Protein based receptor ligand interactions are universally regarded as the initiating point of immune activation. However, it is questionable if i is applicable to immune recognition of solid structures. This issue is particularly relevant in vaccine design as some of the best known adjuvants are solid crystals, such as alum and monosodium urate. Binding of particulate antigens by antigen presenting cells (APC) is a critical step in immune activation. It has been demonstrated that uric acid and alum crystals are potent adjuvants, initiating a robust adaptive immune response. However, the mechanisms of activation are unknown. Using atomic force microscopy as a tool for real time single cell activation analysis, we have collected evidence that uric acid and alum crystals can directly engage cellular membranes, with a force substantially stronger than protein based cellular contacts. Binding of particulate substances activates Syk kinase-dependent signaling in dendritic cells (DCs). These observations suggest a mechanism whereby immune cell activation can be triggered by solid structures via membrane lipid alteration without the requirement for specific cell surface receptors, and a testable hypothesis for crystal-associated inflammation and adjuvanticity. In this proposal, we extend the findings to study the signaling mechanisms involved, particularly the association between cell surface lipid sorting and downstream signal transduction, critical steps in crystal mediated immune activation, as well as how this mechanism affects antigen presentation. The outcome of this work will impact vaccine development and our understanding of crystal related diseases.

Public Health Relevance

We propose here to study how lipids in the immune cell membrane can sense solid structures like crystals and beads. This is an important topic related to vaccine development, implant research, drug delivery and inflammatory responses to air pollution. Specifically, we will study what type of signaling events follow lipid binding in respone to these solid structures and how they impact immune outcomes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI098995-04
Application #
8804240
Study Section
Vaccines Against Microbial Diseases (VMD)
Program Officer
Leitner, Wolfgang W
Project Start
2012-03-01
Project End
2017-02-28
Budget Start
2015-03-01
Budget End
2016-02-29
Support Year
4
Fiscal Year
2015
Total Cost
$208,310
Indirect Cost
$15,430
Name
University of Calgary
Department
Type
DUNS #
207663915
City
Calgary
State
AB
Country
Canada
Zip Code
T2 1-N4
Mu, Libing; Tu, Zhongyuan; Miao, Lin et al. (2018) A phosphatidylinositol 4,5-bisphosphate redistribution-based sensing mechanism initiates a phagocytosis programing. Nat Commun 9:4259
Zhang, Yifei; Rong, Hua; Zhang, Fang-Xiong et al. (2018) A Membrane Potential- and Calpain-Dependent Reversal of Caspase-1 Inhibition Regulates Canonical NLRP3 Inflammasome. Cell Rep 24:2356-2369.e5
Shu, Fei; Shi, Yan (2018) Systematic Overview of Solid Particles and Their Host Responses. Front Immunol 9:1157
Geng, Shuang; Zhong, Yiwei; Zhou, Xiaoyu et al. (2017) Induced Regulatory T Cells Superimpose Their Suppressive Capacity with Effector T Cells in Lymph Nodes via Antigen-Specific S1p1-Dependent Egress Blockage. Front Immunol 8:663
Chen, Jiahuan; Ganguly, Anutosh; Mucsi, Ashley D et al. (2017) Strong adhesion by regulatory T cells induces dendritic cell cytoskeletal polarization and contact-dependent lethargy. J Exp Med 214:327-338
Shi, Yan; Mu, Libing (2017) An expanding stage for commensal microbes in host immune regulation. Cell Mol Immunol 14:339-348
Wen, Yu-Mei; Mu, Libing; Shi, Yan (2016) Immunoregulatory functions of immune complexes in vaccine and therapy. EMBO Mol Med 8:1120-1133
Zhang, Zongde; Li, Jianjian; Zheng, Wencheng et al. (2016) Peripheral Lymphoid Volume Expansion and Maintenance Are Controlled by Gut Microbiota via RALDH+ Dendritic Cells. Immunity 44:330-42
Hari, Aswin; Ganguly, Anutosh; Mu, Libing et al. (2015) Redirecting soluble antigen for MHC class I cross-presentation during phagocytosis. Eur J Immunol 45:383-95
Hari, Aswin; Zhang, Yifei; Tu, Zhongyuan et al. (2014) Activation of NLRP3 inflammasome by crystalline structures via cell surface contact. Sci Rep 4:7281

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