Berberine ameliorates inflammation by inhibiting MrgprB2 receptor-mediated activation of mast cell in mice

Background

Berberine, an isoquinoline alkaloid, is known for anti-inflammatory activities. However, the research on the anti-inflammatory mechanism of berberine is not comprehensive. Recently, studies have shown that MrgprB2 (Mas-related G-protein-coupled receptor B2) in mice and MrgprX2 (Mas-related G-protein-coupled receptor X2) in humans play vital roles in inflammation. Therefore, this study aims to investigate whether the anti-inflammatory activity of berberine is related to MrgprB2 receptor.

Methods

The anti-inflammatory activity of BH (berberine hydrochloride) was evaluated by hindpaw edema analysis, pathological analysis and RT-qPCR. Transgenic mice (MrgprB2^−/− mice), HEK293T cell transfection, calcium imaging, electrophysiology, molecular docking and other methods were employed to investigate the potential relationship between the anti-inflammatory activity of BH and the MrgprB2 receptor.

Results

The results demonstrated that BH significantly alleviated C48/80 (compound 48/80)-induced local inflammation in vivo. This was evidenced by a decrease in paw edema, reduced infiltration of inflammatory cells, inhibition of mast cell activation, and down-regulation of inflammatory factors such as CXCL13 (CXC subfamily 13) and TNF-α (tumor necrosis factor-α). It was also found that knockout of MrgprB2 receptor could block the anti-inflammatory activity of BH in mice. Furthermore, calcium imaging revealed that BH effectively inhibited the activity of MrgprB2 receptor in overexpressed HEK293T cells in vitro. Additionally, it was observed that BH also inhibited MrgprB2-mediated voltage-dependent current changes in mouse peritoneal mast cells. Molecular docking results further indicated that BH had affinity with MrgprX2 protein.

Conclusions

The anti-inflammatory mechanism of BH may be partially attributed to the inhibition of MrgprB2 receptor-mediated mast cell activation.