Single-cell transcriptomics identifies aberrant glomerular angiogenic signalling in the early stages of WT1 kidney disease.

WT1 encodes a podocyte transcription factor whose variants can cause an untreatable glomerular disease in early childhood. Although WT1 regulates many podocyte genes, it is poorly understood which of them are initiators in disease and how they subsequently influence other cell-types in the glomerulus. We hypothesised that this could be resolved using single-cell RNA sequencing (scRNA-seq) and ligand-receptor analysis to profile glomerular cell-cell communication during the early stages of disease in mice harbouring an orthologous human mutation in WT1 (Wt1R394W/+). Podocytes were the most dysregulated cell-type in the early stages of Wt1R394W/+ disease, with disrupted angiogenic signalling between podocytes and the endothelium, including the significant downregulation of transcripts for the vascular factors Vegfa and Nrp1. These signalling changes preceded glomerular endothelial cell loss in advancing disease, a feature also observed in biopsy samples from human WT1 glomerulopathies. Addition of conditioned medium from murine Wt1R394W/+ primary podocytes to wild-type glomerular endothelial cells resulted in impaired endothelial looping and reduced vascular complexity. Despite the loss of key angiogenic molecules in Wt1R394W/+ podocytes, the pro-vascular molecule adrenomedullin was upregulated in Wt1R394W/+ podocytes and plasma and its further administration was able to rescue the impaired looping observed when glomerular endothelium was exposed to Wt1R394W/+ podocyte medium. In comparative analyses, adrenomedullin upregulation was part of a common injury signature across multiple murine and human glomerular disease datasets, whilst other gene changes were unique to WT1 disease. Collectively, our study describes a novel role for altered angiogenic signalling in the initiation of WT1 glomerulopathy. We also identify adrenomedullin as a proangiogenic factor, which despite being upregulated in early injury, offers an insufficient protective response due to the wider milieu of dampened vascular signalling that results in endothelial cell loss in later disease. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

SGLT1 contributes to glucose-mediated exacerbation of ischemia-reperfusion injury in ex vivo rat heart.

Hyperglycaemia is common during acute coronary syndromes (ACS) irrespective of diabetic status and portends excess infarct size and mortality, but the mechanisms underlying this effect are poorly understood. We hypothesized that sodium/glucose linked transporter-1 (SGLT1) might contribute to the effect of high-glucose during ACS and examined this using an ex-vivo rodent heart model of ischaemia-reperfusion injury. Langendorff-perfused rat hearts were subjected to 35 min ischemia and 2 h reperfusion, with variable glucose and reciprocal mannitol given during reperfusion in the presence of pharmacological inhibitors of SGLT1. Myocardial SGLT1 expression was determined in rat by rtPCR, RNAscope and immunohistochemistry, as well as in human by single-cell transcriptomic analysis. High glucose in non-diabetic rat heart exacerbated reperfusion injury, significantly increasing infarct size from 45 ± 3 to 65 ± 4% at 11-22 mmol/L glucose, respectively (p < 0.01), an association absent in diabetic heart (32 ± 1-37 ± 5%, p = NS). Rat heart expressed SGLT1 RNA and protein in vascular endothelium and cardiomyocytes, with similar expression found in human myocardium by single-nucleus RNA-sequencing. Rat SGLT1 expression was significantly reduced in diabetic versus non-diabetic heart (0.608 ± 0.08 compared with 1.116 ± 0.13 probe/nuclei, p < 0.01). Pharmacological inhibitors phlorizin, canagliflozin or mizagliflozoin in non-diabetic heart revealed that blockade of SGLT1 but not SGLT2, abrogated glucose-mediated excess reperfusion injury. Elevated glucose is injurious to the rat heart during reperfusion, exacerbating myocardial infarction in non-diabetic heart, whereas the diabetic heart is resistant to raised glucose, a finding which may be explained by lower myocardial SGLT1 expression. SGLT1 is expressed in vascular endothelium and cardiomyocytes and inhibiting SGLT1 abrogates excess glucose-mediated infarction. These data highlight SGLT1 as a potential clinical translational target to improve morbidity/mortality outcomes in hyperglycemic ACS patients.

Cardiotrophin-1 therapy reduces disease severity in a murine model of glomerular disease.

Cardiotrophin-1 (CT-1), a member of the interleukin (IL)-6 cytokine family, has renoprotective effects in mouse models of acute kidney disease and tubulointerstitial fibrosis, but its role in glomerular disease is unknown. To address this, we used the mouse model of nephrotoxic nephritis to test the hypothesis that CT-1 also has a protective role in immune-mediated glomerular disease. Using immunohistochemistry and analysis of single-cell RNA-sequencing data of isolated glomeruli, we demonstrate that CT-1 is expressed in the glomerulus in male mice, predominantly in parietal epithelial cells and is downregulated in mice with nephrotoxic nephritis. Furthermore, analysis of data from patients revealed that human glomerular disease is also associated with reduced glomerular CT-1 transcript levels. In male mice with nephrotoxic nephritis and established proteinuria, administration of CT-1 resulted in reduced albuminuria, prevented podocyte loss, and sustained plasma creatinine, compared with mice administered saline. CT-1 treatment also reduced fibrosis in the kidney cortex, peri-glomerular macrophage accumulation and the kidney levels of the pro-inflammatory mediator complement component 5a. In conclusion, CT-1 intervention therapy delays the progression of glomerular disease in mice by preserving kidney function and inhibiting renal inflammation and fibrosis.

Micro to macro scale analysis of the intact human renal arterial tree with Synchrotron Tomography.

Background: The kidney vasculature is exquisitely structured to orchestrate renal function. Structural profiling of the vasculature in intact rodent kidneys, has provided insights into renal haemodynamics and oxygenation, but has never been extended to the human kidney beyond a few vascular generations. We hypothesised that synchrotron-based imaging of a human kidney would enable assessment of vasculature across the whole organ. Methods: An intact kidney from a 63-year-old male was scanned using hierarchical phase-contrast tomography (HiP-CT), followed by semi-automated vessel segmentation and quantitative analysis. These data were compared to published micro-CT data of whole rat kidney. Results: The intact human kidney vascular network was imaged with HiP-CT at 25 µm voxels, representing a 20-fold increase in resolution compared to clinical CT scanners. Our comparative quantitative analysis revealed the number of vessel generations, vascular asymmetry and a structural organisation optimised for minimal resistance to flow, are conserved between species, whereas the normalised radii are not. We further demonstrate regional heterogeneity in vessel geometry between renal cortex, medulla, and hilum, showing how the distance between vessels provides a structural basis for renal oxygenation and hypoxia. Conclusions: Through the application of HiP-CT, we have provided the first quantification of the human renal arterial network, with a resolution comparable to that of light microscopy yet at a scale several orders of magnitude larger than that of a renal punch biopsy. Our findings bridge anatomical scales, profiling blood vessels across the intact human kidney, with implications for renal physiology, biophysical modelling, and tissue engineering.

Systemic gene therapy with thymosin ß4 alleviates glomerular injury in mice.

Plasma ultrafiltration in the kidney occurs across glomerular capillaries, which are surrounded by epithelial cells called podocytes. Podocytes have a unique shape maintained by a complex cytoskeleton, which becomes disrupted in glomerular disease resulting in defective filtration and albuminuria. Lack of endogenous thymosin ß4 (TB4), an actin sequestering peptide, exacerbates glomerular injury and disrupts the organisation of the podocyte actin cytoskeleton, however, the potential of exogenous TB4 therapy to improve podocyte injury is unknown. Here, we have used Adriamycin (ADR), a toxin which injures podocytes and damages the glomerular filtration barrier leading to albuminuria in mice. Through interrogating single-cell RNA-sequencing data of isolated glomeruli we demonstrate that ADR injury results in reduced levels of podocyte TB4. Administration of an adeno-associated viral vector encoding TB4 increased the circulating level of TB4 and prevented ADR-induced podocyte loss and albuminuria. ADR injury was associated with disorganisation of the podocyte actin cytoskeleton in vitro, which was ameliorated by treatment with exogenous TB4. Collectively, we propose that systemic gene therapy with TB4 prevents podocyte injury and maintains glomerular filtration via protection of the podocyte cytoskeleton thus presenting a novel treatment strategy for glomerular disease.

The timing of auditory sensory deficits in Norrie disease has implications for therapeutic intervention.

Norrie disease is caused by mutation of the NDP gene, presenting as congenital blindness followed by later onset of hearing loss. Protecting patients from hearing loss is critical for maintaining their quality of life. This study aimed to understand the onset of pathology in cochlear structure and function. By investigating patients and juvenile Ndp-mutant mice, we elucidated the sequence of onset of physiological changes (in auditory brainstem responses, distortion product otoacoustic emissions, endocochlear potential, blood-labyrinth barrier integrity) and determined the cellular, histological, and ultrastructural events leading to hearing loss. We found that cochlear vascular pathology occurs earlier than previously reported and precedes sensorineural hearing loss. The work defines a disease mechanism whereby early malformation of the cochlear microvasculature precedes loss of vessel integrity and decline of endocochlear potential, leading to hearing loss and hair cell death while sparing spiral ganglion cells. This provides essential information on events defining the optimal therapeutic window and indicates that early intervention is needed. In an era of advancing gene therapy and small-molecule technologies, this study establishes Ndp-mutant mice as a platform to test such interventions and has important implications for understanding the progression of hearing loss in Norrie disease.

Mechanisms and cell lineages in lymphatic vascular development.

Lymphatic vessels have critical roles in both health and disease and their study is a rapidly evolving area of vascular biology. The consensus on how the first lymphatic vessels arise in the developing embryo has recently shifted. Originally, they were thought to solely derive by sprouting from veins. Since then, several studies have uncovered novel cellular mechanisms and a diversity of contributing cell lineages in the formation of organ lymphatic vasculature. Here, we review the key mechanisms and cell lineages contributing to lymphatic development, discuss the advantages and limitations of experimental techniques used for their study and highlight remaining knowledge gaps that require urgent attention. Emerging technologies should accelerate our understanding of how lymphatic vessels develop normally and how they contribute to disease.

The Biological Significance and Implications of Planar Cell Polarity for Nephrology.

The orientation of cells in two-dimensional and three-dimensional space underpins how the kidney develops and responds to disease. The process by which cells orientate themselves within the plane of a tissue is termed planar cell polarity. In this Review, we discuss how planar cell polarity and the proteins that underpin it govern kidney organogenesis and pathology. The importance of planar cell polarity and its constituent proteins in multiple facets of kidney development is emphasised, including ureteric bud branching, tubular morphogenesis and nephron maturation. An overview is given of the relevance of planar cell polarity and its proteins for inherited human renal diseases, including congenital malformations with unknown aetiology and polycystic kidney disease. Finally, recent work is described outlining the influence of planar cell polarity proteins on glomerular diseases and highlight how this fundamental pathway could yield a new treatment paradigm for nephrology.

Diverse species-specific phenotypic consequences of loss of function sorting nexin 14 mutations.

Mutations in the SNX14 gene cause spinocerebellar ataxia, autosomal recessive 20 (SCAR20) in both humans and dogs. Studies implicating the phenotypic consequences of SNX14 mutations to be consequences of subcellular disruption to autophagy and lipid metabolism have been limited to in vitro investigation of patient-derived dermal fibroblasts, laboratory engineered cell lines and developmental analysis of zebrafish morphants. SNX14 homologues Snz (Drosophila) and Mdm1 (yeast) have also been conducted, demonstrated an important biochemical role during lipid biogenesis. In this study we report the effect of loss of SNX14 in mice, which resulted in embryonic lethality around mid-gestation due to placental pathology that involves severe disruption to syncytiotrophoblast cell differentiation. In contrast to other vertebrates, zebrafish carrying a homozygous, maternal zygotic snx14 genetic loss-of-function mutation were both viable and anatomically normal. Whilst no obvious behavioural effects were observed, elevated levels of neutral lipids and phospholipids resemble previously reported effects on lipid homeostasis in other species. The biochemical role of SNX14 therefore appears largely conserved through evolution while the consequences of loss of function varies between species. Mouse and zebrafish models therefore provide valuable insights into the functional importance of SNX14 with distinct opportunities for investigating its cellular and metabolic function in vivo.

Beyond a Passive Conduit: Implications of Lymphatic Biology for Kidney Diseases.

The kidney contains a network of lymphatic vessels that clear fluid, small molecules, and cells from the renal interstitium. Through modulating immune responses and via crosstalk with surrounding renal cells, lymphatic vessels have been implicated in the progression and maintenance of kidney disease. In this Review, we provide an overview of the development, structure, and function of lymphatic vessels in the healthy adult kidney. We then highlight the contributions of lymphatic vessels to multiple forms of renal pathology, emphasizing CKD, transplant rejection, and polycystic kidney disease and discuss strategies to target renal lymphatics using genetic and pharmacologic approaches. Overall, we argue the case for lymphatics playing a fundamental role in renal physiology and pathology and treatments modulating these vessels having therapeutic potential across the spectrum of kidney disease.

Endothelial-epithelial communication in polycystic kidney disease: Role of vascular endothelial growth factor signalling.

Whereas targeting the cyst epithelium and its molecular machinery has been the prevailing clinical strategy for polycystic kidney disease, the endothelium, including blood vasculature and lymphatics, is emerging as an important player in this disorder. In this Review, we provide an overview of the structural and functional alterations to blood vasculature and lymphatic vessels in the polycystic kidney. We also discuss evidence for vascular endothelial growth factor signalling, otherwise critical for endothelial cell development and maintenance, as being a fundamental molecular pathway in polycystic kidney disease and a potential therapeutic target for modulating cyst expansion.

Tissue Clearing and Deep Imaging of the Kidney Using Confocal and Two-Photon Microscopy.

Microscopic and macroscopic evaluation of biological tissues in three dimensions is becoming increasingly popular. This trend is coincident with the emergence of numerous tissue clearing strategies, and advancements in confocal and two-photon microscopy, enabling the study of intact organs and systems down to cellular and sub-cellular resolution. In this chapter, we describe a wholemount immunofluorescence technique for labeling structures in renal tissue. This technique combined with solvent-based tissue clearing and confocal imaging, with or without two-photon excitation, provides greater structural information than traditional sectioning and staining alone. Given the addition of paraffin embedding to our method, this hybrid protocol offers a powerful approach to combine confocal or two-photon findings with histological and further immunofluorescent analysis within the same tissue.

Spatiotemporal dynamics and heterogeneity of renal lymphatics in mammalian development and cystic kidney disease.

Heterogeneity of lymphatic vessels during embryogenesis is critical for organ-specific lymphatic function. Little is known about lymphatics in the developing kidney, despite their established roles in pathology of the mature organ. We performed three-dimensional imaging to characterize lymphatic vessel formation in the mammalian embryonic kidney at single-cell resolution. In mouse, we visually and quantitatively assessed the development of kidney lymphatic vessels, remodeling from a ring-like anastomosis under the nascent renal pelvis; a site of VEGF-C expression, to form a patent vascular plexus. We identified a heterogenous population of lymphatic endothelial cell clusters in mouse and human embryonic kidneys. Exogenous VEGF-C expanded the lymphatic population in explanted mouse embryonic kidneys. Finally, we characterized complex kidney lymphatic abnormalities in a genetic mouse model of polycystic kidney disease. Our study provides novel insights into the development of kidney lymphatic vasculature; a system which likely has fundamental roles in renal development, physiology and disease.

Long-term pain relief at five years after medical, repeat surgical procedures or no management for recurrence of trigeminal neuralgia after microvascular decompression: analysis of a historical cohort.

BACKGROUND: Management strategies for the recurrence of trigeminal neuralgia after microvascular decompression include repeat procedures, medical management or no further therapy. No consensus exists as to which strategy is best for pain relief. The aim of this study was to determine the characteristics of patients with recurrences after microvascular decompression in the cohort, and to compare long-term pain relief between different management strategies. MATERIALS AND METHODS: A historical cohort of patients who underwent microvascular decompression at a neurosurgical institution between 1982-2002, followed up by postal survey at five years, was included. Characteristics of patients who experienced a recurrence were compared to those who were recurrence free, and pain relief was compared between each management strategy. RESULTS: From 169 responders who were included in the study, 28 (16.6%) experienced a recurrence after MVD. No characteristics were significantly different between patients who experienced a recurrence and those who did not. Repeat procedures, including repeat microvascular decompression, partial sensory rhizotomy or radiofrequency thermocoagulation, yielded the highest proportion of pain relief after recurrence (p = 0.031), with 63.6% of patients pain-free at five-years. There was no evidence to suggest that the choice of repeat procedure influenced the likelihood of pain relief after recurrence. No further treatment yielded 57.1% pain-free, whereas medical therapy had the lowest proportion of pain-free patients, at 10.0%. CONCLUSION: A variety of options are available to patients for recurrence of TN after microvascular decompression with repeat procedures yielding the greatest likelihood of long-term pain relief in this historical cohort. The choice of management should consider the mechanism of recurrence, the benefits and risks of each option and the severity of the pain. Regardless of the management strategy selected, careful phenotyping of patients before and after surgery is paramount.

Analysis of the first 2645 registrations at the research registry®: A global repository for all study types involving human participants.

BACKGROUND: The Declaration of Helsinki has called for the registration of all research studies involving human participants. Despite this, prior registries did not allow registration certain study types, or retrospective registration. The Research Registry® (www.researchregistry.com) was established in 2015 to provide a venue of registration for any study involving human participants. METHODS: and analysis: This retrospective database analysis describes the first 3000 registrations received by the Research Registry®. Since the launch of the Registry in 2015, we have collected data on each registration and excluded inappropriate registrations through a weekly curation process. The characteristics of all studies registered is presented. Each registration was marked against a quality score by two researchers acting independently, and we describe how this has changed over time. No ethical approval was required for this data only study including no human participants. RESULTS: Of 3000 registrations, we included 2645 that were submitted to the registry between February 2015 and October 2017. The number of registrations increased year on year, and we now receive between 60 and 80 registrations per month. One fifth of registrations were from China (537 [20.3%]). Retrospective observational studies were most commonly registered (1125 [42.5%]), and studies included in excess of 20 million patients (median 80 [IQR:25-200]). The quality score of registrations improved over the time (Kruskal-Wallis p < 0.05), and the 'control/comparator' component of the quality score was most poorly completed (completed by 1199 [54%]). CONCLUSION: The Research Registry® has received registrations on over 2500 registrations, including in excess of 20 million patients, with the quality of registrations improving over time. Retrospective observational studies and case series are the most commonly registered.

Accuracy of the painDETECT screening questionnaire for detection of neuropathic components in hospital-based patients with orofacial pain: a prospective cohort study.

BACKGROUND: Better tools are required for the earlier identification and management of orofacial pain with different aetiologies. The painDETECT questionnaire is a patient-completed screening tool with utility for identification of neuropathic pain in a range of contexts. 254 patients, referred from primary care for management of orofacial pain and attending a secondary care centre, were prospectively recruited, and completed the painDETECT prior to consultation. The aim of this study was to determine the accuracy of the painDETECT to detect neuropathic components of orofacial pain, when compared to a reference standard of clinical diagnosis by experienced physicians, in a cohort of hospital-based patients. RESULTS: For the 251 patients included in the analysis, the painDETECT had a modest ability to detect neuropathic components of orofacial pain (AUROC, 0.63; 95% CI, 0.58-0.70; p = 0.001). Patients with orofacial pain diagnoses associated with neuropathic components had higher painDETECT scores than those with non-neuropathic components. However, the painDETECT was weaker at distinguishing patients with mixed pain types, and multiple diagnoses were associated with poor accuracy of the painDETECT. CONCLUSION: In secondary care settings, the painDETECT performed modestly at identifying neuropathic components, and underestimates the complexity of orofacial pain in its mixed presentations and with multiple diagnoses. Prior to clinical applications or research use, the painDETECT and other generic screening tools must be adapted and revalidated for orofacial pain patients, and separately in primary care, where orofacial pain is considerably less common.

Impact of pain and postoperative complications on patient-reported outcome measures 5 years after microvascular decompression or partial sensory rhizotomy for trigeminal neuralgia.

BACKGROUND: Microvascular decompression (MVD) and partial sensory rhizotomy (PSR) provide longstanding pain relief in trigeminal neuralgia (TN). Given their invasiveness, complications can result from such posterior fossa procedures, but the impact of these procedures and their complications on patient-reported outcome measures (PROM), such as quality of life and distress, are not well established. METHOD: Five years after surgery, patients who underwent first MVD or PSR for TN at one institution, between 1982 and 2002, were sent a self-completion assessment set containing a range of PROMs: the Short Form-12 (SF-12) questionnaire to assess quality of life, the Hospital Anxiety and Depression Scale (HADS) to assess distress, and a questionnaire containing questions about postoperative complications, their severity and impact on quality of life. These findings and demographic data were compared between MVD and PSR. RESULTS: One hundred and eighty-one of 245 (73.9%) patients after first MVD and 49 of 60 (81.7%) after PSR responded, and were included in analyses. The mean SF-12 scores of patients after MVD and PSR at five-year follow-up were significantly lower than English age-matched norms. Though there were no differences in SF-12 physical or mental component scores between the two procedures, patients after PSR were more likely to have case-level anxiety (RR = 3.3; 95% CI, 1.1-10.5; p = 0.03), had more postoperative complications, and of greater severity, including pain (RR = 2.52; 95% CI, 1.5-4.1; p < 0.001), numbness (RR = 5.9; 95% CI, 3.8-9.2; p < 0.001), burning sensations (RR = 3.0; 95% CI, 1.5-5.8; p = 0.001) and difficulty in eating (RR = 17.1; 95% CI, 5.6-53.1; p < 0.001), and these had a larger impact on quality of life for PSR compared to MVD. CONCLUSIONS: The quality of life 5 years after MVD or PSR is poorer than in the general population and associated with postoperative complications such as pain, numbness, burning sensation and difficulty in eating. These complications are commoner after PSR than MVD, and this is associated with anxiety in PSR patients at five-year follow-up. However, these differences are not reflected by quality of life scores. Outcome measures need to incorporate patient experience after treatment for TN, and represent patient priorities for quality of life.

How to apply to a summer undergraduate research program.

Want to get more experience in research, but find it difficult as an undergraduate? A summer research project may be the answer and there are many ways to organize this. Various universities around the world offer summer undergraduate research programs. These tend to be very competitive; hundreds, even thousands of students can apply for only a handful of positions. However, with some proactivity and strong planning, diligent undergraduate students can get accepted onto these prestigious programs. In this article, we outline the steps involved in selecting and successfully applying to a summer undergraduate research program.

Reflective practice in health care and how to reflect effectively.

Reflective practice is a paper requirement of your career progression in health care. However, if done properly, it can greatly improve your skills as a health care provider. This article provides some structure to reflective practice to allow a health care provider to engage more with reflective practice and get more out of the experience.

Surveying opinions of 149 registrants to the Research Registry: Awareness of and attitudes towards research registration.

BACKGROUND: Research registration is an important ethical principle in the Declaration of Helsinki, however, progress to increase registration has been slow. Understanding the attitudes of users towards registries may provide insights into increase research registration. In this survey-based study, we sought to gain insight from users of a single global research registry, the Research Registry® (www.researchregistry.com). METHODS: A Google Forms survey was created and emailed to all users of the Research Registry® (n = 1432). Multiple choice and free-text answers were analyzed using descriptive statistics and thematic analysis respectively. RESULTS: From 925 contactable registrations, 149 (16.1%) completed the survey. The most commonly registered study type was retrospective cohort (32.2%). 23 registrations (15.4%) were made during the planning or conception of the study, whereas 67 (45.0%) registered at the time of journal submission, or during the peer review process. Of those that declared whether they had performed unregistered research or not, 51 (45.5%) participants had previously performed unregistered research. Registrants were most commonly made aware of the Research Registry® through submission to the International Journal of Surgery (IJS) family of journals (n = 57, 47.5%). Survey participants identified the most important features of registration to be its convenience, including the ease, time and cost of registration. Thematic analysis revealed the most common motive for registration to be as a mandatory requirement of journal submission, and that registration can be improved by simplification of the registration process. CONCLUSION: Registries must focus on engaging their network of users to ensure that research registration is a dynamic process. They need to adopt a user-centered and agile approach to their development, with a strong focus on "customer service". Moreover, by working in partnership with journals, it is possible to improve compliance with registration.