Kyoung Chan Doh

Chronic cyclosporine nephropathy is characterized by excessive autophagosome formation and decreased autophagic clearance.

Background The study was performed to investigate the influence of cyclosporine A (CsA)–induced renal injury on autophagy in an experimental model of chronic CsA nephropathy. Methods Three dosages of CsA (7.5, 15, and 30 mg/kg/day) were administered to mice for 4 weeks. The formation of autophagosomes was measured with microtubule-associated protein 1 light chain 3 phospholipid-conjugated form (LC3-II) and beclin-1, and the ability of autophagic clearance was examined with sequestosome-1 (p62). Autophagic vacuoles were visualized and counted using electron microscopy. Double immunolabeling of LC3-II and active caspase-3 was performed to evaluate the association between autophagy and apoptosis. Oxidative stress was evaluated by measuring urinary 8-hydroxy-2′-deoxyguanosine excretion, demonstrating oxidative DNA damage. Antioxidative drugs, pravastatin and N-acetylcysteine, were used to evaluate the role of CsA-induced oxidative stress on autophagy. Results CsA treatment increased the expressions of LC3-II and beclin-1 in the kidney in a dose-dependent manner. The number of p62-positive cells was also significantly increased in a CsA dose–dependent manner. Electron microscopy revealed excessive autophagic vacuoles in the CsA group compared with the vehicle group. Expression of active caspase-3 was increased in a CsA dose–dependent manner and was colocalized with LC3-II in the injured area of CsA-treated kidneys. Concurrent pravastatin or N-acetylcysteine treatment reduced urinary excretion of 8-hydroxy-2′-deoxyguanosine and subsequently decreased LC3-II expression and the number of p62-positive cells compared with the CsA group. Conclusions Chronic CsA nephropathy is a state of excessive autophagic vacuoles and decreased autophagic clearance. Oxidative stress may play an importation role in the induction of autophagy.

Ginseng Treatment Attenuates Chronic Cyclosporine Nephropathy via Reducing Oxidative Stress in an Experimental Mouse Model

Background: This study was performed to investigate whether ginseng extract has a protective effect in an experimental mouse model of chronic cyclosporine (CsA) nephropathy. Methods: Mice were treated with CsA (30 mg/kg/day, subcutaneously) with or without Korean red ginseng extract (KRG) (0.2, 0.4 g/kg/day, orally) on a 0.01% salt diet for 4 weeks. The effect of KRG on CsA-induced renal injury was evaluated by assessing renal function and pathology, mediators of inflammation, tubulointerstitial fibrosis and apoptotic cell death. Using an in vitro model, we also examined the effect of KRG on CsA-treated proximal tubular cells (HK-2). Oxidative stress was measured by assessing 8-hydroxy-2′-deoxyguanosine (8-OHdG) levels in 24-hour urine, tissue sections, and culture media. Results: Four weeks of CsA treatment caused renal dysfunction, typical pathologic lesions and apoptotic cell death. KRG treatment reduced serum creatinine and blood urea nitrogen and histopathology and increased creatinine clearance. Proinflammatory and profibrotic molecules such as induced nitric oxide synthase, cytokines, transforming growth factor (TGF)-β1 and TGF-β1-inducible gene h3 and apoptotic cell death, also decreased with KRG treatment. Consistent with these results, in vitro studies showed that addition of KRG protected against CsA-induced morphological changes, cytotoxicity, inflammation, and apoptotic cell death as demonstrated by annexin V binding. These changes were accompanied by decrease in the level of 8-OHdG in urine and culture supernatant after KRG treatment. Conclusion: The results of our in vivo and in vitro studies demonstrate that KRG has a protective effect in CsA-induced renal injury via reducing oxidative stress.

Dipeptidyl Peptidase IV Inhibitor MK-0626 Attenuates Pancreatic Islet Injury in Tacrolimus-Induced Diabetic Rats

Background Tacrolimus (TAC)-induced pancreatic islet injury is one of the important causes of new-onset diabetes in transplant recipients. This study was performed to evaluate whether a dipeptidyl peptidase IV (DPP IV) inhibitor is effective in improving TAC-induced diabetes mellitus by reducing pancreatic islet injury. Methods Rats were treated with TAC (1.5 mg/kg, subcutaneously) and the DPP IV inhibitor MK-0626 (10 or 20 mg/kg, oral gavage) for 4 weeks. The effect of MK-0626 on TAC-induced diabetes was evaluated by assessing pancreatic islet function, histopathology. TAC-induced incretin dysfunction was also examined based on active glucagon-like peptide-1 (GLP-1) levels in the serum after glucose loading. The protective effect of MK-0626 was evaluated by measuring markers of oxidative stress, oxidative resistance, and apoptosis. To determine whether enhanced GLP-1 signaling is associated with these protective effects, we measured the expression of the GLP-1 receptor (GLP-1R) and the effect of the GLP-1 analog exendin-4 on cell viability and oxidative stress in isolated islets. Results MK-0626 treatment attenuated TAC-induced pancreatic islet dysfunction and islet morphology. TAC treatment led to a defect in active GLP-1 secretion; however, MK-0626 reversed these effects. TAC treatment increased the level of 8-hydroxy-2′-deoxyguanosine (8-OHdG), the number of apoptotic death, and the level of active caspase-3, and decreased the level of manganese superoxide dismutase and heme oxygenase-1; MK-0626 treatment reversed these changes. MK-0626 treatment restored the expression of GLP-1R, and direct administration of exendin-4 to isolated islets reduced TAC-induced cell death and 8-OHdG expression. Conclusions The DPP IV inhibitor MK-0626wasan effective antidiabetic agent that exerted antioxidative and antiapoptotic effects via enhanced GLP-1 signaling in TAC-induced diabetics.

Influence of N-acetylcysteine on Klotho expression and its signaling pathway in experimental model of chronic cyclosporine nephropathy in mice.

Background Cyclosporine A (CsA)–associated oxidative stress has been proposed as an important mechanism of renal injury. This study was designed to examine whether N-acetylcysteine (NAC), a well-known antioxidant, affects Klotho, antiaging gene, expression and its signaling pathway in an experimental model of chronic CsA nephropathy. Methods Mice maintained on a low-sodium diet were given vehicle (olive oil, 1 mL/kg/day), CsA (30 mg/kg/day), NAC (150 mg/kg/day), or a combination of CsA and NAC for 4 weeks. The effect of NAC on CsA-induced renal injury was evaluated with basic parameters, histopathology, and markers of oxidative stress [8-hydroxy-2′-deoxyguanosine (8-OHdG) excretion and manganese superoxide dismutase (MnSOD) expression]. The influence of NAC on Klotho and its signal pathway (p-AKT and p-FoxO1) in CsA-treated mouse kidney was evaluated with immunohistochemistry and/or immunoblot. Results Concomitant administration of CsA and NAC significantly improved renal function and attenuated tubulointerstitial fibrosis, and these changes were accompanied by decreased urinary 8-OHdG level and increased MnSOD expression. NAC treatment preserved Klotho gene expression compared with CsA treatment alone (P<0.05), and this correlated with urinary 8-OHdG excretion (r=–0.934) and MnSOD expression (r=0.873, P<0.001 for both). Concomitant treatment of CsA and NAC translocated FoxO1 from the cytoplasm to the nucleus, implicating dephosphorylation of FoxO1 by NAC in p-AKT/p-FoxO1 pathway. Conclusion NAC treatment preserves Klotho expression and modifies p-AKT/p-FoxO1 pathway in chronic CsA nephropathy.

Ginseng treatment attenuates autophagic cell death in chronic cyclosporine nephropathy

Chronic cyclosporine (CsA) treatment induces autophagic cell death characterized by excessive autophagosome formation and decreased autophagic clearance. In this study, we evaluated the influence of ginseng treatment on autophagy in chronic CsA nephropathy.

Combined treatment of tacrolimus and everolimus increases oxidative stress by pharmacological interactions.

Background Drug-drug interaction between everolimus (EVR) and tacrolimus (TAC) is still undetermined. We evaluated whether EVR enhances TAC-induced organ injury through drug-drug interaction. Methods Tacrolimus (6 mg/kg) was given to rats with or without EVR (1 or 2 mg/kg) orally for 4 weeks. The influences of EVR on TAC-induced organ injury were evaluated in terms of nephrotoxicity and pancreatic islet dysfunction. Drug-drug interaction was evaluated by measuring the level of each drug in the blood and target tissue, and the correlation between the two drugs was observed in the blood and target tissue. The concentration of 8-hydroxy-2′-deoxyguanosine in blood or urine was measured as a marker of oxidative stress, and correlation between drug levels and oxidative stress was also evaluated. Results Tacrolimus treatment alone did not cause overt renal or pancreatic islet injury, but the addition of EVR significantly enhanced the TAC-induced organ injury, as demonstrated by aggravated nephrotoxicity and pancreatic islet dysfunction. The combination of EVR and TAC significantly increased each drug level in the target tissues as well as in blood, and there was good correlation between the two drugs in blood and target organs. The serum and urinary levels of 8-hydroxy-2′-deoxyguanosine were significantly increased in the TAC+EVR group compared with the TAC- or EVR-alone group and were well correlated with drug levels in blood and tissues. Conclusions Everolimus enhances TAC-induced target organ injury by increasing oxidative stress via pharmacological interaction in blood and target tissue. This finding provides a better understanding of the effects of EVR when used in combination with TAC.

Human Adipose Tissue Derived Mesenchymal Stem Cells Aggravate Chronic Cyclosporin Nephrotoxicity by the Induction of Oxidative Stress

The aim of this study was to investigate whether hATMSCs protect against cyclosporine (CsA)-induced renal injury. CsA (7.5 mg/kg) and hATMSCs (3×106/5 mL) were administered alone and together to rats for 4 weeks. The effect of hATMSCs on CsA-induced renal injury was evaluated by assessing renal function, interstitial fibrosis, infiltration of inflammatory cells, and apoptotic cell death. Four weeks of CsA-treatment produced typical chronic CsA-nephropathy. Combined treatment with CsA and hATMSCs did not prevent these effects and showed a trend toward further renal deterioration. To evaluate why hATMSCs aggravated CsA-induced renal injury, we measured oxidative stress, a major mechanism of CsA-induced renal injury. Both urine and serum 8-hydroxydeoxyguanosine(8-OHdG) levels were higher in the CsA+hATMSCs group than in the CsA group (P<0.05). An in vitro study showed similar results. Although the rate of apoptosis did not differ significantly between HK-2 cells cultured in hATMSCs-conditioned medium and those cultured in DMEM, addition of CsA resulted in greater apoptosis in HK-2 cells cultured in hATMSCs-conditioned medium. Addition of CsA increased oxidative stress in the hATMSCs-conditioned medium. The results of our study suggest that treatment with hATMSCs may aggravate CsA-induced renal injury because hATMSCs cause oxidative stress in the presence of CsA.

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.

Increase of Th17 Cell Phenotype in Kidney Transplant Recipients with Chronic Allograft Dysfunction

This study was performed to determine the association of Th17 cell phenotype with chronic allograft dysfunction in kidney transplant recipients (KTRs). We compared the expression of Th17 cell phenotype in KTRs with chronic allograft dysfunction group (CAD, n = 52) with four control groups (long-term stable KTRs (LTS, n = 67), early stable KTRs (ES, n = 28), end stage renal disease (ESRD, n = 45), and healthy control (HC, n = 26). We also performed in vitro study using human proximal renal tubular epithelial cell line (HPRTEpiC) to evaluate the effect of IL-17 on human renal tubular epithelial cells. The CAD group showed increased percentage of Th17 cells out of CD4+ T cells and also increased proportion of IL-17 producing cells out of effector memory T cells or out of CCR4+CCR6+/CD4+ T cells compared to the LTS group and other control groups. Also, the serum level of IL-17, IL-33, and RAGE, and the expression of IL-1beta, RAGE, and HMGB1 mRNA showed an increase in the CAD group compared to the LTS group. In vitro study revealed that IL-17 increased production of IL-6 and IL-8 and up-regulated profibrotic gene expression such as ACTA-2 and CTGF in HPRTEpiC in a dose-dependent manner, which suggests that IL-17 has a role in the development of renal tubular cell injury. The results of our study may suggest that increase of Th17 cell phenotype could be a marker for the chronic allograft injury; hence there is a need to develop diagnostic and therapeutic tools targeting the Th17 cells pathway.

Clinical Significance of Pre- and Post-Transplant BAFF Levels in Kidney Transplant Recipients.

It is well known that pre-transplant B cell activating factor (BAFF) levels are associated with the development of de novo anti-HLA antibodies and antibody mediated rejection post-transplant. However, the clinical significance of BAFF values at allograft rejection has not been determined. In this study, we investigated the clinical significance of pre-transplant BAFF level as well as post-transplant BAFF levels measured when indication biopsy was done. We checked for anti-HLA antibodies in 115 kidney transplant recipients who required allograft biopsy due to an increase in serum creatinine. With the same serum specimen, we measured BAFF levels, and in 78 of these patients, pre-transplant BAFF and anti-HLA antibody levels were detected as well. Patients in each group were divided into tertiles according to BAFF levels. We investigated the relationship between BAFF levels and the occurrence of anti-HLA antibodies. Pre-transplant BAFF levels showed significant association with pre-transplant sensitization, and also with early rejection (Tertile 3, 26.9% vs. Tertile 1, 11.5%; P<0.05). Post-transplant BAFF levels showed significant association with pre-transplant sensitization, but did not show association with anti-HLA antibodies and positive donor-specific antibodies at the time of biopsy. We did not find any association between post-transplant BAFF levels and allograft biopsy results, Banff scores and microvascular inflammation scores. In conclusion, pre-transplant BAFF levels are associated with pre-transplant sensitization and are useful in predicting allograft rejection. But post-transplant BAFF levels measured at the time of indication biopsy are not associated with the appearance of de novo HLA-DSA, allograft rejection, biopsy findings and other allograft outcomes.