Ichiro Miyajima

Systemic anaphylaxis in the mouse can be mediated largely through IgG1 and Fc gammaRIII. Assessment of the cardiopulmonary changes, mast cell degranulation, and death associated with active or IgE- or IgG1-dependent passive anaphylaxis.

We attempted to elicit active anaphylaxis to ovalbumin, or passive IgE- or IgG1-dependent anaphylaxis, in mice lacking either the Fc epsilonRI alpha chain or the FcR gamma chain common to Fc epsilonRI and Fc gammaRI/III, or in mice lacking mast cells (KitW/ KitW-v mice), and compared the responses to those in the corresponding wild-type mice. We found that the FcR gamma chain is required for the death, as well as for most of the pathophysiological changes, associated with active anaphylaxis or IgE- or IgG1-dependent passive anaphylaxis. Moreover, some of the physiological changes associated with either active, or IgG1-dependent passive, anaphylactic responses were significantly greater in Fc epsilonRI alpha chain -/- mice than in the corresponding normal mice. Finally, while both KitW/KitW-v and congenic +/+ mice exhibited fatal active anaphylaxis, mast cell-deficient mice exhibited weaker physiological responses than the corresponding wild-type mice in both active and IgG1-dependent passive systemic anaphylaxis. Our findings strongly suggest that while IgE antibodies and Fc epsilonRI may influence the intensity and/or kinetics of some of the pathophysiological changes associated with active anaphylaxis in the mouse, the mortality associated with this response can be mediated largely by IgG1 antibodies and Fc gammaRIII.

Immune Sensitization in the Skin Is Enhanced by Antigen-Independent Effects of IgE

Contact sensitivity responses require both effective immune sensitization following cutaneous exposure to chemical haptens and antigen-specific elicitation of inflammation upon subsequent hapten challenge. We report that antigen-independent effects of IgE antibodies can promote immune sensitization to haptens in the skin. Contact sensitivity was markedly impaired in IgE(-/-) mice but was restored by either transfer of sensitized cells from wild-type mice or administration of hapten-irrelevant IgE before sensitization. Moreover, IgE(-/-) mice exhibited impairment in the reduction of dendritic cell numbers in the epidermis after hapten exposure. Monomeric IgE has been reported to influence mast cell function. We observed diminished contact sensitivity in mice lacking FcepsilonRI or mast cells, and mRNA for several mast cell-associated genes was reduced in IgE(-/-) versus wild-type skin after hapten exposure. We speculate that levels of IgE normally present in mice favor immune sensitization via antigen-independent but FcepsilonRI-dependent effects on mast cells.

A Randomized Study of Extended Treatment With Peginterferon α-2b Plus Ribavirin Based on Time to HCV RNA Negative–Status in Patients With Genotype 1b Chronic Hepatitis C

OBJECTIVES:The treatment of patients with hepatitis C virus (HCV) genotype 1 with peginterferon plus ribavirin treatment for more than 48 weeks demonstrated high sustained virological response (SVR) rates. Although many studies extended the duration of therapy from 48 weeks to 72 weeks, the optimal duration has not yet been determined.METHODS:A total of 113 genotype 1b patients with high viral load were randomized at baseline to the standard (n=56) or extended (n=57) treatment group. The standard group patients received 48 weeks of peginterferon plus ribavirin treatment. In the extended group, the treatment was performed for 44 weeks after patients became negative for HCV RNA (total duration 48–68 weeks).RESULTS:The SVR rate of the standard and extended group was 36% (20 of 56) and 53% (30 of 57; P=0.07). However, the extended group patients who became negative for HCV RNA between weeks 16 and 24 had a significantly higher SVR rate (78%; 7 of 9) than that of standard group (9%, 1 of 11; P=0.005). The predictive factors for the SVR were the treatment regimen (the standard vs. extended treatment) and the time to HCV RNA negative–status.CONCLUSIONS:The extended treatment significantly increased the SVR rate in patients who were HCV RNA negative at 16–24 weeks.

Effect of interferon treatment on serum 2',5'-oligoadenylate synthetase levels in hepatitis C-infected patients.

Interferon (IFN) is widely used for patients with hepatitis C. Less than half of treated patients respond to IFN therapy, however, and increased resistance to IFN is particularly observed in genotype 1b patients. Recently, genotype 1b patients with the wild type sequence in the NS5A gene were shown to be resistant to therapy, suggesting that the NS5A protein may be involved to IFN resistance. Thus, we investigated the serum 2′,5′‐oligoadenylate synthetase (2′,5′‐OAS) levels before and during IFN treatment. In addition, other biochemical markers and NS5A mutations were also examined in 30 HCV genotype 1b‐positive patients. Before IFN treatment, 2′,5′‐OAS activity in sera was significantly lower in wild type patients than in mutant type patients. All patients were subsequently enrolled in IFN therapy, and 2′,5′‐OAS activity was elevated both in wild and mutant type patients, irrespective of the number of mutations in NS5A. Logistic regression analysis revealed that clearance of serum HCV RNA was independently related to the pretreatment viral load and NS5A mutations, but not to serum 2′,5′‐OAS activity. We concluded that the NS5A protein, that is associated with the outcome of IFN therapy, affects the kinetics of IFN‐induced molecules, such as 2′,5′‐OAS. 2′,5′‐OAS activity does not, however, seem to be related to long‐term virological response to IFN therapy. J. Med. Virol. 62:185–190, 2000.

Mutations in the NS5A Gene Predict Response to Interferon Therapy in Japanese Patients with Chronic Hepatitis C and Cirrhosis

The virus genotype, serum HCV-RNA level and liver histology are reported to be important factors in the response to interferon therapy. Recent studies have revealed that HCV NS5A 2209-2248 amino acid changes affect the response to interferon therapy of genotype 1b chronic hepatitis C. In contrast, some studies done in western countries have reported no such correlation. In the present study, interferon therapy was given to 58 Japanese patients, including 15 liver cirrhosis patients. NS5A 2209-2248 changes, the serum HCV level, ALT level, age and histology were examined in relation to the interferon effect. Twenty-four of the 58 patients (41%) showed a sustained virological response to the therapy. The responses to interferon therapy were significantly correlated with NS5A 2209-2248 changes (p < 0.0001), the HCV-RNA level (p < 0.0001) and histology (p < 0.0060). Among 15 liver cirrhosis patients, 3 of 6 mutant type patients showed a sustained virological response; 5 intermediate and 4 with wild type virus infected patients showed no responses. In conclusion, NS5A 2209-2248 changes may be a useful predictive marker of response to interferon therapy in addition to the serum HCV RNA level even in histologically advanced patients.

Interferon-γ brings additive anti-viral environment when combined with interferon-α in patients with chronic hepatitis C

Abstract T-cell hyporesponsiveness may lead to chronicity of hepatitis C virus (HCV) infection. We evaluated whether interferon (IFN)-γ injection can bring a Th1-dominant environment to patients with chronic hepatitis C. Seventeen patients with genotype 1b received natural IFN-α 5MU daily for the first 2 weeks and three times a week for the next 22 weeks followed by natural IFN-γ 1 MU daily for 2 weeks. In 4 of 17 patients (23.5%), alanine aminotransferase (ALT) was normalized and 3 of these 4 patients (75.0%) cleared HCV RNA. β2 microglobulin (BMG), neopterin and soluble (s) Fas increased with IFN-α and increased more with IFN-γ. Serum interleukin (IL)-12, CD4 and CD8 remained unchanged with IFN-α but increased after IFN-α was replaced by IFN-γ. IL-10 was not changed either with IFN-α or γ. Productions of IL-2, IFN-γ and tumor necrosis factor (TNF)-α by peripheral blood mononuclear cells did not change by IFN-α therapy, however, they were enhanced at the end of IFN-γ therapy. Productions of IL-2 and 4 were unaffected. These results show that some immune parameters become Th1-dominant by additional IFN-γ in patients with chronic hepatitis C. Combination of these two IFNs should be explored.

Interferon accumulation in cirrhotic rat liver

SUMMARY. In patients with chronic hepatitis C, the therapeutic effect of interferon (IFN) is influenced by the progression of liver disease. In a previous study, we showed that 2′,5′‐oligoadenylate synthetase activity in the liver homogenate was significantly lower in cirrhotic rats than in controls after injection of murine IFN. To determine the reason for this decrease, we injected IFN into rats with thioacetamide‐induced cirrhosis and used microautoradiography with human lymphoblastoid interferon ([125I]LyIFN). Accumulation of [125I]LyIFN in cirrhotic rat livers was approximately half of that in control rats (2880±900 vs 5770±600mm2, P<0.01). In the cirrhotic rat livers there were few grains on the hepatocytes, but many on collagen fibres. These results suggest that binding of IFN to its hepatocyte receptors is hindered in the presence of cirrhosis. The decreased amount of IFN reaching hepatocytes may contribute to the poor responses to IFN seen in patients with cirrhosis.

Evaluation of Resistance-Associated Substitutions in NS5A Using Direct Sequence and Cycleave Method and Treatment Outcome with Daclatasvir and Asunaprevir for Chronic Hepatitis C Genotype 1.

Background The aim of this study was to evaluate the efficacy of daclatasvir plus asunaprevir therapy in patients infected with hepatitis C virus and determine its relevance to resistant variants. Methods A total of 629 consecutive patients infected with hepatitis C virus genotype 1 were assessed. Daclatasvir (60 mg/day) plus asunaprevir (200 mg/day) was given for 24 weeks. The virological responses and resistance-associated substitutions of hepatitis C virus mutants were examined by the direct sequence and cycleave methods were evaluated. Results Overall, 89.4% (555/621) of patients exhibited a sustained virological response (SVR). The SVR rates in the patients with wild type, mixed, and mutant type Y93 by direct sequencing were 92.5% (520/562), 70.3% (26/37), and 42.9% (9/21), respectively. The SVR rates in the patients with 100%, 90%, 80%-30%, and 20%-0% Y93 wild by the cycleave method were 93.4% (456/488), 88.2%(30/34), 56.0%(14/25), and 36.8%(7/19), respectively. In contrast, the SVR rates for the wild type and mixed/mutant type L31 by direct sequencing were 90.2% (534/592) and 72.4% (21/29), respectively. In the multivariate analyses, the wild type Y93, no history of simeprevir therapy, the wild type L31, and low HCV RNA level were independent factors of SVR. Conclusion NS5A resistance-associated substitutions, especially Y93H, were major factors predicting the SVR. Although direct sequencing can predict the SVR rate, the cycleave method is considered to be more useful for predicting the SVR when used in combination.

Intraspousal transmission of GB virus C/hepatitis G virus in an hepatitis C virus hyperendemic area in Japan

ObjectiveAn immunoassay for antibodies against an hepatitis G virus (HGV) protein (anti-E2) was recently developed that might serve as a useful marker for diagnosing recovery from HGV infection.MethodsWe investigated the intraspousal transmission of GB virus C/hepatitis G virus (GBV-C/HGV) using both reverse transcription hemipolymerase chain reaction (RT-hemi-PCR for the 5′ untranslated region) and a recently developed anti-E2.ResultsThirty-two GBV-C/HGV-infected index subjects were selected from an hepatitis C virus hyperendemic area in Japan. Of the 32 subjects, seven (6.4%) were GBV-C/HGV RNA-positive, 24 (21.8%) were anti-E2-positive, and one (0.9%) was both GBV-C/HGV RNA- and anti-E2-positive. Among the 32 spouses of these subjects, GBV-C/HGV RNA, anti-E2, and both GBV-C/HGV RNA and anti-E2 positivity were detected in 0, 6, (18.8%), and one (3.1%) spouses, respectively (the total prevalence of GBV-C/HGV was 7 spouses [21.9%]). Thus, the intraspousal transmission of GBV-C/HGV was undeniable in these seven couples. The respective positive rates of 175 sex- and age-matched controls were 7 (4.0%), 26 (14.9%), and 0 (the total prevalence of GBV-C/HGV was 34 [19.4%]). No significant difference in positive rates was observed between the subjects/spouses and the controls. Five spouses among the seven couples who were positive for any of GBV-C/HGV markers had parenteral risk factors such as blood transfusion, acupuncture, and major surgery.ConclusionsBased on these observations, we cannot draw a definitive conclusion that intraspousal transmission of GBV-C/HGV had occurred among these seven couples.

Liver-Associated Natural Killer Activity in Cirrhotic Rats

An impaired host defense mechanism is well known in patients with liver cirrhosis (LC). Using a sinusoidal lavage method, lymphocytes were obtained from LC rats that were administered thioacetamide, and natural killer (NK) activity was measured by 5lCr‐release assay. The NK cell count was measured by flow cytometric analysis using monoclonal antibody (Mab) 3.2.3 and/or CD 3‐8+ as markers for NK cells, and by immunohistochemical staining using Mab 3.2.3. Furthermore, interferon (IFN) α was administered to LC rats and the subsequent changes in hepatic NK activity and NK cell count were observed. In the large granular lymphocyte (LGL)‐rich fraction (Fr.1, LGLs: 60‐90%), the NK activity was significantly lower in the LC rats (40.0±3.8%) compared to that in the control rats (48.4±4.3%) (P<0.005). In addition, the number of NK cells in the liver tissues of the LC rats was significantly lower compared to that in the liver tissues of the control rats by morphometric analysis (P<0.05). For LC rats, NK activity of the Fr.1 24 hr after IFNα administration (5×104 IU / 100 g body weight) increased significantly (P<0.005). Hepatic NK activity and NK cell count were reduced in the LC rats, and recovered following IFNα administration. The results obtained in this study may give clues to better understanding the impaired host defense mechanism in LC patients.