Expression of apoptosis regulatory genes in chronic cyclosporine nephrotoxicity favors apoptosis

Mitochondrial SIRT3 as a protective factor against cyclosporine A-induced nephrotoxicity

Sirtuin3 (SIRT3), a mitochondrial deacetylase, has been shown to be involved in various kidney diseases. In this study, we aimed to clarify the role of SIRT3 in cyclosporine-induced nephrotoxicity and the associated mitochondrial dysfunction. Madin-Darby canine kidney (MDCK) cells were transfected with Flag-tagged SIRT3 for SIRT3 overexpression or SIRT3 siRNA for the inhibition of SIRT3. Subsequently, the cells were treated with cyclosporine A (CsA) or vehicle. Wild-type and SIRT3 knockout (KO) mice were randomly assigned to receive cyclosporine A or olive oil. Furthermore, SIRT3 activator, honokiol, was treated alongside CsA to wild type mice. Our results revealed that CsA treatment inhibited mitochondrial SIRT3 expression in MDCK cells. Inhibition of SIRT3 through siRNA transfection exacerbated apoptosis, impaired the expression of the AMP-activated protein kinase-peroxisome proliferator-activated receptor gamma coactivator 1 alpha (AMPK-PGC1α) pathway, and worsened mitochondrial dysfunction induced by CsA treatment. Conversely, overexpression of SIRT3 through Flag-tagged SIRT3 transfection ameliorated apoptosis, increased the expression of mitochondrial superoxide dismutase 2, and restored the mitochondrial regulator pathway, AMPK-PGC1α. In SIRT3 KO mice, CsA treatment led to aggravated kidney dysfunction, increased kidney tubular injury, and accumulation of oxidative end products indicative of oxidative stress injury. Meanwhile, SIRT3 activation in vivo significantly mitigated these adverse effects, improving kidney function, reducing oxidative stress markers, and enhancing mitochondrial health following CsA treatment. Overall, our findings suggest that SIRT3 plays a protective role in alleviating mitochondrial dysfunction caused by CsA through the activation of the AMPK-PGC1α pathway, thereby preventing further kidney injury.

Cyclosporine-induced kidney damage was halted by sitagliptin and hesperidin via increasing Nrf2 and suppressing TNF-α, NF-κB, and Bax

Cyclosporine A (CsA) is employed for organ transplantation and autoimmune disorders. Nephrotoxicity is a serious side effect that hampers the therapeutic use of CsA. Hesperidin and sitagliptin were investigated for their antioxidant, anti-inflammatory, and tissue-protective properties. We aimed to investigate and compare the possible nephroprotective effects of hesperidin and sitagliptin. Male Wistar rats were utilized for induction of CsA nephrotoxicity (20 mg/kg/day, intraperitoneally for 7 days). Animals were treated with sitagliptin (10 mg/kg/day, orally for 14 days) or hesperidin (200 mg/kg/day, orally for 14 days). Blood urea, serum creatinine, albumin, cystatin-C (CYS-C), myeloperoxidase (MPO), and glucose were measured. The renal malondialdehyde (MDA), glutathione (GSH), catalase, and SOD were estimated. Renal TNF-α protein expression was evaluated. Histopathological examination and immunostaining study of Bax, Nrf-2, and NF-κB were performed. Sitagliptin or hesperidin attenuated CsA-mediated elevations of blood urea, serum creatinine, CYS-C, glucose, renal MDA, and MPO, and preserved the serum albumin, renal catalase, SOD, and GSH. They reduced the expressions of TNF-α, Bax, NF-κB, and pathological kidney damage. Nrf2 expression in the kidney was raised. Hesperidin or sitagliptin could protect the kidney against CsA through the mitigation of oxidative stress, apoptosis, and inflammation. Sitagliptin proved to be more beneficial than hesperidin.

Role of cyclosporin A in the treatment of kidney disease and nephrotoxicity

The clinical use of cyclosporin A (CsA) has led to significant advances and achievements in the field of transplantation and immune diseases. However, the nephrotoxicity of CsA is a major concern in current immunosuppression regimens. CsA causes abnormal kidney function while treating kidney disease, causing problems for clinicians and patients. Evidence of CsA nephrotoxicity is almost always present in transplant recipients after long-term CsA administration (up to 10 years), and similar phenomena occur with other calcineurin inhibitors. In this review, we summarize the mechanisms and influencing factors of CsA for the treatment of primary nephrotic syndrome. The mechanisms of CsA nephrotoxicity, clinical-pathological features, diagnosis, prevention strategies, and risk factors are summarized. We discuss the correlates and mechanisms of the switch between kidney disease prevention and nephrotoxicity of CsA to better understand the function of CsA in the kidney and to provide a basis for the prevention and treatment of CsA nephrotoxicity.

Melanocortin System in Kidney Homeostasis and Disease: Novel Therapeutic Opportunities

Melanocortin peptides, melanocortin receptors, melanocortin receptor accessory proteins, and endogenous antagonists of melanocortin receptors are the key components constituting the melanocortin hormone system, one of the most complex and important hormonal systems in our body. A plethora of evidence suggests that melanocortins possess a protective activity in a variety of kidney diseases in both rodent models and human patients. In particular, the steroidogenic melanocortin peptide adrenocorticotropic hormone (ACTH), has been shown to exert a beneficial effect in a number of kidney diseases, possibly via a mechanism independent of its steroidogenic activity. In patients with steroid-resistant nephrotic glomerulopathy, ACTH monotherapy is still effective in inducing proteinuria remission. This has inspired research on potential implications of the melanocortin system in glomerular diseases. However, our understanding of the role of the melanocortinergic pathway in kidney disease is very limited, and there are still huge unknowns to be explored. The most controversial among these is the identification of effector cells in the kidney as well as the melanocortin receptors responsible for conveying the renoprotective action. This review article introduces the melanocortin hormone system, summarizes the existing evidence for the expression of melanocortin receptors in the kidney, and evaluates the potential strategy of melanocortin therapy for kidney disease.

Dehydroxymethylepoxyquinomicin, a novel nuclear factor-κB inhibitor, prevents the development of cyclosporine A nephrotoxicity in a rat model

Background

Cyclosporine A (CsA) is an essential immunosuppressant in organ transplantation. However, its chronic nephrotoxicity is an obstacle to long allograft survival that has not been overcome. Nuclear factor-κB (NF-κB) is activated in the renal tissue in CsA nephropathy. In this study, we aimed to investigate the effect of the specific NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), in a rat model of CsA nephrotoxicity.

Methods

We administered CsA (15 mg/kg) daily for 28 days to Sprague-Dawley rats that underwent 5/6 nephrectomy under a low-salt diet. We administered DHMEQ (8 mg/kg) simultaneously with CsA to the treatment group, daily for 28 days and evaluated its effect on CsA nephrotoxicity.

Results

DHMEQ significantly inhibited NF-κB activation and nuclear translocation due to CsA treatment. Elevated serum urea nitrogen and creatinine levels due to repeated CsA administration were significantly decreased by DHMEQ treatment (serum urea nitrogen in CsA + DHMEQ vs CsA vs control, 69 ± 6.4 vs 113.5 ± 8.8 vs 43.1 ± 1.1 mg/dL, respectively, p < 0.0001; serum creatinine in CsA + DHMEQ vs CsA vs control, 0.75 ± 0.02 vs 0.91 ± 0.02 vs 0.49 ± 0.02 mg/dL, respectively, p < 0.0001), and creatinine clearance was restored in the treatment group (CsA + DHMEQ vs CsA vs control, 2.57 ± 0.09 vs 1.94 ± 0.12 vs 4.61 ± 0.18 ml/min/kg, respectively, p < 0.0001). However, DHMEQ treatment did not alter the inhibitory effect of CsA on urinary protein secretion. The development of renal fibrosis due to chronic CsA nephrotoxicity was significantly inhibited by DHMEQ treatment (CsA + DHMEQ vs CsA vs control, 13.4 ± 7.1 vs 35.6 ± 18.4 vs 9.4 ± 5.4%, respectively, p < 0.0001), and these results reflected the results of renal functional assessment. DHMEQ treatment also had an inhibitory effect on the increased expression of chemokines, monocyte chemoattractant protein-1, and chemokine (c-c motif) ligand 5 due to repeated CsA administration, which inhibited the infiltration of macrophages and neutrophils into the renal tissue.

Conclusions

These findings suggest that DHMEQ treatment in combination therapy with CsA-based immunosuppression is beneficial to prevent the development of CsA-induced nephrotoxicity.

Growth arrest and DNA damage 45γ is required for caspase-dependent renal tubular cell apoptosis

BACKGROUND

Growth Arrest and DNA Damage 45γ (GADD45γ) is a member of the DNA damage-inducible gene family which responds to environmental stresses. Apoptosis is a critical mode of renal tubular cell death in nephrotoxin-induced acute kidney injury. In this study, we investigated the role of GADD45γ in renal tubular cell apoptosis induced by nephrotoxic drugs.

METHODS

Primary human renal tubular epithelial (HRE) cells were used in this study. To derive stable cell lines in which GADD45γ expression was silenced, HRE cells were transduced with a plasmid encoding GADD45γ-specific shRNA. The recombinant adenovirus containing the GADD45γ gene was synthesized to overexpress GADD45γ protein. Cell death was induced by cisplatin and cyclosporine A (CsA). To prevent apoptotic cell death, pan-caspase inhibitor ZVAD-FMK was used. To prevent non-apoptotic cell death, necrostatin-1 and ferrostatin-1 were used. The degree of apoptosis and necrosis of cultured cells were evaluated by flow cytometry.

RESULTS

Expression of the GADD45γ gene was significantly upregulated in response to treatment with CsA and cisplatin. Apoptosis and necrosis induced by these drugs were significantly reduced by silencing of GADD45γ, and significantly augmented by the overexpression of GADD45γ. The activation of caspase-3 and caspase-7 as well as caspase-9 induced by cisplatin or CsA was reduced by silencing of GADD45γ, and was augmented by the overexpression of GADD45γ, indicating that caspase activation is dependent on the expression of GADD45γ. ZVAD-FMK significantly inhibited apoptosis induced by cisplatin or CsA, indicating a role of caspases in mediating apoptotic cell death. ZVAD-FMK was effective to prevent necrosis as well, indicating that the observed necrosis was a secondary event following apoptosis at least in part.

CONCLUSIONS

To our knowledge, this is the first study to show that GADD45γ is required for the caspase-dependent apoptosis of renal tubular cells induced by nephrotoxic drugs.

The Protective Effect of Fluorofenidone against Cyclosporine A-Induced Nephrotoxicity

BACKGROUND/AIMS

Cyclosporine A (CsA) is an immunosuppressant drug that is used during organ transplants. However, its utility is limited by its nephrotoxic potential. This study aimed to investigate whether fluorofenidone (AKF-PD) could provide protection against CsA-induced nephrotoxicity.

METHODS

Eighty-five male Sprague-Dawley rats were divided into 5 groups: drug solvent, CsA, CsA with AKF-PD (250, 500 mg/kg/day), and CsA with pirfenidone (PFD, 250 mg/kg/day). Tubulointerstitial injury index, extracellular matrix (ECM) deposition, expression of type I and IV collagen, transforming growth factor (TGF)-β1, platelet-derived growth factor (PDGF), Fas ligand (FASL), cleaved-caspase-3, cleaved-poly(ADP-ribose) polymerase (PARP)-1, and the number of transferase-mediated nick end-labeling (TUNEL)-positive renal tubule cells were determined. In addition, levels of TGF-β1, FASL, cleaved-caspase-3, cleaved-PARP-1, and number of annexin V-positive cells were determined in rat proximal tubular epithelial cells (NRK-52E) treated with CsA (20 μmol/L), AKF-PD (400 μg/mL), PFD (400 μg/mL), and GW788388 (5 μmol/L).

RESULTS

AKF-PD (250, 500 mg/kg/day) significantly reduced tubulointerstitial injury, ECM deposition, expression of type I and IV collagen, TGF-β1, PDGF, FASL, cleaved-caspase-3, cleaved-PARP-1, and number of TUNEL-positive renal tubule cells in the CsA-treated kidneys. In addition, AKF-PD (400 μg/mL) significantly decreased TGF-β1, FASL, cleaved-caspase-3, and PARP-1 expression in NRK-52E cells and further reduced the number of annexin V-positive cells.

CONCLUSION

AKF-PD protect kidney from fibrosis and apoptosis in CsA-induced kidney injury.

Immune Responsive Release of Tacrolimus to Overcome Organ Transplant Rejection

Transplant rejection is the key problem in organ transplantation and, in clinic, immunosuppressive agents such as tacrolimus are directly administered to the recipients after surgery for T-cell inhibition. However, direct administration of tacrolimus may bring severe side effects to the recipients. Herein, by rational design of two hydrogelators NapPhePheGluTyrOH (1) and Nap d-Phe dPheGluTyrOH (2), a facile method of immune responsive release of tacrolimus is developed from their hydrogels to overcome organ transplantation rejection. Upon incubation with protein tyrosine kinase, which is activated in T cells after organ transplantation, the tacrolimus-encapsulating Gel 1 or Gel 2 is disassembled to release tacrolimus. Cell experiments show that both Gel 1 and Gel 2 have better inhibition effect on the activated T cells than free drug tacrolimus. Liver transplantation experiments indicate that, after 7 days of treatment of same dose tacrolimus, the recipient rats in the Gel 2 group show significantly extended median survival time of 22 days while the recipients treated with conventional tacrolimus medication have a median survival time of 13 days. It is expected herein that this "smart" facile method of immune responsive release of tacrolimus can be applied to overcome organ transplantation rejection in clinic in the near future.

Selection and use of immunosuppressive therapies after liver transplantation: current German practice

In recent years, immunosuppression (IS) after liver transplantation (LT) has become increasingly diversified as the choice of agents has expanded and clinicians seek to optimize the balance of immunosuppressive potency with the risk of adverse events in individual patients. Calcineurin inhibitors (CNIs) are the primary agents used for patients undergoing liver transplantation. Other therapeutic agents like interleukin-2 receptor antagonists are not universally administered, but can be considered for the delay or reduction in CNI exposure. An early addition of mycophenolate mofetil (MMF) or the mTOR inhibitor everolimus also allows for the reduction in the CNI dose. To reduce the risk of malignancy, in particular of skin tumors, as well as to prevent the deterioration of renal function, everolimus-based therapy may be advantageous. Apart from patients with autoimmune hepatitis, steroids are withdrawn within 3-6 months after transplantation. Overall, immunosuppression can only be standardized in a limited proportion of patients due to specific clinical requirements and risk factors. Future studies should attempt to refine accurate individualization of the immunosuppressive regimen in specific difficult-to-treat patient subpopulations.

The protective effect of vildagliptin in chronic experimental cyclosporine A-induced hepatotoxicity

The study examined the effect of dipeptidyl peptidase-4 (DPP-4) inhibitor, vildagliptin, in cyclosporine (CsA)-induced hepatotoxicity. Rats were divided into 4 groups treated for 28 days: control (vehicle), vildagliptin (10 mg/kg, orally), CsA (20 mg/kg, s.c.), and CsA-vildagliptin group. Liver function was assessed by measuring serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyltransferase (γGT), lactate dehydrogenase (LDH), and albumin, and histopathological changes of liver were examined. Oxidative stress markers were evaluated. Assessment of nuclear factor-kappa B (NF-κB) activity in hepatic nuclear extract, serum DPP-4, and expression of Bax and Bcl2 were also done. CsA-induced hepatotoxicity was evidenced by increase in serum levels of AST, ALT, and γGT; a decrease in serum albumin; and a significant alteration in hepatic architecture. Also, significant increase in thiobarbituric acid reactive substance (TBARS) and decrease in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione (GSH) levels, increased expression Bax proteins with deceased expression of Bcl2, and increased hepatic activity of NF-κB and serum DPP-4 level were observed upon CsA treatment. Vildagliptin significantly improved all altered parameters induced by CsA administration. Vildagliptin has the potential to protect the liver against CsA-induced hepatotoxicity by reducing oxidative stress, DPP-4 activity, apoptosis, and inflammation.

DNA double-strand breaks induced intractable glomerular fibrosis in renal allografts

BACKGROUNDS

The relationship between DNA damage and glomerular fibrosis in renal allografts remains unclear.

METHODS

We examined renal allograft specimens from 35 patients in which DNA double-strand breaks (DSBs) and glomerular fibrosis were detected by phospho-histone H2A.X (γ-H2AX) expression and collagen (COL) types III, IV, and VI accumulation. We also examined the in vitro relationship between DNA damage and COL accumulation by mitomycin C (MMc)-induced DNA damage in human glomerular endothelial cells (HRGEc).

RESULTS

The γ-H2AX and COL type VI, which mainly accumulated in the subendothelial and mesangial regions, were positively correlated with the duration of the post-renal transplant (RT) period. In multiple regression analysis, the duration of the post-RT period and cg in the Banff '07 classification were identified as a significant predictor of COL type VI accumulation and γ-H2AX expression in the glomerular capillaries. In addition, the γ-H2AX-positive area was also identified as a predictor of glomerular accumulation of COL type VI. COL type VI was detected in the cytoplasm of the HRGEc, which was secreted into the supernatant after MMc stimulation with γ-H2AX expression. The number of γ-H2AX (-)/COL type VI (+) cells was inversely associated with the number of γ-H2AX (+)/COL type VI (-) cells during 24-h MMc treatment.

CONCLUSIONS

Our findings suggest that the long-term RT induces DSBs and HRGEc-secreted COL type VI accumulation in the glomerular capillaries, which might progress to intractable glomerular fibrosis.

Pharmacogenetics and drug-induced nephrotoxicity in renal transplant recipients

INTRODUCTION

The advent of calcineurin inhibitors (CNIs), as the leading immunosuppressive agents, not only has revolutionized the transplant medicine but also made it a better therapeutic intervention that guarantees the graft outcome and improves the survival rate of patients. However, genetic polymorphism(s) in the CNIs metabolic substrates genes (CYP3A4, CYP3A5) and their transporter such as P-glycoprotein (P-gp) can influence the CNIs metabolism and elicit some possible systemic and intra-renal exposures to drugs and/or metabolites with differential risk of nephrotoxicity, jeopardizing the transplantation.

METHODS

In the current study, we review the recent literatures to evaluate the effects of genetic polymorphisms of the genes involved in development of chronic calcineurin nephrotoxicity and progression of chronic allograft dysfunction (CAD) providing an extensive overview on their clinical impacts.

RESULTS

Identifying the inherited genetic basis for the inter-individual differences in terms of drug responses and determining the risk of calcineurin-mediated nephrotoxicity and CAD allow optimized personalized administration of these agents whith minimal adverse effects.

CONCLUSION

Pharmacogenetics characteristics of CYP isoforms (CYP3A) and efflux transporters (P-gp and MRP), involved in metabolism and extracellular transportation of the immunosuppressive CNIs, can be of pivotal information in the pharmacotherapy of the renal-transplant recipients. Such information can be used for the successes clinical interventions to attain an improved drug administration strategy with reduced rates of rejection and toxicity.

Cyclosporine A induces apoptotic and autophagic cell death in rat pituitary GH3 cells

Cyclosporine A (CsA) is a powerful immunosuppressive drug with side effects including the development of chronic nephrotoxicity. In this study, we investigated CsA treatment induced apoptotic and autophagic cell death in pituitary GH3 cells. CsA treatment (0.1 to 10 µM) decreased survival of GH3 cells in a dose-dependent manner. Cell viability decreased significantly with increasing CsA concentrations largely due to an increase in apoptosis, while cell death rates due to autophagy altered only slightly. Several molecular and morphological features correlated with cell death through these distinct pathways. At concentrations ranging from 1.0 to 10 µM, CsA induced a dose-dependent increase in expression of the autophagy markers LC3-I and LC3-II. Immunofluorescence staining revealed markedly increased levels of both LC3 and lysosomal-associated membrane protein 2 (Lamp2), indicating increases in autophagosomes. At the same CsA doses, apoptotic cell death was apparent as indicated by nuclear and DNA fragmentation and increased p53 expression. In apoptotic or autophagic cells, p-ERK levels were highest at 1.0 µM CsA compared to control or other doses. In contrast, Bax levels in both types of cell death were increased in a dose-dependent manner, while Bcl-2 levels showed dose-dependent augmentation in autophagy and were decreased in apoptosis. Manganese superoxide dismutase (Mn-SOD) showed a similar dose-dependent reduction in cells undergoing apoptosis, while levels of the intracellular calcium ion exchange maker calbindin-D9k were decreased in apoptosis (1.0 to 5 µM CsA), but unchanged in autophagy. In conclusion, these results suggest that CsA induction of apoptotic or autophagic cell death in rat pituitary GH3 cells depends on the relative expression of factors and correlates with Bcl-2 and Mn-SOD levels.

Mycelia glycoproteins from Cordyceps sobolifera ameliorate cyclosporine-induced renal tubule dysfunction in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cordyceps sorbolifera has been used in Traditional Chinese Medicine for improving the renal function. Cyclosporine A (CsA) is an important immunosuppressive agent in the prevention of renal allograft rejection, but long-term usage of CsA could lead to chronic nephrotoxicity and renal graft failure. The study was aimed to investigate whether the mycelia glycoproteins of Cordyceps sobolifera (CSP) exert prevention effects on CsA-induced nephrotoxicity.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats were randomly assigned into four groups (n=6 per group): normal saline (control group), CSP group, CsA group, and CSP-CsA group (CsA combined treatment with CSP). Glomerular and tubular functions were assessed and histological studies were performed.

RESULTS

CSP, prepared by hot water extraction, ethanol precipitation and membrane dialysis, was found to be composed of three glycoproteins with average molecular weights of 543, 31, and 6.3 kDa, respectively. CsA impaired urea clearance and creatinine clearance were significantly improved by concomitant administration of CSP. TUNEL histochemical stain revealed that CSP significantly decreased CsA-induced apoptosis in renal tubular cells. The reducing effect of caspase-3 activation by CSP was suggested through the over-expression of the anti-apoptosis protein Bcl-2 in renal tubule cells. In assessment of CSP protection of renal tubule function, we found that CSP restored CsA induced magnesium wasting by increasing the magnesium reabsorption channels TRMP6 and TRMP7.

CONCLUSION

The results suggested that CSP had a significant suppressive activity on CsA-induced apoptosis and protective activity against nephron loss possibly via its restoring activity by increasing the magnesium reabsorption channels TRMP6 and TRMP7 on CsA induced magnesium wasting.

Oral administration of ginseng ameliorates cyclosporine-induced pancreatic injury in an experimental mouse model

Background

This study was performed to investigate whether ginseng has a protective effect in an experimental mouse model of cyclosporine-induced pancreatic injury.

Methods

Mice were treated with cyclosporine (30 mg/kg/day, subcutaneously) and Korean red ginseng extract (0.2 or 0.4 g/kg/day, oral gavage) for 4 weeks while on a 0.01% salt diet. The effect of ginseng on cyclosporine-induced pancreatic islet dysfunction was investigated by an intraperitoneal glucose tolerance test and measurements of serum insulin level, β cell area, macrophage infiltration, and apoptosis. Using an in vitro model, we further examined the effect of ginseng on a cyclosporine-treated insulin-secreting cell line. Oxidative stress was measured by the concentration of 8-hydroxy-2′-deoxyguanosine in serum, tissue sections, and culture media.

Results

Four weeks of cyclosporine treatment increased blood glucose levels and decreased insulin levels, but cotreatment with ginseng ameliorated the cyclosporine-induced glucose intolerance and hyperglycemia. Pancreatic β cell area was also greater with ginseng cotreatment compared with cyclosporine monotherapy. The production of proinflammatory molecules, such as induced nitric oxide synthase and cytokines, and the level of apoptotic cell death also decreased in pancreatic β cell with ginseng treatment. Consistent with the in vivo results, the in vitro study showed that the addition of ginseng protected against cyclosporine-induced cytotoxicity, inflammation, and apoptotic cell death. These in vivo and in vitro changes were accompanied by decreases in the levels of 8-hydroxy-2′-deoxyguanosine in pancreatic β cell in tissue section, serum, and culture media during cotreatment of ginseng with cyclosporine.

Conclusions

The results of our in vivo and in vitro studies demonstrate that ginseng has a protective effect against cyclosporine-induced pancreatic β cell injury via reducing oxidative stress.

Current status of immunosuppression in liver transplantation

With advancements in immunosuppressive strategies and availability of better immunosuppressive agents, survival rate following liver transplantation has improved significantly in the recent times. Besides improvements in surgical techniques, the most important factor that has contributed to this better outcome is the progress made in the field of immunosuppression. Over the last several years, the trend has changed to tailored immunosuppression with the aim of achieving optimal graft function while avoiding its undesirable side effects. Induction agents are no longer used routinely and the aim is to provide minimal immunosuppression in the maintenance phase. The present review discusses the various types of immunosuppressive agents, their mechanism of action, clinical utility, advantages and disadvantages, and their side effects in short and long-term. It also discusses about tailoring immunosuppression in presence of various situations such as renal dysfunction, metabolic syndrome, hepatitis C recurrence, cytomegalovirus infections and so on. The issue of chronic kidney disease and the available renal sparing immunosuppressive strategies has been particularly stressed upon. Finally, it discusses about the practical aspects of various immunosuppression regimens including drug monitoring.

Mechanisms of cyclosporine-induced renal cell apoptosis: a systematic review

BACKGROUND/AIMS

Chronic cyclosporine A (CsA) nephrotoxicity (CCN) is an important cause of chronic renal dysfunction with no effective clinical intervention. To further elucidate the mechanisms of renal cell apoptosis in CCN, all relevant in vivo studies on this subject were analyzed.

METHODS

We searched for in vivo studies on the mechanisms of CsA-induced renal cell apoptosis in Medline (1966-July 2010), Embase (1980-July 2010) and ISI (1986-July 2010). The studies were evaluated for their quality according to a set of in vivo standards, data extracted according to PICOS, and then synthesized.

RESULTS

Renal cell apoptosis was an important feature of CCN and an important factor of renal dysfunction. First, CsA could upregulate Fas/Fas ligand, downregulate Bcl-2/Bcl-XL, and increase caspase-1 and caspase-3. Second, it could induce oxidative stress and damage the antioxidant defense system. Third, it could increase endoplasmic reticulum stress protein in a dose- and time-dependent manner. Fourth, CsA could impair the urine concentration and decrease the expression of hypertonicity-induced genes. Fifth, CsA-induced renal cell apoptosis was significantly decreased by blocking the angiotensin II type 1 receptor using losartan.

CONCLUSIONS

The in vivo mechanisms for CCN are more complex than those found in vitro. CsA can induce renal cell apoptosis using five pathways in vivo and activated caspases might be the ultimate intersection of these pathways and the common intracellular pathway mediating apoptosis. These data provide new potential points for intervention and need to be confirmed by further studies.

ER stress contributes to renal proximal tubule injury by increasing SREBP-2-mediated lipid accumulation and apoptotic cell death

Renal proximal tubule injury is induced by agents/conditions known to cause endoplasmic reticulum (ER) stress, including cyclosporine A (CsA), an immunosuppressant drug with nephrotoxic effects. However, the underlying mechanism by which ER stress contributes to proximal tubule cell injury is not well understood. In this study, we report lipid accumulation, sterol regulatory element-binding protein-2 (SREBP-2) expression, and ER stress in proximal tubules of kidneys from mice treated with the classic ER stressor tunicamycin (Tm) or in human renal biopsy specimens showing CsA-induced nephrotoxicity. Colocalization of ER stress markers [78-kDa glucose regulated protein (GRP78), CHOP] with SREBP-2 expression and lipid accumulation was prominent within the proximal tubule cells exposed to Tm or CsA. Prolonged ER stress resulted in increased apoptotic cell death of lipid-enriched proximal tubule cells with colocalization of GRP78, SREBP-2, and Ca(2+)-independent phospholipase A(2) (iPLA(2)β), an SREBP-2 inducible gene with proapoptotic characteristics. In cultured HK-2 human proximal tubule cells, CsA- and Tm-induced ER stress caused lipid accumulation and SREBP-2 activation. Furthermore, overexpression of SREBP-2 or activation of endogenous SREBP-2 in HK-2 cells stimulated apoptosis. Inhibition of SREBP-2 activation with the site-1-serine protease inhibitor AEBSF prevented ER stress-induced lipid accumulation and apoptosis. Overexpression of the ER-resident chaperone GRP78 attenuated ER stress and inhibited CsA-induced SREBP-2 expression and lipid accumulation. In summary, our findings suggest that ER stress-induced SREBP-2 activation contributes to renal proximal tubule cell injury by dysregulating lipid homeostasis.

Comparison of early and late conversion of sirolimus in experimental model of chronic cyclosporine nephropathy

Sirolimus (SRL) is a promising drug for replacing calcineurin inhibitors. We performed this study to determine the optimal time of conversion from cyclosporine (CsA) to SRL in an experimental model of chronic CsA nephropathy. Three separate studies were performed. In the first study, SRL was given to rats with or without CsA for 4 weeks. In the second study, rats were treated initially with CsA for 1 week, and then switched to SRL (early conversion). In the third study, CsA was given for 4 weeks and then replaced by SRL for 4 weeks treatment of CsA (late conversion). The influence of SRL on CsA-induced renal injury was evaluated by assessing renal function, histopathology (interstitial inflammation and fibrosis), and apoptotic cell death. Combined CsA and SRL treatment significantly impaired renal function, increased apoptosis, and interstitial fibrosis and inflammation compared with CsA or SRL treatment alone. Early conversion to SRL did not change renal function, histopathology, or apoptosis compared with early CsA withdrawal. By contrast, late conversion to SRL significantly aggravated these parameters compared with late CsA withdrawal. In conclusion, early conversion from CsA to SRL is effective in preventing CsA-induced renal injury in a setting of CsA-induced renal injury.

A pharmacologically-based array to identify targets of cyclosporine A-induced toxicity in cultured renal proximal tubule cells

Mechanisms of cyclosporine A (CsA)-induced nephrotoxicity were generally thought to be hemodynamic in origin; however, there is now accumulating evidence of a direct tubular effect. Although genomic and proteomic experiments by our group and others provided overall information on genes and proteins up- or down-regulated by CsA in proximal tubule cells (PTC), a comprehensive view of events occurring after CsA exposure remains to be described. For this purpose, we applied a pharmacologic approach based on the use of known activities of a large panel of potentially protective compounds and evaluated their efficacy in preventing CsA toxicity in cultured mouse PTC. Our results show that compounds that blocked protein synthesis and apoptosis, together with the CK2 inhibitor DMAT and the PI3K inhibitor apigenin, were the most efficient in preventing CsA toxicity. We also identified GSK3, MMPs and PKC pathways as potential targets to prevent CsA damage. Additionally, heparinase-I and MAPK inhibitors afforded partial but significant protection. Interestingly, antioxidants and calcium metabolism-related compounds were unable to ameliorate CsA-induced cytotoxicity. Subsequent experiments allowed us to clarify the hierarchical relationship of targeted pathways after CsA treatment, with ER stress identified as an early effector of CsA toxicity, which leads to ROS generation, phenotypical changes and cell death. In summary, this work presents a novel experimental approach to characterizing cellular responses to cytotoxics while pointing to new targets to prevent CsA-induced toxicity in proximal tubule cells.

Melatonin suppresses cyclosporine A-induced autophagy in rat pituitary GH3 cells

Cyclosporine A (CsA) is a powerful immunosuppressive drug with side effects including the induction of chronic nephrotoxicity including endoplasmic reticulum (ER) stress in tubular cells. Recently, it was reported that autophagy is induced by ER stress and serves to alleviate the associated deleterious effects. In the current study, CsA treatment (0-100 microm) decreased cell survival of rat pituitary GH3 cells in a dose-dependent manner. At concentrations ranging from 1.0 to 10 microm, CsA induced a dose-dependent increase in the expression of microtubule-associated protein 1 light chain 3 (LC3)-I and LC3-II. Cells treated with 2.5 microm CsA exhibited cytoplasmic vacuolation, indicating that CsA induces autophagy in rat pituitary GH3 cells. In the presence of 1.0-10 microm CsA, the expression of catalase decreased while that of the ER stress markers, ER luminal binding protein (BiP) and inositol-requiring enzyme 1 alpha (IRE1alpha), increased as compared those levels in untreated cells. These results suggested that CsA-induced autophagy is dependent on ER stress. To determine whether melatonin would protect cells against CsA-induced autophagy, we treated rat pituitary GH3 cells with melatonin in the presence of CsA. Melatonin treatment (100 and 200 microm) suppressed autophagy induced by 2.5 and 5 microm CsA. Furthermore, co-treatment with 100 microm melatonin inhibited LC3-II expression, and increased catalase and phosphorylated p-ERK levels in the presence of 2.5 and 5 microm CsA. BiP and IRE1alpha expression in melatonin-co-treated cells was superior to that in cells treated with 2.5 and 5 microm CsA alone. Thus, melatonin suppresses CsA-mediated autophagy in rat pituitary GH3 cells.

Polymerized type I collagen reduces chronic cyclosporine nephrotoxicity

BACKGROUND

Polymerized type I collagen (P-collagen) has been successfully used to reduce human hypertrophic scars due to its anti-fibrotic and anti-inflammatory properties. We therefore carried out a study to determine if P-collagen reduces functional and structural injury in chronic cyclosporine [cyclosporine A (CsA)] nephropathy.

METHODS

Four groups of six male Wistar rats fed with a low sodium diet were treated with vehicle, P-collagen (0.8 mg/day, i.p.), CsA (15 mg/kg) or CsA + P-collagen for 15 days. Mean arterial pressure, renal blood flow and glomerular filtration rate were measured in all groups. Structural injury such as arteriolopathy, tubulo-interstitial fibrosis (TI-fibrosis) and positive apoptotic cells were quantified. The mRNA expression levels of transforming growth factor-beta (TGF-beta), kidney injury molecule (Kim-1), alpha-smooth muscle actin (alpha-SMA), glutathione peroxidase, catalase and Cu/Zn superoxide dismutase (SOD) as well as MnSOD were assessed. Antioxidant enzyme activity, renal lipoperoxidation and urinary excretion of oxygen peroxide (UH(2)O(2)V) were determined.

RESULTS

Cyclosporine produced renal dysfunction and induced the development of arteriolopathy, TI-fibrosis and tubular apoptosis. These alterations were associated with increases in TGF-beta, Kim-1 and alpha-SMA mRNA levels as well as with a significant increase of oxidative stress and a reduction of SOD activity. P-Collagen partially ameliorated CsA-induced renal dysfunction and structural injury and prevented both tubular apoptosis and increased oxidative stress. This renoprotective effect was found to be associated with a reduction of TGF-beta, Kim-1 and alpha-SMA mRNA levels.

CONCLUSIONS

This study has therefore demonstrated that P-collagen appears to have anti-fibrotic and anti-apoptotic properties and highlights the possibility that the compound might be useful in a strategy to reduce chronic CsA nephrotoxicity.

Donor age and renal P-glycoprotein expression associate with chronic histological damage in renal allografts

The contributions of donor kidney quality (partially determined by donor age), allograft rejection, and calcineurin inhibitor nephrotoxicity on the progression of histologic damage of renal allografts are not completely defined. Moreover, the determinants of individual susceptibility to calcineurin inhibitor nephrotoxicity are not known but may include variability in drug transport and metabolism. In a prospective cohort of 252 adult renal allograft recipients treated with a combination of tacrolimus, mycophenolate mofetil, and corticosteroids, we studied 744 renal allograft biopsies obtained regularly from time of transplantation for 3 yr. We assessed determinants of histologic evolution, including tacrolimus exposure, renal P-glycoprotein (ABCB1) expression, and polymorphisms in the CYP3A4, CYP3A5, and ABCB1 genes. Within the first 3 yr after transplantation, we noted a progressive increase in interstitial fibrosis, tubular atrophy, glomerulosclerosis, and vascular intimal thickening. Older donor age, absence of P-glycoprotein expression at the apical membrane of tubular epithelial cells, and combined donor-recipient homozygosity for the C3435T variant in ABCB1 significantly associated with increased susceptibility to chronic allograft damage independent of graft quality at implantation. Changes in graft function over time reflected these associations with donor age and ABCB1 polymorphisms, but it was acute T cell-mediated and antibody-mediated rejection that determined early graft survival. In conclusion, the effects of older donor age reach beyond the quality of the allograft at implantation and continue to be important for histologic evolution in the posttransplantation period. In addition, ABCB1 genotype and expression of P-glycoprotein in renal tubular epithelial cells determine susceptibility to chronic tubulointerstitial damage of transplanted kidneys.

Accumulation of advanced oxidation protein products induces podocyte apoptosis and deletion through NADPH-dependent mechanisms

The accumulation of plasma advanced oxidation protein products (AOPPs) is prevalent in diverse disorders such as diabetes, metabolic syndromes, and chronic kidney disease. To study whether accumulated AOPPs have an important role in the progression of proteinuria and glomerulosclerosis, we chronically treated normal Sprague-Dawley rats with AOPP-modified rat serum albumin. Podocyte apoptosis was significantly increased coincident with the onset of albuminuria and preceded significant losses of glomerular podocytes. Increasing the amount of AOPPs in the media of conditionally immortalized podocytes rapidly triggered the production of intracellular superoxide by activation of NADPH oxidase and this, in turn, led to an upregulation of p53, Bax, caspase 3 activity, and apoptosis. Chronic inhibition of NADPH oxidase by apocynin prevented podocyte apoptosis, ameliorated podocyte depletion, and decreased albuminuria in AOPP-challenged rats. Our study demonstrates that accumulation of AOPPs promotes NADPH oxidase-dependent podocyte depletion by a p53-Bax apoptotic pathway both in vivo and in vitro.

Tacrolimus causes a blockage of protein secretion which reinforces its immunosuppressive activity and also explains some of its toxic side-effects

BACKGROUND

Tacrolimus (FK506) is a macrolide immunosuppressant drug from the calcineurin inhibitor family, widely used in solid organ and islet cell transplantation, but produces significant side-effects.

OBJECTIVE

This study examined the effect of FK506 on interleukin-2 (IL-2) and insulin secretion, establishing a novel characteristic of this drug that could explain its diverse adverse effects, and developed an experimental model for the simultaneous analysis of mRNA expression and protein secretion affected by this drug.

METHODS

The IL-2 levels when tacrolimus was administered were analysed by Western blot, immunocytochemistry and RT-PCR in a T lymphocyte cellular line (Jurkat) 24 h post-stimulation. The insulin levels when tacrolimus was administered were analysed 4 h after stimulation of glucose-induced insulin secretion in a pancreatic cellular line (MIN6).

RESULTS

The previously published information describes tacrolimus as only capable of partially blocking IL-2 mRNA expression. In our hands, the cellular content of IL-2 is almost undetectable in stimulated Jurkat cells and can be detected in cellular extracts only when the secretory pathway is blocked by brefeldin A (BFA). BFA added 2 h after the beginning of stimulation was able to inhibit IL-2 secretion, without affecting IL-2 mRNA expression. Therefore BFA utilization allowed us to establish a model to analyze the effect on IL-2 secretion, separately from its expression. Tacrolimus added before stimulation inhibits only IL-2 synthesis, but blocks IL-2 protein secretion when added 2 h after stimulation. Similarly, tacrolimus is also capable of blocking the glucose-stimulated secretion of insulin by MIN6 cells. An increase of the intracellular content can be detected concomitantly with a decrease of the hormone measured in the culture medium.

CONCLUSIONS

Results of this study indicate that tacrolimus possesses another important effect in addition to the inhibition of IL-2 gene transcription, namely the ability to act as a general inhibitor of the protein secretory pathway. These results strongly suggest that the diabetogenic effect of the immune suppressant FK506 could be caused by the blockade of insulin secretion. This novel effect also provides an explanation for other side-effects observed in immunosuppressive treatment.

Calcineurin inhibitor nephrotoxicity

The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.

Established and newly proposed mechanisms of chronic cyclosporine nephropathy

Cyclosporine (CsA) has improved patient and graft survival rates following solid-organ transplantation and has shown significant clinical benefits in the management of autoimmune diseases. However, the clinical use of CsA is often limited by acute or chronic nephropathy, which remains a major problem. Acute nephropathy depends on the dosage of CsA and appears to be caused by a reduction in renal blood flow related to afferent arteriolar vasoconstriction. However, the mechanisms underlying chronic CsA nephropathy are not completely understood. Activation of the intrarenal renin-angiotensin system (RAS), increased release of endothelin-1, dysregulation of nitric oxide (NO) and NO synthase, up-regulation of transforming growth factor-beta1 (TGF-beta1), inappropriate apoptosis, stimulation of inflammatory mediators, enhanced innate immunity, endoplasmic reticulum stress, and autophagy have all been implicated in the pathogenesis of chronic CsA nephropathy. Reducing the CsA dosage or using other renoprotective drugs (angiotensin II receptor antagonist, mycophenolate mofetil, and statins, etc.) may ameliorate chronic CsA-induced renal injury. This review discusses old and new concepts in CsA nephropathy and preventive strategies for this clinical dilemma.

Catechin and proanthocyanidin B4 from grape seeds prevent doxorubicin-induced toxicity in cardiomyocytes

The clinical use of doxorubicin, a highly active anticancer drug, is limited by its severe cardiotoxic side effects. Grape seed extract has been reported to exert protective effects on doxorubicin-induced cardiotoxicity. The cardiovascular protective effects of grape seed extract are believed to be ascribed to its antioxidative properties. A series of studies have has demonstrated that polyphenols are instrumental for the antioxidative properties of grape seed extract. This study was designed to investigate whether two major polyphenols isolated from grape seed extract, catechin and proanthocyanidin B4 (Pc B(4)), had protective effects against doxorubicin-induced toxicity in cardiomyocytes and their underlying mechanisms. The results showed that grape seed polyphenols catechin and Pc B(4) pretreatment would protect cardiomyocytes against doxorubicin-induced toxicity by decreasing reactive oxygen species generation as well as the number of apoptotic cells, preventing DNA fragmentation, regulating the expression levels of the pro-apoptotic protein Bax-alpha and the anti-apoptotic protein Bcl-2, and inhibiting apoptotic signaling pathways.

Tanshinone IIA protects neonatal rat cardiomyocytes from adriamycin-induced apoptosis

Tanshinone IIA (TSN) is a monomer extracted from the Chinese herb Danshen. In this study, we examined the effect of Tanshinone IIA on adriamycin (ADR)-induced apoptosis in neonatal rat cardiomyocytes and underlying molecular mechanisms. Primary cultured cardiomyocytes were treated with 1 micromol/L of adriamycin for 24 h with or without pretreatment with Tanshinone IIA (0.5-2 micromol/L) for 2 h. 3-(4,5-dimethyl thiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay, Hoechst staining, and flow cytometry measurement were used to assess cell viability and apoptosis. Fluorescent probes 2',7'-dichlorofluorescein diacetate and dihydroethidium were used to detect the production of reactive oxygen species. Western blotting was used to evaluate the expression of Bcl-2 and Bax proteins. Adriamycin significantly induced apoptosis in cardiomyocytes. Tanshinone IIA (0.5-2 micromol/L) ameliorated apoptosis induced by adriamycin in a dose-dependent manner. Tanshinone IIA (2 micromol/L) markedly attenuated adriamycin-induced reactive oxygen species production. Western blotting revealed that Tanshinone IIA prevented the adriamycin-mediated reduction of the ratio of Bcl-2/Bax. In conclusion, Tanshinone IIA significantly inhibits adriamycin-induced cardiomyocyte apoptosis in a dose-dependent manner, and this effect is at least partly caused by its antioxidant properties.

Caspase-7, Fas and FasL in long-term renal ischaemia/reperfusion and immunosuppressive injuries in rats

BACKGROUND/AIMS

Ischaemia/reperfusion (I/R) injury is important in kidney transplantation. We have previously demonstrated that long-term I/R injury and immunosuppression affect apoptosis and inflammation, but the underlying mechanisms are far from clear. In this study, the involvement of caspase-7, Fas and FasL was further investigated.

METHODS

The right renal pedicle was clamped for 45 min followed by left nephrectomy in 40 rats. Cyclosporine (CsA), tacrolimus (Tac), rapamycin (Rap) or mycophenolate mofetil (MMF) were administered daily for 16 weeks. Caspase-7, Fas and FasL expression, and their correlations with caspase-3, apoptosis, inflammation, renal structure and function were evaluated.

RESULTS

Active caspase-7 was significantly increased in I/R and CsA-treated kidneys and decreased by Tac, Rap and MMF, while the caspase-7 precursor was enhanced by Rap. Active caspase-7-stained cells were scattered throughout the tubulointerstitium and often had apoptotic features. Fas, but not FasL, was increased in I/R and CsA-treated kidneys and decreased by Rap and MMF. Fas and FasL proteins were mainly located in dilated tubules. There were close correlations among caspase-7, Fas, caspase-3, apoptosis, inflammation, renal structure and function.

CONCLUSION

Caspase-7, associated with caspase-3, apoptosis and inflammation, might be involved in long-term I/R and immunosuppressive injury, at least in part through the Fas-signalling pathway.

DNA Fragmentation in Acute and Chronic Rejection After Renal Transplantation

Acute and chronic rejections are important denominators for the long-term function of renal grafts. One important indicator of cell damage is enzymatic DNA fragmentation. To investigate possible mechanisms, the rate of DNA fragmentation (TUNEL staining), the expression of tissue transglutaminase II (a marker of advanced DNA damage), and 8-hydroxy-2'-deoxyguanosine (8-OhdG), an indicator of oxidative injury of nucleic acids, were studied by immunohistochemistry. Semithin sections of renal biopsies revealed 23 patients to show acute interstitial rejections (Banff 97 IA, IB); eight patients, acute vascular rejection (Banff 97 IIA, IIB); and 20 patients, chronic allograft nephropathy (Banff 97 I to III). Correlations were calculated between apoptotic cells and serum creatinine at the time of biopsy and after 6 months. In acute rejection, the proximal tubular cells were apoptotic, particularly in regions with mononuclear infiltrates. In consecutive sections, these apoptotic tubular cells also showed damage by reactive oxygen species (positive 8-OhdG staining). Patients with acute interstitial rejection revealed the highest number of tubular DNA fragmentation (14.9 +/- 10.3) versus chronic allograft nephropathy (9.2 +/- 5.6) as TUNEL-positive cells per 80,000 micro m(2) (P < .05). Patients with acute vascular rejection showed a low degree of tubular apoptosis (6.8 +/- 5.1). There was no significant difference in glomerular DNA fragmentation between acute interstitial and chronic rejections: acute interstitial rejection = 7.1 +/- 5.9 versus chronic allograft nephropathy=6.1 +/- 3.9 TUNEL-positive cells per 80,000 micro m(2). There was a significant negative correlation between the degree of tubular (P < .01) and glomerular (P < .05) apoptosis and the serum creatinine at the time of biopsy as well as after 6 months in all patients irrespective of the Banff class. However, there was heterogeneity in the correlation between renal function and the degree of apoptosis in the glomerular and tubular compartments in the various Banff classes. A positive correlation (P < .01) was observed between the degree of tubular apoptosis and serum creatinine at 6 months after biopsy among patients with acute vascular rejection (Banff 97 IIA, IIB). The present data revealed a high degree of tubular DNA fragmentation associated with oxidative stress in acute interstitial rejection. Nevertheless, apoptosis did not generally negatively influence future renal function and may be important to clear proliferating cells. Apoptosis may also play a different pathophysiological role depending on the type of rejection.

Plantainoside D protects adriamycin-induced apoptosis in H9c2 cardiac muscle cells via the inhibition of ROS generation and NF-κB activation

Plantainoside D (PD), was isolated from the leaves of Picrorhiza scrophulariiflora (Scrophulariaceae). The anti-oxidative activity of PD was evaluated based on scavenging effects on hydroxyl radicals and superoxide anion radicals. Adriamycin (ADR) is a potent anti-tumor drug known to cause severe cardiotoxicity. Although ADR generates free radicals, the role of free radicals in the development of cardiac toxicity has not been understood. This study was undertaken to investigate the protective effect of PD against ADR-induced apoptosis. In vitro, ADR caused dose-dependent toxicity in H9c2 cardiac muscle cells. Pre-treatment of the cardiac muscle cells with PD significantly reduced ADR-induced apoptosis of cardiac muscle cells. PD inhibited the ROS produced by ADR in the cardiac muscle cells. As well, PD increased GSH(glutathione), compared with ADR. In response to ADR, NF-kappaB was activated in H9c2 cells. However the treatment of PD reduced the activation of NF-kappaB. We also observed that the NF-kappaB inhibitor, PDTC, inhibited the cytotoxic effect on ADR-induced apoptosis in cardiac muscle cells. In parallel, IkappaBalpha-dominant negative plasmid-overexpression abrogated ADR-induced apoptosis in H9c2 cardiac muscle cells. In conclusion, these results suggest that Plantaionoside D can inhibit ADR-induced apoptosis in H9C2 cardiac muscle cells via inhibition of ROS generation and NF-kappaB activation. The pure compound PD can be a potential candidate agent which protects cardiotoxicity in ADR-exposed patients.

Insights into the effects of hyperlipoproteinemia on cyclosporine A biodistribution and relationship to renal function

The purpose of this study was to assess the effect of hyperlipoproteinemia on the biodistribution of cyclosporine A (CyA), an extensively lipoprotein bound immunosuppressant, in a rat model and to determine the potential toxicological significance of this effect. Normolipidemic and hyperlipoproteinemic rats were given a single 5 mg/kg dose of CyA as intravenous bolus and at selected times postdose, tissues, blood, and plasma were harvested and assayed for CyA content. Hyperlipoproteinemia was induced by intraperitoneal injection of 1 g/kg poloxamer 407. Compared with normolipidemic animals, hyperlipoproteinemic rats had higher plasma, blood, kidney, and liver CyA concentrations. In contrast, in heart and spleen the concentrations were decreased in hyperlipoproteinemia. The nephrotoxic effect of CyA was also evaluated in normolipidemic and hyperlipoproteinemic rats after 7 days of dosing with 20 mg/kg/day. In both groups of animals, repeated doses of CyA were associated with equivalent decreases in creatinine and urea clearances compared with matching control and predose baseline measures. The concentrations of drug in kidney were equivalent at the conclusion of the study. However, despite these similarities there was microscopic evidence of more severe changes in the kidneys in the hyperlipoproteinemic rats, which also experienced a significant decrease in body weight compared with the normolipedemic animals. In conclusion, the distribution of CyA to kidneys was enhanced in poloxamer 407-induced hyperlipoproteinemic rats after single doses, and with repeated doses there was an apparent greater adverse effect on these animals compared with normolipidemic animals.

Immunohistochemical expression of activated caspase-3 as a marker of apoptosis in glomeruli of human lupus nephritis

BACKGROUND

The role of apoptosis in lupus nephritis (LN) is still controversial. One of the key events in the process of apoptosis is activation of caspase-3. Studies of experimental models suggested that activated caspase-3 is a reliable indicator of apoptotic rate, with a favorable comparison against terminal transferase-mediated DNA nick-end labeling (TUNEL) assay. Our aim is to study apoptosis in various forms of LN and its relationship to histomorphological changes and selected laboratory findings by using activated caspase-3 as a novel marker of apoptosis.

METHODS

We investigated glomerular cell apoptosis in 51 biopsy specimens from patients with LN classified according to the International Society of Nephrology/Renal Pathology Society classification by using the TUNEL method and immunohistochemistry against activated caspase-3. In addition, activity and chronicity indices were calculated and anti-Ki-67 antibody was used to estimate proliferative activity.

RESULTS

Activated caspase-3-positive cells were present in glomeruli of 88.2% of cases, observed in the glomerular tuft and cellular and fibrocellular crescents. In the glomerular tuft, they were found mainly in segments with active inflammatory lesions. There was good correlation between apoptotic index assessed by using activated caspase-3 immunolabeling and the TUNEL method (r = 0.72; P < 0.01). We observed a significant positive correlation between apoptotic index and LN class (P < 0.001). Apoptotic index correlated significantly with activity index, proliferation index, and daily protein excretion (P < 0.001), but not chronicity index, creatinine concentration, or anti-DNA antibody-binding activity in serum.

CONCLUSION

Apoptotic rate is greater in severe active glomerular lesions in human LN, suggesting that apoptosis may be involved in augmenting inflammation in human LN.

Uteroplacental insufficiency increases p53 phosphorylation without triggering the p53-MDM2 functional circuit response in the IUGR rat kidney

Uteroplacental insufficiency (UPI) leads to intrauterine growth restriction (IUGR), which predisposes infants toward renal insufficiency early in life and increases the risk of kidney-related adult morbidities, such as hypertension. This compromised in utero environment has been demonstrated to impair nephrogenesis, as evidenced by a reduced nephron endowment in humans and in rats rendered IUGR by UPI. Concordantly, we have observed that IUGR rats have increased kidney p53 protein levels associated with increased apoptosis. Several factors can regulate p53 gene expression and activity, including posttranslational modifications and protein-protein interactions in the cell. Among these, two important mechanisms are 1) phosphorylation of the amino terminal serine 15 [phospho-p53 (Ser15)], which increases p53 stability and apoptotic activity, and 2) the murine double-minute (MDM2) functional circuit that limits further p53-induced apoptosis by promoting proteosomal degradation of p53. We hypothesize that UPI induces an increase in phospho-p53 (Ser15) in association with an absent MDM2 response, predisposing the kidney to increased apoptosis. To test our hypothesis, we induced IUGR through bilateral uterine artery ligation of the pregnant rat. UPI significantly increased phospho-p53 (Ser15), as well as ataxia teleangiectasia-mutated kinase/A-T-related kinase and dsDNA-activated protein kinase kinase levels, which induce phosphorylation of p53. In contrast, UPI induced no increase in kidney MDM2 mRNA and protein levels in IUGR pups. We conclude that among multiple mechanisms that affect nephrogenesis, UPI induces an increase in p53 phosphorylation without a corresponding increase in MDM2 expression, and we speculate that this response may contribute to the increased apoptosis previously described in the IUGR kidney.

Role of P-glycoprotein in cyclosporine cytotoxicity in the cyclosporine-sirolimus interaction

Cyclosporine nephrotoxicity remains a major side effect in solid organ transplantation, and can be exacerbated by concomitant administration of sirolimus. Cyclosporine and sirolimus are P-glycoprotein (Pgp) substrates. We hypothesized that the Pgp activity level may affect cyclosporine cytotoxicity by interfering with the ability of Pgp to remove cyclosporine from within tubular cells, and that an interaction between cyclosporine and sirolimus on Pgp function may explain the enhancement of cyclosporine nephrotoxicity by sirolimus. Cyclosporine cytotoxicity was evaluated in primary cultures of normal human renal epithelial cells (HRECs) by cell viability and cytotoxicity assays. Verapamil, quinine, PSC833, and PGP-4008 were used as Pgp inhibitors. Rhodamine-123 (R-123), a fluorescent substrate of Pgp, was used to assess Pgp-mediated transport. Cellular cyclosporine concentration was measured by high-performance liquid chromatography coupled to tandem mass spectrometry. Pgp expression and function were confirmed in HRECs and cyclosporine and sirolimus were shown to be Pgp inhibitors in this model. Verapamil-induced inhibition of Pgp led to a significant increase in cellular concentration of cyclosporine (P<0.05). Cyclosporine exerted a concentration-dependent cytotoxic effect on HRECs that was significantly increased by inhibition of Pgp activity. Sirolimus exerted an inhibitory effect on R-123 efflux in HRECs and increased cellular cyclosporine concentrations in a dose-dependent manner. These data demonstrate that Pgp plays a critical role in protecting renal epithelial cells from cyclosporine toxicity. The inhibitory effect of sirolimus on Pgp-mediated efflux and the cellular concentration of cyclosporine could explain the exacerbation of cyclosporine nephrotoxicity observed clinically.

Apoptosis and Caspase-3 in Long-Term Renal Ischemia/Reperfusion Injury in Rats and Divergent Effects of Immunosuppressants

BACKGROUND

Caspase-3 plays a key role in apoptosis, but the involvement of apoptosis and caspase-3 in mediating long-term ischemia/reperfusion (I/R) and immunosuppressive injury are not fully defined. The present study was undertaken to investigate apoptosis and caspase-3 in a renal I/R injury rat model with or without immunosuppression.

METHODS

The right renal pedicle was clamped for 45 minutes and left nephrectomy was induced. Cyclosporin A (CsA), tacrolimus (Tac), rapamycin (Rap), or mycophenolate mofetil (MMF) were administered daily. Animals were killed at 16 weeks, and the levels of apoptosis (with in situ end-labeling fragmented DNA), caspase-3 protein (with immunohistochemistry, Western blotting, and activity assay), and messenger RNA (mRNA; with quantitative reverse-transcriptase polymerase chain reaction) were evaluated.

RESULTS

Kidneys with I/R injury showed increased apoptosis in tubular and interstitial areas compared with control kidneys. Tacrolimus, Rap, and MMF significantly reduced apoptosis, but CsA did not. Distribution of full-length caspase-3 widened in I/R-injured kidneys from normal distal tubules and collecting ducts to dilated proximal tubules and expanded interstitium, whereas active caspase-3 was mainly scattered in damaged tubules and interstitium. Active caspase-3 staining and 24-kDa active caspase-3 protein was enhanced in I/R-injured and CsA-treated kidneys, but decreased by Tac, Rap, and MMF. These results were also consistent with changes in caspase-3 activity. Although caspase-3 mRNA levels were significantly increased in uninephrectomy and I/R-injured kidneys, they were not significantly affected by the immunosuppressants. In addition, all changes detected were positively correlated with renal structure and function.

CONCLUSION

Apoptosis and caspase-3 are not only involved in the long-term renal I/R injury, but also mediate the divergent effects of immunosuppression in this model.

Protective effect of calceolarioside on adriamycin-induced cardiomyocyte toxicity

Adriamycin is a potent antitumor drug that is known to cause severe cardiotoxicity. This study examined the protective effect of calceolarioside on adriamycin-induced cardiomyocyte toxicity. Calceolarioside significantly inhibited the adriamycin induced cell death and caspase-3 activation, which may be explained by the increase in Bcl-2 expression and the inhibition of Bax expression. Calceolarioside increased the expression of the antioxidant molecules and decreased the level of intracellular reactive oxygen species. Catalase, glutathione, N-acetylcysteine, Mannitol and Mn-TBAP (manganese (III) tetrakis-(4-benzoic acid) porphyrin) significantly inhibited the H9c2 cell death induced by adriamycin. Calceolarioside significantly inhibited H9c2 cell death, and was more effective than that observed with the other antioxidants, including probucol, ascorbic acid, and alpha-tocopherol. Overall, these results suggest that calceolarioside can inhibit adriamycin-induced apoptosis in H9c2 cardiomyocyte by inhibiting the generation of reactive oxygen species. Calceolarioside may be a potential candidate agent that inhibits cardiomyocyte-toxicity in adriamycin-exposed patients.

Inhibitory effects of rosmarinic acid on adriamycin-induced apoptosis in H9c2 cardiac muscle cells by inhibiting reactive oxygen species and the activations of c-Jun N-terminal kinase and extracellular signal-regulated kinase

Rosmarinic acid (RA) is a naturally occurring polyphenolic and is found in several herbs in the Lamiaceae family, such as, Perilla frutescens. ADR is a potent anti-tumor drug, but is unfortunately potently cardiotoxic. This study was undertaken to investigate the inhibitory effect of RA on ADR-induced apoptosis in H9c2 cardiac muscle cells at a mechanistic level. In vitro, ADR significantly decreased the viabilities of H9c2 cells, and this was accompanied by apoptotic features, such as a change in nuclear morphology and caspase protease activation. RA was found to markedly inhibit these apoptotic characteristics by reducing intracellular ROS generation and by recovering the mitochondria membrane potential (delta psi). In addition, RA reversed the downregulations of GSH, SOD and Bcl-2 by ADR. In the present study, ADR was found to activate c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), transcriptional factor-activator-protein (AP)-1. We found that c-fos, Jun-B, Jun-D and p-c-Jun were super shifted by ADR, indicating that these proteins have an important role in the ADR-induced AP-1 activation. The inhibitions of JNK and ERK using appropriate inhibitors or dominant negative cell lines reduced ADR-induced apoptosis in H9c2 cardiac muscle cells. Taken together, these results suggest that RA can inhibit ADR-induced apoptosis in H9C2 cardiac muscle cells by inhibiting ROS generation and JNK and ERK activation. Thus, we propose that RA should be viewed as a potential chemotherapeutic that inhibits cardiotoxicity in ADR-exposed patients.

Rosiglitazone protects against cyclosporine-induced pancreatic and renal injury in rats

Rosiglitazone (RGTZ) has protective effect against various types of injury. This study was performed to evaluate the effect of RGTZ on pancreatic and renal injury caused by cyclosporine (CsA). CsA (15 mg/kg) and RGTZ (3 mg/kg) were administered alone and together to the rats for 28 days. The effect of RGTZ on CsA-induced pancreatic injury was evaluated by intraperitoneal glucose tolerance test (IPGTT), plasma insulin concentrations and pancreatic beta-cell morphology. The effect of RGTZ on CsA-induced renal injury was evaluated by assessing renal function and pathology; mediators of inflammation and fibrosis such as angiotensin II (AngII), osteopontin (OPN) and transforming growth factor-beta1 (TGF-beta1) and apoptotic cell death. Four weeks of CsA treatment caused diabetes, renal dysfunction, typical pathologic lesions (arteriolopathy, interstitial fibrosis and inflammatory cells infiltration) and apoptotic cell death. RGTZ treatment decreased blood glucose concentration, increased plasma insulin concentration and preserved pancreatic beta islet mass. RGTZ treatment improved renal function and histopathology. Pro-inflammatory and pro-fibrotic molecules such as AngII, OPN and TGF-beta1, and apoptotic cell death also decreased with RGTZ treatment. These data suggest that RGTZ has a protective effect against CsA-induced pancreatic and renal injury.

Fetoplacental transport and utilization of amino acids in IUGR — a review

Amino acids have multiple functions in fetoplacental development. The supply of amino acids to the fetus involves active transport across and metabolism within the trophoblast. Transport occurs through various amino acid transport systems located on both the maternal and fetal facing membranes, many of which have now been documented to be present in rat, sheep and human placentas. The capacity of the placenta to supply amino acids to the fetus develops during pregnancy through alterations in such factors as surface area and specific time-dependent transport system expression. In intrauterine growth restriction (IUGR), placental surface area and amino acid uptakes are decreased in human and experimental animal models. In an ovine model of IUGR, produced by hyperthermia-induced placental insufficiency (PI-IUGR), umbilical oxygen and essential amino acid uptake rates are significantly reduced in the most severe cases in concert with decreased fetal growth. These changes indicate that severe IUGR is likely associated with a shift in amino acid transport capacity and metabolic pathways within the fetoplacental unit. After transport across the trophoblast in normal conditions, amino acids are actively incorporated into tissue proteins or oxidized. In the sheep IUGR fetus, however, which is hypoxic, hypoglycemic and hypoinsulinemic, there appear to be net effluxes of amino acids from the liver and skeletal muscle, suggesting changes in amino acid metabolism. Potential changes may be occurring in the insulin/IGF-I signaling pathway that includes decreased production and/or activation of specific signaling proteins leading to a reduced protein synthesis in fetal tissues. Such observations in the placental insufficiency model of IUGR indicate that the combination of decreased fetoplacental amino acid uptake and disrupted insulin/IGF signaling in liver and muscle account for decreased fetal growth in IUGR.

Effect of colchicine on cyclosporine nephrotoxicity, reduction of TGF-beta overexpression, apoptosis, and oxidative damage: an experimental animal study

BACKGROUND

Proinflamatory and profibrotic cytokines may be responsible for the cyclosporine A nephrotoxicity. Increased levels of apoptosis, free oxygen redicals, and transforming growth factor beta (TGF-beta), may play an important roles in the pathogenesis of nephrotoxicity. In this experimental animal study, we sought to investigate the effects of colchicine on the cyclosporine nephrotoxicity.

METHOD

Twenty-four Wistar albino rats were divided into three groups: cyclosporine 15 mg/kg subcutaneously (SC); cyclosporine 15 mg/kg SC plus colchicine 30 mcg/kg orally; and a control group; equal doses of olive oil orally were administered to groups 1, 2, and 3. Renal function, cyclosporine levels, and serum malonyldialdehyde (MDA) levels were measured at the end of 4 weeks. Apoptosis, TGF-beta, and other findings were detected in renal tissue with the TUNEL method, with a immunohistochemical method, and with routine staining procedures, respectively.

RESULTS

There were significant differences in the values of mean creatinine clearance between group 1 and group 3 and between group 2 and group 3 (P < .05 for each comparison), but not between group 1 and group 2 (P > .05). MDA levels in group 1 were high compared with the control group (P < .05) with a trend toward elevation relative to group 2 but the results were not statistically significant (P > .05). Renal tubular vacuolization in group 1 and group 2 animal were greater than in the control group, but no significant difference were observed between any of the groups (P > .05). Mononuclear cell infiltration in group 1 and group 2 hosts were higher than the control group, but there was no significant differences between the groups (P > .05). Afferent arteriolar hyalinization was observed group 1 and 2 but not group 3. There was a statistically significant difference between group 1 and group 3 and between group 2 and group 3 (P < .05 for each comparison). The expression level of TGF-beta was higher in group 1 than group 2 or group 3 (P <.05 for each comparison) but group 2 and group 3 were similar (P > .05). Apoptotic cell death count of group 1 was higher than that in group 2 or group 3 (P < .05, for each comparison); moreover, group 2 also showed greater numbers of apoptotic cells than group 3 (P < .001). At the end of the 4 weeks, there was no intersititial fibrosis in any of the hosts.

CONCLUSION

While cyclosporine caused increased TGF-beta expression and apoptotic cell death in the renal tissue of rats colchicine prevented the increase in MDA serum levels, TGF-beta expression, and apoptosis in renal tissue. Our study suggests that colchicine may diminish the cyclosporine nephrotoxicity by its suppressing the expression of TGF-beta, apoptotic cell death, and MDA production.