Kidney International (2020) 97, 951-965; https://doi.

Aims/hypothesis Diabetic cardiomyopathy (DCM) is a serious and under-recognised complication of diabetes. The first sign is diastolic dysfunction, which progresses to heart failure. The pathophysiology of DCM is incompletely understood but microcirculatory changes are important. Endothelial glycocalyx (eGlx) plays multiple vital roles in the microcirculation, including in the regulation of vascular permeability, and is compromised in diabetes but has not previously been studied in the coronary microcirculation in diabetes. We hypothesised that eGlx damage in the coronary microcirculation contributes to increased microvascular permeability and hence to cardiac dysfunction. Methods We investigated eGlx damage and cardiomyopathy in mouse models of type 1 (streptozotocin-induced) and type 2 (db/db) diabetes. Cardiac dysfunction was determined by echocardiography. We obtained eGlx depth and coverage by transmission electron microscopy (TEM) on mouse hearts perfusion-fixed with glutaraldehyde and Alcian Blue. Perivascular oedema was assessed from TEM images by measuring the perivascular space area. Lectin-based fluorescence was developed to study eGlx in paraformaldehyde-fixed mouse and human tissues. The eGlx of human conditionally immortalised coronary microvascular endothelial cells (CMVECs) in culture was removed with eGlx-degrading enzymes before measurement of protein passage across the cell monolayer. The mechanism of eGlx damage in the diabetic heart was investigated by quantitative reverse transcription-PCR array and matrix metalloproteinase (MMP) activity assay. To directly demonstrate that eGlx damage disturbs cardiac function, isolated rat hearts were treated with enzymes in a Langendorff preparation. Angiopoietin 1 (Ang1) is known to restore eGlx and so was used to investigate whether eGlx restoration reverses diastolic dysfunction in mice with type 1 diabetes. Results In a mouse model of type 1 diabetes, diastolic dysfunction (confirmed by echocardiography) was associated with loss of eGlx from CMVECs and the development of perivascular oedema, suggesting increased microvascular permeability. We confirmed in vitro that eGlx removal increases CMVEC monolayer permeability. We identified increased MMP activity as a potential mechanism of eGlx damage and we observed loss of syndecan 4 consistent with MMP activity. In a mouse model of type 2 diabetes we found a similar loss of eGlx preceding the development of diastolic dysfunction. We used isolated rat hearts to demonstrate that eGlx damage (induced by enzymes) is sufficient to disturb cardiac function. Ang1 restored eGlx and this was associated with reduced perivascular oedema and amelioration of the diastolic dysfunction seen in mice with type 1 diabetes. Conclusions/interpretation The association of CMVEC glycocalyx damage with diastolic dysfunction in two diabetes models suggests that it may play a pathophysiological role and the enzyme studies confirm that eGlx damage is sufficient to impair cardiac function. Ang1 rapidly restores the CMVEC glycocalyx and improves diastolic function. Our work identifies CMVEC glycocalyx damage as a potential contributor to the development of DCM and therefore as a therapeutic target. Graphical abstract

Background: Glomerular endothelial cell (GEnC) fenestrations are recognised as an essential component of the glomerular filtration barrier, yet little is known about how they are regulated and their role in disease. Methods: We comprehensively characterized GEnC fenestral and functional renal filtration changes including measurement of glomerular ultrafiltration coefficient and glomerular filtration rate in diabetic mice (BTBR ob-/ob-). We also examined and compared human samples. We evaluated Eps homology domain protein-3 (EHD3) and its association with GEnC fenestrations in diabetes in disease samples and further explore its role as a potential regulator of fenestrations in an in vitro model of fenestration formation using b.End5 cells. Results: Loss of GEnC fenestration density was associated with decreased filtration function in diabetic nephropathy. We identified increased diaphragmed fenestrations in diabetes, which are posited to increase resistance to filtration and further contribute to decreased GFR. We identified decreased glomerular EHD3 expression in diabetes, which was significantly correlated with decreased fenestration density. Reduced fenestrations in EHD3 knock-down b.End5 cells in vitro further suggested a mechanistic role for EHD3 in fenestration formation. Conclusions: This study demonstrates the critical role of GEnC fenestrations in renal filtration function and suggests EHD3 may be a key regulator, loss of which may contribute to declining glomerular filtration function through aberrant GEnC fenestration regulation. This points to EHD3 as a novel therapeutic target to restore filtration function in disease

Patient: Female, 19-year-oldFinal Diagnosis: Status epilepticus and stress induced cardiomyopathySymptoms: SeizureMedication: —Clinical Procedure: —Specialty: ToxicologyObjective:Unusual clinical courseBackground:Synthetic cannabinoids have a higher affinity for the cannabinoid receptors CB1 and CB2 than natural cannabinoids. Their use can be associated with cardiovascular disease and neurological complications. A case is reported of status epilepticus and stress cardiomyopathy following the recreational use of the synthetic cannabinoid, UR-144.Case Report:A 19-year-old woman presented to the emergency department in status epilepticus after smoking the synthetic cannabinoid known as ‘space’. Recurring seizure activity was controlled after three hours. On hospital day 3, the patient developed severe biventricular failure. Cardiac magnetic resonance imaging (MRI) confirmed the diagnosis of stress cardiomyopathy. A comprehensive urine drug screen was performed using gas chromatography-mass spectrometry (GC-MS), which was positive for UR-144, or (1-pentyl-1H-indol-3-yl) (2,2,3,3-tetramethylcyclopropyl)-methanone, and negative for all other illicit recreational drugs. The patient improved at one week following admission, with a left ventricular ejection fraction (LVEF) of 40%. She was discharged home on hospital day 10.Conclusions:The use of the synthetic cannabinoid, UR-144, may be associated with prolonged status epilepticus and stress cardiomyopathy. Physicians should be aware of these potentially lethal complications associated with the recreational use of this and other illicit synthetic cannabinoids.

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Background: The study of glomerular endothelial cell (GEnC) fenestrations including key regulatory factors is neglected despite their loss in diabetic nephropathy, a disease associated with decreased filtration function, being previously described. Methods: We comprehensively characterised GEnC fenestral and renal filtration functional changes including measurement of glomerular ultrafiltration coefficient and glomerular filtration rate (GFR) in diabetic mice and humans. We further evaluated Eps homology domain protein-3 (Ehd3) as a potential regulator of GEnC fenestrations. Results: This study identified loss of GEnC fenestration density which was associated with decreased renal filtration function in diabetic nephropathy. We also identified increased GEnC fenestration width, an ultrastructural change that may develop to maintain filtration surface area. GEnC fenestration width was negatively associated with renal filtration function considered a result of development of diaphragms in widening fenestrations providing resistance to filtration. The increased presence of diaphragmed fenestrations in diabetes was supported by increased PLVAP1 expression. We identified decreased glomerular Ehd3 expression in diabetes and demonstrated its association with GEnC fenestration measurements suggesting its role in regulating fenestrations. We further demonstrated reduced fenestration formation in vitro in an Ehd3 knockdown cell line. Ehd3 was positively associated with filtration function suggesting loss of glomerular Ehd3 expression in disease may contribute to declining glomerular filtration function through aberrant GEnC fenestration regulation. Conclusions: This is the first study to demonstrate the critical role of GEnC fenestrations in renal filtration function and identify a key regulator, Ehd3, that may serve as a therapeutic target to retore filtration function in disease.