Tacrolimus-induced Nephrotoxicity Research Articles

Immunosuppressant drug tacrolimus induced mitochondrial nephrotoxicity, modified PCNA and Bcl-2 expression attenuated by Ocimum basilicum L. in CD1 mice.

Tacrolimus (TAC) is used sporadically as an immunosuppressive agent for organ transplantation, but its clinical used is limited due to its marked nephrotoxicity. Ocimum basilicum L. (Lamiaceae) (OB) had been shown to possess antioxidant, anti-inflammatory and nephroprotective activity, and effective at improving renal inflammation and glomerular. In our study, we aim to evaluate the efficacy of the OB against TAC-induced mitochondrial nephrotoxicity in CD1 mice. Mice were randomly divided into four groups. Group 1 (control group); administered orally with normal saline (1 mL/kg) for two weeks; Group 2 (OB extract treated-group) (500 mg/kg b.wt) gavaged once/day for two weeks; Group 3 (TAC-treated group) (3 mg/kg b.wt, administered ip once a day for two weeks); and Group 4; (TAC plus OB extract treated-group). Tacrolimus-induced nephrotoxicity was assessed biochemically and histopathologically. The OB extract was high in phenolic content (50.3 mg/g of gallic acid equivalent), total flavonoids (14.5 mg/g CE equivalent). The potential antioxidant efficacy of the extract (IC50) was 24.5 μg/mL. OB pretreatment significantly improved the TAC-induced changes in biochemical markers of nephrotoxicity for instance blood urea nitrogen (BUN), creatinine, total protein, and albumin (P < 0.01, when compared with TAC treated group). Also, it significantly restored the increase activities of TBARS, protein carbonyl (PC) (P < 0.001, when compared to healthy control group) and decreased activities of nonprotein thiol (NP-SH) levels, Mn-superoxide dismutase (Mn-SOD) and glutathione peroxidase (GPx) antioxidants of mitochondria. The nephroprotective efficacy of the OB leaves extract was further evident by histopathological analysis together with the PCNA-ir and Bcl2. The upshot of the present study revealed that the OB possessed significant antioxidant and nephroprotective activity and had a preventive effect on the biochemical alterations and histological changes in TAC-treated mice.

The Protective Effect of Febuxostat on Chronic Tacrolimus-Induced Nephrotoxicity in Rats

Background: The use of calcineurin inhibitors is a well-known risk factor for hyperuricemia in kidney transplant recipients. We evaluated the effect of febuxostat (Fx), a new uric acid-lowering drug, on hyperuricemia and renal injury in an experimental model of chronic tacrolimus (Tac)-induced nephropathy. Methods: Chronic Tac nephropathy was induced by administering Tac (1.5 mg/kg/day) to rats on a low-salt diet (0.05%) with oxonic acid (OA, 2%, 0.2 g/kg/day) for 28 days. Two doses of Fx (5 and 10 mg/kg) were concomitantly administered with Tac or vehicle (Vh). We evaluated the effect of Fx on hyperuricemia by measuring serum uric acid (SUA) levels, fractional excretion of uric acid (FEUA), and urate transporters in Tac-induced nephropathy. The effects of Fx on Tac-induced renal injury were evaluated in terms of renal function and arteriolopathy, tubulointerstitial fibrosis, inflammation, and apoptosis. We evaluated oxidative stress as a protective mechanism via xanthine oxidase (XO) activity, and as a marker of oxidative stress (via evaluation of levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 4-hydroxy-2-hexenal (4-HHE)). Results: The Tac group showed higher SUA levels and lower FEUA than did the Vh group, but Fx treatment significantly decreased SUA levels in a dose-dependent manner, with an increase of FEUA at a high dose (10 mg/kg). Tac treatment increased urate-anion exchanger 1 and decreased organic anion transporter type 1 expression in renal tubular cells, but Fx treatment reversed the effects on those transporters. Impaired renal function and histological injury (interstitial fibrosis, inflammation, and arteriolopathy) in the Tac group were markedly improved by Fx administration. Increases in apoptotic cell death and activation of proapoptotic caspase-3 by Tac were remarkably decreased by Fx treatment. Tac administration increased the activity of XO in kidney tissue and serum, and the levels of 8-OHdG in urine and 8-OHdG and 4-HHE of kidney tissue, but combined treatment with Fx decreased the levels of these parameters. Conclusions: Fx is effective in controlling hyperuricemia and in preventing Tac-induced renal injury, via a reduction of oxidative stress. Therefore, a targeted therapy aimed at inhibiting uric acid by Fx may be a useful approach in the management of the progression of nephropathy in renal transplant patients treated with Tac.

Inhibition of dipeptidyl peptidase IV protects tacrolimus-induced kidney injury

Accumulating evidence shows that a gut-released hormone, the glucagon-like peptide-1 (GLP-1), has not only a glucose-lowering effect but also a renoprotective effect against kidney injury. In this study, we investigated whether a dipeptidyl peptidase (DPP) IV inhibitor has a protective effect against tacrolimus-induced renal injury. Rats were treated with tacrolimus (1.5 mg/kg, subcutaneously) and the DPP IV inhibitor MK0626 (10 or 20 mg/kg, oral gavage) for 4 weeks. MK0626 treatment attenuated tacrolimus-induced renal dysfunction, tubulointerstitial fibrosis, and arteriolopathy. Moreover, these improvements were accompanied by a reduction in oxidative stress and apoptosis. MK0626 treatment increased the blood level of GLP-1 and the level of its receptor in tissue sections but did not alter the levels of other DPP IV substrates, such as neuropeptide Y and the stromal cell-derived factor-1. These data suggest that DPP IV inhibition has an important role in the renoprotection against tacrolimus-induced nephrotoxicity via antioxidative and antiapoptotic effects and preservation of the GLP-1 system.

Antiproteinuric Effects of Green Tea Extract on Tacrolimus-Induced Nephrotoxicity in Mice

IntroductionIt has been reported that proteinuria is an early predictive marker in detection of tacrolimus (TAC) nephrotoxicity. The aim of this study was to investigate the antiproteinuric effects of green tea extract (GTE) on TAC-induced acute nephrotoxicity in mice. MethodsThe mice (n = 20) were divided into 4 groups (n = 5 per group); control group mice were intraperitoneally (IP) injected with 0.9% saline, TAC group mice were IP injected with TAC 1 mg/kg, and inducible nitric oxide synthase (iNOS) inhibitor group mice were given in addition NG-nitro-L-arginine-methyl ester 12 mmol/L by subcutaneous injection. TAC-GTE group mice were given TAC by IP injection and GTE 100 mg/kg by subcutaneous injection. ResultsThe 24-hour urine protein amounts were significantly increased in TAC group mice (36.1 ± 9.9 mg/d) compared with control group mice (13.3 ± 5.4 mg/d) and significantly decreased in TAC-GTE group mice (19.1 ± 6.9 mg/d, P < .01) compared with TAC group mice. The nitric oxide (NO) production by TAC was significantly suppressed by GTE and iNOS inhibitor injection. Renal tissue malondialdehyde (MDA) level was significantly increased in the TAC group compared with the control group and was significantly decreased in the TAC-GTE group compared with that of the TAC group. The antioxidant enzyme activities of superoxide dismutase and catalase were significantly suppressed in the TAC group compared with the control group and were restored in the GTE injection group. ConclusionsGTE treatment has beneficial antiproteinuric effects on TAC-induced acute renal injury in mice.

Arteriosclerosis in zero-time biopsy is a risk factor for tacrolimus-induced chronic nephrotoxicity.

Calcineurin inhibitors reduce the acute rejection rate and greatly improve renal allograft survival. However, they are associated with some adverse events, including nephrotoxicity, a risk factor for allograft failure. Chronic calcineurin inhibitor-induced nephrotoxicity causes irreversible damage to renal components, such as arteriolar hyaline thickening. The aim of this study is to investigate the risk factors for tacrolimus-induced chronic nephrotoxicity using zero-time biopsy specimens. Between January 2001 and December 2010, 483 patients who underwent living-related kidney transplantation and had also been placed on a tacrolimus-based regimen were enrolled in this study. There were 1859 specimens evaluated comprising 483 zero-time biopsy specimens and 1376 protocol and for-cause biopsy specimens. De novo arteriolar hyaline thickening due to tacrolimus-induced chronic nephrotoxicity was scored according to the Banff classification aah score. In this study, tacrolimus-induced nephrotoxicity was defined as a positive aah score. Of the 483 patients, 108 patients (22.4%) had biopsy-proven tacrolimus-induced chronic nephrotoxicity. Multivariate analysis showed that interlobular arteriosclerosis proven by zero-time biopsy (OR: 2.23, 95%CI: 1.38-3.58, P < 0.01) and acute rejection episodes (OR: 1.58, 95%CI: 1.00-2.47, P = 0.04) were independent risk factors for tacrolimus-induced chronic nephrotoxicity. However, tacrolimus-induced chronic nephrotoxicity did not affect long-term graft survival. This is the first report showing that arteriosclerosis in zero-time biopsy specimens is a risk factor for histological tacrolimus-induced chronic nephrotoxicity.

Treatment with aliskiren ameliorates tacrolimus-induced nephrotoxicity in rats.

Tacrolimus is frequently used as immunosuppressive agent in organ transplantation but its clinical use is limited due to its marked nephrotoxicity. Male Wistar albino rats weighing 150-200 g (10-12 weeks old) were used. Animals were divided into four groups. Group 1 served as control group and received normal saline, group 2 served as toxic group and received 2 mg/kg tacrolimus i.p., group 3 served as treatment group and received 2 mg/kg tacrolimus i.p. followed by 2 mg/kg aliskiren orally and group 4 served as drug per se group and received 2 mg/kg aliskiren orally. Tacrolimus-induced nephrotoxicity was assessed biochemically and histopathologically. Treatment with aliskiren decreased the tacrolimus-induced changes in biochemical markers of nephrotoxicity such as blood urea nitrogen and creatinine. Aliskiren also attenuated the effects of tacrolimus on oxidative stress parameters such as malondialdehyde, reduced glutathione and catalase. Histopathological and ultrastructural studies showed that aliskiren attenuated tacrolimus-induced renal damage. These results suggest that aliskiren has protective effects against tacrolimus-induced nephrotoxicity; implying that renin inhibitor may counteract nephrotic syndrome associated with immunosuppressant use.

Olmesartan attenuates tacrolimus-induced biochemical and ultrastructural changes in rat kidney tissue.

Tacrolimus, a calcineurin inhibitor, is clinically used as an immunosuppressive agent in organ transplantation, but its use is limited due to its marked nephrotoxicity. The present study investigated the effect of olmesartan (angiotensin receptor blocker) on tacrolimus-induced nephrotoxicity in rats. A total of 24 rats were divided into four groups, which included control, tacrolimus, tacrolimus + olmesartan, and olmesartan groups. Tacrolimus-induced nephrotoxicity was assessed biochemically and histopathologically. Tacrolimus significantly increased BUN and creatinine level. Treatment with olmesartan reversed tacrolimus-induced changes in the biochemical markers (BUN and creatinine) of nephrotoxicity. Tacrolimus significantly decreased GSH level and catalase activity while increasing MDA level. Olmesartan also attenuated the effects of tacrolimus on MDA, GSH, and catalase. In tacrolimus group histological examination showed marked changes in renal tubule, mitochondria, and podocyte processes. Histopathological and ultrastructural studies showed that treatment with olmesartan prevented tacrolimus-induced renal damage. These results suggest that olmesartan has protective effects on tacrolimus-induced nephrotoxicity, implying that RAS might be playing role in tacrolimus-induced nephrotoxicity.

Measurement and Compartmental Modeling of the Effect of CYP3A5 Gene Variation on Systemic and Intrarenal Tacrolimus Disposition

We evaluated the hypothesis that cytochrome P450 3A5 (CYP3A5) expression can affect intrarenal tacrolimus accumulation. Tacrolimus was administered orally to 24 healthy volunteers who were selected on the basis of their CYP3A5 genotype. As compared with CYP3A5 nonexpressors, expressors had a 1.6-fold higher oral tacrolimus clearance and 2.0- to 2.7-fold higher metabolite/parent area under the curve (AUC) ratios for 31-desmethyl tacrolimus (31-DMT), 12-hydroxy tacrolimus, and 13-desmethyl tacrolimus (13-DMT). In addition, the apparent urinary tacrolimus clearance was 36% lower in CYP3A5 expressors as compared with nonexpressors. To explore the mechanism behind this observation, we developed a semiphysiological model of renal tacrolimus disposition and predicted that tacrolimus exposure in the renal epithelium of CYP3A5 expressors is 53% of that for CYP3A5 nonexpressors, when normalized to blood AUC. These data suggest that, at steady state, intrarenal accumulation of tacrolimus and its primary metabolites will depend on the CYP3A5 genotype of the liver and kidneys. This may contribute to interpatient differences in the risk of tacrolimus-induced nephrotoxicity.

Tacrolimus-induced nephrotoxicity and genetic variability: A review

Calcineurin inhibition (CNI) is the mainstay of immunosuppressant therapy for most solid organ transplant patients. High tacrolimus levels are related with acute nephrotoxicity, but the relationship with chronic toxicity is less clear. Variation in disposition of tacrolimus is associated with genetic variation in CYP3A5. Hence, could genetic variation in CYP3A5 or other genes involved in tacrolimus disposition and effect be associated with a risk for tacrolimus-induced nephrotoxicity? To perform a review of the literature and to identify if genetic variation in CYP3A5 or other genes involved in tacrolimus disposition or effect may be associated with tacrolimus-induced nephrotoxicity and/or renal dysfunction in solid organ transplant recipients. Pubmed/Medline, Embase and Google were searched from their inception till November 8th 2010 with the search terms 'tacrolimus', 'genetics', and 'nephrotoxicity' or 'renal dysfunction'. References of relevant articles were screened as well. We identified 13 relevant papers. In kidney recipients, associations between donor ABCB1, recipient CCR5 genotype and tacrolimus-induced nephrotoxicity were found. CYP3A5 genotype studies in kidney recipients yielded contradictory results. In liver recipients, a possible association between recipient ACE, CYP3A5, ABCB1 and CYP2C8 genetic polymorphisms and tacrolimus-induced nephrotoxicity was suggested. In heart recipients, TGF-β genetic polymorphisms were associated with tacrolimus-induced nephrotoxicity. The quality of the studies varied considerably. Limited evidence suggests that variation in genes involved in pharmacokinetics (ABCB1 and CYP3A5) and pharmacodynamics (TGF-β, CYP2C8, ACE, CCR5) of tacrolimus may impact a transplant recipients' risk to develop tacrolimus-induced nephrotoxicity across different transplant organ groups.

Insights into the possible mechanism of cyclosporine-induced chronic nephrotoxicity; arteriolopathy.

Dear Editor, I read with great interest the recent contribution by Uz et al. (1) that demonstrated the protective effects of erdosteine on cyclosporine (CsA)-induced chronic nephrotoxicity in rats. The authors however, did not suggest the possible mechanism of nephrotoxicity or the recent reports concerning the action of antioxidants on nephrotoxicity. I would like to add some considerations on the noteworthy results using antioxidants based on the mechanism of CsA-induced chronic nephropathy. Excessive free radical production has been attributed to inadequate renal perfusion and hypoxia-reoxygenation injury is a well-known prerequisite for chronic nephrotoxicity by the calcineurin inhibitor. CsA-induced chronic nephropathy is characterized not only by vasoconstriction but also by the development of irreversible structural damage including arteriolopathy and tubulointerstitial fibrosis (2). Although most patients do not exhibit nephropathy as a result of vasoconstrictive effects (3) which is the acute unequivocal consequence of CsA (4), arteriolopathy is thought to predispose patients to interstitial fibrosis with tubular atrophy. Therefore, arteriolar vasoconstriction is responsible for both hypertension and compromised glomerular filtration rates that invariably lead to chronic kidney disease over time. Activation of the renin-angiotensin-aldosterone system (RAAS) plays an important role in the pathogenesis of chronic CsA-induced nephropathy. As highlighted in recent reports, it has been suggested that aldosterone plays a central role in the pathogenesis of CsA-induced nephrotoxicity (2). Ryu et al. (5) found that CsA treatment increases plasma renin activity and intrarenal renin levels, which induces nephrotoxicity, and that the protective effects of green tea extract on CsA-induced nephrotoxicity may block the RAAS. Han et al. (6) revealed the effect of sirolimus on CsA and tacrolimus-induced nephrotoxicity using renal expression of the KLOTHO gene, which is an anti-aging gene. Defects in this gene are accompanied by arteriosclerosis, and it accelerates calcineurin inhibitor-induced nephrotoxicity by increased reactive oxygen species (ROS) production. Two principle mechanisms of action have been proposed for antioxidants; one is a chain-breaking mechanism by electron donation (vitamin), and the other is the removal of ROS initiators by quenching chain initiating catalysts (erdosteine, green tea extract) (7). Besides, isoproterenol, which is a sympathomimetic, showed some protective effects by stimulating endogenous melatonin production in CsA-induced nephrotoxicity (8). Therefore, further studies are necessary to elucidate which molecular mechanisms are involved in the pathogenesis of CsA-induced nephropathy with special emphasis on arteriolopathy or the RAAS.

Severe symptomatic hyponatremia--an uncommon presentation of tacrolimus nephrotoxicity

Though tacrolimus-induced nephrotoxicity and hyperkalemia are well known, severe symptomatic hyponatremia is not commonly documented with its use. Here, we report a case of severe symptomatic hyponatremia in a renal transplant recipient on tacrolimus despite normal tacrolimus trough level. All other potential causes of hyponatremia were ruled out in this patient. This case highlights an uncommon aspect of tacrolimus nephrotoxicity, which we should keep in mind while following up a renal transplant recipient.

Prevention of diltiazem in tacrolimus-induced nephrotoxicity: experiment with rats

To study the nephrotoxicity induced by first oral administration of tacrolimus (FK506) and the prevention of diltiazem (Dil). 24 Sprague-Dawley male rats were randomly divided into 4 equal groups: control (n = 6), cyclosporine A (CsA) group (receiving CsA 25 mg.kg(-1).d(-1) so as to develop CsA-induced nephropathy model), FK506 group (receiving FK506 0.8 mg.kg(-1).d(-1), the common renal transplantation therapeutic dose, so as to develop FK506-induced nephropathy model), FK506 + Dil group (receiving CsA 0.8 mg.kg(-1).d(-1) and Dil 8 mg.kg(-1).d(-1)), and control group. Four weeks later body weight was measured, blood samples were collected to examine the creatinine, urea nitrogen, and uric acid, and urine samples were collected to examine the 24 h urine protein, uric acid, and creatinine. Then the rats were killed with their kidneys taken out to undergo histopathological examination. The urine creatinine levels of the CsA and FK506 groups were significantly lower than that of the control group (both P < 0.05), however, there was no significant difference in urine creatinine between the FK506 + Dil group and control group. The blood creatinine levels of both CsA and FK506 groups were significantly higher than those of the FK506 + Dil group and control group (all P < 0.05), however, there was no significant difference in blood creatinine between the FK506 + Dil group and control group. The urea nitrogen level of the CsA group was significantly higher than those of the other 3 groups (all P < 0.05). The creatinine clearance rates of the CsA and FK506 groups were both significantly lower than that of the control group (both P < 0.05), and the creatinine clearance rate of the FK506 + Dil group was between those of the FK506 group and control group, however, with significant differences with both of them. Histopathology examination showed cloudy swelling and vacuolization of the renal tubular epithelial cells in the CsA and FK506 groups. However, the pathological changes of the FK506 + Dil group were remarkably milder in comparison with these 2 groups. FK506 and CsA at the renal transplantation therapeutic dose induce nephrotoxicity. Diltiazem prevents FK506-induced nephrotoxicity.

NADPH oxidase subunits (NOX-1, p22phox, Rac-1) and tacrolimus-induced nephrotoxicity in a rat renal transplant model

NADPH oxidase subunits (NOX-1, p22phox, Rac-1) and tacrolimus-induced nephrotoxicity in a rat renal transplant model

NADPH oxidase subunits (NOX-1, p22phox, Rac-1) and tacrolimus-induced nephrotoxicity in a rat renal transplant model

TGF-beta and oxidative stress are known mediators of renal injury. However, the precise mechanisms by which TGF-beta and oxidative stress may be involved in the development of nephrotoxicity are not known. We examined whether anti-TGF-beta antibody limits nephrotoxicity produced by tacrolimus (TAC) and whether this altered genes that regulate oxidative stress. Renal transplants were performed in Wistar-Furth and Lewis rat strains. Groups included: isograft controls; untreated allografts; allografts treated with 0.25 mg/kg TAC till 90 days with or without 1.0 mg/kg anti-TGF-beta antibody or control antibody. Serum creatinine and BUN levels and renal histology were determined. Real time PCR and western analysis were used to quantify mRNA and protein expression. BUN and creatinine were elevated in TAC-treated rats. TAC increased expression of TGF-beta (37-fold) and NADPH oxidase subunits, NOX-1 (18-fold), p22(phox) (31-fold) and Rac-1 mRNA (20-fold), respectively. Contrariwise, expression of antioxidant genes, superoxide dismutase (SOD) and thioredoxin (TRX) was decreased. Anti-TGF-beta antibody but not control antibody reversed the TAC-induced changes in gene expression, renal histology and function. Our findings suggest a potential for anti-TGF-beta antibody as a novel adjunct therapeutic tool to prevent TAC-induced nephrotoxicity in transplant recipients. The mechanism of protection involves suppression of TGF-beta and the expression of genes that regulate oxidative stress. Moreover, the specific up-regulation of NOX-1, a non-phagocytic NADPH oxidase subunit and its reversal by anti-TGF-beta antibody strongly implicates for the first time the up-regulation of renal parenchymal cell NADPH oxidase in the aetiology of immunosuppression-induced nephrotoxicity.

Clinical Utility of Histological Features of Polyomavirus Allograft Nephropathy

The purpose of this study was to determine if histological features of polyomavirus allograft nephropathy (PVAN) are associated with the clinical presentation and outcomes of PVAN. We examined the histological features of initial and follow-up biopsies of 20 kidney and kidney-pancreas transplant recipients with PVAN during a time prior to routine surveillance. The subjects' demographics, clinical characteristics, and outcomes were compared based upon classification of histological features of PVAN on initial biopsy. Diabetes mellitus (45%) and a history of tacrolimus-induced nephrotoxicity (35%) appeared to be prevalent in subjects with PVAN. Although histological severity of PVAN did not predict or correlate with the clinical course of PVAN, subjects with pattern C on initial PVAN biopsy presented later posttransplant, had higher serum creatinine level at presentation, and had significant allograft deterioration at follow-up than subjects with either pattern A or B on initial biopsy. Resolution of PVAN was noted in 60% of follow-up biopsies and occurred more frequently in subjects with pattern B on initial biopsy. Most subjects developed chronic allograft nephropathy after PVAN and viral clearance did not abrogate the progression to chronic allograft nephropathy. These data indicate that histologic patterns of PVAN may have clinical correlation to disease presentation and prognosis.

Transforming Growth Factor-β1, Vascular Endothelial Growth Factor, and Bone Morphogenic Protein-7 Expression in Tacrolimus-Induced Nephrotoxicity in Rats

The aim of our study was to investigate transforming growth factor ( TGF)-β1, vascular endothelial growth factor ( VEGF), and bone morphogenic protein-7 ( BMP-7) expression in the rat model of chronic tacrolimus (TAC) toxicity compared to healthy controls. Seventeen male Wistar rats were divided into two groups: group 1 animals were healthy controls and Group 2 animals were treated with TAC (1 mg/kg per day intraperitoneally for 8 weeks). At the end of the study period the animals were sacrificed following renal function studies including blood urea nitrogen (BUN), serum creatinine, and creatinine clearance, and renal tissues were examined by light microscopy for the findings of tacrolimus toxicity, specifically for afferent arteriolopathy and interstitial fibrosis. TGF-β1, VEGF, and BMP-7 expression were assessed by semiquantative scoring of the immunohistochemically stained specimens. Mean TAC levels were 5.53 ± 2.38 ng/mL in group 2. BUN, creatinine levels, and creatinine clearance were 57.99 ± 11.13 vs 39.49 ± 5.64 mg/dL; 0.60 ± 0.16 vs 0.65 ± 0.09 mg/dL; 0.97 ± 0.39 vs 1.17 ± 0.32 mL/min in group 2 versus group 1. Only the BUN level was significantly higher in group 2 compared to group 1. Afferent arteriolopathy and interstitial fibrosis were significantly increased in group 2 compared to group 1. TGF-β1 and VEGF expression was significantly increased while BMP-7 expression was significantly decreased in group 2 versus group 1. In conclusion, our findings suggest that TAC-induced nephrotoxicity is associated with increased TGF-β1 and VEGF and decreased BMP-7 expression.

The Experimental Agent Pirfenidone Reduces Pro-Fibrotic Gene Expression in a Model of Tacrolimus-Induced Nephrotoxicity

Tacrolimus nephrotoxicity is thought to contribute to renal allograft dysfunction and subsequent failure, a process that is underpinned by alterations in mRNA expression of genes involved in matrix metabolism. The new anti-fibrotic pirfenidone was tested for its potential to reverse markers of renal dysfunction. Rats were salt-depleted before tacrolimus and pirfenidone treatment. Serum creatinine, urinary protein/creatinine ratio, extracellular matrix deposition (ECM), and mRNA expression of genes involved in matrix turnover were assessed. Tacrolimus reduced TGF-beta mRNA expression below control levels and treatment with pirfenidone at all doses did not alter this effect. Likewise, TIMP-1 mRNA expression was depressed by the addition of tacrolimus and pirfenidone caused a further decrease in expression. Collagen III, MMP-2, and MMP-9 expression was unchanged by tacrolimus, but pirfenidone reduced collagen III below control levels. ECM was slight (1-4%) and not significantly different between groups. These findings suggest that pirfenidone can attenuate the limited fibrotic potential of tacrolimus.

Benefit of theophylline administration in tacrolimus-induced nephrotoxicity in rats.

Tacrolimus (TAC), a widely used nephrotoxic calcineurin inhibitor, is associated with renal vasoconstriction possibly through adenosine receptor activation. Theophylline (THEO), an adenosine receptor inhibitor, protects against the nephrotoxicity of drugs associated with renal vasoconstriction. We hypothesized that coadministration of low dose THEO in rats would prevent TAC-induced nephrotoxicity. Sprague-Dawley rats pair-fed a low-sodium diet were randomized into three groups ( n=10/group): the control (CONTROL) group received the vehicle for both medications; the TAC group received TAC 6 mg/kg/day and vehicle; and the TAC+THEO group received TAC and THEO 17 mg/kg/day. On day 21, a timed urine collection was obtained for creatinine clearance. On day 22, serum creatinine, THEO and whole blood TAC concentrations were determined. One kidney was removed for formalin fixation and histological assessment. In the TAC group, serum creatinine increased while creatinine clearance decreased compared to CONTROL (0.3+/-0.0 vs. 0.4+/-0.0 mg/dl and 0.53+/-0.06 vs. 0.34+/-0.04 ml/min/100 g body weight respectively, p<0.05), while TAC+THEO did not differ from control. There were no significant differences in renal histology. Concurrent administration of low-dose THEO prevented the TAC-induced decline in renal function, consistent with a role for adenosine in TAC-induced nephrotoxicity.

Renin mRNA expression and renal dysfunction in tacrolimus-induced acute nephrotoxicity

Tacrolimus is a superior immunosuppressive agent and has markedly improved the short-term outcome of renal allografts. Despite the beneficial effects of maintaining immunotolerance in organ transplant recipients, it has well-characterized side effects on renal hemodynamics in the early phase. The mechanism of tacrolimus-induced acute nephrotoxicity is still unclear. The purpose of this study was to elucidate the role of renin-angiotensin system (RAS) in tacrolimus-induced acute nephrotoxicity. We examined the renal mRNA levels of renin in order to elucidate the relationship between plasma renin activity (PRA) and tacrolimus-induced renal dysfunction. Daily administration of tacrolimus (4 mg/kg/day) for 2 weeks in spontaneously hypertensive rats (SHR) significantly increased BUN and plasma creatinine (P-Cr) level, while endogenous creatinine clearance (Ccr) significantly decreased in tacrolimus treated rats. Regarding tubular function data, fractional excretion of Na (FENa) and fractional excretion of K were higher in the tacrolimus treated group. Renin mRNA levels in the renal cortex in tacrolimus treated rats significantly increased when compared to the vehicle-treated rats. Ccr level was inversely proportional to PRA, with a high correlation coeffecient. The rise in PRA significantly correlated with increase in FENa by liner regression. Therefore, the results indicate that RAS is involved in the tacrolimus-induced acute nephrotoxicity.

Effects of thymic hormone on reactive oxygen species-scavengers and renal function in tacrolimus-induced nephrotoxicity

The effects of a thymic hormone (Facteur thymique serique; FTS) on renal reactive oxygen species-scavenging enzymes or substances in heminephrectomized rats with and without tacrolimus-induced nephrotoxicity were studied. Rats received both oral dose of tacrolimus (5 mg/kg/day) and subcutaneous administration of three dosages of FTS (5, 50, and 250 μg/kg/day) over 28 days (Group A). In Group B, they received three dosages of FTS alone (0.5, 5, and 50 μg/kg/day) or FTS 50 μg/kg/day with tacrolimus over 28 days. Each dose of FTS (Group A) partially elevated renal creatinine clearances. Tacrolimus enhanced renal glutathione reductase (GSH-R) activities and glutathione (GSH) and depressed catalase (CAT) activities. FTS increased GSH levels and GSH-R activities. Although FTS alone did not change CAT activities, CAT activities recovered as a result of concomitant use of FTS (Groups A and B). A significant positive correlation was found between CAT activity and creatinine clearance. These findings suggest that FTS is useful for the prevention of tacrolimus-induced nephrotoxicity, and that the increase of renal CAT activity in the defense mechanism of FTS might be important for cell protection against active oxygen species.