Assessment of metabolomic and proteomic biomarkers in detection and prognosis of progression of renal function in chronic kidney disease

Chronic kidney disease (CKD) is part of a number of systemic and renal diseases and may reach epidemic proportions over the next decade. Efforts have been made to improve diagnosis and management of CKD. We hypothesised that combining metabolomic and proteomic approaches could generate a more systemic and complete view of the disease mechanisms. To test this approach, we examined samples from a cohort of 49 patients representing different stages of CKD. Urine samples were analysed for proteomic changes using capillary electrophoresis-mass spectrometry and urine and plasma samples for metabolomic changes using different mass spectrometry-based techniques. The training set included 20 CKD patients selected according to their estimated glomerular filtration rate (eGFR) at mild (59.9±16.5 mL/min/1.73 m2; n = 10) or advanced (8.9±4.5 mL/min/1.73 m2; n = 10) CKD and the remaining 29 patients left for the test set. We identified a panel of 76 statistically significant metabolites and peptides that correlated with CKD in the training set. We combined these biomarkers in different classifiers and then performed correlation analyses with eGFR at baseline and follow-up after 2.8±0.8 years in the test set. A solely plasma metabolite biomarker-based classifier significantly correlated with the loss of kidney function in the test set at baseline and follow-up (ρ = −0.8031; p<0.0001 and ρ = −0.6009; p = 0.0019, respectively). Similarly, a urinary metabolite biomarker-based classifier did reveal significant association to kidney function (ρ = −0.6557; p = 0.0001 and ρ = −0.6574; p = 0.0005). A classifier utilising 46 identified urinary peptide biomarkers performed statistically equivalent to the urinary and plasma metabolite classifier (ρ = −0.7752; p<0.0001 and ρ = −0.8400; p<0.0001). The combination of both urinary proteomic and urinary and plasma metabolic biomarkers did not improve the correlation with eGFR. In conclusion, we found excellent association of plasma and urinary metabolites and urinary peptides with kidney function, and disease progression, but no added value in combining the different biomarkers data

Multicentre prospective validation of a urinary peptidome-based classifier for the diagnosis of type 2 diabetic nephropathy

Background Diabetic nephropathy (DN) is one of the major late complications of diabetes. Treatment aimed at slowing down the progression of DN is available but methods for early and definitive detection of DN progression are currently lacking. The ‘Proteomic prediction and Renin angiotensin aldosterone system Inhibition prevention Of early diabetic nephRopathy In TYpe 2 diabetic patients with normoalbuminuria trial' (PRIORITY) aims to evaluate the early detection of DN in patients with type 2 diabetes (T2D) using a urinary proteome-based classifier (CKD273). Methods In this ancillary study of the recently initiated PRIORITY trial we aimed to validate for the first time the CKD273 classifier in a multicentre (9 different institutions providing samples from 165 T2D patients) prospective setting. In addition we also investigated the influence of sample containers, age and gender on the CKD273 classifier. Results We observed a high consistency of the CKD273 classification scores across the different centres with areas under the curves ranging from 0.95 to 1.00. The classifier was independent of age (range tested 16-89 years) and gender. Furthermore, the use of different urine storage containers did not affect the classification scores. Analysis of the distribution of the individual peptides of the classifier over the nine different centres showed that fragments of blood-derived and extracellular matrix proteins were the most consistently found. Conclusion We provide for the first time validation of this urinary proteome-based classifier in a multicentre prospective setting and show the suitability of the CKD273 classifier to be used in the PRIORITY tria

Natural history of chronic kidney disease : Analysis of pathophysiological and prognostic factors of renal failure and its complications

L'insuffisance rénale chronique (IRC) et son stade terminal sont associés à diverses complications, parmi lesquelles de nombreuses modifications du milieu intérieur : urémie, anémie, hyperparathyroïdie, rétention urémique… Les taux d'urée plasmatique ont longtemps été utilisés comme critère diagnostique de l'IRC, malgré l'absence de caractéristiques essentielles à un tel marqueur. Ces caractéristiques ont été discutées au regard de l'utilisation historique des déterminations d'urée. La caractérisation des altérations plasmatiques des patients en IRC est essentielle à la compréhension de la maladie et de leur lien avec la morbi-mortalité. Nous avons alors étendu notre champ d'intérêt à l'ensemble des solutés de rétention urémique, et sommes parvenus à identifier 56 nouveaux solutés à partir des études cliniques récemment publiées. L'évaluation diagnostique s'est poursuivie par l'étude des concentrations plasmatiques et urinaires en acides aminés et de leur association avec le stade d'IRC et ses complications, permettant alors la génération d'hypothèses sur l'origine métabolique de ces altérations. D'autre part, la mise en place d'une méta-analyse à montré une réduction du risque de décès chez les patients traités par dérivés de la vitamine D. La correction des comorbidités (hypovitaminose, perturbations du métabolisme phosphocalcique) et d'autres effets néphroprotecteurs expliqueraient ces bénéfices. Enfin, l'évaluation du protéome urinaire et du score CKD273 qui en résulte s'est avérée très intéressante pour l'identification des patients à risque de progresser, ce qui est un enjeu de santé publique. Ces travaux d'analyse bibliographique et de recherche clinique s'intègrent dans une volonté d'amélioration de la caractérisation de l'IRC et de l'évaluation de sa progression dans le but de prévenir ses complications. Ils sont le socle d'un projet plus large d'observation et d'analyse des caractéristiques des patients en IRC et de leur évolution.Chronic kidney disease (CKD) and end-stage renal disease (ESRD) are associated with various complications, many of which occur within the internal environment: uremia, anemia, hyperparathyroidism, uremic retention… Plasma urea concentrations have long been used as a diagnostic criterion of CKD, despite the absence of some key characteristics. We discussed these features with regards to the historical uses of urea determinations. It is essential to characterize the plasma changes which occur in CKD to understand the disease and the relationship with comorbidities. We expanded our focus to all of uremic retention solutes, and identified 56 new solutes from recently published clinical studies. The study of plasma and urinary concentrations of amino acids and their association with CKD stage and complications further extended the study of CKD diagnosis, and allowed to generate hypotheses on the metabolic origin of these alterations. On the other hand, by meta-analysis, we showed a reduced risk of death in patients treated with vitamin D derivatives. Correcting comorbidities (hypovitaminosis, disturbances of bone and mineral metabolism) and other renoprotective effects may explain these benefits. Finally, the determination of the urinary proteome and the resulting CKD273 score was proved to be very useful for identifying patients at risk of progression, which is a public health issue. This work based on clinical research and literature analyses is part of an effort to improve the characterization of CKD and the evaluation of progression in order to avoid complications. It is the basis for a wider observational project: analyzing the characteristics of CKD patients and their changes over time

Histoire naturelle de la maladie rénale (Analyse des facteurs physiopathologiques et évaluation pronostique de l'insuffisance rénale terminale et de ses complications)

L'insuffisance rénale chronique (IRC) et son stade terminal sont associés à diverses complications, parmi lesquelles de nombreuses modifications du milieu intérieur : urémie, anémie, hyperparathyroïdie, rétention urémique Les taux d'urée plasmatique ont longtemps été utilisés comme critère diagnostique de l'IRC, malgré l'absence de caractéristiques essentielles à un tel marqueur. Ces caractéristiques ont été discutées au regard de l'utilisation historique des déterminations d'urée. La caractérisation des altérations plasmatiques des patients en IRC est essentielle à la compréhension de la maladie et de leur lien avec la morbi-mortalité. Nous avons alors étendu notre champ d'intérêt à l'ensemble des solutés de rétention urémique, et sommes parvenus à identifier 56 nouveaux solutés à partir des études cliniques récemment publiées. L'évaluation diagnostique s'est poursuivie par l'étude des concentrations plasmatiques et urinaires en acides aminés et de leur association avec le stade d'IRC et ses complications, permettant alors la génération d'hypothèses sur l'origine métabolique de ces altérations. D'autre part, la mise en place d'une méta-analyse à montré une réduction du risque de décès chez les patients traités par dérivés de la vitamine D. La correction des comorbidités (hypovitaminose, perturbations du métabolisme phosphocalcique) et d'autres effets néphroprotecteurs expliqueraient ces bénéfices. Enfin, l'évaluation du protéome urinaire et du score CKD273 qui en résulte s'est avérée très intéressante pour l'identification des patients à risque de progresser, ce qui est un enjeu de santé publique. Ces travaux d'analyse bibliographique et de recherche clinique s'intègrent dans une volonté d'amélioration de la caractérisation de l'IRC et de l'évaluation de sa progression dans le but de prévenir ses complications. Ils sont le socle d'un projet plus large d'observation et d'analyse des caractéristiques des patients en IRC et de leur évolution.Chronic kidney disease (CKD) and end-stage renal disease (ESRD) are associated with various complications, many of which occur within the internal environment: uremia, anemia, hyperparathyroidism, uremic retention Plasma urea concentrations have long been used as a diagnostic criterion of CKD, despite the absence of some key characteristics. We discussed these features with regards to the historical uses of urea determinations. It is essential to characterize the plasma changes which occur in CKD to understand the disease and the relationship with comorbidities. We expanded our focus to all of uremic retention solutes, and identified 56 new solutes from recently published clinical studies. The study of plasma and urinary concentrations of amino acids and their association with CKD stage and complications further extended the study of CKD diagnosis, and allowed to generate hypotheses on the metabolic origin of these alterations. On the other hand, by meta-analysis, we showed a reduced risk of death in patients treated with vitamin D derivatives. Correcting comorbidities (hypovitaminosis, disturbances of bone and mineral metabolism) and other renoprotective effects may explain these benefits. Finally, the determination of the urinary proteome and the resulting CKD273 score was proved to be very useful for identifying patients at risk of progression, which is a public health issue. This work based on clinical research and literature analyses is part of an effort to improve the characterization of CKD and the evaluation of progression in order to avoid complications. It is the basis for a wider observational project: analyzing the characteristics of CKD patients and their changes over time.MONTPELLIER-BU Médecine UPM (341722108) / SudocSudocFranceF

5-HT 2C receptors in the ventral tegmental area, but not in the arcuate nucleus, mediate the hypophagic and hypolocomotor effects of the selective 5-HT 2C receptor agonist AR231630 in rats

International audienc

Blood Pressure Seasonality in Hemodialysis Patients from Five European Cities of Different Latitudes

Background/Aims: Climate influences the regulation of blood pressure (BP). Our objective was to precisely estimate BP seasonality in hemodialysis (HD) patients from five European cities with marked climate differences. Methods: Stable prevalent HD patients from 5 European facilities (Santa Cruz de Tenerife (Spain), Seville (Spain), Montpellier (France), Ottignies (Belgium), Umea (Sweden)) present over the years 1995-1999 were included in this historical longitudinal observational study. Individual monthly averages of pre-dialysis BP level were computed from all facility BP measurements (>90 000 observations). The association between BP level and location, seasons and meteorological measurements was analyzed by mixed models. Results: 261 patients were included and followed-up for a median duration of 2 years (6903 monthly observations). Pre-dialysis SBP and DBP were minimal in summer (July) and maximal in winter (November and December), and mean changes were respectively 4.2 [3.0;5.4] and 2.0 [1.3;2.7] mmHg. Seasonality was confirmed in 4 locations (P-season <= 0.0010.001 for SBP and DBP), but not in Umea (both P-season >0.05). Seasonal changes in DBP were larger in southern locations (P-interaction =0.02). BP level was associated with climate parameters: in a positive manner with humidity or rainfall, and inversely with sunshine duration or temperature. The effects of temperature and rainfall on DBP varied with latitude (P-interaction <0.02) and were greater in southern locations. Conclusion: BP varies with seasons and climate in different European areas and seasonality can be more important in southern locations. These changes in BP deserve attention as they may be responsible for a significant increase in cardiovascular risk which may be preventable

Optimisation of cell and ex vivo culture conditions to study vascular calcification

International audienceMedial vascular calcification (MVC) is a highly prevalent disease associated with a high risk of severe, potentially lethal, complications. While animal studies may not systematically be circumvented, in vitro systems have been proven useful to study disease physiopathology. In the context of MVC, the absence of a clinically relevant standardized in vitro method prevents the appropriate comparison and overall interpretation of results originating from different experiments. The aim of our study is to establish in vitro models mimicking in vivo vascular calcification and to select the best methods to unravel the mechanisms involved in MVC. Human aortic smooth muscle cells and rat aortic rings were cultured in different conditions. The influence of fetal calf serum (FCS), alkaline phosphatase, phosphate and calcium concentrations in the medium were evaluated. We identified culture conditions, including the herein reported Aorta Calcifying Medium (ACM), which allowed a reproducible and specific medial calcification of aortic explants. Studying cells and aortic explants cultured, the involvement of bone morphogenetic protein 2 (BMP2) pathway, fibrosis and apoptosis processes in in vitro MVC were demonstrated. Expression of osteoblastic markers was also observed suggesting the occurrence of transdifferentiation of smooth muscle cells to osteoblasts in our models. The use of these models will help researchers in the field of vascular calcification to achieve reproducible results and allow result comparison in a more consistent way

Blood Pressure Seasonality in Hemodialysis Patients from Five European Cities of Different Latitudes

Background/Aims: Climate influences the regulation of blood pressure (BP). Our objective was to precisely estimate BP seasonality in hemodialysis (HD) patients from five European cities with marked climate differences. Methods: Stable prevalent HD patients from 5 European facilities (Santa Cruz de Tenerife (Spain), Seville (Spain), Montpellier (France), Ottignies (Belgium), Umea (Sweden)) present over the years 1995-1999 were included in this historical longitudinal observational study. Individual monthly averages of pre-dialysis BP level were computed from all facility BP measurements (>90 000 observations). The association between BP level and location, seasons and meteorological measurements was analyzed by mixed models. Results: 261 patients were included and followed-up for a median duration of 2 years (6903 monthly observations). Pre-dialysis SBP and DBP were minimal in summer (July) and maximal in winter (November and December), and mean changes were respectively 4.2 [3.0;5.4] and 2.0 [1.3;2.7] mmHg. Seasonality was confirmed in 4 locations (P-season <= 0.0010.001 for SBP and DBP), but not in Umea (both P-season >0.05). Seasonal changes in DBP were larger in southern locations (P-interaction =0.02). BP level was associated with climate parameters: in a positive manner with humidity or rainfall, and inversely with sunshine duration or temperature. The effects of temperature and rainfall on DBP varied with latitude (P-interaction <0.02) and were greater in southern locations. Conclusion: BP varies with seasons and climate in different European areas and seasonality can be more important in southern locations. These changes in BP deserve attention as they may be responsible for a significant increase in cardiovascular risk which may be preventable

Vascular calcification in different arterial beds in ex vivo ring culture and in vivo rat model

International audienceVascular calcification is a risk factor for cardiovascular and kidney diseases. Medial calcification may differently affect the arterial tree depending on vessel location and smooth muscle injury. The aim was to map the anatomical distribution of vascular calcifications on different arteries and artery locations, in cultured artery rings (ex vivo) and in a rat model of elastocalcinosis (in vivo). Vascular calcification was assessed histologically (von Kossa staining of the media) and by calcium content measurement. Arteries of different sizes were harvested from untreated rats for ring culture and from the vitamin D 3 -nicotine (VDN) rat model for direct observation. When cultured in pro-calcifying conditions, thoracic aorta exhibited similar calcification from the arch to the diaphragm. Calcification increased in abdominal aorta along with the reduction in cross sectional area. Carotid and renal arteries exhibited similar ex vivo calcification. In VDN rats, calcification was greater in carotid artery than in aorta, and was accompanied by fibrosis and apoptosis. Ex vivo, calcification was increased by the induction of lesions on arteries. Along the vascular tree, calcification of the arterial wall increases with the narrowing of vessels in ex vivo ring culture and in vivo. The observed differences represent local susceptibility of the vessels to the calcifying processes