Increase In Glomerulosclerosis Research Articles

#2584 Mapping Progression of DKD in ReninAAV UNx db/db mice utilizing time-series RNA sequencing

Abstract Background and Aims The Renin adeno-associated virus (AAV) uninephrectomized (UNx) db/db mouse model of diabetic kidney disease (DKD) recapitulates hallmarks of DKD with hypertension, including albuminuria and glomerulosclerosis. Despite previous characterization of the model, gaps persist in our understanding regarding temporal patterns of gene expression and pathophysiology in the glomeruli. This longitudinal study characterizes isolated glomeruli from ReninAAV UNx db/db mice during progression of DKD with hypertension. Method Female db/db (BKS.Cg-Dock7m +/+ Leprdb/J) received a single i.v. dose of LacZAAV (control) or ReninAAV. Untreated db/m mice (BKS.Cg-Dock7m +/+ Leprdb/J) served as healthy controls. One week after AAV injection, ReninAAV mice underwent UNx, recovered for three weeks, and were subsequently randomized and stratified into 4 groups according to fed blood glucose and body weight. ReninAAV UNx mice were terminated at 4, 8, 12 and 16 weeks (w4-w16) after UNx. Control groups were terminated at 16 weeks. Endpoints included urine and plasma biochemistry, kidney histology (i.e. Collagen 1a1 and Glomerulosclerosis) and RNA sequencing of glomeruli isolated by laser capture microdissection. Results ReninAAV UNx db/db mice showed progressive kidney fibrosis (Col1a1%-area) and albuminuria (uACR) compared to LacZAAV db/db and db/m mice across all timepoints investigated. Furthermore, a significant increase in glomerulosclerosis was observed from w12 and onwards compared to LacZAAV and db/m mice. When compared to LacZAAV mice, more than 1,700 glomerular differentially regulated genes and more than 250 uniquely regulated genes were found at each timepoint, including markers of fibrosis, inflammation and glomerular injury. Several glomerular drug targets exhibited time-specific regulated in ReninAAV UNx db/db mice (e.g. Slc5a2, Egfr, Agtr1a). Regulated genes were segmented into nine clusters with distinct temporal patterns. Among these, a continuous increase in expression of genes associated with extracellular matrix (ECM), small molecule transport and temporal stimulation of metabolic pathways. Finally, a correlation analysis revealed strong associations between ECM and ECM-related pathways vs. glomerulosclerosis and albuminuria. Conclusion The ReninAAV UNx db/db mouse model of hypertensive DKD demonstrates a progressive increase in fibrosis and albuminuria paralleled by dynamic changes in glomerular gene expression signatures. Notably, the identification of temporal patterns of gene expression and pathway regulation provides novel insights into DKD pathophysiology and progression. This underscores the ReninAAV UNx db/db mouse as an applicable model of human DKD in preclinical target and drug discovery.

Modeling the Progression of Hypertensive Kidney Disease in African Americans

Chronic kidney disease (CKD) is associated with the progressive functional loss of nephrons and hypertension (HTN). Several clinical studies demonstrate calcium channel blocker (CCB) therapy mitigates the decline in renal function in humans with essential HTN, but there are few long‐term clinical studies that determine the impact of CCBs in patients with hypertensive CKD. African Americans (AA) have a faster progression to end stage renal disease as compared to the white population which may be partially explained by factors such as salt‐sensitive blood pressure (BP) and greater prevalence of uncontrolled HTN. Observational studies demonstrate BP to be a strong independent risk factor for CKD progression, yet intense BP lowering in AA does not diminish the renal function decline any more than standard therapy. The African American Study of Kidney Disease and Hypertension (AASK) trial suggests AA with proteinuric CKD may have detrimental responses to CCB as compared to an angiotensin converting enzyme (ACE) inhibitor. Therefore, using a large physiological model, we set out to replicate the AASK trial findings and predict the roles of the renin‐angiotensin system, salt intake, and intensive antihypertensive therapy in a virtual population during CCB therapy. Our current mathematical model, HumMod, is a large physiological simulator that is comprised of key systems that play an integral role in BP control such as neural, endocrine, circulatory, and renal systems. All of the parameters (n=335) that control these systems were randomly varied and resulted in over 3,000 unique models that we define as a virtual population. We calibrated this virtual population to patient level data from the AASK trial (BP and glomerular filtration rate [GFR] before and after 3 years of amlodipine). After matching the virtual population to individual level data, the virtual population (n=140) was associated with statistically similar BP and GFR before and after CCB therapy (Figure) as well as similar increases in glomerular damage. Baseline factors such as elevated single nephron GFR and increased tubuloglomerular feedback were correlated with greater declines in renal function and increased glomerulosclerosis after 3 years of CCB. Interestingly, when looking at the models with severe CKD (<35 mL/min), glomerulosclerosis and angiotensin II significantly increased with CCB despite significant falls in mean BP (‐7 ± 7 mmHg). Adding an ACE inhibitor decreased angiotensin II levels and abrogated the increase in glomerulosclerosis while further decreasing BP (‐12 ± 9 mmHg). Decreasing salt intake in addition to the CCB+ACE inhibitor therapy further benefited systemic and glomerular pressures but significantly decreased overall GFR independent of any glomerular damage. Finally, all antihypertensive therapies were associated with significant decreases in left ventricular mass. These data suggest the current clinical markers of renal function such as eGFR may not fully reflect the actual progression of CKD, especially with intensive antihypertensive treatment. Our simulation also supports that angiotensin system inhibitors are renoprotective and cardioprotective when combined with CCB therapy in African American CKD patients.

What is the value of repeat kidney biopsies in patients with lupus nephritis?

Recent studies with protocol biopsies have shown a mismatch between clinical and histological remission in lupus nephritis (LN). We aimed to evaluate histological changes in repeat kidney biopsies by clinical indication in patients with LN. We analyzed 107 patients with LN in which a kidney biopsy was performed between 2008 and 2018. Of those, we included 26 (24.2%) who had ≥2 kidney biopsies. Classification was done according to the International Society of Nephrology/Renal Pathology Society. Mean time between biopsies was 71.5 ± 10.7 months. 73.1% of patients presented a change of class at repeat biopsy; 38.4% to a higher class and 34.6% to a lower class. A significant increase in glomerulosclerosis (% GS) (3.8% vs 18.7%, p = 0.006), interstitial fibrosis (3.8% vs 26.9%, p = 0.021), tubular atrophy (15.4% vs 57.7%, p = 0.001) and chronicity index (CI) (1 vs 3, p < 0.001) was observed at repeat biopsy. Subjects who developed chronic kidney disease progression had a lower rate of complete remission at 12 months (0% vs 37.5%, p = 0.02), higher % GS at first biopsy (7.9% vs 1.2%, p = 0.02) and higher CI (4 vs 2, p = 0.006), tubular atrophy (90% vs 37.6%, p = 0.008), interstitial fibrosis (50% vs 12.5%, p = 0.036) and vascular lesions (60% vs 18.8%, p = 0.031) at second biopsy. Our major finding was that patients with LN showed a significant increase in % GS, interstitial fibrosis, tubular atrophy and vascular lesions in repeat biopsies performed by clinical indication. This suggest that a second kidney biopsy may provide valuable and useful information regarding kidney disease progression.

P0990RENINAAV DOSE-DEPENDENTLY EXACERBATE ALBUMINURIA AND GLOMERULOSCLEROSIS, AND REDUCE GFR IN FEMALE UNINEPHRECTOMIZED DB/DB MICE

Abstract Background and Aims Diabetic nephropathy (DN) is a long-term complication that occurs in ∼40% of diabetes patients and is a leading cause of end-stage renal disease. Despite recent emergence of SGLT2 inhibitors and GLP-1 receptor agonists for nephroprotection in diabetes patients, drug discovery has been halted by the lack of reliable rodent models exhibiting features of human DN. In a newly established mouse model of progressive DN, we investigate the effects of hypertension on kidney injury. Method Female db/db mice were uninephrectomized (UNx) at 8 weeks of age and injected i.v. with a Renin adeno-associated virus (AAV) construct at different doses to induce hypertension, while a LacZAAV construct was used as negative control. db/+ mice served as healthy controls. Hypertension was measured by tail cuff and glomerular filtration rate (GFR) transcutaneous recoding of FITC-sinistrin after i.v. bolus injection at 22 weeks of age. Urine ACR measured in spot urine samples collected before termination 24 weeks of age. Terminal kidney samples were collected for 3D image analyses, histopathological evaluation, and next generation sequencing for gene expression analyses. Results GFR measurements indicated hyperfiltration in all AAV-injected UNx db/db mice compared to db/+ mice, while ReninAAV tended to dose-dependently decrease GFR compared to LacZAAV in UNx db/db mice. Urine ACR was worsened by ReninAAV-induced hypertension compared to LacZAAV controls. Automized AI-based glomerulosclerosis scoring showed ReninAAV dose-dependent increases in glomerulosclerosis compared to LacZAAV controls. 3D kidney imaging demonstrated increased glomerular volume in LacZAAV UNx db/db mice compared to db/+ mice with no further effect in ReninAAV groups. RNA sequencing revealed upregulated gene expression markers of fibrogenesis (incl. Col1a1, Col3, Col4, Fn1, Lamc2 and Vim) and tubular injury markers (Ngal and Kim-1), as well as downregulation of proximal tubular markers (Megalin and Aqp1) in ReninAAV UNx db/db mice compare to LacZAAV controls. Conclusion ReninAAV-induced hypertension in female UNx db/db mice accelerates kidney injury in uninephrectomized db/db mice and aggravates GFR, albuminuria and glomerulosclerosis in parallel with increased expression of genes associated with tubular injury renal fibrosis. Together, these data confirm that ReninAAV UNx db/db mice is a reliable model of DN with features of late stage human disease.

483-P: Key Biochemical and Histopathological Markers of Diabetic Nephropathy Correlate with Hypertension in the Renin-AAV Uninephrectomized db/db Mouse Model

Introduction: Diabetic nephropathy (DN) is a long-term complication that occurs in ∼40% of diabetes patients and is a leading cause of end-stage renal disease. In a newly established mouse model of progressive DN, we investigated the effects of hypertension on kidney injury. Methods: Female db/db mice were uninephrectomized (UNx) at 8 weeks of age and injected i.v. with a Renin adeno-associated virus (AAV) construct at different doses to induce hypertension, while a LacZAAV construct was used as negative control. Sham-operated db/+ mice served as healthy controls. Blood pressure and glomerular filtration rate (GFR) was measured at 22 weeks of age, while urine albumin to creatinine ratio (ACR) was measured before termination and kidney tissue sampling 24 weeks of age. Results: GFR measurements indicated hyperfiltration in all AAV-injected UNx db/db mice compared to db/+ mice, while ReninAAV tended to dose-dependently decrease GFR compared to LacZAAV in UNx db/db mice. Urine ACR was worsened by ReninAAV-induced hypertension compared to LacZAAV controls. 3D kidney imaging demonstrated increased glomerular volume in LacZAAV UNx db/db mice compared to db/+ mice with no further effect in ReninAAV groups. Automized AI-based glomerulosclerosis scoring showed ReninAAV dose-dependent increases in glomerulosclerosis compared to LacZAAV controls. RNA sequencing revealed upregulated gene expression markers of kidney fibrogenesis (Col1a1, Col4, Fn1) and tubular injury (Ngal and Kim-1), as well as downregulation of proximal tubular markers (Megalin, Aqp1) in ReninAAV UNx db/db mice compared to LacZAAV controls. Conclusion: ReninAAV-induced hypertension in female UNx db/db mice aggravates albuminuria and glomerulosclerosis paralleled by increased expression of genes associated with tubular injury renal fibrosis, thus confirming that ReninAAV UNx db/db mice is a reliable model of DN with features of late stage human disease. Disclosure M.V. Østergaard: None. I.R. Sørensen: None. A.A. Pedersen: None. T. Secher: Employee; Self; Gubra. Employee; Spouse/Partner; Novo Nordisk A/S. Stock/Shareholder; Self; Gubra. Stock/Shareholder; Spouse/Partner; Novo Nordisk A/S. F.E. Sembach: Employee; Self; Gubra. M.R. Madsen: None. K. Fosgerau: None. L.N. Fink: Employee; Self; Gubra. Stock/Shareholder; Self; Novo Nordisk A/S. N. Vrang: Board Member; Self; Gubra. Employee; Self; Gubra. Stock/Shareholder; Self; Gubra.

Glomerular Volume and Glomerulosclerosis at Different Depths within the Human Kidney.

Age, CKD risk factors, and kidney function are associated with larger glomerular volume and a higher percentage of globally sclerotic glomeruli. Knowledge of how these associations may differ by cortical depth is limited. To investigate glomerular volume and glomerulosclerosis across different depths of cortex, we studied wedge sections of the renal parenchyma from 812 patients who underwent a radical nephrectomy (for a tumor), separately characterizing glomeruli in the superficial (subcapsular), middle, and deep (juxtamedullary) regions. We compared the association of mean nonsclerotic glomerular volume and of glomerulosclerosis (measured as the percentage of globally sclerotic glomeruli) with age, obesity, diabetes, smoking, kidney function, and structural pathology in the superficial, middle, and deep regions. The superficial, middle, and deep regions showed significant differences in glomerular volume (0.0025, 0.0031, and 0.0028 µm3, respectively) and in glomerulosclerosis (18%, 7%, and 11%, respectively). There was a marked increase in glomerulosclerosis with age in the superficial region, but larger glomerular volume was not associated with age at any cortical depth. Glomerulosclerosis associated more strongly with arteriosclerosis and ischemic-appearing glomeruli in the superficial region. Hypertension, lower eGFR, and interstitial fibrosis associated with glomerulosclerosis and glomerular volume to a similar extent at any depth. Diabetes and proteinuria more strongly associated with glomerulosclerosis in the deep and middle regions, respectively, but neither associated with glomerular volume differently by depth. Obesity associated more strongly with glomerular volume in the superficial cortex. Most clinical characteristic show similar associations with glomerulosclerosis and glomerulomegaly at different cortical depths. Exceptions include age-related glomerulosclerosis, which appears to be an ischemic process and is more predominant in the superficial region.

CD44-Positive Glomerular Parietal Epithelial Cells in a Mouse Model of Calcineurin Inhibitors-Induced Nephrotoxicity

Background/Aims: Calcineurin inhibitors (CNIs) such as cyclosporine A (CsA) and tacrolimus are immunosuppressants that are frequently used as “key drugs” in the fields of transplantation, steroid resistance, refractory nephrotic syndrome, and autoimmune disease. However, long-term CNI use causes nephrotoxicity, the features of which are arteriolar hyalinosis, tubular atrophy, striped interstitial fibrosis, and focal segmental glomerulosclerosis (FSGS). We investigated whether FSGS in CNI-induced nephrotoxicity is associated with CD44-positive glomerular parietal epithelial cells (PECs), which play a significant role in experimental and human FSGS pathogenesis. Methods: We utilized the mouse model of CsA-induced nephrotoxicity, as well as controls. Histopathological and functional data were sequentially collected from 1 to 25 weeks after CsA injection. Glomerular expression of CD44 was immunohistochemically evaluated, as were markers for glomerular podocytes and PECs. Results: Glomerular CD44 expression occurred from 2 weeks after CsA injection and gradually increased in the CsA group. CD44-positive glomerular cells showed coexpression of claudin-1 (PEC marker) but not of synaptopodin (podocyte marker). From 20 weeks after CsA injection, the cells formed a bridge between Bowman’s capsule and the capillary tuft. These features are compatible with those of activated PECs, in which increased foot process effacement leads to bridge formation, and subsequently to an increase in glomerulosclerosis and a decrease in the expression of podocyte markers from 20 weeks. Conclusion: CD44-positive (activated) PECs reflect extremely early podocyte injury in the progression of FSGS formation and may be a good marker for early detection of CNI-induced nephrotoxicity.

NADPH Oxidase Nox5 Aggravates Renal Injury in Akita Mouse Model of Diabetic Nephropathy

Background: Renal reactive oxygen species (ROS) play an important role in mediating kidney injury in diabetes. Increasing evidence suggests that the pro-oxidant enzyme, Nox5 plays a significant role in human diabetic nephropathy (DN). Nox5 is present in humans and rabbits but not in mice or rats. Thus, there is a paucity of information about Nox5 in conventional animal models of DN. We examined the role of Nox5 in the insulin deficient diabetic Akita mice model using human inducible transgenic mice that express Nox5 selectively in endothelial cells (VEcad+Nox5+) or in mesangial cells (SM22+Nox5+). We also examined the endogenous expression of Nox5 in a high fat fed rabbit model of kidney disease. Methods: At week 10 mice were culled and kidneys were removed for the assessment of structural damage as well as gene and protein expression of markers of inflammation, fibrosis and oxidative stress. Protein expression of Nox5 and its localization in glomerular cells (endothelial and mesangial cells) were examined in transgenic mice by immunostaining. We also examined expression of pro-fibrotic gene in high fat fed rabbits by next generation sequencing (NGS) and RT-PCR and renal injury by histochemistry. Results: Expression of Nox5 was confirmed in glomerular endothelial and mesangial cells of transgenic mice. Diabetes induced increase in glomerulosclerosis, gene and protein expression of fibronectin and MCP-1 as well as nitrotyrosine were further increase in both diabetic Nox5 transgenic mice. Moreover, increased expression of Nox5 in high fat fed rabbits vs. normal diet fed rabbits was associated with increased expression of fibronectin, CTGF, collagen IV and VCAM-1 as well as increased mesangial expansion in the kidney. Conclusions: These findings in both transgenic mice model (endothelial and mesangial cells) suggest that Nox5 plays a significant role in mediating renal injury in diabetes. Disclosure J.C. Jha: None. A. Dai: None. M.E. Cooper: Advisory Panel; Self; AbbVie Inc.. Research Support; Self; Boehringer Ingelheim GmbH. Advisory Panel; Self; Boehringer Ingelheim Pharmaceuticals, Inc.. Speaker's Bureau; Self; Eli Lilly and Company. Advisory Panel; Self; Merck Sharp &amp; Dohme Corp., AstraZeneca. Research Support; Self; Novo Nordisk A/S. Advisory Panel; Self; Novartis AG. R.M. Touyz: None. C. Kennedy: Research Support; Self; Prometic Life Sciences Inc.. K. Jandeleit-Dahm: None.

Protocol renal biopsy in patients with lupus nephritis: a single center experience.

Renal biopsy plays an indispensable role in the diagnosis and management of patients with lupus nephritis (LN). A number of studies have evaluated the role of a repeat biopsy in case of disease relapse or treatment unresponsiveness. We studied 40 patients with LN with renal biopsies performed at baseline and after six months of therapy. The baseline and protocol biopsies were compared with respect to histological class transformation, crescents, tubular atrophy, interstitial fibrosis and glomerulosclerosis. We also compared serum creatinine, hemoglobin, systemic lupus erythematosus disease activity index (SLEDAI) scores, 24-h urine protein excretion and C3levels as well as activity index (AI) and chronicity index (CI) at baseline and at six months. Comparison of means was made by paired t test, McNemar test and marginal homogeneity test (multinomial data). Histological class transformation was seen in 10 patients (25%). Intra-class progression to greater chronicity was seen in 10 other patients (25%).There was an increase in glomerulosclerosis, tubular atrophy, interstitial fibrosis and a reduction in cellularity, crescent formation and wire loop lesions in the protocol biopsy. A decline in AI (6.05 vs. 2.50, P <0.001) and SLEDAI scores (8.1 vs. 3.7, P <0.001) and an increase in CI (0.68 vs. 2.52, P <0.001) was observed at the time of protocol biopsy. Our study shows a trend toward greater chronicity in protocol biopsies in LN.

High-fat/fructose feeding during prenatal and postnatal development in female rats increases susceptibility to renal and metabolic injury later in life

Accumulating evidence suggests that both an adverse prenatal and early postnatal environment increase susceptibility to renal and metabolic dysfunction later in life; however, whether exposure to adverse conditions during both prenatal and postnatal development act synergistically to potentiate the severity of renal and metabolic injury remains unknown. Sprague-Dawley rats were fed either a standard diet or a diet high in fat/fructose throughout pregnancy and lactation. After being weaned, female offspring were randomized to either standard diet or the high-fat/high-fructose diet, resulting in the following treatment groups: NF-NF, offspring of mothers fed a standard diet and fed a standard diet postnatally; NF-HF, offspring of mothers fed a standard diet and fed a high-fat/fructose diet postnatally; HF-NF, offspring of mothers fed a high-fat/fructose diet and fed a standard diet postnatally; HF-HF, offspring of mothers fed a high-fat/fructose diet and fed a high-fat/fructose diet postnatally. At the time of euthanasia (17 wk of age), HF-HF offspring weighed 30% more and had 110% more visceral fat than NF-NF offspring. The HF-HF offspring also had elevated blood glucose levels, glucose intolerance, 286% increase in urine albumin excretion, and 60% increase in glomerulosclerosis compared with NF-NF. In addition, HF-HF offspring exhibited a 100% increase in transforming growth factor-β protein expression and 116% increase in the abundance of infiltrated macrophages compared with the NF-NF offspring. These observations suggest that high-fat/fructose feeding during prenatal and throughout postnatal life increases the susceptibility to renal and metabolic injury later in life.

Abstract 1: Loss of Nuclear Receptor 4a1 on a Hypertensive Genetic Background Promotes Immune-Mediated Renal Injury

Nuclear hormone receptors of the NR4A subgroup have been implicated in cancer, atherosclerosis, and most prominently in metabolic disease. However, little is known about the role of NR4A1 in kidney health or disease. Fawn-hooded hypertensive (FHH) Nr4a1 -/- deficient animals were evaluated for blood pressure, proteinuria, renal function and metabolic parameters from 4-24 weeks of age. At week 24, Nr4a1 -/- rats exhibited 4-fold higher proteinuria (81±11.5 mg/24hrs/100gBW) compared to FHH (21±1.0). No difference in telemetry measured blood pressure was observed at any time point, but glomerular filtration rate was significantly decreased in the Nr4a1 -/- (542±78.9 ul/min/gKW) vs FHH (937±75.2). Moderate increases in glomerulosclerosis were seen, but were not different between strains. The severity of tubular atrophy, casts, and fibrosis was significantly increased in Nr4a1 -/- compared to FHH (19±1.86% vs 12±0.8%, respectively). Tubulointerstitial macrophage infiltration was also significantly increased in kidneys from Nr4a1 -/- (245±62 foci per field) compared to FHH (50±13.4) at week 24. Microarray analysis of kidney from week 8-24 found significant up-regulation of important immune mediators, including TGF-β1-2, CCL2 (MCP-1), CCL9 (MIP-1γ), and other chemokines and interleukins. The specific injury (tubulointerstitial), immune cell infiltration, and immune gene expression profile led to the hypothesis that loss of Nr4a1 contributes to the observed injury by an immune-mediated mechanism. To test this hypothesis, bone marrow (bm) cross transplantation studies were performed in 3 groups of irradiated (irr) animals: (1) bmFHH into irrFHH (FHH control); (2) bmFHH into irrNr4a1 -/- ; and (3) bmNr4a1 -/- into irrNr4a1 -/- (Nr4a1 control). The bmFHH into irrNr4a1 -/- animals showed a significant attenuation of proteinuria starting as early as week 12 and continuing through week 24 (35±4.6 mg/24hrs/100gBW) compared to the Nr4a1 -/- control (60±7.5). These data strongly suggest that the mechanism of Nr4a1 -/- renal injury is mediated via an immune mechanism, likely due to the predisposition of the FHH to develop renal injury. Further studies are now underway to better understand the precise immune mechanism that promotes injury in this model.

ACE Inhibition in Anti-Thy1 Glomerulonephritis Limits Proteinuria but Does Not Improve Renal Function and Structural Remodeling

Background/Aims: ACE inhibitor (ACE-I) treatment effectively inhibits proteinuria and ameliorates the course of various renal diseases. In experimental glomerulonephritis, however, angiotensin II (AngII) infusion has also been shown to be renoprotective. We evaluated the long-term (28 days) course of anti-Thy1 glomerulonephritis in animals with suppressed AngII formation by ACE-I treatment. Methods: Brown Norway rats received perindopril (2.8 mg/kg/day, n = 12), dihydropyridine calcium-antagonist amlodipine (Ca-A; 13 mg/kg/day, n = 6) or were left untreated (n = 14). All animals were monitored for blood pressure, proteinuria, and creatinine clearance after anti-Thy1 injection. Renal histology was assessed at day 7 and 28. Results: Systolic blood pressure was equally reduced by ACE-I and Ca-A treatment. AngII suppression prevented development of proteinuria, but did not protect against glomerular microaneurysm formation or reduction in creatinine clearance. After resolution of the microaneurysms, animals with suppressed AngII production showed a modest increase in glomerulosclerosis and vasculopathic thickening of intrarenal vessels. Conclusions: In anti-Thy1 glomerulonephritis, suppression of AngII formation does not protect against the induction of glomerular damage and is associated with mild aggravation of adverse renal fibrotic remodeling. Proteinuria, however, is effectively prevented by ACE-I treatment. Ca-A treatment did not affect the course of glomerulonephritis, indicating that ACE-I effects are blood pressure independent.

Bradykinin receptor 1 activation exacerbates experimental focal and segmental glomerulosclerosis

Focal and segmental glomerulosclerosis (FSGS) is one of the most important causes of end-stage renal failure. The bradykinin B1 receptor has been associated with tissue inflammation and renal fibrosis. To test for a role of the bradykinin B1 receptor in podocyte injury, we pharmacologically modulated its activity at different time points in an adriamycin-induced mouse model of FSGS. Estimated albuminuria and urinary protein to creatinine ratios correlated with podocytopathy. Adriamycin injection led to loss of body weight, proteinuria, and upregulation of B1 receptor mRNA. Early treatment with a B1 antagonist reduced albuminuria and glomerulosclerosis, and inhibited the adriamycin-induced downregulation of podocin, nephrin, and α-actinin-4 expression. Moreover, delayed treatment with antagonist also induced podocyte protection. Conversely, a B1 agonist aggravated renal dysfunction and even further suppressed the levels of podocyte-related molecules. Thus, we propose that kinin has a crucial role in the pathogenesis of FSGS operating through bradykinin B1 receptor signaling.

Histopathological Predictors of Renal Function Decrease After Laparoscopic Radical Nephrectomy

Radical nephrectomy is inevitably associated with a variable renal function decrease. We assessed the association of histopathological parameters in nonneoplastic renal parenchyma with the renal function decrease after radical nephrectomy. We evaluated 32 male and 17 female patients with a mean age of 55.9 years who underwent laparoscopic radical nephrectomy. Using the Cockcroft-Gault formula we calculated the estimated glomerular filtration rate preoperatively and at last followup at a mean of 19.7 months. The study end point was the percent change in the estimated glomerular filtration rate from baseline, defined as (absolute change/baseline) × 100. Three histological features in the nonneoplastic parenchyma were assessed by a renal pathologist, including global glomerulosclerosis, arteriosclerosis and interstitial fibrosis/tubular atrophy. For glomerulosclerosis assessment the percent of affected glomeruli was determined. Arteriosclerosis or the extent of arterial luminal occlusion was graded into 4 groups, including 1-0% to 5%, 2-6% to 25%, 3-26% to 50% and 4-greater than 50%. However, due to small patient numbers groups 1 and 2, and 3 and 4 were condensed, and AS was statistically evaluated as 0% to 25% or greater than 25%. Interstitial fibrosis/tubular atrophy was evaluated as absent/present. The mean estimated glomerular filtration rate decreased 31% from 122 to 85 ml/minute/1.73 m(2) after surgery (p < 0.0001). The percent change in the estimated glomerular filtration rate was associated with glomerulosclerosis extent (p = 0.034). For each 10% increase in glomerulosclerosis the estimated glomerular filtration rate decreased by 9% from baseline. The extent of arteriosclerosis or the presence of interstitial fibrosis/tubular atrophy did not correlate with the estimated glomerular filtration rate decrease. Glomerulosclerosis severity in nonneoplastic parenchyma can predict the rate of renal function decrease after radical nephrectomy. This histopathological parameter should be assessed in all tumor nephrectomy specimens, given that preserving renal function is important for quality of life and clinical outcome in patients with renal cancer.

Renal phenotype in heterozygous Lmx1b knockout mice (Lmx1b +/−) after unilateral nephrectomy

The nail-patella syndrome (NPS) is a rare autosomal-dominant disorder which is caused by loss-of-function mutations in the transcription factor LMX1B. NPS is characterized by dysplastic nails, absent or hypoplastic patellae, minor skeletal abnormalities and nephropathy (in 20-40% of the cases), which is the most severe aspect of the disorder. The current data suggest that genetic modifiers in the outbred human genetic background are responsible for this variable phenotype. Preliminary work on the function of Lmx1b in the kidney has been performed using Lmx1b knockout mice (Lmx1b (-/-)). Although Lmx1b (-/-) mice die within 24 h after birth, they exhibit the characteristic NPS features including the renal abnormalities. But in contrast to the situation in human, no phenotype could so far be detected in heterozygous Lmx1b (+/-) mice. This indicates that our understanding of the pathomechanism underlying the nephropathy is still very limited. In an attempt to further evaluate these mechanisms, we tried to induce a renal phenotype in Lmx1b (+/-) mice, and thus model the human (NPS) situation. We applied unilateral nephrectomy as a model to induce nephron loss and detected a significant (p = 0.02) reduction in compensatory renal growth in heterozygous knockout animals (Lmx1b (+/-)) compared to Lmx1b (+/+) animals, which was correlated with a significantly lower increase in glomerular volume (V(G)) (p = 0.0034) and an increase in glomerulosclerosis (p = 0.085). Thus, Lmx1b deficiency in heterozygous Lmx1b (Lmx1b (+/-)) knockout mice profoundly affects the compensatory response to nephron loss. Moreover, this is the first report of a phenotype in heterozygous Lmx1b (Lmx1b ( +/-)) knockout animals.

PPAR-α and -γ agonists attenuate diabetic kidney disease in the apolipoprotein E knockout mouse

Peroxisome proliferator-activated receptor (PPAR)-alpha and PPAR-gamma agonists are widely used in diabetes. In addition to their effects on lipid and glucose homeostasis, these agents have been postulated to have independent renoprotective actions. In the current study, we assess the efficacy of the PPAR-alpha agonist, gemfibrozil, the PPAR-gamma agonist rosiglitazone and the non-thiazolidinedione PPAR-alpha/gamma coagonist, compound 3q, on kidney structure and function in streptozotocin-treated apolipoprotein E knockout mice. Control and streptozotocin-diabetic mice were randomized to receive rosiglitazone (20 mg/kg/day), gemfibrozil (100 mg/kg/day), or compound 3q (3 mg/kg/day) by gavage, or no treatment for a period of 20 weeks. Renal fibrosis was assessed by standard histology and collagen IV immunohistochemistry. Kidney function was assessed by urinary albumin excretion and creatinine clearance. Diabetes in this model was associated with an increase in glomerulosclerosis, tubulointerstitial fibrosis and increased collagen IV deposition in the glomeruli and tubules. All three agents significantly attenuated glomerulosclerosis, tubulointerstitial expansion and collagen IV deposition. The increase in albuminuria and the decline in kidney function associated with diabetes in this model were also attenuated by each of these agents, with no superiority observed among various treatment groups. These renoprotective effects were observed in the absence of changes in glucose, insulin or lipid levels or a reduction in blood pressure. Combined with their independent anti-atherosclerotic actions, and their important effects on dyslipidaemia and insulin resistance, PPAR agonists may be useful for the prevention of diabetic complications, including kidney disease, even in type 1 diabetes.

The Effects of Ciclosporin in Experimental Glomerulosclerosis

The acute and chronic effects of daily, oral ciclosporin (CS) therapy (25 mg/kg) on proteinuria, blood pressure, renal function and histology were studied in rats subjected to unilateral nephrectomy and 3 weekly intraperitoneal injections of the aminonucleoside of puromycin (PAN). PAN therapy resulted in heavy proteinuria by week 4 which declined by weeks 8 and 16. When CS therapy was started weeks after the last dose of PAN, acute, transient reductions in proteinuria and reversible rises in blood urea nitrogen (BUN) were observed. When CS or oil therapy was started with PAN and continued for 8 or 16 weeks, there were no differences in proteinuria; however, after 16 weeks, CS treated rats had significantly higher BUN levels [65 +/- 11 (23.2 +/- 3.9) vs. 41 +/- 5 mg/dl (14.6 +/- 1.8 mmol/l); p = 0.001], a higher percentage of sclerotic glomeruli (47 +/- 7 vs. 28 +/- 10%; p less than 0.0001) and extensive interstitial fibrosis. There was a strong correlation between glomerulosclerosis and extent of interstitial fibrosis (r = 0.951; p less than 0.0001). These studies demonstrate that rats with experimental focal glomerulosclerosis treated with CS show an acute, transient reduction in proteinuria; however, chronic (for 16 weeks) CS therapy significantly increases azotemia and results in an increase in glomerulosclerosis and interstitial fibrosis.