Ginsenoside Rb1 alleviates blood-brain barrier damage and demyelination in experimental autoimmune encephalomyelitis mice by regulating JNK/ ERK/NF-κB signaling pathway

Ethnopharmacological relevance: The traditional Chinese herb Panax ginseng recorded in "Shennong Herbal Classic" is renowned for its purported vascular regulatory properties and immune-enhancing capabilities. Ginsenoside Rb1 (Rb1), a prominent bioactive compound in Panax, has demonstrated significant neuropharmacological activities. However, its impact on multiple sclerosis (MS) and blood-brain barrier (BBB) damage remains inadequately investigated.

Aim of the study: Inflammation and BBB disruption are pivotal to MS. Tightly packed brain capillary endothelial cells are fundamental to the structural and functional integrity of the BBB. Rb1 has been shown to alleviate BBB damage in stroke rats, but its effect on BBB damage in MS is not well understood. The objective of this study was to examine the role and mechanism of Rb1 on BBB injury in experimental autoimmune encephalomyelitis (EAE) mice.

Materials and methods: The BBB protection effect and mechanism of Rb1 were evaluated in LPS-treated bEnd.3 cells and EAE model mice. The mRNA expression levels of the inflammatory factor and the protein expressions of Matrix Metalloproteinases 9 (MMP9), zona occludens 1 (ZO-1), inhibitor of NF-κB (IκBα), occludin, Jun-amino-terminal kinase (JNK), and nuclear factor-κB (NF-κB) in bEnd.3 cells and mouse cerebral cortex were quantified. The permeability of bEnd.3 cells was examined by measuring trans-endothelial electrical resistance (TEER) and sodium fluorescein (NaF) leakage.

Results: Rb1 administration in the early stages of EAE postponed the disease's onset and lessened its severity. Rb1 inhibited the destruction of the BBB in brain cortex of EAE mice. Rb1 reduced the lipopolysaccharide (LPS)-induced hyperpermeability of bEnd.3 cells and prevented the downregulation of TJ proteins. In addition, in LPS-induced bEnd.3 cells, Rb1 decreased the overproduction of Reactive Oxygen Species. Moreover, Rb1 suppressed the phosphorylation of JNK, ERK, NF-κB, and IκB in vivo and in vitro. Furthermore, the JNK agonist anisomycin was observed to partially abolish the protective effect of Rb1 in bEnd.3 cells treated with LPS.

Conclusions: Taken together, we demonstrated that Rb1 improved demyelination and BBB damage in EAE mice by modulating JNK/ERK/NF-κB signaling pathway. This study can offer a theoretical foundation for the use of Rb1 in the treatment of MS/EAE by preventing BBB injury.

Blood-brain barrier; Experimental autoimmune encephalomyelitis, Multiple sclerosis; Ginsenoside Rb1; JNK/ERK/NF-κB signaling.