ischemia/reperfusion (I/R) injury and mitochondrial dysfunction following liver resection and transplantation. Compared to young patients, elderly patients poorly tolerate I/R injury. Accumulation of abnormal mitochondria after I/R is more prominent in aged livers than in young counterparts. This review highlights how altered autophagy is mechanistically involved in age-dependent hypersensitivity to reperfusion injury.

Metabolome profiling in the study of aging processes

Aging of a living organism is closely related to systemic metabolic changes. But due to the multilevel and network nature of metabolic pathways, it is difficult to understand these connections. Today, this problem is solved using one of the main approaches of metabolomics — untargeted metabolome profiling. The purpose of this publication is to systematize the results of metabolomic studies based on such profiling, both in animal models and in humans.

Multi-omics profiling and biochemical assays reveal the acute toxicity of environmental related concentrations of Di-(2-ethylhexyl) phthalate (DEHP) on the gill of crucian carp (Carassius auratus)

Di-(2-ethylhexyl) phthalate (DEHP) is one of the most extensively utilized plasticizers in the plastic manufacturing process. It is widely used in various fields due to its low cost and excellent effect. Although there is evidence that DEHP is harmful to animal and human health, DEHP-induced gill toxicity in aquatic organisms is inconclusive, and its mechanism has not been fully elucidated. Here, we investigated the effects of DEHP acute exposure on crucian carp gills at environmentally relevant concentrations of 20, 100, and 500 μg/L. Multi-omics profiling and biochemical assays were employed to characterize the potential toxicological mechanisms. The results showed that acute exposure to 100 and 500 μg/L of DEHP leads to oxidative stress in gills, as evidenced by overproduction of reactive oxygen species (ROS), increased antioxidant enzyme activity, and the transformation of glutathione from reduced to oxidized form, resulting in lipid peroxidation. Integrative analysis of transcriptomics and metabolomics indicated that increased purine metabolism was the potential source of increased ROS. Moreover, lipid metabolism disorder, including arachidonic acid metabolism, induces inflammation. Further, DEHP causes the imbalance of the CYP enzyme system in the gill, and DEHP-induced gill toxicity in crucian carp was associated with interference with CYP450 homeostasis. Taken together, this study broadens the molecular understanding of the DEHP-induced gill toxicity in aquatic organisms and provides novel perspectives for assessing the effects of DEHP on target and non-target aquatic organisms in the environment.

Integrated Metabonomics and Network Pharmacology to Reveal the Action Mechanism Effect of Shaoyao Decoction on Ulcerative Colitis

Background

Traditional Chinese medicine (TCM) has the advantage of multi-component and multi-target, which becomes a hot spot in the treatment of numerous diseases. Shaoyao decoction (SYD) is a TCM prescription, which is mainly used to treat damp-heat dysentery clinically, with small side effects and low cost. However, its mechanism remains elusive. The purpose of this study is to explore the mechanism of SYD in the treatment of mice with ulcerative colitis (UC) induced by dextran sulfate sodium (DSS) through metabolomics and network pharmacology, and verify through molecular docking and immunohistochemistry, so as to provide a scientific basis for the role of SYD in the treatment of UC.

Materials and Methods

Firstly, DSS-induced UC models were established and then untargeted metabolomics analysis of feces, livers, serum and urine was performed to determine biomarkers and metabolic pathways closely related to the role of SYD. Besides, network pharmacology was applied to screen the active components and UC-related targets, which was verified by molecular docking. Finally, metabonomics and network pharmacology were combined to draw the metabolite-pathway-target network and verified by immunohistochemistry.

Results

Metabolomics results showed that a total of 61 differential metabolites were discovered in SYD-treated UC with 3 main metabolic pathways containing glycerophospholipid metabolism, sphingolipid metabolism and biosynthesis of unsaturated fatty acids, as well as 8 core targets involving STAT3, IL1B, IL6, IL2, AKT1, IL4, ICAM1 and CCND1. Molecular docking demonstrated that the first five targets had strong affinity with quercetin, wogonin, kaempferol and baicalein. Combined with metabolomics and network pharmacology, sphingolipid signaling pathway, PI3K/AKT-mTOR signaling pathway and S1P3 pathway were identified as the main pathways.

Conclusion

SYD can effectively ameliorate various symptoms and alleviate intestinal mucosal damage and metabolic disorder in DSS induced UC mice. Its effect is mainly related to sphingolipid metabolism, PI3K/AKT-mTOR signaling pathway and S1P3 pathway.

Metabolome Profiling in Aging Studies

Organism aging is closely related to systemic metabolic changes. However, due to the multilevel and network nature of metabolic pathways, it is difficult to understand these connections. Today, scientists are trying to solve this problem using one of the main approaches of metabolomics-untargeted metabolome profiling. The purpose of this publication is to review metabolomic studies based on such profiling, both in animal models and in humans. This review describes metabolites that vary significantly across age groups and include carbohydrates, amino acids, carnitines, biogenic amines, and lipids. Metabolic pathways associated with the aging process are also shown, including those associated with amino acid, lipid, and energy metabolism. The presented data reveal the mechanisms of aging and can be used as a basis for monitoring biological age and predicting age-related diseases in the early stages of their development.

Plasma Metabolomics Identifies the Dysregulated Metabolic Profile of Primary Immune Thrombocytopenia (ITP) Based on GC-MS

ITP is a common autoimmune bleeding disorder with elusive pathogenesis. Our study was implemented to profile the plasma metabolic alterations of patients diagnosed with ITP, aiming at exploring the potential novel biomarkers and partial mechanism of ITP. The metabolomic analysis of plasma samples was conducted using GC-MS on 98 ITP patients and 30 healthy controls (HCs). Age and gender matched samples were selected to enter the training set or test set respectively. OPLS-DA, t-test with FDR correction and ROC analyses were employed to screen out and evaluate the differential metabolites. Possible pathways were enriched based on metabolomics pathway analysis (MetPA). A total of 85 metabolites were investigated in our study and 17 differential metabolites with diagnostic potential were identified between ITP patients and HCs. MetPA showed that the metabolic disorders of ITP patients were mainly related to phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism and glyoxylate and dicarboxylate metabolism. Additionally, we discriminated 6 differential metabolites and 5 enriched pathways in predicting the resistance to glucocorticoids in chronic ITP patients. The distinct metabolites discovered in our study could become novel biomarkers for the auxiliary diagnosis and prognosis prediction of ITP. Besides, the dysregulated pathways might contribute to the development of ITP.

Decline in Liver Mitochondria Metabolic Function Is Restored by Hochuekkito Through Sirtuin 1 in Aged Mice With Malnutrition

Malnutrition impairs basic daily activities and leads to physical frailty, which is aggravated in the elderly compared with young adults. It is also well-known that the elderly are more vulnerable to metabolic stress. Therefore, in this study, using a food restricted (FR) mouse, we aimed to evaluate the effect of aging on locomotor activity and liver metabolic function. Further, we also investigated the involvement of hepatic mitochondria in liver metabolic function during aging, as well as the therapeutic benefit of the traditional Japanese medicine, hochuekkito (HET). Our findings indicated that following food restriction provided as 30% of ad libitum intake for 5 days, the locomotor activity was lower in 23–26-month-old (aged) mice than in 9-week-old (young) mice. Further, compared with young mice, aged mice exhibited significant decreases in the levels of metabolites related to the urea cycle, mitochondrial function, and anti-oxidative stress. The livers of the aged mice also showed a greater decrease in mitochondrial DNA copy number than young mice. Furthermore, the gene expression levels of sirtuin 1 (SIRT1) and mitochondrial biogenesis-related regulators were attenuated in aged mice. However, these changes were partially restored by HET treatment, which also improved locomotor activity, and combined treatment with alanine resulted in more significant effects in this regard. Therefore, our findings suggested that the decrease in locomotor activity in aged FR mice was associated with a decline in the metabolic function of hepatic mitochondria via decreased SIRT1 expression, which was restored by HET treatment. This implies that enhancing the metabolic function of liver mitochondria can contribute to alleviating energy deficiency in the elderly.

Age-related changes in metabolites in young donor livers and old recipient sera after liver transplantation from young to old rats

Liver ageing not only damages liver function but also harms systemic metabolism. To better understand the mechanisms underlying liver ageing, we transplanted the livers of young rats to young and old rats and performed untargeted metabolomics to detect changes in the metabolites in the liver tissues and sera. A total of 153 metabolites in the livers and 83 metabolites in the sera were different between the old and young rats that did not undergo liver transplantation; among these metabolites, 7 different metabolites were observed in both the livers and sera. Five weeks after liver transplantation, the levels of 25 metabolites in the young donor livers were similar to those in the old rats, and this result probably occurred due to the effect of the whole‐body environment of the older recipients on the young livers. The 25 altered metabolites included organic acids and derivatives, lipids and lipid‐like molecules, etc. In the sera, the differences in 78 metabolites, which were significant between the young and old rats, were insignificant in the old recipient rats and made the metabolic profile of the old recipients more similar to that of the young recipients. Finally, combining the above metabolomic data with the transcriptomic data from the GEO, we found that the altered metabolites and genes in the liver were enriched in 9 metabolic pathways, including glycerophospholipid, arachidonic acid, histidine and linoleate. Thus, this study revealed important age‐related metabolites and potential pathways as well as the interaction between the liver and the whole‐body environment.