FXR/ASS1 axis attenuates the TAA-induced liver injury through arginine metabolism

Crataegus pinnatifida polysaccharide alleviates DSS-induced colitis in mice by regulating the intestinal microbiota and enhancing arginine biosynthesis

BACKGROUND

The development of effective and safe dietary supplements is essential for both the prevention and management of ulcerative colitis (UC), as its pathogenesis is intricate and difficult to completely resolve. Crataegus pinnatifida, a medicinal food with a long history of use, has broad medicinal value. Recent research has revealed promising insights into the role of polysaccharide derived from Crataegus pinnatifida on modulating short-chain fatty acids (SCFAs) to alleviate UC inflammation. However, the mechanisms by which CPP regulates the intestinal microbiota and key metabolites during the antagonistic phase of UC have yet to be elucidated.

OBJECTIVE

This research elucidated the protective role of CPP in relation to UC, highlighted the mechanisms through which CPP operates, particularly regarding gut microbiota and metabolism, and offered a theoretical foundation for the potential use of CPP as a dietary supplement aimed at preventing UC.

METHODS

The impact of CPP on acute UC induced by 3 % DSS in mice was examined through the evaluation of the disease activity index, measurement of colon length, and observation of body weight changes. Enzyme-linked immunosorbent assay (ELISA) was used to measure inflammatory factor levels in both serum and colon, as well as to assess oxidative stress mediators. The intestinal histological damage, mucus layer damage and the level of tight junction protein were analyzed by histopathological staining and western blot (WB). The impact of gut microbiota on CPP in colitis was evaluated using 16S rRNA sequencing, microbiota depletion experiments, and fecal microbiota transplantation (FMT) studies. The key metabolic pathways and key metabolites affected by CPP in the treatment of UC were analyzed through untargeted metabolomics sequencing, ELISA, and WB assays.

RESULTS

Prophylactic dietary supplementation with Crataegus pinnatifida polysaccharide (CPP) notably reduced the fundamental clinical manifestations of UC induced by DSS, including DAI score, reduced colon length, and weight loss, as well as inflammation and oxidative stress. CPP promoted the expression of Claudin-1, ZO-1 and Occludin and promoted mucin secretion, which contributed to the mitigation of intestinal barrier damage caused by DSS. 16S sequencing results and metabolomics results revealed that CPP intervention upregulated the relative abundance of Lactobacillus, thereby reshaping the intestinal microbiota and activate the arginine biosynthesis pathway. The results of fecal microbiota transplantation and antibiotic clearance experiments indicated that the alleviating effect of CPP on UC was dependent on the intestinal microbiota and this alleviating effect was transferred through fecal microbiota transplantation. Mechanistically, CPP indirectly promoted the expression of the rate-limiting enzyme argininosuccinate synthase 1 (ASS1) in the intestinal Arginine biosynthesis pathway by reshaping the intestinal microbiota, thereby increasing intestinal Arginine level and alleviating the inflammatory response and oxidative stress induced by DSS and intestinal barrier damage.

CONCLUSION

Our research findings demonstrate that CPP is a plant-derived polysaccharide that alleviates UC by modulating the gut microbiota and enhancing arginine biosynthesis.

Farnesoid X receptor activation alleviates hepatic encephalopathy by improving hepatic ammonia metabolism in murine models

BACKGROUND

Hepatic encephalopathy (HE) is a mental and neurological complication induced by acute or chronic hepatic failure. Emerging evidence indicates that the farnesoid X receptor (FXR), a multifunctional nuclear receptor and transcription factor, plays a pivotal role in regulating the expression of key genes associated with ammonia metabolism. However, the effect of FXR activation on HE has remained largely uncharted.

METHODS

We established mouse models of HE by intraperitoneal injection of thioacetamide (TAA) and partial hepatectomy (PHx). Subsequently, we administered obeticholic acid (OCA) to activate FXR and investigated its effects on HE through comprehensive biochemical, biological, histological and behavioral analysis. Additionally, in vitro experiments were conducted to examine the impact of FXR activation on ammonia stress.

FINDINGS

In the animal model of HE, activation of FXR upregulated the expression of key enzymes involved in ammonia metabolism pathway within the liver, thereby enhancing urea cycle functionality, reducing plasma ammonia levels, and mitigating liver injury. Furthermore, FXR activation significantly improved behavioral activities in mice and mitigated inflammation in the brain. Finally, our findings demonstrated that activating FXR could enhance ammonia metabolism and ammonia tolerance of C3A cells.

INTERPRETATION

Our data provide novel evidence demonstrating that the activation of FXR by OCA exerts regulatory control over the expression of enzymes involved in ammonia metabolism, thereby effectively alleviating HE. Consequently, FXR could emerge as a promising novel target for HE treatment.

FUNDING

This study was supported by the National Natural Science Foundation of China No: 81970726 (to W-D Chen), and Henan Provincial Key Project of Medical Science and Technology Research No: SBGJ202102215 (to WL Ye).

Age-associated reduction in ER-Mitochondrial contacts impairs mitochondrial lipid metabolism and autophagosome formation in the heart

The accumulation of dysfunctional giant mitochondria is a hallmark of aged cardiomyocytes. This study investigated the core mechanism underlying this phenomenon, focusing on the disruption of mitochondrial lipid metabolism and its effects on mitochondrial dynamics and autophagy, using both naturally aging mouse models and etoposide-induced cellular senescence models. In aged cardiomyocytes, a reduction in endoplasmic reticulum-mitochondrial (ER-Mito) contacts impairs lipid transport and leads to insufficient synthesis of mitochondrial phosphatidylethanolamine (PE). A deficiency in phosphatidylserine decarboxylase (PISD) further hinders the conversion of phosphatidylserine to PE within mitochondria, exacerbating the deficit of PE production. This PE shortage disrupts autophagosomal membrane formation, leading to impaired autophagic flux and the accumulation of damaged mitochondria. Modulating LACTB expression to enhance PISD activity and PE production helps maintain mitochondrial homeostasis and the integrity of aging cardiomyocytes. These findings highlight the disruption of mitochondrial lipid metabolism as a central mechanism driving the accumulation of dysfunctional giant mitochondria in aged cardiomyocytes and suggest that inhibiting LACTB expression could serve as a potential therapeutic strategy for mitigating cardiac aging and preserving mitochondrial function.

Spatial and Single-Cell Transcriptomics Reveals the Regional Division of the Spatial Structure of MASH Fibrosis

OBJECTIVE

To elucidate the regional distribution of metabolic dysfunction-associated steatohepatitis (MASH) fibrosis within the liver and to identify potential therapeutic targets for MASH fibrosis.

METHODS

Liver sections from healthy controls, patients with simple steatosis and MASH patients were analysed using spatial transcriptomics integrated with single-cell RNA-seq.

RESULTS

Spatial transcriptomics analysis of liver tissues revealed that the fibrotic region (Cluster 9) was primarily distributed in lobules, with some fibrosis also found in the surrounding area. Integration of the single-cell-sequencing data set (GSE189175) showed a greater proportion of inflammatory cells (Kupffer cells and T cells) and myofibroblasts in MASH. Six genes, showing high- or low-specific expression in Cluster 9, namely, ADAMTSL2, PTGDS, S100A6, PPP1R1A, ASS1 and G6PC, were identified in combination with pathology. The average expression levels of ADAMTSL2, PTGDS and S100A6 on the pathological HE staining map were positively correlated with the increase in the degree of fibrosis and aligned strongly with the distribution of fibrosis. ADAMTSL2+ myofibroblasts play a role in TNF signalling pathways and in the production of ECM structural components. Pseudotime analysis indicated that in the early stages of MASH, infiltration by T cells and Kupffer cells triggers a significant inflammatory response. Subsequently, this inflammation leads to the activation of hepatic stellate cells (HSCs), transforming them into myofibroblasts and promoting the development of liver fibrosis.

CONCLUSION

This study is the first to characterise lineage-specific changes in gene expression, subpopulation composition, and pseudotime analysis in MASH fibrosis and reveals potential therapeutic targets for this condition.

Integrating metabolomics and network pharmacology analysis to explore mechanism of Pueraria lobata against pulmonary fibrosis: Involvement of arginine metabolism pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Pueraria lobata (Willd.) Ohwi is a typical medicinal and edible plant with a long application history in China and Southeast Asia. As a widely used traditional medicine, P. lobata exhibits the properties of anti-inflammatory, antipyretic, antioxidant, relieving cough and asthma. Particularly, the increasing evidence indicates that the P. lobata has the therapeutic effect on fibrotic-related diseases in terms of metabolic regulation. However, the mechanisms of P. lobata on pulmonary fibrosis (PF) has not been thoroughly explored.

AIM OF THE STUDY

This study aimed to explore the effect of arginine metabolites of P. lobata against PF model by integrating metabolomics and network pharmacology analysis. It might provide a new idea for the target finding of P. lobata anti-pulmonary fibrosis.

MATERIALS AND METHODS

In this study, the Sprague Dawley (SD) rats were randomly divided into five experimental groups: saline-treated control group, bleomycin-induced fibrosis group, prednisolone acetate group, P. lobata 3.2 g/kg group and P. lobata 6.4 g/kg group. The therapeutic effect of P. lobata on bleomycin-induced PF in rats was evaluated by clinical symptoms such as lung function, body weight, hematoxylin eosin staining (HE), Masson staining and hydroxyproline assay. Next, the plasma metabolomics analysis was carried out by LC-MS to explore the pathological differences between the group of control, PF and P. lobata-treated rats. Then, the network pharmacology study coupled with experimental validation was conducted to analysis the results of metabolic research. We constructed the "component-target-disease" network of P. lobata in the treatment of PF. In addition, the molecular docking method was used to verify the interaction between potential active ingredients and core targets of P. lobata. Finally, we tested NOS2 and L-OT in arginine-related metabolic pathway in plasma of the rats by enzyme-linked immunosorbent assay (ELISA). Real-time PCR was performed to observe the level of TNF-α mRNA and MMP9 mRNA. And we tested the expression of TNF-α and MMP9 by Western blot analysis.

RESULTS

Our findings revealed that P. lobata improved lung function and ameliorated the pathological symptoms, such as pathological damage, collagen deposition, and body weight loss in PF rats. Otherwise, the plasma metabolomics were employed to screen the differential metabolites of amino acids, lipids, flavonoids, arachidonic acid metabolites, glycoside, etc. Finally, we found that the arginine metabolism signaling mainly involved in the regulating of P. lobata on the treatment of PF rats. Furtherly, the network pharmacology predicted that the arginine metabolism pathway was contained in the top 20 pathways. Next, we integrated metabolomics and network pharmacology that identified NOS2, MMP9 and TNF-α as the P. lobata regulated hub genes by molecular docking. Importantly, it indicated a strong affinity between the puerarin and the NOS2. P. lobata attenuated TNF-α, MMP-9 and NOS2 levels, suppressed TNF-α and MMP-9 protein expression, and decreased L-OT and NOS2 content in PF rats. These results indicated that the effects of P. lobata may ameliorated PF via the arginine metabolism pathway in rats. Therefore, P. lobata may be a potential therapeutic agent to ameliorated PF.

CONCLUSION

In this work, we used metabolomics and network pharmacology to explore the mechanisms of P. lobata in the treatment of PF. Finally, we confirmed that P. lobata alleviated BLM-induced PF in rats by regulating arginine metabolism pathway based on reducing the L-OT and NOS2-related signal molecular. The search for the biomarkers finding of arginine metabolism pathway revealed a new strategy for P. lobata in the treatment of PF.

Proteomics and metabolomics analyses of urine for investigation of gallstone disease in a high-altitude area

BACKGROUND

The incidence of gallstones is high in Qinghai Province. However, the molecular mechanisms underlying the development of gallstones remain unclear.

METHODS

In this study, we collected urine samples from 30 patients with gallstones and 30 healthy controls. The urine samples were analysed using multi-omics platforms. Proteomics analysis was conducted using data-independent acquisition, whereas metabolomics analysis was performed using liquid chromatography-mass spectrometry (LC-MS).

RESULTS

Among the patients with gallstones, we identified 49 down-regulated and 185 up-regulated differentially expressed proteins as well as 195 up-regulated and 189 down-regulated differentially expressed metabolites. Six pathways were significantly enriched: glycosaminoglycan degradation, arginine and proline metabolism, histidine metabolism, pantothenate and coenzyme A biosynthesis, drug metabolism-other enzymes, and the pentose phosphate pathway. Notably, 10 differentially expressed proteins and metabolites showed excellent predictive performance and were selected as potential biomarkers.

CONCLUSION

The findings of our metabolomics and proteomics analyses provide new insights into novel biomarkers for patients with cholelithiasis in high-altitude areas.

PGC-1α loss promotes mitochondrial protein lactylation in acetaminophen-induced liver injury via the LDHB-lactate axis

Coronavirus disease 2019 (COVID-19) affected people worldwide, and fever is one of the major symptoms of this disease. Although Acetaminophen (APAP) is a common fever-reducing medication, it can also mediate liver injury. However, the role of PGC-1α in regulating mitochondrial quality control by lactate dehydrogenase B (LDHB), a vital enzyme catalyzing the conversion of lactate to pyruvate, in APAP-induced hepatotoxicity, is unclear. Here, gene expression omnibus data of patients with APAP-induced liver injury were used to explore gene expression profiles. AML12 cells and C57/BL6 mice were used to establish models of APAP-induced acute liver injury. SIRT1 and PGC-1α were overexpressed in vitro via lentiviral transfection to establish stable cell lines. The results showed that APAP treatment decreased SIRT1/PGC-1α/LDHB expression and increased protein lactylation, mitochondrial lactate levels, and pathological damage in liver mitochondria. PGC-1α upregulation or activation ameliorated APAP-induced damage in the cells and liver. Furthermore, PGC-1α overexpression increased LDHB synthesis, reduced lactylation, and induced a switch from lactate to pyruvate production. These results suggest that PGC-1α and LDHB play a role in APAP-induced liver injury by regulating mitochondrial quality control and lactate metabolic reprogramming. Therefore, the PGC-1α/LDHB axis is a potential therapeutic target for APAP-induced liver injury.

Angelicin: A leading culprit involved in fructus Psoraleae liver injury via inhibition of VKORC1

ETHNOPHARMACOLOGICAL RELEVANCE

The adverse effects of Fructus Psoraleae (FP), especially liver injury, have attracted wide attention in recent years.

AIM OF THE STUDY

To establish a system to explore potential hepatotoxic targets and the chief culprit of liver injury based on clinical experience, network pharmacological method, molecular docking, and in vitro and in vivo experiments.

MATERIALS AND METHODS

Clinical applications and adverse reactions to FP were obtained from public literatures. Components absorbed in the blood were selected as candidates to search for potential active targets (PATs) of FP. Subsequently, potential pharmacological core targets (PPCTs) were screened through the "drug targets-disease targets" network. Non-drug active targets (NPATs) were obtained by subtracting the PPCTs from the PATs. The potential hepatotoxic targets (PHTs) of FP were the intersection targets obtained from Venn analysis using NPATs, hepatotoxic targets, and adverse drug reaction (ADR) targets provided by the databases. Then, potential hepatotoxic components and targets were obtained using the "NPATS-component" network relationship. Molecular docking and in vitro and in vivo hepatotoxicity experiments were performed to verify the targets and related components.

RESULTS

Overall, 234 NPATs were acquired from our analysis, and 6 targets were identified as PHTs. Results from molecular docking and in vitro and in vivo experiments showed that angelicin is the leading cause of liver injury in FP, and VKORC1 plays an important role.

CONCLUSION

The results indicate that six targets, especially VKORC1, are associated with the PHTs of FP, and angelicin is the leading culprit involved in FP liver injury via inhibition of VKORC1.

P2Y2 purinergic receptor gene deletion protects mice from bacterial endotoxin and sepsis-associated liver injury and mortality

The liver plays a significant role in regulating a wide range of metabolic, homeostatic, and host-defense functions. However, the impact of liver injury on the host's ability to control bacteremia and morbidity in sepsis is not well understood. Leukocyte recruitment and activation lead to cytokine and chemokine release, which, in turn, trigger hepatocellular injury and elevate nucleotide levels in the extracellular milieu. P2Y2 purinergic receptors, G protein-coupled and activated by extracellular ATP/UTP, are expressed at the cell surface of hepatocytes and nonparenchymal cells. We sought to determine whether P2Y2 purinergic receptor function is necessary for the maladaptive host response to bacterial infection and endotoxin-mediated inflammatory liver injury and mortality in mice. We report that P2Y2 purinergic receptor knockout mice (P2Y2-/-) had attenuated inflammation and liver injury, with improved survival in response to LPS/galactosamine (LPS/GalN; inflammatory liver injury) and cecal ligation and puncture (CLP; polymicrobial sepsis). P2Y2-/- livers had attenuated c-Jun NH2-terminal kinase activation, matrix metallopeptidase-9 expression, and hepatocyte apoptosis in response to LPS/GalN and attenuated inducible nitric oxide synthase and nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain containing 3 protein expression in response to CLP. Implicating liver injury in the disruption of amino acid homeostasis, CLP led to lower serum arginine and higher bacterial load and morbidity in the WT mice, whereas serum arginine levels were comparable to sham-operated controls in P2Y2-/- mice, which had attenuated bacteremia and improved survival. Collectively, our studies highlight the pathophysiological relevance of P2Y2 purinergic receptor function in inflammatory liver injury and dysregulation of systemic amino acid homeostasis with implications for sepsis-associated immune dysfunction and morbidity in mice.NEW & NOTEWORTHY Our studies provide experimental evidence for P2Y2 purinergic receptor-mediated potentiation of inflammatory liver injury, morbidity, and mortality, in two well-established animal models of inflammatory liver injury. Our findings highlight the potential to target P2Y2 purinergic signaling to attenuate the induction of "cytokine storm" and prevent its deleterious consequences on liver function, systemic amino acid homeostasis, host response to bacterial infection, and sepsis-associated morbidity and mortality.

Single-cell RNA sequencing reveals the effects of capsaicin in the treatment of sepsis-induced liver injury

Sepsis is a difficult-to-treat systemic condition in which liver dysfunction acts as both regulator and target. However, the dynamic response of diverse intrahepatic cells to sepsis remains poorly characterized. Capsaicin (CAP), a multifunctional chemical derived from chilli peppers, has recently been shown to potentially possess anti-inflammatory effects, which is also one of the main approaches for drug discovery against sepsis. We performed single-cell RNA transcriptome sequencing on 86,830 intrahepatic cells isolated from normal mice, cecal ligation and puncture-induced sepsis model mice and CAP-treated mice. The transcriptional atlas of these cells revealed dynamic changes in hepatocytes, macrophages, neutrophils, and endothelial cells in response to sepsis. Among the extensive crosstalk across these major subtypes, KC_Cxcl10 shared strong potential interaction with other cells when responding to sepsis. CAP mitigated the severity of inflammation by partly reversing these pathophysiologic processes. Specific cell subpopulations in the liver act collectively to escalate inflammation, ultimately causing liver dysfunction. CAP displays its health-promoting function by ameliorating liver dysfunction induced by sepsis. Our study provides valuable insights into the pathophysiology of sepsis and suggestions for future therapeutic gain.

RNA-Sequencing Characterization of lncRNA and mRNA Functions in Septic Pig Liver Injury

We assessed differentially expressed (DE) mRNAs and lncRNAs in the liver of septic pigs to explore the key factors regulating lipopolysaccharide (LPS)-induced liver injury. We identified 543 DE lncRNAs and 3642 DE mRNAs responsive to LPS. Functional enrichment analysis revealed the DE mRNAs were involved in liver metabolism and other pathways related to inflammation and apoptosis. We also found significantly upregulated endoplasmic reticulum stress (ERS)-associated genes, including the receptor protein kinase receptor-like endoplasmic reticulum kinase (PERK), the eukaryotic translation initiation factor 2α (EIF2S1), the transcription factor C/EBP homologous protein (CHOP), and activating transcription factor 4 (ATF4). In addition, we predicted 247 differentially expressed target genes (DETG) of DE lncRNAs. The analysis of protein-protein interactions (PPI) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway detected key DETGs that are involved in metabolic pathways, such as N-Acetylgalactosaminyltransferase 2 (GALNT2), argininosuccinate synthetase 1 (ASS1), and fructose 1,6-bisphosphatase 1 (FBP1). LNC_003307 was the most abundant DE lncRNA in the pig liver, with a marked upregulation of >10-fold after LPS stimulation. We identified three transcripts for this gene using the rapid amplification of the cDNA ends (RACE) technique and obtained the shortest transcript sequence. This gene likely derives from the nicotinamide N-methyltransferase (NNMT) gene in pigs. According to the identified DETGs of LNC_003307, we hypothesize that this gene regulates inflammation and endoplasmic reticulum stress in LPS-induced liver damage in pigs. This study provides a transcriptomic reference for further understanding of the regulatory mechanisms underlying septic hepatic injury.