Inhibition of RAC attenuates Adriamycin-induced podocyte injury

Minimal Change Disease (MCD), which is associated with podocyte injury, is the leading cause of nephrotic syndrome in children. A considerable number of patients experience relapses and require prolonged use of prednisone and immunosuppressants. Multi-drug resistance and frequent relapses can lead to disease progression to focal and segmental glomerulosclerosis (FSGS). To identify potential targets for therapy of podocyte injury, we examined microarray data of mRNAs in glomerular samples from both MCD patients and healthy donors, obtained from the GEO database. Differentially expressed genes (DEGs) were used to construct the protein-protein interactions (PPI) network through the application of the search tool for the retrieval of interacting genes (STRING) tool. The most connected genes in the network were ranked using cytoHubba. 16 hub genes were selected and validated by qRT-PCR. RAC2 was identified as a potential therapeutic target for further investigation. By downregulating RAC2, Adriamycin (ADR)-induced human podocytes (HPCs) injury was attenuated. EHT-1864, a small molecule inhibitor that targets the RAC (RAC1, RAC2, RAC3) family, proved to be more effective than RAC2 silencing in reducing HPCs injury. In conclusion, our research suggests that EHT-1864 may be a promising new molecular drug candidate for patients with MCD and FSGS.

Dexamethasone promotes renal fibrosis by upregulating ILT4 expression in myeloid-derived suppressor cells

Studies have shown that adoptive transfer of myeloid-derived suppressor cells (MDSCs) can alleviate various inflammatory diseases, including glomerulonephritis, but the long-term effects of the transferred MDSCs are still unclear. In addition, although glucocorticoids exert immunosuppressive effects on inflammatory diseases by inducing the expansion of MDSCs, the impact of glucocorticoids on the immunosuppressive function of MDSCs and their molecular mechanisms are unclear. In this study, we found that adoptive transfer of MDSCs to doxorubicin-induced focal segmental glomerulosclerosis (FSGS) mice for eight consecutive weeks led to an increase in serum creatinine and proteinuria and aggravation of renal interstitial fibrosis. Similarly, 8 weeks of high-dose dexamethasone administration exacerbated renal interstitial injury and interstitial fibrosis in doxorubicin-induced mice, manifested as an increase in serum creatinine and proteinuria, collagen deposition and α-SMA expression. On this basis, we found that dexamethasone could enhance MDSC expression and secretion of the fibrosis-related cytokines TGF-β and IL-10. Mechanistically, we revealed that dexamethasone promotes the expression of immunoglobulin-like transcription factor 4 (ILT4), which enhances the T-cell inhibitory function of MDSCs and promotes the activation of STAT6, thereby strengthening the expression and secretion of TGF-β and IL-10. Knocking down ILT4 alleviated renal fibrosis caused by adoptive transfer of MDSCs. Therefore, our findings demonstrate that the role and mechanism of dexamethasone mediate the expression and secretion of TGF-β and IL-10 in MDSCs by promoting the expression of ILT4, thereby leading to renal fibrosis.

Drug-induced glomerular diseases

Drug-induced kidney diseases represent a wide range of diseases that are responsible for a significant proportion of all acute kidney injuries and chronic kidney diseases. In the present review, we focused on drug-induced glomerular diseases, more precisely podocytopathies - minimal change diseases (MCD), focal segmental glomerulosclerosis (FSGS) - and membranous nephropathies (MN), from a physiological and a pharmacological point of view. The glomerular filtration barrier is composed of podocytes that form foot processes tightly connected and directly in contact with the basal membrane and surrounding capillaries. The common clinical feature of these diseases is represented by the loss of the ability of the filtration barrier to retain large proteins, leading to massive proteinuria and nephrotic syndrome. Drugs such as non-steroidal anti-inflammatory drugs (NSAIDs), D-penicillamine, tiopronin, trace elements, bisphosphonate, and interferons have been historically associated with the occurrence of MCD, FSGS, and MN. In the last ten years, the development of new anti-cancer agents, including tyrosine kinase inhibitors and immune checkpoint inhibitors, and research into their renal adverse effects highlighted these issues and have improved our comprehension of these diseases.

Btg2 Promotes Focal Segmental Glomerulosclerosis via Smad3-Dependent Podocyte-Mesenchymal Transition

Podocyte injury plays a critical role in the progression of focal segmental glomerulosclerosis (FSGS). Here, it is reported that B-cell translocation gene 2 (Btg2) promotes Adriamycin (ADR)-induced FSGS via Smad3-dependent podocyte-mesenchymal transition. It is found that in FSGS patients and animal models, Btg2 is markedly upregulated by podocytes and correlated with progressive renal injury. Podocyte-specific deletion of Btg2 protected against the onset of proteinuria and glomerulosclerosis in ADR-treated mice along with inhibition of EMT markers such as α-SMA and vimentin while restoring epithelial marker E-cadherin. In cultured MPC5 podocytes, overexpression of Btg2 largely promoted ADR and TGF-β1-induced EMT and fibrosis, which is further enhanced by overexpressing Btg2 but blocked by disrupting Btg2. Mechanistically, Btg2 is rapidly induced by TGF-β1 and then bound Smad3 but not Smad2 to promote Smad3 signaling and podocyte EMT, which is again exacerbated by overexpressing Btg2 but blocked by deleting Btg2 in MPC5 podocytes. Interestingly, blockade of Smad3 signaling with a Smad3 inhibitor SIS3 is also capable of inhibiting Btg2 expression and Btg2-mediated podocyte EMT, revealing a TGF-β/Smad3-Btg2 circuit mechanism in Btg2-mediated podocyte injury in FSGS. In conclusion, Btg2 is pathogenic in FSGS and promotes podocyte injury via a Smad3-dependent EMT pathway.

CDDO-Me ameliorates podocyte injury through anti-oxidative stress and regulation of actin cytoskeleton in adriamycin nephropathy

Podocyte injury is the common initiating event in focal segmental glomerulosclerosis (FSGS). Oxidative stress and inflammation mediate podocyte injury in FSGS. NRF2 pathway regulates the constitutive and inducible transcription of various genes that encode antioxidant proteins and anti-inflammatory proteins and have pivotal roles in the defense against cellular oxidative stress. In this study, we used adriamycin-induced nephropathy (ADR) in mice as a model of FSGS to confirm that CDDO-Me treatment ameliorated adriamycin-induced kidney damage by improving renal function and kidney histology. CDDO-Me inhibited the level of oxidative stress, inflammation, and apoptosis in adriamycin-induced podocyte injury by activating NRF2 pathway in vivo and in vitro. Furthermore, CDDO-Me stabled the cytoskeleton by regulating NRF2/srGAP2a pathway. Together, these findings show that by activating NRF2 pathway, CDDO-Me could be a therapeutic strategy to prevent the adverse effects of adriamycin-induced podocyte injury.

Asparagine endopeptidase protects podocytes in adriamycin-induced nephropathy by regulating actin dynamics through cleaving transgelin

Focal segmental glomerulosclerosis (FSGS) is the most common glomerular disorder causing end-stage renal diseases worldwide. Central to the pathogenesis of FSGS is podocyte dysfunction, which is induced by diverse insults. However, the mechanism governing podocyte injury and repair remains largely unexplored. Asparagine endopeptidase (AEP), a lysosomal protease, regulates substrates by residue-specific cleavage or degradation. We identified the increased AEP expression in the primary proteinuria model which was induced by adriamycin (ADR) to mimic human FSGS. In vivo, global AEP knockout mice manifested increased injury-susceptibility of podocytes in ADR-induced nephropathy (ADRN). Podocyte-specific AEP knockout mice exhibited much more severe glomerular lesions and podocyte injury after ADR injection. In contrast, podocyte-specific augmentation of AEP in mice protected against ADRN. In vitro, knockdown and overexpression of AEP in human podocytes revealed the cytoprotection of AEP as a cytoskeleton regulator. Furthermore, transgelin, an actin-binding protein regulating actin dynamics, was cleaved by AEP, and, as a result, removed its actin-binding regulatory domain. The truncated transgelin regulated podocyte actin dynamics and repressed podocyte hypermotility, compared to the native full-length transgelin. Together, our data reveal a link between lysosomal protease AEP and podocyte cytoskeletal homeostasis, which suggests a potential therapeutic role for AEP in proteinuria disease.

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.

Coexistence of Interstitial Nephritis and the Cellular Variant of Focal Segmental Glomerulosclerosis Secondary to Anabolic Steroid Abuse

Anabolic-androgenic steroids (AAS) have been widely used by young people to enhance performance and increase muscle mass. The use of AAS can affect the kidneys and lead to a myriad of presentations, ranging from mildly elevated serum creatinine and blood urea nitrogen to irreversible chronic kidney disease and focal segmental glomerulosclerosis (FSGS). To the best of our knowledge, the coexistence of interstitial nephritis and the cellular variant of FSGS [Immunoglobulin M (IgM)] secondary to AAS abuse has not been previously reported in the literature. Here, we report the case of a 40-year-old bodybuilder who developed simultaneous interstitial nephritis and the cellular variant of FSGS (IgM) after short-term use of AAS and other dietary supplements.

Role of Rituximab in Patients with Resistant Nephrotic Syndrome

Resistant nephrotic syndrome is a group of disorders with diverse histological findings, which are by definition resistant to corticosteroids given in adequate dose for adequate duration and many are resistant to other therapy as well. In many patients progression to end-stage renal disease is the ultimate outcome. The role of B cells has not been fully explained in man, agents that specifically interfere with B cells would ideally represent the first step toward selective therapy. We studied short term and long term effects of rituximab in patients with resistent primary nephrotic syndrome.

MATERIAL

Study was conducted at SMS-medical college and Hospital Jaipur, four doses of rituximab were given weakly, in fixed dose of 500 mg per dose and proteinuria was evaluated before start of therapy and at 3 months, 6 months and 12 months of therapy. Patients with resistant primary nephrotic syndrome who failed to respond to other therapies, with stable eGFR >30, and controlled BP were included in study. Patients with Active infection, Uncontrolled hypertension, pregnancy were excluded from study.

OBSERVATION

10 patients were enrolled in study out of which 7 FSGS (focal segmental glomeruloscllerosis) and 3 were IMN (idiopathic membranous nephropathy), 5 were female and 5 were male, age 17-61years (average 34.6), weight were 48-70 kg (avg 57.9), BMI 19.4-23 (AVG 21.18), all patients have normal renal function (average creatinine value of 0.8, range= 0.5 to 1.1). At 3 months 1 patient had partial response and 9 had no response. At 6 months of treatment 2 patients had partial response, 3 had complete response and 5 no response. At 12 months of treatment 4 had partial response, 5 had complete response and 1 no response. Out of 10 patients no one had relapse of Nephrotic syndrome at 12 month of therapy. Renal function remain normal in all patients over 12 months followup.

CONCLUSION

This prospective, observational study evaluated 3 month, 6 month, and 12 month outcome of 3 IMN and 7 FSGS patients, with persistent nephrotic range proteinuria and showed that rituximab promoted sustained remission in proteinuria in resistent nephrotic syndrome with normal renal function.

COVID-19 Associated Collapsing FSGS in an APOL1 Homozygous Transplant Recipient After Successful COVID Vaccination: A Case Report

Organ transplant recipients exhibit lower rates of immune response to coronavirus disease 2019 (COVID-19) vaccination. Even when they do mount a demonstrable antibody response, it is unclear what degree of protection is conferred against the myriad potential complications of COVID-19 infection. We present here a case of a kidney transplant recipient who was homozygous for APOL1 risk alleles on low-dose immunosuppression who developed an antibody response to COVID-19 vaccination and subsequently acquired COVID-19 infection. Although she experienced relatively minor effects in other organ systems, she developed severe collapsing focal segmental glomerulosclerosis that left her dependent on hemodialysis on hospital discharge. This suggests that COVID-19 vaccination may not provide protection from infection-associated focal segmental glomerulosclerosis in patients with APOL1 risk alleles.

Pembrolizumab-induced focal segmental glomerulosclerosis: A case report

RATIONALE

Focal segmental glomerulosclerosis (FSGS) is the most common primary glomerular disorder that leads to end-stage kidney disease. Pembrolizumab, an immune checkpoint inhibitor, is an anti-programmed death 1 (PD-1) immunoglobulin G4 antibody approved for the treatment of advanced melanoma and can cause various renal immune-related adverse events (AEs), including acute kidney injury. Several cases of anti PD-1 therapy-induced glomerulonephritis have been reported so far, but FSGS has seldom been reported.

PATIENT CONCERNS

46-year old woman presented to our hospital with generalized edema.

DIAGNOSES

Laboratory examination revealed features of nephrotic syndrome, and kidney biopsy confirmed FSGS. After other etiological factors of secondary FSGS were ruled out, she was diagnosed with FSGS caused by pembrolizumab.

INTERVENTIONS

She did not resume treatment with pembrolizumab and was treated with irbesartan and furosemide according to the American Society of Clinical Oncology Practice guidelines.

OUTCOMES

After 2 months, the features of nephrotic syndrome resolved.

LESSONS

This case provides valuable insight into the etiology of FSGS that can occur as a renal immune-related AE of PD-1 inhibitor therapy. Therefore, patients should undergo evaluation for renal function and urinalysis at baseline and after treatment. If patients treated with PD-1 inhibitors present with renal injury and/or unexplained proteinuria >1 g/day, we would recommend a kidney biopsy to determine the underlying cause and establish an appropriate therapeutic plan.

Rhodojaponin II attenuates kidney injury by regulating TGF-β1/Smad pathway in mice with adriamycin nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Rhododendron molle G. Don (Ericaceae) (RM) is a natural medicinal plant. Its root extracts have been applied in clinic and proved to be effective in chronic glomerulonephritis and rheumatoid arthritis in China. Surprising, little is understood about the key compound of RM and the exact mechanisms underlying its treatment on kidney diseases. In this study, we will explore whether rhodojaponin II (R-II), as the important compound of RM, also exerts the major effect.

MATERIALS AND METHODS

Mouse model of focal segmental glomerulosclerosis was induced by single dose of adriamycin injection. Induced adriamycin nephropathy (ADRN) mice were treated individually with RM root extract (5 mg/kg, n = 5), RM root extract (60 mg/kg, n = 5), R-II (0.04 mg/kg, n = 6) or captopril (30 mg/kg, n = 5) for five weeks. Podocyte marker (nephrin and podocin) expressions were examined by immunohistochemical staining and Western Blot analysis. Fibronectin level was evaluated by immunohistochemical staining and Western Blot analysis. Interstitial infiltrated inflammatory cells (CD4⁺ T cells, CD8⁺ T cells, and CD68⁺ macrophages) were examined with immunohistochemical staining. The expressions of NF-ĸB p-p65 and TGF-β1/Smad pathway associated key proteins, such as TGF-β1, Smad3, phosphorylated-Smad3 (p-Smad3), and Smad7, were analyzed respectively by Western Blot analysis.

RESULTS

RM root extract (5 mg/kg) and its important compound R-II (0.04 mg/kg) significantly ameliorated proteinuria, podocyte injury, and glomerulosclerosis, meanwhile, they hampered interstitial fibrosis in mice with ADRN. R-II significantly reduced NF-ĸB p65 phosphorylation, interstitial infiltrated CD4⁺ T cells, CD8⁺ T cells, and CD68⁺ macrophages, at the same time, down-regulated TGF-β1 and p-Smad3 protein expressions in mice with ADRN.

CONCLUSION

RM root extract, R-II, could effectively ameliorate proteinuria and kidney injury in ADRN, related to its anti-inflammatory effects, as well as suppression of TGF-β1/Smad signaling pathway.

TARGETING TARGETED TREATMENT FOR IMMUNE AND NON-IMMUNE KIDNEY DISEASES

We have found that calcium calmodulin kinase IV is increased in T cells, podocytes, and mesangial cells from patients with systemic lupus erythematosus, as well as in lupus-prone mice, podocytes of patients with focal segmental glomerulosclerosis, and in mice injected with doxorubicin. We showed that this accounts for aberrant T cell function and glomerular damage. Using nanoparticles (nlg) loaded with a small drug inhibitor of calcium calmodulin kinase IV and tagged with antibodies directed to CD4 we have been able to show inhibition of autoimmunity and lupus nephritis. Also, using nlg tagged with antibodies to nephrin, we showed suppression of nephritis in lupus-prone mice and of glomerular damage in mice exposed to doxorubicin. We propose the development of approaches to deliver drugs to cells in a targeted and precise manner.

Hydroxypropyl-β-cyclodextrin protects from kidney disease in experimental Alport syndrome and focal segmental glomerulosclerosis

Studies suggest that altered renal lipid metabolism plays a role in the pathogenesis of diabetic kidney disease and that genetic or pharmacological induction of cholesterol efflux protects from the development of diabetic kidney disease and focal segmental glomerulosclerosis (FSGS). Here we tested whether altered lipid metabolism contributes to renal failure in the Col4a3 knockout mouse model for Alport Syndrome. There was an eight-fold increase in the cholesterol content in renal cortexes of mice with Alport Syndrome. This was associated with increased glomerular lipid droplets and cholesterol crystals. Treatment of mice with Alport Syndrome with hydroxypropyl-β-cyclodextrin (HPβCD) reduced cholesterol content in the kidneys of mice with Alport Syndrome and protected from the development of albuminuria, renal failure, inflammation and tubulointerstitial fibrosis. Cholesterol efflux and trafficking-related genes were primarily affected in mice with Alport Syndrome and were differentially regulated in the kidney cortex and isolated glomeruli. HPβCD also protected from proteinuria and mesangial expansion in a second model of non-metabolic kidney disease, adriamycin-induced nephropathy. Consistent with our experimental findings, microarray analysis confirmed dysregulation of several lipid-related genes in glomeruli isolated from kidney biopsies of patients with primary FSGS enrolled in the NEPTUNE study. Thus, lipid dysmetabolism occurs in non-metabolic glomerular disorders such as Alport Syndrome and FSGS, and HPβCD improves renal function in experimental Alport Syndrome and FSGS.

[FSGS collapsing variant during anabolic steroid abuse: Case Report]

Anabolic Androgenic Steroids (AAS) is an hormone family whose use has considerably increased among body-builders during the last decades. The AAS abuse, especially associated with other drugs or nutritional supplements and protein loads, may cause a variety of pathologies to several organs with a mechanism related to dosage, timing and substance. The kidney is the main metabolizer of these drugs and it can be acutely or chronically damaged with ESKD. The literature reports some cases of Focal Segmental Glomerulosclerosis (FSGS) in body-builders who abused of AAS. However, the link is not well understood and limited to some case-studies. In this paper, we report the case of a young body-builder who developed a FSGS collapsing variant with ESKD after prolonged abuse of AAS and a strongly hyperproteic diet and other dietary supplements. The patient underwent a genetic test because of the rapid and irreversibile onset of ESKD. The test showed a gene mutation of ACTN4, predisposing and causal of some genetic forms of FSGS. It was a very complex case, caused by several factors. The mutant protein of ACTN4 gene makes most vulnerable the cytoskeleton of the podocytes to external disturbances. That would explain why in those patients where the mutation has occurred, only those patients subject to "unfavorable environmental conditions", like the abuse of AAS, can develop a disease.

Role of MiR-155 Signal Pathway in Regulating Podocyte Injury Induced by TGF-β1

BACKGROUND/AIMS

Transforming growth factor beta 1 (TGF-β1) plays a critical role in the pathogenesis of glomerulosclerosis. The purpose of this study was to examine the effects of inhibition of miR-155 on podocyte injury induced by TGF-β1 and to determine further molecular mediators involved in the effects of miR-155.

METHODS

Conditionally immortalized podocytes were cultured in vitro and they were divided into four groups: control; TGF-β1 treatment; TGF-β1 with miR-155 knockdown [using antisense oligonucleotides against miR-155 (ASO-miR-155)] and TGF-β1 with negative control antisense oligonucleotides (ASO-NC). Real time RT-PCR and Western blot analysis were employed to determine the mRNA and protein expression of nephrin, desmin and caspase-9, respectively. Flow cytometry was used to examine the apoptotic rate of podocytes and DAPI fluorescent staining was used to determine apoptotic morphology. In addition, we examined the levels of miR-155, TGF-β1, nephrin, desmin and caspase-9 in glomerular tissues of nephropathy induced by intravenous injections of adriamycin in rats.

RESULTS

mRNA and protein expression of desmin and caspase-9 was increased in cultured TGF-β1-treated podocytes, whereas nephrin was decreased as compared with the control group. Importantly, miR-155 knockdown significantly attenuated upregulation of desmin and caspase-9, and alleviated impairment of nephrin induced by TGF-β1. Moreover, the number of apoptotic podocytes was increased after exposure to TGF-β1 and this was alleviated after miR-155 knockdown. Knocking down miR-155 also decreased an apoptosis rate of TGF-β1-treated podocytes. Note that negative control antisense oligonucleotides failed to alter an increase of the apoptosis rate in TGF-β1-treated podocytes. Consistent with in vitro results, expression of miR-155, TGF-β1, desmin and caspase-9 was increased and nephrin was decreased in glomerular tissues with nephropathy in vivo experiments.

CONCLUSIONS

TGF-β1 impairs the protein expression of nephrin and amplifies the protein expression of desmin and caspase -9 via miR-155 signal pathway. Inhibition of miR-155 alleviates these changes in podocytes-treated with TGF-β1 and attenuated apoptosis of podocytes. Our data suggest that miR-155 plays a role in mediating TGF-β1-induced podocyte injury via nephrin, desmin and caspase-9. Results of the current study also indicate that blocking miR-155 signal has a protective effect on podocyte injury. Targeting one or more of these signaling molecules may present new opportunities for treatment and management of podocyte injury observed in glomerulosclerosis.

Role of Protease-Activated Receptor 2 in Regulating Focal Segmental Glomerulosclerosis

Background /Aims: The underlying mechanisms leading to focal segmental glomerulosclerosis (FSGS) are lacking. In this report, we examined the role of protease-activated receptors (PARs) subtype PAR2 and its downstream signals in regulating the pathophysiological process of FSGS.

METHODS

Nephropathy was induced by intravenous injections of adriamycin (ADR) in rats to study FSGS. Western Blot analysis and ELISA were employed to determine the protein expression levels of PAR2 and its downstream signal pathways as well as the levels of PICs.

RESULTS

In ADR rats, expression of PAR2, PKCε and PKA was amplified and this was accompanied with increases of pro-inflammatory cytokines (PICs) including IL-1β, IL-6 and TNF-α. Inhibition of PAR2 signal by systemic administration of FSLLRY-NH2 (FSL) attenuated amplification of PICs. Notably, FSL further influenced key molecular mediators during development of FSGS. i.e., it specifically restored the impaired nephrin and attenuated the exaggerated transforming growth factor beta 1 (TGF-β1), caspase-9 and desmin thereby improving worsened renal functions and glomerular injury. Consistent with this, in cultured podocytes FSL also largely restored downregulation of nephrin and attenuated amplifications of caspase-9 and desmin induced by TGF-β1.

CONCLUSIONS

Results of this study suggest that PAR2 plays an important role in mediating renal injury induced by glomerulosclerosis. Inhibition of PAR2 signal pathway has a protective effect on FSGS mainly via PIC and TGF-β1 mechanisms. Targeting one or more of these signaling molecules may present new opportunities for treatment and management of FSGS observed in patients.

Gq signaling causes glomerular injury by activating TRPC6

Familial forms of focal segmental glomerulosclerosis (FSGS) have been linked to gain-of-function mutations in the gene encoding the transient receptor potential channel C6 (TRPC6). GPCRs coupled to Gq signaling activate TRPC6, suggesting that Gq-dependent TRPC6 activation underlies glomerular diseases. Here, we developed a murine model in which a constitutively active Gq α subunit (Gq(Q209L), referred to herein as GqQ>L) is specifically expressed in podocytes and examined the effects of this mutation in response to puromycin aminonucleoside (PAN) nephrosis. We found that compared with control animals, animals expressing GqQ>L exhibited robust albuminuria, structural features of FSGS, and reduced numbers of glomerular podocytes. Gq activation stimulated calcineurin (CN) activity, resulting in CN-dependent upregulation of TRPC6 in murine kidneys. Deletion of TRPC6 in GqQ>L-expressing mice prevented FSGS development and inhibited both tubular damage and podocyte loss induced by PAN nephrosis. Similarly, administration of the CN inhibitor FK506 reduced proteinuria and tubular injury but had more modest effects on glomerular pathology and podocyte numbers in animals with constitutive Gq activation. Moreover, these Gq-dependent effects on podocyte injury were generalizable to diabetic kidney disease, as expression of GqQ>L promoted albuminuria, mesangial expansion, and increased glomerular basement membrane width in diabetic mice. Together, these results suggest that targeting Gq/TRPC6 signaling may have therapeutic benefits for the treatment of glomerular diseases.

Kidney diseases associated with anti-vascular endothelial growth factor (VEGF): an 8-year observational study at a single center

Expanded clinical experience with patients taking antiangiogenic compounds has come with increasing recognition of the renal adverse effects. Because renal histology is rarely sought in those patients, the renal consequences are underestimated. Antiangiogenic-treated-cancer patients, who had a renal biopsy for renal adverse effects from 2006 to 2013, were included in the current study. Clinical features and renal histologic findings were reviewed. Our cohort was 100 patients (58 women) with biopsy-proven kidney disease using anti-vascular endothelial growth factor (VEGF) therapy with a mean age of 59.8 years (range, 20-85 yr). Patients were referred for proteinuria, hypertension, and/or renal insufficiency. Kidney biopsy was performed 6.87 ± 7.18 months after the beginning of treatment. Seventy-three patients experienced renal thrombotic microangiopathy (TMA) and 27 patients had variable glomerulopathies, mainly minimal change disease and/or collapsing-like focal segmental glomerulosclerosis (MCN/cFSGS). MCN/cFSGS-like lesions developed mainly with tyrosine-kinase inhibitors, whereas TMA complicated anti-VEGF ligand. Thirty-one percent of TMA patients had proteinuria up to 1 g/24 h. Half of TMA cases are exclusively renal localized. Pathologic TMA features are intraglomerular exclusively. MCN/cFSGS glomeruli displayed a high abundance of KI-67, but synaptopodin was not detected. Conversely, TMA glomeruli exhibited a normal abundance of synaptopodin-like control, whereas KI-67 was absent. Median follow-up was 12 months (range, 1-80 mo). Fifty-four patients died due to cancer progression. Hypertension and proteinuria resolved following drug discontinuation and antihypertensive agents. No patient developed severe renal failure requiring dialysis. Drug continuation or reintroduction resulted in a more severe recurrence of TMA in 3 out of 4 patients requiring maintenance of anti-VEGF agents despite renal TMA. In conclusion, TMA and MCN/cFSGS are the most frequent forms of renal involvement under anti-VEGF therapy. Careful risk-benefit assessment for individual patients should take into account risk factors related to the host and the tumor.

Low-dose of multi-glycoside of Tripterygium wilfordii Hook. f., a natural regulator of TGF-β1/Smad signaling activity improves adriamycin-induced glomerulosclerosis in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Transforming growth factor (TGF)-β1/Smad signaling pathway plays a critical role in the prolonged glomerulosclerosis (GS), which is an important determinant during the progression in chronic kidney disease (CKD). For recent 30 years, multi-glycoside of Tripterygium wilfordii Hook. f. (GTW), an extract from Chinese herbal medicine has been proved clinically effective in improving GS in CKD in China. However, therapeutic mechanisms involved in vivo are still unclear. In this study, we aimed to explain the dose-effects and molecular mechanisms of GTW on GS by regulating TGF-β1/Smad signaling activity in adriamycin (ADR)-induced nephropathy (ADRN).

MATERIALS AND METHODS

Rats with ADRN, created by unilateral nephrectomy and twice adriamycin injections (ADR, 4 mg/kg and 2 mg/kg) within 4 weeks, were divided into four groups, the Sham group, the Vehicle group, the low-dose GTW-treated group, and the high-dose GTW-treated group, and that, sacrificed at the end of the 6th week after administration. Proteinuria, blood biochemical parameters, glomerulosclerotic morphological makers, podocyte shape, and nephrin expression were examined, respectively. Protein expressions of key signaling molecules in TGF-β1/Smad pathway, such as TGF-β1, Smad3, phosphorylated-Smad2/3 (p-Smad2/3), and Smad7, were also evaluated individually.

RESULTS

The results indicated that the characterizations of ADRN involved the typical prolonged GS, a small amount of abnormal proteinuria, and the failing renal function; TGF-β1/Smad signaling molecules, especially Smad3, p-Smad2/3, and Smad7 were activated in vivo, accompanied by the exasperation of glomerulosclerotic lesion; GTW at high-dose (100 mg/kg) and low-dose (50 mg/kg) could slightly ameliorate the prolonged GS and nephrin expression, furthermore, the anti-proliferative action of GTW at high-dose was superior to that at low-dose, but caused the significant liver injury; in ADRN model rats, protein expressions of TGF-β1, p-Smad2/3, and Smad7 in the kidneys could be regulated with the treatment of GTW at low-dose.

CONCLUSION

This study farther demonstrated that the low-dose of GTW, as a natural regulator in vivo, could effectively and safely ameliorate the prolonged GS in FSGS model, via the potential molecular mechanisms involving the reduction of ECM components and the suppression of TGF-β1 over-expression, as well as the bidirectional regulation of TGF-β1/Smad signaling activity.

Acute kidney injury in a patient with nephrotic syndrome due to focal segmental glomerular nephritis induced by a single oral administration of high-dose bisphosphonate (minodronate)

We herein report the case of a 75-year-old man who developed an increased serum creatinine level (4.93 mg/dL) and oliguria with massive proteinuria (7.14 g/day) on the second day after a single oral administration of high-dose (56 mg) minodronate. The histology of a renal biopsy showed one area of glomerular sclerosis among 20 glomeruli with global foot process effacement of podocytes and mild infiltration of lymphocytes and eosinophils into the interstitial space. Acute kidney injury in nephrotic syndrome due to focal segmental glomerular sclerosis induced by minodronate was diagnosed. Following cessation of minodronate without the administration of immunosuppressive agents, the patient's renal function and proteinuria markedly improved.

Inhibition of calcium(2+)/calmodulin-dependent protein kinase type IV ameliorates experimental nephrotic syndrome

OBJECTIVE

Evidence has demonstrated that Ca(2+)/calmodulin-dependent protein kinase type IV (CaMKIV) contributes to altered cytokine production by promoting the production of inflammatory cytokines. This study aimed to explore the protective role and underlying mechanisms of CaMKIV inhibition in experimental nephrotic syndrome.

METHODS

BALB/c mice received single intravenous injections of adriamycin (10 mg/kg) then were sacrificed at two, four and six weeks. In the second study, treatment with KN-93, a CaMKIV inhibitor, or vehicle administered via intraperitoneal injection was started five days after adriamycin injection. Functional and pathologic parameters, the presence of inflammatory infiltration and the expressions of pro-inflammatory cytokines were assessed.

RESULTS

The CaMKIV protein expression levels were upregulated in the mice with adriamycin nephropathy, which was significantly inhibited by KN-93 (p<0.01). As compared with the vehicle-treated controls, KN-93 treatment resulted in marked suppression of proteinuria and serum creatinine at week 6 (p<0.01), but not at two weeks after induction of the disease. KN-93 inhibited glomerulosclerosis and the development of tubulointerstitial lesions. The renal alpha-smooth muscle actin (α-SMA) expression was also significantly suppressed by KN-93 treatment at week 6 (p<0.01). Moreover, KN-93 inhibited the renal monocyte chemoattractant protein-1 (MCP-1) expression, paralleled by a reduction in the interstitial infiltration of macrophages and T-cells (p<0.01).

CONCLUSION

Our findings suggest that activation of CaMKIV signaling is involved in the progression of glomerular diseases with a proteinuric state. Our data therefore justify the development of small molecule CaMKIV inhibitors for the treatment of clinical nephrotic syndrome.

Chronic VEGF blockade worsens glomerular injury in the remnant kidney model

VEGF inhibition can promote renal vascular and parenchymal injury, causing proteinuria, hypertension and thrombotic microangiopathy. The mechanisms underlying these side effects are unclear. We investigated the renal effects of the administration, during 45 days, of sunitinib (Su), a VEGF receptor inhibitor, to rats with 5/6 renal ablation (Nx). Adult male Munich-Wistar rats were distributed among groups S+V, sham-operated rats receiving vehicle only; S+Su, S rats given Su, 4 mg/kg/day; Nx+V, Nx rats receiving V; and Nx+Su, Nx rats receiving Su. Su caused no change in Group S. Seven and 45 days after renal ablation, renal cortical interstitium was expanded, in association with rarefaction of peritubular capillaries. Su did not worsen hypertension, proteinuria or interstitial expansion, nor did it affect capillary rarefaction, suggesting little angiogenic activity in this model. Nx animals exhibited glomerulosclerosis (GS), which was aggravated by Su. This effect could not be explained by podocyte damage, nor could it be ascribed to tuft hypertrophy or hyperplasia. GS may have derived from organization of capillary microthrombi, frequently observed in Group Nx+Su. Treatment with Su did not reduce the fractional glomerular endothelial area, suggesting functional rather than structural cell injury. Chronic VEGF inhibition has little effect on normal rats, but can affect glomerular endothelium when renal damage is already present.

Invariant natural killer T cell agonist modulates experimental focal and segmental glomerulosclerosis

A growing body of evidence demonstrates a correlation between Th2 cytokines and the development of focal and segmental glomerulosclerosis (FSGS). Therefore, we hypothesized that GSL-1, a monoglycosylceramide from Sphingomonas ssp. with pro-Th1 activity on invariant Natural Killer T (iNKT) lymphocytes, could counterbalance the Th2 profile and modulate glomerulosclerosis. Using an adriamycin(ADM)-based model of FSGS, we found that BALB/c mice presented albuminuria and glomerular degeneration in association with a Th2-like pro-fibrogenic profile; these mice also expressed a combination of inflammatory cytokines, such as IL-4, IL-1α, IL-1β, IL-17, TNF-α, and chemokines, such as RANTES and eotaxin. In addition, we observed a decrease in the mRNA levels of GD3 synthase, the enzyme responsible for GD3 metabolism, a glycolipid associated with podocyte physiology. GSL-1 treatment inhibited ADM-induced renal dysfunction and preserved kidney architecture, a phenomenon associated with the induction of a Th1-like response, increased levels of GD3 synthase transcripts and inhibition of pro-fibrotic transcripts and inflammatory cytokines. TGF-β analysis revealed increased levels of circulating protein and tissue transcripts in both ADM- and GSL-1-treated mice, suggesting that TGF-β could be associated with both FSGS pathology and iNKT-mediated immunosuppression; therefore, we analyzed the kidney expression of phosphorylated SMAD2/3 and SMAD7 proteins, molecules associated with the deleterious and protective effects of TGF-β, respectively. We found high levels of phosphoSMAD2/3 in ADM mice in contrast to the GSL-1 treated group in which SMAD7 expression increased. These data suggest that GSL-1 treatment modulates the downstream signaling of TGF-β through a renoprotective pathway. Finally, GSL-1 treatment at day 4, a period when proteinuria was already established, was still able to improve renal function, preserve renal structure and inhibit fibrogenic transcripts. In conclusion, our work demonstrates that the iNKT agonist GSL-1 modulates the pathogenesis of ADM-induced glomerulosclerosis and may provide an alternative approach to disease management.

A review of the diagnosis and treatment of Ochratoxin A inhalational exposure associated with human illness and kidney disease including focal segmental glomerulosclerosis

Ochratoxin A (OTA) exposure via ingestion and inhalation has been described in the literature to cause kidney disease in both animals and humans. This paper reviews Ochratoxin A and its relationship to human health and kidney disease with a focus on a possible association with focal segmental glomerulosclerosis (FSGS) in humans. Prevention and treatment strategies for OTA-induced illness are also discussed, including cholestyramine, a bile-acid-binding resin used as a sequestrant to reduce the enterohepatic recirculation of OTA.

Detection of intrarenal microstructural changes with supersonic shear wave elastography in rats

OBJECTIVES

To evaluate, in a rat model of glomerulosclerosis, whether ultrasonic shear wave elastography detects kidney cortex stiffness changes and predicts histopathological development of fibrosis.

MATERIALS AND METHODS

Three groups were studied transversally: a control group (n = 8), a group after 4 weeks of L-NAME administration (H4, n = 8), and a group after 6 weeks (H6, n = 15). A fourth group was studied longitudinally (n = 8) before, after 4 weeks and after 7 weeks of L-NAME administration. Shear modulus of renal cortex was quantified using supersonic shear imaging technique. Urine was analysed for dosage of protein/creatinine ratio. Kidneys were removed for histological quantification of fibrosis.

RESULTS

Diseased rats showed an increased urinary protein/creatinine ratio. Cortical stiffness expressed as median (interquartile range) was 4.0 kPa (3.3-4.5) in control kidneys. It increased in all but one pathological groups: H4: 7.7 kPa (5.5-8.6) (p < 0.01); H6: 4.8 kPa (3.9-5.9) (not significant); in the longitudinal cohort, from 4.5 kPa (3.1-5.9) to 7.7 kPa (5.9-8.3) at week 4 (p < 0.05) and to 6.9 kPa (6.1-7.8) at week 7 (p < 0.05). Stiffness values were correlated with the proteinuria/creatininuria ratio (r = 0.639, p < 0.001).

CONCLUSIONS

Increased cortical stiffness is correlated with the degree of renal dysfunction. More experience in other models is necessary to understand its relationship with microstructural changes.

Treatment with IFN-{alpha}, -{beta}, or -{gamma} is associated with collapsing focal segmental glomerulosclerosis

BACKGROUND AND OBJECTIVES

Treatment with IFN is rarely associated with nephrotic syndrome and renal biopsy findings of minimal-change disease or FSGS.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We report 11 cases of collapsing FSGS that developed during treatment with IFN and improved after discontinuation of therapy.

RESULTS

The cohort consists of seven women and four men with a mean age of 48.2 yr. Ten of the 11 patients were black. Six patients were receiving IFN-alpha for hepatitis C virus infection (n = 5) or malignant melanoma (n = 1), three were receiving IFN-beta for multiple sclerosis, and two were treated with IFN-gamma for idiopathic pulmonary fibrosis. After a median and mean [corrected] duration of therapy of 4.0 and 12.6 months, respectively, patients presented with acute renal failure (mean creatinine 3.5 mg/dl) and nephrotic-range proteinuria (mean 24-hour urine protein 9.7 g). Renal biopsy revealed collapsing FSGS with extensive foot process effacement and many endothelial tubuloreticular inclusions. Follow-up was available for 10 patients, all of whom discontinued IFN. At a mean of 23.6 months, nine of 10 patients had improvement in renal function, including one with complete remission and two with partial remission. Among the seven patients with available data, mean proteinuria declined from 9.9 to 3.0 g/d. Four of the seven patients were treated with immunosuppression, and there was no detectable benefit.

CONCLUSIONS

Collapsing FSGS may occur after treatment with IFN-alpha, -beta, or -gamma and is typically accompanied by the ultrastructural finding of endothelial tubuloreticular inclusions. Optimal therapy includes discontinuation of IFN.

Increased Oxidative Stress in the Mouse Adriamycin Model of Glomerulosclerosis Is Accompanied by Deposition of Ferric Iron and Altered GGT Activity in Renal Cortex

Chronic renal failure evolves inevitable towards glomerular and tubulo-interstitial sclerosis. This pathological process involves a disturbed redox status of the kidney tissue, leading to irreversible damage. In this study we investigate in an adriamycin model of chronic renal failure in mice the evolution of in vivo hydrogen peroxide production, and the possible role of gamma-glutamyl transpeptidase and ferric iron in the process. Histological changes and ferric iron deposits are evaluated by histochemical staining. To evaluate oxidative stress residual catalase activity, TBARS formation and gamma-glutamyl transpeptidase activity are measured spectrophotometrically. While catalase activity remains the same, a decreased residual catalase activity indicates an increased formation of hydrogen peroxide. Both the activity of gamma-glutamyl transpeptidase and TBARS formation is increased at early stages of the disease. Ferric iron is clearly present in the proximal tubule. Twenty days after adriamycin injection all parameters decrease, probably due to the destruction of the tissue. Our data show the involvement of oxidative stress in the progression of adriamycin induced renal failure in mice. Both radical production and oxidative damage are measurable, while the altered activity of gamma-glutamyl transpeptidase and the deposition of ferric iron suggest the involvement of these factors in the development of a disturbed redox status in the kidney cortex.

Rapamycin attenuates the severity of murine adriamycin nephropathy

BACKGROUND

Rapamycin is an immunosuppressive drug with potent antifibrotic activity. We evaluated the effect of rapamycin on murine adriamycin nephropathy, a model of progressive glomerulosclerosis and tubulointerstitial fibrosis.

METHODS

Adriamycin nephropathy was induced in Balb/c mice by a single intravenous injection of adriamycin. The mice were treated orally with either saline or rapamycin, beginning at the time of adriamycin injection or rapamycin starting 1 week after adriamycin injection. The mice were sacrificed 6 weeks after adriamycin injection.

RESULTS

Saline-treated mice developed massive proteinuria and impaired renal function. Kidney sections from saline-treated mice showed marked focal segmental glomerulosclerosis, tubular dilation with protein cast deposition, interstitial fibrosis, and numerous infiltrating macrophages and T lymphocytes. The intrarenal expression of Collagen I and RANTES was also increased. In contrast, both groups of rapamycin-treated mice had markedly reduced proteinuria and preserved renal function, with only mild histological abnormalities. The intrarenal expression of Collagen I and RANTES was reduced, concomitant with a significant reduction in interstitial inflammatory cell infiltration.

CONCLUSIONS

Rapamycin is effective in attenuating the glomerular and tubulointerstitial abnormalities in adriamycin nephropathy. The beneficial effects of rapamycin are mediated, at least in part, through reduced RANTES expression and inflammatory cell infiltration.

Osteopontin as an injury marker expressing in epithelial hyperplasia lesions helpful in prognosis of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is characterized by typical sclerosis but also shows other non-sclerotic lesions that provide prognostic informations. The glomerular epithelial hyperplasia lesion (EPHL) that develops earlier than the sclerotic lesions is a key determinant of progression of FSGS. However, the relationship among EPHL, glomeular sclerosis, and macrophage infiltration in FSGS is unclear, and the EPHL-associated markers helpful for prognosis of FSGS have still not been completely identified. Here, we performed clinicopathologic, immunochemical, and molecular analyses to examine whether osteopontin (OPN), a macrophage chemokine, is an injury marker of EPHLs correlating with glomerular sclerosis and macrophage mobilization. First, the FSGS model was induced in Balb/c mice by a single injection of adriamycin, and consecutive sclerosis changes were evaluated. In parallel, we used reverse transcription-polymerase chain reaction and Western blot analyses to determine levels of OPN in isolated glomeruli and urine, respectively. Immunohistochemistry was applied to assess the OPN expression in EPHLs and macrophage infiltration around the glomeruli. Our results showed that, within glomeruli, OPN expressed restrictedly within EPHL; the OPN mRNA and protein of glomeruli increased on day 11, correlating well with the early EPHL, and following sclerosis and macrophage infiltration. In addition, immunohistochemistry (IHC) staining of OPN greatly highlighted early glomerular EPHLs, helping microscopic identification of EPHLs. We propose that the OPN expression in EPHLs could contribute to the progression of FSGS by recruiting macrophage toward the compromised glomeruli. Detection of OPN in glomeruli and urine could be helpful in prognosis of FSGS.

Collapsing focal segmental glomerulosclerosis in a liver transplant recipient on alendronate

We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient after the initiation of alendronate for osteopenia. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonates need to be used with caution in these patients. The usefulness of bisphosphonates for the prevention of early bone loss after liver transplantation is increasingly reported. However, there is little information on the safety and efficacy of these drugs when used in the later stages of liver transplant, particularly in the presence of chronic kidney disease. Bisphosphonates are excreted unchanged via the kidneys after reaching the systemic circulation. Some cases of severe kidney injury, in particular collapsing focal segmental glomerulosclerosis, have been described that are associated with the use of pamidronate. Alendronate, a widely used bisphosphonate in transplant patients, has not been related to kidney toxicity. We describe a case of collapsing focal segmental glomerulosclerosis and severe kidney dysfunction in a liver transplant recipient soon after the initiation of alendronate for osteopenia. Possible pathogenetic mechanisms are discussed. In view of the increasing incidence of chronic kidney disease in long-term liver transplant patients, bisphosphonate need to be used with caution in patients with a low glomerular filtration rate.

[Effects of Haikun Shenxi on expression of platelet-derived growth factor-B and mRNA in renal tissue of rats with adriamycin nephropathy]

OBJECTIVE

To investigate the effects of Haikun Shenxi on the expression of platelet-derived growth factor-BB (PDGF-BB) and mRNA in renal tissue of rats with adriamycin nephropathy.

METHOD

Rat model was established by unilateral nephrectomy and injecting adriamycin intraperitoneally. The adriamycin-induced nephrotic rats were randomly divided into 6 groups: normal group, sham operation group, model group, lotensin treatment group, Haikun Shenxi low and high dose treatment groups (0.77, 0.08 mg x kg(-1). Ten weeks later, the 24 hour urine protein and blood biochemistry examinations and renal pathologic changes were observed, and the expression of PDGF-BB and mRNA was measured using immunohistochemical method.

RESULT

Compared with model group, proteinuria and the levels of serum creatinine (Scr) , urea nitrogen (BUN) were decreased obviously in both Haikun Shenxi low and high dose groups. The expression of PDGF-BB and mRNA was mostly presented in cytoplasm of renal tubular epithelial cells and mesangial area, and it could be reduced significantly after treatment (P < 0. 05).

CONCLUSION

The level of PDGF-BB and mRNA is high in renal tissue of adriamycin-induced nephrotic rats. This progress could be effectively inhibited by Haikun Shenxi and the mechanism may be that it can control the excessive expression of PDGF-BB and mRNA.

The renal clearance of dextran sulfate decreases in puromycin aminonucleoside-induced glomerulosclerosis: A puzzle observation

BACKGROUND

Puromycin aminonucleoside-induced nephrosis is characterized by increased renal excretion of plasma proteins. We employed this experimental model to study the urinary clearance of dextran sulfate.

METHODS

The dextran sulfate eliminated by the urine was determined using a metachromatic assay. Polysaccharide fragments were analyzed by chromatographic and electrophoretic procedures. Disaccharide composition of the glomerular heparan sulfate was assessed using digestion with specific lyases.

RESULTS

In normal rats dextran sulfate is partially degraded to lower molecular weight fragments and only then eliminated by the urine. Surprisingly, in puromycin aminonucleoside-induced glomerulosclerosis the molecular size of the fragments of dextran sulfate found in the urine is the same or even lower than in control animals in spite of the marked proteinuria. Furthermore, urinary excretion of dextran sulfate decreases in the experimentally induced nephrosis. This observation cannot be totally attributed to a reduced number of physiologically active nephrons since the glomerular filtration rate decreases approximately 32% after puromycin aminonucleoside administration while the urinary excretion of 8 kDa-dextran sulfate decreases 3-fold. The glomerular heparan sulfate shows reduced sulfation when compared with normal animals. Possibly puromycin aminonucleoside decreases the activity of kidney endoglycosidases, which reduce the molecular size of the sulfated polysaccharide, leading to a decrease in its renal clearance. Reduced sulfation of the glomerular heparan sulfate in the puromycin aminonucleoside-induced nephrosis does not alter the size of the dextran sulfate eliminated by the kidney, as suggested for protein.

CONCLUSIONS

Each pathological process induces a particular modification in the kidney, which in turn can affect the renal selectivity to specific macromolecules in different ways.

Ex vivo programmed macrophages ameliorate experimental chronic inflammatory renal disease

Macrophage infiltration of the kidney is a prominent feature associated with the severity of renal injury and progressive renal failure. To determine the influence of macrophages in renal disease models in the absence of endogenous T and B cells, we performed adoptive transfer of macrophages into severe combined immunodeficient (SCID) mice. In this study, macrophages were isolated from the spleens of BALB/c mice and stimulated with lipopolysaccharide to induce classically activated M1 macrophages or with interleukin-4 (IL-4) and IL-13 to induce alternatively activated M2 macrophages. These macrophages were then infused into SCID mice with adriamycin nephropathy; an in vivo model of chronic inflammatory renal disease analogous to human focal segmental glomerulosclerosis. Mice infused with M1 macrophages had a more severe histological and functional injury, whereas M2 macrophage-induced transfused mice had reduced histological and functional injury. Both M1 and M2 macrophages localized preferentially to the area of injury and maintained their phenotypes even after 4 weeks. The protective effect of M2 macrophages was associated with reduced accumulation and possibly downregulated chemokine and inflammatory cytokine expression of the host infiltrating macrophages. Our findings demonstrate that macrophages not only act as effectors of immune injury but can be induced to provide protection against immune injury.

High sirolimus levels may induce focal segmental glomerulosclerosis de novo

Sirolimus has been associated with high-range proteinuria when used in replacement of calcineurin inhibitors in renal transplant recipients with chronic allograft nephropathy (CAN). Primary FSGS was demonstrated previously in some such patients, but the coexistence of CAN lesions made the interpretation uneasy. However, nephrotic syndrome and FSGS were observed recently in three patients who received sirolimus de novo, without medical history of primary FSGS or CAN. Markers of podocyte differentiation were studied in kidney biopsies of the three patients who received sirolimus de novo and of five patients who switched to sirolimus. All patients developed FSGS lesions of classic type (not otherwise specified), but only switched patients exhibited advanced sclerotic lesions. Immunohistochemistry showed that some podocytes in FSGS lesions had absent or diminished expression of the podocyte-specific epitopes synaptopodin and p57, reflecting dedifferentiation, and had acquired expression of cytokeratin and PAX2, reflecting a immature fetal phenotype. Such a pattern of epitope expression provides evidence for podocyte dysregulation. Moreover, a decrease in vascular endothelial growth factor expression was observed in some glomeruli. In conclusion, sirolimus induces FSGS that is responsible for proteinuria in some transplant patients.

Dietary protein induces endothelin-mediated kidney injury through enhanced intrinsic acid production

Dietary protein as casein (CAS) augments intrinsic acid production, induces endothelin-mediated kidney acidification, and promotes kidney injury. We tested the hypothesis that dietary CAS induces endothelin-mediated kidney injury through augmented intrinsic acid production. Munich-Wistar rats ate minimum electrolyte diets from age 8 to 96 weeks with 50 or 20% protein as either acid-inducing CAS or non-acid-inducing SOY. Urine net acid excretion and distal nephron net HCO3 reabsorption by in vivo microperfusion (Net J(HCO3)) were higher in 50 than 20% CAS but not 50 and 20% SOY. At 96 weeks, 50% compared the 20% CAS had higher urine endothelin-1 excretion (U(ET-1)V) and a higher index of tubulo-interstitial injury (TII) at pathology (2.25+/-0.21 vs 1.25+/-0.13 U, P<0.03), but each parameter was similar in 50 and 20% SOY. CAS (50%) eating NaHCO3 to reduce intrinsic acid production had lower Net J(HCO3), lower U(ET-1)V, and less TII. By contrast, 50% SOY eating dietary acid as (NH4)2SO4 had higher Net J(HCO3), higher U(ET-1)V, and more TII. Endothelin A/B but not A receptor antagonism reduced Net J(HCO3) in 50% CAS and 50% SOY+(NH4)2SO4 animals. By contrast, endothelin A but not A/B receptor antagonism reduced TII in each group. The data support that increased intake of acid-inducing dietary protein induces endothelin B-receptor-mediated increased Net J(HCO3) and endothelin A-receptor-mediated TII through augmented intrinsic acid production.

Life-threatening thrombocytopenia and nephrotic syndrome due to focal segmental glomerulosclerosis associated with pegylated interferon alpha-2b and ribavirin treatment for hepatitis C

BACKGROUND

Interferon-alpha (IFN-alpha)and ribavirin combination therapy for chronic infection with hepatitis C virus produces a number of well-described side effects. Combination therapy with pegylated interferon (PEG-IFN) yields an adverse event profile similar to that observed with the standard IFN, although the frequency of certain adverse events may vary according to the preparation.

CASE REPORT

We report the case of a 44-year-old man who was treated with ribavirin and PEG-IFN-alpha-2b for chronic hepatitis C and developed two rare side effects simultaneously on the 16th week of therapy: severe thrombocytopenia and nephrotic syndrome due to focal segmental glomerulosclerosis. The antiviral treatment was immediately interrupted and the patient received immunosuppressive therapy. He promptly recovered from the thrombocytopenia and partially and slowly from the nephrotic syndrome. To our knowledge, this is the first case reported of the development of such complications at the same time.

Turbulence of glomerular hemodynamics involved in progressive glomerulosclerosis

There is increasing evidence that changes of glomerular hemodynamics or glomerular growth responses may promote the development of glomerulosclerosis. Major problems retarding research progress include lack of suitable experimental animal models, with the exception of the ablation model, and the need for in vivo real-time analysis of glomerular hemodynamics. This study examined the sequence of pathological changes from the viewpoints of microcirculation and histopathology, from the acute stage to the chronic course and the final stage of glomerulosclerosis, using the confocal laser scanning microscope system. There is a marked difference in prognosis between sham-operated (two-kidney) and nephrectomized (one-kidney) rats after injection with anti-Thy-1 antibody. The former reversibly returns to normal and the latter irreversibly go to progressive sclerosis, respectively. The turning point determining the progression of glomerulosclerosis in both groups seemed to be the period from 7 to 14 days after disease induction, when disturbance of local intraglomerular blood flow continued in the one-kidney groups. In conclusion, this study provides the first hemodynamic-based evidence showing that disturbance of intraglomerular microcirculation is a critical marker for progressive glomerulosclerosis.

A potential pathological role of angiopoietins expression in glomeruli during progressive glomerulisclerosis related to podocyte injury

A potential pathological role of angiopoietins (Ang) in glomeruli following podocyte injury-induced progressive glomerulosclerosis was explored. Eighty male Wistar rats were randomly allocated into sham operation group (Sham, n = 25), Uninephrectomy group (UPHT, n = 25) and Uninephrectomy+Daunorubicin group (DRB, n = 30). In DRB group, daunorubicin (5 mg/kg) was injected via tail vein on the 7th and 14th day after uninephrectomy. At week 1, 2, 4, 6 and 8 respectively following establishment of the animal model, 5 rats in Sham group and UPHT group, and 6 in DRB group were taken respectively for determining 24-h urinary protein excretion rate (24hUPER), blood urea nitrogen (BUN) and serum creatinine (Scr). The sections of kidneys were examined by an electric microscope, PAS staining, immunohistochemical staining and in situ hybridization histochemistry. The results showed that 24hUPER, BUN and Scr in DRB group were more than those in Sham group and UPHT group at the same time points, and there was a trend towards an increase on level of GSI in DRB group from week 2 to week 8. Electric microscopy revealed that podocyte injury presented in DRB group. The expression of Ang1 mRNA and protein in glomeruli of DRB group was decreased, while the expression of Ang2 protein in glomeruli of DRB group increased. Meanwhile, the expression of Ang1 mRNA had a negative correlation with the expression of Ang2 mRNA, and the expression of Ang1 protein had a positive correlation with the expression of Ang1 mRNA, and had a negative correlation with 24hUPER, BUN, Scr, glomerular sclerotic index (GSI), the expression of Ang2 protein and CoIV protein. The expression of Ang2 protein had a positive correlation with the expression of Ang2 mRNA, and had a positive correlation with 24hUPER, BUN, Scr, GSI, the expression of CoIV protein. It was concluded that podocyte injury might lead to an alteration in the expression of Ang1 and Ang2 within glomeruli. Ang2 may get rid of inhibition from Ang1 for downregulation of the Ang1 expression, which facilitate upregulation of the Ang2 expression in glomeruli to promote progressive glomerulosclerosis in the rats.

A protective role for programmed death 1 in progression of murine adriamycin nephropathy

Programmed death 1 (PD-1) is a novel member of the CD28/cytotoxic T-lymphocyte-associated protein-4 superfamily, which plays an important role in the regulation of activated T cells. However, it is not clear how PD-1 is expressed in normal and diseased kidney, nor if it has a role in progression of chronic renal disease. PD-1 expression and the effect of monoclonal anti-PD-1 antibody (Ab) were examined in murine adriamycin nephropathy (AN). BALB/c mice were divided into three groups: (a) normal mice, (b) adriamycin (ADR) with control immunoglobulin (Ig)G (ADR-IgG), and (c) ADR with anti-PD-1 Ab (ADR-Ab). AN was induced by a single intravenous injection of ADR. Anti-PD-1 Ab was given by intraperitoneal injection on alternate days from day 0 to day 10, or to day 18. Animals were killed at week 4. Renal function, histological change, and cytokine expression were examined. PD-1 mRNA was detected in kidney tissue of mice with AN in a dose- and time-dependent manner. PD-1 was mainly expressed on injured tubule cells and some interstitial cells, which co-stained with alpha-smooth muscle actin in AN, but not in normal kidney. Anti-PD-1 treatment up to day 18, but not to day 10, worsened glomerular and tubulointerstitial injury. The ratio of urinary protein/creatinine was significantly higher in ADR-Ab mice than ADR-IgG mice. The number of macrophages was significantly increased in ADR-Ab mice compared with ADR-IgG mice. Blockade of PD-1 worsened progressive renal histopathological and functional injury in murine AN. This suggests a possible protective role for PD-1 in chronic renal disease, and its potential as a treatment to slow disease progression.

Proliferating cells in HIV and pamidronate-associated collapsing focal segmental glomerulosclerosis are parietal epithelial cells

Collapsing focal segmental glomerulosclerosis (cFSGS) is characterized by hyperplasia of glomerular epithelial cells. In a mouse model of FSGS and in a patient with recurrent idiopathic FSGS, we identified the proliferating cells as parietal epithelial cells (PECs). In the present study, we have evaluated the origin of the proliferating cells in cFSGS associated with human immunodeficiency virus (HIV) and pamidronate. We performed a detailed study of glomerular lesions in biopsies of two patients with HIV-associated cFSGS and a nephrectomy specimen of a patient with pamidronate-associated cFSGS. Glomeruli were studied by serial sectioning using light and electron microscopy and immunohistochemistry to determine the epithelial cell phenotype. We used Synaptopodin, vascular endothelial growth factor, and CD10 as podocyte markers, CK8 and PAX2 as PEC markers and Ki-67 as marker of cell proliferation. The newly deposited extracellular matrix was characterized using antiheparan sulfate single-chain antibodies. The proliferating cells were negative for the podocyte markers, but stained positive for the PEC markers and the cell proliferation marker Ki-67. The proliferating PAX-2 and CK8 positive cells that covered the capillary tuft were always in continuity with PAX-2/CK8 positive cells lining Bowman's capsule. The matrix deposited by these proliferating cells stained identically to Bowman's capsule. Our study demonstrates that PECs proliferate in HIV and pamidronate-associated cFSGS. Our data do not support the concept of the proliferating, dedifferentiated podocyte.

Reduced podocyte expression of alpha3beta1 integrins and podocyte depletion in patients with primary focal segmental glomerulosclerosis and chronic PAN-treated rats

Integrins attach cells to extracellular matrix (ECM) and mediate signals from ECM to cells or from cells to ECM. They regulate cell functions, including adhesion, migration, cell cycle regulation, and differentiation. Podocytes may detach from the glomerular basement membrane (GBM) and be excreted in the urine, and proteinuria is found in patients with primary focal segmental glomerulosclerosis (FSGS); both may be associated with loss of alpha3beta1integrins. In this study, we have examined the podocyte number in patients with primary FSGS and normal controls, and the alpha3- and beta1-integrin subunits expression of podocytes in patients with primary FSGS and chronic puromycin aminonucleoside (PAN)-treated rats by the morphometric, immunoperoxidase histochemical, and immunoelectron microscopic examination. We also measured their expression serially in rats that received repeated PAN injection. The results showed that the podocyte number was significantly decreased in patients with primary FSGS than in normal control (P < 0.05). The immunostaining score showed that both alpha3- and beta1-integrin subunits on podocytes in patients with primary FSGS were significantly lower than in normal controls (both P < 0.01). The number of immuno-gold particles of alpha3- and beta1-integrins at the effaced foot process area of patients with primary FSGS were also significantly decreased than that of normal controls (both P < 0.05). The immunostaining score of both alpha3- and beta1-integrin subunits was negatively correlated with the degree of glomerular sclerosing score and the amount of daily protein loss, and they were positively correlated with the number of podocytes. Chronic 12-week PAN-treated rats showed similar findings with decreased immunostaining expression and immuno-gold particles of alpha3-integrin on podocytes than in normal control (both P < 0.05). The chronic PAN-treated rats also showed a trend toward gradually decreased immunostaining expression of alpha3-integrin subunit on podocyte during the progress from normal to FSGS state. These studies indicate that podocyte expression of alpha3- and beta1-integrin subunits is significantly reduced in humans with primary FSGS and chronic PAN-treated rats, before the morphological changes of FSGS are observed. The decreased podocyte expression of alpha3beta1 integrins is closely related with podocyte depletion, glomerular sclerosis, and daily protein loss in patients with primary FSGS.

Changes in angiopoietin expression in glomeruli involved in glomerulosclerosis in rats with daunorubicin-induced nephrosis

AIM

To study the potential pathological role of endogenous angiopoietins in daunorubicin-induced progressive glomerulosclerosis in rats.

METHODS

Seventy male Wistar rats were allocated randomly into a daunorubicin group (DRB; n=40) or a control group (n=30). The rats in the DRB group were injected with DRB (15 mg/kg), in their tails. Subsequently, at intervals of 1, 2, 4, 6, 8, and 12 weeks, 5 male Wistar rats in each group were chosen randomly for 24 h urinary protein quantitative measurements (24 h UPQM), and determination of plasma tumor necrosis factor alpha (TNF-alpha), angiopoietin-1 (Ang1), and angiopoietin-2 (Ang2) levels. Kidney sections were examined by electron microscopy, Periodic Acid Schiff (PAS) staining, immunohistochemical staining and in situ hybridization histochemistry.

RESULTS

As glomerulosclerosis progressed in the DRB group, expression of Ang1 mRNA and protein in glomeruli decreased and expression of TNF-alpha protein, Ang2 mRNA and protein in glomeruli increased. Expression of Ang1 mRNA and protein in glomeruli were negatively correlated with 24 h UPQM, Fn protein expression, and mean area of extracellular matrix (MAECM). In comparison, expression of Ang2 mRNA and protein in glomeruli were positively correlated with 24 h UPQM, Fn protein expression and MAECM; furthermore, there was a positive correlation between plasma Ang2 and 24 h UPQM. Plasma TNF-alpha and expression of TNF-alpha in glomeruli were positively correlated with expression of Ang2 mRNA and protein in glomeruli. There was a negative correlation between Ang1 protein expression and Ang2 protein expression in glomeruli.

CONCLUSION

During DRB-induced glomerulosclerosis, podocyte injury led to a shift in the balance of Ang1 and Ang2 in glomeruli. Increased TNF-alpha in plasma and glomeruli may upregulate Ang2 expression in glomeruli. Elevated Ang2 in both plasma and glomeruli may mediate protein permeability through the glomerular filtration barrier. Moreover, local expression of Ang2 may facilitate the progress of glomerulosclerosis by upregulating a component expression of extracellular matrix.