Systemic and joint adipose tissue lipids and their role in osteoarthritis.

Osteoarthritis (OA) is a major disease whose prevalence increases with aging, sedentary lifestyles, and obesity. The association between obesity and OA has been well documented, but the precise mechanisms underlying this heightened risk remain unclear. While obesity imposes greater forces on joints, systemic fat-derived factors such as lipids or adipokine may potentially act on the pathophysiology of OA, but the exact role of these factors in weight-bearing and non-weight-bearing joints remains elusive. Intra-articular adipose tissues (IAAT) have gained significant attention for actively participating in OA pathogenesis by interacting with various joint tissues. Lipid content has been proposed as a diagnostic target for early OA detection and a potential source of biomarkers. Moreover, targeting a specific IAAT called infrapatellar fat pad (IFP) and its lipids hold promise for attenuating OA-associated inflammation. Conversely, bone marrow adipose tissue (BMAT), which was long thought to be an inert filling tissue, is now increasingly considered a dynamic tissue whose volume and lipid content regulate bone remodeling in pathological conditions. Given OA's ability to alter adipose tissues, particularly those within the joint (IFP and BMAT), and the influence of adipose tissues on OA pathogenesis, this review examines the lipids produced by OA-associated adipose tissues, shedding light on their potential role in OA pathophysiology and highlighting them as potential therapeutic targets.