Rajiv Gandhi, Amanda Weston, Carl Virtanen, Mark Takahashi, Nizar Mahomed and Anthony Perruccio
Objective: Previous research has examined gene expression of the IFP from individuals with early and endstage knee OA. However, there is little understanding of whether the differential expression that was found is a local effect associated with OA disease severity. The objective of this study was to compare gene expression of the SAT and IFP both within individuals with early and late stage knee OA.
Methods: Knee SAT and corresponding IFP samples were harvested from twenty-nine patients with endstage and five patients with early stage OA at the time of knee surgery. Total RNA was then extracted, labelled and hybridized to Illumina whole genome expression arrays. Arrays were scanned and intensity of hybridization quantified. Filtered data were analyzed to find significantly different expressed genes between the disease stages and fat types.
Results: SAT gene expression demonstrated significantly less differential genes between disease states when compared to the gene expression profiles of IFP tissues between individuals with early and endstage OA. Among those with early stage OA, the SAT and IFP tissues were highly dissimilar at the gene expression level, whereas among those with endstage OA these tissues were comparatively more similar.
Conclusions: Our findings suggest that the effects of OA on the IFP are localized, more so with later disease stages, while changes in the SAT are less prominent. It is unknown whether or not the localized effects of IFP may be a unique contributor to knee OA or a result of systemic changes occurring in the body. Further research which includes longitudinal assessments with larger cohorts is warranted.