Jian-Qi Lian

Overexpression of Toll-like receptor 2/4 on monocytes modulates the activities of CD4(+)CD25(+) regulatory T cells in chronic hepatitis B virus infection.

The significance of TLR expression and Tregs in HBV infection has not been clearly described. In this report, flow cytometry was performed to assess TLR2/4 expression on monocytes and circulating CD4(+)CD25(+)CD127(low/-) Tregs frequency of 16 acute hepatitis B (AHB), 42 chronic hepatitis B (CHB), 22 asymptomatic HBV carriers (AsC), and 20 normal controls (NC). We found that TLR2 and TLR4 were overexpressed on CD14(+) monocytes in HBV-infected patients as compared with NCs. Upregulation of TLR2 in NCs and TLR4 in CHBs was observed following HBeAg incubation. However, TLR2 and TLR4 expression decreased after HBcAg stimulation. The difference in the proportion of Tregs between NCs and CHBs was significant. Both Pam3Csk4 (TLR2 agonist)- and lipopolysaccharide (TLR4 agonist)-activated CD4(+)CD25(+) Tregs showed enhanced suppression function in CHBs. These results suggest that overexpression of TLR2 and TLR4 may modulate the suppressive function of Tregs, which contribute to the immunotolerance of chronic HBV infection.

Hantaan virus induces toll-like receptor 4 expression, leading to enhanced production of beta interferon, interleukin-6 and tumor necrosis factor-alpha

Hantaan virus (HTNV) infects endothelial cells and is associated with increased vascular permeability during hemorrhagic fever with renal syndrome (HFRS). The pattern of increased vascular permeability is mediated by immune response. Therefore, it is necessary to characterize the mechanism of HTNV involvement in the hosts innate immune. In this study, the expression of five toll-like receptors (TLRs) was analyzed in Endothelial vein cells (EVC-304) following HTNV infection in vitro. TLR4 showed an altered expression after HTNV infection. HTNV infection significantly increased IFN-beta, IL-6 and TNF-alpha secretion from EVC-304 cells, particularly after lipopolysaccharide stimulation. The increased IFN-beta, IL-6 and TNF-alpha production was mediated by TLR4 induction, since the introduction of the small interfering RNA against TLR4 specifically inhibited the HTNV-induced cytokine production. In conclusion, HTNV infection directly induces TLR4 expression and thereby enhanced production of IFN-beta, IL-6 and TNF-alpha, which may contribute to the hosts innate immune response.

Inhibition of Viral Replication Downregulates CD4+CD25high Regulatory T Cells and Programmed Death-Ligand 1 in Chronic Hepatitis B

Chronic hepatitis B is characterized by an impaired immune response to hepatitis B virus (HBV). Telbivudine treatment has significantly improved the clinical outcome of chronic HBV infection. However, the underlying mechanism behind the antiviral response of patients treated with nucleoside analogs remains unclear. To gather more evidence about the mechanism responsible for the weak immune response, in this study we analyzed the effects on HBV viral load of treatment with the nucleoside analogue telbivudine and the percentage of Tregs, programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) expression, and related cytokine production. Peripheral blood mononuclear cells (PBMCs) and serum of 28 patients with chronic hepatitis B were collected at baseline, and 3 mo and 6 mo after therapy was begun. In parallel with the decline in viral load and serum ALT normalization, we found a decline in circulating CD4(+)CD25(high) Tregs, PD-L1 on CD4(+) T cells, and IL-9 production. The expression of PD-1 on CD4(+) T cells and the production of IFN-γ did not increase during therapy. Our findings suggest that the antiviral effect of the nucleoside analogs may be attributable not only to their direct effect on virus suppression, but also to their immunoregulatory capabilities.

Imbalance of regulatory T cells and T helper type 17 cells in patients with chronic hepatitis C.

Pegylated interferon and ribavirin combination therapy is known to be effective in suppressing viral replication in 50–60% of hepatitis C virus (HCV) ‐infected patients. However, HCV‐infected patients often exhibit varied responses to therapy. Therefore, the identification of immunological markers associated with the clinical outcomes of antiviral treatment is critical for improvement of therapeutic options. In this study, we aimed to investigate the ratio of CD4+ CD25+ FoxP3+ regulatory T (Treg) cells to interleukin‐17A (IL‐17A) ‐producing T helper type 17 (Th17) cells, and its association with clinical outcomes in response to anti‐HCV treatment. In all, 114 patients with HCV infection received pegylated interferon‐α2a and ribavirin therapy for 48 weeks, and the frequency of Treg cells and Th17 cells as well as the levels of secreted cytokines were longitudinally analysed by flow cytometry and ELISA. Treg cell proportions and IL‐10 production were significantly elevated in HCV‐infected patients, especially for HCV genotype 1b. However, the frequency of Th17 cells as well as the secretion of IL‐17, IL‐22 and IL‐23 did not reveal notable difference between HCV infections and healthy individuals. Inhibition of HCV replication was accompanied by a reduction in Treg cells, but little influence on Th17 cells, which led to a significant decrease in Treg : Th17 ratios. Skewed Treg : Th17 ratios existed in chronic hepatitis C. HCV RNA load is closely associated with Treg : Th17 ratios during pegylated interferon‐α2a and ribavirin treatment in HCV‐infected patients. The imbalance of Treg cells to Th17 cells might play an important role in persistent HCV infection.

Correlation of Circulating TLR2/4 Expression with CD3+/4+/8+ T Cells and Treg cells in HBV-Related Liver Cirrhosis

Toll-like receptors (TLRs) 2 and 4 play a key role in chronic hepatitis B virus (HBV) infection. However, the role of TLRs in the pathogenesis of HBV-related liver cirrhosis and their regulation of the innate immune response of patients with liver cirrhosis remain unknown. To assess the contribution of TLR2/4 in HBV-related liver cirrhosis, we examined the expression of circulating TLR2 and TLR4 on peripheral blood mononuclear cells (PBMCs), CD4(+)CD25(+)CD127(low/-) Treg proportions, and CD3(+)/CD4(+)/CD8(+) T-cell counts in 30 liver cirrhosis patients, 21 chronic hepatitis B (CHB) patients, and 16 normal controls (NC). Furthermore, we analyzed the relationship between TLR2/4 expression and Treg proportions and T-cell counts. We show that the expression of TLR2 and TLR4 was significantly upregulated in patients with liver cirrhosis compared to NC. TLR4 expression was significantly increased in patients with liver cirrhosis compared to patients with CHB, and for TLR2 expression there were no differences between them. TLR4 expression showed a significant positive correlation with the frequency of Tregs in liver cirrhosis patients. TLR2 expression negatively correlated with CD3(+)/CD4(+)/CD8(+) T-cell counts and HBV viral load in patients with liver cirrhosis. These findings indicate that TLR may be involved in the pathogenesis of HBV-related liver cirrhosis, and may interact with Tregs and CD3(+)/CD4(+)/CD8(+) T cells in the immune response during HBV-related liver cirrhosis.

In Vitro Hepatic Differentiation of Mesenchymal Stem Cells from Human Fetal Bone Marrow

We examined whether human fetal mesenchymal stem cells (FMSCs) derived from fetal bone marrow were able to differentiate into functional hepatocyte-like cells in vitro The surface phenotype of FMSCs was characterized by flow cytometry. To induce hepatic differentiation of FMSCs, we added hepatocyte growth factor, basic fibroblast growth factor and oncostatin M into the cell culture medium. After 21 days of hepatocyte induction, FMSCs expressed the hepatocyte-specific markers, α-fetoprotein and cytokeratin 18, as demonstrated by immunofluorescence staining. Differentiated FMSCs also demonstrated in vitro functions characteristic of liver cells, including albumin production, urea secretion and glycogen storage. In conclusion, fetal bone marrow-derived FMSCs are able to differentiate into functional hepatocyte-like cells and may serve as a source of cells for liver disease therapy.

Analysis of the immune response to Hantaan virus nucleocapsid protein C-terminal-specific CD8+ T cells in patients with hemorrhagic fever with renal syndrome.

Hantaan virus (HTNV), the prototype member of the Hantavirus genus in the family Bunyaviridae, causes hemorrhagic fever with renal syndrome (HFRS), which is characterized by capillary leakage, hemorrhage, and renal injury, and is an important public health problem in China. Some kinds of immune cells, particularly CD8(+) T cells, are involved in the pathogenesis of Hantavirus infection. The nucleocapsid protein (NP) of the Hantavirus is the most conserved structural protein and the most abundant viral protein produced during infection. It is one of the important target antigens that induce the CD8(+) T-cell response. In this study, we examined the CD8(+) T-cell response to HTNV NP C-terminal polypeptides. We synthesized 23 overlapping C-terminal polypeptides and detected the antigen-specific CD8(+) T cell response in 15 patients with HFRS. The results demonstrated that there were NP-specific T-cell responses in bulk cultures of peripheral blood mononuclear cells (PBMCs) from 9 of 15 patients. The peptide 51 (aa 301-315: SPSSIWVFAGAPDRC), peptide 60 (aa 355-369: LRKKSSFYQSYLRRT), and peptide 70 (aa 415-429: DVKVKEISNQEPLKL) induced strong CD8(+) T-cell responses. Among them, peptide 70 induced CTL responses in donors 7, 9, and 11, and the strongest responses were seen in donor 11. Depletion of CD8(+) T cells from PBMCs completely abrogated the peptide-specific T-cell response, while depletion of CD4(+) T cells did not diminish the number of IFN-gamma spot-forming cells. These data suggest that infection with HTNV results in CTL responses to immunodominant regions on the NP.

Inhibition of Hepatitis C Virus Infection by Interferon-γ Through Downregulating Claudin-1

Hepatitis C virus (HCV) is a serious global health threat and current medical treatment options are limited. Interferon (IFN)-gamma is an important proinflammatory cytokine with antiviral activity. However, the mechanism of IFN-gamma in anti-HCV infection remains unclear. In this study, we investigated the role of IFN-gamma on HCV infection of polarized Caco-2 cells using cell culture-derived HCV (HCVcc). We found that downregulation of claudin-1 (CLDN1) induced by IFN-gamma resulted in disruption of barrier function as demonstrated by measurement of transepithelial electrical resistance and dextran permeability. Further, results from confocal microscopy and Western blot analysis showed that in addition to the reduction of CLDN1 expression, IFN-gamma treatment also led to significant changes in the distribution of CLDN1, CD81, and scavenger receptor class B type I. Moreover, infection assays revealed that IFN-gamma-treated cells showed decreased susceptibility to HCVcc infection. These results suggest a novel mechanism that IFN-gamma may inhibit HCV infection by regulating CLDN1 expression and distribution of HCV receptors.

Notch Signaling Contributes to Liver Inflammation by Regulation of Interleukin-22-Producing Cells in Hepatitis B Virus Infection

The mechanism of hepatitis B virus (HBV) induced liver inflammation is not fully elucidated. Notch signaling augmented interleukin (IL)-22 secretion in CD4+ T cells, and Notch-IL-22 axis fine-tuned inflammatory response. We previously demonstrated a proinflammatory role of IL-22 in HBV infection. Thus, in this study, we analyzed the role of Notch in development of IL-22-producing cells in HBV infection by inhibition of Notch signaling using γ-secretase inhibitor DAPT in both hydrodynamic induced HBV-infected mouse model and in peripheral blood cells isolated from patients with HBV infection. mRNA expressions of Notch1 and Notch2 were significantly increased in livers and CD4+ T cells upon HBV infection. Inhibition of Notch signaling in vivo leaded to the reduction in NKp46+ innate lymphoid cells 22 (ILC22) and lymphoid tissue inducer 4 (LTi4) cells in the liver. This process was accompanied by downregulating the expressions of IL-22 and related proinflammatory cytokines and chemokines in the liver, as well as blocking the recruitment of antigen-non-specific inflammatory cells into the liver and subsequent liver injury, but did not affect HBV antigens production and IL-22 secretion in the serum. Furthermore, IL-22 production in HBV non-specific cultured CD4+ T cells, but not HBV-specific CD4+ T cells, was reduced in response to in vitro inhibition of Notch signaling. In conclusion, Notch siganling appears to be an important mediator of the liver inflammation by modulating hepatic ILC22. The potential proinflammatory effect of Notch-mediated ILC22 may be significant for the development of new therapeutic approaches for treatment of hepatitis B.

Down-regulation of CXCR4 expression by SDF-KDEL in CD34+ hematopoietic stem cells: an anti-human immunodeficiency virus strategy.

CXCR4 plays an essential role as the first discovered coreceptor for the entry of T cell tropic isolates of HIV-1. Blocking the surface expression of this receptor may be a potential strategy to prevent HIV-1 infection. A lentiviral vector, pLenti6/V5-S-K, expressing a SDF-KDEL fusion protein was constructed and a replication-incompetent lentiviral stock was produced. The lentiviral stock was transduced into CD34(+) hHSC and the transient expression of the recombinant protein, SDF-1, was assayed using indirect immunofluorescence. The surface expression of CXCR4 in CD34(+) hHSC pretreated with different amounts of recombinant lentiviral vectors was detected by flow cytometric analysis. A marked down-regulation of CXCR4 expression in the cells transduced with recombinant lentiviral vectors pLenti6/V5-S-K was observed by flow cytometry with PE-conjugated anti-human CXCR4 monoclonal antibodies which showed the percentages of the inhibition effects of CXCR4-SDF-1 mediated syncytium formation are presented by concentration. P24 antigen levels of cell culture supernatants were detected on the 4th, 7th, and 10th day, with 10(3) TCID50 HIV-1 infected CD34(+) hHSC to evaluate the inhibitory effect of pLenti6/V5-S-K transduction on HIV-1 infection. The cells transfected with pLenti6/V5-S-K had a significant reduction of HIV-1 DP27 infection compared to controls (P<0.05).