Interleukin-22 And Antioxidant Capacity In Hepatitis B Virus-Associated Hepatocellular Carcinoma

BackgroundPrimary liver cancer is the third most common cause of cancer-related death and rank sixth in terms of incidences.The most common pathological type is hepatocellular carcinoma(HCC)whose proportion is approaching 75-85%in primary liver cancer.Hepatocarcinogenesis pathogenic factors are diverse and complex,containing hepatitis B virus(HBV),hepatitis C virus(HCV),autoimmune liver disease(ALD),nonalcoholic fatty liver disease(NAFLD),infection and so on.Chronic HBV infection is the most common pathogenic factor in our country.Intracellular Reactive oxygen species(ROS)can induce DNA mutations and cancer signaling pathways thereby participating in the growth and proliferation of tumor cells.In order to balance the high ROS in vivo,the body will activate the antioxidant system,such as Glutathione Peroxidase(GPx),Glutathione-s-transferases(GST),Superoxide dismutase 1(SOD1),etc.Interleukin-22(IL-22),a member of the interleukin-10 family cytokine,has been proven to inhibit oxidative stress in the liver.We speculate that IL-22 may have potential clinical value as a therapeutic target through oxidative stress.AimsDetect the IL-22 mRNA expression level in peripheral mononuclear cells(PBMCs)of HCC,Chronic hepatitis B(CHB)patients and Healthy controls(HCs),and assess the relationship between IL-22 and antioxidant capacity in participants’ plasma.Then detect the relationship between antioxidant capacity and IL-22 co-culture concentration in HepG2 cell lines and evaluate the possibility of IL-22 as a potential therapeutic target.Methods53 patients with HBV-associated HCC,50 patients with chronic hepatitis B(CHB)and 24 healthy controls(HCs)were enrolled in this study.IL-22 mRNA expression level in peripheral mononuclear cells(PBMCs)was quantitatively detected by real-time quantitative polymerase chain reaction(RT-qPCR).Enzyme-linked immunosorbent assay(ELISA)was used to detect the Total antioxidant capacity(TAC)、Glutathione S-Transferase(GST)、Glutathione Peroxidase(GPx)>copper/zinc SOD(SOD1)in plasma.HepG2 cells were inoculated in 25T culture flask with complete medium and cultured in an incubator of 37℃ and 5%CO2.When the cell density reached approximately 80%,the cells were dealt with various concentrations of IL-22 in the medium without fetal bovine serum(FBS)for 72 hours,and then the antioxidant capacity was measured in the supernatant.Results1.Basic clinical characteristics of subjects:There were no statistically significant differences in gender(P=0.231)and age(P=0.056),but it had statistically significant differences in ALT,AST,ALB,TBIL,WBC and PLT among the three groups(P<0.001).In HCC group and CHB group,PTA(P=0.032),AFP(P<0.001),HBeAg(P=0.002)and HBV-DNA(P=0.032)were statistically significant,but PT-INR(P=0.109)and HBsAg(P=0.116)had no obviously statistical significance.2.The IL-22 mRNA expression level was obviously significantly lower in HCC group(median 0.0049,interquartile range 0.0006～0.0278)than that in CHB(median 0.0089,interquartile range 0.0052～0.0336,P=0.038)and HCs group(median 0.0897,interquartile range 0.0312～0.3216,P<0.001).The mRNA expression level of IL-22 was statistically significantly lower in CHB group than HCs group(P=0.006).3.IL-22 mRNA expression level in HCC was negatively correlated with PLT(Spearman’s r=-0.345,P=0.011)in peripheral blood,but had no significant differences in the expression of WBC,AIL,AST,ALB,TBIL,PT-INR,PTA,AFP and HBsAg expression.There were no statistically significant differences in HBeAg expression(+,-),HBV-DNA expression,gender(male,female),age(>50 years old,≤50 years old),smoking(+,-),alcohol consumption(+,-),ascites(+,-),tumor numbers(single or multiple),Child-Pugh stage(A,B,C),TNM stage(Ⅰ/Ⅱ,Ⅲ/Ⅳ)and BCLC stage(0/A/B,C/D)(P>0.05).4.The total antioxidant capacity(TAC)(Spearman’s r=0.227,P=0.04),Glutathione Peroxidase(GPx)(Spearman’s r=0.279,P=0.015)and Glutathione S-Transferase(GST)(Spearman’s r=0.3,P=0.01)in plasma were significantly positively correlated with IL-22 mRNA level.There was no significant correlation between Superoxide dismutase 1(SOD1)and IL-22 mRNA level(Spearman’s r=-0.181,P=0.152).5.It is absolutely obvious that some antioxidant ability including SOD1(Spearman’s r=1,P<0.01)and GPx(Spearman’s r=0.9,P=0.037)were significantly positively correlated with the co-culture concentration of IL-22 in HepG2 cell line,but some other antioxidant ability such as TAC(Spearman’s r=0.7,P=0.188)and GST(Spearman’s r=0.3,P=0.624)had no significant correlation.Conclusions1.The IL-22 mRNA expression level in PBMCs of HCC was significantly lower than that of CHB and HCs group,suggesting that the low expression of IL-22 mRNA may be involved in the occurrence of HCC.2.The TAC,GPx,and GST in plasma were positively correlated with IL-22 mRNA level,indicating that IL-22 may be enrolled in the regulation of the antioxidant process of oxidative stress.3.In cell experiments,some antioxidant capacity we detected including SOD1 and GPx were positively correlated with the co-culture concentration of IL-22.It is suggested that IL-22 may participate in the antioxidant capacity of hepatocellular carcinoma.4.IL-22 regulates oxidative stress through some mechanism,suggesting that IL-22 may be a potential therapeutic target for HCC through oxidative stress pathway.