Investigating the therapeutic mechanism of leech in vascular dementia: An integrated approach combining network pharmacology and experimental validation.

BACKGROUND

Vascular dementia (VaD), the second leading cause of dementia following Alzheimer's disease, results from the reduction in cerebral blood flow. Medicinal leeches (SZ) in traditional Chinese medicine (TCM), a classic remedy for promoting blood circulation and improving blood stasis, have shown capabilities to relieve neuroinflammation and repair the blood-brain barrier (BBB) integrity. However, the efficacy and the underlying mechanisms of medicinal leeches in treating VaD remain unclear.

OBJECTIVE

This study aimed to explore the efficacy of medicinal leeches in treating VaD and its molecular mechanisms.

METHODS

An in vivo VaD model of rats was created via a two-vessel occlusion (2VO) ischemia protocol. Learning and memory functions in rats were assessed via the water maze test, Y-maze test, and novel object recognition test. The neuronal injury in rat hippocampus was assessed by H&E and Nissl staining. Network pharmacology (NP) and molecular docking depicted a "SZ-Compounds-Targets" network and visualized the binding pattern between core components of medicinal leeches and key targets of VaD, respectively. Transmission electron microscopy (TEM), ELISA, quantitative PCR, and Western blotting were performed to validate the involvement of the TLR4/NF-κB signaling pathway in leech treatment against VaD.

RESULTS

Medicinal leeches alleviated the cognitive deficits and neuronal injuries in VaD rats. Seven key targets were predicted as the leading contributors to the neuroprotective potential of medicinal leeches against VaD. Enrichment analyses further showed that the Toll-like receptor and NF-κB signaling pathways were enriched in the key targets of medicinal leeches. Experimental assays showed that expression levels of TLR4, MyD88, p-p65, and pro-inflammatory mediators were significantly elevated in VaD rats, which were further enhanced by LPS induction. Encouragingly, leech treatment significantly downregulated their levels.

CONCLUSION

Medicinal leeches can effectively alleviate the learning and cognitive impairments, neurological pathology in the hippocampal CA1 region, and the loss of BBB integrity in VaD rats. Moreover, medicinal leeches can suppress the neuroinflammation in VaD rats through inhibiting the TLR4/NF-κB signaling pathway.