The NEDD8-activating enzyme inhibitor MLN4924 reduces inflammation, blood-brain barrier disruption and brain injury after intracerebral hemorrhage in mice.

Inflammation is a key factor leading to secondary brain injury after intracerebral hemorrhage (ICH). Neddylation, a post-translational modification that attaches NEDD8 (neuronal precursor cell-expressed developmentally downregulated protein 8) to targets, regulates diverse cellular processes. Neddylation is overactivated in various cancers and linked to atherosclerosis and inflammatory disorders, but its role in ICH remains unclear. In this study, mice were subjected to ICH by injection of collagenase. The NEDD8-activating enzyme inhibitor MLN4924 was administered subcutaneously post-ICH. We found that NEDD8 expression was upregulated in macrophages and microglia after ICH. Treatment with MLN4924 reduced NEDD8 expression, cullin-1 neddylation, macrophage infiltration, microglial activation, and the production of proinflammatory cytokines. These anti-inflammatory effects were accompanied by attenuated loss of tight junction proteins, blood-brain barrier (BBB) damage, neuronal degeneration and brain injury, and improved neurological function. Furthermore, MLN4924 treatment induced the accumulation of the cullin-RING E3 ligase substrates, including phosphorylated ERK5 and KLF2, and reduced ICAM-1 expression. Inhibiting ERK5 reversed the beneficial effects of MLN4924 on inflammation, BBB disruption, and neurobehavioral deficits. Collectively, inhibition of the NEDD8 pathway by MLN4924 attenuates inflammation, BBB disruption, and neurological deficits via the p-ERK5-KLF2-ICAM-1 axis, highlighting NEDD8 pathway as a potential therapeutic target for ICH.