CKN reduces TLR4-mediated inflammation and cerebral I/R injury by activating the LXRα/ABCA1 pathway in microglia.

Abstract

Aims: CKN is a self-developed LXRα agonist capable of up-regulating the expression of ABCA1, diminishing intracellular lipid deposition, and attenuating the inflammatory response. Nevertheless, the protective effect and mechanism of ischemic stroke remain indistinct. The aim of this study is to investigate the therapeutic effects and the underlying mechanisms of CKN in ischemic stroke.

Materials and methods: In this study, the tMCAO model was utilized to induce cerebral artery occlusion in mice, and cholesterol-induced BV2 and primary microglia models were adopted. Neuronal damage and the effect of CKN on ABCA1 expression, lipid deposition, and TLR4 signaling in penumbra microglia were assessed.

Key findings: The results demonstrated that: (1) CKN treatment markedly ameliorated the neurological deficit score of the tMCAO model, contracted the infarct size, and mitigated the damage of the cerebral cortex. (2) CKN has the capacity to up-regulate the expression of ABCA1 in microglia within the ischemic penumbra by activating the LXRα/ABCA1 signaling pathway, and minimize lipid deposition and inflammatory responses. (3) The activation of the LXRα/ABCA1 signaling pathway is profoundly implicated in the inflammatory response triggered by CKN inhibition of the TLR4 signaling pathway in microglia.

Significance: The present study demonstrated for the first time that the activation of the LXRα/ABCA1 signaling possessed the ability to attenuate reperfusion injury in ischemic stroke by means of reducing lipid droplet formation and TLR4-mediated inflammatory signaling within microglia in the ischemic penumbra.