The beta2 integrin CD11b/CD18, the most abundant leukocyte integrin, is normally kept in an inactive (low affinity) state on circulating neutrophils and monocytes. Exposure of these cells to agonists, such as chemokines, elicits tightly-regulated intracellular interactions with the integrin's cytoplasmic tails that switch the conformation of the integrin ectodomain into a high affinity (ligand-competent) state, a process known as inside-out activation. Active integrins allow phagocytes to leave the blood circulation into tissues, where they participate in immune clearance. When integrin regulation fails, phagocytes become too sticky, leading to subversive inflammation. Despite extensive studies, a mechanistic understanding of how the integrin is kept in a default inactive state in quiescent phagocytes is incompletely understood, despite the key role of this mechanism in ensuring host survival. In addition, the atomic structure of the full-length ectodomain in the high affinity stat is still unknown, despite the importance of defining this structure in testing current models of integrin activation and for structure-guided design and optimization of antagonists. And previous attempts to block the proinflammatory functions CD11b/CD18 lacked adequate power to demonstrate efficacy in controlled clinical settings and often targeted simultaneously the three other beta2 integrins as well, confounding interpretation of outcomes. The present application seeks to unravel the atomic structure of high affinity CD11b/CD18 ectodomain, determine the role of a novel atypical phosphatase in maintaining the default inactive state in leukocytes and assess the impact of stabilizing this inactive state with a primate-specific monoclonal antibody (that possesses a unique mechanism of action), in protection of the kidney from Delayed Graft Function, an increasingly common clinical problem with no effective therapy. Biochemical, immunochemical, genetic and structural approaches and animal models will be utilized by a multidisciplinary group of investigators to achieve these goals.

Public Health Relevance

The role of integrin CD11b/CD18 in phagocyte-mediated ischemic or immune kidney injury is established experimentally. However, how this pro-inflammatory integrin is maintained in its inactive state in resting phagocytes to prevent injury, the atomic structure it assumes in the proinflammatory state, and if therapies can be developed and successfully applied to block transition to this potentially harmful state are unanswered questions. These will be directly addressed in the proposed biochemical, crystallographic and interventional/therapeutic studies.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01DK048549-27
Application #
8681430
Study Section
Pathobiology of Kidney Disease Study Section (PBKD)
Program Officer
Bishop, Terry Rogers
Project Start
Project End
Budget Start
Budget End
Support Year
27
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
Adair, Brian D; Altintas, Mehmet M; Möller, Clemens C et al. (2014) Structure of the kidney slit diaphragm adapter protein CD2-associated protein as determined with electron microscopy. J Am Soc Nephrol 25:1465-73
Van Agthoven, Johannes F; Xiong, Jian-Ping; Alonso, José Luis et al. (2014) Structural basis for pure antagonism of integrin ?V?3 by a high-affinity form of fibronectin. Nat Struct Mol Biol 21:383-8
Palmyre, Aurélien; Lee, Jeongeun; Ryklin, Gennadiy et al. (2014) Collective epithelial migration drives kidney repair after acute injury. PLoS One 9:e101304
Adair, Brian D; Xiong, Jian-Ping; Alonso, Jose Luis et al. (2013) EM structure of the ectodomain of integrin CD11b/CD18 and localization of its ligand-binding site relative to the plasma membrane. PLoS One 8:e57951
Jones, Phillip B; Adams, Kenneth W; Rozkalne, Anete et al. (2011) Apolipoprotein E: isoform specific differences in tertiary structure and interaction with amyloid-* in human Alzheimer brain. PLoS One 6:e14586
Levy, Bruce D; Zhang, Qing-yin; Bonnans, Caroline et al. (2011) The endogenous pro-resolving mediators lipoxin A4 and resolvin E1 preserve organ function in allograft rejection. Prostaglandins Leukot Essent Fatty Acids 84:43-50
Gupta, Vineet; Alonso, Jose Luis; Sugimori, Takashi et al. (2008) Role of the beta-subunit arginine/lysine finger in integrin heterodimer formation and function. J Immunol 180:1713-8
Gupta, Vineet; Gylling, Annette; Alonso, Jose Luis et al. (2007) The beta-tail domain (betaTD) regulates physiologic ligand binding to integrin CD11b/CD18. Blood 109:3513-20
Arnaout, M Amin; Goodman, Simon L; Xiong, Jian-Ping (2007) Structure and mechanics of integrin-based cell adhesion. Curr Opin Cell Biol 19:495-507
Xiong, Jian-Ping; Goodman, Simon L; Arnaout, M Amin (2007) Purification, analysis, and crystal structure of integrins. Methods Enzymol 426:307-36

Showing the most recent 10 out of 21 publications