title: Cyclic loading of tendon fascicles using a novel fatigue loading system increases interleukin-6 expression by tenocytes.
abstract: Repetitive strain or 'overuse' is thought to be a major factor contributing to the development of tendinopathy. The aims of our study were to develop a novel cyclic loading system, and use it to investigate the effect of defined loading conditions on the mechanical properties and gene expression of isolated tendon fascicles. Tendon fascicles were dissected from bovine-foot extensors and subjected to cyclic tensile strain (1 Hz) at 30% or 60% of the strain at failure, for 0 h (control), 15 min, 30 min, 1 h, or 5 h. Post loading, a quasi-static test to failure assessed damage. Gene expression at a selected loading regime (1 h at 30% failure strain) was analyzed 6 h post loading by quantitative real-time polymerase chain reaction. Compared with unloaded controls, loading at 30% failure strain took 5 h to lead to a significant decrease in failure stress, whereas loading to 60% led to a significant reduction after 15 min. Loading for 1 h at 30% failure strain did not create significant structural damage, but increased Collagen-1-alpha-chain-1 and interleukin-6 (IL6) expression, suggesting a role of IL6 in tendon adaptation to exercise. Correlating failure properties with fatigue damage provides a method by which changes in gene expression can be associated with different degrees of fatigue damage.
authors.affiliation: School of Biological Sciences, University of East Anglia, Norwich, UK. k.legerlotz@uea.ac.uk
authors.forename: K
authors.initials: K
authors.lastname: Legerlotz
authors.forename: G C
authors.initials: GC
authors.lastname: Jones
authors.forename: H R C
authors.initials: HR
authors.lastname: Screen
authors.forename: G P
authors.initials: GP
authors.lastname: Riley
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D003094:Collagen / Q000096:biosynthesis; D005205:Fascia / Q000378:metabolism; D005528:Foot; D005786:Gene Expression Regulation; D015850:Interleukin-6 / Q000378:metabolism*; D008297:Male; D013314:Stress, Mechanical; D052256:Tendinopathy / Q000378:metabolism*; D013710:Tendons / Q000378:metabolism; D013718:Tensile Strength
chemical_list: D015850:Interleukin-6; D003094:Collagen
references.citation: Matrix Biol. 2001 Jun;20(3):159-69
references.pmid: 11420148
references.citation: Br J Rheumatol. 1995 Apr;34(4):321-5
references.pmid: 7788145
references.citation: J Physiol. 2007 Aug 1;582(Pt 3):1303-16
references.pmid: 17540706
references.citation: Rheumatology (Oxford). 2004 Feb;43(2):131-42
references.pmid: 12867575
references.citation: J Biomech. 2010 Aug 26;43(12):2274-80
references.pmid: 20483410
references.citation: Connect Tissue Res. 2003;44(3-4):128-33
references.pmid: 14504032
references.citation: J Biomech. 2005 Jan;38(1):99-105
references.pmid: 15519344
references.citation: Int J Exp Pathol. 2007 Aug;88(4):217-26
references.pmid: 17696902
references.citation: Cardiovasc Diabetol. 2010 Oct 11;9:62
references.pmid: 20937099
references.citation: J Appl Physiol (1985). 2011 Jun;110(6):1549-54
references.pmid: 21350025
references.citation: J Appl Physiol (1985). 2009 Feb;106(2):468-75
references.pmid: 19023016
references.citation: Nat Clin Pract Rheumatol. 2008 Feb;4(2):82-9
references.pmid: 18235537
references.citation: J Physiol. 2005 Sep 15;567(Pt 3):1021-33
references.pmid: 16002437
references.citation: Scand J Med Sci Sports. 2005 Aug;15(4):241-51
references.pmid: 15998341
references.citation: Am J Physiol Regul Integr Comp Physiol. 2002 Jan;282(1):R323-9
references.pmid: 11742855
references.citation: J Physiol. 1999 Nov 15;521 Pt 1:299-306
references.pmid: 10562353
references.citation: Biochem Biophys Res Commun. 2007 Oct 19;362(2):399-404
references.pmid: 17719009
references.citation: J Appl Physiol (1985). 2007 Feb;102(2):541-6
references.pmid: 16990502
references.citation: Am J Sports Med. 2007 Apr;35(4):605-11
references.pmid: 17244903
references.citation: J Appl Physiol (1985). 2007 Feb;102(2):564-72
references.pmid: 17038489
references.citation: Biochem Biophys Res Commun. 2005 Oct 21;336(2):424-9
references.pmid: 16137647
references.citation: Connect Tissue Res. 2003;44(3-4):181-7
references.pmid: 14504039
references.citation: Nat Protoc. 2008;3(6):1101-8
references.pmid: 18546601
references.citation: J Appl Physiol (1985). 2011 Jan;110(1):137-41
references.pmid: 21030675
references.citation: J Physiol. 2000 Nov 15;529 Pt 1:237-42
references.pmid: 11080265
references.citation: Arthritis Rheum. 2002 Dec;46(12):3143-50
references.pmid: 12483717
references.citation: J Physiol. 2002 Aug 1;542(Pt 3):985-90
references.pmid: 12154195
references.citation: Biochem Biophys Res Commun. 2003 Oct 17;310(2):550-4
references.pmid: 14521945
references.citation: J Orthop Res. 2009 Feb;27(2):264-273
references.pmid: 18683881
references.citation: Clin Orthop Relat Res. 2008 Jul;466(7):1555-61
references.pmid: 18470577
references.citation: J Orthop Res. 2008 Oct;26(10):1306-12
references.pmid: 18404723
references.citation: Acta Biomater. 2006 Sep;2(5):505-13
references.pmid: 16839828
references.citation: J Biomech. 2006;39(1):61-9
references.pmid: 16271588
references.citation: J Appl Physiol (1985). 2009 Feb;106(2):506-12
references.pmid: 19036888