Biology subjects

Mason, W. J.

Publications and source records attributed to Mason, W. J..

5 recordsLinked to original sources

bioRxiv2024

Vincristine treatment reverses podocyte damage in focal segmental glomerulosclerosis

IntroductionFocal segmental glomerulosclerosis (FSGS) is a significant cause of chronic kidney disease and triggered by podocyte damage which can result in cytoskeletal alterations leading to foot process effacement. Vincristine is a chemoprotective drug which alters cytoskeletal microtubules and has been used clinically to reverse FSGS. However, the mechanisms underlying the beneficial effect of vincristine are not understood. MethodsWe exposed immortalised human podocytes to serum obtained from an FSGS patient before, during, and after vincristine treatment. Using RNA-sequencing we determined the effect on the podocyte transcriptome alongside impacts on cytoskeletal structure and filtration barrier integrity using a glomerulus-on-a-chip model. ResultsWe describe an adult index FSGS patient successfully treated on multiple occasions by vincristine. Podocytes exposed to serum obtained during or after vincristine treatment contained lower levels of genes associated with microtubule function compared with cells stimulated with serum collected before treatment during disease presentation. Presentation serum altered the patterning of two key podocyte cytoskeletal components, tubulin and F-actin and increased albumin permeability, changes prevented by vincristine treatment. Immunoglobulin depletion experiments revealed that the podocyte damage initiated by the presentation serum was not due to circulating autoantibodies. Defects in tubulin patterning were observed when podocytes were exposed to serum from other FSGS patients, suggestive of a common disease mechanism. ConclusionVincristine therapy produces a milieu that protects against pathological changes induced by FSGS serum, associated with preservation of tubulin and F-actin organisation. The functional role of vincristine warrants further investigation, to advance our understanding of this alternative FSGS therapeutic.

cell biology↗

bioRxiv2024

A unique subset of pericystic endothelium associates with aberrant microvascular remodelling and impaired blood perfusion early in polycystic kidney disease

Hallmarks of autosomal dominant polycystic kidney disease (ADPKD), the most common hereditary kidney anomaly, include expanding fluid-filled epithelial cysts, inflammation, and fibrosis. Despite previous work showing the potential of vascular-based therapies, renal microvascular alterations in ADPKD, and their timing, are poorly understood. Using single-cell transcriptomics of human kidney microvasculature, we identify a population of endothelial cells adjacent to cysts in ADPKD. This pericystic endothelium, distinguishable by its expression of osteopontin (SPP1), has a distinct molecular profile compared to the common endothelial cell injury signature in other kidney diseases. SPP1+ pericystic endothelium was also present in an orthologous mouse model of ADPKD before overt kidney functional decline. By interrogating geometric, topological and fractal properties from three-dimensional imaging of early ADPKD mouse kidneys, we show that pericystic endothelium associates with disorganisation and non-uniformity of the renal cortical microvasculature. Concurrently, we detected region-specific reductions in cortical blood flow within ADPKD murine kidneys using arterial spin labelling. We conclude that ADPKD kidneys contain a unique subset of endothelium manifesting with aberrant remodelling and impaired blood perfusion. Its detection, prior to renal functional decline, advocates the vasculature as a therapeutic target to modulate or preserve renal function in early ADPKD.

pathology↗

bioRxiv2022

Three-dimensional imaging and single-cell transcriptomics of the human kidney implicate perturbation of lymphatics in alloimmunity

Studies of the structural and molecular features of the lymphatic vasculature, which clears fluid, macromolecules and leukocytes from the tissue microenvironment, have largely relied on animal models, with limited information in human organs beyond traditional immunohistochemical assessment. Here, we use three-dimensional imaging and single-cell RNA-sequencing to study lymphatics in the human kidney. We found a hierarchical arrangement of lymphatic vessels within human kidneys, initiating along specialised nephron epithelium in the renal cortex and displaying a distinct, kidney-specific transcriptional profile. In chronic transplant rejection we found kidney allograft lymphatic expansion alongside a loss of structural hierarchy, with human leukocyte antigen-expressing lymphatic vessels infiltrating the medulla, presenting a putative target for alloreactive antibodies. This occurred concurrently with lymphatic vessels invading and interconnecting tertiary lymphoid structures at early stages of lymphocyte colonisation. Analysis of intercellular signalling revealed upregulation of co-inhibitory molecule-mediated CD4+ T cell-lymphatic crosstalk in rejecting kidneys, potentially acting to limit local alloimmune responses. Overall, we delineate novel structural and molecular features of human kidney lymphatics and reveal perturbations to their phenotype and transcriptome in the context of alloimmunity. SUMMARYLymphatics regulate fluid balance and immune cell accumulation but are under-studied in human organs such as the kidney. Jafree and colleagues profiled human kidney lymphatics using three-dimensional imaging and single-cell RNA-sequencing, revealing structural and transcriptional perturbations in rejecting kidney transplants.

immunology↗

bioRxiv2022

Exploration of single-cell transcriptomic landscape identifies aberrant glomerular crosstalk in a murine model of WT1 kidney disease

The glomerulus mediates kidney ultrafiltration through specialised epithelial cells called podocytes which line a basement membrane shared with blood capillary endothelium. Cell-cell crosstalk is critical for glomerular function, but its investigation in childhood glomerular diseases has received little attention. WT1 encodes a transcription factor expressed in podocytes, whose heterozygous variants cause devastating kidney disease in childhood. We used single-cell RNA sequencing and ligand-receptor interaction analysis to resolve the glomerular transcriptional landscape of mice that carry an orthologous human mutation in WT1 (Wt1R394W/+). Podocytes were the most dysregulated cell type in early disease, with disrupted angiogenic signalling preceding glomerular capillary loss. Comparative analyses with additional murine and human glomerular disease datasets identified unique transcriptional changes in WT1 glomerular disease, reflecting a non-immunological pathology, whilst revealing a common injury signature across multiple glomerular diseases. Collectively, this work advocates vascular-based therapies over immunosuppressive drugs in the treatment of WT1 glomerular disease.

cell biology↗

bioRxiv2021

Systemic gene therapy with thymosin β4 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 {beta}4 (TB4), an actin sequestering peptide, exacerbates glomerular injury and disrupts the organisation of the podocyte actin cytoskeleton, however, the effect of exogenous TB4 therapy on podocytopathy is unknown. Here, through interrogating single-cell RNA-sequencing data of isolated glomeruli we demonstrate that Adriamycin, a toxin which injures podocytes and leads to leakage of albumin in the urine of mice, results in reduced levels of podocyte TB4. Systemic administration of an adeno-associated virus vector encoding TB4 prevented Adriamycin-induced podocyte loss and albuminuria. Adriamycin injury was associated with disorganisation of the actin cytoskeleton in vitro, which was ameliorated by exogenous TB4. Furthermore, Adriamycin administration in mice was associated with increased prevalence of podocyte vesicles, a mechanism by which albumin may leak into the urine, which was also prevented by TB4. Collectively, we propose that TB4 gene therapy prevents podocyte injury and maintains glomerular filtration via modulation of the podocyte cytoskeleton thus presenting a novel treatment strategy for glomerular disease.

physiology↗