Hydroxysafflor yellow A attenuates the blood-brain barrier dysfunction and neuroinflammation through anti-inflammatory microglial polarization after intracerebral hemorrhage

Abstract

The destruction of the blood-brain barrier (BBB) is the most common life-threatening event of intracerebral hemorrhage (ICH). Balancing microglia polarization is a prospective therapeutic strategy for BBB injury. This study aims to explore the neuroprotective effects and the underlying mechanisms of Hydroxysafflor yellow A (HSYA) from the perspective of BBB disruption and neuroinflammation. ICH was induced by intracerebral injection of collagenase Ⅶ in C57BL/6J male mice, and HSYA was injected through the tail vein for three days. We established three oral concentrations for HSYA and found that the administration of HSYA (20 mg/kg/d) significantly improved the neurological deficits of ICH mice and reversed the histopathological damage of the brain. Using IgG and Evans Blue staining, we demonstrated that HSYA prominently facilitated the BBB repair after ICH with no bleeding risk. HSYA greatly enhanced the expression of tight junction proteins (ZO-1, occludin, and claudin-5) but decreased MMP9. HSYA also significantly reduced the CD68⁺ microglia with pro-inflammation mediators (IL-1β, IL-6, TNF-α, iNOS, HO-1, and COX2) and increased the Arg-1⁺ microglia with anti-inflammation mediators (IL-10, and TGF-β). We identified the PI3K/Akt signaling pathway through database mining and bioinformatics analysis and verified the activation of PI3K/Akt by HSYA intervention. Further, employing the PI3K-specific antagonist LY294002 confirmed that the pre-administration of LY294002 mostly negated the neuroprotective effects of HSYA. HSYA activates the PI3K/Akt/mTOR signaling pathway, balancing microglial polarization and improving BBB integrity, highlighting its potential to be an effective drug option for ICH treatment.

Keywords: Blood-brain barrier; Hydroxysafflor yellow A; Intracerebral hemorrhage; Microglial polarization; Neuroinflammation; PI3K/Akt signaling pathway.