Date on Master's Thesis/Doctoral Dissertation

5-2016

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biochemistry and Molecular Biology

Degree Program

Biochemistry and Molecular Biology, PhD

Committee Chair

Powell, David

Committee Co-Chair (if applicable)

Clark, Barbara

Committee Member

Clark, Barbara

Committee Member

Kosiewicz, Michele

Committee Member

Prough, Russell

Committee Member

Ramos, Kenneth

Author's Keywords

ABIN1; glomerulonephritis; NF-kB; podocyte; neutrophil; inflammation

Abstract

Glomerulonephritis (GN) is the most common cause of end-stage renal disease worldwide and is characterized by deposition of immune complex, inflammation, proteinuria and podocyte damage. Immunosuppressive therapy is effective in less than 50% of patients, indicating that immunological activity is not the only relevant cause of kidney injury. While methods have been described for neutrophil-mediated immune activation, specific glomerular mechanisms for recruitment of neutrophils and development of GN have not been determined. Here I present a pathogenic mechanism for the development of GN involving a novel podocyte-neutrophil axis and reveal the importance of glomerular NF-κB inhibition by the ubiquitin binding protein, ABIN1. I implicate enhanced glomerular NF-κB activity in human chronic kidney disease using transcriptomic analysis and link genetic ABIN1 polymorphisms to increased risk of lupus-related GN. Mice expressing dysfunctional ABIN1 with disrupted polyubiquitin binding activity are shown to develop spontaneous, progressive glomerular disease. Prevention and early diagnosis require an understanding of the initiating steps of disease pathogenesis, so early pathogenic changes were examined using antibodies directed against the mouse glomerular basement membrane to induce rapid glomerular damage. Glomeruli of mice expressing dysfunctional ABIN1 exhibit increased production of NF-κB target cytokines and rapid induction of GN versus wild type mice. Bone marrow transplantation reveals the glomerular genotype is more critical than the immune genotype following insult, further supporting the role of the target tissue in early disease pathogenesis. I outline the contributions of mass spectrometry to the discovery of modulating factors and disease biomarkers in autoimmunity and describe an optimized technique to characterize the secreted protein milieu of cultured human podocytes. Dysfunctional ABIN1 results in enhanced cytokine production by podocytes that can recruit and activate primary neutrophils. Further, the podocytes are more sensitive to pathogenic cytoskeletal remodeling following exposure to neutrophil granules, highlighting a reciprocal injurious mechanism. Finally, a novel peptide inhibitor of neutrophil granule release attenuates antibody-induced proteinuria in these mice and may have therapeutic potential in human GN. Thus, I describe a novel podocyte-neutrophil axis in the pathogenesis of GN and propose a potential molecular mechanism of GN involving loss of ABIN1 function resulting in excessive NF-κB activation.

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