title: Inflammation Drives Retraction, Stiffening, and Nodule Formation via Cytoskeletal Machinery in a Three-Dimensional Culture Model of Aortic Stenosis.
abstract: In calcific aortic valve disease, the valve cusps undergo retraction, stiffening, and nodular calcification. The inflammatory cytokine, tumor necrosis factor (TNF)-α, contributes to valve disease progression; however, the mechanisms of its actions on cusp retraction and stiffening are unclear. We investigated effects of TNF-α on murine aortic valvular interstitial cells (VICs) within three-dimensional, free-floating, compliant, collagen hydrogels, simulating their natural substrate and biomechanics. TNF-α increased retraction (percentage of diameter), stiffness, and formation of macroscopic, nodular structures with calcification in the VIC-laden hydrogels. The effects of TNF-α were attenuated by blebbistatin inhibition of myosin II-mediated cytoskeletal contraction. Inhibition of actin polymerization with cytochalasin-D, but not inhibition of Rho kinase with Y27632, blocked TNF-α-induced retraction in three-dimensional VIC hydrogels, suggesting that actin stress fibers mediate TNF-α-induced effects. In the hydrogels, inhibitors of NF-κB blocked TNF-α-induced retraction, whereas simultaneous inhibition of c-Jun N-terminal kinase was required to block TNF-α-induced stiffness. TNF-α also significantly increased collagen deposition, as visualized by Masson's trichrome staining, and up-regulated mRNA expression of discoidin domain receptor tyrosine kinase 2, fibronectin, and α-smooth muscle actin. In human aortic valves, calcified cusps were stiffer and had more collagen deposition than noncalcified cusps. These findings suggest that inflammation, through stimulation of cytoskeletal contractile activity, may be responsible for valvular cusp retraction, stiffening, and formation of calcified nodules.
authors.affiliation: Department of Pediatrics, University of California, Los Angeles, Los Angeles, California.
authors.forename: Jina
authors.initials: J
authors.lastname: Lim
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, Los Angeles, California.
authors.forename: Arshia
authors.initials: A
authors.lastname: Ehsanipour
authors.affiliation: Department of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Hsu
authors.affiliation: Department of Physiology, University of California, Los Angeles, Los Angeles, California.
authors.forename: Jinxiu
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Taylor
authors.initials: T
authors.lastname: Pedego
authors.affiliation: Department of Medicine, University of California, Los Angeles, Los Angeles, California.
authors.forename: Alexander
authors.initials: A
authors.lastname: Wu
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, Los Angeles, California.
authors.forename: Chris M
authors.initials: CM
authors.lastname: Walthers
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, Los Angeles, California; Department of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Physiology, University of California, Los Angeles, Los Angeles, California.
authors.forename: Linda L
authors.initials: LL
authors.lastname: Demer
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, Los Angeles, California.
authors.forename: Stephanie K
authors.initials: SK
authors.lastname: Seidlits
authors.affiliation: Department of Medicine, University of California, Los Angeles, Los Angeles, California; Department of Physiology, University of California, Los Angeles, Los Angeles, California; Department of Orthopaedic Surgery, University of California, Los Angeles, Los Angeles, California. Electronic address: ytintut@mednet.ucla.edu.
authors.forename: Yin
authors.initials: Y
authors.lastname: Tintut
mesh_terms: D000818:Animals; D001021:Aortic Valve / Q000473:pathology*; D001024:Aortic Valve Stenosis / Q000473:pathology*; D015153:Blotting, Western; D002114:Calcinosis / Q000473:pathology*; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000473:pathology*; D004195:Disease Models, Animal; D005455:Fluorescent Antibody Technique; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007249:Inflammation / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D060888:Real-Time Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology
chemical_list: D014409:Tumor Necrosis Factor-alpha; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate