ROR2/PCP a New Pathway Controlling Endothelial Cell Polarity Under Flow Conditions.

BACKGROUND: Endothelial cells (ECs) are sensitive to physical forces created by blood flow, especially to laminar shear stress. Among the cell responses to laminar flow, EC polarization against the flow direction emerges as a key event, particularly during the development and remodeling of the vascular network. EC adopt an elongated planar cell shape with an asymmetrical distribution of intracellular organelles along the axis of blood flow. This study aimed to investigate the involvement of planar cell polarity via the receptor ROR2 (receptor tyrosine kinase-like orphan receptor 2) in endothelial responses to laminar shear stress. METHODS: We generated a genetic mouse model with EC-specific deletion of Ror2, in combination with in vitro approaches involving loss- and gain-of-function experiments. RESULTS: During the first 2 weeks of life, the endothelium of the mouse aorta undergoes a rapid remodeling associated with a loss of EC polarization against the flow direction. Notably, we found a correlation between ROR2 expression and endothelial polarization levels. Our findings demonstrate that deletion of Ror2 in murine ECs impaired their polarization during the postnatal development of the aorta. In vitro experiments further validated the essential role of ROR2 in both EC collective polarization and directed migration under laminar flow conditions. Exposure to laminar shear stress triggered the relocalization of ROR2 to cell-cell junctions where it formed a complex with VE-Cadherin and ß-catenin, thereby regulating adherens junctions remodeling at the rear and front poles of ECs. Finally, we showed that adherens junctions remodeling and cell polarity induced by ROR2 were dependent on the activation of the small GTPase Cdc42. CONCLUSIONS: This study identified ROR2/planar cell polarity pathway as a new mechanism controlling and coordinating collective polarity patterns of EC during shear stress response.

Clinical trajectories and impact of acute kidney disease after acute kidney injury in the intensive care unit: a 5-year single-centre cohort study.

BACKGROUND: Patients suffering from acute kidney injury(AKI) in the intensive care unit (ICU) can have various renal trajectories and outcomes. Aims were to assess the various clinical trajectories after AKI in the ICU and to determine risk factors for developing chronic kidney disease (CKD). METHODS: We conducted a prospective 5-year follow-up study in a medical ICU at Bordeaux University Hospital (France). The patients who received invasive mechanical ventilation, catecholamine infusion or both and developed an AKI from September 2013 to May 2015 were included. In the Cox analysis, the violation of the proportional hazard assumption for AKD was handled using appropriate interaction terms with time, resulting in a time-dependent hazard ratio (HR). RESULTS: A total of 232 patients were enrolled, with an age of 62 ± 16 years and a median follow-up of 52 days (interquartile range 6-1553). On day 7, 109/232 (47%) patients progressed to acute kidney disease (AKD) and 66/232 (28%) recovered. A linear trajectory (AKI, AKD to CKD) was followed by 44/63 (70%) of the CKD patients. The cumulative incidence of CKD was 30% [95% confidence interval (CI) 24-36] at the 5-year follow-up. In a multivariable Cox model, in the 6 months following AKI, the HR for CKD was higher in AKD patients [HR 29.2 (95% CI 8.5-100.7); P < 0.0001). After 6 months, the HR for CKD was 2.2 (95% CI 0.6-7.9; P = 0.21; n = 172 patients). CONCLUSION: There were several clinical trajectories of kidney disease after ICU-acquired AKI. CKD risk was higher in AKD patients only in the first 6 months. Lack of renal recovery rather than AKD per se was associated with the risk of CKD.

Impact of previous REnal TRansplantation on the mid-term renal Outcome after CARdiac surgery: the RETROCAR trial.

BACKGROUND: Acute kidney injury (AKI) is one of the most common complications after cardiac surgery with cardiopulmonary bypass (CPB). Renal transplant recipients (RTRs) have a higher risk of cardiac surgery-associated AKI (CSA-AKI). A relationship has been strongly suggested between AKI and poor long-term graft survival. The main objective was to evaluate the impact of on-pump cardiac surgery on the 1-year renal allograft survival rate. METHODS: The study population consisted of 37 RTRs and 56 non-RTRs who underwent cardiac surgery between 1 January 2010 and 31 December 2019. They were matched according to age, sex, preoperative glomerular function, diabetes and type of surgery. The primary composite outcome was renal survival, defined as patient survival without the requirement for permanent dialysis or new kidney transplantation at 1 year after surgery. RESULTS: The renal survival rate was significantly lower in the RTR group than in the non-RTR group [81% versus 96%; odds ratio 0.16 (95% confidence interval 0.03-0.82), P = .03]. The proportion of patients who returned to permanent dialysis was higher in the RTR group than in the non-RTR group (12% versus 0%; P = .02). The proportion of patients with severe AKI was also higher in the RTR group. At 1 year after surgery, serum creatinine level, glomerular filtration rate and all-cause mortality rates were comparable between both groups. CONCLUSION: Patients with a functional renal allograft have a low 1-year renal allograft survival rate after cardiac surgery with CPB. In addition, these patients have significant risks of AKI and acute kidney disease after open-heart surgery.

Increased Capillary Permeability in Heart Induces Diastolic Dysfunction Independently of Inflammation, Fibrosis, or Cardiomyocyte Dysfunction.

BACKGROUND: While endothelial dysfunction is suggested to contribute to heart failure with preserved ejection fraction pathophysiology, understanding the importance of the endothelium alone, in the pathogenesis of diastolic abnormalities has not yet been fully elucidated. Here, we investigated the consequences of specific endothelial dysfunction on cardiac function, independently of any comorbidity or risk factor (diabetes or obesity) and their potential effect on cardiomyocyte. METHODS: The ubiquitine ligase Pdzrn3, expressed in endothelial cells (ECs), was shown to destabilize tight junction. A genetic mouse model in which Pdzrn3 is overexpressed in EC (iEC-Pdzrn3) in adults was developed. RESULTS: EC-specific Pdzrn3 expression increased cardiac leakage of IgG and fibrinogen blood-born molecules. The induced edema demonstrated features of diastolic dysfunction, with increased end-diastolic pressure, alteration of dP/dt min, increased natriuretic peptides, in addition to limited exercise capacity, without major signs of cardiac fibrosis and inflammation. Electron microscopic images showed edema with disrupted EC-cardiomyocyte interactions. RNA sequencing analysis of gene expression in cardiac EC demonstrated a decrease in genes coding for endothelial extracellular matrix proteins, which could be related to the fragile blood vessel phenotype. Irregularly shaped capillaries with hemorrhages were found in heart sections of iEC-Pdzrn3 mice. We also found that a high-fat diet was not sufficient to provoke diastolic dysfunction; high-fat diet aggravated cardiac inflammation, associated with an altered cardiac metabolic signature in EC-Pdzrn3 mice, reminiscent of heart failure with preserved ejection fraction features. CONCLUSIONS: An increase of endothelial permeability is responsible for mediating diastolic dysfunction pathophysiology and for aggravating detrimental effects of a high-fat diet on cardiac inflammation and metabolism.

PHACTR-1 (Phosphatase and Actin Regulator 1) Deficiency in Either Endothelial or Smooth Muscle Cells Does Not Predispose Mice to Nonatherosclerotic Arteriopathies in 3 Transgenic Mice.

BACKGROUND: Genome-wide association studies have revealed robust associations of common genetic polymorphisms in an intron of the PHACTR-1 (phosphatase and actin regulator 1) gene (chr6p24), with cervical artery dissection, spontaneous coronary artery dissection, and fibromuscular dysplasia. The aim was to assess its role in the pathogenesis of cervical artery dissection or fibromuscular dysplasia. METHODS: Using various tissue-specific Cre-driver mouse lines, Phactr1 was deleted either in endothelial cells using 2 tissue-specific Cre-driver (PDGFB [platelet-derived growth factor B]-CreERT2 mice and Tie2 [tyrosine kinase with immunoglobulin and EGF homology domains]-Cre) and smooth muscle cells (smooth muscle actin-CreERT2) with a third tissue-specific Cre-driver. RESULTS: To test the efficacy of the Phactr1 deletion after cre-induction, we confirmed first, a decrease in Phactr1 transcription and Phactr1 expression in endothelial cell and smooth muscle cell isolated from Phactr1iPDGFB and Phactr1iSMA mice. Irrespective to the tissue or the duration of the deletion, mice did not spontaneously display pathological phenotype or vascular impairment: mouse survival, growth, blood pressure, large vessel morphology, or actin organization were not different in knockout mice than their comparatives littermates. Challenging vascular function and repair either by angiotensin II-induced hypertension or limb ischemia did not lead to vascular morphology or function impairment in Phactr1-deleted mice. Similarly, there were no more consequences of Phactr1 deletion during embryogenesis in endothelial cells. CONCLUSIONS: Loss of PHACTR-1 function in the cells involved in vascular physiology does not appear to induce a pathological vascular phenotype. The in vivo effect of the intronic variation described in genome-wide association studies is unlikely to involve downregulation in PHACTR-1 expression.

Impact of Albumin Assays in the Diagnosis of Malnutrition in Hemodialysis Patients: A Cohort Study.

OBJECTIVE: In hemodialysis (HD) patients, malnutrition should be diagnosed by several assessment tools including a plasma albumin concentration of less than 3.8 g/dL or 3.5 g/dL using bromocresol green or immunonephelometry (IN), respectively. However, albumin measurement is not yet standardized and two alternative methods are also commonly used in laboratories: bromocresol purple (BCP) and immunoturbidimetry (IT). This study aimed to revisit the hypoalbuminemia thresholds for BCP and IT, in HD patients. METHODS: Plasma albumin was measured by the four analytical methods during the monthly HD nutritional assessment of 103 prospectively included patients. RESULTS: Significant differences in albumin levels were observed in HD patients depending on the method used. Using BCP or IT with the cut-off at 3.5 g/dL (determined for the general population) we obtained 33% and 9.7% of false hypoalbuminemia in comparison to IN (mean bias of -0.4 g/dL and -0.065 g/dL, respectively). The best hypoalbuminemia threshold for BCP was 3.05 g/dL and 3.4 g/dL for IT. Twenty percent of HD patients were classified as malnourished when albumin was determined by IN. Similar rates were obtained using the new hypoalbuminemia cut-offs for BCP (18.5%) and IT (19.5%). CONCLUSION: To avoid nutritional misclassification of HD patients, we should adjust hypoalbuminemia thresholds when BCP or IT methods are used in laboratories.

ANCA-Negative Pauci-immune Necrotizing Glomerulonephritis: A Case Series and a New Clinical Classification.

RATIONALE & OBJECTIVE: Pauci-immune necrotizing glomerulonephritis (PING) is usually associated with the presence of antineutrophil cytoplasmic antibodies (ANCA). However, a minority (2%-3%) of patients with PING do not have detectable ANCA. We assessed the clinical spectrum and outcome of patients with ANCA-negative PING. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: 74 patients with ANCA-negative PING diagnosed in 19 French nephrology centers between August 2006 and December 2018 were included in the series. Patients' medical files were reviewed, and kidney biopsies were centrally reexamined by pathologists who were masked to the diagnosis. FINDINGS: Median age at diagnosis was 69 (IQR, 61-76) years. The clinical and pathological features were remarkable for a high frequency of extrarenal manifestations (54%), nephrotic syndrome (32%), and endocapillary hypercellularity (31%). Three main subtypes of ANCA-negative PING were observed: infection-associated (n=9[12%]), malignancy-associated (n=6[8%]), and primary (n=57[77%]). For patients with primary PING, induction treatment included mainly corticosteroids (n=56[98%]), cyclophosphamide (n=37[65%]), and rituximab (n=5[9%]). Maintenance treatment consisted mainly of corticosteroids (n=42[74%]), azathioprine (n=18[32%]), and mycophenolate mofetil (n=11[19%]). After a median follow-up period of 28 months, 28 (38%) patients had died and 20 (27%) developed kidney failure (estimated glomerular filtration rate<15mL/min/1.73m2). Eleven (21%) patients (9 with primary and 2 with malignancy-associated PING) relapsed. LIMITATIONS: Retrospective study and limited number of patients; electron microscopy was not performed to confirm the absence of glomerular immune deposits. CONCLUSIONS: Within the spectrum of ANCA-negative PING, infection and malignancy-associated forms represent a distinct clinical subset. This new clinical classification may inform the management of ANCA-negative PING, which remains a severe form of vasculitis with high morbidity and mortality rates despite immunosuppressive treatments.

Towards an in vitro model of the glomerular barrier unit with an innovative bioassembly method.

BACKGROUND: The development of an artificial glomerular unit may be pivotal for renal pathophysiology studies at a multicellular scale. Using a tissue engineering approach, we aimed to reproduce in part the specific glomerular barrier architecture by manufacturing a glomerular microfibre (Mf). METHODS: Immortalized human glomerular cell lines of endothelial cells (GEnCs) and podocytes were used. Cells and a three-dimensional (3D) matrix were characterized by immunofluorescence with confocal analysis, Western blot and polymerase chain reaction. Optical and electron microscopy were used to study Mf and cell shapes. We also analysed cell viability and cell metabolism within the 3D construct at 14 days. RESULTS: Using the Mf manufacturing method, we repeatedly obtained a cellularized Mf sorting human glomerular cells in 3D. Around a central structure made of collagen I, we obtained an internal layer composed of GEnC, a newly formed glomerular basement membrane rich in α5 collagen IV and an external layer of podocytes. The cell concentration, optimal seeding time and role of physical stresses were modulated to obtain the Mf. Cell viability and expression of specific proteins (nephrin, synaptopodin, vascular endothelial growth factor receptor 2 (VEGFR2) and von Willebrandt factor (vWF)) were maintained for 19 days in the Mf system. Mf ultrastructure, observed with EM, had similarities with the human glomerular barrier. CONCLUSION: In summary, with our 3D bio-engineered glomerular fibre, GEnC and podocytes produced a glomerular basement membrane. In the future, this glomerular Mf will allow us to study cell interactions in a 3D system and increase our knowledge of glomerular pathophysiology.

Salt wasting syndrome in brain trauma patients: a pathophysiologic approach using sodium balance and urinary biochemical analysis.

BACKGROUND: To explore the underlying mechanisms leading to the occurrence of hyponatremia and enhanced urinary sodium excretion in brain trauma patients using sodium balance and urinary biochemical analysis. METHODS: We conducted a retrospective analysis of a local database prospectively collected in 60 brain trauma patients without chronic renal dysfunction. Metabolic and hemodynamic parameters were averaged over three consecutive periods over the first seven days after admission. The main outcome investigated in this study was the occurrence of at least one episode of hyponatremia. RESULTS: Over the study period, there was a prompt decrease in sodium balance (163 ± 193 vs. -12 ± 154 mmol/day, p < 0.0001) and free water clearance (- 0.7 ± 0.7 vs. -1.8 ± 2.3 ml/min, p < 0.0001). The area under the ROC curves for sodium balance in predicting the occurrence of hyponatremia during the next period was 0.81 [95% CI: 0.64-0.97]. Variables associated with averaged urinary sodium excretion were sodium intake (R2 = 0.26, p < 0.0001) and fractional excretion of urate (R2 = 0.15, p = 0.009). Urinary sodium excretion was also higher in patients with sustained augmented renal clearance over the study period (318 ± 106 vs. 255 ± 135 mmol/day, p = 0.034). CONCLUSION: The decreased vascular volume resulting from a negative sodium balance is a major precipitating factor of hyponatremia in brain trauma patients. Predisposing factors for enhanced urinary sodium excretion were high sodium intake, high fractional excretion of urate and augmented renal clearance over the first seven days after ICU admission.

Rhabdomyolysis after co-administration of a statin and fusidic acid: an analysis of the literature and of the WHO database of adverse drug reactions.

Following a severe case of rhabdomyolysis in our University Hospital after a co-administration of atorvastatin and fusidic acid, we describe this interaction as this combination is not clearly contraindicated in some countries, particularly for long-term treatment by fusidic acid. All cases of rhabdomyolysis during a co-administration of a statin and fusidic acid were identified in the literature and in the World and Health Organization database, VigiBase® . In the literature, 29 cases of rhabdomyolysis were identified; mean age was 66 years, median duration of co-administration before rhabdomyolysis occurrence was 21 days, 28% of cases were fatal. In the VigiBase® , 182 cases were retrieved; mean age was 68 years, median duration of co-administration before rhabdomyolysis was 31 days and 24% of cases were fatal. Owing to the high fatality associated with this co-administration and the long duration of treatment before rhabdomyolysis occurrence, fusidic acid should be used if there is no appropriate alternative, as long as statin therapy is interrupted for the duration of fusidic acid therapy, and perhaps a week longer. Rarely will interruption of this sort have adverse consequences for the patient.

Increased risk of renal events in people with diabetic foot disease: A longitudinal observational study.

OBJECTIVE: Diabetic kidney disease favors diabetic foot ulcers, however we do not know whether the reverse relation exists. We investigated whether diabetic foot disease (DFD) related to an increased risk of developing renal events. RESEARCH DESIGN AND METHODS: We conducted a retrospective analysis of a cohort of patients hospitalized for type 2 diabetes mellitus (T2DM) between 2009 and 2017, stratified for the risk of diabetic foot ulcer grades 0 (no risk), 1 and 2 (at risk), and 3 (DFD) according to the International Work Group on Diabetic Foot (IWGDF) classification. We highlighted new renal events (end-stage renal disease or a doubling of serum creatinine) in their medical records until December 2020. The relationship between DFD and later renal events was analyzed by multivariable Cox regression model. RESULTS: Among 519 patients, 142 (27 %) had a DFD at baseline, and 159 (30 %) were classified as Grades 1 or 2. Thirty-six renal events occurred during the 54 ± 27 months of follow-up: 19 subjects started dialysis, 1 had a renal transplantation, and 16 had a doubling of serum creatinine: 15 each in subjects with DFD and subjects at risk, versus 6 in subjects with Grade 0 DFD (logrank: P = 0.001). Adjusted for i) age and sex; ii) hyperglycemic exposure; iii) conventional cardiovascular risk factors; iv) renal parameters: and v) new diabetic foot ulcers during follow-up, DFD (HR 2.7 to 5.9) and being at risk of DFD Grades 1-2 (HR 2.8 to 5.1) were significantly related to new renal events. CONCLUSION: The risk of renal events was increased in people with T2DM and DFD.

Impact of dexamethasone in severe COVID-19-induced acute kidney injury: a multicenter cohort study.

BACKGROUND: Acute kidney injury (AKI) in intensive care unit (ICU) patients with severe COVID-19 is common (> 50%). A specific inflammatory process has been suggested in the pathogenesis of AKI, which could be improved by dexamethasone (DXM). In a small monocenter study (n = 100 patients), we reported a potential protective effect of DXM on the risk of AKI. This study aimed to investigate the preventive impact of DXM on AKI in a multicenter study of patients with severe COVID-19. METHODS: We conducted a multicenter study in three French ICUs from March 2020 to August 2021. All patients admitted to ICU for severe COVID-19 were included. Individuals with preexistent AKI or DXM administration before admission to ICU were excluded. While never used during the first wave, DXM was used subsequently at ICU entry, providing two treatment groups. Multivariate Cause-specific Cox models taking into account changes in ICU practices over time, were utilized to determine the association between DXM and occurrence of AKI. RESULTS: Seven hundred and ninety-eight patients were included. Mean age was 62.6 ± 12.1 years, 402/798 (50%) patients had hypertension, and 46/798 (6%) had previous chronic kidney disease. Median SOFA was 4 [3-6] and 420/798 (53%) required invasive mechanical ventilation. ICU mortality was 208/798 (26%). AKI was present in 598/798 (75%) patients: 266/598 (38%), 163/598 (27%), and 210/598 (35%) had, respectively, AKI KDIGO 1, 2, 3, and 61/598 (10%) patients required renal replacement therapy. Patients receiving DXM had a significantly decreased hazard of AKI occurrence compared to patients without DXM (HR 0.67; 95CI 0.55-0.81). These results were consistent in analyses that (1) excluded patients with DXM administration to AKI onset delay of less than 12 h, (2) incorporating the different 'waves' of the COVID-19 pandemic. CONCLUSIONS: DXM was associated with a decrease in the risk of AKI in severe COVID-19 patients admitted to ICU. This supports the hypothesis that the inflammatory injury of AKI may be preventable.

Genetic imputation of kidney transcriptome, proteome and multi-omics illuminates new blood pressure and hypertension targets.

Genetic mechanisms of blood pressure (BP) regulation remain poorly defined. Using kidney-specific epigenomic annotations and 3D genome information we generated and validated gene expression prediction models for the purpose of transcriptome-wide association studies in 700 human kidneys. We identified 889 kidney genes associated with BP of which 399 were prioritised as contributors to BP regulation. Imputation of kidney proteome and microRNAome uncovered 97 renal proteins and 11 miRNAs associated with BP. Integration with plasma proteomics and metabolomics illuminated circulating levels of myo-inositol, 4-guanidinobutanoate and angiotensinogen as downstream effectors of several kidney BP genes (SLC5A11, AGMAT, AGT, respectively). We showed that genetically determined reduction in renal expression may mimic the effects of rare loss-of-function variants on kidney mRNA/protein and lead to an increase in BP (e.g., ENPEP). We demonstrated a strong correlation (r = 0.81) in expression of protein-coding genes between cells harvested from urine and the kidney highlighting a diagnostic potential of urinary cell transcriptomics. We uncovered adenylyl cyclase activators as a repurposing opportunity for hypertension and illustrated examples of BP-elevating effects of anticancer drugs (e.g. tubulin polymerisation inhibitors). Collectively, our studies provide new biological insights into genetic regulation of BP with potential to drive clinical translation in hypertension.

Performance of real-time PCR in suspected haemodialysis catheter-related bloodstream infection: a proof-of-concept study.

Background: Catheter-related bloodstream infections (CRBIs) remain a major cause of mortality in haemodialysis (HD) patients with central venous catheters (CVCs), especially because of the non-specific symptomatology and the delay in microbiological diagnosis with possible use of non-optimal empiric antibiotics. Moreover, empiric broad-spectrum antibiotics increase antibiotic resistance development. This study aims to evaluate the diagnostic performance of real-time polymerase chain reaction (rt-PCR) in suspected HD CRBIs compared with blood cultures. Methods: A blood sample for rt-PCR was collected simultaneously with each pair of blood cultures for suspected HD CRBI. The rt-PCR was performed on the whole blood, without any enrichment stage and with specific DNA primers: 16S (universal bacterial), Staphylococcus spp., Staphylococcus aureus and mecA. Each successive patient with a suspected HD CRBI in the HD centre of Bordeaux University Hospital was included. Performance tests were used to compare the result obtained in each rt-PCR assay with its corresponding routine blood culture. Results: Eighty-four paired samples were collected and compared for 40 suspected HD CRBI events in 37 patients. Among these, 13 (32.5%) were diagnosed as HD CRBI. All rt-PCRs except mecA (insufficient number of positive samples) showed high diagnostic performances within 3.5 h: 16S (sensitivity 100%, specificity 78%), Staphylococcus spp. (sensitivity 100%, specificity 97%), S. aureus (sensitivity 100%, specificity 99%). Based on the rt-PCR results, antibiotics could be more appropriately targeted, thus cutting anti-cocci Gram-positive therapy from 77% to 29%. Conclusions: The performance of rt-PCR in suspected HD CRBI events showed fast and high diagnostic accuracy. Its use would improve HD CRBI management with an antibiotic consumption decrease.