IL-12 is not required for induction of type 1 cytokine responses in viral infections

To investigate the physiological role of IL-12 in viral infections in terms of T cell cytokine responses involved in virus-specific Ig isotype induction and in antiviral protection, immune responses elicited upon infection of IL-12-deficient mice with lymphocytic choriomeningitis virus (LCMV) or vesicular stomatitis virus (VSV) were studied. Infection of IL-12-deficient mice with LCMV induced a virus-specific type 1 cytokine response as determined by in vitro cytokine secretion patterns as well as by in vivo intracellular cytokine staining of LCMV-specific CD4+ TCR transgenic T cells that had clonally expanded in LCMV-infected IL-12-deficient recipient mice. In addition, LCMV- and VSV-specific IgG responses exhibited normal serum IgG2a/IgG1 ratios, demonstrating again virus-specific CD4+ T cell induction of type 1 phenotype in IL-12-deficient mice upon viral infection. LCMV and VSV immune mice were found to be protected against challenge immunization with recombinant vaccinia viruses expressing either the LCMV- or the VSV-derived glycoprotein, respectively. This protection is known to be mediated by T cell-secreted type 1 cytokines IFN-gamma and TNF-alpha. In contrast, IL-12-deficient mice showed impaired abilities to control infection with the facultative intracellular bacterium Listeria monocytogenes at early time points after infection. However, at later time points of infection, IL-12-deficient mice were able to clear infection. These findings may indicate that viruses are able to induce type 1 T cell responses in the absence of IL-12 as opposed to some bacterial or parasitical infections that are crucially dependent on the presence of IL-12 for the induction of type 1 immune responses.     

Interleukin-12 inhibits hepatitis B virus replication in transgenic mice

Interleukin-12 (IL-12) is a heterodimeric cytokine produced by antigen-presenting cells that has the ability to induce gamma interferon (IFN-gamma) secretion by T and natural killer cells and to generate normal Th1 responses. These properties suggest that IL-12 may play an important role in the immune response to many viruses, including hepatitis B virus (HBV). Recently, we have shown that HBV-specific cytotoxic T lymphocytes inhibit HBV replication in the livers of transgenic mice by a noncytolytic process that is mediated in part by IFN-gamma. In the current study, we demonstrated that the same antiviral response can be initiated by recombinant murine IL-12 and we showed that the antiviral effect of IL-12 extends to extrahepatic sites such as the kidney. Southern blot analyses revealed the complete disappearance of HBV replicative intermediates from liver and kidney tissues at IL-12 doses that induce little or no inflammation in these tissues. In addition, immunohistochemical analysis demonstrated the disappearance of cytoplasmic hepatitis B core antigen from both tissues after IL-12 treatment, suggesting that IL-12 either prevents the assembly or triggers the degradation of the nucleocapsid particles within which HBV replication occurs. Importantly, we demonstrated that although IFN-gamma, tumor necrosis factor alpha, and IFN-alpha/beta mRNA are induced in the liver and kidney after IL-12 administration, the antiviral effect of IL-12 is mediated principally by its ability to induce IFN-gamma production in this model. These results suggest that IL-12, through its ability to induce IFN-gamma, probably plays an important role in the antiviral immune response to HBV during natural infection. Further, since relatively nontoxic doses of recombinant IL-12 profoundly inhibit HBV replication in the liver and extrahepatic sites in this model, IL-12 may have therapeutic value as an antiviral agent for the treatment of chronic HBV infection.     

The transformation of acute viral hepatitis B into chronic

500 patients with hepatitis B have been followed up from the acute onset to long-term outcome. As for chronic transformation of the disease, at higher risk are patients with mild form, progredient run and inadequate immune response. Of the highest value for identification and prognostication was a dynamic quantitative control over the system HBeAg-anti-HBe providing separate prognosis of establishment of replicative or integrative variants of chronic hepatitis B. In progredient infection an early administration of reaferon in combination with thymogen is thought valid which in many patients is sufficient to prevent the disease transformation into a chronic form.     

Treatment of chronic viral hepatitis

Recent advances have been made in the treatment of chronic viral hepatitis, mainly with recombinant interferon (IFN) alpha. However, the present treatment of chronic viral hepatitis is not entirely satisfactory because the efficacy is inconstant and/or incomplete. In chronic hepatitis B IFN-alpha induces a sustained interruption of hepatitis B virus (HBV) replication, with a HBeAg to anti-HBe seroconversion in about 30% of patients. Patients most likely to respond are those with no immunosuppression, HBV infection acquired during adulthood or active liver disease with low HBV replication. Responders usually show a significant decrease in serum HBV DNA levels during the first 2 months of therapy, followed by a significant increase in the level of aminotransferases. New nucleoside analogues might be useful in combination with IFN-alpha in the treatment of those who do not respond to IFN therapy. In chronic hepatitis B-D, the rate of sustained response to IFN-alpha therapy is low. To be effective, IFN-alpha must be used at a high dosage (9-10 mega units) with a long duration (1 year). In chronic hepatitis C, IFN-alpha at a dosage of 3 mega units over 6 months, induces a sustained response in about 20% of patients. A higher dosage of IFN (5-10 mega units) and a longer duration of treatment increases the rate of sustained response but is associated with poor tolerance. Non-responders to a first course of IFN do not respond to a second course of treatment. In patients who respond but relapse after treatment, the rate of sustained response after a second course of IFN needs to be assessed. Ribavirin, which has a significant antiviral effect on hepatitis C virus, might be useful in combination with IFN-alpha. At the dosage (3-6 mega units) usually used, IFN-alpha is relatively well tolerated. In about 10% of the patients therapy is interrupted, mainly because of severe fatigue, thyroid dysfunction or depression.     

Management of chronic viral hepatitis

Chronic viral hepatitis is a leading cause of death worldwide. Four of the six identifiable hepatitis viruses are associated with chronic disease. Until recently, the only accepted treatment has been injected interferon alfa. New antiviral medications currently hold promise in the treatment of hepatitis B. Hepatitis C remains more difficult to treat than hepatitis B, but involving the patient in selecting the treatment and identifying patients with better responses to interferon may help the physician direct the management of such patients more successfully.     

Treatment of chronic viral hepatitis

The initial appearance of tyrosine hydroxylase (TH)-, serotonin (5-HT)-, gamma-aminobutyric acid (GABA)-, calcitonin gene-related peptide- (CGRP), substance P-, and synaptophysin-immunoreactivity in the rat pituitary gland, and in the related brain regions was investigated. Several groups of TH-immunoreactive neurons were first detected in the brain stem on day E17, and in the hypothalamus on day E18, followed by TH-immunoreactivity in the median eminence and infundibulum on E19-E20. TH-positive fibers appeared in the posterior lobe on day E20 and in the intermediate lobe on day P0. 5-HT-immunoreactivity was first detected on day E17 in neurons and nerve fibers in the brain stem and in the median eminence, respectively. On day E18, a few 5-HT-immunoreactive fibers were detected in the posterior lobe of the pituitary, although they were consistently seen in the infundibulum from day E19. In newborn rats, some 5-HT-immunoreactive fibers, but no neurons, were seen in the hypothalamus. GABA immunoreactivity appeared on day E17 in several nerve fibers of the infundibulum and the posterior lobe. Some neurons in the cortex and ventral hypothalamus transiently expressed GABA-immunoreactivity on day E17. In newborn rats, a plexus of GABA-immunoreactive fibers was detected for the first time in the intermediate lobe. No CGRP-immunoreactive fibers could be detected in the prenatal pituitary. On day P10, CGRP-immunoreactive fibers were first observed in the anterior lobe. Later their number considerably increased, while only sporadic fibers could be found in the intermediate or posterior lobes. No substance P-immunoreactivity could be detected in any of the lobes in the embryonic or developing postnatal rat pituitary, instead the adult anterior lobe occasionally showed some substance P-immunoreactive fibers. Synaptophysin-immunoreactivity was first detected in the posterior lobe on day E20, followed shortly by its expression in the intermediate lobe in newborn rats. The time course of GABA and 5-HT expression revealed in the present study suggests that these transmitters, which are initially expressed in the developing pituitary clearly before synaptic maturation, may act as trophic molecules during the prenatal period.     

Current therapeutic trends in therapy for chronic viral hepatitis

Hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis delta virus (HDV) are associated with clinically significant chronic infection that may lead to the development of cirrhosis or even hepatocellular carcinoma (HCC). Intervention at the earliest possible stage is needed to prevent such untoward sequelae. Currently, interferon (IFN) is the only approved and widely used agent for the treatment of these infections, including in HBV patients with precore mutant hepatitis or decompensated cirrhosis, but its efficacy is far from satisfactory. Corticosteroid priming has been shown to increase the efficacy of IFN therapy in HBV patients with low abnormal serum transaminase levels, but only a few responders will clear serum hepatitis Bs antigen (HBsAg). Ongoing randomized controlled trials of thymosin alpha 1, lamivudine and famcyclovir have demonstrated encouraging preliminary results. Therapeutic vaccines, such as polypeptides with human leucocyte antigen (HLA)-specific hepatitis B core antigen (HBcAg) epitopes, are under phase II/III clinical trial. For HDV infection, the use of IFN in the early phase of acute superinfection tends to prevent chronic progression. For HCV infection, IFN used at higher doses for a longer period of time is associated with a higher sustained response, but overall it is still not satisfactory. The combined use of ribavirin or corticosteroid priming may improve the effect of IFN therapy by enhancing the durability of the response. Interferon in the acute phase of HCV infection may also prevent chronic progression. There is evidence to suggest that IFN therapy, when associated with response, tends to reduce the risk of cirrhosis or HCC and prolongs survival. There is no doubt that satisfactory treatment of chronic viral infection will require more effective agents and demand optimal treatment strategies, many of which are yet to be found.     

Cytokine production regulating Th1 and Th2 cytokines in hemophagocytic lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is caused by the hyperactivation of T cells and macrophages. The clinical characteristics associated with this disease result from overproduction of Th1 cytokines including interferon-gamma (IFN-gamma), interleukin-2 (IL-2), and tumor necrosis factor-alpha (TNF-alpha). In this study, we analyzed the production of IL-12 and IL-4, which determine Th1 and Th2 response, respectively, and IL-10, which antagonizes Th1 cytokines, in 11 patients with HLH. IL-12 was detected in plasma in all patients (mean peak value, 30.0 +/- 5.0 pg/mL), while IFN-gamma was massively produced in nine patients (mean peak value, 79.2 +/- 112.0 U/mL). IL-4 was not detected in any of the patients. Plasma IL-10 levels were elevated in all patients (mean peak value, 2,698.0 +/- 3,535.0 pg/mL). There was a positive correlation between the levels of IFN-gamma and IL-10 (P < .01). The plasma concentrations of these cytokines were initially high, before decreasing after the acute phase. However, the decrease in IL-10 levels was slower than that of IFN-gamma. Although the concentration of IL-12 was high at the acute phase, in some patients, a peak in the level was delayed until the chronic phase. Thus, in HLH, production of cytokines that promote development of Th1 cells appears to be predominant over that for Th2 cell development. Overproduction of IL-10 was also observed indicating that a mechanism suppressing hyperactivation of Th1 cells and monocytes/macrophages functions in patients with this disease.     

Ethiopathogenesis of hepatitis B viral infection in chimpanzees

Oral glucose tolerance tests were performed on 16 addicts and 16 control subjects. A flat delayed glucose response was demonstrated, with hyperinsulinaemia, elevated plasma growth hormone and normal plasma cortisol in heroin addicts compared with control subjects. These studies suggest a relative insulin resistance in addicts which might be mediated by the elevated growth hormone or some other pharmacologic effect of the chronic opiate abuse.     

The immunological diagnosis of chronic viral hepatitis

Chronic viral diseases of the liver are associated with changes in immune reactions mediated by T and B lymphocytes and dependent in severity on etiological factor (virus of hepatitis B, delta, C, their combination), the disease stage (hepatitis, cirrhosis), the process activity, kind of immune correction. HBsAg, viral hepatitis B marker, was detected in 21.2% of 1400 cases with chronic active hepatitis and liver cirrhosis. 32% of HbsAg-seropositive patients had antibodies to delta-antigen. Antibodies to HBsAg, HCV were found in 27.7 and 14.9% of the above patients. Chronic viral diseases of the liver with persistence of HBV, HDV and HCV markers are characterized by a complex of immune disorders, including a moderate rise in peripheral blood of IgM, IgG, IgA, IgE, Ig kappa, lambda, immune complexes, cryoglobulins, autoantibodies to subcellular structures as well as changes in regulatory (suppressor, helper) and effector (lymphokine-producing) functions of T lymphocytes, inhibition of phagocytosing capacity. The above shifts in immune status, clinical and biochemical activity of the disease are more pronounced in chronic active hepatitis with HCV markers compared to BHV. Of maximal intensity they were in combined viral infection HBV+HDV or HBV+HCV.     

Prognosis in acute viral hepatitis B in children

Epidemiological evaluations indicate an increase of acute viral hepatitis B in children. In this study authors performed an analysis of disease prognosis in retrospective trial in children hospitalized in the Pediatric Department of Infectious Diseases from 1983 to 1993 because of acute viral hepatitis B. It was documented that a risk of persistent hepatitis B may be related to the age of patients with acute viral hepatitis B in the past. In 64% of analyzed patients below 1 year old and in 20% over 6 years-persistent hepatitis was diagnosed, especially in male subjects.     

IFN-gamma is required for viral clearance from central nervous system oligodendroglia

Infection of the central nervous system (CNS) by the JHM strain of mouse hepatitis virus (JHMV) is a rodent model of the human demyelinating disease multiple sclerosis. The inability of effective host immune responses to eliminate virus from the CNS results in a chronic infection associated with ongoing recurrent demyelination. JHMV infects a variety of CNS cell types during the acute phase of infection including ependymal cells, astrocytes, microglia, oligodendroglia, and rarely in neurons. Replication within the majority of CNS cell types is controlled by perforin-dependent virus-specific CTL. However, inhibition of viral replication in oligodendroglia occurs via a perforin-independent mechanism(s). The potential role for IFN-gamma as mediator controlling JHMV replication in oligodendroglia was examined in mice deficient in IFN-gamma secretion (IFN-gamma0/0 mice). IFN-gamma0/0 mice exhibited increased clinical symptoms and mortality associated with persistent virus, demonstrating an inability to control replication. Neither antiviral Ab nor CTL responses were diminished in the absence of IFN-gamma, although increased IgG1 was detected in IFN-gamma0/0 mice. Increased virus Ag in the absence of IFN-gamma localized almost exclusively to oligodendroglia and was associated with increased CD8+ T cells localized within white matter. These data suggest that although perforin-dependent CTL control virus replication within astrocytes and microglia, which constitute the majority of infected CNS cells, IFN-gamma is critical for control of viral replication in oligodendroglia. Therefore, different mechanisms are used by the host defenses to control virus replication within the CNS, dependent upon the phenotype of the targets of virus replication.     

Serum hepatitis G virus RNA in patients with chronic viral hepatitis

OBJECTIVES: The hepatitis G virus (HGV) is a newly described flavivirus that affects a high proportion of patients with chronic viral hepatitis: our objective was to determine what role HGV might play in the course of disease. METHODS: We evaluated stored serum samples from 108 patients with chronic hepatitis B and 99 patients with chronic hepatitis C who participated in trials of alpha-interferon or ribavirin for the presence of hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA by branched DNA and for the presence of HGV RNA by polymerase chain reaction (PCR), using primers from the NS5 region of the genome. RESULTS: Initially, 20 (19%) patients with hepatitis B and 11 (11%) with hepatitis C had HGV RNA in their serum. Patients with and without HGV infection were similar with regard to clinical features, laboratory tests, and hepatic histology. HGV RNA levels fell during interferon therapy and became undetectable in those receiving the highest doses; however, HGV RNA levels returned to pretreatment values when therapy was stopped. With ribavirin therapy, HGV RNA levels did not change. Two- to 12-yr follow-up serum samples were available from 17 initially HGV RNA-positive patients, of whom only 10 (59%) were still positive. CONCLUSIONS: HGV infection is common among patients with chronic hepatitis B and C but has little effect on the short-term course of disease or response to therapy. HGV RNA levels are suppressed but not eradicated by alpha-interferon and are unaffected by ribavirin treatment. Spontaneous loss of HGV RNA occurs over time in a proportion of patients.