Expression of oxidative stress and antioxidant defense genes in the kidney of inbred mice after intestinal ischemia and reperfusion

Potential Neuromodulation of the Cardio-Renal Syndrome

The cardio-renal syndrome (CRS) type 2 is defined as a progressive loss of renal function following a primary insult to the myocardium that may be either acute or chronic but is accompanied by a decline in myocardial pump performance. The treatment of patients with CRS is difficult, and the disease often progresses to end-stage renal disease that is refractory to conventional therapy. While a good deal of information is known concerning renal injury in the CRS, less is understood about how reflex control of renal sympathetic nerve activity affects this syndrome. In this review, we provide insight into the role of the renal nerves, both from the afferent or sensory side and from the efferent side, in mediating renal dysfunction in CRS. We discuss how interventions such as renal denervation and abrogation of systemic reflexes may be used to alleviate renal dysfunction in the setting of chronic heart failure. We specifically focus on a novel cardiac sensory reflex that is sensitized in heart failure and activates the sympathetic nervous system, especially outflow to the kidney. This so-called Cardiac Sympathetic Afferent Reflex (CSAR) can be ablated using the potent neurotoxin resinferitoxin due to the high expression of Transient Receptor Potential Vanilloid 1 (TRPV1) receptors. Following ablation of the CSAR, several markers of renal dysfunction are reversed in the post-myocardial infarction heart failure state. This review puts forth the novel idea of neuromodulation at the cardiac level in the treatment of CRS Type 2.

Nutrigenomic Studies on the Ameliorative Effect of Enzyme-Digested Phycocyanin in Alzheimer's Disease Model Mice

Alzheimer’s disease (AD) is the most common form of dementia, and the cognitive impairments associated with this degenerative disease seriously affect daily life. Nutraceuticals for the prevention or delay of AD are urgently needed. It has been increasingly observed that phycocyanin (PC) exerts neuroprotective effects. AD model mice intracerebroventricularly injected with amyloid beta-peptide 25–35 (Aβ_25–35) at 10 nmol/head displayed significant cognitive impairment in the spontaneous alternation test. Cognitive impairment was significantly ameliorated in mice treated with 750 mg/kg of enzyme-digested (ED) PC by daily oral administration for 22 consecutive days. Application of DNA microarray data on hippocampal gene expression to nutrigenomics studies revealed that oral EDPC counteracted the aberrant expression of 35 genes, including Prnp, Cct4, Vegfd (Figf), Map9 (Mtap9), Pik3cg, Zfand5, Endog, and Hbq1a. These results suggest that oral administration of EDPC ameliorated cognitive impairment in AD model mice by maintaining and/or restoring normal gene expression patterns in the hippocampus.

Antioxidative and Angiogenic Hyaluronic Acid-Based Hydrogel for the Treatment of Peripheral Artery Disease

Peripheral arterial disease (PAD) is a progressive atherosclerotic disorder characterized by blockages of the arteries supplying the lower extremities. Ischemia initiates oxidative damage and mitochondrial dysfunction in the legs of PAD patients, causing injury to the tissues of the leg, significant decline in walking performance, leg pain while walking, and in the most severe cases, nonhealing ulcers and gangrene. Current clinical trials based on cells/stem cells, the trophic factor, or gene therapy systems have shown some promising results for the treatment of PAD. Biomaterial matrices have been explored in animal models of PAD to enhance these therapies. However, current biomaterial approaches have not fully met the essential requirements for minimally invasive intramuscular delivery to the leg. Ideally, a biomaterial should present properties to ameliorate oxidative stress/damage and failure of angiogenesis. Recently, we have created a thermosensitive hyaluronic acid (HA) hydrogel with antioxidant capacity and skeletal muscle-matching stiffness. Here, we further optimized HA hydrogels with the cell adhesion peptide RGD to facilitate the development of vascular-like structures in vitro. The optimized HA hydrogel reduced intracellular reactive oxygen species levels and preserved vascular-like structures against H₂O₂-induced damage in vitro. HA hydrogels also provided prolonged release of the vascular endothelial growth factor (VEGF). After injection into rat ischemic hindlimb muscles, this VEGF-releasing hydrogel reduced lipid oxidation, regulated oxidative-related genes, enhanced local blood flow in the muscle, and improved running capacity of the treated rats. Our HA hydrogel system holds great potential for the treatment of the ischemic legs of patients with PAD.

Mitochondrial Dysfunction and Diabetic Nephropathy: Nontraditional Therapeutic Opportunities

Diabetic nephropathy (DN) is a progressive microvascular diabetic complication. Growing evidence shows that persistent mitochondrial dysfunction contributes to the progression of renal diseases, including DN, as it alters mitochondrial homeostasis and, in turn, affects normal kidney function. Pharmacological regulation of mitochondrial networking is a promising therapeutic strategy for preventing and restoring renal function in DN. In this review, we have surveyed recent advances in elucidating the mitochondrial networking and signaling pathways in physiological and pathological contexts. Additionally, we have considered the contributions of nontraditional therapy that ameliorate mitochondrial dysfunction and discussed their molecular mechanism, highlighting the potential value of nontraditional therapies, such as herbal medicine and lifestyle interventions, in therapeutic interventions for DN. The generation of new insights using mitochondrial networking will facilitate further investigations on nontraditional therapies for DN.

α1-Microglobulin (A1M) Protects Human Proximal Tubule Epithelial Cells from Heme-Induced Damage In Vitro

Oxidative stress is associated with many renal disorders, both acute and chronic, and has also been described to contribute to the disease progression. Therefore, oxidative stress is a potential therapeutic target. The human antioxidant α₁-microglobulin (A1M) is a plasma and tissue protein with heme-binding, radical-scavenging and reductase activities. A1M can be internalized by cells, localized to the mitochondria and protect mitochondrial function. Due to its small size, A1M is filtered from the blood into the glomeruli, and taken up by the renal tubular epithelial cells. A1M has previously been described to reduce renal damage in animal models of preeclampsia, radiotherapy and rhabdomyolysis, and is proposed as a pharmacological agent for the treatment of kidney damage. In this paper, we examined the in vitro protective effects of recombinant human A1M (rA1M) in human proximal tubule epithelial cells. Moreover, rA1M was found to protect against heme-induced cell-death both in primary cells (RPTEC) and in a cell-line (HK-2). Expression of stress-related genes was upregulated in both cell cultures in response to heme exposure, as measured by qPCR and confirmed with in situ hybridization in HK-2 cells, whereas co-treatment with rA1M counteracted the upregulation. Mitochondrial respiration, analyzed with the Seahorse extracellular flux analyzer, was compromised following exposure to heme, but preserved by co-treatment with rA1M. Finally, heme addition to RPTE cells induced an upregulation of the endogenous cellular expression of A1M, via activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)-pathway. Overall, data suggest that A1M/rA1M protects against stress-induced damage to tubule epithelial cells that, at least partly, can be attributed to maintaining mitochondrial function.

iTRAQ-Based Comparative Proteomics Analysis of Urolithiasis Rats Induced by Ethylene Glycol

Nephrolithiasis is a frequent chronic urological condition with a high prevalence and recurrence rate. Proteomics studies on urolithiasis rat models are highly important in characterizing the pathophysiology of kidney stones and identifying potential approaches for preventing and treating kidney stones. The isobaric tags for relative and absolute quantification (iTRAQ) were performed to identify differentially expressed proteins (DEPs) in the kidney between urolithiasis rats and control rats. The results showed that 127 DEPs (85 upregulated and 42 downregulated) were identified in urolithiasis and control rats. The functions of DEPs were predicted by Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and protein-protein interaction (PPI) network analysis. The expression of four upregulated proteins (Tagln, Akr1c9, Spp1, and Fbn1) and four downregulated proteins (Hbb, Epb42, Hmgcs2, and Ca1) were validated by parallel reaction monitoring (PRM). Proteomics studies of ethylene glycol-induced urolithiasis rat models using iTRAQ and PRM helped to elucidate the molecular mechanism governing nephrolithiasis and to identify candidate proteins for the treatment of kidney stones.

Mitochondria in Sepsis-Induced AKI

AKI is a common clinical condition associated with the risk of developing CKD and ESKD. Sepsis is the leading cause of AKI in the intensive care unit (ICU) and accounts for nearly half of all AKI events. Patients with AKI who require dialysis have an unacceptably high mortality rate of 60%-80%. During sepsis, endothelial activation, increased microvascular permeability, changes in regional blood flow distribution with resulting areas of hypoperfusion, and hypoxemia can lead to AKI. No effective drugs to prevent or treat human sepsis-induced AKI are currently available. Recent research has identified dysfunction in energy metabolism as a critical contributor to the pathogenesis of AKI. Mitochondria, the center of energy metabolism, are increasingly recognized to be involved in the pathophysiology of sepsis-induced AKI and mitochondria could serve as a potential therapeutic target. In this review, we summarize the potential role of mitochondria in sepsis-induced AKI and identify future therapeutic approaches that target mitochondrial function in an effort to treat sepsis-induced AKI.

Changing expression profiles of long non-coding RNAs, mRNAs and circular RNAs in ethylene glycol-induced kidney calculi rats

Background

To explore long non-coding RNA (lncRNA), mRNA and circular RNA (circRNA) expression profiles and their biological functions in the pathogenesis of kidney stones in ethylene glycol-induced urolithiasis rats.

Results

The expression of 1440 lncRNAs, 2455 mRNAs and 145 circRNAs was altered in the kidneys of urolithiasis rats. GO and KEGG biological pathway analysis were performed to predict the functions of differentially expressed lncRNAs, circRNAs and co-expressed potential targeting genes. Co-expression networks of lncRNA-mRNA and circRNA-miRNA were constructed based on correlation analysis between differentially expressed RNAs. mRNAs coexpressed with lncRNAs were involved in many kidney diseases, e.g., Ephb6 was associated with the reabsorption ability of the kidney. Arl5b was associated with the dynamic changes in the podocyte foot process in podocyte injury. miRNAs co-expressed with circRNAs, such as rno-miR-138-5p and rno-miR-672-5p, have been proven to be functional in hypercalciuria urolithiasis.

Conclusion

The expression profile provided a systematic perspective on the potential functions of lncRNAs and circRNAs in the pathogenesis of kidney stones. Differentially expressed lncRNAs and circRNAs might serve as treatment targets for kidney stones.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5052-8) contains supplementary material, which is available to authorized users.

Effect of hyperbaric oxygenation on the expression of glutathione peroxidase 4 and lactoperoxidase genes in the lung of isogenic mice after ischemia/reperfusion injury in the small bowel

PURPOSE

To evaluate the effect of hyperbaric oxygenation (HBO) on the expression of the genes antioxidant glutathione peroxidase 4 (Gpx4) and lactoperoxidase (Lpo) in the lung of mice subjected to intestinal ischemia and reperfusion (IIR).

METHODS

Control group (CG) in which were subjected to anesthesia, laparotomy and observation for 120 minutes; an ischemia and reperfusion group (IRG) subjected to anesthesia, laparotomy, small bowel ischemia for 60 minutes and reperfusion for 60 minutes; and three groups treated with HBO during ischemia (HBOG + I), during reperfusion (HBOG + R) and during ischemia and reperfusion (HBOG + IR). Studied 84 genes of oxidative stress by the method (RT-qPCR). Genes with expression levels three times below or above the threshold cycle were considered significantly hypoexpressed or hyperexpressed, respectively (Student's t-test p<0.05).

RESULTS

Gpx4 and Lpo were hiperexpressed on IRG, showing a correlation with these genes with lung oxidative stress. Treated with HBO, there was a significant reduction on genic expression on HBOG+I.

CONCLUSION

Hyperbaric oxygenation showed to be associated with decreased expression of these antioxidant genes, suggesting a beneficial effect on the mechanism of pulmonary oxidative stress whenever applied during the ischemia.

Mitochondrial energetics in the kidney

The kidney requires a large number of mitochondria to remove waste from the blood and regulate fluid and electrolyte balance. Mitochondria provide the energy to drive these important functions and can adapt to different metabolic conditions through a number of signalling pathways (for example, mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) pathways) that activate the transcriptional co-activator peroxisome proliferator-activated receptor-γ co-activator 1α (PGC1α), and by balancing mitochondrial dynamics and energetics to maintain mitochondrial homeostasis. Mitochondrial dysfunction leads to a decrease in ATP production, alterations in cellular functions and structure, and the loss of renal function. Persistent mitochondrial dysfunction has a role in the early stages and progression of renal diseases, such as acute kidney injury (AKI) and diabetic nephropathy, as it disrupts mitochondrial homeostasis and thus normal kidney function. Improving mitochondrial homeostasis and function has the potential to restore renal function, and administering compounds that stimulate mitochondrial biogenesis can restore mitochondrial and renal function in mouse models of AKI and diabetes mellitus. Furthermore, inhibiting the fission protein dynamin 1-like protein (DRP1) might ameliorate ischaemic renal injury by blocking mitochondrial fission.

Organizers and activators: Cytosolic Nox proteins impacting on vascular function

NADPH oxidases of the Nox family are important enzymatic sources of reactive oxygen species (ROS) in the cardiovascular system. Of the 7 members of the Nox family, at least three depend for their activation on specific cytosolic proteins. These are p47phox and its homologue NoxO1 and p67phox and its homologue NoxA1. Also the Rho-GTPase Rac is important but as this protein has many additional functions, it will not be covered here. The Nox1 enzyme is preferentially activated by the combination of NoxO1 with NoxA1, whereas Nox2 gains highest activity with p47phox together with p67phox. As p47phox, different to NoxO1 contains an auto inhibitory region it has to be phosphorylated prior to complex formation. In the cardio-vascular system, all cytosolic Nox proteins are expressed but the evidence for their contribution to ROS production is not well established. Most data have been collected for p47phox, whereas NoxA1 has basically not yet been studied. In this article the specific aspects of cytosolic Nox proteins in the cardiovascular system with respect to Nox activation, their expression and their importance will be reviewed. Finally, it will be discussed whether cytosolic Nox proteins are suitable pharmacological targets to tamper with vascular ROS production.

Understanding and Controlling Sialylation in a CHO Fc-Fusion Process

A Chinese hamster ovary (CHO) bioprocess, where the product is a sialylated Fc-fusion protein, was operated at pilot and manufacturing scale and significant variation of sialylation level was observed. In order to more tightly control glycosylation profiles, we sought to identify the cause of variability. Untargeted metabolomics and transcriptomics methods were applied to select samples from the large scale runs. Lower sialylation was correlated with elevated mannose levels, a shift in glucose metabolism, and increased oxidative stress response. Using a 5-L scale model operated with a reduced dissolved oxygen set point, we were able to reproduce the phenotypic profiles observed at manufacturing scale including lower sialylation, higher lactate and lower ammonia levels. Targeted transcriptomics and metabolomics confirmed that reduced oxygen levels resulted in increased mannose levels, a shift towards glycolysis, and increased oxidative stress response similar to the manufacturing scale. Finally, we propose a biological mechanism linking large scale operation and sialylation variation. Oxidative stress results from gas transfer limitations at large scale and the presence of oxygen dead-zones inducing upregulation of glycolysis and mannose biosynthesis, and downregulation of hexosamine biosynthesis and acetyl-CoA formation. The lower flux through the hexosamine pathway and reduced intracellular pools of acetyl-CoA led to reduced formation of N-acetylglucosamine and N-acetylneuraminic acid, both key building blocks of N-glycan structures. This study reports for the first time a link between oxidative stress and mammalian protein sialyation. In this study, process, analytical, metabolomic, and transcriptomic data at manufacturing, pilot, and laboratory scales were taken together to develop a systems level understanding of the process and identify oxygen limitation as the root cause of glycosylation variability.

Dysregulation of renal microRNA expression after deep hypothermic circulatory arrest in rats

OBJECTIVES

Acute kidney injury (AKI) is a severe complication of cardiopulmonary bypass-deep hypothermic circulatory arrest (DHCA) surgery. Non-coding microRNAs (miRNAs) are considered as key players in kidney physiology and pathology. However, whether they are implicated in DHCA-induced AKI at the early stage post-surgery is less studied, and requires for further investigation.

METHODS

In this study, kidney tissues were removed at 2 h post-surgery from Sprague-Dawley rats that underwent a 60-min DHCA (18°C), with samples from sham-operated rats as control. Renal RNA isolates were analysed with Affymetrix miRNA microarray 4.0 containing 728 mature rat miRNA probes.

RESULTS

Seventy-one miRNAs were down-regulated and 4 were up-regulated in the kidneys of DHCA rats [log2 (fold change, FC) > 1, P < 0.05]. Novel differentially expressed miRNAs, such as miRNA-3068, miR-1949 and miR-3473, were identified in the injured kidney tissues. Putative target genes of the down-regulated miR-30b-5p, miR-199a-5p, miR-148b-3p and miR-10a-3p were subjected to analyses of gene ontology (GO) categories and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The results indicated that these miRNAs targeted a large set of genes involved in essential biological processes related to AKI pathogenesis, such as apoptotic process and response to hypoxia, as well as genes implicated in critical signalling pathways, such as chemokine, lysosome and FoxO signalling pathways (false discovery rate-corrected, P < 0.05).

CONCLUSIONS

The identified 75 differentially expressed miRNAs hold the potential to serve as novel early markers and novel therapeutic targets for DHCA-AKI.

[Urinary protein detection by iTRAQ® associated with renal transplant complications and its modification with therapy]

BACKGROUND

After renal transplant, surgical, infection complications, as well as graft rejection may occur; early detection through non-invasive markers is the key to change therapy and avoid biopsy.

OBJECTIVE

The aime of the study is to determine urine protein profiles in patients undergoing renal transplant with complications and detect its variation when therapy is modified.

MATERIAL AND METHODS

Urine samples were collected from patients prior the transplant and various postoperative stages. Urinary protein profiles were obtained by peptide labeling using isobaric isotopes for relative quantification (iTRAQ(®)).

RESULTS

A total of 22 patients were included, of whom 12 developed post-transplant complication: 2 with graft rejection (one male and one female) and 10 (6 males and 4 females) in the group of post-transplant infections. Using iTRAQ(®) 15/345 and 28/113 proteins were identified and fulfilled the acceptance criteria, in graft rejection and post-transplant infections group, respectively.

CONCLUSIONS

Albumin was the only protein found in both groups, the remaining proteins were different. The 5 proteins with higher scores in graft rejection were: alpha-1-microglobulin, 5'-nucleotidase cytosolic III, retinol-binding protein 4, membrane protein palmitoylated 4, and serine carboxypeptidase, while post-transplant infections were: mitochondrial acetyl-coenzyme A synthetase, putative adenosyl homocysteinase 2, zinc finger protein GLIS1, putative protein FAM157B, and zinc finger protein 615. It remains to elucidate the involvement of each of these in patients with renal transplantation.