The Demonstration Of Alpha Klotho Deficiency In Human Chronic Kidney Disease With A Novel Synthetic Antibody

Background. alpha Klotho is the prototypic member of the Klotho family and is most highly expressed in the kidney. alpha Klotho 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), alpha Klotho deficiency has been shown to be an early biomarker as well as a pathogenic factor. The database for alpha Klotho 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 alpha Klotho 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 alpha Klotho in humans and established that human CKD is associated with alpha Klotho deficiency in serum and urine. alpha Klotho 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 alpha Klotho is inherently unstable in the CKD milieu suggesting that decreased production may not be the sole reason for alpha Klotho 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 alpha Klotho deficiency in human CKD, and we set the foundation for the development of diagnostic and therapeutic applications of anti-alpha Klotho antibodies.