Chronic hepatitis B virus (HBV) infection is endemic in the Asian-Pacific region, and reactivation of HBV post-cancer chemotherapy has become an emerging clinical challenge. Patients with detectable serum HBV DNA before chemotherapy and those receiving intensive chemotherapy are particularly at a risk of HBV reactivation. Most patients with HBV reactivation are positive for hepatitis B surface antigen (HBsAg) and are, therefore, easily identified by recommended serological screening before chemotherapy. However, a small, but significant proportion of subjects who have apparently recovered from HBV infection as reflected by HBsAg negativity and hepatitis B core antibody positivity in HBV endemic areas may also experience reactivation when host immunity is severely compromised by cancer chemotherapy. Serum alanine aminotransferase, HBsAg, and/or HBV DNA should be monitored closely in these subjects and antiviral therapy should be administered immediately when any evidence of HBV reactivation is detected during chemotherapy. The prophylactic use of nucleos(t)ide analogs before chemotherapy and its continuation until reconstitution of host immunity remain the mainstay of effective prevention of hepatitis B reactivation in this special clinical entity.

Hepatitis B virus reactivation in patients receiving cancer chemotherapy: natural history, pathogenesis, and management.

Hepatitis B virus (HBV) causes chronic hepatitis in hundreds of millions of people worldwide, which can eventually lead to hepatocellular carcinoma (HCC). The molecular mechanisms underlying HBV persistence are not well understood. In this study, we found that HBV inhibited the chemotherapy drug etoposide-induced apoptosis of hepatoma cells. Further analysis revealed that HBV mRNAs possess a microRNA 15a/16 (miR-15a/16)-complementary site (HBV nucleotides [nt] 1362 to 1383) that acts as a sponge to bind and sequester endogenous miR-15a/16. Consequently, Bcl-2, known as the target of miR-15a/16, was upregulated in HBV-infected cells. The data from HBV-transgenic mice further confirmed that HBV transcripts cause the reduction of miR-15a/16 and increase of Bcl-2. More importantly, we examined the levels of HBV transcripts and miR-15a/16 in HBV-infected HCC from patients and found that the amount of HBV mRNA and the level of miR-15a/16 were negatively correlated. Consistently, the level of Bcl-2 mRNA was upregulated in HBV-infected patients. In conclusion, we identified a novel HBV mRNA–miR-15a/16–Bcl-2 regulatory pathway that is involved in inhibiting etoposide-induced apoptosis of hepatoma cells, which may contribute to facilitating chronic HBV infection and hepatoma development.

Hepatitis B Virus Inhibits Apoptosis of Hepatoma Cells by Sponging the MicroRNA 15a/16 Cluster

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.21442

Ethanol-induced oxidative stress suppresses generation of peptides for antigen presentation by hepatoma cells.

Multiple sclerosis (MS) is a demyelinating inflammatory disease of the CNS. Though originally believed to be CD4-mediated, additional immune effector mechanisms, including myelin-specific CD8 + T cells, are now proposed to participate in the pathophysiology of MS. To study the immunologic and encephalitogenic behavior of HLA-A*0201-binding myelin-derived epitopes in vivo, we used a humanized HLA-A*0201-transgenic mouse model. Eight HLA-A*0201-binding peptides derived from myelin oligodendrocyte glycoprotein (MOG), an immunodominant myelin self-Ag, were identified in silico. After establishing their relative affinity for HLA-A*0201 and their capacity to form stable complexes with HLA-A*0201 in vitro, their immunological characteristics were studied in HLA-A*0201-transgenic mice. Five MOG peptides, which bound stably to HLA-A*0201 exhibited strong immunogenicity by inducing a sizeable MOG-specific HLA-A*0201-restricted CD8 + T cell response in vivo. Of these five candidate epitopes, four were processed by MOG-transfected RMA target cells and two peptides proved immunodominant in vivo in response to a plasmid-encoding native full-length MOG. One of the immunodominant MOG peptides (MOG 181 ) generated a cytotoxic CD8 + T cell response able to aggravate CD4 + -mediated EAE. Therefore, this detailed in vivo characterization provides a hierarchy of candidate epitopes for MOG-specific CD8 + T cell responses in HLA-A*0201 MS patients identifying the encephalitogenic MOG 181 epitope as a primary candidate.

/pdf/cd8-t-cell-responses-to-myelin-oligodendrocyte-glycoprotein-tmy9qbc3gu.pdf

CD8 T Cell Responses to Myelin Oligodendrocyte Glycoprotein-Derived Peptides in Humanized HLA-A*0201-Transgenic Mice

Autoreactivity may play a critical role in the chronification of atopic dermatitis (AD). Several studies showed that AD patients produce IgE Abs specific for autoantigens, and we described Th as well as CD8(+) T cells specific for the autoallergen Hom s 2, the α-chain of the nascent polypeptide-associated complex (α-NAC). This study aimed to investigate the frequency and inflammatory phenotype of autoallergen-specific CD8(+) T cells. CD8(+) T cell immunodominant epitopes of α-NAC were mapped by applying prediction softwares, and binding affinity was confirmed by stabilization of empty MHC complexes. MHC class I tetramers were assembled and binding cells were analyzed directly ex vivo by flow cytometry and in terms of single-cell assessment by ChipCytometry. We report significantly elevated numbers of α-NAC-specific peripheral T cells in sensitized patients compared with nonatopic controls. These cells secrete IL-4 and IFN-γ, and surface markers revealed significantly elevated frequencies of circulating terminally differentiated α-NAC-specific CD8(+) T cells in patients with AD compared with nonatopic donors. The observed phenotype of α-NAC-specific CD8(+) T cells indicates a role in the pathogenesis of AD.

α-NAC–Specific Autoreactive CD8+ T Cells in Atopic Dermatitis Are of an Effector Memory Type and Secrete IL-4 and IFN-γ

Frequencies of epitope-specific cytotoxic T lymphocytes in active chronic viral hepatitis B infection by using MHC class I peptide tetramers

It is necessary to evaluate the cytokine secretion status of CD8+ T lymphocytes and elucidate the factors influencing cytokine secretion, because the secretion of cytokines is also an important feature of CD8+ T lymphocytes, and the cytokines usually play critical roles in the outcome of diseases. We showed here that peptide AYRPPNAPI, derived from the core antigen of hepatitis B virus (HBV), could bind to H-2 Kd and induce primed splenocytes from HBcAg expression plasmid-immunized mice to produce gamma interferon (IFN-gamma) in H-2 Kd- and CD8-dependent manners instead of in a CD4-dependent manner. The induced cells were mainly CD3 and CD8 positive but had no cytotoxic effect on the corresponding target cells. When administered into HBV transgenic mice, these cells can decrease the serum HBV load without causing liver damage. These results suggest that this peptide is a special kind of CD8+ T-cell epitope, for which specific CD8+ T cells can produce IFN-gamma when antigenic stimulation is encountered but which have no cytotoxic effect on the corresponding target cells both in vitro and in HBV transgenic mice. This phenomenon indicates initially that the functional mechanisms of CD8+ T cells can be determined by their epitope specificity, which may be associated with the development of epitope-based immunotherapeutic approaches for infectious diseases and tumors.

H-2 Kd-Restricted Hepatitis B Virus-Derived Epitope Whose Specific CD8+ T Lymphocytes Can Produce Gamma Interferon without Cytotoxicity

Vaccination with antigenic peptide-pulsed antigen-presenting cells (APC) represents an attractive approach for therapy for cancer and diseases caused by intracellular infections. It has been suggested that sufficient stable MHC/peptide complexes on the surface of APC might play an important role in the generation of antitumor and antiviral immunity in vivo. In this study, we observed that exogenous peptides that were artificially fused with an endoplasmic reticulum (ER) retrieval signal, a C-terminal Lys-Asp-Glu-Leu sequence, could be efficiently presented by intracellular MHC class I molecules in a TAP- and proteasome-independent, but brefeldin A-sensitive manner. The APC retained the capacity to display surface MHC/peptide complexes for a prolonged period. In addition, our results show that vaccination with DC bearing our fusion peptides induced greatly enhanced specific CTL response, and resulted in significant inhibition of tumor growth. Thus, the ER retrieval signal modification can be regarded as a novel method for targeting exogenous peptides into the intracellular MHC class I presentation pathway, and may improve the clinical utility of vaccines based on synthetic peptide pulsed DC.

MHC class I-associated presentation of exogenous peptides is not only enhanced but also prolonged by linking with a C-terminal Lys-Asp-Glu-Leu endoplasmic reticulum retrieval signal.

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Frequencies of epitope-specific cytotoxic T lymphocytes in active chronic viral hepatitis B infection by using MHC class I peptide tetramers

H-2 Kd-Restricted Hepatitis B Virus-Derived Epitope Whose Specific CD8+ T Lymphocytes Can Produce Gamma Interferon without Cytotoxicity

MHC class I-associated presentation of exogenous peptides is not only enhanced but also prolonged by linking with a C-terminal Lys-Asp-Glu-Leu endoplasmic reticulum retrieval signal.