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Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have proven to delay diabetic kidney disease (DKD) progression on top of the standard of care with the renin-angiotensin system (RAS) blockade. The molecular mechanisms underlying the synergistic effect of SGLT2i and RAS blockers is poorly understood. We gave a SGLT2i (empagliflozin), an angiotensin-converting enzyme inhibitor (ramipril), or a combination of both drugs for 8 weeks to diabetic (db/db) mice. Vehicle-treated db/db and db/m mice were used as controls. At the end of the experiment, mice were killed, and the kidneys were saved to perform a differential high-throughput proteomic analysis by mass spectrometry using isobaric tandem mass tags (TMT labeling) that allow relative quantification of the identified proteins. The differential proteomic analysis revealed 203 proteins differentially expressed in one or more experimental groups (false discovery rate < 0.05 and Log2 fold change ≥ ±1). Fourteen were differentially expressed in the kidneys from the db/db mice treated with empagliflozin with ramipril. Among them, MAP17 was up-regulated. These findings were subsequently validated by Western blot. The combined therapy of empagliflozin and ramipril up-regulated MAP17 in the kidney of a diabetic mice model. MAP17 is a major scaffolding protein of the proximal tubular cells that places transporters together, namely SGLT2 and NHE3. Our results suggest that SGLT2i on top of RAS blockade may protect the kidney by boosting the inactivation of NHE3 via the up-regulation of key scaffolder proteins such as MAP17.
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Diabetes Mellitus Experimental , Nefropatias Diabéticas , Camundongos , Animais , Nefropatias Diabéticas/tratamento farmacológico , Nefropatias Diabéticas/metabolismo , Sistema Renina-Angiotensina , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Ramipril/farmacologia , Ramipril/uso terapêutico , Proteômica , Trocador 3 de Sódio-Hidrogênio/metabolismoRESUMO
Endothelin (ET) is found to be increased in kidney disease secondary to hyperglycaemia, hypertension, acidosis, and the presence of insulin or proinflammatory cytokines. In this context, ET, via the endothelin receptor type A (ETA) activation, causes sustained vasoconstriction of the afferent arterioles that produces deleterious effects such as hyperfiltration, podocyte damage, proteinuria and, eventually, GFR decline. Therefore, endothelin receptor antagonists (ERAs) have been proposed as a therapeutic strategy to reduce proteinuria and slow the progression of kidney disease. Preclinical and clinical evidence has revealed that the administration of ERAs reduces kidney fibrosis, inflammation and proteinuria. Currently, the efficacy of many ERAs to treat kidney disease is being tested in randomized controlled trials; however, some of these, such as avosentan and atrasentan, were not commercialized due to the adverse events related to their use. Therefore, to take advantage of the protective properties of the ERAs, the use of ETA receptor-specific antagonists and/or combining them with sodium-glucose cotransporter 2 inhibitors (SGLT2i) has been proposed to prevent oedemas, the main ERAs-related deleterious effect. The use of a dual angiotensin-II type 1/endothelin receptor blocker (sparsentan) is also being evaluated to treat kidney disease. Here, we reviewed the main ERAs developed and the preclinical and clinical evidence of their kidney-protective effects. Additionally, we provided an overview of new strategies that have been proposed to integrate ERAs in kidney disease treatment.
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Antagonistas dos Receptores de Endotelina , Nefropatias , Humanos , Bloqueadores do Receptor Tipo 1 de Angiotensina II/uso terapêutico , Antagonistas do Receptor de Endotelina A , Endotelina-1 , Endotelinas , Rim , Nefropatias/tratamento farmacológico , Proteinúria/tratamento farmacológico , Receptor de Endotelina ARESUMO
Treatments with sodium-glucose 2 cotransporter inhibitors (SGLT2i) or endothelin receptor antagonists (ERA) have shown cardiorenal protective effects. The present study aimed to evaluate the cardiorenal beneficial effects of the combination of SGLT2i and ERA on top of renin-angiotensin system (RAS) blockade. Type 2 diabetic mice (db/db) were treated with different combinations of an SGLT2i (empagliflozin), an ERA (atrasentan), and an angiotensin-converting enzyme inhibitor (ramipril) for 8 weeks. Vehicle-treated diabetic mice and non-diabetic mice were included as controls. Weight, blood glucose, blood pressure, and kidney and heart function were monitored during the study. Kidneys and heart were collected for histological examination and to study the intrarenal RAS. Treatment with empagliflozin alone or combined significantly decreased blood glucose compared to vehicle-treated db/db. The dual and triple therapies achieved significantly greater reductions in diastolic blood pressure than ramipril alone. Compared to vehicle-treated db/db, empagliflozin combined with ramipril or in triple therapy significantly prevented GFR increase, but only the triple combination exerted greater protection against podocyte loss. In the heart, empagliflozin alone or combined reduced cardiac isovolumetric relaxation time (IVRT) and left atrium (LA) diameter as compared to vehicle-treated db/db. However, only the triple therapy was able to reduce cardiomyocyte area. Importantly, the add-on triple therapy further enhanced the intrarenal ACE2/Ang(1-7)/Mas protective arm of the RAS. These data suggest that triple therapy with empagliflozin, atrasentan and ramipril show synergistic cardiorenal protective effects in a type 2 diabetic mouse model.
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Diabetes Mellitus Tipo 2 , Sistema Renina-Angiotensina , Camundongos , Animais , Transportador 2 de Glucose-Sódio , Atrasentana/farmacologia , Antagonistas dos Receptores de Endotelina/farmacologia , Glicemia , Ramipril/farmacologia , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Receptores de EndotelinaRESUMO
Data reproducibility and single-center bias are concerns in preclinical research and compromise translation from animal to human. Multicenter preclinical randomized controlled trials (pRCT) may reduce the gap between experimental studies and RCT and improve the predictability of results, for example Jak1/2 inhibition in lupus nephritis. To evaluate this, we conducted the first pRCT in the kidney domain at two Spanish and two German academic sites. Eligible MRL/MpJ-Faslpr mice (female, age13-14 weeks, stress scores of less than two and no visible tumor or signs of infection) were equally randomized to either oral treatment with the Jak1/2 inhibitor baricitinib or vehicle for four weeks. Central blinded histology analysis was performed at an independent fifth site. The primary endpoint was the urinary protein/creatinine ratio. Baricitinib treatment did not significantly affect proteinuria, histological markers of activity and chronicity, or the glomerular filtration rate but significantly improved plasma autoantibody levels and lymphadenopathy. Data heterogeneity was noted across the different centers referring in part to phenotype differences between MRL/MpJ-Faslpr mice bred at different sites, mimicking well patient phenotype diversity in lupus trials. Multicenter pRCT can overcome single-center bias at the cost of increasing variability and reducing effect size. Thus, our pRCT predicts a low effect size of baricitinib treatment on human lupus nephritis in heterogeneous study populations.
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Nefrite Lúpica , Animais , Modelos Animais de Doenças , Feminino , Humanos , Janus Quinase 1 , Rim , Nefrite Lúpica/tratamento farmacológico , Camundongos , Camundongos Endogâmicos MRL lpr , Camundongos Endogâmicos , Reprodutibilidade dos TestesRESUMO
Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have clearly demonstrated their beneficial effect in diabetic kidney disease (DKD) on top of the standard of care [blood glucose control, renin-angiotensin system blockade, smoking cessation and blood pressure (BP) control], even in patients with overt DKD. However, the indication of this drug class is still blood glucose lowering in type 2 diabetic patients with estimated glomerular filtration rate >45 mL/min/1.73 m2. Based on the new evidence, several scientific societies have emphasized the preferential prescription of SGLT2i for patients at risk of heart failure or kidney disease, but still within the limits set by health authorities. A rapid positioning of both the European Medicines Agency and the US Food and Drug Administration will allow patients with overt DKD to benefit from SGLT2i. Clinical experience suggests that SGLT2i safety management may in part mirror renin-angiotensin blockade safety management in patients with overt DKD. This review focuses on the rationale for an indication of SGTL2i in DKD. We further propose clinical steps for maximizing the safety of SGLT2i in DKD patients on other antidiabetic, BP or diuretic medication.
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Diabetes Mellitus Tipo 2/tratamento farmacológico , Nefropatias Diabéticas/prevenção & controle , Inibidores do Transportador 2 de Sódio-Glicose/uso terapêutico , Transportador 2 de Glucose-Sódio/química , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/patologia , Nefropatias Diabéticas/etiologia , Nefropatias Diabéticas/patologia , Humanos , PrognósticoRESUMO
Diabetes prevalence is constantly increasing and, nowadays, it affects more than 350 million people worldwide. Therefore, the prevalence of diabetic nephropathy (DN) has also increased, becoming the main cause of end-stage renal disease (ESRD) in the developed world. DN is characterized by albuminuria, a decline in glomerular filtration rate (GFR), hypertension, mesangial matrix expansion, glomerular basement membrane thickening, and tubulointerstitial fibrosis. The therapeutic advances in the last years have been able to modify and delay the natural course of diabetic kidney disease (DKD). Nevertheless, there is still an urgent need to characterize the pathways that are involved in DN, identify risk biomarkers and prevent kidney failure in diabetic patients. Rodent models provide valuable information regarding how DN is set and its progression through time. Despite the utility of these models, kidney disease progression depends on the diabetes induction method and susceptibility to diabetes of each experimental strain. The classical DN murine models (Streptozotocin-induced, Akita, or obese type 2 models) do not develop all of the typical DN features. For this reason, many models have been crossed to a susceptible genetic background. Knockout and transgenic strains have also been created to generate more robust models. In this review, we will focus on the description of the new DN rodent models and, additionally, we will provide an overview of the available methods for renal phenotyping.
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Nefropatias Diabéticas/patologia , Animais , Nefropatias Diabéticas/genética , Nefropatias Diabéticas/fisiopatologia , Modelos Animais de Doenças , Taxa de Filtração Glomerular , Humanos , Rim/patologia , Rim/fisiopatologia , Podócitos/patologiaRESUMO
PURPOSE OF REVIEW: The majority of end-stage renal disease including dialysis and kidney transplant patients are men. In contrast, the incidence of chronic kidney disease (CKD) is higher in women compared with men. In this review, we dissect the sex hormone levels and its effects on experimental models and patients with CKD. RECENT FINDINGS: Sex hormones are clearly involved in CKD progression to end-stage renal disease (ESRD). A significant reduction in lipid peroxidation as a mechanism of renoprotection has been observed in kidneys of streptozotocin (STZ)-diabetic ovariectomized rats after estradiol administration. Furthermore, a G-protein-coupled estrogen receptor inhibits podocyte oxidative stress maintaining the integrity of the mitochondrial membrane. Sex hormone depletion has been shown to modulate RAS system and protect against kidney injury in the male STZ-diabetic model. In human primary proximal tubular epithelial cells, a proteomic study showed that dihydrotestosterone dysregulated metabolic, suggesting that the deleterious effect of androgens within the kidney maybe related to altered energy metabolism in renal tubules. SUMMARY: Male gender is associated with worse CKD progression and this fact may be ascribed to sex hormone. Although male hormones exert a deleterious effect in terms of increasing oxidative stress, activating RAS system, and worsening fibrosis within the damaged kidney, female hormones exert a renoprotective effect.
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Hormônios Esteroides Gonadais/fisiologia , Insuficiência Renal Crônica/etiologia , Animais , Diabetes Mellitus Experimental/complicações , Metabolismo Energético , Hormônios Esteroides Gonadais/sangue , Humanos , Estresse Oxidativo/efeitos dos fármacos , Ratos , Insuficiência Renal Crônica/metabolismo , Fatores SexuaisRESUMO
Recurrence of idiopathic focal segmental glomerulosclerosis (FSGS) is a serious complication after kidney transplantation. FSGS relapse is suspected by a sudden increase in proteinuria but there is not an accurate noninvasive diagnostic tool to confirm this entity or to detect patients at risk. We aimed to validate the diagnostic performance of ApoA-Ib to detect FSGS relapses by measuring urinary ApoA-Ib in a retrospective cohort of 61 kidney transplanted patients (37 FSGS and 24 non-FSGS). In addition, to assess the ApoA-Ib predictive ability, ApoA-Ib was measured periodically in a prospective cohort of 13 idiopathic FSGS patients who were followed during 1 year after transplantation. ApoA-Ib had a sensitivity of 93.3% and a specificity of 90.9% to diagnose FSGS relapses, with a high negative predictive value (95.2%), confirming our previous results. In the prospective cohort, ApoA-Ib predated the recurrence in four of five episodes observed. In the nonrelapsing group (n = 9), ApoA-Ib was negative in 37 of 38 samples. ApoA-Ib has the potential to be a good diagnostic biomarker of FSGS relapses, providing a confident criterion to exclude false positives even in the presence of high proteinuria. It has also the potential to detect patients at risk of relapse, even before transplantation.
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Apolipoproteína A-I/urina , Glomerulosclerose Segmentar e Focal/diagnóstico , Transplante de Rim/efeitos adversos , Adulto , Biomarcadores , Feminino , Glomerulosclerose Segmentar e Focal/urina , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , RecidivaAssuntos
Glomerulosclerose Segmentar e Focal , Nefropatias , Apolipoproteína A-I , Criança , Humanos , Peso Molecular , ProteinúriaRESUMO
Introduction: Atypical hemolytic uremic syndrome (aHUS) is a complement system (CS)-mediated ultrarare disease that manifests as thrombotic microangiopathy (TMA) with preferential small kidney vessels involvement. Transient CS activation is also observed in secondary TMA or in patients at risk of developing aHUS. There is no gold standard test to monitor disease activity; however, the ex vivo C5b-9 deposition test seems to be a good approach. Methods: We assessed the C5b-9 deposition induced by serum samples of patients with aHUS (n = 8) and with TMA associated with kidney (n = 2), lung (n = 1) or hematopoietic stem cell (HSC) transplantation (HSCT, n = 2) during the acute phase of the disease or in remission. As control for transplant-associated TMA (TA-TMA), we analyzed samples of clinically stable kidney and HSC-transplanted patients without signs of TMA. In addition, we studied 1 child with genetic risk of aHUS during an acute infection. Results: In the acute disease phase or in patients with disease activity despite C5 blockade, a significant increase of C5b-9 deposition was detected. In all patients with clinical response to C5 blockade but one, levels of C5b-9 deposition were within the normal range. Finally, we detected increased C5b-9 deposition levels in an asymptomatic child with genetic risk of aHUS when a concomitant otitis episode was ongoing. Conclusion: The ex vivo C5b-9 deposition test is an auspicious tool to monitor CS activity in aHUS and TA-TMA. In addition, we demonstrate that the test may be useful to detect subclinical increase of CS activity, which expands the spectrum of patients that would benefit from a better CS activity assessment.
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BACKGROUND: Some studies have indicated that sodium-glucose cotransporter-2 (SGLT2) inhibitors promote an increase in cell iron use. OBJECTIVES: The aim of this study was to examine, in patients with stable heart failure with reduced left ventricular ejection fraction (HFrEF), the effect of dapagliflozin on ferrokinetic parameters and whether short-term changes in peak oxygen consumption (Vo2) after dapagliflozin treatment are influenced by baseline and serial ferrokinetic status. METHODS: This was an exploratory analysis of a randomized, double-blind clinical trial that evaluated the effect of dapagliflozin vs placebo on peak Vo2 in patients with HFrEF (NCT04197635) and included 76 of the 90 patients initially enrolled in the trial. Changes in peak Vo2 at 1 and 3 months were explored according to baseline and longitudinal ferrokinetic parameters (natural logarithm [ln] ferritin, transferrin saturation index [TSAT], soluble transferrin receptor, and hepcidin). Linear mixed-effect regression was used for the analyses. RESULTS: Compared with placebo, dapagliflozin led to a significant decrease in 3-month ln ferritin (P = 0.040) and an increase in 1-month ln soluble transferrin receptor (P = 0.023). Between-treatment comparisons revealed a stepwise increase in peak Vo2 in the dapagliflozin group at 1 and 3 months, which was especially apparent at lower baseline values of TSAT and ferritin (P < 0.05). Lower time-varying values of TSAT (1 and 3 months) also identified patients with greater improvements in peak Vo2. CONCLUSIONS: In patients with stable HFrEF, treatment with dapagliflozin resulted in short-term increases in peak Vo2, which were most marked in patients with surrogates of greater iron deficiency at baseline and during treatment. (Short-Term Effects of Dapagliflozin on Peak Vo2 in HFrEF [DAPA-VO2]; NCT04197635).
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Insuficiência Cardíaca , Função Ventricular Esquerda , Humanos , Volume Sistólico , Insuficiência Cardíaca/tratamento farmacológico , Ferro , Resultado do Tratamento , Ferritinas , Receptores da Transferrina/uso terapêuticoRESUMO
Mechanisms of cyclosporine A (CsA)-induced nephrotoxicity were generally thought to be hemodynamic in origin; however, there is now accumulating evidence of a direct tubular effect. Although genomic and proteomic experiments by our group and others provided overall information on genes and proteins up- or down-regulated by CsA in proximal tubule cells (PTC), a comprehensive view of events occurring after CsA exposure remains to be described. For this purpose, we applied a pharmacologic approach based on the use of known activities of a large panel of potentially protective compounds and evaluated their efficacy in preventing CsA toxicity in cultured mouse PTC. Our results show that compounds that blocked protein synthesis and apoptosis, together with the CK2 inhibitor DMAT and the PI3K inhibitor apigenin, were the most efficient in preventing CsA toxicity. We also identified GSK3, MMPs and PKC pathways as potential targets to prevent CsA damage. Additionally, heparinase-I and MAPK inhibitors afforded partial but significant protection. Interestingly, antioxidants and calcium metabolism-related compounds were unable to ameliorate CsA-induced cytotoxicity. Subsequent experiments allowed us to clarify the hierarchical relationship of targeted pathways after CsA treatment, with ER stress identified as an early effector of CsA toxicity, which leads to ROS generation, phenotypical changes and cell death. In summary, this work presents a novel experimental approach to characterizing cellular responses to cytotoxics while pointing to new targets to prevent CsA-induced toxicity in proximal tubule cells.
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Apoptose/efeitos dos fármacos , Ciclosporina/toxicidade , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Imunossupressores/toxicidade , Túbulos Renais Proximais/efeitos dos fármacos , Animais , Células Cultivadas , Quinase 3 da Glicogênio Sintase/metabolismo , Humanos , Túbulos Renais Proximais/patologia , Metaloproteinases da Matriz/metabolismo , Camundongos , Proteína Quinase C/metabolismo , Espécies Reativas de Oxigênio/metabolismoRESUMO
The reduction-oxidation (redox) system consists of the coupling and coordination of various electron gradients that are generated thanks to serial reduction-oxidation enzymatic reactions. These reactions happen in every cell and produce radical oxidants that can be mainly classified into reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS modulate cell-signaling pathways and cellular processes fundamental to normal cell function. However, overproduction of oxidative species can lead to oxidative stress (OS) that is pathological. Oxidative stress is a main contributor to diabetic kidney disease (DKD) onset. In the kidney, the proximal tubular cells require a high energy supply to reabsorb proteins, metabolites, ions, and water. In a diabetic milieu, glucose-induced toxicity promotes oxidative stress and mitochondrial dysfunction, impairing tubular function. Increased glucose level in urine and ROS enhance the activity of sodium/glucose co-transporter type 2 (SGLT2), which in turn exacerbates OS. SGLT2 inhibitors have demonstrated clear cardiovascular benefits in DKD which may be in part ascribed to the generation of a beneficial equilibrium between oxidant and antioxidant mechanisms.
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Nefropatias Diabéticas , Inibidores do Transportador 2 de Sódio-Glicose , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Nefropatias Diabéticas/metabolismo , Humanos , Rim/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Transportador 2 de Glucose-Sódio , Inibidores do Transportador 2 de Sódio-Glicose/farmacologiaRESUMO
A major complication of primary focal segmental glomerulosclerosis (FSGS) is its recurrence after kidney transplantation that happens in 30 to 40% of the patients. The diagnosis of these relapses is not always easy as the histological lesions are not highly specific and appear after the proteinuria increase. Currently, there are no accurate biomarkers to detect FSGS recurrence. Our group identified a modified form of Apolipoprotein A-I (ApoA-I), named ApoA-Ib, specifically present in the urine of recurrent FSGS patients after kidney transplantation. Aberrant forms of ApoA-I have also been described in the urine of native primary FSGS patients; this feature has been associated with prominent staining of ApoA-I at the apical membrane of the tubular cells. In this study, we aim to analyze the ApoA-I distribution in kidney allograft biopsies of recurrent FSGS patients. We detected ApoA-I by immunohistochemistry in kidney allograft biopsies of patients with FSGS relapse after kidney transplantation and in kidney allograft biopsies of patients with a disease different from FSGS in the native kidney (non-FSGS). In recurrent FSGS patients, ApoA-I was prominently localized at the brush border of the tubular cells, while in the non-FSGS patients, ApoA-I was found along the cytoplasm of the tubular cells. The localization of ApoA-I at the brush border of the tubular cells is a specific feature of primary FSGS in relapse. This suggests that ApoA-I staining in kidney biopsies, coupled with ApoA-Ib measurement in urine, could be used as a diagnostic tool of primary FSGS relapse after kidney transplantation due to its highly specific tubular distribution.
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BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the current coronavirus disease 2019 (COVID-19). The main organ affected in this infection is the lung and the virus uses the angiotensin-converting enzyme 2 (ACE2) as a receptor to enter the target cells. In this context, a controversy raised regarding the use of renin-angiotensin system (RAAS) blockers, as these drugs might increase ACE2 expression in some tissues and potentially increase the risk for SARS-CoV-2 infection. This is specially concerning in diabetic patients as diabetes is a risk factor for COVID-19. METHODS: 12-week old diabetic mice (db/db) were treated with ramipril, or vehicle control for 8 weeks. Non-diabetic db/m mice were included as controls. ACE2 expression and activity were studied in lung, kidney and heart of these animals. RESULTS: Kidney ACE2 activity was increased in the db/db mice as compared to the db/m (143.2% ± 23% vs 100% ± 22.3%, p = 0.004), whereas ramipril had no significant effect. In the lung, no differences were found in ACE2 when comparing db/db mice to db/m and ramipril also had no significant effect. In the heart, diabetes decreased ACE2 activity (83% ± 16.8%, vs 100% ± 23.1% p = 0.02), and ramipril increased ACE2 significantly (83% ± 16.8% vs 98.2% ± 15%, p = 0.04). CONCLUSIONS: In a mouse model of type 2 diabetes, ramipril had no significant effect on ACE2 activity in either kidneys or in the lungs. Therefore, it is unlikely that RAAS blockers or at least angiotensin-converting enzyme inhibitors increase the risk of SARS-CoV-2 infection through increasing ACE2.
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Enzima de Conversão de Angiotensina 2/metabolismo , Tratamento Farmacológico da COVID-19 , Diabetes Mellitus Experimental/tratamento farmacológico , Rim/metabolismo , Pulmão/metabolismo , Miocárdio/metabolismo , Ramipril/farmacologia , SARS-CoV-2/metabolismo , Enzima de Conversão de Angiotensina 2/genética , Animais , COVID-19/enzimologia , COVID-19/genética , COVID-19/patologia , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Rim/patologia , Rim/virologia , Pulmão/patologia , Pulmão/virologia , Masculino , Camundongos , Camundongos Mutantes , Especificidade de Órgãos/efeitos dos fármacos , Especificidade de Órgãos/genética , SARS-CoV-2/genéticaRESUMO
Primary or idiopathic focal segmental glomerulosclerosis (FSGS) is a kidney entity that involves the podocytes, leading to heavy proteinuria and in many cases progresses to end-stage renal disease. Idiopathic FSGS has a bad prognosis, as it involves young individuals who, in a considerably high proportion (â¼15%), are resistant to corticosteroids and other immunosuppressive treatments as well. Moreover, the disease recurs in 30-50% of patients after kidney transplantation, leading to graft function impairment. It is suspected that this relapsing disease is caused by a circulating factor(s) that would permeabilize the glomerular filtration barrier. However, the exact pathologic mechanism is an unsettled issue. Besides its poor outcome, a major concern of primary FSGS is the complexity to confirm the diagnosis, as it can be confused with other variants or secondary forms of FSGS and also with other glomerular diseases, such as minimal change disease. New efforts to optimize the diagnostic approach are arising to improve knowledge in well-defined primary FSGS cohorts of patients. Follow-up of properly classified primary FSGS patients will allow risk stratification for predicting the response to different treatments. In this review we will focus on the diagnostic algorithm used in idiopathic FSGS both in native kidneys and in disease recurrence after kidney transplantation. We will emphasize those potential confusing factors as well as their detection and prevention. In addition, we will also provide an overview of ongoing studies that recruit large cohorts of glomerulopathy patients (Nephrotic Syndrome Study Network and Cure Glomerulonephropathy, among others) and the experimental studies performed to find novel reliable biomarkers to detect primary FSGS.
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Around the world diabetic kidney disease (DKD) is the main cause of chronic kidney disease (CKD), which is characterized by mesangial expansion, glomerulosclerosis, tubular atrophy, and interstitial fibrosis. The hallmark of the pathogenesis of DKD is an increased extracellular matrix (ECM) accumulation causing thickening of the glomerular and tubular basement membranes, mesangial expansion, sclerosis, and tubulointerstitial fibrosis. The matrix metalloproteases (MMPs) family are composed of zinc-dependent enzymes involved in the degradation and hydrolysis of ECM components. Several MMPs are expressed in the kidney; nephron compartments, vasculature and connective tissue. Given their important role in DKD, several studies have been performed in patients with DKD proposing that the measurement of their activity in serum or in urine may become in the future markers of early DKD. Studies from diabetic nephropathy experimental models suggest that a balance between MMPs levels and their inhibitors is needed to maintain renal homeostasis. This review focuses in the importance of the MMPs within the kidney and their modifications at the circulation, kidney and urine in patients with DKD. We also cover the most important studies performed in experimental models of diabetes in terms of MMPs levels, renal expression and its down-regulation effect.
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Hospital admissions and mortality from the Coronavirus disease 2019 (COVID-19) pandemic are spreading throughout the world, and second and third waves are thought to be likely. Risk factors for severe COVID-19 include diabetes, chronic kidney disease and cardiovascular disease. Currently, there is no vaccine and no approved therapy. Therapeutic approaches are aimed at preventing viral replication and spread, limiting the impact of the inflammatory overdrive (cytokine storm), preventing thromboembolic complications and replacing or supporting organ function. However, despite organ support, mortality is currently 65% for those receiving advanced respiratory support and 78% for those requiring renal replacement therapies. Thus, efforts should be made to provide adjuvant organ protection therapy. This may imply novel therapies in clinical development (e.g., the Fas ligand trap asunercept), but uptake of repurposed drugs already in clinical use may be faster. In this regard, sodium glucose co-transporter-2 (SGLT2) inhibitors were recently shown to protect the heart and kidney both within and outside of a diabetic milieu context. Further, preclinical data support a beneficial effect for the lung. We now discuss the potential benefits and risks of SGLT2 inhibitors in COVID-19 and an ongoing clinical trial testing the impact of dapagliflozin on outcomes in COVID-19 patients with respiratory failure.
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Apolipoprotein A-Ib (ApoA-Ib) is a high molecular weight form of Apolipoprotein A-I (ApoA-I) found specifically in the urine of kidney-transplanted patients with recurrent idiopathic focal segmental glomerulosclerosis (FSGS). To determine the nature of the modification present in ApoA-Ib, we sequenced the whole APOA1 gene in ApoA-Ib positive and negative patients, and we also studied the protein primary structure using mass spectrometry. No genetic variations in the APOA1 gene were found in the ApoA-Ib positive patients that could explain the increase in its molecular mass. The mass spectrometry analysis revealed three extra amino acids at the N-Terminal end of ApoA-Ib that were not present in the standard plasmatic form of ApoA-I. These amino acids corresponded to half of the propeptide sequence of the immature form of ApoA-I (proApoA-I) indicating that ApoA-Ib is a misprocessed form of proApoA-I. The description of ApoA-Ib could be relevant not only because it can allow the automated analysis of this biomarker in the clinical practice but also because it has the potential to shed light into the molecular mechanisms that cause idiopathic FSGS, which is currently unknown.