Mycophenolate Mofetil Ameliorates Arteriolopathy and Decreases Transforming Growth Factor-β1 in Chronic Cyclosporine Nephrotoxicity

Afferent arteriolopathy is the most characteristic lesion of chronic cyclosporine (CsA) nephrotoxicity. We investigated the effect of therapeutic doses of mycophenolate mofetil (MMF) in a model of chronic CsA nephrotoxicity where transforming growth factor-beta (TGF-beta) was shown to play a central role. Rats treated with vehicle, MMF 10 mg/kg/day, CsA 10 mg/kg/day or CsA + MMF were sacrificed at 7 or 28 days. Physiologic and histologic changes were studied in addition to TGF-beta1 mRNA and protein expressions, and mRNA expression of plasminogen activator inhibitor-1 (PAI-1) and the extracellular matrix (ECM) proteins biglycan and types I and IV collagen. While MMF markedly ameliorated afferent arteriolopathy, it had no significant effect on interstitial fibrosis and tubular atrophy. In addition, MMF treatment reduced both TGF-beta1 mRNA and protein levels by 39% and 32%, respectively (p < 0.05 vs. CsA only). The expression of the ECM proteins followed that of TGF-beta1 and was significantly decreased with MMF; a similar effect was observed with PAI-1, suggesting an increase in ECM degradation. These results suggest that MMF exerts a beneficial effect on CsA arteriolopathy and that it decreases TGF-beta1. While this drug combination may be useful clinically, long-term studies are needed to determine if MMF has a lasting benefit.     

Effect of cyclosporine and sirolimus on the expression of connective tissue growth factor in rat experimental chronic nephrotoxicity

BACKGROUND/AIMS: Connective tissue growth factor (CTGF) is a pro-fibrotic growth factor that acts downstream of transforming growth factor (TGF)-beta. However, CTGF regulation remains unknown. We tried to determine the effect of two commonly used immunosuppressants, cyclosporine (CsA) and sirolimus (SRL), on CTGF expression in a model of chronic nephrotoxicity. METHODS: Adult Sprague-Dawley rats kept on a low-salt diet were treated daily for 4 weeks with vehicle (VH), SRL (0.3 mg/kg), CsA5 (5 mg/kg), CsA10 (10 mg/kg) or both CsA5 and SRL. CTGF and TGF-beta1 expressions were evaluated by Northern blot. Functional and histologic parameters in addition to number of apoptotic cells were determined. RESULTS: At 28 days, both CsA doses were capable of inhibiting CTGF mRNA expression to levels similar to control. On the other hand, SRL increased CTGF expression by 3.5-fold. However, addition of CsA to SRL completely reversed that trend and returned levels to control. The results were different for TGF-beta1, which was increased by both CsA and SRL and to a greater extent by the drug combination. CONCLUSION: Unlike TGF-beta, CTGF does not seem to play an important role in CsA-induced chronic nephrotoxicity. In addition, calcineurin-dependent pathways are likely involved in CTGF regulation.     

Effect of nitric oxide modulation on TGF-beta1 and matrix proteins in chronic cyclosporine nephrotoxicity

BACKGROUND: Chronic cyclosporine (CsA) nephrotoxicity is characterized by interstitial fibrosis and afferent arteriolar hyalinosis. L-arginine (L-Arg), the substrate for nitric oxide (NO) synthase and N-nitro-L-arginine-methyl ester (L-NAME), the NO synthase inhibitor, were shown to modulate acute CsA nephrotoxicity. However, the mechanism of fibrosis in chronic CsA nephrotoxicity remains unclear. Thus, we examined the effect of NO modulation on fibrosis and the expression of transforming growth factor-beta1 (TGF-beta1) and matrix proteins in chronic CsA nephrotoxicity. METHODS: Rats were administered CsA (7.5 mg/kg), CsA + L-Arg (1.7 g/kg), CsA + L-NAME (3.5 mg/kg), vehicle (VH), VH + L-Arg, and VH + L-NAME, and were sacrificed at 7 or 28 days. NO production, physiologic parameters, and histology were studied in addition to the mRNA expression of TGF-beta1, plasminogen activator inhibitor-1 (PAI-1) and the matrix proteins biglycan and collagens type I and IV by Northern and the protein expression of PAI-1 and fibronectin by enzyme-linked immunosorbent assay. RESULTS: While L-NAME strikingly reduced NO biosynthesis and worsened the glomerular filtration rate and CsA-induced fibrosis, L-Arg had the opposite beneficial effect. In addition, the CsA-induced up-regulated expression of TGF-beta1, PAI-1, and the matrix proteins biglycan, fibronectin, and collagen I was significantly increased with L-NAME and strikingly improved with L-Arg. Collagen IV expression was not affected. Also, NO modulation did not affect VH-treated rats. CONCLUSIONS: Chronic CsA nephrotoxicity can be aggravated by NO blockade and ameliorated by NO enhancement, suggesting that NO maintains a protective function. NO modulation was associated with a change in TGF-beta1 expression, which, in turn, was associated with alterations in matrix deposition and matrix degradation through its effect on PAI-1.     

Pirfenidone Treatment Decreases Transforming Growth Factor-β1 and Matrix Proteins and Ameliorates Fibrosis in Chronic Cyclosporine Nephrotoxicity

Chronic cyclosporine (CsA) nephrotoxicity is characterized by tubulointerstitial fibrosis. Pirfenidone (PFD) is a novel antifibrotic compound that was shown to prevent and even reverse fibrosis. The mechanism of action of PFD is unclear but involves inhibition of transforming growth factor-beta (TGF-beta). Salt-depleted rats were administered CsA, CsA + PFD, vehicle (VH) or VH + PFD and sacrificed at 28days. Physiologic and histologic changes were studied in addition to TGF-beta1, plasminogen activator inhibitor-1 (PAI-1) and biglycan mRNA expressions by Northern blot. TGF-beta1 immunohistochemistry was also performed. Treatment with PFD ameliorated CsA-induced fibrosis by about 50% (p < 0.05). CsA-induced decrease in creatinine clearance improved with PFD but the difference was not significant. TGF-beta1, PAI-1 and biglycan mRNA expressions increased with CsA (p < 0.05 vs. VH) but strikingly improved with PFD treatment (p < 0.05 vs. CsA), which brought the levels down to VH levels. PFD treatment also decreased TGF-beta1 protein expression by 80%. These results demonstrate that PFD can attenuate renal fibrosis in this model. PFD was associated with a decrease in TGF-beta1 expression, which, in turn, was associated with a decrease in matrix deposition. These experiments suggest that PFD can be clinically useful for preventing chronic CsA nephrotoxicity and may prove to be helpful in other progressive renal diseases.     

Combination therapy with sirolimus and mycophenolate mofetil: effects on the kidney and on transforming growth factor-beta1

Sirolimus (SRL) is not nephrotoxic, but it has been shown to increase transforming growth factor (TGF)-beta. We investigated the effect of combining mycophenolate mofetil (MMF) with SRL on renal structure and function and on TGF-beta1. Rats treated with vehicle (VH), MMF 10 mg/kg/d, SRL 0.3 mg/kg/d, or SRL+MMF were killed at 28 days. The physiologic and histologic changes and expression of TGF-beta1, plasminogen activator inhibitor-1, and extracellular matrix proteins were studied. Although SRL alone did not alter renal function and structure, it increased TGF-beta1 mRNA by 44% and protein by 48% (P <0.05 vs. VH). Treatment with MMF did not affect TGF-beta1. When combined with SRL, MMF decreased TGF-beta1 expression to VH levels. A similar trend was observed with plasminogen activator inhibitor-1 and extracellular matrix proteins. The long-term consequence of increased TGF-beta in SRL-treated kidneys remains unknown. However, because MMF can reverse this trend, SRL and MMF combination therapy may be protective.     

Immunosuppressant use without bone loss--implications for bone loss after transplantation.

Cyclosporine A (CsA) is associated with posttransplantation bone disease. Immunosuppressant drugs such as sirolimus (SRL), which are more potent and less deleterious than CsA, are being developed. Previous experiments have shown that SRL although immunosuppressive, is relatively bone sparing. The use of low doses of CsA and SRL in combination has displayed in vivo synergism. This study was initiated to examine the effect of low-dose CsA and SRL on bone metabolism, thereby hopefully providing a bone sparing immunosuppressive regimen for transplant recipients. One hundred and nineteen rats were divided into groups: basal, vehicle, CsA high dose, CsA low dose, SRL low dose, and combination low-dose CsA and SRL. The basal group was killed on day 0 for histomorphometry. The experimental groups were weighed and bled on days 0, 28, 56, and 84 and were killed on day 84 for histomorphometry. Serial assays for blood urea nitrogen (BUN), creatinine, and osteocalcin were performed. Osteocalcin was raised on days 28 and 56 in the high dose CsA group. Histomorphometry showed osteopenia with high-dose CsA. Low-dose CsA was relatively bone sparing, while low-dose SRL and combined low-dose CsA did not cause bone loss. In conclusion, the synergistic combination of low-dose CsA and SRL has the potential of providing both bone sparing and immunosuppressive benefits.     

Comparison of expression of TGF-beta1, its receptors TGFbeta1R-I and TGFbeta1R-II in rat kidneys during chronic nephropathy induced by cyclosporine and tacrolimus

OBJECTIVE: Chronic rejection is a major cause of graft dysfunction after kidney transplantation. Long-term treatment with cyclosporine (CsA) or tacrolimus (FK506) results in chronic nephrotoxicity. Transforming growth factor-beta1 (TGFbeta1) and its receptors type I (TR-I) and type II (TR-II) have been known to contribute to this side effect. The expression of TGF-beta1, TR-I, and TR-II in rat kidneys has not been compared during chronic nephropathy induced by CsA or FK506. METHODS: Rat models of chronic CsA- or FK506-induced nephropathy were established using Sandimun Neoral or Prograf administration. The kidneys were dissected and TGF-beta1, TR-I, and TR-II proteins and TR-I and TR-II mRNAs measured by immunohistochemistry and in situ hybridization, respectively, to compare the results of the two groups. RESULTS: The functional and morphologic studies showed that in the rats the nephrotoxic effects of FK506 were not as significant as those of CsA. The results of immunohistochemistry and in situ hybridization showed that the expression of renal TGFbeta1, TR I, TR-II proteins and TR and TR II mRNA in the FK506 group were lower than those in the CsA groups. CONCLUSION: These results showed that both FK506 and CSA display nephrotoxicity, but that the nephrotoxicity of FK506 was less than that of CsA in chronic nephropathy.     

Cyclosporine-induced interstitial fibrosis and arteriolar TGF-beta expression with preserved renal blood flow

BACKGROUND: Cyclosporine A (CsA)-induced chronic nephrotoxicity is characterized by interstitial fibrosis and afferent arteriole hyalinosis. CsA lesion has been linked to maintained renal vasoconstriction and narrowing of the afferent arteriole lumen diameter, leading to preglomerular ischemia. We investigated the role of renal hemodynamics in CsA-induced transforming growth factor (TGF-beta) expression and interstitial fibrosis. METHODS: Groups of rats fed a low salt diet were given CsA 5 mg/kg/day (CsA) or the vehicle (olive oil, [VH]) s.c. and had the renal blood flow (RBF), glomerular filtration rate (GFR), mean arterial pressure, renal vascular resistance, renal histologic changes, and immunohistochemical features for macrophages and TGF-beta evaluated after 1, 2, and 8 weeks of treatment. RESULTS: At week 1, despite normal renal hemodynamics and MAP, there was a significant macrophage interstitial influx in CsA-treated rats (70+/-16 vs. 29+/-4 cells+/0.5 mm2, in CsA vs. VH, P=0.02) that was progressive with treatment (80+/-13 vs. 32+/-8 cells+/0.5 mm2, P=0.016 and 197+/-36 vs. 23+/-3 cells+/0.5 mm2, P=0.0002, CsA vs. VH at 2 and 8 weeks, respectively). After 2 weeks of treatment, CsA animals developed a significant interstitial fibrosis, with preserved RBF, even when it was assessed 2 hr after CsA injection. There was a significant increase in the immunostaining for TGF-beta in the juxtaglomerular arterioles in CsA-treated rats (48.6+/-3.8 vs. 35.1+/-1.1%, CsA vs. VH at 2 weeks, P<0.05 and 59.0+/-3.2 vs. 37.0+/-2.1%, CsA vs. VH at 8 weeks, P=0.0001). A significant and progressive GFR decrease followed the renal structural injury of CsA treatment. Arteriolar and glomerular anatomic injury were not found throughout the study. CONCLUSIONS: Low CsA doses might generate interstitial fibrosis without any decrease in RBF or structural arteriolar lesion evidence, possibly through early macrophage influx and increased TGF-beta expression. It clearly seems that CsA-induced ischemia and tubulointerstitial injury may occur independently, suggesting that chronic CsA nephrotoxicity may be very hard to prevent or even not be preventable at all.     

Differentiation between chronic rejection and chronic cyclosporine toxicity by analysis of renal cortical mRNA

BACKGROUND: In kidney transplantation, chronic allograft nephropathy (CAN) is the major cause of graft loss. Causes of CAN include chronic rejection and chronic cyclosporine A (CsA) nephrotoxicity. It is necessary to differentiate between these two entities in order to apply the appropriate therapeutic regimen for the individual patient, but this is hampered by the lack of discriminating functional and morphologic parameters. We investigated whether renal cortical mRNA levels for several matrix proteins can serve as discriminating parameters. METHODS: Patients with chronic rejection (N= 19) and chronic CsA toxicity (N= 17) were selected by clinical and histologic criteria. Protocol biopsies without histologic abnormalities, taken at 6 months after transplantation from patients receiving CsA, were used as controls (N= 6). Total RNA was extracted from the renal biopsy tissue, and mRNA levels of transforming growth factor-beta (TGF-beta) and the extracellular matrix (ECM) molecules collagen Ialpha1, IIIalpha1, IValpha3, decorin, fibronectin, and laminin beta2 were measured by real-time polymerase chain reaction (PCR). RESULTS: In both patient groups, the mean collagen IValpha3 and fibronectin mRNA levels were significantly elevated compared to those in controls, whereas only in CsA toxicity were the laminin beta2 and TGF-beta mRNA levels significantly increased. The increase of laminin beta2 and TGF-beta mRNA levels was significantly higher in the CsA toxicity group than in the chronic rejection group (P < 0.001 and P= 0.004, respectively). Receiver-operating characteristic (ROC) curve analysis showed that with a 15.6-fold increase in laminin beta2 mRNA expression as cut-off point, the presence of CsA toxicity could be predicted with an 87% sensitivity and an 88% specificity. CONCLUSION: Renal laminin beta2 and TGF-beta mRNA levels can be used to differentiate between chronic rejection and chronic CsA toxicity in renal transplants. The method of mRNA quantification might be applicable as an additional diagnostic tool in clinical practice.     

Human allograft arterial injury is ameliorated by sirolimus and cyclosporine and correlates with suppression of interferon-gamma

BACKGROUND: Chronic allograft dysfunction may result from arterial injury, manifest as transplant arteriosclerosis (TA). This represents an important factor limiting long-term outcomes after heart and kidney transplantation; a relationship between acute allograft arterial injury and TA has been suggested. We have used SCID/bg mice bearing transplanted human artery, inoculated with allogeneic human PBMC to study arteriopathy in human vessels. Earlier work demonstrated arteriopathy similar to that observed clinically, and identified interferon-gamma as a mediator of the process. This study evaluated whether sirolimus (SRL), with cyclosporine A (CsA) or alone, affects TA, and examined possible mechanisms of action. METHODS: CB17/SCID/bg mice were transplanted with human arteries replacing the abdominal aorta; reconstituted with allogeneic human PBMC. Controls received vehicle alone for comparison with mice given CsA (5 mg/kg/d), SRL (0.1 or 0.5 mg/kg/d), or CsA (5 mg/kg/d) plus SRL (0.1 mg/kg/d). Transplant arteries were examined 28 days later by histology and immunohistochemistry; circulating human interferon-gamma was evaluated by ELISA, and intragraft interferon-gamma mRNA by qRT-PCR. RESULTS: The characteristic TA was modestly reduced by CsA or low-dose SRL, but eliminated by combination CsA plus SRL or higher dose SRL alone. Circulating interferon-gamma was reduced by CsA, but inhibition was dramatic with SRL alone or combined with CsA. Intragraft interferon-gamma and HLA-DR expression were moderately reduced by CsA or SRL, and eliminated with combined CsA plus SRL. CONCLUSIONS: SRL plus CsA prevented allograft arteriopathy, correlating with suppression of intragraft interferon-gamma, suggesting that SRL effects may result from anti-inflammatory consequences from inhibiting interferon-gamma.     

Sirolimus reduces the incidence of acute rejection episodes despite lower cyclosporine doses in caucasian recipients of mismatched primary renal allografts: a phase II trial. Rapamune Study Group

BACKGROUND: The novel agent sirolimus (SRL; Rapamune; rapamycin) inhibits the immune response by a mechanism distinct from those of calcineurin antagonists or antimetabolites. This randomized, controlled, multicenter, single blind, phase II trial examined the combination of SRL, steroids, and full versus reduced doses of cyclosporine (CsA) for prophylaxis of acute renal allograft rejection. METHODS: A total of 149 recipients of mismatched cadaveric- or living-donor primary renal allografts were randomized into six groups. Three groups received placebo or 1 or 3 mg/m2/day SRL, as well as steroids and full-dose CsA (Sandimmune). Three groups received steroids, reduced-dose CsA (target trough level 50% of full-dose range), and 1, 3, or 5 mg/m2/day SRL. RESULTS: The incidence of biopsy-proven acute rejection episodes within the first 6 months after transplant was reduced from 32.0% in the control group to 8.5% in patients receiving SRL (1 or 3 mg/m2/day) and full-dose Sandimmune CsA (P=0.018). Similar low rates of acute rejection episodes were observed among non-African-Americans, but not African-Americans, treated with SRL and reduced-dose Sandimmune CsA. Despite the augmented immunosuppression, 1-year patient and graft survival rates did not differ significantly across groups. Adverse effects attributable to CsA, including hypertension and new-onset diabetes mellitus, were not exacerbated by SRL. Except for an increased incidence of pneumonia among patients receiving full-dose CsA and 3 mg/m2/day SRL, the incidences of opportunistic infections were similar in all treatment groups. Although SRL produced more frequent, but reversible, hematological and lipid abnormalities, it had no apparent nephrotoxic effects to exacerbate CsA-induced renal dysfunction. CONCLUSIONS: SRL in combination with CsA and steroids not only lowers the incidence of biopsy-proven acute renal allograft rejection episodes, but also may permit CsA sparing, at least among Caucasian patients, without an increased risk of rejection.     

Sirolimus-Induced Ulceration of the Small Bowel in Islet Transplant Recipients: Report of Two Cases

Sirolimus (SRL) has been used for most islet recipients over the past 5 years. It provides balanced immunosuppression in combination with low-dose calcineurin inhibitors, while avoiding corticosteroids. This regimen decreases the risk of nephrotoxicity, neurotoxicity and diabetogenicity. SRL has also been used selectively in clinical liver and kidney transplantation. A number of common side effects including anemia, leucopenia, thrombocytopenia, hypercholesterolemia, mouth ulceration, joint pain, extremity edema and impaired wound healing have been associated with the use of SRL. As SRL is used more frequently, evidence has been gathered on its rare but severe side effects. We report 2 patients who underwent islet transplantation and developed symptomatic small bowel ulceration that resolved after complete withdrawal of SRL. Although small bowel ulceration is rare, it can potentially progress to more serious complications if not treated adequately. Our experience highlights an uncommon but potentially serious adverse effect of high-dose SRL in islet recipients.     

High-and Low-dose Regimens of Cyclosporin in Renal Transplantation: Immunosuppressive Efficacy and Side-effects

The immunosuppressive effectiveness and nephrotoxic side-effectsof either high-dose cyclosporin (CsA) (16 mg/kg per day) orlow-dose (9mg/kg per day) in combination with azathioprine (Aza)(1 mg/kg per day) were studied in 80 renal transplant patientswho also received low-dose corticosteroids. At 3 months, patientswho received high-dose CsA were randomly assigned to eithercontinuation of CsA or conversion to Aza, whereas in the triple-therapygroup either CsA or Aza was discontinued. No differences inpatient (97.5%) or graft survival (90%–92.5%) were foundat 1 year. There were no differences in the incidence of primarynon-functioning kidneys. The incidence of acute rejection episodeswas 45% in the high-dose CsA group and 55% in the group treatedwith low CsA doses together with Aza (not significant). At 3months the mean creatinine clearance was 60±4ml/min (mean±SEM)in the high-dose group (mean cumulative CsA dose 0.96 g/kg)compared with 55±3 ml/min in the low-dose group (meancumulative CsA dose 0.60 g/kg). At 1 year no differences inthe degree of proteinuria or the incidence of hypertension wasfound between the different groups. The best mean creatinineclearance at 1 year (77±5 ml/min) was found in patientswho received high doses of CsA for 3 months followed by conversion.     

Sirolimus in Combination with Tacrolimus Is Associated with Worse Renal Allograft Survival Compared to Mycophenolate Mofetil Combined with Tacrolimus

Cyclosporine (CsA) nephrotoxicity is enhanced by sirolimus (SRL). Tacrolimus is perceived to be less nephrotoxic than CsA, and therefore, CsA has been largely replaced by tacrolimus (TAC) when calcineurin inhibitors are used with SRL. We analyzed 44 915 adult renal transplants in the Scientific Renal Transplant Registry (SRTR) from 2000 to 2004. Three thousand five hundred twenty-four (7.8%) patients received a baseline immunosuppressive regimen of TAC/SRL, with an inferior overall (log-rank p<0.001) and death-censored graft survival (p<0.001) as compared to TAC/MMF (N=27 007). This effect was confirmed in multivariate Cox models; the adjusted hazard ratio (AHR) for overall graft loss with TAC/SRL was 1.47 (95% CI=1.32, 1.63) and for CsA/SRL 1.38 (95% CI=1.20, 1.59) relative to TAC/MMF. These effects were most apparent in high-risk transplants. Six-month acute rejection rates were low (11.5-12.6%) and not different between groups. In summary, national data indicate that TAC/SRL as compared to TAC/MMF is associated with significantly worse renal allograft survival in all subgroups of patients and, in particular, higher-risk transplants. These results have to be interpreted in the context of the inherent limitations of any retrospective database analysis and evaluated in context with data from prospective clinical trials.     

Kidney function and morphology after short-term combination therapy with cyclosporine A, tacrolimus and sirolimus in the rat.

BACKGROUND: Sirolimus (SRL) may supplement calcineurin inhibitors in clinical organ transplantation. These are nephrotoxic, but SRL seems to act differently displaying only minor nephrotoxic effects, although this question is still open. In a number of treatment protocols where SRL was combined with a calcineurin inhibitor indications of a synergistic nephrotoxic effect were described. The aim of this study was to examine further the renal function, including morphological analysis of the kidneys of male Sprague-Dawley rats treated with either cyclosporine A (CsA), tacrolimus (FK506) or SRL as monotherapies or in different combinations. METHODS: For a period of 2 weeks, CsA 15 mg/kg/day (given orally), FK506 3.0 mg/kg/day (given orally) or SRL 0.4 mg/kg/day (given intraperitoneally) was administered once a day as these doses have earlier been found to achieve a significant immunosuppressive effect in Sprague-Dawley rats. In the 'conscious catheterized rat' model, the glomerular filtration rate (GFR) was measured as the clearance of Cr(EDTA). The morphological analysis of the kidneys included a semi-quantitative scoring system analysing the degree of striped fibrosis, subcapsular fibrosis and the number of basophilic tubules, plus an additional stereological analysis of the total grade of fibrosis in the cortex stained with Sirius Red. RESULTS: CsA, FK506 and SRL all significantly decreased the GFR. A further deterioration was seen when CsA was combined with either FK506 or SRL, whereas the GFR remained unchanged in the group treated with FK506 plus SRL when compared with treatment with any of the single substances. The morphological changes presented a similar pattern. The semi-quantitative scoring was significantly worst in the group treated with CsA plus SRL (P<0.001 compared with controls) and the analysis of the total grade of fibrosis also showed the highest proportion in the same group and was significantly different from controls (P<0.02). The FK506 plus SRL combination showed only a marginally higher degree of fibrosis as compared with controls (P=0.05). CONCLUSION: This rat study demonstrated a synergistic nephrotoxic effect of CsA plus SRL, whereas FK506 plus SRL was better tolerated.     

雷帕霉素对环孢素A诱导的慢性肾毒性的影响

目的　了解雷帕霉素 (RPM)对环孢素A(CsA)诱导的慢性肾毒性的影响。方法　对进低盐饮食的大鼠给予RPM与CsA溶剂、RPM (0 .5mg·kg-1·d-1与 1mg·kg-1·d-1)、CsA (4mg·kg-1·d-1与 8mg·kg-1·d-1)以及两者联用 ,均用药 2 8d。结果　接受RPM 1mg·kg-1·d-1的大鼠血糖明显升高 ,加重CsA(4mg·kg-1·d-1)诱导的慢性肾毒性作用 ;而亚治疗剂量的RPM (0 .5mg·kg-1·d-1)与CsA(4mg·kg-1·d-1)联用只引起轻度的血糖上升及肾小管细胞受损与间质纤维化 ,与前者相比 ,P <0 .0 5。治疗剂量的RPM(1mg·kg-1·d-1)与CsA(8mg·kg-1·d-1)联用则导致更为显著的肾功能受损、结构改变与高糖血症。结论　亚治疗剂量的RPM与CsA的联用可协同产生慢性肾毒性作用