Citations

Summary Background Hospitalized patients with hyperkalemia are heterogeneous, and cluster approaches may identify specific homogenous groups. This study aimed to cluster patients with hyperkalemia on admission using unsupervised machine learning (ML) consensus clustering approach, and to compare characteristics and outcomes among these distinct clusters. Methods Consensus cluster analysis was performed in 5133 hospitalized adult patients with admission hyperkalemia, based on available clinical and laboratory data. The standardized mean difference was used to identify each cluster’s key clinical features. The association of hyperkalemia clusters with hospital and 1-year mortality was assessed using logistic and Cox proportional hazard regression. Results Three distinct clusters of hyperkalemia patients were identified using consensus cluster analysis: 1661 (32%) in cluster 1, 2455 (48%) in cluster 2 and 1017 (20%) in cluster 3. Cluster 1 was mainly characterized by older age, higher serum chloride and acute kidney injury (AKI), but lower estimated glomerular filtration rate (eGFR), serum bicarbonate and hemoglobin. Cluster 2 was mainly characterized by higher eGFR, serum bicarbonate and hemoglobin, but lower comorbidity burden, serum potassium and AKI. Cluster 3 was mainly characterized by higher comorbidity burden, particularly diabetes and end-stage kidney disease, AKI, serum potassium, anion gap, but lower eGFR, serum sodium, chloride and bicarbonate. Hospital and 1-year mortality risk was significantly different among the three identified clusters, with highest mortality in cluster 3, followed by cluster 1 and then cluster 2. Conclusion In a heterogeneous cohort of hyperkalemia patients, three distinct clusters were identified using unsupervised ML. These three clusters had different clinical characteristics and outcomes.

AbstractBackgroundThis study aimed to assess outcomes of delivery hospitalizations, including acute kidney injury (AKI), obstetric and foetal events and resource utilization among pregnant women with kidney transplants compared with pregnant women with no known kidney disease and those with chronic kidney disease (CKD) Stages 3–5.MethodHospitalizations for delivery in the US were identified using the enhanced delivery identification method in the National Inpatient Sample dataset from the years 2009 to 2014. Diagnoses of CKD Stages 3–5, kidney transplantation, along with obstetric events, delivery methods and foetal events were identified using ICD‐9‐CM diagnosis and procedure codes. Patients with no known kidney disease group were identified by excluding any diagnoses of CKD, end stage kidney disease, and kidney transplant. Multivariable logistic regression accounting for the survey weights and matched regression was conducted to investigate the risk of maternal and foetal complications in women with kidney transplants, compared with women with no kidney transplants and no known kidney disease, and to women with CKD Stages 3–5.ResultA total of 5, 408, 215 hospitalizations resulting in deliveries were identified from 2009 to 2014, including 405 women with CKD Stages 3–5, 295 women with functioning kidney transplants, and 5, 405, 499 women with no known kidney disease. Compared with pregnant women with no known kidney disease, pregnant kidney transplant recipients were at higher odds of hypertensive disorders of pregnancy (OR = 3.11, 95% CI [2.26, 4.28]), preeclampsia/eclampsia/HELLP syndrome (OR = 3.42, 95% CI [2.54, 4.60]), preterm delivery (OR = 2.46, 95% CI [1.75, 3.45]), foetal growth restriction (OR = 1.74, 95% CI [1.01, 3.00]) and AKI (OR = 10.46, 95% CI [5.33, 20.56]). There were no significant differences in rates of gestational diabetes or caesarean section. Pregnant women with kidney transplants had 1.30‐times longer lengths of stay and 1.28‐times higher costs of hospitalization. However, pregnant women with CKD Stages 3–5 were at higher odds of AKI (OR = 5.29, 95% CI [2.41, 11.59]), preeclampsia/eclampsia/HELLP syndrome (OR = 1.72, 95% CI [1.07, 2.76]) and foetal deaths (OR = 3.20, 95% CI [1.06, 10.24]), and had 1.28‐times longer hospital stays and 1.37‐times higher costs of hospitalization compared with pregnant women with kidney transplant.ConclusionPregnant women with kidney transplant were more likely to experience adverse events during delivery and had longer lengths of stay and higher total charges when compared with women with no known kidney disease. However, pregnant women with moderate to severe CKD were more likely to experience serious complications than kidney transplant recipients.

Key Points Women with severe preeclampsia demonstrate abnormal levels of the complement alternative pathway components. Genetic variants in the complement alternative pathway are more prevalent in those with severe phenotype preeclampsia compared with the general population. Future studies should explore the role of medications that block the complement alternative pathway in treatment of preeclampsia. Background Preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome share many clinical and biologic features with thrombotic microangiopathy syndromes caused by complement abnormalities. Our hypothesis was that similar functional and genetic alterations in the complement alternative pathway (CAP) are present in these disorders of pregnancy. Methods We conducted quantitative analysis of proteins involved in CAP using ELISA and nephelometry on prospectively collected blood samples from patients with severe phenotype preeclampsia (defined as delivery ≤34 weeks due to preeclampsia), HELLP syndrome, or eclampsia, and matched normotensive controls ( n =25 in each arm) between 2011 and 2016. Sequencing was performed to interrogate 14 genes encoding CAP components. Results Both groups were similar in age, gravidity, parity, marital status, and race. The study group had a higher BMI (mean±SD, 32±8 versus 25±4 kg/m 2 ; P =0.002) and earlier gestational age at delivery (32.5±3.6 versus 40.3±1 weeks; P <0.001). Serologic studies demonstrated elevated Bb subunit (median [range], 1.2 [0.5–4.3] versus 0.6 [0.5–1] μ g/ml; P<0.001), complement C5 concentration (28 [18–33] versus 24 [15–34] mg/dl; P =0.03), and sMAC (371 [167–761] versus 184 [112–249] ng/ml; P<0.001) concentrations in patients with preeclampsia. Two thirds of patients with preeclampsia had at least one nonsynonymous sequence variant in CAP genes. Conclusion Patients with severe phenotype preeclampsia manifest functional alterations in CAP activation. Genetic variants in the CAP genes were detected in several patients, but a larger population study is necessary to fully evaluate genetic risk. Genetic screening and complement-targeted treatment may be useful in risk stratification and novel therapeutic approaches.

As passionate readers, occasional writers, reviewers, and editors with different experiences, when we were asked to participate in shaping and proposing a new journal, the first question that we had to deal with was, of course, “do we really need a new nephrology journal [...]

Abstract Key Points The healthy kidney prominently expresses angiotensin-converting enzyme 2 (ACE2) mRNA, protein, and activity, with ACE2 protein abundantly displayed in proximal tubules. Renal ACE2 expression decreases after ischemic AKI but is induced by LPS in a heme oxygenase-1-dependent manner. ACE2 induction/angiotensin (1–7) and angiotensin (1–7) may offer therapeutic approaches for AKI without or with coronavirus disease 2019, respectively. Background The actions of angiotensin-converting enzyme 2 (ACE2) oppose those of the renin-angiotensin-aldosterone system. ACE2 may be a cytoprotectant in some tissues. This study examined ACE2 expression in models of AKI. Methods ACE2 mRNA and protein expression and ACE2 activity were assessed in murine ischemic AKI. Renal ACE2 mRNA expression was evaluated in LPS-induced AKI in wild-type (C57BL/6J) mice, in heme oxygenase-1 +/+ and heme oxygenase-1 −/− mice, and after unilateral ureteral obstruction (UUO) in wild-type mice. The effect of sex and age on renal ACE2 protein expression was also assessed. Results In ischemic AKI, ACE2 mRNA and protein expression and ACE2 activity were reduced as compared with such indices in the intact kidney. In ischemic AKI, ACE2, which, in health, is prominently expressed in the tubular epithelium, especially proximal tubules, is decreased in expression in these segments. Decreased ACE2 expression in AKI did not reflect reduced GFR, because ACE2 mRNA expression was unaltered after UUO. LPS induced renal ACE2 mRNA expression in wild-type mice, but this effect did not occur in heme oxygenase-1–deficient mice. In ischemic and LPS-induced AKI, renal expression of the Mas receptor was increased. In the intact kidney, renal ACE2 protein expression decreased in female mice as compared with male mice, but was unaltered with age. Conclusion We conclude that renal ACE2 expression is decreased in ischemic AKI, characterized by decreased GFR and abundant cell death, but is upregulated in LPS-induced AKI, an effect requiring heme oxygenase-1. Determining the significance of ACE2 expression in experimental AKI merits further study. We suggest that understanding the mechanism underlying ACE2 downregulation in AKI may offer insights relevant to COVID-19: ACE2 expression is downregulated after ACE2 mediates SARS-CoV-2 cellular entry; such downregulation is proinflammatory; and AKI commonly occurs and determines outcomes in COVID-19.

Objective: Preeclampsia is a cardiovascular complication characterised by the new onset of hypertension and proteinuria or other end-organ dysfunction. Currently there are no effective treatments for preeclampsia except delivery of the placenta and the baby, often pre-term. Administration of mesenchymal stem cells (MSCs) has shown therapeutic potential in pre-clinical models of preeclampsia. In this study, we aimed to identify novel placental miRNAs in preeclampsia which could be targeted by MSCs or their extracellular vesicles (MSC-EVs). Design and method: Human MSCs were isolated from abdominal fat tissue during caesarean section and cultured for 48 h. Human umbilical cord endothelial cells (HUVEC) were co-cultured with MSCs from pregnancies with or without preeclampsia (n = 3) up to 90 h and angiogenesis assessed using tubule formation assay in IncuCyteu live cell imaging system. Using separate patient samples, miRNA was isolated from placentae from women with and without preeclampsia (n = 2) and miRNA next generation sequencing (miRNAseq) performed. The expression of two miRNAs identified in miRNAseq (miRNA-183–5p and miRNA-203a-3p) were measured in HUVEC cells exposed to 24 h hypoxia (1%) or normoxia (21%) in the presence of MSC conditioned medium (MSC-CM) or MSC-EVs. Results: MSCs isolated from women with preeclampsia demonstrated impaired pro-angiogenic profile compared to MSCs derived from normotensive pregnancies measured by the network length (mm/m2) of HUVECs following 66 h, 72 h, 78 h, 84 h and 90 h of exposure to MSC-CM (n = 3, p = 0.001). The results of miRNAseq identified a number of aberrantly expressed miRNAs including mir-183–5p (logFC = -2.8, p = 0.001) and mir-203a-3p (logFC = -6.7, p = 0.001). Following exposure of HUVECs to hypoxia, mir-183–5p was significantly increased by approximately 8-fold (p = 0.001) whereas mir-203a-3p showed no change in expression. MSC-CM and MSC-EVs were both capable of ameliorating this increase in mir-183–5p as a result of hypoxia (p = 0.01, MSC-CM; p = 0.001, MSC-EVs). Conclusions: In patients with preeclampsia, MSCs show impaired angiogenic function, potentially leading to inappropriate placental development and angiogenesis in pregnancy. Administration of healthy MSCs or associated MSC-EVs could have a therapeutic potential in the treatment of preeclampsia and the mechanism could involve novel mir-183–5p as a treatment target.

Abstract Citations are an important, but often overlooked, part of every scientific paper. They allow the reader to trace the flow of evidence, serving as a gateway to relevant literature. Most scientists are aware of citations’ errors, but few appreciate the prevalence of these problems. The purpose of the present study was to examine how often frequently cited papers in biomedical scientific literature are cited inaccurately. The study included an active participation of the first authors of included papers; to first-hand verify the citations accuracy. Findings from feasibility study, where we reviewed 1540 articles containing 2526 citations of 14 most cited articles in which the authors were affiliated with the Faculty of Medicine University of Belgrade, were further evaluated for external confirmation in an independent verification set of articles. Verification set included 4912 citations identified in 2995 articles that cited 13 most cited articles published by authors affiliated with the Mayo Clinic Division of Nephrology and Hypertension. A citation was defined as being accurate if the cited article supported or was in accordance with the statement by citing authors. At least one inaccurate citation was found in 11 and 15% of articles in the feasibility study and verification set, respectively, suggesting that inaccurate citations are common in biomedical literature. The most common problem was the citation of nonexistent findings (38.4%), followed by an incorrect interpretation of findings (15.4%). One-fifth of inaccurate citations were due to chains of inaccurate citations. Based on these findings, several actions to reduce citation inaccuracies have been proposed.

A key immunomodulatory cytokine, IL-10 (interleukin-10), has been shown to be dysregulated in preeclampsia, a pregnancy-specific hypertensive disorder, further characterized by multi-system involvement. However, studies have reported inconsistent findings about circulating IL-10 levels in preeclamptic versus normotensive pregnancies. The aim of the present systematic review and meta-analysis was to assess circulating IL-10 levels in preeclamptic and normotensive pregnancies at 2 time points: before, and at the time of preeclampsia diagnosis. PubMED, EMBASE, and Web of Science databases were searched to include all published studies examining circulating IL-10 levels in preeclamptic and normotensive pregnancies. Differences in IL-10 levels were evaluated by standardized mean differences. Of 876 abstracts screened, 56 studies were included in the meta-analysis. Circulating IL-10 levels were not different before the time of active disease (standardized mean differences, −0.01 [95% CI, −0.11 to 0.08]; P =0.76). At the time of active disease, women with preeclampsia (n=1599) had significantly lower IL-10 levels compared with normotensive controls (n=1998; standardized mean differences, −0.79 [95% CI, −1.22 to −0.35]; P =0.0004). IL-10 levels were lower in both early/severe and late/mild forms of preeclampsia. Subgroup analysis revealed that IL-10 measurement methodology (ELISA or multiplex bead array) and the sample type (plasma or serum) significantly influenced the observed differences, with the use of sera paired with ELISA technology providing the best distinction in IL-10 levels between preeclamptic and normotensive pregnancies. These findings support the role of decreased IL-10 levels in the pathophysiology of preeclampsia. Future studies should address the therapeutic potential of IL-10 in preeclampsia.

The coronavirus disease 2019 (COVID-19) pandemic is associated with significant morbidity and mortality throughout the world, predominantly due to lung and cardiovascular injury. The virus responsible for COVID-19—severe acute respiratory syndrome coronavirus 2—gains entry into host cells via ACE2 (angiotensin-converting enzyme 2). ACE2 is a primary enzyme within the key counter-regulatory pathway of the renin-angiotensin system (RAS), which acts to oppose the actions of Ang (angiotensin) II by generating Ang-(1–7) to reduce inflammation and fibrosis and mitigate end organ damage. As COVID-19 spans multiple organ systems linked to the cardiovascular system, it is imperative to understand clearly how severe acute respiratory syndrome coronavirus 2 may affect the multifaceted RAS. In addition, recognition of the role of ACE2 and the RAS in COVID-19 has renewed interest in its role in the pathophysiology of cardiovascular disease in general. We provide researchers with a framework of best practices in basic and clinical research to interrogate the RAS using appropriate methodology, especially those who are relatively new to the field. This is crucial, as there are many limitations inherent in investigating the RAS in experimental models and in humans. We discuss sound methodological approaches to quantifying enzyme content and activity (ACE, ACE2), peptides (Ang II, Ang-[1–7]), and receptors (types 1 and 2 Ang II receptors, Mas receptor). Our goal is to ensure appropriate research methodology for investigations of the RAS in patients with severe acute respiratory syndrome coronavirus 2 and COVID-19 to ensure optimal rigor and reproducibility and appropriate interpretation of results from these investigations.

Abstract Context Preeclampsia is a leading cardiovascular complication in pregnancy lacking effective diagnostic and treatment strategies. Objective To investigate the diagnostic and therapeutic target potential of the angiogenesis proteins, FK506-binding protein like (FKBPL) and CD44. Design and Intervention FKBPL and CD44 plasma concentration or placental expression were determined in women pre- or postdiagnosis of preeclampsia. Trophoblast and endothelial cell function was assessed following mesenchymal stem cell (MSC) treatment and in the context of FKBPL signaling. Settings and Participants Human samples prediagnosis (15 and 20 weeks of gestation; n ≥ 57), or postdiagnosis (n = 18 for plasma; n = 4 for placenta) of preeclampsia were used to determine FKBPL and CD44 levels, compared to healthy controls. Trophoblast or endothelial cells were exposed to low/high oxygen, and treated with MSC-conditioned media (MSC-CM) or a FKBPL overexpression plasmid. Main Outcome Measures Preeclampsia risk stratification and diagnostic potential of FKBPL and CD44 were investigated. MSC treatment effects and FKBPL-CD44 signaling in trophoblast and endothelial cells were assessed. Results The CD44/FKBPL ratio was reduced in placenta and plasma following clinical diagnosis of preeclampsia. At 20 weeks of gestation, a high plasma CD44/FKBPL ratio was independently associated with the 2.3-fold increased risk of preeclampsia (odds ratio = 2.3, 95% confidence interval [CI] 1.03-5.23, P = 0.04). In combination with high mean arterial blood pressure (&gt;82.5 mmHg), the risk further increased to 3.9-fold (95% CI 1.30-11.84, P = 0.016). Both hypoxia and MSC-based therapy inhibited FKBPL-CD44 signaling, enhancing cell angiogenesis. Conclusions The FKBPL-CD44 pathway appears to have a central role in the pathogenesis of preeclampsia, showing promising utilities for early diagnostic and therapeutic purposes.