Inducible Major Vault Protein Plays a Pivotal Role in Double-Stranded RNA- or Virus-Induced Proinflammatory Response.

Pathogen invasion triggers robust antiviral cytokine production via different transcription factor signaling pathways. We have previously demonstrated that major vault protein (MVP) induces type I IFN production during viral infection; however, little is known about the role of MVP in proinflammatory responses. In this study, we found in vitro that expression of MVP, IL-6, and IL-8 was inducible upon dsRNA stimulation or viral infection. Moreover, MVP was essential for the induction of IL-6 and IL-8, as impaired expression of IL-6 and IL-8 in MVP-deficient human PBMCs, human lung epithelial cells (A549), and THP-1 monocytes, as well as in murine splenocytes, peritoneal macrophages, and PBMCs from MVP-knockout (MVP(-/-)) mice, was observed. Upon investigation of the underlying mechanisms, we demonstrated that MVP acted in synergy with AP-1 (c-Fos) and CCAAT/enhancer binding protein (C/EBP)ß-liver-enriched transcriptional activating protein to activate the IL6 and IL8 promoters. Introduction of mutations into the AP-1 and C/EBPß binding sites on the IL6 and IL8 promoters resulted in the loss of synergistic activation with MVP. Furthermore, we found that MVP interacted with both c-Fos and C/EBPß. The interactions promoted nuclear translocation and recruitment of these transcription factors to IL6 and IL8 promoter regions. In the MVP(-/-) mouse model, significantly decreased expression of early antiviral cytokines resulted in higher viral titer in the lung, higher mortality, and heavier lung damage after infection with lethal influenza A virus. Taken together, our findings help to delineate a novel role of MVP in host proinflammatory response.

Inducible CYP4F12 enhances Hepatitis C virus infection via association with viral nonstructural protein 5B.

Hepatitis C virus (HCV) nonstructural protein 5B (NS5B) functions as an RNA-dependent RNA polymerase in the HCV replication complex derived from the endoplasmic reticulum in hepatic cells. In this study, NS5B was used as bait in a yeast two-hybrid assay to screen a human liver cDNA library. We confirmed that CYP4F12, a member of the cytochrome P450 superfamily, interacted with NS5B. Furthermore, overexpression of CYP4F12 facilitated HCV replication. In contrast, knockdown of CYP4F12 by specific shRNA decreased HCV replication and viral protein expression. Moreover, our results demonstrated that HCV infection increased the binding of the transcription factor SREBP1 to the CYP4F12 promoter and activated the promoter activity, which indicated that HCV infection increased the expression of CYP4F12 through the SREBP1 pathway. Our results showed that HCV infection induced expression of CYP4F12 protein, which bound to the HCV replication complex to facilitate viral replication.

Dual effects of interleukin-18: inhibiting hepatitis B virus replication in HepG2.2.15 cells and promoting hepatoma cells metastasis.

Interleukin-18 (IL-18) has been reported to inhibit hepatitis B virus (HBV) replication in the liver of HBV transgenic mice; however, the molecular mechanism of its antiviral effect has not been fully understood. In the present study, it was shown that IL-18 and its receptors (IL-18R) were constitutively expressed in hepatoma cell lines HepG2 and HepG2.2.15 as well as normal liver cell line HL-7702. We demonstrated that IL-18 directly inhibited HBV replication in HepG2.2.15 cells via downregulating the activities of HBV core and X gene promoters. The suppressed HBV replication by IL-18 could be rescued by the administration of BAY11-7082, an inhibitor of transcription factor NF-κB. On the other hand, it was of interest that IL-18 promoted HepG2 cell metastasis and migration dose dependently in both wound-healing assays and Transwell assays. The underlying mechanism could be partially attributable to the increased activities of extracellular matrix metalloproteinase (MMP)-9, MMP-3, and MMP-2 by IL-18, which upregulated the mRNA levels of MMP-3 and MMP-9 in a NF-κB-dependent manner. Furthermore, it was confirmed that expression of IL-18/IL-18R and most MMPs were remarkably upregulated in hepatocellular carcinoma (HCC) liver cancer tissue specimens, suggesting that IL-18/IL-18R-triggered signaling pathway was closely related to HCC metastasis in vivo. Therefore, we revealed the dual effects of IL-18 in human hepatocytes: it not only inhibited HBV replication but also promoted hepatoma cells metastasis and migration. NF-κB played a critical role in both effects. Our work contributed to a deeper understanding of the biological function of IL-18 in human hepatocytes.

[Effect of Vitamin D3 to Platelet Activation Mediated by Tumor Cell Culture Medium].

OBJECTIVE: To investigate the effect of vitamin D3 to platelet activation by tumor cell culture medium. METHODS: The peripheral blood platelets of BALB/c mice were isolated. The platelets were activated in 4T1 culture fluid for 24 h. The platelets were divided into 7 groups: control group, activation group, 1 nmol/L vitamin D3 group, 10 nmol/L vitamin D3 group, 50 nmol/L vitamin D3 group, 100 nmol/L vitamin D3 group, and positive drug (0.1 µmol/L eptifibatide) group. CCK-8 assay was used to detect the platelet proliferation at 24, 48 and 72 h. Flow cytometry was used to detect the expression of CD61 and CD62p and receptor for advanced glycation end products (RAGE) at 24, 48 and 72 h. ELISA was used to detect the level of platelet-endothelial cell adhesion molecule-1 (PECAM-1) at 24, 48 and 72 h. RESULTS: The CD41+/CD61+ and CD41+/CD62p+ ratio, PECAM-1 content and RAGE expression of platelets in activated group were all significantly increased as compared with those in control group (P<0.05). Compared with the activated group, the platelet proliferation, proportion of CD41+/CD61+ and CD41+/CD62p+, content of PECAM-1 and RAGE expression in vitamin D3 groups were all decreased (P<0.05). CONCLUSION: Vitamin D3 shows antiplatelet effect and can inhibit platelet proliferation and activation.

[Detection of HHV-8 Virus in 450 Free Blood Donons in Wuhan and Its Genotyping Based on ORFK1 Gene].

OBJECTIVE: To investigate the infection of HHV-8 virus in free blood donors in Wuhan. METHODS: Whole blood samples were collected from 450 free blood donors in Wuhan, and the genomic DNA extraction and serum collection were performed respectively. And then, the positive rate of HHV-8 was detected by PCR and ELISA, the positive detection rates were compared between them. Finally, HHV-8 ORFK1 gene was cloned by PCR in the positive samples, and the HHV-8 ORFK1 gene th was genetyped through sequencing analysis, homology comparison and phylogenetic tree construction. RESULTS: 25 and 23 cases of positive samples were detected by PCR and ELISA, their positive rate were 5.56% and 5.11% respectively, and without statistically significant difference using χ2 test analysis (P > 0.05). Based on the results of ORFK1 gene cloning and sequence analysis in 23 positive samples, 15 samples C subtype of had HHV-8 ORFK1 gene, and 8 cases had A subtype had HHV-8 ORFK1 gene. CONCLUSION: There is a certain percentage of HHV-8 infection in the free blood donors in Wuhan. It is suggested to increase the HHV-8 virus screening for free blood donors, so as to ensure the quality of blood.

Development of a more efficient hepatitis B virus vaccine by targeting hepatitis B virus preS to dendritic cells.

BACKGROUND: Conventional hepatitis B virus (HBV) vaccines fail to induce protective antibody titers in 5-10% of immune-competent vaccinees. Therefore, there remains an urgent need to develop a safe and effective HBV vaccine. METHODS: In this study, we developed an effective and economical method for producing the HBV vaccine by using the high binding capacity of biotin-streptavidin. The preS antigen of HBV was fused with the core streptavidin (cSA) moiety (preS-cSA) and highly expressed in Escherichia coli. We investigated whether the preS-cSA protein could target dendritic cells (DCs) by binding a biotinylated antibody against the DC receptor CD205 (biotin-αCD205). Moreover, we evaluated the preS-cSA/biotin-αCD205 complex as a candidate vaccine by detecting the humoral and cellular immune responses elicited by this vaccine. RESULTS: Our data show that the preS-cSA/biotin-αCD205 complex targeted DCs and induced high anti-HBV antibody titers of IgG2a, IgG1, and IgG in vivo. Furthermore, vaccination with the preS-cSA/biotin-αCD205 complex prevented HBV infection in female mice. More interestingly, this novel vaccine exerted a therapeutic role in mice with HBV infection. CONCLUSIONS: Taken together, our results reveal that the preS-cSA/biotin-αCD205 vaccine induces effective immunological protection against HBV, and is a promising candidate for preventing HBV infections.

Soluble interleukin-6 receptor is elevated during influenza A virus infection and mediates the IL-6 and IL-32 inflammatory cytokine burst.

Influenza A virus (IAV) infection is a major worldwide public health problem. However, the factors involved in mediating the inflammatory response to this infection and their relationships remain poorly understood. Here, we show that IAV infection stimulates the expression of the soluble IL-6 receptor (sIL-6R), a multifunctional protein involved in IL-6 signaling. Interestingly, sIL-6R expression upregulated the levels of its own ligand, IL-6 and those of the pro-inflammatory cytokine IL-32. shRNA-mediated knockdown of sIL-6R suppressed IL-6 and IL-32, indicating that this regulation is dependent on sIL-6R during IAV infection. Furthermore, our results demonstrate that IL-32 participates in a negative feedback loop that inhibits sIL-6R while upregulating IL-6 expression during IAV infection. Therefore, we show that sIL-6R is a critical cellular factor involved in the acute inflammatory response to viral infection.

HCV NS4B induces apoptosis through the mitochondrial death pathway.

The hepatitis C virus (HCV) NS4B protein is known to induce the formation of a membranous web that is thought to be the site of viral RNA replication. However, the exact functions of NS4B remain poorly characterized. In this study, we found that NS4B induced apoptosis in 293T cells and Huh7 cells, as confirmed by Hoechst staining, DNA fragmentation, and annexin V/PI assays. Furthermore, protein immunoblot analysis demonstrated that NS4B triggered the cleavage of caspase 3, caspase 7, and poly(ADP-ribose) polymerase (PARP). Further studies revealed that NS4B induced the activation of caspase 9, the reduction of mitochondrial membrane potential and the release of cytochrome c from the mitochondria. However, NS4B expression did not trigger XBP1 mRNA splicing and increase the expression of binding immunoglobulin protein (BiP, or GRP78) and C/EBP homologous protein (CHOP), which serves as the indicators of ER stress. Taken together, our results suggest that HCV NS4B induces apoptosis through the mitochondrial death pathway.