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.

Expression of brain-derived neurotrophic factor in kidneys from normal and cyclosporine-treated rats.

BACKGROUND: Accumulating evidence suggests that a decrease in brain-derived neurotrophic factor (BDNF) level induces a variety of psychiatric and neurological disorders. However, the expression and role of BDNF in the kidney have not been explored. The present study examined the expression of BDNF and tropomyosin-related kinase (Trk) receptors in an experimental model of chronic cyclosporine A (CsA) nephropathy. METHODS: Sprague-Dawley rats on a salt-deplete diet were treated daily for four weeks with vehicle or CsA. Urine profiles, apoptotic cell death, oxidative stress (8-hydroxy-2'-deoxyguanosine, 8-OHdG), and expression of BDNF and Trk receptors (TrkB and TrkC) were compared between groups. The impact of vasopressin infusion on the urine-concentrating ability was examined by measuring the expression of aquaporin-2 (AQP-2) and BDNF and urine profiles in normal and CsA-treated rats. RESULTS: Compared with the vehicle-treated rats, rats given CsA had enhanced urine volume and declined urine osmolality. Immunohistochemistry and immunoblotting showed that BDNF and Trk receptors were constitutively expressed in kidneys from vehicle-treated rats. This was confirmed by double immunofluorescent staining for Na-K-ATPase-α1, AQP-1, and AQP-2. By contrast, the expression of these factors decreased in kidneys from CsA-treated rats (BDNF: 51.1 ± 19.5% vs. 102.0 ± 30.3%, p < 0.01). Downregulation of BDNF was accompanied by impairment of urine osmolality, and this was reversed by exogenous infusion of vasopressin. Notably, the number of TUNEL-positive cells correlated negatively with BDNF expression and positively with urinary 8-OHdG excretion. CONCLUSIONS: BDNF is expressed in the collecting duct of the kidney and may be associated with urine-concentrating ability in an experimental model of chronic CsA-induced nephropathy. Our study provides a new avenue for further investigation of chronic CsA nephropathy.

Synergistic effects of leflunomide and benazepril in streptozotocin-induced diabetic nephropathy.

BACKGROUND: Leflunomide (LEF) and benazepril have renoprotective effects on diabetic nephropathy (DN) through their anti-inflammatory and anti-fibrotic activities. This study investigated whether combined treatment using LEF and benazepril affords superior protection compared with the respective monotherapies. METHODS: Diabetes was induced with streptozotocin (STZ, 65 mg/kg) by intraperitoneal injection in male Wistar rats. Two weeks after STZ injection, diabetic rats were treated daily for 12 weeks with LEF (10 mg/kg), benazepril (10 mg/kg), or a combination of both. Basic parameters (body weight, fasting blood glucose level, and 24 h urinary protein excretion), histopathology, inflammatory [inflammatory cell infiltration (ED-1), monocyte chemoattractant protein-1 (MCP-1), and Toll-like receptor-2 (TLR-2)] and glomerulosclerotic factors [transforming growth factor-ß1 (TGF-ß1) and connective tissue growth factor (CTGF)], and oxidative stress (8-hydroxy-2'-deoxyguanosine, 8-OHdG) were studied. RESULTS: Benazepril or LEF treatment significantly prevented body weight loss and 24 h urinary protein excretion induced by diabetes; combined treatment with LEF and benazepril further improved these parameters compared with giving each drug alone (all p < 0.01). Increased expression of inflammatory (MCP-1 and TLR-2) and glomerulosclerotic (TGF-ß1 and CTGF) factors in diabetic rat kidney was reduced by treatment with either LEF or benazepril and was further reduced by the combined administration of the two drugs (p < 0.01). These effects were accompanied by suppression of urinary 8-OHdG excretion. There was no significant between-group difference in blood glucose level. CONCLUSIONS: LEF treatment lessens DN, and combined treatment with LEF and benazepril provides synergistic effects in preventing DN.

Ginseng treatment attenuates autophagic cell death in chronic cyclosporine nephropathy.

AIMS: 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. METHODS: Mice were treated with CsA (30 mg/kg) with or without Korean red ginseng (KRG) extract (0.2, 0.4 g/kg) for 4 weeks. The effect of KRG on CsA-induced autophagosome formation was measured using phospholipid-conjugated form of LC3-II, beclin-1, and autophagic vacuoles were visualized with electron microscopy. Autophagic clearance was evaluated by accumulation of p62/sequestosome 1 (p62) and ubiquitin, then double immunolabeling for p62 and either LC3-II or ubiquitin. To demonstrate the association between the effects of KRG treatment on autophagy and apoptosis, double immunolabelling for LC3-II and active caspase-3 was performed. Multiple autophagy pathways were also examined. RESULTS: KRG co-treatment significantly decreased the expression of LC3-II, beclin-1, and the number of autophagic vacuoles compared with the CsA group, and these changes were accompanied by improvements in renal dysfunction and fibrosis. CsA-induced accumulation of p62 and ubiquitin was also decreased by KRG treatment, and these proteins were colocalized with LC3-II and with each other. KRG treatment simultaneously reduced the expression of both active caspase-3 and LC3-II in the injured area. KRG treatment during chronic CsA nephropathy induced the expression of AKT/mTOR, which is a pathway that inhibits autophagy, and reduced AMPK expression. CONCLUSION: Ginseng treatment attenuated CsA-induced excessive autophagosome formation and autophagic aggregates. These findings suggest that ginseng has a renoprotective effect against CsA-induced autophagic cell death.

Pathogenesis and management of renal fibrosis induced by unilateral ureteral obstruction.

Regardless of the underlying etiology, renal fibrosis is the final histological outcome of progressive kidney disease. Unilateral ureteral obstruction (UUO) is an ideal and reproducible experimental rodent model of renal fibrosis, which is characterized by tubulointerstitial inflammatory responses, accumulation of extracellular matrix, tubular dilatation and atrophy, and fibrosis. The magnitude of UUO-induced renal fibrosis is experimentally manipulated by the species chosen, animal age, and the severity and duration of the obstruction, while relief of the obstruction allows the animal to recover from fibrosis. The pathogenesis of renal fibrosis is complex and multifactorial and is orchestrated by activation of renin-angiotensin system (RAS), oxidative stress, inflammatory response, transforming growth factor beta 1-Smad pathway, activated myofibroblasts, cell death (apoptosis, autophagy, ferroptosis, and necroptosis), destruction of intracellular organelles, and signaling pathway. The current therapeutic approaches have limited efficacy. Inhibition of RAS and use of antioxidants and antidiabetic drugs, such as inhibitors of sodium-glucose cotransporter 2 and dipeptidyl peptidase-4, have recently gained attention as therapeutic strategies to prevent renal scarring. This literature review highlights the state of the art regarding the molecular mechanisms relevant to the management of renal fibrosis caused by UUO.

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)-ß1 and TGF-ß1-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.

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.

Statin upregulates the expression of klotho, an anti-aging gene, in experimental cyclosporine nephropathy.

BACKGROUND: We recently reported that long-term cyclosporine (CsA)-induced oxidative stress is associated with decreased expression of klotho, an anti-aging gene. This study evaluated whether the antioxidant effect of statin might upregulate klotho expression in CsA-induced renal injury. METHODS: Two separate experiments were performed. First, the dose-dependent effect of statin on klotho expression was evaluated in normal mouse kidneys. Second, the effect of statin on klotho expression was evaluated in experimental chronic CsA nephropathy in mice. We performed immunohistochemistry and immunoblotting for klotho, Forkhead box O transcription factors [FoxOs; phosphorylated FoxO1 (p-FoxO1) and FoxO3a (p-FoxO3a)] and their target molecules, manganese superoxide dismutase (MnSOD), Bim and hemeoxygenase-1. RESULTS: Statin treatment upregulated klotho expression in a dose-dependent manner in the normal mouse kidney and alleviated the decrease in klotho expression in kidneys exhibiting CsA nephropathy. CsA administration increased p-FoxO1 expression and decreased p-FoxO3a expression, whereas concurrent statin treatment reversed these changes, increased the expression of the antioxidant enzymes MnSOD and hemeoxygenase-1 and decreased the expression of the pro-apoptotic protein Bim. CONCLUSION: Statin-mediated upregulation of klotho expression and differential regulation of FoxO expression promote resistance to CsA-induced oxidative stress.

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.

Determination of rituximab dose according to immunologic risk in ABO-incompatible kidney transplantation.

The adequate rituximab (RTX) dosage in ABO-incompatible transplantation (ABO-IKT) remains undetermined. We used two kinds of RTX dosage groups [low RTX (100 mg/m(2)) and typical RTX (375 mg/m(2)) dosage groups] according to immunologic risks and investigated the change of B-cell, anti-ABO antibodies, and the clinical outcome in ABO-IKT according to the RTX dose. Fifteen patients with high immunologic risk [panel reactive antibody (PRA) > 50%, retransplant, AB to O transplant] were assigned to typical RTX group and 17 patients without risk were assigned to low RTX group. We compared the changes of B-cell, anti-ABO antibody titer, required number of plasmapheresis (PP), and the clinical outcome after transplantation between the two groups. After infusion of RTX, peripheral blood B-cell counts were successfully depleted to <1% in both groups. Before kidney transplantation (KT), the minimal number of PP to achieve the target titer (1:16) (2.6 ± 2.7 vs. 2.2 ± 2.5; p = 0.66) and the titer reduction rate of anti-ABO antibodies did not differ between the two groups (low RTX: 1.52 ± 1.21 vs. typical RTX: 1.53 ± 1.20, p = 0.94). After KT, anti-ABO antibody titer was suppressed less than 1:32 in both groups up to posttransplant 1 year. The allograft function and infectious complication did not differ between the two groups as well. In ABO-IKT, low RTX is comparable with typical RTX dosing with respect to B-cell depletion, antibody rebound suppression, the effect on clinical outcome in patients with low immunologic risk.

Inhibition of RIP1-RIP3-mediated necroptosis attenuates renal fibrosis via Wnt3α/ß-catenin/GSK-3ß signaling in unilateral ureteral obstruction.

Renal fibrosis represents the final common outcome of chronic kidney disease of virtually any etiology. However, the mechanism underlying the evolution of renal fibrosis remains to be addressed. This study sought to clarify whether RIP1-RIP3-mediated necroptosis is involved in renal fibrosis via Wnt3α/ß-catenin/GSK-3ß signaling in vitro and in a rat model of unilateral ureteral obstruction (UUO). Rats with UUO were administered RIP inhibitors (necrostatin-1 or GSK872) or ß-catenin/TCF inhibitor ICG-001 daily for 7 consecutive days. UUO caused significant renal tubular necrosis and overexpression of RIP1-RIP3-MLKL axis proteins, and was accompanied by activation of the NLRP3 inflammasome and renal fibrosis. Oxidative stress caused by UUO was closely associated with endoplasmic reticulum stress and mitochondrial dysfunction, which resulted in apoptotic cell death via Wnt3α/ß-catenin/GSK-3ß signaling. All of these effects were abolished by an RIP inhibitor (necrostatin-1 or GSK872) or ICG-001. In H2O2-treated HK-2 cells, both RIP inhibitor and ICG-001 decreased intracellular reactive oxygen species production and apoptotic cells, but increased cell viability. Activated Wnt3α/ß-catenin/GSK-3ß signaling was decreased by either RIP inhibitor or ICG-001. Our findings suggest that RIP1-RIP3-mediated necroptosis contributes to the development of renal fibrosis via Wnt3α/ß-catenin/GSK-3ß signaling in UUO and may be a therapeutic target for protection against renal scarring of other origins.

Coenzyme Q10 attenuates renal fibrosis by inhibiting RIP1-RIP3-MLKL-mediated necroinflammation via Wnt3α/ß-catenin/GSK-3ß signaling in unilateral ureteral obstruction.

OBJECTIVE: Coenzyme Q10 (CoQ10) protects against various types of injury, but its role in preventing renal scarring in chronic kidney disease remains an open question. Herein, we evaluated whether CoQ10 attenuates renal fibrosis by interfering with necroinflammation in a rat model of unilateral ureteral obstruction (UUO) and in vitro. METHODS: Rats with UUO were treated daily with CoQ10 or an RIP inhibitor (necrostatin-1 or GSK872) for 7 days. The influence of CoQ10 on renal injury caused by UUO was evaluated by histopathology and analysis of gene expression, oxidative stress, intracellular organelles, apoptosis, and Wnt3α/ß-catenin/GSK-3ß signaling·H2O2-exposed human kidney (HK-2) cells were also examined after treatment with CoQ10 or an RIP inhibitor. RESULTS: UUO induced marked renal tubular necrosis, upregulation of RIP1-RIP3-MLKL axis proteins, activation of the NLRP3 inflammasome, and evolution of renal fibrosis. UUO-induced oxidative stress evoked excessive endoplasmic reticulum stress and mitochondrial dysfunction, which triggered apoptotic cell death through Wnt3α/ß-catenin/GSK-3ß signaling. All of these effects were mitigated by CoQ10 or an RIP inhibitor. In H2O2-treated HK-2 cells, CoQ10 or an RIP inhibitor suppressed the expression of RIP1-RIP3-MLKL proteins and pyroptosis-related cytokines, and hindered the production of intracellular reactive oxygen species as shown by MitoSOX Red staining and apoptotic cell death but increased cell viability. The CoQ10 or Wnt/ß-catenin inhibitor ICG-001 deactivated H2O2-stimulated activation of Wnt3α/ß-catenin/GSK-3ß signaling. CONCLUSION: These findings suggest that CoQ10 attenuates renal fibrosis by inhibiting RIP1-RIP3-MLKL-mediated necroinflammation via Wnt3α/ß-catenin/GSK-3ß signaling in UUO.

Dapagliflozin Alleviates Renal Fibrosis by Inhibiting RIP1-RIP3-MLKL-Mediated Necroinflammation in Unilateral Ureteral Obstruction.

Dapagliflozin, a sodium-glucose cotransporter-2 inhibitor, offers renoprotection in diabetes. However, potential for use in nondiabetic kidney disease remains unknown. Herein, we assessed whether dapagliflozin alleviates renal fibrosis by interfering with necroinflammation in a rat model of unilateral ureteral obstruction (UUO) and in vitro. After induction of UUO, rats were administered dapagliflozin daily for seven consecutive days. UUO induced significant renal tubular necrosis and overexpression of RIP1-RIP3-MLKL axis proteins; these coincided with NLRP3 inflammasome activation, and subsequent development of renal fibrosis. Oxidative stress caused by UUO is tightly associated with endoplasmic reticulum stress and mitochondrial dysfunction, leading to apoptotic cell death through Wnt3α/ß-catenin/GSK-3ß signaling; all of which were abolished by both dapagliflozin and specific RIP inhibitors (necrostatin-1 and GSK872). In H2O2-treated HK-2 cells, dapagliflozin and RIP inhibitors suppressed overexpression of RIP1-RIP3-MLKL proteins and pyroptosis-related cytokines, decreased intracellular reactive oxygen species production and apoptotic cell death, whereas cell viability was improved. Moreover, activated Wnt3α/ß-catenin/GSK-3ß signaling was inhibited by dapagliflozin and Wnt/ß-catenin inhibitor ICG-001. Our findings suggest that dapagliflozin ameliorates renal fibrosis by inhibiting RIP1-RIP3-MLKL-mediated necroinflammation via Wnt3α/ß-catenin/GSK-3ß signaling in UUO.

L-carnitine treatment attenuates renal tubulointerstitial fibrosis induced by unilateral ureteral obstruction.

BACKGROUND/AIMS: Accumulating evidence indicates that L-carnitine (LC) protects against multiorgan damage through its antioxidant properties and preservation of the mitochondria. Little information is available about the effects of LC on renal fibrosis. This study examined whether LC treatment would provide renoprotection in a rat model of unilateral ureteral obstruction (UUO) and in vitro. METHODS: Sprague-Dawley rats that underwent UUO were treated daily with LC for 7 or 14 days. The influence of LC on renal injury caused by UUO was evaluated by histopathology, and analysis of gene expression, oxidative stress, mitochondrial function, programmed cell death, and phosphatidylinositol 3-kinase (PI3K)/ AKT/forkhead box protein O 1a (FoxO1a) signaling. In addition, H2O2-exposed human kidney cells (HK-2) were treated with LC. RESULTS: LC treatment inhibited expression of proinflammatory and profibrotic cytokines, and was followed by a significant attenuation of tubulointerstitial inflammation and fibrosis. The increased oxidative stress caused by UUO was associated with mitochondrial dysfunction and excessive apoptosis and autophagy via PI3K/AKT/FoxO1a-dependent signaling, and this was abrogated by administration of LC. In H2O2-exposed HK-2 cells, LC decreased intracellular production of reactive oxygen species, and suppressed expression of profibrotic cytokines and reduced the number of apoptotic cells. CONCLUSION: LC protects against the progression of tubulointerstitial fibrosis in an obstructed kidney.

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.

Upregulation of hyaluronan and its binding receptors in an experimental model of chronic cyclosporine nephropathy.

AIM: Hyaluronan (HA) is an important extracellular matrix (ECM) proteoglycan. The localization of HA and its binding receptors, CD44 and LYVE-1, was evaluated in an experimental model of chronic cyclosporine A (CsA)-induced nephropathy. METHODS: Sprague-Dawley rats maintained on a low-salt diet (0.05% sodium) received an s.c. injection of vehicle (1 mL/kg per day olive oil; VH groups) or CsA (15 mg/kg per day; CsA groups) for 1 or 4 weeks. Induction of chronic CsA nephropathy was evaluated according to renal function and pathology and expression of HA, CD44, LYVE-1, ED-1 and alpha-smooth muscle actin (alpha-SMA). RESULTS: CsA treatment for 4 weeks caused renal dysfunction, which was accompanied by typical striped interstitial fibrosis. In the VHroup, HA immunoreactivity was observed only in the inner medulla. However, the area of HA immunoreactivity increased with the duration of CsA treatment: CsA treatment for 1 week extended HA immunoreactivity to the outer medulla, and CsA treatment for 4 weeks caused a further extension of HA immunoreactivity to the cortex, which was vulnerable to CsA-induced renal injury. HA binding receptor, CD44 and LYVE-1 expression were also upregulated in the CsA groups, and were localized to the area of fibrosis and the peritubular capillaries of the cortex. In the CsA groups, ED-1 and alpha-SMA were predominantly expressed in fibrotic areas in which HA had accumulated. CONCLUSION: These findings suggest that upregulation of HA and its binding receptors are involved in interstitial fibrosis in chronic CsA-induced renal injury.

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.

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-0626 was an effective antidiabetic agent that exerted antioxidative and antiapoptotic effects via enhanced GLP-1 signaling in TAC-induced diabetics.