Xijiao Dihuang Decoction Attenuates Microglia/Macrophage-Mediated Inflammatory Response in Cerebral Injury by Modulating the PI3K/Akt/HIF-1α/NLRP3 Axis.

ETHNOPHARMACOLOGICAL RELEVANCE Xijiao Dihuang Decoction (XJDH), originating from Beiji Qianjin Yaofang (Thousand Gold Prescriptions for Emergencies) compiled by Sun Simiao during the Tang Dynasty (652 AD), is a classical Traditional Chinese Medicine (TCM) formula comprising Cornu Bubali (substituted for Rhinoceros horn), Radix Rehmanniae, Paeoniae Radix Rubra, and Cortex Moutan. In TCM clinical practice, XJDH has traditionally been prescribed for "Xue-Re" (Blood-Heat) syndrome characterized by febrile diseases with bleeding tendency, blood stasis and impaired consciousness, a clinical pattern that shares pathophysiological features with the inflammatory cascade and microcirculatory dysfunction in acute ischemic stroke (AIS). However, the molecular mechanism by which XJDH alleviates cerebral injury via the microglia/macrophage inflammatory cascade remains incompletely characterized.

Aim

OF THE STUDY This study aims to elucidate the mechanism by which XJDH ameliorates cerebral injury by mitigating the microglia/macrophage inflammatory cascade, in association with the PI3K/Akt/HIF-1α/NLRP3 axis.

Materials And Methods

The middle cerebral artery occlusion (MCAO) model in C57BL/6J mice and a lipopolysaccharide (LPS)-induced inflammatory model in RAW264.7 and THP-1 cells were established for in vivo and in vitro experiments, respectively. Pathological alterations, inflammatory responses, and the PI3K/Akt/HIF-1α axis were assessed by HE staining, TUNEL assay, immunofluorescence, ELISA, RT-qPCR, and Western blot analyses. The PI3K inhibitor LY294002 , the Akt agonist SC79 and the HIF-1α agonist DMOG were employed for pathway verification. Serum from 60 participants (20 controls, 20 AIS, and 20 AIS treated with XJDH) was also analyzed for inflammatory cytokines.

Results

XJDH dose-dependently promoted neurological function, decreased cerebral infarct volume, attenuated histopathological injury, and mitigated cell apoptosis in MCAO. Network pharmacology identified 244 shared targets between XJDH and AIS, with PI3K/Akt and HIF-1 pathways ranking among the top enriched pathways. Molecular docking confirmed favorable binding affinities of key XJDH constituents to PI3K (-8.7 kcal/mol), Akt (-6.0 kcal/mol), and HIF-1α (-7.0 kcal/mol). XJDH significantly enhanced PI3K and Akt phosphorylation levels, downregulated HIF-1α and NLRP3, and shifted microglia/macrophages from an M1- toward an M2-dominant phenotype in MCAO mice. These effects were largely abolished by LY294002 in both RAW264.7 and THP-1 cells. Consistently, Akt activation by SC79 potentiated, whereas HIF-1α stabilization by DMOG reversed, the anti-inflammatory effect of XJDH, supporting the involvement of the Akt-HIF-1α axis.

Conclusions

XJDH ameliorates cerebral injury in mice in association with the PI3K/Akt/HIF-1α/NLRP3 axis and a shift of microglia/macrophages away from an M1-dominant phenotype; these findings provide preclinical, ethnopharmacology-oriented rationale warranting further validation in neuron-macrophage co-culture systems and, ultimately, randomized clinical evaluation.