title: The demonstration of αKlotho deficiency in human chronic kidney disease with a novel synthetic antibody.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON, Canada.
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Barker
authors.affiliation: Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Johanne
authors.initials: J
authors.lastname: Pastor
authors.affiliation: Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON, Canada.
authors.forename: Danielle
authors.initials: D
authors.lastname: Carranza
authors.affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Quiñones
authors.affiliation: Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Griffith
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
authors.forename: Regina
authors.initials: R
authors.lastname: Goetz
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA.
authors.forename: Moosa
authors.initials: M
authors.lastname: Mohammadi
authors.affiliation: Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Ye
authors.affiliation: Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Jianning
authors.initials: J
authors.lastname: Zhang
authors.affiliation: 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.
authors.forename: Ming Chang
authors.initials: MC
authors.lastname: Hu
authors.affiliation: 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.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuro-o
authors.affiliation: 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.
authors.forename: Orson W
authors.initials: OW
authors.lastname: Moe
authors.affiliation: Banting and Best Department of Medical Research and Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, ON, Canada.
authors.forename: Sachdev S
authors.initials: SS
authors.lastname: Sidhu
mesh_terms: D000818:Animals; D000906:Antibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005346:Fibroblast Growth Factors / Q000097:blood; D005966:Glucuronidase / Q000172:deficiency* / Q000276:immunology; D064368:Healthy Volunteers; D006801:Humans; D015151:Immunoblotting; D007140:Immunoglobulin Fab Fragments / Q000097:blood; D047468:Immunoprecipitation; D000090265:Klotho Proteins; D051379:Mice; D019151:Peptide Library; D051381:Rats; D051436:Renal Insufficiency, Chronic / Q000201:enzymology*
chemical_list: D000906:Antibodies; D015415:Biomarkers; D007140:Immunoglobulin Fab Fragments; D019151:Peptide Library; D005346:Fibroblast Growth Factors; D005966:Glucuronidase; D000090265:Klotho Proteins
keywords: assay; chronic kidney disease; klotho; synthetic antibodies