Synovial joints contain a synovial lining (synovium) consisting primarily of synovial fibroblasts and a synovial cavity containing SF.ĭuring inflammation, immune cells such as macrophages, lymphocytes, and neutrophils infiltrate the joint and SF accumulates. Synovial inflammation is a symptom of many rheumatic musculoskeletal diseases such as rheumatoid arthritis (RA), juvenile idiopathic arthritis (JIA), spondyloarthritis (SpA), osteoarthritis (OA), and systemic lupus erythematosus (lupus). Homogenization of the entire SF sample leads to less variability in IgG and oxylipin levels and prevents erroneous conclusions based on incomplete isolation of synovial fluid cells. This percentage was higher for T and B cells: 7–85% (median 22%) and 7–88% (median 23 %), respectively. Between 0.8 and 70% of immune cells (median 5%) remained in suspension and were missing in subsequent analyses when the cells were isolated from untreated SF.
There was no difference in variation for cytokines, 15-HETE, and fatty acids arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
In all patients, there was less variation in IgG, 17-HDHA, leukotriene B 4 (LTB 4), and prostaglandin E 2 (PGE 2) levels when homogenization was performed before aliquoting the SF sample.
Cell numbers and phenotype were determined using flow cytometry. The fluid was subsequently treated with hyaluronidase and centrifuged to isolate remaining cells. For cell analysis, synovial fluid was first centrifuged and the pellet was separated from the fluid. Cytokine and IgG levels were measured by ELISA or Luminex and a total of seven fatty acid and oxylipin levels were determined using LC-MS/MS in all aliquots. Synovial fluid was either treated with hyaluronidase as a whole or after aliquoting to determine whether the concentration of soluble mediators is evenly distributed in the viscous synovial fluid. SF was obtained from the knee of 29 arthritis patients (26 rheumatoid arthritis, 2 osteoarthritis, and 1 juvenile idiopathic arthritis patient) as part of standard clinical care. In this study, we investigated the importance of homogenization of the total SF sample before subsequent analysis.
Owing to its complex composition and especially the presence of hyaluronic acid, SF is usually viscous and non-homogeneous. Synovial fluid (SF) is commonly used for diagnostic and research purposes, as it is believed to reflect the local inflammatory environment.
0 kommentar(er)
