Department of Rheumatology, Leiden University Medical Centre, Leiden, The Netherlands.
Ann Rheum Dis. 2011 May;70(5):851-7. doi: 10.1136/ard.2010.140046. Epub 2011 Jan 17.
Obesity is a risk factor for the development of osteoarthritis (OA) in hands and knees. Adipose tissue can secrete different adipokines with powerful immunomodulatory effects. The infrapatellar fat pad (IFP) is an intra-articular organ in the vicinity of the synovium and cartilage. It is hypothesised that IFP-derived soluble factors could contribute to pathological processes in the knee joint. A study was therefore undertaken to compare the release of inflammatory mediators in the IFP and subcutaneous adipose tissue (ScAT) and to characterise the adipocytes and immune cell infiltrate in these tissues.
Paired IFP and ScAT samples were obtained from 27 patients with primary OA. The stromal vascular cell fraction (SVF) was isolated and characterised by fluorescence activated cell sorting. Cytokine and adipokine release in fat- and adipocyte-conditioned media was measured by luminex.
IFP secreted higher levels of inflammatory mediators such as interleukin 6 (IL-6), adipsin, adiponectin and visfatin than ScAT. This could be due to differences in the phenotype of adipocytes and/or in the composition and phenotype of the SVF cells. IFP adipocyte-conditioned media showed a trend towards more IL-6 and adipsin than ScAT. Moreover, the SVF fraction of IFP contained more cells/g tissue, a lower percentage of T cells and a higher percentage of mast cells than ScAT. In addition, T cells had a predominantly pro-inflammatory phenotype while macrophages had a mixed pro- and anti-inflammatory phenotype in the IFP.
There are profound differences in secreted inflammatory factors and immune cell composition between the IFP and ScAT. These data indicate that IFP-derived soluble mediators could contribute to pathophysiological processes in the OA knee joint.
肥胖是手和膝关节骨关节炎（OA）发展的一个危险因素。脂肪组织可以分泌具有强大免疫调节作用的不同脂肪因子。髌下脂肪垫（IFP）是关节内靠近滑膜和软骨的器官。据推测，IFP 来源的可溶性因子可能有助于膝关节的病理过程。因此，进行了一项研究，以比较 IFP 和皮下脂肪组织（ScAT）中炎症介质的释放，并对这些组织中的脂肪细胞和免疫细胞浸润进行特征描述。
从 27 例原发性 OA 患者中获得配对的 IFP 和 ScAT 样本。通过荧光激活细胞分选分离并表征基质血管细胞部分（SVF）。通过 luminex 测量脂肪和脂肪细胞条件培养基中细胞因子和脂肪因子的释放。
IFP 分泌的炎症介质水平高于 ScAT，例如白细胞介素 6（IL-6）、脂联素、脂联素和内脏脂肪素。这可能是由于脂肪细胞表型和/或 SVF 细胞组成和表型的差异所致。IFP 脂肪细胞条件培养基中 IL-6 和脂联素的水平呈上升趋势，高于 ScAT。此外，IFP 的 SVF 部分比 ScAT 含有更多的细胞/g 组织、较低百分比的 T 细胞和较高百分比的肥大细胞。此外，T 细胞表现出主要的促炎表型，而巨噬细胞在 IFP 中表现出混合的促炎和抗炎表型。
IFP 和 ScAT 之间在分泌的炎症因子和免疫细胞组成方面存在显著差异。这些数据表明，IFP 衍生的可溶性介质可能有助于 OA 膝关节的病理生理过程。
