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Mathieson P.W.,University of Bristol | Mathieson P.W.,Academic Renal Unit
Clinical Kidney Journal | Year: 2012

The podocyte is a key cell in the selective filtering action of the glomerular capillary wall. Podocyte injury is of pathogenetic and prognostic significance in human glomerular disease; podocyte repair and regeneration are important therapeutic targets. In particular, podocyte function is dependent on the cells' actin cytoskeleton: this maintains their complex structure. Alterations in the actin cytoskeleton arise from a variety of genetic and acquired causes. Therapeutic agents that are beneficial in proteinuric disease may act at least partly by restoring the cell shape via effects on the actin cytoskeleton. Recent studies of podocytes in vivo and in vitro are described, highlighting clinically relevant observations and those that help us understand the ways in which we may harness nature's own mechanisms to repair and/or renew these specialized glomerular cells, with a particular focus on their actin cytoskeleton. Drugs that have beneficial effects on podocytes can improve our ability to treat important renal diseases including diabetic nephropathy. Currently available agents can be applied in this way and the rapid progress in the study of podocytes is highlighting new therapeutic targets that can bring even more specificity. © 2012 The Author. Source

Mathieson P.W.,Academic Renal Unit
Nature Reviews Nephrology | Year: 2012

Injury to the podocyte results in proteinuria and often leads to progressive kidney disease. As podocytes have limited ability to repair and/or regenerate, the extent of podocyte injury is a major prognostic determinant in diabetic nephropathy and other common causes of end-stage renal disease. Therapies aimed at preventing or limiting podocyte injury and/or at promoting podocyte repair or regeneration therefore have major potential clinical and economic benefits. Many current therapies-including glucocorticosteroids and calcineurin antagonists-have potent effects on podocytes. The nonspecific natures of these agents lead to undesirable systemic adverse effects: an agent with a more specific focus on podocytes would cause less treatment-associated morbidity. Recent years have seen dramatic advances in our understanding of podocyte biology and in particular regulation of its actin cytoskeleton, the major determinant of the complex architecture on which these cells depend for their function. This advance has allowed the identification of potential therapeutic targets and the next few years should see the development and testing of specific therapies aimed at the podocyte. Thus we are about to move from a situation where some of our 'blunderbuss' older therapies fortuitously happened to have beneficial effects on podocytes to a new era where advances in biological knowledge about a key cell type in the kidney will allow targeted drug design. As well as being intellectually more satisfying, every reason exists to believe that patients of the future will benefit and that the scourge of progressive kidney disease will be more effectively tackled. © 2011 Macmillan Publishers Limited. All rights reserved. Source

Speight J.,AHP Research | Reaney M.D.,AHP Research | Woodcock A.J.,Royal Holloway, University of London | Smith R.M.,Academic Renal Unit | Shaw J.A.M.,Newcastle University
Diabetic Medicine | Year: 2010

Aims: For selected individuals with complex Type 1 diabetes, pancreatic islet transplantation (IT) offers the potential of excellent glycaemic control without significant hypoglycaemia, balanced by the need for ongoing systemic immunosuppression. Increasingly, patient-reported outcomes (PROs) are considered alongside biomedical outcomes as a measure of transplant success. PROs in IT have not previously been compared directly with the closest alternate treatment option, pancreas transplant alone (PTA) or pancreas after kidney (PAK). Methods: We used a Population, Intervention, Comparisons, Outcomes (PICO) strategy to search Scopus and screened 314 references for inclusion. Results: Twelve studies [including PRO assessment of PAK, PTA, islet-after kidney (IAK) and islet transplant alone (ITA); n = 7-205] used a total of nine specified and two unspecified PRO measures. Results were mixed but identified some benefits which remained apparent up to 36 months post-transplant, including improvements in fear of hypoglycaemia, as well as some aspects of diabetes-specific quality of life (QoL) and general health status. Negative outcomes included short-term pain associated with the procedure, immunosuppressant side effects and depressed mood associated with loss of graft function. Conclusions: The mixed results may be attributable to limited sample sizes. Also, some PRO measures may lack sensitivity to detect actual changes, as they exclude issues and domains of life likely to be important for QoL post-transplantation and when patients may no longer perceive themselves to have diabetes. Thus, the full impact of islet/pancreas transplantation (alone or after kidney) on QoL is unknown. Furthermore, no studies have assessed patient satisfaction, which may highlight further advantages and disadvantages of transplantation. © 2010 Diabetes UK. Source

Saleem M.A.,Academic Renal Unit
Pediatric Nephrology | Year: 2013

Nephrotic syndrome is a disorder of the glomerular filtration barrier, a highly specialised tri-layer structure with unique functional properties. Recent advances emanating from the field of molecular genetics have revealed the podocyte as probably the central player in the control of glomerular filtration. More specifically, the cell-cell junction between adjacent podocyte foot processes, namely, the slit diaphragm, has been revealed to be made up of a sophisticated multi-protein complex which dynamically controls foot process architecture via signalling to the actin cytoskeleton. Key genes that have been identified from the study of inherited nephrotic syndromes include those encoding nephrin, podocin, TRPC6 (transient receptor potential canonical channel-6) and α-actinin-4, and more remain to be found. It is now possible to identify genetic causes underlying a proportion of nephrotic syndromes presenting at any age. The next big challenge for clinicians and researchers is to translate the molecular information learnt into the understanding of acquired, non-inherited forms of the disease and to guide therapeutic options. In this regard several exciting advances have been made, both in understanding the molecular mechanisms of current therapies and in revealing circulating plasma factors and the molecular pathways they trigger in the podocyte, that could be targeted by novel therapies. © 2012 IPNA. Source

Bills V.L.,University of Bristol | Salmon A.H.,University of Bristol | Salmon A.H.,Academic Renal Unit | Harper S.J.,University of Bristol | And 5 more authors.
BJOG: An International Journal of Obstetrics and Gynaecology | Year: 2011

Objective Pre-eclampsia is diagnosed by hypertension and proteinuria, probably caused by endothelial dysfunction, resulting in symptoms including oedema, inflammation and altered metabolism. Vascular endothelial growth factor A (VEGF-A) is detected at higher concentrations in plasma from patients with pre-eclampsia than in plasma from normotensive pregnant patients when determined by radioimmunoassay. This study tested the hypothesis that circulating VEGF-A in pre-eclamptic plasma is biologically active in vivo, and aimed to identify specific isoforms responsible for this activity. Design Plasma from pre-eclamptic (n = 17) and normotensive (n = 10) pregnant women was perfused into Rana mesenteric microvessels, and the subsequent change in microvascular permeability was measured using a single-vessel perfusion micro-occlusion technique. Results Pre-eclamptic but not normotensive plasma resulted in a 5.25 ± 0.8-fold acute increase in vascular permeability (P = 0.0003). This increase could be blocked by the incubation of plasma with bevacizumab, an antibody to VEGF-A (n = 7; P = 0012), and by VEGF-A receptor inhibition by SU5416 at doses specific to VEGF-A receptor-1 (VEGFR1), but not by the VEGF-A receptor-2 inhibitor, ZM323881. Although VEGF165b levels were not significantly altered in the PET samples, the increase in permeability was also inhibited by incubation of pre-eclamptic plasma with an inhibitory monoclonal antibody specific for VEGF165b (n = 6; P < 0.01), or by the addition of placental growth factor 1 (PlGF-1; n = 3; P < 0.001). PlGF-1 was detected at lower concentrations in pre-eclamptic plasma than in normotensive plasma. Conclusions These findings suggest that circulating VEGF-A levels in pre-eclampsia are biologically active because of a loss of repression of VEGFR1 signalling by PlGF-1, and VEGF165b may be involved in the increased vascular permeability of pre-eclampsia. © 2011 The Authors BJOG An International Journal of Obstetrics and Gynaecology © 2011 RCOG. Source

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