No aggravation of renal injury in apolipoprotein E knockout mice (ApoE/) after subtotal nephrectomy
Moriz Buzello1,
Christian Stefan Haas5,
Frank Hauptmann1,
Marie Luise Gross1,
Jörg Faulhaber6,
Stefan Schultze-Mosgau4,
Heimo Ehmke6,
Eberhard Ritz2 and
Kerstin Amann3
1Department of Pathology and 2Department of Internal Medicine, University of Heidelberg, Heidelberg, 3Department of Pathology, 4Department of Oral and Maxillofacial Surgery and 5Department of Internal Medicine IV, University of Erlangen-Nürnberg, Erlangen and 6Department of Vegetative Physiology and Pathophysiology, UKE, Hamburg Germany
Correspondence and offprint requests to: Dr Kerstin Amann, Department of Pathology, University of Erlangen-Nürnberg, Krankenhausstraße 810, D-91054 Erlangen, Germany. Email: kerstin.amann{at}patho.imed.uni-erlangen.de
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Abstract
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Background. There is substantial experimental evidence that various forms of dyslipidaemia aggravate the course of renal failure and that reversal of dyslipidaemia ameliorates progression of renal failure. The apolipoprotein E knockout mouse (ApoE/) is an established model of accelerated atherogenesis. We investigated whether the course of renal disease after uninephrectomy (UNX) and subtotal nephrectomy (SNX) is altered in ApoE/ mice compared with their genetic controls.
Methods. Ten-week-old, male ApoE/ mice (body weight 25±2 g) were subjected either to sham operation (sham), UNX or SNX. C57BL/6 sham, UNX and SNX mice served as controls (body weight 26±3 g). The food intake of ApoE/ and C57BL/6 mice was kept identical by a pair-feeding protocol. After 12 weeks, mean arterial blood pressure and heart rate were measured in awake resting mice, the kidneys were perfusion fixed and analysed using quantitative histological methods, immunohistochemistry and RTPCR.
Results. At baseline, the sham ApoE/ mice had significantly higher (P<0.05) serum cholesterol and triglycerides than the controls. In parallel, mean arterial blood pressure was significantly elevated in sham ApoE/ mice compared with controls (137±15 vs 116±4 mmHg; P<0.05). In the sham groups, the glomerulosclerosis index was significantly higher in the ApoE/ mice (1.05±0.14 vs 0.57±0.07; P<0.05), whereas the tubulointerstitial damage score was comparable (0.06±0.04 vs 0.04±0.02; n.s.). After SNX there was a significant increase in glomerulosclerosis index, but no difference could be detected between ApoE/ and controls (1.75±0.16 vs 1.61±0.01, n.s.). The same was true for the tubulointerstitial damage index.
Conclusions. Despite some glomerulosclerosis and elevated mean arterial blood pressure at baseline, no acceleration of progression of renal disease was found in this genetic model of hyperlipoproteinaemia. This observation suggests that despite the known spontaneous histological changes in untouched kidneys, however, the presence of hyperlipidaemia in the ApoE/ mouse does not cause more severe progression in the present models of moderate renal disease.
Keywords: ApoE/ knockout mouse; dyslipidaemia; glomerulosclerosis; progression of renal failure; subtotal nephrectomy
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Introduction
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Several observations in humans [1,2] and experimental animal studies of dyslipoproteinaemia resulting from dietary [35] or genetic manipulation [68] showed that dyslipoproteinaemia is associated with impairment of renal structure and function. Conversely, reversal of dyslipoproteinaemia by dietary measures [9], administration of fibrates [10] or other lipid lowering agents including statines [9,11,12] mitigates the degree of renal damage. Taken together, these observations strongly argue for a harmful effect of dyslipoproteinaemia on renal structure and function. The mechanisms by which lipoproteins influence the kidney are still not fully understood. In particular, it is not clear whether dyslipidaemia mediates its deleterious effect directly or via induction of other pathways, i.e. the atherosclerotic pathways. Investigations in apolipoprotein E knockout mice (ApoE/) have provided insights into the pathogenesis of vascular disease pointing to a protective role of ApoE [13]. Additionally, loss of the ApoE gene has been shown to be involved in the late onset of Alzheimer's disease, also due to its cholesterol transporting properties [14]. Recently, it has been shown that after substitution of ApoE in ApoE/ mice, low levels of ApoE significantly ameliorate atherosclerosis, even though these ApoE levels were too low to reverse hyperlipidaemia [5]. In addition, Wen et al. [15] documented mild spontaneous glomerular alterations in 24-week-old and more severe alterations in 36-week-old female ApoE/ mice on a standard diet, whereas Bruneval et al. [16] found glomerular changes even in 20-week-old male ApoE/ only on a high cholesterol diet.
In the present study, we investigated whether in the models of uninephrectomy (UNX) and subtotal nephrectomy (SNX), progression was faster in the ApoE/ compared with their genetic control, the C57BL/6 mouse.
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Materials and methods
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Animal model
Adult male ApoE/ mice and their genetic background (C57BL/6 mice), which served as a control, were obtained from the Bomholtgard Breeding and Research Center (Silkeborg, Denmark) at the age of 8 weeks. Two weeks later they were subjected either to sham operation (sham), UNX or SNX in a single session by resection of the right kidney and weight controlled surgical removal of 75% of the cortex of the left kidney. Both ApoE/ and C57BL/6 mice undergoing sham served as baseline controls [17]. All animals received a low cholesterol diet (Altromin 1324; Altromin Co., Lage/Lippe, Germany) containing 19% protein, 0.24% NaCl and 5% fat (0.4% saturated, 1.29% uniunsaturated, 3.31% polyunsaturated fatty acids). Food intake in the corresponding groups (sham, UNX, SNX) of ApoE/ and C57BL/6 mice was kept identical using a pair-feeding protocol. The experiment was terminated 12 weeks after surgery: under ketamine (Ketanest, 10%; WDT, Garbsen, Germany) and xylazine-HCl (Rompun, 2%; Bayer Co., Leverkusen) anaesthesia blood samples were taken and perfusion fixation was performed using a 3% glutaraldehyde solution at body temperature [18]. The kidney was carefully removed and weighed; afterwards the volume of the kidney was calculated using the specific weight of the kidney (1.04 g/cm3) [18]. In parallel, for additional immunohistochemical studies and RTPCR analysis, five sham ApoE/ mice and C57BL/6 controls as well as five SNX ApoE/ mice were perfused with ice-cold saline [19]. All experiments and measurements were performed in accordance with national guidelines for the care and use of research animals.
Blood pressure measurement
Mean arterial blood pressure and heart rate were measured in awake resting mice at the day of perfusion fixation as previously described [20]. The animals were anaesthetized with a single dose of intraperitoneal ketamine (100 µg/g body weight) and xylazine-HCl (4 µg/g body weight). A polyethylene catheter (outer diameter: 400 µm) was inserted into the left carotid artery, fixed to the vessel wall and led to the neck of the animal. The mice usually awoke <60 min after induction of the anaesthesia and recovered from surgical procedure for at least 5 h prior to recording of the baseline blood pressure. During recovery and recordings, mice were placed in plexiglas tubes to restrict their movements partially. The catheters were connected to a pressure transducer (PRC-21K, amplifier MIO-0501, FMI). Arterial blood pressure and heart rate were continuously recorded at 100 Hz (80586, DAS-0216, Keithly-Metrabyte; Lab Tech Notebook 10.2.1, Labtech) for 15 min. Averages for mean arterial blood pressure and mean heart rate were calculated over the last 60 s of each recording period.
Serum chemistry
At the time of perfusion, fixation blood samples from the aorta were taken in EDTA tubes. Serum creatinine and urea were measured enzymatically with Boehringer Mannheim reagents using a Hitachi 917 747/400 analyser. A lipid profile comprising serum cholesterol and trigylcerides was determined by enzymatic methods using commercially available tests from Boehringer Co. (Mannheim, Germany).
Morphological evaluation
All investigations were performed in a blinded manner, i.e. the observer was unaware of the study group the animal belonged to.
Glomerular damage indices. As indices of renal damage the extent of glomerulosclerosis, i.e. the increase in mesangial cell or matrix content or the obliteration of capillary lumina, was analysed in 100 systematically subsampled glomeruli per animal [18,21]. Tubulointerstitial changes (tubular atrophy, dilation, casts, interstitial inflammation and fibrosis) and vascular damage (wall thickening, lumen obliteration, fibrinoid necrosis) were assessed in a blinded manner using a well established semi-quantitative scoring system [18,21]. The resulting indices in each animal were expressed as a mean of all scores obtained.
Glomerular geometry. To evaluate glomerular geometry we examined paraffin sections by light microscopy using haematoxylin and eosin stains. The area and the volume density of the renal cortex and the medulla, as well as the volume density of the glomeruli (VVglom) and the number of glomeruli per area (NA) were determined using a Zeiss eyepiece (Integrationsplatte II; Zeiss Co., Oberkochen, Germany) and the point counting method (PP = AA = VV) at a magnification of x100 [2124]. Total glomerular volume (Vglom) was calculated by multiplying volume density of glomeruli and cortex volume (VVglom x VC). Glomerular number per volume (NV) was determined using the following equation: NV = k/ß x NA1.5/VV0.5 with k=1.03 and ß=1.382 [2124]. The total number of glomeruli per one kidney (Nglom) was calculated by multiplication of glomerular number per volume (NV) and cortex volume (VC). The mean glomerular volume (v) was then derived from total glomerular volume and total number of glomeruli per kidney (Vglom/Nglom).
Measurements of wall thickness and lumen diameter. Morphometric analysis of wall thickness, lumen diameter and wall-to-lumen ratio was carried out using planimetry and a semi-automatic image analysing system (AnalysisPRO; SIS, Münster, Germany) at a magnification of x400. In brief, the outer and inner vessel diameter were measured at two opposing sites of the vascular wall since this is the site which is least affected by the sectioning angle. Wall thickness was calculated as (outer diameter inner diameter) / 2 and wall-to-lumen ratio was derived from wall thickness divided by the inner diameter.
Immunohistochemistry
Immunohistochemical analysis was performed on paraffin sections using antibodies against collagen IV (anti-collagen IV, polyclonal rabbit; 1:100; Biotrend, Köln, Germany), fibronectin (anti-fibronectin, polyclonal rabbit, 1:100; Sigma, Deisenhofen, Germany) and PDGF (anti-PDGF, polyclonal goat; 1:50; Upstate Biotechnology, Lake Placid, USA) and the avidin-biotin technique [1719]. Briefly, paraffin sections were dewaxed, dehydrated in xylol and washed with PBS buffer; after blocking of non-specific binding with 3% H2O2 (20 min, room temperature) and 100% fetal calf serum (30 min, 37°C) sections were washed with PBS and then incubated with the primary antibodies overnight (4°C). After rinsing in PBS, sections were then incubated for 30 min with the second antibodies (biotinylated anti-rabbit and anti-goat, 1:200, 30 min at room temperature). Then the sections were again washed in PBS, incubated for 30 min with Avidin (Biogenex, USA) and washed again. Then the label complex was applied (DAB-Kit; Vector, Germany) for 520 min; colour development was stopped under microscopic control by adding water and sections were then finally counterstained using haematoxylin. All antibodies had been tested for specificity in the mouse. Negative controls were performed either by omitting the primary antibody or by substitution of the primary antibody with equimolar concentrations of preimmune rabbit or goat IgG (Sigma Co., Taufkirchen, Germany) as described in detail [1719,25]. To reduce run-to-run variations in the staining intensity, all stainings of the same antibody were performed in the same run for all animals [18]. The sections were examined using light microscopy at a magnification of x400 and a semi-quantitative scoring system (04): score 0, no expression; score 1, mild expression; score 2, moderate expression; score 3, strong expression; score 4, extremely strong expression [26]. For analysis of immunohistochemical staining, 25 systematic subsampled glomeruli per animal were scored. All analyses were performed in a blinded manner, i.e. the observer was unaware of the experimental protocol.
RTPCR for ET-1, TGF-ß and PDGF mRNA
Because of the well known interaction between endothelin (ET), TGF-ß and PDGF in the pathogenesis and progression of renal disease [23], mRNA expression of these factors was investigated in five animals per group using RTPCR as described before [23,24]. Total RNA was isolated from frozen tissue samples of rat kidneys using Trizol (Gibco BLR Co., Eggenstein, Germany); integrity was checked by gel electrophoresis. RNA concentration was determined photometrically in triplicate.
Oligonucleotides. The primers were as follows. ET-1: sense, 5'-TGGCTTTCCAAGGAGCTCC-3'; antisense, 5'-CTTGGCAGAAATTCCAGC-3', resulting in a PCR fragment of 339 bp. The mutant comprised 302 bp. TGF-ß: sense, 5'-TGGCTTTCCAAGGAGCTCC-3'; antisense, 5'-GCTTGGCAGAAATTCC-AHC-3', resulting in a 403 bp fragment. The mutant had a length of 300 bp. PDGF: sense, 5'-CCTGTGCCCATTCGCAGGAA-3'; antisense, 5'-TTGGCCACCTTGACACTGCG-3'. The fragment was 226 bp in length and the mutant comprised 183 bp.
RTPCR. RT was performed according to the method of Paul et al. [27]. The reaction was run on a Perkin Elmer DNA thermal cycler 480 (Perkin Elmer, Langen, Germany) under the following conditions: initial denaturation, 94°C, 3 min; 94°C, 1 min; annealing, 55°C, 1 min; extension, 72°C, 1 min, 2628 cycles.
Competitive PCR. Semi-quantitative measurements of ET-1, TGF-ß and PDGF mRNA were carried out using deletion mutants of the respective cDNAs as internal standard [23,24]. Analysis of PCR fragments was done according to a modification of the method of Paul et al. [27] as described in detail [23,24].
Statistical analysis
All data were tested for normality distribution. The results are given as mean (x)±standard deviation (SD). Differences between groups were analysed by using the KruskalWallis test or ANOVA followed by a post hoc Duncan multiple range analysis (SPSS, SPSS Inc., Chicago, IL, USA).
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Results
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Description of the model (Table 1)
As a result of the pair-feeding protocol, the body weight was not significantly different in C57BL/6 controls and ApoE/ mice. Mean arterial blood pressure was somewhat higher in sham ApoE/ mice (137±15 mmHg) compared with sham C57BL/6 controls (116±4mmHg). Compared with the sham animals, blood pressure was not altered after UNX or SNX in either C57BL/6 (111±7 mmHg) or ApoE/ (134±13 mmHg) mice. The heart rates as well as the heart weights (data not shown) were not different in sham C57BL/6 and ApoE/ mice, respectively. Serum creatinine concentrations increased only marginally after SNX in C57BL/6 (0.44±0.14 mg/dl) and ApoE/ (0.52±0.07mg/dl) mice compared with the values in the respective baseline groups (0.23±0.06 and 0.35±0.03 mg/dl, respectively). The values in sham and UNX ApoE/ groups were significantly higher, however, than in the respective C57BL/6 control groups. Serum urea levels were significantly higher in both SNX groups than in all other groups; after SNX, the values were comparable, however, in the ApoE/ and control mice. As expected, total cholesterol values were approximately 10 times higher in ApoE/ mice (675±86 mg/dl) than in C57BL/6 (73±13 mg/dl, P<0.05) controls and increased further after UNX or SNX, whereas in C57BL/6 controls no significant change after the interventions could be noted. Triglyceride values were also significantly higher in sham ApoE/ mice (76±26 mg/dl) than in C57BL/6 (41±17 mg/dl) controls and were further increased in ApoE/ mice after SNX (118±44 mg/dl, P<0.05).
Morphological indices of renal damage and glomerulus geometry (Tables 2 and 3 and Figure 1)
Compared with sham C57BL/6 controls the glomerulosclerosis index was significantly higher in the sham ApoE/ mice (Table 2). The typical morphology of the glomerulus in the different experimental groups is shown in Figure 1. A slight expansion of the mesangial matrix, irregularities of the capillary tuft and some spontaneous mesangiolysis were noted in 22-week-old male sham ApoE/ mice (Figure 1B) compared with sham controls (Figure 1A). After UNX, slight glomerular enlargement, an increase in mesangial matrix and in mesangial cell number leading to a higher glomerulosclerosis index, which was only in control animals significantly different from sham (Figure 1C and D) was seen. SNX led to further glomerular enlargement and a marked increase in mesangial cell number and mesangial matrix with a significant increase in glomerulosclerosis index in both ApoE/ and control mice compared with the sham groups (Figure 1E and F). Nevertheless, even after SNX, no significant difference in glomerulosclerosis could be observed between the ApoE/ (1.75±0.16) and C57BL/6 (1.61±0.11) groups. The tubulointerstitial damage was only mild to moderate; however, it was significantly higher in ApoE/ mice after SNX, than in all sham and UNX groups, but no significant difference was seen between both SNX groups (Table 2). In parallel with the increase in glomerulosclerosis index, alterations of mesangial collagen IV, fibronectin and PDGF protein expression were noted in SNX ApoE/ mice compared with sham ApoE/ mice (see details below).

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Fig. 1. Representive examples of glomerulosclerosis in ApoE/ mice (DE) and their genetic controls (AC). (A) Sham C57BL/6, (B) UNX C57BL/6, (C) SNX C57BL/6, (D) sham ApoE/, (E) UNX ApoE/, (F) SNX ApoE/.
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It is well known that the number and size of glomeruli affect the evolution of glomerulosclerosis. To exclude such confounding effects, the number and volume of glomeruli were evaluated in ApoE/ mice and C57BL/6 controls. Table 3 documents that mean glomerular volume was comparable between the corresponding ApoE/ and control groups; it was significantly higher, however, in both SNX groups compared with the other groups. The number of glomeruli tended to be lower in ApoE/ mice, but this difference was not statistically significant. In addition, counting of glomerular number confirmed that the degree of renal surgical ablation (SNX) was comparable in ApoE/ and control animals.
Although semi-quantitative assessment of vascular changes did not reveal any significant differences between the vascular index in the experimental groups (Table 2), morphometric analysis of wall thickness of interlobular arteries revealed significantly (P<0.05) higher values after SNX in both ApoE/ (7.24±0.16 µm) and control mice (7.47±0.05 µm) compared with the sham and UNX groups. In addition, there was a tendency to lower values in sham (6.01±0.16 µm) and UNX (6.59±0.13 µm) ApoE/ mice compared with sham (6.69±0.58 µm) and UNX (7.33±0.08 µm) controls, but these differences were not statistically significant. Plaque formation or calcification was not seen in renal arteries.
Immunohistological investigations (Figure 2) and RTPCR
Using immunohistochemistry, we investigated changes in glomerular protein expression after SNX in ApoE/ mice; the qualitative results are given in Figure 2. We found an increase in mesangial collagen type IV expression in ApoE/ mice after SNX (score: 2.08±0.64; Figure 2B) compared with sham ApoE/ mice (score: 0.81±0.38; Figure 2A). In parallel, mesangial protein expression of fibronectin (score: 1.33±0.11) and PDGF (score: 1.67±0.24) were also increased after SNX in ApoE/ mice (Figure 2D and E) compared with sham mice (scores: 0.79±0.20 and 0.27±0.09, respectively; Figure 2C and F) where they were only hardly detectable.

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Fig. 2. Representative examples of immunhistochemical changes in sham (A, C and E) and SNX ApoE/ mice (B, D and F). The results of the respective negative controls are given as small inserts. Increased mesangial collagen type IV expression in ApoE/ mice after SNX (B) compared with sham (A). Protein expression of fibronectin was markedly increased in the mesangium of ApoE/ mice after SNX (D) compared with sham (C) where there was only minor expression. Glomerular PDGF protein expression was also markedly increased in ApoE/ mice after SNX (F) compared with sham (E) where it was hardly detectable.
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Using semi-quantitative competitive RTPCR, a significantly higher amount of renal ET-1 mRNA was noted in kidneys of sham ApoE/ animals (2.15±0.51) compared with sham control animals (1.28±0.48, P<0.05). Expression of renal ET-1 mRNA did not further increase, however, after SNX (2.16±0.85). In contrast to ET-1, no significant differences in renal TGF-ß mRNA or PDGF mRNA expression were noted between the sham control animals (2.74±0.80 and 0.97±0.22) and the sham ApoE/ animals (2.46±0.43 and 1.04±0.25), respectively. Similarly, after SNX of ApoE/ animals, there was no significant change in renal TGF-ß or PDGF mRNA (2.44±0.87 and 0.84±0.30) expression compared with values in sham animals.
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Discussion
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The present study was designed to evaluate whether renal injury after UNX or SNX is more severe in mice with hereditary dyslipidaemia, i.e. in the ApoE/ mouse. The study yielded two major findings concerning the phenotype of the ApoE/ mice. First, the renal phenotype of 22-week-old ApoE/ mice is characterized by some spontaneous mesangial matrix expansion and mesangial cell hyperplasia as reflected by a higher glomerulosclerosis index and mesangiolysis. In addition, there was a tendency to lower numbers of glomeruli per kidney with somewhat higher mean glomerular volume. Secondly, the ApoE/ mice have a slightly elevated mean arterial blood pressure which did not further increase after UNX and SNX, respectively. Hence, one would assume that the above characteristics should predispose to a more rapid progression of renal lesions. Unexpectedly, despite higher baseline levels of glomerulosclerosis index in the ApoE/ mice compared with wild-type mice, possibly related to somewhat higher blood pressure values, no amplification of renal and, in particular, glomerular injury, after moderate reduction of renal mass, was noted compared with SNX wild-type mice. The ApoE/ mouse was generated in C57BL/6 mice and substantial backcrossing was performed. It is unlikely, therefore, that the differences between the two strains were generated by a different genetic background. It is known, however, that a C57BL/6 background constitutes a certain resistance to glomerular disease in mice, be it degenerative or immunological [28]. In addition, in principle, the sex of the animals may be of some importance since it was shown that females are less prone to dyslipidaemia-associated glomerular disease. In our study, however, we used only male mice and therefore, it is unlikely that our failure to detect differences between ApoE/ and control animals resulted from sex differences.
The present study was designed to evaluate whether progression of renal injury after UNX or SNX is more severe in mice with hereditary dyslipidaemia.
Paradoxically, however, SNX of ApoE/ mice did not lead to a significantly higher increase in serum creatinine or urea concentration, mean arterial blood pressure, glomerulosclerosis and expression of extracellular matrix proteins in the glomerulus as compared with the SNX C57BL/6 control mice. Obviously, ApoE/ mice have marked glomerulosclerosis and elevated blood pressure at baseline, but no acceleration of progression in this experimental model of renal failure was noted.
In the present study, we used semi-quantitative and quantitative histological methods to detect differences in renal structure of ApoE/ and C57Bl/6 controls that had been well validated in the rat model of SNX [4,21,23,24]. These methods had been proved to be highly sensitive and reliable in assessing the effect of various interventions on progression of renal damage, e.g. the role of sympathetic nerve dysfunction [24], 1,25(OH)2D3 [18] or various antihypertensive agents [21,29]. The experimental conditions were well standardized and we took great care to control for a number of potential confounding factors, such as food consumption or degree of resection of renal tissue or blood pressure. Since food intake has a particular effect on progression of glomerulosclerosis it is important that body weights were comparable between all groups. This indicates that our pair-feeding protocol was successful. The mechanisms of progression differed to some extent between the UNX and the SNX model. Possibly because the remnant kidney remains untouched in the UNX model, it shows less tubulointerstitial alterations compared with SNX. In addition, it is well known that in the UNX model, progression of renal injury is the result of preglomerular vasodilatation causing increased intra-glomerular pressures.
The findings of the present study are in striking contrast to those obtained in a number of previous studies where spontaneous renal injury or aggravation of pre-existing injury in animals exposed to high dietary lipid intake or different forms of dyslipidaemia was demonstrated [3,4,30,31]. The results are particularly amazing since in the study of Wen et al. [15] after 24 weeks and, particularly after 36 weeks, female ApoE/ mice developed spontaneous glomerular lesions with macrophage accumulation, commonly with foam cell appearance, deposition of extracellular matrix, glomerular hyperplasia, and foci of mesangiolysis associated with capillary microaneurysms. The observation of no difference in the morphological markers of progression, however, is further reinforced by serial measurements of blood urea and creatinine concentrations in the long-term study of Bro and coworkers [32] where, after the initial increase following SNX, constant elevations of these parameters were noted up to 22 weeks after UNX and SNX. A further point may relate to experimental conditions. Bruneval et al. [16] documented that only male ApoE/ mice fed a high cholesterol diet developed marked glomerular alterations. It is also possible that differences in oxidative stress (which was not measured) may account for the different outcomes. Other confounder factors may be the age of the animals and the duration of the study. In the study by Wen and coworkers [15], however, glomerular foam cells in mesangial areas were already detected in 24-week-old female ApoE/ mice on a standard diet.
At any rate, what emerges from these observations is that there was a striking discrepancy between the reaction of the (non-lesioned) aortic wall and the (lesioned) kidney to the milieu provided by the genetic hyperlipidaemia in the ApoE/ mouse [17]. Obviously, at least in this genetic model, the injured kidney is less susceptible to lipid-induced damage than the non-lesioned central arteries which develop accelerated atherosclerosis [17].
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Acknowledgments
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The skillful technical assistance of Z. Antoni, H. Derks, R. Dussel, G. Gorsberg, M. Klewer, P. Rieger, S. Söllner, M. Weckbach and H. Ziebart is gratefully acknowledged. M. Buzello, M. L. Gross and J. Faulhaber were recipients of a grant of the Graduiertenkolleg Nieren- und Kreislaufregulation of the Deutsche Forschungsgemeinschaft. Supported by the Federal Ministry of Education and Research (BMBF) and by the Interdisciplinary Center for Clinical Research (IZKF) at the University Hospital of the University of Erlangen-Nuremberg (B 40). Parts of the study were also supported by the Deutsche Forschungsgemeinschaft (SFB 423, project B8).
Conflict of interest statement. None declared.
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References
|
---|
- Keane WF, Kasiske BL, ODonell MP. The role of lipids in progressive glomerular disease. Adv Exp Med Biol 1987; 223: 8187[Medline]
- Samuelsson O, Attman PO, Knight-Gibson C et al. Complex apolipoprotein B-containing lipoprotein particles are associated with a higher rate of progression of human chronic renal insufficiency. J Am Soc Nephrol 1998; 9: 14821488[Abstract]
- Scheuer H, Gwinner W, Hohlbach, J et al. Oxidant stress in hyperlipidemia-induced renal damage. Am J Physiol Renal Physiol 2000; 278: F63F74[Abstract/Free Full Text]
- Song H, Li X, Zhu C, Wie M. Glomerulosclerosis in adriamycin-induced nephrosis is accelerated by lipid-rich diet. Pediatr Nephrol 2000; 15: 196200[CrossRef][ISI][Medline]
- Thorngate FE, Rudel RL, Walzer RL, Williams DL. Low level of extrahepatic nonmacrophage apoE inhibits atherosclerosis without correcting hypercholesterolemia in apoE-deficient mice. Arterioscler Thromb Vasc Biol 2000; 20: 19391945[Abstract/Free Full Text]
- Binder CJ, Weiher H, Exner M, Kerjaschki D. Glomerular overproduction of oxygen radicals in Mpv17 gen inactivated mice causes podocyte foot process flattening and proteinuria: a model of steroid-resistant nephrosis sensitive to radical scavenger therapy. Am J Pathol 1999; 154: 10671075[Abstract/Free Full Text]
- Coimbra TM, Janssen U, Gröne HJ et al. Early events leading to renal injury in obese Zucker (fatty) rats with type II diabetes. Kidney Int 2000; 57: 167182[CrossRef][ISI][Medline]
- Lambert G, Sakai N, Vaisman BL et al. Analysis of glomerulosclerosis and atherosclerosis in lecithin cholesterol acyltransferase-deficient mice. J Biol Chem 2001; 276: 1509015098[Abstract/Free Full Text]
- Ingram AJ, Parbtani A, Clark WF et al. Dietary alteration of dihomogamma-linolenic acid/arachidonic acid ratio in a rat 5/6-renal-ablation model. J Am Soc Nephrol 1996; 7: 10241031[Abstract]
- McCarthy KJ, Routh RE, Shaw W, Walsh K, Welbourne TC, Johnson JH. Troglitazone halts diabetic glomerulosclerosis by blockade of mesangial expansion. Kidney Int 2000; 58: 23412350[CrossRef][ISI][Medline]
- Lee HS, Jeong JY, Kim BC, Kim YS, Zhang YZ, Chung HK. Dietary antioxidant inhibits lipoprotein oxidation and renal injury in experimental focal segmental glomerulosclerosis. Kidney Int 1997; 51: 11511159[ISI][Medline]
- Vazquez-Perez S, Aragoncillo P, de Las Heras N et al. Atorvastatin prevents glomerulosclerosis and renal endothelial dysfunction in hypercholesterolaemic rabbits. Nephrol Dial Transplant 2001; 16 [Suppl 1]: 4044[Medline]
- Moghadasian MH, McManus BM, Nguyen LB et al. Pathophysiology of apolipoprotein E deficiency in mice: relevance to apo E-related disorders in humans. FASEB J 2001; 15: 26232630[Abstract/Free Full Text]
- Corder EH, Saunders AM, Strittmatter WJ et al. Gene dose of apolipoprotein E type allele and the risk of Alzheimer's disease in late onset families. Science 1993; 261: 921923[ISI][Medline]
- Wen M, Segerer S, Dantas M et al. Renal injury in apolipoprotein E-deficient mice. Lab Invest 2002; 82: 9991006[ISI][Medline]
- Bruneval P, Bariety J, Belair MF, Mandet C, Heudes D, Nicoletti A. Mesangial expansion associated with glomerular endothelial cell activation and macrophage recruitment is developing in hyperlipidaemic apoE null mice. Nephrol Dial Transplant 2002; 17: 20992107[Abstract/Free Full Text]
- Buzello M, Törnig J, Faulhaber J, Ehmke H, Ritz E, Amann K. The apolipoprotein E knockout mouse: a model documenting accelerated atherogenesis in uremia. J Am Soc Nephrol 2003; 14: 311316[Abstract/Free Full Text]
- Schwarz U, Amann K, Orth SR, Simonaviciene A, Wessels S, Ritz E. Effect of 1,25(OH)2 vitamin D3 on glomerulosclerosis in subtotally nephrectomized rats. Kidney Int 1998; 53: 16961705[CrossRef][ISI][Medline]
- Amann K, Kronenberg G, Gehlen F et al. Cardiac remodelling in experimental renal failure-an immunhistochemical study. Nephrol Dial Transplant 1998; 13: 19581966[Abstract]
- Dono R, Texido G, Dussel R, Ehmke H, Zeller R. Impaired cerebral cortex development and blood pressure regulation in FGF-2-deficient mice. EMBO J 1998; 17: 42134225[Abstract/Free Full Text]
- Amann K, Nichols C, Törnig J, Schwarz U, Zeier M, Mall G, Ritz E. Effect of ramipril, nifedipine and moxonidine on glomerular morphology and podocyte structure in experimental renal failure. Nephrol Dial Transplant 1996; 11: 10031011[Abstract]
- Weibel ER. Practical methods of biological morphometry. In: Stereological Methods. Academic Press, New York: 1979
- Amann K, Koch A, Hofstetter J et al. Glomerulosclerosis and progression: effect of subantihypertensive doses of alpha and beta blockers. Kidney Int 2001; 60: 13091323[CrossRef][ISI][Medline]
- Amann K, Rump LC, Simonaviciene A et al. Effects of low dose sympathetic inhibition on glomerulosclerosis and albuminuria in subtotally nephrectomised rats. J Am Soc Nephrol 2000; 11: 14691478[Abstract/Free Full Text]
- Haas CS, Amann K, Schittny J, Blaser B, Müller U, Hartner A. Glomerular and renal vascular structural changes in alpha8 integrin-deficient mice. J Am Soc Nephrol 2003; 14: 22882296[Abstract/Free Full Text]
- Gross ML, El-Shakmak A, Szabo A et al. ACE-inhibitors but not endothelin receptor blockers prevent podocyte loss in early diabetic nephropathy. Diabetologia 2003; 4: 856868[CrossRef]
- Paul M, Wagner J, Dzau VJ. Gene expression of the renin-angiotensin system in human tissues: quantitative analysis by the polymerase chain reaction. J Clin Invest 1993; 91: 20582064[ISI][Medline]
- Zheng F, Plati AR, Potier M et al. Resistance to glomerulosclerosis in b6 mice disappears after menopause. Am J Pathol 2003; 162: 13391348[Abstract/Free Full Text]
- ODonnell MP, Kasiske BL, Kim Y, Schmitz PG, Keane WF. Lovastatin retards the progression of established glomerular disease in obese Zucker rats. Am J Kidney Dis 1993; 22: 8389[ISI][Medline]
- Nabokov A, Amann K, Gassmann P, Schwarz U, Orth SR, Ritz E. The renoprotective effect of angiotensin-converting enzyme inhibitors in experimental chronic renal failure is not dependent on enhanced kinin activity. Nephrol Dial Transplant 1998; 13: 173176[Abstract]
- Romero R, Higueruelo S, Vaquero M, Biosca C, Martinez-Ocana JC, Pastor C. Effects of polyunsaturated fatty acids on rat glomerulosclerosis induced by hypercholesterolaemic diet. Res Exp Med (Berl) 1998; 198: 110[CrossRef][Medline]
- Bro S, Bentzon JF, Falk E, Olgaard K, Nielsen LB. Chronic renal failure accelerates atherogenesis in apolipoprotein-E deficient mice. J Am Soc Nephrol 2003; 14: 24662474[Abstract/Free Full Text]
Received for publication: 26. 6.03
Accepted in revised form: 1.10.03