| Objective:HBV,a member of hepatotropic virus family,can cause adverse outcomes by chronic HBV infection include chronic hepatitis,cirrhosis and hepatocellular carcinoma(HCC).HBV does not have directly cytopathic effect on the hepatocytes.The disturbed immune response to viral antigens or virus and the inflammatory processes initiated by host immunity when eliminating the virus is mostly thought to be responsible for chronic liver damages in patients with HBV infection.However,little is known about the role of innate immunity in the pathological mechanisms underlying the progression of chronic hepatitis B(CHB).Absent in melanoma 2(AIM2)is a recently recognized cytoplasmic receptor,recognizing double-stranded DNA(dsDNA).AIM2 can bind to dsDNA and associates with the adaptor molecule ASC(apoptosis-associated speck-like protein containing a CARD),which contains a caspase activation and recruitment domain.As a result,AIM2 inflammasome is formed.This complex then activates caspase-1(CASP-1)and leads to the formation of mature interleukin 1?(IL-1?)and interleukin18(IL-18).In this study,we assayed the hepatic AIM2 expression and investigated the mRNA expression of AIM2 in liver tissues and peripheral blood mononuclear cells(PBMCs)in patients with CHB and HBV related acute-on-chronic liver failure(ACLF),in order to elucidate whether AIM2 might be in involved in the detection of HBV in hepatocytes and be associated with innate immunity and inflammatory response after HBV infection,thus leading to inflammatory damages of liver.Methods:A total 73 subjects were enrolled in our study and divided into3 groups including 30 CHB patients,23 HBV related ACLF patients and 20 healthy controls.All of the patients were randomly selected from the inpatients or outpatients of the Third Hospital of Hebei Medical Universityfrom June 2015 to December 2016,and the controls were also recruited from the medical examination center of the very hospital at the same period.Meanwhile,we collected 21 liver tissues of the CHB patients who underwent liver biopsy,19 liver tissues of the HBV related ACLF patients who received liver transplantation and 5 liver tissues of liver donors during liver transplantation.None received immunotherapy,anti-HBV or hepatitis B vaccine treatment for 6 months prior to enrollment.All of the CHB and HBV related ACLF patients were diagnosed according to the Guidelines on Prevention and Treatment for Chronic Hepatitis B in China(2015 edition)or the Diagnostic and Treatment Guidelines for Liver Failure(2012 edition)developed by the Chinese Society of Hepatology and the Chinese Society of Infectious Disease respectively.We examined the regular serum biochemical indexes along with HBV DNA load,and valued the serum levels of Hepatitis B Virus Surface Antigen(HBs Ag)and Hepatitis B Virus e Antigen(HBeAg).Then we measured the expression of AIM2 in liver tissue by immunehistochemical staining and detected the mRNA expression of AIM2 in liver tissue as well as in PBMCs by quantitative real-time polymerase chain reaction.Results:1 Demographic and clinical characteristics of the studied subjects including people groups of CHB,HBV related ACLF and healthy control.The ages and sex ratio were no significantly different for the chosen healthy control people group compared with that of patient groups.CHB patients had obviously higher levels of the serum albumin(ALB),HBV DNA loading,Hepatitis B Virus Surface Antigen(HBsAg),Hepatitis B Virus e Antigen(HBeAg)in blood than that of HBV related ACLF patients and healthy controls(P<0.05 for both conditions),but the serum total bilirubin(TBIL),direct bilirubin(DBIL),international normalized ratio(INR)levels are much lower compared with that of the HBV related ACLF patients(P <0.01).And there is no significant difference for alanine transaminase(ALT),aspartate transaminase(AST)between the CHB patients and HBV relatedACLF patients(P > 0.05).2 The expression of AIM2 mRNA was higher in PBMC of the CHB patients.The studied subjects received AIM2 mRNA expressions detection in PBMC by Quantitative real time PCR.The relative quantitative expressions of AIM2 mRNA in control group were set to 1.00.And the results were: the AIM2 mRNA expression was significantly higher for the CHB patients(4.426± 5.395)than that of HBV related ACLF patient(2.077 ± 1.291)and control(1.00 ± 0.00)groups.There was significant difference between each group(all P < 0.01).3 The expression of AIM2 was higher in liver tissues of the CHB patients.The studied subjects received AIM2 mRNA expressions detection in liver tissues by Quantitative real time PCR.The relative quantitative expressions of AIM2 mRNA in control group were set to 1.00.And the results were: the AIM2 mRNA expression was significantly higher for the CHB patients(3.231± 2.005)than that of HBV related ACLF patients(1.598 ± 0.662)and control(1.00 ± 0.00)groups.There was significant difference between each group(all P < 0.01).The immune-histochemical staining was performed to measure the expression of AIM2 in liver tissues.The IHC detection demonstrated that AIM2 widely expressed in the cytoplasm of hepatocytes.AIM2 expression was increased in HBV-infected liver tissues,but nearly not was in the normal hepatocytes.Hepatic AIM2 expressions were higher in CHB patients than that of HBV related ACLF patients and healthy controls,and control group were the lowest.4 Correlation analysis of AIM2 mRNA in PBMC of CHB patients with clinical indexes.The AIM2 mRNA levels in PBMC were positively correlated with serum ALT levels(r = 0.575,P < 0.01)and AST levels(r = 0.563,P<0.01)in CHB patients.The AIM2 mRNA levels in PBMC were respectively found negatively correlated with HBV DNA levels(r=-0.663,P<0.01),HBs Aglevels(r =-0.622,P < 0.01),and HBeAg levels(r =-0.431,P < 0.01)in CHB patients.Conclusion:1 AIM2 expression in liver tissues and PBMC is higher in CHB patients than that of HBV related ACLF patients,for which CHB may have a higher AIM2 related innate immune response to HBV infection.2 Cytoplasmic HBV DNA could potentially be recognized by AIM2,leading to the AIM2 inflammasome formation,and ultimately inducing the innate immune responce to HBV infection,further suggesting that AIM2 may play an important role in the pathogenesis of liver inflammatory dameges underlying the progression of CHB. |
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