ABSTRACT
Chronic ischemia triggers senescence in renal tubules and at least partly mediates kidney dysfunction and damage through a p16Ink4a -related mechanism. We previously showed that mesenchymal stromal/stem cells (MSCs) delivered systemically do not effectively decrease cellular senescence in stenotic murine kidneys. We hypothesized that selective MSC targeting to injured kidneys using an anti-KIM1 antibody (KIM-MSC) coating would enhance their ability to abrogate cellular senescence in murine renal artery stenosis (RAS). KIM-MSC were injected into transgenic INK-ATTAC mice, which are amenable for selective eradication of p16Ink4a+ cells, 4 weeks after induction of unilateral RAS. To determine whether KIM-MSC abolish p16Ink4a -dependent cellular senescence, selective clearance of p16Ink4a+ cells was induced in a subgroup of RAS mice using AP20187 over 3 weeks prior to KIM-MSC injection. Two weeks after KIM-MSC aortic injection, renal senescence, function, and tissue damage were assessed. KIM-MSC delivery decreased gene expression of senescence and senescence-associated secretory phenotype factors, and improved micro-MRI-derived stenotic-kidney glomerular filtration rate and perfusion. Renal fibrosis and tubular injury also improved after KIM-MSC treatment. Yet, their efficacy was slightly augmented by prior elimination of p16Ink4a+ senescent cells. Therefore, selective targeting of MSC to the injured kidney markedly improves their senolytic potency in murine RAS, despite incomplete eradication of p16+ cells. KIM-MSC may constitute a useful therapeutic strategy in chronic renal ischemic injury.
Subject(s)
Mesenchymal Stem Cells , Renal Artery Obstruction , Animals , Cellular Senescence , Cyclin-Dependent Kinase Inhibitor p16/metabolism , Ischemia/metabolism , Kidney/metabolism , Mesenchymal Stem Cells/metabolism , Mice , Mice, Transgenic , Renal Artery Obstruction/metabolismABSTRACT
INTRODUCTION: Obesity is a health burden that impairs cellular processes. Mesenchymal stem/stromal cells (MSCs) are endowed with reparative properties and can ameliorate renal injury. Obesity impairs human MSC function in-vitro, but its effect on their in-vivo reparative potency remains unknown. SUBJECTS AND METHODS: Abdominal adipose tissue-derived MSC were harvested from patients without ('lean') or with obesity ('obese') (body mass index <30 or ≥30 kg/m2, respectively) during kidney donation or bariatric surgery, respectively. MSC (5 × 105/200 µL) or vehicle were then injected into 129S1 mice 2 weeks after renal artery stenosis (RAS) or sham surgery (n = 8/group). Two weeks later, mice underwent magnetic resonance imaging to assess renal perfusion and oxygenation in-vivo, and kidneys then harvested for ex-vivo studies. RESULTS: Similar numbers of lean and obese-MSCs engrafted in stenotic mouse kidneys. Vehicle-treated RAS mice had reduced stenotic-kidney cortical and medullary perfusion and oxygenation. Lean (but not obese) MSC normalized ischemic kidney cortical perfusion, whereas both effectively mitigated renal hypoxia. Serum creatinine and blood pressure were elevated in RAS mice and lowered only by lean-MSC. Both types of MSCs alleviated stenotic-kidney fibrosis, but lean-MSC more effectively than obese-MSC. MSC senescence-associated beta-gal activity, and gene expression of p16, p21, and vascular endothelial growth factor correlated with recipient kidney perfusion and tissue injury, linking MSC characteristics with their in-vivo reparative capacity. DISCUSSION: Human obesity impairs the reparative properties of adipose-tissue-derived MSCs, possibly by inducing cellular senescence. Dysfunction and senescence of the endogenous MSC repair system in patients with obesity may warrant targeting interventions to restore MSC vitality.
Subject(s)
Mesenchymal Stem Cells , Renal Artery Obstruction , Animals , Humans , Kidney/pathology , Mesenchymal Stem Cells/metabolism , Mice , Obesity/metabolism , Renal Artery Obstruction/metabolism , Renal Artery Obstruction/pathology , Vascular Endothelial Growth Factor AABSTRACT
Tumor necrosis factor (TNF)-α-induced gene/protein (TSG)-6 regulates the immunomodulatory properties of mesenchymal stem cells (MSCs), but its ability to protect the ischemic kidney is unknown. In a swine model of renal artery stenosis (RAS) and metabolic syndrome (MetS), we assessed the contribution of TSG-6 produced by MSCs to their immunomodulatory properties. Pigs were studied after 16 wk of diet-induced MetS and unilateral RAS and were either untreated or treated 4 wk earlier with intrarenal autologous adipose tissue-derived MSCs (n = 6 each). Lean, MetS, and RAS sham animals served as controls. We studied renal function in vivo (using computed tomography) and kidney histopathology and macrophage phenotype ex vivo. In vitro, TSG-6 levels were also measured in conditioned media of human MSCs incubated with TNF-α and levels of the tubular injury marker lactate dehydrogenase in conditioned media after coculturing macrophages with injured human kidney 2 (HK-2) cells with or without TSG-6. The effects of TSG-6 on macrophage phenotype (M1/M2), adhesion, and migration were also determined. MetS + RAS showed increased M1 macrophages and renal vein TNF-α levels. After MSC delivery, renal vein TSG-6 increased and TNF-α decreased, the M1-to-M2 ratio decreased, renal function improved, and fibrosis was alleviated. In vitro, TNF-α increased TSG-6 secretion by human MSCs. TSG-6 decreased lactate dehydrogenase release from injured HK-2 cells, increased expression of macrophage M2 markers, and reduced M1 macrophage adhesion and migration. Therefore, TSG-6 released from MSCs may decrease renal tubular cell injury, which is associated with regulating macrophage function and phenotype. These observations suggest that TSG-6 is endowed with renoprotective properties.NEW & NOTEWORTHY Tumor necrosis factor-α-induced gene/protein (TSG)-6 regulates the immunomodulatory properties of MSCs, but its ability to protect the ischemic kidney is unknown. In pigs with renal artery stenosis, we show that MSC delivery increased renal vein TSG-6, decreased kidney inflammatory macrophages, and improved renal function. In vitro, TSG-6 decreased inflammatory macrophages and tubular cell injury. Therefore, TSG-6 released from MSCs may decrease renal tubular cell injury, which is associated with regulating macrophage function and phenotype.
Subject(s)
Epithelial Cells/cytology , Macrophages/cytology , Mesenchymal Stem Cells/cytology , Phenotype , Renal Artery Obstruction/pathology , Animals , Coculture Techniques , Cytokines/metabolism , Humans , Kidney/metabolism , Kidney/pathology , Metabolic Syndrome/drug therapy , Metabolic Syndrome/metabolism , Protective Agents/pharmacology , Renal Artery Obstruction/metabolism , Swine , Tumor Necrosis Factor-alpha/metabolismABSTRACT
Scattered tubular-like cells (STCs), dedifferentiated renal tubular epithelial cells, contribute to renal self-healing, but severe injury might blunt their effectiveness. We hypothesized that ischemic renovascular disease (RVD) induces senescence in STC and impairs their reparative potency. CD24+/CD133+ STCs were isolated from swine kidneys after 16 weeks of RVD or healthy controls. To test their reparative capabilities in injured kidneys, control or RVD-STC (5×105) were prelabeled and injected into the aorta of 2 kidneys, 1-clip (2k,1c) mice 2 weeks after surgery. Murine renal function and oxygenation were studied in vivo 2 weeks after injection using micro-magnetic resonance imaging, and fibrosis, tubulointerstitial injury, capillary density, and expression of profibrotic and inflammatory genes ex vivo. STC isolated from swine RVD kidneys showed increased gene expression of senescence and senescence-associated secretory phenotype markers and positive SA-ß-gal staining. Delivery of normal pig STCs in 2k,1c mice improved murine renal perfusion, blood flow, and glomerular filtration rate, and downregulated profibrotic and inflammatory gene expression. These renoprotective effects were blunted using STC harvested from RVD kidneys, which also failed to attenuate hypoxia, fibrosis, tubular injury, and capillary loss in injured mouse 2k,1c kidneys. Hence, RVD may induce senescence in endogenous STC and impair their reparative capacity. These observations implicate cellular senescence in the pathophysiology of ischemic kidney disease and support senolytic therapy to permit self-healing of senescent kidneys.
Subject(s)
Cellular Senescence/physiology , Kidney/pathology , Renal Artery Obstruction/pathology , Renal Insufficiency/pathology , Animals , Cells, Cultured , Female , Fibrosis/metabolism , Fibrosis/pathology , Kidney/metabolism , Mice , Renal Artery Obstruction/metabolism , Renal Insufficiency/metabolism , SwineABSTRACT
Renal artery stenosis is a common condition in patients with coronary or peripheral vascular disease where the renin angiotensin aldosterone system (RAAS) is overactivated. In this context, there is a narrowing of the renal arteries that stimulate an increase in the expression and release of renin, the rate-limiting protease in RAAS. The resulting rise in renin expression is a known driver of renovascular hypertension, frequently associated with kidney injury and end organ damage. Thus, there is a great interest in developing novel treatments for this condition. The molecular and cellular mechanism of renin control in renal artery stenosis is not fully understood and warrants further investigation. To induce renal artery stenosis in mice, a modified 2 kidney 1 clip (2K1C) Goldblatt mouse model was developed. The right kidney was stenosed in wild type mice and sham operated mice were used as control. After renal artery stenosis, we determined renin expression and kidney injury. Kidneys were harvested, and fresh cortices were used to determine protein and mRNA expression of renin. This animal model is reproducible and can be used to study pathophysiological responses, molecular and cellular pathways involved in renovascular hypertension and kidney injury.
Subject(s)
Acute Kidney Injury/diagnosis , Disease Models, Animal , Kidney/surgery , Lipocalin-2/metabolism , Renal Artery Obstruction/physiopathology , Renal Artery/physiopathology , Renin/metabolism , Acute Kidney Injury/etiology , Acute Kidney Injury/metabolism , Animals , Blood Pressure , Female , Kidney/metabolism , Male , Mice , Mice, Inbred C57BL , Renal Artery Obstruction/complications , Renal Artery Obstruction/metabolismABSTRACT
Scattered tubular-like cells (STCs) are dedifferentiated surviving tubular epithelial cells that repair neighboring injured cells. Experimental renal artery stenosis (RAS) impairs STC reparative potency by inducing mitochondrial injury, but the exact mechanisms of mitochondrial damage remain unknown. We hypothesized that RAS alters expression of mitochondria-related genes, contributing to mitochondrial structural damage and dysfunction in swine STCs. CD24+/CD133+ STCs were isolated from pig kidneys after 10 wk of RAS or sham (n = 3 each). mRNA sequencing was performed, and nuclear DNA (nDNA)-encoded mitochondrial genes and mitochondrial DNA (mtDNA)-encoded genes were identified. Mitochondrial structure, ATP generation, biogenesis, and expression of mitochondria-associated microRNAs were also assessed. There were 96 nDNA-encoded mitochondrial genes upregulated and 12 mtDNA-encoded genes downregulated in RAS-STCs versus normal STCs. Functional analysis revealed that nDNA-encoded and mtDNA-encoded differentially expressed genes were primarily implicated in mitochondrial respiration and ATP synthesis. Mitochondria from RAS STCs were swollen and showed cristae remodeling and loss and decreased ATP production. Immunoreactivity of the mitochondrial biogenesis marker peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α and expression of the mitochondria-associated microRNAs miR-15a, miR-181a, miR-196a, and miR-296-3p, which target several mtDNA genes, were higher in RAS-STCs compared with normal STCs, suggesting a potential modulation of mitochondria-related gene expression. These results demonstrate that RAS induces an imbalance in mtDNA- and nDNA-mitochondrial gene expression, impairing mitochondrial structure and function in swine STCs. These observations support development of gene gain- and loss-of-function strategies to ameliorate mitochondrial damage and preserve the reparative potency of STCs in patients with renal ischemia.
Subject(s)
Gene Expression , Genes, Mitochondrial , Ischemia/genetics , Kidney/blood supply , Mitochondria/metabolism , Renal Artery Obstruction/metabolism , Animals , Female , Ischemia/metabolism , Organelle Biogenesis , Renal Artery Obstruction/genetics , SwineABSTRACT
BACKGROUND: Mitochondria modulate endothelial cell (EC) function, but may be damaged during renal disease. We hypothesized that the ischemic and metabolic constituents of swine renovascular disease (RVD) induce mitochondrial damage and impair the function of renal artery ECs. METHODS: Pigs were studied after 16 weeks of metabolic syndrome (MetS), renal artery stenosis (RAS), or MetS + RAS, and Lean pigs served as control (n = 6 each). Mitochondrial morphology, homeostasis, and function were measured in isolated primary stenotic-kidney artery ECs. EC functions were assessed in vitro, whereas vasoreactivity of renal artery segments was characterized in organ baths. RESULTS: Lean + RAS and MetS + RAS ECs showed increased mitochondrial area and decreased matrix density. Mitochondrial biogenesis was impaired in MetS and MetS + RAS compared with their respective controls. Mitochondrial membrane potential similarly decreased in MetS, Lean + RAS, and MetS + RAS groups, whereas production of reactive oxygen species increased in MetS vs. Lean, but further increased in both RAS groups. EC tube formation was impaired in MetS, RAS, and MetS + RAS vs. Lean, but EC proliferation and endothelial-dependent relaxation of renal artery segments were blunted in MetS vs. Lean, but further attenuated in Lean + RAS and MetS + RAS. CONCLUSIONS: MetS and RAS damage mitochondria in pig renal artery ECs, which may impair EC function. Coexisting MetS and RAS did not aggravate EC mitochondrial damage in the short time of our in vivo studies, suggesting that mitochondrial injury is associated with impaired renal artery EC function.
Subject(s)
Endothelial Cells/metabolism , Endothelium, Vascular/physiopathology , Hypertension, Renovascular/metabolism , Mitochondria/metabolism , Renal Artery/metabolism , Vasodilation/physiology , Animals , Disease Models, Animal , Endothelial Cells/pathology , Endothelium, Vascular/metabolism , Endothelium, Vascular/pathology , Female , Hypertension, Renovascular/pathology , Hypertension, Renovascular/physiopathology , Membrane Potential, Mitochondrial/physiology , Metabolic Syndrome/metabolism , Metabolic Syndrome/pathology , Mitochondria/pathology , Nitric Oxide Synthase Type III/metabolism , Random Allocation , Reactive Oxygen Species/metabolism , Renal Artery/pathology , Renal Artery/physiopathology , Renal Artery Obstruction/metabolism , Renal Artery Obstruction/pathology , Sus scrofa , Swine , Vascular Endothelial Growth Factor A/metabolismABSTRACT
Background Renal artery stenosis is a common cause of renal ischemia, contributing to the development of chronic kidney disease. To investigate the role of local CD40 expression in renal artery stenosis, Goldblatt 2-kidney 1-clip surgery was performed on hypertensive Dahl salt-sensitive rats (S rats) and genetically modified S rats in which CD40 function is abolished (Cd40mutant). Methods and Results Four weeks following the 2-kidney 1-clip procedure, Cd40mutant rats demonstrated significantly reduced blood pressure and renal fibrosis in the ischemic kidneys compared with S rat controls. Similarly, disruption of Cd40 resulted in reduced 24-hour urinary protein excretion in Cd40mutant rats versus S rat controls (46.2±1.9 versus 118.4±5.3 mg/24 h; P<0.01), as well as protection from oxidative stress, as indicated by increased paraoxonase activity in Cd40mutant rats versus S rat controls (P<0.01). Ischemic kidneys from Cd40mutant rats demonstrated a significant decrease in gene expression of the profibrotic mediator, plasminogen activator inhibitor-1 (P<0.05), and the proinflammatory mediators, C-C motif chemokine ligand 19 (P<0.01), C-X-C Motif Chemokine Ligand 9 (P<0.01), and interleukin-6 receptor (P<0.001), compared with S rat ischemic kidneys, as assessed by quantitative PCR assay. Reciprocal renal transplantation documented that CD40 exclusively expressed in the kidney contributes to ischemia-induced renal fibrosis. Furthermore, human CD40-knockout proximal tubule epithelial cells suggested that suppression of CD40 signaling significantly inhibited expression of proinflammatory and -fibrotic genes. Conclusions Taken together, our data suggest that activation of CD40 induces a significant proinflammatory and -fibrotic response and represents an attractive therapeutic target for treatment of ischemic renal disease.
Subject(s)
CD40 Antigens/metabolism , Ischemia/metabolism , Kidney/blood supply , Kidney/metabolism , Mutation , Renal Artery Obstruction/metabolism , Animals , Blood Pressure , CD40 Antigens/genetics , Cell Line , Disease Models, Animal , Fibrosis , Glomerular Filtration Rate , Humans , Inflammation Mediators/metabolism , Ischemia/genetics , Ischemia/pathology , Ischemia/physiopathology , Kidney/pathology , Kidney/physiopathology , Kidney Tubules, Proximal/metabolism , Kidney Tubules, Proximal/pathology , Male , Oxidative Stress , Plasminogen Activator Inhibitor 1/metabolism , Rats, Inbred Dahl , Renal Artery Obstruction/genetics , Renal Artery Obstruction/pathology , Renal Artery Obstruction/physiopathology , Signal TransductionABSTRACT
BACKGROUND: Scattered tubular-like cells (STCs) proliferate and differentiate to support neighboring injured renal tubular cells during recovery from insults. Renal artery stenosis (RAS) induces renal ischemia and hypertension and leads to loss of kidney function, but whether RAS alters renal endogenous repair mechanisms, such as STCs, remains unknown. We hypothesize that RAS in swine modifies the messenger RNA (mRNA) profile of STCs, blunting their in vitro reparative capacity. METHODS: CD24+/CD133+ STCs were isolated from pig kidneys after 10-weeks of RAS or sham (n = 3 each) and their gene cargo analyzed using high-throughput mRNAseq. Expression profiles for upregulated and downregulated mRNAs in RAS-STCs were functionally interpreted by gene ontology analysis. STC activation was assessed by counting the total number of STCs in pig kidney sections using flow cytometry, whereas cell proliferation was assessed in vitro. RESULTS: Of all expressed genes, 1430 genes were upregulated and 315 downregulated in RAS- versus Normal-STCs. Expression of selected candidate genes followed the same fold change directions as the mRNAseq findings. Genes upregulated in RAS-STCs were involved in cell adhesion, extracellular matrix remodeling, and kidney development, whereas those downregulated in RAS-STCs are related to cell cycle and cytoskeleton. The percentage of STCs from dissociated kidney cells was higher in RAS versus Normal pigs, but their proliferation rate was blunted. CONCLUSIONS: Renal ischemia and hypertension in swine induce changes in the mRNA profile of STCs, associated with increased STC activation and impaired proliferation. These observations suggest that RAS may alter the reparative capacity of STCs.
Subject(s)
Renal Artery Obstruction/genetics , Transcriptome , Animals , Cells, Cultured , Female , Kidney Tubules/cytology , Kidney Tubules/metabolism , Renal Artery Obstruction/metabolism , SwineABSTRACT
OBJECTIVE: Renovascular disease (RVD) produces chronic underperfusion of the renal parenchyma and progressive ischemic injury. Metabolic abnormalities often accompany renal ischemia, and are linked to poorer renal outcomes. However, the mechanisms of injury in kidneys exposed to the ischemic and metabolic components of RVD are incompletely understood. We hypothesized that coexisting renal artery stenosis (RAS) and metabolic syndrome (MetS) would exacerbate mitochondrial damage, aggravating poststenotic kidney injury in swine. METHODS: Domestic pigs were studied after 16 weeks of either standard diet (Lean) or high-fat/high-fructose (MetS) with or without superimposed RAS (nâ=â6 each). Single-kidney renal blood flow (RBF) and glomerular filtration rate (GFR) were assessed in vivo with multidetector-CT, and renal tubular mitochondrial structure, homeostasis and function and renal injury ex vivo. RESULTS: Both RAS groups achieved significant stenosis. Single-kidney RBF and GFR were higher in MetS compared with Lean, but decreased in Lean+RAS and MetS+RAS vs. their respective controls. MetS and RAS further induced changes in mitochondrial structure, dynamics, and function, and their interaction (dietâ×âischemia) decreased matrix density, mitophagy, and ATP production, and lead to greater renal fibrosis. CONCLUSION: Coexisting RAS and MetS synergistically aggravate mitochondrial structural damage and dysfunction, which may contribute to structural injury and dysfunction in the poststenotic kidney. These observations suggest that mitochondrial damage precedes loss of renal function in experimental RVD, and position mitochondria as novel therapeutic targets in these patients.
Subject(s)
Kidney/pathology , Metabolic Syndrome/complications , Mitochondria/pathology , Renal Artery Obstruction/complications , Animals , Female , Glomerular Filtration Rate/physiology , Kidney/metabolism , Metabolic Syndrome/metabolism , Metabolic Syndrome/pathology , Mitochondria/metabolism , Renal Artery Obstruction/metabolism , Renal Artery Obstruction/pathology , Renal Circulation , Sus scrofa , SwineABSTRACT
No disponible
Subject(s)
Humans , Female , Middle Aged , 3-Iodobenzylguanidine/pharmacokinetics , Renal Artery Obstruction/diagnostic imaging , Renal Artery Obstruction/metabolism , Adrenal Glands/physiology , Kidney/diagnostic imaging , Kidney/metabolism , Severity of Illness IndexABSTRACT
BACKGROUND/AIMS: Atherosclerotic renal artery stenosis (ARAS) may cause kidney injury and mitochondrial dysfunction, which is linked to cellular senescence. Elamipretide, a mitochondria-targeted peptide, improves renal function in ARAS, but whether it alleviates senescence is unknown. We hypothesized that elamipretide would reduce senescence stenotic kidney (STK) in ARAS. METHODS: Domestic pigs were randomized to control and unilateral ARAS untreated or treated with subcutaneous elamipretide (5d/wk) for 4 weeks starting after 6 weeks of ARAS or sham (n=6 each). After completion of treatment, STK renal blood flow (RBF) and glomerular filtration rate (GFR) were assessed in-vivo using multi-detector computed-tomography. Renal fibrosis and oxidative stress were analyzed in trichrome- and dihydroethidium-stained slides, respectively. Mitochondrial markers involved in the electrontransport chain (COX4, ATP/ADP ratio), biogenesis (PGC1α, PPARα), dynamics (MFN2, DRP1), and mitophagy (parkin, p62) were measured in the kidney using ELISA, western-blot, and immunohistochemistry. Cellular senescence (senescence-associated ß-galactosidase and heterochromatin foci, phosphorylated-H2AX, and p16/21/53) and senescence-associated secretory phenotype (SASP; PAI-1, MCP-1, TGFß, and TNFα) markers were studied by microscopy, quantitative reverse transcription-polymerase chain reaction, and western-blot. RESULTS: Blood pressure was elevated whereas STK-RBF and GFR were decreased in ARAS pigs, and tissue scarring was increased. ARAS induced STK cellular senescence and accumulated dysfunctional mitochondria, which were associated with cardiolipin loss, upregulated mitochondrial biogenesis, and defective mitophagy. Elamipretide normalized STK-RBF and GFR, alleviated fibrosis and oxidative stress, and restored mitochondrial cardiolipin, biogenesis, and mitophagy in ARAS, but did not change SASP markers, and attenuated only senescenceassociated ß-galactosidase activity and p53 gene expression. CONCLUSION: Mitochondrial protection improved renal function and fibrosis in the ARAS STK, but only partly mitigated cellular senescence. This finding suggests that mitochondrial dysfunction may not be a major determinant of cellular senescence in the early stage of ARAS.
Subject(s)
Cellular Senescence , Kidney/physiology , Mitochondria/metabolism , Renal Artery Obstruction/pathology , Animals , Cardiolipins/metabolism , Cellular Senescence/drug effects , Creatinine/blood , Diet, High-Fat , Disease Models, Animal , Female , Fibrosis , Glomerular Filtration Rate , Kidney/pathology , Mitochondria/drug effects , Mitophagy/drug effects , Oligopeptides/pharmacology , Oligopeptides/therapeutic use , Oxidative Stress/drug effects , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Renal Artery Obstruction/drug therapy , Renal Artery Obstruction/metabolism , Renal Circulation/drug effects , Swine , Tumor Suppressor Protein p53/metabolism , Ubiquitin-Protein Ligases/metabolismSubject(s)
3-Iodobenzylguanidine/pharmacokinetics , Kidney/diagnostic imaging , Kidney/metabolism , Radiopharmaceuticals/pharmacokinetics , Renal Artery Obstruction/diagnostic imaging , Renal Artery Obstruction/metabolism , Adrenal Glands/physiology , Female , Humans , Middle Aged , Severity of Illness IndexABSTRACT
BACKGROUND: The collateral circulation is important in maintenance of blood supply to the ischemic kidney distal to renal artery stenosis (RAS). Obesity metabolic syndrome (MetS) preserves renal blood flow (RBF) in the stenotic kidney, but whether this is related to an increase of collateral vessel growth is unknown. We hypothesized that MetS increased collateral circulation around the renal artery. METHODS: Twenty-one domestic pigs were randomly divided into unilateral RAS fed an atherogenic (high-fat/high-fructose, MetS-RAS) or standard diet, or controls (n = 7 each). RBF, glomerular filtration rate (GFR), and the peristenotic collateral circulation were assessed after 10 weeks using multidetector computed tomography (CT) and the intrarenal microcirculation by micro-CT. Vascular endothelial growth factor (VEGF) expression was studied in the renal artery wall, kidney, and perirenal fat. Renal fibrosis and stiffness were examined by trichrome and magnetic resonance elastography. RESULTS: Compared with controls, RBF and GFR were decreased in RAS, but not in MetS-RAS. MetS-RAS formed peristenotic collaterals to the same extent as RAS pigs but induced greater intrarenal microvascular loss, fibrosis, stiffness, and inflammation. MetS-RAS also attenuated VEGF expression in the renal tissue compared with RAS, despite increased expression in the perirenal fat. CONCLUSIONS: MetS does not interfere with collateral vessel formation in the stenotic kidney, possibly because decreased renal arterial VEGF expression offsets its upregulation in perirenal fat, arguing against a major contribution of the collateral circulation to preserve renal function in MetS-RAS. Furthermore, preserved renal function does not protect the poststenotic kidney from parenchymal injury.
Subject(s)
Collateral Circulation , Kidney/blood supply , Metabolic Syndrome/physiopathology , Microcirculation , Renal Artery Obstruction/physiopathology , Renal Artery/physiopathology , Renal Circulation , Animals , Blood Flow Velocity , Disease Models, Animal , Kidney/pathology , Metabolic Syndrome/complications , Metabolic Syndrome/metabolism , Renal Artery/metabolism , Renal Artery Obstruction/complications , Renal Artery Obstruction/metabolism , Renal Artery Obstruction/pathology , Sus scrofa , Vascular Endothelial Growth Factor A/metabolismABSTRACT
Renovascular disease (RVD), which is prevalent in the elderly, significantly increases cardiovascular risk and can progressively deteriorate renal function. The loss of renal function in patients with RVD is associated with a progressive dysfunction, damage, and loss of renal microvessels, which can be combined with decreased renal bioavailability of vascular endothelial growth factor (VEGF) and a defective vascular repair and proliferation. This association has been the impetus for recent efforts that have focused on developing methods to stop the progression of renal injury by protecting the renal microvasculature. This mini-review focuses on recent studies supporting potential applications of VEGF therapy for the kidney and discusses underlying mechanisms of renoprotection.
Subject(s)
Kidney/metabolism , Neovascularization, Physiologic/physiology , Renal Circulation/physiology , Vascular Endothelial Growth Factor A/metabolism , Animals , Humans , Kidney/blood supply , Renal Artery Obstruction/metabolismABSTRACT
We recently developed a therapeutic biopolymer composed of an elastin-like polypeptide (ELP) fused to vascular endothelial growth factor (VEGF) and showed long-term renoprotective effects in experimental renovascular disease after a single intra-renal administration. Here, we sought to determine the specificity, safety, efficacy, and mechanisms of renoprotection of ELP-VEGF after systemic therapy in renovascular disease. We tested whether kidney selectivity of the ELP carrier would reduce off-target binding of VEGF in other organs. In vivo bio-distribution after systemic administration of ELP-VEGF in swine was determined in kidneys, liver, spleen, and heart. Stenotic-kidney renal blood flow and glomerular filtration rate were quantified in vivo using multi-detector computed tomography (CT) after six weeks of renovascular disease, then treated with a single intravenous dose of ELP-VEGF or placebo and observed for four weeks. CT studies were then repeated and the pigs euthanized. Ex vivo studies quantified renal microvascular density (micro-CT) and fibrosis. Kidneys, liver, spleen, and heart were excised to quantify the expression of angiogenic mediators and markers of progenitor cells. ELP-VEGF accumulated predominantly in the kidney and stimulated renal blood flow, glomerular filtration rate, improved cortical microvascular density, and renal fibrosis, and was accompanied by enhanced renal expression of VEGF, downstream mediators of VEGF signaling, and markers of progenitor cells compared to placebo. Expression of angiogenic factors in liver, spleen, and heart were not different compared to placebo-control. Thus, ELP efficiently directs VEGF to the kidney after systemic administration and induces long-term renoprotection without off-target effects, supporting the feasibility and safety of renal therapeutic angiogenesis via systemic administration of a novel kidney-specific bioengineered compound.
Subject(s)
Angiogenesis Inducing Agents/pharmacology , Kidney/blood supply , Kidney/drug effects , Neovascularization, Physiologic/drug effects , Peptides/pharmacology , Renal Artery Obstruction/drug therapy , Vascular Endothelial Growth Factor A/pharmacology , Angiogenesis Inducing Agents/administration & dosage , Angiogenesis Inducing Agents/pharmacokinetics , Angiogenesis Inducing Agents/toxicity , Animals , Apoptosis/drug effects , Biomarkers/metabolism , Disease Models, Animal , Drug Carriers , Fibrosis , Glomerular Filtration Rate/drug effects , Injections, Intravenous , Kidney/metabolism , Kidney/pathology , Peptides/administration & dosage , Peptides/pharmacokinetics , Peptides/toxicity , Recombinant Fusion Proteins/pharmacology , Renal Artery Obstruction/metabolism , Renal Artery Obstruction/pathology , Renal Artery Obstruction/physiopathology , Renal Circulation/drug effects , Stem Cells/drug effects , Stem Cells/metabolism , Sus scrofa , Tissue Distribution , Vascular Endothelial Growth Factor A/administration & dosage , Vascular Endothelial Growth Factor A/pharmacokinetics , Vascular Endothelial Growth Factor A/toxicityABSTRACT
Mesenchymal stem/stromal cells (MSCs) have distinct capability for renal repair, but may have safety concerns. MSC-derived extracellular vesicles emerged as a novel noncellular alternative. Using a porcine model of metabolic syndrome and renal artery stenosis we tested whether extracellular vesicles attenuate renal inflammation, and if this capacity is mediated by their cargo of the anti-inflammatory cytokine interleukin (IL) 10. Pigs with metabolic syndrome were studied after 16 weeks of renal artery stenosis untreated or treated four weeks earlier with a single intrarenal delivery of extracellular vesicles harvested from adipose tissue-derived autologous MSCs. Lean and sham metabolic syndrome animals served as controls (seven each). Five additional pigs with metabolic syndrome and renal artery stenosis received extracellular vesicles with pre-silenced IL10 (IL10 knock-down). Single-kidney renal blood flow, glomerular filtration rate, and oxygenation were studied in vivo and renal injury pathways ex vivo. Retention of extracellular vesicles in the stenotic kidney peaked two days after delivery and decreased thereafter. Four weeks after injection, extracellular vesicle fragments colocalized with stenotic-kidney tubular cells and macrophages, indicating internalization or fusion. Extracellular vesicle delivery attenuated renal inflammation, and improved medullary oxygenation and fibrosis. Renal blood flow and glomerular filtration rate fell in metabolic syndrome and renal artery stenosis compared to metabolic syndrome, but was restored in pigs treated with extracellular vesicles. These renoprotective effects were blunted in pigs treated with IL10-depleted extracellular vesicles. Thus, extracellular vesicle-based regenerative strategies might be useful for patients with metabolic syndrome and renal artery stenosis.
Subject(s)
Extracellular Vesicles/transplantation , Kidney , Mesenchymal Stem Cell Transplantation/methods , Metabolic Syndrome/surgery , Nephritis/prevention & control , Renal Artery Obstruction/surgery , Animals , Cell Hypoxia , Cells, Cultured , Disease Models, Animal , Extracellular Vesicles/metabolism , Female , Fibrosis , Glomerular Filtration Rate , Interleukin-10/genetics , Interleukin-10/metabolism , Kidney/metabolism , Kidney/pathology , Kidney/physiopathology , Metabolic Syndrome/complications , Metabolic Syndrome/genetics , Metabolic Syndrome/metabolism , Nephritis/etiology , Nephritis/genetics , Nephritis/metabolism , Oxygen/blood , RNA Interference , Renal Artery Obstruction/complications , Renal Artery Obstruction/genetics , Renal Artery Obstruction/metabolism , Renal Circulation , Sus scrofa , Time Factors , Transplantation, AutologousABSTRACT
Renal artery stenosis (RAS) is increasingly encountered in clinical practice. The two most common etiologies are fibromuscular dysplasia (FMD) and atherosclerotic renal artery disease (ARAS), with the latter accounting for the vast majority of cases. Significant RAS activates the renin-angiotensin-aldosterone system and is associated with three major clinical syndromes: ischemic nephropathy, hypertension, and destabilizing cardiac syndromes. Over the past two decades, advancements in diagnostic and interventional techniques have led to improved detection and the widespread use of endovascular renal artery revascularization strategies in the management of ARAS. However, renal artery stenting for ARAS remains controversial. Although several studies have demonstrated some benefit with renal artery revascularization, this has not been to the extent anticipated or predicted. Moreover, these trials have significant flaws in their study design and are hampered with inherent bias which make their interpretation challenging. In this review, we evaluate the existing body of evidence and offer an approach to the management of patients with ARAS in light of the current literature. From the data provided, identification of subgroup of patients, namely, those with a hemodynamically significant RAS in the context of progressive renal insufficiency and/or deteriorating arterial hypertension, seems possible and may derive clinical benefit from ARAS stent revascularization. Appropriate patient selection is therefore the key and more robust studies are required.
Subject(s)
Blood Vessel Prosthesis Implantation , Hypertension, Renovascular , Renal Artery Obstruction/surgery , Renal Artery , Stents , Blood Vessel Prosthesis Implantation/instrumentation , Blood Vessel Prosthesis Implantation/methods , Humans , Hypertension, Renovascular/etiology , Hypertension, Renovascular/metabolism , Hypertension, Renovascular/prevention & control , Kidney/blood supply , Kidney/physiopathology , Patient Selection , Renal Artery Obstruction/complications , Renal Artery Obstruction/metabolism , Renin-Angiotensin System/physiologyABSTRACT
BACKGROUND: The management of ischemic nephropathy due to atherosclerotic renal artery stenosis has become increasingly conservative in the modern era, with current guidelines recommending optimized medical therapy as the initial step. The doubts raised by the recently published trials of revascularization strategies have led to a renewed focus on pharmacological strategies promoting blood pressure control and renal protection. It is essential to further elucidate the pathophysiological mechanisms underlying hypoperfusion induced renal microvascular dysfunction with subsequent tissue injury and fibrogenesis. The role of renin angiotensin aldosterone system as a mediator of the main pathophysiological consequences of ischemic nephropathy is well known. However, more recent experimental evidence on the adrenergic system and intrarenal tubular feedback mechanisms has stimulated new interest towards a multi-target therapeutic approach. METHODS: This review focuses on the pharmacology of the principle therapeutic drug classes currently used in the treatment of atherosclerotic renal artery stenosis with an analysis of their metabolic aspects and use in clinical practice based on evidence from clinical trials. RESULTS AND CONCLUSIONS: An optimal pharmacologic approach is crucial for a successful prevention of renal injury and cardiovascular events in this high-risk population. Antihypertensive treatment should include renin angiotensin aldosterone system blockade medication not only for their antihypertensive properties, but especially for those cardio and renoprotective.
Subject(s)
Angiotensin II Type 1 Receptor Blockers/therapeutic use , Angiotensin II Type 2 Receptor Blockers/therapeutic use , Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Ischemia/drug therapy , Kidney/drug effects , Renal Artery Obstruction/drug therapy , Renal Insufficiency, Chronic/drug therapy , Renin-Angiotensin System/drug effects , Angiotensin II Type 1 Receptor Blockers/adverse effects , Angiotensin II Type 2 Receptor Blockers/adverse effects , Angiotensin-Converting Enzyme Inhibitors/adverse effects , Animals , Humans , Ischemia/metabolism , Ischemia/physiopathology , Kidney/metabolism , Kidney/physiopathology , Renal Artery Obstruction/metabolism , Renal Artery Obstruction/physiopathology , Renal Insufficiency, Chronic/metabolism , Renal Insufficiency, Chronic/physiopathology , Renin/antagonists & inhibitors , Renin/metabolism , Treatment OutcomeABSTRACT
Renovascular hypertension (RVH) is a common cause of both cardiovascular and renal morbidity and mortality. In renal artery stenosis (RAS), atrophy in the stenotic kidney is associated with an influx of macrophages and other mononuclear cells. We tested the hypothesis that chemokine receptor 2 (CCR2) inhibition would reduce chronic renal injury by reducing macrophage influx in the stenotic kidney of mice with RAS. We employed a well-established murine model of RVH to define the relationship between macrophage infiltration and development of renal atrophy in the stenotic kidney. To determine the role of chemokine ligand 2 (CCL2)/CCR2 signaling in the development of renal atrophy, mice were treated with the CCR2 inhibitor RS-102895 at the time of RAS surgery and followed for 4 wk. Renal tubular epithelial cells expressed CCL2 by 3 days following surgery, a time at which no significant light microscopic alterations, including interstitial inflammation, were identified. Macrophage influx increased with time following surgery. At 4 wk, the development of severe renal atrophy was accompanied by an influx of inducible nitric oxide synthase (iNOS)+ and CD206+ macrophages that coexpressed F4/80, with a modest increase in macrophages coexpressing arginase 1 and F4/80. The CCR2 inhibitor RS-102895 attenuated renal atrophy and significantly reduced the number of dual-stained F4/80+ iNOS+ and F4/80+ CD206+ but not F4/80+ arginase 1+ macrophages. CCR2 inhibition reduces iNOS+ and CD206+ macrophage accumulation that coexpress F4/80 and renal atrophy in experimental renal artery stenosis. CCR2 blockade may provide a novel therapeutic approach to humans with RVH.