TREM1/DAP12-mediated neuron-microglia crosstalk in ischemic stroke: Huangxiong formula reduces Neuroinflammation and neuronal Pyroptosis.

Background

The inflammatory cascade drives the progression of ischemic stroke (IS), with neuron-microglia interactions playing a critical role in maintaining brain homeostasis. Huangxiong Formula (HXF) demonstrates clinical efficacy in IS; however, its precise neuroprotective mechanism remains unclear. This study investigates whether HXF mitigates neuroinflammation by modulating microglial polarization and neuronal pyroptosis.

Methods

In vivo, HXF was administered to mice in a middle cerebral artery occlusion/reperfusion (MCAO/R) model. In vitro, a TREM1-overexpressing BV2 microglial cell line was established, and HT22 neurons were treated with conditioned medium derived from LPS-stimulated microglia. HXF-containing cerebrospinal fluid (HXF-CSF) was used for microglial treatment.

Results

HXF significantly improved neurological scores, enhanced cerebral perfusion, and reduced infarct volume in MCAO/R mice. Mechanistically, HXF shifted microglial polarization from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype and inhibited neuronal pyroptosis, as evidenced by reduced levels of IL-18, IL-1β, and cleaved caspase-1, along with suppression of the TREM1/DAP12 pathway. In vitro, HXF-CSF directly suppressed microglial M1 polarization and cytokine release. Conditioned medium derived from HXF-CSF-treated microglia markedly reduced pyroptosis in HT22 neurons. TREM1 overexpression in microglia abolished these protective effects.

Conclusion

HXF alleviates neuroinflammation and neuronal pyroptosis by inhibiting microglial M1 polarization through the TREM1/DAP12 pathway. Microglial TREM1 represents a key therapeutic target, supporting the clinical application of HXF for ischemic stroke.