RESUMO
SignificanceUsing SARS-CoV-2 as a relevant case study for infectious disease, we investigate the structure-function relationships that dictate antiviral spherical nucleic acid (SNA) vaccine efficacy. We show that the SNA architecture can be rapidly employed to target COVID-19 through incorporation of the receptor-binding domain, and that the resulting vaccine potently activates human cells in vitro and mice in vivo. Furthermore, when challenged with a lethal viral infection, only mice treated with the SNA vaccine survived. Taken together, this work underscores the importance of rational vaccine design for infectious disease to yield vaccines that elicit more potent immune responses to effectively fight disease.
Assuntos
Controle de Doenças Transmissíveis , Ácidos Nucleicos/imunologia , Vacinas de DNA/imunologia , Animais , Biotecnologia , COVID-19/prevenção & controle , Controle de Doenças Transmissíveis/métodos , Doenças Transmissíveis/etiologia , Doenças Transmissíveis/imunologia , Humanos , Ácidos Nucleicos/química , SARS-CoV-2/imunologia , Desenvolvimento de Vacinas , Vacinas de DNA/genética , Vacinas Virais/genética , Vacinas Virais/imunologiaRESUMO
The concept of local formation of angiotensin II in the kidney has changed over the last 10-15 years. Local synthesis of angiotensinogen in the proximal tubule has been proposed, combined with prorenin synthesis in the collecting duct. Binding of prorenin via the so-called (pro)renin receptor has been introduced, as well as megalin-mediated uptake of filtered plasma-derived renin-angiotensin system (RAS) components. Moreover, angiotensin metabolites other than angiotensin II [notably angiotensin-(1-7)] exist, and angiotensins exert their effects via three different receptors, of which angiotensin II type 2 and Mas receptors are considered renoprotective, possibly in a sex-specific manner, whereas angiotensin II type 1 (AT1) receptors are believed to be deleterious. Additionally, internalized angiotensin II may stimulate intracellular receptors. Angiotensin-converting enzyme 2 (ACE2) not only generates angiotensin-(1-7) but also acts as coronavirus receptor. Multiple, if not all, cardiovascular diseases involve the kidney RAS, with renal AT1 receptors often being claimed to exert a crucial role. Urinary RAS component levels, depending on filtration, reabsorption, and local release, are believed to reflect renal RAS activity. Finally, both existing drugs (RAS inhibitors, cyclooxygenase inhibitors) and novel drugs (angiotensin receptor/neprilysin inhibitors, sodium-glucose cotransporter-2 inhibitors, soluble ACE2) affect renal angiotensin formation, thereby displaying cardiovascular efficacy. Particular in the case of the latter three, an important question is to what degree they induce renoprotection (e.g., in a renal RAS-dependent manner). This review provides a unifying view, explaining not only how kidney angiotensin formation occurs and how it is affected by drugs but also why drugs are renoprotective when altering the renal RAS. SIGNIFICANCE STATEMENT: Angiotensin formation in the kidney is widely accepted but little understood, and multiple, often contrasting concepts have been put forward over the last two decades. This paper offers a unifying view, simultaneously explaining how existing and novel drugs exert renoprotection by interfering with kidney angiotensin formation.
Assuntos
Angiotensinogênio , Doenças Cardiovasculares , Feminino , Humanos , Masculino , Angiotensina II/metabolismo , Enzima de Conversão de Angiotensina 2 , Angiotensinogênio/metabolismo , Doenças Cardiovasculares/metabolismo , Sistemas de Liberação de Medicamentos , Rim/irrigação sanguínea , Rim/metabolismo , Renina/metabolismo , Sistema Renina-Angiotensina , Inibidores do Transportador 2 de Sódio-Glicose/metabolismoRESUMO
There are diverse pathophysiological mechanisms involved in acute kidney injury (AKI). Among them, overactivity of the renin-angiotensin system (RAS) has been described. Angiotensin-converting enzyme 2 (ACE2) is a tissue RAS enzyme expressed in the apical border of proximal tubules. Given the important role of ACE2 in the metabolism of angiotensin II, this study aimed to characterize kidney and urinary ACE2 in a mouse model of AKI. Ischemia-reperfusion injury (IRI) was induced in C57BL/6 mice by clamping of the left renal artery followed by removal of the right kidney. In kidneys harvested 48 h after IRI, immunostaining revealed a striking maldistribution of ACE2 including spillage into the tubular lumen and the presence of ACE2-positive luminal casts in the medulla. In cortical membranes, ACE2 protein and enzymatic activity were both markedly reduced (37 ± 4 vs. 100 ± 6 ACE2/ß-actin, P = 0.0004, and 96 ± 14 vs. 152 ± 6 RFU/µg protein/h, P = 0.006). In urine, full-length membrane-bound ACE2 protein (100 kDa) was markedly increased (1,120 ± 405 vs. 100 ± 46 ACE2/µg creatinine, P = 0.04), and casts stained for ACE2 were recovered in the urine sediment. In conclusion, in AKI caused by IRI, there is a marked loss of ACE2 from the apical tubular border with deposition of ACE2-positive material in the medulla and increased urinary excretion of full-length membrane-bound ACE2 protein. The deficiency of tubular ACE2 in AKI suggests that provision of this enzyme could have therapeutic applications and that its excretion in the urine may also serve as a diagnostic marker of severe proximal tubular injury.NEW & NOTEWORTHY This study provides novel insights into the distribution of kidney ACE2 in a model of AKI by IRI showing a striking detachment of apical ACE2 from proximal tubules and its loss in urine and urine sediment. The observed deficiency of kidney ACE2 protein and enzymatic activity in severe AKI suggests that administration of forms of this enzyme may mitigate AKI and that urinary ACE2 may serve as a potential biomarker for tubular injury.
Assuntos
Injúria Renal Aguda , Enzima de Conversão de Angiotensina 2 , Rim , Traumatismo por Reperfusão , Animais , Masculino , Camundongos , Injúria Renal Aguda/urina , Injúria Renal Aguda/patologia , Injúria Renal Aguda/metabolismo , Injúria Renal Aguda/enzimologia , Enzima de Conversão de Angiotensina 2/metabolismo , Enzima de Conversão de Angiotensina 2/urina , Biomarcadores/urina , Modelos Animais de Doenças , Rim/metabolismo , Rim/patologia , Rim/enzimologia , Camundongos Endogâmicos C57BL , Peptidil Dipeptidase A/urina , Peptidil Dipeptidase A/metabolismo , Sistema Renina-Angiotensina , Traumatismo por Reperfusão/urina , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/enzimologiaRESUMO
Urinary [Formula: see text] excretion is decreased in chronic kidney disease (CKD), but very little is known about fecal [Formula: see text] excretion. Sodium zirconium cyclosilicate (SZC) is a cation exchanger that selectively captures K+ in the gastrointestinal tract. We investigated if SZC can sequester [Formula: see text] in vivo and evaluated the effect of SZC on fecal [Formula: see text] in a mouse model of CKD. Mice with CKD induced by 5/6 kidney ablation were fed either a regular diet or a diet containing SZC (4 g/kg) and followed for 7 days. Fecal [Formula: see text] was measured before and after the addition of 50 meq KCl/L to release [Formula: see text] from SZC. [Formula: see text] sequestered in SZC in the gastrointestinal (GI) tract was estimated from the change in fecal [Formula: see text] observed when KCl was added to liberate the sequestered [Formula: see text]. In mice with CKD, fecal [Formula: see text] excretion was higher than in normal mice and also higher than urine [Formula: see text] excretion measured concurrently. Using data pooled from the SZC diet, the change in [Formula: see text] was 6.5 ± 0.6 compared with 0.6 ± 0.6 µmol/g on the normal diet (P < 0.0001). In conclusion, fecal [Formula: see text] excretion in CKD is increased and about sixfold higher than urine [Formula: see text] excretion, revealing an important route of elimination of [Formula: see text] present in the GI tract. SZC administration sequesters a substantial portion of [Formula: see text] in the GI tract, suggesting that the binding of [Formula: see text] offers therapeutic potential beyond its known primary action as a specific K+ binder.NEW & NOTEWORTHY Fecal [Formula: see text] excretion in chronic kidney disease is increased and about sixfold higher than urine [Formula: see text] excretion, revealing an important route of elimination of [Formula: see text] that is present in the gastrointestinal tract. Sodium zirconium cyclosilicate (SZC) administration sequesters a substantial portion of [Formula: see text], suggesting that binding of [Formula: see text] by SZC in the gastrointestinal tract offers therapeutic potential in chronic kidney disease and other clinical conditions beyond its known primary action of SZC as a specific K+ binder.
Assuntos
Hiperpotassemia , Insuficiência Renal Crônica , Animais , Camundongos , Potássio , Trato GastrointestinalRESUMO
BACKGROUND: Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) uses full-length angiotensin converting enzyme 2 (ACE2) as a main receptor to enter target cells. The goal of this study was to demonstrate the preclinical efficacy of a novel soluble ACE2 protein with increased duration of action and binding capacity in a lethal mouse model of COVID-19. METHODS: A human soluble ACE2 variant fused with an albumin binding domain (ABD) was linked via a dimerization motif hinge-like 4-cysteine dodecapeptide (DDC) to improve binding capacity to SARS-CoV-2. This novel soluble ACE2 protein (ACE2-1-618-DDC-ABD) was then administered intranasally and intraperitoneally to mice before intranasal inoculation of SARS-CoV-2 and then for two additional days post viral inoculation. RESULTS: Untreated animals became severely ill, and all had to be humanely euthanized by day 6 or 7 and had pulmonary alveolar hemorrhage with mononuclear infiltrates. In contrast, all but one mouse infected with a lethal dose of SARS-CoV-2 that received ACE2-1-618-DDC-ABD survived. In the animals inoculated with SARS-CoV-2 that were untreated, viral titers were high in the lungs and brain, but viral titers were absent in the kidneys. Some untreated animals, however, had variable degrees of kidney proximal tubular injury as shown by attenuation of the proximal tubular brush border and increased NGAL and TUNEL staining. Viral titers in the lung and brain were reduced or nondetectable in mice that received ACE2-1-618-DDC-ABD, and the animals developed only moderate disease as assessed by a near-normal clinical score, minimal weight loss, and improved lung and kidney injury. CONCLUSIONS: This study demonstrates the preclinical efficacy of a novel soluble ACE2 protein, termed ACE2-1-618-DDC-ABD, in a lethal mouse model of SARS-CoV-2 infection that develops severe lung injury and variable degrees of moderate kidney proximal tubular injury.
Assuntos
Enzima de Conversão de Angiotensina 2 , COVID-19 , Enzima de Conversão de Angiotensina 2/uso terapêutico , Animais , COVID-19/terapia , Rim/virologia , Pulmão/virologia , Camundongos , SARS-CoV-2RESUMO
BACKGROUND: There is an urgent need for approaches to prevent and treat SARS-CoV-2 infection. Administration of soluble ACE2 protein acting as a decoy to bind to SARS-CoV-2 should limit viral uptake mediated by binding to membrane-bound full-length ACE2, and further therapeutic benefit should result from ensuring enzymatic ACE2 activity to affected organs in patients with COVID-19. METHODS: A short variant of human soluble ACE2 protein consisting of 618 amino acids (hACE2 1-618) was generated and fused with an albumin binding domain (ABD) using an artificial gene encoding ABDCon, with improved albumin binding affinity. Human kidney organoids were used for infectivity studies of SARS-CoV-2 in a BSL-3 facility to examine the neutralizing effect of these novel ACE2 variants. RESULTS: Whereas plasma ACE2 activity of the naked ACE2 1-618 and ACE2 1-740 lasted about 8 hours, the ACE2 1-618-ABD resulted in substantial activity at 96 hours, and it was still biologically active 3 days after injection. Human kidney organoids express ACE2 and TMPRSS2, and when infected with SARS-CoV-2, our modified long-acting ACE2 variant neutralized infection. CONCLUSIONS: This novel ACE2 1-618-ABD can neutralize SARS-CoV-2 infectivity in human kidney organoids, and its prolonged duration of action should ensure improved efficacy to prevent viral escape and dosing convenience.
RESUMO
Aminopeptidase A is one of the most potent enzymes within the renin-angiotensin system in terms of angiotensin II degradation. Here, we examined whether there is a kidney phenotype and any compensatory changes in other renin angiotensin system enzymes involved in the metabolism of angiotensin II associated with aminopeptidase A deficiency. Kidneys harvested from aminopeptidase A knockout mice were examined by light and electron microscopy, immunohistochemistry and immunofluorescence. Kidney angiotensin II levels and the ability of renin angiotensin system enzymes in the glomerulus to degrade angiotensin II ex vivo, their activities, protein and mRNA levels in kidney lysates were evaluated. Knockout mice had increased blood pressure and mild glomerular mesangial expansion without significant albuminuria. By electron microscopy, knockout mice exhibited a mild increase of the mesangial matrix, moderate thickening of the glomerular basement membrane but a striking appearance of knob-like structures. These knobs were seen in both male and female mice and persisted after the treatment of hypertension. In isolated glomeruli from knockout mice, the level of angiotensin II was more than three-fold higher as compared to wild type control mice. In kidney lysates from knockout mice angiotensin converting enzyme activity, protein and mRNA levels were markedly decreased possibly as a compensatory mechanism to reduce angiotensin II formation. Thus, our findings support a role for aminopeptidase A in the maintenance of glomerular structure and intra-kidney homeostasis of angiotensin peptides.
Assuntos
Membrana Basal Glomerular , Glutamil Aminopeptidase , Rim , Angiotensina II/metabolismo , Animais , Feminino , Membrana Basal Glomerular/metabolismo , Glutamil Aminopeptidase/genética , Glutamil Aminopeptidase/metabolismo , Rim/metabolismo , Masculino , Camundongos , Camundongos Knockout , Sistema Renina-Angiotensina/genéticaRESUMO
Angiotensin converting enzyme 2 (ACE2) plays an important role in inflammation, which is attributable at least, in part, to the conversion of the pro-inflammatory angiotensin (Ang) II peptide into angiotensin 1-7 (Ang 1-7), a peptide which opposes the actions of AngII. ACE2 and AngII are present in many tissues but information on the cornea is lacking. We observed that mice deficient in the Ace2 gene (Ace2-/- ), developed a cloudy cornea phenotype as they aged. Haze occupied the central cornea, accompanied by corneal edema and neovascularization. In severe cases with marked chronic inflammation, a cell-fate switch from a transparent corneal epithelium to a keratinized, stratified squamous, psoriasiform-like epidermis was observed. The stroma contained a large number of CD11c, CD68, and CD3 positive cells. Corneal epithelial debridement experiments in young ACE2-deficient mice showed normal appearing corneas, devoid of haze. We hypothesized, however, that these mice are "primed" for a corneal inflammatory response, which once initiated, would persist. In vitro studies reveal that interleukins (IL-1a, IL-1b), chemokines (CCL2, CXCL8), and TNF-α, are all significantly elevated, resulting in a cytokine storm-like phenotype. This phenotype could be partially rescued by treatment with the AngII type 1 receptor (AT1R) antagonist, losartan, suggesting that the observed effect was mediated by AngII acting on its main receptor. Since the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes human ACE2 as the receptor for entry with subsequent downregulation of ACE2, corneal inflammation in Ace2-/- mice may have a similar mechanism with that in COVID-19 patients. Thus the Ace2-/- cornea, because of easy accessibility, may provide an attractive model to explore the molecular mechanisms, immunological changes, and treatment modalities in patients with COVID-19.
Assuntos
Enzima de Conversão de Angiotensina 2/genética , Córnea/patologia , Síndrome da Liberação de Citocina/fisiopatologia , Modelos Animais de Doenças , Angiotensina II/metabolismo , Animais , COVID-19 , Células Cultivadas , Quimiocinas/metabolismo , Células Epiteliais/metabolismo , Humanos , Interleucinas/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , SARS-CoV-2 , Células THP-1 , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Angiotensin-converting enzyme II (ACE2) is a homologue of angiotensin-converting enzyme discovered in 2000. From the initial discovery, it was recognized that the kidneys were organs very rich on ACE2. Subsequent studies demonstrated the precise localization of ACE2 within the kidney and the importance of this enzyme in the metabolism of Angiotensin II and the formation of Angiotensin 1-7. With the recognition early in 2020 of ACE2 being the main receptor of severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2), the interest in this protein has dramatically increased. In this review, we will focus on kidney ACE2; its localization, its alterations in hypertension, diabetes, the effect of ACE inhibitors and angiotensin type 1 receptor blockers (ARBs) on ACE2 and the potential use of ACE2 recombinant proteins therapeutically for kidney disease. We also describe the emerging kidney manifestations of COVID-19, namely the frequent development of acute kidney injury. The possibility that binding of SARS-CoV-2 to kidney ACE2 plays a role in the kidney manifestations is also briefly discussed.
Assuntos
Betacoronavirus/patogenicidade , Infecções por Coronavirus/enzimologia , Nefropatias/enzimologia , Rim/enzimologia , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/enzimologia , Receptores Virais/metabolismo , Injúria Renal Aguda/enzimologia , Injúria Renal Aguda/virologia , Enzima de Conversão de Angiotensina 2 , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Animais , Antivirais/uso terapêutico , Betacoronavirus/efeitos dos fármacos , COVID-19 , Infecções por Coronavirus/tratamento farmacológico , Infecções por Coronavirus/virologia , Diabetes Mellitus/enzimologia , Diabetes Mellitus/fisiopatologia , História do Século XXI , Interações Hospedeiro-Patógeno , Humanos , Hipertensão/enzimologia , Hipertensão/fisiopatologia , Rim/fisiopatologia , Nefropatias/tratamento farmacológico , Nefropatias/fisiopatologia , Pandemias , Peptidil Dipeptidase A/história , Peptidil Dipeptidase A/uso terapêutico , Pneumonia Viral/virologia , Receptores Virais/história , SARS-CoV-2 , Tratamento Farmacológico da COVID-19RESUMO
A new coronavirus, referred to as SARS-CoV-2, is responsible for the recent outbreak of severe respiratory disease. This outbreak first detected in Wuhan, China in December 2019, has spread to other regions of China and to 25 other countries as of January, 2020. It has been known since the 2003 SARS epidemic that the receptor critical for SARS-CoV entry into host cells is the angiotensin-converting enzyme 2 (ACE2). The S1 domain of the spike protein of SARS-CoV attaches the virus to its cellular receptor ACE2 on the host cells. We thought that it is timely to explain the connection between the SARS-CoV, SARS-CoV-2, ACE2 and the rationale for soluble ACE2 as a potential therapy.
Assuntos
Betacoronavirus/patogenicidade , Infecções por Coronavirus/tratamento farmacológico , Peptidil Dipeptidase A , Pneumonia Viral/tratamento farmacológico , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/patogenicidade , Ligação Viral , Enzima de Conversão de Angiotensina 2 , Animais , COVID-19 , Linhagem Celular , Haplorrinos , Humanos , Peptidil Dipeptidase A/fisiologia , Proteínas Recombinantes/uso terapêutico , SARS-CoV-2 , Solubilidade , Replicação Viral , Tratamento Farmacológico da COVID-19RESUMO
In this commentary we emphasize the renoprotective effect of cyclic angiotensin-(1-7) described by Cassis et al. in a mouse model of diabetic kidney disease. The importance of the study is that this peptide was even more protective than the angiotensin-converting enzyme inhibitor lisinopril administered alone and that when the 2 componds were combined, the renoprotective action was additive.
Assuntos
Diabetes Mellitus , Nefropatias Diabéticas , Angiotensina I , Inibidores da Enzima Conversora de Angiotensina , Animais , Rim , Lisinopril , Camundongos , Fragmentos de PeptídeosRESUMO
Angiotensin-converting enzyme 2 (ACE2) is a carboxypeptidase that potently degrades angiotensin II to angiotensin 1-7. Previous studies showed that injection of the enzymatic ectodomain of recombinant ACE2 (rACE2) markedly increases circulatory levels of ACE2 activity, and effectively lowered blood pressure in angiotensin II-induced hypertension. However, due to the short plasma half-life of rACE2, its therapeutic potential for chronic use is limited. To circumvent this, we generated a chimeric fusion of rACE2 and the immunoglobulin fragment Fc segment to increase its plasma stability. This rACE2-Fc fusion protein retained full peptidase activity and exhibited greatly extended plasma half-life in mice, from less than two hours of the original rACE2, to over a week. A single 2.5 mg/kg injection of rACE2-Fc increased the overall angiotensin II-conversion activities in blood by up to 100-fold and enhanced blood pressure recovery from acute angiotensin II induced hypertension seven days after administration. To assess rACE2-Fc given weekly on cardiac protection, we performed studies in mice continuously infused with angiotensin II for 28 days and in a Renin transgenic mouse model of hypertension. The angiotensin II infused mice achieved sustained blood pressure control and reduced cardiac hypertrophy and fibrosis. In chronic hypertensive transgenic mice, weekly injections of rACE2-Fc effectively lowered plasma angiotensin II and blood pressure. Additionally, rACE2-Fc ameliorated albuminuria, and reduced kidney and cardiac fibrosis. Thus, our chimeric fusion strategy for rACE2-Fc is suitable for future development of new renin angiotensin system-based inhibition therapies.
Assuntos
Hipertensão/tratamento farmacológico , Fragmentos Fc das Imunoglobulinas/uso terapêutico , Peptidil Dipeptidase A/uso terapêutico , Proteínas Recombinantes de Fusão/uso terapêutico , Angiotensina II/administração & dosagem , Angiotensina II/sangue , Enzima de Conversão de Angiotensina 2 , Animais , Linhagem Celular , Modelos Animais de Doenças , Feminino , Meia-Vida , Humanos , Hipertensão/etiologia , Fragmentos Fc das Imunoglobulinas/genética , Fragmentos Fc das Imunoglobulinas/isolamento & purificação , Fragmentos Fc das Imunoglobulinas/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Peptidil Dipeptidase A/genética , Peptidil Dipeptidase A/isolamento & purificação , Peptidil Dipeptidase A/farmacologia , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/isolamento & purificação , Proteínas Recombinantes de Fusão/farmacologia , Renina/genética , Sistema Renina-Angiotensina/efeitos dos fármacos , Resultado do TratamentoRESUMO
The pathways implicated in diabetic kidney disease (DKD) are largely derived from animal models. To examine if alterations in renin-angiotensin system (RAS) in humans are concordant with those in rodent models, we measured concentration of angiotensinogen (AOG), cathepsin D (CTSD), angiotensin-converting enzyme (ACE), and ACE2 and enzymatic activities of ACE, ACE2, and aminopeptidase-A in FVB mice 13-20 wk after treatment with streptozotocin (n = 9) or vehicle (n = 15) and people with long-standing type 1 diabetes, with (n = 37) or without (n = 81) DKD. In streptozotocin-treated mice, urine AOG and CTSD were 10.4- and 3.0-fold higher than in controls, respectively (P < 0.001). Enzymatic activities of ACE, ACE2, and APA were 6.2-, 3.2-, and 18.8-fold higher, respectively, in diabetic animals (P < 0.001). Angiotensin II was 2.4-fold higher in diabetic animals (P = 0.017). Compared with people without DKD, those with DKD had higher urine AOG (170 vs. 15 µg/g) and CTSD (147 vs. 31 µg/g). In people with DKD, urine ACE concentration was 1.8-fold higher (1.4 vs. 0.8 µg/g in those without DKD), while its enzymatic activity was 0.6-fold lower (1.0 vs. 1.6 × 109 RFU/g in those without DKD). Lower ACE activity, but not ACE protein concentration, was associated with ACE inhibitor (ACEI) treatment. After adjustment for clinical covariates, AOG, CTSD, ACE concentration, and ACE activity remained associated with DKD. In conclusion, in mice with streptozotocin-induced diabetes and in humans with DKD, urine concentrations and enzymatic activities of several RAS components are concordantly increased, consistent with enhanced RAS activity and greater angiotensin II formation. ACEI use was associated with a specific reduction in urine ACE activity, not ACE protein concentration, suggesting that it may be a marker of exposure to this widely-used therapy.
Assuntos
Diabetes Mellitus Experimental/urina , Diabetes Mellitus Tipo 1/urina , Nefropatias Diabéticas/urina , Enzimas/urina , Insuficiência Renal Crônica/urina , Sistema Renina-Angiotensina , Adulto , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Animais , Biomarcadores/urina , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/diagnóstico , Diabetes Mellitus Tipo 1/complicações , Diabetes Mellitus Tipo 1/diagnóstico , Nefropatias Diabéticas/diagnóstico , Nefropatias Diabéticas/etiologia , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Insuficiência Renal Crônica/diagnóstico , Insuficiência Renal Crônica/etiologia , Sistema Renina-Angiotensina/efeitos dos fármacos , Regulação para Cima , UrináliseRESUMO
Blockers of the renin-angiotensin system are effective in the treatment of experimental and clinical diabetic nephropathy. An approach different from blocking the formation or action of angiotensin II (1-8) that could also be effective involves fostering its degradation. Angiotensin-converting enzyme 2 (ACE2) is a monocarboxypeptidase that cleaves angiotensin II (1-8) to form angiotensin (1-7). Therefore, we examined the renal effects of murine recombinant ACE2 in mice with streptozotocin-induced diabetic nephropathy as well as that of amplification of circulating ACE2 using minicircle DNA delivery prior to induction of experimental diabetes. This delivery resulted in a long-term sustained and profound increase in serum ACE2 activity and enhanced ability to metabolize an acute angiotensin II (1-8) load. In mice with streptozotocin-induced diabetes pretreated with minicircle ACE2, ACE2 protein in plasma increased markedly and this was associated with a more than 100-fold increase in serum ACE2 activity. However, minicircle ACE2 did not result in changes in urinary ACE2 activity as compared to untreated diabetic mice. In both diabetic groups, glomerular filtration rate increased significantly and to the same extent as compared to non-diabetic controls. Albuminuria, glomerular mesangial expansion, glomerular cellularity, and glomerular size were all increased to a similar extent in minicircle ACE2-treated and untreated diabetic mice, as compared to non-diabetic controls. Recombinant mouse ACE2 given for 4 weeks by intraperitoneal daily injections in mice with streptozotocin-induced diabetic nephropathy also failed to improve albuminuria or kidney pathology. Thus, a profound augmentation of ACE2 confined to the circulation failed to ameliorate the glomerular lesions and hyperfiltration characteristic of early diabetic nephropathy. These findings emphasize the importance of targeting the kidney rather than the circulatory renin angiotensin system to combat diabetic nephropathy.
Assuntos
Diabetes Mellitus Experimental/complicações , Nefropatias Diabéticas/etiologia , Rim/enzimologia , Peptidil Dipeptidase A/sangue , Albuminúria/enzimologia , Albuminúria/etiologia , Albuminúria/genética , Angiotensina I/metabolismo , Angiotensina II/metabolismo , Enzima de Conversão de Angiotensina 2 , Animais , Autoantígenos/genética , Colágeno Tipo IV/deficiência , Colágeno Tipo IV/genética , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/enzimologia , Nefropatias Diabéticas/sangue , Nefropatias Diabéticas/enzimologia , Nefropatias Diabéticas/fisiopatologia , Feminino , Taxa de Filtração Glomerular , Rim/patologia , Rim/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fragmentos de Peptídeos/metabolismo , Peptidil Dipeptidase A/administração & dosagem , Peptidil Dipeptidase A/genética , Proteínas Recombinantes/administração & dosagem , Fatores de TempoRESUMO
Hypobicarbonatemia, or a reduced bicarbonate concentration in plasma, is a finding seen in 3 acid-base disorders: metabolic acidosis, chronic respiratory alkalosis and mixed metabolic acidosis and chronic respiratory alkalosis. Hypobicarbonatemia due to chronic respiratory alkalosis is often misdiagnosed as a metabolic acidosis and mistreated with the administration of alkali therapy. Proper diagnosis of the cause of hypobicarbonatemia requires integration of the laboratory values, arterial blood gas, and clinical history. The information derived from the urinary response to the prevailing acid-base disorder is useful to arrive at the correct diagnosis. We discuss the use of urine anion gap, as a surrogate marker of urine ammonium excretion, in the evaluation of a patient with low plasma bicarbonate concentration to differentiate between metabolic acidosis and chronic respiratory alkalosis. The interpretation and limitations of urine acid-base indexes at bedside (urine pH, urine bicarbonate, and urine anion gap) to evaluate urine acidification are discussed.
Assuntos
Acidose/diagnóstico , Alcalose Respiratória , Hiperventilação , Acidente Vascular Cerebral/complicações , Desequilíbrio Hidroeletrolítico , Idoso de 80 Anos ou mais , Alcalose Respiratória/sangue , Alcalose Respiratória/diagnóstico , Alcalose Respiratória/etiologia , Diagnóstico Diferencial , Gerenciamento Clínico , Feminino , Humanos , Concentração de Íons de Hidrogênio , Hiperventilação/sangue , Hiperventilação/etiologia , Desequilíbrio Hidroeletrolítico/sangue , Desequilíbrio Hidroeletrolítico/diagnóstico , Desequilíbrio Hidroeletrolítico/etiologiaRESUMO
Ogilvie's syndrome, or acute colonic pseudo-obstruction, is characterized by massive dilation of the colon without mechanical obstruction. Water and electrolytes often can be sequestered in the dilated intestinal loops resulting in profuse and watery diarrhea as well as hypokalemia. We report an anuric, end-stage renal disease (ESRD) patient undergoing peritoneal dialysis (PD) who developed acute colonic pseudo-obstruction causing a prolonged hospitalization. He also developed severe hypokalemia with a serum potassium (K+) as low as 2.4 mEq/L and required 180 - 240 mEq of potassium chloride per day for more than a month to correct it. While PD K+ losses often contribute to hypokalemia, the PD K+ loss was estimated to be only 39 mEq/day. Therefore, PD could only contribute modestly to the recalcitrant hypokalemia observed during the episode of pseudo-obstruction. It has been shown, however, that patients with colonic pseudo-obstruction have enhanced colonic K+ secretion. In addition, experimental studies in patients with chronic kidney disease (CKD) have demonstrated that colonic K+ excretion can be up to 3 times greater than in individuals with normal renal function. This increase may involve an upregulation of the large conductance K+ channel (maxi-K), also known as the BK channel, in the apical border of the colonocytes. We suggest that ESRD may have placed our patient at a greater risk of developing hypokalemia as his colon may have already adapted to secrete more K+. Clinicians should be aware of this extrarenal K+ wasting etiology in patients with colonic pseudo-obstruction, particularly in those with CKD where such a severe K+ deficit is not anticipated and, therefore, may inhibit more rigorous K+ replacement.