RESUMO
Acute kidney injury (AKI) is deadly and expensive, and specific, effective therapy remains a large unmet need. We have demonstrated the beneficial effects of transplanted adult tubular cells and extracellular vesicles (EVs; exosomes) derived from those renal cells on experimental ischemic AKI, even when administered after renal failure is established. To further examine the mechanisms of benefit with renal EVs, we tested the hypothesis that EVs from other epithelia or platelets (a rich source of EVs) might be protective, using a well-characterized ischemia-reperfusion model. When given after renal failure was present, renal EVs, but not those from skin or platelets, markedly improved renal function and histology. The differential effects allowed us to examine the mechanisms of benefit with renal EVs. We found significant decreases in oxidative stress postischemia in the renal EV-treated group with preservation of renal superoxide dismutase and catalase as well as increases in anti-inflammatory interleukin-10. In addition, we propose a novel mechanism of benefit: renal EVs enhanced nascent peptide synthesis following hypoxia in cells and in postischemic kidneys. Although EVs have been used therapeutically, these results serve as "proof of principle" to examine the mechanisms of injury and protection.NEW & NOTEWORTHY Acute kidney injury is common and deadly, yet the only approved treatment is dialysis. Thus, a better understanding of injury mechanisms and potential therapies is needed. We found that organ-specific, but not extrarenal, extracellular vesicles improved renal function and structure postischemia when given after renal failure occurred. Oxidative stress was decreased and anti-inflammatory interleukin-10 increased with renal, but not skin or platelet, exosomes. We also propose enhanced nascent peptide synthesis as a novel protective mechanism.
Assuntos
Injúria Renal Aguda , Vesículas Extracelulares , Traumatismo por Reperfusão , Humanos , Interleucina-10 , Plaquetas , Rim/metabolismo , Vesículas Extracelulares/patologia , Isquemia/metabolismo , Injúria Renal Aguda/patologia , Estresse Oxidativo , Traumatismo por Reperfusão/patologiaRESUMO
Mortality in acute kidney injury (AKI) patients remains very high, although very important advances in understanding the pathophysiology and in diagnosis and supportive care have been made. Most commonly, adverse outcomes are related to extra-renal organ dysfunction and failure. We and others have documented inflammation in remote organs as well as microvascular dysfunction in the kidney after renal ischemia. We hypothesized that abnormal microvascular flow in AKI extends to distant organs. To test this hypothesis, we employed intravital multiphoton fluorescence imaging in a well-characterized rat model of renal ischemia/reperfusion. Marked abnormalities in microvascular flow were seen in every organ evaluated, with decreases up to 46% observed 48 hours postischemia (as compared to sham surgery, p = 0.002). Decreased microvascular plasma flow was found in areas of erythrocyte aggregation and leukocyte adherence to endothelia. Intravital microscopy allowed the characterization of the erythrocyte formations as rouleaux that flowed as one-dimensional aggregates. Observed microvascular abnormalities were associated with significantly elevated fibrinogen levels. Plasma flow within capillaries as well as microthrombi, but not adherent leukocytes, were significantly improved by treatment with the platelet aggregation inhibitor dipyridamole. These microvascular defects may, in part, explain known distant organ dysfunction associated with renal ischemia. The results of these studies are relevant to human acute kidney injury.
Assuntos
Injúria Renal Aguda , Traumatismo por Reperfusão , Humanos , Ratos , Animais , Microcirculação/fisiologia , Insuficiência de Múltiplos Órgãos/complicações , Rim/irrigação sanguínea , Isquemia/complicações , Injúria Renal Aguda/complicações , Traumatismo por Reperfusão/complicações , Circulação RenalRESUMO
Mortality in acute kidney injury (AKI) remains very high, yet the cause of death is often failure of extrarenal organs. We and others have demonstrated remote organ dysfunction after renal ischemia. The term "cardiorenal syndrome" was first applied to the "cross talk" between the organs by the National Heart, Lung, and Blood Institute of the National Institutes of Health, and the clinical importance is being increasingly appreciated. Nevertheless, more information is needed to effectively address the consequences of renal injury on the heart. Since AKI often occurs in patients with comorbidities, we investigated the effect of renal ischemia in the setting of existing cardiac failure. We hypothesized that the cardiac effects of renal ischemia would be significantly amplified in experimental cardiomyopathy. Male Sprague-Dawley rats with preexisting cardiac and renal injury due to low-dose doxorubicin were subjected to bilateral renal artery occlusion. Cardiac structure and function were examined 2 days after reperfusion. Loss of functional myocardial tissue with decreases in left ventricular pressure, increases in apoptotic cell death, inflammation, and collagen, and greater disruption in ultrastructure with mitochondrial fragmentation were seen in the doxorubicin/ischemia group compared with animals in the groups treated with doxorubicin alone or following ischemia alone. Systemic inflammation and cardiac abnormalities persisted for at least 21 wk. These results suggest that preexisting comorbidities can result in much more severe distant organ effects of acute renal injury. The results of this study are relevant to human AKI.NEW & NOTEWORTHY Acute kidney injury is common, expensive, and deadly, yet morbidity and mortality are often secondary to remote organ dysfunction. We hypothesized that the effects of renal ischemia would be amplified in the setting of comorbidities. Sustained systemic inflammation and loss of functional myocardium with significantly decreased systolic and diastolic function, apoptotic cell death, and increased collagen and inflammatory cells were found in the heart after renal ischemia in the doxorubicin cardiomyopathy model (vs. renal ischemia alone). Understanding the remote effects of renal ischemia has the potential to improve outcomes in acute kidney injury.
Assuntos
Injúria Renal Aguda , Traumatismo por Reperfusão , Humanos , Ratos , Animais , Masculino , Insuficiência de Múltiplos Órgãos , Ratos Sprague-Dawley , Rim/metabolismo , Isquemia , Inflamação , Doxorrubicina/farmacologia , Traumatismo por Reperfusão/metabolismoRESUMO
Ischemic acute kidney injury is common, deadly, and accelerates the progression of chronic kidney disease, yet has no specific therapy. After ischemia, reperfusion is patchy with early and persistent impairment in regional renal blood flow and cellular injury. We tested the hypothesis that intrarenal coagulation results in sustained renal ischemia following reperfusion, using a well-characterized model. Markedly decreased, but heterogeneous, microvascular plasma flow with microthrombi was found postischemia by intravital microscopy. Widespread tissue factor expression and fibrin deposition were also apparent. Clotting was accompanied by complement activation and inflammation. Treatment with exosomes derived from renal tubular cells or with the fibrinolytic urokinase, given 24 h postischemia when renal failure was established, significantly improved microvascular flow, coagulation, serum creatinine, and histological evidence of injury. These data support the hypothesis that intrarenal clotting occurs early and the resultant sustained ischemia is a critical determinant of renal failure following ischemia; they demonstrate that the coagulation abnormalities are amenable to therapy and that therapy results in improvement in both function and postischemic inflammation.NEW & NOTEWORTHY Ischemic renal injury carries very high morbidity and mortality, yet has no specific therapy. We found markedly decreased, heterogeneous microvascular plasma flow, tissue factor induction, fibrin deposition, and microthrombi after renal ischemia-reperfusion using a well-characterized model. Renal exosomes or the fibrinolytic urokinase, administered after renal failure was established, improved microvascular flow, coagulation, renal function, and histology. Data demonstrate that intrarenal clotting results in sustained ischemia amenable to therapy that improves both function and postischemic inflammation.
Assuntos
Injúria Renal Aguda , Traumatismo por Reperfusão , Animais , Creatinina , Traumatismo por Reperfusão/patologia , Tromboplastina/metabolismo , Ativador de Plasminogênio Tipo Uroquinase/metabolismo , Rim/metabolismo , Isquemia/metabolismo , Injúria Renal Aguda/metabolismo , Reperfusão , Modelos Animais de Doenças , Inflamação/metabolismo , Fibrina/metabolismoRESUMO
Hypoxic acute kidney injury, a major unresolved problem, initiates, or aggravates, renal functional and structural decline. There is no treatment for hypoxic acute renal injury and its sequelae. We tested the hypothesis that human kidney tubular cells, or their extracellular vesicles (exosomes), prevent renal injury when infused intravenously 24 hours after 50 minutes of bilateral renal ischemia in Nude rats. Cells and their exosomes were from harvested human kidneys declined for transplantation. Injections of either cells or exosomes, given after 24 and 48 hours of reperfusion, preserved renal function and structure in both treatment groups. However, exosomes were superior to cells; and maintained renal vascular and epithelial networks, prevented renal oxidant stress, and apoptosis; and restrained activation of pro-inflammatory and pro-fibrogenic pathways. Exosomes worked in 24 hours, consistent with functional rather than regenerative activity. Comprehensive proteomic analysis identified 6152 renal proteins from all cellular compartments; and 628 were altered by ischemia at all cell levels, while 377 were significantly improved by exosome infusions. We conclude that renal damage from severe ischemia was broad, and human renal exosomes prevented most protein alterations. Thus, exosomes seem to acutely correct a critical and consequential abnormality during reperfusion. In their absence, renal structure and cells transition to a chronic state of fibrosis and extensive renal cell loss.
Assuntos
Injúria Renal Aguda/terapia , Micropartículas Derivadas de Células/transplante , Túbulos Renais/transplante , Traumatismo por Reperfusão/terapia , Injúria Renal Aguda/patologia , Animais , Apoptose , Exossomos/transplante , Vesículas Extracelulares/transplante , Humanos , Masculino , Ratos , Traumatismo por Reperfusão/patologiaRESUMO
Ischemic renal injury is a complex syndrome; multiple cellular abnormalities cause accelerating cycles of inflammation, cellular damage, and sustained local ischemia. There is no single therapy that effectively resolves the renal damage after ischemia. However, infusions of normal adult rat renal cells have been a successful therapy in several rat renal failure models. The sustained broad renal benefit achieved by relatively few donor cells led to the hypothesis that extracellular vesicles (EV, largely exosomes) derived from these cells are the therapeutic effector in situ We now show that EV from adult rat renal tubular cells significantly improved renal function when administered intravenously 24 and 48 hours after renal ischemia in rats. Additionally, EV treatment significantly improved renal tubular damage, 4-hydroxynanoneal adduct formation, neutrophil infiltration, fibrosis, and microvascular pruning. EV therapy also markedly reduced the large renal transcriptome drift observed after ischemia. These data show the potential utility of EV to limit severe renal ischemic injury after the occurrence.
Assuntos
Vesículas Extracelulares , Túbulos Renais/metabolismo , Rim/metabolismo , Traumatismo por Reperfusão/patologia , Injúria Renal Aguda/patologia , Aldeídos/química , Animais , Comunicação Celular , Modelos Animais de Doenças , Exossomos/metabolismo , Feminino , Perfilação da Expressão Gênica , Genótipo , Hipóxia/patologia , Rim/patologia , Microcirculação , Neutrófilos/metabolismo , Fenótipo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Insuficiência Renal , Fatores de TempoRESUMO
Diabetic nephropathy (DN) remains incurable and is the main cause of end-stage renal disease. We approached the pathophysiology of DN with systems biology, and a comprehensive profile of renal transcripts was obtained with RNA-Seq in ZS (F1 hybrids of Zucker and spontaneously hypertensive heart failure) rats, a model of diabetic nephropathy. We included sham-operated lean control rats (LS), sham-operated diabetic (DS), and diabetic rats with induced renal ischemia (DI). Diabetic nephropathy in DI was accelerated by the single episode of renal ischemia. This progressive renal decline was associated with renal iron accumulation, although serum and urinary iron levels were far lower in DI than in LS. Furthermore, obese/diabetic ZS rats have severe dyslipidemia, a condition that has been linked to hepatic iron overload. Hence, we tested and found that the fatty acids oleic acid and palmitate stimulated iron accumulation in renal tubular cells in vitro. Renal mRNAs encoding several key proteins that promote iron accumulation were increased in DI. Moreover, renal mRNAs encoding the antioxidant proteins superoxide dismutase, catalase, and most of the glutathione synthetic system were suppressed, which would magnify the prooxidant effects of renal iron loads. Substantial renal iron loads occur in obese/diabetic rats. We propose that in diabetes, specific renal gene activation is partly responsible for iron accumulation. This state might be further aggravated by lipid-stimulated iron uptake. We suggest that progressive renal iron overload may further advance renal injury in obese/diabetic ZS rats.
RESUMO
Autosomal recessive polycystic kidney disease is a truly catastrophic monogenetic disease, causing death and end stage renal disease in neonates and children. Using PCK female rats, an orthologous model of autosomal recessive polycystic kidney disease harboring mutant Pkhd1, we tested the hypothesis that intravenous renal cell transplantation with normal Sprague Dawley male kidney cells would improve the polycystic kidney disease phenotype. Cytotherapy with renal cells expressing wild type Pkhd1 and tubulogenic serum amyloid A1 had powerful and sustained beneficial effects on renal function and structure in the polycystic kidney disease model. Donor cell engraftment and both mutant and wild type Pkhd1 were found in treated but not control PCK kidneys 15 weeks after the final cell infusion. To examine the mechanisms of global protection with a small number of transplanted cells, we tested the hypothesis that exosomes derived from normal Sprague Dawley cells can limit the cystic phenotype of PCK recipient cells. We found that renal exosomes originating from normal Sprague Dawley cells carried and transferred wild type Pkhd1 mRNA to PCK cells in vivo and in vitro and restricted cyst formation by cultured PCK cells. The results indicate that transplantation with renal cells containing wild type Pkhd1 improves renal structure and function in autosomal recessive polycystic kidney disease and may provide an intra-renal supply of normal Pkhd1 mRNA.
Assuntos
Túbulos Renais/patologia , Rim Policístico Autossômico Recessivo/metabolismo , Rim Policístico Autossômico Recessivo/terapia , Animais , Proliferação de Células/efeitos dos fármacos , Terapia Baseada em Transplante de Células e Tecidos , Células Cultivadas , Cistos/metabolismo , Modelos Animais de Doenças , Exossomos , Feminino , Genótipo , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Fígado/metabolismo , Masculino , Fenótipo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Proteína Amiloide A Sérica/metabolismoRESUMO
BACKGROUND: Diabetic nephropathy is the main cause of end-stage renal disease and has reached epidemic proportions. METHODS: Comprehensive genomic profiling (RNAseq) was employed in the ZS (F1 hybrids of Zucker and spontaneously hypertensive heart failure) model of diabetic nephropathy. Controls were lean littermates. RESULTS: Diabetic nephropathy in obese, diabetic ZS was accelerated by a single episode of renal ischemia (DI). This rapid renal decline was accompanied by the activation of the renal complement system in DI, and to a lesser extent in sham-operated diabetic rats (DS). In DI there were significant increases in renal mRNA encoding C3, C4, C5, C6, C8, and C9 over sham-operated lean normal controls (LS). Moreover, mRNAs encoding the receptors for the anaphylatoxins C3a and C5a were also significantly increased in DI compared to LS. The classic complement pathway was activated in diabetic kidneys with significant increases of C1qa, C1qb, and C1qc mRNAs in DI over LS. In addition, critical regulators of complement activation were significantly attenuated in DI and DS. These included mRNAs encoding CD55, decay accelerating factor, and CD59, which inhibit the membrane attack complex. C3, C4, and C9 proteins were demonstrated in renal tubules and glomeruli. The complement RNAseq data were incorporated into a gene network showing interactions among C3-generating renal tubular cells and other immune competent migratory cells. CONCLUSIONS: We conclude that local activation of the complement system mediates renal injury in diabetic nephropathy.
Assuntos
Proteínas do Sistema Complemento/genética , Nefropatias Diabéticas/genética , Isquemia/complicações , Rim/irrigação sanguínea , Rim/metabolismo , RNA Mensageiro/metabolismo , Animais , Antígenos CD55/genética , Antígenos CD59/genética , Hipóxia Celular/fisiologia , Células Cultivadas , Complemento C1q/genética , Complemento C3/genética , Complemento C4/genética , Complemento C5/genética , Complemento C6/genética , Complemento C8/genética , Complemento C9/genética , Nefropatias Diabéticas/fisiopatologia , Modelos Animais de Doenças , Rim/patologia , Túbulos Renais/citologia , Masculino , Obesidade/complicações , Ratos , Receptor da Anafilatoxina C5a/genética , Receptores Acoplados a Proteínas G/genéticaRESUMO
Diabetic nephropathy, the most common cause of progressive chronic renal failure and end-stage renal disease, has now reached global proportions. The only means to rescue diabetic patients on dialysis is renal transplantation, a very effective therapy but severely limited by the availability of donor kidneys. Hence, we tested the role of intravenous renal cell transplantation (IRCT) on obese/diabetic Zucker/SHHF F1 hybrid (ZS) female rats with severe ischemic and diabetic nephropathy. Renal ischemia was produced by bilateral renal clamping of the renal arteries at 10 wk of age, and IRCT with genetically modified normal ZS male tubular cells was given intravenously at 15 and 20 wk of age. Rats were euthanized at 34 wk of age. IRCT with cells expressing serum amyloid A had strong and long-lasting beneficial effects on renal function and structure, including tubules and glomeruli. However, donor cells were found engrafted only in renal tubules 14 wk after the second infusion. The results indicate that IRCT with serum amyloid A-positive cells is effective in preventing the progression of chronic kidney disease in rats with diabetic and ischemic nephropathy.
Assuntos
Nefropatias Diabéticas/complicações , Falência Renal Crônica/etiologia , Falência Renal Crônica/prevenção & controle , Rim/citologia , Rim/metabolismo , Proteína Amiloide A Sérica/metabolismo , Transplantes , Administração Intravenosa , Animais , Diabetes Mellitus Experimental/complicações , Modelos Animais de Doenças , Progressão da Doença , Feminino , Isquemia/complicações , Rim/irrigação sanguínea , Masculino , Obesidade/complicações , Ratos , Ratos Zucker , Resultado do TratamentoRESUMO
Despite advances in the treatment of diabetic nephropathy (DN), currently available therapies have not prevented the epidemic of progressive chronic kidney disease (CKD). The morbidity of CKD, and the inexorable increase in the prevalence of end-stage renal disease, demands more effective approaches to prevent and treat progressive CKD. We undertook next-generation sequencing in a rat model of diabetic nephropathy to study in depth the pathogenic alterations involved in DN with progressive CKD. We employed the obese, diabetic ZS rat, a model that develops diabetic nephropathy, characterized by progressive CKD, inflammation, and fibrosis, the hallmarks of human disease. We then used RNA-seq to examine the combined effects of renal cells and infiltrating inflammatory cells acting as a pathophysiological unit. The comprehensive systems biology analysis of progressive CKD revealed multiple interactions of altered genes that were integrated into morbid networks. These pathological gene assemblies lead to renal inflammation and promote apoptosis and cell cycle arrest in progressive CKD. Moreover, in what is clearly a major therapeutic challenge, multiple and redundant pathways were found to be linked to renal fibrosis, a major cause of kidney loss. We conclude that systems biology applied to progressive CKD in DN can be used to develop novel therapeutic strategies directed to restore critical anomalies in affected gene networks.
Assuntos
Nefropatias Diabéticas/imunologia , Nefropatias Diabéticas/metabolismo , Inflamação/metabolismo , Nefropatias/imunologia , Nefropatias/metabolismo , Animais , Western Blotting , Nefropatias Diabéticas/genética , Sequenciamento de Nucleotídeos em Larga Escala , Imuno-Histoquímica , Inflamação/genética , Nefropatias/genética , Masculino , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Biologia de Sistemas , TranscriptomaRESUMO
Acute kidney injury (AKI) and chronic renal failure (CKD) are the most challenging problems in nephrology. Multiple therapies have been attempted but these interventions have minimal effects on the eventual outcomes, and all too often the result is end-stage renal disease (ESRD). The only effective therapy for ESRD is renal transplantation but only a small fraction of patients receive transplants. In this work we introduce a novel approach to transplantation designed to regenerate kidneys afflicted by severe AKI or CKD: intravenous renal cell transplantation (IRCT) with adult rat primary renal cells reprogrammed to express the SAA gene localized and engrafted in kidneys of rat recipients that had severe AKI or CKD. IRCT significantly resolved renal dysfunction and limited kidney damage, inflammation, and fibrosis. Severe CKD was successfully improved by IRCT using kidney cells from donor rats or by renal cell self-donation in a form of autotransplantation. We propose that IRCT with adult primary renal cells reprogrammed to express the SAA gene can be used to effectively treat AKI and CKD.
Assuntos
Injúria Renal Aguda/terapia , Transplante de Células/métodos , Falência Renal Crônica/terapia , Transplante de Rim/métodos , Rim/citologia , Injúria Renal Aguda/patologia , Amiloide/metabolismo , Animais , Western Blotting , Células Cultivadas , Feminino , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Injeções Intravenosas , Rim/patologia , Falência Renal Crônica/patologia , Túbulos Renais/citologia , Túbulos Renais/crescimento & desenvolvimento , Masculino , RNA Mensageiro/biossíntese , Ratos , Ratos Sprague-Dawley , Regeneração , Transfecção , Transplante Autólogo , Cromossomo YRESUMO
BACKGROUND/AIMS: Chronic kidney disease (CKD) from diabetic nephropathy is characterized by progressive loss of renal function. The renal decline has been viewed as a linear fall, presumably dependent on metabolic, hemodynamic and dietary stresses. However, renal injury in diabetic nephropathy can be rapidly aggravated by unpredictable external and internal factors, a state of affairs inconsistent with a linear loss of function. Acute renal injury and subsequent inflammation are potential factors, and we investigated their presence in renal biopsies from patients with nephropathy. METHODS: In a protocol approved by the Indiana University School of Medicine Institutional Review Board, renal biopsy specimens, estimated GFR, proteinuria and renal survival were examined in patients with diabetic nephropathy. RESULTS: Prominent clusters of inflammatory cells, particularly macrophages, were detected in the renal biopsy specimens. CKD progressed rapidly but not linearly, in that CKD was characterized by a succession of seemingly random episodes of self-limited acute renal failure. Episodes of acute kidney injury were associated with progression to end-stage renal disease. CONCLUSIONS: We propose that diabetic nephropathy is complicated by unpredictable and possibly random episodes of usually self-limited acute renal failure, and by subsequent renal inflammation, which appear to accelerate progression and eventual kidney loss.
Assuntos
Injúria Renal Aguda/complicações , Neuropatias Diabéticas/complicações , Inflamação/complicações , Falência Renal Crônica/etiologia , Injúria Renal Aguda/patologia , Biópsia , Neuropatias Diabéticas/patologia , Progressão da Doença , Fibrose/patologia , Taxa de Filtração Glomerular , Humanos , Inflamação/patologia , Rim/patologia , Pessoa de Meia-IdadeRESUMO
Serum amyloid A protein (SAA), a prominent component of the acute-phase response, is strongly expressed in developing and repairing kidneys and promotes tubulogenesis. Accordingly, we reprogrammed relatively undifferentiated NRK52E cells with the mouse SAA1.1 gene and transplanted SAA-positive and -negative cells into rats with acute renal failure. We found that SAA-positive cells accelerated renal recovery in three models of acute renal failure: gentamicin nephrotoxicity, cisplatin-mediated renal injury, and ischemia-reperfusion renal injury. The dramatic improvement of renal failure was demonstrable within 2 days, consistent with an early paracrine effect. However, abundant donor cells were also found integrated in the healing tubular architecture after 7 days. We conclude that infusions of SAA-positive cells promote renal recovery after acute renal failure and offer a potentially powerful and novel therapy of renal failure.
Assuntos
Injúria Renal Aguda/terapia , Transplante de Células , Terapia Genética/métodos , Rim/metabolismo , Traumatismo por Reperfusão/terapia , Proteína Amiloide A Sérica/biossíntese , Injúria Renal Aguda/genética , Injúria Renal Aguda/metabolismo , Injúria Renal Aguda/fisiopatologia , Animais , Apoptose , Linhagem Celular , Proliferação de Células , Cisplatino , Modelos Animais de Doenças , Genótipo , Gentamicinas , Rim/patologia , Rim/fisiopatologia , Camundongos , Proteína 1 Transportadora de Ânions Orgânicos/metabolismo , Fenótipo , Antígeno Nuclear de Célula em Proliferação/metabolismo , Ratos , Ratos Sprague-Dawley , Recuperação de Função Fisiológica , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/fisiopatologia , Proteína Amiloide A Sérica/genética , Trocador 3 de Sódio-Hidrogênio , Trocadores de Sódio-Hidrogênio/metabolismo , Fatores de Tempo , TransfecçãoRESUMO
BACKGROUND: Diabetes mellitus and its complications are a public health problem of epidemic proportions. Both diabetes and chronic kidney disease (CKD) increase the risk of acute kidney injury (AKI). Months after a single episode of acute ischaemia to the diabetic kidney, we have found an accelerated progression of nephropathy, with impaired function, severe renal inflammation, microvascular dysfunction, fibrosis and apoptotic cell death. We termed this entity the post-ischaemic inflammatory syndrome. We now test the hypothesis that blocking inflammation ameliorates the post-ischaemic inflammatory syndrome. METHODS: Obese-diabetic ZS rats (F(1) hybrids of spontaneously hypertensive heart failure and Zucker fatty diabetic rats) were treated with mycophenolate mofetil (MMF), subjected to renal ischaemia or sham surgery, and monitored via the powerful technique of intravital microscopy. RESULTS: Amelioration of post-ischaemia inflammation with MMF therapy improved long-term renal function, microvascular dysfunction, fibrosis and apoptosis. CONCLUSION: These data support the hypothesis that the post-ischaemic inflammatory syndrome accelerates diabetic CKD, is a critical determinant of injury, and can be successfully treated.
Assuntos
Nefropatias Diabéticas/tratamento farmacológico , Imunossupressores/uso terapêutico , Isquemia/complicações , Rim/irrigação sanguínea , Ácido Micofenólico/análogos & derivados , Nefrite/tratamento farmacológico , Animais , Apoptose/efeitos dos fármacos , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Permeabilidade Capilar/efeitos dos fármacos , Nefropatias Diabéticas/imunologia , Nefropatias Diabéticas/fisiopatologia , Agregação Eritrocítica/efeitos dos fármacos , Fibrose , Molécula 1 de Adesão Intercelular/genética , Rim/patologia , Masculino , Ácido Micofenólico/uso terapêutico , Nefrite/imunologia , Ratos , Receptores Depuradores Classe E/genética , SíndromeRESUMO
Diabetes is a major epidemic, and diabetic nephropathy is the most common cause of end-stage renal disease. Two critical components of diabetic nephropathy are persistent inflammation and chronic renal ischemia from widespread vasculopathy. Moreover, acute ischemic renal injury is common in diabetes, potentially causing chronic kidney disease or end-stage renal disease. Accordingly, we tested the hypothesis that acute renal ischemia accelerates nephropathy in diabetes by activating proinflammatory pathways. Lean and obese-diabetic ZS rats (F(1) hybrids of spontaneously hypertensive heart failure and Zucker fatty diabetic rats) were subjected to bilateral renal ischemia or sham surgery before the onset of proteinuria. The postischemic state in rats with obesity-diabetes was characterized by progressive chronic renal failure, increased proteinuria, and renal expression of proinflammatory mediators. Leukocyte number in obese-diabetic rat kidney was markedly increased for months after ischemia. Intrarenal blood flow velocity was decreased after ischemia in lean control and obese-diabetic rats, although it recovered in lean rats. At 2 mo after ischemia, blood flow velocity decreased further in sham-surgery and postischemia obese-diabetic rats, so that RBC flow velocity was only 39% of control in the obese-diabetic rats after ischemia. In addition, microvascular density remained depressed at 2 mo in kidneys of obese-diabetic rats after ischemia. Abnormal microvascular permeability and increases in interstitial fibrosis and apoptotic renal cell death were also more pronounced after ischemia in obese-diabetic rats. These data support the hypothesis that acute renal ischemia in obesity-diabetes severely aggravates chronic inflammation and vasculopathy, creating a self-perpetuating postischemia inflammatory syndrome, which accelerates renal failure.
Assuntos
Nefropatias Diabéticas/etiologia , Isquemia/complicações , Rim/irrigação sanguínea , Síndrome Metabólica/complicações , Nefrite/complicações , Obesidade/complicações , Animais , Apoptose , Permeabilidade Capilar , Agregação Celular , Eritrócitos/fisiologia , Fibrose , Molécula 1 de Adesão Intercelular/metabolismo , Rim/metabolismo , Rim/patologia , Leucócitos/fisiologia , Masculino , Ratos , Ratos Zucker , Circulação Renal , Insuficiência Renal/etiologia , Receptores Depuradores Classe E/metabolismoRESUMO
Serum amyloid A protein (SAA) surges 1,000-fold in the blood of acute-phase animals, and yet its function during these acute events remains unknown. We report herein that SAA stimulates a developmental program in cultured NRK-52E cells that culminates in differentiated and functional tubules that feature a proximal tubule phenotype. We also found strong SAA expression in states of tubule formation (in utero stage) and regeneration (recovery from ischemia-reperfusion injury). These data lend support to a novel view of a more localized renal acute-phase reaction, where renal SAA may act as a paracrine or autocrine molecule that promotes tubule formation during development and repair.
Assuntos
Reação de Fase Aguda/metabolismo , Túbulos Renais/efeitos dos fármacos , Túbulos Renais/crescimento & desenvolvimento , Proteína Amiloide A Sérica/metabolismo , Reação de Fase Aguda/induzido quimicamente , Animais , Caseínas/toxicidade , Linhagem Celular , Rim/efeitos dos fármacos , Rim/patologia , Camundongos , Camundongos Endogâmicos C57BL , RatosRESUMO
The early nephropathy in obese, diabetic, dyslipidemic (ZS) rats is characterized by tubular lipid accumulation and pervasive inflammation, two critically interrelated events. We now tested the hypothesis that proximal tubules from ZS obese diabetic rats in vivo, and proximal tubule cells (NRK52E) exposed to oxidized LDL (oxLDL) in vitro, change their normally quiescent epithelial phenotype into a proinflammatory phenotype. Urine of obese diabetic rats contained more lipid peroxides, and LOX-1, a membrane receptor that internalizes oxidized lipids, was mobilized to luminal sites. Levels of ICAM-1 and focal adhesion kinase, which participate in leukocyte migration and epithelial dedifferentiation, respectively, were also upregulated in tubules. NRK52E cells exposed to oxLDL showed similar modifications, plus suppression of anti-inflammatory transcription factor peroxisome proliferator-activated receptor-delta. In addition, oxLDL impaired epithelial barrier function. These alterations were prevented by an anti-LOX-1 antibody. The data support the concept that tubular LOX-1 activation driven by lipid oxidants in the preurine fluid is critical in the inflammatory changes. We suggest that luminal lipid oxidants and abnormal tubular permeability may be partly responsible for the renal tubulointerstitial injury of obesity, diabetes, and dyslipidemia.
Assuntos
Nefropatias Diabéticas/patologia , Inflamação/patologia , Nefropatias/patologia , Obesidade/patologia , Receptores Depuradores Classe E/fisiologia , Animais , Apoptose/genética , Apoptose/fisiologia , Adesão Celular/fisiologia , Linhagem Celular , Permeabilidade da Membrana Celular/fisiologia , Nefropatias Diabéticas/complicações , Impedância Elétrica , Humanos , Imuno-Histoquímica , Inflamação/genética , Molécula 1 de Adesão Intercelular/biossíntese , Nefropatias/etiologia , Nefropatias/genética , Túbulos Renais/patologia , Microscopia Confocal , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Obesidade/complicações , PPAR delta/metabolismo , Ratos , Ratos Endogâmicos SHR , Ratos Sprague-Dawley , Ratos Zucker , Receptores de LDL/metabolismo , Receptores Depuradores Classe E/genética , Distribuição Tecidual , Regulação para Cima/fisiologiaRESUMO
LOX-1 is a multifunctional membrane receptor that binds and internalizes oxidized LDL (oxLDL). We tested the hypothesis that blockade of LOX-1 with an anti-LOX-1 antibody limits nephropathy in male rats with diabetes and dyslipidemia (ZS rats; F(1) hybrid product of Zucker fatty diabetic rats and spontaneous hypertensive heart failure rats). Lean ZS rats were controls, while untreated obese ZS (OM), ZS obese rats injected with nonspecific rabbit IgG (OM-IgG; 2 microg intravenous injection given weekly), and obese ZS rats given anti-LOX-1 rabbit antibody (OM-Ab; 2 microg intravenous injection given weekly) were the experimental groups. The rats were treated from 6 to 21 wk of age. All obese groups had severe dyslipidemia and hyperglycemia. Kidneys of obese rats expressed LOX-1 in capillaries and tubules, were larger, accumulated lipid, had intense oxidative stress, leukocyte infiltration, depressed mitochondrial enzyme level and function, and peritubular fibrosis (all P < 0.05 vs. lean ZS rats). Injections with LOX-1 antibody limited these abnormalities (P < 0.01 vs. data in OM or OM-lgG rats). In vitro, renal epithelial LOX-1 expression was verified in a cultured proximal tubule cell line. Our study indicates that anti-LOX-1 (vascular and epithelial) therapy may effectively reverse critical pathogenic elements of nephropathy in diabetes and dyslipidemia.
Assuntos
Anticorpos Anti-Idiotípicos/uso terapêutico , Diabetes Mellitus/tratamento farmacológico , Dislipidemias/tratamento farmacológico , Rim/irrigação sanguínea , Rim/fisiopatologia , Receptores Depuradores Classe E/imunologia , Animais , Anticorpos Anti-Idiotípicos/imunologia , Capilares/metabolismo , Capilares/fisiopatologia , Linhagem Celular , Complicações do Diabetes/complicações , Complicações do Diabetes/metabolismo , Diabetes Mellitus/metabolismo , Modelos Animais de Doenças , Dislipidemias/complicações , Dislipidemias/metabolismo , Epitélio/metabolismo , Epitélio/fisiopatologia , Fibrose/etiologia , Fibrose/metabolismo , Fibrose/prevenção & controle , Rim/metabolismo , Túbulos Renais Proximais/metabolismo , Túbulos Renais Proximais/fisiopatologia , Peroxidação de Lipídeos/fisiologia , Masculino , Nefrite/etiologia , Nefrite/metabolismo , Nefrite/prevenção & controle , Obesidade/complicações , Obesidade/metabolismo , Ratos , Ratos Zucker , Receptores Depuradores Classe E/metabolismoRESUMO
Generalized capillary dysfunction is a morbid element in the metabolic syndrome, and it is likely involved in its complications. We tested the hypothesis that vast amounts of serum albumin previously observed in kidneys of rats with the metabolic syndrome were caused, in part, by leakage from renal peritubular capillaries. We report herein large scale leaks of plasma fluid in peritubular capillaries of rats with the metabolic syndrome. This finding was directly demonstrated in vivo, and the presence of leftover albumin residue confirmed the leak in postmortem kidney specimens. Moreover, renal interstitial fibrosis and tubular atrophy were found in a distribution similar to the leaked renal albumin in obese rats. We suggest that there is an important link between peritubular capillary damage and interstitial fibrosis, represented as tubulointerstitial disease in the metabolic syndrome. We propose that maintenance of the peritubular microcirculation may improve renal outcomes in diabetes and the metabolic syndrome.