Prognostic value of chronicity grading on renal outcomes in patients with IgA nephropathy.

Many studies have shown that chronic changes are strong predictors of renal outcomes in various kidney diseases, including IgA nephropathy. The Mayo Clinic/Renal Pathology Society suggested a glomerulonephritis reporting system with a proposal for standardized grading of chronic changes. The purpose of this study was to predict renal outcomes in patients with IgA nephropathy using chronicity grading in comparison to the Oxford classification which did not include global sclerosis. A total of 4,151 patients with IgA nephropathy were enrolled from the Korean GlomeruloNephritis Study Group registry. Chronicity grading was categorized into minimal, mild, moderate, and severe according to the extent of chronic changes. The Oxford T and S scores were considered as chronic lesions. Three prediction models were constructed: the Oxford classification model (Oxford S plus T), chronicity grading model A (chronicity grading), and chronicity grading model B (chronicity grading plus Oxford S). Using these three prediction models, the primary renal outcome (end-stage renal disease) was evaluated using Cox regression analysis and prediction performance. During the median follow-up of 6.1 (2.7-9.9) years, 304 (7.3%) patients progressed to end-stage renal disease with a cumulative incidence rate of 1.02 events per 100 person-years. In a fully adjusted multivariable model, chronicity grading was independently associated with the primary renal outcome in both models A and B. Compared to the Oxford model, both models A and B showed improvements in model fit, but not in discrimination (ΔC 0.001; 95% CI, -0.010 to 0.013 and ΔC 0.002; 95% CI, -0.005 to 0.008, respectively). Model B demonstrated improvements in integrated discrimination improvement (0.01; 95% CI, 0-0.03) and continuous net reclassification improvement (0.49; 95% CI, 0.02-0.72). The severity of chronicity grading is closely related to adverse renal outcomes in patients with IgA nephropathy, and chronicity grading could provide additional information in clinical practice alongside the Oxford classification.

A multicenter, randomized, open-label, comparative, phase IV study to evaluate the efficacy and safety of combined treatment with mycophenolate mofetil and corticosteroids in advanced immunoglobulin A nephropathy.

BACKGROUND: It remains unclear whether immunosuppressive agents are effective in patients with immunoglobulin A nephropathy (IgAN). We investigated the efficacy of a mycophenolate mofetil (MMF) and corticosteroid combination therapy in patients with advanced IgAN. METHODS: We conducted a multicenter, randomized, placebo-controlled, parallel-group study of 48 weeks administration of MMF and corticosteroids in biopsy-proven advanced IgAN patients with estimated glomerular filtration rate (eGFR) of 20-50 mL/min/1.73 m2 and urine protein-to-creatinine ratio (UPCR) of >0.75 g/day. The primary outcome was complete (UPCR < 0.3 g/day) or partial (>50% reduction of UPCR compared to baseline) remission at 48 weeks. RESULTS: Among the 48 randomized patients, the percentage that achieved complete or partial remission was greater in the combination therapy group than in the control group (4.2% vs. 0% and 29.1% vs. 5.0%, respectively). Compared with the combination therapy group, eGFR in the control group decreased significantly from week 36 onward, resulting in a final adjusted mean change of -4.39 ± 1.22 mL/min/1.73 m2 (p = 0.002). The adjusted mean changes after 48 weeks were 0.62 ± 1.30 and -5.11 ± 1.30 mL/min/1.73 m2 (p = 0.005) in the treatment and control groups, respectively. The UPCR was significantly different between the two groups; the adjusted mean difference was -0.47 ± 0.17 mg/mgCr and 0.07 ± 0.17 mg/mgCr in the treatment and control group, respectively (p = 0.04). Overall adverse events did not differ between the groups. CONCLUSION: In advanced IgAN patients with a high risk for disease progression, combined MMF and corticosteroid therapy appears to be beneficial in reducing proteinuria and preserving renal function.

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.

Renal Outcome of IgM Nephropathy: A Comparative Prospective Cohort Study.

Immunoglobulin M nephropathy (IgMN) is an idiopathic glomerulonephritis characterized by diffuse deposits of IgM in the glomerular mesangium. However, its renal prognosis remains unknown. We compared renal outcomes of IgMN patients with those of patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), or mesangial proliferative glomerulonephritis (MsPGN) from a prospective observational cohort, with 1791 patients undergoing native kidney biopsy in eight hospitals affiliated with The Catholic University of Korea between December 2014 and October 2020. IgMN had more mesangial proliferation and matrix expansion than MsPGN and more tubular atrophy and interstitial fibrosis than MCD. IgMN patients had decreased eGFR than MCD patients in the earlier follow-up. However, there was no significant difference in urine protein or eGFR among all patients at the last follow-up. When IgMN was divided into three subtypes, patients with FSGS-like IgMN tended to have lower eGFR than those with MCD-like or MsPGN-like IgMN but higher proteinuria than MsPGN-like IgMN without showing a significant difference. The presence of hypertension at the time of kidney biopsy predicted ≥20% decline of eGFR over two years in IgMN patients. Our data indicate that IgMN would have a clinical course and renal prognosis similar to MCD, FSGS, and MsPGN.

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.

Consensus regarding diagnosis and management of atypical hemolytic uremic syndrome.

Thrombotic microangiopathy (TMA) is defined by specific clinical characteristics, including microangiopathic hemolytic anemia, thrombocytopenia, and pathologic evidence of endothelial cell damage, as well as the resulting ischemic end-organ injuries. A variety of clinical scenarios have features of TMA, including infection, pregnancy, malignancy, autoimmune disease, and medications. These overlapping manifestations hamper differential diagnosis of the underlying pathogenesis, despite recent advances in understanding the mechanisms of several types of TMA syndrome. Atypical hemolytic uremic syndrome (aHUS) is caused by a genetic or acquired defect in regulation of the alternative complement pathway. It is important to consider the possibility of aHUS in all patients who exhibit TMA with triggering conditions because of the incomplete genetic penetrance of aHUS. Therapeutic strategies for aHUS are based on functional restoration of the complement system. Eculizumab, a monoclonal antibody against the terminal complement component 5 inhibitor, yields good outcomes that include prevention of organ damage and premature death. However, there remain unresolved challenges in terms of treatment duration, cost, and infectious complications. A consensus regarding diagnosis and management of TMA syndrome would enhance understanding of the disease and enable treatment decision-making.

Changing pattern and safety of pretransplant malignancy in kidney transplant recipients.

BACKGROUND: Cancer rates are increasing not only in the general population but also in patients with end-stage renal disease. We investigated the changing pattern of pretransplant malignancy in kidney transplant recipients over 5 decades. METHODS: We reviewed 3,748 kidney transplant recipients between 1969 and 2016. We divided patients into three groups (1969-1998, 1999-2006, 2007-2016) based on the era of the cancer screening system used throughout the nation. We analyzed the incidence and pattern of pretransplant malignancy among the three groups. We also evaluated recurrent and de novo malignancy in these patients compared to patients without pretransplant malignancy. RESULTS: A total of 72 patients exhibited pretransplant malignancy (1.9%). There were no cases of pretransplant cancer until 1998, but the rate of pretransplant malignancy gradually increased to 1.1% during 1999-2006 and further increased to 4.3% thereafter. The most frequent types of pretransplant malignancy changed from the bladder, liver, and stomach cancers to thyroid cancer and renal cell carcinoma. There were no de novo cases, but there were three cases of recurrent cancer in patients with pretransplant malignancy; the recurrence rate among kidney transplant recipients with pretransplant malignancy was not significantly different from the incidence rate of de novo malignancy among kidney transplant recipients without pretransplant malignancy (4.2% vs. 6.9%, P = 0.48). CONCLUSION: The incidence of pretransplant malignancy in kidney transplantation candidates is gradually increasing, and recent increases were accompanied by changes in cancer types. Pretransplant malignancy may not be a hindrance to kidney transplantation because of the low incidence of posttransplant recurrence and de novo malignancy.

Clinical outcomes and effects of treatment in older patients with idiopathic membranous nephropathy.

BACKGROUND/AIMS: Membranous nephropathy (MN) is the most common primary glomerular disease diagnosed in older patients. Few reports describe the clinical outcomes in older patients with idiopathic MN. METHODS: The outcomes of 135 patients with histologically proven MN were analyzed. 'Older' was defined as 60 years of age or older at the time of the renal biopsy. The rates of complete remission (CR), progression to end-stage renal disease (ESRD) and infection were compared between older and younger patients. RESULTS: The cumulative event rate for achieving CR was inferior (p = 0.012) and that for requiring renal replacement was higher (p = 0.015) in older patients, and they had a greater risk of infection (p = 0.005). Older age was a significant predictor of a lower rate of CR (adjusted odds ratio [OR], 0.51; 95% confidence interval [CI], 0.26 to 0.98), and was a robust predictor of infection (adjusted OR, 5.27; 95% CI, 1.31 to 21.20). Conservative treatment was associated with a lower remission rate (p = 0.036) and corticosteroid treatment was less effective in achieving CR (p = 0.014), in preventing progression to ESRD (p = 0.013) and in reducing infection (p = 0.033) in older patients. Cyclosporine treatment had similar clinical outcomes with regard to CR, ESRD progression, and infection in older patients. CONCLUSION: Older age was independently associated with inferior rates of CR and greater risk of infection. Treatment modalities affected the outcomes of older patients differently in that cyclosporine treatment is predicted to be more useful than corticosteroids.

Inhibition of lymphatic proliferation by the selective VEGFR-3 inhibitor SAR131675 ameliorates diabetic nephropathy in db/db mice.

Recent studies have demonstrated that chronic inflammation-induced lymphangiogenesis plays a crucial role in the progression of various renal diseases, including diabetic nephropathy. SAR131675 is a selective vascular endothelial cell growth factor receptor-3 (VEGFR-3)-tyrosine kinase inhibitor that acts as a ligand for VEGF-C and VEGF-D to inhibit lymphangiogenesis. In this study, we evaluated the effect of SAR131675 on renal lymphangiogenesis in a mouse model of type 2 diabetes. Male C57BLKS/J db/m and db/db mice were fed either a regular chow diet or a diet containing SAR131675 for 12 weeks from 8 weeks of age. In addition, we studied palmitate-induced lymphangiogenesis in human kidney-2 (HK2) cells and RAW264.7 monocytes/macrophages, which play a major role in lymphangiogenesis in the kidneys. SAR131475 ameliorated dyslipidemia, albuminuria, and lipid accumulation in the kidneys of db/db mice, with no significant changes in glucose and creatinine levels and body weight. Diabetes-induced systemic inflammation as evidenced by increased systemic monocyte chemoattractant protein-1 and tumor necrosis factor-α level was decreased by SAR131475. SAR131475 ameliorated the accumulation of triglycerides and free fatty acids and reduced inflammation in relation to decreased chemokine expression and pro-inflammatory M1 macrophage infiltration in the kidneys. Downregulation of VEGF-C and VEGFR-3 by SAR131475 inhibited lymphatic growth as demonstrated by decreased expression of LYVE-1 and podoplanin that was further accompanied by reduced tubulointerstitial fibrosis, and inflammation in relation to improvement in oxidative stress and apoptosis. Treatment with SAR131475 improved palmitate-induced increase in the expression of VEGF-C, VEGFR-3, and LYVE-1, along with improvement in cytosolic and mitochondrial oxidative stress in RAW264.7 and HK2 cells. Moreover, the enhanced expression of M1 phenotypes in RAW264.7 cells under palmitate stress was reduced by SAR131475 treatment. The results suggest that modulation of lymphatic proliferation in the kidneys is a new treatment approach for type 2 diabetic nephropathy and that SAR131675 is a promising therapy to ameliorate renal damage by reducing lipotoxicity-induced lymphangiogenesis.

Attenuated Lymphatic Proliferation Ameliorates Diabetic Nephropathy and High-Fat Diet-Induced Renal Lipotoxicity.

Lymphangiogenesis occurs in response to renal injury and is correlated with interstitial fibrosis. Diabetes- and high-fat diet (HFD)-induced intrarenal lipotoxicity and their relationships with lymphangiogenesis are not established. We used PPARα agonist, fenofibrate, to unravel the linkage between lipotoxicity and lymphangiogenesis. Eight-week-old male C57BLKS/J db/db mice and HFD Spontaneously hypertensive rats (SHRs) were fed fenofibrate for 12 weeks. HK-2 and RAW264.7 cells were used to investigate their lymphangiogenic capacity in relation to lipotoxicity. Fenofibrate improved intrarenal lipotoxicity by increasing expression of PPARα and phosphorylation of AMPK. Lymphatic proliferation was attenuated; expression of lymphatic endothelial hyaluronan receptor-1 (LYVE-1), podoplanin, vascular endothelial growth factor-C (VEGF-C), and vascular endothelial growth factor receptor-3 (VEGFR-3) was decreased. In parallel, extent of tubulointerstitial fibrosis, apoptosis and inflammatory cell infiltration was reduced. In HK2 cells, palmitate- and high glucose-induced over expression of lymphatic makers was diminished by fenofibrate via activation of PPARα-AMPK-pACC signaling. Enhanced expression of M1 phenotype in RAW264.7 cells correlated with increased lymphatic growth. A causal relationship between lipotoxicity and lymphatic proliferation with a cellular link to macrophage activation can be speculated; pro-inflammatory M1 type macrophage is involved in the development of lymphangiogenesis through stimulation of VEGF-C and by its transdifferentiation into lymphatic endothelial cells.

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.

Outcome of endovascular salvage of immature hemodialysis arteriovenous fistulas.

PURPOSE: To assess the causes of immature hemodialysis arteriovenous fistula and the outcome of endovascular salvage. METHODS: The outcome of 207 endovascular salvage procedures in 139 patients after the first successful cannulation was analyzed retrospectively from January 2011 to December 2017 in the Catholic University of Korea, Seoul St. Mary's Hospital. RESULTS: Of the 139 patients aged 62 ± 13 years, 45% were women, 59% had diabetes, and 71% were maintained on hemodialysis using central venous catheters. Mean interval between arteriovenous fistula creation and referral to angiography was 87 ± 63 days. While inflow stenosis (54.4%) was the most common cause of immature forearm fistulas (n = 76), both inflow (38.6%) and mixed stenosis (35.1%) were the main causes of immature upper arm fistulas (n = 63). Endovascular salvage procedures included percutaneous transluminal angioplasty (n = 174) and accessory vein obliteration (n = 30). The overall technical and clinical success rates were 97% and 93.4%, respectively. Mean interval between endovascular procedure and the first successful cannulation of the fistula was 28 ± 35 days. At 3, 6, and 12 months following the first successful cannulation, the primary patency rates were 81%, 69.5%, and 57.6%, respectively, and the secondary patency rates were 97.2%, 96%, and 94.8%, respectively. Mixed stenosis was the only determinant of secondary patency rate of immature arteriovenous fistula (hazard ratio = 6.334, confidence interval = 1.364-29.423, p = 0.018), and patients with mixed stenosis had poorer access outcomes (p = 0.016). CONCLUSION: Immature arteriovenous fistulas can be successfully salvaged by aggressive and timely endovascular intervention. Mixed stenosis is associated with poor access outcomes.

Effects of Resveratrol on the Renin-Angiotensin System in the Aging Kidney.

The renin-angiotensin system (RAS), especially the angiotensin II (Ang II)/angiotensin II type 1 receptor (AT1R) axis, plays an important role in the aging process of the kidney, through increased tissue reactive oxygen species production and progressively increased oxidative stress. In contrast, the angiotensin 1-7 (Ang 1-7)/Mas receptor (MasR) axis, which counteracts the effects of Ang II, is protective for end-organ damage. To evaluate the ability of resveratrol (RSV) to modulate the RAS in aging kidneys, eighteen-month-old male C57BL/6 mice were divided into two groups that received either normal mouse chow or chow containing resveratrol, for six months. Renal expressions of RAS components, as well as pro- and antioxidant enzymes, were measured and mouse kidneys were isolated for histopathology. Resveratrol-treated mice demonstrated better renal function and reduced albuminuria, with improved renal histologic findings. Resveratrol suppressed the Ang II/AT1R axis and enhanced the AT2R/Ang 1-7/MasR axis. Additionally, the expression of nicotinamide adenine dinucleotide phosphate oxidase 4, 8-hydroxy-2'-deoxyguanosine, 3-nitrotyrosine, collagen IV, and fibronectin was decreased, while the expression of endothelial nitric oxide synthase and superoxide dismutase 2 was increased by resveratrol treatment. These findings demonstrate that resveratrol exerts protective effects on aging kidneys by reducing oxidative stress, inflammation, and fibrosis, through Ang II suppression and MasR activation.

Cinacalcet-mediated activation of the CaMKKß-LKB1-AMPK pathway attenuates diabetic nephropathy in db/db mice by modulation of apoptosis and autophagy.

Apoptosis and autophagy are harmoniously regulated biological processes for maintaining tissue homeostasis. AMP-activated protein kinase (AMPK) functions as a metabolic sensor to coordinate cellular survival and function in various organs, including the kidney. We investigated the renoprotective effects of cinacalcet in high-glucose treated human glomerular endothelial cells (HGECs), murine podocytes and C57BLKS/J-db/db mice. In cultured HGECs and podocytes, cinacalcet decreased oxidative stress and apoptosis and increased autophagy that were attributed to the increment of intracellular Ca2+ concentration and the phosphorylation of Ca2+/calmodulin-dependent protein kinase kinaseß (CaMKKß)-Liver kinase B1 (LKB1)-AMPK and their downstream signals including the phosphorylation of endothelial nitric oxide synthase (eNOS) and increases in superoxide dismutases and B cell leukemia/lymphoma 2/BCL-2-associated X protein expression. Interestingly, intracellular chelator BAPTA-AM reversed cinacalcet-induced CaMKKß elevation and LKB1 phosphorylation. Cinacalcet reduced albuminuria without influencing either blood glucose or Ca2+ concentration and ameliorated diabetes-induced renal damage, which were related to the increased expression of calcium-sensing receptor and the phosphorylation of CaMKKß-LKB1. Subsequent activation of AMPK was followed by the activation of peroxisome proliferator-activated receptor γ coactivator-1α and phospho-Ser1177eNOS-nitric oxide, resulting in a decrease in apoptosis and oxidative stress as well as an increase in autophagy.Our results suggest that cinacalcet increases intracellular Ca2+ followed by an activation of CaMKKß-LKB1-AMPK signaling in GECs and podocytes in the kidney, which provides a novel therapeutic means for type 2 diabetic nephropathy by modulation of apoptosis and autophagy.

Clinical significance of the presence of anti-human leukocyte antigen-donor specific antibody in kidney transplant recipients with allograft dysfunction.

BACKGROUND/AIMS: This study investigated the clinical significance of detecting anti-human leukocyte antigen-donor specific antibody (HLA-DSA) in kidney transplant recipients (KTRs) requiring indication biopsy owing to allograft dysfunction. METHODS: We analyzed the presence of HLA-DSA in 210 KTRs who took indication biopsy. We divided these cases into two groups, HLA-DSA (+) (n = 52) and HLA-DSA (-) (n = 158) group, and compared the clinical characteristics, pathological findings, and clinical outcomes of the two groups. RESULTS: The rates of retransplant, pretransplant sensitization, and HLA-mismatch were significantly higher in HLA-DSA (+) group than in HLA-DSA (-) group (p < 0.05 for each comparison). In histologic finding, all types of rejections were more frequent in the former group. Besides, scores of both the T-cell injury markers such as tubulitis, interstitial inf lammation, and vasculitis and antibody-mediated injury markers such as peritubular C4d deposition and microvascular inflammation (glomerulitis plus peritubular capillaritis) were higher in HLA-DSA (+) group (p < 0.05 for each). Notably, allograft outcomes were worse in HLA-DSA (+) group. Further, multivariate analysis showed that presence of HLA-DSA, advanced interstitial fibrosis/tubular atrophy (interstitial fibrosis plus tubular atrophy ≥ 2), and allograft rejection in biopsy were independent risk factors for allograft failure. CONCLUSIONS: The results of this study showed that presence of HLA-DSA in a case of allograft dysfunction adversely influences allograft outcome, and its detection, irrespective of the result of the allograft biopsy, necessitates intensive monitoring and treatment.

Extracellular Superoxide Dismutase Attenuates Renal Oxidative Stress Through the Activation of Adenosine Monophosphate-Activated Protein Kinase in Diabetic Nephropathy.

AIMS: Oxidative stress plays a crucial role in the pathogenesis of diabetic nephropathy (DN). We evaluated whether extracellular superoxide dismutase (EC-SOD) has a renoprotective effect through activation of adenosine monophosphate-activated protein kinase (AMPK) in diabetic kidneys. RESULTS: Human recombinant EC-SOD (hEC-SOD) was administered to 8-week-old male C57BLKS/J db/db mice through intraperitoneal injection once a week for 8 weeks. Renal SOD3 expression was suppressed in db/db mice, which was significantly enhanced by hEC-SOD treatment. hEC-SOD improved albuminuria, mesangial expansion, and interstitial fibrosis in db/db mice. At the molecular level, hEC-SOD increased phosphorylation of AMPK, activation of peroxisome proliferative-activated receptor γ coactivator 1α (PGC-1α), and dephosphorylation of forkhead box O transcription factor (FoxO)1 and FoxO3a. The protective effects of hEC-SOD were attributed to enhanced nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) and subsequently increased expression of NAD(P)H dehydrogenase 1 and heme oxygenase-1. Consequently, hEC-SOD recovered from systemic and renal inflammation and apoptosis, as reflected by the decreases of serum and renal monocyte chemoattractant protein-1 and tumor necrosis factor-α levels and increases of BCL-2/BAX ratio in diabetic kidney. hEC-SOD also improved oxidative stress and resulted in increased renal and urinary 8-hydroxy-2'-deoxyguanosine and 8-isoprostane levels in db/db mice. In cultured human glomerular endothelial cells, hEC-SOD ameliorated apoptosis and oxidative stress caused by high glucose exposure through activation of AMPK and PGC-1α and dephosphorylation of FoxOs. INNOVATION: These findings demonstrated for the first time that EC-SOD can potentially ameliorate hyperglycemia-induced oxidative stress, apoptosis, and inflammation through activation of AMPK and its downstream pathways in diabetic kidneys. CONCLUSIONS: EC-SOD is a potential therapeutic target for treatment of type 2 DN through intrarenal AMPK-PGC-1α-Nrf2 and AMPK-FoxOs signaling. Antioxid. Redox Signal. 28, 1543-1561.

Clinical effects of pre-transplant serum 25-hydroxyvitamin D level on post-transplant immunologic and non-immunologic outcomes in kidney transplant recipients.

BACKGROUND: The aim of this study was to investigate the effects of pre-transplant serum 25-hydroxyvitamin D (25(OH)D) level on non-immunologic and immunologic aspects of post-transplant clinical outcomes in kidney transplant recipients (KTRs). METHODS: We investigated 174 KTRs with low immunologic risk at baseline. We divided the patients into three groups according to baseline serum 25(OH)D level and compared the post-transplant clinical outcomes of acute rejection, infectious complications, and osteoporosis among the groups. RESULT: Thirty cases of biopsy-proven acute rejection (BPAR) were detected during the first year after KT. In the highest tertile, the rate of acute rejection (8.6%) was significantly lower than that in the lowest tertile (25.4%) (p=0.016), and a high 25(OH)D level was independently associated with a low incidence of BPAR in multivariate analysis. In contrast, serum 25(OH)D level did not show a significant association with overall or any specific type of infectious complication. Lipid profile, intact parathyroid hormone (PTH) level, and hemoglobin level were similar among the three tertile groups. The incidence of osteoporosis and bone mineral density (BMD) score were also similar across all three groups. CONCLUSIONS: Pre-transplant serum 25(OH)D level is a significant predictor of acute rejection, but it does not predict infection or metabolic complications.

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.

Resveratrol increases AdipoR1 and AdipoR2 expression in type 2 diabetic nephropathy.

BACKGROUND: Adiponectin has multiple functions including insulin sensitization, anti-inflammation and antiatherogenesis in various organs. Adiponectin activates 5'-adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor (PPAR)α via the adiponectin receptor (AdipoR) 1 and 2, which are critical for regulating lipids and glucose homeostasis and for controlling oxidative stress. We investigated whether resveratrol can inhibit renal damage in type 2 diabetic db/db mice and the underlying mechanisms of its effects. METHODS: Four groups of male C57 BLKS/J db/m and db/db mice and human glomerular endothelial cells (HGECs) were used. Resveratrol was administered to diabetic and nondiabetic mice by oral gavage for 12 weeks starting at 8 weeks of age. RESULTS: In db/db mice, resveratrol increased serum adiponectin levels and decreased albuminuria, glomerular matrix expansion, inflammation and apoptosis in the glomerulus. Resveratrol increased the phosphorylation of AMPK and silent information regulator T1 (SIRT1), and decreased phosphorylation of downstream effectors class O forkhead box (FoxO)1 and FoxO3a via increasing AdipoR1 and AdipoR2 in the renal cortex. Furthermore, resveratrol increased expression of PPARγ coactivator (PGC)-1α, estrogen-related receptor-1α, and phosphorylated acetyl-CoA carboxylase and decreased sterol regulatory element-binding protein 1. This effect lowered the content of nonesterified fatty acid and triacylglycerol in the kidneys, decreasing apoptosis, oxidative stress and activating endothelial nitric oxide synthase. Resveratrol prevented cultured HGECs from undergoing high-glucose-induced oxidative stress and apoptosis by activating the AMPK-SIRT1-PGC-1α axis and PPARα through increases in AdipoR1 and AdipoR2 expression. CONCLUSIONS: These results suggest that resveratrol prevents diabetic nephropathy by ameliorating lipotoxicity, oxidative stress, apoptosis and endothelial dysfunction via increasing AdipoR1 and AdipoR2 expression.

PPARα agonist, fenofibrate, ameliorates age-related renal injury.

The kidney ages quickly compared with other organs. Expression of senescence markers reflects changes in the energy metabolism in the kidney. Two important issues in aging are mitochondrial dysfunction and oxidative stress. Peroxisome proliferator-activated receptor α (PPARα) is a member of the ligand-activated nuclear receptor superfamily. PPARα plays a major role as a transcription factor that regulates the expression of genes involved in various processes. In this study, 18-month-old male C57BL/6 mice were divided into two groups, the control group (n=7) and the fenofibrate-treated group (n=7) was fed the normal chow plus fenofibrate for 6months. The PPARα agonist, fenofibrate, improved renal function, proteinuria, histological change (glomerulosclerosis and tubular interstitial fibrosis), inflammation, and apoptosis in aging mice. This protective effect against age-related renal injury occurred through the activation of AMPK and SIRT1 signaling. The activation of AMPK and SIRT1 allowed for the concurrent deacetylation and phosphorylation of their target molecules and decreased the kidney's susceptibility to age-related changes. Activation of the AMPK-FOXO3a and AMPK-PGC-1α signaling pathways ameliorated oxidative stress and mitochondrial dysfunction. Our results suggest that activation of PPARα and AMPK-SIRT1 signaling may have protective effects against age-related renal injury. Pharmacological targeting of PPARα and AMPK-SIRT1 signaling molecules may prevent or attenuate age-related pathological changes in the kidney.