Kazumasa Hiroishi

Intrahepatic status of regulatory T cells in autoimmune liver diseases and chronic viral hepatitis

Aim:  Regulatory T cells (Tregs) maintain immunological tolerance and suppress autoreactive immune responses. We evaluated the intrahepatic status of Tregs in patients with autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), chronic hepatitis C (CH‐C), or chronic hepatitis B (CH‐B).

A minimal and optimal cytotoxic T cell epitope within hepatitis C virus nucleoprotein

Amino acid residues 81-100 of the hepatitis C virus (HCV) nucleoprotein contain a cytotoxic T cell epitope that is recognized by cytotoxic T lymphocytes (CTLs) in association with human leukocyte antigen B44. With panels of truncated and overlapping peptides, the minimal and optimal epitope recognized by CTLs was shown to be a 9-mer peptide (residues 88-96). The peptide can stimulate effectively CTLs that are able to recognize endogenously synthesized and processed HCV nucleoprotein.

Infection of B cells with hepatitis C virus for the development of lymphoproliferative disorders in patients with chronic hepatitis C.

Infection with hepatitis C virus (HCV) is associated with lymphoproliferative disorders, represented by essential mixed cryoglobulinemia and B‐cell non‐Hodgkins lymphoma, but the pathogenic mechanism remains obscure. HCV may infect B cells or interact with their cell surface receptors, and induce lymphoproliferation. The influence of HCV infection of B cells on the development of lymphoproliferative disorders was evaluated in 75 patients with persistent HCV infection. HCV infection was more prevalent (63% vs. 16%, 14%, or 17% P < 0.05 for each), and HCV RNA levels were higher (3.35 ± 3.85 vs. 1.75 ± 2.52, 2.15 ± 2.94 or 2.10 ± 2.90 log copies/100 ng, P < 0.01 for each) in B cells than CD4+, CD8+ T cells or other cells. Negative‐strand HCV RNA, as a marker of viral replication, was detected in B cells from four of the 75 (5%) patients. Markers for lymphoproliferative disorders were more frequent in the 50 patients with chronic hepatitis C than the 32 with chronic hepatitis B, including cryoglobulinemia (26% vs. 0%, P < 0.001), low CH50 levels (48% vs. 3%, P = 0.012), and the clonality of B cells (12% vs. 0%, P < 0.01). By multivariate analysis, HCV RNA in B cells was an independent factor associated with the presence of at least one marker for lymphoproliferation (odds ratio: 1.98 [95% confidence interval: 1.36–7.24], P = 0.027). Based on the results obtained, the infection of B cells with HCV would play an important role in the development of lymphoproliferative disorders. J. Med. Virol. 81:619–627, 2009

Guideline on the use of new anticancer drugs for the treatment of Hepatocellular Carcinoma 2010 update

The “Guideline on the Use of New Anticancer Drugs for the Treatment of Hepatocellular Carcinoma” was prepared by the Study Group on New Liver Cancer Therapies established by the “Research Project on Emergency Measures to Overcome Hepatitis” under the auspices of the Health and Labour Sciences Research Grant. The Guideline brings together data collected by the Study Group on the use and incidence of adverse events in 264 patients with advanced hepatocellular carcinoma (HCC) treated using sorafenib and in 535 patients with advanced HCC treated using miriplatin at 16 participating institutions up until 22 December 2010, as well as referring to the published studies, academic presentations, and reports from the private sector. The aim of this Guideline is to facilitate understanding and current thinking regarding the proper usage of new anticancer drugs towards actual use in therapy. In terms of the format, the Guideline presents “clinical questions” on issues pertaining to medical care, makes “recommendations” on diagnosis and treatment in response to each of these clinical questions, and provides a rationale for these recommendations in the form of “scientific statements”.

Three new cytotoxic T cell epitopes identified within the hepatitis C virus nucleoprotein.

Cytotoxic T lymphocytes (CTLs) may play a role in host defence against hepatitis C virus (HCV) infection, and HCV-specific CTL epitopes may be included in vaccines to induce protective CTLs. We identified three new epitopes within the HCV nucleoprotein recognized by CTLs. HCV nucleoprotein residues 28-37 are the minimal epitope recognized by CTLs in association with the class I human leukocyte antigen B60, and epitopes in HCV nucleoprotein residues 111-130 and 161-180 are both recognized by CTLs in association with the class II human leukocyte antigen DRBI*08032.

Cyclooxygenase‐2 gene promoter polymorphisms affect susceptibility to hepatitis C virus infection and disease progression

Aim:  Because polymorphisms of cyclooxygenase‐2 (COX‐2) and osteopontin (OPN) promoter regions and a promoter/enhancer region of forkhead box protein 3 (FOXP3) gene are known to affect immune responses, we examined whether these polymorphisms can influence susceptibility to hepatitis C virus (HCV) infection and progression of liver disease.

Immune responses in hepatitis C virus infection and mechanisms of hepatitis C virus persistence

Immune responses against hepatitis C virus (HCV) play a crucial role in the pathogenesis of chronic hepatitis C. HCV infection often persists and leads to chronic hepatitis and eventually cirrhosis. Accumulated data suggest that HCV proteins suppress host immune responses through the suppression of functions of immune cells, such as cytotoxic T lymphocytes, natural killer cells, and dendritic cells. They also suppress the type 1 interferon signaling system. The resulting insufficient immune responses against HCV lead to the sustained infection. The appropriate control of immune responses would contribute to the eradication of HCV and the improvement of hepatitis, but there are still many issues to be clarified. This review describes the scientific evidence to support these emerging concepts, and will touch on the implications for improving antiviral therapy.

Genetic polymorphism in cyclooxygenase‐2 promoter affects hepatic inflammation and fibrosis in patients with chronic hepatitis C

Summary.  Cyclooxygenase (COX)‐2 is involved in inflammation, anti‐apoptosis and carcinogenesis. The ‐1195GG genotype of single nucleotide polymorphism (SNP) in COX‐2 promoter was associated with low platelet counts in patients with chronic hepatitis C. Polymorphism of patatin‐like phospholipase domain‐containing protein 3 (PNPLA3) gene (rs738409 C>G) have been reported to be associated with cirrhosis, and the major genotype of SNPs near interleukin (IL)28B are related to viral clearance. The present study was designed to assess the contribution of these SNPs to disease progression in patients with chronic hepatitis C. The study enrolled 220 Japanese patients with chronic hepatitis C. Three SNPs, ‐1195 COX‐2, PNPLA3 and IL28B (rs8099917), were genotyped in order to analyze their association with hepatic fibrosis and inflammation. The ‐1195GG genotype in COX‐2 was associated with advanced fibrosis and higher levels of inflammation in the liver tissues. The major genotype of IL28B was also associated with advanced fibrosis, but the polymorphism of PNPLA3 was neither associated with fibrosis nor inflammation. Multivariate analysis showed that ‐1195GG in COX‐2 is an independent factor associated with advanced fibrosis, while the major genotype of IL28B and HCV genotype 2 were other independent factors. In conclusion, the ‐1195GG genotype in COX‐2 is a genetic marker for liver disease progression, while the PNPLA3 genotypes are not associated with disease progression in Japanese patients with chronic hepatitis C.

Immune Response of Cytotoxic T Lymphocytes and Possibility of Vaccine Development for Hepatitis C Virus Infection

Immune responses of cytotoxic T lymphocytes (CTLs) are implicated in viral eradication and the pathogenesis of hepatitis C. Weak CTL response against hepatitis C virus (HCV) may lead to a persistent infection. HCV infection impairs the function of HCV-specific CTLs; HCV proteins are thought to actively suppress host immune responses, including CTLs. Induction of a strong HCV-specific CTL response in HCV-infected patients can facilitate complete HCV clearance. Thus, the development of a vaccine that can induce potent CTL response against HCV is strongly expected. We investigated HCV-specific CTL responses by enzyme-linked immuno-spot assay and/or synthetic peptides and identified over 40 novel CTL epitopes in the HCV protein. Our findings may contribute to the development of the HCV vaccine. In this paper, we describe the CTL responses in HCV infection and the attempts at vaccine development based on recent scientific articles.

In vivo immunological antitumor effect of OK-432-stimulated dendritic cell transfer after radiofrequency ablation

Abstract Radiofrequency ablation therapy (RFA) is a radical treatment for liver cancers and induces tumor antigen-specific immune responses. In the present study, we examined the antitumor effects of focal OK-432-stimulated dendritic cell (DC) transfer combined with RFA and analyzed the functional mechanisms involved using a murine model. C57BL/6 mice were injected subcutaneously with colon cancer cells (MC38) in their bilateral flanks. After the establishment of tumors, the subcutaneous tumor on one flank was treated using RFA, and then OK-432-stimulated DCs were injected locally. The antitumor effect of the treatment was evaluated by measuring the size of the tumor on the opposite flank, and the immunological responses were assessed using tumor-infiltrating lymphocytes, splenocytes and draining lymph nodes. Tumor growth was strongly inhibited in mice that exhibited efficient DC migration after RFA and OK-432-stimulated DC transfer, as compared to mice treated with RFA alone or treatment involving immature DC transfer. We also demonstrated that the antitumor effect of this treatment depended on both CD8-positive and CD4-positive cells. On the basis of our findings, we believe that combination therapy for metastatic liver cancer consisting of OK-432-stimulated DCs in combination with RFA can proceed to clinical trials, and it is anticipated to be markedly superior to RFA single therapy.