[Effects of mast cells on degradation of collagen fibers in dimethylnitrosamine-induced hepatic fibrosis of rat].
OBJECTIVE
To investigate the relationship between mast cell and hepatic fibrosis by histopathological method and semi-quantitative measurement.


METHODS
Seventy-two Wistary male rats, the control group and the normal group of each only 16, experimental group of 40 rat liver fibrosis was induced by injection of DMN and was sampled at eight different time points. HE, histochemistry, immunohistochemistry (ABC method) and immunofluorescence were performed. The size of fibrosis and the number of mast cells were counted. The expression of MMP-2 and TIMP-2 was documented and electron microscopic examination was performed.


RESULTS
After injection of DMN, the fibrosis was the most severe in the 2 week (3.72%) and the first month (3.73%, P = 0.2626), and then gradually diminished, although residual fibrosis was still present at 12 months (1.42%, P = 0.0003). The appearance of mast cells began at 2 weeks (1.73 per 200 power field in average by light microscope) after the injection and reached the peak at 4 months (3.06, P = 0.008). Residual amount of mast cells were present at 12 months (1.04, P = 0.045). However, the degree of fibrosis was not proportional or overlapping with the number of mast cells in this experiment model. Mast cells expressed MMP-2 but not TIMP-2.


CONCLUSIONS
In the DMN-induced rat liver fibrosis model, mast cell may be an integral player in the pathogenesis of liver fibrosis and may contribute to the degradation of fibrosis by synthesizing and secreting MMP-2.
Department of Pathology, Beijing Tongren Hospital, Capital Medical University, Beijing 100730, China. jinyulan.love@163.com
Yu-lan
YL
Jin
Quan
Q
Zhou
Cheng
C
Tian
Hong-gang
HG
Liu
Yosihiro
Y
Hayashi
Hideaki
H
Enzan
D000199:Actins / Q000378:metabolism; D000818:Animals; D002452:Cell Count; D004128:Dimethylnitrosamine; D008103:Liver Cirrhosis / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008407:Mast Cells / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D053802:Tryptases / Q000378:metabolism
D000199:Actins; D004128:Dimethylnitrosamine; D020778:Matrix Metalloproteinase 2; D019716:Tissue Inhibitor of Metalloproteinase-2; D053802:Tryptases; C498862:Acta2 protein, rat; C522363:Mmp2 protein, rat