| Trichinella spiralis(T.spiralis)is a zoonotic parasite with the unique biological characteristics.It can complete entire life cycle in the same host,and parasite in different tissue of its host at different developmental stage.Adult worm(Ad)of T.spiralis parasitize in the intestine of the host,newborn larvae(NBL)parasitize in the intestine and blood circulatory system,and muscle larvae(ML)are mainly parasitize in the striated muscle of the host.In order to build an environment that suitable for survival and no excessive stimulation to the host,T.spiralis can regulate the host's immune response at various stages.Excretion/secretion products(ESP)has multiple biological functions.It can reduce the inflammatory response caused by invasion,induce apoptosis,participate in the changes of physiological and biochemical characteristics,and reconstruct the structure of host cell.Based on its unique biological characteristics and ability to regulate the host's immune response,T.spiralis and ESP have been used in the therapy studies of different diseases.The domestic and overseas studies showed that T.spiralis infection could increase the host's resistance to tumors.T.spiralis ESP could inhibit the proliferation of tumor cells in vitro.However,the mechanism of the anti-tumor effect of T.spiralis keep still unclear.In this study,the inhibitory effect of T.spiralis infection,ML and Ad6 ESP on the growth of H22 hepatocarcinoma cells were investigated respectively and then we discussed the possible mechanism of T.spiralis anti-tumor.In this study,the model of H22 hepatocarcinoma were constructed by injecting5×10~6 H22 hepatocarcinoma cells into the armpit of the right forelimb on the 7th day after the mice were infected with 350 T.spiralis.The tumor-bearing mice uninfected with T.spiralis were used as a control group,to explored the inhibitory effect of T.spiralis infection on the growth of tumor in mice.The results showed that the tumor inhibition rate was 63.49%,The results indicated that T.spiralis infection significantly inhibited the growth of H22 transplanted hepatocarcinoma in mice.In order to explore the role of host immunity induced by T.spiralis infection in againsting H22 transplanted hepatocarcinoma,100 BALB/c mice were randomly divided into control group(20 mice),T.spiralis group(20 mice),tumor group(30mice),and T.spiralis+tumor group(30 mice).The mice of the T.spiralis+tumor group were grafted H22 hepatocarcinoma cells on the 7th day after the mice were infected with the T.spiralis in the study.The mice of the tumor group and the T.spiralis+tumor group were grafted H22 hepatocarcinoma cells at the same time point.On the 7th,14th,21st,28th and 35th day of the experiment,3 mice of each group were sacrificed.Spleen cells of the mice were collected,and used for culture to collect supernatant or stored in the-80?refrigerator for total RNA extraction.The expression of interleukin-2(IL-2),interferon-gamma(IFN-?)and interleukin-4(IL-4)in the spleens of mice in each group were detected by Quantitative Real-Time PCR and ELISA.The expression of IL-2 and IFN-?in the spleen cells of T.spiralis group and T.spiralis+tumor group showed high levels on the 7th,14th,21st and28th day of the experiment.The expression of IL-2 and IFN-?in the T.spiralis group and T.spiralis+tumor group were decreased and were not significantly different compared with control group and tumor group on the 28th day of the experiment.The expression of IL-4 in the spleen cells of the T.spiralis group and T.spiralis+tumor group remained high on the 14th and 21st days of the experiment.The results of this study indicate that IL-2 and IFN-?of the Th1-type cytokines in the early phase of T.spiralis infection and IL-4 of Th2-type cytokines anti-inflammation cytokine in the late phase of T.spiralis infection may contribute to the inhibition of tumor growth.In addition,ESP of T.spiralis were collected at different stages and used to investigated the effects on cell proliferation and apoptosis of H22 hepatocarcinoma cells,and their effects on cell proliferation and apoptosis of H22 hepatocarcinoma cells were investigated in vitro and used to investigate whether infection of T.spiralis can induce apoptosis in tumor.The result of CCK-8 showed that T.s ML ESP and Ad6 ESP had a significant inhibitory effect on mouse H22 hepatocarcinoma cells when the concentrations of T.s ML ESP and Ad6 ESP exceeded 0.2 mg/mL.Annexin V-FITC/PI cell apoptosis detection showed T.spiralis ML ESP and Ad6 ESP at the concentration of 0.4 mg/mL stimulate H22 hepatocarcinoma cells for 48 hours and the apoptosis rates were 18.02%and 14.89%,Western blotting results showed that the ratio of Bax/Bcl-2 and the expression of Caspase-3 in H22 hepatocarcinoma cells and tumor tissues were up-regulated.The study indicated that T.spiralis ML ESP and Ad6 ESP could inhibit the growth of mouse H22 hepatocarcinoma cells and induce their apoptosis.The infection of T.spiralis can upregulated of Bax and Caspase-3 expression in tumor of H22 tumor-bearing mice,increase the level of apoptosis in tumor,and inhibit the further development of H22 hepatocarcinoma cells transplanted tumors in mice. |
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