Danhong Injection Modulates Microglial Polarization and Neuroinflammation via the JUNB/NF-κB Pathway in Ischemic Stroke.

Abstract

Ethnopharmacological relevance: Ischemic stroke (IS) is a leading cause of death and disability in China. Danhong Injection (DHI) is a traditional Chinese medicine preparation made from Salvia miltiorrhiza var. miltiorrhiza and Carthamus tinctorius L. It is used for treating stroke in China with proven safety and efficacy. Microglia M1/M2 polarization is a key factor in IS inflammatory response. However, the key transcription factors that regulate microglia polarisation are unknown. It is also not clear how DHI exerts its mechanism in the treatment of IS.

Aim of the study: This research aimed to investigate the effect of DHI on microglial polarization and neuroinflammation associated with IS and to elucidate the underlying mechanisms, with an emphasis on the JUNB/NF-κB signaling pathway.

Materials and methods: An oxygen-glucose deprivation (OGD) damage cell model and a permanent middle cerebral artery occlusion (pMCAO) model in C57BL/6 mice were employed. Neurological deficits, cerebral infarct volume, and microglial activation were assessed. Non-targeted metabolomics analysis with UHPLC-QE-MS and molecular biology methods, including RT-qPCR and Western blot, were applied to investigate the mechanisms.

Results: In vivo, DHI decreased inflammation, reduced brain damage, and enhanced neurological function. DHI also ameliorated microglial activation and OGD-induced apoptosis in vitro. Metabolomics analysis identified significant metabolic changes, particularly in amino acid metabolism. Additionally, DHI treatment decreased the upregulated mRNA levels of ASS1 and ASL after OGD, indicating an influence on the arginine biosynthesis pathway, which is crucial for microglial function. DHI modulated the M1 to M2 phenotypes of microglial polarization and regulated microglial polarization through the JUNB/NF-κB signaling pathway. This was confirmed by JUNB silencing experiments.

Conclusions: DHI exhibits neuroprotective effects via suppressing ASS1 through the JUNB/NF-κB pathway, promoting the M2 state of microglia, and lowering the expression of inflammatory cytokines. This research unveils the potential therapeutic target of JUNB for IS treatment and sheds light on the novel intervention mechanism of DHI in microglial cells.