RESUMO
BACKGROUND: Without a viable cure, chronic kidney disease is a global health concern. Inflammatory damage in and around the renal tubules dictates disease severity and is contributed to by multiple cell types. Activated in response to danger associated molecular patterns (DAMPs) including ATP, the NOD-like receptor protein-3 (NLRP3) inflammasome is integral to this inflammation. In vivo, we have previously observed that increased expression of Connexin 43 (Cx43) is linked to inflammation in chronic kidney disease (CKD) whilst in vitro studies in human proximal tubule cells highlight a role for aberrant Cx43 hemichannel mediated ATP release in tubule injury. A role for Cx43 hemichannels in priming and activation of the NLRP3 inflammasome in tubule epithelial cells remains to be determined. METHODS: Using the Nephroseq database, analysis of unpublished transcriptomic data, examined gene expression and correlation in human CKD. The unilateral ureteral obstruction (UUO) mouse model was combined with genetic (tubule-specific Cx43 knockout) and specific pharmacological blockade of Cx43 (Peptide5), to explore a role for Cx43-hemichannels in tubule damage. Human primary tubule epithelial cells were used as an in vitro model of CKD. RESULTS: Increased Cx43 and NLRP3 expression correlates with declining glomerular filtration rate and increased proteinuria in biopsies isolated from patients with CKD. Connexin 43-tubule deletion prior to UUO protected against tubular injury, increased expression of proinflammatory molecules, and significantly reduced NLRP3 expression and downstream signalling mediators. Accompanied by a reduction in F4/80 macrophages and fibroblast specific protein (FSP1+) fibroblasts, Cx43 specific hemichannel blocker Peptide5 conferred similar protection in UUO mice. In vitro, Peptide5 determined that increased Cx43-hemichannel activity primes and activates the NLRP3 inflammasome via ATP-P2X7 receptor signalling culminating in increased secretion of chemokines and cytokines, each of which are elevated in individuals with CKD. Inhibition of NLRP3 and caspase 1 similarly decreased markers of tubular injury, whilst preventing the perpetual increase in Cx43-hemichannel activity. CONCLUSION: Aberrant Cx43-hemichannel activity in kidney tubule cells contributes to tubule inflammation via activation of the NLRP3 inflammasome and downstream paracrine mediated cell signalling. Use of hemichannel blockers in targeting Cx43-hemichannels is an attractive future therapeutic target to slow or prevent disease progression in CKD. Video Abstract.
Assuntos
Conexina 43 , Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Insuficiência Renal Crônica , Animais , Humanos , Camundongos , Trifosfato de Adenosina/metabolismo , Conexina 43/metabolismo , Inflamassomos/metabolismo , Inflamação/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismoRESUMO
Focal segmental glomerulosclerosis (FSGS) is a major cause of end-stage renal disease and remains without specific treatment. To identify new events during FSGS progression, we used an experimental model of FSGS associated with nephroangiosclerosis in rats injected with L-NAME (Nω-nitro-L-arginine methyl ester). After transcriptomic analysis we focused our study on the role of Isthmin-1 (ISM1, an anti-angiogenic protein involved in endothelial cell apoptosis. We studied the renal expression of ISM1 in L-NAME rats and other models of proteinuria, particularly at the glomerular level. In the L-NAME model, withdrawal of the stimulus partially restored basal ISM1 levels, along with an improvement in renal function. In other four animal models of proteinuria, ISM1 was overexpressed and localized in podocytes while the renal function was degraded. Together these facts suggest that the glomerular expression of ISM1 correlates directly with the progression-recovery of the disease. Further in vitro experiments demonstrated that ISM1 co-localized with its receptors GRP78 and integrin αvß5 on podocytes. Treatment of human podocytes with low doses of recombinant ISM1 decreased cell viability and induced caspase activation. Stronger ISM1 stimuli in podocytes dropped mitochondrial membrane potential and induced nuclear translocation of apoptosis-inducing factor (AIF). Our results suggest that ISM1 participates in the progression of glomerular diseases and promotes podocyte apoptosis in two different complementary ways: one caspase-dependent and one caspase-independent associated with mitochondrial destabilization.
Assuntos
Glomerulosclerose Segmentar e Focal , Podócitos , Animais , Humanos , Ratos , Inibidores da Angiogênese/uso terapêutico , Caspases/metabolismo , Modelos Animais de Doenças , Glomerulosclerose Segmentar e Focal/metabolismo , NG-Nitroarginina Metil Éster/metabolismo , Podócitos/metabolismo , Proteinúria/metabolismoRESUMO
To guide the development of therapeutic interventions for acute kidney injury, elucidating the deleterious pathways of this global health problem is highly warranted. Emerging evidence has indicated a pivotal role of endothelial dysfunction in the etiology of this disease. We found that the class III semaphorin SEMA3C was ectopically upregulated with full length protein excreted into the blood and truncated protein secreted into the urine upon kidney injury and hypothesized a role for SEAM3C in acute kidney injury. Sema3c was genetically abrogated during acute kidney injury and subsequent kidney morphological and functional defects in two well-characterized models of acute kidney injury; warm ischemia/reperfusion and folic acid injection were analyzed. Employing a beta actin-dependent, inducible knockout of Sema3c, we demonstrate that in acute kidney injury SEMA3C promotes interstitial edema, leucocyte infiltration and tubular injury. Additionally, intravital microscopy combined with Evans Blue dye extravasation and primary culture of magnetically sorted peritubular endothelial cells identified a novel role for SEMA3C in promoting vascular permeability. Thus, our study points to microvascular permeability as an important driver of injury in acute kidney injury, and to SEMA3C as a novel permeability factor and potential target for therapeutic intervention.
Assuntos
Injúria Renal Aguda , Traumatismo por Reperfusão , Semaforinas , Injúria Renal Aguda/genética , Injúria Renal Aguda/prevenção & controle , Animais , Permeabilidade Capilar , Células Endoteliais/metabolismo , Feminino , Humanos , Rim/metabolismo , Masculino , Camundongos , Traumatismo por Reperfusão/complicações , Traumatismo por Reperfusão/genética , Traumatismo por Reperfusão/prevenção & controle , Semaforinas/genética , Semaforinas/metabolismoRESUMO
Renal disease is a major public health challenge since its prevalence has continuously increased over the last decades. At the end stage, extrarenal replacement therapy and transplantation remain the only treatments currently available. To understand how the disease progresses, further knowledge of its pathophysiology is needed. For this purpose, experimental models, using mainly rodents, have been developed to unravel the mechanisms involved in the initiation and progression of renal disease, as well as to identify potential targets for therapy. The gap junction protein connexin 43 has recently been identified as a novel player in the development of kidney disease. Its expression has been found to be altered in many types of human renal pathologies, as well as in different animal models, contributing to the activation of inflammatory and fibrotic processes that lead to renal damage. Furthermore, Cx43 genetic, pharmacogenetic, or pharmacological inhibition preserved renal function and structure. This review summarizes the existing advances on the role of this protein in renal diseases, based mainly on different in vivo animal models of acute and chronic renal diseases.
Assuntos
Conexina 43 , Insuficiência Renal Crônica , Animais , Humanos , Conexina 43/metabolismo , Rim/metabolismo , Conexinas/metabolismo , Insuficiência Renal Crônica/metabolismo , FibroseRESUMO
Notch3 plays an important role in the differentiation and development of vascular smooth muscle cells. Mice lacking Notch3 show deficient renal autoregulation. The aim of the study was to investigate the mechanisms involved in the Notch3-mediated control of renal vascular response. To this end, renal resistance vessels (afferent arterioles) were isolated from Notch3-/- and wild-type littermates (WT) and stimulated with angiotensin II (ANG II). Contractions and intracellular Ca2+ concentrations were blunted in Notch3-/- vessels. ANG II responses in precapillary muscle arterioles were similar between the WT and Notch3-/- mice, suggesting a focal action of Notch3 in renal vasculature. Abolishing stored Ca2+ with thapsigargin reduced Ca2+ responses in the renal vessels of the two strains, signifying intact intracellular Ca2+ mobilization in Notch3-/-. EGTA (Ca2+ chelating agent), nifedipine (L-type channel-blocker), or mibefradil (T-type channel-blocker) strongly reduced contraction and Ca2+ responses in WT mice but had no effect in Notch3-/- mice, indicating defective Ca2+ entry. Notch3-/- vessels responded normally to KCl-induced depolarization, which activates L-type channels directly. Differential transcriptomic analysis showed a major down-regulation of Cacna1h gene expression, coding for the α1H subunit of the T-type Ca2+ channel, in Notch3-/- vessels. In conclusion, renal resistance vessels from Notch3-/- mice display altered vascular reactivity to ANG II due to deficient Ca2+-entry. Consequently, Notch3 is essential for proper excitation-contraction coupling and vascular-tone regulation in the kidney.
Assuntos
Rim , Nifedipino , Receptor Notch3 , Animais , Camundongos , Angiotensina II/farmacologia , Arteríolas/metabolismo , Cálcio/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Rim/metabolismo , Mibefradil/metabolismo , Nifedipino/farmacologia , Resistência Vascular , Receptor Notch3/genética , Deleção de Genes , Camundongos KnockoutRESUMO
Galectin-3 (Gal-3) is a 30KDa lectin implicated in multiple pathophysiology pathways including renal damage and fibrosis. Gal-3 binds ß-galactoside through its carbohydrate-recognition domain. From intra-cellular to extra-cellular localization, Gal-3 has multiple roles including transduction signal pathway, cell-to-cell adhesion, cell to extracellular matrix adhesion, and immunological chemoattractant protein. Moreover, Gal-3 has also been linked to kidney disease in both preclinical models and clinical studies. Gal-3 inhibition appears to improve renal disease in several pathological conditions, thus justifying the development of multiple drug inhibitors. This review aims to summarize the latest literature regarding Gal-3 in renal pathophysiology, from its role as a biomarker to its potential as a therapeutic agent.
Assuntos
Galectina 3 , Nefropatias , Fibrose , Galectina 3/metabolismo , Humanos , Rim/metabolismo , Nefropatias/metabolismo , Transdução de SinaisRESUMO
Of increasing prevalence, diabetes is characterised by elevated blood glucose and chronic inflammation that precedes the onset of multiple secondary complications, including those of the kidney and the eye. As the leading cause of end stage renal disease and blindness in the working population, more than ever is there a demand to develop clinical interventions which can both delay and prevent disease progression. Connexins are membrane bound proteins that can form pores (hemichannels) in the cell membrane. Gated by cellular stress and injury, they open under pathophysiological conditions and in doing so release 'danger signals' including adenosine triphosphate into the extracellular environment. Linked to sterile inflammation via activation of the nod-like receptor protein 3 inflammasome, targeting aberrant hemichannel activity and the release of these danger signals has met with favourable outcomes in multiple models of disease, including secondary complications of diabetes. In this review, we provide a comprehensive update on those studies which document a role for aberrant connexin hemichannel activity in the pathogenesis of both diabetic eye and kidney disease, ahead of evaluating the efficacy of blocking connexin-43 specific hemichannels in these target tissues on tissue health and function.
Assuntos
Conexina 43/metabolismo , Complicações do Diabetes/terapia , Olho/patologia , Inflamação/metabolismo , Inflamação/terapia , Rim/patologia , Animais , Humanos , Microvasos/patologiaRESUMO
BACKGROUND: Polycystic kidney disease (PKD) is a genetic disorder affecting millions of people worldwide that is characterized by fluid-filled cysts and leads to end-stage renal disease (ESRD). The hallmarks of PKD are proliferation and dedifferentiation of tubular epithelial cells, cellular processes known to be regulated by Notch signaling. METHODS: We found increased Notch3 expression in human PKD and renal cell carcinoma biopsies. To obtain insight into the underlying mechanisms and the functional consequences of this abnormal expression, we developed a transgenic mouse model with conditional overexpression of the intracellular Notch3 (ICN3) domain specifically in renal tubules. We evaluated the alterations in renal function (creatininemia, BUN) and structure (cysts, fibrosis, inflammation) and measured the expression of several genes involved in Notch signaling and the mechanisms of inflammation, proliferation, dedifferentiation, fibrosis, injury, apoptosis and regeneration. RESULTS: After one month of ICN3 overexpression, kidneys were larger with tubules grossly enlarged in diameter, with cell hypertrophy and hyperplasia, exclusively in the outer stripe of the outer medulla. After three months, mice developed numerous cysts in proximal and distal tubules. The cysts had variable sizes and were lined with a single- or multilayered, flattened, cuboid or columnar epithelium. This resulted in epithelial hyperplasia, which was observed as protrusions into the cystic lumen in some of the renal cysts. The pre-cystic and cystic epithelium showed increased expression of cytoskeletal filaments and markers of epithelial injury and dedifferentiation. Additionally, the epithelium showed increased proliferation with an aberrant orientation of the mitotic spindle. These phenotypic tubular alterations led to progressive interstitial inflammation and fibrosis. CONCLUSIONS: In summary, Notch3 signaling promoted tubular cell proliferation, the alignment of cell division, dedifferentiation and hyperplasia, leading to cystic kidney diseases and pre-neoplastic lesions.
Assuntos
Células Epiteliais/metabolismo , Túbulos Renais/metabolismo , Doenças Renais Policísticas/etiologia , Doenças Renais Policísticas/metabolismo , Receptor Notch3/metabolismo , Animais , Biomarcadores , Modelos Animais de Doenças , Suscetibilidade a Doenças , Células Epiteliais/patologia , Fibrose , Expressão Gênica , Imuno-Histoquímica , Neoplasias Renais/etiologia , Neoplasias Renais/metabolismo , Neoplasias Renais/patologia , Túbulos Renais/patologia , Camundongos , Doenças Renais Policísticas/patologia , Receptor Notch3/genéticaRESUMO
BACKGROUND: The matricellular protein periostin has been associated with CKD progression in animal models and human biopsy specimens. Periostin functions by interacting with extracellular matrix components to drive collagen fibrillogenesis and remodeling or by signaling through cell-surface integrin receptors to promote cell adhesion, migration, and proliferation. However, its role in AKI is unknown. METHODS: We used mice with conditional tubule-specific overexpression of periostin or knockout mice lacking periostin expression in the renal ischemia-reperfusion injury model, and primary cultures of isolated tubular cells in a hypoxia-reoxygenation model. RESULTS: Tubular epithelial cells showed strong production of periostin during the repair phase of ischemia reperfusion. Periostin overexpression protected mice from renal injury compared with controls, whereas knockout mice showed increased tubular injury and deteriorated renal function. Periostin interacted with its receptor, integrin-ß1, to inhibit tubular cell cycle arrest and apoptosis in in vivo and in vitro models. After ischemia-reperfusion injury, periostin-overexpressing mice exhibited diminished expression of proinflammatory molecules and had more F4/80+ macrophages compared with knockout mice. Macrophages from periostin-overexpressing mice showed increased proliferation and expression of proregenerative factors after ischemia-reperfusion injury, whereas knockout mice exhibited the opposite. Coculturing a macrophage cell line with hypoxia-treated primary tubules overexpressing periostin, or treating such macrophages with recombinant periostin, directly induced macrophage proliferation and expression of proregenerative molecules. CONCLUSIONS: In contrast to the detrimental role of periostin in CKD, we discovered a protective role of periostin in AKI. Our findings suggest periostin may be a novel and important mediator of mechanisms controlling renal repair after AKI.
Assuntos
Injúria Renal Aguda , Moléculas de Adesão Celular/fisiologia , Proliferação de Células , Macrófagos/fisiologia , Injúria Renal Aguda/etiologia , Animais , Modelos Animais de Doenças , Rim/irrigação sanguínea , Masculino , Camundongos , Camundongos Knockout , Traumatismo por Reperfusão/complicações , Traumatismo por Reperfusão/patologiaRESUMO
BACKGROUND: Tubulointerstitial fibrosis represents the key underlying pathology of Chronic Kidney Disease (CKD), yet treatment options remain limited. In this study, we investigated the role of connexin43 (Cx43) hemichannel-mediated adenosine triphosphate (ATP) release in purinergic-mediated disassembly of adherens and tight junction complexes in early tubular injury. METHODS: Human primary proximal tubule epithelial cells (hPTECs) and clonal tubular epithelial cells (HK2) were treated with Transforming Growth Factor Beta1 (TGF-ß1) ± apyrase, or ATPγS for 48 h. For inhibitor studies, cells were co-incubated with Cx43 mimetic Peptide 5, or purinergic receptor antagonists Suramin, A438079 or A804598. Immunoblotting, single-cell force spectroscopy and trans-epithelial electrical resistance assessed protein expression, cell-cell adhesion and paracellular permeability. Carboxyfluorescein uptake and biosensing measured hemichannel activity and real-time ATP release, whilst a heterozygous Cx43+/- mouse model with unilateral ureteral obstruction (UUO) assessed the role of Cx43 in vivo. RESULTS: Immunohistochemistry of biopsy material from patients with diabetic nephropathy confirmed increased expression of purinergic receptor P2X7. TGF-ß1 increased Cx43 mediated hemichannel activity and ATP release in hPTECs and HK2 cells. The cytokine reduced maximum unbinding forces and reduced cell-cell adhesion, which translated to increased paracellular permeability. Changes were reversed when cells were co-incubated with either Peptide 5 or P2-purinoceptor inhibitors. Cx43+/- mice did not exhibit protein changes associated with early tubular injury in a UUO model of fibrosis. CONCLUSION: Data suggest that Cx43 mediated ATP release represents an initial trigger in early tubular injury via its actions on the adherens and tight junction complex. Since Cx43 is highly expressed in nephropathy, it represents a novel target for intervention of tubulointerstitial fibrosis in CKD. Video Abstract In proximal tubular epithelial cells (PTECs), tight junction proteins, including zona occuludens-1 (ZO-1), contribute to epithelial integrity, whilst the adherens junction protein epithelial (E)-cadherin (ECAD) maintains cell-cell coupling, facilitating connexin 43 (Cx43) gap junction-mediated intercellular communication (GJIC) and the direct transfer of small molecules and ions between cells. In disease, such as diabetic nephropathy, the pro-fibrotic cytokine transforming growth factor beta1 (TGF-ß1) binds to its receptor and recruits SMAD2/3 signalling ahead of changes in gene transcription and up-regulation of Cx43-mediated hemichannels (HC). Uncoupled hemichannels permit the release of adenosine triphosphate (ATP) in to the extracellular space (↑[ATP]e), where ATP binds to the P2X7 purinoreceptor and activates the nucleotide-binding domain and leucine-rich repeat containing (NLR) protein-3 (NLRP3) inflammasome. Inflammation results in epithelial-to-mesenchymal transition (EMT), fibrosis and tubular injury. A major consequence is further loss of ECAD and reduced stickiness between cells, which can be functionally measured as a decrease in the maximum unbinding force needed to uncouple two adherent cells (Fmax). Loss of ECAD feeds forward to further lessen cell-cell coupling exacerbating the switch from GJIC to HC-mediated release of ATP. Reduction in ZO-1 impedes tight junction effectiveness and decreases trans-epithelial resistance (↓TER), resulting in increased paracellular permeability.
Assuntos
Trifosfato de Adenosina/metabolismo , Conexina 43/fisiologia , Túbulos Renais , Insuficiência Renal Crônica/metabolismo , Animais , Adesão Celular , Linhagem Celular , Humanos , Túbulos Renais/metabolismo , Túbulos Renais/patologia , Camundongos , Pessoa de Meia-IdadeRESUMO
Background Podocyte loss and effacement of interdigitating podocyte foot processes are the major cause of a leaky filtration barrier and ESRD. Because the complex three-dimensional morphology of podocytes depends on the actin cytoskeleton, we studied the role in podocytes of the actin bundling protein palladin, which is highly expressed therein.Methods We knocked down palladin in cultured podocytes by siRNA transfection or in zebrafish embryos by morpholino injection and studied the effects by immunofluorescence and live imaging. We also investigated kidneys of mice with podocyte-specific knockout of palladin (PodoPalld-/- mice) by immunofluorescence and ultrastructural analysis and kidney biopsy specimens from patients by immunostaining for palladin.Results Compared with control-treated podocytes, palladin-knockdown podocytes had reduced actin filament staining, smaller focal adhesions, and downregulation of the podocyte-specific proteins synaptopodin and α-actinin-4. Furthermore, palladin-knockdown podocytes were more susceptible to disruption of the actin cytoskeleton with cytochalasin D, latrunculin A, or jasplakinolide and showed altered migration dynamics. In zebrafish embryos, palladin knockdown compromised the morphology and dynamics of epithelial cells at an early developmental stage. Compared with PodoPalld+/+ controls, PodoPalld-/- mice developed glomeruli with a disturbed morphology, an enlarged subpodocyte space, mild effacement, and significantly reduced expression of nephrin and vinculin. Furthermore, nephrotoxic serum injection led to significantly higher levels of proteinuria in PodoPalld-/- mice than in controls. Kidney biopsy specimens from patients with diabetic nephropathy and FSGS showed downregulation of palladin in podocytes as well.Conclusions Palladin has an important role in podocyte function in vitro and in vivo.
Assuntos
Actinas/metabolismo , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Podócitos/metabolismo , Animais , Citoesqueleto , Feminino , Adesões Focais , Expressão Gênica , Inativação Gênica , Humanos , Glomérulos Renais/patologia , Masculino , Camundongos Knockout , Proteínas dos Microfilamentos/metabolismo , Morfolinos/farmacologia , Podócitos/patologia , RNA Mensageiro/metabolismo , Vinculina/genética , Vinculina/metabolismo , Peixe-Zebra , Proteínas de Peixe-Zebra/genética , Proteínas de Peixe-Zebra/metabolismoRESUMO
Acute kidney injury is a major risk factor for subsequent chronic renal and/or cardiovascular complications. Previous studies have shown that Notch3 was de novo expressed in the injured renal epithelium in the early phases of chronic kidney disease. Here we examined whether Notch3 is involved in the inflammatory response and the epithelial cell damage that typifies ischemic kidneys using Notch3 knockout mice and mice with short-term activated Notch3 signaling (N3ICD) in renal epithelial cells. After ischemia/reperfusion, N3ICD mice showed exacerbated infiltration of inflammatory cells and severe tubular damage compared to control mice. Inversely, Notch3 knockout mice were protected against ischemia/reperfusion injury. Renal macrophages derived from Notch3 knockout mice failed to activate proinflammatory cytokines. Chromatin immunoprecipitation analysis of the Notch3 promoter identified NF-κB as the principal inducer of Notch3 in ischemia/reperfusion. Thus, Notch3 induced by NF-κB in the injured epithelium sustains a proinflammatory environment attracting activated macrophages to the site of injury leading to a rapid deterioration of renal function and structure. Hence, targeting Notch3 may provide a novel therapeutic strategy against ischemia/reperfusion and acute kidney injury by preservation of epithelial structure and disruption of proinflammatory signaling.
Assuntos
Injúria Renal Aguda/patologia , Túbulos Renais/patologia , Receptor Notch3/metabolismo , Traumatismo por Reperfusão/complicações , Injúria Renal Aguda/etiologia , Injúria Renal Aguda/imunologia , Animais , Modelos Animais de Doenças , Células Epiteliais/imunologia , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Epitélio/metabolismo , Epitélio/patologia , Humanos , Túbulos Renais/imunologia , Túbulos Renais/metabolismo , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NF-kappa B/metabolismo , Regiões Promotoras Genéticas/genética , Receptor Notch3/genéticaRESUMO
Chronic kidney disease is an incurable to date pathology with a continuously growing incidence that contributes to the increase of the number of deaths worldwide. With currently no efficient prognostic or therapeutic options being available, the only possibility for treatment of end-stage renal disease is renal replacement therapy through dialysis or transplantation. Understanding the molecular mechanisms participating in the progression of renal diseases and uncovering the pathways implicated will permit the identification of novel and more efficient targets of therapy. Connexin43 was recently identified as a novel player in the development of chronic kidney disease. It was found de novo expressed and/or differentially localized in various renal cell populations during progression of renal disease, indicating an abnormal connexin signaling, both in patients and animal models. Subsequent in vivo studies demonstrated that connexin43 is involved in mediating inflammatory and fibrotic processes contributing to renal damage. Genetic, pharmaco-genetic or peptide-based inhibition of connexin43 in animal models and cell culture systems was successful in preventing the progression of the pathology and preserving the cell phenotypes. This review will summarize the recent advances on connexin43 in the field of kidney diseases and discuss the potential of future connexin43-based therapies against chronic kidney disease.
Assuntos
Conexina 43/metabolismo , Insuficiência Renal Crônica/patologia , Conexina 43/antagonistas & inibidores , Conexina 43/genética , Humanos , Rim/metabolismo , Células Mesangiais/citologia , Células Mesangiais/metabolismo , Oligonucleotídeos Antissenso/uso terapêutico , Peptídeos/química , Peptídeos/metabolismo , Peptídeos/uso terapêutico , Podócitos/citologia , Podócitos/metabolismo , Insuficiência Renal Crônica/tratamento farmacológico , Insuficiência Renal Crônica/metabolismoRESUMO
De novo expression in the kidney of periostin, a protein involved in odontogenesis and osteogenesis, has been suggested as a biomarker of renal disease. In this study, we investigated the mechanism(s) of induction and the role of periostin in renal disease. Using a combination of bioinformatics, reporter assay, and chromatin immunoprecipitation analyses, we found that NFκB and other proinflammatory transcription factors induce periostin expression in vitro and that binding of these factors on the periostin promoter is enriched in glomeruli during experimental GN. Mice lacking expression of periostin displayed preserved renal function and structure during GN. Furthermore, delayed administration of periostin antisense oligonucleotides in wild-type animals with GN reversed already established proteinuria, diminished tissue inflammation, and improved renal structure. Lack of periostin expression also blunted the de novo renal expression of integrin-ß3 and phosphorylation of focal adhesion kinase and AKT, known mediators of integrin-ß3 signaling that affect cell motility and survival, observed during GN in wild-type animals. In vitro, recombinant periostin increased the expression of integrin-ß3 and the concomitant phosphorylation of focal adhesion kinase and AKT in podocytes. Notably, periostin and integrin-ß3 were highly colocalized in biopsy specimens from patients with inflammatory GN. These results demonstrate that interplay between periostin and renal inflammation orchestrates inflammatory and fibrotic responses, driving podocyte damage through downstream activation of integrin-ß3 signaling. Targeting periostin may be a novel therapeutic strategy for treating CKD.
Assuntos
Moléculas de Adesão Celular/fisiologia , Integrina beta3/fisiologia , Nefropatias/etiologia , NF-kappa B/fisiologia , Animais , Feminino , Glomerulonefrite/complicações , Nefropatias/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Transdução de SinaisRESUMO
GN refers to a variety of renal pathologies that often progress to ESRD, but the molecular mechanisms underlying this progression remain incompletely characterized. Here, we determined whether dysregulated expression of the gap junction protein connexin 43, which has been observed in the progression of renal disease, contributes to GN progression. Immunostaining revealed de novo expression of connexin 43 in damaged glomeruli in patients with glomerular diseases as well as in mice after induction of experimental GN. Notably, 2 weeks after the induction of GN with nephrotoxic serum, mice with a heterozygous deletion of the connexin 43 gene (connexin 43+/-) had proteinuria, BUN, and serum creatinine levels significantly lower than those of wild-type animals. Additionally, the connexin 43+/- mice showed less crescent formation, tubular dilation, monocyte infiltration, and interstitial renal fibrosis. Treatment of cultured podocytes with connexin 43-specific blocking peptides attenuated TGF-ß-induced cytoskeletal and morphologic changes and apoptosis as did treatment with the purinergic blocker suramin. Finally, therapeutic treatment of GN mice with connexin 43-specific antisense oligodeoxynucleotide improved functional and structural renal parameters. These findings suggest that crosstalk between connexin 43 and purinergic signaling contributes to podocyte damage in GN. Given that this protein is highly induced in individuals with glomerular diseases, connexin 43 may be a novel target for therapeutic treatment of GN.
Assuntos
Conexina 43/metabolismo , Glomerulonefrite/metabolismo , Animais , Apoptose , Desdiferenciação Celular , Linhagem Celular , Modelos Animais de Doenças , Progressão da Doença , Feminino , Fibrose , Glomerulonefrite/patologia , Humanos , Rim/patologia , Camundongos , Podócitos/metabolismo , Receptores Purinérgicos/metabolismoRESUMO
Kidneys are highly complex organs, playing a crucial role in human physiopathology, as they are implicated in vital processes, such as fluid filtration and vasomotor tone regulation. There is growing evidence that gap junctions are major determinants of renal physiopathology. It has been demonstrated that their expression or channel activity may vary depending on physiological and pathological situations within distinct renal compartments. While some studies have focused on the role of connexins in renal physiology, our knowledge regarding the functional relevance of pannexins is still very limited. In this paper, we provide an overview of the involvement of connexins, pannexins and their channels in various physiological processes related to different renal compartments.
Assuntos
Conexinas/metabolismo , Junções Comunicantes/metabolismo , Junções Comunicantes/fisiologia , Rim/metabolismo , Rim/fisiologia , Animais , Comunicação Celular/fisiologia , Humanos , Canais Iônicos/metabolismoRESUMO
The incidence and prevalence of chronic kidney disease represents an important problem for public health. In renal diseases, the main histologic alterations derive from the development of renal fibrosis which results from the loss of the balance between pro- and anti-fibrotic factors. Tyrosine kinase receptors (RTKs) and matricellular proteins (MPs) are nowadays studied as potential modulators of renal injury. RTKs regulate cell cycle, migration, metabolism and cellular differentiation. Discoidin domain receptor-1 (DDR-1) is an RTK that has been extensively studied in cancer, and lung and renal diseases. It modulates inflammatory recruitment, extracellular matrix deposition and fibrosis; in renal diseases, it appears to act independently of the underlying disease. MPs regulate cell-matrix interactions and matrix accumulation, cellular adhesion and migration, and expression of inflammatory cells. Periostin is an MP, mainly studied in bone, heart, lung and cancer. Several studies demonstrated that it mediates cell-matrix interactions, migration of inflammatory cells and development of fibrosis. Recently, it has been reported in several nephropathies. In this review, we discuss the potential pathological roles of DDR-1 and periostin focussing on the kidney in both experimental models and human diseases.
Assuntos
Moléculas de Adesão Celular/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Insuficiência Renal Crônica/metabolismo , Receptor com Domínio Discoidina 1 , HumanosAssuntos
Exossomos/genética , Glomérulos Renais/lesões , MicroRNAs/genética , Insuficiência Renal Crônica/genética , Insuficiência Renal Crônica/urina , Regulação para Cima/genética , Adulto , Desdiferenciação Celular , Feminino , Taxa de Filtração Glomerular , Humanos , Masculino , MicroRNAs/metabolismo , Pessoa de Meia-Idade , Podócitos/metabolismo , Podócitos/patologia , Insuficiência Renal Crônica/fisiopatologiaRESUMO
Excessive recruitment of monocytes and progression of fibrosis are hallmarks of chronic kidney disease (CKD). Recently we reported that the expression of connexin 43 (Cx43) was upregulated in the kidney during experimental nephropathy. To investigate the role of Cx43 in the progression of CKD, we interbred RenTg mice, a genetic model of hypertension-induced CKD, with Cx43+/- mice. The renal cortex of 5-month-old RenTgCx43+/- mice showed a marked decrease of cell adhesion markers leading to reduced monocyte infiltration and interstitial renal fibrosis compared with their littermates. In addition, functional and histological parameters such as albuminuria and glomerulosclerosis were ameliorated in RenTgCx43+/- mice. Interestingly, treatment with Cx43 antisense produced remarkable improvement of renal function and structure in 1-year-old RenTg mice. Similar results were found in Cx43+/- or wild-type mice treated with Cx43 antisense after obstructive nephropathy. Furthermore, in these mice, Cx43 antisense attenuated E-cadherin downregulation and phosphorylation of the transcription factor Sp1 by the ERK pathway resulting in decreased transcription of type I collagen gene. Interestingly, Cx43-specific blocking peptide inhibited monocyte adhesion in activated endothelium and profibrotic pathways in tubular cells. Cx43 was highly increased in biopsies of patients with CKD. Thus, Cx43 may represent a new therapeutic target against the progression of CKD.
Assuntos
Conexina 43/genética , Oligonucleotídeos Antissenso/uso terapêutico , Insuficiência Renal Crônica/tratamento farmacológico , Insuficiência Renal Crônica/patologia , Albuminúria/tratamento farmacológico , Albuminúria/genética , Animais , Caderinas/metabolismo , Adesão Celular , Colágeno Tipo I/genética , Conexina 43/análise , Progressão da Doença , Regulação para Baixo/efeitos dos fármacos , Fibrose , Glomerulosclerose Segmentar e Focal/tratamento farmacológico , Glomerulosclerose Segmentar e Focal/genética , Humanos , Sistema de Sinalização das MAP Quinases , Camundongos , Monócitos/fisiologia , Oligonucleotídeos Antissenso/farmacologia , Fosforilação/efeitos dos fármacos , Insuficiência Renal Crônica/genética , Fator de Transcrição Sp1/metabolismo , Transcrição GênicaRESUMO
Vascular endothelial dysfunction is a major risk factor in the development of renal diseases. Recent studies pointed out a major interest for the inter-endothelial junction protein CD146, as its expression is modulated during renal injury. Indeed, some complex mechanisms involving this adhesion molecule and its multiple ligands are observed in a large number of renal diseases in fundamental or clinical research. The purpose of this review is to summarize the most recent literature on the role of CD146 in renal pathophysiology, from experimental nephropathy to clinical trials.