New insights into the pathogenesis of membranous glomerulonephritis

Calcineurin inhibitor therapy in combination with Tripterygium wilfordii polyglycoside tablets for idiopathic membranous nephropathy: A retrospective clinical observation

To compare the efficacy and safety of calcineurin inhibitor (CNI) and Tripterygium wilfordii polyglycoside tablets (TWPs) in treating idiopathic membranous nephropathy (IMN) with CNI and glucocorticoids (GCs).Data of patients with IMN who were treated with CNI+TWPs (TWP group) or CNI+GCs (GC group) and followed up for more than 12 months at the Affiliated Hospital of Shandong University of Traditional Chinese Medicine from 2017 to 2020 were retrospectively analyzed. The 24-h urine protein (24hUP), serum albumin (ALB), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), serum creatinine, alanine aminotransferase, and aspartate transaminase levels on the third, sixth, ninth, and twelfth months of treatment and phospholipase A2 receptor (PLA2R) level before and after treatment were compared in both groups.We recruited 64 patients who were assigned to either the GC group (n = 31) or TWP group (n = 33). No difference in baseline indicators between the two groups were observed (P > .05). After 12 months, the 24hUP levels of both groups significantly decreased compared with that at baseline (P < .01). At the end of the sixth month, 24hUP of the TWP group were less and reduced more quickly than those in the GC group (P < .05), but there is no difference at the other time point (P > .05). After treatment, the number of patients who up to the standard of TG and the ALB levels in both groups increased (P < .05), the LDL-C levels and the number of patients positive for PLA2R in both groups were reduced (P < .05), and no significant difference was observed in the overall changes of 24hUP, ALB and LDL-C levels, TG compliance rate, and PLA2R positive rate between both groups (P > .05). During treatment, no patient in either group had hepatorenal dysfunction, one case in the TWP group and two cases in the GC group experienced side effects, but no apparent difference in the side effects were observed between both groups (P > .05).Two therapeutic schemes have the advantage of reducing urinary protein excretion in patients with IMN. Compared with CNI+GCs, CNI+TWPs have high efficiency and is widely applied, which might be considered as an optimum therapy in the future.

Dysregulated levels of glycogen synthase kinase-3β (GSK-3β) and miR-135 in peripheral blood samples of cases with nephrotic syndrome

Background

Glycogen synthase kinase-3 (GSK-3β) is a serine/threonine kinase with multifunctions in various physiological procedures. Aberrant level of GSK-3β in kidney cells has a harmful role in podocyte injury.

Methods

In this article, the expression levels of GSK-3β and one of its upstream regulators, miR-135a-5p, were measured in peripheral blood mononuclear cells (PBMCs) of cases with the most common types of nephrotic syndrome (NS); focal segmental glomerulosclerosis (FSGS) and membranous glomerulonephritis (MGN). In so doing, fifty-two cases along with twenty-four healthy controls were included based on the strict criteria.

Results

Levels of GSK-3β mRNA and miR-135 were measured with quantitative real-time PCR. There were statistically significant increases in GSK-3β expression level in NS (P = 0.001), MGN (P = 0.002), and FSGS (P = 0.015) groups compared to the control group. Dysregulated levels of miR-135a-5p in PBMCs was not significant between the studied groups. Moreover, a significant decrease was observed in the expression level of miR-135a-5p in the plasma of patients with NS (P = 0.020), MGN (P = 0.040), and FSGS (P = 0.046) compared to the control group. ROC curve analysis approved a diagnostic power of GSK-3β in discriminating patients from healthy controls (AUC: 0.72, P = 0.002) with high sensitivity and specificity.

Conclusions

Dysregulated levels of GSK-3β and its regulator miR-135a may participate in the pathogenesis of NS with different etiology. Therefore, more research is needed for understanding the relationship between them.

Inhibition of tumor necrosis factor signaling attenuates renal immune cell infiltration in experimental membranous nephropathy

Idiopathic membranous nephropathy (MN) is an autoimmune-mediated glomerulonephritis and the most common cause of idiopathic nephrotic syndrome in adult humans. A tumor necrosis factor α (TNF-α)-mediated inflammatory response via TNF receptor 1 (TNFR1) and TNFR2 has been proposed as a pathogenic factor. In this study, we assessed the therapeutic response to blocking TNF signaling in experimental MN. Murine MN was induced experimentally by cationic bovine serum albumin (cBSA); phosphate-buffered saline was used in control mice. In MN mice, TNF was inhibited by etanercept blocking of TNFR1/TNFR2 or the preligand assembly domain fusion protein (PLAD.Fc), a small fusion protein that can preferentially block TNFR1 signaling. Disease severity and possible mechanisms were assessed by analyzing the metabolic and histopathology profiles, lymphocyte subsets, immunoglobulin production, oxidative stress, and apoptosis. cBSA-induced MN mice exhibited typical nephrotic syndrome and renal histopathology. MN mice given etanercept or PLAD.Fc did not exhibit significant reduction of proteinuria, amelioration of glomerular lesions, or attenuation of immune complex deposition. Immune cell subsets, serum immunoglobulin levels, production of reactive oxygen species, and cell apoptosis in the kidney were not altered by TNF inhibition. By contrast, MN mice receiving etanercept or PLAD.Fc exhibited significantly decreased infiltration of immune cells into the kidney. These results show that the therapeutic effects of blocking TNFR1 and/or TNFR2 signaling in experimental MN are not clinically effective. However, TNF signaling inhibition significantly attenuated renal immune cell infiltration in experimental MN.

miR-217 Is a Useful Diagnostic Biomarker and Regulates Human Podocyte Cells Apoptosis via Targeting TNFSF11 in Membranous Nephropathy

Background

MicroRNAs have recently been verified as useful diagnostic biomarkers in various diseases. In this study, we investigated whether miR-217 is a useful diagnostic biomarker and the possible pathological mechanism of miR-217 in this disease.

Methods

Patients with focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), and diabetic nephropathy (DN) and control patients were enrolled in this study. The miR-217 inhibitor and mimics were transfected into human podocyte cells to investigate the pathological mechanism of miR-217 in this disease. Relevant indicators were detected and tested.

Results

Compared with control patients, miR-217 was significantly downregulated and TNFSF11 was significantly upregulated in MN. Then, miR-217 had obvious separation between patients with MN and control patients, with an AUC of 0.941, a cutoff value of <750.0 copies/ul, and sensitivity and specificity of 88.9% and 75.9%. In addition, the TNFSF11 was confirmed to be the target gene of miR-217. Finally, in in vitro experiments, the upregulation of miR-217 could decrease the expression of TNFSF11 and not induce human podocyte cells apoptosis; however, the downregulation of miR-217 could bring about an opposite change.

Conclusions

miR-217 is a useful diagnostic biomarker and is involved in human podocyte cells apoptosis via targeting TNFSF11 in membranous nephropathy.

Spontaneous remission of membranous glomerulonephritis with successful fetal outcome: A case report and literature review

Membranous glomerulonephritis (MGN) represents an immunologically mediated disease characterized by deposition of immune complexes in the glomerular subepithelial space. Persistent proteinuria at diagnosis predicts poor prognosis. Pregnancy with MGN is a risk of fetal loss and may worsen maternal renal function.Here, we report a lady with MGN and proteinuria achieved spontaneous remission and successful fetal outcome naive to any medications. The 26-year old woman had 1-year history of persistent proteinuria (5.5-12.56 g/24 hours) and biopsy-proven MGN. Histopathological characteristics included glomerular basement membrane spikes, subepithelial monoclonal IgG immunofluorescence, and diffuse electron dense deposits. She was sticking to a regular morning exercise routine without any medications. After successful delivery of a full-term baby girl, the mother had improved proteinuria (0.56 g/24 hours) and albuminuria (351.96 g/24 hours contrasting 2281.6 g/24 hours before pregnancy). The baby had normal height and body weight at 4 months old.We identified more pregnancies with MGN in 5 case reports and 5 clinical series review articles (7-33 cases included). Spontaneous remission of maternal MGN with good fetal outcome rarely occurred in mothers on immunosuppressive therapy.Mothers naive to immunosuppressive therapy may achieve spontaneous remission of maternal membranous glomerulonephritis and successful fetal outcome. Theoretically, fetus might donate stem cells to heal mother's kidney.

Down-regulation of miR-186 contributes to podocytes apoptosis in membranous nephropathy

BACKGROUND AND AIM

Podocytes apoptosis is the key process in the development of membranous nephropathy and miR-186 is reported to be related with cell apoptosis. Here we investigated the expression of miR-186 in membranous nephropathy (MGN) patients and the mechanism underlying the podocytes apoptosis.

METHODS

Thirty patients with MGN and 30 healthy people were included in this study. The expression of miR-186 was detected in renal tissue and podocyte cells exposed to AngII by real-time PCR. Caspase-3 activity was used to evaluate podocytes apoptosis. TLR4 and P2×7 protein expression was quantified by western blotting. miR-186 inhibitor and miR-186 mimic were transfected into cells to investigate the mechanism underlying miR-186 in podocytes apoptosis.

RESULTS

In MGN patients, the level of miR-186 was significantly down-regulated as well as the protein expression of TLR4 and P2×7 was up-regulated in renal tissue. In vitro experiments, TLR4 siRNA increased the expression of miR-186 and miR-186 inhibitor elevated the mRNA and protein expression of P2×7 in podocytes exposed to AngII. In addition, the level of cleaved-caspase-3 was up-regulated by miR-186 inhibitor. The TUNEL-positive cells and caspase-3 activity of podocytes induced by AngII were down-regulated by miR-186 mimic.

CONCLUSIONS

We revealed that TLR4 is involved in the regulation of miR-186 expression, and the anti-apoptotic effect of miR-186 on podocytes is correlated with P2×7 regulation.

Resveratrol ameliorates renal damage, increases expression of heme oxygenase-1, and has anti-complement, anti-oxidative, and anti-apoptotic effects in a murine model of membranous nephropathy

Background

Idiopathic membranous nephropathy (MN) is an autoimmune-mediated glomerulonephritis and a common cause of nephrotic syndrome in adults. There are limited available treatments for MN. We assessed the efficacy of resveratrol (RSV) therapy for treatment of MN in a murine model of this disease.

Methods

Murine MN was experimentally induced by daily subcutaneous administration of cationic bovine serum albumin, with phosphate-buffered saline used in control mice. MN mice were untreated or given RSV. Disease severity and pathogenesis was assessed by determination of metabolic and histopathology profiles, lymphocyte subsets, immunoglobulin production, oxidative stress, apoptosis, and production of heme oxygenase-1 (HO1).

Results

MN mice given RSV had significantly reduced proteinuria and a marked amelioration of glomerular lesions. RSV also significantly attenuated immunofluorescent staining of C3, although there were no changes of serum immunoglobulin levels or immunocomplex deposition in the kidneys. RSV treatment of MN mice also reduced the production of reactive oxygen species (ROS), reduced cell apoptosis, and upregulated heme oxygenase 1 (HO1). Inhibition of HO1 with tin protoporphyrin IX partially reversed the renoprotective effects of RSV. The HO1 induced by RSV maybe via Nrf2 signaling.

Conclusion

Our results show that RSV increased the expression of HO1 and ameliorated the effects of membranous nephropathy in a mouse model due to its anti-complement, anti-oxidative, and anti-apoptotic effects. RSV appears to have potential as a treatment for MN.

Toll-like receptor 9 SNPs are susceptible to the development and progression of membranous glomerulonephritis: 27 years follow-up in Taiwan

The purpose of this study was to determine whether toll-like receptors 9 (TLR9) gene polymorphisms (rs352139 and rs352140) were markers of susceptibility to the development and progression of membranous nephropathy (MGN) in Taiwanese patients. The polymorphisms were investigated by polymerase chain reaction in 397 Taiwanese individuals (134 MGN patients and 263 controls). Patients with malignancy, chronic infectious diseases, lupus nephritis, or drug-induced secondary MGN were excluded from the study. Data showed AA genotype at rs352139 SNP or GG genotype at rs352140 SNP may indicate higher risk for MGN (odds ratio [OR] = 1.55; 95% confidence interval [CI] = 1.02-2.35, at rs352139 SNP; OR = 1.57; 95% CI = 1.03-2.39, at rs352140 SNP). However, MGN patients with A-G haplotype were susceptible for decreased creatinine clearance rate and for seriously tubule-interstitial fibrosis. The result suggests for the first time that TLR9 (rs352139 and rs352140) polymorphisms may contribute to the development and progression of MGN.

Skimmin, a Coumarin from Hydrangea paniculata, Slows down the Progression of Membranous Glomerulonephritis by Anti-Inflammatory Effects and Inhibiting Immune Complex Deposition

Skimmin is one of the major pharmacologically active molecules present in Hydrangea paniculata, a medical herb used in the traditional Chinese medicine as an anti-inflammatory agent. In the current study, we attempted to investigate its renoprotective activity and underlying mechanisms in a rat model of membranous glomerulonephritis induced by cationic bovine serum albumin (c-BSA). Sprague-Dawley (SD) rats were divided into five groups, including normal control, model control, Mycophenolate Mofetil-treated group, and two skimming-treated groups (15 mg/kg and 30 mg/kg). Our research showed that treatment with skimmin significantly reduced the levels of blood urea nitrogen (BUN), urinary albumin excretion (UAE), and serum creatinine (Scr) as compared with model control after experimental induction of membranous glomerulonephritis (P < 0.01). Moreover, glomerular hypercellularity, tubulointerstitial injury, and glomerular deposition of IgG were less intense after skimmin treatment. By immunochemistry analysis, we demonstrated that skimmin could significantly inhibit interleukin-1 β (IL1 β ) and IL-6 expression (P < 0.05), reduce the loss of nephrin and podocin, and suppress the infiltration of renal interstitium by CD3-positive T cell and CD20-positive B cell. These results suggest that treatment with skimmin can significantly improve renal function and suppress the IgG deposition as well as the development of glomerular lesions in a rat model of membranous glomerulonephritis.

Immunopathological events initiated and maintained by pathogenic IgG autoantibodies in an experimental autoimmune kidney disease

The experimental models of Heymann nephritis (HN) and slowly progressive Heymann nephritis (SPHN) give us rare opportunities to investigate the etiologies and pathogenesis of two immunopathological processes in rats leading to: (1) autoimmune disease, where the autoimmune disease HN and SPHN is initiated and maintained by cross-reactive pathogenic IgG autoantibodies (aabs) directed against the renal proximal convoluted tubules' brush border (BB) cells - where the nephritogenic antigen (ag) is produced and localized - damaging and releasing BB associated nephritogenic ag into the circulation which in turn contributes to continuation of the autoimmune disease; and (2) immune complex glomerulonephritis, where the glomerular injury is initiated, proceeding into a chronic progressive disease by depositing immune complexes (ICs) - made up of a glomerular epithelial cell produced endogenous nephritogenic ag and the developing pathogenic IgG aab directed against the nephritogenic ag, and complement components - on the epithelial side of the glomerular basement membrane. We also observed how the normally functioning immune system is able to avert autoimmune disease developments by circulating specific non-pathogenic IgM aabs clearing the system of intracytoplasmic ags released from cells at the end of their life spans or following damage by toxic agents. We also described how an autoimmune disease SPHN can be prevented and when present terminated by the implementation of a new vaccination technique we have developed and call modified vaccination technique. By increasing the specific IgM aab production against the native nephritogenic ag - by injecting ICs made up of: [nephritogenic ag X homologous anti-nephritogenic ag IgM ab] in slight ag excess into SPHN rats - pathogenic IgG aab producing native and modified nephritogenic ags were removed from the circulation and termination of the autoimmune disease causing immune events was achieved. Even though HN and SPHN are not well-known disease models, their studies are important because the etiologies and pathogenesis of two conditions - that can also occur in humans, namely autoimmune diseases and membranous glomerulonephritis - can be simultaneously investigated.

Rho-kinase inhibition prevents proteinuria in immune-complex-mediated antipodocyte nephritis

Podocyte foot process retraction is a hallmark of proteinuric glomerulonephritis. Cytoskeletal rearrangement causes a redistribution of slit membrane proteins from the glomerular filtration barrier towards the cell body. However, the underlying signaling mechanisms are presently unknown. Recently, we have developed a new experimental model of immune-mediated podocyte injury in mice, the antipodocyte nephritis (APN). Podocytes were targeted with a polyclonal antipodocyte antibody causing massive proteinuria around day 10. Rho-kinases play a central role in the organization of the actin cytoskeleton of podocytes. We therefore investigated whether inhibition of Rho-kinases would prevent podocyte disruption. C57/BL6 mice received antipodocyte serum with or without daily treatment with the specific Rho-kinase inhibitor HA-1077 (5 mg/kg). Immunoblot analysis demonstrated activation of Rho-kinase in glomeruli of antipodocyte serum-treated mice, which was prevented by HA-1077. Increased Rho-kinase activity was localized to podocytes in APN mice by immunostainings against the phosphorylated forms of Rho-kinase substrates. Rho-kinase inhibition significantly reduced podocyte loss from the glomerular tuft. Periodic acid staining demonstrated less podocyte hypertrophy in Rho-kinase-inhibited APN mice, despite similar amounts of immune complex deposition. Electron microscopy revealed reduced foot process effacement compared with untreated APN mice. Internalization of the podocyte slit membrane proteins nephrin and synaptopodin was prevented by Rho-kinase inhibition. Functionally, Rho-kinase inhibition significantly reduced proteinuria without influencing blood pressure. In rats with passive Heymann nephritis and human kidney biopsies from patients with membranous nephropathy, Rho-kinase was activated in podocytes. Together, these data suggest that increased Rho-kinase activity in the podocyte may be a mechanism for in vivo podocyte foot process retraction.

Melatonin enhances endogenous heme oxygenase-1 and represses immune responses to ameliorate experimental murine membranous nephropathy

Idiopathic membranous nephropathy (MN), an autoimmune-mediated glomerulonephritis, is one of the most common causes of nephrotic syndrome in adults. Therapeutic agents for MN remain ill defined. We assessed the efficacy of melatonin therapy for MN. Experimental murine MN was induced with cationic bovine serum albumin, and the mice were immediately administered 20 mg/kg melatonin or phosphate-buffered saline subcutaneously once a day. Disease severity was verified by examining serum and urine metabolic profiles and renal histopathology. The expression of cytokines and oxidative stress markers, cell apoptosis, and the associated mechanisms were also determined. Mice treated with melatonin displayed a significant reduction in proteinuria and a marked amelioration of glomerular lesions, with attenuated immunocomplex deposition. The subpopulations of T cells were not altered, but the CD19(+) B-cell subpopulation was significantly reduced in the MN mice treated with melatonin. The expression of cytokine mRNAs in splenocytes indicated that melatonin reduced the expression of proinflammatory cytokines and increased the expression of anti-inflammatory cytokines (interleukin 10). The production of reactive oxygen species and TUNEL-positive apoptotic cells in the kidney were also significantly reduced in the melatonin-treated MN mice. Melatonin also upregulated heme oxygenase 1 (HO1) and ameliorated MN. The blockade of HO1 expression with SnPP, a HO1 inhibitor, attenuated HO1 induction by melatonin and thus mitigated its renoprotective effects during MN. Our results suggest that melatonin treatment ameliorates experimental MN via multiple pathways, including by its antioxidative, antiapoptotic, and immunomodulatory effects. Melatonin should be considered a potential therapeutic intervention for MN in the future.

The Gne M712T mouse as a model for human glomerulopathy

Pathological glomerular hyposialylation has been implicated in certain unexplained glomerulopathies, including minimal change nephrosis, membranous glomerulonephritis, and IgA nephropathy. We studied our previously established mouse model carrying a homozygous mutation in the key enzyme of sialic acid biosynthesis, N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase. Mutant mice died before postnatal day 3 (P3) from severe glomerulopathy with podocyte effacement and segmental glomerular basement membrane splitting due to hyposialylation. Administration of the sialic acid precursor N-acetylmannosamine (ManNAc) led to improved sialylation and survival of mutant pups beyond P3. We determined the onset of the glomerulopathy in the embryonic stage. A lectin panel, distinguishing normally sialylated from hyposialylated glycans, used WGA, SNA, PNA, Jacalin, HPA, and VVA, indicating glomerular hyposialylation of predominantly O-linked glycoproteins in mutant mice. The glomerular glycoproteins nephrin and podocalyxin were hyposialylated in this unique murine model. ManNAc treatment appeared to ameliorate the hyposialylation status of mutant mice, indicated by a lectin histochemistry pattern similar to that of wild-type mice, with improved sialylation of both nephrin and podocalyxin, as well as reduced albuminuria compared with untreated mutant mice. These findings suggest application of our lectin panel for categorizing human kidney specimens based on glomerular sialylation status. Moreover, the partial restoration of glomerular architecture in ManNAc-treated mice highlights ManNAc as a potential treatment for humans affected with disorders of glomerular hyposialylation.

Production of heterologous IgG antibody against Heymann nephritis antigen by injections of immune complexes

Heterologous IgG antibody (ab) can be produced against Heymann nephritis (HN) antigen (ag) in rabbits by administering it in Freund's complete adjuvant. The developing abs reacted at high titre with rat kidney brush border (BB) regions of the renal proximal tubules in an indirect fluorescence ab test. A single IV injection of the heterologous ab into a susceptible strain of rat resulted in the localization of IgG ab to glomerular fixed ags, producing immune complex glomerular nephritis. The injected ab also reacted with the BB region of the renal proximal tubules. The aim of this experiment was to find out whether heterologous IgG ab against the HN ag can also be produced in recipient rabbits by injecting immune complexes (ICs) composed of a rat kidney tubular preparation [rat kidney fraction 3 (rKF3)] and donor rabbit-derived rabbit anti-rKF3 IgG ab. We found that anti-rKF3 IgG ab--against the BB region of the renal proximal tubules--could be induced in rabbits injected with ICs, and the resulting ab was able to initiate passive HN in rats. This was the first time a pathogenic IgG ab was produced against HN ag in rabbits without the use of adjuvant. Ab responses in recipient rabbits were achieved by ab information transfer. Recipient rabbits injected with the IC produced the same class of immunoglobulin with the same specificity against the target ag rKF3, as was present in the innoculum, namely rabbit anti-rKF3 IgG ab.

TRPC channel modulation in podocytes-inching toward novel treatments for glomerular disease

Glomerular kidney disease is a major healthcare burden and considered to represent a sum of disorders that evade a refined and effective treatment. Excellent biological and genetic studies have defined pathways that go awry in podocytes, which are the regulatory cells of the glomerular filter. The question now is how to define targets for novel improved therapies. In this review, we summarize critical points around targeting the TRPC6 channel in podocytes.

Approaching biomarkers of membranous nephropathy from a murine model to human disease

Background. Membranous glomerulonephropathy (MN) is the most prevalent cause of nephrotic syndrome in adult humans. However, the specific biomarkers of MN have not been fully elucidated. We examined the alterations in gene expression associated with the development of MN. Methods. Murine MN was induced by cationic bovine serum albumin (cBSA). After full-blown MN, cDNA microarray analysis was performed to identify gene expression changes, and highly expressed genes were evaluated as markers both in mice and human kidney samples. Results. MN mice revealed clinical proteinuria and the characteristic diffuse thickening of the glomerular basement membrane. There were 175 genes with significantly different expressions in the MN kidneys compared with the normal kidneys. Four genes, metallothionein-1 (Mt1), cathepsin D (CtsD), lymphocyte 6 antigen complex (Ly6), and laminin receptor-1 (Lamr1), were chosen and quantified. Mt1 was detected mainly in tubules, Lamr1 was highly expressed in glomeruli, and CtsD was detected both in tubules and glomeruli. The high expressions of Lamr1 and CtsD were also confirmed in human kidney biopsies. Conclusion. The murine MN model resembled the clinical and pathological features of human MN and may provide a tool for investigating MN. Applying cDNA microarray analysis may help to identify biomarkers for human MN.

Immunohistochemical evaluation of podocalyxin expression in glomerulopathies associated with nephrotic syndrome

It is now well established that morphological change of podocytes is closely correlated to the development of proteinuria. The aim of this study was to investigate the role of podocalyxin, a major podocyte protein, in the pathogenesis of glomerulopathies primarily associated with the nephrotic syndrome. Immunohistochemical expression of podocalyxin has been evaluated in 51 renal samples, including healthy controls, patients with podocytopathies (minimal change disease [MCD], focal segmental glomerulosclerosis [FSGS]) and membranous glomerulopathy (MG). A computerized image analysis program has been used. Statistical analysis was performed using analysis of variance and Bonferroni tests. Immunohistochemical expression of podocalyxin has been observed within the podocytes of healthy controls. In MCD, podocalyxin expression was globally reduced despite the normal appearance of the glomeruli. In FSGS, podocalyxin loss was observed in both the segmental sclerotic and the nonsclerotic areas being significantly more prominent in the former. Reduction of podocalyxin in MG was demonstrated for the first time immunohistochemically. The percentage of the stained area was statistical significantly higher in the controls than in each pathologic group. However, among pathologic groups (FSGS, MCD, MG), there was no statistically significant difference. This is one of the few studies investigating podocalyxin immunohistochemical expression in glomerulopathies associated with nephrotic syndrome. The observed reduction in podocalyxin expression suggests that it constitutes a target molecule in nephrotic syndrome pathogenesis regardless of the underlying cause.

Successful treatment of membranous glomerulonephritis with rituximab in calcineurin inhibitor-dependent patients

BACKGROUND AND OBJECTIVES

Calcineurin inhibitors (CNIs) induce remission of proteinuria in most nephrotic patients with membranous glomerulonephropathy (MGN). However, 60% of patients become treatment dependent and are at risk of chronic nephrotoxicity. The aim of this study was to evaluate the efficacy of rituximab in patients with long-term dependence on CNIs.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Thirteen patients with MGN, normal renal function, and proven dependence on CNIs, despite previous treatment with other immunosuppressant drugs, received a single trial of four weekly doses of rituximab (375 mg/m(2)). Outcome measures were the percentage of patients with CNI withdrawal and no evidence of relapse and the percentage of patients with complete or partial remission 30 mo after CNI withdrawal.

RESULTS

After rituximab, proteinuria decreased significantly (2.5 +/- 0,76 basal versus 0.85 +/- 0.17 at 6 mo; P = .0003). CNIs and other immunosuppressant drugs could be withdrawn in all patients with no evidence of relapse. After CNI withdrawal, GFR increased significantly (90.3 +/- 15 basal to 106.4 +/- 20 at 3 mo with a mean increase of 15.3% [range 0-20]). Three patients suffered a relapse of nephrotic proteinuria 19, 23, and 28 mo after rituximab treatment; all were successfully treated with a second course of rituximab. At 30 mo, all patients were in remission.

CONCLUSIONS

In patients with MGN with long-term CNI dependence, rituximab can be an effective tool to overcome dependence on CNI, thus avoiding the risk of nephrotoxicity related to the chronic exposure to these drugs.

HO-1 induction ameliorates experimental murine membranous nephropathy: anti-oxidative, anti-apoptotic and immunomodulatory effects

BACKGROUND

Therapeutic agents for membranous nephropathy (MN) remain ill-defined. Haeme oxygenase (HO)-1 is considered to play a protective role in various disorders. Here, we assessed the efficacy of HO-1 induction therapy for MN.

METHODS

MN was induced in BALB/c mice with intravenous injections of cationic bovine serum albumin. Three groups of mice were administered 100 micromol/kg Cobalt protoporphyrin (CoPP, a potent HO-1 inducer), Tin protoporphyrin (SnPP, a potent HO-1 inhibitor) or phosphate-buffered saline via intra-peritoneal injections once a week starting from the induction of MN. Disease severity was verified by serum and urine metabolic profiles and by renal histopathology. Cytokine profiles, immunoglobulin production, the expression of oxidative stress markers (thiobarbituric acid reactive substances, TBARS) and apoptosis, as measured by TUNEL, were also determined.

RESULTS

Mice treated with CoPP displayed a significant reduction in proteinuria and a marked amelioration of glomerular lesions, accompanied by attenuated immune-complex deposition. The production of immunoglobulins in MN mice treated with CoPP was significantly reduced compared with that of mice in the other two groups. TBARS in the serum and kidneys, as well as apoptosis, were also significantly reduced in CoPP-treated mice. Cytokine mRNA expression in the renal cortex indicated that CoPP not only decreased the expression of proinflammatory cytokines, but also increased the expression of anti-inflammatory cytokines (interleukin-10).

CONCLUSIONS

HO-1 induction therapy may ameliorate experimental MN via multiple pathways, including anti-oxidative, anti-apoptotic and immunomodulatory effects. HO-1 inducing regimens should be considered as a potential therapeutic intervention in MN in the future.

Transgenerational epigenetic effects of the endocrine disruptor vinclozolin on pregnancies and female adult onset disease

Endocrine disruptor exposure during gonadal sex determination was previously found to induce male rat adult onset transgenerational disease (F1-F4 generation), and this was associated with an alteration in the epigenetic (i.e., DNA methylation) programming of the male germ line. The current study was designed to characterize the transgenerational disease phenotypes of the female adult offspring. Pregnant rats (F0 generation) were treated transiently with vinclozolin (i.e., fungicide with anti-androgenic activity) on embryonic (E) days E8-E14 of gestation. F1 control and vinclozolin generation offspring from different litters were mated to produce F2 offspring, and similarly F2 generation animals produced F3 generation offspring. Observations demonstrated that 9 out of 105 pregnant rats (8.6%) from the vinclozolin F1-F3 generations exhibited uterine hemorrhage and/or anemia late in pregnancy. None (0 out of 82) of the control F1-F3 generation females had similar pregnancy problems. Complete blood cell counts and serum chemistry profiles demonstrated that selected vinclozolin generation animals, but not controls, exhibited marked regenerative anemia in late pregnancy. Examination of kidney histology revealed moderate or severe glomerular abnormalities in 67% of the vinclozolin F2 and F3 generation adult females compared with 18% of the controls. Adult female vinclozolin generation animals also developed various types of tumors in 6.5% of the animals (11 out of 170), while 2% of control-line animals (3 out of 151) developed mammary tumors. Observations demonstrate that vinclozolin exposure during gonadal sex determination promotes a transgenerational increase in pregnancy abnormalities and female adult onset disease states.

Infection and glomerulonephritis

Glomerular injury, occurring either as primary glomerular disease or as part of a systemic disease process, is usually a result of immune-mediated mechanisms. The morphologic reaction pattern has a diverse spectrum of appearance, ranging from normal by light microscopy in minimal change disease to crescentic forms of glomerulonephritis, with conspicuous disruption of the normal glomerular morphology. The mechanisms of glomerular immune deposit formation include trapping of circulating antigen-antibody complexes and the in situ formation of immune complexes within the glomerulus. While the majority of postinfectious immune-complex-mediated glomerulonephritides are believed to result from the deposition of circulating antigen-antibody complexes, preformed outside of the kidney and secondarily deposited in the kidney, the notion of forming in situ antigen-antibody complexes to either planted antigens or to integral structural components of the glomerulus, through "cross-reacting" autoimmune reactions, is gaining popularity in a variety of forms of glomerulonephritides. Patients with HIV infection may develop a spectrum of renal pathology, the glomerular manifestations of which include both antigen-antibody complex and nonimmune-complex-mediated pathogenetic mechanisms. Similarly, patients with Streptococcal infections, Hepatitis B virus, or Hepatitis C virus infection may develop a spectrum of glomerulonephritides, which are predominantly immune-complex-mediated. Therapy for glomerular diseases due to HIV, hepatitis B, or C virus infections remains a challenge.

Titrating rituximab to circulating B cells to optimize lymphocytolytic therapy in idiopathic membranous nephropathy

BACKGROUND AND OBJECTIVES

Rituximab, given in four weekly doses, is a promising treatment for idiopathic membranous nephropathy and other immune-mediated diseases and lymphoproliferative disorders. This multidose regimen, however, may cause hypersensitivity reactions and is extremely expensive. This study was aimed at evaluating whether titrating rituximab to circulating CD20 B cells may improve safety and limit costs of treatment.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In a matched-cohort, single-center, controlled study, the outcome of 12 new incident patients who had idiopathic membranous nephropathy and nephrotic syndrome and received a B cell-driven treatment was compared with that of 24 historical reference patients who were given the standard protocol of four weekly doses of 375 mg/m2.

RESULTS

Only one patient needed a second dose to achieve full CD20 cell depletion. At 1 yr, time course of the components of nephrotic syndrome and the proportion of patients who achieved disease remission (25%) was identical in both groups. Persistent CD20 cell depletion was achieved in all patients. Costs for rituximab treatment and hospitalizations totalled 3770.90 euros ($4902.20) and 13,977.60 euros ($18,170.80) with the B cell-driven and the four-dose protocol, respectively. One patient on standard protocol had a severe adverse reaction at second rituximab dose. Thus, B cell titrated as effectively as standard rituximab treatment achieves B cell depletion and idiopathic membranous nephropathy remission but is fourfold less expensive, allowing for more than 10,000 euros, approximately $13,000 in savings per patient.

CONCLUSIONS

Avoiding unnecessary reexposure to rituximab is extremely cost-saving and may limit the production of antichimeric antibodies that may increase the risk for adverse reactions and prevent re-treatment of disease recurrences.

Mutation in the key enzyme of sialic acid biosynthesis causes severe glomerular proteinuria and is rescued by N-acetylmannosamine

Mutations in the key enzyme of sialic acid biosynthesis, uridine diphospho-N-acetylglucosamine 2-epimerase/N-acetylmannosamine (ManNAc) kinase (GNE/MNK), result in hereditary inclusion body myopathy (HIBM), an adult-onset, progressive neuromuscular disorder. We created knockin mice harboring the M712T Gne/Mnk mutation. Homozygous mutant (Gne(M712T/M712T)) mice did not survive beyond P3. At P2, significantly decreased Gne-epimerase activity was observed in Gne(M712T/M712T) muscle, but no myopathic features were apparent. Rather, homozygous mutant mice had glomerular hematuria, proteinuria, and podocytopathy. Renal findings included segmental splitting of the glomerular basement membrane, effacement of podocyte foot processes, and reduced sialylation of the major podocyte sialoprotein, podocalyxin. ManNAc administration yielded survival beyond P3 in 43% of the Gne(M712T/M712T) pups. Survivors exhibited improved renal histology, increased sialylation of podocalyxin, and increased Gne/Mnk protein expression and Gne-epimerase activities. These findings establish this Gne(M712T/M712T) knockin mouse as what we believe to be the first genetic model of podocyte injury and segmental glomerular basement membrane splitting due to hyposialylation. The results also support evaluation of ManNAc as a treatment not only for HIBM but also for renal disorders involving proteinuria and hematuria due to podocytopathy and/or segmental splitting of the glomerular basement membrane.

Anti-CD20 monoclonal antibody (rituximab) for the treatment of recurrent idiopathic membranous nephropathy in a renal transplant patient

Idiopathic membranous nephropathy (IMN) remains the most common histologic entity associated with adult-onset nephrotic syndrome. The therapy for IMN is challenging. Steroids and various other immunosuppressive agents have been tried in IMN; however, current agents have not altered the course of IMN, are nonspecific and can be very toxic. In native kidneys affected by IMN, rituximab, a monoclonal antibody against the B-cell surface antigen CD20, has been shown to reduce proteinuria and prevent disease progression. In this report, we describe a 39-year-old white male with end-stage renal disease secondary to IMN that, 4 months post living unrelated kidney transplant, developed recurrent IMN with 18 g/day of proteinuria. In addition to angiotensin converting enzyme inhibitor and statins, the patient was treated with 4 weekly doses of 375 mg/m2 of rituximab with significant reduction in proteinuria, a corresponding increase in serum albumin and improvement in hypercholesterolemia. At 3 years post-transplant, his kidney function remains stable with 0.5 g/day of proteinuria.