[Establishment of vulnerable plaque model by mast cell activation in adventitia and evaluation of effectiveness of intervention of Shenlian tablet]

This study was designed to investigate the activity of Shenlian tablet in stabilization of the atherosclerosis (As) plaque in apoE(-/-) mice and explore the mechanisms. Rat peritoneal mast cells were randomly allocated and treated with Shenlian tablet (100, 50, 25, 12.5 mg·L(-1)) or cromoglicate sodium (200 μg·L(-1)) for 2 h before exposure to substance P. Histamine, tryptase, IL-1β and NF-κB were measured in the cell culture supernatant by ELISA assay. The plaque formation was induced by common carotid artery cannula method combined with high-fat diet in apoE(-/-) mice, and the plaque instability was induced by substance P through local mast cell degranulation. Mice were divided into eight groups that included the model 1 (M1, sham-operated group), M2 (carotid artery cannula combined with high-fat diet）, M3 (M2 combined with substance P 0.5 μg/mouse, Shenlian extract (95, 190 and 380 mg·kg(-1)·d(-1)), atorvastatin (2.6 mg·kg-1·d(-1)) and normal control group. Total cholesterol (TC), high-density lipoprotein (HDL-C), high-sensitivity C-reactive protein (hs CRP), matrix metalloproteinases 9 (MMP-9) and histamine were measured by ELISA. Thickness, plaque area, mast cell degranulation were observed by hematoxylin and eosin staining, toluidine blue staining. CD117 antigen expression were observed by confocal microscopy. Intracellular phosphorylation was detected using the Bio-Plex 6-plex phosphoprotein assay kit. The results show that the mast cell membrane was stabilized by Shenlian tablet. Histamine, tryptase, interleukin l-β and NF-κB exhibited a significantly reduction in the Shenlian tablet-treated group (P0.05 or P0.01). Substance P significantly enhanced activation and degranulation of adventitial mast cells. In addition, it increased adventitia inflammatory cells infiltration and promoted intraplaque hemorrhages in apoE(-/-) mice model group. The proliferation, degranulation and inflammation of mast cell were significantly inhibited by Shenlian tablet. On the other hand, the same treatment decreased hs-CRP, MMP-9 and histamine in serum. IκB, p38 MAPK phosphorylation, intraplaque hemorrhage and collagen degradation were reduced in the presence of Shenlian tablet, which increased the stability of the As plaque. The results show that the vulnerable plaque model induced by mast cell activation in adventitia was established. Shenlian tablet exhibited a protective effect in this model. Shenlian tablet may increase the plaque stability via inhibition of mast cell-mediated inflammatory response.