Chronic hepatitis B virus (HBV) infection is associated with functionally impaired virus-specific T cell responses. Although the myeloid-derived suppressor cells (MDSCs) are known to play a critical role in impairing antiviral T cell responses, viral factors responsible for the expansion of MDSCs in chronic hepatitis B (CHB) remain obscure. In order to elucidate the mechanism of monocytic MDSCs (mMDSCs) expansion and T cell function suppression during persistent HBV infection, we analyzed the circulation frequency of mMDSCs in 164 CHB patients and 70 healthy donors, and found that the proportion of mMDSCs in HBeAg (+) CHB patients was significantly increased compared to that in HBeAg (-) patients, which positively correlated with the level of HBeAg. Furthermore, exposure of peripheral blood mononuclear cells (PBMCs) isolated from healthy donors to HBeAg led to mMDSCs expansion and significant upregulation of IL-1β, IL-6 and indoleamine-2, 3-dioxygenase (IDO), and depletion of the cytokines abrogated HBeAg-induced mMDSCs expansion. Moreover, HBeAg-induced mMDSCs suppressed the autologous T-cell proliferation in vitro, and the purified mMDSCs from HBeAg (+) subjects markedly reduced the proliferation of CD4⁺ and CD8⁺ T cells and IFN-γ production, which could be efficiently restored by inhibiting IDO. In summary, HBeAg-induced mMDSCs expansion impairs T cell function through IDO pathway and favors the establishment of a persistent HBV infection, suggesting a mechanism behind the development of HBeAg-induced immune tolerance. HBeAg is not a structural component of HBV and is not essential for viral DNA replication, however, HBeAg positivity is associated with high levels of viremia in patients. HBeAg may represent a viral strategy to establish persistent infection, but the mechanism remains largely ambiguous. Growing evidence suggests that chronic HBV infection may be shaped by MDSCs-mediated T-cell exhaustion. Here, we report that the frequency of circulating mMDSCs in HBeAg (+) patients is higher than HBeAg (-) patients and positively correlates with serum HBeAg levels. The correlation is further demonstrated by in vitro HBeAg stimulation of PBMCs, which induced mMDSCs expansion. Furthermore, HBeAg-induced expansion of mMDSCs is dependent upon cytokine IL-6 and IL-1β, and the indoleamine-2, 3-dioxynase (IDO) plays a critical role in the suppression of T cell proliferation and IFN-γ production by HBeAg-activated mMDSCs. Therefore, our findings demonstrate a novel mechanism responsible for mMDSCs expansion in HBeAg (+) patients, and suggest that the HBeAg-mMDSC-IDO axis may serve as an immunotherapeutic target of chronic hepatitis B.

B- and T-lymphocyte attenuator (BTLA) levels are increased in patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF). This condition is characterized by susceptibility to infection and T-cell immune exhaustion. However, whether BTLA can induce T-cell immune exhaustion and increase the risk of infection remains unclear. Here, we report that BTLA levels are significantly increased in the circulating and intrahepatic CD4⁺ T cells from patients with HBV-ACLF, and are positively correlated with disease severity, prognosis, and infection complications. BTLA levels were upregulated by the IL-6 and TNF signaling pathways. Antibody crosslinking of BTLA activated the PI3K-Akt pathway to inhibit the activation, proliferation, and cytokine production of CD4⁺ T cells while promoting their apoptosis. In contrast, BTLA knockdown promoted their activation and proliferation. BTLA^-/- ACLF mice exhibited increased cytokine secretion, and reduced mortality and bacterial burden. The administration of a neutralizing anti-BTLA antibody reduced Klebsiella pneumoniae load and mortality in mice with ACLF. These data may help elucidate HBV-ACLF pathogenesis and aid in identifying novel drug targets.

Background: CDCA5 plays an important role in the development of various human cancers, but the associated mechanisms have not been investigated in hepatocellular carcinoma (HCC). Materials and methods: We evaluated expression levels and functions of CDCA5 in HCC and showed that CDCA5 is upregulated in HCC tissues compared with paired or unpaired normal liver tissues. Results: Increased CDCA5 expression in HCCs was significantly associated with shorter survival of patients. Knockdown of CDCA5 using lentivirus-mediated shRNA significantly inhibited cell proliferation and suppressed cell survival, as well as induced cell cycle arrest at the G2/M phase and cell apoptosis of HCC cells. The tumor suppression effects of CDCA5 knockdown were mediated by decreased expression of cyclin-dependent kinase 1 (CDK1) and CyclinB1, which were increased in HCC tissues comparing with adjacent normal liver tissues. Moreover, upregulation of CDCA5 was positively associated with increased CDK1 and CyclinB1 expression in HCC tissues. Conclusion: The present data warrant consideration of CDCA5 as a prognostic biomarker and therapeutic target for HCC.

The natural history of chronic hepatitis B virus (HBV) infection was divided into 4 phases. Patients in the inactive carrier (IC) status and immune tolerant (IT) phase had normal alanine aminotransferase levels but huge different viral loads. The mechanism underlying low viral replication status in IC phase is unknown. We determined the intrahepatic transcriptomes of 83 chronic hepatitis B patients by microarray analysis of liver biopsies, and screened the effect of differentially regulated genes on HBV replication using specific small interfering RNAs in vitro. The gene profile distinguishing active chronic hepatitis from IT and IC was predominantly composed of immune-related genes. The liver transcriptomes between the IT and IC phase were largely similar, and 109 expressed genes were significantly different. By performing systematic screening, 5 candidate genes including EVA1A, which were expressed at a relative higher level in IC phase than IT, were identified to regulate HBV replication and gene expression in cellular models. The immune-related pathways were up-regulated in the active chronic hepatitis phase but not in the IT and IC phase. A number of intrahepatic genes highly expressed in the IC phase may participate in the control of HBV replication and determine the inactive status of HBV infection.

The proinflammatory cytokines transforming growth factor beta 1 (TGF-β1) and interleukin (IL)-31 have been implicated in tissue injury. However, whether TGF-β1/IL-31 are stimulated and elevated in response to liver injury that leads to fibrogenesis in hepatitis B virus-related liver cirrhosis (HBV-LC) remains unclear. To investigate the association between TGF-β1/IL-31 and stages of chronic HBV infection, serum TGF-β1, IL-9, IL-10,IL-17, IL-22, IL-23, IL-31, IL-33, and IL-35 were determined among patients with chronic hepatitis B (CHB; n=19), HBV-LC (n=20), and a normal control population (NC; n=18). Disease severity in patients with HBV-LC was assessed using model for end-stage liver disease (MELD) scores. Serum TGF-β1 and IL-31 levels were strongly positively linked in all subjects, and both correlated positively with IL-22, IL-33, and IL-17. TGF-β1 and IL-31 levels in the blood were both significantly higher in CHB and HBV-LC patients than in NC subjects. Elevated serum TGF-β1 and IL-31 levels were positively associated with albumin, alpha-fetoprotein, creatinine, white blood cell count, and platelet levels. Serum TGF-β1 and IL-31 were markedly higher in HBV-LC patients who did not have esophageal varices, and IL-31 had the highest sensitivity and specificity (90.9% and 66.7%, respectively) for indicating the absence of this complication. In summary, TGF-β1 and IL-31 were linked to progression from CHB to LC, and correlated well with the severity of HBV-LC. These findings suggest possible roles of the TGF-β1/IL-31 pathway in the pathogenesis of liver fibrosis during chronic HBV infection.