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Bisson SK, Ung RV, Mac-Way F. Role of the Wnt/ β-Catenin Pathway in Renal Osteodystrophy. Int J Endocrinol 2018; 2018:5893514. [PMID: 29808090 PMCID: PMC5901476 DOI: 10.1155/2018/5893514] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Accepted: 03/08/2018] [Indexed: 12/17/2022] Open
Abstract
Vascular calcification and bone fragility are common and interrelated health problems that affect chronic kidney disease (CKD) patients. Bone fragility, which leads to higher risk of fracture and mortality, arises from the abnormal bone remodeling and mineralization that are seen in chronic kidney disease. Recently, sclerostin and Dickkopf-related protein 1 were suggested to play a significant role in CKD-related bone disease as they are known inhibitors of the Wnt pathway, thus preventing bone formation. This review focuses on new knowledge about the Wnt pathway in bone, how its function is affected by chronic kidney disease and how this affects bone structure. Expression of components and inhibitors of the Wnt pathway has been shown to be affected by the loss of kidney function, and a better understanding of the bone effects of Wnt pathway inhibitors could allow the development of new therapies to prevent bone fragility in this population.
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Affiliation(s)
- Sarah-Kim Bisson
- Faculty and Department of Medicine, CHU de Québec Research Center, L'Hôtel-Dieu de Québec Hospital, Endocrinology and Nephrology Axis, Université Laval, Quebec, Canada
| | - Roth-Visal Ung
- Faculty and Department of Medicine, CHU de Québec Research Center, L'Hôtel-Dieu de Québec Hospital, Endocrinology and Nephrology Axis, Université Laval, Quebec, Canada
| | - Fabrice Mac-Way
- Faculty and Department of Medicine, CHU de Québec Research Center, L'Hôtel-Dieu de Québec Hospital, Endocrinology and Nephrology Axis, Université Laval, Quebec, Canada
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52
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Baldan A, Giusti A, Bosi C, Malaventura C, Forni G, Borgna-Pignatti C. Pseudoxanthoma Elasticum-Like in β-Thalassemia Major, a matter of α-Klotho and Parathyroid Hormone? Hemoglobin 2017; 41:254-259. [DOI: 10.1080/03630269.2017.1403927] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Alessandro Baldan
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
| | - Andrea Giusti
- Bone Clinic, Department of Geriatric Care, Orthogeriatrics and Rehabilitation, Galliera Hospital, Genoa, Italy
| | - Cristina Bosi
- Department of Medical Sciences, Section of Internal and Cardio-Respiratory Medicine, University of Ferrara, Ferrara, Italy
| | - Cristina Malaventura
- Department of Medical Sciences, Section of Pediatrics, University of Ferrara, Ferrara, Italy
| | - Gianluca Forni
- Center of Microcitemia and Congenital Anemias, Galliera Hospital, Genoa, Italy
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Suppression of Wnt Signaling and Osteogenic Changes in Vascular Smooth Muscle Cells by Eicosapentaenoic Acid. Nutrients 2017; 9:nu9080858. [PMID: 28796175 PMCID: PMC5579651 DOI: 10.3390/nu9080858] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 08/04/2017] [Accepted: 08/07/2017] [Indexed: 01/01/2023] Open
Abstract
Vascular medial calcification is often observed in patients with arteriosclerosis. It is also associated with systolic hypertension, wide pulse pressure, and fluctuation of blood pressure, which results in cardiovascular events. Eicosapentaenoic acid (EPA) has been shown to suppress vascular calcification in previous animal experiments. We investigated the inhibitory effects of EPA on Wnt signaling, which is one of the important signaling pathways involved in vascular calcification. Intake of food containing 5% EPA resulted in upregulation of the mRNA expression of Klotho, an intrinsic inhibitor of Wnt signaling, in the kidneys of wild-type mice. Expression levels of β-catenin, an intracellular signal transducer in the Wnt signaling pathway, were increased in the aortas of Klotho mutant (kl/kl) mice compared to the levels in the aortas of wild-type mice. Wnt3a or BIO, a GSK-3 inhibitor that activates β-catenin signaling, upregulated mRNA levels of AXIN2 and LEF1, Wnt signaling marker genes, and RUNX2 and BMP4, early osteogenic genes, in human aorta smooth muscle cells. EPA suppressed the upregulation of AXIN2 and BMP4. The effect of EPA was cancelled by T0070907, a PPARγ inhibitor. The results suggested that EPA could suppress vascular calcification via the inhibition of Wnt signaling in osteogenic vascular smooth muscle cells via PPARγ activation.
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54
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Milovanova SY, Milovanov YS, Taranova MV, Dobrosmyslov IA. [Effects of keto/amino acids and a low-protein diet on the nutritional status of patients with Stages 3B-4 chronic kidney disease]. TERAPEVT ARKH 2017; 89:30-33. [PMID: 28745686 DOI: 10.17116/terarkh201789630-33] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
AIM To evaluate the efficacy of keto/amino acids in maintaining protein balance and preventing mineral metabolic disturbances and the development of uremic hyperparathyroidism in the long-term use of a low-protein diet (LPD) in patients with Stages 3B-4 chronic kidney disease (CKD). SUBJECTS AND METHODS Ninety patients with CKD caused by chronic latent glomerulonephritis in 65 patients and chronic tubulointerstitial nephritis of various etiologies (gout, drug-induced, and infection) in 25 were examined. The investigators conducted clinical, laboratory, and instrumental examinations, including bioelectrical impedance analysis (body mass index (BMI), the percentages of lean and fat mass), echocardiography and radiography of the abdominal aorta in the lateral projection (the presence of cardiac valvular and aortic calcification), and pulse wave velocity measurements using a Sphygmocor apparatus (vessel stiffness estimation). The stages of CKD were defined according to the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) criteria; glomerular filtration rate was calculated using the CKD EPI equation. According to the diet used, all the patients were divided into 3 groups: 1) 30 patients who took LPD (0.6 g of protein per kg of body weight/day) in combination with the keto/amino acid ketosteril (1 tablet per 5 kg of body weight/day; Diet One); 2) 30 patients who used LPD in combination with the other keto/amino acid ketoaminol at the same dose (Diet Two); 3) 30 patients had LPD without using the keto/amino acids (Diet Three) (a control group). RESULTS During a follow-up, there were no signs of malnutrition in Groups 1 and 2 patients receiving LPD (0.6 g protein per kg/day) in combination with the keto/amino acids ketosteril and ketaminol, respectively. At the same time, 11 (36.6%) patients in Group 3 (a control group) who did not take the keto/amino acids showed a BMI decrease from 24 (23; 26) kg/m2 to 18.5 (17; 19.2) kg/m2 (p < 0.05), including that of lean body mass from 37.4 (36; 38.8) to 30 (29.1; 34.7)% in the men (p<0.05) and from 29.8 (26.8; 31) to 23.9 (22; 25.7)% in the women (p<0.01). In addition, at the end of the study, there were elevated serum phosphorus levels (p<0.05) and mainly higher parathyroid hormone concentrations in Group 3 patients who received LPD without using the amino/keto acids than in Groups 1 and 2. As compared to Group 3, Groups 1 and 2 displayed no differences in the quantity of cardiac and aortic calcification and in the augmentation index (arterial stiffness). The ketosteril and ketaminol groups versus the control group had also higher s-Klotho levels (p<0.01) that were inversely correlated with glomerular filtration rate (r =-0.467; p<0.01). CONCLUSION The keto/amino acids ketosteril or ketoaminol are an important component of LPD, which prevents malnutrition and an additional source of calcium that inhibits hyperphosphatemia and slows the development of uremic hyperparathyroidism. Incorporation of keto/amino acids into LPD leads to a less pronounced reduction in s-Klotho protein in relation to the degree of renal failure than does LPD without keto/amino acids.
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Affiliation(s)
- S Yu Milovanova
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
| | - Yu S Milovanov
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
| | - M V Taranova
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
| | - I A Dobrosmyslov
- I.M. Sechenov First Moscow State Medical University, Ministry of Health of Russia, Moscow, Russia
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Klotho levels: association with insulin resistance and albumin-to-creatinine ratio in type 2 diabetic patients. Int Urol Nephrol 2017; 49:1809-1814. [PMID: 28677090 DOI: 10.1007/s11255-017-1646-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 06/26/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE The present study aimed at evaluating the relationship between Klotho levels and insulin resistance and albumin-to-creatinine ratio (ACR) in type 2 diabetic patients with CKD. METHODS We conducted an observational, cross-sectional study in our outpatient diabetic nephropathy clinic from 2014 to 2016, enrolling a total of 107 type 2 diabetic patients with stage 2-3 CKD, with a mean age of 59 years. Several clinical and laboratorial parameters were evaluated, including those related to mineral and carbohydrate metabolism. RESULTS The mean eGFR at baseline was 53.2 mL/min, and the mean levels of ACR and Klotho were 181.9 µg/mg and 331.1 pg/m, respectively. In the simple linear regression model, Klotho levels were correlated with age, phosphorus, PTH, ACR, HOMA, IL-6, FGF-23, OxLDL, eGFR and vitamin D levels. Applying a multivariate linear regression model, only the ACR, HOMA-IR, FGF-23 and vitamin D independently influenced the Klotho levels. In the generalized linear model, only the Klotho groups were statistically significant as independent variable (p = 0.007). The results show that the group 1 (<268) compared with group 3 (>440) had higher odds in the higher ACR (≥181), ORa = 3.429, p = 0.014. There were no statistically significant differences between Klotho groups 2 and 3, and the HOMA-IR obtained showed that group 1 (<268) had greater odds of HOMA-IR ≥2 when compared with group 3 (>440), ORa = 21.59, p = 0.017. CONCLUSIONS Our results showed that Klotho levels are influenced by FGF23, vitamin D and insulin resistance. This suggests that Klotho levels might be affected by renal function as well as having a relevant role on insulin metabolism and ACR homeostasis.
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56
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Neyra JA, Hu MC. Potential application of klotho in human chronic kidney disease. Bone 2017; 100:41-49. [PMID: 28115282 PMCID: PMC5474175 DOI: 10.1016/j.bone.2017.01.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 01/18/2017] [Accepted: 01/18/2017] [Indexed: 01/13/2023]
Abstract
The extracellular domain of transmembrane alpha-Klotho (αKlotho, hereinafter simply called Klotho) is cleaved by secretases and released into the circulation as soluble Klotho. Soluble Klotho in the circulation starts to decline early in chronic kidney disease (CKD) stage 2 and urinary Klotho possibly even earlier in CKD stage 1. Therefore soluble Klotho could serve as an early and sensitive marker of kidney function decline. Moreover, preclinical animal data support Klotho deficiency is not just merely a biomarker, but a pathogenic factor for CKD progression and extrarenal CKD complications including cardiovascular disease and disturbed mineral metabolism. Prevention of Klotho decline, re-activation of endogenous Klotho production or supplementation of exogenous Klotho are all associated with attenuation of renal fibrosis, retardation of CKD progression, improvement of mineral metabolism, amelioration of cardiomyopathy, and alleviation of vascular calcification in CKD. Therefore Klotho is not only a diagnostic and/or prognostic marker for CKD, but the treatment of Klotho deficiency may be a promising strategy to prevent, retard, and decrease the burden of comorbidity in CKD.
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Affiliation(s)
- Javier A Neyra
- Department of Internal Medicine, University of Texas Southwestern Medical Center, USA; Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, USA
| | - Ming Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, USA; Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, USA.
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57
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Hsia CCW, Ravikumar P, Ye J. Acute lung injury complicating acute kidney injury: A model of endogenous αKlotho deficiency and distant organ dysfunction. Bone 2017; 100:100-109. [PMID: 28347910 PMCID: PMC5621379 DOI: 10.1016/j.bone.2017.03.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 03/23/2017] [Accepted: 03/23/2017] [Indexed: 12/11/2022]
Abstract
The lung interfaces with atmospheric oxygen via a large surface area and is perfused by the entire venous return bearing waste products collected from the whole body. It is logical that the lung is endowed with generous anti-oxidative capacity derived both locally and from the circulation. The single-pass pleiotropic alpha-Klotho (αKlotho) protein was discovered when its genetic disruption led to premature multi-organ degeneration and early death. The extracellular domain of αKlotho is cleaved by secretases and released into circulation as endocrine soluble αKlotho protein, exerting wide-ranging cytoprotective effects including anti-oxidation on distant organs including the lung, which exhibits high sensitivity to circulating αKlotho insufficiency. Because circulating αKlotho is derived mainly from the kidney, acute kidney injury (AKI) leads to systemic αKlotho deficiency that in turn increases the risks of pulmonary complications, i.e., edema and inflammation, culminating in the acute respiratory distress syndrome. Exogenous αKlotho increases endogenous anti-oxidative capacity partly via activation of the Nrf2 pathway to protect lungs against injury caused by direct hyperoxia exposure or AKI. This article reviews the current knowledge of αKlotho antioxidation in the lung in the setting of AKI as a model of circulating αKlotho deficiency, an under-recognized condition that weakens innate cytoprotective defenses and contributes to the dysfunction in distant organs.
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Affiliation(s)
- Connie C W Hsia
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America.
| | - Priya Ravikumar
- Department of Internal Medicine, Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America
| | - Jianfeng Ye
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-9034, United States of America
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58
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Kim SJ, Cheresh P, Eren M, Jablonski RP, Yeldandi A, Ridge KM, Budinger GRS, Kim DH, Wolf M, Vaughan DE, Kamp DW. Klotho, an antiaging molecule, attenuates oxidant-induced alveolar epithelial cell mtDNA damage and apoptosis. Am J Physiol Lung Cell Mol Physiol 2017; 313:L16-L26. [PMID: 28428174 DOI: 10.1152/ajplung.00063.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/03/2017] [Accepted: 04/16/2017] [Indexed: 11/22/2022] Open
Abstract
Alveolar epithelial cell (AEC) apoptosis and inadequate repair resulting from "exaggerated" lung aging and mitochondrial dysfunction are critical determinants promoting lung fibrosis. α-Klotho, which is an antiaging molecule that is expressed predominantly in the kidney and secreted in the blood, can protect lung epithelial cells against hyperoxia-induced apoptosis. We reasoned that Klotho protects AEC exposed to oxidative stress in part by maintaining mitochondrial DNA (mtDNA) integrity and mitigating apoptosis. We find that Klotho levels are decreased in both serum and alveolar type II (AT2) cells from asbestos-exposed mice. We show that oxidative stress reduces AEC Klotho mRNA and protein expression, whereas Klotho overexpression is protective while Klotho silencing augments AEC mtDNA damage. Compared with wild-type, Klotho heterozygous hypomorphic allele (kl/+) mice have increased asbestos-induced lung fibrosis due in part to increased AT2 cell mtDNA damage. Notably, we demonstrate that serum Klotho levels are reduced in wild-type but not mitochondrial catalase overexpressing (MCAT) mice 3 wk following exposure to asbestos and that EUK-134, a MnSOD/catalase mimetic, mitigates oxidant-induced reductions in AEC Klotho expression. Using pharmacologic and genetic silencing studies, we show that Klotho attenuates oxidant-induced AEC mtDNA damage and apoptosis via mechanisms dependent on AKT activation arising from upstream fibroblast growth factor receptor 1 activation. Our findings suggest that Klotho preserves AEC mtDNA integrity in the setting of oxidative stress necessary for preventing apoptosis and asbestos-induced lung fibrosis. We reason that strategies aimed at augmenting AEC Klotho levels may be an innovative approach for mitigating age-related lung diseases.
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Affiliation(s)
- Seok-Jo Kim
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Paul Cheresh
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Mesut Eren
- Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Renea P Jablonski
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Anjana Yeldandi
- Department of Pathology, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Karen M Ridge
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - G R Scott Budinger
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois.,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - Dong-Hyun Kim
- Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois; and
| | - Myles Wolf
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina
| | - Douglas E Vaughan
- Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
| | - David W Kamp
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois; .,Department of Medicine, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
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59
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Yin S, Zhang Q, Yang J, Lin W, Li Y, Chen F, Cao W. TGFβ-incurred epigenetic aberrations of miRNA and DNA methyltransferase suppress Klotho and potentiate renal fibrosis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:1207-1216. [PMID: 28285987 DOI: 10.1016/j.bbamcr.2017.03.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 03/03/2017] [Accepted: 03/06/2017] [Indexed: 12/31/2022]
Abstract
Renal fibrosis is a common pathological feature of chronic kidney diseases (CKD) and its development and progression are significantly affected by epigenetic modifications such as aberrant miRNA and DNA methylation. Klotho is an anti-aging and anti-fibrotic protein and its early decline after renal injury is reportedly associated with aberrant DNA methylation. However, the key upstream pathological mediators and the molecular cascade leading to epigenetic Klotho suppression are not exclusively established. Here we investigate the epigenetic mechanism of Klotho deficiency and its functional relevance in renal fibrogenesis. Fibrotic kidneys induced by unilateral ureteral occlusion (UUO) displayed marked Klotho suppression and the promoter hypermethylation. These abnormalities were likely due to deregulated transforming growth factor-beta (TGFβ) since TGFβ alone caused the similar epigenetic aberrations in cultured renal cells and TGFβ blockade prevented the alterations in UUO kidney. Further investigation revealed that TGFβ enhanced DNA methyltransferase (DNMT) 1 and DNMT3a via inhibiting miR-152 and miR-30a in both renal cells and fibrotic kidneys. Accordingly the blockade of either TGFβ signaling or DNMT1/3a activities significantly recovered the Klotho loss and attenuated pro-fibrotic protein expression and renal fibrosis. Moreover, Klotho knockdown by RNA interferences abolished the anti-fibrotic effects of DNMT inhibition in both TGFβ-treated renal cell and UUO kidney, indicating that TGFβ-mediated miR-152/30a inhibitions, DNMT1/3a aberrations and subsequent Klotho loss constitute a critical regulatory loop that eliminates Klotho's anti-fibrotic activities and potentiates renal fibrogenesis. Thus, our study elaborates a novel epigenetic cascade of renal fibrogenesis and reveals the potential therapeutic targets for treating the renal fibrosis-associated kidney diseases.
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Affiliation(s)
- Shasha Yin
- Nanjing University School of Medicine, Jiangsu, Key Laboratory of Molecular Medicine, Nanjing 210093, China
| | - Qin Zhang
- Nanjing University School of Medicine, Jiangsu, Key Laboratory of Molecular Medicine, Nanjing 210093, China
| | - Jun Yang
- Nanjing University School of Medicine, Jiangsu, Key Laboratory of Molecular Medicine, Nanjing 210093, China
| | - Wenjun Lin
- Nanjing University School of Medicine, Jiangsu, Key Laboratory of Molecular Medicine, Nanjing 210093, China
| | - Yanning Li
- Nanjing University School of Medicine, Jiangsu, Key Laboratory of Molecular Medicine, Nanjing 210093, China
| | - Fang Chen
- Nanjing University School of Medicine, Jiangsu, Key Laboratory of Molecular Medicine, Nanjing 210093, China
| | - Wangsen Cao
- Nanjing University School of Medicine, Jiangsu, Key Laboratory of Molecular Medicine, Nanjing 210093, China.
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60
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Tan SJ, Crosthwaite A, Langsford D, Obeysekere V, Ierino FL, Roberts MA, Hughes PD, Hewitson TD, Dwyer KM, Toussaint ND. Mineral adaptations following kidney transplantation. Transpl Int 2017; 30:463-473. [PMID: 28120476 DOI: 10.1111/tri.12925] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/28/2016] [Accepted: 01/18/2017] [Indexed: 12/30/2022]
Abstract
Klotho is predominantly expressed in the kidney and reported to have antioxidant and antifibrotic properties. Soluble Klotho (sKl), the circulating protein cleaved from membrane-bound Klotho, is reduced significantly with kidney disease and inversely associated with mortality. sKl has not been thoroughly evaluated prospectively after kidney transplantation. Incident kidney transplant recipients (KTRs) were prospectively evaluated pretransplantation, 1, 12 and 52 weeks post-transplantation. Basic biochemistry, sKl and intact FGF23 were measured. Within-subject comparisons were evaluated using repeat-measure anova or Friedman's analysis. Effects of immunosuppression and biochemical parameters on sKl and FGF-23 over time were analysed using mixed-effects modelling. Median serum creatinine (sCr) at 1 week was 116 (92-142) μmol/l, and at 52 weeks, all 29 KTRs had a functioning graft with median sCr of 111 (97-131) μmol/l. Compared with baseline, sKl was increased at 52 weeks following an initial decline at 1 week (P < 0.005 and P < 0.01, respectively), while FGF23 was considerably reduced at 52 weeks (P < 0.001). In a mixed-effects model, an increased sKl was not associated with reduction in immunosuppression or evaluated biochemical parameters. Modest increase in sKl is observed one-year postkidney transplantation with excellent early graft function suggesting factors beyond renal capacity may influence circulating sKl. FGF23 normalization was observed. Longer term evaluation in transplantation, specifically addressing the effects of immunosuppression, is required to understand the pathophysiology of the sKl/FGF23 axis and potential for modification.
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Affiliation(s)
- Sven-Jean Tan
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine, The University of Melbourne, Parkville, Vic., Australia
| | - Amy Crosthwaite
- Department of Medicine, The University of Melbourne, Parkville, Vic., Australia.,Department of Nephrology, Austin Hospital, Heidelberg, Vic., Australia
| | - David Langsford
- Department of Nephrology, Northern Hospital, Epping, Vic., Australia
| | - Varuni Obeysekere
- Department of Endocrinology, St Vincent's Hospital Melbourne, Fitzroy, Vic., Australia
| | - Frank L Ierino
- Department of Medicine, The University of Melbourne, Parkville, Vic., Australia.,Department of Nephrology, St Vincent's Hospital Melbourne, Fitzroy, Vic., Australia.,Victorian Kidney Transplantation Collaborative, Melbourne, Vic., Australia
| | - Matthew A Roberts
- Victorian Kidney Transplantation Collaborative, Melbourne, Vic., Australia.,Eastern Health Clinical School, Monash University, Box Hill, Vic., Australia
| | - Peter D Hughes
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine, The University of Melbourne, Parkville, Vic., Australia
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine, The University of Melbourne, Parkville, Vic., Australia
| | - Karen M Dwyer
- Department of Medicine, The University of Melbourne, Parkville, Vic., Australia.,Department of Nephrology, St Vincent's Hospital Melbourne, Fitzroy, Vic., Australia.,Victorian Kidney Transplantation Collaborative, Melbourne, Vic., Australia.,School of Medicine, Deakin University, Geelong, Vic., Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine, The University of Melbourne, Parkville, Vic., Australia
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61
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The effect of nephrectomy on Klotho, FGF-23 and bone metabolism. Int Urol Nephrol 2017; 49:681-688. [PMID: 28130714 PMCID: PMC5357491 DOI: 10.1007/s11255-017-1519-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 01/17/2017] [Indexed: 01/12/2023]
Abstract
Background Increased concentration of fibroblast growth factor 23 (FGF-23) and decreased levels of soluble Klotho (sKL) are linked to negative clinical outcomes among patients with chronic kidney disease and acute kidney injury. Therefore, it is reasonable to hypothesize that GFR reduction caused by nephrectomy might alter mineral metabolism and induces adverse consequences. Whether nephrectomy due to urological indications causes derangements in FGF-23 and sKL has not been studied. The aim of the study was to evaluate the effect of acute GFR decline due to unilateral nephrectomy on bone metabolism, FGF-23 and sKL levels. Methods This is a prospective, single-centre observational study of patients undergoing nephrectomy due to urological indications. Levels of C-terminal FGF-23 (c-FGF-23), sKL and bone turnover markers [β-crosslaps (CTX), bone-specific alkaline phosphatase (bALP) and tartrate-resistant acid phosphatase 5b (TRAP 5b)] were measured before and after surgery (5 ± 2 days). Results Twenty-nine patients were studied (14 females, age 63.0 ± 11.6, eGFR 87.3 ± 19.2 ml/min/1.73 m2). After surgery, eGFR significantly declined (p < 0.0001). Nephrectomy significantly decreased sKL level [709.8 (599.9–831.2) vs. 583.0 (411.7–752.6) pg/ml, p < 0.001] and did not change c-FGF-23 concentration [70.5 (49.8–103.3) vs. 77.1 (60.5–109.1) RU/ml, p = 0.9]. Simultaneously, alterations in bone turnover markers were observed. Serum concentration of CTX increased [0.49 (0.4–0.64) vs. 0.59 (0.46–0.85) ng/ml, p = 0.001], while bALP and TRAP 5b decreased [23.6 (18.8–31.4) vs. 17.9 (15.0–22.0) U/l, p < 0.0001 and 3.3 (3.0–3.7) vs. 2.8 (2.3–3.2) U/l, p < 0.001, respectively]. Conclusions Nephrectomy among patients with preserved renal function before surgery does not increase c-FGF-23 but reduces sKL. Moreover, nephrectomy results in derangements in bone turnover markers in short-term follow-up. These changes may participate in pathogenesis of bone disease after nephrectomy.
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Liu QF, Ye JM, Yu LX, Dong XH, Feng JH, Xiong Y, Gu XX, Li SS. Klotho mitigates cyclosporine A (CsA)-induced epithelial-mesenchymal transition (EMT) and renal fibrosis in rats. Int Urol Nephrol 2016; 49:345-352. [PMID: 27796696 DOI: 10.1007/s11255-016-1439-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 10/11/2016] [Indexed: 02/06/2023]
Abstract
PURPOSE Klotho deficiency is implicated in various kidney diseases, including renal fibrosis. The aim of this study was to investigate the effect of Klotho administration on epithelial-mesenchymal transition (EMT) and renal fibrosis induced by cyclosporine A (CsA) in rats. METHODS CsA-induced renal fibrosis was established by oral administration of CsA (30 mg/kg) to rats on a low-salt diet for 28 days. Klotho was administered to rats by intraperitoneal injection. Renal pathological changes were evaluated by hematoxylin and eosin and Masson's trichrome staining. The EMT response was assessed by measuring the level of TGF-β1, E-cadherin and α-SMA by immunohistochemistry and Western blot. RESULTS Administration of CsA for 28 days induced renal damage, decreased Klotho expression and activated the EMT response (demonstrated as increased TGF-β1 and α-SMA expression accompanied by decreased in E-cadherin expression). Treatment with Klotho significantly ameliorated pathological lesions of the kidney by modulating the expression of EMT-associated proteins in the kidney. CONCLUSIONS Klotho inhibits CsA-induced EMT and renal fibrosis in rats. Klotho may serve as a therapeutic agent to minimize CsA-induced renal fibrosis.
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Affiliation(s)
- Qi-Feng Liu
- Department of Nephrology, Kunshan First People's Hospital Affiliated to Jiangsu University, Kunshan, Jiangsu, China
| | - Jian-Ming Ye
- Department of Nephrology, Kunshan First People's Hospital Affiliated to Jiangsu University, Kunshan, Jiangsu, China
| | - Li-Xia Yu
- Department of Nephrology, Kunshan First People's Hospital Affiliated to Jiangsu University, Kunshan, Jiangsu, China
| | - Xiao-Hong Dong
- Department of Nephrology, Kunshan First People's Hospital Affiliated to Jiangsu University, Kunshan, Jiangsu, China
| | - Jian-Hua Feng
- Department of Nephrology, Kunshan First People's Hospital Affiliated to Jiangsu University, Kunshan, Jiangsu, China
| | - Yan Xiong
- Department of Nephrology, Kunshan First People's Hospital Affiliated to Jiangsu University, Kunshan, Jiangsu, China
| | - Xiao-Xia Gu
- Department of Nephrology, Kunshan First People's Hospital Affiliated to Jiangsu University, Kunshan, Jiangsu, China
| | - Sha-Sha Li
- Clinical Research Centre, Kunshan First People's Hospital Affiliated to Jiangsu University, 91 Qianjin West Road, Kunshan, Jiangsu, China.
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Liu X, Chen Y, McCoy CW, Zhao T, Quarles DL, Pi M, Bhattacharya SK, King G, Sun Y. Differential Regulatory Role of Soluble Klothos on Cardiac Fibrogenesis in Hypertension. Am J Hypertens 2016; 29:1140-7. [PMID: 27543985 DOI: 10.1093/ajh/hpw062] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 05/23/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Soluble Klotho functions as an endocrine factor that plays important roles in a variety of pathophysiological processes. Soluble Klotho contains 130 KDa and 65 KDa isoforms. However, their distinct individual functional heterogeneity remains uncertain. Herein, we investigated the regulatory role of two soluble Klothos on cardiac fibrogenic responses. METHODS AND RESULTS The effect of soluble Klothos on myofibroblast differentiation, proliferation, and collagen synthesis/degradation were examined in cultured mouse cardiac myofibroblasts. The role of 130 KDa Klotho on fibrosis in hypertensive heart disease were examined in wild type (WT) and Klotho transgenic (Tg/+) mice receiving chronic angiotensin (Ang)II infusion. Our in vitro studies revealed that addition of 130 KDa soluble Klotho isoform increased collagen synthesis in a dose dependent manner. Furthermore, 130 KDa Klotho significantly stimulated myofibroblast differentiation, proliferation, and ERK phosphorylation, which were abolished by fibroblast growth factor (FGF) receptor antagonist (SU5402). In contrast, 65 KDa soluble Klotho treatment significantly suppressed myofibroblast proliferation and collagen synthesis. In vivo study further demonstrated that chronic AngII infusion lead to cardiac fibrosis in both WT and Tg/+ mice. However, cardiac collagen, TGF-β1, TIMP-2, and α-smooth muscle actin (SMA) levels were markedly upregulated in Tg/+ mice compared to WT cohort. CONCLUSION Taken together, these findings implicate that 130 KDa soluble Klotho plays a stimulatory role in cardiac myofibroblast growth and activity through FGF pathway, whereas 65 KDa soluble Klotho exerts an anti-fibrotic effect in cardiac myofibroblasts. Thus, two distinct isoforms of soluble Klotho appear to play the counter-regulatory roles in cardiac fibrogenic responses.
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Affiliation(s)
- Xue Liu
- Department of Pharmacology, Harbin Medical University, Harbin, China
| | - Yuanjian Chen
- Division of Cardiovascular Diseases, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN
| | - Cody W McCoy
- Division of Cardiovascular Diseases, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN
| | - Tieqiang Zhao
- Division of Cardiovascular Diseases, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN
| | - Darryl L Quarles
- Division of Nephrology, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN
| | - Min Pi
- Division of Nephrology, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN
| | - Syamal K Bhattacharya
- Division of Cardiovascular Diseases, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN
| | - Gwendalyn King
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL
| | - Yao Sun
- Division of Cardiovascular Diseases, Department of Medicine, University of Tennessee Health Science Center, Memphis, TN;
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Kim SS, Song SH, Kim IJ, Lee EY, Lee SM, Chung CH, Kwak IS, Lee EK, Kim YK. Decreased plasma α-Klotho predict progression of nephropathy with type 2 diabetic patients. J Diabetes Complications 2016; 30:887-92. [PMID: 27037042 DOI: 10.1016/j.jdiacomp.2016.03.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 03/04/2016] [Accepted: 03/09/2016] [Indexed: 01/07/2023]
Abstract
AIM The potential role of soluble α-klotho in diabetic kidney disease has not yet been evaluated. The aim of this study was to evaluate the association of plasma and/or urine α-klotho with the progression of type 2 diabetic nephropathy. METHODS The baseline values of plasma and urine α-klotho were measured in 147 patients with type 2 diabetes mellitus with an estimated glomerular filtration rate (eGFR) of ≥60mL/min/1.73m(2). In this prospective observational study, a total of 109 type 2 diabetic patients were followed up for 34months (8-50 months). RESULTS Plasma α-klotho, but not urine α-klotho, was negatively correlated with the decline of eGFR (r=-0.304, P=0.001; r=0.042, P=0.068, respectively). After adjusting for several clinical parameters, baseline eGFR and urine ACR, plasma α-klotho was significantly associated with the decline of eGFR (r=-0.219, P=0.008). In the normoalbuminuria group (n=63), the plasma α-klotho remained significantly associated with a decline in eGFR (r=0.324, P=0.004) in the final model. CONCLUSIONS It is suggested that plasma α-klotho may be an early biomarker for predicting renal impairment in type 2 diabetic patients. The disappearance of a compensatory increase of plasma α-klotho might be a predictive marker for the progression of type 2 diabetic nephropathy.
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Affiliation(s)
- Sang Soo Kim
- Department of Internal Medicine, Pusan National University Hospital, Busan, Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Korea
| | - Sang Heon Song
- Department of Internal Medicine, Pusan National University Hospital, Busan, Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Korea
| | - In Joo Kim
- Department of Internal Medicine, Pusan National University Hospital, Busan, Korea; Biomedical Research Institute, Pusan National University Hospital, Busan, Korea.
| | - Eun Young Lee
- Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Korea.
| | - Su Mi Lee
- Department of Internal Medicine, Dong-A University Hospital, Busan, Korea
| | - Choon Hee Chung
- Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Ihm Soo Kwak
- Department of Internal Medicine, Pusan National University Hospital, Busan, Korea
| | | | - Yong Ki Kim
- Kim Yong Ki Internal Medicine Clinic, Busan, Korea
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Impact of Renal Transplantation and Nephrectomy on Urinary Soluble Klotho Protein. Transplant Proc 2016; 47:1697-9. [PMID: 26293036 DOI: 10.1016/j.transproceed.2015.06.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Revised: 06/06/2015] [Accepted: 06/16/2015] [Indexed: 12/29/2022]
Abstract
BACKGROUND Klotho is a single-pass transmembrane protein predominantly expressed in the kidneys. The soluble form of klotho has been shown to participate in various pathophysiological activities. However, information regarding the kinetics of soluble klotho remains limited. We herein assessed serial changes in the amounts of 24-hour urinary excreted soluble klotho among renal transplant recipients and concomitant living donors before and after transplantation. METHODS A total of 15 recipients and donors were included in the current study, and the amounts of urinary soluble klotho were quantified using a sandwich enzyme-linked immunosorbent assay. RESULTS Urine samples were available in 6 of the 15 recipients prior to the procedure. The amounts of urinary klotho in these 6 recipients and overall living donors at the baseline were 58.6 ng/day (IR: 29.3-142) and 698.8 ng/day (IR: 62.3-1619.5), respectively. Those in the recipients on postoperative day 2 (median 522.3 ng/day; IR 337.1-1168.5, P < .05) and day 5 (median 723.2 ng/day; IR 254.7-1238.6, P < .05) were significantly higher than the baseline values. Among the living donors, only a transient increase was observed in the amounts of urinary klotho on postoperative day 2. CONCLUSION The current data regarding the urinary soluble klotho in recipients support the hypothesis that the kidney is a major source of urinary soluble klotho among the numerous components of the urinary tract. In living donors, the complex nature of events associated with acute reductions in the renal mass may modulate the release of soluble klotho from the kidneys into the urine.
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Abstract
Alpha-Klotho (αKlotho) protein is encoded by the gene, Klotho, and functions as a coreceptor for endocrine fibroblast growth factor-23. The extracellular domain of αKlotho is cleaved by secretases and released into the circulation where it is called soluble αKlotho. Soluble αKlotho in the circulation starts to decline in chronic kidney disease (CKD) stage 2 and urinary αKlotho in even earlier CKD stage 1. Therefore soluble αKlotho is an early and sensitive marker of decline in kidney function. Preclinical data from numerous animal experiments support αKlotho deficiency as a pathogenic factor for CKD progression and extrarenal CKD complications including cardiac and vascular disease, hyperparathyroidism, and disturbed mineral metabolism. αKlotho deficiency induces cell senescence and renders cells susceptible to apoptosis induced by a variety of cellular insults including oxidative stress. αKlotho deficiency also leads to defective autophagy and angiogenesis and promotes fibrosis in the kidney and heart. Most importantly, prevention of αKlotho decline, upregulation of endogenous αKlotho production, or direct supplementation of soluble αKlotho are all associated with attenuation of renal fibrosis, retardation of CKD progression, improvement of mineral metabolism, amelioration of cardiac function and morphometry, and alleviation of vascular calcification in CKD. Therefore in rodents, αKlotho is not only a diagnostic and prognostic marker for CKD but the enhancement of endogenous or supplement of exogenous αKlotho are promising therapeutic strategies to prevent, retard, and decrease the comorbidity burden of CKD.
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Affiliation(s)
- J A Neyra
- University of Texas Southwestern Medical Center, Dallas, TX, United States; Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - M C Hu
- University of Texas Southwestern Medical Center, Dallas, TX, United States; Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, United States.
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Zeng Y, Wang PH, Zhang M, Du JR. Aging-related renal injury and inflammation are associated with downregulation of Klotho and induction of RIG-I/NF-κB signaling pathway in senescence-accelerated mice. Aging Clin Exp Res 2016; 28:69-76. [PMID: 25986237 DOI: 10.1007/s40520-015-0371-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 05/05/2015] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND AIMS The predominant distribution of the antiaging Klotho protein in both the kidneys and brain may point to its essential role in protecting against dysfunction of the kidney-brain axis during the aging process. Our previous study showed that the downregulation of Klotho was involved in aging-related cognitive impairment in aged senescence-accelerated mouse prone-8 (SAMP8) mice. The present study investigated the potential role of Klotho in aging-associated inflammation and renal injury. METHODS Age- and gender-matched groups of SAMP8 mice and their corresponding normal control senescence-accelerated mouse resistant-1 (SAMR1) were used to investigate the potential role of Klotho in aging-associated inflammation and renal injury. RESULTS Compared with aged SAMR1 controls, early-stage chronic kidney disease (CKD), which is associated with an increase in the urinary albumin-to-creatinine ratio, inflammatory cell infiltration, glomerulosclerosis, and tubulointerstitial fibrosis, was observed in aged SAMP8 mice. Furthermore, the aging-related loss of Klotho-induced activation of the retinoic acid-inducible gene 1/nuclear factor-κB (RIG-I/NF-κB) signaling pathway and subsequent production of the proinflammatory mediators tumor necrosis factor α, interleukin-6, and inducible nitric oxide synthase in the kidneys of aged SAMP8 mice compared with SAMR1 controls. CONCLUSIONS The present results suggest that aging-related inflammation and the development of early-stage CKD are likely associated with the downregulation of Klotho and induction of the RIG-I/NF-κB signaling pathway in 12-month-old SAMP8 mice. Moreover, aged SAMP8 mice with cognitive deficits and renal damage may be a potential mouse model for investigating the kidney-brain axis in the aging process.
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Affiliation(s)
- Yi Zeng
- Department of Pharmacology, Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Ping-Han Wang
- Department of Pharmacology, Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Mao Zhang
- Department of Pharmacology, Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China
| | - Jun-Rong Du
- Department of Pharmacology, Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, Chengdu, 610041, China.
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Lin Y, Chen J, Sun Z. Antiaging Gene Klotho Deficiency Promoted High-Fat Diet-Induced Arterial Stiffening via Inactivation of AMP-Activated Protein Kinase. Hypertension 2016; 67:564-73. [PMID: 26781278 DOI: 10.1161/hypertensionaha.115.06825] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 12/24/2015] [Indexed: 12/21/2022]
Abstract
Klotho was originally discovered as an aging-suppressor gene. The objective of this study is to investigate whether klotho gene deficiency affects high-fat diet (HFD)-induced arterial stiffening. Heterozygous Klotho-deficient (KL(+/-)) mice and WT littermates were fed on HFD or normal diet. HFD increased pulse wave velocity within 5 weeks in KL(+/-) mice but not in wild-type mice, indicating that klotho deficiency accelerates and exacerbates HFD-induced arterial stiffening. A greater increase in blood pressure was found in KL(+/-) mice fed on HFD. Protein expressions of phosphorylated AMP-activated protein kinase-α (AMPKα), phosphorylated endothelial nitric oxide synthase (eNOS), and manganese-dependent superoxide dismutase (Mn-SOD) were decreased, whereas protein expressions of collagen I, transforming growth factor-β1, and Runx2 were increased in aortas of KL(+/-) mice fed on HFD. Interestingly, daily injections of an AMPKα activator, 5-aminoimidazole-4-carboxamide-3-ribonucleoside, abolished the increases in pulse wave velocity, blood pressure, and blood glucose in KL(+/-) mice fed on HFD. Treatment with 5-aminoimidazole-4-carboxamide-3-ribonucleoside for 2 weeks not only abolished the downregulation of phosphorylated AMPKα, phosphorylated eNOS, and Mn-SOD levels but also attenuated the increased levels of collagen I, transforming growth factor-β1, Runx2, superoxide, elastic lamellae breaks, and calcification in aortas of KL(+/-) mice fed on HFD. In cultured mouse aortic smooth muscle cells, cholesterol plus KL-deficient serum decreased phosphorylation levels of AMPKα and LKB1 (an important upstream regulator of AMPKα activity) but increased collagen I synthesis, which can be eliminated by activation of AMPKα by 5-aminoimidazole-4-carboxamide-3-ribonucleoside. In conclusions, Klotho deficiency promoted HFD-induced arterial stiffening and hypertension via downregulation of AMPKα activity.
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Affiliation(s)
- Yi Lin
- From the Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center
| | - Jianglei Chen
- From the Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center
| | - Zhongjie Sun
- From the Department of Physiology, College of Medicine, University of Oklahoma Health Sciences Center.
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Abstract
Alternative splicing (AS) has emerged in the postgenomic era as one of the main drivers of proteome diversity, with ≥94% of multiexon genes alternatively spliced in humans. AS is therefore one of the main control mechanisms for cell phenotype, and is a process deregulated in disease. Numerous reports describe pathogenic mutations in splice factors, splice sites, or regulatory sequences. Additionally, compared with the physiologic state, disease often associates with an abnormal proportion of splice isoforms (or novel isoforms), without an apparent driver mutation. It is therefore essential to study how AS is regulated in physiology, how it contributes to pathogenesis, and whether we can manipulate faulty splicing for therapeutic advantage. Although the disease most commonly linked to deregulation of AS in several genes is cancer, many reports detail pathogenic splice variants in diseases ranging from neuromuscular disorders to diabetes or cardiomyopathies. A plethora of splice variants have been implicated in CKDs as well. In this review, we describe examples of these CKD-associated splice variants and ideas on how to manipulate them for therapeutic benefit.
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Affiliation(s)
- Megan Stevens
- School of Physiology and Pharmacology, Faculty of Biomedical Sciences, and Academic Renal Unit, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Sebastian Oltean
- School of Physiology and Pharmacology, Faculty of Biomedical Sciences, and Academic Renal Unit, School of Clinical Sciences, Faculty of Health Sciences, University of Bristol, Bristol, United Kingdom
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Mostafidi E, Moeen A, Nasri H, Ghorbani Hagjo A, Ardalan M. Serum Klotho Levels in Trained Athletes. Nephrourol Mon 2016; 8:e30245. [PMID: 26981496 PMCID: PMC4780197 DOI: 10.5812/numonthly.30245] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 08/15/2015] [Accepted: 11/10/2015] [Indexed: 01/04/2023] Open
Abstract
Background: Klotho is an anti-aging protein that is predominantly secreted by the kidneys. Objectives: The aim of the study was to measure and compare the circulating Klotho levels in the serum of trained athletes and in healthy, non-athlete controls. Materials and Methods: Thirty trained football players were enrolled and their serum Klotho levels were measured the morning after their last evening exercise training. Results: The plasma free Klotho concentration was significantly higher in the athlete group (3.375 ± 1.48 ng/mL) compared to the non-athletes (1.39 ± 0.43 ng/mL) (P < 0.05). Serum levels of cholesterol, triglycerides, calcium, and phosphorus were not significantly different between the two groups. Conclusions: Regular aerobic exercise could increase plasma Klotho levels, and this could be an explanation for exercise-related anti-aging effects.
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Affiliation(s)
- Elmira Mostafidi
- Department of Pathology, Imam Reza Hospital, Tabriz University of Medical Sciences, Tabriz, IR Iran
- Kidney Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran
| | - Akbar Moeen
- Faculty of Sport Sciences, Science and Research Branch, Islamic Azad University, Tehran, IR Iran
| | - Hamid Nasri
- Department of Nephrology, Alzahra Hospital, Isfahan University of Medical Sciences, Isfahan, IR Iran
| | - Amir Ghorbani Hagjo
- Department of Biochemistery, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, IR Iran
| | - Mohammadreza Ardalan
- Kidney Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran
- Corresponding author: Mohammadreza Ardalan, Kidney Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran. Tel: +98-9141168518, Fax: +98-4133366579, E-mail:
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Inhibition of H3K9 histone methyltransferase G9a attenuates renal fibrosis and retains klotho expression. Kidney Int 2016; 89:147-57. [PMID: 26444031 DOI: 10.1038/ki.2015.291] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 07/26/2015] [Accepted: 07/31/2015] [Indexed: 02/06/2023]
Abstract
H3K9 methyltransferase G9a is reportedly induced by transforming growth factor-β1 (TGF-β1) and has an important role in the development of epithelial-mesenchymal transposition in cancer cells. Since the transcriptional activity of the Klotho gene is regulated by H3K9 modification, we investigated the effects of G9a on renal fibrosis and klotho expression. G9a levels were significantly upregulated by day 7 in the kidneys of unilateral ureteral-obstructed mice, but this was inhibited by TGF-β1-neutralizing antibody. Administration of G9a small interfering RNA not only decreased α-smooth muscle actin and fibronectin but also increased klotho expression in the ureteral-obstructed mice. Similarly, intraperitoneal injection of BIX01294, a specific inhibitor of G9a, showed beneficial effects on renal fibrosis and klotho expression with decreased monomethylation of H3K9 (me1). In in vitro experiments, BIX01294 also inhibited TGF-β1-induced fibrotic changes and klotho downregulation along with suppressed H3K9me1. In human kidney biopsy specimens, areas of G9a immunostaining correlated positively with H3K9me1 levels, as well as fibrotic markers, but correlated negatively with klotho expression. Thus, TGF-β1-induced G9a has an important role in the progression of renal fibrosis and reduced klotho expression through H3K9me1.
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72
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Mukhin NA, Milovanov YS, Kozlovskaya LV, Dobrosmyslov IA, Milovanova LY. The serum level of the morphogenetic protein fibroblast growth factor 23 (FGF-23) as a marker for the efficiency of hyperphosphatemia therapy with phosphate-binding agents in chronic kidney disease. TERAPEVT ARKH 2016; 88:41-45. [DOI: 10.17116/terarkh201688441-45] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Ravikumar P, Li L, Ye J, Shi M, Taniguchi M, Zhang J, Kuro-o M, Hu MC, Moe OW, Hsia CCW. αKlotho deficiency in acute kidney injury contributes to lung damage. J Appl Physiol (1985) 2015; 120:723-32. [PMID: 26718784 DOI: 10.1152/japplphysiol.00792.2015] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 12/28/2015] [Indexed: 12/19/2022] Open
Abstract
αKlotho is a circulating protein that originates predominantly from the kidney and exerts cytoprotective effects in distant sites. We previously showed in rodents that the lung is particularly vulnerable to αKlotho deficiency. Because acute lung injury is a common and serious complication of acute kidney injury (AKI), we hypothesized that αKlotho deficiency in AKI contributes to lung injury. To test the hypothesis, we created AKI by renal artery ischemia-reperfusion in rats and observed the development of alveolar interstitial edema and increased pulmonary oxidative damage to DNA, protein, and lipids. Administration of αKlotho-containing conditioned media 6 h post-AKI did not alter plasma creatinine but improved recovery of endogenous αKlotho production 3 days post-AKI, reduced lung edema and oxidative damage, and increased endogenous antioxidative capacity in the lung. Intravenously injected αKlotho rapidly exits alveolar capillaries as a macromolecule, suggesting transcytosis and direct access to the epithelium. To explore the epithelial action of αKlotho, we simulated oxidative stress in vitro by adding hydrogen peroxide to cultured A549 lung epithelial cells. Purified recombinant αKlotho directly protected cells at 20 pM with half-maximal effects at 40-50 pM, which is compatible with circulating αKlotho levels. Addition of recombinant αKlotho activated an antioxidant response element reporter and increased the levels of target proteins of the nuclear factor erythroid-derived 2 related factor system. In summary, αKlotho deficiency in AKI contributes to acute lung injury by reducing endogenous antioxidative capacity and increasing oxidative damage in the lung. αKlotho replacement partially reversed these abnormalities and mitigated pulmonary complications in AKI.
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Affiliation(s)
- Priya Ravikumar
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Liping Li
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Jianfeng Ye
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Mingjun Shi
- Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Masatomo Taniguchi
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Jianning Zhang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Makoto Kuro-o
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Ming Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Orson W Moe
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas
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Mammalian target of rapamycin signaling inhibition ameliorates vascular calcification via Klotho upregulation. Kidney Int 2015; 88:711-21. [DOI: 10.1038/ki.2015.160] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 04/02/2015] [Accepted: 04/09/2015] [Indexed: 11/09/2022]
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Abstract
Aging is an inevitable and progressive biological process involving dysfunction and eventually destruction of every tissue and organ. This process is driven by a tightly regulated and complex interplay between genetic and acquired factors. Klotho is an antiaging gene encoding a single-pass transmembrane protein, klotho, which serves as an aging suppressor through a wide variety of mechanisms, such as antioxidation, antisenescence, antiautophagy, and modulation of many signaling pathways, including insulin-like growth factor and Wnt. Klotho deficiency activates Wnt expression and activity contributing to senescence and depletion of stem cells, which consequently triggers tissue atrophy and fibrosis. In contrast, the klotho protein was shown to suppress Wnt-signaling transduction, and inhibit cell senescence and preserve stem cells. A better understanding of the potential effects of klotho on stem cells could offer novel insights into the cellular and molecular mechanisms of klotho deficiency-related aging and disease. The klotho protein may be a promising therapeutic agent for aging and aging-related disorders.
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Affiliation(s)
- Ao Bian
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA ; Department of Nephrology, First Affiliated Hospital of Nanjing Medical University, Nanjing, People's Republic of China
| | - Javier A Neyra
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
| | - Ming Zhan
- Methodist Hospital Research Institute, Weill Cornell Medical College, Houston, TX, USA
| | - Ming Chang Hu
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA ; Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, USA
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Seo MY, Yang J, Lee JY, Kim K, Kim SC, Chang H, Won NH, Kim MG, Jo SK, Cho W, Kim HK. Renal Klotho expression in patients with acute kidney injury is associated with the severity of the injury. Korean J Intern Med 2015; 30:489-95. [PMID: 26161015 PMCID: PMC4497336 DOI: 10.3904/kjim.2015.30.4.489] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 05/16/2014] [Accepted: 08/18/2014] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND/AIMS The potential physiologic roles of Klotho in acute kidney injury (AKI) have recently been demonstrated in animal models. However, to date, there have been no human studies investigating the expression of renal Klotho in AKI. METHODS We retrospectively collected biopsy specimens and clinical data of AKI patients between January 2001 and December 2012. Klotho expression was determined by immunohistochemical staining, and the clinical-pathological correlation was examined. RESULTS Among the 34 patients diagnosed with acute tubular necrosis or acute tubulointerstitial nephritis, 21 patients without chronic histological lesions were included. The mean age was 37.3 ± 18.5 years and the mean peak creatinine level was 8.2 ± 5.5 mg/dL. In total, 10 patients (47.6%) received temporary renal replacement therapy (RRT); however, 17 patients (81%) showed functional recovery with creatinine levels of < 1.3 mg/dL after 1 month. The intensity of Klotho expression was scored as a percentage of Klotho-positive area. The renal Klotho score showed a significant negative correlation with the initial or peak creatinine level. When the patients were divided into three groups according to the Klotho score (low, middle, high), the low group had a significantly higher peak creatinine level and a more frequent requirement for RRT. However, the Klotho score was not a significant predictor of renal recovery. CONCLUSIONS The results demonstrated that renal Klotho expression in humans decreased significantly according to the severity of AKI, regardless of the etiology, and that low expression was associated with a poor short-term outcome.
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Affiliation(s)
- Min Young Seo
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Jihyun Yang
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Jun Yong Lee
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Kitae Kim
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Sun Chul Kim
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Hyojeong Chang
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Nam Hee Won
- Department of Pathology, Korea University Anam Hospital, Seoul, Korea
| | - Myung-Gyu Kim
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Sang-Kyung Jo
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Wonyong Cho
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
| | - Hyoung Kyu Kim
- Department of Internal Medicine, Korea University Anam Hospital, Seoul, Korea
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Tamma G, Goswami N, Reichmuth J, De Santo NG, Valenti G. Aquaporins, vasopressin, and aging: current perspectives. Endocrinology 2015; 156:777-88. [PMID: 25514088 DOI: 10.1210/en.2014-1812] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Functioning of the hypothalamic-neurohypophyseal-vasopressin axis is altered in aging, and the pathway may represent a plausible target to slow the process of aging. Arginine vasopressin, a nine-amino acid peptide that is secreted from the posterior pituitary in response to high plasma osmolality and hypotension, is central in this pathway. Vasopressin has important roles in circulatory and water homoeostasis mediated by vasopressin receptor subtypes V1a (vascular), V1b (pituitary), and V2 (vascular, renal). A dysfunction in this pathway as a result of aging can result in multiple abnormalities in several physiological systems. In addition, vasopressin plasma concentration is significantly higher in males than in females and vasopressin-mediated effects on renal and vascular targets are more pronounced in males than in females. These findings may be caused by sex differences in vasopressin secretion and action, making men more susceptible than females to diseases like hypertension, cardiovascular and chronic kidney diseases, and urolithiasis. Recently the availability of new, potent, orally active vasopressin receptor antagonists, the vaptans, has strongly increased the interest on vasopressin and its receptors as a new target for prevention of age-related diseases associated with its receptor-altered signaling. This review summarizes the recent literature in the field of vasopressin signaling in age-dependent abnormalities in kidney, cardiovascular function, and bone function.
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Affiliation(s)
- Grazia Tamma
- Department of Biosciences, Biotechnologies, and Biopharmaceutics (G.T., G.V.), University of Bari, 70125 Bari, Italy; Istituto Nazionale di Biostrutture e Biosistemi (G.T., G.V.), 00136 Roma, Italy; Gravitational Physiology and Medicine Research Unit (N.G., J.R.), Institute of Physiology, Medical University of Graz, 8036 Graz, Austria; Department of Medicine (N.G.D.S.), Second University of Naples, 80138 Naples, Italy; and Centro di Eccellenza di Genomica (G.V.) Campo Biomedico Ed Agrario, University of Bari, 70126 Bari, Italy
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Torregrosa I, Montoliu C, Urios A, Giménez-Garzó C, Tomás P, Solís MÁ, Ramos C, Juan I, Puchades MJ, Saez GT, Blasco ML, Miguel A. Klotho urinario determinado por ELISA como biomarcador precoz de fracaso renal agudo en pacientes sometidos a cirugía cardiaca o angiografía coronaria. Nefrologia 2015; 35:172-8. [DOI: 10.1016/j.nefro.2014.12.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 12/03/2014] [Indexed: 01/30/2023] Open
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Abstract
PURPOSE OF REVIEW Cardiovascular disease remains the single most serious contributor to mortality in chronic kidney disease (CKD). Although conventional risk factors are prevalent in CKD, both cardiomyopathy and vasculopathy can be caused by pathophysiologic mechanisms specific to the uremic state. CKD is a state of systemic αKlotho deficiency. Although the molecular mechanism of action of αKlotho is not well understood, the downstream targets and biologic functions of αKlotho are astonishingly pleiotropic. An emerging body of literature links αKlotho to uremic vasculopathy. RECENT FINDINGS The expression of αKlotho in the vasculature is controversial because of conflicting data. Regardless of whether αKlotho acts as a circulating or resident protein, there are good data associating changes in αKlotho levels with vascular pathology including vascular calcification and in-vitro data of the direct action of αKlotho on both the endothelium and vascular smooth muscle cells in terms of cytoprotection and prevention of mineralization. SUMMARY It is critical to understand the pathogenic role of αKlotho on the integral endothelium-vascular smooth muscle network rather than each cell type in isolation in uremic vasculopathy, as αKlotho can serve as a potential prognostic biomarker and a biological therapeutic agent.
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Bordonaro M, Lazarova DL. Hypothesis: cell signalling influences age-related risk of colorectal cancer. J Cell Mol Med 2015; 19:74-81. [PMID: 25388238 PMCID: PMC4288351 DOI: 10.1111/jcmm.12366] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 06/10/2014] [Indexed: 01/05/2023] Open
Abstract
We propose that ageing is linked to colonic carcinogenesis through crosstalk between Wnt activity and signalling pathways related to ageing and senescence: progerin, klotho and mTOR. Mutations in the Wnt signalling pathway are responsible for the majority of colorectal cancers (CRCs); however, hyperactivation of Wnt signalling by butyrate, a breakdown product of dietary fibre, induces CRC cell apoptosis. This effect of butyrate may in part explain the protective action of fibre against CRC. Hutchinson-Gilford progeria syndrome is a premature ageing disorder caused by accumulation of the progerin protein; however, healthy individuals also produce progerin in the course of their normal ageing. Progerin activates expression of the Wnt inhibitors HES1 and TLE1. Thus, we hypothesize that with age, the increasing expression of progerin suppresses butyrate-mediated Wnt hyperactivation and apoptosis, leading to increased CRC risk. Wild-type klotho contributes to a significantly increased lifespan; however, Klotho gene variants differ significantly between newborns and elderly. Klotho inhibits basal Wnt signalling activity; thus, the protein may function as a tumour suppressor for CRC. However, similar to progerin, klotho variants associated with lifespan differences may repress butyrate-mediated Wnt hyperactivation, and thus increase the risk of CRC. Finally, mTOR signalling has also been linked to human ageing, and crosstalk between Wnt and mTOR signalling may influence colonic tumourigenesis. Understanding how progerin, klotho and mTOR link ageing with colonic neoplastic development may lead to novel preventive and therapeutic strategies against CRC associated with age.
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Affiliation(s)
- Michael Bordonaro
- Department of Basic Sciences, The Commonwealth Medical CollegeScranton, PA, USA
| | - Darina L Lazarova
- Department of Basic Sciences, The Commonwealth Medical CollegeScranton, PA, USA
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Otani-Takei N, Masuda T, Akimoto T, Honma S, Watanabe Y, Shiizaki K, Miki T, Kusano E, Asano Y, Kuro-o M, Nagata D. Association between Serum Soluble Klotho Levels and Mortality in Chronic Hemodialysis Patients. Int J Endocrinol 2015; 2015:406269. [PMID: 26604925 PMCID: PMC4641198 DOI: 10.1155/2015/406269] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2015] [Revised: 10/04/2015] [Accepted: 10/13/2015] [Indexed: 01/25/2023] Open
Abstract
Klotho is a single-pass transmembrane protein predominantly expressed in the kidney. The extracellular domain of Klotho is subject to ectodomain shedding and is released into the circulation as a soluble form. Soluble Klotho is also generated from alternative splicing of the Klotho gene. In mice, defects in Klotho expression lead to complex phenotypes resembling those observed in dialysis patients. However, the relationship between the level of serum soluble Klotho and overall survival in hemodialysis patients, who exhibit a state of Klotho deficiency, remains to be delineated. Here we prospectively followed a cohort of 63 patients with a mean duration of chronic hemodialysis of 6.7 ± 5.4 years for a median of 65 months. Serum soluble Klotho was detectable in all patients (median 371 pg/mL, interquartile range 309-449). Patients with serum soluble Klotho levels below the lower quartile (<309 pg/mL) had significantly higher cardiovascular and all-cause mortality rates. Furthermore, the higher all-cause mortality persisted even after adjustment for confounders (hazard ratio 4.14, confidence interval 1.29-13.48). We conclude that there may be a threshold for the serum soluble Klotho level associated with a higher risk of mortality.
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Affiliation(s)
- Naoko Otani-Takei
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Takahiro Masuda
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
- *Takahiro Masuda:
| | - Tetsu Akimoto
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Sumiko Honma
- Department of Nephrology, Japanese Red Cross Koga Hospital, Koga, Ibaraki, Japan
| | - Yuko Watanabe
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Kazuhiro Shiizaki
- Division of Anti-Aging Medicine, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Takuya Miki
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Eiji Kusano
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Yasushi Asano
- Department of Nephrology, Japanese Red Cross Koga Hospital, Koga, Ibaraki, Japan
| | - Makoto Kuro-o
- Division of Anti-Aging Medicine, Center for Molecular Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
| | - Daisuke Nagata
- Division of Nephrology, Department of Internal Medicine, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan
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Nitta K, Nagano N, Tsuchiya K. Fibroblast growth factor 23/klotho axis in chronic kidney disease. Nephron Clin Pract 2014; 128:1-10. [PMID: 25402964 DOI: 10.1159/000365787] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 06/26/2014] [Indexed: 12/27/2022] Open
Abstract
Fibroblast growth factor-23 (FGF23) is a bone-derived hormone that regulates phosphate and 1,25-hydroxyvitamin D [1,25(OH)2D] metabolism. FGF23 binds to FGF receptor 1 with its coreceptor Klotho and maintains serum phosphate levels within the normal range by increasing renal phosphate excretion. In addition, FGF23 reduces the synthesis and accelerates the degradation of 1,25(OH)2D to reduce intestinal phosphate absorption. Moreover, FGF23 acts at the parathyroid gland to decrease parathyroid hormone synthesis and secretion. In chronic kidney disease (CKD), serum FGF23 levels rise exponentially as renal function declines long before a significant increase in serum phosphate concentration occurs. Although there is room for argument, FGF23 and Klotho are recently reported contributors to vascular calcification. Finally, prospective observational studies have shown that serum FGF23 concentrations predict mortality not only among dialysis patients but among predialysis CKD patients. In addition to being a coreceptor for FGF23, Klotho circulates as an endocrine substance and exerts a multitude of effects. This review describes recent advances in research on the FGF23-Klotho axis in CKD. © 2014 S. Karger AG, Basel.
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Affiliation(s)
- Kosaku Nitta
- Kidney Center, Department of Medicine, Tokyo Women's Medical University, Tokyo, Japan
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83
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Abstract
The Klotho family consists of three single-pass transmembrane proteins—αKlotho, βKlotho and γKlotho. Each of them combines with fibroblast growth factor (FGF) receptors (FGFRs) to form receptor complexes for various FGF’s. αKlotho is a co-receptor for physiological FGF23 signaling and appears essential for FGF23-mediated regulation of mineral metabolism. αKlotho protein also plays a FGF23-independent role in phosphate homeostasis. Animal experimental studies and clinical observations have demonstrated that αKlotho deficiency leads to severe hyperphosphatemia; moderate elevation of αKlotho reduces serum phosphate and extremely high αKlotho induces hypophosphatemia and high-FGF23. αKlotho maintains circulating phosphate in a narrow range by modulating intestinal phosphate absorption, urinary phosphate excretion by the kidney, and phosphate distribution into bone rather than soft tissue in concerted interaction with other calciophosphotropic hormones such as PTH, FGF23, and 1,25-(OH)2 vitamin D. The role of αKlotho in maintenance of phosphate homeostasis is mediated by direct suppression of Na-dependent phosphate cotransporters in target organs. Therefore, αKlotho manipulation may be a novel strategy for genetic and acquired phosphate disorders and for medical conditions with αKlotho deficiency such as chronic kidney disease in future.
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Affiliation(s)
- Ao Bian
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Nephrology, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, PR of China
| | - Changying Xing
- Department of Nephrology, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, PR of China
| | - Ming Chang Hu
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
- Corresponding author: Ming Chang Hu, M.D.; Ph.D., Department of Internal Medicine, Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, UT Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX, 75390-885 USA, Telephone: 1-214-648-9797, Tax: 1-214-648-5652,
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84
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Barker SL, Pastor J, Carranza D, Quiñones H, Griffith C, Goetz R, Mohammadi M, Ye J, Zhang J, Hu MC, Kuro-o M, Moe OW, Sidhu SS. The demonstration of αKlotho deficiency in human chronic kidney disease with a novel synthetic antibody. Nephrol Dial Transplant 2014; 30:223-33. [PMID: 25324355 DOI: 10.1093/ndt/gfu291] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND αKlotho is the prototypic member of the Klotho family and is most highly expressed in the kidney. αKlotho has pleiotropic biologic effects, and in the kidney, its actions include regulation of ion transport, cytoprotection, anti-oxidation and anti-fibrosis. In rodent models of chronic kidney disease (CKD), αKlotho deficiency has been shown to be an early biomarker as well as a pathogenic factor. The database for αKlotho in human CKD remains controversial even after years of study. METHODS We used a synthetic antibody library to identify a high-affinity human antigen-binding fragment that recognizes human, rat and mouse αKlotho primarily in its native, rather than denatured, form. RESULTS Using an immunoprecipitation-immunoblot (IP-IB) assay, we measured both serum and urinary levels of full-length soluble αKlotho in humans and established that human CKD is associated with αKlotho deficiency in serum and urine. αKlotho levels were detectably lower in early CKD preceding disturbances in other parameters of mineral metabolism and progressively declined with CKD stages. We also found that exogenously added αKlotho is inherently unstable in the CKD milieu suggesting that decreased production may not be the sole reason for αKlotho deficiency. CONCLUSION Synthetic antibody libraries harbor tremendous potential for a variety of biomedical and clinical applications. Using such a reagent, we furnish data in support of αKlotho deficiency in human CKD, and we set the foundation for the development of diagnostic and therapeutic applications of anti-αKlotho antibodies.
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Affiliation(s)
- Sarah L Barker
- Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Johanne Pastor
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Danielle Carranza
- Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON, Canada
| | - Henry Quiñones
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Carolyn Griffith
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Regina Goetz
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Moosa Mohammadi
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Jianfeng Ye
- Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Jianning Zhang
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Ming Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Makoto Kuro-o
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Orson W Moe
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Sachdev S Sidhu
- Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON, Canada
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Lee EY, Kim SS, Lee JS, Kim IJ, Song SH, Cha SK, Park KS, Kang JS, Chung CH. Soluble α-klotho as a novel biomarker in the early stage of nephropathy in patients with type 2 diabetes. PLoS One 2014; 9:e102984. [PMID: 25084095 PMCID: PMC4118846 DOI: 10.1371/journal.pone.0102984] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 06/24/2014] [Indexed: 01/25/2023] Open
Abstract
Objective Although α-klotho is known as an anti-aging, antioxidant, and cardio-renal protective protein, the clinical implications of soluble α-klotho levels in patients with diabetes have not been evaluated. Therefore, this study evaluated whether plasma and urinary α-klotho levels are associated with albuminuria in kidney disease in diabetes. Research Design and Methods A total of 147 patients with type 2 diabetes and 25 healthy control subjects were enrolled. The plasma and urine concentrations of α-klotho were analyzed by enzyme-linked immunosorbent assay. Results Plasma α-klotho (572.4 pg/mL [95% CI, 541.9–604.6 pg/mL] vs. 476.9 pg/mL [95% CI, 416.9–545.5 pg/mL]) and urinary α-klotho levels (59.8 pg/mg creatinine [95% CI, 43.6–82.0 pg/mg creatinine] vs. 21.0 pg/mg creatinine [95% CI, 9.7–45.6 pg/mg creatinine]) were significantly higher in diabetic patients than non-diabetic controls. Among diabetic patients, plasma α-klotho concentration was inversely associated with albuminuria stages (normoalbuminuria, 612.6 pg/mL [95% CI, 568.9–659.6 pg/mL], microalbuminuria, 551.8 pg/mL [95% CI, 500.5–608.3 pg/mL], and macroalbuminuria, 505.7 pg/mL [95% CI, 439.7–581.7 pg/mL] (p for trend = 0.0081), while urinary α-klotho levels were remained constantly high with increasing urinary albumin excretion. Conclusions Soluble α-klotho levels in plasma and urine may be novel and useful early markers of diabetic renal injury.
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Affiliation(s)
- Eun Young Lee
- Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Korea
- * E-mail:
| | - Sang Soo Kim
- Department of Internal Medicine, Pusan National University Hospital, Busan, Korea
| | - Ji-Sung Lee
- Biostatistical Consulting Unit, Soonchunhyang University Medical Center, Seoul, Korea
| | - In Joo Kim
- Department of Internal Medicine, Pusan National University Hospital, Busan, Korea
| | - Sang Heon Song
- Department of Internal Medicine, Pusan National University Hospital, Busan, Korea
| | - Seung-Kuy Cha
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Kyu-Sang Park
- Department of Physiology, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Jeong Suk Kang
- Department of Internal Medicine, Soonchunhyang University Cheonan Hospital, Cheonan, Korea
| | - Choon Hee Chung
- Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
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Abstract
PURPOSE OF REVIEW The wealth of data regarding fibroblast growth factor-23 (FGF23) and Klotho in chronic kidney disease (CKD) has risen exponentially over the past decade. This review is an attempt to summarize pivotal aspects of previous research, provide an update of recent findings and define important areas for future investigation. RECENT FINDINGS The phosphaturic hormone FGF23 increases dramatically as renal function declines. Identification of contributing stimuli to the rise in FGF23 is fundamental and recent evidence suggest a multifactorial cause which entails perturbed osteocyte function and renal mechanisms such as Klotho deficiency and, somewhat paradoxically, systemic Klotho excess. Circulating FGF23 predicts adverse outcomes, particularly cardiovascular disease, in CKD as well as in the general population. The concept of FGF23 merely as a biomarker and regulator of mineral metabolism is currently challenged by data linking FGF23 to pathological processes such as cardiac hypertrophy. Conversely, tissue level of the FGF23 coreceptor Klotho declines in early CKD and this deficiency is linked to accelerated ageing, cellular senescence, vascular calcification, oxidative stress and renal fibrosis. At present, methodological difficulties limit the utility of soluble Klotho measurements. Animal proof-of-concept studies have demonstrated beneficial effects of Klotho delivery in CKD, whereas anti-FGF23 therapy using neutralizing antibodies improved biochemical and bone parameters at the expense of increased vascular calcification and mortality. SUMMARY Pathological alterations of FGF23-Klotho in CKD are implicated as clinical biomarkers and may provide novel therapeutic strategies to alleviate the cardiovascular risk and slow CKD progression.
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Zununi Vahed S, Nikasa P, Ardalan M. Klotho and renal fibrosis. Nephrourol Mon 2013; 5:946-8. [PMID: 24693499 PMCID: PMC3955284 DOI: 10.5812/numonthly.16179] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 11/11/2013] [Indexed: 02/06/2023] Open
Affiliation(s)
- Sepide Zununi Vahed
- Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, IR Iran
- Chronic Kidney Disease Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran
| | - Parisa Nikasa
- Faculty of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, IR Iran
- Chronic Kidney Disease Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran
| | - Mohammadreza Ardalan
- Chronic Kidney Disease Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran
- Corresponding author: Mohammadreza Ardalan, Chronic Kidney Disease Research Center, Tabriz University of Medical Sciences, Tabriz, IR Iran. Tel: +98-9141168518, Fax: +98-4113366579, E-mail:
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de Brito Galvao JF, Nagode LA, Schenck PA, Chew DJ. Calcitriol, calcidiol, parathyroid hormone, and fibroblast growth factor-23 interactions in chronic kidney disease. J Vet Emerg Crit Care (San Antonio) 2013; 23:134-62. [PMID: 23566108 PMCID: PMC3677418 DOI: 10.1111/vec.12036] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Accepted: 02/05/2013] [Indexed: 12/13/2022]
Abstract
Objective To review the inter-relationships between calcium, phosphorus, parathyroid hormone (PTH), parent and activated vitamin D metabolites (vitamin D, 25(OH)-vitamin D, 1,25(OH)2-vitamin D, 24,25(OH)2-vitamin D), and fibroblast growth factor-23 (FGF-23) during chronic kidney disease (CKD) in dogs and cats. Data Sources Human and veterinary literature. Human Data Synthesis Beneficial effects of calcitriol treatment during CKD have traditionally been attributed to regulation of PTH but new perspectives emphasize direct renoprotective actions independent of PTH and calcium. It is now apparent that calcitriol exerts an important effect on renal tubular reclamation of filtered 25(OH)-vitamin D, which may be important in maintaining adequate circulating 25(OH)-vitamin D. This in turn may be vital for important pleiotropic actions in peripheral tissues through autocrine/paracrine mechanisms that impact the health of those local tissues. Veterinary Data Synthesis Limited information is available reporting the benefit of calcitriol treatment in dogs and cats with CKD. Conclusions A survival benefit has been shown for dogs with CKD treated with calcitriol compared to placebo. The concentrations of circulating 25(OH)-vitamin D have recently been shown to be low in people and dogs with CKD and are related to survival in people with CKD. Combination therapy for people with CKD using both parental and activated vitamin D compounds is common in human nephrology and there is a developing emphasis using combination treatment with activated vitamin D and renin-angiotensin-aldosterone-system (RAAS) inhibitors.
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Lam-Rachlin J, Romero R, Korzeniewski SJ, Schwartz AG, Chaemsaithong P, Hernandez-Andrade E, Dong Z, Yeo L, Hassan SS, Chaiworapongsa T. Infection and smoking are associated with decreased plasma concentration of the anti-aging protein, α-klotho. J Perinat Med 2013; 41:581-94. [PMID: 23770558 PMCID: PMC4144357 DOI: 10.1515/jpm-2013-0084] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 05/14/2013] [Indexed: 02/06/2023]
Abstract
OBJECTIVE The objective of this study was to determine whether maternal plasma concentrations of soluble α-klotho are different between women with microbial invasion of the intra-amniotic cavity (MIAC) and those without MIAC among preterm labor and intact membranes (PTL) or preterm prelabor rupture of membranes (pPROM). METHODS A cross-sectional study was conducted to include women in the following groups: i) PTL with MIAC (n=14); ii) PTL without MIAC (n=79); iii) pPROM with MIAC (n=30); and iv) pPROM without MIAC (n=33). MIAC was defined as a positive amniotic fluid culture for microorganisms (aerobic/anaerobic bacteria or genital mycoplasmas). Amniotic fluid samples were obtained within 48 h of maternal blood collection. Plasma concentration of soluble α-klotho was determined by ELISA. RESULTS i) The median plasma concentration (pg/mL) of soluble α-klotho was significantly lower in patients with MIAC than in those without MIAC (787.0 vs. 1117.8; P<0.001). ii) Among patients with PTL, those with MIAC had a lower median plasma concentration (pg/mL) of soluble α-klotho than those without MIAC (787.0 vs. 1138.9; P=0.007). iii) Among patients with pPROM, those with MIAC had a lower median plasma concentration (pg/mL) of soluble α-klotho than those without MIAC (766.4 vs. 1001.6; P=0.045). iv) There was no significant difference in the median plasma concentration of soluble α-klotho between PPROM without MIAC and PTL without MIAC (1001.6 pg/mL vs. 1138.9 pg/mL, respectively; P=0.5). v) After adjustment for potential confounders (maternal age, tobacco use, gestational age at venipuncture), soluble α-klotho remained significantly associated with MIAC (P=0.02); and vi) Among patients without MIAC, smoking was significantly associated with a lower median plasma concentration soluble α-klotho than in non-smokers (794.2 pg/mL vs. 1382.0 pg/mL, respectively; P<0.001); however, this difference was not observed in patients with MIAC. CONCLUSIONS Intra-amniotic infection occurring at preterm gestations (regardless of membrane status) was associated with a decrease in maternal plasma concentrations of soluble α-klotho. Moreover, among patients without infection, the plasma concentration of α-klotho was lower in smokers.
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Affiliation(s)
- Jennifer Lam-Rachlin
- Perinatology Research Branch, Wayne State University/Hutzel Women ’ s Hospital, MI 48201, USA.
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Block GA, Ix JH, Ketteler M, Martin KJ, Thadhani RI, Tonelli M, Wolf M, Jüppner H, Hruska K, Wheeler DC. Phosphate Homeostasis in CKD: Report of a Scientific Symposium Sponsored by the National Kidney Foundation. Am J Kidney Dis 2013; 62:457-73. [DOI: 10.1053/j.ajkd.2013.03.042] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Accepted: 03/19/2013] [Indexed: 02/08/2023]
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Zhou L, Li Y, Zhou D, Tan RJ, Liu Y. Loss of Klotho contributes to kidney injury by derepression of Wnt/β-catenin signaling. J Am Soc Nephrol 2013; 24:771-85. [PMID: 23559584 DOI: 10.1681/asn.2012080865] [Citation(s) in RCA: 276] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Aging is an independent risk factor for CKD, but the molecular mechanisms that link aging and CKD are not well understood. The antiaging protein Klotho may be an endogenous antagonist of Wnt/β-catenin signaling, which promotes fibrogenesis, suggesting that loss of Klotho may contribute to CKD through increased Wnt/β-catenin activity. Here, normal adult kidneys highly expressed Klotho in the tubular epithelium, but various models of nephropathy exhibited markedly less expression of Klotho. Loss of Klotho was closely associated with increased β-catenin in the diseased kidneys, suggesting an inverse correlation between Klotho and canonical Wnt signaling. In vitro, both full-length and secreted Klotho bound to multiple Wnts, including Wnt1, Wnt4, and Wnt7a. Klotho repressed gene transcription induced by Wnt but not by active β-catenin. Furthermore, Klotho blocked Wnt-triggered activation and nuclear translocation of β-catenin, as well as the expression of its target genes in tubular epithelial cells. Investigating potential mediators of Klotho loss in CKD, we found that TGF-β1 suppressed Klotho expression and concomitantly activated β-catenin; conversely, overexpression of Klotho abolished fibrogenic effects of TGF-β1. In two mouse models of CKD induced by unilateral ureteral obstruction or adriamycin, in vivo expression of secreted Klotho inhibited the activation of renal β-catenin and expression of its target genes. Secreted Klotho also suppressed myofibroblast activation, reduced matrix expression, and ameliorated renal fibrosis. Taken together, these results suggest that Klotho is an antagonist of endogenous Wnt/β-catenin activity; therefore, loss of Klotho may contribute to kidney injury by releasing the repression of pathogenic Wnt/β-catenin signaling.
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Affiliation(s)
- Lili Zhou
- Division of Nephrology, Nanfang Hospital, Southern Medical University and Guangdong Provincial Institute of Nephrology, Guangzhou, China
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Affiliation(s)
- Jürg Biber
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland; , ,
| | - Nati Hernando
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland; , ,
| | - Ian Forster
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, CH-8057 Zurich, Switzerland; , ,
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Hu MC, Shiizaki K, Kuro-o M, Moe OW. Fibroblast growth factor 23 and Klotho: physiology and pathophysiology of an endocrine network of mineral metabolism. Annu Rev Physiol 2013; 75:503-33. [PMID: 23398153 PMCID: PMC3770142 DOI: 10.1146/annurev-physiol-030212-183727] [Citation(s) in RCA: 407] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The metabolically active and perpetually remodeling calcium phosphate-based endoskeleton in terrestrial vertebrates sets the demands on whole-organism calcium and phosphate homeostasis that involves multiple organs in terms of mineral flux and endocrine cross talk. The fibroblast growth factor (FGF)-Klotho endocrine networks epitomize the complexity of systems biology, and specifically, the FGF23-αKlotho axis highlights the concept of the skeleton holding the master switch of homeostasis rather than a passive target organ as hitherto conceived. Other than serving as a coreceptor for FGF23, αKlotho circulates as an endocrine substance with a multitude of effects. This review covers recent data on the physiological regulation and function of the complex FGF23-αKlotho network. Chronic kidney disease is a common pathophysiological state in which FGF23-αKlotho, a multiorgan endocrine network, is deranged in a self-amplifying vortex resulting in organ dysfunction of the utmost severity that contributes to its morbidity and mortality.
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Affiliation(s)
- Ming Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
- Department of Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390;
| | - Kazuhiro Shiizaki
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Makoto Kuro-o
- Department of Pathology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
- Department of Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390;
| | - Orson W. Moe
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
- Department of Physiology University of Texas Southwestern Medical Center, Dallas, Texas 75390
- Department of Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390;
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Abstract
Klotho is highly expressed in the kidney and a soluble form of Klotho functions as an endocrine substance that exerts multiple actions including the modulation of renal solute transport and the protection of the kidney from a variety of insults in experimental models. At present, the Klotho database is still largely preclinical, but the anticipated forthcoming impact on clinical nephrology can be immense. This manuscript puts these potentials into perspective for the clinician. There is renal and systemic Klotho deficiency in both acute kidney injury (AKI) and chronic kidney disease (CKD). Klotho plummets very early and severely in AKI and represents a pathogenic factor that exacerbates acute kidney damage. In CKD, Klotho deficiency exerts a significant impact on progression of renal disease and extra renal complications. In AKI, soluble Klotho levels in plasma and/or urine may serve as an early biomarker for kidney parenchymal injury. Restoration by exogenous supplementation or stimulation of endogenous Klotho may prevent and/or ameliorate kidney injury and mitigate CKD development. In CKD, Klotho levels may be an indicator of early disease and predict the rate of progression, and presence and severity of soft tissue calcification. The correction of Klotho deficiency may delay progression and forestall development of extra renal complications in CKD. Rarely does one find a molecule with such broad potential applications in nephrology. Klotho can possibly emerge on the horizon as a candidate for an unprecedented sole biomarker and intervention. Nephrologists should monitor the progress of the preclinical studies and the imminently emerging human database.
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Abstract
Klotho is a single-pass transmembrane protein that is highly expressed in the kidney and is known to act as a coreceptor for fibroblast growth factor 23. The extracellular domain can be produced independently or shed from membrane-bound Klotho and functions as an endocrine substance with multiple functions including antioxidation, modulation of ion transport, suppression of fibrosis, and preservation of stem cells. Emerging evidence has revealed that Klotho deficiency is an early event in acute kidney injury (AKI), and a pathogenic factor that exacerbates acute kidney damage and contributes to long-term consequences. Restoration by exogenous supplementation or stimulation of endogenous Klotho might prevent and ameliorate injury, promote recovery, and suppress fibrosis to mitigate development of chronic kidney disease. Although data are still emerging, in this Perspectives article we discuss why this renal-derived protein is a highly promising candidate as both an early biomarker and therapeutic agent for AKI.
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Affiliation(s)
- Ming-Chang Hu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8885, USA.
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