Ji-Yuan Zhang

Interleukin-17–producing CD4+ T cells increase with severity of liver damage in patients with chronic hepatitis B†

Interleukin‐17 (IL‐17)‐producing CD4+ T cells (Th17)‐mediated immune response has been demonstrated to play a critical role in inflammation‐associated disease; however, its role in chronic hepatitis B virus (HBV) infection remains unknown. Here we characterized peripheral and intrahepatic Th17 cells and analyzed their association with liver injury in a cohort of HBV‐infected patients including 66 with chronic hepatitis B (CHB), 23 with HBV‐associated acute‐on‐chronic liver failure (ACLF), and 30 healthy subjects as controls. The frequency of circulating Th17 cells increased with disease progression from CHB (mean, 4.34%) to ACLF (mean, 5.62%) patients versus healthy controls (mean, 2.42%). Th17 cells were also found to be largely accumulated in the livers of CHB patients. The increases in circulating and intrahepatic Th17 cells positively correlated with plasma viral load, serum alanine aminotransferase levels, and histological activity index. In vitro, IL‐17 can promote the activation of myeloid dendritic cells and monocytes and enhance the capacity to produce proinflammatory cytokines IL‐1β, IL‐6, tumor necrosis factor (TNF)‐α, and IL‐23 in both CHB patients and healthy subjects. In addition, the concentration of serum Th17‐associated cytokines was also increased in CHB and ACLF patients. Conclusion: Th17 cells are highly enriched in both peripheral blood and liver of CHB patients, and exhibit a potential to exacerbate liver damage during chronic HBV infection. (HEPATOLOGY 2009.)

B7-H1 Up-Regulation on Myeloid Dendritic Cells Significantly Suppresses T Cell Immune Function in Patients with Chronic Hepatitis B

Although dysfunctional dendritic cells contribute to inadequate adaptive immunity in chronic hepatitis B (CHB), underlying molecular mechanisms remain largely undefined. In this study, we examined B7-H1 expression on circulating myeloid dendritic cells (mDCs) in 46 CHB patients, 10 autoimmune hepatitis patients, and 10 healthy subjects as control. We found that B7-H1 expression is significantly up-regulated on circulating mDCs of CHB and autoimmune hepatitis patients compared with healthy individuals. The B7-H1 up-regulation was significantly correlated with an elevation of serum alanine aminotransaminase levels and plasma viral load. In addition, in vitro, both IFN-α and IFN-γ could strongly stimulate mDCs to express B7-H1. More importantly, elevated B7-H1 expression is also closely associated with the suppression of T cell immune function. In vitro blockade of B7-H1 signaling could not only down-regulate IL-10 and up-regulate IL-12 production by mDCs, but also enhance mDC-mediated allostimulatory capacity and cytokine production of T cells. Blockade of B7-H1 signaling could improve hepatitis B c Ag-pulsed monocyte-derived DC-induced IFN-γ production by autologous hepatitis B virus-specific T cells. These new findings suggested that chronic inflammation may contribute to B7-H1 up-regulation on mDCs in CHB patients, which potentially cause defective hepatitis B virus-specific T cell function and viral persistence. Our findings further support the notion that the blockade of B7-H1 may represent a novel therapeutic approach for this disease.

Hypercytolytic activity of hepatic natural killer cells correlates with liver injury in chronic hepatitis B patients.

Natural killer (NK) cells are abundant in the liver and serve as a major innate immune component against microbial infection. Although NK cells have been implicated in inducing hepatocellular damage in patients with chronic hepatitis virus infections, the roles that hepatic NK cells play in chronic hepatitis B virus (HBV) infections remain obscure. In this study, we comprehensively characterized intrahepatic and peripheral NK cells and investigated their impact on liver pathology in a cohort of HBV‐infected individuals; this cohort included 51 immune‐activated (IA) patients, 27 immune‐tolerant (IT) carriers, and 26 healthy subjects. We found that NK cells expressing NK receptors (activation receptors) preferentially accumulated in the livers of IA patients, in which they were activated and skewed toward cytolytic activity but without a concomitant increase in interferon‐γ production, in comparison with those of IT carriers and healthy subjects. Further analysis showed that the livers of IA patients, in comparison with those of IT and healthy subjects, expressed higher levels of interleukin‐12 (IL‐12), IL‐15, and IL‐18 in situ and lower levels of IL‐10, which in vitro can induce the activation and degranulation of NK cells from healthy individuals. Finally, hepatic NK cells displayed more cytolytic activity than peripheral NK cells, and this was found to be positively correlated with the liver histological activity index and serum alanine aminotransferase levels in these IA patients. Conclusion: In IA patients, hepatic NK cells are activated and preferentially skew toward cytolytic activity, which depends on an imbalanced cytokine milieu and correlates with liver injury during chronic HBV infection. (HEPATOLOGY 2011)

The decrease of regulatory T cells correlates with excessive activation and apoptosis of CD8+ T cells in HIV-1-infected typical progressors, but not in long-term non-progressors

Persistent HIV infection results in a decrease in absolute counts of CD4+ CD25+ regulatory T cells (Treg). To investigate the role of decreased Treg counts in the regulation of excessive activation and apoptosis of CD8+ T cells in human immunodeficiency virus (HIV)‐1 infection, we characterized Treg in 83 HIV‐1‐infected individuals, including 19 long‐term non‐progressors (LTNPs) and 51 typical progressors (TPs) who were treatment‐naïve, and 13 AIDS patients on highly active antiretroviral therapy (HAART), of whom nine were complete responders (CRs) and the remaining four were non‐responders (NRs) to the treatment. TPs but not LTNPs had a significant decrease in absolute counts of circulating Treg, which was inversely correlated with the activation and apoptosis of CD8+ T cells. Efficient HAART was found to increase Treg counts in CR patients and temper the excessive activation and apoptosis of CD8+ T cells. Moreover, isolated Treg significantly inhibited the spontaneous and anti‐CD3‐induced apoptosis of CD8+ T cells in a dose‐dependent manner in vitro. Thus, our findings indicate that the decrease in Treg closely correlates with the increase in apoptotic CD8+ T cells and disease progression in chronic HIV‐1 infection, and that Treg may play a key role in maintaining the balance between the amount and quality of CD8+ T cells in HIV‐1 infection. Manipulation of Treg function may be a promising strategy for immune therapy of this disease.

Hyper-Activated Pro-Inflammatory CD16+ Monocytes Correlate with the Severity of Liver Injury and Fibrosis in Patients with Chronic Hepatitis B

Background Extensive mononuclear cell infiltration is strongly correlated with liver damage in patients with chronic hepatitis B virus (CHB) infection. Macrophages and infiltrating monocytes also participate in the development of liver damage and fibrosis in animal models. However, little is known regarding the immunopathogenic role of peripheral blood monocytes and intrahepatic macrophages. Methodology/Principal Findings The frequencies, phenotypes, and functions of peripheral blood and intrahepatic monocyte/macrophage subsets were analyzed in 110 HBeAg positive CHB patients, including 32 immune tolerant (IT) carriers and 78 immune activated (IA) patients. Liver biopsies from 20 IA patients undergoing diagnosis were collected for immunohistochemical analysis. IA patients displayed significant increases in peripheral blood monocytes and intrahepatic macrophages as well as CD16+ subsets, which were closely associated with serum alanine aminotransferase (ALT) levels and the liver histological activity index (HAI) scores. In addition, the increased CD16+ monocytes/macrophages expressed higher levels of the activation marker HLA-DR compared with CD16− monocytes/macrophages. Furthermore, peripheral blood CD16+ monocytes preferentially released inflammatory cytokines and hold higher potency in inducing the expansion of Th17 cells. Of note, hepatic neutrophils also positively correlated with HAI scores. Conclusions These distinct properties of monocyte/macrophage subpopulations participate in fostering the inflammatory microenvironment and liver damage in CHB patients and further represent a collaborative scenario among different cell types contributing to the pathogenesis of HBV-induced liver disease.

Decreased ratio of Treg cells to Th17 cells correlates with HBV DNA suppression in chronic hepatitis B patients undergoing entecavir treatment.

Background Treatment with nucleotide analogs is known to be effective in inhibiting HBV replication; however, patients with chronic hepatitis B (CHB) often show a wide range of clinical responses to these drugs. Therefore, the identification of an early immunologic marker associated with the clinical outcomes in such cases is critical for the improved clinical management. In our study, we aimed to investigate whether the viral load in CHB patients affected the ratio of the number of regulatory T cells (Tregs) to the number of interleukin-17-producing helper (Th17) cells. Further, we evaluated the clinical implications of the alterations in this ratio. Methodology/Principal Findings Nine patients seropositive for hepatitis B e antigen received entecavir monotherapy for 12 months and the percentages of Tregs and Th17 cells as well as the HBV-specific IL-17 productions in these patients were longitudinally analyzed. The entecavir-induced suppression of HBV replication was accompanied by a rapid increase in the number of Th17 cells, together with a decrease in Treg cells, which lead to a significant reduction of Treg/Th17 ratios. In addition, peripheral blood mononuclear cells (PBMCs) exhibited a decreased IL-17 production upon stimulation with the HBV core antigen in vitro. Conclusions The inhibition of viral replication results in an increase in Th17 cells and concomitant decrease in Treg cells. This imbalance of Treg cells to Th17 cells might have an important role in HBV persistence during entecavir treatment.

Impairment of CD4+ cytotoxic T cells predicts poor survival and high recurrence rates in patients with hepatocellular carcinoma.

The role of CD4+ cytotoxic T cells (CTLs) in hepatocellular carcinoma (HCC) remains obscure. This study characterized CD4+ CTLs in HCC patients and further elucidated the associations between CD4+ CTLs and HCC disease progression. In all, 547 HCC patients, 44 chronic hepatitis B (CHB) patients, 86 liver cirrhosis (LC) patients, and 88 healthy individuals were enrolled in the study. CD4+ CTLs were defined by flow cytometry, immunohistochemistry, and lytic granule exocytosis assays. A multivariate analysis of prognostic factors for overall survival was performed using the Cox proportional hazards model. Circulating and liver‐infiltrating CD4+ CTLs were found to be significantly increased in HCC patients during early stage disease, but decreased in progressive stages of HCC. This loss of CD4+ CTLs was significantly correlated with high mortality rates and reduced survival time of HCC patients. In addition, the proliferation, degranulation, and production of granzyme A, granzyme B, and perforin of CD4+ CTLs were inhibited by the increased forkhead/winged helix transcription factor (FoxP3+) regulatory T cells in these HCC patients. Further analysis showed that both circulating and tumor‐infiltrating CD4+ CTLs were independent predictors of disease‐free survival and overall survival after the resection of the HCC. Conclusion: The progressive deficit in CD4+ CTLs induced by increased FoxP3+ regulatory T cells was correlated with poor survival and high recurrence rates in HCC patients. These data suggest that CD4+ CTLs may represent both a potential prognostic marker and a therapeutic target for the treatment of HCC. (HEPATOLOGY 2013)

Immunopathogenesis and prognostic immune markers of chronic hepatitis B virus infection

Host immune responses induced by hepatitis B virus (HBV) infection not only substantially drive disease progression, but also significantly influence efficacy of antiviral treatments in HBV‐infected individuals. Therefore, it is important to fully understand the course of immune pathogenesis and to find efficient immunological markers that can predict the disease progression of chronic HBV infection. This review introduces the current progress in clinical immunology and analyzes the mechanisms of antiviral effects and liver injury, which are induced by both innate and adaptive immune responses. The recently identified immunological markers indicated to be closely correlated with disease progression and antiviral efficacy during HBV infection are also summarized. Careful monitoring of these immune markers may help physicians to make decisions on when to begin or withdraw antiviral drugs, or to formulate the prognosis of acute‐on‐chronic liver failure (ACLF) patients in the clinic. Finally, this review highlights some novel therapeutic strategies to modulate host immunity that have been proposed to sustain antiviral control of chronic HBV infection, as well as the challenges that we are presently facing in the field.

Increased turnover of FoxP3high regulatory T cells is associated with hyperactivation and disease progression of chronic HIV-1 infection.

Objectives:To characterize the homeostasis of CD4+FoxP3high regulatory T cells (Treg) and its association with immune hyperactivation in the disease progression of chronic HIV-1 infection. Design:Treg proliferation and apoptosis markers were determined and the relation to disease progression and Treg activation was analyzed. Methods:Fifty-six HIV-1-infected highly active antiretroviral therapy (HAART)-naive subjects and 17 HAART-treated subjects were enrolled. Proliferation and apoptosis of Treg from peripheral blood were evaluated by intracellular Ki-67 and active caspase-3 or surface Annexin-V staining. T-cell activation markers, CD38 and HLA-DR, were simultaneously monitored. The effects of in vitro TCR (T cell receptor) stimulation on proliferation, apoptosis, and activation of Treg were determined from both HIV-1-infected subjects and healthy controls. Results:HIV-1-infected patients displayed increased Treg turnover status indicated by higher expression of proliferation marker Ki-67 and apoptosis marker active caspase-3 and Annexin-V. Turnover level of Treg was positively associated with disease progression and immune hyperactivation. In vitro TCR stimulation increased the turnover level of Treg. The HAART treatment decreased the turnover and activation levels of Treg in complete responders. Conclusions:Turnover level of Treg was increased in HIV-1-infected subjects, which is associated with immune hyperactivation and the disease progression, and may serve as a surrogate marker to predict HIV-1 disease progression.

Dynamic decrease in PD-1 expression correlates with HBV-specific memory CD8 T-cell development in acute self-limited hepatitis B patients

BACKGROUND/AIMS Programmed death-1 (PD-1) upregulation can impair virus-specific CD8 T-cell responses during chronic viral infection. Whether and how PD-1 affects virus-specific memory CD8 T cells in humans with acute viral infection, however, remains largely undefined. METHODS The association between PD-1 expression and HBV-specific memory CD8 T-cell responses were longitudinally analyzed in eighteen patients with acute hepatitis B virus (HBV) infection, including ten patients with human leucocyte antigen (HLA)-A201 and eight with other HLA-A2 subtypes. RESULTS At clinical onset, PD-1 was significantly up-regulated and subsequently led to the functional suppression of HBV-specific effector CD8 T cells, as blocking PD-1/PD-L1 interactions in vitro enhanced their proliferation and IFN-gamma production. Following disease resolution, HBV-specific effector CD8 T cells developed into memory T cells. During this period, the dynamic PD-1 decrease was numerically correlated with the reduction of HBV-specific CD8 T-cell frequency, phenotypically with an acquisition of CCR7, CD45RA and CD127 expressions, and functionally with the increase in proliferation and IFN-gamma production of the memory T cells. CONCLUSIONS PD-1-mediated inhibitory signaling not only attenuates HBV-specific CD8 T-cell effector function during the acute phase of infection but also correlates with the development of HBV-specific memory CD8 T cells following disease resolution.