RESUMO
Arterial media calcification refers to the pathological deposition of calcium phosphate crystals in the arterial wall. This pathology is a common and life-threatening complication in chronic kidney disease, diabetes and osteoporosis patients. Recently, we reported that the use of a TNAP inhibitor, SBI-425, attenuated arterial media calcification in a warfarin rat model. Employing a high-dimensionality unbiased proteomic approach, we also investigated the molecular signaling events associated with blocking arterial calcification through SBI-425 dosing. The remedial actions of SBI-425 were strongly associated with (i) a significant downregulation of inflammatory (acute phase response signaling) and steroid/glucose nuclear receptor signaling (LXR/RXR signaling) pathways and (ii) an upregulation of mitochondrial metabolic pathways (TCA cycle II and Fatty Acid ß-oxidation I). Interestingly, we previously demonstrated that uremic toxin-induced arterial calcification contributes to the activation of the acute phase response signaling pathway. Therefore, both studies suggest a strong link between acute phase response signaling and arterial calcification across different conditions. The identification of therapeutic targets in these molecular signaling pathways may pave the way to novel therapies against the development of arterial media calcification.
Assuntos
Calcinose , Calcificação Vascular , Ratos , Animais , Varfarina , Reação de Fase Aguda , Proteômica , Fosfatase Alcalina/metabolismo , Calcinose/metabolismo , Calcificação Vascular/patologiaRESUMO
Calcification of the medial layer, inducing arterial stiffness, contributes significantly to cardiovascular mortality in patients with chronic kidney disease (CKD). Extracellular nucleotides block the mineralization of arteries by binding to purinergic receptors including the P2Y2 receptor. This study investigates whether deletion of the P2Y2 receptor influences the development of arterial media calcification in CKD mice. Animals were divided into: (i) wild type mice with normal renal function (control diet) (n = 8), (ii) P2Y2 R-/- mice with normal renal function (n = 8), (iii) wild type mice with CKD (n = 27), and (iv) P2Y2 R-/- mice with CKD (n = 22). To induce CKD, animals received an alternating (0.2-0.3%) adenine diet for 7 weeks. All CKD groups developed a similar degree of chronic renal failure as reflected by high serum creatinine and phosphorus levels. Also, the presence of CKD induced calcification in the heart and medial layer of the aortic wall. However, deletion of the P2Y2 receptor makes CKD mice more susceptible to the development of calcification in the heart and aorta (aortic calcium scores (median ± IQR), CKD-wild type: 0.34 ± 4.3 mg calcium/g wet tissue and CKD-P2Y2 R-/- : 4.0 ± 13.2 mg calcium/g wet tissue). As indicated by serum and aortic mRNA markers, this P2Y2 R-/- mediated increase in CKD-related arterial media calcification was associated with an elevation of calcification stimulators, including alkaline phosphatase and inflammatory molecules interleukin-6 and lipocalin 2. The P2Y2 receptor should be considered as an interesting therapeutic target for tackling CKD-related arterial media calcification.
Assuntos
Fosfatase Alcalina , Lipocalina-2 , Insuficiência Renal Crônica , Túnica Íntima , Calcificação Vascular , Animais , Camundongos , Fosfatase Alcalina/genética , Fosfatase Alcalina/metabolismo , Cálcio/metabolismo , Lipocalina-2/genética , Lipocalina-2/metabolismo , Insuficiência Renal Crônica/complicações , Insuficiência Renal Crônica/genética , Insuficiência Renal Crônica/metabolismo , Túnica Íntima/metabolismo , Túnica Íntima/patologia , Regulação para Cima , Calcificação Vascular/etiologia , Calcificação Vascular/genética , Calcificação Vascular/metabolismoRESUMO
BACKGROUND: Cardiovascular disease remains the leading cause of death in chronic kidney disease (CKD) patients, especially in those undergoing dialysis and kidney transplant surgery. CKD patients are at high risk of developing arterial media calcifications (AMC) and arterial stiffness. We hypothesized that investigation of disease progression at an early stage could provide novel insights in understanding AMC etiology. METHODS: An adenine diet was administered to male Wistar rats to induce AMC. Rats were sacrificed after 2, 4 and 8 weeks. AMC was measured by assessment of aortic calcium and visualized using histology. Arterial stiffness was measured in vivo by ultrasound and ex vivo by applying cyclic stretch of physiological magnitude on isolated arterial segments, allowing us to generate the corresponding pressure-diameter loops. Further, ex vivo arterial reactivity was assessed in organ baths at 2 and 4 weeks to investigate early alterations in biomechanics/cellular functionality. RESULTS: CKD rats showed a time-dependent increase in aortic calcium which was confirmed on histology. Accordingly, ex vivo arterial stiffness progressively worsened. Pressure-diameter loops showed a gradual loss of arterial compliance in CKD rats. Additionally, viscoelastic properties of isolated arterial segments were altered in CKD rats. Furthermore, after 2 and 4 weeks of adenine treatment, a progressive loss in basal, nitric oxide (NO) levels was observed, which was linked to an increased vessel tonus and translates into an increasing viscous modulus. CONCLUSIONS: Our observations indicate that AMC-related vascular alterations develop early after CKD induction prior to media calcifications being present. Preventive action, related to restoration of NO bioavailability, might combat AMC development.
Assuntos
Arteriosclerose , Calcinose , Insuficiência Renal Crônica , Calcificação Vascular , Rigidez Vascular , Masculino , Ratos , Animais , Cálcio , Ratos Wistar , Diálise Renal , Insuficiência Renal Crônica/complicações , Rigidez Vascular/fisiologia , Progressão da Doença , Adenina , Calcificação Vascular/etiologia , Calcificação Vascular/prevenção & controleRESUMO
Arterial media calcification is an active cell process. This encompasses osteochondrogenic transdifferentiation of vascular smooth muscle cells followed by the deposition of calcium-phosphate crystals. Increasing evidence suggests a significant role for endothelial cells (ECs) in the development of arterial media calcification. This manuscript explores a role for endothelial dysfunction in the disease progression of arterial media calcification. Male rats were randomly assigned to four different groups. The first group received standard chow. The second group was given L-NAME (≈50 mg kg-1 · d-1 ), to induce endothelial dysfunction, in addition to standard chow. The third group and fourth group received a warfarin-supplemented diet to induce mild calcification and the latter group was co-administered L-NAME. Prior to sacrifice, non-invasive measurement of aortic distensibility was performed. Animals were sacrificed after 6 weeks. Arterial media calcification was quantified by measuring aortic calcium and visualized on paraffin-embedded slices by the Von Kossa method. Arterial stiffness and aortic reactivity was assessed on isolated carotid segments using specialized organ chamber setups. Warfarin administration induced mineralization. Simultaneous administration of warfarin and L-NAME aggravated the arterial media calcification process. Through organ chamber experiments an increased vessel tonus was found, which could be linked to reduced basal NO availability, in arteries of warfarin-treated animals. Furthermore, increased calcification because of L-NAME administration was related to a further compromised endothelial function (next to deteriorated basal NO release also deteriorated stimulated NO release). Our findings suggest early EC changes to impact the disease progression of arterial media calcification.
Assuntos
Calcinose , Calcificação Vascular , Doenças Vasculares , Animais , Cálcio , Progressão da Doença , Células Endoteliais , Masculino , NG-Nitroarginina Metil Éster , Ratos , Túnica Média , Calcificação Vascular/induzido quimicamente , Varfarina/toxicidadeRESUMO
Arterial medial calcification (AMC) is the deposition of calcium phosphate in the arteries. AMC is widely thought to share similarities with physiological bone formation; however, emerging evidence suggests several key differences between these processes. N-acetylcysteine (NAC) displays antioxidant properties and can generate hydrogen sulphide (H2 S) and glutathione (GSH) from its deacetylation to l-cysteine. This study found that NAC exerts divergent effects in vitro, increasing osteoblast differentiation and bone formation by up to 5.5-fold but reducing vascular smooth muscle cell (VSMC) calcification and cell death by up to 80%. In vivo, NAC reduced AMC in a site-specific manner by 25% but had no effect on the bone. The actions of l-cysteine and H2 S mimicked those of NAC; however, the effects of H2 S were much less efficacious than NAC and l-cysteine. Pharmacological inhibition of H2 S-generating enzymes did not alter the actions of NAC or l-cysteine; endogenous production of H2 S was also unaffected. In contrast, NAC and l-cysteine increased GSH levels in calcifying VSMCs and osteoblasts by up to 3-fold. This suggests that the beneficial actions of NAC are likely to be mediated via the breakdown of l-cysteine and the subsequent GSH generation. Together, these data show that while the molecular mechanisms driving the actions of NAC appear similar, the downstream effects on cell function differ significantly between osteoblasts and calcifying VSMCs. The ability of NAC to exert these differential actions further supports the notion that there are differences between the development of pathological AMC and physiological bone formation. NAC could represent a therapeutic option for treating AMC without exerting negative effects on bone.
Assuntos
Acetilcisteína , Sulfeto de Hidrogênio , Acetilcisteína/farmacologia , Artérias/metabolismo , Glutationa/metabolismo , Sulfeto de Hidrogênio/metabolismo , Sulfeto de Hidrogênio/farmacologia , Osteoblastos/metabolismo , OsteogêneseRESUMO
[Figure: see text].
Assuntos
Apoptose , Reprogramação Celular , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Dano ao DNA , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Osteogênese , Calcificação Vascular/metabolismo , Animais , Células Cultivadas , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Modelos Animais de Doenças , Feminino , Histonas/metabolismo , Humanos , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/patologia , Fosforilação , Ratos Wistar , Transdução de Sinais , Calcificação Vascular/genética , Calcificação Vascular/patologiaRESUMO
Myo-inositol hexakisphosphate (IP6) is a natural product known to inhibit vascular calcification (VC), but with limited potency and low plasma exposure following bolus administration. Here we report the design of a series of inositol phosphate analogs as crystallization inhibitors, among which 4,6-di-O-(methoxy-diethyleneglycol)-myo-inositol-1,2,3,5-tetrakis(phosphate), (OEG2)2-IP4, displays increased in vitro activity, as well as more favorable pharmacokinetic and safety profiles than IP6 after subcutaneous injection. (OEG2)2-IP4 potently stabilizes calciprotein particle (CPP) growth, consistently demonstrates low micromolar activity in different in vitro models of VC (i.e., human serum, primary cell cultures, and tissue explants), and largely abolishes the development of VC in rodent models, while not causing toxicity related to serum calcium chelation. The data suggest a mechanism of action independent of the etiology of VC, whereby (OEG2)2-IP4 disrupts the nucleation and growth of pathological calcification.
Assuntos
Fosfatos de Inositol/química , Fosfatos de Inositol/farmacologia , Calcificação Vascular/tratamento farmacológico , 6-Fitase/metabolismo , Adenina/efeitos adversos , Animais , Células Cultivadas , Avaliação Pré-Clínica de Medicamentos/métodos , Difusão Dinâmica da Luz , Etilenoglicol/química , Humanos , Injeções Subcutâneas , Fosfatos de Inositol/farmacocinética , Masculino , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Ratos Sprague-Dawley , Uremia/tratamento farmacológico , Uremia/fisiopatologia , Calcificação Vascular/induzido quimicamente , Difração de Raios XRESUMO
Arterial media calcification refers to ectopic mineralization in the arterial wall and favors arterial stiffness and cardiovascular events. Patients with chronic kidney disease (CKD), diabetes, or osteoporosis are highly vulnerable to the development of arterial media calcifications. Tissue non-specific alkaline phosphatase (TNAP) is upregulated in calcified arteries and plays a key role in the degradation of the calcification inhibitor pyrophosphate into inorganic phosphate ions. A recent study published in The Journal of Pathology showed that an oral dosage of 10 or 30 mg/kg/day SBI-425, a selective TNAP inhibitor, inhibited the development of arterial media calcification in mice with CKD, without affecting bone mineralization. Their results indicated that SBI-425 is an effective and safe treatment for arterial media calcification. However, additional studies regarding the effect of TNAP-inhibitor SBI-425 on the progression and even the reversion of pre-existing pathological arterial media calcifications without affecting physiological bone mineralization are deserved. Furthermore, investigating the extent to which SBI-425 inhibits arterial calcification in a non-CKD context would be of particular interest to treat this comorbidity in diabetes and osteoporosis patients. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Assuntos
Calcificação Fisiológica , Calcinose , Fosfatase Alcalina , Animais , Humanos , Camundongos , Reino UnidoRESUMO
Biomineralization of the extracellular matrix is an essential, regulated process. Inappropriate mineralization of bone and the vasculature has devastating effects on patient health, yet an integrated understanding of the chemical and cell biological processes that lead to mineral nucleation remains elusive. Here, we report that biomineralization of bone and the vasculature is associated with extracellular poly(ADP-ribose) synthesized by poly(ADP-ribose) polymerases in response to oxidative and/or DNA damage. We use ultrastructural methods to show poly(ADP-ribose) can form both calcified spherical particles, reminiscent of those found in vascular calcification, and biomimetically calcified collagen fibrils similar to bone. Importantly, inhibition of poly(ADP-ribose) biosynthesis in vitro and in vivo inhibits biomineralization, suggesting a therapeutic route for the treatment of vascular calcifications. We conclude that poly(ADP-ribose) plays a central chemical role in both pathological and physiological extracellular matrix calcification.
Assuntos
Biomineralização , Dano ao DNA , Poli Adenosina Difosfato Ribose/metabolismo , Calcificação Vascular/metabolismo , Adolescente , Adulto , Idoso , Animais , Vasos Sanguíneos/metabolismo , Vasos Sanguíneos/patologia , Bovinos , Linhagem Celular , Células Cultivadas , Colágeno/metabolismo , Matriz Extracelular/metabolismo , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Osteoblastos/metabolismo , Osteoblastos/patologia , Estresse Oxidativo , Ratos , Ratos Wistar , OvinosRESUMO
BACKGROUND: Protein-bound uremic toxins indoxyl sulfate (IS) and p-cresyl sulfate (PCS) have been associated with cardiovascular morbidity and mortality in patients with CKD. However, direct evidence for a role of these toxins in CKD-related vascular calcification has not been reported. METHODS: To study early and late vascular alterations by toxin exposure, we exposed CKD rats to vehicle, IS (150 mg/kg per day), or PCS (150 mg/kg per day) for either 4 days (short-term exposure) or 7 weeks (long-term exposure). We also performed unbiased proteomic analyses of arterial samples coupled to functional bioinformatic annotation analyses to investigate molecular signaling events associated with toxin-mediated arterial calcification. RESULTS: Long-term exposure to either toxin at serum levels similar to those experienced by patients with CKD significantly increased calcification in the aorta and peripheral arteries. Our analyses revealed an association between calcification events, acute-phase response signaling, and coagulation and glucometabolic signaling pathways, whereas escape from toxin-induced calcification was linked with liver X receptors and farnesoid X/liver X receptor signaling pathways. Additional metabolic linkage to these pathways revealed that IS and PCS exposure engendered a prodiabetic state evidenced by elevated resting glucose and reduced GLUT1 expression. Short-term exposure to IS and PCS (before calcification had been established) showed activation of inflammation and coagulation signaling pathways in the aorta, demonstrating that these signaling pathways are causally implicated in toxin-induced arterial calcification. CONCLUSIONS: In CKD, both IS and PCS directly promote vascular calcification via activation of inflammation and coagulation pathways and were strongly associated with impaired glucose homeostasis.
Assuntos
Carbamatos/efeitos adversos , Intolerância à Glucose/fisiopatologia , Indicã/efeitos adversos , Poliésteres/efeitos adversos , Insuficiência Renal Crônica/patologia , Calcificação Vascular/induzido quimicamente , Animais , Produtos Biológicos/farmacologia , Biópsia por Agulha , Carbamatos/farmacologia , Modelos Animais de Doenças , Imuno-Histoquímica , Indicã/farmacologia , Masculino , Metformina/farmacologia , Poliésteres/farmacologia , Distribuição Aleatória , Ratos , Ratos Wistar , Sensibilidade e Especificidade , Calcificação Vascular/tratamento farmacológico , Calcificação Vascular/patologiaRESUMO
The use of geo-engineering materials to manage phosphorus in lakes has increased in recent years with aluminium and lanthanum based materials being most commonly applied. Hence the potential impact of the use of these compounds on human health is receiving growing interest. This review seeks to understand, evaluate and compare potential unintended consequences on human health and ecotoxicological risks associated with the use of lanthanum- and aluminium-based materials to modify chemical and ecological conditions in water bodies. In addition to their therapeutic use for the reduction of intestinal phosphate absorption in patients with impaired renal function, the phosphate binding capacity of aluminium and lanthanum also led to the development of materials used for water treatment. Although lanthanum and aluminium share physicochemical similarities and have many common applications, their uptake and kinetics within the human body and living organisms importantly differ from each other which is reflected in a different toxicity profile. Whilst a causal role in the development of neurological pathologies, skeletal lesions, hematopoietic disorders and respiratory effects has unequivocally been demonstrated with increased exposure to aluminium, studies until now have failed to find such a clear association after exposure to lanthanum although caution is warranted. Our review indicates that lanthanum and aluminium have a distinctly different profile with respect to their potential effects on human health. Regular monitoring of both aluminium and lanthanum concentrations in lanthanum-/aluminium-treated water by the responsible authorities is recommended to avoid acute accidental or chronic low level accumulation.
Assuntos
Recuperação e Remediação Ambiental/métodos , Fósforo/análise , Medição de Risco/métodos , Poluentes Químicos da Água/análise , Alumínio/metabolismo , Água Doce , Humanos , Lantânio/metabolismo , Fósforo/metabolismo , Poluentes Químicos da Água/metabolismoRESUMO
Dipeptidyl peptidase 4 (DPP4) is a conserved exopeptidase with an important function in protein regulation. The activity of DPP4, an enzyme which can either be anchored to the plasma membrane or circulate free in the extracellular compartment, affects the glucose metabolism, cellular signaling, migration and differentiation, oxidative stress and the immune system. DPP4 is also expressed on the surface of osteoblasts, osteoclasts and osteocytes, and was found to play a role in collagen metabolism. Many substrates of DPP4 have an established role in bone metabolism, among which are incretins, gastrointestinal peptides and neuropeptides. In general, their effects favor bone formation, but some effects are complex and have not been completely elucidated. DPP4 and some of its substrates are known to interact with adipokines, playing an essential role in the energy metabolism. The prolongation of the half-life of incretins through DPP4 inhibition led to the development of these inhibitors to improve glucose tolerance in diabetes. Current literature indicates that the inhibition of DPP4 activity might also result in a beneficial effect on the bone metabolism, but the long-term effect of DPP4 inhibition on fracture outcome has not been entirely established. Diabetic as well as postmenopausal osteoporosis is associated with an increased activity of DPP4, as well as a shift in the expression levels of DPP4 substrates, their receptors, and adipokines. The interactions between these factors and their relationship in bone metabolism are therefore an interesting field of study.
Assuntos
Adipocinas/metabolismo , Dipeptidil Peptidase 4/metabolismo , Inibidores da Dipeptidil Peptidase IV/metabolismo , Osteogênese/fisiologia , Animais , Diabetes Mellitus/tratamento farmacológico , Diabetes Mellitus/metabolismo , Inibidores da Dipeptidil Peptidase IV/farmacologia , Inibidores da Dipeptidil Peptidase IV/uso terapêutico , Humanos , Osteoporose/tratamento farmacológico , Osteoporose/metabolismo , Ligação Proteica/fisiologia , Especificidade por SubstratoRESUMO
Acute kidney injury (AKI) is an underestimated, yet important risk factor for development of chronic kidney disease (CKD). Even after initial total recovery of renal function, some patients develop progressive and persistent deterioration of renal function and these patients are more likely to progress to end-stage renal disease (ESRD). Animal models are indispensable for unravelling the mechanisms underlying this progression towards CKD and ESRD and for the development of new therapeutic strategies in its prevention or treatment. Ischemia (i.e. hypoperfusion after surgery, bleeding, dehydration, shock, or sepsis) is a major aetiology in human AKI, yet unilateral ischemia-reperfusion is a rarely used animal model for research on CKD and fibrosis. Here, we demonstrate in C57Bl/6J mice, by both histology and gene expression, that unilateral ischemia-reperfusion without contralateral nephrectomy is a very robust model to study the progression from acute renal injury to long-term tubulo-interstitial fibrosis, i.e. the histopathological hallmark of CKD. Furthermore, we report that the extent of renal fibrosis, in terms of Col I, TGFß, CCN2 and CCN3 expression and collagen I immunostaining, increases with increasing body temperature during ischemia and ischemia-time. Thus, varying these two main determinants of ischemic injury allows tuning the extent of the long-term fibrotic outcome in this model. Finally, in order to cover the whole practical finesse of ischemia-reperfusion and allow model and data transfer, we provide a referenced overview on crucial technical issues (incl. anaesthesia, analgesia, and pre- and post-operative care) with the specific aim of putting starters in the right direction of implementing ischemia in their research and stimulate them, as well as the community, to have a critical view on ischemic literature data.
Assuntos
Injúria Renal Aguda/complicações , Insuficiência Renal Crônica/etiologia , Traumatismo por Reperfusão/complicações , Injúria Renal Aguda/metabolismo , Injúria Renal Aguda/patologia , Animais , Modelos Animais de Doenças , Fibrose , Rim/metabolismo , Rim/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase em Tempo Real , Insuficiência Renal Crônica/metabolismo , Insuficiência Renal Crônica/patologia , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/fisiopatologiaRESUMO
Zoledronic acid, a highly potent nitrogen-containing bisphosphonate used for the treatment of pathological bone loss, is excreted unmetabolized via the kidney if not bound to the bone. In cancer patients receiving high doses of the compound renal excretion may be associated with acute tubular necrosis. The question of how zoledronic acid is internalized by renal tubular cells has not been answered until now. In the current work, using a primary human tubular cell culture system, the pathway of cellular uptake of zoledronic acid (fluorescently/radiolabeled) and its cytotoxicity were investigated. Previous studies in our laboratory have shown that this primary cell culture model consistently mimics the physiological characteristics of molecular uptake/transport of the epithelium in vivo. Zoledronic acid was found to be taken up by tubular cells via fluid-phase-endocytosis (from apical and basolateral side) as evidenced by its co-localization with dextran. Cellular uptake and the resulting intracellular level was twice as high from the apical side compared to the basolateral side. Furthermore, the intracellular zoledronic acid level was found to be dependent on the administered concentration and not saturable. Cytotoxic effects however, were only seen at higher administration doses and/or after longer incubation times. Although zoledronic acid is taken up by tubular cells, no net tubular transport could be measured. It is concluded that fluid-phase-endocytosis of zoledronic acid and cellular accumulation at high doses may be responsible for the acute tubular necrosis observed in some cancer patients receiving high doses of the compound.
Assuntos
Difosfonatos/efeitos adversos , Difosfonatos/farmacocinética , Imidazóis/efeitos adversos , Imidazóis/farmacocinética , Túbulos Renais/fisiologia , Células Cultivadas , Relação Dose-Resposta a Droga , Endocitose , Humanos , Túbulos Renais/citologia , Túbulos Renais/efeitos dos fármacos , Modelos Biológicos , Neoplasias/tratamento farmacológico , Ácido ZoledrônicoRESUMO
Prior to colonoscopy, bowel cleansing is performed for which frequently oral sodium phosphate (OSP) is used. OSP results in significant hyperphosphatemia and cases of acute kidney injury (AKI) referred to as acute phosphate nephropathy (APN; characterized by nephrocalcinosis) are reported after OSP use, which led to a US-FDA warning. To improve the safety profile of OSP, it was evaluated whether the side-effects of OSP could be prevented with intestinal phosphate binders. Hereto a Wistar rat model of APN was developed. OSP administration (2 times 1.2 g phosphate by gavage) with a 12h time interval induced bowel cleansing (severe diarrhea) and significant hyperphosphatemia (21.79 ± 5.07 mg/dl 6h after the second OSP dose versus 8.44 ± 0.97 mg/dl at baseline). Concomitantly, serum PTH levels increased fivefold and FGF-23 levels showed a threefold increase, while serum calcium levels significantly decreased from 11.29 ± 0.53 mg/dl at baseline to 8.68 ± 0.79 mg/dl after OSP. OSP administration induced weaker NaPi-2a staining along the apical proximal tubular membrane. APN was induced: serum creatinine increased (1.5 times baseline) and nephrocalcinosis developed (increased renal calcium and phosphate content and calcium phosphate deposits on Von Kossa stained kidney sections). Intestinal phosphate binding (lanthanum carbonate or aluminum hydroxide) was not able to attenuate the OSP induced side-effects. In conclusion, a clinically relevant rat model of APN was developed. Animals showed increased serum phosphate levels similar to those reported in humans and developed APN. No evidence was found for an improved safety profile of OSP by using intestinal phosphate binders.
Assuntos
Injúria Renal Aguda/induzido quimicamente , Hiperfosfatemia/induzido quimicamente , Fosfatos/efeitos adversos , Administração Oral , Hidróxido de Alumínio/administração & dosagem , Animais , Colonoscopia , Modelos Animais de Doenças , Fator de Crescimento de Fibroblastos 23 , Testes de Função Renal , Lantânio/administração & dosagem , Masculino , Fosfatos/administração & dosagem , Ratos , Ratos WistarRESUMO
Dipeptidyl peptidase 4 (DPP4) is an exopeptidase which modulates the function of its substrates, among which are insulin-releasing incretins. DPP4 inhibitors are currently used to improve glucose tolerance in type 2 diabetes patients. Inhibition of DPP4 exhibits protective effects on ischemia-reperfusion injury (IRI) of the heart and lung. As DPP4 and its substrates are also expressed in the kidney, we studied the effect of the DPP4 inhibitor vildagliptin on the outcome of IRI-induced acute kidney injury in rats in a model of 30-min unilateral renal ischemia, followed by contralateral nephrectomy. Saline, 1, or 10 mg/kg vildagliptin (VG1/VG10) was administered intravenously 15 min before the surgery. Animals were euthanized after 2, 12, amd 48 h of reperfusion. DPP4 inhibition resulted in a significant dose-dependent decrease in serum creatinine (1.31 ± 0.32 and 0.70 ± 0.19 mg/dl for VG1 and VG10, respectively, vs. 1.91 ± 0.28 mg/dl for controls at 12 h; P < 0.01). Tubular morphology (PAS-PCNA) revealed significantly reduced tubular necrosis at 12 h (62.1 ± 18.0 and 77.5 ± 22.0% in VG10 and saline, respectively). VG did not affect regeneration but decreased apoptosis, as shown by twofold decreased Bax/Bcl-2 mRNA expression and a threefold decrease in apoptotic bodies on terminal deoxynucleotidyl transferase dUTP nick-end labeling-stained sections. VG treatment significantly reduced serum malondialdehyde twofold in both VG1- and VG10-treated ischemic and sham-operated animals compared with controls and also resulted in a significant decrease in mRNA expression of the proinflammatory marker CXCL10 at 2 h of reperfusion. Through a mechanism yet to be fully understood, VG treatment results in a functional protection of the kidney against IRI. This protection was associated with antiapoptotic, immunological, and antioxidative changes.
Assuntos
Adamantano/análogos & derivados , Dipeptidil Peptidase 4/metabolismo , Inibidores da Dipeptidil Peptidase IV/uso terapêutico , Nitrilas/uso terapêutico , Pirrolidinas/uso terapêutico , Traumatismo por Reperfusão/prevenção & controle , Adamantano/uso terapêutico , Animais , Apoptose/efeitos dos fármacos , Glicemia/metabolismo , Creatinina/sangue , Rim/fisiopatologia , Túbulos Renais/patologia , Masculino , Estresse Oxidativo/efeitos dos fármacos , Ratos , VildagliptinaRESUMO
BACKGROUND/AIMS: The present study was conducted to investigate the renal tubular handling of inorganic cadmium (Cd(2+)) by exposing primary human tubular cell cultures to physiologically relevant doses of cadmium chloride (CdCl(2)). Furthermore, the cellular accumulation of Cd(2+) was compared to that of metallothionein-1-bound Cd (Cd7MT-1). Finally, this study aimed to investigate the effect of the accumulation of Cd (both Cd(2+) and Cd7MT-1) in renal cells on the expression of genes relevant to nephrotoxic processes. METHODS: Cd concentration was measured using atomic absorption spectrometry. mRNA expression was evaluated by quantitative real-time RT-PCR. RESULTS: Cd(2+) accumulated into human tubular cells in a concentration- and time-dependent way. Furthermore, cellular accumulation of Cd(2+) was different from the cellular accumulation of Cd7MT-1, indicative for different uptake routes. Finally, mRNA expression of the genes encoding the anti-oxidative proteins metallothionein-1 (MT-1) and heme-oxygenase-1 (HO-1) as well as the pro-apoptotic Bcl-2-associated X protein (Bax) were upregulated by CdCl(2) and not by Cd7MT1. CONCLUSION: In the presence of physiologically relevant Cd concentrations, tubular accumulation of the element in its inorganic form is different from that of Cd7MT-1. Furthermore, the tubular accumulation of inorganic Cd induces mRNA expression of genes of which the protein products may play a role in Cd-associated renal toxicity.
RESUMO
Erythropoietin (EPO) exerts (renal) tissue protective effects. Since it is unclear whether this is a direct effect of EPO on the kidney or not, we investigated whether EPO is able to protect human renal tubular epithelial cells (hTECs) from oxidative stress and if so which pathways are involved. EPO (epoetin delta) could protect hTECs against oxidative stress by a dose-dependent inhibition of reactive oxygen species formation. This protective effect is possibly related to the membranous expression of the EPO receptor (EPOR) since our data point to the membranous EPOR expression as a prerequisite for this protective effect. Oxidative stress reduction went along with the upregulation of renoprotective genes. Whilst three of these, heme oxygenase-1 (HO-1), aquaporin-1 (AQP-1), and B-cell CLL/lymphoma 2 (Bcl-2) have already been associated with EPO-induced renoprotection, this study for the first time suggests carboxypeptidase M (CPM), dipeptidyl peptidase IV (DPPIV), and cytoglobin (Cygb) to play a role in this process.
Assuntos
Eritropoetina/farmacologia , Túbulos Renais Proximais/efeitos dos fármacos , Túbulos Renais Proximais/patologia , Estresse Oxidativo/efeitos dos fármacos , Células Cultivadas , Citoglobina , Dipeptidil Peptidase 4/genética , Dipeptidil Peptidase 4/metabolismo , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Células Epiteliais/patologia , Epoetina alfa , Proteínas Ligadas por GPI , Regulação da Expressão Gênica/efeitos dos fármacos , Globinas/genética , Globinas/metabolismo , Glucose Oxidase , Humanos , Túbulos Renais Proximais/enzimologia , Metaloendopeptidases/genética , Metaloendopeptidases/metabolismo , Estresse Oxidativo/genética , Substâncias Protetoras/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores da Eritropoetina/metabolismo , Proteínas RecombinantesRESUMO
BACKGROUND/AIMS: Erythropoiesis-stimulating agents (ESAs) may have therapeutic benefits beyond ameliorating anemia. Although ESAs have renoprotective effects in acute/chronic renal injury models, their effects on blood pressure could also worsen chronic renal failure (CRF). The development of human cell-derived erythropoietin analogue epoetin delta prompted us (1) to investigate whether in a 5/6th nephrectomy-induced CRF rat model, epoetin delta-mediated renoprotective effects occur independently of its hematopoietic effects and (2) to unravel the involvement of particular factors herein. METHODS: After induction of CRF in Wistar rats, epoetin delta was administered for 8 weeks at different doses: 0 IU/kg (uremic control); 48, 100 or 300 IU/kg 1x/week, and 16 or 100 IU/kg 3x/week. During this period hematopoietic and renal functional parameters as well as systolic blood pressure (SBP) were monitored. RESULTS: After 8 weeks, control CRF rats showed reduced hematocrit (Hct)/hemoglobin (Hb) levels and increased SBP. Epoetin delta dose-dependently attenuated the reduction in Hct/Hb. Furthermore, epoetin delta treatment resulted in reduced deterioration of renal function in CRF rats after 8 weeks which was accompanied by decreased collagen deposition, renal fibrosis and interstitial macrophage infiltration. Remarkably, these renoprotective effects did not show the same dose dependency as compared to that seen for the hematopoietic response and were also seen at subhematopoietic doses. Interestingly, epoetin delta treatment resulted in a dose-dependent decrease of profibrotic (TGF-beta) and proapoptotic (Bcl-2-associated X protein) genes together with a significant dose-dependent increase of antifibrotic (hepatocyte growth factor) and antiapoptotic (Bcl-2) genes. Epoetin delta treatment had no effect on VEGF expression. CONCLUSION: Epoetin delta treatment could delay the progression of CRF through antiapoptotic and antifibrotic mechanisms. This protective action of epoetin delta on the kidney probably is not directly related to its hematopoietic effects.
Assuntos
Apoptose/efeitos dos fármacos , Eritropoetina/uso terapêutico , Fator de Crescimento de Hepatócito/fisiologia , Falência Renal Crônica/tratamento farmacológico , Fator de Crescimento Transformador beta/fisiologia , Anemia/tratamento farmacológico , Animais , Pressão Sanguínea/efeitos dos fármacos , Modelos Animais de Doenças , Progressão da Doença , Fibrose , Hematínicos/uso terapêutico , Fator de Crescimento de Hepatócito/biossíntese , Humanos , Rim/patologia , Masculino , Nefrectomia , Ratos , Ratos Wistar , Proteínas Recombinantes , Fator de Crescimento Transformador beta/biossíntese , Proteína X Associada a bcl-2/biossínteseRESUMO
The kidney has several defense mechanisms to avert nephrocalcinosis by preventing intratubular crystal formation and adherence. Little is known about the fate of luminally adhered crystals. In order to study post-crystal adhesion defense mechanisms we quantified the number and morphology of crystal-containing tubules in rats at various time points following ethylene glycol administration as well as in renal biopsies of patients diagnosed with nephrocalcinosis of different etiology. In rats, nephrocalcinosis was completely cleared by epithelial overgrowth of adherent crystals, which were then translocated to the interstitium and subsequently disintegrated. These processes correlated with a low to moderate infiltration of inflammatory cells. Patients with nephrocalcinosis due either to acute phosphate nephropathy, primary hyperoxaluria, preterm birth, or transplantation also showed epithelial crystal overgrowth independent of the underlying disorder or the nature of the crystals. Our study found a quantitative association between changes in tubular and crystalline morphology and crystal clearance, demonstrating the presence of an important and active nephrocalcinosis-clearing mechanism in both rat and man.