Mammalian Target of Rapamycin Inhibition Halts the Progression of Proteinuria in a Rat Model of Reduced Renal Mass
Fritz Diekmann*,,
Jordi Rovira*,
Joaquim Carreras,
Edgar M. Arellano*,
Elisenda Bañón-Maneus*,
María José Ramírez-Bajo*,
Alex Gutiérrez-Dalmau*,
Mercè Brunet and
Josep M. Campistol*
Departments of * Nephrology and Renal Transplantation, Pathology, and Clinical Pharmacology, Hospital Clínic, Barcelona, Spain; and Department of Nephrology, Charité Campus Mitte, Berlin, Germany
Correspondence: Dr. Fritz Diekmann, Department of Nephrology and Renal Transplantation, Hospital Clínic, Villarroel, 170, E-08036 Barcelona, Spain. Phone: +34-932275423; Fax: +34-932275498; E-mail: fdiekman{at}clinic.ub.es
Received for publication January 22, 2007.
Accepted for publication May 29, 2007.
Many kidney transplant patients experience an increase in proteinuriawhen converted from a calcineurin inhibitor–based regimento one based on a mammalian target of rapamycin (mTOR) inhibitor,and preexisting proteinuria and poor renal function have beenidentified as risk factors for this increase. Our aim was toevaluate the effect of sirolimus, an mTOR inhibitor, on renalfunction and histology in a proteinuric model of reduced renalmass. Sirolimus-treated animals had approximately half as muchproteinuria as vehicle-treated animals (P < 0.05), and hadless glomerulosclerosis, tubular atrophy, interstitial fibrosis,and inflammation. Immunohistochemistry showed that sirolimusattenuated the increased expression of renal vascular endothelialgrowth factor (VEGF), as well as the expression of VEGF receptors1 and 2. In conclusion, sirolimus halted the progression ofproteinuria and structural damage in a rat model of reducedrenal mass, possibly through a reduction in renal VEGF activity.
The mTOR inhibitor (mTOR-I) sirolimus can be used as base orconcomitant immunosuppressive treatment in solid organ transplantationand offers the potential of potent immunosuppressive treatmentwithout calcineurin inhibitor–like toxicity.1–3Furthermore, mTOR-I have gained attention for their antiproliferativeproperties.4 An increase in proteinuria was observed in manypatients who were converted from a calcineurin inhibitor–basedregimen to an mTOR-I–based regimen.5,6 Although severalrisk factors for the increase in proteinuria after conversion,such as preexisting proteinuria and poor renal function, havebeen identified, possible pathomechanism are still being investigatedand remain unclear.7–9 It has been suggested that oneof the possible pathomechanisms of mTOR-I–associated proteinuriamight involve the vascular endothelial growth factor (VEGF).8,10VEGF is a factor of endothelial cell survival, endothelial repair,and angiogenesis.11,12 In a remnant kidney model, VEGF is overexpressedin the early phase, leading to hypertrophy of the remainingtissue and consequent impairment of renal function. This canbe prevented by early VEGF antagonism.13 Conversely, late afterrenal mass reduction, the VEGF system is downregulated and externalVEGF application improves renal function.14 Thus, the VEGF systemis regulated according to specific pathologic situations. Inhumans, VEGF antagonism as part of treatment for malignant tumorscan lead to proteinuria,15 but also high VEGF concentrations—asobserved in colorectal cancer—lead to proteinuric nephropathy.16Thus, a balance of the VEGF system seems to be important forglomerular function and glomerular endothelial cell regeneration.Guba et al.17 showed that VEGF secretion is inhibited by sirolimustreatment.
As an experimental approach to mTOR-I–related proteinuria,we chose the renal mass reduction rat model to mimic a situationof renal insufficiency and proteinuria, glomerular sclerosis,and interstitial fibrosis. In this model, initial proliferationand glomerular hypertrophy are followed by renal fibrosis.14,18,19The aim was to evaluate the influence of treatment with sirolimus,initiated after onset of proteinuria, on the further developmentof proteinuria in a model of reduced renal mass. Further objectiveswere the evaluation of the influence of sirolimus on the histologyand on the renal VEGF system.
Thirty-one animals reached the end of the study and were completelyanalyzed (sham rats that received vehicle, n = 8; nephrectomizedrats that received vehicle, n = 7; sham rats that received sirolimus,n = 7; nephrectomized rats that received sirolimus, n = 9).Nine animals were lost either during the operative proceduresor shortly thereafter without ever receiving sirolimus.
Sirolimus Concentrations
The whole-blood trough concentrations were 38.8 ± 7.9and 33.7 ± 5.3 ng/ml in the sham rats that received sirolimusand the nephrectomized rats that received sirolimus respectively(NS).
Renal Functional Analysis
Creatinine clearance was markedly reduced after renal mass reductioncompared with sham-operated control rats. The values of creatinineand creatinine clearance are given in Figure 1. The treatmentwith sirolimus had no influence on creatinine or creatinineclearance, neither in the sham-operated rats nor in the ratswith renal mass reduction.
Figure 1. Creatinine clearance normalized per body weight. Values for sham-operated rats are represented by squares: , vehicle treatment; , sirolimus treatment; values for rats with reduced renal mass are represented by triangles: , vehicle treatment; , sirolimus treatment. The creatinine clearances of sham-operated rats were significantly higher regardless of treatment with or without sirolimus. Sirolimus treatment alone did not have any influence on creatinine clearance.
Proteinuria was observed as early as 3 wk after renal mass reductionand increased to 66.9 ± 33.3 mg/d urinary protein excretionat 5 wk after nephrectomy in both groups with nephrectomy, whereasit did not change in the sham-operated rats. Values of proteinuriaare given in Figure 2. Rats that received nephrectomy and sirolimusexperienced no further increase of proteinuria after week 6,whereas vehicle-treated rats doubled the amount of daily urinaryprotein excretion until the last follow-up at 12 wk after initiationof treatment (Figure 2).
Figure 2. Treatment with sirolimus inhibited the progression of proteinuria in rats with reduced renal mass. *Significantly different versus sham-operated rats; #significantly different versus vehicle treatment; *#P < 0.05; **##P < 0.01; ***###P < 0.001.
Histologic Analysis
The glomerular diameter was increased in rats with renal massreduction in the vehicle group (0.11 ± 0.007 versus 0.18± 0.02 mm; P = 0.001) as well as in the sirolimus group(0.11 ± 0.007 versus 0.15 ± 0.01 mm; P = 0.003).The glomeruli of rats with reduced renal mass and sirolimustreatment were significantly smaller (P = 0.004).
The results of the evaluation of tubular atrophy, interstitialfibrosis and inflammation, and glomerulosclerosis are givenin Table 1. The nephrectomized rats that received vehicle showedsevere tubular atrophy, interstitial fibrosis, interstitialinflammation, and glomerulosclerosis. In the nephrectomizedrats that received sirolimus, the total number of sclerosedglomeruli and the severity of segmental glomerulosclerosis weresignificantly reduced (Figures 3 and 4). The degree of tubularatrophy, interstitial fibrosis, and inflammation were also significantlyreduced in the nephrectomized rats that received sirolimus comparedwith the nephrectomized rats that received vehicle.
Figure 3. Trichromic stains of a representative kidney of rats with sham operation and vehicle treatment (A), renal mass reduction and vehicle treatment (B), sham operation and sirolimus treatment (C), or renal mass reduction and sirolimus treatment (D). Magnification, x100.
Figure 4. Incidence of glomerulosclerosis as different grades of severity of segmental glomerular sclerosis ranging from unaffected glomerular to complete sclerosis. Sham-operated rats did not show any affection of glomeruli. More than 30% of the glomeruli of vehicle-treated rats with renal mass reduction showed severe segmental or total sclerotic lesions. This effect was significantly attenuated by sirolimus treatment.
Urinary VEGF Concentrations
Urinary VEGF concentrations normalized for urinary creatinineare depicted in Figure 5. The urinary VEGF concentrations weresignificantly reduced by renal mass reduction in the vehicle-treatedgroup (sham rats that received vehicle versus nephrectomizedrats that received vehicle 0.05 ± 0.02 versus 0.02 ±0.01 pg/mg creatinine; P = 0.007). Sirolimus treatment numericallyincreased the urinary VEGF concentrations in sham rats (0.09± 0.06; sham rats that received vehicle versus sham ratsthat received sirolimus; NS). The reduction of the urinary VEGFconcentration through renal mass reduction was completely abolishedby sirolimus treatment (nephrectomized rats that received vehicleversus nephrectomized rats that received sirolimus, 0.02 ±0.01 versus 0.11 ± 0.09; P = 0.006).
Figure 5. Urinary VEGF concentrations normalized for urinary creatinine concentration. *Significantly different versus sham-operated rats; #significantly different versus vehicle treatment; **##P < 0.01.
Serum VEGF Concentrations
Serum VEGF concentrations were increased in vehicle-treatedrats with renal mass reduction compared with vehicle-treatedsham rats (sham rats that received vehicle versus nephrectomizedrats that received vehicle 4.8 ± 2.8 versus 10.4 ±2.1 pg/ml; P = 0.014; Figure 6). Sirolimus treatment led toa numerical increase of serum VEGF concentrations (sham ratsthat received sirolimus versus nephrectomized rats that receivedsirolimus 33.0 ± 22.5 versus 36.7 ± 25.5 pg/ml;NS); however, this difference reached statistical significanceonly in the comparison of the groups with renal mass reduction(nephrectomized rats that received vehicle versus nephrectomizedrats that received sirolimus; P = 0.006).
Figure 6. Serum VEGF concentrations. *Significantly different versus sham-operated rats; #significantly different versus vehicle treatment; *P < 0.05; ##P < 0.01.
Immunohistochemistry of Renal VEGF and Its Receptors VEGF.
Renal mass reduction was accompanied by an increase of glomerularVEGF expression in the immunohistochemical analysis in the nephrectomizedrats that received vehicle (intensity of glomerular VEGF staining:sham rats that received vehicle versus nephrectomized rats thatreceived vehicle: 1.6 ± 0.7 versus 2.6 ± 0.5;P = 0.009). Sirolimus treatment attenuated the increase of glomerularVEGF activity in the nephrectomized rats that received sirolimus(sham rats that received sirolimus versus nephrectomized ratsthat received sirolimus: 1.0 ± 0.0 versus 1.1 ±0.4; NS; Figure 7). The difference of glomerular VEGF stainingbetween the groups with renal mass reduction was significant(nephrectomized rats that received vehicle versus nephrectomizedrats that received sirolimus, P = 0.001). Tubuli of sham-operatedrats did not show any VEGF staining at all (Figure 7). TubularVEGF staining of the nephrectomized rats that received vehiclewas more intense than that of the nephrectomized rats that receivedsirolimus (2.0 ± 0.0 versus 0.6 ± 0.4; P = 0.001).
Figure 7. Immunohistochemical stains for VEGF of a representative kidney of rats with sham operation and vehicle treatment (A), renal mass reduction and vehicle treatment (B), sham operation and sirolimus treatment (C), or renal mass reduction and sirolimus treatment (D). Magnification, x400.
VEGF Receptor 1.
Glomerular VEGF receptor 1 staining showed an increased intensityin the nephrectomized rats that received vehicle (sham ratsthat received vehicle versus nephrectomized rats that receivedvehicle: 2.0 ± 0.0 versus 2.8 ± 0.4; P = 0.007);however, a decreased intensity in both sirolimus-treated groups(sham rats that received sirolimus versus nephrectomized ratsthat received sirolimus: 1.2 ± 0.3 versus 1.3 ±0.5 [NS]; sham rats that received vehicle versus sham rats thatreceived sirolimus: P = 0.005; nephrectomized rats that receivedvehicle versus nephrectomized rats that received sirolimus:P = 0.002; Figure 8). Tubular VEGF receptor 1 staining was apparentonly in the nephrectomized rats that received vehicle. Neitherthe nephrectomized rats that received sirolimus nor the ratsin the two sham-operated groups showed tubular VEGF receptor1 staining (P < 0.01).
Figure 8. Immunohistochemical stains for the VEGF receptor 1 of a representative kidney of rats with sham operation and vehicle treatment (A), renal mass reduction and vehicle treatment (B), sham operation and sirolimus treatment (C), or renal mass reduction and sirolimus treatment (D). Magnification, x400.
VEGF Receptor 2.
Glomerular staining for the VEGF receptor 2 was markedly increasedin the vehicle-treated rats with renal mass reduction comparedwith sham-operated control rats (nephrectomized rats that receivedvehicle versus sham rats that received vehicle 2.4 ±0.4 versus 0.9 ± 0.4; P = 0.01; Figure 9). Sirolimuslowered the glomerular signal of the VEGF receptor 2 in thesham rats that received sirolimus versus sham rats that receivedvehicle (sham rats that received sirolimus: 0.2 ± 0.3;P = 0.013). The VEGF receptor 2 intensity was also lower inthe nephrectomized rats that received sirolimus compared withthe nephrectomized rats that received vehicle (nephrectomizedrats that received sirolimus: 1.2 ± 0.27; P = 0.004).
Figure 9. Immunohistochemical stains for the VEGF receptor 2 of a representative kidney of rats with sham operation and vehicle treatment (A), renal mass reduction and vehicle treatment (B), sham operation and sirolimus treatment (C), or renal mass reduction and sirolimus treatment (D). Magnification, x400.
Tubular VEGF receptor 2 staining was increased in the nephrectomizedrats that received vehicle (nephrectomized rats that receivedvehicle versus sham rats that received vehicle: 1.0 ±0.0 versus 0.0 ± 0.0; P < 0.001). This increase wassignificantly less intense in the nephrectomized rats that receivedsirolimus (0.1 ± 0.2; nephrectomized rats that receivedvehicle versus nephrectomized rats that received sirolimus:P = 0.001).
In our model of renal mass reduction, we observed a reducedcreatinine clearance and an increase in proteinuria and tubulointerstitialas well as glomerular lesions. To our knowledge, this is thefirst study showing that the intervention with an mTOR inhibitorafter 6 wk when significant proteinuria is already present attenuatesthe further increase of proteinuria and leads to better renalhistology as compared with the vehicle group. The lesions areaccompanied by an activation of the VEGF system, which can bepartially attenuated by treatment with sirolimus.
Sirolimus prevented the further increase of proteinuria. Wecould further show that sirolimus treatment was accompaniedby less interstitial inflammation and fibrosis, less tubularatrophy, and less glomerular lesions after 3 mo of treatment.In a rat model of type 1 diabetes with diabetic nephropathy,Lloberas et al.20 demonstrated the beneficial effects of sirolimustreatment. They showed that low-dosage treatment with troughconcentrations of 2.3 ng/ml led to significantly decreased albuminuria.However, in their model, glomerular hypertrophy was not affectedby sirolimus treatment. The difference compared with our results,in which sirolimus seemed to protect from glomerular hypertrophyas well, might be the higher sirolimus trough concentrationused in our model. Indeed, Nagai et al.21 showed that the AKT/mTORpathway was activated in the pathomechanism of glomerular hypertrophyin experimental diabetic nephropathy.
The achieved drug concentration in our study is high comparedwith target concentrations in clinical use today. In some clinicaltrials in the past, similar drug concentrations were used successfully.3In a recently published experimental model,22 a high intraperitonealdosage of 2 mg/kg per d (corresponding to a weekly dosage of14 mg/kg) was applied. We chose an intermediate dosage correspondingto 3 mg/kg per wk.
In contrast to our results, Daniel et al.23 demonstrated thata high dosage of the mTOR inhibitor Everolimus, applied earlyin an anti-Thy1.1 nephritis rat model, increased mortality andglomerular sclerosis, an effect that was not seen by the sameauthors in low-dosage treatment or when treatment was started3 d after induction of the lesions. The negative effect of thedrug in this model was linked to inhibition of endothelial cellproliferation and reduced VEGF activity.
VEGF has also been proposed to play a significant role in thedevelopment of glomerular hypertrophy and albuminuria in themodel of renal ablation, which could be shown by Schrijverset al.13 In their study, the administration of a neutralizingVEGF antibody directly after renal mass reduction had a beneficialeffect by significantly attenuating the increase of albuminuriaand glomerular hypertrophy.
In our study, we showed that renal mass reduction led to anactivation of the VEGF system (i.e., an increase of the serumVEGF concentration) in the nephrectomized rats that receivedvehicle as well as a higher intensity of renal immunohistochemicalstaining of VEGF and its receptors 1 and 2. This was accompaniedby a reduced urinary VEGF concentration. Although our studydesign does not offer an explanation for this, one could speculatethat despite a higher VEGF serum concentration and more intenseimmunostaining, a higher number of active renal VEGF receptorsmight be able to reduce the urinary VEGF concentration. In ourstudy, sirolimus treatment significantly reduced the immunostainingof VEGF and its receptors in rats with renal mass ablation.In accordance with our findings, Solà-Vilà etal.24 demonstrated that sirolimus reduced the glomerular VEGFprotein concentration in the anti-Thy1.1 model. Concerning theinfluence of sirolimus on VEGF receptors, Guba et al.17 showedthat proliferation of human umbilical cord vein endothelialcells as a response to VEGF is markedly reduced by sirolimus,suggesting that sirolimus interferes with the signaling cascadeof VEGF receptors. Indeed, mTOR is situated downstream of thereceptor in the VEGF signaling cascade,11 suggesting that mTORblockade could negatively influence the signaling. In our study,the VEGF serum concentration was significantly increased bysirolimus in both the group without and the group with renalmass ablation. Izzedine et al.8 observed a significant increaseof the serum VEGF concentration in a renal transplant patientassociated with sirolimus treatment. This finding was confirmedby Stracke et al.,10 who detected an increased VEGF serum concentrationin kidney transplant patients who were treated with an mTORinhibitor as compared with patients who received a calcineurininhibitor. Possibly, the interrupted VEGF receptor signalingcascade might also lead to interference with a feedback mechanismthat is implicated in the regulation of VEGF secretion, therebycontributing to higher VEGF serum concentrations.
Whether modulation of the VEGF system (e.g., through the useof an mTOR inhibitor) leads to a negative effect, as observedby Daniel et al.,23 or to a beneficial consequence, as observedby Schrijvers et al.13 or in our model, might depend on thetype of damage and the timing of the treatment. It is imaginablethat VEGF might be needed for endothelial repair for a shortperiod and later exert negative effects in terms of favoringglomerular hypertrophy and fibrotic mechanisms. However, theimplication of the VEGF system in different models of diseasesuch as the model of anti-Thy1.1 nephritis23 or of diabeticnephropathy20 or ours might be different and not sufficientto explain the distinct effects of mTOR-I treatment in thesedifferent models or in transplant patients.
In patients with mTOR-I–associated proteinuria, the VEGFsystem has been examined only in relatively few cases and neverin a systematic manner.8,10 Therefore, prospective studies inhumans are necessary to elucidate possible changes of the VEGFsystem in this context.
Our results demonstrate that sirolimus treatment can attenuatethe increase in proteinuria and structural damage in a modelof renal mass reduction. This effect is accompanied by a decreasein the activity of the local renal VEGF system.
Animals
Male Wistar rats (Charles River Laboratories España,Barcelona, Spain) weighing approximately 225 g were used. Theywere kept at constant temperature and humidity and on a 12-hlight/dark cycle. The rats had free access to standard rat chow(Harlan Interfauna Ibèrica, S.L., Barcelona, Spain) andwater. This study was approved by and conducted according tothe guidelines of the local animal ethics committee (Comitèètic d’experimentació animal CEEA, Decret214/97).
Experimental Design
The rats (n = 40) were randomly assigned to four groups. Twoof these groups were assigned to undergo renal mass reductionand the other two to have sham operations. Renal mass reductionwas performed by cryoablation and subsequent contralateral uninephrectomyafter 1 wk, as published by Schrijvers et al.13 The rats ofthe sham groups underwent surgery at the same time points. Theseprocedures were performed under general anesthesia with isofluorane(Forane; Abbott Laboratories, S.A., Madrid, Spain). After anabdominal incision, the left kidney was exposed and separatedfrom the adrenal gland. The lower and upper poles of the leftkidney were frozen by application of a cylinder of dry ice ofstandard size for 2 min on each pole. Thereafter, the same cylinderof dry ice was applied to the anterior and posterior sides ofthe kidney. After 1 wk, the right kidney was removed. The ratsof the sham groups underwent the same abdominal incision andmanipulation of the left and the right kidneys without tissuedestruction. All rats received buprenorphine (Buprex; Schering-PloughS.A., Madrid, Spain) at a dosage of 0.03 mg/kg per 12 h for24 h after surgery. Six weeks after the second surgical intervention,the rats were randomly assigned to receive either treatmentwith sirolimus (supplied by Wyeth Pharmaceuticals, Collegeville,PA) 1.0 mg/kg intraperitoneally three times per week or vehiclefor 12 wk. The vehicle consisted of polysorbate 80 (Sigma-Aldrich,Madrid, Spain), dimethylacetate, and polyethylene glycol 400(Merck S.A., Madrid, Spain).
Sirolimus Concentrations
Sirolimus whole-blood trough concentrations were measured usingan HPLC assay coupled to a triple quadrupole mass spectrometer(Quatro Micro; Micromass, Waters, Milford, MA) with a limitof detection of 1 ng/ml and a linearity from 1 to 75 ng/ml.
Renal Functional Parameters
Serum creatinine, creatinine clearance, urinary protein excretion,hemoglobin, triglycerides, and total cholesterol were determinedtwice before initiation of sirolimus treatment and then everyother week by the hospital central laboratory. For collectionof urine samples for the determination of creatinine clearanceand urinary protein excretion, the rats were housed in metaboliccages separately for 24 h.
Histologic Analysis
At the end of the study, the rats were killed and kidney sampleswere harvested, fixed in formalin, and embedded in paraffinby routine methods. Hematoxylin-eosin, periodic acid Schiff,and trichromic staining was performed.
Segmental and complete glomerular sclerosis was analyzed usinga semiquantitative scoring system from 0 to 4 (0, no affection;1, <25% of glomerular area affected; 2, 25 to 49% affected;3, 50 to 99% affected; 4, complete glomerular sclerosis). Tubularatrophy and interstitial fibrosis as well as interstitial inflammationwere scored from grade 0 to 3 (0, none [<5%]; 1, mild [6to 25%]; 2, moderate [26 to 50%]; 3, severe [>50%]).
Glomerular diameter was assessed by calculation of the meanof diameters of 20 randomly chosen glomeruli per rat. Histologicanalysis was performed using a laboratory upright microscope,and diameters were measured using an eyepiece micrometer (BX51and 20,4-10/100 EYEP.MICRO., respectively; Olympus UK Ltd, Middlesex,UK).
Urinary and Serum VEGF Concentrations
At 17 wk after nephrectomy, rats were individually housed inmetabolic cages for collection of 24-h urine in iceboxes (dryice). The urine was defrosted and filtered before it was centrifugedat 2000 rpm (500 x g) for 10 min. The supernatant was used todetect VEGF by ELISA kit (RayBiotech, Norcross, GA) and creatininefor data normalization. VEGF serum detection was determinedby Quantikine Rat VEGF ELISA kit (R&D Systems, Minneapolis,MN).
Immunohistochemistry of Renal VEGF Ligand and Receptor
Consecutive sections were deparaffinized in xylene, and antigenretrieval was performed by proteolytic digestion with proteinaseK for 2 min (Proteinase K ready to use S3020; DakoCytomation,Glostrup Denmark). Unspecific staining was blocked with 3% normalgoat sera (S-1000; Vector Laboratories, Burlingame, CA) for10 min before incubation for 30 min with primary antibodiesthat were diluted with antibody diluent with background-reducingcomponents (Dako S3022). The primary antibodies used were (1)VEGF, monoclonal mouse anti-rat VEGF (Clone VG1), dilution 1:3000;(2) VEGFR1, polyclonal rabbit anti-rat VEGF receptor-1, dilution1:5; and (3) VEGFR2, polyclonal rabbit anti-rat VEGF receptor-2,dilution 1:25. All antibodies were purchased from Abcam (Cambridge,UK). Detection was performed using the EnVision system (DakoCytomation)according to the manufacturer's instructions. An isotype-matchedcontrol antibody was used as a negative control. Staining intensitywas scored from grade 0 to 3 (0, none; 1, mild; 2, moderate;3, strong).
All images were acquired using an Olympus BX51 clinical microscopeand DP70 digital camera and software (Olympus, Tokyo, Japan;objective lens, UPlanApo 20/0.70 NA).
Statistical Analyses
Statistical analysis was performed using the SPSS 14.0 statisticspackage. Values are given as means ± SD. The Mann-WhitneyU test, Wilcoxon test, or Kruskal-Wallis test was used whereapplicable.
This study was supported by grants from Wyeth Pharmaceuticals,from "Redes Temáticas de Investigación cooperativaV-2003-REDC03," and from the "Fondo de InvestigaciónSanitaria, FIS 03/0557." A.G.D. received a grant from the InstitutoCarlos III, Ministerio de Sanidad y Consumo.
Parts of this work were published in abstract form at the annualmeeting of the American Society of Nephrology; November 14 through19, 2006; San Diego, CA.
We gratefully appreciate the help, advice, and support fromDr. M. Solé and Dr. J. F. Ramírez, Departmentof Pathology, Hospital Clínic. We also thank Dr. EnriqueGranados (Wyeth, Madrid, Spain) for excellent help and support.
Footnotes
Published online ahead of print. Publication date availableat www.jasn.org.
F.D. and J.R. contributed equally to the study design and preparationof the manuscript.
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(2009)
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[Abstract][Full Text][PDF]
E. Letavernier, P. Bruneval, S. Vandermeersch, J. Perez, C. Mandet, M.-F. Belair, J.-p. Haymann, C. Legendre, and L. Baud Sirolimus interacts with pathways essential for podocyte integrity
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[Abstract][Full Text][PDF]
N. Lloberas, J. Torras, G. Alperovich, J. M. Cruzado, P. Gimenez-Bonafe, I. Herrero-Fresneda, M.{m. d.}l. Franquesa, I. Rama, and J. M. Grinyo Different renal toxicity profiles in the association of cyclosporine and tacrolimus with sirolimus in rats
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[Abstract][Full Text][PDF]
S. L. Lui, R. Tsang, K. W. Chan, F. Zhang, S. Tam, S. Yung, and T. M. Chan Rapamycin attenuates the severity of established nephritis in lupus-prone NZB/W F1 mice
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[Abstract][Full Text][PDF]
K. Hochegger, G. L. Jansky, A. Soleiman, A. M. Wolf, A. Tagwerker, C. Seger, A. Griesmacher, G. Mayer, and A. R. Rosenkranz Differential Effects of Rapamycin in Anti-GBM Glomerulonephritis
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[Abstract][Full Text][PDF]
S. Kramer, Y. Wang-Rosenke, V. Scholl, E. Binder, T. Loof, D. Khadzhynov, H. Kawachi, F. Shimizu, F. Diekmann, K. Budde, et al. Low-dose mTOR inhibition by rapamycin attenuates progression in anti-thy1-induced chronic glomerulosclerosis of the rat
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[Abstract][Full Text][PDF]
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Abstract
Introduction
, vehicle treatment; 
, sirolimus treatment; values for rats with reduced renal mass are represented by triangles: 
, vehicle treatment; 
, sirolimus treatment. The creatinine clearances of sham-operated rats were significantly higher regardless of treatment with or without sirolimus. Sirolimus treatment alone did not have any influence on creatinine clearance.
