Grainyhead-like 2 deficiency and kidney cyst growth in a mouse model

BACKGROUND: The transcription factor Grainyhead-like 2 (GRHL2) plays a crucial role in maintaining the epithelial barrier properties of the renal collecting duct and is essential for osmoregulation. We noticed a reduction in GRHL2 expression in cysts derived from the collecting ducts in kidneys affected by Autosomal Dominant Polycystic Kidney Disease (ADPKD). However, the specific role of GRHL2 in cystic kidney disease remains unknown. METHODS: The functional role of the transcription factor Grhl2 in the context of cystic kidney disease was examined through analysis of its expression pattern in patient samples with ADPKD and generating a transgenic cystic kidney disease (TCKD) mouse model by overexpressing the human proto-oncogene c-MYC in kidney collecting ducts. Next, TCKD mice bred with collecting duct-specific Grhl2 knockout mice (Grhl2KO). The resulting TCKD-Grhl2KO mice and their littermates were examined by various types of histological and biochemical assays and gene profiling analysis via RNA-seq. RESULTS: A comprehensive examination of kidney samples from patients with ADPKD revealed GRHL2 downregulation in collecting duct-derived cyst epithelia. Comparative analysis of TCKD and TCKD-Grhl2KO mice exhibited that the collecting duct-specific deletion of Grhl2 resulted in markedly aggravated cyst growth, worsened kidney dysfunction, and shortened life span. Furthermore, transcriptomic analyses indicated sequential downregulation of kidney epithelial cyst development regulators (Frem2, Muc1, Cdkn2c, Pkd2, and Tsc1) during cyst progression in kidneys of TCKD-Grhl2KO mice which included presumed direct Grhl2 target genes. CONCLUSIONS: These results suggest GRHL2 as a potential progression modifier, especially for cysts originating from collecting ducts

MRT-basierte automatische Nierensegmentierung und daraus abgeleitete Marker: Eine Auswertung der bevölkerungsweiten NAKO Gesundheitsstudie

HINTERGRUND: Die automatische und akkurate Segmentierung der Niere und ihrer Kompartimente Kortex, Medulla und Sinus ist eine Voraussetzung für die bevölkerungsweite Erforschung potenziell neuer bildgebungsbasierter Biomarker der Niere. METHODE: Wir haben ein robustes Deep-Learning-Framework zur (Sub-)Segmentierung der Niere entwickelt, das auf einem hierarchischen 3-D „convolutional neural network“ (CNN) basiert. Das CNN ist für mehrskalige Probleme der kombinierten Lokalisation und Segmentierung optimiert und wurde auf abdominale Magnetresonanztomografien aus der bevölkerungsbasierten NAKO Gesundheitsstudie angewendet. ERGEBNISSE: Die Übereinstimmung zwischen Modellvorhersagen und manuellen Segmentierungen war gut bis ausgezeichnet. Die Medianwerte für das auf die Körperoberfläche normierte Volumen von Gesamtniere, Kortex, Medulla und Sinus bei 9 934 Probandinnen und Probanden betrugen 158, 115, 43 und 24 mL/m2. Die Verteilungen dieser Marker wurden sowohl für die Gesamtpopulation als auch für eine Subgruppe von Personen ohne Nierenerkrankung oder damit in Beziehung stehenden Erkrankungen errechnet. Multivariable adjustierte Regressionsanalysen zeigten, dass Diabetes mellitus, männliches Geschlecht und eine höhere geschätzte glomeruläre Filtrationsrate (eGFR, „estimated glomerular filtration rate“) wichtige Prädiktoren für ein höheres Gesamt- und Kortexvolumen waren. Zum Beispiel war jeder Anstieg der glomerulären Filtrationsrate (GFR) um eine Einheit (das heißt um 1 mL/min pro 1,73 m2 Körperoberfläche) mit einer signifikanten Zunahme des Gesamtnierenvolumens um 0,98 mL/m2 verbunden. Die Volumina waren bei Personen mit chronischer Nierenerkrankung niedriger als bei denjenigen ohne. SCHLUSSFOLGERUNG: Die Extraktion von bildbasierten Biomarkern durch CNN-basierte Sub-Segmentierung der Niere mit Daten aus einer populationsbasierten Studie liefert verlässliche Ergebnisse und bildet eine solide Grundlage für weitere Untersuchungen

Plasma NGAL levels in stable kidney transplant recipients and the risk of allograft loss

BACKGROUND: The object of this study was to investigate the utility of Neutrophil gelatinase-associated lipocalin (NGAL) and Calprotectin (CPT) to predict long-term graft survival in stable kidney transplant recipients (KTR). METHODS: 709 stable outpatient KTR were enrolled >2 months post-transplant. The utility of plasma and urinary NGAL (pNGAL, uNGAL) and plasma and urinary CPT at enrollment to predict death-censored graft loss (GL) was evaluated during a 58-month follow-up. RESULTS: Among biomarkers, pNGAL showed best predictive ability for graft loss and was the only biomarker with an AUC > 0.7 for GL within 5 years. Patients with GL within 5 years (n=49) had a median pNGAL of 304[IQR 235-358] versus 182[IQR 128 -246]ng/ml with surviving grafts (p<0.001). Time-dependent Receiver operating characteristic analyses at 58 months indicated an Area-Under-the-Curve (AUC) for pNGAL of 0.795, serum creatinine (sCr) based estimated glomerular filtration rate (eGFR) CKD EPI had an AUC of 0.866. pNGAL added to a model based on conventional risk factors for GL with death as competing risk (age, transplant age, presence of donor specific antibodies, presence of proteinuria, history of delayed graft function) had a strong independent association with GL (subdistribution Hazard ratio (sHR) for binary log transfomed pNGAL (log2 (pNGAL)) (3.4 95% CI 2.24-5.15), p<0.0001). This association was substantially attenuated when eGFR was added to the model (sHR for log2 (pNGAL) 1.63 95% CI 0.92-2.88, p=0.095). Category-free net reclassification improvement of a risk model including log2(pNGAL) additionally to conventional risk factors and eGFR was 54.3% (95% CI 9.2 to 99.3%) but C-statistic did not improve significantly. CONCLUSIONS: pNGAL was an independent predictor of renal allograft loss in stable KTR from one transplant center but did not show consistent added value when compared to baseline predictors including the conventional marker eGFR. Future studies in larger cohorts are warranted

Oligodendrocyte-derived LGI3 and its receptor ADAM23 organize juxtaparanodal Kv1 channel clustering for short-term synaptic plasticity

Neurodevelopmental disorders, such as intellectual disability (ID), epilepsy, and autism, involve altered synaptic transmission and plasticity. Functional characterization of their associated genes is vital for understanding physio-pathological brain functions. LGI3 is a recently recognized ID-associated gene encoding a secretory protein related to an epilepsy-gene product, LGI1. Here, we find that LGI3 is uniquely secreted from oligodendrocytes in the brain and enriched at juxtaparanodes of myelinated axons, forming nanoscale subclusters. Proteomic analysis using epitope-tagged Lgi3 knockin mice shows that LGI3 uses ADAM23 as a receptor and selectively co-assembles with Kv1 channels. A lack of Lgi3 in mice disrupts juxtaparanodal clustering of ADAM23 and Kv1 channels and suppresses Kv1-channel-mediated short-term synaptic plasticity. Collectively, this study identifies an extracellular organizer of juxtaparanodal Kv1 channel clustering for finely tuned synaptic transmission. Given the defective secretion of the LGI3 missense variant, we propose a molecular pathway, the juxtaparanodal LGI3-ADAM23-Kv1 channel, for understanding neurodevelopmental disorders

Epigenetic regulatory layers in the 3D nucleus

Nearly 7 decades have elapsed since Francis Crick introduced the central dogma of molecular biology, as part of his ideas on protein synthesis, setting the fundamental rules of sequence information transfer from DNA to RNAs and proteins. We have since learned that gene expression is finely tuned in time and space, due to the activities of RNAs and proteins on regulatory DNA elements, and through cell-type-specific three-dimensional conformations of the genome. Here, we review major advances in genome biology and discuss a set of ideas on gene regulation and highlight how various biomolecular assemblies lead to the formation of structural and regulatory features within the nucleus, with roles in transcriptional control. We conclude by suggesting further developments that will help capture the complex, dynamic, and often spatially restricted events that govern gene expression in mammalian cells

Interferon regulatory factor 4 plays a pivotal role in the development of aGVHD-associated colitis

Interferon regulatory factor 4 (IRF4) is a master transcription factor that regulates T helper cell (Th) differentiation. It interacts with the Basic leucine zipper transcription factor, ATF-like (BATF), depletion of which in CD4)(+ T cells abrogates acute graft-versus-host disease (aGVHD)-induced colitis. Here, we investigated the immune-regulatory role of Irf4 in a mouse model of MHC-mismatched bone marrow transplantation. We found that recipients of allogenic Irf4(-/-) CD4(+) T cells developed less GVHD-related symptoms. Transcriptome analysis of re-isolated donor Irf4(-/-) CD4(+) T helper (Th) cells, revealed gene expression profiles consistent with loss of effector T helper cell signatures and enrichment of a regulatory T cell (Treg) gene expression signature. In line with these findings, we observed a high expression of the transcription factor BTB and CNC homolog 2; (BACH2) in Irf4(-/-) T cells, which is associated with the formation of Treg cells and suppression of Th subset differentiation. We also found an association between BACH2 expression and Treg differentiation in patients with intestinal GVHD. Finally, our results indicate that IRF4 and BACH2 act as counterparts in Th cell polarization and immune homeostasis during GVHD. In conclusion, targeting the BACH2/IRF4-axis could help to develop novel therapeutic approaches against GVHD

Adiposity influences on myocardial deformation: a cardiovascular magnetic resonance feature tracking study in people with overweight to obesity without established cardiovascular disease

The objective of this study was to assess whether dietary-induced weight loss improves myocardial deformation in people with overweight to obesity without established cardiovascular disease applying cardiovascular magnetic resonance (CMR) with feature tracking (FT) based strain analysis. Ninety people with overweight to obesity without established cardiovascular disease (age 44.6 ± 9.3 years, body mass index (BMI) 32.6 ± 4 kg/m(2)) underwent CMR. We retrospectively quantified FT based strain and LA size and function at baseline and after a 6-month hypocaloric diet, with either low-carbohydrate or low-fat intake. The study cohort was compared to thirty-four healthy normal-weight controls (age 40.8 ± 16.0 years, BMI 22.5 ± 1.4 kg/m(2)). At baseline, the study cohort with overweight to obesity without established cardiovascular disease displayed significantly increased global circumferential strain (GCS), global radial strain (GRS) and LA size (all p 0.05 versus controls). Dietary-induced weight loss led to a significant reduction in GCS, GRS and LA size irrespective of macronutrient composition (all p < 0.01). In a population with overweight to obesity without established cardiovascular disease subclinical myocardial changes can be detected applying CMR. After dietary-induced weight loss improvement of myocardial deformation could be shown. A potential clinical impact needs further studies

Hypertensive disorders of pregnancy and long-term maternal cardiovascular risk: bridging epidemiological knowledge into personalized postpartum care and follow-up

Cardiovascular disease (CVD) is globally the leading cause of death and disability. Sex-specific causes of female CVD are under-investigated. Pregnancy remains an underinvestigated sex-specific stress test for future CVD and a hitherto missed opportunity to initiate prevention of CVD at a young age. Population-based studies show a strong association between female CVD and hypertensive disorders of pregnancy. This association is also present after other pregnancy complications that are associated with placental dysfunction, including fetal growth restriction, preterm delivery and gestational diabetes mellitus. Few women are, however, offered systematic cardio-preventive follow-up after such pregnancy complications. These women typically seek help from the health system at first clinical symptom of CVD, which may be decades later. By this time, morbidity is established and years of preventive opportunities have been missed out. Early identification of modifiable risk factors starting postpartum followed by systematic preventive measures could improve maternal cardiovascular health trajectories, promoting healthier societies. In this non-systematic review we briefly summarize the epidemiological associations and pathophysiological hypotheses for the associations. We summarize current clinical follow-up strategies, including some proposed by international and national guidelines as well as user support groups. We address modifiable factors that may be underexploited in the postpartum period, including breastfeeding and blood pressure management. We suggest a way forward and discuss the remaining knowledge gaps and barriers for securing the best evidence-based follow-up, relative to available resources after a hypertensive pregnancy complication in order to prevent or delay onset of premature CVD

ADAM19 cleaves the PTH receptor and associates with brachydactyly type E

Brachydactyly type E (BDE), shortened metacarpals, metatarsals, cone-shaped epiphyses, and short stature commonly occurs as a sole phenotype. Parathyroid hormone-like protein (PTHrP) has been shown to be responsible in all forms to date, either directly or indirectly. We used linkage and then whole genome sequencing in a small pedigree, to elucidate BDE and identified a truncated disintegrin-and-metalloproteinase-19 (ADAM19) allele in all affected family members, but not in nonaffected persons. Since we had shown earlier that the extracellular domain of the parathyroid hormone receptor (PTHR1) is subject to an unidentified metalloproteinase cleavage, we tested the hypothesis that ADAM19 is a sheddase for PTHR1. WT ADAM19 cleaved PTHR1, while mutated ADAM-19 did not. We mapped the cleavage site that we verified with mass spectrometry between amino acids 64-65. ADAM-19 cleavage increased G(q) and decreased G(s) activation. Moreover, perturbed PTHR1 cleavage by ADAM19 increased ß-arrestin2 recruitment, while cAMP accumulation was not altered. We suggest that ADAM19 serves as a regulatory element for PTHR1 and could be responsible for BDE. This sheddase may affect other PTHrP or PTH-related functions

In vivo monitoring of renal tubule volume fraction using dynamic parametric MRI

PURPOSE: The increasing incidence of kidney diseases is a global concern, and current biomarkers and treatments are inadequate. Changes in renal tubule luminal volume fraction (TVF) serve as a rapid biomarker for kidney disease and improve understanding of renal (patho)physiology. This study uses the amplitude of the long T(2) component as a surrogate for TVF in rats, by applying multiexponential analysis of the T(2)-driven signal decay to examine micromorphological changes in renal tissue. METHODS: Simulations were conducted to identify a low mean absolute error (MAE) protocol and an accelerated protocol customized for the in vivo study of T(2) mapping of the rat kidney at 9.4 T. We then validated our bi-exponential approach in a phantom mimicking the relaxation properties of renal tissue. This was followed by a proof-of-principle demonstration using in vivo data obtained during a transient increase of renal pelvis and tubular pressure. RESULTS: Using the low MAE protocol, our approach achieved an accuracy of MAE < 1% on the mechanical phantom. The T(2) mapping protocol customized for in vivo study achieved an accuracy of MAE < 3%. Transiently increasing pressure in the renal pelvis and tubules led to significant changes in TVF in renal compartments: ΔTVF(cortex) = 4.9%, ΔTVF(outer_medulla) = 4.5%, and ΔTVF(inner_medulla) = −14.6%. CONCLUSION: These results demonstrate that our approach is promising for research into quantitative assessment of renal TVF in in vivo applications. Ultimately, these investigations have the potential to help reveal mechanism in acute renal injury that may lead to chronic kidney disease, which will support research into renal disorders