The Distinct Expressions of Integrins αDβ2 and αMβ2 Differently Regulate Macrophage Migration in 3D Matrix in vitro and in Tissue during Inflammation

Author

Kui Cui, East Tennessee State UniversityFollow

Degree Name

PhD (Doctor of Philosophy)

Program

Biomedical Sciences

Date of Award

8-2019

Committee Chair or Co-Chairs

Valentin Yakubenko

Committee Members

Donald B. Hoover, Meng-yang Zhu, Diego J. Rodriguez Gil, Chuanfu Li

Abstract

Chronic inflammation is an essential mechanism during the development of cardiovascular and metabolic diseases. The outcome of diseases depends on the balance between the migration and accumulation of macrophages in damaged tissues. Macrophage motility is highly regulated by adhesive receptors, integrins. Namely, intermediate expression of integrin supports macrophage migration, while a high integrin density inhibits it. Our studies are focused on evaluation of the contribution of related integrins α_Dβ₂ and α_Mβ₂ to macrophage migration and development of chronic inflammation.

We found that integrin α_Dβ₂ is upregulated on M1-macrophages in vitro and pro-inflammatory macrophages in atherosclerotic lesions. Interestingly, the expression of ligand-sharing integrin α_Mβ₂ remains unaltered. Using in vitro three-dimensional migration and in vivo tracking of adoptively-transferred fluorescently-labeled macrophages during the resolution of inflammation, we found that robust adhesion of M1-activated macrophages translates to weak 3D migration, which depends on the high expression of α_Dβ₂, since α_D-deficiency decreases M1-macrophage adhesion and improves macrophage migration. In contrast, α_D- and α_M-knockouts decrease M2-macrophages migration, demonstrating that moderate integrin expression supports cell motility. In model of high fat diet-induced diabetes, α_D-deficiency prevents the retention of inflammatory macrophages in adipose tissue and improves metabolic parameters, while α_M-deficiency does not affect macrophage accumulation.

We detected a new ligand for integrins α_Mβ₂ and α_Dβ₂, 2-(ω-carboxyethyl)pyrrole (CEP). CEP is preferentially generated during inflammation-mediated oxidation and forms adduct with ECM proteins generating novel substrate for α_Mβ₂ and α_Dβ_2. Targeting CEP-dependent macrophage adhesion can be a useful approach to control α_Dβ₂-mediated chronic inflammation.

Using specially designed peptide library, protein-protein interaction and adhesion assay, we identified a peptide, called P5, which significantly inhibited α_D-CEP binding. P5 peptide regulates macrophage migration in three-dimensional matrix in vitro and reduced macrophage accumulation during thioglycollate-induced peritoneal inflammation. Effect of P5 is completely eliminated in α_D-deficient macrophages. Tracking of adoptively-transferred fluorescently-labeled WT and α_D^-/- monocytes in diabetic mice confirmed that α_D-dependent inhibition of macrophage accumulation in adipose tissue is mediated by P5 peptide.

Taken together, these results demonstrate the importance of α_Dβ₂ and α_Dβ₂-CEP interaction for the accumulation of infiltrating macrophages during inflammation and propose P5 peptide as a potential inhibitor of atherogenesis and diabetes.

Document Type

Dissertation - unrestricted

Recommended Citation

Cui, Kui, "The Distinct Expressions of Integrins αDβ2 and αMβ2 Differently Regulate Macrophage Migration in 3D Matrix in vitro and in Tissue during Inflammation" (2019). Electronic Theses and Dissertations. Paper 3614. https://dc.etsu.edu/etd/3614

Copyright

Copyright by the authors.