Metabolomics Analysis of the Renal Cortex in Rats With Acute Kidney Injury Induced by Sepsis

Chronic exposure to tris(1,3-dichloro-2-propyl) phosphate: Effects on intestinal microbiota and serum metabolism in rats

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a widely used organophosphate ester that can adversely affect animal or human health. The intestinal microbiota is critical to human health. High-dose exposure to TDCIPP can markedly affect the intestinal ecosystem of mice, but the effects of long-term exposure to lower concentrations of TDCIPP on the intestinal flora and body metabolism remain unclear. In this study, TDCIPP was administered to Sprague-Dawley rats by gavage at a dose of 13.3 mg/kg bw/day for 90 days. TDCIPP increased the relative weight of the kidneys (P = 0.017), but had no effect on the relative weight of the heart, liver, spleen, lungs, testes, and ovaries (P > 0.05). 16 S rRNA gene sequencing revealed that long-term TDCIPP exposure affected the diversity, relative abundance, and functions of rat gut microbes. The serum metabolomics of the rats showed that TDCIPP can disrupt the serum metabolic profiles, result in the up-regulation of 26 metabolites and down-regulation of 3 metabolites, and affect multiple metabolic pathways in rat sera. In addition, the disturbed genera and metabolites were correlated. The functions of some disturbed gut microbes were consistent with the affected metabolic pathways in the sera, and these metabolic pathways were all associated with kidney disease, suggesting that TDCIPP may cause kidney injury in rats by affecting the intestinal flora and serum metabolism.

The metabolic pathway regulation in kidney injury and repair

Kidney injury and repair are accompanied by significant disruptions in metabolic pathways, leading to renal cell dysfunction and further contributing to the progression of renal pathology. This review outlines the complex involvement of various energy production pathways in glucose, lipid, amino acid, and ketone body metabolism within the kidney. We provide a comprehensive summary of the aberrant regulation of these metabolic pathways in kidney injury and repair. After acute kidney injury (AKI), there is notable mitochondrial damage and oxygen/nutrient deprivation, leading to reduced activity in glycolysis and mitochondrial bioenergetics. Additionally, disruptions occur in the pentose phosphate pathway (PPP), amino acid metabolism, and the supply of ketone bodies. The subsequent kidney repair phase is characterized by a metabolic shift toward glycolysis, along with decreased fatty acid β-oxidation and continued disturbances in amino acid metabolism. Furthermore, the impact of metabolism dysfunction on renal cell injury, regeneration, and the development of renal fibrosis is analyzed. Finally, we discuss the potential therapeutic strategies by targeting renal metabolic regulation to ameliorate kidney injury and fibrosis and promote kidney repair.

Metabolomics and machine learning approaches for diagnostic and prognostic biomarkers screening in sepsis

BACKGROUND

Sepsis is a life-threatening disease with a poor prognosis, and metabolic disorders play a crucial role in its development. This study aims to identify key metabolites that may be associated with the accurate diagnosis and prognosis of sepsis.

METHODS

Septic patients and healthy individuals were enrolled to investigate metabolic changes using non-targeted liquid chromatography-high-resolution mass spectrometry metabolomics. Machine learning algorithms were subsequently employed to identify key differentially expressed metabolites (DEMs). Prognostic-related DEMs were then identified using univariate and multivariate Cox regression analyses. The septic rat model was established to verify the effect of phenylalanine metabolism-related gene MAOA on survival and mean arterial pressure after sepsis.

RESULTS

A total of 532 DEMs were identified between healthy control and septic patients using metabolomics. The main pathways affected by these DEMs were amino acid biosynthesis, phenylalanine metabolism, tyrosine metabolism, glycine, serine and threonine metabolism, and arginine and proline metabolism. To identify sepsis diagnosis-related biomarkers, support vector machine (SVM) and random forest (RF) algorithms were employed, leading to the identification of four biomarkers. Additionally, analysis of transcriptome data from sepsis patients in the GEO database revealed a significant up-regulation of the phenylalanine metabolism-related gene MAOA in sepsis. Further investigation showed that inhibition of MAOA using the inhibitor RS-8359 reduced phenylalanine levels and improved mean arterial pressure and survival rate in septic rats. Finally, using univariate and multivariate cox regression analysis, six DEMs were identified as prognostic markers for sepsis.

CONCLUSIONS

This study employed metabolomics and machine learning algorithms to identify differential metabolites that are associated with the diagnosis and prognosis of sepsis patients. Unraveling the relationship between metabolic characteristics and sepsis provides new insights into the underlying biological mechanisms, which could potentially assist in the diagnosis and treatment of sepsis.

TRIAL REGISTRATION

This human study was approved by the Ethics Committee of the Research Institute of Surgery (2021-179) and was registered by the Chinese Clinical Trial Registry (Date: 09/12/2021, ChiCTR2200055772).

Metabolomics profile of plasma in acute diquat-poisoned patients using gas chromatography-mass spectrometry

Diquat (DQ) has been confirmed to be toxic to humans and responsible for severe health impairment. While to date, very little is known about the toxicological mechanisms of DQ. Thus, investigations to discover the toxic targets and potential biomarkers of DQ poisoning are urgently needed. In this study, a metabolic profiling analysis was conducted to reveal the changes of metabolites of plasma and find out the potential biomarkers of DQ intoxication by GC-MS. First, multivariate statistical analysis demonstrated that acute DQ poisoning can lead to metabolomic changes in human plasma. Then, metabolomics studies showed that 31 of the identified metabolites were significantly altered by DQ. Pathway analysis indicated that three primarily metabolic pathways including phenylalanine, tyrosine and tryptophan biosynthesis, taurine and hypotaurine metabolism, and phenylalanine metabolism were affected by DQ, resulting in the perturbations of phenylalanine, tyrosine, taurine, and cysteine. Finally, the results of receiver operating characteristic analysis showed the above four metabolites could be used as reliable tools for the diagnosis and severity assessments of DQ intoxication. These data provided the theoretical basis for basic research to understand the potential mechanisms of DQ poisoning, and also identified the desirable biomarkers with great potential for clinical applications.

Choline supplementation attenuates experimental sepsis-associated acute kidney injury

Acute kidney injury (AKI) is common in critically ill patients, and sepsis is its leading cause. Sepsis-associated AKI (SA-AKI) causes greater morbidity and mortality than other AKI etiologies, yet the underlying mechanisms are incompletely understood. Metabolomic technologies can characterize cellular energy derangements, but few discovery analyses have evaluated the metabolomic profile of SA-AKI. To identify metabolic derangements amenable to therapeutic intervention, we assessed plasma and urine metabolites in septic mice and critically ill children and compared them by AKI status. Metabolites related to choline and central carbon metabolism were differentially abundant in SA-AKI in both mice and humans. Gene expression of enzymes related to choline metabolism was altered in the kidneys and liver of mice with SA-AKI. Treatment with intraperitoneal choline improved renal function in septic mice. Because pediatric patients with sepsis displayed similar metabolomic profiles to septic mice, choline supplementation may attenuate pediatric septic AKI.NEW & NOTEWORTHY Altered choline metabolism plays a role in both human and murine sepsis-associated acute kidney injury (SA-AKI), and choline administration in experimental SA-AKI improved renal function. These findings indicate that 1) mouse models can help interrogate clinically relevant mechanisms and 2) choline supplementation may ameliorate human SA-AKI. Future research will investigate clinically the impact of choline supplementation on human renal function in sepsis and, using model systems, how choline mediates its effects.

Analysis of metabolic disturbances attributable to sepsis-induced myocardial dysfunction using metabolomics and transcriptomics techniques

Background: Sepsis-induced myocardial dysfunction (SIMD) is the most common and severe sepsis-related organ dysfunction. We aimed to investigate the metabolic changes occurring in the hearts of patients suffering from SIMD.

Methods: An animal SIMD model was constructed by injecting lipopolysaccharide (LPS) into mice intraperitoneally. Metabolites and transcripts present in the cardiac tissues of mice in the experimental and control groups were extracted, and the samples were studied following the untargeted metabolomics–transcriptomics high-throughput sequencing method. SIMD-related metabolites were screened following univariate and multi-dimensional analyses methods. Additionally, differential analysis of gene expression was performed using the DESeq package. Finally, metabolites and their associated transcripts were mapped to the relevant metabolic pathways after extracting transcripts corresponding to relevant enzymes. The process was conducted based on the metabolite information present in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.

Results: One hundred and eighteen significant differentially expressed metabolites (DEMs) (58 under the cationic mode and 60 under the anionic mode) were identified by studying the SIMD and control groups. Additionally, 3,081 significantly differentially expressed genes (DEGs) (1,364 were down-regulated and 1717 were up-regulated DEGs) were identified in the transcriptomes. The comparison was made between the two groups. The metabolomics–transcriptomics combination analysis of metabolites and their associated transcripts helped identify five metabolites (d-mannose, d-glucosamine 6-phosphate, maltose, alpha-linolenic acid, and adenosine 5′-diphosphate). Moreover, irregular and unusual events were observed during the processes of mannose metabolism, amino sugar metabolism, starch metabolism, unsaturated fatty acid biosynthesis, platelet activation, and purine metabolism. The AMP-activated protein kinase (AMPK) signaling pathways were also accompanied by aberrant events.

Conclusion: Severe metabolic disturbances occur in the cardiac tissues of model mice with SIMD. This can potentially help in developing the SIMD treatment methods.

Multi-Omics Techniques Make it Possible to Analyze Sepsis-Associated Acute Kidney Injury Comprehensively

Sepsis-associated acute kidney injury (SA-AKI) is a common complication in critically ill patients with high morbidity and mortality. SA-AKI varies considerably in disease presentation, progression, and response to treatment, highlighting the heterogeneity of the underlying biological mechanisms. In this review, we briefly describe the pathophysiology of SA-AKI, biomarkers, reference databases, and available omics techniques. Advances in omics technology allow for comprehensive analysis of SA-AKI, and the integration of multiple omics provides an opportunity to understand the information flow behind the disease. These approaches will drive a shift in current paradigms for the prevention, diagnosis, and staging and provide the renal community with significant advances in precision medicine in SA-AKI analysis.

The role of BBS2 in regulating adipogenesis and the association of its sequence variants with meat quality in Qinchuan cattle

The BBS2 gene plays a vital role in human obesity and fat deposition. However, little is known about it in beef cattle. Therefore, this study investigates the function of BBS2 in the fat deposition of beef cattle and screens the effective SNPs marker for meat quality traits in cattle breeding. The expression of BBS2 is negatively correlated with marbling ratios of beef cattle. Moreover, the knockdown of BBS2 promoted adipogenesis and lipid accumulation of bovine preadipocytes by stimulating PPARγ, FABP4, and FASN expression (P < 0.01). Four novel SNPs in the exons of BBS2 in Chinese Qinchuan cattle were identified and of which the g.24226239C > T (Q527), g.24223562G > A (V441I), and g.24227851A > G (Q627R) were significantly associated with the meat quality of Qinchuan cattle (P < 0.01, P < 0.05). The findings suggested that BBS2 could be used as a candidate gene for meat quality improvement in Qinchuan cattle. Furthermore, these genotypes can be exploited as molecular markers in future beef breeding projects.

Metabolomic profiling demonstrates evidence for kidney and urine metabolic dysregulation in a piglet model of cardiac surgery-induced acute kidney injury

Acute kidney injury (AKI) is a common cause of morbidity after congenital heart disease surgery. Progress on diagnosis and therapy remains limited, however, in part due to poor mechanistic understanding and a lack of relevant translational models. Metabolomic approaches could help identify novel mechanisms of injury and potential therapeutic targets. In the present study, we used a piglet model of cardiopulmonary bypass with deep hypothermic circulatory arrest (CPB/DHCA) and targeted metabolic profiling of kidney tissue, urine, and serum to evaluate metabolic changes specific to animals with histological acute kidney injury. CPB/DHCA animals with acute kidney injury were compared with those without acute kidney injury and mechanically ventilated controls. Acute kidney injury occurred in 10 of 20 CPB/DHCA animals 4 h after CPB/DHCA and 0 of 7 control animals. Injured kidneys showed a distinct tissue metabolic profile compared with uninjured kidneys (R² = 0.93, Q² = 0.53), with evidence of dysregulated tryptophan and purine metabolism. Nine urine metabolites differed significantly in animals with acute kidney injury with a pattern suggestive of increased aerobic glycolysis. Dysregulated metabolites in kidney tissue and urine did not overlap. CPB/DHCA strongly affected the serum metabolic profile, with only one metabolite that differed significantly with acute kidney injury (pyroglutamic acid, a marker of oxidative stress). In conclusion, based on these findings, kidney tryptophan and purine metabolism are candidates for further mechanistic and therapeutic investigation. Urine biomarkers of aerobic glycolysis could help diagnose early acute kidney injury after CPB/DHCA and warrant further evaluation. The serum metabolites measured at this early time point did not strongly differentiate based on acute kidney injury.

NEW & NOTEWORTHY This project explored the metabolic underpinnings of postoperative acute kidney injury (AKI) following pediatric cardiac surgery in a translationally relevant large animal model of cardiopulmonary bypass with deep hypothermic circulatory arrest. Here, we present novel evidence for dysregulated tryptophan catabolism and purine catabolism in kidney tissue and increased urinary glycolysis intermediates in animals who developed histological AKI. These pathways represent potential diagnostic and therapeutic targets for postoperative AKI in this high-risk population.

Dexpanthenol attenuates inflammatory damage and apoptosis in kidney and liver tissues of septic mice

Sepsis is capable of causing systemic infections resulting in multiple organ damage. Dexpanthenol (DXP) has been reported to protect against kidney and liver injury. Therefore, this paper attempts to explore the role of DXP in sepsis-induced kidney and liver injury. A mice model of sepsis was established using the cecal ligation and puncture (CLP) method. The expressions of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and monocyte chemoattractant protein (MCP)-1 in the serum of mice were measured utilizing enzyme linked immunosorbent assay (ELISA). Additionally, the damage of kidney and liver tissues in CLP-induced mice was determined by their respective commercial kits, western blot, and hematoxylin–eosin (HE) staining kits. The apoptosis of kidney and liver tissues in CLP-induced mice was assessed by means of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and western blot. It was observed that DXP decreased the expressions of TNF-α, IL-1β, IL-6, and MCP-1 in the serum of CLP-induced mice, attenuated the functional impairment, pathological damage, inflammation, and cell apoptosis of kidney tissue. Meanwhile, DXP decreased the functional impairment of liver in CLP-induced mice, reduced the levels of inflammatory factors and antioxidant enzymes, attenuated liver pathological damage, and decreased cell apoptosis in liver tissues. In conclusion, DXP attenuates inflammatory damage and apoptosis in kidney and liver organs in a sepsis model.

A Deep Insight Into Regulatory T Cell Metabolism in Renal Disease: Facts and Perspectives

Kidney disease encompasses a complex set of diseases that can aggravate or start systemic pathophysiological processes through their complex metabolic mechanisms and effects on body homoeostasis. The prevalence of kidney disease has increased dramatically over the last two decades. CD4⁺CD25⁺ regulatory T (Treg) cells that express the transcription factor forkhead box protein 3 (Foxp3) are critical for maintaining immune homeostasis and preventing autoimmune disease and tissue damage caused by excessive or unnecessary immune activation, including autoimmune kidney diseases. Recent studies have highlighted the critical role of metabolic reprogramming in controlling the plasticity, stability, and function of Treg cells. They are also likely to play a vital role in limiting kidney transplant rejection and potentially promoting transplant tolerance. Metabolic pathways, such as mitochondrial function, glycolysis, lipid synthesis, glutaminolysis, and mammalian target of rapamycin (mTOR) activation, are involved in the development of renal diseases by modulating the function and proliferation of Treg cells. Targeting metabolic pathways to alter Treg cells can offer a promising method for renal disease therapy. In this review, we provide a new perspective on the role of Treg cell metabolism in renal diseases by presenting the renal microenvironment、relevant metabolites of Treg cell metabolism, and the role of Treg cell metabolism in various kidney diseases.

Maintaining homeostasis of mitochondria and endoplasmic reticulum with NSC228155 alleviates cisplatin-induced acute kidney injury

Acute kidney injury (AKI) is a common complication of hospitalization with high mortality. Approximately 30% of patients receiving cisplatin, the first-line chemotherapy treatment, develop AKI. NSC228155 is a novel compound with potential anti-cancer and anti-bacterial effects. Its therapeutic efficacy in other diseases is unclear. In the present study, we investigated the effect of NSC228155 on cisplatin-induced AKI. The mice were consecutively treated with 2.5 mg/kg of NSC228155 for five days and injected with cisplatin (22 mg/kg) via intraperitoneal injection on day three. NSC228155 strikingly improved the renal function by decreasing the serum creatinine by 52.6% in the cisplatin-induced AKI mice model. Pathologically, NSC228155 profoundly alleviated the tubular damage in Periodic Acid-Schiff staining, and significantly reduced the expression of tubular injury markers and apoptosis in the cisplatin-injured mice kidneys. NSC228155 effectively restored the mitochondrial homeostasis by decreasing damaged mitochondria, activating signals for mitochondrial dynamics and recycling, and corrected mitochondrial dysfunction in ATP production and oxidative stress in the cisplatin model. Transcriptomics and metabolomics analysis on the mice renal cortex suggested that NSC228155 profoundly corrected energy metabolism, especially citrate cycle-related pathways, oxidative stress, and endoplasmic reticulum (ER) stress in the cisplatin-induced AKI kidneys. NSC228155 effectively inhibited ER stress induced by cisplatin or tunicamycin in mice kidneys and HK-2 cells. Co-treatment of NSC228155 with 4-phenylbutyrate or MnTBAP showed a similar therapeutic effect in AKI as the inhibitors or NSC228155 alone did, and corrected the mitochondrial dysfunction and ER stress, respectively, indicating the crosstalk between ER and mitochondria played essential roles in the therapeutic effect of NSC228155 in AKI. Together, these results consistently demonstrated that NSC228155 alleviated cisplatin-induced AKI by restoring the homeostasis in mitochondria and ER, suggesting a therapeutic potential and perhaps a novel strategy for drug discovery.

Metabolomic Study on Iohexol-Induced Nephrotoxicity in Rats Based on NMR and LC-MS Analyses

Iohexol, the raw material of nonionic X-ray computed tomography (X-CT) contrast medium, is usually injected into the vein before CT angiography diagnosis. It is used for angiography, urography, and lymphography. With the advantages of low contrast density and good tolerance, it is currently one of the most popular contrast media. However, the renal toxicity of iohexol seriously affects its safety use. Therefore, it is of great importance to identify new potential diagnostic biomarkers and therapeutic targets in the process of contrast medium-induced acute kidney injury (CI-AKI) in order to safely use iohexol in clinical practice. In this study, in order to understand the metabolic mechanism of CI-AKI, ultra-high-performance liquid chromatography/quadrupole-Orbitrap-mass spectrometry and ¹H NMR-based metabolomic techniques were utilized to study the metabolic spectra of kidney, plasma, and urine from CI-AKI rats, and a total of 30 metabolites that were closely related to kidney injury were screened out, which were mainly related to 9 metabolic pathways. The results further indicated that iohexol might intensify kidney dysfunction in vivo by disrupting the metabolic pathways in the body, especially through blocking energy metabolism, amino acid metabolism, and promoting inflammatory reactions.

Metabolic Profiling Analysis of Liver in Landes Geese During the Formation of Fatty Liver via GC-TOF/MS

Fatty liver production results from the process of overfeeding geese, inducing a dramatic increase in de novo liver lipogenesis. To investigate the alteration of liver metabolites by overfeeding, especially lipid metabolites, and the potential pathways causing these changes, 60 Landes geese at 65 days old were raised in three groups with 20 geese per group, namely, the D0 group (free from gavage), D7 group (overfeeding for 7 days), and D25 group (overfeeding for 25 days). At 90 days old, segments of liver tissue were collected from 10 geese of each group for gas chromatography time-of-flight/mass spectrometry (GC-TOF/MS) analysis. A large number of endogenous molecules in the livers of geese were altered dramatically by overfeeding. In the livers of overfed geese, the level of oleic acid was observed to continuously increase, while the levels of phenylalanine, methyl phosphate, sulfuric acid, and 3-hydroxybenzaldehyde were decreased. The most significantly different metabolites were enriched in amino acid, lipid, and nucleotide metabolism pathways. The present study further supports the idea that Landes geese efficiently produce fatty liver, and potential biomarkers and disturbed metabolic pathways during the process of forming fatty liver were identified. In conclusion, this study might provide some insights into the underlying mechanisms of fatty liver formation.

The predict value of serum/urocystatin C on acute kidney injury in elderly patients with sepsis

OBJECTIVE

To evaluate the predict value of serum/urocystatin C in acute kidney injury (AKI) in elderly patients with sepsis.

METHODS

A retrospective study was performed and 80 senile patients with sepsis in ** hospital of China was included. According to the diagnosis of AKI, all patients were divided into non-AKI group and AKI group. The clinical characteristics, laboratory and physiological indicators of the two groups were compared. The receiver operating characteristic curve (ROC) was used to analyze the accuracy of the variables, including serum cystatin C, urocystatin C, and serum creatinine, to predict the occurrence of AKI in patients with sepsis.

RESULTS

Of the 80 elderly patients with sepsis in China, 29 patients had AKI. Compared with the non-AKI group, patients in the AKI group had higher APACHE II scores, higher SOFA scores, higher procalcitonin, and lower mean arterial pressure (P < 0.05). The levels of serum cystatin C, urocystatin C, and serum creatinine in the AKI group were significantly higher than those in the non-AKI group (P < 0.05), while the difference in intensive care unit (ICU) mortality rate between the two groups was not significantly different (P > 0.05). The ROC curve showed that the area under the curve of serum cystatin C was 0.893, the area under the curve of urocystatin C was 0.898, and the area under the curve of serum creatinine was 0.652.

CONCLUSION

Serum cystatin and urocystatin could be used to predict the occurrence of AKI in elderly patients with sepsis.

Serum metabolic profile of postoperative acute kidney injury following infant cardiac surgery with cardiopulmonary bypass

BACKGROUND

We sought to determine differences in the circulating metabolic profile of infants with or without acute kidney injury (AKI) following cardiothoracic surgery with cardiopulmonary bypass (CPB).

METHODS

We performed a secondary analysis of preoperative and 24-h postoperative serum samples from infants ≤ 120 days old undergoing CPB. Metabolic profiling of the serum samples was performed by targeted analysis of 165 serum metabolites via tandem mass spectrometry. We then compared infants who did or did not develop AKI in the first 72 h postoperatively to determine global differences in the preoperative and 24-h metabolic profiles in addition to specific differences in individual metabolites.

RESULTS

A total of 57 infants were included in the study. Six infants (11%) developed KDIGO stage 2/3 AKI and 13 (23%) developed stage 1 AKI. The preoperative metabolic profile did not differentiate between infants with or without AKI. Infants with severe AKI could be moderately distinguished from infants without AKI by their 24-h metabolic profile, while infants with stage 1 AKI segregated into two groups, overlapping with either the no AKI or severe AKI groups. Differences in these 24-h metabolic profiles were driven by 21 metabolites significant at an adjusted false discovery rate of < 0.05. Prominently altered pathways include purine, methionine, and kynurenine/nicotinamide metabolism.

CONCLUSION

Moderate-to-severe AKI after infant cardiac surgery is associated with changes in the serum metabolome, including prominent changes to purine, methionine, and kynurenine/nicotinamide metabolism. A portion of infants with mild AKI demonstrated similar metabolic changes, suggesting a potential role for metabolic analysis in the evaluation of lower stage injury.

Alteration of N6-Methyladenosine RNA Profiles in Cisplatin-Induced Acute Kidney Injury in Mice

Aim: To identify the alterations of N6-methyladenosine (m⁶A) RNA profiles in cisplatin-induced acute kidney injury (Cis-AKI) in mice.

Materials and Methods: The total level of m⁶A and the expression of methyltransferases and demethylases in the kidneys were measured. The profiles of methylated RNAs were determined by the microarray method. Bioinformatics analysis was performed to predict the functions.

Results: Global m⁶A levels were increased after cisplatin treatment, accompanied by the alterations of Mettl3, Mettl14, Wtap, Fto, and Alkbh5. A total of 618 mRNAs and 98 lncRNAs were significantly differentially methylated in response to cisplatin treatment. Bioinformatics analysis indicated that the methylated mRNAs predominantly acted on the metabolic process.

Conclusion: M⁶A epitranscriptome might be significantly altered in Cis-AKI, which is potentially implicated in the development of nephrotoxicity.

Changes of Lipopolysaccharide-Induced Acute Kidney and Liver Injuries in Rats Based on Metabolomics Analysis

Background

The bacterial endotoxin lipopolysaccharide (LPS) was the classic inducer to establish many inflammatory disease models, especially multiple organ injury. Evidences indicated that the mechanism that causes inflammation response is not just related to cytokine release. The main aim of this study was to better elucidate the possible links between metabolic changes and the pathogenesis of LPS-induced acute liver and kidney in order to understand the mechanisms and screening therapeutic targets for developing early diagnostic strategies and treatments.

Methods

An experimental rat model was established by intraperitoneal injection of 10 mg/kg LPS. An untargeted metabolomics analysis of the serum in the LPS and control groups was carried out using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/QTOF-MS). LPS-induced pathological damage in the lungs, liver, kidneys, and colon was observed, along with changes in biochemical indexes, indicating that there was a severe inflammatory response in many organs after administration of LPS for 8 h. Principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) showed distinct separation in the serum metabolite profiles between the LPS and control groups, indicating significant changes in endogenous metabolites.

Results

The untargeted metabolomics analysis showed that there were 127 significantly different serum metabolites and 53 altered pathways after LPS administration, including pathways related to the metabolism of D-glutamine and D-glutamate, taurine and hypotaurine, beta-alanine, glutathione, and butanoate, which are involved in the inflammatory response, oxidative stress, and amino acid metabolism.

Conclusion

The study suggested that LPS-induced acute liver and kidney injury mainly involves inflammatory response, oxidative stress, and protein synthesis, finally causing multi-organ damage. Correcting the disturbances to the metabolites and metabolic pathways may help to prevent and/or treat LPS-induced acute liver and kidney damage.

Metabolomics Analysis of the Development of Sepsis and Potential Biomarkers of Sepsis-Induced Acute Kidney Injury

Sepsis-induced acute kidney injury (SI-AKI) is a serious condition in critically ill patients. Currently, the diagnosis is based on either elevated serum creatinine levels or oliguria, which partially contribute to delayed recognition of AKI. Metabolomics is a potential approach for identifying small molecule biomarkers of kidney diseases. Here, we studied serum metabolomics alterations in rats with sepsis to identify early biomarkers of sepsis and SI-AKI. A rat model of SI-AKI was established by intraperitoneal injection of lipopolysaccharide (LPS). Thirty Sprague-Dawley (SD) rats were randomly divided into the control (CT) group and groups treated for 2 hours (LPS2) and 6 hours (LPS6) with LPS (10 rats per group). Nontargeted metabolomics screening was performed on the serum samples from the control and SI-AKI groups. Combined multivariate and univariate analysis was used for pairwise comparison of all groups to identify significantly altered serum metabolite levels in early-stage AKI in rats with sepsis. Orthogonal partial least squares discriminant analysis (OPLS-DA) showed obvious separation between the CT and LPS2 groups, CT and LPS6 groups, and LPS2 and LPS6 groups. All comparisons of the groups identified a series of differential metabolites according to the threshold defined for potential biomarkers. Intersections and summaries of these differential metabolites were used for pathway enrichment analysis. The results suggested that sepsis can cause an increase in systemic aerobic and anaerobic metabolism, an impairment of the oxygen supply, and uptake and abnormal fatty acid metabolism. Changes in the levels of malic acid, methionine sulfoxide, and petroselinic acid were consistently measured during the progression of sepsis. The development of sepsis was accompanied by the development of AKI, and these metabolic disorders are directly or indirectly related to the development of SI-AKI.

The Albumin-to-Fibrinogen Ratio Independently Predicts Acute Kidney Injury in Infants With Ventricular Septal Defect Undergoing Cardiac Surgery With Cardiopulmonary Bypass

Background: Acute kidney injury (AKI) is a common and serious complication faced by children following ventricular septal defect (VSD) surgery with cardiopulmonary bypass (CPB). The objective of this study was to explore potential predictors inherent to AKI. Methods: VSD infants who were scheduled for elective cardiac surgery with CPB from 2017 to 2020 were enrolled in this study. Based on the Pediatric Risk, Injury, Failure, Loss, End-Stage Renal Disease (pRIFLE) criteria, patients were divided into AKI and non-AKI groups. Univariate and multivariate logistic regression analyses were carried out in order to evaluate potential risk factors for AKI. Receiver operating characteristic (ROC) curves were generated to evaluate the predictive probabilities of risk factors for AKI. Results: Of all the 338 enrolled VSD infants, 49 manifested AKI with an incidence of 14.5% (49/338). The ROC curve indicated that albumin-to-fibrinogen ratio (AFR) during CPB was a significant predictor of AKI [area under the curve (AUC), 0.711; p < 0.001]. Based on the univariate and multivariate logistic analyses, AFR during CPB [odds ratio (OR), 1.89; 95% confidence interval (CI), 1.22-2.76, p = 0.011] was the only independent risk factor for AKI. Conclusions: This study demonstrated that a low AFR (<9.35) during CPB was an independent risk factor for AKI in VSD infants following cardiac surgery with CPB.

Alteration of plasma metabolites associated with chemoradiosensitivity in esophageal squamous cell carcinoma via untargeted metabolomics approach

BACKGROUND

To investigate the differences in plasma metabolomic characteristics between pathological complete response (pCR) and non-pCR patients and identify biomarker candidates for predicting the response to neoadjuvant chemoradiotherapy (nCRT) in esophageal squamous cell carcinoma (ESCC).

METHODS

A total of 46 ESCC patients were included in this study. Gas chromatography time-of- flight mass spectrometry (GC-TOF/MS) technology was applied to detect the plasma samples collected before nCRT via untargeted metabolomics analysis.

RESULTS

Five differentially expressed metabolites (out of 109) was found in plasma between pCR and non-pCR groups. Compared with non-pCR group, isocitric acid (p = 0.0129), linoleic acid (p = 0.0137), citric acid (p = 0.0473) were upregulated, while L-histidine (p = 0.0155), 3'4 dihydroxyhydrocinnamic acid (p = 0.0339) were downregulated in the pCR plasma samples. Pathway analyses unveiled that citrate cycle (TCA cycle), glyoxylate and dicarboxylate metabolic pathway were associated with ESCC chemoradiosensitivity.

CONCLUSION

The present study provided supporting evidence that GC-TOF/MS based metabolomics approach allowed identification of metabolite differences between pCR and non-pCR patients in plasma levels, and the systemic metabolic status of patients may reflect the response of ESCC patient to neoadjuvant chemoradiotherapy.

Comprehensive Evaluation of Lipopolysaccharide-Induced Changes in Rats Based on Metabolomics

Purpose

Substantial evidence indicates that lipopolysaccharide (LPS) exposure can lead to systemic inflammatory response syndrome (SIRS) and multiple organ failure. Previous metabolomic studies have mainly focused on LPS-induced depression or hepatic and renal effects. However, no comprehensive metabolomics-based analysis of the serum, liver, kidney, hippocampus, and heart following exposure to LPS has been undertaken to date.

Material and Methods

Male Sprague-Dawley rats were randomly allocated to a control and a LPS-treated group (n=8). LPS for 2 weeks (0.5 mg/kg every other day) was given via intraperitoneal injection. Gas chromatography-mass spectrometry (GC-MS) was used for metabolite determination, while multivariate statistical analysis was performed to identify differentially expressed metabolites between the two groups.

Results

Our study revealed that 24, 13, 12, 7, and 12 metabolites were differentially expressed between the LPS treatment group and the control group in the serum, liver, kidney, hippocampus, and heart, respectively. We further identified that these metabolic changes were mainly involved with aminoacyl-tRNA biosynthesis; glutathione metabolism; glyoxylate and dicarboxylate metabolism; glycine, serine, and threonine metabolism; arginine biosynthesis; bile acid biosynthesis; and glycerolipid metabolism.

Conclusion

We have systematically elucidated the metabolic changes underlying LPS-induced SIRS, thereby providing insight into the mechanisms associated with these alterations.