title: Basement membrane stiffening promotes retinal endothelial activation associated with diabetes.
abstract: Endothelial activation is a hallmark of the high-glucose (HG)-induced retinal inflammation associated with diabetic retinopathy (DR). However, precisely how HG induces retinal endothelial activation is not fully understood. We hypothesized that HG-induced up-regulation of lysyl oxidase (LOX), a collagen-cross-linking enzyme, in retinal capillary endothelial cells (ECs) enhances subendothelial basement membrane (BM) stiffness, which, in turn, promotes retinal EC activation. Diabetic C57BL/6 mice exhibiting a 70 and 50% increase in retinal intercellular adhesion molecule (ICAM)-1 expression and leukocyte accumulation, respectively, demonstrated a 2-fold increase in the levels of BM collagen IV and LOX, key determinants of capillary BM stiffness. Using atomic force microscopy, we confirmed that HG significantly enhances LOX-dependent subendothelial matrix stiffness in vitro, which correlated with an ∼2.5-fold increase in endothelial ICAM-1 expression, a 4-fold greater monocyte-EC adhesion, and an ∼2-fold alteration in endothelial NO (decrease) and NF-κB activation (increase). Inhibition of LOX-dependent subendothelial matrix stiffening alone suppressed HG-induced retinal EC activation. Finally, using synthetic matrices of tunable stiffness, we demonstrated that subendothelial matrix stiffening is necessary and sufficient to promote EC activation. These findings implicate BM stiffening as a critical determinant of HG-induced retinal EC activation and provide a rationale for examining BM stiffness and underlying mechanotransduction pathways as therapeutic targets for diabetic retinopathy.
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yang
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Harry A
authors.initials: HA
authors.lastname: Scott
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Finny
authors.initials: F
authors.lastname: Monickaraj
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Soroush
authors.initials: S
authors.lastname: Ardekani
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Carolina F
authors.initials: CF
authors.lastname: Nitta
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cabrera
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Paul G
authors.initials: PG
authors.lastname: McGuire
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Umar
authors.initials: U
authors.lastname: Mohideen
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA.
authors.forename: Arup
authors.initials: A
authors.lastname: Das
authors.affiliation: *Department of Bioengineering and Department of Physics and Astronomy, University of California, Riverside, Riverside, California, USA; Department of Surgery and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico, USA; and New Mexico Veterans Affairs Health Care System, Albuquerque, New Mexico, USA kghosh@engr.ucr.edu.
authors.forename: Kaustabh
authors.initials: K
authors.lastname: Ghosh
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000473:pathology*; D002460:Cell Line; D003921:Diabetes Mellitus, Experimental / Q000150:complications*; D003930:Diabetic Retinopathy / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D042783:Endothelial Cells / Q000378:metabolism; D004727:Endothelium / Q000473:pathology*; D005786:Gene Expression Regulation / Q000502:physiology; D000882:Haplorhini; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes; D008249:Protein-Lysine 6-Oxidase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000473:pathology*
chemical_list: D008249:Protein-Lysine 6-Oxidase
keywords: diabetic retinopathy; inflammation; lysyl oxidase; matrix stiffness; nitric oxide