The experimental model of nephrotic syndrome induced by Doxorubicin in rodents: an update

Nicotinamide ameliorates podocyte injury and albuminuria in adriamycin-induced nephropathy

Podocytes are key components of the glomerular filtration barrier, and their injury leads to proteinuria, chronic kidney disease (CKD), and nephrotic syndrome. Effective treatments for these conditions are not well established, and prevention of podocyte injury is a crucial challenge. Nicotinamide (NAM), a form of vitamin B3, has been reported to exert beneficial effects in various renal disease models due to its antioxidant and anti-inflammatory properties and its ability to replenish nicotinamide adenine dinucleotide (NAD+). However, its impact on adriamycin (ADR)-induced nephropathy, a model of nephrotic syndrome caused by podocyte injury, remains unclear. We investigated the effects of NAM administration in a mouse model of ADR nephropathy. BALB/c mice were intravenously administered ADR to induce nephropathy. In the NAM-treated group, mice received 0.6% NAM in drinking water ad libitum starting 7 days before ADR administration. After 14 days, NAM treatment decreased albuminuria, glomerular sclerosis, and podocyte injury, and reduced inflammation and oxidative stress markers in the kidneys. NAM and NAD+ levels were decreased in ADR-treated kidneys, and the expression of the NAD+-consuming enzymes SIRT1 and poly(ADP-ribose) polymerase 1 (PARP-1) was decreased and increased, respectively. Nicotinamide N-methyltransferase expression was increased. NAM canceled these abnormalities. In cultured rat podocytes, NAD+ alleviated ADR-induced cytotoxicity, apoptosis, and inflammation. These findings suggest that NAM prevents ADR nephropathy and podocyte injury, likely through NAD+ replenishment.NEW & NOTEWORTHY Nephrotic syndrome can lead to end-stage kidney disease and cause severe complications. Currently, effective treatments for nephrotic syndrome have not been established, and new therapeutic approaches targeting podocyte injury are needed. Nicotinamide prevents podocyte injury in adriamycin-induced nephropathy in mice and ameliorates albuminuria, pathological changes, oxidative stress, and inflammation. Here, we provide evidence that pretreatment with nicotinamide can attenuate podocyte injury and subsequent nephropathy in mice.

Nanoenzyme-based sensors for the detection of anti-tumor drugs

Natural enzymes are a class of biological catalysts that can catalyze a specific substrate. Although natural enzymes have catalytic activity, they are susceptible to the influence of external environment such as temperature, and storage requirements are more stringent. Since the first discovery of magnetic Fe3O4 nanoparticles with peroxidase-like activity in 2007, the research on nanoenzymes has entered a rapid development stage. Nanoenzymes synthesized by chemical methods not only have the catalytic activity of natural enzymes but also are more stable, easy to store, and convenient to prepare. Anthracyclines, as a commonly used anti-tumor chemotherapy drug, will produce many side effects such as myelosuppression and liver function damage after long-term use, which will affect its therapeutic effects. This paper reviews the characteristics, classification, and mechanisms of nanoenzymes. The detection of anti-tumor drugs, especially anthracycline drugs, using a nanoenzyme-based sensor was emphatically introduced. On this basis, the application of nanoenzyme-based sensors in the detection of anti-tumor drugs is  prospected.

Characterization of a new model of chemotherapy-induced heart failure with reduced ejection fraction and nephrotic syndrome in Ren-2 transgenic rats

All anthracyclines, including doxorubicin (DOXO), the most common and still indispensable drug, exhibit cardiotoxicity with inherent risk of irreversible cardiomyopathy leading to heart failure with reduced ejection fraction (HFrEF). Current pharmacological strategies are clearly less effective for this type of HFrEF, hence an urgent need for new therapeutic approaches. The prerequisite for success is thorough understanding of pathophysiology of this HFrEF form, which requires an appropriate animal model of the disease. The aim of this study was to comprehensively characterise a novel model of HF with cardiorenal syndrome, i.e. DOXO-induced HFrEF with nephrotic syndrome, in which DOXO was administered to Ren-2 transgenic rats (TGR) via five intravenous injections in a cumulative dose of 10 mg/kg of body weight (BW). Our analysis included survival, echocardiography, as well as histological examination of the heart and kidneys, blood pressure, but also a broad spectrum of biomarkers to evaluate cardiac remodelling, fibrosis, apoptosis, oxidative stress and more. We have shown that the new model adequately mimics the cardiac remodelling described as "eccentric chamber atrophy" and myocardial damage typical for DOXO-related cardiotoxicity, without major damage of the peritoneum, lungs and liver. This pattern corresponds well to a clinical situation of cancer patients receiving anthracyclines, where HF develops with some delay after the anticancer therapy. Therefore, this study may serve as a comprehensive reference for all types of research on DOXO-related cardiotoxicity, proving especially useful in the search for new therapeutic strategies.

PPAR-α Insufficiency Enhances Doxorubicin-Induced Nephropathy in PPAR-α Knockout Mice and a Murine Podocyte Cell Line

Peroxisome proliferator-activated receptor-alpha (PPAR-α) and its exogenous activators (fibrates) promote autophagy. However, whether the deleterious effects of PPAR-α deficiency on doxorubicin (DOX)-induced podocytopathy are associated with reduced autophagy remains to be clarified. We investigated the mechanisms of PPAR-α in DOX-induced podocytopathy and tubular injury in PPAR-α knockout (PAKO) mice and in a murine podocyte cell line. DOX-treated PAKO mice showed higher serum levels of triglycerides and non-esterified fatty acids and more severe podocytopathy than DOX-treated wild-type mice, as evidenced by higher urinary levels of proteins and podocalyxin at 3 days to 2 weeks and higher blood urea nitrogen and serum creatinine levels at 4 weeks. Additionally, there was an increased accumulation of p62, a negative autophagy marker, in the glomerular and tubular regions in DOX-treated PAKO mice at Day 9. Moreover, DOX-treated PAKO mice showed more severe glomerulosclerosis and tubular damage and lower podocalyxin expression in the kidneys than DOX-treated control mice at 4 weeks. Furthermore, DOX treatment increased p-p53, an apoptosis marker, and cleaved the caspase-3 levels and induced apoptosis, which was ameliorated by fenofibrate, a PPAR-α activator. Fenofibrate further enhanced AMPK activation and autophagy under fed and fasting conditions. Conclusively, PPAR-α deficiency enhances DOX-induced podocytopathy, glomerulosclerosis, and tubular injury, possibly by reducing autophagic activity in mouse kidneys.

Characteristics of sodium and water retention in rats with nephrotic syndrome induced by puromycin aminonucleoside

INTRODUCTION

Nephrotic syndrome (NS) is characterized by renal sodium and water retention. The mechanisms are not fully elucidated.

METHODS

The NS rat model was established by single intraperitoneal injection of 100 mg/kg puromycin aminonucleoside (PAN). The plasma electrolyte level and urinary sodium excretion were monitored dynamically. The changes of some sodium transporters, including epithelial Na+ channel (ENaC), Na+/H+ exchanger 3 (NHE3), Na+-K+-2Cl- cotransporter 2 (NKCC2) and Na+-Cl- cotransporter (NCC) in renal cortex at different time points and the level of peripheral circulation factors were detected.

RESULTS

The urinary sodium excretion of the model group increased significantly on the first day, then decreased compared with the control group, and there was no significant difference between the model group and the control group on the 12th day. The changes of peripheral circulation factors were not obvious. Some sodium transporters in renal cortex increased in varying degrees, while NKCC2 decreased significantly compared with the control group.

CONCLUSIONS

The occurrence of NS edema may not be related to the angiotensin system. The decrease of urinary sodium excretion is independent of the development of albuminuria. During the 18 days of observation, it can be divided into three stages: sodium retention, sodium compensation, and simple water retention. The mechanism is related to the increased expression of α-ENaC, γ-ENaC, NHE3 and NCC in a certain period of time, the compensatory decrease of NKCC2 expression and the continuous increase of aquaporin 2 (AQP2) expression.

N-(2-hydroxy phenyl) acetamide ameliorate inflammation and doxorubicin-induced nephrotoxicity in rats

Doxorubicin (DOX) is an anthracyclin antibiotic used for the treatment of various cancers. Nephrotoxicity is among the serious side effects of DOX, therefore, DOX-induced nephrotoxic model has been widely used to study nephropathies. The objectives of this study is to investigate the possible anti-inflammatory and nephroprotective effects of salicylic acid derivative, N-(2-hydroxy phenyl) acetamide (NA-2), in a rat model of DOX-induced nephrotoxicity. The in vitro anti-inflammatory potential of NA-2 was manifested by whole blood oxidative burst and nitric oxide (NO) assays with no toxicity on normal human fibroblast (BJ) cells, human embryonic kidney (HEK-293) cells, and normal monkey kidney epithelial (Vero) cells. The in vivo study included five groups: Normal control, DOX (6 mg/kg DOX-i.v.via tail vein), NA-2 treated control-i.p., NA-2/DOX treated-i.p., and prednisolone/DOX treated. After 7 days of DOX administration, rats with urinary protein level of >50 mg/kg/day were selected. Treatment group rats received i.p. doses of NA-2 (10 mg/kg/day) for 3 weeks with weekly monitoring of urinary protein excretion and body weights. mRNA expression of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, and kidney injury molecule (KIM)-1 was analyzed by quantitative polymerase chain reaction (qPCR). Protein expressions were analyzed by immunohistochemistry. NA-2 attenuated DOX-induced changes in serum and urine levels, and improved inflammatory profile of the renal tissue. Histopathological findings revealed protective effects of NA-2 showing lesser lesions. We conclude that NA-2 is able to protect against DOX-induced renal damage functionally, biochemically and histopathologically with corresponding improvement in the kidney inflammatory profile.

Current understanding of the molecular mechanisms of circulating permeability factor in focal segmental glomerulosclerosis

The pathogenetic mechanisms underlying the onset and the post-transplant recurrence of primary focal segmental glomerulosclerosis (FSGS) are complex and remain yet to be fully elucidated. However, a growing body of evidence emphasizes the pivotal role of the immune system in both initiating and perpetuating the disease. Extensive investigations, encompassing both experimental models and patient studies, have implicated T cells, B cells, and complement as crucial actors in the pathogenesis of primary FSGS, with various molecules being proposed as potential "circulating factors" contributing to the disease and its recurrence post kidney-transplantation. In this review, we critically assessed the existing literature to identify essential pathways for a comprehensive characterization of the pathogenesis of FSGS. Recent discoveries have shed further light on the intricate interplay between these mechanisms. We present an overview of the current understanding of the engagement of distinct molecules and immune cells in FSGS pathogenesis while highlighting critical knowledge gaps that require attention. A thorough characterization of these intricate immune mechanisms holds the potential to identify noninvasive biomarkers that can accurately identify patients at high risk of post-transplant recurrence. Such knowledge can pave the way for the development of targeted and personalized therapeutic approaches in the management of FSGS.

Integrated single-cell RNA-seq analysis revealed podocyte injury through activation of the BMP7/AMPK/mTOR mediated autophagy pathway

BACKGROUND

Nephrotic syndrome (NS) is a chronic kidney disease mainly caused by impaired podocytes, ultimately resulting in massive proteinuria or even end-stage renal disease (ESRD).

METHODS

The objective of this study was to explore the potential pathogenesis of NS caused by podocyte injury, and further explore the underlying mechanism through data mining, bioinformatics analysis, and experimental verification. The integrated analyses including Seurat, CellChat, gene ontology (GO), and molecular docking were performed based on the single-cell RNA-seq data (scRNA-seq). The adriamycin (ADR)-induced podocyte injury model in vitro was established to conduct the experimental verification for bioinformatics analysis results through western blot and real-time quantitative PCR (RT-qPCR).

RESULTS

The results of bioinformatics analysis revealed that the bone morphogenetic protein (BMP) signaling pathway was involved in the podocyte-to-podocyte communication, which plays a crucial role in podocyte injury. The expression of BMP7 was significantly increased in ADR-induced podocytes through activating the Adenosine-monophosphate activated-protein kinase/Mammalian target of rapamycin (AMPK/mTOR) mediated autophagy pathway, and these findings were confirmed by in vitro experiments.

CONCLUSION

This study first demonstrated that BMP7 participated in ADR-induced podocyte injury. The BMP7/AMPK/mTOR mediated autophagy pathway may play a crucial role in podocyte injury, which may be the potential therapeutic target for NS patients.

Pharmacological investigation of indole alkaloids from Alstonia scholaris against chronic glomerulonephritis

BACKGROUND

As one of the most commonly used folk medicines in "Dai" ethno-medicine system, Alstonia scholaris (l.) R. Br. has also been used for treat "water related diseases", such as chronic kidney disease. However, few study was reported for it on the intervention of chronic glomerulonephritis (CGN).

PURPOSE

To investigate the effect and potential mechanism of indole alkaloids from A. scholaris leaves in ICR mice with adriamycin nephropathy, as well as providing experimental evidence for the further application.

METHODS

ICR Mice were selected for injections of adriamycin (ADR) to induce the CGN model and administered total alkaloids (TA) and four main alkaloids continuously for 42 and 28 days, respectively. The pharmacological effects were indicated by serum, urine, and renal pathological observations. The targets and pathways of indole alkaloids on CGN intervention were predicted using the network pharmacology approach, and the immortalized mice glomerular podocyte (MPC5) cells model stimulated by ADR was subsequently selected to further verify this by western blotting and RT-qPCR methods.

RESULTS

TA and four major compounds dramatically reduced the levels of urinary protein, serum urea nitrogen (BUN), and creatinine (CRE) in ADR - induced CGN mice, while increasing serum albumin (ALB) and total protein (TP) levels as well as ameliorating kidney damage. Moreover, four alkaloids effected on 33 major target proteins and 153 pathways in the CGN, among which, PI3K-Akt as the main pathway, an important pathway for kidney protection by network pharmacology prediction, and then the four target proteins - HRAS, CDK2, HSP90AA1, and KDR were screened. As a result, Val-and Epi can exert a protective effect on ADR-stimulated MPC5 cells injury at a concentration of 50 μM. Furthermore, the proteins and RNA expression of HRAS, HSP90AA1, and KDR were down-regulated, and CDK2 was up-regulated after the intervention of Val-and Epi, which were supported by Western blotting and RT-qPCR. Additionally, Val-and Epi inhibited ROS production in the MPC5 cells model.

CONCLUSION

This study is the first to confirm the potential therapeutic effect of alkaloids from A. scholaris on CGN. TA with major bioactive components (vallesamine and 19‑epi-scholaricine) could exert protective effects against the ADR-induced CGN by regulating four key proteins: HRAS, CDK2, HSP90AA1, and KDR of the PI3K-Akt pathway.

Therapeutic treatment with phosphodiesterase-4 inhibitors alleviates kidney injury and renal fibrosis by increasing MMP-9 in a doxorubicin-induced nephrotoxicity mouse model

Nephrotic syndrome (NS) is associated with kidney dysfunction and is an important cause of morbidity and mortality in industrialized countries. Here, we evaluated the effects of the phosphodiesterase-4 (PDE-4) inhibitors rolipram and roflumilast on a doxorubicin-induced NS model. Early-stage rolipram treatment preserved glomerular filtration barrier function, as indicated by reduced serum protein and albumin loss and the prevention of hypercholesterolemia. These effects were associated with reduced glomerular and tubular lesions and abrogated renal cell apoptosis. In addition, rolipram treatment reduced inflammation, which was characterized by a decrease in macrophage accumulation and reduced levels of CCL2 and TNF in the kidneys. Rolipram also reduced renal fibrosis, which was associated with decreased α-smooth muscle actin (α-SMA) area and increased metalloproteinase 9 (MMP9) activity in renal tissue. Late-stage rolipram or roflumilast treatment preserved glomerular filtration barrier function, as characterized by reduced serum albumin loss, decreased proteinuria, and the prevention of hypercholesterolemia. Importantly, only roflumilast treatment was associated with a reduction in glomerular and tubular lesions at this time point. In addition, both rolipram and roflumilast reduced renal tissue fibrosis and MMP9 activity in renal tissue.

Nephrotic Syndrome and Renin-angiotensin System: Pathophysiological Role and Therapeutic Potential

Idiopathic Nephrotic Syndrome (INS) is the most frequent etiology of glomerulopathy in pediatric patients and one of the most common causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD) in this population. In this review, we aimed to summarize evidence on the pathophysiological role and therapeutic potential of the Renin-Angiotensin System (RAS) molecules for the control of proteinuria and for delaying the onset of CKD in patients with INS. This is a narrative review in which the databases PubMed, Web of Science, and Sci- ELO were searched for articles about INS and RAS. We selected articles that evaluated the pathophysiological role of RAS and the effects of the alternative RAS axis as a potential therapy for INS. Several studies using rodent models of nephropathies showed that the treatment with activators of the Angiotensin-Converting Enzyme 2 (ACE2) and with Mas receptor agonists reduces proteinuria and improves kidney tissue damage. Another recent paper showed that the reduction of urinary ACE2 levels in children with INS correlates with proteinuria and higher concentrations of inflammatory cytokines, although data with pediatric patients are still limited. The molecules of the alternative RAS axis comprise a wide spectrum, not yet fully explored, of potential pharmacological targets for kidney diseases. The effects of ACE2 activators and receptor Mas agonists show promising results that can be useful for nephropathies including INS.

Integrating network pharmacology approach and experimental validation to reveal the alleviation of Shenkangning capsule on chronic nephritis

ETHNOPHARMACOLOGICAL RELEVANCE

Shenkangning (SKN), a Chinese patent medicine composed by eight Chinese medicinal herbs, is commonly applied to treat chronic glomerulonephritis (CGN) in clinic. However, its mechanism is still not clear now.

AIM OF THE STUDY

This study is designed to evaluate the SKN-provided alleviation on adriamycin (ADR)-induced nephropathy, to reveal its mechanism by integrating network pharmacology analysis and experimental evidences, and to further find the main drug that makes a major contribution to its efficacy.

MATERIALS AND METHODS

ADR was intravenously injected to mice to induce focal segmental glomerulosclerosis (FSGS). Renal histological evaluation was conducted. The level of urinary protein, and serum amounts of creatinine, urea nitrogen (BUN) and albumin were detected. The potential mechanisms were predicted by network pharmacology analysis and further validated by Real-time polymerase chain reaction (RT-PCR), Western-blot and enzyme-linked immunosorbent assay (ELISA).

RESULTS

SKN (1, 10 g/kg) improved ADR-induced nephropathy in mice. Network pharmacology results predicted that inflammation and oxidative stress were crucially involved in the SKN-provided amelioration on nephropathy. SKN reduced the activation of nuclear factor-κB (NF-κB) and the expression of some pro-inflammatory cytokines, and increased the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and the expression of its downstream genes in ADR-induced nephropathy in mice. Furthermore, SKN also restored the reduced expression of both podocin and synaptopodin, which are podocyte-associated proteins. Further results showed that the toxic drug Danfupian (DFP) had no contribution to the SKN-provided alleviation on ADR-induced nephropathy in mice. After integrating the results from evaluating anti-inflammation, anti-oxidant and anti-injury of podocytes in vitro and from comparing the activity of the whole SKN and SKN without Astragali Radix (Huangqi, HQ) in vivo, we found that HQ played a crucial contribution to the SKN-provided amelioration on ADR-induced nephropathy in mice.

CONCLUSION

SKN improved ADR-induced nephropathy through suppressing renal inflammation and oxidative stress injury via abrogating NF-κB activation and activating Nrf2 signaling pathway. HQ played a main contribution to the SKN-provided amelioration on ADR-induced nephropathy.

Experimental Study on the Mechanism of Cinnamaldehyde Ameliorate Proteinuria Induced by Adriamycin

Objective. Cinnamaldehyde (CA) is the main active component of Guizhi (Cinnamomi ramulus) to ameliorate adriamycin- (ADR-) induced proteinuria in rats. However, the underlying mechanism of CA against proteinuria remains unclear. The aim of this study was to investigate the action mechanisms of CA to treat proteinuria. Methods. 13 rats were randomly selected from 78 SD rats as control group, and the other rats were injected with ADR (3 mg/kg/time) twice through tail vein on day 1 and day 8 for modeling. After modeling, the rats were randomly divided into 5 groups as follows: ADR group, ADR+CA low-dose group, ADR+CA middle-dose group, ADR+CA high-dose group and Benazepril group with 13 rats in each group. The urine of SD rats was collected for 24 h, urine protein, creatinine and urea nitrogen were detected, renal index was calculated, and HE staining and western blot were performed. Results. The 24 h urine volume and urine protein, renal function, and renal histopathology got worse significantly in the ADR group. To western blot, CA downregulated the protein expression of ACE and Ang-2 and upregulated the protein expression of ACE2 in RAS signaling pathway. Conclusion. The underlying action mechanism of CA to treat NS might mainly be achieved by regulating RAS signaling pathway.

Effect of Nephropathy Prescription I on the Expression of Angptl3 and Podocyte-Associated Protein in Mice with Adriamycin-Induced Nephropathy

Objective

This study aimed to investigate the effects of Nephropathy Prescription I on the expression of angptl3, nephrin, and podocin, in addition to its protective effects on podocytes in mice with adriamycin-induced nephropathy.

Methods

BALB/c mice were randomly divided into the control (C), adriamycin (Model or M), adriamycin + Nephropathy Prescription I (M + Z), adriamycin + prednisone acetate (M + S), and adriamycin + Nephropathy Prescription I + prednisone acetate groups (M + Z + S). All mice except those in the C group in the experimental groups were treated with a single tail vein injection of adriamycin. The urine albumin-creatinine ratio was measured before model establishment and on the 7th day, 14th day, 21st day, and 28th day of doxorubicin injection. All the mice were sacrificed on the 29th day. Blood samples were collected to observe biochemical indicators in the serum. The morphological structure and podocyte ultrastructure in the kidney were observed using light and electron microscopy, respectively. The expression of angptl3, nephrin, and podocin at the mRNA and protein levels was detected by real-time PCR and western blotting, respectively.

Results

Following modeling with adriamycin, albuminuria was observed in urine samples in the first week, and the urinary protein/creatinine ratio increased maximally in the fourth week in the M group (P < 0.05). In contrast, the urinary protein/creatinine ratio significantly decreased (P < 0.05) in the third week in the (M + Z) group compared to that in the M group. Similarly, this ratio decreased in the (M + S) and (M + Z + S) groups compared to that in the M group throughout the experiment. Compared with the C group, serum albumin content and the expression of nephrin and podocin decreased (P < 0.05), whereas blood lipid level and the expression of angptl3 increased (P < 0.05) in the M group. Glomerular foot process fusion was observed in this group using electron microscopy. In all the intervention groups, serum albumin content and the expression of nephrin and podocin increased (P < 0.05), whereas blood lipid level and the expression of angptl3 decreased (P < 0.05), with alleviated glomerular foot process injury observed particularly in the (M + Z + S) group.

Conclusion

The Nephropathy Prescription I can alleviate albuminuria, increase serum albumin levels, lower blood lipid levels, and reduce the fusion of foot processes of podocytes in mice with adriamycin-induced nephropathy. The protective effects of the Nephropathy Prescription I may function by reducing Angptl3 expression and increasing nephrin and podocin expression.

Osteocrin ameliorates adriamycin nephropathy via p38 mitogen-activated protein kinase inhibition

Natriuretic peptides exert multiple effects by binding to natriuretic peptide receptors (NPRs). Osteocrin (OSTN) binds with high affinity to NPR-C, a clearance receptor for natriuretic peptides, and inhibits degradation of natriuretic peptides and consequently enhances guanylyl cyclase-A (GC-A/NPR1) signaling. However, the roles of OSTN in the kidney have not been well clarified. Adriamycin (ADR) nephropathy in wild-type mice showed albuminuria, glomerular basement membrane changes, increased podocyte injuries, infiltration of macrophages, and p38 mitogen-activated protein kinase (MAPK) activation. All these phenotypes were improved in OSTN- transgenic (Tg) mice and NPR3 knockout (KO) mice, with no further improvement in OSTN-Tg/NPR3 KO double mutant mice, indicating that OSTN works through NPR3. On the contrary, OSTN KO mice increased urinary albumin levels, and pharmacological blockade of p38 MAPK in OSTN KO mice ameliorated ADR nephropathy. In vitro, combination treatment with ANP and OSTN, or FR167653, p38 MAPK inhibitor, reduced Ccl2 and Des mRNA expression in murine podocytes (MPC5). OSTN increased intracellular cyclic guanosine monophosphate (cGMP) in MPC5 through GC-A. We have elucidated that circulating OSTN improves ADR nephropathy by enhancing GC-A signaling and consequently suppressing p38 MAPK activation. These results suggest that OSTN could be a promising therapeutic agent for podocyte injury.

Ultra-Performance Liquid Chromatography-Q-Exactive Orbitrap-Mass Spectrometry Analysis for Metabolic Communication between Heart and Kidney in Adriamycin-Induced Nephropathy Rats

BACKGROUND/AIMS

Although the adriamycin-induced nephropathy model is frequently employed in the study of nephrotic syndrome and focal segmental glomerulosclerosis, the accompanying myocardial damage has always been a cause for concern. Therefore, there is a great need to study cardiorenal communication in this model.

METHODS

An adriamycin-induced nephropathy model was established via tail vein injection. The levels of the biochemical indicators serum albumin, serum globulin, serum total protein, serum cholesterol, serum creatinine (SCr), urinary protein, and urinary creatinine (UCr) were measured, and histopathological changes in the heart and kidneys were assessed using hematoxylin-eosin staining. Metabolomic changes in the heart, blood, and kidneys were analyzed using the metabolomics method based on ultra-performance liquid chromatography Q-Exactive Orbitrap mass spectrometry.

RESULTS

Compared with the control group, the model group showed significant decreases in serum protein and total protein levels, albumin/globulin ratio, and creatinine clearance rate as well as significant increases in serum cholesterol, SCr, urinary protein, and UCr levels. Significant pathological changes were observed in the renal pathology sections in the model group, including diffusely merged glomerular epithelial cells, inflammatory infiltration, and vacuolated glomerular cells. Additionally, thickened myocardial fibers, swollen nuclei, inflammatory infiltration, and partial myocardial necrosis could be seen in the cardiac pathology sections in the model group. Based on multivariate statistical analysis, a total of 20 differential metabolites associated with 15 metabolic pathways were identified in the heart, 7 differential metabolites with 7 metabolic pathways were identified in the blood, and 16 differential metabolites with 21 metabolic pathways were identified in the kidney. Moreover, 6 common metabolic pathways shared by the heart and kidney were identified: arginine and proline metabolism; arginine biosynthesis; glutathione metabolism; alanine, aspartate, and glutamate metabolism; beta-alanine metabolism; and histidine metabolism. Among these metabolic pathways, alanine, aspartate, and glutamate metabolism was shared by the heart, blood, and kidney. Succinic acid was found to be the key regulatory metabolite in cardiorenal metabolic communication.

CONCLUSION

Six metabolic pathways were found to be involved in cardiorenal metabolic communication in an adriamycin-induced nephropathy model, in which alanine, aspartate, and glutamate metabolism may be the metabolic link between the heart and kidney in the development and maintenance of oxidative stress and inflammation. Succinic acid may serve as a key regulatory metabolic switch or marker of cardiac and renal co-injury, as shown in an adriamycin-induced nephropathy model.

Imperatae rhizoma-Hedyotis diffusa Willd. herbal pair alleviates nephrotic syndrome by integrating anti-inflammatory and hypolipidaemic effects

BACKGROUND

Nephrotic syndrome (NS) is a common nephropathy with a complex and diverse aetiology. Both Imperatae rhizoma and Hedyotis diffusa Willd. are herbs that are widely used as medicine and functional food. In traditional Chinese medicine theory, they are used as an herbal pair (HP) to treat inflammation-related diseases in the clinic, especially disorders of the kidney.

PURPOSE

This study aimed to investigate the anti-inflammatory and hypolipidaemic effects of HP in an NS rat model and provide scientific data for its clinical application.

METHODS

An NS model was established by two-dose injection of Sprague-Dawley rats with adriamycin. Seven groups, including the sham, model, HP treatment (0.25, 0.5 and 1.0 g/kg/d), prednisone (positive control, 5 mg/kg/d), and atorvastatin (positive control, 4 mg/kg/d) groups, were tested. The biochemical indexes of renal function and inflammatory cytokines were determined by ELISA kits and/or qPCR assays, and the crucial protein involved in the signalling pathway were subsequently tested by qPCR and/or Western blotting. Based on specific compounds identified by LC-Q-TOF-MS, network pharmacological study was carried out.

RESULTS

The levels of BUN, Scr, Upro, UA, Alb, TC, TG, and LDL-C were significantly elevated in model rats. HP treatment for four weeks improved the renal function and the dyslipidaemia by decreasing the levels of all parameters, except BUN and Scr. HP treatment (0.5 and 1.0 g/kg/d) upregulated the expression of PPARγ, CYP7b1, and LDLR in the liver, while it down-regulated PCSK9, showing a regulatory effect on lipid metabolism disorder. The levels of TNF-α and IL-1β in the plasma and the mRNA expression of TNF-α, IL-1β, MCP-1, and TGF-β1 in the kidney were decreased in HP groups, revealing its anti-inflammatory effect in NS rats. The HP exerted an alleviation effect on the inflammatory response through the NF-κB pathway by inhibiting the mRNA and protein expression of p50 and p65. There were 34 compounds identified or tentatively characterized in HP. In the network pharmacological study, PPARG(PPARγ), PCSK9, RELA(p65), and NF-κB1(p50) were the top 20 targets for HP, supporting the animal experimental results.

CONCLUSION

HP exhibited protective effects on NS rats. These effects might be closely related to the inhibition of NF-κB and PCSK9-LDLR and activation of the PPARγ-CYP7B1 signalling pathways.

Adriamycin does not damage podocytes of zebrafish larvae

Podocytes are highly specialized epithelial cells that are essential for an intact glomerular filtration barrier in the kidney. Several glomerular diseases like focal segmental glomerulosclerosis (FSGS) are initially due to podocyte injury and loss. Since causative treatments for FSGS are not available until today, drug screening is of great relevance. In order to test a high number of drugs, FSGS needs to be reliably induced in a suitable animal model. The zebrafish larva is an ideal model for kidney research due to the vast amount of offsprings, the rapid development of a simple kidney and a remarkable homology to the mammalian glomerulus. Zebrafish larvae possess a size-selective glomerular filtration barrier at 4 days post fertilization including podocytes with interdigitating foot processes that are connected by a slit membrane. Adriamycin is an anthracycline which is often used in mice and rats to induce a FSGS-like phenotype. In this study, we aimed to induce a similar phenotype to zebrafish larvae by adding adriamycin to the tank water in different concentrations. Surprisingly, zebrafish larvae did not develop glomerular injury and displayed an intact filtration barrier after treatment with adriamycin. This was shown by (immuno-) histology, our filtration assay, in vivo imaging by 2-photon microcopy, RT-(q)PCR as well as transmission electron microscopy. To summarize, adriamycin is unable to induce a podocyte-related damage in zebrafish larvae and therefore major effort must be made to establish FSGS in zebrafish larvae to identify effective drugs by screenings.

Olive leaf extract attenuates adriamycin-induced focal segmental glomerulosclerosis in spontaneously hypertensive rats via suppression of oxidative stress, hyperlipidemia, and fibrosis

Olive (Olea europaea L.) leaf extract (OLE) possesses powerful antioxidant, antihyperlipidemic, and anti-inflammatory properties. The aim was to investigated the effects of OLE on the hyperlipidemia, antioxidant defense, heme oxygenase/biliverdin reductase (HO/BVR) pathway, inflammation, and fibrosis in spontaneously hypertensive rats with focal segmental glomerulosclerosis (FSGS, a progressive form of chronic kidney disease) induced by adriamycin (2 mg/kg, i.v., twice in a 21-day period). Daily treatment of OLE (80 mg/kg, p.o.) for 6 weeks suppressed protein oxidation and lipid peroxidation (p < .01 and p < .001, respectively), significantly increased antioxidant enzymes activities and normalized antioxidant capacity, leading to the improvement of antioxidant defense independently of the HO/BVR pathway. Furthermore, the values of triglycerides (p < .01), total, and low-density lipoprotein cholesterol (p < .05, both) were improved by OLE. OLE strongly prevented glomerulosclerosis, interstitial inflammation, and fibrosis (renal injury score, FSGS: 8 ± 0.45 vs. FSGS+OLE: 4.20 ± 1.07; p < .01), as evidenced by normalized fibronectin content (p < .001), suppressed interstitial inflammatory cells infiltration and collagen deposition, without changing cytokines expressions. OLE decreased blood pressure with a tendency to reduce urine albumin loss. These data suggest that OLE may be effective in slowing down the progression of FSGS.

Curcumin, as a pleiotropic agent, improves doxorubicin-induced nephrotic syndrome in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Curcumin, a phenolic compound extracted from the rhizome of turmeric (Curcuma longa L.), has been reported to have broad biological functions including potent antioxidant and renoprotective effects. It has been reported that Curcumin has a certain protective effect on the kidney. However, its mechanism of action needs further study.

AIM OF THE STUDY

The present research aims at investigating the therapeutic effects and its underlying mechanism of curcumin on NS.

MATERIALS AND METHODS

The conditionally immortalized mouse podocyte cell line was utilized to evaluate the podocyte-protective effect of curcumin and its effects on NF-κB pathway and Nrf2/ARE pathway in podocyte in vitro. Furthermore, the DOX-induced NS rats were utilized to investigate the therapeutic effects and its underlying mechanism of curcumin against NS in vivo.

RESULTS

The consequences of this study revealed that curcumin activated Nrf2, inhibited NF-κB pathway and up-regulated podocin in DOX-induced podocyte. Further research results showed that curcumin can considerably alleviate proteinuria and improve hypoalbuminemia in NS rats, and lower blood lipid levels to alleviate hyperlipidemia in NS rats, indicating that curcumin has significant therapeutic effects on rat NS. Further observation by electron microscopy and detection showed that curcumin can improve renal function and podocyte injury, which may be related to the repairment of mRNA expression and podocin protein. Interestingly, the results of the blood rheology test showed that curcumin can effectively reduce whole blood viscosity (WBV) and plasma viscosity (PV), and reduce hematocrit (Hct). In addition, the oxidative stress state of kidney in NS rats was considerably reversed by curcumin, which may be achieved by activating Nrf2 and increasing the expression of antioxidant enzymes HO-1, NQO-1. We also found that NF-κB pathway is activated in the kidney of NS rats, and curcumin can inhibit the activation of NF-κB by down-regulating the expression of NF-κB p65, reducing the level of p-IκBα and up-regulating the expression of IκBα.

CONCLUSION

These findings suggest that curcumin, as a multifunctional agent, exerts a protective effect on DOX-induced nephrotic syndrome in rats, which provides a pharmacological basis for the further development of curcumin and also provides a basis for the advantages of multi-targeted drugs in the processing of NS.

Evaluation of Injury Degree of Adriamycin-Induced Nephropathy in Rats Based on Serum Metabolomics Combined with Proline Marker

Nephrotic syndrome (NS) is one of the leading causes of end-stage renal failure. Unfortunately, reliable surrogate markers for early diagnosing and monitoring the entire progression of NS are as yet absent. A method using UPLC-Q exactive HR-MS was established for the serum metabolomic study of adriamycin-induced nephropathy in rats. Two rat nephropathy models induced by adriamycin were adopted to reflect different degrees of renal damage of early and advanced stages. Then two MPC5 cell models were used to verify the role of proline in the progression of kidney injury. The results showed that seven metabolites such as 14S-HDHA, DPA, and DHA were associated with early renal injury, while 12 metabolites such as tryptophan, linoleyl carnitine, and LysoPC (18:3) reflected the advanced renal disease. At the same time, metabolites including LPE (22:6), LysoPC (22:5), and proline that changed during the whole process of NS were defined as progressive markers. Pathway analysis results showed that fatty acid metabolism, glycerophospholipid metabolism, and amino acids metabolism participated in the occurrence and development of NS. In addition, the change trend of intracellular proline content was consistent with that in serum, and the results were further supported by the detection of the crucial gene PYCRL. This study provides an important basis for searching for diagnostic markers of NS and also provides a methodological reference for early diagnosing and monitoring the pathogenesis of other progressive diseases.

Performance of severity parameters to detect chemotherapy-induced pain and distress in mice

According to European Union directive 2010/63/EU a severity classification of experimental procedures performed on laboratory animals is mandatory. This includes a prospective evaluation of all interventions performed within the experiment, as well as an assessment of the actual burden of each animal during the experiment. In this regard, the evaluation and scoring of defined criteria regarding the health state of animals could help to early identify deteriorations in animal health and facilitate the application of humane endpoints. This article discusses the applicability of an adapted score sheet in BALB/cAnNRj mice receiving either cisplatin, doxorubicin or busulfan, three chemotherapeutic agents with different toxicological profiles and longitudinal non-invasive molecular imaging. The health state was investigated by score sheets documenting general state, body weight, spontaneous behaviour and treatment specific parameters (e.g. anaemia, neurotoxicity, persistent diarrhoea). Although blood and serum analyses clearly indicated various organ damage, most scoring parameters except for body weight did not report on the deceasing animal health state. Thus, there is need for more sensitive observational parameters to judge the animal's health state and welfare.

Renoprotective Effect of Plantago major Against Proteinuria and Apoptosis Induced by Adriamycin in Rat

Objective

Adriamycin (ADR) is an important anti-cancer drug which can cause renal toxicity. Given the known anti-inflammatory and antioxidant effects of Plantago major (P. major), the aim of this study was to determine the effects of hydroalcoholic extract of P. major on ADR- induced nephropathy in rats.

Methods

Fifty male Wistar albino rats were randomly divided into 5 groups including: control, ADR (5 mg/kg), ADR + P. major (600 and 1200 mg/kg) and P. major (1200 mg/kg). The animals were treated with P. major extract for 5 consecutive weeks and ADR was intravenously injected on the 7th day of the study. Urine and serum samples were collected on days 0, 14, 21, 28, and 35 for the measurement of serum cholesterol and albumin levels and urine protein excretion rate. At the end of the study, the left kidneys were removed for apoptosis assessment.

Results

Administration of ADR significantly decreased serum albumin level and increased serum cholesterol and urine protein excretion rate as well as, apoptotic cell numbers compared to the control group (P < 0.001) while had no effect on glomerular filtration rate (P > 0.05). Treatment with P. major, in both 600 and 1200 mg/kg doses, increased serum albumin level and decreased serum cholesterol concentration, urine protein excretion rate and as well as the number of apoptotic cell compared to the ADR group (P < 0.001).

Conclusion

Our results showed that the P. major extract effectively protects against ADR- induced nephropathy by reducing kidney apoptosis and improving renal functioning in rats.

Retrobulbar Sinus Injection of Doxorubicin is More Efficient Than Lateral Tail Vein Injection at Inducing Experimental Nephrotic Syndrome in Mice: A Pilot Study

Doxorubicin-induced nephropathy in mice is a model for studying experimental nephrotic syndrome. It corresponds to puromycin aminonucleoside nephrosis in rats. In this model, susceptible 129 S1/SvImJ mice are administered a rapid intravenous injection that can be accomplished via either the lateral tail vein or the retrobulbar sinus. Because doxorubicin is a highly toxic substance, extravasation must be avoided during the administration of the intravenous injection to prevent the development of large necrotizing lesions and exacerbation of the animals’ stress. In the present study, we compared the safety and stress of these two injection routes by using histopathological analyses of the animals’ orbital cavities or tails, respectively. The injection of 14.5 µg/g body weight doxorubicin into the mice’s lateral tail veins (n = 9) or retrobulbar sinuses (n = 19) caused no clinically detectable stress or impairment. Histopathologies of the specimens five days after doxorubicin injection revealed inflammatory lesions at the injection sites in both groups. In the orbital sinus specimens from the retrobulbar-injected group, fibrosis was evident 25 days after injection. Moreover, while all of the retrobulbar-injected mice (100%) developed nephrotic syndrome, tail vein-injected mice had a significantly lower response rate (66%, p = 0.047, Fisher’s exact test) and exhibited only attenuated features of nephrotic syndrome. It was therefore concluded that doxorubicin administration via either lateral tail vein or retrobulbar sinus injections led to a similar induction of histopathological changes with no effects on the clinical well-being of the mice. However, retrobulbar sinus injections were more efficient for inducing experimental nephrotic syndrome.

A scrutiny of circulating microRNA biomarkers for drug-induced tubular and glomerular injury in rats

Drug-induced acute kidney injury (AKI) is a frequent cause of adverse drug reaction. Serum creatinine (CRE) and blood urea nitrogen (BUN) are widely used as standard biomarkers for kidney injury; however, the sensitivity and specificity are considered to be low. In recent years, circulating microRNA (miRNAs) have been attracting considerable attention as novel biomarkers for organ injury, but there are currently no established miRNA biomarkers for drug-induced AKI. The present study aimed to identify plasma miRNAs that may enable early and specific detection of drug-induced tubular and glomerular injury through next-generation sequencing analysis. Six-week old male Sprague-Dawley (SD) rats were intravenously administered cisplatin (CSP, 6 mg/kg) and gentamicin (GEN, 120 mg/kg) to induce tubular injury. To create glomerular injury models, puromycin (PUR, 120 mg/kg) and doxorubicin (DOX, 7.5 mg/kg) were intravenously administered, and these models were always accompanied by tubular damage. Small RNA-sequencing was performed to analyze time-dependent changes in the plasma miRNA profiles. The cluster analyses showed that there were distinct plasma miRNA profiles according to the types of injury, and the changes reflected the progress of renal damages. In the differential analysis, miR-3473 was specifically up-regulated in the glomerular injury models. miR-143-3p and miR-122-5p were commonly down-regulated in all models, and the changes were earlier than the traditional biomarkers, such as plasma CRE and BUN. These data indicated that changes in the specific miRNAs in plasma may enable the early and sensitive detection of tubular and glomerular injuries. The present study suggests the potential utility of plasma miRNAs in the early and type-specific detection of drug-induced AKI.

An impaired hepatic clock system effects lipid metabolism in rats with nephropathy

Hyperlipidemia is a key clinical feature in patients with nephrotic syndrome (NS) that is associated with the incidence of cardiovascular events. Recent studies have suggested that the disorders of triglycerides, gluconeogenesis and liver glucose metabolism are associated with the abnormal transcription of clock genes. However, changes to the circadian rhythm of blood lipids in NS require further exploration, and the effects of NS on the hepatic clock system remain to be elucidated. In the present study, the impaired diurnal rhythm of the hepatic core clock genes (BMAL1, CLOCK, CRY1, CRY2, PER1 and PER2) significantly induced circadian rhythm abnormalities in liver-specific clock-controlled genes (LXR, CYP7A1, SREBP-1, ABCA1, DEC1 and DEC2; all P<0.05), which were significantly associated with the abnormal diurnal rhythms of triglyceride, total cholesterol, aspartate aminotransferase and alanine aminotransferase (all P<0.05) in rats with Adriamycin-induced nephropathy. Furthermore, a protein-protein interaction network was identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses based on the human database was conducted to obtain signaling pathway and correlation prediction analyses of overall human clock and clock-controlled gene correlations. Strong correlations of the aforementioned clock genes were detected (avg. local clustering coefficient, 0.849) which suggested significant enrichment in circadian rhythm signaling. The present results indicated that damage to hepatic clock systems may impact blood lipid circadian rhythm disorders in NS, and offer a starting point for understanding the crosstalk between peripheral organs and peripheral clock systems.

The expressional disorder of the renal RAS mediates nephrotic syndrome of male rat offspring induced by prenatal ethanol exposure

This study aimed to prove that prenatal ethanol exposure (PEE) can induce nephrotic syndrome in male rat offspring and to explore the underlying intrauterine programming mechanisms. Pregnant Wistar rats were intragastrically administered ethanol (4 g/kg d) from gestational day (GD) 9 to GD 20, and the male fetuses were delivered by cesarean section at GD20 and the male adult offspring were euthanized at postnatal week (PW) 24. In vitro, the primary metanephric mesenchyme cells were treated with ethanol at concentrations of 15-60 mM. The results indicated that the kidneys of adult offspring in the PEE group exhibited glomerulosclerosis as well as interstitial fibrosis. The levels of serum creatinine and urine protein were elevated; the serum total cholesterol level was increased and the serum albumin concentration was reduced. In the fetal kidney, developmental retardation was presented in the PEE group via pathological examinations, accompanied by the expressional inhibition of the glial-cell-line-derived neurotrophic factor/c-ret tyrosine kinase receptor (GDNF/c-ret) signaling pathway. Although serum angiotensin II (Ang II) level and the gene expression of renal angiotensin-converting enzyme (ACE) were increased in the PEE group, the expression of renal angiotensin II type 2 receptor (AT₂R) was significantly inhibited, accompanied by a reduction in the H3K27ac level on the AT₂R gene promoter. In the non-classical renin-angiotensin system (RAS), the expression of renal angiotensin converting enzyme 2 (ACE2) and Mas receptor (MasR) were inhibited in the PEE group. The above changes of the classical and non-classical RAS all sustained from utero to adulthood. In vitro, ethanol elevated the gene expression of ACE and angiotensin II type 1a receptor (AT_1aR) whereas it reduced the expression of AT₂R, ACE2, and MasR, accompanied by a reduction in the H3K27ac level on AT₂R gene promoter. Taken together, these results suggested that PEE can induce fetal kidney developmental retardation and adult nephrotic syndrome, and direct regulation of ethanol to the renal RAS was involved in the mechanism of nephrotic syndrome induced by PEE.

A novel in vivo method to quantify slit diaphragm protein abundance in murine proteinuric kidney disease

Injury of the glomerular filter causes proteinuria by disrupting the sensitive interplay of the glomerular protein network. To date, studies of the expression and trafficking of glomerular proteins have been mostly limited to in vitro or histologic studies. Here, we report a novel in vivo biotinylation assay that allows the quantification of surface expression of glomerular proteins in mice. Kidneys were perfused in situ with biotin before harvest. Afterwards glomeruli were isolated and lyzed. The protein of interest was separated by immunoprecipitation and the amount of surface-expressed protein was quantified by Western blot analysis with streptavidin staining. As proof-of-concept, we examined the presence of nephrin in the slit diaphragm in two well-established murine models of proteinuric kidney disease: nephrotoxic nephritis and adriamycin nephropathy. In proteinuric animals, significantly less nephrin was detected in the slit diaphragm. When proteinuria decreased once again during the course of disease, the amount of surface nephrin returned to the baseline. Our present results suggest that our assay is a valuable tool to study the glomerular filter in proteinuric kidney diseases. Note that the assay is not limited to proteins expressed in the slit diaphragm, and all surface proteins that are accessible to biotin perfusion and immunoprecipitation qualify for this analysis.

Matrine ameliorates adriamycin-induced nephropathy in rats by enhancing renal function and modulating Th17/Treg balance

Matrine (MAT) is an active alkaloid extracted from Radix Sophora flavescens. The present study was to investigate whether MAT could effectively treat Adriamycin-induced nephropathy (AIN). AIN was induced in rats using a single injection of Adriamycin (ADR). Renal interleukin-6 (IL-6), IL-10, IL-17 and transforming growth factor-β (TGF-β) levels, and the expression of forkhead box protein 3 (Foxp3) and retinoid-related orphan nuclear receptor γt (Rorγt) was measured. AIN rats developed severe albuminuria, hypoalbuminaemia, hyperlipidaemia and podocyte injury. Daily administration of MAT (100mg/kg or 200mg/kg) significantly prevented ADR-induced podocyte injury, decreased AIN symptoms and improved renal pathology manifestations. Of note, treatment with MAT (100mg/kg) plus prednisone (Pre, 5mg/kg) had equivalent efficacy to that of Pre alone (10mg/kg). Additional findings showed that ADR triggered a disordered cytokine network and abnormal expression of Foxp3 and Rorγt in rats, as reflected by increased levels of IL-6, IL-10, TGF-β, Rorγt and decreased levels of IL-10 and Foxp3. Interestingly, MAT weakened the disordered cytokine network and normalized the expression of Foxp3 and Rorγt. In addition, a significant negative correlation was observed between the values of Foxp3/Rorγt and renal pathology scores. Finally, MAT normalized regulatory T cells (Treg)/ T-helper17 cells (Th17) ratio in peripheral blood mononuclear cells of AIN rats. These data indicate MAT prevents AIN through the modification of disordered plasma lipids and recovery of renal function, and this bioactivity is at least partly attributed to the suppression of renal inflammation and the regulation of the Treg/Th17 imbalance.

Treatment with irbesatan may improve slit diaphragm alterations in rats with adriamycin-induced nephropathy

Objective:

The study aimed to evaluate the effects of oral administration of irbesartan in adriamycin-induced nephropathy considering laboratory changes, kidney histology, and expression of proteins related to slit diaphragm and cytoskeleton of the podocyte.

Methods:

The animals were divided into control, model, methylprednisolone (MP), and irbesartan groups. The 24-hour urinary protein and biochemical indicators were determined, and renal pathological changes were observed. The mRNA and protein expression of nephrin, podocin, CD2-associated protein (CD2AP), and desmin in the kidney tissue were analyzed.

Results:

The urinary protein excretion levels in the MP and irbesartan groups were lower than those in the model group (p<0.01). Electron microscopy showed that fusion of the glomerular foot processes of the rats in the irbesartan group was significantly reduced. The mRNA and protein expression levels of nephrin and podocin in the renal tissue in the MP and irbesartan groups were up-regulated compared with the model group (p<0.05), whereas the mRNA and protein expression levels of CD2AP and desmin were significantly down-regulated (p<0.01).

Conclusions:

For rats with adriamycin-induced nephropathy, irbesartan could significantly reduce proteinuria. As a possible mechanism, irbesartan may improve the slit diaphragm protein of the glomerular podocyte and stabilize the cytoskeleton of the podocyte.

The Alzheimer's disease risk factor CD2AP maintains blood-brain barrier integrity

CD2-associated protein (CD2AP) is a leading genetic risk factor for Alzheimer's disease, but little is known about the function of CD2AP in the brain. We studied CD2AP(-/-) mice to address this question. Because CD2AP(-/-) mice normally die by 6 weeks from nephrotic syndrome, we used mice that also express a CD2AP transgene in the kidney, but not brain, to attenuate this phenotype. CD2AP-deficient mice had no behavioral abnormalities except for mild motor and anxiety deficits in a subset of CD2AP(-/-) mice exhibiting severe nephrotic syndrome, associated with systemic illness. Pentylenetetrazol (PTZ)-induced seizures occurred with shorter latency in CD2AP(-/-) mice, but characteristics of these seizures on electroencephalography were not altered. As CD2AP is expressed in brain-adjacent endothelial cells, we hypothesized that the shorter latency to seizures without detectably different seizure characteristics may be due to increased penetration of PTZ related to compromised blood-brain barrier integrity. Using sodium fluorescein extravasation, we found that CD2AP(-/-) mice had reduced blood-brain barrier integrity. Neither seizure severity nor blood-brain barrier integrity was correlated with nephrotic syndrome, indicating that these effects are dissociable from the systemic illness associated with CD2AP deficiency. Confirming this dissociation, wild-type mice with induced nephrotic syndrome maintained an intact blood-brain barrier. Taken together, our results support a role of CD2AP in mediating blood-brain barrier integrity and suggest that cerebrovascular roles of CD2AP could contribute to its effects on Alzheimer's disease risk.

Increased Migratory and Activation Cell Markers of Peripheral Blood Lymphocytes in an Experimental Model of Nephrotic Syndrome

The present study aimed to evaluate the expression of CD80 and CD18 in subpopulations of peripheral blood leukocytes and oxidative kidney damage in rats with nephrotic syndrome (NS) induced by doxorubicin (Dox) in comparison to control animals at different time points. Male adult Wistar rats were submitted to 24-hour urine and blood collection for biochemical and immunological analysis at 7, 14, 21, and 28 days after Dox injection. After euthanasia, the kidneys were removed for histological analysis and the evaluation of oxidative stress. The phenotypic characterization of leukocytes was performed using flow cytometry. Dox-injected animals exhibited increased CD18 expression in cytotoxic T lymphocytes, NK cells, and monocytes and high CD80 expression in monocytes. Kidney oxidative damage was positively correlated with CD80 expression in monocytes and serum levels of creatinine. These results suggest that phagocytic and cytotoxic cells are preferentially recruited to the tissue injury site, which may contribute to kidney dysfunction in this animal model of NS. The blockade of integrin and costimulatory molecules may provide new therapeutic opportunities for NS.