摘要
AIM: To further investigate the role of human B7 homolog 1 (B7-H1) in the mechanism of persistent hepatitis B virus (HBV) infection. METHODS: Peripheral and intra-hepatic B7-H1 expression were compared by flow cytometry and immunochemical staining between two 2 distinct groups, one being chronic HBV tolerance patients (CHB-T) and the other being acute hepatitis B patients (AHB). B7-H1 mRNA expression level was also compared by real time polymerase chain reaction between CHB-T and AHB patients. The location of intra-hepatic B7-H1 and CD40 expression were analyzed by immunofluorescence. The levels of B7-H1 and CD40 expression on cultured myeloid dendritic cells (mDCs) with or without hepatitis B surface antigen (HBsAg) treatment were analyzed dynamically by flow cytometry. Intracellular interferon-γ (IFN-γ) staining and the stimulatory capacity of mDC of cultured mDC with or without HBsAg treatment were also compared by flow cytometry. RESULTS: Peripheral B7-H1 expression on mDCs was increased significantly in AHB compared to CHB-T patients (P < 0.05). In the liver tissues from CHB-T patients, B7-H1 positive cells were almost absent despite a persistently elevated serum HBsAg load. In contrast, there were indeed increased B7-H1-positive cells in situ in the liver tissue from AHB. In vitro analysis showed the parallel upregulation of B7-H1 and CD40 on CD11c+ mDCs after the onset of stimulation. Addition of recombinant hepatitis B surface antigen (rHBsAg) significantly decreased CD40 expression (P < 0.05 at 16 h, 20 h and 24 h time points). B7-H1 expression was also inhibited by rHBsAg, and the inhibition rate of CD40 was greater than that of B7-H1. This preferential inhibition of CD40 expression on mDCs by rHBsAg resulted in the dysfunction of mDCs and T cells in the mixed leucocyte reaction (MLR) system. With rHBsAg pretreatment, in a carboxyfluorescein diacetate succinimidyl ester (CFSE) labeled MLR system at a ratio of 1:5 responder cell-stimulator cell (R/S), the CFSE dim percentage of T cells decreased from 85.1% to 25.4% and decreased from 30.3% to 12.0% at 1:10 R/S. IFN-γ production by CD8+ T cells, in the MLR system, was reduced significantly by HBsAg pretreatment. At ratios of 1:5 R/S, the percentage of IFN-γ and CD8 dual positive T cells decreased from 55.2% ± 5.3% to 15.1% ±3.1% (P < 0.001), and decreased from 35.0% ± 5.1% to 7.3% ± 2.7% at ratios of 1:10 R/S (P < 0.001). CONCLUSION: B7-H1 is not a signature of immune dysfunction, but an inflammation marker. HBsAg regulate immune response by tipping the balance between B7-H1 and CD40.
AIM： To further investigate the role of human B7 homolog 1 （B7-H1） in the mechanism of persistent hepatitis B virus （HBV） infection. METHODS： Peripheral and intra-hepatic B7-H1 expression were compared by flow cytometry and immunochemical staining between two 2 distinct groups, one being chronic HBV tolerance patients （CHB-T） and the other being acute hepatitis B patients （AHB）. B7-H1 mRNA expression level was also compared by real time polymerase chain reaction between CHB-T and AHB patients. The location of intra-hepatic B7-H1 and CD40 expression were analyzed by immunofluorescence. The levels of B7-H1 and CD40 expression on cultured myeloid dendritic cells （mDCs） with or without hepatitis B surface antigen （HBsAg） treatment were analyzed dynamically by flow cytometry. Intracellular interferon-γ （IFN-γ） staining and the stimulatory capacity of mDC of cultured mDC with or without HBsAg treatment were also compared by flow cytometry. RESULTS： Peripheral B7-H1 expression on mDCs was increased significantly in AHB compared to CHB-T patients （P 0.05）. In the liver tissues from CHB-T patients, B7-H1 positive cells were almost absent despite a persistently elevated serum HBsAg load. In contrast, there were indeed increased B7-H1-positive cells in situ in the liver tissue from AHB. In vitro analysis showed the parallel upregulation of B7-H1 and CD40 on CD11c＋ mDCs after the onset of stimulation. Addition of recombinant hepatitis B surface antigen （rHBsAg） significantly decreased CD40 expression （P 0.05 at 16 h, 20 h and 24 h time points）. B7-H1 expression was also inhibited by rHBsAg, and the inhibition rate of CD40 was greater than that of B7-H1. This preferential inhibition of CD40 expression on mDCs by rHBsAg resulted in the dysfunction of mDCs and T cells in the mixed leucocyte reaction （MLR） system. With rHBsAg pretreatment, in a carboxyfluorescein diacetate succinimidyl ester （CFSE） labeled MLR system at a ratio of 1：5 responder cell-stimulator cell （R/S）, the CFSE dim percentage of T cells decreased from 85.1% to 25.4% and decreased from 30.3% to 12.0% at 1：10 R/S. IFN-γ production by CD8＋ T cells, in the MLR system, was reduced significantly by HBsAg pretreatment. At ratios of 1：5 R/S, the percentage of IFN-γ and CD8 dual positive T cells decreased from 55.2% ± 5.3% to 15.1% ±3.1% （P 0.001）, and decreased from 35.0% ± 5.1% to 7.3% ± 2.7% at ratios of 1：10 R/S （P 0.001）. CONCLUSION： B7-H1 is not a signature of immune dysfunction, but an inflammation marker. HBsAg regulate immune response by tipping the balance between B7-H1 and CD40.
基金
Supported by Key Program of National Natural Science Foundation of China, No. 30730085
Zhejiang Provincial Natural Science Foundation, No. Y2110169
Zhejiang Provincial Natural Science Foundation, No. Y207465
