Untargeted metabolomics identifies succinate as a biomarker and therapeutic target in aortic aneurysm and dissection

Trailblazing in adjuvant research: succinate's uncharted territory with neutrophils

The purpose of this study is to investigate the previously unknown connection that succinate has with neutrophils in the setting of adjuvant-mediated immunological enhancement. It has been discovered that succinates stimulate the recruitment of neutrophils in immunization sites, which in turn induces the expression of what is known as neutrophil-derived B cell-activating factor (BAFF). Further amplification of vaccine-induced antibody responses is provided via the succinate receptor 1-interferon regulatory factor 5 (SUCNR1-IRF5)-BAFF signaling pathway, which provides insights into a unique mechanism for immunological enhancement.NEW & NOTEWORTHY This study explores the role of succinate as a vaccine adjuvant, revealing its capacity to enhance neutrophil recruitment at immunization sites, which boosts B cell activation through the succinate receptor 1-interferon regulatory factor 5-B cell-activating factor (SUCNR1-IRF5-BAFF) signaling pathway. Results demonstrate succinate's potential to amplify vaccine-induced antibody responses, highlighting its significance in immunological enhancement and offering new insights into the adjuvant mechanisms of action, particularly in neutrophil-mediated immune responses.

Innovation in pathogenesis and management of aortic aneurysm

Aortic aneurysm (AA) refers to the persistent dilatation of the aorta, exceeding three centimeters. Investigating the pathophysiology of this condition is important for its prevention and management, given its responsibility for more than 25000 deaths in the United States. AAs are classified based on their location or morphology. various pathophysiologic pathways including inflammation, the immune system and atherosclerosis have been implicated in its development. Inflammatory markers such as transforming growth factor β, interleukin-1β, tumor necrosis factor-α, matrix metalloproteinase-2 and many more may contribute to this phenomenon. Several genetic disorders such as Marfan syndrome, Ehler-Danlos syndrome and Loeys-Dietz syndrome have also been associated with this disease. Recent years has seen the investigation of novel management of AA, exploring the implication of different immune suppressors, the role of radiation in shrinkage and prevention, as well as minimally invasive and newly hypothesized surgical methods. In this narrative review, we aim to present the new contributing factors involved in pathophysiology of AA. We also highlighted the novel management methods that have demonstrated promising benefits in clinical outcomes of the AA.

Pulmonary succinate receptor 1 elevation in high-fat diet mice exacerbates lipopolysaccharides-induced acute lung injury via sensing succinate

BACKGROUND

Individuals with obesity have higher level of circulating succinate, which acts as a signaling factor that initiates inflammation. It is obscure whether succinate and succinate receptor 1 (SUCNR1) are involved in the process of obesity aggravating acute lung injury (ALI).

METHODS

The lung tissue and blood samples from patients with obesity who underwent lung wedgectomy or segmental resection were collected. Six-week-old male C57BL/6J mice were fed a high-fat diet for 12 weeks to induce obesity and lipopolysaccharides (LPS) were injected intratracheally (100 μg, 1 mg/ml) for 24 h to establish an ALI model. The pulmonary SUCNR1 expression and succinate level were measured. Exogenous succinate was supplemented to assess whether succinate exacerbated the LPS-induced lung injury. We next examined the cellular localization of pulmonary SUCNR1. Furthermore, the role of the succinate-SUCNR1 pathway in LPS-induced inflammatory responses in MH-s macrophages and obese mice was investigated.

RESULT

The pulmonary SUCNR1 expression and serum succinate level were significantly increased in patients with obesity and in HFD mice. Exogenous succinate supplementation significantly increased the severity of ALI and inflammatory response. SUCNR1 was mainly expressed on lung macrophages. In LPS-stimulated MH-s cells, knockdown of SUCNR1 expression significantly inhibited pro-inflammatory cytokines' expression, the increase of hypoxia-inducible factor-1α (HIF-1α) expression, inhibitory κB-α (IκB-α) phosphorylation, p65 phosphorylation and p65 translocation to nucleus. In obese mice, SUCNR1 inhibition significantly alleviated LPS-induced lung injury and decreased the HIF-1α expression and IκB-α phosphorylation.

CONCLUSION

The high expression of pulmonary SUCNR1 and serum succinate accumulation at least partly participate in the process of obesity aggravating LPS-induced lung injury.

Asiatic acid alleviates vascular remodeling in BAPN-induced aortic dissection through inhibiting NF-κB p65/CX3CL1 signaling

Inflammation assumes a pivotal role in the aortic remodeling of aortic dissection (AD). Asiatic acid (AA), a triterpene compound, is recognized for its strong anti-inflammatory properties. Yet, its effects on β-aminopropionitrile (BAPN)-triggered AD have not been clearly established. The objective is to determine whether AA attenuates adverse aortic remodeling in BAPN-induced AD and clarify potential molecular mechanisms. In vitro studies, RAW264.7 cells pretreated with AA were challenged with lipopolysaccharide (LPS), and then the vascular smooth muscle cells (VSMCs)-macrophage coculture system was established to explore intercellular interactions. To induce AD, male C57BL/6J mice at three weeks of age were administered BAPN at a dosage of 1 g/kg/d for four weeks. To decipher the mechanism underlying the effects of AA, RNA sequencing analysis was conducted, with subsequent validation of these pathways through cellular experiments. AA exhibited significant suppression of M1 macrophage polarization. In the cell coculture system, AA facilitated the transformation of VSMCs into a contractile phenotype. In the mouse model of AD, AA strikingly prevented the BAPN-induced increases in inflammation cell infiltration and extracellular matrix degradation. Mechanistically, RNA sequencing analysis revealed a substantial upregulation of CX3CL1 expression in BAPN group but downregulation in AA-treated group. Additionally, it was observed that the upregulation of CX3CL1 negated the beneficial impact of AA on the polarization of macrophages and the phenotypic transformation of VSMCs. Crucially, our findings revealed that AA is capable of downregulating CX3CL1 expression, accomplishing this by obstructing the nuclear translocation of NF-κB p65. The findings indicate that AA holds promise as a prospective treatment for adverse aortic remodeling by suppressing the activity of NF-κB p65/CX3CL1 signaling pathway.

Biomarker Screening by LCMS and Liquid Chip Technology in Acute Aortic Dissection

BACKGROUND

Aortic dissection (AD) is a serious disease. Previous study, the use of peripheral blood biomarkers to diagnose AD showed strong clinical feasibility, but the possible molecular mechanism is unclear.

METHODS

Sera from 79 healthy subjects, 73 patients with well-established AD, and 74 patients with well-established acute myocardial infarction (AMI) were investigated by Liquid Chromatograph-Mass Spectrometer to detect metabolites (AFMK, Glycerophosphocholine, Inosine, SPH). The cell factor expression in the 3 group were detected by Liquid Chip Technology.

RESULTS

The serum content trends of 4 metabolic indexes in patients with AMI and AD group were used as the diagnostic models, and the effective diagnosis rate was 97.8%. The diagnosis rate is 89.8% in distinguishing patients with AMI from patients with AD. The expression in serum of the 3 groups showed that there were significant differences in the expression of 23 cytokines. By correlation analysis, it was found that miP-1, IL-7, MIP-1β, EGF and other cytokines were significantly correlated with the 4 metabolic molecules.

CONCLUSIONS

AFMK, Glycerophosphocholine, Inosine, Sphingfungin B (SPH) metabolites are potential biomarkers for AD, and the influence of related metabolic process may be related to the expression of miP-1, IL-7, MIP-1β, EGF, and other cytokines.

Safety and efficacy of ketorolac in improving the prognosis of acute type A aortic dissection patients: a protocol of a randomized, double-blinded, and placebo-controlled study

BACKGROUND

Acute type A aortic dissection (aTAAD) is a critical and life-threatening condition. Previous research has demonstrated that the use of ketorolac not only reduces the progression, incidence, and severity of aortic aneurysms in animal models, but also decreases postoperative mortality and complications in patients undergoing open abdominal aortic aneurysm replacement. However, there is a lack of studies investigating the efficacy of ketorolac in treating aTAAD in humans. Therefore, we conducted a study to evaluate the safety and efficacy of ketorolac in patients with aTAAD. Our hypothesis was that ketorolac treatment for aTAAD patients would meet safety indicators and effectively improve patient prognosis.

METHODS/DESIGN

This study is a single-center, randomized, double-blinded, and placebo-controlled study. A total of 120 patients with aTAAD will be recruited and will be randomized into the ketorolac group and placebo group with a ratio of 1:1. Ketorolac tromethamine 60 mg per 2 ml will be intramuscularly injected within 2 h before surgery, followed by intramuscular injections of 30 mg per 1 ml BID. on the first and second postoperative days in the Ketorolac group, while 0.9% saline will be administered at the same dose, dosage form, and time in the placebo group. This study aims to evaluate the safety and efficacy of ketorolac in improving the prognosis of aTAAD. The primary endpoint is the composite endpoint event concerning drug-related adverse events. Secondary endpoints include drug-related adverse events, laboratory examination of blood, diagnostic imaging tests, clinical biomarkers, etc. DISCUSSION: This study has been approved by the Medical Ethics Committee of Affiliated Nanjing Drum Tower Hospital, Nanjing University Medical College (approval number: 2023-197-02). This study is designed to evaluate the safety and efficacy of ketorolac in patients with aTAAD. All participating patients will sign an informed consent form, and the trial results will be published in international peer-reviewed journals.

TRIAL REGISTRATION

The Chinese Clinical Trial Registry ( http://www.chictr.org.cn ) ChiCTR2300074394. Registered on 4 October 2023.

Promising dawn in the management of pulmonary hypertension: The mystery veil of gut microbiota

The gut microbiota is a complex community of microorganisms inhabiting the intestinal tract, which plays a vital role in human health. It is intricately involved in the metabolism, and it also affects diverse physiological processes. The gut-lung axis is a bidirectional pathway between the gastrointestinal tract and the lungs. Recent research has shown that the gut microbiome plays a crucial role in immune response regulation in the lungs and the development of lung diseases. In this review, we present the interrelated factors concerning gut microbiota and the associated metabolites in pulmonary hypertension (PH), a lethal disease characterized by elevated pulmonary vascular pressure and resistance. Our research team explored the role of gut-microbiota-derived metabolites in cardiovascular diseases and established the correlation between metabolites such as putrescine, succinate, trimethylamine N-oxide (TMAO), and N, N, N-trimethyl-5-aminovaleric acid with the diseases. Furthermore, we found that specific metabolites, such as TMAO and betaine, have significant clinical value in PH, suggesting their potential as biomarkers in disease management. In detailing the interplay between the gut microbiota, their metabolites, and PH, we underscored the potential therapeutic approaches modulating this microbiota. Ultimately, we endeavor to alleviate the substantial socioeconomic burden associated with this disease. This review presents a unique exploratory analysis of the link between gut microbiota and PH, intending to propel further investigations in the gut-lung axis.

Advances in the study of S100A9 in cardiovascular diseases

Cardiovascular disease (CVD) is a group of diseases that primarily affect the heart or blood vessels, with high disability and mortality rates, posing a serious threat to human health. The causative factors, pathogenesis, and characteristics of common CVD differ, but they all involve common pathological processes such as inflammation, oxidative stress, and fibrosis. S100A9 belongs to the S100 family of calcium-binding proteins, which are mainly secreted by myeloid cells and bind to the Toll-like receptor 4 and receptor for advanced glycation end products and is involved in regulating pathological processes such as inflammatory response, fibrosis, vascular calcification, and endothelial barrier function in CVD. The latest research has found that S100A9 is a key biomarker for diagnosing and predicting various CVD. Therefore, this article reviews the latest research progress on the diagnostic and predictive, and therapeutic value of S100A9 in inflammatory-related CVD such as atherosclerosis, myocardial infarction, and arterial aneurysm and summarizes its molecular mechanisms in the progression of CVD, aiming to explore new predictive methods and to identify potential intervention targets for CVD in clinical practice.

Type 2 diabetes and succinate: unmasking an age-old molecule

Beyond their conventional roles in intracellular energy production, some traditional metabolites also function as extracellular messengers that activate cell-surface G-protein-coupled receptors (GPCRs) akin to hormones and neurotransmitters. These signalling metabolites, often derived from nutrients, the gut microbiota or the host's intermediary metabolism, are now acknowledged as key regulators of various metabolic and immune responses. This review delves into the multi-dimensional aspects of succinate, a dual metabolite with roots in both the mitochondria and microbiome. It also connects the dots between succinate's role in the Krebs cycle, mitochondrial respiration, and its double-edge function as a signalling transmitter within and outside the cell. We aim to provide an overview of the role of the succinate-succinate receptor 1 (SUCNR1) axis in diabetes, discussing the potential use of succinate as a biomarker and the novel prospect of targeting SUCNR1 to manage complications associated with diabetes. We further propose strategies to manipulate the succinate-SUCNR1 axis for better diabetes management; this includes pharmacological modulation of SUCNR1 and innovative approaches to manage succinate concentrations, such as succinate administration and indirect strategies, like microbiota modulation. The dual nature of succinate, both in terms of origins and roles, offers a rich landscape for understanding the intricate connections within metabolic diseases, like diabetes, and indicates promising pathways for developing new therapeutic strategies.

Research Progress on the Pathogenesis of Aortic Aneurysm and Dissection in Metabolism

Aortic aneurysm and dissection are complicated diseases having both high prevalence and mortality. It is usually diagnosed at advanced stages and posing diagnostic and therapeutic challenges due to the limitations of current detecting methods for aortic dissection used in clinics. Metabonomics demonstrated its great potential capability in the early diagnosis and personalized treatment of several diseases. Emerging evidence suggests that metabolic disorders including amino acid metabolism, glycometabolism, and lipid metabolism disturbance are involved in the pathogenesis of aortic aneurysm and dissection by affecting multiple functional aortic cells. The purpose of this review is to provide new insights into the metabolism alterations and their related regulatory mechanisms with a focus on recent advances and findings and provide a theoretical basis for the diagnosis, prevention, and drug development for aortic aneurysm and dissection.

Chemical Mechanism of Fireworm Bioluminescence - A Theoretical Proposition

Odontosyllis undecimdonta is a marine worm, commonly known as a fireworm, that exhibits bluish-green bioluminescence (BL). The luciferin (L) and oxyluciferin (OL) during fireworm BL have been experimentally identified in vitro. The L and OL are the respective starting point and ending point of a series of complicated chemical reactions in the BL. However, the chemical mechanism of the fireworm BL remains largely unknown. Before the experiments provided strong evidence for the mechanism, based on our previously successful studies on several bioluminescent systems, we theoretically proposed the chemical mechanism of the fireworm BL in this article. By means of the spin-flip and time-dependent density functional calculations, we clearly described the complete process from L to OL: under the catalysis of luciferase, L undergoes deprotonation and reacts with 3O2 to form a dioxetanone anion via the single-electron transfer mechanism; the dioxetanone anion decomposes into the OL at the first singlet excited state (S1) by the gradually reversible charge-transfer-induced luminescence mechanism; and the S1-OL emits light and deexcites to OL in the ground state.

Multinomial machine learning identifies independent biomarkers by integrated metabolic analysis of acute coronary syndrome

A multi-class classification model for acute coronary syndrome (ACS) remains to be constructed based on multi-fluid metabolomics. Major confounders may exert spurious effects on the relationship between metabolism and ACS. The study aims to identify an independent biomarker panel for the multiclassification of HC, UA, and AMI by integrating serum and urinary metabolomics. We performed a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics study on 300 serum and urine samples from 44 patients with unstable angina (UA), 77 with acute myocardial infarction (AMI), and 29 healthy controls (HC). Multinomial machine learning approaches, including multinomial adaptive least absolute shrinkage and selection operator (LASSO) regression and random forest (RF), and assessment of the confounders were applied to integrate a multi-class classification biomarker panel for HC, UA and AMI. Different metabolic landscapes were portrayed during the transition from HC to UA and then to AMI. Glycerophospholipid metabolism and arginine biosynthesis were predominant during the progression from HC to UA and then to AMI. The multiclass metabolic diagnostic model (MDM) dependent on ACS, including 2-ketobutyric acid, LysoPC(18:2(9Z,12Z)), argininosuccinic acid, and cyclic GMP, demarcated HC, UA, and AMI, providing a C-index of 0.84 (HC vs. UA), 0.98 (HC vs. AMI), and 0.89 (UA vs. AMI). The diagnostic value of MDM largely derives from the contribution of 2-ketobutyric acid, and LysoPC(18:2(9Z,12Z)) in serum. Higher 2-ketobutyric acid and cyclic GMP levels were positively correlated with ACS risk and atherosclerosis plaque burden, while LysoPC(18:2(9Z,12Z)) and argininosuccinic acid showed the reverse relationship. An independent multiclass biomarker panel for HC, UA, and AMI was constructed using the multinomial machine learning methods based on serum and urinary metabolite signatures.

NAD+ rescues aging-induced blood-brain barrier damage via the CX43-PARP1 axis

Blood-brain barrier (BBB) function deteriorates during aging, contributing to cognitive impairment and neurodegeneration. It is unclear what drives BBB leakage in aging and how it can be prevented. Using single-nucleus transcriptomics, we identified decreased connexin 43 (CX43) expression in cadherin-5+ (Cdh5+) cerebral vascular cells in naturally aging mice and confirmed it in human brain samples. Global or Cdh5+ cell-specific CX43 deletion in mice exacerbated BBB dysfunction during aging. The CX43-dependent effect was not due to its canonical gap junction function but was associated with reduced NAD+ levels and mitochondrial dysfunction through NAD+-dependent sirtuin 3 (SIRT3). CX43 interacts with and negatively regulates poly(ADP-ribose) polymerase 1 (PARP1). Pharmacologic inhibition of PARP1 by olaparib or nicotinamide mononucleotide (NMN) supplementation rescued NAD+ levels and alleviated aging-associated BBB leakage. These findings establish the endothelial CX43-PARP1-NAD+ pathway's role in vascular aging and identify a potential therapeutic strategy to combat aging-associated BBB leakage with neuroprotective implications.

Independent and Interactive Roles of Immunity and Metabolism in Aortic Dissection

Aortic dissection (AD) is a cardiovascular disease that seriously endangers the lives of patients. The mortality rate of this disease is high, and the incidence is increasing annually, but the pathogenesis of AD is complicated. In recent years, an increasing number of studies have shown that immune cell infiltration in the media and adventitia of the aorta is a novel hallmark of AD. These cells contribute to changes in the immune microenvironment, which can affect their own metabolism and that of parenchymal cells in the aortic wall, which are essential factors that induce degeneration and remodeling of the vascular wall and play important roles in the formation and development of AD. Accordingly, this review focuses on the independent and interactive roles of immunity and metabolism in AD to provide further insights into the pathogenesis, novel ideas for diagnosis and new strategies for treatment or early prevention of AD.

Succinic acid exacerbates experimental autoimmune uveitis by stimulating neutrophil extracellular traps formation via SUCNR1 receptor

AIMS

To investigate the effect of succinic acid on the development of experimental autoimmune uveitis (EAU) and the underlying mechanism.

METHODS

Succinic acid was administrated intraperitoneally to evaluate its effects on immune response and EAU in mice. Intraocular inflammation was evaluated by histopathological scoring. Frequencies of Th1/Th17 cells were measured by flow cytometry. Concentrations of IFN-γ/IL-17A, neutrophil elastase (NE) and myeloperoxidase (MPO) were determined by enzyme-linked immunosorbent test. Infiltration of neutrophils and generation of neutrophil extracellular traps (NETs) within the eye were assessed by immumofluorescence. NETs formation in extracellular matrix was visualised by laser scanning confocal microscopy. Succinate receptor (SUCNR1) antagonist was used to investigate its effect on the generation of NETs.

RESULTS

Intraperitoneal injection of succinic acid exacerbated EAU severity as evidenced by severe histological changes in association with elevated frequencies of splenic Th1/Th17 cells, and upregulated levels of IFN-γ/IL-17A and NETs in plasma. In vitro experiments showed that succinic acid could promote the generation of NETs by neutrophils as shown by increased expression of NE and MPO.NETs could increase the frequencies of Th1/Th17 cells in CD4+ T cells and their expression of IFN-γ/IL-17A. In the experiment of receptor antagonism, the upregulatory effect of succinic acid on NETs could be significantly blocked by SUCNR1 antagonist.

CONCLUSIONS

Succinic acid could worsen EAU induced by IRBP in mice. This effect was possibly mediated by its upregulation on NETs generation and frequencies of Th1/Th17 cells in affiliation with increased production of IFN-γ/IL-17A through succinic acid-SUCNR1 axis.

Generative Adversarial Network-based Noncontrast CT Angiography for Aorta and Carotid Arteries

Background Iodinated contrast agents (ICAs), which are widely used in CT angiography (CTA), may cause adverse effects in humans, and their use is time-consuming and costly. Purpose To develop an ICA-free deep learning imaging model for synthesizing CTA-like images and to assess quantitative and qualitative image quality as well as the diagnostic accuracy of synthetic CTA (Syn-CTA) images. Materials and Methods A generative adversarial network (GAN)-based CTA imaging model was trained, validated, and tested on retrospectively collected pairs of noncontrast CT and CTA images of the neck and abdomen from January 2017 to June 2022, and further validated on an external data set. Syn-CTA image quality was evaluated using quantitative metrics. In addition, two senior radiologists scored the visual quality on a three-point scale (3 = good) and determined the vascular diagnosis. The validity of Syn-CTA images was evaluated by comparing the visual quality scores and diagnostic accuracy of aortic and carotid artery disease between Syn-CTA and real CTA scans. Results CT scans from 1749 patients (median age, 60 years [IQR, 50-68 years]; 1057 male patients) were included in the internal data set: 1137 for training, 400 for validation, and 212 for testing. The external validation set comprised CT scans from 42 patients (median age, 67 years [IQR, 59-74 years]; 37 male patients). Syn-CTA images had high similarity to real CTA images (normalized mean absolute error, 0.011 and 0.013 for internal and external test set, respectively; peak signal-to-noise ratio, 32.07 dB and 31.58 dB; structural similarity, 0.919 and 0.906). The visual quality of Syn-CTA and real CTA images was comparable (internal test set, P = .35; external validation set, P > .99). Syn-CTA showed reasonable to good diagnostic accuracy for vascular diseases (internal test set: accuracy = 94%, macro F1 score = 91%; external validation set: accuracy = 86%, macro F1 score = 83%). Conclusion A GAN-based model that synthesizes neck and abdominal CTA-like images without the use of ICAs shows promise in vascular diagnosis compared with real CTA images. Clinical trial registration no. NCT05471869 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Zhang and Turkbey in this issue.

The mechanisms of action of mitochondrial targeting agents in cancer: inhibiting oxidative phosphorylation and inducing apoptosis

The tumor microenvironment affects the structure and metabolic function of mitochondria in tumor cells. This process involves changes in metabolic activity, an increase in the amount of reactive oxygen species (ROS) in tumor cells compared to normal cells, the production of more intracellular free radicals, and the activation of oxidative pathways. From a practical perspective, it is advantageous to develop drugs that target mitochondria for the treatment of malignant tumors. Such drugs can enhance the selectivity of treatments for specific cell groups, minimize toxic effects on normal tissues, and improve combinational treatments. Mitochondrial targeting agents typically rely on small molecule medications (such as synthetic small molecules agents, active ingredients of plants, mitochondrial inhibitors or autophagy inhibitors, and others), modified mitochondrial delivery system agents (such as lipophilic cation modification or combining other molecules to form targeted mitochondrial agents), and a few mitochondrial complex inhibitors. This article will review these compounds in three main areas: oxidative phosphorylation (OXPHOS), changes in ROS levels, and endogenous oxidative and apoptotic processes.

Role of OGDH in Atophagy-IRF3-IFN-β pathway during classical swine fever virus infection

Classical swine fever (CSF) is a severe infectious disease caused by the classical swine fever virus (CSFV) that poses significant challenges to the swine industry. α-ketoglutarate dehydrogenase (OGDH), the first rate-limiting enzyme of the tricarboxylic acid (TCA) cycle, catalyzes α-ketoglutarate (α-KG) to succinyl-CoA, playing a crucial role in glycometabolism. Our previous studies showed that CSFV disrupts the TCA cycle, resulting in α-KG accumulation. However, the interplay between CSFV and OGDH remains unclear. In this study, we found that CSFV significantly reduces OGDH protein levels and promotes α-KG secretion through OGDH in PK-15 cells. Furthermore, we observed CSFV C protein interacts with OGDH and revealed that CSFV utilizes NDP52/NBR1 to target OGDH protein degradation in the autophagy-lysosome pathway. We also unveiled that OGDH overexpression inhibits CSFV proliferation, whereas OGDH knockdown increases CSFV proliferation. Further investigation into the mechanisms of OGDH on CSFV replication revealed that OGDH regulates the AMPK-mTOR-autophagy pathway. Additionally, using the autophagy agonist/inhibitor, rapamycin/3-MA, we observed that OGDH modulates autophagy to regulate the IRF3-IFN-β network and CSFV replication. These findings shed light on the role of OGDH in CSFV infection and host metabolism, promoting the development of innovative strategies for combating CSFV and other viral infections via targeting metabolic pathways.

Untargeted plasma metabolome identifies biomarkers in patients with extracranial arteriovenous malformations

Objective: This study aimed to investigate the plasma metabolic profile of patients with extracranial arteriovenous malformations (AVM). Method: Plasma samples were collected from 32 AVM patients and 30 healthy controls (HC). Ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) was employed to analyze the metabolic profiles of both groups. Metabolic pathway enrichment analysis was performed through Kyoto Encyclopedia of Genes and Genomes (KEGG) database and MetaboAnalyst. Additionally, machine learning algorithms such as Least Absolute Shrinkage and Selection Operator (LASSO) and random forest (RF) were conducted to screen characteristic metabolites. The effectiveness of the serum biomarkers for AVM was evaluated using a receiver-operating characteristics (ROC) curve. Result: In total, 184 differential metabolites were screened in this study, with 110 metabolites in positive ion mode and 74 metabolites in negative mode. Lipids and lipid-like molecules were the predominant metabolites detected in both positive and negative ion modes. Several significant metabolic pathways were enriched in AVMs, including lipid metabolism, amino acid metabolism, carbohydrate metabolism, and protein translation. Through machine learning algorithms, nine metabolites were identify as characteristic metabolites, including hydroxy-proline, L-2-Amino-4-methylenepentanedioic acid, piperettine, 20-hydroxy-PGF2a, 2,2,4,4-tetramethyl-6-(1-oxobutyl)-1,3,5-cyclohexanetrione, DL-tryptophan, 9-oxoODE, alpha-Linolenic acid, and dihydrojasmonic acid. Conclusion: Patients with extracranial AVMs exhibited significantly altered metabolic patterns compared to healthy controls, which could be identified using plasma metabolomics. These findings suggest that metabolomic profiling can aid in the understanding of AVM pathophysiology and potentially inform clinical diagnosis and treatment.

H3.3B controls aortic dissection progression by regulating vascular smooth muscle cells phenotypic transition and vascular inflammation

Aortic dissection is a devastating cardiovascular disease with a high lethality. Histone variants maintain the genomic integrity and play important roles in development and diseases. However, the role of histone variants in aortic dissection has not been well identified. In the present study, H3f3b knockdown reduced the synthetic genes expression of VSMCs, while overexpressing H3f3b exacerbated the cellular immune response of VSMCs induced by inflammatory cytokines. Combined RNA-seq and ChIP-seq analyses revealed that histone variant H3.3B directly bound to the genes related to extracellular matrix, VSMC synthetic phenotype, cytokine responses and TGFβ signaling pathway, and regulated their expressions. In addition, VSMC-specific H3f3b knockin aggravated aortic dissection development in mice, while H3f3b knockout significantly reduced the incidence of aortic dissection. In term of mechanisms, H3.3B regulated Spp1 and Ccl2 genes, inducing the apoptosis of VSMCs and recruiting macrophages. This study demonstrated the vital roles of H3.3B in phenotypic transition of VSMCs, loss of media VSMCs, and vascular inflammation in aortic dissection.

Metabolomic characterization benefits the identification of acute lung injury in patients with type A acute aortic dissection

Introduction: Acute aortic dissection (AAD) often leads to the development of acute lung injury (ALI). However, the early detection and diagnosis of AAD in patients with ALI pose significant challenges. The objective of this study is to investigate distinct metabolic alterations in the plasma samples of AAD patients with ALI, AAD patients without ALI, and healthy individuals. Method: Between September 2019 and September 2022, we retrospectively collected data from 228 AAD patients who were diagnosed with ALI through post-surgery chest X-ray and PaO2/FiO2 assessments. Univariate analysis was employed to identify pre-surgery risk factors for ALI. Additionally, we conducted high-throughput target metabolic analysis on 90 plasma samples, comprising 30 samples from AAD patients with ALI, 30 from patients with AAD only, and 30 from healthy controls. After LC-MS spectral processing and metabolite quantification, the recursive feature elimination with cross-validation (RFECV) analysis based on the random forest was used to select the optimal metabolites as a diagnostic panel for the detection of AAD patients with ALI. The support vector machines (SVM) machine learning model was further applied to validate the diagnostic accuracy of the established biomarker panel. Results: In the univariate analysis, preoperative β-HB and TNF-α exhibited a significant association with lung injury (OR = 0.906, 95% CI 0.852-0.965, p = 0.002; OR = 1.007, 95% CI 1.003-1.011, p < 0.0001). The multiple-reaction monitoring analysis of 417 common metabolites identified significant changes in 145 metabolites (fold change >1.2 or <0.833, p < 0.05) across the three groups. Multivariate statistical analysis revealed notable differences between AAD patients and healthy controls. When compared with the non-ALI group, AAD patients with ALI displayed remarkable upregulation in 19 metabolites and downregulation in 4 metabolites. Particularly, combining citric acid and glucuronic acid as a biomarker panel improved the classification performance for distinguishing between the ALI and non-ALI groups. Discussion: Differentially expressed metabolites in the ALI group were primarily involved in amino acids biosynthesis, carbohydrate metabolism (TCA cycle), arginine and proline metabolism, and glucagon signaling pathway. These findings demonstrate a great potential of the targeted metabolomic approach for screening, routine surveillance, and diagnosis of pulmonary injury in patients with AAD.

Metabolomic analysis reveals the metabolic disturbance in aortic dissection: Subtype difference and accurate diagnosis

BACKGROUND AND AIMS

Aortic dissection (AD), a severe clinical emergency with high mortality, is easily misdiagnosed as are other cardiovascular diseases. This study aimed at discovering plasma metabolic markers with the potential to diagnose AD and clarifying the metabolic differences between two subtypes of AD.

METHODS AND RESULTS

To facilitate the diagnosis of AD, we investigated the plasma metabolic profile by metabolomic approach. A total 482 human subjects were enrolled in the study: 80 patients with AD (50 with Stanford type A and 30 with Stanford type B), 198 coronary artery disease (CAD) patients, and 204 healthy individuals. Plasma samples were submitted to targeted metabolomic analysis. The partial least-squares discriminant analysis models were constructed to illustrate clear discrimination of AD patients with CAD patients and healthy control. Subsequently, the metabolites that were clinically relevant to the disturbances in AD were identified. Twenty metabolites induced the separation of AD patients and healthy control, 9 of which caused the separation of CAD patients and healthy control. There are 11 metabolites specifically down-regulated in AD group. Subgroup analysis showed that the levels of glycerol and uridine were dramatically lower in the plasma of patients with Stanford type A AD than those in the healthy control or Stanford type B AD groups.

CONCLUSION

This study characterized metabolomic profiles specifically associated with the pathogenesis and development of AD. The findings of this research may potentially lead to earlier diagnosis and treatment of AD.

Pleiotropic activities of succinate: The interplay between gut microbiota and cardiovascular diseases

Cardiovascular diseases (CVDs) continue to be a significant contributor to global mortality, imposing a substantial burden and emphasizing the urgent need for disease control to save lives and prevent disability. With advancements in technology and scientific research, novel mechanisms underlying CVDs have been uncovered, leading to the exploration of promising treatment targets aimed at reducing the global burden of the disease. One of the most intriguing findings is the relationship between CVDs and gut microbiota, challenging the traditional understanding of CVDs mechanisms and introducing the concept of the gut-heart axis. The gut microbiota, through changes in microbial compositions and functions, plays a crucial role in influencing local and systemic effects on host physiology and disease development, with its metabolites acting as key regulators. In previous studies, we have emphasized the importance of specific metabolites such as betaine, putrescine, trimethylamine oxide, and N,N,N-trimethyl-5-aminovaleric acid in the potential treatment of CVDs. Particularly noteworthy is the gut microbiota-associated metabolite succinate, which has garnered significant attention due to its involvement in various pathophysiological pathways closely related to CVDs pathogenesis, including immunoinflammatory responses, oxidative stress, and energy metabolism. Furthermore, we have identified succinate as a potential biomarker, highlighting its therapeutic feasibility in managing aortic dissection and aneurysm. This review aims to comprehensively outline the characteristics of succinate, including its biosynthetic process, summarize the current evidence linking it to CVDs causation, and emphasize the host-microbial crosstalk involved in modulating CVDs. The insights presented here offer a novel paradigm for future management and control of CVDs.

The role of aldehyde dehydrogenase 2 in cardiovascular disease

Aldehyde dehydrogenase 2 (ALDH2) is a mitochondrial enzyme involved in the detoxification of alcohol-derived acetaldehyde and endogenous aldehydes. The inactivating ALDH2 rs671 polymorphism, present in up to 8% of the global population and in up to 50% of the East Asian population, is associated with increased risk of cardiovascular conditions such as coronary artery disease, alcohol-induced cardiac dysfunction, pulmonary arterial hypertension, heart failure and drug-induced cardiotoxicity. Although numerous studies have attributed an accumulation of aldehydes (secondary to alcohol consumption, ischaemia or elevated oxidative stress) to an increased risk of cardiovascular disease (CVD), this accumulation alone does not explain the emerging protective role of ALDH2 rs671 against ageing-related cardiac dysfunction and the development of aortic aneurysm or dissection. ALDH2 can also modulate risk factors associated with atherosclerosis, such as cholesterol biosynthesis and HDL biogenesis in hepatocytes and foam cell formation and efferocytosis in macrophages, via non-enzymatic pathways. In this Review, we summarize the basic biology and the clinical relevance of the enzymatic and non-enzymatic, tissue-specific roles of ALDH2 in CVD, and discuss the future directions in the research and development of therapeutic strategies targeting ALDH2. A thorough understanding of the complex roles of ALDH2 in CVD will improve the diagnosis, management and prognosis of patients with CVD who harbour the ALDH2 rs671 polymorphism.

Pharmacological effects and mechanisms of YiYiFuZi powder in chronic heart disease revealed by metabolomics and network pharmacology

Introduction: YiYiFuZi powder (YYFZ) is a classical formula in Chinese medicine, which is commonly used clinically for the treatment of Chronic Heart Disease (CHD), but it's pharmacological effects and mechanism of action are currently unclear. Methods: An adriamycin-induced CHD model rat was established to evaluate the pharmacological effects of YYFZ on CHD by the results of inflammatory factor level, histopathology and echocardiography. Metabolomic studies were performed on rat plasma using UPLC-Q-TOF/MS to screen biomarkers and enrich metabolic pathways; network pharmacology analysis was also performed to obtain the potential targets and pathways of YYFZ for the treatment of CHD. Results: The results showed that YYFZ significantly reduced the levels of TNF-α and BNP in the serum of rats, alleviated the disorder of cardiomyocyte arrangement and inflammatory cell infiltration, and improved the cardiac function of rats with CHD. The metabolomic analysis identified a total of 19 metabolites, related to amino acid metabolism, fatty acid metabolism, and other metabolic pathways. Network pharmacology showed that YYFZ acts through PI3K/Akt signaling pathway, MAPK signaling pathway and Ras signaling pathway. Discussion: YYFZ treatment of CHD modulates blood metabolic pattern and several protein phosphorylation cascades but importance specific changes for therapeutic effect require further studies.

The markers and risk stratification model of intracranial aneurysm instability in a large Chinese cohort

Intracranial aneurysm is the leading cause of nontraumatic subarachnoid hemorrhage. Evaluating the unstable (rupture and growth) risk of aneurysms is helpful to guild decision-making for unruptured intracranial aneurysms (UIA). This study aimed to develop a model for risk stratification of UIA instability. The UIA patients from two prospective, longitudinal multicenter Chinese cohorts recruited from January 2017 to January 2022 were set as the derivation cohort and validation cohort. The primary endpoint was UIA instability, comprising aneurysm rupture, growth, or morphology change, during a 2-year follow-up. Intracranial aneurysm samples and corresponding serums from 20 patients were also collected. Metabolomics and cytokine profiling analysis were performed on the derivation cohort (758 single-UIA patients harboring 676 stable UIAs and 82 unstable UIAs). Oleic acid (OA), arachidonic acid (AA), interleukin 1β (IL-1β), and tumor necrosis factor-α (TNF-α) were significantly dysregulated between stable and unstable UIAs. OA and AA exhibited the same dysregulated trends in serums and aneurysm tissues. The feature selection process demonstrated size ratio, irregular shape, OA, AA, IL-1β, and TNF-α as features of UIA instability. A machine-learning stratification model (instability classifier) was constructed based on radiological features and biomarkers, with high accuracy to evaluate UIA instability risk (area under curve (AUC), 0.94). Within the validation cohort (492 single-UIA patients harboring 414 stable UIAs and 78 unstable UIAs), the instability classifier performed well to evaluate the risk of UIA instability (AUC, 0.89). Supplementation of OA and pharmacological inhibition of IL-1β and TNF-α could prevent intracranial aneurysms from rupturing in rat models. This study revealed the markers of UIA instability and provided a risk stratification model, which may guide treatment decision-making for UIAs.

Spontaneous reperfusion enhances succinate concentration in peripheral blood from stemi patients but its levels does not correlate with myocardial infarct size or area at risk

Succinate is enhanced during initial reperfusion in blood from the coronary sinus in ST-segment elevation myocardial infarction (STEMI) patients and in pigs submitted to transient coronary occlusion. Succinate levels might have a prognostic value, as they may correlate with edema volume or myocardial infarct size. However, blood from the coronary sinus is not routinely obtained in the CathLab. As succinate might be also increased in peripheral blood, we aimed to investigate whether peripheral plasma concentrations of succinate and other metabolites obtained during coronary revascularization correlate with edema volume or infarct size in STEMI patients. Plasma samples were obtained from peripheral blood within the first 10 min of revascularization in 102 STEMI patients included in the COMBAT-MI trial (initial TIMI 1) and from 9 additional patients with restituted coronary blood flow (TIMI 2). Metabolite concentrations were analyzed by ¹H-NMR. Succinate concentration averaged 0.069 ± 0.0073 mmol/L in patients with TIMI flow ≤ 1 and was significantly increased in those with TIMI 2 at admission (0.141 ± 0.058 mmol/L, p < 0.05). However, regression analysis did not detect any significant correlation between most metabolite concentrations and infarct size, extent of edema or other cardiac magnetic resonance (CMR) variables. In conclusion, spontaneous reperfusion in TIMI 2 patients associates with enhanced succinate levels in peripheral blood, suggesting that succinate release increases overtime following reperfusion. However, early plasma levels of succinate and other metabolites obtained from peripheral blood does not correlate with the degree of irreversible injury or area at risk in STEMI patients, and cannot be considered as predictors of CMR variables.Trial registration: Registered at www.clinicaltrials.gov (NCT02404376) on 31/03/2015. EudraCT number: 2015-001000-58.

Global proteomic analysis reveals lysine succinylation contributes to the pathogenesis of aortic aneurysm and dissection

Protein lysine succinylation is a recently discovered posttranslational modification. This study examined the role of protein lysine succinylation in the pathogenesis of aortic aneurysm and dissection (AAD). 4D label-free LC-MS/MS analysis was used to perform the global profiles of succinylation in aortas obtained from 5 heart transplant donors, 5 patients with thoracic aortic aneurysm (TAA), and 5 patients with thoracic aortic dissection (TAD). In comparison to normal controls, we detected 1138 succinylated sites from 314 proteins in TAA, and 1499 sites from 381 proteins in TAD. Among these, 120 differentially succinylated sites from 76 proteins overlapped between TAA and TAD (|log2FC| > 0.585, p < 0.05). These differentially modified proteins were mainly localized in the mitochondria and cytoplasm, and were primarily involved in diverse energy metabolic processes, including carbon metabolism, amino acid catabolism, and β-oxidation of fatty acids. By establishing an in vitro model of lysine succinylation in vascular smooth muscle cells, we observed changes in the activities of three key metabolic enzymes (PKM, LDHA, and SDHA). These findings suggest that succinylation potentially contributes to the pathogenesis of aortic diseases, and presents a valuable resource for investigating the functional roles and regulatory mechanisms of succinylation in AAD. SIGNIFICANCE: AAD are interrelated life-threatening diseases associated with high morbidity and mortality. Although we discovered that lysine succinylation was significantly up-regulated in the aorta tissues of patients with AAD, its role in the progression of aortic diseases is largely unknown. We conducted a 4D label-free LC-MS/MS analysis and identified 120 differentially succinylated sites on 76 proteins that overlapped between TAA and TAD as compared to normal controls. Lysine succinylation may contribute to the pathogenesis of AAD by regulating energy metabolism pathways. The proteins containing succinylated sites could be served as potential diagnostic markers and therapeutic targets for aortic diseases.

Small molecule metabolites: discovery of biomarkers and therapeutic targets

Metabolic abnormalities lead to the dysfunction of metabolic pathways and metabolite accumulation or deficiency which is well-recognized hallmarks of diseases. Metabolite signatures that have close proximity to subject's phenotypic informative dimension, are useful for predicting diagnosis and prognosis of diseases as well as monitoring treatments. The lack of early biomarkers could lead to poor diagnosis and serious outcomes. Therefore, noninvasive diagnosis and monitoring methods with high specificity and selectivity are desperately needed. Small molecule metabolites-based metabolomics has become a specialized tool for metabolic biomarker and pathway analysis, for revealing possible mechanisms of human various diseases and deciphering therapeutic potentials. It could help identify functional biomarkers related to phenotypic variation and delineate biochemical pathways changes as early indicators of pathological dysfunction and damage prior to disease development. Recently, scientists have established a large number of metabolic profiles to reveal the underlying mechanisms and metabolic networks for therapeutic target exploration in biomedicine. This review summarized the metabolic analysis on the potential value of small-molecule candidate metabolites as biomarkers with clinical events, which may lead to better diagnosis, prognosis, drug screening and treatment. We also discuss challenges that need to be addressed to fuel the next wave of breakthroughs.

Changes of gut microbiota and tricarboxylic acid metabolites may be helpful in early diagnosis of necrotizing enterocolitis: A pilot study

Purpose

We aimed to explore the value of gut microbiota and tricarboxylic acid (TCA) metabolites in early diagnosis of necrotizing enterocolitis (NEC) among infants with abdominal manifestations.

Methods

Thirty-two preterm infants with abdominal manifestations at gestational age ≤ 34 weeks were included in the study and were divided into non-NEC (n = 16) and NEC (n = 16) groups. Faecal samples were collected when the infants were enrolled. The gut microbiota was analysed with high-throughput sequencing, and TCA metabolites were measured with multiple reaction monitoring (MRM) targeted metabolomics. Receiver operating characteristic (ROC) curves were generated to explore the predictive value of the obtained data.

Results

There was no significant difference in alpha diversity or beta diversity between the two groups (p &gt; 0.05). At the phylum level, Proteobacteria increased, and Actinomycetota decreased in the NEC group (p &lt; 0.05). At the genus level, Bifidobacterium and Lactobacillaceae decreased significantly, and at the species level, unclassified Staphylococcus, Lactobacillaceae and Bifidobacterium animalis subsp. lactis decreased in the NEC group (p &lt; 0.05). Further Linear discriminant analysis effect sizes (LEfSe) analysis showed that the change in Proteobacteria at the phylum level and Lactobacillaceae and Bifidobacterium at the genus level scored higher than 4. The concentrations of succinate, L-malic acid and oxaloacetate in the NEC group significantly increased (p &lt; 0.05), and the areas under the ROC curve for these metabolites were 0.6641, 0.7617, and 0.7344, respectively.

Conclusion

Decreased unclassified Staphylococcus, Lactobacillaceae and Bifidobacterium animalis subsp. lactis at the species level as well as the increase in the contents of some TCA metabolites, including succinate, L-malic acid and oxaloacetate, have potential value for the early diagnosis of NEC.

ADAMTS-7 deficiency attenuates thoracic aortic aneurysm and dissection in mice

Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening cardiovascular disease with severe extracellular matrix (ECM) remodeling that lacks efficient early stage diagnosis and nonsurgical therapy. A disintegrin and metalloproteinase with thrombospondin motif 7 (ADAMTS-7) is recognized as a novel locus for human coronary artery atherosclerosis. Previous work by us and others showed that ADAMTS-7 promoted atherosclerosis, postinjury neointima formation, and vascular calcification. However, whether ADAMTS-7 is involved in TAAD pathogenesis is unknown. We aimed to explore the alterations in ADAMTS-7 expression in human and mouse TAAD, and investigate the role of ADAMTS-7 in TAAD formation. A case-control study of TAAD patients (N = 86) and healthy participants (N = 88) was performed. The plasma ADAMTS-7 levels were markedly increased in TAAD patients within 24 h and peaked in 7 days. A TAAD mouse model was induced with 0.5% β-aminopropionitrile (BAPN) in drinking water. ELISA analysis of mouse plasma, Western blotting, and immunohistochemical staining of aorta showed an increase in ADAMTS-7 in the early stage of TAAD. Moreover, ADAMTS-7-deficient mice exhibited significantly attenuated TAAD formation and TAAD rupture-related mortality in both male and female mice, which was accompanied by reduced artery dilation and inhibited elastin degradation. ADAMTS-7 deficiency caused repressed inflammatory response and complement system activation during TAAD formation. An increase in plasma ADAMTS-7 is a novel biomarker for human TAAD. ADAMTS-7 deficiency attenuates BAPN-induced murine TAAD. ADAMTS-7 is a potential novel target for TAAD diagnosis and therapy. KEY MESSAGES: A case-control study revealed increased plasma ADAMTS-7 is a risk factor for TAAD. ADAMTS-7 was elevated in plasma and aorta at early stage of mouse TAAD. ADAMTS-7 knockout attenuated mouse TAAD formation and mortality in both sexes.

The mechanism and therapy of aortic aneurysms

Aortic aneurysm is a chronic aortic disease affected by many factors. Although it is generally asymptomatic, it poses a significant threat to human life due to a high risk of rupture. Because of its strong concealment, it is difficult to diagnose the disease in the early stage. At present, there are no effective drugs for the treatment of aneurysms. Surgical intervention and endovascular treatment are the only therapies. Although current studies have discovered that inflammatory responses as well as the production and activation of various proteases promote aortic aneurysm, the specific mechanisms remain unclear. Researchers are further exploring the pathogenesis of aneurysms to find new targets for diagnosis and treatment. To better understand aortic aneurysm, this review elaborates on the discovery history of aortic aneurysm, main classification and clinical manifestations, related molecular mechanisms, clinical cohort studies and animal models, with the ultimate goal of providing insights into the treatment of this devastating disease. The underlying problem with aneurysm disease is weakening of the aortic wall, leading to progressive dilation. If not treated in time, the aortic aneurysm eventually ruptures. An aortic aneurysm is a local enlargement of an artery caused by a weakening of the aortic wall. The disease is usually asymptomatic but leads to high mortality due to the risk of artery rupture.

Gasdermin D Deficiency in Vascular Smooth Muscle Cells Ameliorates Abdominal Aortic Aneurysm Through Reducing Putrescine Synthesis

Abdominal aortic aneurysm (AAA) is a common vascular disease associated with significant phenotypic alterations in vascular smooth muscle cells (VSMCs). Gasdermin D (GSDMD) is a pore-forming effector of pyroptosis. In this study, the role of VSMC-specific GSDMD in the phenotypic alteration of VSMCs and AAA formation is determined. Single-cell transcriptome analyses reveal Gsdmd upregulation in aortic VSMCs in angiotensin (Ang) II-induced AAA. VSMC-specific Gsdmd deletion ameliorates Ang II-induced AAA in apolipoprotein E (ApoE)^-/- mice. Using untargeted metabolomic analysis, it is found that putrescine is significantly reduced in the plasma and aortic tissues of VSMC-specific GSDMD deficient mice. High putrescine levels trigger a pro-inflammatory phenotype in VSMCs and increase susceptibility to Ang II-induced AAA formation in mice. In a population-based study, a high level of putrescine in plasma is associated with the risk of AAA (p < 2.2 × 10^-16 ), consistent with the animal data. Mechanistically, GSDMD enhances endoplasmic reticulum stress-C/EBP homologous protein (CHOP) signaling, which in turn promotes the expression of ornithine decarboxylase 1 (ODC1), the enzyme responsible for increased putrescine levels. Treatment with the ODC1 inhibitor, difluoromethylornithine, reduces AAA formation in Ang II-infused ApoE^-/- mice. The findings suggest that putrescine is a potential biomarker and target for AAA treatment.

Succinate-SUCNR1 induces renal tubular cell apoptosis

Succinate has long been known to be only an intermediate product of the tricarboxylic acid cycle until identified as a natural ligand for SUCNR1 in 2004. SUCNR1 is widely expressed throughout the body, especially in the kidney. Abnormally elevated succinate is associated with many diseases, including obesity, type 2 diabetes, nonalcoholic fatty liver disease, and ischemia injury, but it is not known whether succinate can cause kidney damage. This study showed that succinate induced apparent renal injury after treatment for 12 wk, characterized by a reduction in 24 h urine and the significant detachment of the brush border of proximal tubular epithelial cells, tubular dilation, cast formation, and vacuolar degeneration of tubular cells in succinate-treated mice. Besides, succinate caused tubular epithelial cell apoptosis in kidneys and HK-2 cells. Mechanistically, succinate triggered cell apoptosis via SUCNR1 activation. In addition, succinate upregulated ERK by binding to SUCNR1, and inhibition of ERK using PD98059 abolished the proapoptotic effects of succinate in HK-2 cells. In summary, our study provides the first evidence that succinate acts as a risk factor and contributes to renal injury, and further research is required to discern the pathological effects of succinate on renal functions.

Integration of LC-MS-Based and GC-MS-Based Metabolic Profiling to Reveal the Effects of Domestication and Boiling on the Composition of Duck Egg Yolks

Egg yolks contain abundant lipids, proteins, and minerals that provide not only essential nutrients for embryonic development but also cheap sources of nutrients for consumers worldwide. Previous composition analyses of egg yolks primarily focused on nutrients such as lipids and minerals. However, few studies have reported the effects of domestication and heating on yolk composition and characteristics. The objective of this study was to investigate the impact of domestication and boiling on the metabolite contents of egg yolks via untargeted metabolomics using GC-MS and LC-MS. In this study, eggs were collected from Fenghua teals, captive mallards, and Shaoxing ducks. Twelve duck eggs (half raw and half cooked) were randomly selected from each variety, and the egg yolks were separated for metabolic profiling. The analysis identified 1205 compounds in the egg yolks. Domestication generated more differential metabolites than boiling, which indicated that the changes in the metabolome of duck egg yolk caused by domestication were greater than those caused by boiling. In a comparative analysis of domestic and mallard ducks, 48 overlapping differential metabolites were discovered. Among them, nine metabolites were upregulated in domesticated ducks, including monoolein, emodin, daidzein, genistein, and glycitein, which may be involved in lipid metabolism; some of them may also act as phytoestrogens (flavonoids). Another 39 metabolites, including imethylethanolamine, harmalan, mannitol, nornicotine, linoleic acid, diphenylamine, proline betaine, alloxanthin, and resolvin d1, were downregulated by domestication and were linked to immunity, anti-inflammatory, antibacterial, and antioxidant properties. Furthermore, four overlapping differential metabolites that included amino acids and dipeptides were discovered in paired comparisons of the raw and boiled samples. Our findings provided new insights into the molecular response of duck domestication and supported the use of metabolomics to examine the impact of boiling on the composition of egg yolks.

Aorta- and liver-generated TMAO enhances trained immunity for increased inflammation via ER stress/mitochondrial ROS/glycolysis pathways

We determined whether gut microbiota-produced trimethylamine (TMA) is oxidized into trimethylamine N-oxide (TMAO) in nonliver tissues and whether TMAO promotes inflammation via trained immunity (TI). We found that endoplasmic reticulum (ER) stress genes were coupregulated with MitoCarta genes in chronic kidney diseases (CKD); TMAO upregulated 190 genes in human aortic endothelial cells (HAECs); TMAO synthesis enzyme flavin-containing monooxygenase 3 (FMO3) was expressed in human and mouse aortas; TMAO transdifferentiated HAECs into innate immune cells; TMAO phosphorylated 12 kinases in cytosol via its receptor PERK and CREB, and integrated with PERK pathways; and PERK inhibitors suppressed TMAO-induced ICAM-1. TMAO upregulated 3 mitochondrial genes, downregulated inflammation inhibitor DARS2, and induced mitoROS, and mitoTEMPO inhibited TMAO-induced ICAM-1. β-Glucan priming, followed by TMAO restimulation, upregulated TNF-α by inducing metabolic reprogramming, and glycolysis inhibitor suppressed TMAO-induced ICAM-1. Our results have provided potentially novel insights regarding TMAO roles in inducing EC activation and innate immune transdifferentiation and inducing metabolic reprogramming and TI for enhanced vascular inflammation, and they have provided new therapeutic targets for treating cardiovascular diseases (CVD), CKD-promoted CVD, inflammation, transplantation, aging, and cancer.

Tandem mass tag-based quantitative proteomic analysis identification of succinylation related proteins in pathogenesis of thoracic aortic aneurysm and aortic dissection

Background

Thoracic aortic aneurysm and dissection (TAAD) are devastating cardiovascular diseases with a high rate of disability and mortality. Lysine succinylation, a newly found post-translational modification, has been reported to play an important role in cardiovascular diseases. However, how succinylation modification influences TAAD remains obscure.

Methods

Ascending aortic tissues were obtained from patients with thoracic aortic aneurysm (TAA, n = 6), thoracic aortic dissection (TAD) with pre-existing aortic aneurysm (n = 6), and healthy subjects (n = 6). Global lysine succinylation level was analyzed by Western blotting. The differentially expressed proteins (DEPs) were analyzed by tandem mass tag (TMT) labeling and mass spectrometry. Succinylation-related proteins selected from the literature review and AmiGO database were set as a reference inventory for further analysis. Then, the pathological aortic sections were chosen to verify the proteomic results by Western blotting and qRT-PCR.

Results

The level of global lysine succinylation significantly increased in TAA and TAD patients compared with healthy subjects. Of all proteins identified by proteomic analysis, 197 common DEPs were screened both in TAA and TAD group compared with the control group, of which 93 proteins were significantly upregulated while 104 were downregulated. Among these 197 DEPs, OXCT1 overlapped with the succinylation-related proteins and was selected as the target protein involved in thoracic aortic pathogenesis. OXCT1 was further verified by Western blotting and qRT-PCR, and the results showed that OXCT1 in TAA and TAD patients was significantly lower than that in healthy donors (p < 0.001), which was consistent with the proteomic results.

Conclusions

OXCT1 represents novel biomarkers for lysine succinylation of TAAD and might be a therapeutic target in the future.

Gut microbiome and metabolites, the future direction of diagnosis and treatment of atherosclerosis?

Over the past few decades, the treatment of atherosclerotic cardiovascular disease has mainly been through an LDL lowering strategy and treatments targeting other traditional risk factors for atherosclerosis, which has significantly reduced cardiovascular mortality. However, the overall benefit of targeting these risk factors has stagnated, and the discovery of new therapeutic targets for atherosclerosis remains a challenge. Accumulating evidence from clinical and animal experiments has revealed that the gut microbiome play a significant role in human health and disease, including cardiovascular diseases. The gut microbiome contribute to host health and disease through microbial composition and function. The gut microbiome function like an endocrine organ by generating bioactive metabolites that can impact atherosclerosis. In this review, we describe two gut microbial metabolites/pathways by which the gut affects atherosclerotic cardiovascular disease. On the one hand, we discuss the effects of trimethylamine oxide (TMAO), bile acids and aromatic amino acid metabolites on the development of atherosclerosis, and the protective effects of beneficial metabolites short chain amino acids and polyamines on atherosclerosis. On the other hand, we discuss novel therapeutic strategies for directly targeting gut microbial metabolites to improve cardiovascular outcomes. Reducing gut-derived TMAO levels and interfering with the bile acid receptor farnesoid X receptor (FXR) are new therapeutic strategies for atherosclerotic disease. Enzymes and receptors in gut microbiota metabolic pathways are potential new drug targets. We need solid insight into these underlying mechanisms to pave the way for therapeutic strategies targeting gut microbial metabolites/pathways for atherosclerotic cardiovascular disease.

Changes in the gut microbiome of patients with type a aortic dissection

Objective

To investigate the characteristic changes in the gut microbiota of patients with type A aortic dissection (AAD) and provide a theoretical basis for future microbiome-oriented interventional studies.

Methods

High-throughput 16S rDNA sequencing was performed on the stool samples of patients with and without (healthy control subjects) AAD. Using alpha and beta diversity analysis, we compared the gut microbiota composition of 20 patients with AAD and 20 healthy controls matched for gender, age, BMI, and geographical region. The accuracy of AAD prediction by differential microbiome was calculated using the random forest machine learning model. Targeted measurement of the plasma concentration of short-chain fatty acids (SCFAs), which are the main metabolites of the gut microbiome, was performed using gas chromatography-mass spectrometry (GC-MS). Spearman's correlation analysis was conducted to determine the relationships of gut microbiome and SCFAs with the clinical characteristics of subjects.

Results

The differences in gut microbiota alpha diversity between patients with AAD and the healthy controls were not statistically significant (Shannon index: p = 0.19; Chao1: p = 0.4); however, the microbiota composition (beta diversity) was significantly different between the two groups (Anosim, p = 0.001). Bacteroidota was enriched at the phylum level, and the SCFA-producing genera Prevotella, Porphyromonas, Lachnospiraceae, and Ruminococcus and inflammation-related genera Fenollaria and Sutterella were enriched at the genus level in the AAD group compared with those in the control group. The random forest model could predict AAD from gut microbiota composition with an accuracy of 87.5% and the area-under-curve (AUC) of the receiver operating characteristic curve was 0.833. The SCFA content of patients with AAD was higher than that of the control group, with the difference being statistically significant (p < 0.05). The different microflora and SCFAs were positively correlated with inflammatory cytokines.

Conclusion

To the best of our knowledge, this is the first demonstration of the presence of significant differences in the gut microbiome of patients with AAD and healthy controls. The differential microbiome exhibited high predictive potential toward AAD and was positively correlated with inflammatory cytokines. Our results will assist in the development of preventive and therapeutic treatment methods for patients with AAD.

Succinate metabolism and its regulation of host-microbe interactions

Succinate is a circulating metabolite, and the relationship between abnormal changes in the physiological concentration of succinate and inflammatory diseases caused by the overreaction of certain immune cells has become a research focus. Recent investigations have shown that succinate produced by the gut microbiota has the potential to regulate host homeostasis and treat diseases such as inflammation. Gut microbes are important for maintaining intestinal homeostasis. Microbial metabolites serve as nutrients in energy metabolism, and act as signal molecules that stimulate host cell and organ function and affect the structural balance between symbiotic gut microorganisms. This review focuses on succinate as a metabolite of both host cells and gut microbes and its involvement in regulating the gut - immune tissue axis by activating intestinal mucosal cells, including macrophages, dendritic cells, and intestinal epithelial cells. We also examined its role as the mediator of microbiota - host crosstalk and its potential function in regulating intestinal microbiota homeostasis. This review explores feasible ways to moderate succinate levels and provides new insights into succinate as a potential target for microbial therapeutics for humans.

Impact of combined chronic exposure to low-dose bisphenol A and fructose on serum adipocytokines and the energy target metabolome in white adipose tissue

Background: Adipose tissue is a dynamic endocrine organ that plays a key role in regulating metabolic homeostasis. Previous studies confirmed that bisphenol A (BPA) or fructose can interfere with the function of adipose tissue. Nonetheless, knowledge on how exposure to BPA and fructose impacts energy metabolism in adipose tissue remains limited.Purpose: To determine impact of combined chronic exposure to low-dose bisphenol A and fructose on serum adipocytokines and the energy target metabolome in white adipose tissue.Method: 57 energy metabolic intermediates in adipose tissue and 7 adipocytokines in serum from Sprague Dawley rats were examined after combined exposure to two levels of BPA (lower dose: 0.25, and higher dose: 25 μg/kg every other day) and 5% fructose for 6 months.Results: combined exposure to lower-dose BPA and fructose significantly increased omentin-1, pyruvic acid, adenosine triphosphate (ATP), adenosine monophosphate (AMP), inosine monophosphate (IMP), inosine, and l-lactate; however, these parameters were not significantly affected by higher-dose BPA combined with fructose. Interestingly, the level of succinate (an intermediate of the citric acid cycle) increased dose-dependently in adipose tissue, and the level of apelin 13 (a versatile adipocytokine) decreased dose-dependently in serum after combined exposure to BPA and fructose. Phosphoenolpyruvic acid, phenyl-lactate, and ornithine were significantly correlated with asprosin, omentin-1, apelin, apelin 13, and adiponectin, while l-tyrosine was significantly correlated with irisin and a-FABP under combined exposure to BPA and fructose.Conclusions: these findings indicated that lower-dose BPA combined with fructose could amplify the impact on glycolysis, energy storage, and purine nucleotide biosynthesis in adipose tissue, and adipocytokines, such as omentin-1 and apelin 13, may be related to metabolic interference induced by BPA and fructose exposure.

EASY-FIA: A Readably Usable Standalone Tool for High-Resolution Mass Spectrometry Metabolomics Data Pre-Processing

Flow injection analysis coupled with high-resolution mass spectrometry (FIA-HRMS) is a fair trade-off between resolution and speed. However, free software available for data pre-processing is few, web-based, and often requires advanced user specialization. These tools rarely embedded blank and noise evaluation strategies, and direct feature annotation. We developed EASY-FIA, a free standalone application that can be employed for FIA-HRMS metabolomic data pre-processing by users with no bioinformatics/programming skills. We validated the tool's performance and applicability in two clinical metabolomics case studies. The main functions of our application are blank subtraction, alignment of the metabolites, and direct feature annotation by means of the Human Metabolome Database (HMDB) using a minimum number of mass spectrometry parameters. In a scenario where FIA-HRMS is increasingly recognized as a reliable strategy for fast metabolomics analysis, EASY-FIA could become a standardized and feasible tool easily usable by all scientists dealing with MS-based metabolomics. EASY-FIA was implemented in MATLAB with the App Designer tool and it is freely available for download.

Applying multi-omics techniques to the discovery of biomarkers for acute aortic dissection

Acute aortic dissection (AAD) is a cardiovascular disease that manifests suddenly and fatally. Due to the lack of specific early symptoms, many patients with AAD are often overlooked or misdiagnosed, which is undoubtedly catastrophic for patients. The particular pathogenic mechanism of AAD is yet unknown, which makes clinical pharmacological therapy extremely difficult. Therefore, it is necessary and crucial to find and employ unique biomarkers for Acute aortic dissection (AAD) as soon as possible in clinical practice and research. This will aid in the early detection of AAD and give clear guidelines for the creation of focused treatment agents. This goal has been made attainable over the past 20 years by the quick advancement of omics technologies and the development of high-throughput tissue specimen biomarker screening. The primary histology data support and add to one another to create a more thorough and three-dimensional picture of the disease. Based on the introduction of the main histology technologies, in this review, we summarize the current situation and most recent developments in the application of multi-omics technologies to AAD biomarker discovery and emphasize the significance of concentrating on integration concepts for integrating multi-omics data. In this context, we seek to offer fresh concepts and recommendations for fundamental investigation, perspective innovation, and therapeutic development in AAD.

Effects of Malate Ringer's solution on myocardial injury in sepsis and enforcement effects of TPP@PAMAM-MR

BACKGROUND

Myocardial dysfunction played a vital role in organ damage after sepsis. Fluid resuscitation was the essential treatment in which Lactate Ringer's solution (LR) was commonly used. Since LR easily led to hyperlactatemia, its resuscitation effect was limited. Malate Ringer's solution (MR) was a new resuscitation crystal liquid. Whether MR had a protective effect on myocardial injury in sepsis and the relevant mechanism need to be studied.

METHODS

The cecal ligation and puncture (CLP) inducing septic model and lipopolysaccharide (LPS) stimulating cardiomyocytes were used, and the cardiac function, the morphology and function of mitochondria were observed. The protective mechanism of MR on myocardial injury was explored by proteomics. Then the effects of TPP@PAMAM-MR, which consisted of the mitochondria- targeting polymer embodied malic acid, was further observed.

RESULTS

Compared with LR, MR resuscitation significantly prolonged survival time, improved the cardiac function, alleviated the damages of liver, kidney and lung following sepsis in rats. The proteomics of myocardial tissue showed that differently expressed proteins between MR and LR infusion involved oxidative phosphorylation, apoptosis. Further study found that MR decreased ROS, improved the mitochondrial morphology and function, and ultimately enhanced mitochondrial respiration and promoted ATP production. Moreover, MR infusion decreased the expression of apoptosis-related proteins and increased the expression of anti-apoptotic proteins. TPP@PAMAM@MA was a polymer formed by wrapping L-malic acid with poly amido amine (PAMAM) modified triphenylphosphine material. TPP@PAMAM-MR (TPP-MR), which was synthesized by replacing the L-malic acid of MR with TPP@PAMAM@MA, was more efficient in targeting myocardial mitochondria and was superior to MR in protecting the sepsis-inducing myocardial injury.

CONCLUSION

MR was suitable for protecting myocardial injury after sepsis. The mechanism was related to MR improving the function and morphology of cardiomyocyte mitochondria and inhibiting cardiomyocyte apoptosis. The protective effect of TPP-MR was superior to MR.

Arachidonic acid is associated with dyslipidemia and cholesterol-related lipoprotein metabolism signatures

Introduction

Abnormal lipoprotein metabolism is associated with a variety of diseases, cardiovascular disease in particular. Free fatty acids (FAs) and triglycerides (TGs) are the principal lipid species in adipocytes and are the major components of lipoproteins. However, in routine clinical laboratory testing, only the total plasma concentrations of FAs and TGs are typically measured.

Methods

We collected 965 individuals with hyperlipidemia plasma and clinical characteristics; high-throughput metabolomics permits the accurate qualitative and quantitative assessment of a variety of specific FAs and TGs and their association with lipoproteins; through regression analysis, the correlation between multiple metabolites and routine measured lipid parameters was found. Mice were fed a diet containing AA, and the concentrations of TC and TG in the plasma of mice were detected by enzyme method, western blot and qRT-PCR detected the protein and mRNA levels of cholesterol synthesis and metabolism in mice.

Result

Using LC-MS/MS identified eight free FA and 27 TG species in plasma samples, the plasma concentrations of free arachidonic acid (AA) and AA-enriched TG species were significantly associated with the plasma low-density lipoprotein-cholesterol, apolipoprotein B (ApoB), and total cholesterol (TC) concentrations after adjustment for age, sex, the use of lipid-lowering therapy, and body mass index. AA-rich diet significantly increased the plasma concentrations of TC and ApoB and the liver expression of ApoB protein and reduced the protein expression of ATP binding cassette subfamily G members 5 and 8 in mice.

Discussion

In this study, it was clarified that the plasma concentrations of free AA- and AA-enriched TG species were significantly associated with the plasma low-density lipoprotein-cholesterol, ApoB, and TC concentrations in individuals with hyperlipidemia, and it was verified that AA could increase the plasma TC level in mice. Taken together, these findings suggest a potential role of AA in the regulation of plasma cholesterol and lipoprotein concentrations.

Nuclear Receptor NR1D1 Regulates Abdominal Aortic Aneurysm Development by Targeting the Mitochondrial Tricarboxylic Acid Cycle Enzyme Aconitase-2

BACKGROUND

Metabolic disorder increases the risk of abdominal aortic aneurysm (AAA). NRs (nuclear receptors) have been increasingly recognized as important regulators of cell metabolism. However, the role of NRs in AAA development remains largely unknown.

METHODS

We analyzed the expression profile of the NR superfamily in AAA tissues and identified NR1D1 (NR subfamily 1 group D member 1) as the most highly upregulated NR in AAA tissues. To examine the role of NR1D1 in AAA formation, we used vascular smooth muscle cell (VSMC)-specific, endothelial cell-specific, and myeloid cell-specific conditional Nr1d1 knockout mice in both AngII (angiotensin II)- and CaPO₄-induced AAA models.

RESULTS

Nr1d1 gene expression exhibited the highest fold change among all 49 NRs in AAA tissues, and NR1D1 protein was upregulated in both human and murine VSMCs from AAA tissues. The knockout of Nr1d1 in VSMCs but not endothelial cells and myeloid cells inhibited AAA formation in both AngII- and CaPO₄-induced AAA models. Mechanistic studies identified ACO2 (aconitase-2), a key enzyme of the mitochondrial tricarboxylic acid cycle, as a direct target trans-repressed by NR1D1 that mediated the regulatory effects of NR1D1 on mitochondrial metabolism. NR1D1 deficiency restored the ACO2 dysregulation and mitochondrial dysfunction at the early stage of AngII infusion before AAA formation. Supplementation with αKG (α-ketoglutarate, a downstream metabolite of ACO2) was beneficial in preventing and treating AAA in mice in a manner that required NR1D1 in VSMCs.

CONCLUSIONS

Our data define a previously unrecognized role of nuclear receptor NR1D1 in AAA pathogenesis and an undescribed NR1D1-ACO2 axis involved in regulating mitochondrial metabolism in VSMCs. It is important that our findings suggest αKG supplementation as an effective therapeutic approach for AAA treatment.

Loss of myeloid Tsc2 predisposes to angiotensin II-induced aortic aneurysm formation in mice

RATIONALE

Genetic studies have proved the involvement of Tuberous sclerosis complex subunit 2 (Tsc2) in aortic aneurysm. However, the exact role of macrophage Tsc2 in the vascular system remains unclear. Here, we examined the potential function of macrophage Tsc2 in the development of aortic remodeling and aortic aneurysms.

METHODS AND RESULTS

Conditional gene knockout strategy combined with histology and whole-transcriptomic analysis showed that Tsc2 deficiency in macrophages aggravated the progression of aortic aneurysms along with an upregulation of proinflammatory cytokines and matrix metallopeptidase-9 in the angiotensin II-induced mouse model. G protein-coupled receptor 68 (Gpr68), a proton-sensing receptor for detecting the extracellular acidic pH, was identified as the most up-regulated gene in Tsc2 deficient macrophages compared with control macrophages. Additionally, Tsc2 deficient macrophages displayed higher glycolysis and glycolytic inhibitor 2-deoxy-D-glucose treatment partially attenuated the level of Gpr68. We further demonstrated an Tsc2-Gpr68-CREB network in macrophages that regulates the inflammatory response, proteolytic degradation and vascular homeostasis. Gpr68 inhibition largely abrogated the progression of aortic aneurysms caused by Tsc2 deficiency in macrophages.

CONCLUSIONS

The findings reveal that Tsc2 deficiency in macrophages contributes to aortic aneurysm formation, at least in part, by upregulating Gpr68 expression, which subsequently drives proinflammatory processes and matrix metallopeptidase activation. The data also provide a novel therapeutic strategy to limit the progression of the aneurysm resulting from Tsc2 mutations.

Potential metabolomic biomarkers for the identification and diagnosis of type A acute aortic dissection in patients with hypertension

Objectives

Most patients with acute aortic dissection (AAD) have a history of hypertension. Diagnosis of AAD in patients with hypertension at an early stage is complicated and challenging. This study aimed to explore the distinctive metabolic changes in plasma samples of AAD patients with hypertension and patients with hypertension only and provide early identification and diagnosis of AAD in patients with hypertension.

Materials and methods

We collected blood samples from 20 patients with type A AAD and hypertension admitted to the emergency department and physically examined other 20 patients with hypertension as controls. The plasma metabolomic profiles of these patients were determined using untargeted metabolomics with ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry.

Results

A total of 38 metabolites that differed between the AAD and hypertension groups were screened. In the positive ion mode, 12 metabolites were different between the two groups, and in the negative ion mode, 26 metabolites were different. Among the 26 different metabolites detected by the negative ion mode, 21 were significantly upregulated and five were downregulated in patients with AAD compared to patients with hypertension. Moreover, five metabolites were upregulated and seven were significantly downregulated in patients with AAD compared to those with hypertension, as detected by the positive ion mode. The metabolites differentially expressed in AAD were mainly involved in lipid metabolism (fatty acid biosynthesis, biosynthesis of unsaturated fatty acids, and linoleic acid metabolism), carbohydrate metabolism (galactose, fructose, and mannose metabolisms), and membrane transport (ATP-binding cassette transporters). Interestingly, plasma hydrocortisone and dimethylglycine concentrations were significantly increased in patients with type A AAD, with the highest area under the curve value (AUC = 0.9325 or 0.9200, respectively) tested by the receiver operating characteristic curve analysis.

Conclusion

This study provides possible metabolic markers for the early clinical diagnosis of AAD in patients with hypertension.