title: Strain-dependent oxidant release in articular cartilage originates from mitochondria.
abstract: Mechanical loading is essential for articular cartilage homeostasis and plays a central role in the cartilage pathology, yet the mechanotransduction processes that underlie these effects remain unclear. Previously, we showed that lethal amounts of reactive oxygen species (ROS) were liberated from the mitochondria in response to mechanical insult and that chondrocyte deformation may be a source of ROS. To this end, we hypothesized that mechanically induced mitochondrial ROS is related to the magnitude of cartilage deformation. To test this, we measured axial tissue strains in cartilage explants subjected to semi-confined compressive stresses of 0, 0.05, 0.1, 0.25, 0.5, or 1.0 MPa. The presence of ROS was then determined by confocal imaging with dihydroethidium, an oxidant sensitive fluorescent probe. Our results indicated that ROS levels increased linearly relative to the magnitude of axial strains (r(2) = 0.87, p < 0.05), and significant cell death was observed at strains >40%. By contrast, hydrostatic stress, which causes minimal tissue strain, had no significant effect. Cell-permeable superoxide dismutase mimetic Mn(III)tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride significantly decreased ROS levels at 0.5 and 0.25 MPa. Electron transport chain inhibitor, rotenone, and cytoskeletal inhibitor, cytochalasin B, significantly decreased ROS levels at 0.25 MPa. Our findings strongly suggest that ROS and mitochondrial oxidants contribute to cartilage mechanobiology.
authors.affiliation: Ignacio Ponseti Orthopaedic Cell Biology Lab, Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA, marc-brouillette@uiowa.edu.
authors.forename: M J
authors.initials: MJ
authors.lastname: Brouillette
authors.forename: P S
authors.initials: PS
authors.lastname: Ramakrishnan
authors.forename: V M
authors.initials: VM
authors.lastname: Wagner
authors.forename: E E
authors.initials: EE
authors.lastname: Sauter
authors.forename: B J
authors.initials: BJ
authors.lastname: Journot
authors.forename: T O
authors.initials: TO
authors.lastname: McKinley
authors.forename: J A
authors.initials: JA
authors.lastname: Martin
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D002417:Cattle; D003571:Cytochalasin B / Q000494:pharmacology; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012402:Rotenone / Q000494:pharmacology; D013314:Stress, Mechanical
chemical_list: D005456:Fluorescent Dyes; D016877:Oxidants; D017382:Reactive Oxygen Species; D012402:Rotenone; D003571:Cytochalasin B
references.citation: Mol Cell Biol. 2007 Aug;27(16):5737-45
references.pmid: 17562866
references.citation: Biomech Model Mechanobiol. 2007 Jan;6(1-2):103-11
references.pmid: 16821016
references.citation: Ann Biomed Eng. 1996 Jul-Aug;24(4):500-12
references.pmid: 8841725
references.citation: J Biomech. 2008 Aug 7;41(11):2430-7
references.pmid: 18619596
references.citation: Trends Biochem Sci. 2010 Sep;35(9):505-13
references.pmid: 20430626
references.citation: Bone. 2003 Jul;33(1):1-13
references.pmid: 12919695
references.citation: Nat Rev Rheumatol. 2011 Mar;7(3):161-9
references.pmid: 21200395
references.citation: J Biomech. 1998 May;31(5):445-51
references.pmid: 9727342
references.citation: Arthritis Rheum. 2002 Dec;46(12):3190-200
references.pmid: 12483723
references.citation: J Biol Chem. 1955 Nov;217(1):383-93
references.pmid: 13271402
references.citation: J Cell Sci. 1998 Mar;111 ( Pt 5):573-83
references.pmid: 9454731
references.citation: FASEB J. 2010 Aug;24(8):2938-50
references.pmid: 20335224
references.citation: Cell Death Differ. 2008 Apr;15(4):621-7
references.pmid: 18259201
references.citation: Biomech Model Mechanobiol. 2006 Jun;5(2-3):123-32
references.pmid: 16506016
references.citation: Free Radic Res. 2007 Jun;41(6):699-712
references.pmid: 17516243
references.citation: Biomech Model Mechanobiol. 2006 Jun;5(2-3):180-91
references.pmid: 16520962
references.citation: J Bioenerg Biomembr. 2011 Dec;43(6):663-71
references.pmid: 21986957
references.citation: Arch Biochem Biophys. 1996 Jan 1;325(1):20-8
references.pmid: 8554339
references.citation: J Orthop Res. 2004 Jan;22(1):131-9
references.pmid: 14656671
references.citation: Arthritis Rheum. 2008 Aug;58(8):2409-19
references.pmid: 18668543
references.citation: J Biomech. 2001 Nov;34(11):1463-9
references.pmid: 11672721
references.citation: Proc Inst Mech Eng H. 2011 Oct;225(10):993-1002
references.pmid: 22204121
references.citation: Osteoarthritis Cartilage. 2010 Jul;18(7):909-16
references.pmid: 20434573
references.citation: Arthritis Rheum. 2004 Dec;50(12):3915-24
references.pmid: 15593204
references.citation: Arch Biochem Biophys. 2011 Mar 15;507(2):350-5
references.pmid: 21211511
references.citation: J Rheumatol. 2007 Mar;34(3):556-62
references.pmid: 17309123
references.citation: Mol Cell Proteomics. 2009 Jul;8(7):1475-89
references.pmid: 19196708
references.citation: J Bone Joint Surg Am. 2009 Aug;91(8):1890-7
references.pmid: 19651946
references.citation: Biochem J. 1997 Jan 1;321 ( Pt 1):95-102
references.pmid: 9003406
references.citation: Osteoarthritis Cartilage. 2012 Apr;20(4):323-9
references.pmid: 22305999
references.citation: J Anat. 1991 Apr;175:251-61
references.pmid: 2050570
references.citation: J Anat. 1999 Apr;194 ( Pt 3):343-53
references.pmid: 10386772
references.citation: J Orthop Res. 2012 Apr;30(4):593-8
references.pmid: 21928429
references.citation: J Orthop Res. 2013 Feb;31(2):191-6
references.pmid: 22930474
references.citation: Z Rheumatol. 1991 Sep-Oct;50(5):304-12
references.pmid: 1776367
references.citation: Dev Cell. 2006 Jan;10(1):11-20
references.pmid: 16399074
references.citation: Rheumatology (Oxford). 2008 Nov;47(11):1622-7
references.pmid: 18775967
references.citation: J Orthop Res. 2010 Aug;28(8):1057-63
references.pmid: 20108345
references.citation: J Orthop Res. 2010 Jul;28(7):914-20
references.pmid: 20058262