Experimental Study Of The Role Of Cytokines In Radiation-induced Liver Injury

Objeetive:1 To establish rabit model of semi-liver radiation-indueed liver injury with different doses irradiation.The histological changes of radiation-indueed liver injury and the ralationship between them were observed for finding out a new way to treat liver cancer.2 To observe the expression of tumor necrosis factor-α(TNF-α),transforming growth factor-β(TGF-β), platelet- derived growth factor(PDGF) and connective tissue growth factor (CTGF) in liver tissue caused by radiation and investigate the association between the cytokines and radiation-indueed liver injury and those factors which influence them,to further reveal the radioactive pathogenesis of liver injury for finding out a new way to treat it.Method:1 Establishment of rabit model for semi-liver radiation-indueed liver injury.The rabits were randomly divided into 4 groups,including control(A) and radiation group (B,C,D).The rabits were anaesthetized by Anesthesia procedure SumianxinII(SMX) and Ketamine which were mixed in the ratio of 1:1,and fixed on the board.Then located it in the negative pressure vacuum mat and under a CT scan( the scan range from diaphragmatic dome to margo interior hepatis). Then transmitted the CT images to TPS work station. The radiation field was compassed the right semi-liver which at the right side of the cholecyst. 55% isodose curve was as the reference curve. The stereotactic radiotherapy with 2.5 collimating apparatus. The dose of group B,C and D were separately 10Gy,15Gy and 20Gy.2 Observation of the changes of cytokines and histology.Three months after radiation,the rabits were anaesthetized deep. We cut 3 pieces of liver tissues which size was about 1cm×1cm×1cm from different areas of the liver:the center of radiation target (high dose area),the edge of radiation target (low dose area),lateral lobes of left semi-liver (non-radiation area).The liver tissue was stained with H.E. and Masson.The expression of TNF-α,TGF-β1,PDGF,CTGF were examined using immunohistoehemical method.3 Statistiealanalysis.The out come was analyzed with SPSS 13.0 software.Results:1 General observation:In the process of Experiment,the performance of the radiation therapy group rabits is:dull color,apathetic, unresponsive,poor appetite,easily startled and the slow growth of weight.2 Histological changes in radiation-indueed liver injury: Gross appearance :The size of injury livers was smaller, the edge was blunt, the texture was hard, the surface and cut surface were gray-yellow,the center of diaphragmatic surface was especial apparent and the surface touch rough,occasionally there were small nodules on the surface.The changes above-mentioned were apparent when the rabbits were given high radiation dose.All of the hepatic lobes had no difference from gross appearance.H.E. and Masson in Light microscope:The livers after radiotherapy could be seen center veins and blood sinus congestion under the light microscope. Also we could see venous occlusive disease, liver necrosis,inflammatory cell infiltration around the bile duct, small bile duct hyperplasia, collagen fibers in the portal areas,blood sinus,central venous sinus and around were increase and extend to hepatic lobule and hepatic cord. With the radiation dose increased,the change of different dose groups based on the same area of liver aggravated;the change of different areas of the liver in the same dose group was different,the high dose area was more serious than low dose area and the low dose area was more serious than non-radiation area.3 The expression of cytokinesIn radiation groups, TNF-α,TGF-β1,PDGF,CTGF were significantly expression in the cytoplasm of hepatic cells between fibers, portal areas,entral vein and around. With the radiation dose increased, cytokine expression of irradiated group was increase,the difference was significant(P<0.05),and the difference was significant with the control group(P<0.05); the expression of cytokine in different areas of the same radiation was different,the high dose area was more positive than low dose area and the low dose area was more positive than non-radiation area, the difference was significant(P<0.05),and the difference was significant with the control group(P<0.05).4 Correlation analysis for the histopathological manifestation:The expression of cytokines and the degree of hepatic fibrosis correlated with the irradiation dose positively(r =0.899,0.958,0.959,0.968,0.967,P<0.05),So,with the increase of the dose,the expression of cytokines increased significantly,the fibrosis became severe. The expression of TNF-α, TGF-β1, PDGF,CTGF was positively correlated(r=0.810,0.863, 0.866, 0.821,0.899,0.804,P<0.05).The expression of cytokines had a positive correlation with the degree of fibrosis (r=0.892,0.848, 0.942,0.764,P<0.05).Conclusion1 The histological changes of radiation-indueed liver injury in rabits were hepatic vein occlusion disease (VOD) and liver fibrosis.With the radiation dose increased hepatic vein occlusion,liver fibrosis and liver cells and the bile duct injury gradually increased.Prompted the liver dose of radioactive lead to liver injury is an important factor in the occurrence.2 It can be seen that a wide range of TNF-α, TGF-β1, PDGF,CTGF expression in the radioactive liver injury tissue ,the positive expression of cytokines increase with the radiation dose and the injury became severe.The expression of cytokines and the degree of hepatic fibrosis correlated with the irradiation dose positively,TNF-α,TGF-β1,PDGF,CTGF may play an important role in promoting the formation of hepatic fibrosis,and the radiological dose and liver injury occurred close,the reason of radiation induced injury in liver has many factors.3 TNF-α,TGF-β1,PDGF,CTGF expression similar to the distribution,relevant,and parallel on degree of liver fibrosis and pathological,suggesting the formation of hepatic fibrosis is a complex process with a variety of cytokines involved.In the course of the occurrence of liver fibrosis cytokines closely related to each other,there may existence reaction cascaded, co-promotion of radioactive progressive liver fibrosis progress.4 We found that the expression of cytokines increased outside field of irradiation,have significant difference with the control group,so that the radioactive liver damage may not limited in a certain period by local organizations,local radiation-induced damage would gradually exposure to outside field of irradiation.