Sialadenitis histologically resembling Sjogren syndrome in mice transgenic for hepatitis C virus envelope genes

[Evolution of Sjögren syndrome associated with hepatitis C virus when chronic hepatitis C is treated by interferon or the association of interferon and ribavirin]

Hepatitis C virus is one of the most likely candidates as a potential pathogenic agent causing Sjogren's syndrome (SS) in a subset of patients. Nobody has until now described the evolution of SS associated with HCV when chronic hepatitis C is treated with antiviral therapy, interferon being an auto-immunity inductor. This is the purpose of our study.

METHODS

Prospective study of 12 patients with a HCV-associated SS defined as certain according to the first european criteria and treated with interferon or interferon/ribavirin for their chronic hepatitis C.

RESULTS

More than fifty percent of these patients developed a severe immunological complication especially when they were treated with interferon alone. Ribavirin may have had a protective role on interferon-mediated immunological complications. These complications went on after cessation of therapy. Sicca syndrome was improved only in the patients treated with the association (in 50% of the cases), but these patients also had a sustained virological response. It is difficult to tell if this improvement was due to the hepatitis C virus eradication or ribavirin treatment.

CONCLUSION

Hepatitis C virus is implicated in the development of SS in a specific subset of patients for which we can propose the term SS "secondary to HCV" and this disease is not utterly benign especially after the introduction of interferon therapy. Ribavirin when associated with interferon gives a significative sustained virological response and could lower the incidence of immunological interferon-mediated complications with a favorable outcome of sicca syndrome.

Cell culture models and animal models of viral hepatitis. Part II: hepatitis C

The lack of a preventive vaccine, coupled with common unresponsiveness to treatment and coinfection with HIV, has made HCV a major threat to public health. The authors review in vitro and in vivo models that are being used to study HCV and to develop new treatments and preventive measures.

Sjögren syndrome associated with hepatitis C virus: a multicenter analysis of 137 cases

To define the clinical and immunologic pattern of expression of Sjögren syndrome (SS) associated with chronic hepatitis C virus (HCV) infection, we conducted a multicenter study aiming to collect a large number of patients with SS and HCV infection. Inclusion criteria were the fulfillment of at least 4 of the classification criteria for SS proposed by the European Community Study Group and repeated positive HCV serology, confirmed by recombinant immunoblot assay and/or detection of serum HCV-RNA by polymerase chain reaction. One hundred thirty-seven patients were included (104 female and 33 male; mean age, 65 yr). Seventy-nine (58%) patients presented a systemic process with diverse extraglandular manifestations, with articular involvement (44%), vasculitis (20%), and neuropathy (16%) being the most frequent features observed. The main immunologic features were antinuclear antibodies (65%), hypocomplementemia (51%), and cryoglobulinemia (50%). Cryoglobulins were associated with a higher frequency of cutaneous vasculitis, rheumatoid factor, and hypocomplementemia. Thirty-two (23%) patients had positive anti-Ro/SS-A and/or anti-La/SS-B antibodies; these patients were predominantly women and had a higher prevalence of some extraglandular features and a lower frequency of liver involvement. Nineteen (14%) patients developed neoplasia, with hematologic neoplasia (8 cases) and hepatocellular carcinoma (6 cases) being the most frequent types. Eighty-five percent of SS-HCV patients also fulfilled the recently proposed 2002 classification criteria for SS. In conclusion, HCV-associated SS is indistinguishable in most cases from the primary form using the most recent set of classification criteria. Chronic HCV infection should be considered an exclusion criterion for the classification of primary SS, not because it mimics primary SS, but because the virus may be implicated in the development of SS in a specific subset of patients. We propose the term "SS secondary to HCV" when these patients fulfill the 2002 classification criteria for SS.

A dual role for interferon-gamma in the pathogenesis of Sjogren's syndrome-like autoimmune exocrinopathy in the nonobese diabetic mouse

Sjogren's syndrome-like autoimmune exocrinopathy (AEC) in the nonobese diabetic (NOD) mouse progresses from a preimmune phase to an immune phase, resulting in dry mouth and/or dry eyes. In the present study, the impact of the prototypical T-helper type 1 cytokine, interferon-gamma (IFN-gamma), on the onset of AEC was investigated using both the IFN-gamma and the IFN-gamma receptor gene knockout mice, NOD.IFN-gamma(-/-) and NOD.IFN-gammaR(-/-), respectively. Neither the NOD.IFN-gamma(-/-) nor the NOD.IFN-gammaR(-/-) mice exhibited increased acinar cell apoptosis and abnormal salivary protein expression, typically observed in parental NOD mice prior to disease. Without these preimmune phase abnormalities, NOD.IFN-gamma(-/-) and NOD.IFN-gammaR(-/-) mice showed no subsequent autoimmune responses against the salivary glands at 20 weeks. Interestingly, real-time polymerase chain reaction and electrophoretic gel mobility shift assays suggested that IFN-gamma and STAT1, as well as the transcriptional activity of STAT1 in NOD glands, were increased at birth. Unlike the neonatal submandibular glands of NOD or NOD-scid mice that show abnormal glandular morphogenesis at birth, the submandibular glands of the newly constructed congenic strain, NOD-scid.IFN-gamma(-/-), were found to be normal. Taken together, IFN-gamma appears to play a critical role not only during the later immune phase of AEC, but also the early preimmune phase, independent of effector functions of immune cells. How exactly IFN-gamma functions during this period remains speculative.

Hepatitis C virus, Sjögren's syndrome and B-cell lymphoma: linking infection, autoimmunity and cancer

An increased prevalence of hematologic malignancies is often described in patients with Sjögren's syndrome (SS). Viruses have been proposed as possible etiologic or triggering agents of systemic autoimmune diseases (SADs), with hepatitis C virus (HCV) being one of the viruses most frequently associated with autoimmune features and with systemic autoimmune diseases such as mixed cryoglobulinemia or SS. Moreover, the association between HCV infection and hematologic malignancies, mainly non-Hodgkin's lymphoma (NHL), is supported by several studies. For these reasons, the recognized association of specific systemic autoimmune diseases (mainly SS and mixed cryoglobulinemia) with HCV infection, added to the possible evolution of any one of these entities into a B-cell NHL, suggests the possibility of a close relationship among SS, HCV and B-cell lymphoproliferative disorders, especially in patients with type II mixed cryoglobulinemia.

Hepatitis C virus-associated extrahepatic manifestations: a review

The hepatitis C virus (HCV) infection is a worldwide disease that is characterized by a preferential chronic evolution with mild to severe liver disease, including cirrhosis and, in lesser proportion, hepatocarcinoma. Out of these complications, HCV is frequently reported to complicate extrahepatic manifestations. Among those associated to HCV infection with a high degree of certainty, mixed cryoglobulinemia and its complications (skin, neurological, renal, rheumatological involvement) are the most prevalent (50%) in HCV-infected patients. The other diseases include noncryoglobulinemic systemic vasculitis, splenic lymphoma with villous lymphocytes, fatigue, porphyria cutanea tarda, sicca syndrome, and autoantibodies production. The extrahepatic manifestations that share mild-degree certainty of association with HCV infection include B-cell non-Hodgkin lymphoma, autoimmune thrombocytopenia, pruritus, and type II diabetes mellitus. The other diseases such as autoimmune thyroiditis, lichen planus are more questionable for their eventual association with HCV and others (pulmonary fibrosis with or without polymyositis, progressive encephalomyelitis, Mooren's corneal ulcers, erythema nodosum, chronic polyradiculonevritis) are mostly case reports. Howerver, even in cases of tight association, the mechanisms through which HCV may promote or induce extrahepatic manifestations remain unclear and merit further investigations.

Pathogenesis of hepatitis C-associated hepatocellular carcinoma

Epidemiologic, clinical, and virologic data have shown a close association between chronic infection with hepatitis C virus (HCV) and the development of hepatocellular carcinoma (HCC). In many countries of the developed world, HCV infection accounts for more than half of the cases of HCC. HCC usually arises after 2-4 decades of infection, typically in the context of an underlying cirrhosis. Treatment of hepatitis C with interferon-alfa can lead to sustained clearance of HCV, and small prospective studies as well as larger retrospective analyses suggest that interferon therapy leads to a decrease in the incidence of HCC. Without a reliable tissue culture system or a small animal model of HCV infection, analysis of the mechanisms by which HCV leads to cancer has been difficult. Nevertheless, both in vitro expression systems and in vivo transgenic mice studies suggest that HCV has an inherent carcinogenic potential. Understanding the pathogenesis of HCV-associated HCC is important in developing effective means of prevention and treatment of this highly malignant form of cancer.

HCV infection and oral lichen planus: a weak association when HCV is endemic

Oral lichen planus (OLP), an immune-mediated disorder, has been reported as an extra-hepatic manifestation of Hepatitis C virus (HCV) infection, especially in HCV hyperendemic areas such as southern Europe and Japan. The aim of this study was to investigate from an epidemiological standpoint whether HCV infection is an important factor affecting the relative risk of OLP in a Mediterranean population or whether this relates to the degree of HCV endemicity. Two cohorts of OLP patients resident in two different regions of southern Italy (Campania and Sicily; n = 859) were evaluated for HCV infection status and categorized into five age classes to respective region-matched controls. No significant difference was found between OLP patients and the general population in this area, when data were corrected by the age-stratified prevalence of HCV. Therefore, the age-specific prevalence of HCV infection in OLP patients shows a close trend of direct association with increasing age, without significant differences with the general population of each geographical area. An aetiological link between OLP and HCV cannot be inferred solely by epidemiological data.

New Insights into the Diagnosis and Treatment of Dry Eye

Over the past decade, numerous advances have been made in relation to dry eye diagnostic markers, technologies, and treatment options. The mainstay of treatment of dry eye is the use of artificial tear solutions and punctum plugs. A goal is the development of agents that provide symptomatic treatment and, at the same time, improve ocular surface keratinization. It is the authors' opinion that the functional visual acuity tester and the new tear stability analysis system will be widely used to improve diagnosis and evaluate treatment outcomes in KCS. Advances in treatment will utilize anti-inflammatory agents, immune suppressants such as Cyclosporin A and FK-506, growth hormones, androgens, topical mucins and ocular surface stimulating drugs, like INS365. Although aqueous-deficient dry eye is most commonly not associated with Sjogren syndrome (SS), aqueous-deficient dry eye is often most severe in patients with SS; thus, this article focuses mainly on SS-associated dry eye.

Hepatitis C virus infection and diabetes: direct involvement of the virus in the development of insulin resistance

BACKGROUND & AIMS

Epidemiological studies have suggested a linkage between type 2 diabetes and chronic hepatitis C virus (HCV) infection. However, the presence of additional factors such as obesity, aging, or cirrhosis prevents the establishment of a definite relationship between these 2 conditions.

METHODS

A mouse model transgenic for the HCV core gene was used.

RESULTS

In the glucose tolerance test, plasma glucose levels were higher at all time points including in the fasting state in the core gene transgenic mice than in control mice, although the difference was not statistically significant. In contrast, the transgenic mice exhibited a marked insulin resistance as revealed by the insulin tolerance test, as well as significantly higher basal serum insulin levels. Feeding with a high-fat diet led to the development of overt diabetes in the transgenic mice but not in control mice. A high level of tumor necrosis factor-alpha, which has been also observed in human chronic hepatitis C patients, was considered to be one of the bases of insulin resistance in the transgenic mice, which acts by disturbing tyrosine phosphorylation of insulin receptor substrate-1. Moreover, administration of an anti-tumor necrosis factor-alpha antibody restored insulin sensitivity.

CONCLUSIONS

The ability of insulin to lower the plasma glucose level in the HCV transgenic mice was impaired, as observed in chronic hepatitis C patients. These results provide a direct experimental evidence for the contribution of HCV in the development of insulin resistance in human HCV infection, which finally leads to the development of type 2 diabetes.

Oral diseases possibly associated with hepatitis C virus

Morbidity associated with hepatitis C virus (HCV) infection can involve a variety of extrahepatic conditions, including lichen planus (LP) and sialadenitis, predominantly or exclusively involving the oral region, conditions which have been largely neglected in reviews. The literature suggests that HCV-infected patients may frequently have Sjögren-like sialadenitis with mild clinical symptoms, whereas oral LP may be significantly associated with HCV infections in Southern Europe and Japan but not in Northern Europe. These geographical differences could be related to immunogenetic factors such as the HLA-DR6 allele, significantly expressed in Italian patients with OLP and HCV. Analysis of experimental data suggests that HCV could be involved in the pathogenesis of both these diseases. Moreover, parotid lymphoma may arise in patients with sialadenitis, mainly with type II cryoglobulinemia. Little attention has been paid to oral health needs in HCV-infected patients and the variable effect of interferon-alpha therapy on oral tissues. Further research is needed, because of the potentially great influence of oral diseases possibly linked to HCV on the quality of life of millions of patients.

Incidence of Sjögren's syndrome in Japanese patients with hepatitis C virus infection

BACKGROUND AND AIM

Hepatitis viruses induce not only chronic liver diseases but also the impairment of other organs and tissues as extrahepatic manifestations. In particular, hepatitis C virus (HCV) is involved in various extrahepatic manifestations. The purpose of the present study was to evaluate Sjögren's syndrome (SS) and lichen planus (LP) involvement, which are various extrahepatic manifestations in patients with liver diseases related to hepatitis B virus (HBV) or HCV.

METHODS

We examined a total of 110 Japanese patients with chronic liver disease: 29 with HBV infections and 81 HCV infections.

RESULTS

The prevalence of SS according to European and Japanese criteria in patients with chronic HCV infection was significantly higher than in patients with chronic HBV infection (European criteria: 25.9 vs 3.4%; P < 0.05, Japanese criteria: 21.0 vs 3.4%; P = 0.05). Lichen planus was observed in one (3.4%) of 29 patients with chronic HBV infection, and in 11 (13.6%) of 81 patients with chronic HCV infection. Simultaneously combined LP and SS occurred in 8.6% (seven of 81) of patients with HCV infection, but in none with HBV infection.

CONCLUSIONS

Clinicians should routinely follow the HCV-infected patients, paying sufficient attention to the presence of SS and LP, and they should also carefully monitor their prognosis.

Extrahepatic manifestations of hepatitis C infection

Hepatitis C virus (HCV) affects 1.8% of the American population, and approximately 38% of patients with HCV will manifest symptoms of at least 1 extrahepatic manifestation during the illness. Renal disease, neuropathy, lymphoma, and Sjögren syndrome with or without mixed cryoglobulinemia are all strongly associated with HCV infection. Porphyria cutanea tarda and diabetes have also been linked to HCV. Most extrahepatic manifestations of chronic HCV infection are immunological, and the chronic infection seems to be necessary for their development. The molecular study of the unique way in which the HCV virus interacts with the human immune system is beginning to provide plausible explanations of the pathogenic role of HCV in some of these syndromes, but many pathogenetic links remain completely obscure.

Alteration of intrahepatic cytokine expression and AP-1 activation in transgenic mice expressing hepatitis C virus core protein

Hepatitis C virus (HCV) infection often leads to the development of hepatocellular carcinoma (HCC), but its molecular mechanism has not been clearly elucidated. Previously, transgenic mice constitutively expressing HCV core protein have been shown to develop HCC, suggesting a pivotal role of the core protein in hepatocarcinogenesis. Here, we analyzed the expression of cytokines associated with a variety of cellular processes, including cell proliferation, in the mouse model for HCV-associated HCC to define the molecular events prior to oncogenesis. The expression of tumor necrosis factor-alpha and interleukin-1beta was increased at both protein and mRNA levels. In addition, the activities of c-Jun N-terminal kinase and activator protein-1 (AP-1), downstream effectors, were enhanced, while IkappaB kinase or nuclear factor-kappaB activities were not enhanced. Thus, the altered in vivo expression of cytokines with AP-1 activation in consequence to the core protein expression may contribute to hepatocarcinogenesis in persistent HCV infection.

Ocular manifestations of hepatitis C virus infection

Approximately 3.6 million persons in the United States are infected with the hepatitis C virus (HCV), a condition with both hepatic and extrahepatic sequelae. Although no pathognomonic manifestation of HCV infection in the eye has been demonstrated, associations between HCV infection and various ocular syndromes have been reported in small case series and individual patients. At this time, the ocular manifestations of HCV infections best supported by the literature include a dry eye syndrome similar to Sjögren syndrome, and ischemic retinopathy caused by either an HCV-induced vasculitis or treatment with interferon. Patients with diabetes seem to be more susceptible to interferon retinopathy and to subsequent permanent visual loss. There have been no cases of HCV transmission via corneal transplantation, suggesting that current cadaveric screening protocols are effective in preventing this route of transmission. Screening for HCV should be considered in patients with risk factors for HCV infection who suffer from unexplained ischemic retinopathy or dry eyes.

Prevalence of seropositivity for hepatitis C virus in cataract patients and the general population

PURPOSE

To investigate the epidemiologic relationship between hepatitis C virus (HCV) infection and cataract.

SETTING

Yoshida Eye Clinic, Fukuoka, Japan.

METHODS

This study included 492 patients with age-related cataract and 2624 controls who had a municipal mass health screening. All subjects were 60 years or older and inhabitants of Chikugo City (population 45000), Fukuoka, Japan. Each subject was serologically tested for HCV using the third-generation enzyme immunoassay. Seropositivity was compared in subgroups consisting of patients by decade; that is 60 to 69 years of age, 70 to 79 years of age, and 80 to 90 years of age.

RESULTS

The prevalence of HCV in the cataract group and health-screening (control) group was 18.3% and 7.1%, respectively, in the 60- to -69 year subgroup; 17.8% and 6.6%, respectively, in the 70- to 79-year subgroup; and 15.1% and 3.7%, respectively, in the 80- to 90-year subgroup. In each subgroup, the prevalence of HCV was significantly higher in the cataract group than in the control group (P <.01, chi-square test). In the cataract group, the HCV seropositive and seronegative groups did not differ significantly in the prevalence of hepatitis B virus (P =.548, Fisher exact probability test).

CONCLUSIONS

Patients with age-related cataract had significantly higher seropositivity for HCV than an age-matched general population. This suggests that HCV infection may play a role in the development and/or progression of cataract.

The liver is a common non-exocrine target in primary Sjögren's syndrome: a retrospective review

BACKGROUND

The autoimmune destruction of exocrine glands that defines primary Sjögren's syndrome (1 degrees SS) often extends to non-exocrine organs including the liver. We aimed to determine the prevalence of liver disease in patients with 1 degrees SS and to evaluate the association of this complication with other non-exocrine features and serologic markers of autoimmunity and systemic inflammation.

METHODS

We reviewed 115 charts of patients with 1 degrees SS and further analyzed the 73 cases that fulfilled the European Epidemiology Center Criteria, seeking evidence for clinical and subclinical liver disease.

RESULTS

Liver function tests had been determined in 59 of the 73 patients. Of those, 29 patients (49.1%) had abnormal liver function tests including 20.3% with clinically overt hepatic disease. Liver disease was the most common non-exocrine feature in this cohort. Risk factors for abnormal liver function tests were distributed similarly between the patients with and without liver disease. In 60% of patients with abnormal liver function tests no explanation for this complication was found except for 1 degrees SS. Liver involvement was significantly more common in 1 degrees SS patients who also had evidence of lung, kidney and hematological abnormalities. Patients with abnormal liver function tests were also more likely to have an elevated sedimentation rate and a positive anti-ENA during the course of their disease.

CONCLUSION

Liver involvement is a common complication in 1 degrees SS. Its presence correlates with systemic disease. We consider that this complication should be routinely sought in patients with 1 degrees SS, especially when a positive anti-ENA or evidence of systemic inflammation is found.

Viral etiopathogenesis of Sjögren's syndrome: role of the hepatitis C virus

Patients with hepatitis C virus (HCV) chronic infection present some extrahepatic manifestations that may mimic the clinical, immunologic and histological manifestations of primary Sjögren's syndrome (SS). Thus, HCV patients with sicca symptomatology and positive autoantibodies could be misdiagnosed as a 'primary' SS. Nevertheless, there are several clinical and immunologic features that could help us differentiate both processes.

Role of hepatitis C virus in the development of hepatocellular carcinoma: transgenic approach to viral hepatocarcinogenesis

Overwhelming lines of epidemiologic evidence have indicated that chronic infection with hepatitis C virus (HCV) poses a major risk towards the development of hepatocellular carcinoma (HCC). It remains controversial whether HCV plays a direct role in the pathogenesis of HCV-associated HCC or whether it merely serves an indirect role. Using the transgenic mouse model established by us, it has become evident that the core protein of HCV confers oncogenic potential. The findings in our studies indicate that HCV is directly involved in hepatocarcinogenesis, albeit other factors, such as continued cell death and regeneration associated with chronic hepatitis, may also play a role. Taken together, our results indicate that there could be a mechanism for the development of HCC in persistent hepatitis virus infection that is distinct from the pathogenesis of other cancers, like colorectal cancer. Thus, although accumulation of a set of genetic aberrations may also be necessary for a multistage development of HCC, HCV core protein, to which an oncogenic potential is ascribed, may allow some stages to be skipped in hepatocarcinogenesis. The possibility that infection with HCV may be capable of inducing HCC in the absence of a complete set of genetic aberrations would help explain the unusually high incidence and multicentric nature of HCC developing in chronic hepatitis C.

Whole stimulated salivary flow in patients with chronic hepatitis C virus infection

BACKGROUND

Salivary gland disorders have been included among the extra-hepatic manifestations related to HCV infection.

METHODS

The whole stimulated salivary flow rate (spitting technique) was studied in 74 HCV infected patients to evaluate salivary gland dysfunction.

RESULTS

The salivary flow of the patients with chronic HCV infection was similar to that of the healthy controls. The association between subjective xerostomia salivary flow was seen to be very weak. No significant associations were found between salivary flow and age, sex, risk factor of acquired infection, ALT, AST, GGT, ALP values, time lapsed since the diagnosis or HCV-RNA detection in saliva.

CONCLUSIONS

Although the functional repercussion of hepatitis C related lymphocytic sialoadenitis remains unclear, we did not find a significant reduction in the whole stimulated salivary flow in HCV infected patients.

Genetic aspects of Sjögren's syndrome

Sjögren's syndrome is a multisystem inflammatory rheumatic disease that is classified into primary and secondary forms, with cardinal features in the eye (keratoconjunctivitis sicca) and mouth (xerostomia). The aetiology behind this autoimmune exocrinopathy is probably multifactorial and influenced by genetic as well as by environmental factors that are as yet unknown. A genetic predisposition to Sjögren's syndrome has been suggested on the basis of familial aggregation, animal models and candidate gene association studies. Recent advances in molecular and genetic methodologies should further our understanding of this complex disease. The present review synthesizes the current state of genetics in Sjögren's syndrome.

Hepatocarcinogenesis in hepatitis viral infection: lessons from transgenic mouse studies

Over the past decade, genetically engineered mouse models have been used for studies of the mechanisms underlying human diseases. One advantage of these models is that the targeted protein executes its function in normal cells in their natural tissue microenvironments. Transgenic mouse models for human viral hepatitis have also been established and have provided new insights into the pathogenesis of hepatitis and hepatocellular carcinoma (HCC). In the search for the mechanism of hepatocarcinogenesis in hepatitis viral infection, two viral proteins, the core protein of hepatitis C virus (HCV) and the HBx protein of hepatitis B virus (HBV), have been shown to possess oncogenic potential through transgenic mouse studies, indicating the direct involvement of the hepatitis viruses in hepatocarcinogenesis. The presence of the hepatitis C virus core or HBx protein, which has an oncogenic potential, may allow some of the steps in multistep hepatocarcinogenesis to be skipped. This may explain the very high frequency of HCC in patients with HCV or HBV infection.

New animal models of hepatitis B and C

The narrow host range of infection and lack of suitable tissue culture systems for the propagation of hepatitis B and C viruses are limitations that have prevented a more thorough understanding of persistent infection and the pathogenesis of chronic liver disease. With hepatitis B virus (HBV), this lack of knowledge has been partially overcome by the discovery and characterization of HBV-like viruses in wild animals. With hepatitis C virus (HCV), related flaviviruses have been used as surrogate systems for such studies. Other laboratories have developed transgenic mice that express virus gene products and/or support virus replication. Some HBV transgenic mouse models develop fulminant hepatitis, acute hepatitis, or chronic liver disease after adoptive transfer, and others spontaneously develop hepatocellular carcinoma (HCC), as in human infections. Among HCV transgenic mice, most develop no disease, but acute hepatitis has been observed in one model, and HCC in another. Although mice are not susceptible to HBV and HCV, their ability to replicate these viruses and to develop liver diseases characteristic of human infections provides new opportunities to study pathogenesis and develop novel therapeutics.

Molecular clones of hepatitis C virus: applications to animal models

Hepatitis C virus (HCV) is a global public health problem, with approximately 3% of the world population now infected. The clinical course of HCV often involves chronic infection, which can lead to liver dysfunction and hepatocellular carcinoma. Because HCV cannot be efficiently propagated in cell culture, researchers have relied heavily on animal models to study the physical characteristics of HCV and the course of events associated with HCV infection. The chimpanzee is the only nonhuman primate actually proven to be susceptible to HCV infection and has commonly been used to study viral hepatitis induced by HCV. Molecular cloning of the HCV genome has now allowed HCV transmission studies in chimpanzees to progress from the early work of characterizing infectious serum to a current focus of characterizing infectious HCV molecular clones. Moreover, the cloned HCV genome has paved the way for the development of alternative animal models for HCV, most notably transgenic mouse models for the study of HCV pathogenesis. The authors review these animal model applications of the HCV molecular clones, including construction and transmission of mutant viral genomes. The expression of specific viral protein products in these animal models will provide important insight into the structure-function relation that specific HCV genome sequences impart on virus replication and pathogenesis.

Preliminary classification of nonmalignant B cell proliferation in Sjögren's syndrome: perspectives on pathobiology and treatment based on an integrated clinico-pathologic and molecular study approach

A classification of nonmalignant lymphoproliferation in Sjögren's syndrome is presented, based on the results of international meetings regarding Sjögren's syndrome-associated lymphomagenesis and on our results of a clinico-pathologic and molecular study and long-term follow-up in well-characterized patients. Sjögren's syndrome pathobiology has similarities to hepatitis C virus-related B-cell lymphoproliferation. Antigen stimulation with the preferential expansion of rheumatoid factor-positive clones and specific immunoglobulin gene expression and recombination represent key biologic events in lymphoproliferation. This classification is based on the coupling of molecular and histological studies and may result in more selective treatment approaches.

Treatment of chronic sialadenitis in a murine model of Sjögren's syndrome by local fasL gene transfer

OBJECTIVE

Infection of Fas (Fas/CD95)-mutant C57BL/6 (B6)-lpr/lpr mice with murine cytomegalovirus (MCMV) leads to a chronic sialadenitis similar to that of Sjögren's syndrome (SS). The aim of this study was to evaluate whether chronic sialadenitis would also occur in Fas ligand (FasL/CD95L)-mutant B6-gld/gld mice upon infection with MCMV and whether the expression of FasL by local gene transfer using recombinant adenoviral vectors would be an effective therapeutic strategy.

METHODS

B6-gld/gld mice were infected intraperitoneally with MCMV, and salivary glands were analyzed histologically at different time points. For treatment of sialadenitis, recombinant adenoviral vectors expressing the fasL gene (AdLoxpFasL + AxCANCre) or the lacZ gene (AdCMVLacZ) were locally injected into the salivary glands of MCMV-infected B6-gld/gld mice and uninfected B6-+/+ and B6-gld/gld mice.

RESULTS

Following MCMV infection, B6-gld/gld mice developed an acute and chronic sialadenitis characterized by multiple foci of infiltrating T cells. After local injection of adenoviral vectors, high levels of lacZ or fasL gene expression could be detected in acinar and ductal cells. Treatment of acute and chronic sialadenitis in B6-gld/gld mice with local fasL gene transfer resulted in a significant reduction in the number of inflammatory foci and tissue destruction in salivary glands compared with mice treated with AdCMVLacZ. Despite high levels of FasL expression after injection of recombinant vectors, <5% of ductal and acinar cells were TUNEL positive, demonstrating that, in this model of SS, acinar and ductal cells were not highly sensitive to FasL-mediated apoptosis.

CONCLUSION

Chronic sialadenitis similar to that of SS developed in B6-gld/gld mice after MCMV infection. FasL expression was reconstituted by local gene transfer, resulting in significant reduction of infiltrating mononuclear cells, which indicates that local gene transfer of fasL might be a novel treatment for chronic sialadenitis.

Possible role of cytotoxic T cells in acute liver injury in hepatitis C virus cDNA transgenic mice mediated by Cre/loxP system

A line of hepatitis C virus (HCV) transgenic mice was established previously that was mediated by Cre/loxP system using HCV cDNA, including core, E1, E2 and NS2 genes. Intravenous infection of a recombinant adenovirus that expresses Cre DNA recombinase (AxCANCre) induced HCV structural protein expression in the liver of transgenic mice. HCV core protein production and transgene recombination in the mouse liver were serially evaluated after AxCANCre infusion. Core proteins were expressed efficiently and transgene was almost completely recombined in the liver of mice after 3 days and then the levels of both core protein production and transgene recombination decreased continuously for 28 days. However, 30.6% of the transgene recombination remained at 28 days and only 2.7% of core production remained at 28 days after infection. Compared with nontransgenic controls, the serum alanine aminotransferase levels in transgenic mice were significantly higher 10, 14, and 21 days after adenovirus infection. Histological scoring also indicated severe pathological changes in the liver of transgenic mice after adenovirus infection. AxCANCre infusion increased CD8+ lymphocyte infiltration into the liver of transgenic mice compared with that of non-transgenic controls. Furthermore, cytotoxic T lymphocytes (CTLs) isolated from transgenic mice during liver injury were specific for the HCV proteins. These results suggest that HCV structural proteins expressed in the liver of transgenic mice enhanced liver injury. HCV-specific CTLs may be to enhance hepatitis. Thus, the present HCV transgenic mouse model provides a useful model of liver injury due to HCV, and the host immune response may play a pivotal role(s) in the pathogenesis of HCV.

Hepatitis C virus infection mimicking primary Sjögren syndrome. A clinical and immunologic description of 35 cases

Hepatitis C virus (HCV) infection is emerging as an extremely common and insidiously progressive liver disease that is often associated with several extrahepatic manifestations. In 1992, a possible relationship between Sjögren syndrome (SS) and patients with HCV infection was first postulated. Subsequently, several studies demonstrated that a "true" SS, with similar clinical and histologic features to those observed in primary SS, may occur in some patients with chronic HCV infection. We report the clinical and immunologic characteristics of 35 patients with chronic HCV infection and a well-documented diagnosis of SS. Compared with 60 patients with primary SS who tested negative for HCV antibodies, SS-HCV patients showed a higher mean age (65.9 yr versus 61.5 yr, p = 0.04), a lower prevalence of parotidomegaly (17% versus 47%, p = 0.004), and a higher prevalence of liver involvement (94% versus 3%, p < 0.001). Moreover, those patients with HCV-related SS showed a higher prevalence of anti-parietal cell gastric antibodies (31% versus 13%, p = 0.03), antimitochondrial antibodies (14% versus 2%, p = 0.02), cryoglobulinemia (60% versus 10%, p < 0.001), hypocomplementemia (60% versus 8%, p < 0.001), and a lower prevalence of anti-Ro/SS-A (17% versus 38%, p = 0.03). The "true" SS observed in some patients with HCV may be considered 1 of the extrahepatic manifestations of HCV, and we suggest that HCV infection can be considered as an exclusion criterion for the diagnosis of primary SS.

What can transgenic and gene-targeted mouse models teach us about salivary gland physiology?

Thousands of genetically modified mice have been developed since the first reports of stable expression of recombinant DNA in this species nearly 20 years ago. This mammalian model system has revolutionized the study of whole-animal, organ, and cell physiology. Transgenic and gene-targeted mice have been widely used to characterize salivary-gland-specific expression and to identify genes associated with tumorigenesis. Moreover, several of these mouse lines have proved to be useful models of salivary gland disease related to impaired immunology, i.e., Sjögren's syndrome, and disease states associated with pathogens. Despite the availability of genetically modified mice, few investigators have taken advantage of this resource to better their understanding of salivary gland function as it relates to the production of saliva. In this article, we describe the methods used to generate transgenic and gene-targeted mice and provide an overview of the advantages of and potential difficulties with these models. Finally, using these mouse models, we discuss the advances made in our understanding of the salivary gland secretion process.

Possible role of cytotoxic T cells in acute liver injury in hepatitis C virus cDNA transgenic mice mediated by Cre/loxP system

A line of hepatitis C virus (HCV) transgenic mice was established previously that was mediated by Cre/loxP system using HCV cDNA, including core, E1, E2 and NS2 genes. Intravenous infection of a recombinant adenovirus that expresses Cre DNA recombinase (AxCANCre) induced HCV structural protein expression in the liver of transgenic mice. HCV core protein production and transgene recombination in the mouse liver were serially evaluated after AxCANCre infusion. Core proteins were expressed efficiently and transgene was almost completely recombined in the liver of mice after 3 days and then the levels of both core protein production and transgene recombination decreased continuously for 28 days. However, 30.6% of the transgene recombination remained at 28 days and only 2.7% of core production remained at 28 days after infection. Compared with nontransgenic controls, the serum alanine aminotransferase levels in transgenic mice were significantly higher 10, 14, and 21 days after adenovirus infection. Histological scoring also indicated severe pathological changes in the liver of transgenic mice after adenovirus infection. AxCANCre infusion increased CD8+ lymphocyte infiltration into the liver of transgenic mice compared with that of non-transgenic controls. Furthermore, cytotoxic T lymphocytes (CTLs) isolated from transgenic mice during liver injury were specific for the HCV proteins. These results suggest that HCV structural proteins expressed in the liver of transgenic mice enhanced liver injury. HCV-specific CTLs may be to enhance hepatitis. Thus, the present HCV transgenic mouse model provides a useful model of liver injury due to HCV, and the host immune response may play a pivotal role(s) in the pathogenesis of HCV.

Histopathological and immunohistochemical study of oral lichen planus-associated HCV infection

Background: In recent years, it has been suggested that oral lichen planus (OLP), a chronic inflammatory keratotic lesion, is related to hepatitis C virus (HCV) infection. Therefore, we evaluated whether the presence or absence of HCV infection caused any histopathological differences in OLP tissues. Methods; The subjects consisted of 31 patients with HCV-related liver disease complicated by OLP (32 OLP lesions) and ten OLP patients without complications due to either HCV infection or liver disease (control). A histopathological evaluation was performed in these patients. In addition, immunostaining was done on nine OLP tissues infected with HCV and on six OLP tissues without HCV infection in order to evaluate lymphocyte subsets (T cells or B cells) infiltrating into topical regions with OLP. Furthermore, the severity of hepatic fibrosis and inflammation was evaluated in liver tissues obtained by liver biopsy from six patients with HCV-related liver disease to evaluate whether there were any relationships between the severity of hepatic fibrosis or inflammation and OLP tissues. Results: There were no significant differences in the histopathological characteristics specific to OLP or in the ratios of T and B cells among infiltrating lymphocytes regardless of the presence or absence of HCV infection. Moreover, there were no certain relationships between the severity of hepatic fibrosis or inflammation and the severity of lymphocytic infiltration in OLP. Conclusions: HCV infection does not appear to influence the histopathological and immunohistochemical features of OLP.

Hepatitis C infection and associated oral health problems

Hepatitis C infection is widespread throughout the community. This study aimed to assess the status of oral health of persons infected with hepatitis C. DMFT and CPITN indices were recorded at a clinic providing priority dental care for people with hepatitis C infection. The data were compared with information from an existing survey of general dental patients. Social impact was assessed using a modified Oral Health Impact Profile questionnaire. The DMFT index differed significantly between hepatitis C and general patients. The number of decayed and missing teeth was greater in those infected with hepatitis C for all patients aged between 25 and 50 years. Although there was no significant difference in CPITN categories for subjects evaluated, a marked trend for poor periodontal health was noted for those individuals with hepatitis C. Salivary flow was reduced in 50 per cent of hepatitis C infected subjects. Social impact was significantly affected with 71 per cent of hepatitis C subjects reporting painful aching in the mouth and 56 per cent having difficulty in relaxing. In conclusion, the results from the project strongly indicate an urgent need for priority delivery of dental care for people with hepatitis C infection.

Latent autoimmune thyroiditis in untreated patients with HCV chronic hepatitis: a case-control study

In order to establish a relationship between Hepatitis C virus (HCV) chronic infection and autoimmune thyroiditis, 97 untreated patients with biopsy-proven HCV chronic hepatitis and 97 controls were studied. An ultrasound examination of the thyroid and an assay of serum thyroid-stimulating hormone (TSH), thyroid hormones and anti-thyroid antibodies were performed in all cases. The overall prevalence of thyroid abnormalities was higher in patients than in controls (17 vs. 4%, P<0.01) and the prevalence of anti-thyroid antibodies was significantly different between the two groups (P<0. 02). HCV patients with (n=13) compared to HCV patients without anti-thyroid antibodies (n=84) were older, predominantly female, and more frequently had increased serum TSH levels or a hypoechogenic pattern of the thyroid gland, while Knodell's score and prevalence of cirrhosis were similar. Latent autoimmune thyroiditis is more frequent in untreated HCV patients than in controls. This finding raises questions about the mechanism of autoimmunity induced by HCV and provides an explanation for the high rate of overt autoimmune thyroiditis during interferon treatment in these patients.

Gastric mucosa as an additional extrahepatic localization of hepatitis C virus: viral detection in gastric low-grade lymphoma associated with autoimmune disease and in chronic gastritis

The hepatitis C virus (HCV) has been linked to B-cell lymphoproliferation and autoimmunity, and has been localized in several tissues. The clinical observation of an HCV-infected patient with Sjögren's syndrome (SS) and Helicobacter pylori (HP) positive gastric low-grade B-cell non-Hodgkin's lymphoma (NHL), which did not regress after HP eradication, led us to investigate the possible localization of HVC in the gastric microenvironment. HCV genome and antigens were searched in gastric biopsy specimens from the previously mentioned case, as well as from 9 additional HCV-infected patients (8 with chronic gastritis and 1 with gastric low-grade B-cell NHL). HCV-specific polymerase chain reaction (PCR) and immunohistochemistry procedures were used. The gastric B-cell NHL from the patient with SS was characterized by molecular analyses of B-cell clonality. HCV RNA was detected in both the gastric low-grade B-cell NHL and in 3 out of 6 gastric samples from the remaining cases. HCV antigens were detected in the residual glandular cells within the gastric B-cell NHL lesions, in glandular cells from 2 of the 3 additional gastric lesions that were HCV positive by PCR, and in 1 additional chronic gastritis sample in which HCV-RNA studies could not be performed. By molecular analyses, of immunoglobulin genes, the B-cell NHL from the patient with SS was confirmed to be a primary gastric lymphoma, subjected to ongoing antigenic stimulation and showing a significant similarity with rheumatoid factor (RF) and anti-HCV- antibody sequences. Our results show that HCV can localize in the gastric mucosa.

Processing and functions of Hepatitis C virus proteins

Hepatitis C virus (HCV) has a positive-stranded RNA genome of about 9.5 kb and a large open reading frame encoding a precursor polyprotein of ca. 3,000 amino acids (aa). This polyprotein is cleaved by host cellular signalase(s) and viral proteases into 10 viral proteins in the order of NH(2)-Core-E1-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS 5B-COOH. Core and E1/E2 are considered to be a capsid protein and envelope glycoproteins, respectively. NS2-NS5B are putative nonstructural proteins involved in the replication of HCV. NS2/3 is a metalloprotease which cleaves in cis at the NS2/3 junction. NS3 possesses serine protease and RNA helicase activities and is responsible for the cleavage of the remaining nonstructural proteins. NS4A is suggested to be a cofactor for NS3 protease. Although the function of p7, NS4B and NS5A are still unknown, an association of a mutation in NS5A with a susceptibility to interferon (IFN) has been reported. NS5B possesses an RNA-dependent RNA polymerase activity. Most of the current findings in HCV proteins depend on expression studies of HCV cDNA clones because of the lack of an efficient replication system in cell cultures. Therefore, a final assignment of cleavages and functions of HCV proteins has to await the propagation of HCV in cell cultures.

Fas Ligand-Mediated Exocrinopathy Resembling Sjögren’s Syndrome in Mice Transgenic for IL-10

Although IL-10 has been implicated in the pathogenesis of several autoimmune diseases, the mechanisms by which this cytokine mediates inflammatory lesions remain to be elucidated. Exocrine gland destruction is an important early step in the development of Sjögren’s syndrome. To better understand the role of IL-10 in Sjögren’s syndrome, we made transgenic mice in which the mouse IL-10 gene was regulated by the human salivary amylase promoter. Transgenic expression of IL-10 induced apoptosis of glandular tissue destruction and lymphocyte infiltration consisting primarily of Fas-ligand (FasL)+ CD4+ T cells, as well as in vitro up-regulation of FasL expression on T cells. These data suggest that overexpression of IL-10 in the glands and their subsequent Fas/FasL-mediated bystander tissue destruction is a causal factor in the development of this disease.

Murine cytomegalovirus induces a Sjögren's syndrome-like disease in C57Bl/6-lpr/lpr mice

OBJECTIVE

To analyze Fas and tumor necrosis factor receptor I (TNFRI) apoptosis pathways in salivary gland inflammatory disease induced by murine cytomegalovirus (MCMV) infection.

METHODS

Four different strains of mice (C57BI/6 [B6]-+/+, Fas-deficient B6-lpr/lpr, TNFRI-deficient B6-tnfr1(0/0), and B6-tnfr1(0/0)-lpr/lpr mice) were infected intraperitoneally with the Smith strain of MCMV (1 x 10(5) plaque-forming units). Viral load was determined by a plaque assay, inflammation and apoptosis by immunohistochemistry and staining with terminal dUTP nickend labeling, and autoantibodies by enzyme-linked immunosorbent assay.

RESULTS

Infectious MCMV was not detectable by day 100. Although all MCMV-infected mice developed acute sialadenitis by day 28, a chronic (>100 days), severe salivary gland inflammation and anti-Ro and anti-La antibodies developed only in the B6-lpr/lpr mice. Apoptotic cells were detected during the acute, but not the chronic, phase of inflammation.

CONCLUSION

Both Fas- and TNFRI-mediated apoptosis contribute to the clearance of MCMV-infected cells in the salivary glands. However, because Fas-mediated apoptosis is necessary for the down-modulation of the immune response, a defect in this process can lead to a postinfection, chronic inflammatory response that resembles Sjögren's syndrome.

The core protein of hepatitis C virus induces hepatocellular carcinoma in transgenic mice

Hepatitis C virus (HCV) is the main cause of chronic hepatitis worldwide. Chronic hepatitis ultimately results in the development of hepatocellular carcinoma (HCC). However, the mechanism of hepatocarcinogenesis in chronic HCV infection is still unclear. The ability of the core protein of HCV to modulate gene transcription, cell proliferation and cell death may be involved in the pathogenesis of HCC. Here, we report the development of HCC in two independent lines of mice transgenic for the HCV core gene, which develop hepatic steatosis early in life as a histological feature characteristic of chronic hepatitis C. After the age of 16 months, mice of both lines developed hepatic tumors that first appeared as adenomas containing fat droplets in the cytoplasm. Then HCC, a more poorly-differentiated neoplasia, developed from within the adenomas, presenting in a 'nodule-in-nodule' manner without cytoplasmic fat droplets; this closely resembled the histopathological characteristics of the early stage of HCC in patients with chronic hepatitis C. These results indicate that the HCV core protein has a chief role in the development of HCC, and that these transgenic mice provide good animal models for determining the molecular events in hepatocarcinogenesis with HCV infection.

Hepatitis C virus, non-Hodgkin's lymphomas and hepatocellular carcinoma

In a case-control study in northeastern Italy hepatitis C virus infection seemed to increase by about 50-fold the risk of non-Hodgkin's lymphoma involving the liver and major salivary glands (i.e. larger than that for hepatocellular carcinoma) and by about fourfold the risk of lymphomas at other sites.