circGRAMD1B contributes to migration, invasion and epithelial-mesenchymal transition of lung adenocarcinoma cells via modulating the expression of SOX4.

Lung adenocarcinoma (LUAD) represents the subtype of non-small-cell lung cancer (NSCLC), with the high morbidity over the world. Mounting studies have highlighted the important roles of circular RNAs (circRNA) in cancers, including LUAD. This study mainly focused on revealing the role of circGRAMD1B and its relevant regulatory mechanism in LUAD cells. RT-qPCR and Western blot were conducted to detect the expression of target genes. Function assays were performed to determine the effect of related genes on migration, invasion, and epithelial-mesenchymal transition (EMT) of LUAD cells. Mechanism analyses were conducted to figure out the specific mechanism with regard to circGRAMD1B and its downstream molecules as well. Based on the experimental results, circGRAMD1B was upregulated in LUAD cells and promoted the migration, invasion, and EMT of LUAD cells. Mechanically, circGRAMD1B sponged miR-4428 to upregulate the expression of SOX4. In addition, SOX4 activated the expression of MEX3A at the transcriptional level, thereby modulating PI3K/AKT pathway to facilitate LUAD cell malignant behaviors. In conclusion, circGRAMD1B is discovered to modulate miR-4428/SOX4/MEX3A axis to further activate PI3K/AKT pathway, finally boosting migration, invasion, and EMT of LUAD cells.

An Improved New YOLOv7 Algorithm for Detecting Building Air Conditioner External Units from Street View Images.

Street view images are emerging as new street-level sources of urban environmental information. Accurate detection and quantification of urban air conditioners is crucial for evaluating the resilience of urban residential areas to heat wave disasters and formulating effective disaster prevention policies. Utilizing street view image data to predict the spatial coverage of urban air conditioners offers a simple and effective solution. However, detecting and accurately counting air conditioners in complex street-view environments remains challenging. This study introduced 3D parameter-free attention and coordinate attention modules into the target detection process to enhance the extraction of detailed features of air conditioner external units. It also integrated a small target detection layer to address the challenge of detecting small target objects that are easily missed. As a result, an improved algorithm named SC4-YOLOv7 was developed for detecting and recognizing air conditioner external units in street view images. To validate this new algorithm, we extracted air conditioner external units from street view images of residential buildings in Guilin City, Guangxi Zhuang Autonomous Region, China. The results of the study demonstrated that SC4-YOLOv7 significantly improved the average accuracy of recognizing air conditioner external units in street view images from 87.93% to 91.21% compared to the original YOLOv7 method while maintaining a high speed of image recognition detection. The algorithm has the potential to be extended to various applications requiring small target detection, enabling reliable detection and recognition in real street environments.

NIR/MRI-Guided Oxygen-Independent Carrier-Free Anti-Tumor Nano-Theranostics.

Imaging-guided photothermal therapy (PTT)/photodynamic therapy (PDT) for cancer treatment are beneficial for precise localization of the malignant lesions and combination of multiple cell killing mechanisms in eradicating stubborn thermal-resistant cancer cells. However, overcoming the adverse impact of tumor hypoxia on PDT efficacy remains a challenge. Here, carrier-free nano-theranostic agents are developed (AIBME@IR780-APM NPs) for magnetic resonance imaging (MRI)-guided synergistic PTT/thermodynamic therapy (TDT). Two IR780 derivatives are synthesized as the subject of nanomedicine to confer the advantages for the nanomedicine, which are by feat of amphiphilic IR780-PEG to enhance the sterical stability and reduce the risk from reticuloendothelial system uptake, and IR780-ATU to chelate Mn2+ for T1 -weighted MRI. Dimethyl 2,2'-azobis(2-methylpropionate) (AIBME), acting as thermally decomposable radical initiators, are further introduced into nanosystems with the purpose of generating highly cytotoxic alkyl radicals upon PTT launched by IR780 under 808 nm laser irradiation. Therefore, the sequentially generated heat and alkyl radicals synergistically induce cell death via synergistic PTT/TDT, ignoring tumor hypoxia. Moreover, these carrier-free nano-theranostic agents present satisfactory biocompatibility, which could be employed as a powerful weapon to hit hypoxic tumors via MRI-guided oxygen-independent PTT and photonic TDT.

ß-Aminoisobutyric acid supplementation attenuated salt-sensitive hypertension in Dahl salt-sensitive rats through prevention of insufficient fumarase.

The human Dietary Approaches to Stop Hypertension-Sodium Trial has shown that ß-aminoisobutyric acid (BAIBA) may prevent the development of salt-sensitive hypertension (SSHT). However, the specific antihypertensive mechanism remains unclear in the renal tissues of salt-sensitive (SS) rats. In this study, BAIBA (100 mg/kg/day) significantly attenuated SSHT via increased nitric oxide (NO) content in the renal medulla, and it induced a significant increase in NO synthesis substrates (L-arginine and malic acid) in the renal medulla. BAIBA enhanced the activity levels of total NO synthase (NOS), inducible NOS, and constitutive NOS. BAIBA resulted in increased fumarase activity and decreased fumaric acid content in the renal medulla. The high-salt diet (HSD) decreased fumarase expression in the renal cortex, and BAIBA increased fumarase expression in the renal medulla and renal cortex. Furthermore, in the renal medulla, BAIBA increased the levels of ATP, ADP, AMP, and ADP/ATP ratio, thus further activating AMPK phosphorylation. BAIBA prevented the decrease in renal medullary antioxidative defenses induced by the HSD. In conclusion, BAIBA's antihypertensive effect was underlined by the phosphorylation of AMPK, the prevention of fumarase's activity reduction caused by the HSD, and the enhancement of NO content, which in concert attenuated SSHT in SS rats.

Effects of almonds on ameliorating salt-induced hypertension in dahl salt-sensitive rats.

BACKGROUND: Excessive dietary salt intake is related to an increased risk of hypertension. Dietary functional foods probably could help to improve salt-induced hypertension. In this study, Dahl salt-sensitive (DSS) rats were used to investigate their metabolic differences from those of salt-resistant SS.13BN rats and determine whether dietary protein-rich almonds could ameliorate salt-induced elevation of blood pressure in DSS rats. RESULTS: After high-salt intake, the systolic blood pressure and mean arterial pressure of the DSS rats increased dramatically. Metabolomics analysis indicated abnormal amino acid metabolism in their kidneys. Their renal nitric oxide (NO) content and nitric oxide synthase activity decreased significantly after high-salt diet. Oxidative stress also occurred in DSS rats. After the DSS rats received almond supplementation, the levels of various amino acids in their kidney increased, and renal arginine and NO contents were upregulated. Their renal hydrogen peroxide and malonaldehyde levels decreased, whereas renal catalase, superoxide dismutase and glutathione peroxidase activities and glutathione levels increased. CONCLUSION: The renal abnormal amino acid metabolism of DSS rats contributed to the impaired NO production in response to high-salt intake. Together with salt-induced oxidative stress, high-salt diet intake ultimately led to an increase in the blood pressure of DSS rats. Protein-rich almond supplementation might prevent the development of salt-induced hypertension by restoring arginine and NO regeneration and alleviating salt-induced oxidative stress. © 2021 Society of Chemical Industry.

[The renal metabolic mechanism of salt sensitive hypertension in Dahl-SS rats].

The kidney is one of the main target organs involved in hypertension, and it regulates water and salt metabolism, blood volume and vascular resistance. High salt intake induces salt and water retention, persistent endothelial dysfunction and elevation of blood pressure in salt sensitive individuals. Dahl salt sensitive (Dahl-SS) rats, as a classic animal model for salt sensitive hypertension, have many similar stably inherited physiological characteristics to human with salt sensitive hypertension, such as salt sensitivity, hyperlipidemia, insulin resistance, renal failure, increased urinary protein secretion and low plasma renin activity. Based on renal physiology and biochemistry researches and multi-omics analyses in Dahl-SS rats, this review will summarize the relationship between salt sensitive hypertension and renal redox, NO, amino acids, glucose and lipid metabolism.

Momordica charantia Extract Confers Protection Against Hypertension in Dahl Salt-Sensitive Rats.

Hypertension is one of the main factors of cardiovascular disease worldwide and is strongly related to the overall mortality. High salt intake is a major risk factors for hypertension. Identifying functional foods that can help prevent mechanistic abnormalities mediating salt-induced hypertension is an issue of considerable nutraceutical and scientific interest. Dietary Momordica charantia may be an alternative approach to avoid salt-induced hypertension. Dahl salt-sensitive (DSS) rats were used to determine whether Momordica charantia water extracts (ME) exerts anti-hypertensive effects in the present study. ME gavage could significantly prevented the increase of blood pressure, blood urea nitrogen, creatinine, and urine protein-to-creatinine ratio of DSS rats. Metabolomics analysis indicated that high-salt diet induced abnormal amino acid metabolism was related to nitric oxide (NO) deficiency, but ME gavage could upregulate the activities of nitric oxide synthase, aspartate aminotransferase, argininosuccinate lyase, argininosuccinate synthase and restore endogenous synthesis of arginine and NO. Meanwhile, renal function was improved after ME gavage. Citrulline, as one of the important component in ME, could attenuate salt-induced hypertension by increasing endogenous synthesis of arginine and NO. Antioxidants in ME, such as phenolic compound, may avoid high-salt induced oxidative stress in DSS rats, which may be another mechanism by which ME prevented blood pressure increase. Thus, the present study indicated that feeding Momordica charantia could avoid high-salt-induced hypertension in DSS rats.

Reconstruction and analysis of correlation networks based on GC-MS metabolomics data for hypercholesterolemia.

BACKGROUND AND AIMS: Hypercholesterolemia is characterized by the elevation of plasma total cholesterol level, especially low-density lipoprotein (LDL) cholesterol. This disease is usually caused by a mutation in genes such as LDL receptor, apolipoprotein B, or proprotein convertase subtilisin/kexin type 9. However, a considerable number of patients with hypercholesterolemia do not have any mutation in these candidate genes. In this study, we examined the difference in the metabolic level between patients with hypercholesterolemia and healthy subjects, and screened the potential biomarkers for this disease. METHODS: Analysis of plasma metabolomics in hypercholesterolemia patients and healthy controls was performed by gas chromatography-mass spectrometry and metabolic correlation networks were constructed using Gephi-0.9.2. RESULTS: First, metabolic profile analysis confirmed the distinct metabolic footprints between the patients and the healthy ones. The potential biomarkers screened by orthogonal partial least-squares discrimination analysis included l-lactic acid, cholesterol, phosphoric acid, d-glucose, urea, and d-allose (Variable importance in the projection > 1). Second, arginine and methionine metabolism were significantly perturbed in hypercholesterolemia patients. Finally, we identified that l-lactic acid, l-lysine, l-glutamine, and l-cysteine had high scores of centrality parameters in the metabolic correlation network. CONCLUSION: Plasma l-lactic acid could be used as a sensitive biomarker for hypercholesterolemia. In addition, arginine biosynthesis and cysteine and methionine metabolism were profoundly altered in patients with hypercholesterolemia.

Revealing metabolic pathways relevant to prediabetes based on metabolomics profiling analysis.

AIMS: Dahl salt-sensitive (SS) rats develop similar prediabetes lesion characteristics, such as impaired glucose tolerance (IGT), when compared with the salt resistant rat. In this study, we evaluate the risk of high glucose intake during prediabetes and reveal the metabolic pathways relevant to the pathophysiology of prediabetes to diabetes using the SS rat model and compared this with the salt-resistant consomic SS.13BN rat model. METHODS: SS rats were fed with normal chow ±10% glucose solution ad libitum for five weeks. The same experimental treatment was performed on the SS.13BN rats. Metabolites derived from the serum and liver tissue were measured through biochemical and metabolomics analyses. Multivariate, pathway enrichment, and metabolic correlation network analyses were performed based on the metabolomics data. RESULTS: Biochemical analysis revealed that serum triglyceride (TG) significantly increased with a significant decrease in serum total cholesterol (TC) after high glucose intake in the SS rat. Metabolic pathway analysis revealed that high glucose intake interfered with galactose, glyoxylate, and dicarboxylate metabolism, most evidently in the SS rat. Hepatic l-lactic acid content increased in the SS rat after high glucose intake, whereas the opposite was observed in SS.13BN rats. Metabolic correlation network analysis based on serum metabolites revealed that urea and l-valine had higher metabolic centrality in the SS rat. CONCLUSION: Our findings revealed that high glucose intake can significantly stimulate hypertriglyceridemia and reduce serum TC level. The profoundly altered metabolic pathway included galactose, glyoxylate, and dicarboxylate metabolism. l-lactic acid was screened as a biomarker in liver, whereas l-valine and urea were screened as hub metabolites in serum.

Metabolomics and correlation network analyses of core biomarkers in type 2 diabetes.

The identification of metabolic pathways and the core metabolites provide novel molecular targets for the prevention and treatment of diseases. Diabetes is often accompanied with multiple metabolic disorders including hyperglycemia and dyslipidemia. Analysis of the variances of plasma metabolites is critical for identifying potential therapeutic targets for diabetes. In the current study, non-diabetic subjects with normal glucose tolerance and diabetics (age 40-60 years; n = 42 per group) were selected and plasma samples were analyzed by GC-MS for various metabolites profiling followed by network analysis. Our study identified 24 differential metabolites that were mainly enriched in protein synthesis, lipid and amino acid metabolism. Furthermore, we applied the correlation network analysis on these differential metabolites in fatty acid and amino acid metabolism and identified glycerol, alanine and serine as the hub metabolites in diabetic group. In addition, we measured the activities of enzymes in gluconeogenesis and amino acid metabolism and found significant higher activities of fructose 1,6-bisphosphatase, pyruvate carboxylase, lactate dehydrogenase, aspartate aminotransferase and alanine aminotransferase in diabetic patients. In contrast, the enzyme activities of glycolysis pathway (e.g., hexokinase, phosphofructokinase and pyruvate kinase) and TCA cycle (e.g., isocitrate dehydrogenase, succinate dehydrogenase, fumarate hydratase and malate dehydrogenase) were reduced in diabetes. Together, our studies showed that the linoleic acid and amino acid metabolism were the most affected metabolic pathways and glycerol, alanine and serine could play critical role in diabetes. The integration of network analysis and metabolic data could provide novel molecular targets or biomarkers for diabetes.

High-salt diet affects amino acid metabolism in plasma and muscle of Dahl salt-sensitive rats.

Genetic background and high-salt diet are considered key factors contributing to the development of hypertension and its associated metabolic disorders. Metabolomics is an emerging powerful tool to analyze the low-molecular weight metabolites in plasma and tissue. This study integrated metabolomics and correlation network analysis to investigate the metabolic profiles of plasma and muscle of Dahl salt-sensitive (SS) rats and SS.13BN rats (control) under normal and high-salt diet. The hub metabolites, which could play important roles in the metabolic changes, were identified by correlation network analysis. The results of the network analysis were further confirmed by pathway analysis and enzyme activity analysis. The results indicated a higher amino acid levels in both plasma and muscle of SS rats fed with high-salt diet. Alanine was found as a hub metabolite with the highest score of three centrality indices and also as the significant differential metabolite in plasma of SS rats after high-salt diet. Valine and lysine were found as hub metabolites and differential metabolites in muscle of SS rats after high-salt diet. Amino acid levels increased in both plasma and muscle of SS rats fed with a high salt diet. Moreover, alanine in plasma and valine and lysine in muscle as hub metabolites could play important roles in the response to high-salt diet.

Cargo-Free Nanomedicine with pH Sensitivity for Codelivery of DOX Conjugated Prodrug with SN38 To Synergistically Eradicate Breast Cancer Stem Cells.

As a result of their ability to transform into bulk cancer cells and their resistance to radiotherapy and chemotherapy, cancer stem cells (CSCs) are currently considered as a major obstacle for cancer treatment. Application of multiple drugs using nanocarriers is a promising approach to simultaneously eliminate noncancer stem cells (non-CSCs) and CSCs. Herein, to employ the advantages of nanomedicine while avoiding new excipients, pH-responsive prodrug (PEG-CH═N-DOX) was employed as the surfactant to fabricate cargo-free nanomedicine for codelivery of DOX conjugated prodrug with SN38 to synergistically eradicate breast cancer stem cells (bCSCs) and non-bCSCs. Through the intermolecular interaction between DOX and SN38, PEG-CH═N-DOX and SN38 were assembled together to form a stable nanomedicine. This nanomedicine not only dramatically enhanced drug accumulation efficiency at the tumor site but also effectively eliminated bCSCs and non-bCSCs, which resulted in achieving a superior in vivo tumor inhibition activity. Additionally, the biosafety of this nanomedicine was systematically studied through immunohistochemistry, blood biochemistry assay, blood routine examination, and metabolomics. The results revealed that this nanomedicine significantly reduced the adverse effects of DOX and SN38. Therefore, this simple yet efficient nanomedicine provided a promising strategy for future clinical applications.

Combined metabolomic and correlation networks analyses reveal fumarase insufficiency altered amino acid metabolism.

Fumarase catalyzes the interconversion of fumarate and l-malate in the tricarboxylic acid cycle. Fumarase insufficiencies were associated with increased levels of fumarate, decreased levels of malate and exacerbated salt-induced hypertension. To gain insights into the metabolism profiles induced by fumarase insufficiency and identify key regulatory metabolites, we applied a GC-MS based metabolomics platform coupled with a network approach to analyze fumarase insufficient human umbilical vein endothelial cells (HUVEC) and negative controls. A total of 24 altered metabolites involved in seven metabolic pathways were identified as significantly altered, and enriched for the biological module of amino acids metabolism. In addition, Pearson correlation network analysis revealed that fumaric acid, l-malic acid, l-aspartic acid, glycine and l-glutamic acid were hub metabolites according to Pagerank based on their three centrality indices. Alanine aminotransferase and glutamate dehydrogenase activities increased significantly in fumarase deficiency HUVEC. These results confirmed that fumarase insufficiency altered amino acid metabolism. The combination of metabolomics and network methods would provide another perspective on expounding the molecular mechanism at metabolomics level.

Multifunctional Cargo-Free Nanomedicine for Cancer Therapy.

Nanocarriers encapsulating multiple chemotherapeutics are a promising strategy to achieve combinational chemotherapy for cancer therapy; however, they generally use exotic new carriers without therapeutic effect, which usually suffer from carrier-related toxicity issues, as well as having to pass extensive clinical trials to be drug excipients before any clinical applications. Cargo-free nanomedicines, which are fabricated by drugs themselves without new excipients and possess nanoscale characteristics to realize favorable pharmacokinetics and intracellular delivery, have been rapidly developed and drawn much attention to cancer treatment. Herein, we discuss recent advances of cargo-free nanomedicines for cancer treatment. After a brief introduction to the major types of carrier-free nanomedicine, some representative applications of these cargo-free nanomedicines are discussed, including combination therapy, immunotherapy, as well as self-monitoring of drug release. More importantly, this review draws a brief conclusion and discusses the future challenges of cargo-free nanomedicines from our perspective.

Nanotechnology for Cancer Therapy Based on Chemotherapy.

Chemotherapy has been widely applied in clinics. However, the therapeutic potential of chemotherapy against cancer is seriously dissatisfactory due to the nonspecific drug distribution, multidrug resistance (MDR) and the heterogeneity of cancer. Therefore, combinational therapy based on chemotherapy mediated by nanotechnology, has been the trend in clinical research at present, which can result in a remarkably increased therapeutic efficiency with few side effects to normal tissues. Moreover, to achieve the accurate pre-diagnosis and real-time monitoring for tumor, the research of nano-theranostics, which integrates diagnosis with treatment process, is a promising field in cancer treatment. In this review, the recent studies on combinational therapy based on chemotherapy will be systematically discussed. Furthermore, as a current trend in cancer treatment, advance in theranostic nanoparticles based on chemotherapy will be exemplified briefly. Finally, the present challenges and improvement tips will be presented in combination therapy and nano-theranostics.

Elevation of fumarase attenuates hypertension and can result from a nonsynonymous sequence variation or increased expression depending on rat strain.

The activity of fumarase, an enzyme in the tricarboxylic acid cycle, is lower in Dahl salt-sensitive SS rats compared with SS.13BN rats. SS.13BN rats have a Brown Norway (BN) allele of fumarase and exhibit attenuated hypertension. The SS allele of fumarase differs from the BN allele by a K481E sequence variation. It remains unknown whether higher fumarase activities can attenuate hypertension and whether the mechanism is relevant without the K481E variation. We developed SS-TgFh1 transgenic rats overexpressing fumarase on the background of the SS rat. Hypertension was attenuated in SS-TgFh1 rats. Mean arterial pressure in SS-TgFh1 rats was 20 mmHg lower than transgene-negative SS littermates after 12 days on a 4% NaCl diet. Fumarase overexpression decreased H2O2, while fumarase knockdown increased H2O2 Ectopically expressed BN form of fumarase had higher specific activity than the SS form. However, sequencing of more than a dozen rat strains indicated most rat strains including salt-insensitive Sprague-Dawley (SD) rats had the SS allele of fumarase. Despite that, total fumarase enzyme activity in the renal medulla was still higher in SD rats than in SS rats, which was associated with higher expression of fumarase in SD. H2O2 can suppress the expression of fumarase. Renal medullary interstitial administration of fumarase siRNA in SD rats resulted in higher blood pressure on the high-salt diet. These findings indicate elevation of total fumarase activity attenuates the development of hypertension and can result from a nonsynonymous sequence variation in some rat strains and higher expression in other rat strains.

Mitochondrial Dysfunction and Altered Renal Metabolism in Dahl Salt-Sensitive Rats.

BACKGROUND/AIMS: The kidney plays a critical role in the control of blood pressure and its elevation in salt-induced hypertension. Mitochondrial dysfunction, especially in energy metabolism, has been associated with hypertension. Here, we aimed to investigate mitochondrial function and metabolic features in renal mitochondria of Dahl salt-sensitive (SS) rats to gain further insight into the relationship between mitochondrial metabolism and predisposition to hypertension. METHODS: In this study, SS rats fed low-salt (LS) or high-salt (HS) diets were used to investigate mitochondrial function and metabolism including mitochondrial enzyme activities, pyridine nucleotides, metabolites, and oxidative stress by biochemical analysis and gas chromatography-mass spectrometer (GC-MS). RESULTS: Significantly lower activity levels of fumarase, isocitrate dehydrogenase and succinyl-CoA synthetase were observed in renal mitochondria of SS rats compared with SS.13BN control rats fed LS diets. Intra-mitochondrial pyridine nucleotide content and mitochondrial metabolism were adversely affected in SS rats. In accordance with this, reduced ATP production, Δψm, and superoxide dismutase (SOD) activity were also observed in mitochondria of the renal medulla and cortex of SS rats. Moreover, ATP production was further impaired and oxidative stress was increased, confirming that the mitochondria of SS rats fed HS diets were dysfunctional compared to those of rats fed LS diets. CONCLUSIONS: Our data demonstrated that the renal mitochondria of SS rats exhibited complicated metabolic alteration and dysfunction in low-salt diets, and high-salt diets aggravated these dysfunctions. Thus, these results may be associated with renal dysfunction, which, in turn, would help in understanding the development of salt-sensitive hypertension.

Ultrastructure of mitochondria and the endoplasmic reticulum in renal tubules of Dahl salt-sensitive rats.

Metabolic and functional abnormalities in the kidney precede or coincide with the initiation of overt hypertension in the Dahl salt-sensitive (SS) rat. However, renal histological injury in SS rats is mild before the development of overt hypertension. We performed electron microscopy analysis in 7-wk-old SS rats and salt-insensitive consomic SS.13(BN) rats and Sprague-Dawley (SD) rats fed a 4% NaCl diet for 7 days. Long mitochondria (>2 µm) accounted for a significantly smaller fraction of mitochondria in medullary thick ascending limbs in SS rats (4% ± 1%) than in SS.13(BN) rats (8% ± 1%, P < 0.05 vs. SS rats) and SD rats (9% ± 1%, P < 0.01 vs. SS rats), consistent with previous findings of mitochondrial functional insufficiency in the medulla of SS rats. Long mitochondria in proximal tubules, however, were more abundant in SS rats than in SS.13(BN) and SD rats. The width of the endoplasmic reticulum, an index of endoplasmic reticulum stress, was significantly greater in medullary thick ascending limbs of SS rats (107 ± 1 nm) than in SS.13(BN) rats (95 ± 2 nm, P < 0.001 vs. SS rats) and SD rats (74 ± 3 nm, P < 0.01 vs. SS or SS.13(BN) rats). The tubules examined were indistinguishable between rat strains under light microscopy. These data indicate that ultrastructural abnormalities occur in the medullary thick ascending limbs of SS rats before the development of histological injury in renal tubules, providing a potential structural basis contributing to the subsequent development of overt hypertension.

Analysis of metabolites in plasma reveals distinct metabolic features between Dahl salt-sensitive rats and consomic SS.13(BN) rats.

Salt-sensitive hypertension is a major risk factor for cardiovascular disorders. Our previous proteomic study revealed substantial differences in several proteins between Dahl salt-sensitive (SS) rats and salt-insensitive consomic SS.13(BN) rats. Subsequent experiments indicated a role of fumarase insufficiency in the development of hypertension in SS rats. In the present study, a global metabolic profiling study was performed using gas chromatography/mass spectrometry (GC/MS) in plasma of SS rats (n=9) and SS.13(BN) rats (n=8) on 0.4% NaCl diet, designed to gain further insights into the relationship between alterations in cellular intermediary metabolism and predisposition to hypertension. Principal component analysis of the data sets revealed a clear clustering and separation of metabolic profiles between SS rats and SS.13(BN) rats. 23 differential metabolites were identified (P<0.05). Higher levels of five TCA cycle metabolites, fumarate, cis-aconitate, isocitrate, citrate and succinate, were observed in SS rats. Pyruvate, which connects TCA cycle and glycolysis, was also increased in SS rats. Moreover, lower activity levels of fumarase, aconitase, α-ketoglutarate dehydrogenase and succinyl-CoA synthetase were detected in the heart, liver or skeletal muscles of SS rats. The distinct metabolic features in SS and SS.13(BN) rats indicate abnormalities of TCA cycle in SS rats, which may play a role in predisposing SS rats to developing salt-sensitive hypertension.

High-salt diet induces dyslipidemia through the SREBP2/PCSK9 pathway in dahl salt-sensitive rats.

A high-salt diet is known to increase serum cholesterol levels; however, the underlying mechanism of salt-induced dyslipidemia in patients with salt-sensitivity remains poorly understood. We aimed to investigate whether high-salt diet (HSD) can induce dyslipidemia and elucidate the underlying mechanism of salt-induced dyslipidemia in Dahl salt-sensitive (SS) rats. Metabolomic and biochemical analyses revealed that the consumption of an HSD (8 % NaCl) significantly increased the serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) in SS rats. The enzyme-linked immunosorbent assay demonstrated an increase in circulating proprotein convertase subtilisin/kexin type 9 (PCSK9) levels, accompanied by a decrease in hepatic low-density lipoprotein receptor (LDLR) levels due to HSD consumption. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis revealed that HSD consumption activated sterol regulatory element-binding protein-2 (SREBP2) expression in the liver and kidney, resulting in upregulation of PCSK9 at the transcriptional level in the liver and at the translational level in the kidney, ultimately increasing circulating PCSK9 levels. The combined effects of HSD on the liver and kidney contributed to the development of hypercholesterolemia. Furthermore, an in vitro assay confirmed that high-salt exposure led to an increase in the protein expression of SREBP2 and PCSK9 secretion, thereby reducing low-density lipoprotein (LDL) uptake. This study, for the first time, shows that an HSD induces dyslipidemia through activation of the SREBP2/PCSK9 pathway, providing new insights into the prevention and treatment of dyslipidemia in patients with salt sensitivity.