Excessive branched-chain amino acid accumulation restricts mesenchymal stem cell-based therapy efficacy in myocardial infarction

Imaging technology in tracking the intravital fate of transplanted stem cells

Stem cell therapy emerges as a promising alternative strategy for diseases that currently lack effective treatment options. Investigating the pharmacokinetic properties of stem cells, such as their survival, migration, differentiation, and engraftment dynamics, offers valuable insights for elucidating therapeutic mechanisms, refining treatment protocols, and ultimately enhancing therapeutic efficacy. Moreover, the pharmaceutical research of stem cell products is an essential prerequisite for regulatory approval. This contribution focus on the development of advanced imaging technologies for noninvasive monitoring the intravital fate of implanted stem cells, as well as the advantages and challenges of each imaging approach. Through comprehensive analysis of stem cell metabolic pathway, we identify critical barriers to clinical translation of stem cell therapy. In the end, we discuss future perspectives and opportunities in stem cell tracking and functional assessment.

Glucose-dependent insulinotropic polypeptide/glucagon-like peptide 1 receptor agonist tirzepatide promotes branched chain amino acid catabolism to prevent myocardial infarction in non-diabetic mice

AIMS

A novel dual glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1 receptor agonist, tirzepatide (LY3298176, TZP), has been developed to treat Type 2 diabetes mellitus (T2DM). In ischaemic heart diseases, TZP is involved in cardiac metabolic processes. However, its efficacy and safety in treating heart failure (HF) following myocardial infarction (MI) remain uncertain.

METHODS AND RESULTS

Herein, 12 week C57BL/6J mice were subjected to MI surgery, followed by administration of TZP. The effects of TZP on cardiac function and metabolism were thoroughly assessed by physiological, histological, and cellular analyses. Downstream effectors of TZP were screened through untargeted metabolomics analysis and molecular docking. Construct a lower branched chain amino acid (BCAA) diet model to determine whether TZP's cardioprotective effect is associated with reducing BCAA levels. Our results demonstrated that TZP reduced mortality following MI, decreased the infarct area, and attenuated cardiomyocyte necrosis. Pathological evaluation of cardiac tissues demonstrated increased fibrosis repair and decreased inflammatory infiltration. Mechanistically, untargeted metabolomics analysis uncovered a positive correlation between TZP and the BCAA catabolism pathway. The molecular docking verified that TZP could bind with branched-chain keto acid dehydrogenase E1 subunit α (BCKDHA). TZP reduced BCKDHA phosphorylation at S293, enhanced BCAA catabolism, and inhibited the activation of metabolism by activating rapamycin (mTOR) signalling pathway. Furthermore, mice fed a low-BCAA diet post-MI demonstrated reduced cardiomyocyte necrosis, increased fibrosis repair, and decreased inflammatory infiltration. These cardioprotective effects were further enhanced when used synergistically with TZP.

CONCLUSION

Taken together, our findings provide new perspectives on the unrecognized role of TZP in cardiac protection. TZP enhanced BCAA catabolism and attenuated BCAA/mTOR signalling pathway in MI mice. Consequently, this study may present novel therapeutic options for patients with HF.

3-D Sustained-Release Culture Carrier Alleviates Rat Intervertebral Disc Degeneration by Targeting STING in Transplanted Skeletal Stem Cells

The hypoxic and high-pressure microenvironment of the intervertebral discs poses a major challenge to the survival and therapeutic efficiency of exogenous stem cells. Therefore, improving the utilization efficiency and therapeutic effect of exogenous stem cells to delay intervertebral disc degeneration (IVDD) is of great importance. Here, hypoxic induction studies are conducted in vivo and in vitro using rat costal cartilage-derived skeletal stem cells (SSCs) and find that hypoxia activates the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)/stimulator of interferon genes (STING) signaling pathway and increased reactive oxygen species (ROS) accumulation, triggering ferroptosis in SSCs through hypoxia-inducible factor-1 alpha-dependent mitophagy. Progressive hypoxia preconditioning reduce STING expression and ROS accumulation, inducing SSCs differentiation into nucleus pulposus-like cells via the Wnt signaling pathway. Considering this, a 3-D sustained-release culture carrier is generated by mixing SSCs with methacrylated hyaluronic acid and polydopamine nanoparticles coated with the STING inhibitor C-176 and evaluated its inhibitory effect on IVDD. This carrier is demonstrated to inhibit the cGAS/STING pathway and prevent ROS accumulation by continuously releasing C-176-coated polydopamine nanoparticles, thereby reducing ferroptosis, promoting differentiation, and ultimately attenuating IVDD, suggesting its potential as a novel treatment strategy.

Dietary branched-chain amino acids intake and coronary artery calcium progression: insights from the coronary artery risk development in young adults (CARDIA) study

OBJECTIVE

Branched-chain amino acids (BCAA) have been implicated in the risk of cardiovascular disease. However, it is unclear whether dietary BCAA intake, specifically isoleucine, leucine, and valine are associated with coronary artery calcium (CAC) progression.

METHODS

We included the participants from the Coronary Artery Risk Development in Young Adults (CARDIA) study cohort for the analysis. Dietary intake of BCAA was assessed at year 7 of the study. CAC was measured using standardized computed tomography scans at years 15, 20, and 25. CAC progression was defined as follows: for participants with a baseline CAC of 0, progression was defined as CAC > 0 at follow-up; for those with 0 < baseline CAC < 100, progression was defined as an annualized change of ≥ 10; and for those with baseline CAC ≥ 100, progression was defined as an annualized percent change of ≥ 10%. Multivariate adjusted Cox regression models were utilized to examine the associations between BCAA intake and CAC progression.

RESULTS

Among 2381 included participants (average age 40.4 ± 3.5 years, 44.9% men), 629 participants (26.4%) exhibited CAC progression during a follow-up period of 8.90 ± 2.03 years. In the fully adjusted model, high intake of total BCAA, and its individual components, isoleucine, leucine, and valine were associated with an increased risk of CAC progression by 35.6% (HR, 1.356 [95% CI, 1.040-1.769]), 30.5% (HR, 1.305 [95% CI, 1.001-1.701]), 30.9% (HR, 1.309 [95% CI, 1.003-1.706]), and 33.9% (HR, 1.339 [95% CI, 1.026-1.747]), respectively, compared to their corresponding low intake groups. The associations were consistent across various subgroups, including age, sex, race, and body mass index, but were stronger in participants without baseline CAC (interaction P < 0.001). These results remained robust in a series of sensitivity analyses.

CONCLUSIONS

High dietary intake of BCAA, including isoleucine, leucine, and valine, were independently associated with an increased risk of CAC progression. The findings may implication for dietary modifications in primary prevention of subclinical atherosclerosis.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov ; Unique identifier: NCT00005130.

Molecular characterization of PANoptosis-related genes as novel signatures for peripheral nerve injury based on time-series transcriptome sequencing

Programmed cell death (PCD) pathways play pivotal roles in the development and progression of peripheral nerve injury (PNI). PANoptosis, as a novel form of PCD pathway with key features of pyroptosis, apoptosis and necroptosis, is implicated in the pathogenesis of multiple neurologic diseases. This study aimed to identify PANoptosis-related biomarkers and characterize their molecular roles and immune landscape in PNI. PANoptosis-related genes (PRGs) were retrieved from Reactome pathway database and previous literatures. Differentially expressed PANoptosis-related genes (DEPRGs) were identified based on a time-series transcriptome sequencing dataset. DEPRGs were predicted to be enriched in inflammatory response, inflammatory complex, PCD and NOD-like receptor signaling pathway through GO, KEGG, Reactome and GSEA analysis. Hub genes, including Ripk3, Pycard and Il18, were then recognized through PPI network and multiple algorithms. The molecular regulatory mechanisms of hub genes were elucidated by transcription factor network and competing endogenous RNA network. Moreover, the immune cell landscape of hub genes was analyzed. Eventually, the expression levels of hub genes were verified through external dataset and animal model. Ripk3, Pycard and Il18 were remarkably upregulated in PNI samples, which were in consistent with the results of bioinformatic analysis. This study uncovered the molecular characterization of PANoptosis-related genes in PNI and illustrated the novel PANoptosis biomarkers for PNI.

Mesenchymal Stem Cells and Their Extracellular Vesicles Are a Promising Alternative to Antibiotics for Treating Sepsis

Sepsis is a life-threatening disease caused by the overwhelming response to pathogen infections. Currently, treatment options for sepsis are limited to broad-spectrum antibiotics and supportive care. However, the growing resistance of pathogens to common antibiotics complicates treatment efforts. Excessive immune response (i.e., cytokine storm) can persist even after the infection is cleared. This overactive inflammatory response can severely damage multiple organ systems. Given these challenges, managing the excessive immune response is critical in controlling sepsis progression. Therefore, Mesenchymal stem cells (MSCs), with their immunomodulatory and antibacterial properties, have emerged as a promising option for adjunctive therapy in treating sepsis. Moreover, MSCs exhibit a favorable safety profile, as they are eventually eliminated by the host's immune system within several months post-administration, resulting in minimal side effects and have not been linked to common antibiotic therapy drawbacks (i.e., antibiotic resistance). This review explores the potential of MSCs as a personalized therapy for sepsis treatment, clarifying their mechanisms of action and providing up-to-date technological advancements to enhance their protective efficacy for patients suffering from sepsis and its consequences.

Pretreatment with Notoginsenoside R1 enhances the efficacy of neonatal rat mesenchymal stem cell transplantation in model of myocardial infarction through regulating PI3K/Akt/FoxO1 signaling pathways

BACKGROUND

Although stem cell transplantation is a promising approach for the treatment of myocardial infarction (MI), there are still some problems faced such as the low survival rate of stem cells. Here, we investigated the role of Notoginsenoside R1 (NGR1) pretreatment in improving the effects of neonatal rat bone marrow mesenchymal stem cell (MSC) transplantation for treatment of MI.

METHODS

Cardiac functions were detected by echocardiography and the myocardial infarct size was determined by Masson's trichrome staining in a rat model of MI. The cardioprotective effects of NGR1/LY294002 co-pretreated MSCs was evaluated to explore the underlying mechanism. The angiogenesis was determined by vWF and α-SMA immunofluorescence staining and cell apoptosis was detected by TUNEL. In vitro, the effects of NGR1 on stem cell proliferation was examined by CCK-8 and levels of P-Akt, P-CREB, P-FoxO1 were detected by western blot. Apoptosis, ROS content, and cytokine levels were examined by DAPI and TUNEL staining, a ROS assay kit, and ELISA, respectively.

RESULTS

NGR1 elevated the therapeutic effect of MSC transplantation on infarction by preserving cardiac function, increasing angiogenesis and expressions of IGF-1, VEGF, and SDF-1, and reducing cell apoptosis, whereas the addition of LY294002 prior to NGR1 treatment significantly counteracted the foregoing effects of NGR1. NGR1 pretreatment and SC79 pretreatment were similar in that both significantly increased P-Akt and P-FoxO1 levels in MSC and did not affect P-CREB levels. Besides, both NGR1 and SC79 promoted VEGF, SCF and bFGF levels in MSC cultures, and significantly reduced ROS accumulation and the attenuated cell apoptosis in MSC triggered by H2O2. Similarly, addition of LY294002 before NGR1 treatment significantly counteracted the aforementioned effects of NGR1 in vitro.

CONCLUSIONS

NGR1 pretreatment enhances the effect of MSC transplantation for treatment of MI through paracrine signaling, and the mechanism underlying this effect may be associated with PI3K/Akt/FoxO1 signaling pathways.

Pretreatment with growth differentiation factor 15 augments cardioprotection by mesenchymal stem cells in myocardial infarction by improving their survival

BACKGROUND

The clinical application of mesenchymal stem cells (MSCs) in myocardial infarction (MI) is severely hampered by their poor survival. Pretreatment is a key strategy that has been adopted to promote their therapeutic efficacy. This study aimed to investigate the benefit of growth differentiation factor 15-pretreated MSCs (GDF15-MSCs) in enhancing cardiac repair following MI and to determine the underlying mechanisms.

METHODS

MSCs with or without GDF15 pretreatment were exposed to serum deprivation and hypoxia (SD/H) challenge. Apoptosis of MSCs was assessed by TUNEL staining. The conditioned media (CM) of MSCs and GDF15-MSCs was collected by centrifugation. MSCs and GDF15-MSCs were transplanted into the peri-infarct region in a mouse model of MI. Cardiac function, fibrosis and MSC survival were examined 4 weeks after MSC transplantation.

RESULTS

Pretreatment with GDF15 greatly reduced SD/H-induced apoptosis of MSCs via inhibition of reactive oxygen species (ROS) generation by attenuating mitochondrial fission. Mechanistically, GDF15 pretreatment ameliorated mitochondrial fission of MSCs under SD/H challenge by activating the AMPK pathway. These effects were partially abrogated by AMPK inhibitor. Pretreatment with GDF15 also promoted paracrine effects of MSCs in vitro, evidenced by improving tube formation of HUVECs, and inhibited the apoptosis of cardiomyocytes induced by SD/H. At 4 weeks after transplantation, compared with MSCs, GDF15 pretreatment strongly promoted the survival of MSCs in the ischemic heart with consequent enhanced cardiac function, reduced cardiac fibrosis and increased angiogenesis.

CONCLUSIONS

Our study showed that pretreatment with GDF15 promoted the cardioprotective effects of MSCs in MI via regulation of pro-survival signaling and paracrine actions. GDF15 pretreatment is an effective approach to enhance the therapeutic efficacy of MSCs in ischemic heart disease.

Therapeutic Applications of Engineered Mesenchymal Stromal Cells for Enhanced Angiogenesis in Cardiac and Cerebral Ischemia

Ischemic diseases are characterized by obstruction of blood flow to the respective organs, of which ischemia of the heart and brain are the most prominent manifestations with shared pathophysiological mechanisms and risk factors. While most revascularization therapies aim to restore blood flow, this can be challenging due to the limited therapeutic window available for treatment approaches. For a very long time, mesenchymal stromal cells have been used to treat cerebral and cardiac ischemia. However, their application is restricted either by inefficient mode of delivery or the low cell survival rates following implantation into the ischemic microenvironment. Nonetheless, several studies are currently focusing on using of mesenchymal stromal cells engineered to overexpress therapeutic genes as a cell-based gene therapy to restore angiogenesis. This review delves into the utilization of MSCs for angiogenesis and the applications of engineered MSCs for the treatment of cardiac and cerebral ischemia. Moreover, the safety issues related to the genetic modification of MSCs have also been discussed.

Branched-chain amino acids deficiency promotes diabetic cardiomyopathy by activating autophagy of cardiac fibroblasts

Rationale: More than half of the patients with type II diabetes mellitus (T2D) develop diabetic cardiomyopathy (DCM). Glycemic control alone cannot effectively prevent or alleviate DCM. Methods: Herein, we concentrated on the variations in levels of metabolites between DCM and T2D patients without cardiomyopathy phenotype. In high-fat diet/low-dose streptozotocin-induced T2D and leptin receptor-deficient diabetic mouse models, we investigated the effect of altering branched-chain amino acids (BCAAs) levels on DCM. Results: We discovered that the levels of plasma BCAAs are notably lower in 15 DCM patients compared to 19 T2D patients who do not exhibit cardiomyopathy phenotype, using nuclear magnetic resonance analysis. This finding was further validated in two additional batches of samples, 123 DCM patients and 129 T2D patients based on the BCAA assay kit, and 30 DCM patients and 30 T2D patients based on the LC-MS/MS method, respectively. Moreover, it is verified that BCAA deficiency aggravated, whereas BCAA supplementation alleviated cardiomyopathy phenotypes in diabetic mice. Furthermore, BCAA deficiency promoted cardiac fibroblast activation by stimulating autophagy in DCM mice. Mechanistically, BCAA deficiency activated autophagy via the AMPK-ULK1 signaling pathway in cardiac fibroblasts. Using pharmacological approaches, we validated our findings that autophagy inhibition relieved, whereas autophagy activation aggravated, DCM phenotypes. Conclusions: Taken together, we describe a novel perspective wherein BCAA supplementation may serve as a potential therapeutic agent to mitigate DCM and fibrosis. Our findings provide insights for the development of preventive measures for DCM.

Myocardial infarction in rats was alleviated by MSCs derived from the maternal segment of the human umbilical cord

Background

Mesenchymal stem cells (MSCs) are safe and effective in treating myocardial infarction (MI) and have broad application prospects. However, the heterogeneity of MSCs may affect their therapeutic effect on the disease. We recently found that MSCs derived from different segments of the same umbilical cord (UC) showed significant difference in the expression of genes that are related to heart development and injury repair. We therefore hypothesized that those MSCs with high expression of above genes are more effective to treat MI and tested it in this study.

Methods

MSCs were isolated from 3 cm-long segments of the maternal, middle and fetal segments of the UC (maternal-MSCs, middle-MSCs and fetal-MSCs, respectively). RNA-seq was used to analyze and compare the transcriptomes. We verified the effects of MSCs on oxygen-glucose deprivation (OGD)-induced cardiomyocyte apoptosis in vitro. In vivo, a rat MI model was established by ligating the left anterior descending coronary artery, and MSCs were injected into the myocardium surrounding the MI site. The therapeutic effects of MSCs derived from different segments of the UC were evaluated by examining cardiac function, histopathology, cardiomyocyte apoptosis, and angiogenesis.

Results

Compared to fetal-MSCs and middle-MSCs, maternal-MSCs exhibited significantly higher expression of genes that are associated with heart development, such as GATA-binding protein 4 (GATA4), and myocardin (MYOCD). Coculture with maternal-MSCs reduced OGD-induced cardiomyocyte apoptosis. In rats with MI, maternal-MSCs significantly restored cardiac contractile function and reduced the infarct size. Mechanistic experiments revealed that maternal-MSCs exerted cardioprotective effects by decreasing cardiomyocyte apoptosis, and promoting angiogenesis.

Conclusion

Our data demonstrated that maternal segment-derived MSCs were a superior cell source for regenerative repair after MI. Segmental localization of the entire UC when isolating hUCMSCs was necessary to improve the effectiveness of clinical applications.

OmicShare tools: A zero-code interactive online platform for biological data analysis and visualization

The OmicShare tools platform is a user-friendly online resource for data analysis and visualization, encompassing 161 bioinformatic tools. Users can easily track the progress of projects in real-time through an overview interface. The platform has a powerful interactive graphics engine that allows for the custom-tailored modification of charts generated from analyses. The visually appealing charts produced by OmicShare improve data interpretability and meet the requirements for publication. It has been acknowledged in over 4000 publications and is available in https://www.omicshare.com/tools/.

The Role of Prolactin in Amniotic Membrane Regeneration: Therapeutic Potential for Premature Rupture of Membranes

Premature rupture of membranes (PROM) is defined as rupture of fetal membranes before the onset of labor. Prolactin (PRL) is secreted by decidual membranes and accumulated significantly in the amniotic fluid during pregnancy. PRL could ameliorate inflammation and collagen degradation in fetal membranes. However, the role of PRL in amniotic membrane is not well characterized. We isolated human amniotic epithelial stem cells (hAESCs) from human fetal membranes to study the effect of PRL on proliferation, migration, and antioxidative stress. Amniotic pore culture technique (APCT) model was constructed to evaluate the tissue regeneration effect in vitro. The potential targets and pathways of PRL acting in amnion via integrated bioinformatic methods. PRL had a dose-dependent effect on hAESCs in vitro. PRL (500 ng/mL) significantly improved the viability of hAESCs and inhibited cell apoptosis, related to the upregulation of CCN2 expression and downregulation of Bax, Caspase 3, and Caspase 8. PRL accelerated migration process in hAESCs via downregulation of MMP2, MMP3, and MMP9. PRL attenuated the cellular damage and mitochondrial dysfunction induced by hydrogen peroxide in hAESCs. PRL accelerated the healing process in the APCT model significantly. The top 10 specific targets (IGF1R, SIRT1, MAP2K1, CASP8, MAPK14, MCL1, NFKB1, HIF1A, MTOR, and HSP90AA1) and signaling pathways (such as HIF signaling pathway) were selected using an integrated bioinformatics approach. PRL improves the viability and antioxidative stress function of hAESCs and the regeneration of ruptured amniotic membranes in vitro. Thus, PRL has great therapeutic potential for prevention and treatment of ruptured membranes.

Integrative analysis of Iso-Seq and RNA-seq data reveals transcriptome complexity and differential isoform in skin tissues of different hair length Yak

BACKGROUND

The hair follicle development process is regulated by sophisticated genes and signaling networks, and the hair grows from the hair follicle. The Tianzhu white yak population exhibits differences in hair length, especially on the forehead and shoulder region. However, the genetic mechanism is still unclear. Isoform sequencing (Iso-seq) technology with advantages in long reads sequencing. Hence, we combined the Iso-seq and RNA-seq methods to investigate the transcript complexity and difference between long-haired yak (LHY) and normal-haired yak (NHY).

RESULTS

The hair length measurement result showed a significant difference between LHY and NHY on the forehead and the shoulder (P-value < 0.001). The skin samples from the forehead and the shoulder of LHY and NHY were pooled for isoform sequencing (Iso-seq). We obtained numerous long transcripts, including novel isoforms, long non-coding RNA, alternative splicing events, and alternative polyadenylation events. Combined with RNA-seq data, we performed differential isoforms (DEIs) analysis between LHY and NHY. We found that some hair follicle and skin development-related DEIs, like BMP4, KRT2, IGF2R, and COL1A2 in the forehead skin; BMP1, KRT1, FGF5, COL2A1, and IGFBP5 in the shoulder skin. Enrichment analysis revealed that DEIs in both two comparable groups significantly participated in skin and hair follicle development-related pathways, like ECM-receptor interaction, focal adhesion, and PI3K-Akt signaling pathways. The results indicated that the hair follicle development of Tianzhu white yak may influence the hair length difference. Besides, the protein-protein interaction (PPI) network of DEIs showed COL2A1 and COL3A1 exhibited a high degree of centrality, and these two genes were suggested as potential candidates for the hair length growth of Tianzhu white yak.

CONCLUSIONS

The results provided a comprehensive analysis of the transcriptome complexity and identified differential transcripts that enhance our understanding of the molecular mechanisms underlying the variation in hair length growth in Tianzhu white yak.

Phenylacetyl glutamine (PAGln) enhances cardiomyocyte death after myocardial infarction through β1 adrenergic receptor

This study aims to explore the roles of phenylacetyl glutamine (PAGln) on myocardial infarction (MI) pathogenesis. Here, using targeted metabolomics analysis, it was found that the plasma metabolite PAGln was upregulated in coronary artery disease (CAD) patients and MI mice and could be an independent risk factor for CAD. In vivo and in vitro functional experiments revealed that PAGln pretreatment enhanced MI-induced myocardial injury and cardiac fibrosis, as evident by the increased infarct size, cardiomyocyte death, and the upregulated expression of cardiac fibrosis markers (Col1a1 and α-SMA). Combined with RNA-sequencing analysis and G protein-coupled receptor (GPCR) inhibitor, we found that the GPCR signaling activation is essential for PAGln-mediated effects on cardiomyocyte death. Furthermore, drug affinity responsive target stability and cellular thermal shift assay demonstrated that PAGln could interact with β1-adrenergic receptor (AR). Moreover, β1-AR blocker treatment indeed extended the cardiac remodeling after PAGln-enhanced MI. These results suggest that PAGln might be a potential therapeutic target for extending the cardiac remodeling window in MI patients that signals via β1-AR.

Stem cell-based therapy in cardiac repair after myocardial infarction: Promise, challenges, and future directions

Stem cells represent an attractive resource for cardiac regeneration. However, the survival and function of transplanted stem cells is poor and remains a major challenge for the development of effective therapies. As two main cell types currently under investigation in heart repair, mesenchymal stromal cells (MSCs) indirectly support endogenous regenerative capacities after transplantation, while induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) functionally integrate into the damaged myocardium and directly contribute to the restoration of its pump function. These two cell types are exposed to a common microenvironment with many stressors in ischemic heart tissue. This review summarizes the research progress on the mechanisms and challenges of MSCs and iPSC-CMs in post-MI heart repair, introduces several randomized clinical trials with 3D-mapping-guided cell therapy, and outlines recent findings related to the factors that affect the survival and function of stem cells. We also discuss the future directions for optimization such as biomaterial utilization, cell combinations, and intravenous injection of engineered nucleus-free MSCs.

The Role of Branched-chain Amino Acids and Their Metabolism in Cardiovascular Diseases

Branched-chain amino acids (BCAAs), including leucine, isoleucine, and valine, are essential amino acids for protein synthesis. Recent studies have yielded new insights into their diverse physiological and pathological roles in health and disease. Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality globally. An increasing number of clinical studies have demonstrated that high levels of circulating BCAAs are associated with an increased risk of CVDs. Animal studies have provided preliminary evidence linking BCAA intake and metabolism with cardiovascular diseases. Despite these insights, the causal relationship between BCAA metabolism and CVD remains poorly established, and the underlying mechanisms remain incompletely understood. Here, we aim to provide an update on the current understanding of the roles of BCAAs and their metabolism in the development and progression of various CVDs. We also discuss the potential strategies targeting BCAA nutrition and metabolism for the prevention and treatment of CVDs.

Deficiency of BCAT2-mediated branched-chain amino acid catabolism promotes colorectal cancer development

OBJECTIVE

Branched-chain amino acid (BCAA) metabolism is involved in the development of colorectal cancer (CRC); however, the underlying mechanism remains unclear. Therefore, this study investigates the role of BCAA metabolism in CRC progression.

METHODS

Dietary BCAA was administered to both azoxymethane-induced and azoxymethane/dextran sodium sulfate-induced CRC mouse models. The expression of genes related to BCAA metabolism was determined using RNA sequencing. Adjacent tissue samples, obtained from 58 patients with CRC, were subjected to quantitative real-time PCR and immunohistochemical analysis. Moreover, the suppressive role of branched-chain aminotransferase 2 (BCAT2) in cell proliferation, apoptosis, and xenograft mouse models was investigated. Alterations in BCAAs and activation of downstream pathways were also assessed using metabolic analysis and western blotting.

RESULTS

High levels of dietary BCAA intake promoted CRC tumorigenesis in chemical-induced CRC and xenograft mouse models. Both the mRNA and protein levels of BCAT2 were decreased in tumor tissues of patients with CRC compared to those in normal tissues. Proliferation assays and xenograft models confirmed the suppressive role of BCAT2 in CRC progression. Furthermore, the accumulation of BCAAs caused by BCAT2 deficiency facilitated the chronic activation of mTORC1, thereby mediating the oncogenic effect of BCAAs.

CONCLUSION

BCAT2 deficiency promotes CRC progression through inhibition of BCAAs metabolism and chronic activation of mTORC1.

Targeted Metabolomics Analysis of Serum Amino Acids in T2DM Patients

Purpose

Amino acids are the important metabolites in the body and play a crucial role in biological processes. The purpose of this study is to provide a profile of amino acids change in the serum of T2DM patients and identify potential biomarkers.

Patients and Methods

In this study, we quantitatively determined the serum amino acid profiles of 30 T2DM patients and 30 healthy volunteers. T test and multivariate statistical analysis were used to identify candidate biomarkers with GraphPad Prism 9.5 software and MetaboAnalyst 5.0 on-line platform.

Results

Thirty-four amino acids were quantified, and 19 amino acid levels differed significantly between T2DM and Healthy groups. Screened by the specific screening criteria (VIP>1.0; P<0.05; FC>1.5, or FC<0.67) in MetaboAnalyst 5.0 platform, 8 amino acids were identified as potential biomarkers. Pearson rank correlation test showed 14 differential amino acids were significantly correlated with T2DM-related physiological parameters.

Conclusion

The results of this study provide theoretical basis for the subsequent development of dietary supplements for the prevention or treatment of T2DM and its complications.

Branched-Chain Amino Acid Accumulation Fuels the Senescence-Associated Secretory Phenotype

The essential branched-chain amino acids (BCAAs) leucine, isoleucine, and valine play critical roles in protein synthesis and energy metabolism. Despite their widespread use as nutritional supplements, BCAAs' full effects on mammalian physiology remain uncertain due to the complexities of BCAA metabolic regulation. Here a novel mechanism linking intrinsic alterations in BCAA metabolism is identified to cellular senescence and the senescence-associated secretory phenotype (SASP), both of which contribute to organismal aging and inflammation-related diseases. Altered BCAA metabolism driving the SASP is mediated by robust activation of the BCAA transporters Solute Carrier Family 6 Members 14 and 15 as well as downregulation of the catabolic enzyme BCAA transaminase 1 during onset of cellular senescence, leading to highly elevated intracellular BCAA levels in senescent cells. This, in turn, activates the mammalian target of rapamycin complex 1 (mTORC1) to establish the full SASP program. Transgenic Drosophila models further indicate that orthologous BCAA regulators are involved in the induction of cellular senescence and age-related phenotypes in flies, suggesting evolutionary conservation of this metabolic pathway during aging. Finally, experimentally blocking BCAA accumulation attenuates the inflammatory response in a mouse senescence model, highlighting the therapeutic potential of modulating BCAA metabolism for the treatment of age-related and inflammatory diseases.

Metabolic signatures in post-myocardial infarction heart failure, including insights into prediction, intervention, and prognosis

Heart failure (HF) is a prevalent long-term complication of myocardial infarction (MI). The incidence of post-MI HF is high, and patients with the condition have a poor prognosis. Accurate identification of individuals at high risk for post-MI HF is crucial for implementation of a protective and ideally personalized strategy to prevent fatal events. Post-MI HF is characterized by adverse cardiac remodeling, which results from metabolic changes in response to long-term ischemia. Moreover, various risk factors, including genetics, diet, and obesity, can influence metabolic pathways in patients. This review focuses on the metabolic signatures of post-MI HF that could serve as non-invasive biomarkers for early identification in high-risk populations. We also explore how metabolism participates in the pathophysiology of post-MI HF. Furthermore, we discuss the potential of metabolites as novel targets for treatment of post-MI HF and as biomarkers for prognostic evaluation. It is expected to provide valuable suggestions for the clinical prevention and treatment of post-MI HF from a metabolic perspective.

Branched-chain amino acid catabolic defect in vascular smooth muscle cells drives thoracic aortic dissection via mTOR hyperactivation

Metabolic reprogramming of vascular smooth muscle cell (VSMC) plays a critical role in the pathogenesis of thoracic aortic dissection (TAD). Previous researches have mainly focused on dysregulation of fatty acid or glucose metabolism, while the impact of amino acids catabolic disorder in VSMCs during the development of TAD remains elusive. Here, we identified branched-chain amino acid (BCAA) catabolic defect as a metabolic hallmark of TAD. The bioinformatics analysis and data from human aorta revealed impaired BCAA catabolism in TAD individuals. This was accompanied by upregulated branched-chain α-ketoacid dehydrogenase kinase (BCKDK) expression and BCKD E1 subunit alpha (BCKDHA) phosphorylation, enhanced vascular inflammation, and hyperactivation of mTOR signaling. Further in vivo experiments demonstrated that inhibition of BCKDK with BT2 (a BCKDK allosteric inhibitor) treatment dephosphorylated BCKDHA and re-activated BCAA catabolism, attenuated VSMCs phenotypic switching, alleviated aortic remodeling, mitochondrial reactive oxygen species (ROS) damage and vascular inflammation. Additionally, the beneficial actions of BT2 were validated in a TNF-α challenged murine VSMC cell line. Meanwhile, rapamycin conferred similar beneficial effects against VSMC phenotypic switching, cellular ROS damage as well as inflammatory response. However, co-treatment with MHY1485 (a classic mTOR activator) reversed the beneficial effects of BT2 by reactivating mTOR signaling. Taken together, the in vivo and in vitro evidence showed that impairment of BCAA catabolism resulted in aortic accumulation of BCAA and further caused VSMC phenotypic switching, mitochondrial ROS damage and inflammatory response via mTOR hyperactivation. BCKDK and mTOR signaling may serve as the potential drug targets for the prevention and treatment of TAD.

Molecular mechanisms of cellular metabolic homeostasis in stem cells

Many tissues and organ systems have intrinsic regeneration capabilities that are largely driven and maintained by tissue-resident stem cell populations. In recent years, growing evidence has demonstrated that cellular metabolic homeostasis plays a central role in mediating stem cell fate, tissue regeneration, and homeostasis. Thus, a thorough understanding of the mechanisms that regulate metabolic homeostasis in stem cells may contribute to our knowledge on how tissue homeostasis is maintained and provide novel insights for disease management. In this review, we summarize the known relationship between the regulation of metabolic homeostasis and molecular pathways in stem cells. We also discuss potential targets of metabolic homeostasis in disease therapy and describe the current limitations and future directions in the development of these novel therapeutic targets.

Complement factor H inhibits endothelial cell migration through suppression of STAT3 signaling

Complement factor H (CFH), a major soluble inhibitor of complement, is a plasma protein that directly interacts with the endothelium of blood vessels. Mutations in the CFH gene lead to diseases associated with excessive angiogenesis; however, the underlying mechanisms are unknown. The present study aimed to determine the effects of CFH on endothelial cells and to explore the underlying mechanisms. The adenoviral plasmid expressing CFH was transduced into HepG2 cells, and the culture medium supernatant was collected and co-cultured with human umbilical vein endothelial cells (HUVECs). Cell proliferation was measured by CCK8 and MTT assays, and cell migration was measured by wound healing and Transwell assays. Reverse transcription-quantitative PCR was performed to detect gene transcription. Western blotting was used to determine protein levels. The results revealed that CFH can inhibit migration, but not viability, of HUVECs. In addition, CFH did not significantly alter MAPK or TGF-β signaling, whereas it decreased STAT3 phosphorylation in HUVECs. Furthermore, CFH failed to reduce migration of HUVECs, with inhibition of STAT3 signaling by STATTIC or activation of STAT3 signaling by overexpression of STAT3 (Y705D) compromising CFH-inhibited HUVEC migration. CFH also decreased the expression levels of vascular endothelial growth factor receptor 2, a downstream effector of STAT3 mediating endothelial cell migration. In conclusion, the present study suggested that CFH may be a potential therapeutic target for angiogenesis-related diseases.

Elevated branched-chain amino acid promotes atherosclerosis progression by enhancing mitochondrial-to-nuclear H2O2-disulfide HMGB1 in macrophages

As the essential amino acids, branched-chain amino acid (BCAA) from diets is indispensable for health. BCAA supplementation is often recommended for patients with consumptive diseases or healthy people who exercise regularly. Latest studies and ours reported that elevated BCAA level was positively correlated with metabolic syndrome, diabetes, thrombosis and heart failure. However, the adverse effect of BCAA in atherosclerosis (AS) and its underlying mechanism remain unknown. Here, we found elevated plasma BCAA level was an independent risk factor for CHD patients by a human cohort study. By employing the HCD-fed ApoE^-/- mice of AS model, ingestion of BCAA significantly increased plaque volume, instability and inflammation in AS. Elevated BCAA due to high dietary BCAA intake or BCAA catabolic defects promoted AS progression. Furthermore, BCAA catabolic defects were found in the monocytes of patients with CHD and abdominal macrophages in AS mice. Improvement of BCAA catabolism in macrophages alleviated AS burden in mice. The protein screening assay revealed HMGB1 as a potential molecular target of BCAA in activating proinflammatory macrophages. Excessive BCAA induced the formation and secretion of disulfide HMGB1 as well as subsequent inflammatory cascade of macrophages in a mitochondrial-nuclear H₂O₂ dependent manner. Scavenging nuclear H₂O₂ by overexpression of nucleus-targeting catalase (nCAT) effectively inhibited BCAA-induced inflammation in macrophages. All of the results above illustrate that elevated BCAA promotes AS progression by inducing redox-regulated HMGB1 translocation and further proinflammatory macrophage activation. Our findings provide novel insights into the role of animo acids as the daily dietary nutrients in AS development, and also suggest that restricting excessive dietary BCAA consuming and promoting BCAA catabolism may serve as promising strategies to alleviate and prevent AS and its subsequent CHD.

Time-Varying Effect of Physical Activity on Mortality Among Myocardial Infarction Survivors: A Nationwide Population-Based Cohort Study

Background

Physical activity (PA) is an important component of secondary prevention after myocardial infarction (MI). The mortality risk of MI survivors varies at different post-MI periods, yet the time-varying effect of total PA is unclear. We aimed to investigate the association between different volumes and patterns of total PA and mortality at different post-MI periods.

Methods

Using data from the China Patient-centered Evaluative Assessment of Cardiac Events Million Persons Project, we divided the screened MI survivors into within-1-year and beyond-1-year groups based on the duration between their baseline interview and MI onset. Total PA was divided into insufficient ( < 3000 metabolic equivalent of task [MET] minutes/week) and sufficient PA. Sufficient PA was further categorized as moderate and high (3000-4500 and > 4500 MET minutes/week) volumes; leisure ( ≥ 50%) and non-leisure ( > 50%) patterns. Data on mortality were derived from the National Mortality Surveillance System and Vital Registration of the Chinese Center for Disease Control and Prevention. Cox proportional hazard models were fitted to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Restricted cubic spline regression analyses were performed to examine the dose-response association between PA and mortality.

Results

During the follow-up (median 3.7 years) of the 20,653 post-MI patients, 751 patients died. In the within-1-year group, moderate (HR: 0.59, 95% CI: 0.40 to 0.88) and high (0.63, 0.45 to 0.88) volumes and both patterns (leisure: 0.52, 0.29 to 0.94; non-leisure: 0.64, 0.46 to 0.88) of PA were all associated with significantly lower risk of mortality, compared with insufficient PA. In the beyond-1-year group, the association was observed in high volume (0.69, 0.56 to 0.86) and both patterns (leisure: 0.64, 0.48 to 0.87; non-leisure: 0.79, 0.65 to 0.97). A non-linear relationship between PA and mortality was found in the within-1-year group (p for non-linearity < 0.001), while a linear relationship was demonstrated in the beyond-1-year group (p for non-linearity = 0.107).

Conclusions

Sufficient total PA was associated with mortality risk reduction after MI, either leisure or non-leisure pattern. Different dose-response associations between PA and mortality were found at different post-MI periods. These results could promote individualized and scientifically derived secondary prevention strategies for MI.