HIF1α-dependent uncoupling of glycolysis suppresses tumor cell proliferation.

Hypoxia-inducible factor-1α (HIF1α) attenuates mitochondrial activity while promoting glycolysis. However, lower glycolysis is compromised in human clear cell renal cell carcinomas, in which HIF1α acts as a tumor suppressor by inhibiting cell-autonomous proliferation. Here, we find that, unexpectedly, HIF1α suppresses lower glycolysis after the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) step, leading to reduced lactate secretion in different tumor cell types when cells encounter a limited pyruvate supply such as that typically found in the tumor microenvironment in vivo. This is because HIF1α-dependent attenuation of mitochondrial oxygen consumption increases the NADH/NAD+ ratio that suppresses the activity of the NADH-sensitive GAPDH glycolytic enzyme. This is manifested when pyruvate supply is limited, since pyruvate acts as an electron acceptor that prevents the increment of the NADH/NAD+ ratio. Furthermore, this anti-glycolytic function provides a molecular basis to explain how HIF1α can suppress tumor cell proliferation by increasing the NADH/NAD+ ratio.

Erythroid SLC7A5/SLC3A2 amino acid carrier controls red blood cell size and maturation.

Inhibition of the heterodimeric amino acid carrier SLC7A5/SLC3A2 (LAT1/CD98) has been widely studied in tumor biology but its role in physiological conditions remains largely unknown. Here we show that the SLC7A5/SLC3A2 heterodimer is constitutively present at different stages of erythroid differentiation but absent in mature erythrocytes. Administration of erythropoietin (EPO) further induces SLC7A5/SLC3A2 expression in circulating reticulocytes, as it also occurs in anemic conditions. Although Slc7a5 gene inactivation in the erythrocyte lineage does not compromise the total number of circulating red blood cells (RBCs), their size and hemoglobin content are significantly reduced accompanied by a diminished erythroblast mTORC1 activity. Furthermore circulating Slc7a5-deficient reticulocytes are characterized by lower transferrin receptor (CD71) expression as well as mitochondrial activity, suggesting a premature transition to mature RBCs. These data reveal that SLC7A5/SLC3A2 ensures adequate maturation of reticulocytes as well as the proper size and hemoglobin content of circulating RBCs.

Unique expression of the atypical mitochondrial subunit NDUFA4L2 in cerebral pericytes fine tunes HIF activity in response to hypoxia.

A central response to insufficient cerebral oxygen delivery is a profound reprograming of metabolism, which is mainly regulated by the Hypoxia Inducible Factor (HIF). Among other responses, HIF induces the expression of the atypical mitochondrial subunit NDUFA4L2. Surprisingly, NDUFA4L2 is constitutively expressed in the brain in non-hypoxic conditions. Analysis of publicly available single cell transcriptomic (scRNA-seq) data sets coupled with high-resolution multiplexed fluorescence RNA in situ hybridization (RNA F.I.S.H.) revealed that in the murine and human brain NDUFA4L2 is exclusively expressed in mural cells with the highest levels found in pericytes and declining along the arteriole-arterial smooth muscle cell axis. This pattern was mirrored by COX4I2, another atypical mitochondrial subunit. High NDUFA4L2 expression was also observed in human brain pericytes in vitro, decreasing when pericytes are muscularized and further induced by HIF stabilization in a PHD2/PHD3 dependent manner. In vivo, Vhl conditional inactivation in pericyte targeting Ng2-cre transgenic mice dramatically induced NDUFA4L2 expression. Finally NDUFA4L2 inactivation in pericytes increased oxygen consumption and therefore the degree of HIF pathway induction in hypoxia. In conclusion our work reveals that NDUFA4L2 together with COX4I2 is a key hypoxic-induced metabolic marker constitutively expressed in pericytes coupling mitochondrial oxygen consumption and cellular hypoxia response.

Minimal invasive surgery for multiple adhesive small bowel obstruction: Results of a comparative multicenter study.

AIM OF THE STUDY: Laparoscopic adhesiolysis in small bowel obstruction (SBO) is getting increasingly normal. In patients with multiple adhesive SBOs (MASBO), laparoscopic approaches might increase the risk of bowel injury due to the distended and potentially compromised small bowel. It remains a challenge to the surgeons, entails an interdisciplinary team, trying to achieve the least complications as possible. The study aimed to compare surgical outcomes of laparoscopic procedures (multi-port vs. single-port) in the management of MASBO. PATIENTS AND METHODS: Comparative study of 68 patients with post-operative MASBO treated with Single-Port single incision laparoscopic surgery (SILS) and Multi-port Laparoscopic Surgery in two centers of Bogota, Colombia between January 2013 and June 2018. RESULTS: All patients underwent laparoscopic management, 27 patients by SILS, and 41 patients by multi-port. The average surgical time in the multiport approach was 167 min versus SILS with 129 min. Laparoscopic intestinal resection was performed in 4.4% of patients, through multi-port using intracorporeal anastomosis. Mean hospital stay of 3.2 days for the SILS approach versus multi-port in 2.2 days. CONCLUSIONS: Both laparoscopic approaches, in MASBO treatment is feasible in qualified hands. Patient selection and medical judgment seem to be the most essential factors for a positive result.

OBJETIVOS DEL ESTUDIO: Cada día es más frecuente la adherensiolisis laparoscópica en obstrucción del intestino delgado. En pacientes con obstrucciones debidas a múltiples adherencias del intestino delgado (OMAID), los abordajes laparoscópicos pueden incrementar el riesgo de daño de víscera hueca debido a la presencia de asas distendidas. Continúa siendo un reto para el cirujano, requiriendo un grupo interdisciplinario para disminuir las posibles complicaciones. Este estudio busca comparar los desenlaces de abordajes laparoscópicos (Multipuerto vs. monopuerto) en el manejo del OMAID. PACIENTES Y MÉTODOS: Se realizó un estudio de 68 pacientes con OMAID postoperatorio tratado con cirugía laparoscópica de monopuerto y múltipuerto en dos centros de Bogotá, Colombia entre enero de 2013 y junio de 2018. RESULTADOS: Pacientes llevados a manejo laparoscópico, 27 por monopuerto y 41 por múltipuerto, con tiempo quirúrgico promedio de 129 y 167 minutos respectivamente. 4.1% de los pacientes requirieron resección intestinal, todas en pacientes con abordaje múltipuerto con anastomosis intracorpóreas. El tiempo medio de hospitalización fue de 3.2 días para monopuerto y 2.2 días para multipuerto. CONCLUSIONES: Ambos abordajes laparoscópicos son factibles para el manejo del OMAID en manos calificadas. La selección del paciente y el juicio médico parecen ser factores fundamentales en el resultado positivo.

Metformin reduces macrophage HIF1α-dependent proinflammatory signaling to restore brown adipocyte function in vitro.

Therapeutic potential of metformin in obese/diabetic patients has been associated to its ability to combat insulin resistance. However, it remains largely unknown the signaling pathways involved and whether some cell types are particularly relevant for its beneficial effects. M1-activation of macrophages by bacterial lipopolysaccharide (LPS) promotes a paracrine activation of hypoxia-inducible factor-1α (HIF1α) in brown adipocytes which reduces insulin signaling and glucose uptake, as well as ß-adrenergic sensitivity. Addition of metformin to M1-polarized macrophages blunted these signs of brown adipocyte dysfunction. At the molecular level, metformin inhibits an inflammatory program executed by HIF1α in macrophages by inducing its degradation through the inhibition of mitochondrial complex I activity, thereby reducing oxygen consumption in a reactive oxygen species (ROS)-independent manner. In obese mice, metformin reduced inflammatory features in brown adipose tissue (BAT) such as macrophage infiltration, proinflammatory signaling and gene expression, and restored the response to cold exposure. In conclusion, the impact of metformin on macrophages by suppressing a HIF1α-dependent proinflammatory program is likely responsible for a secondary beneficial effect on insulin-mediated glucose uptake and ß-adrenergic responses in brown adipocytes.

Pharmacological HIF-PHD inhibition reduces renovascular resistance and increases glomerular filtration by stimulating nitric oxide generation.

AIM: Hypoxia-inducible factors (HIFs) are O2 -sensitive transcription factors that regulate multiple biological processes which are essential for cellular adaptation to hypoxia. Small molecule inhibitors of HIF-prolyl hydroxylase domain (PHD) dioxygenases (HIF-PHIs) activate HIF-dependent transcriptional programs and have broad clinical potential. HIF-PHIs are currently in global late-stage clinical development for the treatment of anaemia associated with chronic kidney disease. Although the effects of hypoxia on renal haemodynamics and function have been studied in animal models and in humans living at high altitude, the effects of pharmacological HIF activation on renal haemodynamics, O2 metabolism and metabolic efficiency are not well understood. METHODS: Using a cross-sectional study design, we investigated renal haemodynamics, O2 metabolism, gene expression and NO production in healthy rats treated with different doses of HIF-PHIs roxadustat or molidustat compared to vehicle control. RESULTS: Systemic administration of roxadustat or molidustat resulted in a dose-dependent reduction in renovascular resistance (RVR). This was associated with increased glomerular filtration rate (GFR), urine flow and tubular sodium transport rate (TNa ). Although both total O2 delivery and TNa were increased, more O2 was extracted per transported sodium in rats treated with high-doses of HIF-PHIs, suggesting a reduction in metabolic efficiency. Changes in RVR and GFR were associated with increased nitric oxide (NO) generation and substantially suppressed by pharmacological inhibition of NO synthesis. CONCLUSIONS: Our data provide mechanistic insights into dose-dependent effects of short-term pharmacological HIF activation on renal haemodynamics, glomerular filtration and O2 metabolism and identify NO as a major mediator of these effects.

Inactivation of HIF-prolyl 4-hydroxylases 1, 2 and 3 in NG2-expressing cells induces HIF2-mediated neurovascular expansion independent of erythropoietin.

AIM: NG2 cells in the brain are comprised of pericytes and NG2 glia and play an important role in the execution of cerebral hypoxia responses, including the induction of erythropoietin (EPO) in pericytes. Oxygen-dependent angiogenic responses are regulated by hypoxia-inducible factor (HIF), the activity of which is controlled by prolyl 4-hydroxylase domain (PHD) dioxygenases and the von Hippel-Lindau (VHL) tumour suppressor. However, the role of NG2 cells in HIF-regulated cerebral vascular homeostasis is incompletely understood. METHODS: To examine the HIF/PHD/VHL axis in neurovascular homeostasis, we used a Cre-loxP-based genetic approach in mice and targeted Vhl, Epo, Phd1, Phd2, Phd3 and Hif2a in NG2 cells. Cerebral vasculature was assessed by immunofluorescence, RNA in situ hybridization, gene and protein expression analysis, gel zymography and in situ zymography. RESULTS: Vhl inactivation led to a significant increase in angiogenic gene and Epo expression. This was associated with EPO-independent expansion of capillary networks in cortex, striatum and hypothalamus, as well as pericyte proliferation. A comparable phenotype resulted from the combined inactivation of Phd2 and Phd3, but not from Phd2 inactivation alone. Concomitant PHD1 function loss led to further expansion of the neurovasculature. Genetic inactivation of Hif2a in Phd1/Phd2/Phd3 triple mutant mice resulted in normal cerebral vasculature. CONCLUSION: Our studies establish (a) that HIF2 activation in NG2 cells promotes neurovascular expansion and remodelling independently of EPO, (b) that HIF2 activity in NG2 cells is co-controlled by PHD2 and PHD3 and (c) that PHD1 modulates HIF2 transcriptional responses when PHD2 and PHD3 are inactive.

Differential Contribution of N- and C-Terminal Regions of HIF1α and HIF2α to Their Target Gene Selectivity.

Cellular response to hypoxia is controlled by the hypoxia-inducible transcription factors HIF1α and HIF2α. Some genes are preferentially induced by HIF1α or HIF2α, as has been explored in some cell models and for particular sets of genes. Here we have extended this analysis to other HIF-dependent genes using in vitro WT8 renal carcinoma cells and in vivo conditional Vhl-deficient mice models. Moreover, we generated chimeric HIF1/2 transcription factors to study the contribution of the HIF1α and HIF2α DNA binding/heterodimerization and transactivation domains to HIF target specificity. We show that the induction of HIF1α-dependent genes in WT8 cells, such as CAIX (CAR9) and BNIP3, requires both halves of HIF, whereas the HIF2α transactivation domain is more relevant for the induction of HIF2 target genes like the amino acid carrier SLC7A5. The HIF selectivity for some genes in WT8 cells is conserved in Vhl-deficient lung and liver tissue, whereas other genes like Glut1 (Slc2a1) behave distinctly in these tissues. Therefore the relative contribution of the DNA binding/heterodimerization and transactivation domains for HIF target selectivity can be different when comparing HIF1α or HIF2α isoforms, and that HIF target gene specificity is conserved in human and mouse cells for some of the genes analyzed.

Non-isothermal drying of bio-wastes: Kinetic analysis and determination of effective moisture diffusivity.

A macro-thermogravimetric analysis (macro-TGA) was applied to analyse the non-isothermal drying of different bio-wastes (quince solid waste, grape marc and pumpkin shell from different enterprises located in San Juan Province, Argentina). The experimental data were obtained at three heating rates (5, 10 and 15 K/min) and two different initial moisture contents (30 and 50% w/w). These data were fitted using the Coats-Redfern and Sharp methods. The D2 model showed the best fitting for all experiments when using the Coats-Redfern method. It is assumed that drying occurs on the solid boundary. The predicted Ea values ranged from 43.60 to 64.50 kJ/mol for the three bio-wastes under the different experimental conditions. The Ea value slightly increases with the increase in heating rate because the wastes require more energy to undergo drying. Deff increases moderately with temperature at the beginning of the dehydration process; then, this increasing behaviour is significant due to the loss of continuous moisture channels. Otherwise, Deff increases with the initial moisture content, showing that the humidity of the samples did not reach the saturation content.

Laparoscopic Common Bile Duct Exploration With Primary Closure After Failed Endoscopic Retrograde Cholangiopancreatography Without Intraoperative Cholangiography: A Case Series from a Referral Center in Bogota, Colombia.

Background: Despite the effectiveness of laparoscopic common bile duct (CBD) surgery, no case series details the use and advantages of laparoscopic CBD exploration (LCBDE) without use of intraoperative cholangiography (IOC) in endoscopic retrograde cholangiopancreatography (ERCP) failure. Therefore, we present a case series regarding our success with LCBDE in managing CBD stones (CBDSs) using laparoscopic technique without IOC. Materials and Methods: We performed a descriptive retrospective observational study. Patients with CBDSs, alone or along with gallbladder stones, were treated through LCBDE with primary CBD closure after failed ERCP. Results: All patients underwent LCBDE with choledocotomy and primary duct closure. Patients with gallbladder stones underwent laparoscopic cholecystectomy (78%). All procedures were successful, and no conversions occurred. Surgery duration averaged 106 minutes. Intraoperative bleeding averaged 15 cc, and no mortalities occurred. No patients required additional surgery or intensive care unit admission. Hospitalization duration averaged 5 days. Conclusions: Therefore, a laparoscopic approach with primary CBD closure after failed ERCP for complex CBDSs is safe and effective.

Impacto socioeconómico del manejo actual de la pancreatitis aguda de origen biliar severa: estudio comparativo / Socioeconomic impact of the current management of severe biliary acute pancreatitis: comparative study

RESUMEN Objetivo La pancreatitis aguda de origen biliar es una patología gastrointestinal común, en donde el tratamiento oportuno es el pilar más importante a pesar de sus discrepancias. El objetivo del estudio es establecer el impacto socioeconómico en el manejo actual de esta patología, comparando dos hospitales de tercer nivel de estrato socioeconómico alto y bajo de la ciudad de Bogotá, Colombia. Materiales y Métodos Se realizó un estudio retrospectivo, comparativo de corte transversal entre enero de 2012 y diciembre de 2017, en dos hospitales de Bogotá D. C. Se evaluaron sus características socioeconómicas, género, tiempo de evolución al momento de la consulta, Marshall score, estancia en UCI, estancia hospitalaria, complicaciones, manejo quirúrgico y mortalidad. Resultados Se analizaron 101 pacientes de dos estratos socioeconómicos diferentes (alto y bajo). Se encontró que los pacientes de estrato bajo tienen un riesgo diez veces mayor de requerir un procedimiento quirúrgico. Asimismo, registraron una mayor mortalidad en comparación con pacientes de estrato alto (11,3% vs. 4,2%). También se evidenciaron más complicaciones en el grupo de nivel socioeconómico bajo con respecto al alto, como en la falla exocrina (81,1% vs. 31,3%) y el síndrome compartimental (35,8% vs. 4,2%). Conclusión Se encuentra mayor morbimortalidad en los pacientes de bajo nivel socioeconómico en el contexto de esta patología. Este estudio puede guiar a nuevas investigaciones acerca del impacto socioeconómico en los desenlaces de pancreatitis aguda severa.(AU)

ABSTRACT Objetive Acute pancreatitis of biliary origin is a common gastrointestinal pathology, in which timely management still is the most important. The aims of this research is establish the socioeconomic impact in the current management of severe acute pancreatitis of biliary origin comparing two centers of the third level, one of high socioeconomic population and another of low in Bogotá, Colombia. Materials and Methods A retrospective, cross-sectional comparative study was conducted between January 2012 and December 2017, in two hospitals of Bogotá DC. We evaluated their socioeconomic characteristics, gender, time of evolution at the time of consultation, Marshall score, ICU stay, hospital stay, complications, surgical management and mortality. Results 101 patients from two different socioeconomic strata (high and low) were analyzed, where a 10 times higher risk of requiring a surgical procedure in the group of patients with low stratum was found, as well as a higher mortality compared with those of high stratum. (11.3% Vs 4.2%). There were also more complications in the low socioeconomic group with respect to the high, as in the exocrine failure (81.1% vs 31.3%) and the compartment syndrome (35.8% vs 4.2%). Conclusion There is greater morbidity and mortality in patients of low socioeconomic status in the context of this pathology. This study can guide new research that increases the clarity of the socioeconomic impact on the outcomes of severe acute pancreatitis.(AU)

HIF1α Suppresses Tumor Cell Proliferation through Inhibition of Aspartate Biosynthesis.

Cellular aspartate drives cancer cell proliferation, but signaling pathways that rewire aspartate biosynthesis to control cell growth remain largely unknown. Hypoxia-inducible factor-1α (HIF1α) can suppress tumor cell proliferation. Here, we discovered that HIF1α acts as a direct repressor of aspartate biosynthesis involving the suppression of several key aspartate-producing proteins, including cytosolic glutamic-oxaloacetic transaminase-1 (GOT1) and mitochondrial GOT2. Accordingly, HIF1α suppresses aspartate production from both glutamine oxidation as well as the glutamine reductive pathway. Strikingly, the addition of aspartate to the culture medium is sufficient to relieve HIF1α-dependent repression of tumor cell proliferation. Furthermore, these key aspartate-producing players are specifically repressed in VHL-deficient human renal carcinomas, a paradigmatic tumor type in which HIF1α acts as a tumor suppressor, highlighting the in vivo relevance of these findings. In conclusion, we show that HIF1α inhibits cytosolic and mitochondrial aspartate biosynthesis and that this mechanism is the molecular basis for HIF1α tumor suppressor activity.

[Socioeconomic impact of the current management of severe biliary acute pancreatitis: comparative study]. / Impacto socioeconómico del manejo actual de la pancreatitis aguda de origen biliar severa: estudio comparativo.

OBJETIVE: Acute pancreatitis of biliary origin is a common gastrointestinal pathology, in which timely management still is the most important. The aims of this research is establish the socioeconomic impact in the current management of severe acute pancreatitis of biliary origin comparing two centers of the third level, one of high socioeconomic population and another of low in Bogotá, Colombia. MATERIALS AND METHODS: A retrospective, cross-sectional comparative study was conducted between January 2012 and December 2017, in two hospitals of Bogotá DC. We evaluated their socioeconomic characteristics, gender, time of evolution at the time of consultation, Marshall score, ICU stay, hospital stay, complications, surgical management and mortality. RESULTS: 101 patients from two different socioeconomic strata (high and low) were analyzed, where a 10 times higher risk of requiring a surgical procedure in the group of patients with low stratum was found, as well as a higher mortality compared with those of high stratum. (11.3% Vs 4.2%). There were also more complications in the low socioeconomic group with respect to the high, as in the exocrine failure (81.1% vs 31.3%) and the compartment syndrome (35.8% vs 4.2%). CONCLUSION: There is greater morbidity and mortality in patients of low socioeconomic status in the context of this pathology. This study can guide new research that increases the clarity of the socioeconomic impact on the outcomes of severe acute pancreatitis.

OBJETIVO: La pancreatitis aguda de origen biliar es una patología gastrointestinal común, en donde el tratamiento oportuno es el pilar más importante a pesar de sus discrepancias. El objetivo del estudio es establecer el impacto socioeconómico en el manejo actual de esta patología, comparando dos hospitales de tercer nivel de estrato socioeconómico alto y bajo de la ciudad de Bogotá, Colombia. MATERIALES Y MÉTODOS: Se realizó un estudio retrospectivo, comparativo de corte transversal entre enero de 2012 y diciembre de 2017, en dos hospitales de Bogotá D. C. Se evaluaron sus características socioeconómicas, género, tiempo de evolución al momento de la consulta, Marshall score, estancia en UCI, estancia hospitalaria, complicaciones, manejo quirúrgico y mortalidad. RESULTADOS: Se analizaron 101 pacientes de dos estratos socioeconómicos diferentes (alto y bajo). Se encontró que los pacientes de estrato bajo tienen un riesgo diez veces mayor de requerir un procedimiento quirúrgico. Asimismo, registraron una mayor mortalidad en comparación con pacientes de estrato alto (11,3% vs. 4,2%). También se evidenciaron más complicaciones en el grupo de nivel socioeconómico bajo con respecto al alto, como en la falla exocrina (81,1% vs. 31,3%) y el síndrome compartimental (35,8% vs. 4,2%). CONCLUSIÓN: Se encuentra mayor morbimortalidad en los pacientes de bajo nivel socioeconómico en el contexto de esta patología. Este estudio puede guiar a nuevas investigaciones acerca del impacto socioeconómico en los desenlaces de pancreatitis aguda severa.

An energy-friendly alternative in the large-scale production of soybean oil.

Soybean oil is widely used as cooking oil, whereas the soybean cake is a valuable ingredient for animal food. The extraction of soybean oil is an energy-intensive process, with additional significant impact on the environment via the wastewater and hexane emissions. The research investigated different ways to minimize the energy consumption. In a traditional process, both direct (live) steam and indirect steam heating (jackets, tubular exchangers) are used to deliver the required heat duty. Direct steam injection is restricted to the first evaporator and the stripper, for a total of 620 kg/h. Indirect steam is also applied in the evaporators for a total of 6.44 MW. The desolventizing process requires a steam energy input of 8.15 MW. Integration of a heat exchanger network in the evaporation and stripping part of the process reduces the amount of direct steam usage from 620 kg/h to 270 kg/h and of the indirect heat duty from 6.44 to 5.05 MW. In the cake desolventizing part of the process, the energy requirement is reduced from 8.15 to 2.12 MW. The overall gross energy saving is hence ∼50%. The improvements moreover reduce both the waste water loadings by 56.5% and the CO2 emissions by 62.5%. Hexane emissions are moreover significantly (>90%) reduced.

HIF Oxygen Sensing Pathways in Lung Biology.

Cellular responses to oxygen fluctuations are largely mediated by hypoxia-inducible factors (HIFs). Upon inhalation, the first organ inspired oxygen comes into contact with is the lungs, but the understanding of the pulmonary HIF oxygen-sensing pathway is still limited. In this review we will focus on the role of HIF1α and HIF2α isoforms in lung responses to oxygen insufficiency. In particular, we will discuss novel findings regarding their role in the biology of smooth muscle cells and endothelial cells in the context of hypoxia-induced pulmonary vasoconstriction. Moreover, we will also discuss recent studies into HIF-dependent responses in the airway epithelium, which have been even less studied than the HIF-dependent vascular responses in the lungs. In summary, we will review the biological functions executed by HIF1 or HIF2 in the pulmonary vessels and epithelium to control lung responses to oxygen fluctuations as well as their pathological consequences in the hypoxic lung.

Hypoxia-inducible factor prolyl-4-hydroxylation in FOXD1 lineage cells is essential for normal kidney development.

Hypoxia in the embryo is a frequent cause of intra-uterine growth retardation, low birth weight, and multiple organ defects. In the kidney, this can lead to low nephron endowment, predisposing to chronic kidney disease and arterial hypertension. A key component in cellular adaptation to hypoxia is the hypoxia-inducible factor pathway, which is regulated by prolyl-4-hydroxylase domain (PHD) dioxygenases PHD1, PHD2, and PHD3. In the adult kidney, PHD oxygen sensors are differentially expressed in a cell type-dependent manner and control the production of erythropoietin in interstitial cells. However, the role of interstitial cell PHDs in renal development has not been examined. Here we used a genetic approach in mice to interrogate PHD function in FOXD1-expressing stroma during nephrogenesis. We demonstrate that PHD2 and PHD3 are essential for normal kidney development as the combined inactivation of stromal PHD2 and PHD3 resulted in renal failure that was associated with reduced kidney size, decreased numbers of glomeruli, and abnormal postnatal nephron formation. In contrast, nephrogenesis was normal in animals with individual PHD inactivation. We furthermore demonstrate that the defect in nephron formation in PHD2/PHD3 double mutants required intact hypoxia-inducible factor-2 signaling and was dependent on the extent of stromal hypoxia-inducible factor activation. Thus, hypoxia-inducible factor prolyl-4-hydroxylation in renal interstitial cells is critical for normal nephron formation.

Prolyl-4-hydroxylase 2 and 3 coregulate murine erythropoietin in brain pericytes.

A classic response to systemic hypoxia is the increased production of red blood cells due to hypoxia-inducible factor (HIF)-mediated induction of erythropoietin (EPO). EPO is a glycoprotein hormone that is essential for normal erythropoiesis and is predominantly synthesized by peritubular renal interstitial fibroblast-like cells, which express cellular markers characteristic of neuronal cells and pericytes. To investigate whether the ability to synthesize EPO is a general functional feature of pericytes, we used conditional gene targeting to examine the von Hippel-Lindau/prolyl-4-hydroxylase domain (PHD)/HIF axis in cell-expressing neural glial antigen 2, a known molecular marker of pericytes in multiple organs. We found that pericytes in the brain synthesized EPO in mice with genetic HIF activation and were capable of responding to systemic hypoxia with the induction of Epo. Using high-resolution multiplex in situ hybridization, we determined that brain pericytes represent an important cellular source of Epo in the hypoxic brain (up to 70% of all Epo-expressing cells). We furthermore determined that Epo transcription in brain pericytes was HIF-2 dependent and cocontrolled by PHD2 and PHD3, oxygen- and 2-oxoglutarate-dependent prolyl-4-hydroxylases that regulate HIF activity. In summary, our studies provide experimental evidence that pericytes in the brain have the ability to function as oxygen sensors and respond to hypoxia with EPO synthesis. Our findings furthermore suggest that the ability to synthesize EPO may represent a functional feature of pericytes in the brain and kidney.

Desarrollo y validación de la Escala breve de autoevaluación de la sabiduría (EBAS) en adultos mayores argentinos / Development and validation of the Brief Scale of Self-assessed Wisdom (EBAS) in Argentinian older adults

El objetivo de la investigación es el diseño de una escala breve en español para la evaluación de la sabiduría en adultos mayores. Para ello, se llevaron a cabo tres estudios. En el primero, una muestra de 505 adultos mayores de 50 años completó un cuestionario de 45 ítems en relación con la sabiduría seleccionados por jueces expertos. Un análisis de componentes principales ofreció una solución de 20 ítems agrupados en tres componentes, que explicaba el 42% de la varianza con una consistencia interna satisfactoria (a = 0.85). Posteriormente se puso a prueba la validez estructural de la escala mediante un AFC aplicado a los datos aportados por una muestra de 290 adultos mayores de 50 años. La solución con tres dimensiones independientes era la que mostraba una mejor bondad de ajuste. Por último, en un tercer estudio con 409 adultos mayores de 50 años se obtuvieron datos respecto a la validez concurrente y estabilidad temporal de las puntuaciones de la escala. Se encontró una relación moderadamente alta con otras escalas similares (r=0.45), una relación baja con una escala de deseabilidad social (r = 0.26) y una correlación test-retest satisfactoria (r=0.75). Se comentan las implicaciones teóricas y posibles usos de escala, así como sus limitaciones.

The article is aimed at designing a brief scale in Spanish to assess wisdom among older people. To do that, three studies were carried out. In the first one, a sample made up of 505 people of 50 year-old and older completed a questionnaire that included 45 wisdom-related items selected by experts. The application of a principal component analysis yielded a 20-item solution grouped into three components, which accounted for 42% of the variance, and with a satisfactory internal consistency (a = 0.85). In a second study the structural validity of the scale was tested by means of a CFA applied to data gathered in a 290 people sample. Thee three independent dimension solution was the one that fitted best. Finally, in a third study involving 409 people 50 years and older, the concurrent validity and the stability of scale scores were tested. They were moderately related with scores of a conceptually related scale (r=0.45). Their relationship with a scale of social desirability was low (r = 0.26), while the test-retest correlation was satisfactory (r=0.75). Theoretical implications, possible uses and limitations of the scale were discussed.

Distinct subpopulations of FOXD1 stroma-derived cells regulate renal erythropoietin.

Renal peritubular interstitial fibroblast-like cells are critical for adult erythropoiesis, as they are the main source of erythropoietin (EPO). Hypoxia-inducible factor 2 (HIF-2) controls EPO synthesis in the kidney and liver and is regulated by prolyl-4-hydroxylase domain (PHD) dioxygenases PHD1, PHD2, and PHD3, which function as cellular oxygen sensors. Renal interstitial cells with EPO-producing capacity are poorly characterized, and the role of the PHD/HIF-2 axis in renal EPO-producing cell (REPC) plasticity is unclear. Here we targeted the PHD/HIF-2/EPO axis in FOXD1 stroma-derived renal interstitial cells and examined the role of individual PHDs in REPC pool size regulation and renal EPO output. Renal interstitial cells with EPO-producing capacity were entirely derived from FOXD1-expressing stroma, and Phd2 inactivation alone induced renal Epo in a limited number of renal interstitial cells. EPO induction was submaximal, as hypoxia or pharmacologic PHD inhibition further increased the REPC fraction among Phd2-/- renal interstitial cells. Moreover, Phd1 and Phd3 were differentially expressed in renal interstitium, and heterozygous deficiency for Phd1 and Phd3 increased REPC numbers in Phd2-/- mice. We propose that FOXD1 lineage renal interstitial cells consist of distinct subpopulations that differ in their responsiveness to Phd2 inactivation and thus regulation of HIF-2 activity and EPO production under hypoxia or conditions of pharmacologic or genetic PHD inactivation.

Dimethyl fumarate attenuates cerebral edema formation by protecting the blood-brain barrier integrity.

Brain edema is a hallmark of various neuropathologies, but the underlying mechanisms are poorly understood. We aim to characterize how tissue hypoxia, together with oxidative stress and inflammation, leads to capillary dysfunction and breakdown of the blood-brain barrier (BBB). In a mouse stroke model we show that systemic treatment with dimethyl fumarate (DMF), an antioxidant drug clinically used for psoriasis and multiple sclerosis, significantly prevented edema formation in vivo. Indeed, DMF stabilized the BBB by preventing disruption of interendothelial tight junctions and gap formation, and decreased matrix metalloproteinase activity in brain tissue. In vitro, DMF directly sustained endothelial tight junctions, inhibited inflammatory cytokine expression, and attenuated leukocyte transmigration. We also demonstrate that these effects are mediated via activation of the redox sensitive transcription factor NF-E2 related factor 2 (Nrf2). DMF activated the Nrf2 pathway as shown by up-regulation of several Nrf2 target genes in the brain in vivo, as well as in cerebral endothelial cells and astrocytes in vitro, where DMF also increased protein abundance of nuclear Nrf2. Finally, Nrf2 knockdown in endothelial cells aggravated subcellular delocalization of tight junction proteins during ischemic conditions, and attenuated the protective effect exerted by DMF. Overall, our data suggest that DMF protects from cerebral edema formation during ischemic stroke by targeting interendothelial junctions in an Nrf2-dependent manner, and provide the basis for a completely new approach to treat brain edema.