Chronic kidney disease (CKD) is grave health problem in the U.S.A. and worldwide with unacceptably high morbidity and mortality. Disorders of mineral metabolism are ubiquitous and assume a central role in CKD in terms of contribution to its progression, complications, and mortality. Models of dysfunctional mineral metabolism in CKD have evolved over time and some effective interventions have indeed been developed but are still rather limited in terms of their ability to prevent or reverse these morbid disorders. Based on the current database including our own preliminary data, we present a model where Klotho deficiency is an early event in CKD followed by rise in fibroblast growth factor-23 (FGF23) and decline in vitamin D, which is then compounded by hyperparathyroidism and hyperphosphatemia. These disturbances aggravate each other resulting in a self-amplifying downward spiral that leads to numerous morbid consequences of mineral disturbance that ramifies into bone disease and cardiovascular complications. We propose to test our hypothesis utilizing not observational measurements, but an interventional approach to interrupt the vicious cycle rather than using primarily rodent models of CKD. First, we will restore normal Klotho expression by replacement therapy and look for retardation or arrest of progression and complications of kidney disease. Second, we will suppress endogenous FGF23 using an antagonistic peptide (C-terminal fragment of FGF23) that we discovered and verified in normal rodents. The read-out will be the same as that used for testing Klotho replacement therapy. Third, we will test several simple maneuvers that can potentially preserve or stimulate endogenous Klotho expression. Depending on the initial findings from these three sets of studies, we will consider designing combination therapy. Mineral disturbances in CKD is in dire need for novel models that encompass more of our database and most critically, definitive interventions that target the root of the problem. The proposed experiments serve dual purposes. It will prove or refute our hypothesis of the vicious cycle of Klotho, FGF23, vitamin D, parathyroid hormone, and phosphate. In addition, it will also lay the foundation of preclinical data to test the therapeutic potential of Klotho replacement and FGF23 antagonism.

Public Health Relevance

Chronic kidney disease is a formidable public healthy problem that impacts negatively on quality of life, survival, and health care costs but there is limited definitive therapy at present at our disposal. We constructed a model where abnormalities in two proteins called Klotho and Fibroblast Growth Factor-23 triggers a downhill spiral of a host of ill events in kidney disease. In this application, we aim to test this model and also devise novel ways to arrest this spiraling deterioration.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK091392-02
Application #
8251210
Study Section
Cellular and Molecular Biology of the Kidney Study Section (CMBK)
Program Officer
Kimmel, Paul
Project Start
2011-04-10
Project End
2016-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
2
Fiscal Year
2012
Total Cost
$345,372
Indirect Cost
$127,872
Name
University of Texas Sw Medical Center Dallas
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
800771545
City
Dallas
State
TX
Country
United States
Zip Code
75390
Neyra, Javier A; Moe, Orson W; Hu, Ming Chang (2015) Fibroblast growth factor 23 and acute kidney injury. Pediatr Nephrol 30:1909-18
Ravikumar, Priya; Ye, Jianfeng; Zhang, Jianning et al. (2014) ?-Klotho protects against oxidative damage in pulmonary epithelia. Am J Physiol Lung Cell Mol Physiol 307:L566-75
Panesso, Monica C; Shi, Mingjun; Cho, Han J et al. (2014) Klotho has dual protective effects on cisplatin-induced acute kidney injury. Kidney Int 85:855-70
Hu, Ming Chang; Kuro-o, Makoto; Moe, Orson W (2014) ?Klotho and vascular calcification: an evolving paradigm. Curr Opin Nephrol Hypertens 23:331-9
Bobulescu, Ion Alexandru; Lotan, Yair; Zhang, Jianning et al. (2014) Triglycerides in the human kidney cortex: relationship with body size. PLoS One 9:e101285
Hu, Ming-Chang; Shi, Mingjun; Cho, Han J et al. (2013) The erythropoietin receptor is a downstream effector of Klotho-induced cytoprotection. Kidney Int 84:468-81
Huang, Chou-Long; Moe, Orson W (2013) Clinical assessment of phosphorus status, balance and renal handling in normal individuals and in patients with chronic kidney disease. Curr Opin Nephrol Hypertens 22:452-8
Bobulescu, I Alexandru; Maalouf, Naim M; Capolongo, Giovanna et al. (2013) Renal ammonium excretion after an acute acid load: blunted response in uric acid stone formers but not in patients with type 2 diabetes. Am J Physiol Renal Physiol 305:F1498-503
Hu, Ming Chang; Kuro-o, Makoto; Moe, Orson W (2013) Renal and extrarenal actions of Klotho. Semin Nephrol 33:118-29
Kuro-o, Makoto (2013) Klotho, phosphate and FGF-23 in ageing and disturbed mineral metabolism. Nat Rev Nephrol 9:650-60

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