Secretase-Independent and RhoGTPase/PAK/ERK-Dependent Regulation of Cytoskeleton Dynamics in Astrocytes by NSAIDs and Derivatives

Profens like ibuprofen, R-flurbiprofen, or CHF5074 are being considered for the treatment of Alzheimer's disease because epidemiological data indicates that non-steroidal anti-inflammatory drugs are protective against neurodegeneration. Rho-GTPases are small G proteins, including RhoA, Cdc42, and Rac1, which control cytoskeleton dynamics. Because ibuprofen promotes axon growth via RhoA in neurons, we examined whether profens modulate astrocyte plasticity via Rho-GTPases. We report that ibuprofen (100-500 μM), R-flurbiprofen (100-500 μM), and CHF5074 (10-30 μM) caused a concentration-dependent stellation of astrocytes in primary cultures, associated with the reorganization of GFAP and actin filaments. The stellation was independent of COX2, α-, β- or γ-secretase as judged by the lack of effect of inhibitors of these enzymes. RhoA, PAK, and Cdc42, but not Rac1, accounted for the profen-mediated stellation, as concluded from the joint analyses of activities and reversal experiments with adenoviral or pharmacological manipulations. Ibuprofen accelerated migration in a scratch-wound assay, while R-flurbiprofen had no effect and CHF5074 caused deceleration. Cell polarity regulation by Cdc42 and ERK1/2 may underlie the paradoxical effects of profens on migration. We conclude that profens regulate cytoskeleton dynamics in astrocytes via Rho-GTPases, PAK, and ERK1/2. Since migration is a hallmark of astrocyte response during inflammation we propose that, in addition to (or instead of) lowering amyloid-β42 via secretases, ibuprofen and its derivatives may prevent Alzheimer's disease instead of AD by modulating astrocyte reactivity through Rho-GTPase/PAK/ERK-dependent signaling.