Expression of Smac/Diablo in tubular epithelial cells and during acute renal failure

Expression of Smac/Diablo in tubular epithelial cells and during acute renal failure.BackgroundApoptosis contributes to tubular cell loss in the course of renal injury. However, the mechanisms regulating tubular cell apoptosis are not well understood. Smac/Diablo is a mitochondrial protein that is released to the cytosol during apoptosis, where it blocks the antiapoptotic activity of inhibitor of apoptosis proteins (IAPs).MethodsWe have studied the regulation of Smac/Diablo mRNA and protein expression in murine toxic acute tubular necrosis, and in cultured tubular epithelial cells exposed to the lethal cytokine tumor necrosis factor (TNF).ResultsFolic acid–induced acute renal failure was associated with tubular cell apoptosis. Smac/Diablo mRNA and protein levels increased by 50% at 24 hours. TNF, a cytokine whose renal expression increases in folic acid nephropathy, induced apoptosis in cultured tubular epithelial cells in a time-dependent manner. In addition, TNF increased the mRNA and protein expression of Smac/Diablo.ConclusionThese findings support the concept that regulation of Smac/Diablo mRNA and protein expression is a mechanism by which lethal stimuli amplify their lethal potential in renal cells

Tight blood pressure control decreases apoptosis during renal damage

Tight blood pressure control decreases apoptosis during renal damage.BackgroundAn excess rate of apoptosis could lead to the gradual loss of renal mass. In this study, we investigated the role of apoptosis in the renal damage secondary to hypertension.MethodsSpontaneously hypertensive rats with 5/6 renal mass reduction (subtotal nephrectomy) were distributed to receive no-treatment, 200mg/L quinapril, 360mg/L losartan, or triple therapy (200mg/L hydralazine, 4mg/L reserpine, and 100mg/L hydrochlorothiazide) for 5weeks. Sham-operated spontaneously hypertensive rats served as controls. Age-matched Wistar-Kyoto (WKY) rats, with or without subtotal nephrectomy, were also studied.ResultsNontreated spontaneously hypertensive rats + subtotal nephrectomy developed proteinuria, glomerular sclerosis, and tubulointerstitial lesions. In comparison to spontaneously hypertensive rats, an increment in the number of [proliferating cell nuclear antigen (PCNA)]-positive and apoptotic [terminal deoxynucleotidyl transferase (Tdt)-mediated deoxyuridine triphosphate biotin nick end labeling (TUNEL)]-positive tubular and glomerular cells was observed. By contrast, WKY + subtotal nephrectomy rats showed less severe morphologic lesions, and only the number of proliferating cells increased. By Western blot, an up-regulation of renal Bax (apoptosis inducer) was noted both in spontaneously hypertensive rats + subtotal nephrectomy and WKY + subtotal nephrectomy rats. By contrast, Bcl-xL (apoptosis protector) was up-regulated in WKY + subtotal nephrectomy rats but not in spontaneously hypertensive rats + subtotal nephrectomy. The administration of appropriate doses of quinapril, losartan, or triple therapy to spontaneously hypertensive rats + subtotal nephrectomy normalized systolic blood pressure, partially prevented proteinuria, renal lesions and apoptosis, and decreased Bax, but no changes were noted in Bcl-xL. The Bax/Bcl-xL index was significantly increased in spontaneously hypertensive rats + subtotal nephrectomy compared to sham-operated spontaneously hypertensive rats and decreased in treated groups.ConclusionThe combination of renal mass reduction and hypertension caused severe renal lesions associated to an increment of apoptosis rate, mainly in tubular epithelial cells. Tight blood pressure control decreased the apoptosis rate and morphologic lesions. These studies suggest that changes in the expression of apoptosis-regulatory genes contribute to the progressive damage in hypertensive rats with renal mass reduction

The interaction between mitochondrial oxidative stress and gut microbiota in the cardiometabolic consequences in diet-induced obese rats

Background: The objective of this study is to determine the role of mitochondrial oxidative stress in the dysbiosis associated with a high fat diet in rats. In addition, the impact of gut microbiota (GM) in the cardiometabolic consequences of diet-induced obesity in rats has been evaluated. Methods: Male Wistar rats were fed either a high fat diet (HFD) or a control (CT) one for 6 weeks. At the third week, one-half of the animals of each group were treated with the mitochondrial antioxidant MitoTempo (MT; 0.7 mgKg−1 day−1 i.p). Results: Animals fed an HFD showed a lower microbiota evenness and diversity in comparison to CT rats. This dysbiosis is characterized by a decrease in Firmicutes/Bacteroidetes ratio and relevant changes at family and genera compared with the CT group. This was accompanied by a reduction in colonic mucin-secreting goblet cells. These changes were reversed by MT treatment. The abundance of certain genera could also be relevant in the metabolic consequences of obesity, as well as in the occurrence of cardiac fibrosis associated with obesity. Conclusions: These results support an interaction between GM and mitochondrial oxidative stress and its relation with development of cardiac fibrosis, suggesting new approaches in the management of obesity-related cardiometabolic consequences.This work was supported by Instituto de Salud Carlos III-Fondo Europeo de Desarrollo Regional (FEDER) (PI18/00257; CIBERCV) a way to build Europe, Ministerio de Economía y Competitividad (SAF2016-81063). EMM was supported by a contract from CAM (Atracción de talento). BG was funded by the FPI Program from the Government of Castilla y León (co-funded by FSE)

Comparison of oxidative stress markers in HIV-infected patients on efavirenz or atazanavir/ritonavir-based therapy

Introduction Chronic low‐grade inflammation and immune activation may persist in HIV patients despite effective antiretroviral therapy (ART). These abnormalities are associated with increased oxidative stress (OS). Bilirubin (BR) may have a beneficial role in counteracting OS. Atazanavir (ATV) inhibits UGT1A1, thus increasing unconjugated BR levels, a distinctive feature of this drug. We compared changes in OS markers in HIV patients on ATV/r versus efavirenz (EFV)‐based first‐line therapies. Materials and Methods Cohort of the Spanish Research Network (CoRIS) is a multicentre, open, prospective cohort of HIV‐infected patients naïve to ART at entry and linked to a biobank. We identified hepatitis C virus/hepatitis B virus (HCV/HBV) negative patients who started first‐line ART with either ATV/r or EFV, had a baseline biobank sample and a follow‐up sample after at least nine months of ART while maintaining initial regimen and being virologically suppressed. Lipoprotein‐associated Phospholipase A2 (Lp‐PLA2), Myeloperoxidase (MPO) and Oxidized LDL (OxLDL) were measured in paired samples. Marker values at one year were interpolated from available data. Multiple imputations using chained equations were used to deal with missing values. Change in the OS markers was modelled using multiple linear regressions adjusting for baseline marker values and baseline confounders. Correlations between continuous variables were explored using Pearson's correlation tests. Results 145 patients (97 EFV; 48 ATV/r) were studied. Mean (SD) baseline values for OS markers in EFV and ATV/r groups were: Lp‐PLA2 [142.2 (72.8) and 150.1 (92.8) ng/mL], MPO [74.3 (48.2) and 93.9 (64.3) µg/L] and OxLDL [76.3 (52.3) and 82.2 (54.4) µg/L]. After adjustment for baseline variables patients on ATV/r had a significant decrease in Lp‐PLA2 (estimated difference −16.3 [CI 95%: −31.4, −1.25; p=0.03]) and a significantly lower increase in OxLDL (estimated difference −21.8 [−38.0, −5.6; p<0.01] relative to those on EFV, whereas no differences in MPO were found. Adjusted changes in BR were significantly higher for the ATV/r group (estimated difference 1.33 [1.03, 1.52; p<0.01]). Changes in BR and changes in OS markers were significantly correlated. Conclusions In virologically suppressed patients on stable ART, OS was lower in ATV/r‐based regimens compared to EFV. We hypothesize these changes could be in part attributable to increased BR plasma levels

Comparison of oxidative stress markers in HIV-infected patients on efavirenz or atazanavir/ritonavir-based therapy

INTRODUCTION: Chronic low-grade inflammation and immune activation may persist in HIV patients despite effective antiretroviral therapy (ART). These abnormalities are associated with increased oxidative stress (OS). Bilirubin (BR) may have a beneficial role in counteracting OS. Atazanavir (ATV) inhibits UGT1A1, thus increasing unconjugated BR levels, a distinctive feature of this drug. We compared changes in OS markers in HIV patients on ATV/r versus efavirenz (EFV)-based first-line therapies. MATERIALS AND METHODS: Cohort of the Spanish Research Network (CoRIS) is a multicentre, open, prospective cohort of HIV-infected patients naïve to ART at entry and linked to a biobank. We identified hepatitis C virus/hepatitis B virus (HCV/HBV) negative patients who started first-line ART with either ATV/r or EFV, had a baseline biobank sample and a follow-up sample after at least nine months of ART while maintaining initial regimen and being virologically suppressed. Lipoprotein-associated Phospholipase A2 (Lp-PLA2), Myeloperoxidase (MPO) and Oxidized LDL (OxLDL) were measured in paired samples. Marker values at one year were interpolated from available data. Multiple imputations using chained equations were used to deal with missing values. Change in the OS markers was modelled using multiple linear regressions adjusting for baseline marker values and baseline confounders. Correlations between continuous variables were explored using Pearson's correlation tests. RESULTS: 145 patients (97 EFV; 48 ATV/r) were studied. Mean (SD) baseline values for OS markers in EFV and ATV/r groups were: Lp-PLA2 [142.2 (72.8) and 150.1 (92.8) ng/mL], MPO [74.3 (48.2) and 93.9 (64.3) µg/L] and OxLDL [76.3 (52.3) and 82.2 (54.4) µg/L]. After adjustment for baseline variables patients on ATV/r had a significant decrease in Lp-PLA2 (estimated difference -16.3 [CI 95%: -31.4, -1.25; p=0.03]) and a significantly lower increase in OxLDL (estimated difference -21.8 [-38.0, -5.6; p<0.01] relative to those on EFV, whereas no differences in MPO were found. Adjusted changes in BR were significantly higher for the ATV/r group (estimated difference 1.33 [1.03, 1.52; p<0.01]). Changes in BR and changes in OS markers were significantly correlated. CONCLUSIONS: In virologically suppressed patients on stable ART, OS was lower in ATV/r-based regimens compared to EFV. We hypothesize these changes could be in part attributable to increased BR plasma levels.S

Participación de la endotelina en la patogenia del daño glomerular. Estudios in vitro e in vivo

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 27-5-199

An orally active ETA/ETB receptor antagonist ameliorates proteinuria and glomerular lesions in rats with proliferative nephritis

An orally active ETA/ETB receptor antagonist ameliorates proteinuria and glomerular lesions in rats with proliferative nephritis. The proliferation of mesangial cells and the extracellular matrix expansion constitute the most outstanding morphological aspects of the majority of progressive glomerular diseases. In vitro, endothelin-1 (ET-1) is mitogenic for mesangial cells and induces matrix protein synthesis. We studied the possible participation of ET-1 in the pathogenesis of renal damage in a normotensive model of proliferative nephritis. Coincidentally with maximal proteinuria and glomerular lesions, an increase was found in the glomerular mRNA expression of preproET-1 and the ETA receptor (10 and 6 times compared to controls, respectively), but not of the ETB receptor, and in ET-1 urinary excretion (217 ± 33 vs. 84 ± 4pg ET-1/24 hr, N = 4 to 5, P < 0.05). By in situ hybridization, an increase in preproET-1 mRNA expression in glomerular endothelial, epithelial and mesangial cells, and in some tubular cells was observed. The administration of bosentan, an ETA/ETB receptor antagonist, had a beneficial effect on the evolution of nephritis, preventing the appearance of intense proteinuria (76 ± 35 vs. 380 ± 77 mg/24 hr, N = 4 to 5, P < 0.05), the morphological lesions and the renal function impairment (creatinine clearance 367 ± 46 vs. 268 ± 33 µ1/min/100 g, N = 4 to 5). Simultaneously, there was a decrease in ET-1 urinary excretion (88 ± 14 vs. 217 ± 33 pgET-1/24 hr, N = 4,5, P < 0.05) and in the renal preproET-1 mRNA expression. The mean systolic blood pressures remained in the normal range in all animals. These data indicate that ET-1 participates in the pathogenesis of proteinuria and glomerular injury in a model of proliferative nephritis. The nonpeptidic orally active ETA/ETB receptor antagonists could be useful in the treatment of some human nephritis

Persistent Proteinuria Up-Regulates Angiotensin II Type 2 Receptor and Induces Apoptosis in Proximal Tubular Cells

Apoptosis is implicated in the progressive cell loss and fibrosis both at glomerular and tubulointerstitial level. In this study, we examined the potential mechanisms by which persistent proteinuria (protein-overload model) could induce apoptosis. After uninephrectomy (UNX), Wistar rats received daily injections of 0.5 g of bovine serum albumin (BSA)/100 g body weight or saline. Both at day 8 and day 28, rats receiving BSA had proteinuria and renal lesions characterized by tubular atrophy and/or dilation and mononuclear cell infiltration. In relation to control-UNX rats, renal cortex of nephritic rats showed an increment in AT2 mRNA (reverse transcriptase-polymerase chain reaction) and protein (Western blot) expression. In both groups, AT2 receptor immunostaining was mainly localized in proximal tubular cells. Rats with persistent proteinuria showed a significantly increased number of terminal dUTP nick-end labeling positive apoptotic cells compared with UNX-controls, both in glomeruli and tubulointerstitium. Double staining for apoptosis and AT2 receptor showed that most terminal dUTP nick-end labeling positive cells were found in tubules expressing AT2 receptor. Using an antibody that recognizes the active form caspase-3, we observed an increment in caspase-3 activation in rats receiving BSA with respect to those receiving saline. Rats with persistent proteinuria showed a diminution in the phosphorylation of Bcl-2 with respect to UNX-controls both at day 8 and day 28. By contrast, no changes were observed either in the Bax or in the Bcl-2 protein levels. The administration of BSA to UNX rats induced a diminution in the phosphorylation of ERK with respect to UNX-control at all times studied. The changes observed in ERK activities took place without alterations of ERK1/2 protein levels. In summary, our data suggest that persistent proteinuria causes apoptosis in tubular cells through the activation of AT2 receptor, which can, in turn, inhibit MAP kinase (ERK1/2) activation and Bcl-2 phosphorylation

Relación entre la cuantificación de calcio coronario y la composición de la microbiota intestinal en sujetos sin enfermedad cardiovascular previa: estudio piloto

[Aim]: To investigate the relationship between gut microbiota composition and the presence of coronary atherosclerosis assessed by coronary artery calcium (CAC) quantification in individuals without previous cardiovascular disease (CVD). [Methods]: We included 20 patients over 18 years of age with no history of CVD who underwent multiple detector-computed tomography. From each patient, a stool sample was obtained to characterize gut microbiota composition by sequencing bacterial 16S ribosomal RNA gene. In addition, circulating levels of TNF-α and IL-1β, as well as trimethylamine N-oxide (TMAO) were determined in plasma samples by automated ELISA and capillary gas chromatography-mass spectrometry, respectively. [Results]: The mean age of patients was 63.5 years and 60% were women. Half of patients had CAC >100 (Agatston score), and were characterized by a higher abundance of the phylum Proteobacteria, mainly of bacteria belonging to the families Enterobacteriaceae and than patients with a CAC ≤ 100. Moreover, bacterial genera identified as biomarkers, such as Enterobacter, Escherichia/Shigella y Klebsiella, were positively associated with inflammation levels and with TMAO production. [Conclusion]: Our data shows a gut microbiota profile associated with the presence of coronary calcium in patients without previous CVD. Although there are no strategies to decrease the amount of coronary calcium, gut microbiota is highly malleable by several factors. The possibility of preventing and even intervening CVD progression through strategies targeted gut microbiota is a very attractive idea that deserves further studies.[Objetivo]: Determinar si existe alguna asociación entre el perfil de microbiota intestinal y la carga aterosclerótica global medida mediante cuantificación de calcio coronario (CCC) en sujetos sin antecedentes de enfermedad cardiovascular (ECV). [Métodos]: Se incluyeron 20 pacientes mayores de edad, sin antecedentes de ECV a los que se les hizo la CCC mediante tomografía computarizada multicorte. Además, se les recogió una muestra de heces para caracterizar la composición de la microbiota intestinal mediante la secuenciación del gen 16S RNAr con técnicas de secuenciación masiva y una muestra de sangre para la cuantificación de citoquinas proinflamatorias, mediante ELISA específicos, y del metabolito bacteriano N-óxido de trimetilamina (TMAO) por cromatografía de gases/líquidos acoplada a espectrometría de masas en tándem. [Resultados]: La media de edad fue de 63,5 años y un 60% eran mujeres. La mitad de los pacientes (n = 10) presentaron una CCC >100 y se caracterizaron por una mayor abundancia de bacterias del filo Proteobacteria, pertenecientes principalmente a las familias Enterobacteriaceae y Pasteurellaceae, que los pacientes con CCC ≤ 100. La mayoría de los géneros bacterianos identificados, Enterobacter, Escherichia/Shigella, Klebsiella, Citrobacter y Salmonella, se asociaron positivamente con los niveles plasmáticos de TNF-α o IL-1β y con la producción de TMAO. [Conclusión]: Los resultados de este estudio piloto muestran un perfil de microbiota intestinal asociado a la presencia de CCC >100 en pacientes sin ECV previa, caracterizado por un aumento en la proporción de géneros bacterianos productores de TMAO. Puesto que la composición de la microbiota intestinal es altamente modulable por diversos factores, es posible que, en un futuro, podamos prevenir, e incluso intervenir, la enfermedad cardiovascular mediante estrategias nutricionales.Este trabajo ha sido parcialmente financiado con una Beca Fundación Española de Arteriosclerosis (FEA)/Sociedad Española de Arteriosclerosis (SEA) 2016 para Investigación Básica, concedida durante el XXIX Congreso Nacional SEA celebrado en Granada del 18 al 20 de mayo de 2016