Recombinant fibroblast interferon and immune interferon for treating chronic hepatitis B virus infection: patients' tolerance and the effect on viral markers

IFN-γ: A Crucial Player in the Fight Against HBV Infection?

About 0.8 million people die because of hepatitis B virus (HBV) infection each year. In around 5% of infected adults, the immune system is ineffective in countering HBV infection, leading to chronic hepatitis B (CHB). CHB is associated with hepatocellular carcinoma, which can lead to patient death. Unfortunately, although current treatments against CHB allow control of HBV infection, they are unable to achieve complete eradication of the virus. Cytokines of the IFN family represent part of the innate immune system and are key players in virus elimination. IFN secretion induces the expression of interferon stimulated genes, producing proteins that have antiviral properties and that are essential to cell-autonomous immunity. IFN-α is commonly used as a therapeutic approach for CHB. In addition, IFN-γ has been identified as the main IFN family member responsible for HBV eradication during acute infection. In this review, we summarize the key evidence gained from cellular or animal models of HBV replication or infection concerning the potential anti-HBV roles of IFN-γ with a particular focus on some IFN-γ-inducible genes.

Inhibition of hepatitis B virus DNA replicative intermediate forms by recombinant interferon-γ

AIM: To evaluate the in vitro anti-HBV activity of recombinant human IFN-γ, alone and in combination with lamivudine.

METHODS: A recombinant baculovirus-HBV/HepG2 culture system was developed which could support productive HBV infection in vitro. Expression of HBsAg and HBeAg in infected HepG2 culture medium was detected by commercial enzyme immunoassays. HBV DNA replication intermediates were detected in infected cells by Southern hybridization and viral DNA load was determined by dot hybridization.

RESULTS: IFN-γ at 0.1 to 5 μg/L efficiently down regulated HBsAg expression in transduced HepG2 cells. At 5 μg/L, IFN-γ also suppressed HBV DNA replication in these cells. While treatment with a combination of lamivudine and IFN-γ showed no additive effect, sequential treatment first with lamivudine and then IFN-γ was found to be promising. In this culture system the best HBV suppression was observed with a pulse of 2 μmol/L lamivudine for two days, followed by 1 μg/L IFN-γ for another four days. Compared to treatment with lamivudine alone, the sequential use of 0.2 μmol/L lamivudine for two days, followed by 5 μg/L IFN-γ for six days showed a 72% reduction in HBV cccDNA pool.

CONCLUSION: This in vitro study warrants further evaluation of a combination of IFN-γ and lamivudine, especially in IFN-α non-responder chronic hepatitis B patients. A reduced duration of lamivudine treatment would also restrict the emergence of drug-resistant HBV mutants.

Assessment of natural and interleukin-2-induced production of interferon-gamma in patients with liver diseases

AIM: To determine whether the production of lower interferon gamma (IFNl) by lymphocytes in patients with liver diseases is due to defects of the lymphocytes themselves or to other cofactors, such as interleukin-2 (IL-2).

METHODS: Peripheral blood mononuclear cells (PBMCs) from patients with various liver diseases were cultured with or without phytohemagglutinin (PHA) and IL-2. The cells were harvested and counted, and the supernatants were tested for IFNl by a sensitive and quantitative ABC-enzyme-linked immunosorbent assay (ELISA).

RESULTS: IFNl was not found in serum samples from patients or normal individuals. However, IFNl was detectable in supernatants of non-induced and induced PBMCs by ABC-ELISA. In non-induced PBMCs (group 1), the content of IFNl in supernatants from control, chronic active hepatitis (CAH), chronic persistent hepatitis (CPH), and hepatocellular carcinoma (HCC) was 8.72/L, 5.03/L, 6.02/L, and 4.91/L, respectively. The production of IFNl in liver disease was significantly decreased compared to control. In PBMCs stimulated with PHA (group 2), the content of IFNl was 22.71/L, 17.12/L, 14.54/L, and 17.63/L, respectively. In PBMCs induced by IL-2 (group 3), the amount of IFNl in supernatant from control (60.67/L) was much larger than those from CAH (21.70/L), CPH (24.00/L), and HCC (19.15/L) (p < 0.01). When comparing the amount of IFNl in group 3 with that in group 1, we found that IFNl production was enhanced by nearly 4-folds in liver diseases and by over 7-fold in control. In contrast, the number of PBMCs, whether from liver diseases or from control, was increased by only approximately 3-fold.

CONCLUSION: The decreased production of IFNl in liver diseases, including HCC, is mainly due to endogenous defects of lymphocytes but may also involve a decrease in stimulating cofactors, such as IL-2.

Treatment of chronic hepatitis B

Chronic infection with the hepatitis B virus (HBV) is a major cause of worldwide morbidity and mortality. A large number of therapeutic approaches has been tried, including interferon (IFN), nucleoside analogues and immunomodulators. To date controlled clinical trials have shown that only IFN is of long-term value but many patients fail to respond to treatment. New approaches to treating patients with IFN-resistant hepatitis B are currently undergoing clinical and experimental evaluation, and it seems likely that new therapeutic agents will be available in the near future.

Interferon-gamma receptor expression in chronic hepatitis B virus infection

It is known that interferon-gamma (IFN gamma) is not effective in inducing a sustained inhibition of HBV replication in patients with chronic HBV infection in contrast to interferon-alpha (IFN alpha). To determine whether this was related to IFN gamma receptor (IFN gamma-R) underexpression, binding characteristics of IFN gamma to peripheral blood lymphocytes were studied in chronic HBV infection using radioiodinated recombinant IFN gamma. Peripheral blood lymphocytes from patients with chronic HBV infection (n = 20), normal healthy controls (n = 12) and patients with non-viral related chronic liver disease expressed a similar number of IFN gamma-R (medians (ranges): 1891 (1581-2515); 1916 (1589-2441); 1893 (1692-2104) sites/cell, respectively, p = N.S.) with a similar dissociation constant (Kd approximately 0.7-2.7 nM). There was no correlation between IFN gamma-R expression and serum transaminase, serum HBsAg and HBV-DNA titres and liver histology. IFN alpha therapy in vivo also did not enhance IFN gamma-R expression (n = 3). There is therefore, no evidence from this data that IFN gamma-R is underexpressed in patients with chronic HBV infection to account for the difference in clinical response to these two forms of therapy.

Effect of interferon-gamma on hepatitis B viral antigen expression in primary hepatocyte culture

Interferon-alpha has been shown recently to selectively enhance hepatocyte expression of HBsAg/pre-S2 in chronic hepatitis B virus infection in a way that may enhance immune recognition. To determine the effect of interferon-gamma on hepatitis B virus antigen expression, hepatocytes isolated from patients with chronic hepatitis B virus infection were incubated in the absence or presence of interferon-gamma and viral antigen expression was assessed by both radioimmunoassay and immunocytochemistry using appropriate monoclonal antibodies. Interferon-gamma inhibited the expression of all hepatitis B virus antigens tested. Intracellular HBsAg measured by radioimmunoassay of sonicated hepatocytes fell by 29% with 1 U/ml (p less than 0.01) and 36% with 10 U/ml of interferon-gamma (p less than 0.001) compared with control treatment. Secreted HBsAg was reduced by 19% with 10 U/ml of interferon-gamma (p less than 0.01). Intracellular HBeAg was also decreased by 29% with 1 U/ml (p less than 0.05) and 42% with 10 U/ml of interferon-gamma (p less than 0.05), but no significant change was found in the amount of secreted HBeAg. The proportion of hepatocytes containing various hepatitis B virus antigens and the intracellular viral antigen staining densities also fell significantly with interferon-gamma incubation. Interestingly, the addition of interferon-gamma abolished the augmenting effect of interferon-alpha on intracellular HBsAg. These data indicate that interferon-gamma, in contrast to interferon-alpha, has an inhibitory effect on hepatocyte expression of all hepatitis B virus antigens including HBsAg/pre-S2, suggesting that this may be one factor that accounts for their difference in clinical activity in patients with chronic hepatitis B virus infection.

Treatment with human gamma interferon of chronic hepatitis B: comparative study with alpha interferon

A pilot study was designed to determine the tolerance and effectiveness of natural or recombinant gamma interferon in patients with chronic hepatitis B. Sixteen patients received 0.5 to 3.0 million units (MU) per day of gamma interferon (IFN-gamma) for 7 days. Nineteen chronic hepatitis B patients who were treated with 5-6 MU leukocyte-derived alpha interferon (IFN-alpha) daily served as controls. All completed the treatment schedule. IFN-gamma exerted mild, but significant inhibitory effects (P less than .05) on serum DNA polymerase levels. However, the changes were significantly less (P less than .001) than those seen with IFN-alpha therapy when compared with percent change from basal values. In contrast, serum 2', 5'-oligoadenylate synthetase (2-5 AS) activities were markedly enhanced to a similar extent during therapy with both IFNs. Serum beta 2-microglobulin values were significantly increased by administration with both IFNs, although higher values were seen with IFN-gamma. Five patients received 1 MU IFN-gamma for 28 consecutive days and their HBeAg levels similarly decreased as those seen in patients treated with IFN-alpha. Side effects seemed to be greater during IFN-gamma therapy than IFN-alpha despite the lower doses used. The antiviral effect on serum HBV levels appeared less with IFN-gamma than with IFN-alpha. Alternatively immunomodulatory functions may have been enhanced with IFN-gamma in patients with chronic HBV infection.

A randomised controlled trial of recombinant interferon-gamma in Chinese patients with chronic hepatitis B virus infection

Nineteen Chinese patients with chronic hepatitis B virus (HBV) infection, seropositive for HBV e antigen (HBeAg) and HBV DNA on at least three occasions in 6 months, were randomised to receive either recombinant human interferon-gamma (rIFN gamma) 0.1 mg/m2 intramuscularly thrice weekly for 16 weeks (n = 11) or no anti-viral therapy (controls, n = 8). Five patients in the treatment group and four patients in the control group had persistently elevated serum alanine aminotransferases (ALT) of over two times the upper limit of normal before entering into the trial. rIFN gamma had no or minimal inhibitory effect on serum HBV DNA during treatment and no patient developed e-seroconversion or sustained loss of serum HBV DNA. Hepatitic flare, which occurred in a proportion of patients responding successfully to interferon-alpha (IFN alpha) therapy, was not observed with rIFN gamma treatment. Side-effects included pyrexia and mild headache that showed tachyphylaxis and were well tolerated by all patients. In the control group, one patient with elevated pre-entry serum ALT lost serum HBV DNA and seroconverted to anti-HBe. Another patient with elevated ALT lost serum HBV DNA transiently during therapy. In the dose given, rIFN gamma was safe but had no apparent anti-viral effects in Chinese patients with chronic HBV infection.

Effect of interferon administration on serum hepatitis C virus RNA in patients with chronic hepatitis C

Hepatitis C virus RNA as detected by reverse transcription and nested polymerase chain reaction was monitored in 16 patients with chronic hepatitis C treated with interferon. Hepatitis C virus RNA became undetectable after 4 to 8 wk of interferon administration in 13 of the 16 patients. During 6 mo of follow-up, 5 of the 13 patients who became negative for hepatitis C virus RNA after interferon administration remained negative, and all five continued to have normal ALT levels. Repeat liver biopsy in these five patients revealed histological improvement. Antibody to hepatitis C virus, which was initially positive in all treated patients, fell to undetectable levels in three of the five patients. In contrast, aminotransferase levels rose again in all eight patients who had become hepatitis C virus RNA negative but had again exhibited hepatitis C virus RNA after completion of therapy. In 16 untreated patients, hepatitis C virus RNA remained detectable. These results indicate that detection of hepatitis C virus RNA may be useful as a marker of viral replication in chronic hepatitis C; they also suggest that interferon should again be administered to patients who become hepatitis C virus RNA negative on treatment but again exhibit this marker of viral replication when treatment is stopped.

Effect of sizofiran, a polysaccharide, on interferon gamma, antibody production and lymphocyte proliferation specific for hepatitis B virus antigen in patients with chronic hepatitis B

To examine whether sizofiran (SPG), a polysaccharide isolated from Schizophyllum commune Fries, could modulate the immune response of immunocompetent cells to hepatitis B virus (HBV) nucleocapsid antigens, we investigated in vitro the production of interferon-gamma (IFN-gamma) and antibody (antibody to HB core and e antigens; anti-HBc and anti-HBe), and proliferation by peripheral blood mononuclear cells (PBMC) from six patients with chronic hepatitis B and four control individuals in the presence of recombinant HBcAg and purified HBeAg. Sizofiran alone in culture and in combination with HBV Ag was found to enhance IFN-gamma production and the proliferative response of PBMC from the patients compared with corresponding medium or HBV Ag alone culture. In contrast, antibody production was not elicited by SPG alone, but amplified by the drug in HBcAg-stimulated culture. In vitro leukocyte IFN-alpha addition increased IFN-gamma production, but suppressed the proliferation of PBMC from both controls and patients in the presence or absence of SPG and HBV Ag. These results indicate that SPG is able to modulate both cellular and humoral immune responses specific for nucleocapsid antigens in patients with chronic hepatitis B.

A randomized, controlled trial of interferon alfa-2b alone and after prednisone withdrawal for the treatment of chronic hepatitis B. The Hepatitis Interventional Therapy Group

BACKGROUND AND METHODS

Chronic hepatitis B is a common and often progressive liver disorder for which there is no accepted therapy. To assess the efficacy of treatment with interferon, we randomly assigned patients with chronic hepatitis B to one of the following regimens: prednisone for 6 weeks followed by 5 million units of recombinant interferon alfa-2b daily for 16 weeks; placebo followed by 5 million units of interferon daily for 16 weeks; placebo followed by 1 million units of interferon daily for 16 weeks; or observation with no treatment.

RESULTS

Hepatitis B e antigen and hepatitis B viral DNA disappeared from serum significantly more often in the patients given prednisone plus interferon (16 of 44 patients, or 36 percent) or 5 million units of interferon alone (15 of 41; 37 percent) than in the untreated controls (3 of 43; 7 percent; P less than 0.001); the difference between those given 1 million units of interferon (7 of 41; 17 percent) and the controls was not significant. The strongest independent predictor of a response to treatment was the amount of hepatitis B viral DNA in serum at entry (P less than 0.0001). Of the 38 patients who responded to interferon, 33 (87 percent) had normal serum aminotransferase levels after therapy; 11 patients who responded (29 percent), but no controls, lost the hepatitis B surface antigen. Blinded histologic assessment revealed a significant improvement in periportal necrosis in the treated patients (P = 0.03).

CONCLUSIONS

In chronic hepatitis B, treatment with interferon alfa-2b (5 million units per day for 16 weeks) was effective in inducing a sustained loss of viral replication and achieving remission, assessed biochemically and histologically, in over a third of patients. Moreover, in about 10 percent of the patients treated with interferon, hepatitis B surface antigen disappeared from serum.

Therapy of chronic hepatitis B with recombinant human alpha and gamma interferon

Eight patients with chronic hepatitis B entered a pilot study of gamma interferon and alpha interferon in combination. Gamma interferon alone had minimal inhibitory effects on serum levels of hepatitis B virus as monitored by serum HBV DNA and DNA-polymerase activity. The drug also gave troublesome side effects. In contrast, alpha interferon had more potent inhibitory effects on serum HBV levels and fewer side effects. When combined, the two interferons showed no additive or synergistic effects in inhibiting serum levels of HBV DNA or DNA polymerase. These findings indicate that the addition of gamma interferon to alpha interferon provides no additional antiviral effects but contributes significantly to side effects.

Alpha-interferon therapy of chronic hepatitis B. Current status and recommendations

Antiviral therapy for chronic hepatitis B is still experimental. Recent studies suggest that a 3- to 6-month course of alpha-interferon in doses ranging from 5-10 million units (5 million units/m2) given daily or three times weekly will result in a clinical, biochemical and serological remission in 30-40% of patients with well compensated liver disease and with hepatitis B virus DNA and hepatitis B e antigen in serum. Features that predict a beneficial response to treatment include high initial serum aminotransferase activities and low levels of circulating viral DNA. Asian patients and children may be less likely to respond to treatment than Caucasian adults. Pre-treatment of patients with a 6-week course of high doses of prednisone may help to increase the response rate to alpha-interferon alone, but this approach should be used only in patients with mild disease and perhaps in patients who have previously failed to respond to alpha-interferon alone. The best approach to treatment of patients with complications of chronic hepatitis B and atypical serological patterns is still uncertain. The efficacy and the side effects of alpha-interferon therapy should be carefully balanced in the decision to treat patients with chronic hepatitis B. Future studies should focus upon the use of newer antiviral agents alone or in combination with alpha-interferon.

Beta- and gamma-interferon in chronic active hepatitis B. A pilot trial of short-term combination therapy

A controlled, randomized trial of a short-term, medium-dose combination therapy of beta- and gamma-interferon was performed in 20 patients with chronic active hepatitis B. According to clinical, biochemical, and histologic findings that were followed up for 16-24 mo, the combined treatment was successful in 5 of 10 patients. Two of the patients eliminated the virus completely, as confirmed by Southern blotting of hepatocellular deoxyribonucleic acid (DNA) against hepatitis B virus DNA. In the other 3 responders hepatitis B surface antigen persisted in the absence of hepatitis B e antigen, replicating hepatitis B virus DNA in the liver and inflammatory disease activity. Two of these responders with persistent hepatitis B surface antigen had hepatitis B virus DNA integrated into the hepatocyte genome and 1 responder had nonreplicating, episomal virus DNA. In the control group of 10 patients one spontaneous remission occurred. Antiviral treatment was significantly (p less than 0.05) more successful within the first 4 yr after infection (5 responders of 6 treated patients) than after longer disease duration (no responder of 4 treated patients). The results of this pilot study suggest that a combination of beta- and gamma-interferon may be an effective therapy for chronic active hepatitis B when started early after infection.