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HBsAg Interferes with the TLR Signaling Pathway in Macrophage-like Cells

Author: LiuHua
Tutor: YuanZhengHong；ChuYiWei；TongWenYan
School: Fudan University
Course: Pathogenic microbiology
Keywords: Hepatitis B surface antigen Toll-like receptor Macrophage -like cells THP-1 SOCS1
CLC: R392
Type: Master's thesis
Year: 2006
Downloads: 149
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Abstract

Hepatitis B virus (hepatitis B virus, HBV) membrane of an incomplete circular double-stranded DNA virus, human cases of infection caused by the different clinical manifestations, had acute hepatitis, chronic persistent hepatitis, and even death sex fulminant hepatitis. Now generally believed that the immune system-mediated host-virus interaction with viral clearance after HBV infection and hepatitis disease process. Multiple studies have shown, the vitality, diversity and effector function of the body of HBV-specific cellular immune response is the key to the outcome of HBV infection and, therefore, the cellular immune response dysfunction is considered to be an important reason for persistent HBV infection. The reason is unclear, but the cause of persistent HBV infection in patients with T-cell reaction barriers the start specific T cell responses antigen-presenting function blocked and must play a role in which. Toll-like receptors (Toll likereceptors, TLRs) family belongs to the pattern recognition receptors (pattern recognition receptors, PRRs) members, mediated pathogen recognition conserved molecular structure, plays a very important role in the innate immune system. Recent studies have found that TLR signaling pathway regulates antigen-presenting cell activation is to start with the premise of normal T cell immune response, some viral proteins interfere with the activation of the TLR signaling pathway with of TLRs its downstream signaling molecules interaction, suggesting that the virus can antigen presenting affect the activation of the TLR signaling pathway to regulate the immune system. Of HBV viral proteins are also able to take advantage of this immunomodulatory mechanism has yet to be proved. Do this selection of differentiated THP-1 macrophage-like cells in this study as the object of study, observation secretion HBV infection membrane protein - HBsAg (hepatitis B surface antigen, HBsAg) TLR signaling pathway. First detected by Real-time PCR method in PMA-stimulated THP-1 and THP-1 macrophage-like cells induced to differentiate TLR expression profiling. The results show, the THP-1 to differentiate into macrophage-like cells, the expression of the majority of TLRs has increased significantly. And macrophage-like cells, TLR1, TLR2, TLR4 and TLR6 expression was significantly higher than the other of TLRs. Moderating Effect of HBsAg for full activation of TLR signaling pathway case studies, choose to activate the high expression of TLRs signaling pathway in the macrophage-like cells for further study. TLR1 / 2 the ligand pam3csk4 and TLR4 ligand LPS-stimulated cells by Real-time PCR and ELISA, respectively, from the detection of the protein and mRNA levels of IL-10 and IL-12 expression, the results show that treatment of HBsAg extracellular the pam3csk4 and LPS induced a dose-dependent manner interfere with IL-10 and IL-12 generation, suggesting that the HBsAg can interfere with macrophage-like cells TLR signaling pathway. In order to understand the influence of HBsAg TLR downstream signaling pathways, using immunofluorescence analysis the induction of LPS and pam3csk4 of NF-κB p65 into nuclear. Found that the presence of HBsAg obvious interference the pam3csk4 and LPS-induced NF-κB p65 into the nucleus, and the results of Western blotting analysis also showed that, HBsAg suppression the induction of pam3csk4 and LPS-induced IκB-α degradation, which prompted HBsAg TLRs downstream NF -κB pathway interference effect. Further with Western blotting detection of phosphorylated the EEK protein expression, the results showed that HBsAg to prevent the pam3csk4 and LPS-induced ERK protein phosphorylation HBsAg ERK pathway downstream of TLRs also influential. The above results proved once again that the HBsAg inhibition TLR signaling pathway activation. To further understand the mechanisms of the HBsAg interference TLR signaling pathway, Real-time PCR detection processing of HBsAg expression of the macrophage-like cell TLRs. The results of HBsAg does not rely on cut the TLRs expression to interfere with TLR signaling pathway activation, even HBsAg could upregulate the expression of TLR4. In addition to the identification of interference with the outer membrane of TLRs intracellular adjustment factors can also affect the activation of the TLR signaling pathway. It has been found that a variety of to adjustment factor affecting TLR signal transduction, including MyD88s, IRAK3 Tollip the IRF family, IRF4 and IRF5 and the SOCS family's SOCS1 and SOCS3 etc.. Real-time PCR analysis HBsAg extracellular processing affect the expression of these regulatory factors, and found that the HBsAg can up-regulate the expression of SOCS1 prompt HBsAg may interfere with the TLR pathway activation in macrophage-like cells by upregulating SOCS1. In summary, our results suggest that the high load HBsAg, HBV infection may cause depletion of T cells directly affect the acquired immune response, may also affect the innate immune response by interfering with the activation of TLR signaling pathways to influence antigen presenting, to prevent the establishment of HBV-specific T-cell immune response. Further develop this study will help to understand the reasons for low persistent HBV infected T-cell responses, and provide a new theoretical basis to explore the pathogenic mechanism of chronic HBV infection and the development of new anti-HBV drugs.

HBsAg Interferes with the TLR Signaling Pathway in Macrophage-like Cells

Abstract

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