Altered glycosylation of IgG4 promotes lectin complement pathway activation in anti-PL A2R1-associated membranous nephropathy

Primary membranous nephropathy (pMN) is a leading cause of nephrotic syndrome in adults. In most cases, this autoimmune kidney disease is associated with autoantibodies against the M-type phospholipase A2 receptor (PLA2R1) expressed on kidney podocytes, but the mechanisms leading to glomerular damage remain elusive. Here, we developed a cell culture model using human podocytes and found that anti-PLA2R1-positive pMN patient sera or isolated IgG4, but not IgG4-depleted sera, induced proteolysis of the 2 essential podocyte proteins synaptopodin and NEPH1 in the presence of complement, resulting in perturbations of the podocyte cytoskeleton. Specific blockade of the lectin pathway prevented degradation of synaptopodin and NEPH1. Anti-PLA2R1 IgG4 directly bound mannose-binding lectin in a glycosylation-dependent manner. In a cohort of pMN patients, we identified increased levels of galactose-deficient IgG4, which correlated with anti-PLA2R1 titers and podocyte damage induced by patient sera. Assembly of the terminal C5b-9 complement complex and activation of the complement receptors C3aR1 or C5aR1 were required to induce proteolysis of synaptopodin and NEPH1 by 2 distinct proteolytic pathways mediated by cysteine and aspartic proteinases, respectively. Together, these results demonstrated a mechanism by which aberrantly glycosylated IgG4 activated the lectin pathway and induced podocyte injury in primary membranous nephropathy.Proteomic

Quantification of Glomerular Epithelial Cell Adhesion by Using Anti-DNA Antibodies in ELISA

A sensitive and reproducible microassay is described for quantification of adhesion of cells to matrix-coated 96-wells plates under different experimental conditions. For this purpose glomerular visceral epithelial cells (GVEC) were used. Attached GVEC were fixed with methanol and incubated with a monoclonal anti-DNA antibody. Following standard procedures, the amount of bound antibody was quantified by ELISA. A positive linear relationship in the range of 800-5000 cells per well was found between OD values and cell numbers obtained by handcounting (r=0.94, p In conclusion, this cell adhesion microassay is simple, reliable, sensitive, and cost-effective, since it requires small amounts of GVEC and reagents

Membranous nephropathy associated with IgG4-related disease

Immunoglobulin G4 (IgG4)-related systemic disease is a rare condition characterized by high levels of circulating IgG4 and IgG4-positive plasma cell infiltrates in various organs, including the pancreas, salivary glands, biliary tract, liver, lung, and kidney. We describe a case of a 54-year-old man with IgG4-related systemic disease presenting with autoimmune pancreatitis and Mikulicz disease. Steroid therapy decreased circulating IgG4 levels and promoted regression of clinical signs. Thereafter, an increase in serum IgG4 values was followed by the occurrence of nephrotic-range proteinuria. Kidney biopsy showed membranous nephropathy with no IgG4-positive cell infiltrates. A search for circulating immune complexes was negative, and antibodies against M-type phospholipase A2 receptor could not be detected. Western blot analyses identified circulating IgG3 reacting with superoxide dismutase 2. This case suggests that membranous nephropathy represents an additional renal manifestation of IgG4-related systemic disease, with a pathogenesis possibly associated with neoproduction of autoantibodies targeting podocyte antigen(s)

Antibody induced injury to podocytes with proteinuria and foot process swelling in a transgenic (T16) mouse

T16 mice contain a human 3′ untranslated sequence of the Thy 1.1 gene. Unlike normal mice they express Thy 1.1 protein on the podocytes which was immuno-localized to podocyte apical and basal plasma membranes and filtration slit. When monoclonal anti-Thy 1.1 antibody (OX7) was injected in nonproteinuric heterozygous mice there was rapid podocyte foot process swelling and proteinuria. Immunofluorescence showed granular glomerular OX7 binding at one hour. Progressive loss of pedicels occurred with 17.9 ± 2.5, 14.4 ± 1.1 and 10.5 ± 3.5 per 10 nm glomerular basement membrane (GBM) remaining 1, 6 and 24 hours, respectively, after 1 mg OX7, vs 32.2 ± 2.0 in T16 mice given saline. Twenty-four hour proteinuria was OX7 dose-dependent, peaked at 1–3 days and reduced to near basal levels 9–11 days thereafter. Proteinuria was nonselective except at very low doses (0.1 mg OX7) where microalbuminuria was seen. F(ab′)2 OX7 administration also caused proteinuria in T16 mice. One milligram F(ab′)1 OX7 caused diffuse foot process swelling without manifest proteinuria in T16 mice. Anti-Thy 1.1 IgM monoclonal antibody did not produce the effects of OX7 in T16 mice. Foot process swelling was not modified by histamine or 5-hydroxytryptamine antagonists. OX7 did not cause complement activation or leucocyte infiltration, hence glomerular injury appeared to be mediated directly by the antibody

Erratum: Epidermal growth factor receptor promotes glomerular injury and renal failure in rapidly progressive crescentic glomerulonephritis (Nature Medicine (2011) 17 (1242-1250))

Erratum: Epidermal growth factor receptor promotes glomerular injury and renal failure in rapidly progressive crescentic glomerulonephriti

New approaches to the treatment of dense deposit disease.

Contains fulltext : 35305.pdf (publisher's version ) (Closed access)The development of clinical treatment protocols usually relies on evidence-based guidelines that focus on randomized, controlled trials. For rare renal diseases, such stringent requirements can represent a significant challenge. Dense deposit disease (DDD; also known as membranoproliferative glomerulonephritis type II) is a prototypical rare disease. It affects only two to three people per million and leads to renal failure within 10 yr in 50% of affected children. On the basis of pathophysiology, this article presents a diagnostic and treatment algorithm for patients with DDD. Diagnostic tests should assess the alternative pathway of complement for abnormalities. Treatment options include aggressive BP control and reduction of proteinuria, and on the basis of pathophysiology, animal data, and human studies, plasma infusion or exchange, rituximab, sulodexide, and eculizumab are additional options. Criteria for treatment success should be prevention of progression as determined by maintenance or improvement in renal function. A secondary criterion should be normalization of activity levels of the alternative complement pathway as measured by C3/C3d ratios and C3NeF levels. Outcomes should be reported to a central repository that is now accessible to all clinicians. As the understanding of DDD increases, novel therapies should be integrated into existing protocols for DDD and evaluated using an open-label Bayesian study design

Optimal pricing and grant policies for museums

The “free access” policy designed by the British Government has encouraged interest in museum financial issues. We define a principal-agent model for museum administration where there are two income sources: public grants and ticket revenues. This model allows us to define the optimal contract determining public grants, ticket prices, budget and managerial effort. We find a theoretical explanation for the inelastic pricing strategy commonly adopted in cultural economics. We further find that museum manager should never have any control over the price of tickets. The model can also be applied to other institutions, such as schools or NGOs, which are able to raise funds directly from private (e.g., ticket revenues or membership fees) or public sources. Copyright Springer Science+Business Media, B.V. 2006Grants, Public valuation, Public prices, Museums, Principal-agent model,