Adriamycin-induced Focal Segmental Glomerulosclerosis Research Articles

Colony stimulating factor-1 receptor drives glomerular parietal epithelial cell activation in focal segmental glomerulosclerosis

Parietal epithelial cells (PECs) are kidney progenitor cells with similarities to a bone marrow stem cell niche. In focal segmental glomerulosclerosis (FSGS) PECs become activated and contribute to extracellular matrix deposition. Colony stimulating factor-1 (CSF-1), a hematopoietic growth factor, acts via its specific receptor, CSF-1R, and has been implicated in several glomerular diseases, although its role on PEC activation is unknown. Here, we found that CSF-1R was upregulated in PECs and podocytes in biopsies from patients with FSGS. Through invitro studies, PECs were found to constitutively express CSF-1R. Incubation with CSF-1 induced CSF-1R upregulation and significant transcriptional regulation of genes involved in pathways associated with PEC activation. Specifically, CSF-1/CSF-1R activated the ERK1/2 signaling pathway and upregulated CD44 in PECs, while both ERK and CSF-1R inhibitors reduced CD44 expression. Functional studies showed that CSF-1 induced PEC proliferation and migration, while reducing the differentiation of PECs into podocytes. These results were validated in the Adriamycin-induced FSGS experimental mouse model. Importantly, treatment with either the CSF-1R-specific inhibitor GW2580 or Ki20227 provided a robust therapeutic effect. Thus, we provide evidence of the role of the CSF-1/CSF-1R pathway in PEC activation in FSGS, paving the way for future clinical studies investigating the therapeutic effect of CSF-1R inhibitors on patients with FSGS.

Synergism of calycosin and bone marrow-derived mesenchymal stem cells to combat podocyte apoptosis to alleviate adriamycin-induced focal segmental glomerulosclerosis.

Bone marrow-derived mesenchymal stem cells (MSCs) show podocyte-protective effects in chronic kidney disease. Calycosin (CA), a phytoestrogen, is isolated from Astragalus membranaceus with a kidney-tonifying effect. CA preconditioning enhances the protective effect of MSCs against renal fibrosis in mice with unilateral ureteral occlusion. However, the protective effect and underlying mechanism of CA-pretreated MSCs (MSCsCA) on podocytes in adriamycin (ADR)-induced focal segmental glomerulosclerosis (FSGS) mice remain unclear. To investigate whether CA enhances the role of MSCs in protecting against podocyte injury induced by ADR and the possible mechanism involved. ADR was used to induce FSGS in mice, and MSCs, CA, or MSCsCA were administered to mice. Their protective effect and possible mechanism of action on podocytes were observed by Western blot, immunohistochemistry, immunofluorescence, and real-time polymerase chain reaction. In vitro, ADR was used to stimulate mouse podocytes (MPC5) to induce injury, and the supernatants from MSC-, CA-, or MSCsCA-treated cells were collected to observe their protective effects on podocytes. Subsequently, the apoptosis of podocytes was detected in vivo and in vitro by Western blot, TUNEL assay, and immunofluorescence. Overexpression of Smad3, which is involved in apoptosis, was then induced to evaluate whether the MSCsCA-mediated podocyte protective effect is associated with Smad3 inhibition in MPC5 cells. CA-pretreated MSCs enhanced the protective effect of MSCs against podocyte injury and the ability to inhibit podocyte apoptosis in ADR-induced FSGS mice and MPC5 cells. Expression of p-Smad3 was upregulated in mice with ADR-induced FSGS and MPC5 cells, which was reversed by MSCCA treatment more significantly than by MSCs or CA alone. When Smad3 was overexpressed in MPC5 cells, MSCsCA could not fulfill their potential to inhibit podocyte apoptosis. MSCsCA enhance the protection of MSCs against ADR-induced podocyte apoptosis. The underlying mechanism may be related to MSCsCA-targeted inhibition of p-Smad3 in podocytes.

Synthesis and structural characterization of xylan acetate ester and its antinephritic effects in rats with experimental chronic kidney disease

Acetic acid has been shown to be effective in chronic kidney disease (CKD). However, it is a low-molecular-weight compound that allows it to be absorbed in the upper digestive tract so that it cannot function in colon. To overcome these deficiencies, an acetate-releasing xylan derivative, xylan acetate ester (XylA), was synthesized and selected in this study for its potential in the treatment of CKD. IR, NMR and HPGPC were used to characterize the structure of XylA and its antinephritic effects was evaluated in vivo. The results showed that acetate was successfully grafted onto the C-2 and C-3 positions of xylan and with a molecular weight at 69157 Da. XylA treatments could relieve the symptoms of CKD in an adenine-induced chronic renal failure (CRF) model and an adriamycin-induced focal segmental glomerulosclerosis (FSGS) model in SD rats. Further study indicated that XylA could upregulate the short-chain fatty acids (SCFAs) in vitro and vivo. Nevertheless, the relative abundance of Phascolarctobacterium in colon was increased after XylA treatment. XylA could upregulate G-protein-coupled receptor 41 (GPR41) expression, inhibit glomerular cell apoptosis and promoting proliferation. Our study expands the application of xylan and provides a new idea for the treatment of CKD with acetic acid.

MicroRNA-155-5p Aggravates Adriamycin-Induced Focal Segmental Glomerulosclerosis through Targeting Nrf2

Introduction: Focal segmental glomerulosclerosis (FSGS) is characterized by focal and segmental obliteration of glomerular capillary tufts with increased matrix and usually associated with nephrotic range proteinuria. FSGS is a huge burden to society; however, the mechanisms remain unclear and treatment is still lacking. Methods: Adriamycin nephropathy was induced by Adriamycin injection and some mice were also injected with Anti-miR-155-5p LNA or YC-1 (a pharmacological inhibitor of HIF-1). At 6 weeks, the mice were sacrificed, and kidneys, blood and urine samples were collected for further analysis. Results: We demonstrated a significant increase of miR-155-5p in kidney tissues in Adriamycin-induced FSGS mouse models. We also found Adriamycin treatment led to the activation of HIF-1, and inhibition of HIF-1 using YC-1 partly prevented the induction of miR-155-5p. Functionally, anti-miR-155-5p attenuated kidney injury and delayed the progression of renal fibrosis. Further, anti-miR-155-5p also enhanced the expression of Nrf2 following Adriamycin treatment. Further, our luciferase microRNA target reporter assay verified Nrf2 as a direct target of miR-155-5p. Our further results indicated anti-miR-155-5p could suppress kidney oxidative stress and inflammation, also supporting Nrf2 was the direct target of miR-155-5p. Finally, we also found miR-155-5p did not increase in serum but significantly increased in urine, indicating urinary miR-155-5p may be useful for FSGS diagnosis. Conclusion: This study identified a HIF-1/miR-155-5p/Nrf2 axis which can promote kidney oxidative stress and inflammation, finally aggravating kidney injury and accelerating the progression of renal fibrosis in FSGS. Moreover, the increase in urinary miR-155-5p may be useful for the diagnosis of FSGS.

Blocking ribosomal protein S6 phosphorylation inhibits podocyte hypertrophy and focal segmental glomerulosclerosis

Ribosomal protein S6 (rpS6) phosphorylation mediates the hypertrophic growth of kidney proximal tubule cells. However, the role of rpS6 phosphorylation in podocyte hypertrophy and podocyte loss during the pathogenesis of focal segmental glomerulosclerosis (FSGS) remains undefined. Here, we examined rpS6 phosphorylation levels in kidney biopsy specimens from patients with FSGS and in podocytes from mouse kidneys with Adriamycin-induced FSGS. Using genetic and pharmacologic approaches in the mouse model of FSGS, we investigated the role of rpS6 phosphorylation in podocyte hypertrophy and loss during development and progression of FSGS. Phosphorylated rpS6 was found to be markedly increased in the podocytes of patients with FSGS and Adriamycin-induced FSGS mice. Genetic deletion of the Tuberous sclerosis 1 gene in kidney glomerular podocytes activated mammalian target of rapamycin complex 1 signaling to rpS6 phosphorylation, resulting in podocyte hypertrophy and pathologic features similar to those of patients with FSGS including podocyte loss, leading to segmental glomerulosclerosis. Since protein phosphatase 1 is known to negatively regulate rpS6 phosphorylation, treatment with an inhibitor increased phospho-rpS6 levels, promoted podocyte hypertrophy and exacerbated formation of FSGS lesions. Importantly, blocking rpS6 phosphorylation (either by generating congenic rpS6 knock-in mice expressing non-phosphorylatable rpS6 or by inhibiting ribosomal protein S6 kinase 1-mediated rpS6 phosphorylation with an inhibitor) significantly blunted podocyte hypertrophy, inhibited podocyte loss, and attenuated formation of FSGS lesions. Thus, our study provides genetic and pharmacologic evidence indicating that specifically targeting rpS6 phosphorylation can attenuate the development of FSGS lesions by inhibiting podocyte hypertrophy and associated podocyte depletion.

Nuclear exclusion of YAP exacerbates podocyte apoptosis and disease progression in Adriamycin-induced focal segmental glomerulosclerosis

AbstractFocal segmental glomerulosclerosis (FSGS) is a chronic glomerular disease with poor clinical outcomes. Podocyte loss via apoptosis is one important mechanism underlying the pathogenesis of FSGS. Recently, Yes-associated-protein (YAP), a key downstream protein in the Hippo pathway, was identified as an activator for multiple gene transcriptional factors in the nucleus to control cell proliferation and apoptosis. To investigate the potential role of YAP in the progression of FSGS, we examined kidney samples from patients with minimal change disease or FSGS and found that increases in podocyte apoptosis is positively correlated with the cytoplasmic distribution of YAP in human FSGS. Utilizing an established mT/mG transgenic mouse model and primary cultured podocytes, we found that YAP was distributed uniformly in nucleus and cytoplasm in the podocytes of control animals. Adriamycin treatment induced gradual nuclear exclusion of YAP with enhanced phospho-YAP/YAP ratio, accompanied by the induction of podocyte apoptosis both in vivo and in vitro. Moreover, we used verteporfin to treat an Adriamycin-induced FSGS mouse model, and found YAP inhibition by verteporfin induced nuclear exclusion of YAP, thus increasing podocyte apoptosis and accelerating disease progression. Therefore, our findings suggest that YAP nuclear distribution and activation in podocytes is an important endogenous anti-apoptotic mechanism during the progression of FSGS.An increase in podocyte apoptosis is positively correlated with the cytoplasmic distribution of YAP in focal segmental glomerulosclerosis (FSGS). YAP inhibition by verteporfin induces nuclear exclusion of YAP, thus increasing the podocyte apoptosis and accelerating disease progression. Therefore, this study suggests that YAP activation and nuclear distribution in podocytes is an endogenous anti-apoptotic mechanism during the progression of FSGS.

Baicalin alleviates adriamycin-induced focal segmental glomerulosclerosis and proteinuria by inhibiting the Notch1-Snail axis mediated podocyte EMT

Podocyte injury is an early event and core in the development of focal segmental glomerular sclerosis (FSGS) that induces poor prognosis. Epithelial-mesenchymal transition (EMT) as a response of podocyte to injury leads to podocyte depletion and proteinuria. The abnormally reactivated NOTCH pathway may be involved in podocyte EMT. Baicalin, as a natural flavonoid compound, had significant inhibitory activity on tissue fibrosis and tumor cell invasion. However, its potential role and molecular mechanisms to injured podocyte in FSGS are little known. Here we found that baicalin could inhibit podocyte EMT markers expression and cell migration induced by TGF-β1, accompanied by the up-regulated expression of slit diaphragm (SD) proteins and cell-cell adhesion molecule. Further investigation revealed that EMT inhibition of baicalin on injured podocyte is mainly mediated by the reduction of notch1 activation and its downstream Snail expression. Using the adriamycin-induced FSGS model, we determined that baicalin suppresses the Notch1-Snail axis activation in podocytes, relieves glomerulus structural disruption and dysfunction, and reduces proteinuria. Altogether, these findings suggest that baicalin is a novel renoprotective agent against podocyte EMT in FSGS and indicate its underlying mechanism that involves in negative regulation of the Notch1-Snail axis.

SO076EVOLOCUMAB HAS THERAPEUTIC EFFECTS ON EXPERIMENTAL MODEL OF FSGS

Abstract Background and Aims Proprotein convertase subtilisin/kexin type 9 (PCSK9), which accelerates LDL-receptor degradation, plays a central role in dyslipidemia in nephrotic syndrome (NS). Intracellular LDL-C accumulation is supposed to damage podocytes through oxidative stress, foam cell formation, and apoptosis. In the present study, we investigate the effects of evolocumab (EVO), which is anti-PCSK9 monoclonal antibody, on a murine model of adriamycin-induced focal segmental glomerulosclerosis (FSGS) with NS in order to clarify the potential of EVO as a therapeutic agent in FSGS. Method Male BALB/c mice aged 9 to 11 weeks were divided into vehicle and intervention groups. The mice underwent subcutaneous injection of normal saline (FSGS-Vehicle group) or EVO (30 mg/kg) (FSGS-EVO group) and immediately after that, they were administered adriamycin (11.5 mg/kg) from tail vein. All mice were sacrificed on Day 14, and then morphological and functional analyses were performed. Results EVO treatment significantly reduced serum levels of LDL-C (mg/dl, 305.3±77.1 vs. 159.1±31.7, p<0.01) and PCSK9 (ng/ml, 652.9±230.0 vs 311±116.5, p<0.001). In addition, EVO treatment significantly improved renal function, including albuminuria (albumin/creatinine (Cr), 15.73±1.26 vs. 7.32±1.02, p<0.001), serum Cr (mg/dl, 0.48±0.13 vs. 0.18±0.044, p<0.001) and BUN (mg/dl, 80.08±20.22 vs. 46.86±9.60, p<0.05). Compatibly with the clinical data, the severity of glomerulosclerosis score (semi-quantification, 2.44 vs. 1.95, p<0.001) was ameliorated and podocyte density (number of podocyte/glomerulus, 2.61 vs. 7.54, p<0.001) was maintained in the FSGS-EVO mice compared with the FSGS-Vehicle mice. Conclusion Our findings provided novel insights into the protective effects of EVO on adriamycin nephropathy, indicating EVO as a potent therapeutic agent for FSGS.

Transcription factor MafB in podocytes protects against the development of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a common cause of steroid-resistant nephrotic syndrome. Spontaneous remission of FSGS is rare and steroid-resistant FSGS frequently progresses to renal failure. Many inheritable forms of FSGS have been described, caused by mutations in proteins that are important for podocyte function. Here, we show that a basic leucine zipper transcription factor, MafB, protects against FSGS. MAFB expression was found to be decreased in the podocytes of patients with FSGS. Moreover, conditional podocyte-specific MafB-knockout mice developed FSGS with massive proteinuria accompanied by depletion of the slit diaphragm-related proteins (Nphs1 and Magi2), and the podocyte-specific transcription factor Tcf21. These findings indicate that MafB plays a crucial role in the pathogenesis of FSGS. Consistent with this, adriamycin-induced FSGS and attendant proteinuria were ameliorated by MafB overexpression in the podocytes of MafB podocyte-specific transgenic mice. Thus, MafB could be a new therapeutic target for FSGS.

MiR-150 inhibitor ameliorates adriamycin-induced focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is the most common cause of adult nephrotic syndrome in USA. Its mechanisms remain unclear and the effective treatment lacks. We previously reported that upregulation of microRNA (miR)-150 in human podocytes increases profibrotic proteins and decreases anti-fibrotic suppressor of cytokine signaling 1 (SOCS1). We aimed to clarify whether miR-150 inhibitor can ameliorate glomerular injury and to identify its corresponding mechanisms in adriamycin-induced FSGS mice. We found that renal miR-150 increased in adriamycin-induced FSGS mice and FAM-labeled locked nucleic acid-anti-miR-150 (LNA-anti-miR-150) was absorbed by the animal kidneys 6 h after subcutaneous injection. The administration of LNA-anti-miR-150 (2 mg/kg BW twice weekly for 6 w) inhibited renal miR-150 levels without systemic toxicity. With renal miR-150 inhibition, proteinuria, hypoalbuminemia, and hyperlipemia were ameliorated in FSGS mice compared to the scrambled LNA. Meanwhile, the elevated profibrotic proteins and proinflammatory cytokines, decreased antifibrotic SOCS1, and the filtration of T cells in FSGS mice were reverted by LNA-anti-miR-150. Finally, we found that miR-150 most located on podocytes in renal biopsies of FSGS patients. We conclude that LNA-anti-miR-150 might be a novel promising therapeutic agent for FSGS. The renal protective mechanisms might be mediated by anti-fibrosis and anti-inflammation as well as reducing infiltration of T cells in the kidney.

C–C chemokine receptor type 2 mediates glomerular injury and interstitial fibrosis in focal segmental glomerulosclerosis

Glomerulosclerosis and tubulointerstitial fibrosis are hallmarks of chronic kidney injury leading to end-stage renal disease. Inflammatory mechanisms contribute to glomerular and interstitial scarring, including chemokine-mediated recruitment of leucocytes. In particular, accumulation of C-C chemokine receptor type 2 (CCR2)-expressing macrophages promotes renal injury and fibrotic remodelling in diseases like glomerulonephritis and diabetic nephropathy. The functional role of CCR2 in the initiation and progression of primary glomerulosclerosis induced by podocyte injury remains to be characterized. We analysed glomerular expression of CCR2 and its chemokine ligand C-C motif chemokine ligand 2 (CCL2) in human focal segmental glomerulosclerosis (FSGS). Additionally, CCL2 expression was determined in stimulated murine glomeruli and glomerular cells in vitro. To explore pro-inflammatory and profibrotic functions of CCR2 we induced adriamycin nephropathy, a murine model of FSGS, in BALB/c wild-type and Ccr2-deficient mice. Glomerular expression of CCR2 and CCL2 significantly increased in human FSGS. In adriamycin-induced FSGS, progressive glomerular scarring and reduced glomerular nephrin expression was paralleled by induced glomerular expression of CCL2. Adriamycin exposure stimulated secretion of CCL2 and tumour necrosis factor-α (TNF) in isolated glomeruli and mesangial cells and CCL2 in parietal epithelial cells. In addition, TNF induced CCL2 expression in all glomerular cell populations, most prominently in podocytes. In vivo, Ccr2-deficient mice with adriamycin nephropathy showed reduced injury, macrophage and fibrocyte infiltration and inflammation in glomeruli and the tubulointerstitium. Importantly, glomerulosclerosis and tubulointerstitial fibrosis were significantly ameliorated. Our data indicate that CCR2 is an important mediator of glomerular injury and progression of FSGS. CCR2- targeting therapies may represent a novel approach for its treatment.

Resveratrol Attenuates Adriamycin-Induced Focal Segmental Glomerulosclerosis through C3aR/C5aR- Sphingosine Kinase 1 Pathway

Background/Aim: Focal segmental glomerulosclerosis (FSGS) typically presents with nephrotic range proteinuria, which could eventually develop into end-stage renal disease. Resveratrol (RSV) is a natural polyphenol compound, which has been reported to suppress inflammatory response and renal interstitial fibrosis. This study is aimed at evaluating the renoprotective effect of RSV treatment on adriamycin-induced FSGS. Methods: In Balb/c mice, adriamycin nephropathy was induced by adriamycin (10 mg/kg body weight, diluted in normal saline) via a tail vein on day 0. Then the mice were treated with RSV (40 mg/kg body weight) once daily by oral gavage, again starting on the day of adriamycin injection and continued for 6 weeks. At 6 weeks, the mice were sacrificed; kidneys and blood samples were collected for further analysis. Results: When treated with adriamycin, the expressions of C3aR, C5aR, sphingosine kinase 1 (Sphk1), and soluble urokinase-type plasminogen activator receptor (suPAR) were upregulated, while RSV treatment could inhibit the expressions of C3aR, C5aR, Sphk1, and suPAR, eventually leading to anti-inflammatory and anti-fibrosis conditions. Conclusion: RSV attenuates adriamycin-induced FSGS through C3aR/C5aR-Sphk1 pathway.

Astaxanthin Attenuates Adriamycin-Induced Focal Segmental Glomerulosclerosis

Background/Aim: Focal segmental glomerulosclerosis (FSGS) is a specific pattern of chronic renal injury with progressive glomerular scarring. The phenotypic alterations that contribute to FSGS include inflammatory response and oxidative stress. Astaxanthin (ATX) has a broad range of biological functions, particularly antioxidant and anti-inflammatory ones. This study was designed to evaluate the renoprotective effect of ATX treatment on Adriamycin-induced FSGS. Methods: In Balb/c mice, Adriamycin nephropathy was induced by Adriamycin (10 mg/kg body weight, diluted in normal saline) via a tail vein on day 0. Then the mice were treated with ATX (50 mg/kg body weight) once daily by oral gavage, again starting on the day of Adriamycin injection and continued for 6 weeks. At 6 weeks, the mice were sacrificed; kidneys and blood samples were collected for further analysis. Results: Animals that underwent intermittent exposure to ATX treatment exhibited significant improvements in renal functional parameters as well as in glomerular and interstitial fibrosis compared to those undergoing saline treatment in FSGS mouse models. ATX treatment exerted anti-inflammatory and antioxidant effects by promoting Nrf2 expression and suppressing renal nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome activation. Conclusion: ATX might offer a ray of hope for ameliorating FSGS.

Thiazolidinedione attenuate proteinuria and glomerulosclerosis in Adriamycin‐induced nephropathy rats via slit diaphragm protection

The slit diaphragm (SD) of podocyte impairment contributes to massive proteinuria and progressive glomerulosclerosis in many human glomerular diseases. The aim of the study was to determine if thiazolidinedione (TZD) reduce proteinuria and glomerulosclerosis in focal segmental glomerulosclerosis (FSGS) by preserving the structure and function of SD. Adriamycin-induced FSGS rat models were employed. Urinary protein content was measured dynamically during the experiment. Additional biochemical parameters in serum samples were measured after the animals were killed. Glomerular sclerosis index (SI) and podocyte foot processes fusion rate (PFR) were evaluated. The protein and mRNA expressing levels of nephrin, podocin and CD2-associated protein (CD2AP) in glomeruli were assessed by immunohistochemistry and real-time quantitative polymerase chain reaction, respectively. The density of podocytes was also evaluated after anti-Wilms' tumour-1 immunohistochemical staining. Rosiglitazone treatment partially reduced proteinuria, but did not significantly affect the serum levels of triglyceride, cholesterol, albumin, glucose, urea nitrogen and creatinine in Adriamycin-induced FSGS rats. Glomerular SI and podocyte foot PFR were significantly attenuated by rosiglitazone treatment. Rosiglitazone prevented the reduction of nephrin, podocin and CD2AP protein expression induced by Adriamycin, however, the mRNA expression levels of these SD-related markers did not change significantly. Rosiglitazone therapy did not reverse Adriamycin-mediated reduction of the density of podocytes. The study data suggest that TZD are promising therapeutic agents on FSGS, and the mechanism may be mediated in part by directly protecting the structure and function of SD.

CCR1 blockade reduces interstitial inflammation and fibrosis in mice with glomerulosclerosis and nephrotic syndrome

CC chemokines mediate leukocyte infiltration into inflamed tissue. We have recently shown that blockade of the CC chemokine receptor CCR1 reduces interstitial inflammation and fibrosis in murine obstructive nephropathy. However, it is not known whether CCR 1 blockade is protective in progressive renal injury associated with severe proteinuria. We therefore studied the effect of the small-molecule CCR1 antagonist BX471 in a murine model of adriamycin-induced focal segmental glomerulosclerosis (FSGS) with nephrotic syndrome and progressive interstitial inflammation and fibrosis. Adriamycin nephropathy with persistent proteinuria was induced in male BALB/c mice by two intravenous injections of adriamycin (13 mg/kg) at day 0 and 14. BX471 treatment was started at day 14 when proteinuria and interstitial inflammation had developed. At 6 weeks, renal histology was studied by morphometry and immunohistochemistry. At week 6, adriamycin-treated mice showed FSGS, associated with tubulointerstitial injury consisting of tubular dilation and atrophy, interstitial leukocyte infiltration, and fibrosis. The mRNA expression of CCR1 and CC chemokines, including the CCR1 ligands CCL3 (MIP-1alpha) and CCL5 (RANTES), was up-regulated in diseased kidneys, with a prominent interstitial expression of CCL5. Compared to vehicle-treated controls BX471 significantly reduced the amount of macrophages and T lymphocytes in interstitial lesions by 51% and 22%, respectively. Markers of renal fibrosis such as interstitial fibroblasts (48%) and interstitial volume (23%) were significantly reduced by BX471 treatment. In contrast, the extent of proteinuria and glomerular sclerosis was not affected by BX471 treatment. Blockade of CCR1 substantially reduced interstitial leukocyte accumulation and the subsequent renal fibrosis in a murine model of nephrotic syndrome and FSGS. These findings support a role for CCR1 in interstitial leukocyte recruitment and suggest that CCR1 blockade might be a new therapeutic strategy in progressive nephropathies such as FSGS.