The infrapatellar fat pad in knee osteoarthritis: An important source of interleukin‐6 and its soluble receptor
- 29 October 2009
- journal article
- research article
- Published by Wiley in Arthritis & Rheumatism
- Vol. 60 (11), 3374-3377
- https://doi.org/10.1002/art.24881
Abstract
Objective Obesity is a potent risk factor in knee osteoarthritis (OA). It has been suggested that adipokines, secreted by adipose tissue (AT) and largely found in the synovial fluid of OA patients, derive in part from the infrapatellar fat pad (IFP), also known as Hoffa's fat pad. The goal of this study was to characterize IFP tissue in obese OA patients and to compare its features with thigh subcutaneous AT to determine whether the IFP contributes to local inflammation in knee OA via production of specific cytokines. Methods IFP and subcutaneous AT samples were obtained from 11 obese women (body mass index ≥30 kg/m2) with knee femorotibial OA. Gene expression was measured by real‐time quantitative polymerase chain reaction. Cytokine concentrations in plasma and in conditioned media of cultured AT explants were determined by enzyme‐linked immunosorbent assay or by Luminex xMAP technology. Results In IFP tissue versus subcutaneous AT, there was a decrease in the expression of genes for key enzymes implicated in adipocyte lipid metabolism, whereas the expression levels of genes for AT markers remained similar. A 2‐fold increase in the expression of the gene for interleukin‐6 (IL‐6), a 2‐fold increase in the release of IL‐6, and a 3.6‐fold increase in the release of soluble IL‐6 receptor (sIL‐6R) were observed in IFP samples, compared with subcutaneous AT, but the rates of secretion of other cytokines in IFP samples were similar to the rates in subcutaneous AT. In addition, leptin secretion was decreased by 40%, whereas adiponectin secretion was increased by 70%, in IFP samples versus subcutaneous AT. Conclusion Our results indicate that the IFP cytokine profile typically found in OA patients could play a role in paracrine inflammation via the local production of IL‐6/sIL‐6R and that such a profile might contribute to damage in adjacent cartilage.Keywords
This publication has 13 references indexed in Scilit:
- Adipocyte metabolism and obesityJournal of Lipid Research, 2009
- A new player in cartilage homeostasis: adiponectin induces nitric oxide synthase type II and pro-inflammatory cytokines in chondrocytesOsteoarthritis and Cartilage, 2008
- A giant extrasynovial osteochondroma in the infrapatellar fat pad: end stage Hoffa’s diseaseArchives of orthopaedic and trauma surgery, 2007
- Obesity and osteoarthritis: more complex than predicted!Annals Of The Rheumatic Diseases, 2006
- Adipose Tissue-Derived Factors: Impact on Health and DiseaseEndocrine Reviews, 2006
- Differential distribution of adipokines between serum and synovial fluid in patients with osteoarthritis. Contribution of joint tissues to their articular productionOsteoarthritis and Cartilage, 2006
- Leptin, from fat to inflammation: old questions and new insightsFEBS Letters, 2004
- Natural vs Vaccine-Acquired Immunity to Cytomegalovirus—ReplyJAMA, 2003
- Cytokine production in the infrapatellar fat pad: another source of cytokines in knee synovial fluidsAnnals Of The Rheumatic Diseases, 2003
- Radiological Assessment of Osteo-ArthrosisAnnals Of The Rheumatic Diseases, 1957