Infrapatellar fat pad adipose tissue-derived macrophages displays a predominant CD11c+CD206+ phenotype and expresses genotypes attributable to key features of OA pathogenesis

In knee osteoarthritis (OA), macrophages are the most predominant immune cells that infiltrate synovial tissues and IPFPs. Both M1 and M2 macrophages have been described, but their role in OA have not been fully investigated. Therefore, we investigated macrophage subpopulations in IPFPs and synovial tissues of knee OA patients and their correlation with disease severity, examined their transcriptomics and tested for factors that influenced their polarization. 42 samples overall from knee OA patients were used to study the gene expression profile of macrophages. One pooled sample of macrophages isolated from an infrapatellar fat pad was obtained from 14 patients. Three pooled samples were utilized in this study.