Human Autoantibodies in Anti-GBM Disease

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DESCRIPTION (provided by applicant):Anti glomerular basement membrane (GBM) disease is an autoimmune disease mediated by antibodies against the GBM. The usual clinical picture is rapidly progressive glomerulonephritis (RPGN) resulting in end stage renal disease. These patients consequently suffer a significant reduction in quality of life, due to life-long need for renal replacement therapy. While significant knowledge currently exist about the structural basis of the antigen (Ag) of human anti-GBM disease, alpha3(IV) NCI collagen (alpha3(IV)); the pathogenesis of this autoimmune disease has yet to be fully elucidated. Although putative antigenic epitopes have been identified, little is known about the origin, structure and conformation of pathogenic human anti-GBM antibodies (Ab) that recognize these epitopes.The studies proposed here seek to identify how autoantibodies against alpha3(IV) initiate nephritis through binding to the GBM. Using the XenoMouseII (XMII) model of human anti-GBM disease that has been developed in our laboratory, I propose to generate human monoclonal antibodies (mAb), directed towards 2 putatively pathogenically relevant epitopes on Antibodies against the GBM. The usual clinical picture is rapidly progressive glomerulonephritis (RPGN) resulting in end stage renal disease. These patients consequently suffer a significant reduction in quality of life, due to life-long need for renal replacement therapy. While significant knowledge currently exist about the structural basis of the antigen (Ag) of human anti-GBM disease, alpha3(IV) NCI collagen (alpha3(IV)); the pathogenesis of this autoimmune disease has yet to be fully elucidated. Although putative antigenic epitopes have been identified, little is known about the origin, structure and conformation of pathogenic human anti-GBM antibodies (Ab) that recognize these epitopes. The studies proposed here seek to identify how autoantibodies against alpha3(IV) initiate nephritis through binding to the GBM. Using the XenoMouseII (XMII) model of human anti-GBM disease that has been developed in our laboratory, I propose to generate human monoclonal antibodies (mAb), directed towards 2 putatively pathogenically relevant epitopes on alpha3(IV) (Aim 1). The specificity and affinity with which these mAb bind alpha3(IV) in vitro will be determined (Aim 2), and correlated to their pathogenicity (Aim 3). Sequencing of the hypervariable region of the pathogenic mAb will allow prediction of the 3-dimensional structure of the Ag-binding region. Subsequently, this information should enable me to determine which amino acid residues in the hypervariable region are essential for the interaction with alpha3(IV) (Aim 2) and the disease producing autoAb (Aim 3). These studies should help provide insights into the basic pathophysiology of anti-GBM disease. Additionally, these results may aide in the design and evaluation of effective therapies (e.g., small molecules) for treatment of this devastating disease, in the future.The K08 mechanism will enable me to undertake mentored research training in basic immunology and the pathogenesis of autoimmune glomerulonephritis. These studies will be conducted in Dr. Michael P. Madaio's laboratory at the University of Pennsylvania. The training and studies will greatly facilitate my career goals of working as a physician/scientist in an academic setting.