Ceria nanoparticles ameliorate renal fibrosis by modulating the balance between oxidative phosphorylation and aerobic glycolysis

Background and aims Renal fibrosis is the common outcome in all progressive forms of chronic kidney disease. Unfortunately, the pathogenesis of renal fibrosis remains largely unexplored, among which metabolic reprogramming plays an extremely crucial role in the evolution of renal fibrosis. Ceria nanoparticles (CeNP-PEG) with strong ROS scavenging and anti-inflammatory activities have been applied for mitochondrial oxidative stress and inflammatory diseases. The present study aims to determine whether CeNP-PEG has therapeutic value for renal fibrosis. Methods The unilateral ureteral obstructive fibrosis model was used to assess the therapeutic effects in vivo. Transforming growth factor beta1-induced epithelial-to-mesenchymal transition in HK-2 cells was used as the in vitro cell model. The seahorse bioscience X96 extracellular flux analyzer was used to measure the oxygen consumption rate and extracellular acidification rate. Results In the present study, CeNP-PEG treatment significantly ameliorated renal fibrosis by increased E-cadherin protein expression, and decreased α-SMA, Vimentin and Fibronectin expression both in vitro and in vivo. Additionally, CeNP-PEG significantly reduced the ROS formation and improved the levels of mitochondrial ATP. The seahorse analyzer assay demonstrated that the extracellular acidification rate markedly decreased, whereas the oxygen consumption rate markedly increased, in the presence of CeNP-PEG. Furthermore, the mitochondrial membrane potential markedly enhanced, hexokinase 1 and hexokinase 2 expression significantly decreased after treatment with CeNP-PEG. Conclusions CeNP-PEG can block the dysregulated metabolic status and exert protective function on renal fibrosis. This may provide another therapeutic option for renal fibrosis. Graphical Abstract

Olaparib: A Clinically Applied PARP Inhibitor Protects from Experimental Crohn’s Disease and Maintains Barrier Integrity by Improving Bioenergetics through Rescuing Glycolysis in Colonic Epithelial Cells

Crohn’s disease (CD) is an inflammatory disorder of the intestines characterized by epithelial barrier dysfunction and mucosal damage. The activity of poly(ADP-ribose) polymerase-1 (PARP-1) is deeply involved in the pathomechanism of inflammation since it leads to energy depletion and mitochondrial failure in cells. Focusing on the epithelial barrier integrity and bioenergetics of epithelial cells, we investigated whether the clinically applied PARP inhibitor olaparib might improve experimental CD. We used the oral PARP inhibitor olaparib in the 2,4,6-trinitrobenzene sulfonic acid- (TNBS-) induced mouse colitis model. Inflammatory scoring, cytokine levels, colon histology, hematological analysis, and intestinal permeability were studied. Caco-2 monolayer culture was utilized as an epithelial barrier model, on which we used qPCR and light microscopy imaging, and measured impedance-based barrier integrity, FITC-dextran permeability, apoptosis, mitochondrial oxygen consumption rate, and extracellular acidification rate. Olaparib reduced the inflammation score, the concentration of IL-1β and IL-6, enhanced the level of IL-10, and decreased the intestinal permeability in TNBS-colitis. Blood cell ratios, such as lymphocyte to monocyte ratio, platelet to lymphocyte ratio, and neutrophil to lymphocyte ratio were improved. In H2O2-treated Caco-2 monolayer, olaparib decreased morphological changes, barrier permeability, and preserved barrier integrity. In oxidative stress, olaparib enhanced glycolysis (extracellular acidification rate), and it improved mitochondrial function (mitochondrial coupling efficiency, maximal respiration, and spare respiratory capacity) in epithelial cells. Olaparib, a PARP inhibitor used in human cancer therapy, improved experimental CD and protected intestinal barrier integrity by preventing its energetic collapse; therefore, it could be repurposed for the therapy of Crohn’s disease.

Evidence for a Physiological Mitochondrial Angiotensin II System in the Kidney Proximal Tubules

The present study tested the hypotheses that overexpression of an intracellular Ang II (angiotensin II) fusion protein, mito-ECFP/Ang II, selectively in the mitochondria of mouse proximal tubule cells induces mitochondrial oxidative and glycolytic responses and elevates blood pressure via the Ang II/AT 1a receptor/superoxide/NHE3 (the Na + /H + exchanger 3)-dependent mechanisms. A PT-selective, mitochondria-targeting adenoviral construct encoding Ad-sglt2-mito-ECFP/Ang II was used to test the hypotheses. The expression of mito-ECFP/Ang II was colocalized primarily with Mito-Tracker Red FM in mouse PT cells or with TMRM in kidney PTs. Mito-ECFP/Ang II markedly increased oxygen consumption rate as an index of mitochondrial oxidative response (69.5%; P <0.01) and extracellular acidification rate as an index of mitochondrial glycolytic response (34%; P <0.01). The mito-ECFP/Ang II–induced oxygen consumption rate and extracellular acidification rate responses were blocked by AT 1 blocker losartan ( P <0.01) and a mitochondria-targeting superoxide scavenger mito-TEMPO ( P <0.01). By contrast, the nonselective NO inhibitor L-NAME alone increased, whereas the mitochondria-targeting expression of AT 2 receptors (mito-AT 2 /GFP) attenuated the effects of mito-ECFP/Ang II ( P <0.01). In the kidney, overexpression of mito-ECFP/Ang II in the mitochondria of the PTs increased systolic blood pressure 12±3 mm Hg ( P <0.01), and the response was attenuated in PT-specific PT- Agtr1a −/− and PT- Nhe3 −/− mice ( P <0.01). Conversely, overexpression of AT 2 receptors selectively in the mitochondria of the PTs induced natriuretic responses in PT- Agtr1a −/− and PT- Nhe3 −/− mice ( P <0.01). Taken together, these results provide new evidence for a physiological role of PT mitochondrial Ang II/AT 1a /superoxide/NHE3 and Ang II/AT 2 /NO/NHE3 signaling pathways in maintaining blood pressure homeostasis.

Identification of ASCT1 As a Candidate Molecule Enhancing Antioxidant Activity in Primary Human AML Cells

Introduction: Recent studies have shown that the specific alteration of metabolic pathways are involved in the regulation of function of normal hematopoietic stem cells (HSCs) and leukemic stem cells (LSCs) in acute myeloid leukemia (AML). However, little is known about the features of metabolic activity in human HSCs and LSCs. To reveal the metabolic pathway alterations in primary AML cells, we performed the comprehensive metabolome analysis by comparing normal human CD34+ hematopoietic stem/progenitor cells (HSPCs)(n=5) and CD34+ primitive AML cells containing LSCs (n=16) using highly sensitive CE-tandem mass spectrometry. Method: Metabolome analysis Metabolites were extracted from primitive CD34+ AML cells (n=16) and normal CD34+ bone marrow cells (n=4) and cord blood cells (n=1). Metabolome analysis was conducted by the C-SCOPE package of HMT using capillary electrophoresis time-of-flight mass spectrometry (CE-TOFMS) for cation analysis, and capillary electrophoresis-tandem mass spectrometry (CE-MS/MS) for anion analysis. 116 metabolites were targeted for analysis in this study. Oxygen consumption rates and extracellular acidification rate O2 consumption rates (OCR) and extracellular acidification rate (ECAR) were measured by the Seahorse XF96 extracellular flux analyzer. Three replicate wells of 400,000 leukemic or normal cells per well were seeded in 96-well XF96 well plates coated with BD Cell-Tak (BD Biosciences) in serum-free unbuffered DMEM. Analyses were performed both at basal conditions and after injection of OLI (1 mg/ml), FCCP (1 mM), Antimycin A (5 mM). Result: We detected 101 metabolites involved in central carbon and energy metabolism. In glucose metabolism, the level of lactate, an end-product of aerobic glycolysis, were lower in CD34+ AML cells than normal HSPCs, whereas the level of pyruvate, a precursor of lactate, was not different. Thus, CD34+ AML cells had a significantly high pyruvate/lactate ratio as compared to normal HSPCs, suggesting that aerobic respiration is preferentially utilized in CD34+ AML cells. To confirm this observation, we directly measured the O2 consumption rate (OCR) and extracellular acidification rate (ECAR) of CD34+ AML cells (n=4) and normal HSPCs (n=5) by XF96 extracellular flux analyzer. OCR reflects the activity of aerobic respiration, whereas ECAR reflects lactate generation and correlates with anaerobic respiration activity. Therefore, OCR/ECAR ratio is a good index for the discrimination of aerobic and anaerobic respiration pattern. We found that the OCR/ECAR ratio of CD34+ primitive AML cells was significantly high as compared to that of HSPCs, suggesting that CD34+ AML cells predominantly utilized aerobic respiration. Although the aerobic respiration resulted in the production of reactive oxygen species (ROS), the intracellular ROS level was not different between CD34+ AML (n=7) cells and normal HSPCs (n=3), suggesting that the antioxidant activity should be strongly enhanced in CD34+ AML cells. Consistent with the observation, we found that CD34+ AML cells had a much higher level of glutathione (GSH), a primary intracellular antioxidant, than normal HSPCs. To clarify the molecular mechanisms how CD34+ primitive AML cells could maintain high GSH level, we analyzed the expression of cysteine transporters, because cysteine uptake is the rate-limiting step of GSH synthesis. In human, three amino acid transporters including ASCT1, ASC1 and xCT are known as cystine/cysteine transporters. Interestingly, ASCT1 was significantly highly expressed in CD34+ AML cells (n=10) as compared to normal CD34+ HSPCs (n=3). Of note, normal CD34+CD38- HSCs completely lacked ASCT1 expression, whereas CD34+CD38-LSCs expressed at a high level, indicating the possibility that the high expression of ASCT1 should be a LSC specific machinery for enhanced GSH synthesis. Thus, human AML cells predominantly utilize aerobic respiration that is supported by a high level of GSH, and AML specific ASCT1 expression presumably contributes to the high level of GSH. These data suggest that ASCT1 should be a promising molecule to specifically target AML stem/progenitor cells. Disclosures Akashi: Celgene: Research Funding; Astellas Pharma: Research Funding; Shionogi & Co., Ltd: Research Funding; Asahi Kasei Pharma Corporation: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Bristol Meyers Squibb: Research Funding; Kyowa Hakko Kirin: Consultancy, Research Funding; Sunitomo Dainippon Pharma: Consultancy.

Abstract 117: Poly (i:c) Attenuates Myocardial I/R Injury via Glycolytic Dependent Yap Activation and by Suppression of MiR-143

Glycolytic metabolism plays a critical role in ischemia/reperfusion (I/R) injury. The Yes associated protein (YAP) is a core effector of the Hippo pathway that regulates cell proliferation and apoptosis. We observed that poly (I:C) enhanced glycolysis and Yap activation in neonatal cardiomyocytes. This study investigated whether poly (I:C) will attenuate myocardial I/R injury via a glycolytic dependent mechanism. Mice (n=6/group) were treated with poly (I:C) (10 μg/25g body weight) one h before the hearts were subjected to ischemia (45 min) followed by reperfusion (24 h). Sham surgery served as sham control. Poly (I:C) treatment significantly reduced infarct size by 35% and enhanced EF% by 20.5% and FS% by 24.9% compared with I/R group. The expression of miR-143 was markedly reduced and Yap levels were significantly increased in poly (I:C) treated hearts. In vitro data show that poly (I:C) treatment enhanced extracellular acidification rate (ECAR) and lactate production in HL-1 cardiomyocytes. In vivo inhibition of hexokinase 2 abolished poly (I:C)-induced cardioprotection. To determine the role of miR-143 in regulation of glycolysis, we transfected HL-1 cardiomyocytes with anti-miR-143 mimics before the cells were subjected to hypoxia/reoxygenation. We observed that anti-miR-143 significantly enhanced cell viability, reduced LDH release, and increased hexokinase 2 levels and extracellular acidification rate (ECAR). To determine whether suppression of miR-143 will induce protection against myocardial I/R injury, we loaded anti-miR-143 on exosomes (Exo-antimiR-143) by transection of bone marrow stromal cells with anti-miR-143 mimics. MiR-control mimics served as control (Exo-miR-control). Exo-miR-143 was delivered into the myocardium through the right carotid artery immediately before the hearts (n=6/group) were subjected to I/R. We observed that delivery of Exo-antimiR-143 significantly enhanced EF% by 20.5% and FS% by 26.4% and decreased infarct size by 42.2%, when compared with untreated I/R group. Delivery of Exo-miR-control did not alter I/R-induced cardiac dysfunction and infarct size. We conclude that poly (I:C) attenuates myocardial I/R injury via glycolytic dependent YAP mechanism and suppression of miR-143 expression.