Anti-CD81 antibodies reduce migration of activated T lymphocytes and attenuate mouse experimental colitis.

Inflammatory bowel disease (IBD) is an immunological disease associated with CD4+ T cell activation in the intestines. CD81 is a regulator of the immune system with multiple biological functions. Therefore, in this study, we assessed the contribution of CD81 to IBD pathophysiology and the therapeutic efficacy of anti-CD81 antibodies. Expression of CD81 was increased on activated T cells in vitro and in colitic mice in vivo. Therapeutic effects of anti-CD81 antibodies on colitic symptoms and inflammation were evaluated in mice with colitis, including long-term effects of the antibodies. Treatment with anti-CD81 antibodies improved colitis scores, reduced colon shortening, decreased loss of body weight, and resulted in fewer pathological changes of the colon in colitic mice. Moreover, the increased inflammatory markers in the blood of colitic mice were decreased by anti-CD81 antibodies. The anti-CD81 antibody treatment had long-lasting therapeutic effects on colitic mice, even after cessation of treatment. Two different clones of the anti-mouse CD81 antibody were also effective in mice with colitis. Furthermore, anti-CD81 antibodies reduced migration of CD4+ T cells both in colitic mice and in vitro. Thus, CD81 contributes to IBD pathology and treatment with anti-CD81 antibodies may be a potential novel therapy for IBD patients.

Publisher Correction: Regulation of the Hepatitis B virus replication and gene expression by the multi-functional protein TARDBP.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A monoclonal antibody recognizing a new epitope on CD81 inhibits T-cell migration without inducing cytokine production.

CD81 is involved in leukocyte migration and cytokine induction. Previous work found that anti-CD81 monoclonal antibodies (mAbs) showed therapeutic potential for several immune diseases via inhibiting leukocyte migration. Although the suppression of cell migration is a promising approach for treating immune diseases, some anti-CD81 mAbs can induce cytokine production, which may exacerbate disease. To obtain new anti-human CD81 mAbs that inhibited migration in the absence of cytokine production enhancement activity, we screened a human single chain variable fragment by phage library. One of the new anti-CD81 mAbs isolated, DSP-8250, had equivalent inhibitory cell migration activity with the established anti-CD81 mAb 5A6, but it lacked cytokine induction activity. These mAbs recognized different epitopes on CD81. mAb 5A6, which had inhibitory activity on T-cell migration and increased cytokine production, bound to three residues, Ser179, Asn180 and Phe186 of CD81. In contrast, DSP-8250, which had inhibitory activity on T-cell migration but no cytokine enhancement activity, bound to four residues, His151, Ala164, Ser168 and Asn172 of CD81 as a unique epitope. These results indicate that the set of His151, Ala164, Ser168 and Asn172 forms a novel epitope that might make the application of anti-CD81 mAb therapeutically useful.

Regulation of the Hepatitis B virus replication and gene expression by the multi-functional protein TARDBP.

Hepatitis B virus (HBV) infects the liver and is a key risk factor for hepatocellular carcinoma. Identification of host factors that support viral replication is important to understand mechanisms of viral replication and to develop new therapeutic strategies. We identified TARDBP as a host factor that regulates HBV. Silencing or knocking out the protein in HBV infected cells severely impaired the production of viral replicative intermediates, mRNAs, proteins, and virions, whereas ectopic expression of TARDBP rescued production of these products. Mechanistically, we found that the protein binds to the HBV core promoter, as shown by chromatin precipitation as well as mutagenesis and protein-DNA interaction assays. Using LC-MS/MS analysis, we also found that TARDBP binds to a number of other proteins known to support the HBV life cycle, including NPM1, PARP1, Hsp90, HNRNPC, SFPQ, PTBP1, HNRNPK, and PUF60. Interestingly, given its key role as a regulator of RNA splicing, we found that TARDBP has an inhibitory role on pregenomic RNA splicing, which might help the virus to export its non-canonical RNAs from the nucleus without being subjected to unwanted splicing, even though mRNA nuclear export is normally closely tied to RNA splicing. Taken together, our results demonstrate that TARDBP is involved in multiple steps of HBV replication via binding to both HBV DNA and RNA. The protein's broad interactome suggests that TARDBP may function as part of a RNA-binding scaffold involved in HBV replication and that the interaction between these proteins might be a target for development of anti-HBV drugs.

Involvement of microRNA-224 in cell proliferation, migration, invasion, and anti-apoptosis in hepatocellular carcinoma.

BACKGROUND AND AIM: Changes in microRNA (miRNA) expression have been detected in a broad range of biological processes including cancer. Here we determined the role of miRNA dysregulation in hepatocellular carcinoma (HCC). METHODS: We investigated the expression of nine cancer-related miRNAs in HCC. Among these, miR-224 was the most significantly uprgulated in HCC tissues (n = 18), compared with normal (n = 9) and HCC adjacent non-tumorous liver tissues (n = 18). After leading-in currently reported gene targets from Sanger miRBase, we characterized the expression profiles of target genes of miR-224 using cDNA microarray. The altered expression was subsequently validated by real-time polymerase chain reaction and Western blot. The phenotypic changes by miR-224 expression were identified by cell viability, apoptosis, and in vitro scratch assays. RESULTS: The microarray analysis and miRNA target prediction analysis allowed the identification of significant changes in 68 putative gene targets after overexpression of miR-224. The high-ranking genes CDC42, CDH1, PAK2, BCL-2, and MAPK1 were confirmed as important targets of miR-224 and involvement in hepatocarcinogenesis. Overexpression of miR-224 significantly in Hek293 and Huh7 cells altered the expression levels of CDC42, CDH1, PAK2, and BCL-2 at both mRNA and protein levels. Similar changes in the expression of the same genes were also observed in HCC tissues. Via functional analyses, cell proliferation, migration and anti-apoptosis were proved to be affected by miR-224 expression. CONCLUSION: The results suggest that miR-224 plays a role in cell proliferation, migration, invasion, and anti-apoptosis in HCC by directly binding to its gene targets, implicating this RNA in HCC development and progression.

Variation in the DEPDC5 locus is associated with progression to hepatocellular carcinoma in chronic hepatitis C virus carriers.

Chronic viral hepatitis is the most important risk factor for progression to hepatocellular carcinoma (HCC). To identify genetic risk factors for progression to HCC in individuals with chronic hepatitis C virus (HCV), we analyzed 467,538 SNPs in 212 Japanese individuals with chronic HCV with HCC and 765 individuals with chronic HCV without HCC. We identified one intronic SNP in the DEPDC5 locus on chromosome 22 associated with HCC risk and confirmed the association using an independent case-control population (710 cases and 1,625 controls). The association was highly significant when we analyzed the stages separately as well as together (rs1012068, P(combined) = 1.27 × 10(-13), odds ratio = 1.75). The significance level of the association further increased after adjustment for gender, age and platelet count (P = 1.35 × 10(-14), odds ratio = 1.96). Our findings suggest that common variants within the DEPDC5 locus affect susceptibility to HCC in Japanese individuals with chronic HCV infection.