A phase I/II study of recombinant human interleukin-12 in patients with chronic hepatitis C

Reprogrammed chondrocytes engineered to produce IL-12 provide novel ex vivo immune-gene therapy for cancer

AIM

The somatic cell reprogramming technology was applied to a novel and promising ex vivo immune-gene therapy strategy for cancer. To establish a novel ex vivo cytokine gene therapy of cancer using the somatic cell reprogramming procedures.

METHODS

Mouse fibroblasts were converted into chondrocytes and subsequently transduced with IL-12 gene. The resultant IL-12 induced chondrogenic cells were irradiated with x-ray and inoculated into mice bearing CT26 colon cancer.

RESULTS

The irradiation at 20 Gy or higher totally eliminated the proliferative potential of the cells, while less significantly influencing the IL-12 production from the cells. An inoculation of the irradiated IL-12 induced chondrogenic cells significantly suppressed tumor by inducing tumor-specific cytotoxic T lymphocytes, enhancing natural killer tumoricidal activity and inhibiting tumor neoangiogenesis in the mice.

CONCLUSION

The somatic cell reprogramming procedures may provide a novel and effective means to treat malignancies.

Dysfunctional CD8+ T cells in hepatitis B and C are characterized by a lack of antigen-specific T-bet induction

In humans infected with hepatitis B or C, high expression of a protein called T-bet in virus-fighting immune cells is associated with spontaneous clearance of the virus. Absence of T-bet was more often seen in patients whose infections became chronic.

The transcription factor T-bet regulates the production of interferon-γ and cytotoxic molecules in effector CD8 T cells, and its expression correlates with improved control of chronic viral infections. However, the role of T-bet in infections with differential outcome remains poorly defined. Here, we report that high expression of T-bet in virus-specific CD8 T cells during acute hepatitis B virus (HBV) and hepatitis C virus (HCV) infection was associated with spontaneous resolution, whereas T-bet deficiency was more characteristic of chronic evolving infection. T-bet strongly correlated with interferon-γ production and proliferation of virus-specific CD8 T cells, and its induction by antigen and IL-2 stimulation partially restored functionality in previously dysfunctional T-bet–deficient CD8 T cells. However, restoration of a strong interferon-γ response required additional stimulation with IL-12, which selectively induced the phosphorylation of STAT4 in T-bet⁺ CD8 T cells. The observation that T-bet expression rendered CD8 T cells responsive to IL-12 suggests a stepwise mechanism of T cell activation in which T-bet facilitates the recruitment of additional transcription factors in the presence of key cytokines. These findings support a critical role of T-bet for viral clearance and suggest T-bet deficiency as an important mechanism behind chronic infection.

Review article: management of chronic hepatitis C in patients with contraindications to anti-viral therapy

BACKGROUND

There are patients with chronic hepatitis C who are not eligible for the current interferon-based therapies or refuse to be treated due to secondary effects.

AIM

To provide information on alternative treatments for the management of these patients.

METHODS

A PubMed search was performed to identify relevant literature. Search terms included hepatitis C virus, anti-inflammatory treatment, antioxidant, natural products and alternative treatment, alone or in combination. Additional publications were identified using the references cited by primary and review articles.

RESULTS

Several approaches, such as iron depletion (phlebotomy), treatment with ursodeoxycholic acid or glycyrrhizin, have anti-inflammatory and/or anti-fibrotic effects. Life interventions like weight loss, exercise and coffee consumption are associated with a biochemical improvement. Other alternatives (ribavirin monotherapy, amantadine, silibinin, vitamin supplementation, etc.) do not have any beneficial effect or need to be tested in larger clinical studies.

CONCLUSION

There are therapeutic strategies and lifestyle interventions that can be used to improve liver damage in patients with chronic hepatitis C who cannot receive or refuse interferon-based treatments.

CD27 engagement by a soluble CD70 protein enhances non-cytolytic antiviral activity of CD56bright natural killer cells by IFN-γ secretion

We investigated regulation of human NK cell function by CD27 engagement using a recombinant soluble CD70 protein. CD27 was preferentially expressed on CD56(bright) NK cells, and soluble CD70 protein bound to CD27(+)CD56(bright) NK cells. While soluble CD70 protein enhanced IFN-γ secretion by CD56(bright) NK cells in the presence of IL-12, it augmented neither cytolytic activity nor proliferation of NK cells. Thus, we next asked if soluble CD70 protein could be used to induce non-cytolytic antiviral activity of NK cells using an in vitro hepatitis C virus (HCV) infection system. Soluble CD70 protein stimulated NK cells to suppress HCV replication by enhancing NK cell IFN-γ secretion without killing infected cells. Taken together, we demonstrate that CD27 engagement by a soluble CD70 protein enhances non-cytolytic antiviral activity of CD56(bright) NK cells by IFN-γ secretion. Thus, this soluble CD70 protein may be useful for the treatment of viral infections such as HCV infection.

Target-mediated disposition model describing the dynamics of IL12 and IFNγ after administration of a mifepristone-inducible adenoviral vector for IL-12 expression in mice

Interleukin-12 (IL12) is a cytokine with potential applications in the treatment of cancer given the potent immune response that it triggers, in part due to its ability to stimulate expression of interferon-γ (IFNγ). To avoid the toxicity associated with systemic exposure to IL12, a high-capacity adenoviral vector carrying a liver-specific, mifepristone-inducible IL12 expression system (HC-Ad/RUmIL12) has been developed. However, the maintenance of IL12 expression at therapeutic levels is compromised by the inhibitory effect of IFNγ on inducible systems. The aim of this work is to develop a semi-mechanistic model to characterize the relationship between IL12 and IFNγ in wild-type and knock-out mice for the IFNγ receptor treated with HC-Ad/RUmIL12 under different dosing regimens in order to better understand the key mechanisms controlling the system. Rapid binding was considered to account for target-mediated disposition exhibited by both cytokines (equilibrium dissociation constant were 18 and 2.28 pM for IL12 and IFNγ, respectively). The final model included: (1) IFNγ receptor turnover, (2) irreversible free cytokine elimination from the serum compartment, (3) internalization of the IL12 receptor complex, (4) IL12 expression upregulated by the co-administration of the adenoviral vector and mifepristone and downregulated by the IFNγ receptor, and (5) synthesis of IFNγ controlled by the relative increments in the bound IL12. In conclusion, a model simultaneously describing the kinetics of IL12 and IFNγ in the context of gene therapy was developed and validated with additional data. The model was applied to design an experimental dosing protocol intended to maintain sustained therapeutic IL12 levels.

Immunotherapy of viral infections

Among the microorganisms that cause diseases of medical or veterinary importance, the only group that is entirely dependent on the host, and hence not easily amenable to therapy via pharmaceuticals, is the viruses. Since viruses are obligate intracellular pathogens, and therefore depend a great deal on cellular processes, direct therapy of viral infections is difficult. Thus, modifying or targeting nonspecific or specific immune responses is an important aspect of intervention of ongoing viral infections. However, as a result of the unavailability of effective vaccines and the extended duration of manifestation, chronic viral infections are the most suitable for immunotherapies. We present an overview of various immunological strategies that have been applied for treating viral infections after exposure to the infectious agent.

Immune-based therapy for chronic hepatitis C

Chronic, persistent HCV infection is a public health issue. It often progresses to life-threatening complications, including liver cirrhosis and hepatocellular carcinoma. The current standard therapy is a combination of pegylated IFN-alpha and ribavirin. This therapy results in a sustained virologic response in only 50% of patients infected with HCV genotype 1 and is often accompanied with substantial side-effects. Therefore, it is imperative to develop novel therapies with higher efficacy and less substantial side-effects. Impaired immune responses to HCV are key features of chronic HCV infection; thus, intervention strategies typically involve boosting the immune responses against HCV. These immune-based therapies for chronic HCV infection include therapeutic vaccines, antagonists of T cell inhibitory factors, anti-HCV neutralizing antibodies, cytokines, and agonists for TLRs. Currently, various types of immune-based therapies are under development that might be used as a monotherapy or in combination with other antiviral drugs for the treatment of chronic HCV infection.

Prospects for use of interleukin-12 as a mucosal adjuvant for vaccination of humans to protect against respiratory pneumococcal infection

Mucosal vaccination against pneumococcal disease offers potential protection against otitis media, pneumonia and invasive disease, including providing herd benefit by reducing pathogen carriage. The major obstacle, however, remains the lack of a suitable adjuvant for use in humans. Animal models have demonstrated success of interleukin-12 (IL-12) as an adjuvant for mucosal vaccines using recombinant pneumococcal protein antigens. This review examines the biology of the IL-12 cytokine family, the toxicity of IL-12 in human studies and suggests approaches by which IL-12 could be developed as a mucosal adjuvant with pneumococcal protein based vaccines, for use in humans.

Nanogel DDS enables sustained release of IL-12 for tumor immunotherapy

For a valid cytokine immunotherapy of malignancies, a suitable delivery system that ensures slow-release of cytokines is required, because short half-life in vivo of the molecules ruins therapeutic efficacy while causing severe systemic toxic effects. We previously showed that the cholesterol-bearing pullulan (CHP)-based hydrogel nanoparticles, or nanogel, encapsulates, stabilizes and releases various molecules. Here we applied this nanogel to administration in vivo of interleukin-12 (IL-12). Recombinant murine IL-12 (rmIL-12) was successfully incorporated into CHP nanogel simply by incubated with CHP at room temperature. After subcutaneously injected into mice, the CHP/rmIL-12 complex led to a prolonged elevation in IL-12 concentration in the sera. Repetitive administrations of the CHP/rmIL-12, but not rmIL-12 alone, induced drastic growth retardation of preestablished subcutaneous fibrosarcoma without causing any serious toxic event. The present study proposes a novel therapeutic intervention technology, taking advantage of slow and sustained release of bioactive cytokines from the self-assembling biocompatible nanoparticles.

Modulation of the IL-12/IFN-γ axis by IFN-α therapy for hepatitis C

Although IFN-alpha forms the foundation of therapy for chronic hepatitis C, only a minority of patients has a sustained response to IFN-alpha alone. The antiviral activities of IFN-alpha formed the rationale for its use in viral hepatitis. However, IFN-alpha and the other Type I IFNs are also pleiotropic immune regulators. Type I IFNs can promote IFN-gamma production by activating STAT4 but can also inhibit production of IL-12, a potent activator of STAT4 and IFN-gamma production. The efficacy of IFN-alpha in the treatment of hepatitis C may therefore depend in part on the balance of IFN-gamma-inducing and IL-12-suppressing effects. We characterized the effects of pegylated IFN-alpha therapy for hepatitis C on the capacity of patients' PBMC to produce IL-12 and IFN-gamma ex vivo. Cells from patients with a sustained virological response to therapy had significantly greater levels of IFN-alpha-driven IFN-gamma production prior to treatment than those from nonresponding patients. No differences in pretreatment IL-12 productive capacity were seen between patient groups. However, therapy with IFN-alpha led to suppression of inducible IL-12 production throughout the course of therapy in both groups of patients.

Treatment of chronic hepatitis C in non-responsive patients with pegylated interferon associated with ribavirin and thalidomide: report of six cases of total remission

Hepatitis C virus (HCV) infection is an important public health issue worldwide. It is estimated that over 170 million people are infected with the virus. The present study reports six cases in which patients did not respond to combination therapy with pegylated interferon and ribavirin. However, after the addition of thalidomide to the therapy, the patients presented negative RNA PCR. The use of thalidomide combined with pegylated interferon and ribavirin for the treatment of hepatitis C is described here for the first time in the related literature.

Immunomodulatory therapy for chronic hepatitis B virus infection

Hepatitis B virus (HBV) is one of the most prevalent viral pathogens of man with around 350 million chronically infected patients. It has been postulated that in persistently infected individuals the HBV-specific immune response is too weak to eliminate HBV from all infected hepatocytes, but sufficiently strong to continuously destroy HBV-infected hepatocytes and to induce chronic inflammatory liver disease. The primary aim in the treatment of chronic hepatitis B is to induce sustained disease remission and prevent serious complications like liver failure and/or hepatocellular carcinoma. The recent emergence of drug-resistant HBV mutants and post-treatment relapse as a consequence of nucleoside analogue monotherapy emphasizes that the principal goal should be to stimulate a successful immune response. In this paper we will focus on the immune response to HBV and we will review reported data on immunotherapeutic strategies like immunomodulatory drugs (cytokines and Thymic derivates) and vaccine therapies using currently available recombinant anti-HBV vaccines, lipopeptide-based T cell vaccine and newly developed genetic vaccines.

Therapeutic modalities in hepatitis C: challenges and development

Our understanding of the pathogenicity of hepatitis C virus (HCV) is based on patients infected chronically for >20 years. The lack of a suitable animal model, the narrow host range of the virus, and the protracted onset of liver disease induced by HCV have hampered advances in treatment. In spite of these problems, we identified patient and viral characteristics that predict responses to current therapies, including HCV genotype, viral load, body weight, age, liver histology, co-infection with HIV and treatment adherence and tolerance. Interferon (IFN) alpha was the first therapy for chronic HCV infection. The combination of IFN plus ribavirin increases sustained virological response rates compared with IFN alone. Two pegylated IFNs have been developed and are widely approved for the treatment of chronic hepatitis C: peginterferon alpha-2a (40 KD), and pegylated IFN alpha-2b (12 KD). These products have reduced systemic clearance, prolonged half-lives and reduced antigenicity compared with conventional IFN. The reduced clearance results in sustained plasma levels of the drug and allows for once-weekly dosing. Pegylated IFN alpha-2b (12 KD) has a small, linear polyethylene glycol (PEG) moiety and has an intermediate duration of activity; peginterferon alpha-2a (40 KD) incorporates a large, branched-chain PEG moiety and has a longer half-life than both conventional IFN alpha and pegylated IFN alpha-2b (12 KD). The combination of a pegylated IFN plus ribavirin significantly increases sustained virological response rates compared with conventional IFN plus ribavirin in patients with chronic hepatitis C and is now recognized as the standard of care for these patients.

Association of interleukin-12 p40 gene 3’-untranslated region polymorphism and outcome of HCV infection

AIM: To investigate the effect of interleukin-12 p40 gene (IL12B) 3’-untranslated region polymorphism on the outcome of HCV infection.

METHODS: A total of 133 patients who had been infected with HCV for 12-25 (18.2 ± 3.8) years, were enrolled in this study. Liver biochemical tests were performed with an automated analyzer and HCV RNA was detected by fluorogenic quantitative polymerase chain reaction. B-mode ultrasound was used for liver examination. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used for the detection of IL12B (1188A/C) polymorphism.

RESULTS: Self-limited infection was associated with AC genotype (OR = 3.48; P = 0.001) and persistent infection was associated with AA genotype (OR = 0.34; P = 0.014) at site 1188 of IL12B. In patients with persistent HCV infection, no significant differences were found regarding the age, gender, duration of infection and biochemical characteristics (P > 0.05). According to B-mode ultrasound imaging and clinical diagnosis, patients with persistent infection were divided into groups based on the severity of infection. No significant differences were found in the frequency of IL-12 genotype (1188A/C) between different groups (P > 0.05).

CONCLUSION: The polymorphism of IL12B (1188A/C) appears to have some influence on the outcome of HCV infection.

A multicenter study of recombinant human interleukin 12 for the treatment of chronic hepatitis C virus infection in patients nonresponsive to previous therapy

Recombinant human interleukin 12 (IL-12) is an immunomodulatory cytokine that is active against several viruses. Treatment options in patients with chronic hepatitis C with nonresponse to interferon (IFN)-based therapy are limited. Prior dose-ranging studies have indicated drug tolerability and transient suppression of hepatitis C virus (HCV) RNA by IL-12. The aim of this study was to determine the safety and efficacy of prolonged IL-12 therapy in patients who have failed treatment with IFN-alpha +/- ribavirin. A total of 225 patients at 21 U.S. sites who had a history of nonresponse to IFN-alpha or combination IFN-alpha plus ribavirin for treatment of HCV were randomized to 500 ng/kg IL-12 or placebo subcutaneously twice weekly for 12 weeks. The groups were then unblinded; patients receiving IL-12 continued for another 36 weeks, and the placebo group received 48 weeks of treatment with IL-12 in an open-label fashion. HCV RNA, serum alanine aminotransferase (ALT) level, and a repeat liver biopsy were assessed at 24 weeks following therapy. Approximately 1% (2 of 160) of nonresponsive patients enrolled for treatment had a sustained virologic response to IL-12 therapy, but 3% (7 of 225) developed severe adverse events probably related to treatment, resulting in early termination of the trial. Common adverse effects reported by most patients included chills, fever, fatigue, headache, and arthralgia. At termination of the study, 160 patients had received at least 8 weeks of treatment with IL-12. Paired liver biopsy specimens were available for evaluation in 54 patients, but there were no significant changes in Knodell fibrosis or histologic activity index (HAI) scores. In conclusion, IL-12 as monotherapy at the doses used in this trial for chronic hepatitis C has low efficacy, was poorly tolerated, and is unlikely to provide an alternative to conventional IFN-based therapy.

Cytokines as clinical adjuvants: how far are we?

In spite of the explosive growth in the discovery of cytokines and chemokines and in the understanding of their modes of action, clinical use of such agents as adjuvants has been primarily restricted to patients with cancer or chronic viral infections suffering from various levels of immune impairment and for whom the chemotherapeutic armamentarium, as well as other forms of immunotherapy, have been exhausted. This cautious approach has been justified by the difficulties inherent to the biological function and delivery of such pleiotropic agents, where doses needed to achieve the targeted immune enhancement often result in serious side effects, especially during systemic administration. In addition, optimization of dosages, administration schedules and biological effects in humans often do not correlate well with preclinical data derived from animal models. Nevertheless, novel preventive immunization strategies that target a precise type of immune response in immunocompetent individuals are expected to greatly benefit from the incorporation of cytokines and chemokines. This review provides an overview of current clinical administration of cytokines as well as a description of select Phase I testing of new agents designed to enhance immune defenses in vivo.

Optimized expression and specific activity of IL-12 by directed molecular evolution

DNA delivery of IL-12 has shown promise in reducing the toxic side effects associated with administration of recombinant human (h)IL-12 protein while maintaining the ability to inhibit tumor growth and abolish tumor metastases in animal models. We have developed a more potent version of IL-12 by using DNA shuffling and screening to improve its expression in human cells and specific activity on human T cells. The most improved evolved IL-12 (EvIL-12) derived from seven mammalian genes encoding both the p35 and p40 subunits of IL-12 showed a 128-fold improvement in human T cell proliferation compared with native hIL-12 during the initial screening of supernatants from transected cells. When purified hIL-12 and EvIL-12 proteins were compared in vitro in human T cell proliferation and Th1 differentiation assays, it was demonstrated that EvIL-12 exhibited a concomitant 10-fold increase in the specific activity of the protein compared with hIL-12. Furthermore, DNA shuffling improved the level of expression and homogeneity of the heterodimer synthesized by 293 human embryonic kidney cells transfected with EvIL-12 by at least 10-fold. Molecular analysis of the variant revealed strategic placement of amino acid substitutions that potentially may facilitate heterodimer formation and product expression. The enhanced expression and biological activity of EvIL-12 may improve the effectiveness of IL-12 gene-based vaccines and therapeutics without the toxic side effects sometimes associated with hIL-12 protein administration.

Th1/Th2 cytokine imbalance in patients with Sjögren syndrome secondary to hepatitis C virus infection

OBJECTIVE

To investigate if the serum immunologic profile, as delineated by serum circulating levels of Th1/Th2 cytokines and autoantibodies, is different in patients with Sjögren syndrome (SS) with and without hepatitis C virus (HCV) infection.

METHODS

This study included 20 patients with HCV-related SS and 47 consecutive patients with primary SS. All fulfilled 4 or more of the modified 1996 European criteria for SS. Serum levels of interleukin (IL)-2 (pg/mL), srIL-2 (pM), tumor necrosis factor (TNF)-alpha (pg/mL), IL-6 (pg/mL), and IL-10 (pg/mL) were determined using enzyme immunoassay. We also analyzed the following immunologic tests: anti-nuclear antibodies (ANA), anti-mitochondrial antibodies (AMA), anti-parietal cell antibodies (PCA), anti-smooth muscle antibodies (SMA), anti-liver-kidney microsome antibodies type-1 (LKM-1), anti-Ro/SS-A, anti-La/SS-B, rheumatoid factor (RF), complement factors (C3 and C4), and cryoglobulins.

RESULTS

Of the 20 patients with HCV-related SS, 18 were women and 2 men (mean age, 66 years). Patients with HCV-related SS had a different cytokine profile compared with patients with primary SS, with higher circulating levels of IL-6 (73.6 v 33.0 pg/mL, P =.045), IL-10 (6.7 v 3.1 pg/mL, P =.01), srIL-2 (124.6 v 72.7 pM, P =.001), and TNF-alpha (59.8 v 31.7 pg/mL, P =.003). The main immunologic features were ANA, detected in 75% of patients, RF in 63%, cryoglobulinemia in 50%, hypocomplementemia in 40%, SMA in 30%, PCA in 25%, anti-Ro/SS-A in 25%, AMA in 20% and anti-La/SS-B in 16%. When compared with primary SS patients, those with HCV-related SS had a higher prevalence of AMA (20% v 2%, P =.025), hypocomplementemia (40% v 11%, P =.015), and cryoglobulinemia (50% v 12%, P =.003).

CONCLUSION

Although chronic HCV infection may mimic the main clinical, histologic and immunologic features of primary SS, patients with HCV-related SS showed some differentiated characteristics, including a predominant Th2 pattern and a higher frequency of cryoglobulinemia and hypocomplementemia (features closely related to HCV). This suggests that the SS observed in some HCV patients should be interpreted as one of the extrahepatic manifestations of chronic HCV infection.

A Phase I, placebo-controlled trial of multi-dose recombinant human interleukin-12 in patients with HIV infection

OBJECTIVES

Interleukin (IL)-12 is a cytokine that stimulates T lymphocytes and natural killer cells to generate a Type 1 T-helper lymphocyte immune response. The primary objective of this study was to determine the safety and immunologic activity of repeated recombinant human IL-12 (rhIL-12) dosing in HIV-infected patients over a broad range of the HIV disease spectrum.

DESIGN

A randomized, placebo-controlled, Phase 1 trial design was chosen to control for the effects of HIV disease alone on safety and immunologic measurements.

METHODS

HIV-infected patients on antiretroviral therapy received rhIL-12 or placebo twice weekly for 4 weeks. Subjects were monitored for safety and changes in absolute lymphocyte subset number, serum interferon (IFN)gamma and neopterin levels, plasma HIV RNA level, peripheral blood mononuclear cell (PBMC)-inducible IFNgamma responses to mitogen, and PBMC proliferative responses to phytohemagglutinin, tetanus, Candida, Mycobacterium avium complex, streptokinase, and HIV p24 and gp160 antigens.

RESULTS

rhIL-12 was well tolerated at doses up to 100 ng/kg in subjects enrolled with CD4 cell counts < 50 x 10(6) cells/l and at all doses in subjects with CD4 cell counts of 300 x 10(6)-500 x 10(6) cells/l. rhIL-12 resulted in dose-related increases in serum neopterin (particularly in subjects with baseline CD4 cell counts of 300-500 x 10(6) cells/l) but in no significant changes in other immunologic measurements or plasma HIV RNA levels.

CONCLUSIONS

rhIL-12 dosed twice weekly at < or = 100 ng/kg was well tolerated in HIV-infected patients and resulted in dose-related increases in serum neopterin (possibly reflecting the effect of some degree of IFNgamma induction). However, there was no evidence of improvement in antigen-specific immune response.

Present treatment expectations and risks of chronic hepatitis C

During recent years, the treatment of chronic hepatitis C has increased in efficacy. Initially, the only approved treatment for this disease was interferon-alpha (IFN-alpha) monotherapy, achieving a 15% rate of sustained response. Subsequently, a combination of IFN-alpha plus ribavirin showed a greater efficacy: up to 40% success with 3 MU of IFN-alpha three times weekly and 1000-1200 mg of ribavirin daily in naive patients and in those who had relapsed after a course of IFN-alpha therapy. Pegylated interferon (PEG-IFN), due to its better efficacy and tolerance, has displaced the use of recombinant IFN. Nevertheless, the sustained response rate mainly depends on HCV RNA load and HCV genotype. Presumably, in future, new strategies based on gene therapy will play an important role in the treatment of chronic hepatitis C.

Interleukin-12 in the treatment of chronic hepatitis B and C

Interleukin-12 plays a central role in mounting an effective cellular immune response directed towards elimination of intracellular pathogens. In two open label, multicenter, dose-escalation phase I/II studies tolerability, pharmacokinetics, pharmacodynamics, and efficacy of subcutaneously administered recombinant human interleukin-12 (rHuIL-12) was assessed in the treatment of chronic hepatitis B and C. Forty-six patients with chronic hepatitis B and 60 patients with chronic hepatitis C were treated for 12 and 10 consecutive weeks, respectively. rHuIL-12 was generally well tolerated, but was associated with temporary decreases in neutrophils and lymphocyte counts, and with elevations in serum transaminases and bilirubin. Serum IL-12 levels observed were higher at 0.5 microg/kg compared with 0.25 microg/kg doses, suggesting a dose-related increase in systemic exposure of IL-12. Measurable levels of interferon-gamma were also observed at the highest dose of 0.5 microg/kg. At the end of treatment HBV DNA clearance was greater in patients treated with 0.50 microg/kg (25%) or with 0.25 microg/kg (13%) compared with those given 0.03 microg/kg. In patients with chronic hepatitis C, HCV RNA remained detectable in all patients. A more than 50% decrease in pretreatment HCV RNA levels was observed in 3/16 patients (0.03 microg/kg), in 3/14 (0.10 microg/kg), in 6/15 (0.25 microg/kg), and in 8/15 patients of the 0.5 microg/kg dose group. In conclusion, antiviral activity of rHuIL-12 in patients with chronic hepatitis B or C does not appear to be advantageous in comparison to other currently available treatments.

Neopterin measurement in clinical diagnosis

Neopterin is a marker associated with cell-mediated immunity. It is produced in monocytes/macrophages primarily upon stimulation with interferon-gamma. Due to its chemical structure, neopterin belongs to the class of pteridines. It is excreted in an unchanged form via the kidneys. Serum levels above 10 nmol/L are regarded as elevated. The levels of neopterin in body fluids are elevated in infections, autoimmune diseases, malignancies, allograft rejection, cardiac and renal failure, coronary artery disease and myocardial infarction. Neopterin measurements not only provide an insight into the present state of cell-mediated immune response but also allow monitoring and prognosis of disease progression.

Experimental and emerging therapies for chronic hepatitis C virus infection

Hepatitis C virus infection is prevalent throughout the world and is associated with substantial morbidity, mortality and health economic burden. No effective preventative measure, including vaccination, is currently available. Incremental and substantial progress in the rate of viral eradication using interferon-based therapies has been made over the past decade. The most recent advance has been related to the development of a pegylated form of IFN-alpha by two independent pharmaceutical companies. Pegylation of IFN-alpha appears to prolong its half-life, allowing for less frequent dosing. Reports have suggested that pegylated interferons are also associated with better efficacy for viral eradication in patients with hepatitis C virus. Slower progress also has been made in developing non-interferon-based therapeutic agents against hepatitis C virus, including protease inhibitors, helicase inhibitors, ribozymes, antisense therapies, cytokine-based therapies and T-cell-based therapeutic vaccines.

A pilot trial of recombinant interleukin-12 in patients with chronic hepatitis C who previously failed treatment with interferon-alpha

OBJECTIVE

Interleukin-12 is a cytokine with a multitude of immunomodulatory actions. Currently, interferon-alpha (IFN-alpha) monotherapy and combination treatment with IFN and ribavirin are the only therapies with proven efficacy against chronic hepatitis C infection. The purpose of this study was to assess the safety and antiviral activity of recombinant interleukin-12 (rhIL-12) in adults with chronic hepatitis C who did not achieve a sustained response to previous IFN-alpha therapy.

METHODS

This was a randomized, placebo-controlled, double-blind trial. We randomized 24 patients to one of three dose groups: 30 ng/kg, 100 ng/kg, and 300 ng/kg. Within each group, six patients received rhIL-12, and two patients received placebo administered s.c. twice a week for 12 wk.

RESULTS

Three of six patients treated with rhIL-12 at a dose of 300 ng/kg had loss of detectable hepatitis C RNA by reverse transcription-polymerase chain reaction compared with the placebo group (p = 0.05). All patients relapsed at the end of the 3-month treatment period. No other dose group demonstrated a loss of detectable hepatitis C RNA.

CONCLUSIONS

RhIL-12 at 300 ng/kg can suppress hepatitis C RNA to undetectable levels by reverse transcription-polymerase chain reaction, although relapse occurred when treatment was stopped. RhIL-12 was well tolerated with the most common side effects being flu-like symptoms and headaches.

Treatment of chronic viral hepatitis

Significant advances have been made in the treatment of both hepatitis B and C. Cure for the majority is becoming reality. Combination regimens are now established therapy in hepatitis C and the near future will see the adoption of a similar approach to hepatitis B. Interferon alpha therapy remains important, with the development of more efficacious pegylated forms. In this article we review current therapy and discuss future strategies of the therapy for chronic viral hepatitis.

Cytokine network in nonresponding chronic hepatitis C patients with genotype 1: role of triple therapy with interferon alpha, ribavirin, and ursodeoxycholate

OBJECTIVE

(i) to characterize the profile of tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), IL 10, Fas-ligand and transforming growth factor beta (TGF beta), chronic hepatitis C (HCV) patients with genotype 1; (ii) to determine the influence of triple therapy (TT) with interferon alpha (IFN alpha) + ribavirin + ursodeoxycholic acid on these cytokines and (iii) to establish the relationship between the pro-inflammatory cytokines and the outcome of treatment.

DESIGN AND METHODS

22 patients infected with HCV-genotype 1 a/b and non responsive to IFN-alpha monotherapy were enrolled in the TT. The controls were 49 HCV naïve patients with genotype 1 a/b. Cytokine levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The baseline TNF alpha values (pg/mL) in the sustained responders (SRs) (63+/-3) were significantly lower than non-responders (NRs) (140+/-16) (p < 0.001). Baseline Fas (ng/mL) levels were also lower in SRs (4.3+/-0.2) than NRs (5.4+/-0.4) (p < 0.05).

CONCLUSIONS

Fas and TNF alpha may be used as serological markers of inflammation and effectiveness of therapy.

Cytokines as predictors for sustained response and as markers for immunomodulation in patients with chronic hepatitis C

OBJECTIVES

(i) To characterize serum cytokine levels of tumor necrosis factor alpha (TNF alpha), interleukin 6 (IL 6), IL 8 and IL 12 in non-cirrhotic patients with chronic hepatitis C, (ii) to correlate the levels of these cytokines with the degree of the disease at the basal level, (iii) to correlate these levels with the response to therapy, (iv) to compare profiles of cytokines in monotherapy (MT) versus combination therapy (CT), and (v) to compare the immunomodulatory effects of MT versus CT.

DESIGN AND METHODS

47 patients were enrolled in the study. The controls were 120 volunteers (recruited from students and staff) that did not present HCV RNA positive and were not known to suffer any other metabolic disease. Thirty patients formed the other group of controls, with alcoholic liver disease (ALD). Serum cytokine levels were assessed using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The sustained responders (SRs) have basal values much lower than relapsed responders (RRs) and non-responders (NRs) regardless of the therapy.

CONCLUSIONS

Cytokines can be used as non-invasive markers for sustained response and as monitors for the outcome of therapy.

Current and future therapies of hepatitis C

With recent advances in the treatment of chronic hepatitis C, patients with elevated aminotransferase levels, detectable HCV RNA in the serum, and chronic inflammation are candidates for therapy. The best initial therapy is interferon plus ribavirin, achieving a sustained response rate in 40% of patients. The duration of therapy should be based on HCV genotype (48 weeks for genotype 1; 24 weeks for other genotypes). Serum HCV RNA should be measured at week 24 to assess response and guide further therapy in patients with genotype 1 infection. Patients unsuitable for combination therapy can be treated with interferon monotherapy. Side effects, dose modification and discontinuation are generally more frequent with interferon plus ribavirin, but can be managed with close follow-up and careful monitoring. With rapid developments in treatment, new therapies will require careful prospective evaluation according to HCV genotype and viral-load characteristics. Recommendations for therapy will probably change every few years, and novel approaches may provide effective therapy for most patients with hepatitis C.

Type 1/Type 2 immunity in infectious diseases

T helper type 1 (Th1) lymphocytes secrete secrete interleukin (IL)-2, interferon-gamma, and lymphotoxin-alpha and stimulate type 1 immunity, which is characterized by intense phagocytic activity. Conversely, Th2 cells secrete IL-4, IL-5, IL-9, IL-10, and IL-13 and stimulate type 2 immunity, which is characterized by high antibody titers. Type 1 and type 2 immunity are not strictly synonymous with cell-mediated and humoral immunity, because Th1 cells also stimulate moderate levels of antibody production, whereas Th2 cells actively suppress phagocytosis. For most infections, save those caused by large eukaryotic pathogens, type 1 immunity is protective, whereas type 2 responses assist with the resolution of cell-mediated inflammation. Severe systemic stress, immunosuppression, or overwhelming microbial inoculation causes the immune system to mount a type 2 response to an infection normally controlled by type 1 immunity. In such cases, administration of antimicrobial chemotherapy and exogenous cytokines restores systemic balance, which allows successful immune responses to clear the infection.

Human immune response to recombinant human proteins

Delivery of pharmacological doses of proteins to people has raised concerns of inducing immune responses, especially when the protein is provided in multiple doses over an extended period of time. Immune responses could impact the therapeutic exposure and efficacy of the protein itself. In addition, there have been fears of anaphylaxis or autoimmunity. This review summarizes the available literature regarding the measurement and evaluation of immune responses observed during clinical assessment of recombinant human proteins. Immune responses have ranged from none at all to inactivation and/or accelerated clearance. Presence of antibodies does not necessarily impact therapeutic viability. While responses are related to frequency and route of delivery, there is no clear relationship that enables one to predict the clinical experience.

The prevention and management of viral hepatitis

In this review we will discuss advances in the primary and secondary prevention of viral hepatitis and the treatment for chronic viral hepatitis.

Hepatitis C

In the latter half of the 20th century, HCV emerged as the most common cause of chronic liver disease, and will likely remain so. Since its initial discovery in 1989, rapid progress has been made in our understanding of the virology, epidemiology, natural history, diagnosis, and treatment of HCV. Over the next few decades, as further advancements are made, superior treatment options will become available.

Regulation of interleukin 12 and interleukin 10 expression in vaccinia virus-infected human monocytes and U-937 cell line

Regulation of IL-12 and IL-10 production in normal human monocytes infected with vaccinia virus (VV) was analysed. IL-12 and IL-10 mRNAs were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) and IL-12 and IL-10 protein by ELISA. RT-PCR analysis revealed a marked-up regulation of IL-12 (p40) and IL-10 expression in virally infected cells compared with that from control (non-infected) cells at 24 h post-infection (p.i.). IL-12 transcripts occurred earlier (at 4 h p.i.) than IL-10 mRNA. A significant increase in IL-12 and IL-10 secretion into the medium was caused by the virus, and even a much more pronounced increase in both interleukins expression (mRNAs and proteins) followed LPS or Staphylococcus aureus treatment. Vaccinia virus infection did not alter IL-10 secretion and IL-10 mRNA content (or even cause a decrease) in a human monocytic cell line U937. Undetectable levels of IL-12 protein were found in the cell line although the transcripts were present in the cells at first hours p.i. It appears now that vaccinia virus transiently and sequentially induces IL-12 and IL-10 in human monocytes.

Viral hepatitis

Viral hepatitis accounts for most liver diseases seen in hepatology practice. In the past year studies have been focused on uncovering the basic mechanisms of viral-cellular interactions, the knowledge of which will contribute to more effective treatment. Hepatitis A virus outbreaks still occur, even in the most developed countries, which points to the need for more comprehensive vaccination measures. Lessons learned from the treatment of HIV with combination antiviral therapies are being applied to both chronic hepatitis B and C. Progress has been made toward better understanding of viral kinetics and the quasi-species of hepatitis C virus with new and more sensitive diagnostic methods. Several therapeutic protocols are emerging to identify and tailor the management approach in various subsets of the population. Although posttransplantation hepatitis B has been more effectively managed with lamivudine therapy, no major advances have been accomplished in the treatment of recurrent hepatitis C among transplant recipients. Major advances in the field of viral hepatitis including A to E and TT viruses during the past year are highlighted.

A phase I/II study of recombinant human interleukin-12 in patients with chronic hepatitis B

BACKGROUND/AIMS

Interleukin-12 (IL-12) may be active against hepatitis B virus (HBV). The objective of the study was to assess the tolerability, activity, pharmacokinetics, and pharmacodynamics of three dose levels (0.03 microg/kg b.w., n=15; 0.25 microg/kg b.w., n=15; 0.50 microg/kg b.w., n=16) of recombinant human (rHu) IL-12 given s.c. once a week for 12 consecutive weeks.

METHODS

Forty-six patients with chronic hepatitis B, HBV DNA positivity and aminotransferase elevation were included in a multicenter prospective randomized phase I/II study.

RESULTS

Compared with the baseline, HBV DNA levels had decreased significantly at the end of rHuIL-12 treatment and after the 12-week follow-up period (p<0.001). The response to rHuIL-12 treatment was dose-dependent: at the end of the study HBV DNA clearance was greater in patients treated with 0.50 microg/kg b.w. (25%) or with 0.25 microg/kg b.w. (13%) compared with those given 0.03 microg/kg b.w. (7%). Moreover, HBeAg became undetectable at the end of follow-up in five of the patients given the 0.25microg/kg (2/15) or the 0.50 microg/kg (3/16) dose. The drug pharmacology showed that IL-12 had an estimated half-life of 30 h with levels remaining detectable for more than 48 h after rHuIL-12 administration. The serum levels of IL-12, interferon-gamma, IL-10, neopterin and beta2-microglobulin as well as the area under the curve (AUC) were rHuIL-12 dose-related. Side effects were observed more frequently with higher doses, including moderate decreases in lymphocyte and neutrophil counts; three patients withdrew prematurely from treatment. The local reaction observed at the injection site was unrelated to the drug dose. Only one patient showed detectable antibody levels to rHuIL-12 without clinical impact.

CONCLUSIONS

Treatment with rHuIL-12 at the doses investigated is safe and tolerable, and appears to be active against HBV in patients with chronic hepatitis B.

A pilot study of daily subcutaneous interleukin-10 in patients with chronic hepatitis C infection

The Th1/Th2 cytokine balance is important in persistence of infection and liver injury in chronic hepatitis C. The aim of this study was to administer the anti-inflammatory cytokine, recombinant human interleukin-10 (rHuIL-10), for 28 days in patients with chronic hepatitis C and to assess the safety and measure the effect on alanine aminotransferase (ALT, a marker of hepatic inflammation) levels and serum hepatitis C virus (HCV) RNA values. Three treatment-naive and 13 interferon (IFN) nonresponder patients (total 16 patients) with compensated chronic HCV infection were enrolled in this study. Patients were randomized to receive rHuIL-10 at a dose of 4 or 8 microg/kg/day as a single daily subcutaneous injection for 28 days. ALT values and serum HCV RNA were measured at days 0, 1, 3, 8, 15, 22, and 28 during therapy and at follow-up 2 and 4 weeks after cessation of the 4-week treatment period. ALT values normalized in 9 of 16 patients during therapy and remained normal until the end of treatment in 8 patients. The decreases in ALT values occurred in both the 4 microg and 8 microg dosage groups and were seen in both IFN naive and nonresponder patients. Mean ALT values fell significantly during the study period but usually returned to pretreatment levels by the end of the 4-week follow-up period (p < 0.05). HCV RNA concentrations did not vary significantly during or after therapy. (No patient had either an increase or a decrease in HCV RNA levels of > or =1.5 log during the study.) The drug was well tolerated, with no adverse symptoms noted. Platelet counts fell transiently to 73,000 and 63,000 in 2 patients. No other toxicity was observed, and no patients discontinued therapy. In chronic hepatitis C, short-term therapy with IL-10 was well tolerated and caused transient normalization of ALT values in 50% of patients, which returned to pretreatment levels on cessation of treatment. There were no significant changes observed in serum HCV RNA concentrations during the study. These immunomodulatory effects are similar to those observed with ribavirin monotherapy in chronic hepatitis C. Further study of rHuIL-10 alone or in combination with antiviral agents in chronic hepatitis C is warranted.