A Non-Targeted Capillary Electrophoresis-Mass Spectrometry Strategy to Study Metabolic Differences in an In vitro Model of High-Glucose Induced Changes in Human Proximal Tubular HK-2 Cells

Delivery of exogenous miR-19b by Wharton's Jelly Mesenchymal Stem Cells attenuates transplanted kidney ischemia/reperfusion injury by regulating cellular metabolism

Renal ischemia-reperfusion injury (IRI) frequently occurs following kidney transplantation, and exosomes derived from umbilical cord mesenchymal stem cells (WJ-MSC-Exos) have shown promise in treating IRI in transplanted kidneys. Our study delved into the potential mechanism of WJ-MSC-Exos in ameliorating IRI in transplanted kidneys, revealing that miR-19b is abundantly present in WJ-MSC-Exos. Both in vivo and in vitro experiments demonstrated that the absence of miR-19b abolished the protective effects of WJ-MSC-Exos against renal IRI. Mechanistically, miR-19b suppressed glycogen synthase kinase-3β (GSK3β) expression, thereby stabilizing PDXK protein through direct binding. Treatment with WJ-MSC-Exos led to reduced PDXK levels and enhanced pyridoxine accumulation, ultimately mitigating IRI in transplanted kidneys and I/R-induced HK2 cell apoptosis. These findings elucidate the underlying mechanism of WJ-MSC-Exos in alleviating IRI in transplanted kidneys, unveiling novel therapeutic targets for post-kidney transplantation IRI and providing a solid theoretical foundation for the clinical application of WJ-MSC-Exos in IRI treatment post-transplantation.

Piceatannol Protects against High Glucose-Induced Injury of Renal Tubular Epithelial Cells via Regulating Carbonic Anhydrase 2

INTRODUCTION

We here evaluated the efficacy of piceatannol (PIC) in high glucose (HG)-induced injury of renal tubular epithelial cells HK-2.

METHODS

After the establishment of an HG-induced cell injury model and the treatment with PIC at both high and low concentrations and/or acetazolamide (ACZ, the inhibitor of carbonic anhydrase 2 [CA2]), MTT and flow cytometry assays were carried out to confirm the viability and apoptosis of HK-2 cells. The levels of oxidative stress markers lactate dehydrogenase (LDH), malondialdehyde (MDA), and reactive oxygen species (ROS), the ratio of glutathione/oxidized glutathione (GSH/GSSG), and the CA2 activity were determined. Both quantitative reverse-transcription polymerase chain reaction and Western blot were used to calculate the expressions of CA2 (the predicted target gene of PIC via intersecting the data from bioinformatic analyses) and AKT pathway-related (phosphatase and tensin homolog [PTEN], phosphorylated [p]-AKT, AKT) and apoptosis-related proteins (Bcl-2 and cleaved caspase-3).

RESULTS

HG suppressed cell viability and the levels of GSH/GSSG ratio, CA2, pThr308-AKT/AKT, pSer473-AKT/AKT, and Bcl-2, while promoting cell apoptosis, the levels of LDH, MDA, and ROS, and the expressions of PTEN and cleaved caspase-3. All effects of HG were reversed by PIC at a high concentration. CA2 was predicted and identified as the target of PIC. In HG-treated HK-2 cells, additionally, ACZ reversed the effects of PIC on the viability, apoptosis, and levels of both oxidative stress markers and AKT pathway- and apoptosis-related factors.

CONCLUSION

PIC protects against HG-induced injury of HK-2 cells via regulating CA2.

Long Non-Coding RNA Small Nucleolar RNA Host Gene 5 (SNHG5) Regulates Renal Tubular Damage in Diabetic Nephropathy via Targeting MiR-26a-5p

The study explored the diagnostic value of SNHG5 in diabetic nephropathy (DN) and investigated the role and mechanism on DN via establishing the in vitro HK2 cell model. This study recruited 62 types 2 diabetes mellitus (T2DM) patients, 58 DN patients and 60 healthy controls (HC). The expressions of serum SNHG5 and miR-26a-5p were measured by RT-qPCR analysis. The diagnostic value of SNHG5 in DN was assessed by ROC curve. The in vitro cell model was built to estimate the effects of SNHG5 on cell viability, cell apoptosis, inflammation response and oxidative stress. Serum SNHG5 was increased in DN patients (relative expression: 2.04±0.34) and had the diagnostic value in DN. After HK2 cells were treated with high glucose, the cell viability decreased and apoptosis increased, and the production of inflammatory cytokines and ROS enhanced significantly. It was noticed that inhibition of SNHG5 could reverse the above phenomenon caused by high glucose. Besides, serum miR-26a-5p was diminished in DN patients, and luciferase reporter gene revealed that miR-26a-5p is direct target of SNHG5. These results indicated that inhibition of SNHG5 may mitigate HG-induced renal tubular damage via targeting miR-26a-5p, which providing a new insight into the mechanism of renal tubule damage in DN patients.

Exploratory Metabolomic Analysis Based on Reversed-Phase Liquid Chromatography-Mass Spectrometry to Study an In Vitro Model of Hypoxia-Induced Metabolic Alterations in HK-2 Cells

Oxygen deficiency in cells, tissues, and organs can not only prevent the proper development of biological functions but it can also lead to several diseases and disorders. In this sense, the kidney deserves special attention since hypoxia can be considered an important factor in the pathophysiology of both acute kidney injury and chronic kidney disease. To provide better knowledge to unveil the molecular mechanisms involved, new studies are necessary. In this sense, this work aims to study, for the first time, an in vitro model of hypoxia-induced metabolic alterations in human proximal tubular HK-2 cells because renal proximal tubules are particularly susceptible to hypoxia. Different groups of cells, cultivated under control and hypoxia conditions at 0.5, 5, 24, and 48 h, were investigated using untargeted metabolomic approaches based on reversed-phase liquid chromatography–mass spectrometry. Both intracellular and extracellular fluids were studied to obtain a large metabolite coverage. On the other hand, multivariate and univariate analyses were carried out to find the differences among the cell groups and to select the most relevant variables. The molecular features identified as affected metabolites were mainly amino acids and Amadori compounds. Insights about their biological relevance are also provided.

Comprehensive metabolomic study of the response of HK-2 cells to hyperglycemic hypoxic diabetic-like milieu

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease. Although hyperglycaemia has been determined as the most important risk factor, hypoxia also plays a relevant role in the development of this disease. In this work, a comprehensive metabolomic study of the response of HK-2 cells, a human cell line derived from normal proximal tubular epithelial cells, to hyperglycemic, hypoxic diabetic-like milieu has been performed. Cells simultaneously exposed to high glucose (25 mM) and hypoxia (1% O2) were compared to cells in control conditions (5.5 mM glucose/18.6% O2) at 48 h. The combination of advanced metabolomic platforms (GC-TOF MS, HILIC- and CSH-QExactive MS/MS), freely available metabolite annotation tools, novel databases and libraries, and stringent cut-off filters allowed the annotation of 733 metabolites intracellularly and 290 compounds in the extracellular medium. Advanced bioinformatics and statistical tools demonstrated that several pathways were significantly altered, including carbohydrate and pentose phosphate pathways, as well as arginine and proline metabolism. Other affected metabolites were found in purine and lipid metabolism, the protection against the osmotic stress and the prevention of the activation of the β-oxidation pathway. Overall, the effects of the combined exposure of HK-cells to high glucose and hypoxia are reasonably compatible with previous in vivo works.

CE-MS for metabolomics: Developments and applications in the period 2018-2020

Capillary electrophoresis-mass spectrometry (CE-MS) is now a mature analytical technique in metabolomics, notably for the efficient profiling of polar and charged metabolites. Over the past few years, (further) progress has been made in the design of improved interfacing techniques for coupling CE to MS; also, in the development of CE-MS approaches for profiling metabolites in volume-restricted samples, and in strategies that further enhance the metabolic coverage. In this article, which is a follow-up of a previous review article covering the years 2016-2018 (Electrophoresis 2019, 40, 165-179), the main (technological) developments in CE-MS methods and strategies for metabolomics are discussed covering the literature from July 2018 to June 2020. Representative examples highlight the utility of CE-MS in the fields of biomedical, clinical, microbial, plant and food metabolomics. A complete overview of recent CE-MS-based metabolomics studies is given in a table, which provides information on sample type and pretreatment, capillary coatings, and MS detection mode. Finally, some general conclusions and perspectives are given.

Effect of Salinomycin on Expression Pattern of Genes Associated with Apoptosis in Endometrial Cancer Cell Line

Background

Salinomycin is part of a group of ionophore antibiotics characterized by an activity towards tumor cells. To this day, the mechanism through which salinomycin induces their apoptosis is not fully known yet. The goal of this study was to assess the expression pattern of genes and the proteins coded by them connected with the process of programmed cell death in an endometrial cancer cell Ishikawa culture exposed to salinomycin and compared to the control.

Materials and Methods

Analysis of the effect of salinomycin on Ishikawa endometrial cancer cells (ECACC 99040201) included a cytotoxicity MTT test (with a concentration range of 0.1-100 µM), assessment of the induction of apoptosis and necrosis by salinomycin at a concentration of 1 µM as well the assessment of the expression of the genes chosen in the microarray experiment (microarray HG-U 133A_2) and the proteins coded by them connected with apoptosis (RTqPCR, ELISA assay). The statistical significance level for all analyses carried out as part of this study was p<0.05.

Results

It was observed that salinomycin causes the death of about 50% of cells treated by it (50.74±0.80% of all cells) at a concentration of 1µM. The decrease in the number of living cells was determined directly after treatment of the cells with the drug (time 0). The average percent of late apoptotic cells was 1.65±0.24% and 0.57±0.01% for necrotic cells throughout the entire observation period.

Discussion

Microarray analysis indicated the following number of mRNA differentiating the culture depending on the time of incubation with the drug: H_12 vs C = 114 mRNA, H_8 vs C = 84 mRNA, H_48 vs. C = 27 mRNA, whereas 5 mRNAs were expressed differently at all times. During the whole incubation period of the cells with the drug, the following dependence of the expression profile of the analyzed transcripts was observed: Bax>p53>FASL>BIRC5>BCL2L.

Conclusion

The analysis carried out indicated that salinomycin, at a concentration of 1 µM, stopped the proliferation of 50% of endometrial cancer cells, mainly by inducing the apoptotic process of the cells. The molecular exponent of the induction of programmed cell death was an observed increase in the transcriptional activity of pro-apoptotic genes: Bax;p53;FASL and a decrease in the expression of anti-apoptotic genes: BCL2L2; BIRC5.