Abstract

Astrocytes, the primary glial cells in the central nervous system, play a critical role in neuroinflammation, a process often mediated by the activation of Toll-like receptors (TLRs). Hyaluronic acid (HA), a major component of the extracellular matrix, is known to exert differential effects on cellular signaling based on its molecular weight. This study investigated the distinct effects of high molecular weight (HMW) and low molecular weight (LMW) HA on the release of omega-3 (docosahexaenoic acid, DHA; eicosapentaenoic acid, EPA) and omega-6 (arachidonic acid, AA) polyunsaturated fatty acids (PUFAs) from primary rat astrocytes following TLR activation. Using HPLC-MS/MS, we found that LMW HA significantly reduced the short-term release of AA, while HMW HA did not affect AA but increased the release of DHA and EPA. Furthermore, prolonged exposure (48 hours) to both HA forms led to an adaptive decrease in the release of all tested PUFAs. A comparison of HA's ability to modulate TLR-stimulated responses revealed that both HMW and LMW HA affected the TLR4-induced expression of the pro-inflammatory marker IL-1β. These findings demonstrate that the molecular weight of HA is a critical determinant in regulating the release of PUFAs, which are precursors to potent lipid mediators, and suggests that HMW HA may possess a protective, anti-inflammatory potential in the brain by promoting the release of anti-inflammatory omega-3 fatty acids.