Metalloprotease Meprinβ in Rat Kidney: Glomerular Localization and Differential Expression in Glomerulonephritis

Meprin (EC 3.4.24.18) is an oligomeric metalloendopeptidase found in microvillar membranes of kidney proximal tubular epithelial cells. Here, we present the first report on the expression of meprinβ in rat glomerular epithelial cells and suggest a potential involvement in experimental glomerular disease. We detected meprinβ in glomeruli of immunostained rat kidney sections on the protein level and by quantitative RT-PCR of laser-capture microdissected glomeruli on the mRNA level. Using immuno-gold staining we identified the membrane of podocyte foot processes as the main site of meprinβ expression. The glomerular meprinβ expression pattern was altered in anti-Thy 1.1 and passive Heymann nephritis (PHN). In addition, the meprinβ staining pattern in the latter was reminiscent of immunostaining with the sheep anti-Fx1A antiserum, commonly used in PHN induction. Using Western blot and immunoprecipitation assays we demonstrated that meprinβ is recognized by Fx1A antiserum and may therefore represent an auto-antigen in PHN. In anti-Thy 1.1 glomerulonephritis we observed a striking redistribution of meprinβ in tubular epithelial cells from the apical to the basolateral side and the cytosol. This might point to an involvement of meprinβ in this form of glomerulonephritis

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Practical Considerations for the Use of Sparsentan in the Treatment of Patients with IgAN in Clinical Practice

Kirk N Campbell,1 Siân Griffin,2 Howard Trachtman,3 Rob Geletka,4 Muh Geot Wong5,6 1Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA; 2Department of Nephrology, University Hospital of Wales, Cardiff, UK; 3Department of Pediatrics, University of Michigan, Ann Arbor, MI, USA; 4Travere Therapeutics, Inc., San Diego, CA, USA; 5Department of Renal Medicine, Concord Repatriation General Hospital, Concord, NSW, Australia; 6Concord Clinical School, University of Sydney, Concord, NSW, AustraliaCorrespondence: Kirk N Campbell, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1243, New York, NY, 10029, USA, Tel +1 212-241-6271, Fax +1 212-987-0389, Email [email protected]: Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. It is characterized by the mesangial deposition of IgA-containing immune complexes, triggering damage to the glomerular filtration barrier that is amplified by the tandem action of endothelin-1 and angiotensin II at their receptors. Proteinuria and progressive glomerular damage cause loss of kidney function in up to 50% of patients within 10– 20 years. The risk of progression is strongly associated with persistent proteinuria (> 0.75– 1 g/day). Current standard of care involves interventions to decrease proteinuria and control blood pressure. Immunosuppressive agents, used in selected patients at high risk for progression, can be associated with significant side effects. Sparsentan, a novel non-immunosuppressive single-molecule Dual Endothelin Angiotensin Receptor Antagonist (DEARA), received FDA accelerated approval based on interim results from the PROTECT trial, which demonstrated that sparsentan-treated patients achieved a significantly greater reduction in proteinuria from baseline versus the active control irbesartan and that sparsentan was generally safe and well tolerated. Sparsentan is the first non-immunosuppressive treatment to be FDA-approved for the reduction of proteinuria in adults with IgAN at high risk of disease progression. We provide practical guidance for the clinical use of sparsentan in adults with IgAN.Plain Language Summary: Immunoglobulin A nephropathy (IgAN) is a type of kidney disease that most commonly affects young adults. IgAN can get worse over time and lead to kidney failure within 10– 20 years after being diagnosed. People with IgAN who leak protein in their urine (ie, proteinuria) at high levels are likely to lose their kidneys faster. The Kidney Disease Improving Global Outcomes 2021 clinical practice guidelines recommend reducing the amount of protein in the urine and keeping blood pressure in check to help protect the kidneys. Doctors sometimes give medications that can weaken the immune system to patients with IgAN who are at high risk for faster loss of kidney function; however, these drugs can have troublesome side effects. Sparsentan is a new treatment that is taken in one pill each day. It targets two important pathways (endothelin-1 and angiotensin II) that lead to the loss of kidney function in IgAN. More than 1200 patients have tried sparsentan in clinical trials, and it seems to be safe and well tolerated. It also reduces protein in the urine much better than irbesartan, a blood pressure medicine often used to treat IgAN. For adults with IgAN at high risk of worsening disease, sparsentan is the first medication approved by the US Food and Drug Administration (FDA) that can reduce protein in the urine without hurting the immune system. This article gives practical advice on how to use sparsentan in adults with IgAN, including who should get it, how to start treatment, and how to check if treatment is working for the patient.Keywords: immunoglobulin A nephropathy, sparsentan, treatment, dual endothelin angiotensin receptor antagonis

Novel targets of antifibrotic and anti-inflammatory treatment in CKD

Chronic kidney disease (CKD) is becoming a worldwide epidemic, driven largely by the dramatic rise in the prevalence of diabetes and obesity. Novel targets and treatments for CKD are, therefore, desperately needed - to both mitigate the burden of this disease in the general population and reduce the necessity for renal replacement therapy in individual patients. This Review highlights new insights into the mechanisms that contribute to CKD, and approaches that might facilitate the development of disease-arresting therapies for CKD. Particular focus is given to therapeutic approaches using antifibrotic agents that target the transforming growth factor ?superfamily. In addition, we discuss new insights regarding the roles of vascular calcification, the NADPH oxidase family, and inflammation in the pathogenesis of CKD. We also highlight a new understanding regarding kidney energy sensing pathways (AMPK, sirtuins, and mTOR) in a variety of kidney diseases and how they are linked to inflammation and fibrosis. Finally, exciting new insights have been made into the role of mitochondrial function and mitochondrial biogenesis in relation to progressive kidney disease. Prospective therapeutics based on these findings will hopefully renew hope for clinicians and patients in the near future. 2014 Macmillan Publishers Limited. All rights reserved.SCOPUS: ar.jSCOPUS: ar.jinfo:eu-repo/semantics/publishe