The angiotensin receptor neprilysin inhibitor LCZ696 attenuates renal fibrosis via ASK1/JNK/p38 MAPK-mediated apoptosis in unilateral ureteral obstruction.

The angiotensin receptor neprilysin inhibitor LCZ696 affords superior cardioprotection and renoprotection compared with renin-angiotensin blockade monotherapy, but the underlying mechanisms remain elusive. Herein, we evaluated whether LCZ696 attenuates renal fibrosis by inhibiting ASK1/JNK/p38 mitogen-activated protein kinase (MAPK)-mediated apoptosis in a rat model of unilateral ureteral obstruction (UUO) and in vitro. Rats with UUO were treated daily for 7 days with LCZ696, valsartan, or the selective ATP competitive inhibitor of apoptosis signal-regulating kinase 1 (ASK1), GS-444217. The effects of LCZ696 on renal injury were examined by assessing the histopathology, oxidative stress, intracellular organelles, apoptotic cell death, and MAPK pathways. H2O2-exposed human kidney 2 (HK-2) cells were also examined. LCZ696 and valsartan treatment significantly attenuated renal fibrosis caused by UUO, and this was paralleled by downregulation of proinflammatory cytokines and decreased inflammatory cell influx. Intriguingly, LCZ696 had stronger effects on renal fibrosis and inflammation than valsartan. UUO-induced oxidative stress triggered mitochondrial destruction and endoplasmic reticulum stress, which resulted in apoptotic cell death; these effects were reversed by LCZ696. Both GS-444217 and LCZ696 hampered the expression of death-associated ASK1/JNK/p38 MAPKs. In H2O2-treated HK-2 cells, LCZ696 and GS-444217 increased cell viability but decreased the production of intracellular reactive oxygen species and MitoSOX and apoptotic cell death. Both agents also deactivated H2O2-stimulated activation of ASK1/JNK/p38 MAPKs. These findings suggest that LCZ696 protects against UUO-induced renal fibrosis by inhibiting ASK1/JNK/p38 MAPK-mediated apoptosis.

Nicotine exacerbates tacrolimus-induced renal injury by programmed cell death.

BACKGROUND/AIMS: Cigarette smoking is an important modifiable risk factor in kidney disease progression. However, the underlying mechanisms for this are lacking. This study aimed to assess whether nicotine (NIC), a major toxic component of cigarette smoking, would exacerbates tacrolimus (TAC)-induced renal injury. METHODS: Sprague-Dawley rats were treated daily with NIC, TAC, or both drugs for 4 weeks. The influence of NIC on TAC-caused renal injury was examined via renal function, histopathology, oxidative stress, mitochondria, endoplasmic reticulum (ER) stress, and programmed cell death (apoptosis and autophagy). RESULTS: Both NIC and TAC significantly impaired renal function and histopathology, while combined NIC and TAC treatment aggravated these parameters beyond the effects of either alone. Increased oxidative stress, ER stress, mitochondrial dysfunction, proinf lammatory and profibrotic cytokine expressions, and programmed cell death from either NIC or TAC were also aggravated by the two combined. CONCLUSION: Our observations suggest that NIC exacerbates chronic TAC nephrotoxicity, implying that smoking cessation may be beneficial for transplant smokers taking TAC.

L-Carnitine protects against tacrolimus-induced renal injury by attenuating programmed cell death via PI3K/AKT/PTEN signaling.

Reducing immunosuppressant-related complications using conventional drugs is an efficient therapeutic strategy. L-carnitine (LC) has been shown to protect against various types of renal injury. In this study, we investigated the renoprotective effects of LC in a rat model of chronic tacrolimus (TAC) nephropathy. SD rats were injected with TAC (1.5 mg · kg-1 · d-1, sc) for 4 weeks. Renoprotective effects of LC were assessed in terms of renal function, histopathology, oxidative stress, expression of inflammatory and fibrotic cytokines, programmed cell death (pyroptosis, apoptosis, and autophagy), mitochondrial function, and PI3K/AKT/PTEN signaling. Chronic TAC nephropathy was characterized by severe renal dysfunction and typical histological features of chronic nephropathy. At a molecular level, TAC markedly increased the expression of inflammatory and fibrotic cytokines in the kidney, induced oxidative stress, and led to mitochondrial dysfunction and programmed cell death through activation of PI3K/AKT and inhibition of PTEN. Coadministration of LC (200 mg · kg-1 · d-1, ip) caused a prominent improvement in renal function and ameliorated histological changes of kidneys in TAC-treated rats. Furthermore, LC exerted anti-inflammatory and antioxidant effects, prevented mitochondrial dysfunction, and modulated the expression of a series of apoptosis- and autophagy-controlling genes to promote cell survival. Human kidney proximal tubular epithelial cells (HK-2 cells) were treated with TAC (50 µg/mL) in vitro, which induced production of intracellular reactive oxygen species and expression of an array of genes controlling programmed cell death (pyroptosis, apoptosis, and autophagy) through interfering with PI3K/AKT/PTEN signaling. The harmful responses of HK-2 cells to TAC were significantly attenuated by cotreatment with LC and the PI3K inhibitor LY294002 (25 µM). In conclusion, LC treatment protects against chronic TAC nephropathy through interfering the PI3K/AKT/PTEN signaling.

Exogenous pancreatic kininogenase protects against renal fibrosis in rat model of unilateral ureteral obstruction.

Tissue kallikrein has protective function against various types of injury. In this study, we investigated whether exogenous pancreatic kininogenase (PK) conferred renoprotection in a rat model of unilateral ureteral obstruction (UUO) and H2O2-treated HK-2 cells in vitro. SD rats were subjected to UUO surgery, then PK (7.2 U/g per day, ip) was administered for 7 or 14 days. After the treatment, rats were euthanized; the obstructed kidneys were harvested for further examination. We found that PK administration significantly attenuated interstitial inflammation and fibrosis, and downregulated the expression of proinflammatory (MCP-1, TLR-2, and OPN) and profibrotic (TGF-ß1 and CTGF) cytokines in obstructed kidney. UUO-induced oxidative stress, closely associated with excessive apoptotic cell death and autophagy via PI3K/AKT/FoxO1a signaling, which were abolished by PK administration. We further showed that PK administration increased the expression of bradykinin receptors 1 and 2 (B1R and B2R) mRNA and the production of NO and cAMP in kidney tissues. Coadministration with either B1R antagonist (des-Arg9-[Leu8]-bradykinin) or B2R antagonist (icatibant) abrogated the renoprotective effects of PK, and reduced the levels of NO and cAMP in obstructed kidney. In H2O2-treated HK-2 cells, addition of PK (6 pg/mL) significantly decreased ROS production, regulated the expression of oxidant and antioxidant enzymes, suppressed the expression of TGF-ß1 and MCP-1, and inhibited cell apoptosis. Our data demonstrate that PK treatment protects against the progression of renal fibrosis in obstructed kidneys.

Shen-Kang protects against tacrolimus-induced renal injury.

BACKGROUND/AIMS: Evidence suggests that Shen-Kang (SK), a traditional Chinese herbal medicine, protects against various types of renal injury. In this study, we evaluated whether SK treatment confers renoprotection in a rat model of chronic tacrolimus (TAC) nephropathy. METHODS: Rats were treated daily with TAC (1.5mg/kg, subcutaneously) and SK (450 mg/kg, intravenously) for 4 weeks. The effects of SK on TAC-induced renal injury were assessed by measuring renal function, urine albumin excretion, histopathology, inflammatory cell infiltration, expression of profibrotic (transforming growth factor ß1 [TGF-ß1] and TGF-ß inducible gene-h3 [ßig-h3]) and proinflammatory cytokines, oxidative stress, and apoptotic cell death. RESULTS: Administration of SK preserved glomerular integrity (fractional mesangial area and Wilms tumor 1-positive glomeruli), attenuated tubulointerstitial fibrosis, and reduced the number of ectodermal dysplasia 1-positive cells, and this was paralleled by improved urine albumin excretion and renal dysfunction. At the molecular level, SK treatment suppressed expression of TGF-ß1/Smad2/3, ßig-h3, and proinflammatory cytokines. Oxidative stress and apoptotic cell death were significantly decreased with SK treatment, and apoptosis-related genes were regulated toward cell survival (active caspase-3 and the B-cell lymphoma-2/Bcl2-associated X [Bcl-2/Bax] ratio). CONCLUSION: SK protects against TAC-induced renal injury.

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, ß 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 ß 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 ß 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 ß 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 ß cell injury via reducing oxidative stress.

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.

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 (3×10(6)/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.

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.

Higher infiltration by Th17 cells compared with regulatory T cells is associated with severe acute T-cell-mediated graft rejection.

The aim of this study was to evaluate whether the Th17 and Treg cell infiltration into allograft tissue is associated with the severity of allograft dysfunction and tissue injury in acute T cell-mediated rejection (ATCMR). Seventy-one allograft tissues with biopsy-proven ATCMR were included. The biopsy specimens were immunostained for FOXP3 and IL-17. The allograft function was assessed at biopsy by measuring serum creatinine (Scr) concentration, and by applying the modified diet in renal disease (MDRD) formula, which provides the estimated glomerular filtration rate (eGFR). The severity of allograft tissue injury was assessed by calculating tissue injury scores using the Banff classification. The average numbers of infiltrating Treg and Th17 cells were 11.6 ± 12.2 cells/mm² and 5.6 ± 8.0 cells/mm², respectively. The average Treg/Th17 ratio was 5.6 ± 8.2. The Treg/Th17 ratio was significantly associated with allograft function (Scr and MDRD eGFR) and with the severity of interstitial injury and tubular injury (P < 0.05, all parameters). In separate analyses of the number of infiltrating Treg and Th17 cells, Th17 cell infiltration was significantly associated with allograft function and the severity of tissue injury. By contrast, Treg cell infiltration was not significantly associated with allograft dysfunction or the severity of tissue injury. The results of this study show that higher infiltration of Th17 cell compared with Treg cell is significantly associated with the severity of allograft dysfunction and tissue injury.

Clinical significance of slow recovery of graft function in living donor kidney transplantation.

BACKGROUND: The clinical significance of slow recovery of graft function (SGF) in living donor kidney transplantation is unclear. We evaluated the incidence, risk factors, and clinical outcome of SGF in living donor transplantation. METHODS: Three hundred ten living donor kidney recipients were included and categorized into immediate recovery of graft function (IGF; n=239) and SGF (n=71), according to estimated glomerular filtration rate (60 mL/min/1.73 m) at posttransplant day 14. We compared the clinical parameters, protocol biopsy findings, acute rejection (AR), and 10-year graft survival between the two groups. RESULTS: The SGF group had an older recipient age, lower ratio of donor to recipient body mass index, and higher incidence of AR than IGF group, as shown by protocol biopsies. The SGF group had significantly more AR episodes than IGF group within 12 months (21.1% vs. 13.4%, P<0.05) and during follow-up period (32.4% vs. 20.1%, P<0.05). The 10-year graft survival rate did not differ between groups, but AR presence was significantly associated with a lower graft survival in the SGF group than the IGF group (64.9% vs. 78.9%, P<0.05). CONCLUSIONS: SGF in the early posttransplant period is immunologically active and should be considered as one of the risk factors for determining long-term graft survival in living donor kidney transplantation.