The Effect Of Th1/Th2 Cytokines On The Liver Injury Of Guinea Pigs Induced By Trichloroethylene

Background Trichloroethylene (TCE) is an organic solvent mainly used as degreaser in industry. Occupational exposing to TCE, workers appear dermatitis (DMLT) with liver injury, and it has become a major occupational health issue now. In recent years, there are many studies on the mechanism of skin injury, which considered it as delayed-type hypersensitivity. DMLT patients often have severe liver injury, which is the direct cause of death, but there are little studies on the mechanism of liver injury. Existing mechanisms such as immune and genetic polymorphism is hard to explain DMLT associated with liver injury. Th1/Th2 Cytokines are closely related to inflammatory response, and they influence each other. The Cytokines network system play an important role in inflammatory injury by starting and suppress inflammation.Objective Detecting IL-4, IL-10, IL-12 and IFN-γexpression in liver homogenate of Guinea Pigs in different groups and different time points, combined with liver function tests and pathological examination, to investigate the mechanism of liver injury induced by TCE.Method Female guinea pigs, which were white and weighing 250～300g ,were adopted. After adaptive feeding a week, the Guinea Pigs were divided to blank control group, solvent (olive oil) control group, TCE group in random. To monitor the status of guinea-pig growth and health, their weight was measured regularly. Adopting Guinea Pig Maximization Test (GPMT) to establish sensitization model, to observe and record the skin reaction in Guinea Pigs back and take pictures. Reaction in Guinea Pigs skin was scored in accordance with the skin reaction score standards in"Toxic chemicals identified technical specifications"(the Ministry of Health superintend made【2005】No.272). When the skin reaction scores of test group≥1, it should be ruled positive skin sensitization, which was sensitized group, otherwise was non-sensitized group. 24h before, 24h and 72h after sensitization test suctioned the serum of Guinea Pigs and killed the animals. Serum was prepared for Hepatic function. Cytokine levels in liver homogenate were determined by ELISA and immunohistochemistry. Experimental results were analyzed with SPSS13.0.Result1. Sensitization rate In the skin sensitization test, the control group, solvent control group and TCE 14d group showed no erythema or edema; 19 of 30 animals in TCE test group showed erythema and edema, sensitization rate is 63.3%.2. Pathological test results In the control group and solvent control group, liver cells arranged in neat, with large round nuclei, clear nuclear membrane and uniform cytoplasm; Liver cell swelling was seen in part of TCE non-sensitized animals. There was a small amount of liver cell edema in TCE 24h sensitized group, while more liver cell swelling and nucleus broken disappear in TCE 72h sensitized group.3. Results of liver function Compared with the control group, liver function of solvent group was not statistically significant (p>0.05); ALT levels in TCE sensitized group elevated significantly (p<0.05), and ALT levels of TCE un-sensitized group elevated, but the difference was not statistically significant (p>0.05); Compared with TCE 14d group, TCE sensitized 24h group and TCE non-sensitized 72h group, ALT and AST levels in TCE sensitized 72h group increased significantly(p<0.05); Compared with TCE sensitized 24h group and TCE non-sensitized 72h group, ALB levels in TCE sensitized 72h group increased significantly(p<0.05) .4. Results of IL-12 Compared with the blank control group, IL-12 level in solvent control group showed no significant difference(p> 0.05); Compared with the solvent control group, IL-12 in sensitized 72h group and un-sensitized 72h group elevated significantly; IL-12 in TCE non-sensitized group was slightly higher than the sensitized group, but the difference was not statistically significant (p>0.05).5. Results of IFN-γCompared with the blank control group, IFN-γlevel in solvent control group showed no significant difference(p>0.05); Compared with the solvent control group, IFN-γin sensitized group and non-sensitized group elevated significantly; IFN-γwere significantly increased in TCE 72h sensitized group compared with TCE14d group, TCE sensitized 24h group and TCE non-sensitized 72h group(p<0.05).6. Results of IL-4 Compared with the blank control group, IL-4 level in solvent control group showed no significant difference(p>0.05); Compared with the solvent control group, IL-4 in sensitized group and non-sensitized group elevated significantly(p<0.05); IL-4 were significantly increased in TCE sensitized group compared with TCE non-sensitized group(p<0.05).7. Results of IL-10 Compared with the blank control group, IL-10 levels in solvent control group showed no significant difference (p>0.05); Compared with the solvent control group, TCE sensitized group and non- sensitized group was significantly elevated (p<0.05); IL-10 levels of TCE 14d group were not statistically deferent from solvent control group (p>0.05).8. IFN-γ/IL-4 Compared with the blank control group, solvent control group showed no significant difference (p>0.05); TCE sensitized 24h group was lower significantly than solvent control group and 72h sensitized group (p <0.05) .9. IL-12/IL-10 Compared with the blank control group, solvent control group showed no significant difference (p>0.05); Compared with solvent control group, TCE sensitized group decreased, the difference was statistically significant (p <0.05); TCE sensitized 24h group were significantly lower than non-sensitized 24h group, the difference was statistically significant (p <0.05) . Conclusion1. TCE sensitized model was established by Guinea Gigs Maximum Test, TCE sensitization rate was 63.3%.2. TCE can cause liver cells pathological damage, edema, nuclear breakdown; The injury was common in the TCE sensitized group, while it can be seen in part of TCE non-sensitized Guinea Pigs.3. TCE treatment can result in guinea pig liver injury, damage aggravated with time. 4. IL-4, IL-10, IL-12 and IFN-γmay have participated in liver injury induced by TCE. 24h after the last challenge, Th1/Th2 balance showed a tilt to Th2. As time goes, Th1/Th2 reaches a new balance at the 72h time point.