Experimental model of membranous nephropathy in mice: sequence of histological and biochemical events

Decay-Accelerating Factor Restrains Complement Activation and Delays Progression of Murine cBSA-Induced Membranous Nephropathy

Key Points

In a murine model of cationic bovine serum albumin (cBSA)–induced membranous nephropathy (MN), complement regulator decay-accelerating factor is upregulated and restrains complement activation. Studies using genetic deletion or pharmacological antagonism of C3aR indicate that the main effector mechanism of complement activation in cBSA-induced MN is C3a/C3aR signaling. C3a formation and/or C3aR-mediated signaling represent promising targets for hypothesis-driven therapies for MN.

Background

Complement activation is believed to play a major pathogenic role in membranous nephropathy (MN), but its effector mechanisms are still unclear. Even less investigated is the role of podocyte-expressed complement regulators, including decay-accelerating factor (DAF) in disease pathophysiology.

Methods

We induced MN by serial injections of cationic bovine serum albumin (cBSA) in WT, DAF−/−, and C3aR−/− BALB/c mice and measured disease severity (by albuminuria, BUN, serum albumin, and glomerular histologic changes) and signs of complement activation in the glomeruli (immunofluorescence for C1q, C3b, and membrane attack complex). We also treated DAF−/− mice with cBSA-induced MN with a selective C3aR antagonist and measured the same readouts.

Results

cBSA-induced MN was associated with increased glomerular expression of DAF. Genetic deletion of DAF resulted in increased complement activation and higher disease severity than in WT animals. Treating cBSA-injected DAF−/− mice with a C3aR antagonist reduced disease severity. Similarly, C3aR−/− animals were protected from cBSA-induced MN, despite IgG deposition in the glomeruli and complement activation. Evidence of C1q and C3b deposition in the glomeruli of these mice suggest that IgG-cBSA immune complex formation in the glomeruli activates complement through the classical pathway.

Conclusions

On cBSA-induced injury, podocytes upregulate DAF expression, which restrains complement activation. However, after prolonged injury, complement activation overcomes DAF regulatory effects leading to the formation of soluble anaphylatoxin C3a that, by signaling through C3aR, promotes glomerular injury and cBSA-induced MN disease progression. Considering the growing number of complement targeting therapies, our findings may have major translational effect on the treatment of patients with MN.

uPA deficiency aggravates cBSA-induced membranous nephropathy through Th2-prone immune response in mice

Urokinase plasminogen activator (uPA) is a crucial activator of the fibrinolytic system that modulates tissue remodeling, cancer progression, and inflammation. However, its role in membranous nephropathy (MN) remains unclear. To clarify this issue, an established mouse model mimicking human MN induced by cationic bovine serum albumin (cBSA) in BALB/c mice was used, which have a Th2-prone genetic background. To induce MN, cBSA was injected into Plau knockout (Plau-/-) and wild-type (WT) mice. The blood and urine samples were collected to measure biochemical parameters, including serum concentrations of IgG1 and IgG2a, using enzyme-linked immunoassay. The kidneys were histologically examined for the presence of glomerular polyanions, reactive oxygen species (ROS), and apoptosis, and transmission electron microscopy was used to examine subepithelial deposits. Lymphocyte subsets were determined by flow cytometry. Four weeks post-cBSA administration, Plau-/- mice exhibited a significantly high urine protein/creatine ratio, hypoalbuminemia, and hypercholesterolemia compared with WT mice. Histologically, compared with WT mice, Plau-/- mice showed more severe glomerular basement thickening, mesangial expansion, IgG granular deposition, intensified podocyte effacement, irregular thickening of glomerular basement membrane and subepithelial deposits, and abolishment of the glycocalyx. Moreover, increased renal ROS and apoptosis were observed in Plau-/- mice with MN. B lymphocyte subsets and the IgG1/IgG2a ratio were significantly higher in Plau-/- mice after MN induction. Thus, uPA deficiency induces a Th2-dominant immune response, leading to increased subepithelial deposits, ROS, and apoptosis in the kidneys, subsequently exacerbating MN progression in mice. This study provides a novel insight into the role of uPA in MN progression.

Rodent models to study sodium retention in experimental nephrotic syndrome

Sodium retention and edema are hallmarks of nephrotic syndrome (NS). Different experimental rodent models have been established for simulating NS, however, not all of them feature sodium retention which requires proteinuria to exceed a certain threshold. In rats, puromycin aminonucleoside nephrosis (PAN) is a classic NS model introduced in 1955 that was adopted as doxorubicin-induced nephropathy (DIN) in 129S1/SvImJ mice. In recent years, mice with inducible podocin deletion (Nphs2^Δipod ) or podocyte apoptosis (POD-ATTAC) have been developed. In these models, sodium retention is thought to be caused by activation of the epithelial sodium channel (ENaC) in the distal nephron through aberrantly filtered serine proteases or proteasuria. Strikingly, rodent NS models follow an identical chronological time course after the development of proteinuria featuring sodium retention within days and spontaneous reversal thereafter. In DIN and Nphs2^Δipod mice, inhibition of ENaC by amiloride or urinary serine protease activity by aprotinin prevents sodium retention, opening up new and promising therapeutic approaches that could be translated into the treatment of nephrotic patients. However, the essential serine protease(s) responsible for ENaC activation is (are) still unknown. With the use of nephrotic rodent models, there is the possibility that this (these) will be identified in the future. This review summarizes the various rodent models used to study experimental nephrotic syndrome and the insights gained from these models with regard to the pathophysiology of sodium retention.

Downregulation of AANAT by c-Fos in tubular epithelial cells with membranous nephropathy

Melatonin is a hormone majorly secreted by the pineal gland and contributes to a various type of physiological functions in mammals. The melatonin production is tightly limited to the AANAT level, yet the most known molecular mechanisms underlying AANAT gene transcription is limited in the pinealocyte. Here, we find that c-Fos and cAMP-response element-binding protein (CREB) decreases and increases the AANAT transcriptional activity in renal tubular epithelial cell, respectively. Notably, c-Fos knockdown significantly upregulates melatonin levels in renal tubular cells. Functional results indicate that AANAT expression is decreased by c-Fos and resulted in enhancement of cell damage in albumin-injury cell model. We further find an inverse correlation between c-Fos and AANAT levels in renal tubular cells from experimental membranous nephropathy (MN) samples and clinical MN specimens. Our finding provides the molecular basis of c-Fos in transcriptionally downregulating expression of AANAT and melatonin, and elucidate the protective role of AANAT in preventing renal tubular cells death in albumin-injury cell model and MN progression.

The MTNR1A mRNA is stabilized by the cytoplasmic hnRNPL in renal tubular cells

The downregulation of melatonin receptor 1A (MTNR1A) is associated with a range of pathological conditions, including membranous nephropathy. Knowledge of the mechanism underlying MTNR1A expression has been limited to the transcriptional regulation level. Here, RNA interference screening in human kidney cells revealed that heterogeneous nuclear ribonucleoprotein L (hnRNPL) upregulated MTNR1A RNA post-transcriptionally. hnRNPL knockdown or overexpression led to increased or decreased levels of cyclic adenosine monophosphate-responsive element-binding protein phosphorylation, respectively. Molecular studies showed that cytoplasmic hnRNPL exerts a stabilizing effect on the MTNR1A transcript through CA-repeat elements in its coding region. Further studies revealed that the interaction between hnRNPL and MTNR1A serves to protect MNTR1A RNA degradation by the exosome component 10 protein. MTNR1A, but not hnRNPL, displays a diurnal rhythm in mouse kidneys. Enhanced levels of MTNR1A recorded at midnight correlated with robust binding activity between cytoplasmic hnRNPL and the MTNR1A transcript. Both hnRNPL and MTNR1A were decreased in the cytoplasm of tubular epithelial cells from experimental membranous nephropathy kidneys, supporting their clinical relevance. Collectively, our data identified cytoplasmic hnRNPL as a novel player in the upregulation of MTNR1A expression in renal tubular epithelial cells, and as a potential therapeutic target.

Clusterin Deficiency Predisposes C57BL/6j Mice to Cationic Bovine Serum Albumin-Induced Glomerular Inflammation

Background

Membranous nephropathy (MN) is a specific entity of glomerulonephritis, and its glomerular inflammation is characterized by the deposition of immune complexes in the glomerular basement membrane and proteinuria. However, the molecular mechanisms underlying the glomerular inflammation of MN are not fully understood. This study was designed to investigate the role of clusterin (CLU) in the development of MN using a mouse model of cationic bovine serum albumin (cBSA)-induced MN.

Methods

Both wild-type C57BL/6j (WT) and CLU-knockout C57BL/6j (CLU-KO) mice were immunized with cBSA. The kidney function was determined by the levels of serum creatinine (SCr), blood urea nitrogen (BUN) and urinary protein. MN and glomerular deposits of CLU, complement C3 and immunoglobulins (Igs) were determined by histological analyses. Serum proteins were analyzed by the enzyme-linked immunosorbent assay, Western blot and liquid chromatography-mass spectrometry.

Results

Here, we showed that after cBSA immunization, SCr and proteinuria were increased in CLU-KO mice but not in WT mice. Similarly, severe glomerular atrophy and mesangial expansion along with C3 deposit were only found in the kidneys of CLU-KO mice but not in WT mice. However, there were no differences of serum IgG and complement 3 levels between CLU-KO and WT mice. In the serum of WT mice, CLU bound to anti-cBSA IgG, complements (eg, C8), proteinase/protease inhibitors and antioxidative proteins to form a complex, and incubation with WT serum reduced the complement-dependent lysis of podocytes in cultures.

Conclusion

Our data suggest that a CLU deficiency induces cBSA-initiated glomerular inflammation of MN in a disease-resistant strain of mice, suggesting an anti-glomerular inflammatory function of CLU in the resistance to MN development. This function may be at least in part due to the formation of CLU-anti-cBSA Igs complex that prevents glomerular inflammation or injury in the disease-resistant mice.

Role of melatonin receptor 1A and pituitary homeobox-1 coexpression in protecting tubular epithelial cells in membranous nephropathy

Membranous nephropathy (MN), a type of glomerular nephritis, is one of the most common causes of nephrotic syndrome in adults. Although it is known that melatonin plays a protective role in MN, the role of melatonin receptors in the pathophysiology of MN is unclear. Using an experimental MN model and clinical MN specimens, we studied melatonin receptor expression and found that melatonin receptor 1A (MTNR1A) expression was significantly downregulated in renal tubular epithelial cells. Molecular studies showed that the transcription factor pituitary homeobox-1 (PITX1) promoted MTNR1A expression via direct binding to its promoter. Treatment of a human tubular cell line with albumin to induce injury resulted in the stable reduction in MTNR1A and PITX1 expression. PITX1 levels were significantly downregulated in tubular epithelial cells from mice MN kidneys and MN renal specimens. Knockdown of MTNR1A, PITX1, or cyclic adenosine monophosphate-responsive element-binding protein (CREB) decreased E-cadherin (CDH1) expression, but upregulated Per2 and α-smooth muscle actin (αSMA) expression. Blockade of the MTNR1A receptor with luzindole in MN mice further impaired renal function; this was accompanied by CDH1 downregulation and Per2 and αSMA upregulation. Together, our results suggest that in injured tissue, decreased PITX1 expression at the MTNR1A promoter regions leads to decreased levels of MTNR1A in renal tubular epithelial cells, which increases the future risk of MN.

The natural compound 2,3,5,4'-tetrahydroxystilbene-2-O-β-d glucoside protects against adriamycin-induced nephropathy through activating the Nrf2-Keap1 antioxidant pathway

2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-glucoside (THSG) is an active compound extracted from Polygonum multiflorum Thunb. This herb and radix Polygoni Multiflori preparata have been used to treat arteriosclerosis, hyperlipidemia, hypercholesterolemia, and diabetes for thousands of years. This study aimed to investigate the protective effects of THSG in an Adriamycin (AD)-induced focal segmental glomerulosclerosis (FSGS) mouse model and the underlying mechanisms in an in vitro system. Mice were treated with THSG (2.5 and 10 mg/kg, oral gavage) for 24 consecutive days. On the third day, mice were intravenously given a single dose of AD (10 mg/kg). At the end of the experiment, plasma and kidney samples were harvested to evaluate the therapeutic effects of THSG. The potential mechanisms of THSG in protecting against AD-induced cytotoxicity were examined using a real-time polymerase chain reaction, immunoblots, lactate dehydrogenase assay, and a cellular oxidized-thiol detection system in a mouse mesangial cell line. In this study, THSG showed concentration-dependent protective effects in ameliorating the progression of AD-induced FSGS. THSG suppressed albuminuria and hypercholesterolemia and reduced the status of lipid peroxidation in urine, plasma, and kidney tissue samples. Furthermore, THSG protected against podocyte damage, reduced renal fibrotic gene expressions, and alleviated the severity of glomerulosclerosis. Treatment of mouse mesangial cells with THSG induced nuclear factor erythroid-derived 2-like 2 (Nrf2) nuclear translocation, increased heme oxygenase-1 and NAD(P)H:quinone oxidoreductase (NQO)-1 gene expressions, and reduced cellular thiol oxidation and resistance to AD-induced cytotoxicity. Silencing Nrf2 and its repressor protein, Kelch-like ECH-associated protein 1 (Keap1), abolished these protective effects of THSG. In conclusion, THSG can play a protective role in ameliorating the progression of FSGS in a mouse model through activation of the Nrf2-Keap1 antioxidant pathway. Although a well-designed therapeutic study is needed, THSG may be applied to manage chronic kidney disease.

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.

Vanillic Acid Ameliorates Cationic Bovine Serum Albumin Induced Immune Complex Glomerulonephritis in BALB/c Mice

Preclinical Research Vanillic acid (VA) is a dihydroxybenzoic acid derivative widely used as a flavoring agent. It has chemopreventive effects on experimentally-induced carcinogenesis and in ulcerative colitis. The object of the present study was to investigate the effects of VA, alone and in combination with methylprednisolone (MP), on cationic bovine serum albumin (cBSA induced immune-complex glomerulonephritis in female BALB/c mice. Pre-immunization was carried out with cBSA in BALB/c mice and repeated (cBSA, 13 mg/kg, 3 times/week, i.v.) for 6 weeks to induce glomerulonephritis which was confirmed by the presence of severe proteinuria. The effect of VA (50, 100, and 200 mg/kg, p.o.) and its combination with MP (12.5 mg/kg, p.o.) was assessed in the nephrotic disease model. Treatment with VA decreased inflammatory nephrotic injury as evidenced by decreased proteinuria, serum creatinine, blood urea nitrogen, serum IgG1 and TNF-α levels. Co-administration of VA with MP showed an improvement in the immunohistochemistry of glomerular nephrin and podocin. The present results indicate that VA has a nephroprotective effect in the management of autoimmune nephritis. Drug Dev Res 77 : 171-179, 2016.   © 2016 Wiley Periodicals, Inc.

Significance of the urokinase-type plasminogen activator and its receptor in the progression of focal segmental glomerulosclerosis in clinical and mouse models

Background

suPAR biomarker generally considered a pathogenic factor in FSGS. However, studies have been published that dispute this conclusion. The current study was designed to investigate the roles of uPA and suPAR in FSGS in clinical and mouse models.

Methods

Clinical subjects including those with biopsy-proven FSGS and MCD were enrolled. To verify the role of uPA in FSGS, Adriamycin was used to induce FSGS in uPA knockout (uPA^−/−) and BALB/c (WT) mice. Proteinuria and suPAR, the cleaved/intact forms of the circulating suPAR, and possible proteases involving cleavage of the suPAR were also studied.

Results

FSGS clinical cases presented significantly higher serum levels of suPAR and Cr and lower serum levels of uPA. In the mice model, the uPA^−/− group exhibited faster disease progression and worsening proteinuria than the WT group. In addition, the uPA^−/− group had higher plasma suPAR levels, glomerular cell apoptosis, and dysregulation of the Th1/Th2 balance. In an analysis of suPAR variants in FSGS, both the intact and cleaved forms of the suPAR were higher in clinical subjects and the mouse model. However, the process of suPAR cleavage was not mediated by enzymatic activities of the uPA, elastase, or cathepsin G.

Conclusions

A deficiency of uPA accelerated the progression of Adriamycin-induced mouse FSGS model. Decrease of serum uPA levels may be an indicator of the progression of FSGS in clinical subjects and animal models.

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.

Chaperonin-containing t-complex protein-1 subunit β as a possible biomarker for the phase of glomerular hyperfiltration of diabetic nephropathy

In cell model, we discovered the association between chaperonin-containing t-complex polypeptide 1 subunit β (TCP-1β) and early diabetic nephropathy (DN). In this study, we further explored the relationships between TCP-1β and type 2 diabetic mellitus (DM). To mimic the clinical hyperfiltration state, a type 2 DM mice model was established by feeding a high-fat diet in combination with treatment of streptozotocin and nicotinamide. Blood and urine were collected to determine creatinine clearance (C_cr), and kidney tissues were harvested for evaluation of TCP-1β expression by immunohistochemistry and Western blot. Meanwhile, clinical subjects of healthy controls and type 2 DM were recruited to strengthen the evidence with urine TCP-1β. Results showed that C_cr and the expression of TCP-1β in kidney were significantly higher one week after hyperglycemia development, suggesting that the hyperfiltration state was successfully established in the mice model. TCP-1β was expressed predominantly on renal tubules. By using the estimated glomerular filtration rate to index progression in clinical investigation, urine TCP-1β level was associated with the hyperfiltration phase in type 2 DM patients. Conclusively, we confirmed that TCP-1β is a possible biomarker for early nephropathy of type 2 DM, but further mechanistic study to elucidate its cause and pathway is needed.

Phosphotriesterase-related protein sensed albuminuria and conferred renal tubular cell activation in membranous nephropathy

Background

Membranous nephropathy (MN) is a common cause of nephrotic syndrome that may progress to end-stage renal disease (ESRD). The formation of MN involves the in situ formation of subepithelial immune deposits and leads to albuminuria; however, the underlying mechanism of how MN leads to ESRD remains unclear. The aim of this study was to investigate the expression and biological functions of phosphotriesterase-related protein (PTER) in MN.

Results

In the progression of MN, the expression of PTER increased significantly and was mainly expressed in the renal tubular cells. Both mRNA and protein expression levels of PTER were increased in a concentration- and time-dependent manner in the in vitro albuminuria tubular cell model. Silencing the expression of PTER by RNA interference diminished albuminuria-induced inflammatory and pro-fibrotic cytokines production.

Conclusions

Our findings reveal that PTER may sense albuminuria in the progression of MN, induce tubular cell activation and lead to ESRD.

Ferulic Acid, an Angelica sinensis-Derived Polyphenol, Slows the Progression of Membranous Nephropathy in a Mouse Model

Membranous nephropathy (MN) is a leading cause of adult nephrotic syndrome but lacks adequate treatment. Different extracts of Angelica sinensis (AS) and one of its active compounds, ferulic acid (FA), were used to evaluate the therapeutic effects in a MN mouse model. The MN model was grouped into three subgroups: no treatment (N-T), treatment at induction of MN (Pre-T), and treatment after full-blown MN (Post-T). The results showed that the methanol (ME) layer of AS extract exhibited a therapeutic effect on MN-induced proteinuria. The ME layer-enriched compound, FA, improved the hypoalbuminemia, hyperlipidemia, and proteinuria in both Pre-T and Post-T groups. Ferulic acid also reduced the formation of oxidative protein products and increased the synthesis of antioxidant enzymes in groups Pre-T and Post-T. Regarding angiogenesis factors, the antiangiogenic factors in renal glomeruli were increased in group N-T, but, after FA treatment, only one of the antiangiogenic factors, thrombospondin-1, showed a significant decrease. Furthermore, the expression of Th2 predominant showed significant decrease in both Pre-T and Post-T groups when compared to that of N-T group. In summary, FA retarded the progression of MN, and the mechanisms involved the regulation of oxidative stresses, angiogenic and antiangiogenic factors, and attenuation of Th2 response.

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.

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.