Inhibition of activator protein 1 attenuates neuroinflammation and brain injury after experimental intracerebral hemorrhage.

Aims: Intracerebral hemorrhage (ICH) is a devastating type of stroke without specific treatment. Activator protein 1 (AP-1), as a gene regulator, initiates cytokine expression in response to environmental stimuli. In this study, we investigated the relationship between AP-1 and neuroinflammation-associated brain injury triggered by ICH.

Methods: Intracerebral hemorrhage mice were developed by autologous blood or collagenase infusion. We measured the dynamics of AP-1 in mouse brain tissues during neuroinflammation formation after ICH. The effects of the AP-1 inhibitor SR11302 on brain injury and neuroinflammation as well as the underlying mechanisms were investigated in vivo and in vitro.

Results: AP-1 was significantly upregulated in mouse brain tissue as early as 6 hours after ICH, accompanied by elevations in proinflammatory factors, including interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α. Inhibition of AP-1 using SR11302 reduced neurodeficits and brain edema at day 3 after ICH. SR11302 ablated microglial IL-6 and TNF-α production and brain-infiltrating leukocytes in ICH mice. In addition, SR11302 treatment diminished thrombin-induced production of IL-6 and TNF-α in cultured microglia.

Conclusions: Inhibition of AP-1 curbs neuroinflammation and reduces brain injury following ICH.