title: Knee and hip intra-articular adipose tissues (IAATs) compared with autologous subcutaneous adipose tissue: a specific phenotype for a central player in osteoarthritis.
abstract: OBJECTIVE
  Compared with subcutaneous adipose tissue (SCAT), infrapatellar fat pad (IFP), the main knee intra-articular adipose tissue (IAAT), has an inflammatory phenotype in patients with osteoarthritis (OA). We phenotyped suprapatellar fat pad (SPFP) and hip acetabular fat pad (AFP), two other IAATs, to determinate the unique signature of IAATs compared with SCAT.
  
  
  METHODS
  IFP, SPFP, AFP and autologous SCAT were obtained from patients with OA during total knee (n=38) or hip replacement (n=5). Fibrosis and adipocyte area were analysed by histology and vascularisation, leucocyte and mast cell infiltration were analysed by immunohistochemistry for von Willebrand factor, leucocytes and tryptase, respectively. Secretion of interleukin (IL)-6, IL-8 and prostaglandin E2(PGE2) was assessed by ELISA. The mRNA expression of adipocyte-associated genes (ATGL, LPL, PPAR-γ, FABP4 and CD36) and developmental genes (SFRP2, HoxC9 and EN1) was determined. The inflammatory response of isolated fibroblast-like synoviocytes (FLS) to autologous IFP and SPFP conditioned media was examined.
  
  
  RESULTS
  Fibrosis, vascularisation and leucocyte and mast cell infiltration were greater in IAATs than SCAT, and levels of IL-6, IL-8 and PGE2were greater in all IAATs than SCAT. IFP and SPFP induced a similar inflammatory response to FLS. Adipocyte area was smaller in IAATs than SCAT. Adipocyte-associated and developmental genes showed a similar gene expression pattern in all IAATs, different from SCAT.
  
  
  CONCLUSIONS
  IFP but also SPFP and AFP (gathered under the term 'IAAT') may play a deleterious role in OA by affecting joint homeostasis because of their inflammatory phenotype and their close interaction with synovium in the same functional unit.
authors.affiliation: INSERM, Sorbonne University, UPMC Univ Paris 06, Centre de Recherche Saint-Antoine (CRSA), Paris, France.|Department of Rheumatology, AP-HP Henri Mondor Hospital, Créteil Cedex, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Eymard
authors.affiliation: INSERM, Sorbonne University, UPMC Univ Paris 06, Centre de Recherche Saint-Antoine (CRSA), Paris, France.
authors.forename: Audrey
authors.initials: A
authors.lastname: Pigenet
authors.affiliation: INSERM, Sorbonne University, UPMC Univ Paris 06, Centre de Recherche Saint-Antoine (CRSA), Paris, France.
authors.forename: Danièle
authors.initials: D
authors.lastname: Citadelle
authors.affiliation: INSERM UMR_S1166, Sorbonne University, UPMC Univ Paris 06, Pitié-Salpêtrière Hospital, Paris, France.|Institute of Cardiometabolism and Nutrition, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France.
authors.forename: Joan
authors.initials: J
authors.lastname: Tordjman
authors.affiliation: INSERM, Sorbonne University, UPMC Univ Paris 06, Centre de Recherche Saint-Antoine (CRSA), Paris, France.
authors.forename: Louise
authors.initials: L
authors.lastname: Foucher
authors.affiliation: INSERM, Sorbonne University, UPMC Univ Paris 06, Centre de Recherche Saint-Antoine (CRSA), Paris, France.
authors.forename: Cindy
authors.initials: C
authors.lastname: Rose
authors.affiliation: Department of Orthopedic Surgery, AP-HP Henri Mondor Hospital, Créteil Cedex, France.
authors.forename: Charles-Henri
authors.initials: CH
authors.lastname: Flouzat Lachaniette
authors.affiliation: INSERM UMR_S1166, Sorbonne University, UPMC Univ Paris 06, Pitié-Salpêtrière Hospital, Paris, France.|Institute of Cardiometabolism and Nutrition, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France.
authors.forename: Christine
authors.initials: C
authors.lastname: Rouault
authors.affiliation: INSERM UMR_S1166, Sorbonne University, UPMC Univ Paris 06, Pitié-Salpêtrière Hospital, Paris, France.|Institute of Cardiometabolism and Nutrition, Assistance Publique-Hôpitaux de Paris, Pitié-Salpêtrière Hospital, Paris, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Clément
authors.affiliation: INSERM, Sorbonne University, UPMC Univ Paris 06, Centre de Recherche Saint-Antoine (CRSA), Paris, France.|Department of Rheumatology, AP-HP Henri Mondor Hospital, Créteil Cedex, France.|Department of Rheumatology, Inflammation-Immunopathology-Biotherapy Department (DHU i2B), AP-HP Saint-Antoine Hospital, Paris, France.
authors.forename: Francis
authors.initials: F
authors.lastname: Berenbaum
authors.affiliation: Department of Rheumatology, AP-HP Henri Mondor Hospital, Créteil Cedex, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Chevalier
authors.affiliation: INSERM, Sorbonne University, UPMC Univ Paris 06, Centre de Recherche Saint-Antoine (CRSA), Paris, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Houard
mesh_terms: D017667:Adipocytes / Q000378:metabolism / Q000473:pathology; D000273:Adipose Tissue / Q000378:metabolism* / Q000473:pathology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D018955:CD36 Antigens / Q000235:genetics; D017077:Culture Media, Conditioned / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism; D050556:Fatty Acid-Binding Proteins / Q000235:genetics; D005260:Female; D015870:Gene Expression; D006621:Hip Joint; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D007719:Knee Joint; D008049:Lipase / Q000235:genetics; D008071:Lipoprotein Lipase / Q000235:genetics; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000235:genetics / Q000378:metabolism*; D020370:Osteoarthritis, Knee / Q000235:genetics / Q000378:metabolism*; D047495:PPAR gamma / Q000235:genetics; D010641:Phenotype; D012333:RNA, Messenger / Q000378:metabolism*; D050151:Subcutaneous Fat / Q000378:metabolism / Q000473:pathology; D000070918:Synoviocytes / Q000187:drug effects; D055815:Young Adult; D000094742:Secreted Frizzled-Related Proteins; D000217:Acyltransferases
chemical_list: D018955:CD36 Antigens; D017077:Culture Media, Conditioned; D015232:Dinoprostone; D050556:Fatty Acid-Binding Proteins; D018398:Homeodomain Proteins; D015850:Interleukin-6; D016209:Interleukin-8; D008049:Lipase; D008071:Lipoprotein Lipase; D008565:Membrane Proteins; D047495:PPAR gamma; D012333:RNA, Messenger; C513076:EN1 protein, human; C493410:FABP4 protein, human; C522807:Hoxc9 protein, human; C109618:SFRP2 protein, human; D000094742:Secreted Frizzled-Related Proteins; C494794:PNPLA2 protein, human; D000217:Acyltransferases; C548261:LPL protein, human
keywords: Inflammation; Osteoarthritis; Synovitis