title: Inflammatory and Metabolic Alterations of Kager's Fat Pad in Chronic Achilles Tendinopathy.
abstract: BACKGROUND
  Achilles tendinopathy is a painful inflammatory condition characterized by swelling, stiffness and reduced function of the Achilles tendon. Kager's fat pad is an adipose tissue located in the area anterior to the Achilles tendon. Observations reveal a close physical interplay between Kager's fat pad and its surrounding structures during movement of the ankle, suggesting that Kager's fat pad may stabilize and protect the mechanical function of the ankle joint.
  
  
  OBJECTIVE
  The aim of this study was to characterize whether Achilles tendinopathy was accompanied by changes in expression of inflammatory markers and metabolic enzymes in Kager's fat pad.
  
  
  METHODS
  A biopsy was taken from Kager's fat pad from 31 patients with chronic Achilles tendinopathy and from 13 healthy individuals. Gene expression was measured by reverse transcription-quantitative PCR. Focus was on genes related to inflammation and lipid metabolism.
  
  
  RESULTS
  Expression of the majority of analyzed inflammatory marker genes was increased in patients with Achilles tendinopathy compared to that in healthy controls. Expression patterns of the patient group were consistent with reduced lipolysis and increased fatty acid β-oxidation. In the fat pad, the pain-signaling neuropeptide substance P was found to be present in one third of the subjects in the Achilles tendinopathy group but in none of the healthy controls.
  
  
  CONCLUSIONS
  Gene expression changes in Achilles tendinopathy patient samples were consistent with Kager's fat pad being more inflamed than in the healthy control group. Additionally, the results indicate an altered lipid metabolism in Kager's fat pad of Achilles tendinopathy patients.
authors.affiliation: Department of Exercise and Nutrition, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jessica
authors.initials: J
authors.lastname: Pingel
authors.affiliation: Department of Biology, University of Copenhagen, Copenhagen, Denmark; Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: M Christine H
authors.initials: MC
authors.lastname: Petersen
authors.affiliation: Diagnostic Centre, Silkeborg Regional Hospital, Silkeborg, Denmark.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Fredberg
authors.affiliation: Diagnostic Centre, Silkeborg Regional Hospital, Silkeborg, Denmark.
authors.forename: Søren G
authors.initials: SG
authors.lastname: Kjær
authors.affiliation: Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Quistorff
authors.affiliation: CopenRehab, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Henning
authors.initials: H
authors.lastname: Langberg
authors.affiliation: Department of Biology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jacob B
authors.initials: JB
authors.lastname: Hansen
mesh_terms: D000125:Achilles Tendon / Q000378:metabolism* / Q000473:pathology*; D000273:Adipose Tissue / Q000378:metabolism* / Q000473:pathology*; D000328:Adult; D015415:Biomarkers; D001706:Biopsy; D016022:Case-Control Studies; D002908:Chronic Disease; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004734:Energy Metabolism; D005260:Female; D015870:Gene Expression; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D052256:Tendinopathy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D016207:Cytokines; D018836:Inflammation Mediators