Yi-Zhi-Fang-Dai Formula Protects against Aβ1-42 Oligomer Induced Cell Damage via Increasing Hsp70 and Grp78 Expression in SH-SY5Y Cells

Yi-Zhi-Fang-Dai Formula Exerts Neuroprotective Effects Against Pyroptosis and Blood-Brain Barrier-Glymphatic Dysfunctions to Prevent Amyloid-Beta Acute Accumulation After Cerebral Ischemia and Reperfusion in Rats

Background: The dysfunctional blood–brain barrier (BBB)–glymphatic system is responsible for triggering intracerebral amyloid-beta peptide (Aβ) accumulation and acts as the key link between ischemic stroke and dementia dominated by Alzheimer’s disease (AD). Recently, pyroptosis in cerebral ischemia and reperfusion (I/R) injury is demonstrated as a considerable mechanism causing BBB–glymphatic dysfunctions and Aβ acute accumulation in the brain. Targeting glial pyroptosis to protect BBB–glymphatic functions after cerebral I/R could offer a new viewpoint to prevent Aβ accumulation and poststroke dementia. Yi-Zhi-Fang-Dai formula (YZFDF) is an herbal prescription used to cure dementia with multiple effects of regulating inflammatory responses and protecting the BBB against toxic Aβ-induced damage. Hence, YZFDF potentially possesses neuroprotective effects against cerebral I/R injury and the early pathology of poststroke dementia, which evokes our current study.

Objectives: The present study was designed to confirm the potential efficacy of YZFDF against cerebral I/R injury and explore the possible mechanism associated with alleviating Aβ acute accumulation.

Methods: The models of cerebral I/R injury in rats were built by the method of middle cerebral artery occlusion/reperfusion (MCAO/R). First, neurological function assessment and cerebral infarct measurement were used for confirming the efficacy of YZFDF on cerebral I/R injury, and the optimal dosage (YZFDF-H) was selected to conduct the experiments, which included Western blotting detections of pyroptosis, Aβ_1-42 oligomers, and NeuN, immunofluorescence observations of glial pyroptosis, aquaporin-4 (AQP-4), and Aβ locations, brain water content measurement, SMI 71 (a specific marker for BBB)/AQP-4 immunohistochemistry, and Nissl staining to further evaluate BBB–glymphatic functions and neuronal damage.

Results: YZFDF obviously alleviated neurological deficits and cerebral infarct after cerebral I/R in rats. Furthermore, YZFDF could inactivate pyroptosis signaling via inhibiting caspase-1/11 activation and gasdermin D cleavage, ameliorate glial pyroptosis and neuroinflammation, protect against BBB collapse and AQP-4 depolarization, prevent Aβ acute accumulation and Aβ_1-42 oligomers formation, and reduce neuronal damage and increase neurons survival after reperfusion.

Conclusion: Our study indicated that YZFDF could exert neuroprotective effects on cerebral I/R injury and prevent Aβ acute accumulation in the brain after cerebral I/R associated with inhibiting neuroinflammation-related pyroptosis and BBB–glymphatic dysfunctions.

Yi-Zhi-Fang-Dai Formula Exerts a Protective Effect on the Injury of Tight Junction Scaffold Proteins in Vitro and in Vivo by Mediating Autophagy through Regulation of the RAGE/CaMKKβ/AMPK/mTOR Pathway

Alzheimer's disease (AD) is a chronic neurodegeneration disease that is closely related to the abnormal tight junction scaffold proteins (TJ) proteins of the blood-brain barrier (BBB). Recently, Yi-Zhi-Fang-Dai Formula (YZFDF) had exerted a neuronal protective effect against amyloid peptide (Aβ) toxicity. Still, the therapeutic mechanism of YZFDF in restoring Aβ-induced injury of TJ proteins (ZO-1, Occludin, and Claudin-5) remains unclear. This study aimed to explore the underlying mechanism of YZFDF in alleviating the injury of TJ proteins. We examined the impacts of YZFDF on autophagy-related proteins and the histopathology of Aβ in the APP/PS1 double-transgenic male mice. We then performed the free intracellular calcium levels [Ca²⁺]i analysis and the cognitive behavior test of the AD model. Our results showed that YZFDF ameliorated the injury of TJ proteins by reducing the mRNA transcription and expression of the receptor for advanced glycation end-products (RAGE), the levels of [Ca²⁺]i, calmodulin-dependent protein kinase β (CaMKKβ), phosphorylated AMP-activated protein kinase (AMPK). Accordingly, YZFDF increased the expression of the phosphorylated mammalian targets of rapamycin (mTOR), leading to inhibition of autophagy (downregulated LC3 and upregulated P62). Moreover, the Aβ_1-42 oligomers-induced alterations of autophagy in murine mouse brain capillary (bEnd.3) cells were blocked by RAGE small interfering RNA (siRNA). These results suggest that YZFDF restored TJ proteins' injury by suppressing autophagy via RAGE signaling. Furthermore, YZFDF reduced the pathological precipitation of Aβ in the hippocampus, and improved cognitive behavior impairment of the AD model suggested that YZFDF might be a potential therapeutic candidate for treating AD through RAGE/CaMKKβ/AMPK/mTOR-regulated autophagy pathway.