Recent work has shown that activation of the alternative pathway of complement is central to the pathogenesis of a large number of glomerular and tubulointerstitial renal diseases. It is not known, however, why the kidney is so frequently and uniquely vulnerable to alternative pathway-mediated injury. The central hypothesis of this grant is that the plasma protein factor H is critical for controlling alternativ pathway activation on the glomerular basement membrane and the surface of injured mesangial cells and tubular epithelial cells. Complement regulation within the kidney by factor H is disrupted by the local production of proteins that impair factor H function and by complement-activating microparticles shed by injured cells throughout the body. To test this hypothesis, the following specific aims will be pursued.
Aim 1) Determine which regulatory proteins control complement activation in the kidney. The working hypothesis for this aim is that factor H prevents spontaneous complement activation on the GBM and on injured mesangial and tubular epithelial cells. We will use in vitro and in vivo methods to determine which renal surfaces require factor H to prevent complement-mediated injury. We will use targeted complement inhibitors to restore factor H to sites of complement activation within the kidney.
Aim 2) Determine how the protein annexin A2 modulates complement regulation by factor H within the kidney. The working hypothesis for this aim is that annexin A2 expressed within the injured kidney blocks factor H function, thus permitting local activation of the alternative pathway. The experiments in this aim will utilize recombinant annexin A2, SiRNA, and mice with targeted deletion of the gene for annexin A2 in order to determine how annexin A2 promotes complement activation on the surface of cells of the kidney in vitro and in vivo.
Aim 3) Determine whether plasma microparticles impair complement regulation within the kidney. The working hypothesis of this aim is that microparticles shed from injured endothelial cells cause complement activation within the kidney. These experiments will utilize cyclosporine to generate endothelial microparticles and test whether they cause injury in factor H deficient mice. Cyclosporine-induced microparticles will be injected into factor H deficient mice to determine whether the microparticles directly increase alternative pathway activation and cause renal injury. Finally, we will test whether CR2-factor H, a targeted complement inhibitor, prevents cyclosporine-induced vascular and renal toxicity in factor H deficient mice. The approach outlined above is innovative because it challenges the current understanding of how factor H controls complement activation on tissues and it provides an explanation for why the kidney, among all of the organs, is so uniquely susceptible to alternative pathway-mediated injury. The studies in this grant are significant because they examine a process central to the pathogenesis of a wide range of renal diseases and provide new treatment strategies for these diseases.

Public Health Relevance

The proposed research is relevant to public health because activation of the complement system contributes to renal injury in a wide range of renal diseases. Standard immunosuppressive drugs are not effective at preventing injury by the complement system. The therapeutic agents tested in these experiments may offer an important new approach to treating renal disease.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
2R01DK076690-06A1
Application #
8636168
Study Section
Pathobiology of Kidney Disease Study Section (PBKD)
Program Officer
Kimmel, Paul
Project Start
2006-12-01
Project End
2018-06-30
Budget Start
2013-09-18
Budget End
2014-06-30
Support Year
6
Fiscal Year
2013
Total Cost
$336,038
Indirect Cost
$118,538
Name
University of Colorado Denver
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
041096314
City
Aurora
State
CO
Country
United States
Zip Code
80045
Tomlinson, Stephen; Thurman, Joshua M (2018) Tissue-targeted complement therapeutics. Mol Immunol 102:120-128
Goetz, Lindsey; Laskowski, Jennifer; Renner, Brandon et al. (2018) Complement factor H protects mice from ischemic acute kidney injury but is not critical for controlling complement activation by glomerular IgM. Eur J Immunol 48:791-802
Luo, Wentian; Olaru, Florina; Miner, Jeffrey H et al. (2018) Alternative Pathway Is Essential for Glomerular Complement Activation and Proteinuria in a Mouse Model of Membranous Nephropathy. Front Immunol 9:1433
Klawitter, Jelena; Pennington, Alexander; Klawitter, Jost et al. (2017) Mitochondrial cyclophilin D ablation is associated with the activation of Akt/p70S6K pathway in the mouse kidney. Sci Rep 7:10540
Rubtsova, Kira; Rubtsov, Anatoly V; Thurman, Joshua M et al. (2017) B cells expressing the transcription factor T-bet drive lupus-like autoimmunity. J Clin Invest 127:1392-1404
Casiraghi, F; Azzollini, N; Todeschini, M et al. (2017) Complement Alternative Pathway Deficiency in Recipients Protects Kidney Allograft From Ischemia/Reperfusion Injury and Alloreactive T Cell Response. Am J Transplant 17:2312-2325
Thurman, Joshua M; Frazer-Abel, Ashley; Holers, V Michael (2017) The Evolving Landscape for Complement Therapeutics in Rheumatic and Autoimmune Diseases. Arthritis Rheumatol 69:2102-2113
Thurman, Joshua M (2017) Getting over our Immune-Complex - C5a receptor blockade is the answer. Cell Mol Immunol 14:319-320
Li, Dan; Zou, Lin; Feng, Yan et al. (2016) Complement Factor B Production in Renal Tubular Cells and Its Role in Sodium Transporter Expression During Polymicrobial Sepsis. Crit Care Med 44:e289-99
Thurman, Joshua M; Nester, Carla M (2016) All Things Complement. Clin J Am Soc Nephrol 11:1856-1866

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