Epstein-Barr virus as an etiological agent in primary Sjögren's syndrome

Sjögren's Syndrome and Viral Infections

Sjögren's syndrome (SS) is a systemic autoimmune disease, characterized by lymphocytic infiltration of the secretory glands. This leads to dryness of the main mucosal surfaces such as the mouth, eyes, nose, larynx, pharynx, and vagina. Although there is little morbidity data at the initial diagnosis, SS may be a serious disease, with extra mortality caused by hematological cancer. The cause of SS is unknown, but factors postulated to play a role include genetic and environmental factors, hormonal abnormality, and viral infection. Under the influence of these factors, the immune system becomes abnormal and the tissue is damaged. In this study, we summarize recent developments in our understanding of the relationship between SS and viral infections, including Epstein-Barr virus (EBV), hepatitis C virus (HCV), human T cell lymphotropic virus type 1 (HTLV-1), cytomegalovirus (CMV), and human immunodeficiency virus (HIV).

Role of Viral Infections in the Pathogenesis of Sjögren's Syndrome: Different Characteristics of Epstein-Barr Virus and HTLV-1

Viruses are possible pathogenic agents in several autoimmune diseases. Sjögren’s syndrome (SS), which involves exocrine dysfunction and the appearance of autoantibodies, shows salivary gland- and lacrimal gland-oriented clinical features. Epstein-Barr virus (EBV) is the most investigated pathogen as a candidate that directly induces the phenotype found in SS. The reactivation of the virus with various stimuli induced a dysregulated form of EBV that has the potential to infect SS-specific B cells and plasma cells that are closely associated with the function of an ectopic lymphoid structure that contains a germinal center (GC) in the salivary glands of individuals with SS. The involvement of human T-cell leukemia virus type 1 (HTLV-1) in SS has been epidemiologically established, but the disease concept of HTLV-1-associated SS remains unexplained due to limited evidence from basic research. Unlike the cell-to-cell contact between lymphocytes, biofilm-like structures are candidates as the mode of HTLV-1 infection of salivary gland epithelial cells (SGECs). HTLV-1 can infect SGECs with enhanced levels of inflammatory cytokines and chemokines that are secreted from SGECs. Regardless of the different targets that viruses have with respect to affinitive lymphocytes, viruses are involved in the formation of pathological alterations with immunological modifications in SS.

A Case of Ulcerative Colitis Following Acute Hepatitis Induced by Epstein-Barr Virus Infection

Epstein-Barr virus (EBV) infection varies in its clinical manifestations and severity. EBV can be a causative agent of hepatitis and may have a role in the pathogenesis of chronic autoimmune diseases including inflammatory bowel disease. A 24-year-old woman was admitted to our hospital, presenting with fever and elevated liver enzymes. She was diagnosed with acute hepatitis and EBV infection according to serologic tests and liver biopsy. Within two months, she was re-admitted to our hospital, presenting with hematochezia and lower abdominal pain. She was diagnosed with ulcerative colitis. In situ hybridization for EBV was positive in initial liver biopsy and colon biopsy. Here we report an unusual case of acute EBV hepatitis followed at a short interval by ulcerative colitis.

Fatal chronic active Epstein-Barr virus infection mimicking autoimmune hepatitis

We report a 22-year-old female who presented with pyrexia, pancytopenia and liver dysfunction. The patient showed mild liver dysfunction with low-grade fever and mild hepatosplenomegaly 6 years previously, and autoimmune hepatitis (AIH) was diagnosed based on the examination of the laboratory data and liver biopsy. On admission, both markers of Epstein-Barr virus (EBV) and in-situ hybridisation from a liver biopsy specimen indicated chronic active EBV infection (CAEBV). The patient was administered an immunosuppressive agent and antiviral drug added to steroid therapy, but ultimately died from liver failure and virus-associated haemophagocytosis 10 months after the definite diagnosis. Retrospective examination of the serum at the diagnosis of AIH revealed extremely high titres of antibody to EBV, and EBV-DNA was also detectable by polymerase chain reaction. These results suggest the possibility that the patient may already have suffered from CAEBV at the initial diagnosis. We presume that hepatic involvement of CAEBV should be considered as differential diagnosis in cases showing liver dysfunction with clinical and biochemical features observed in AIH.

An update of the etiology and management of xerostomia

Salivary gland disease gives rise to salivary gland enlargement, pain, and prolonged xerostomia (dry mouth). Xerostomia is the most common long-standing problem for the majority of affected patients. There are many causes of dry mouth, with long-standing xerostomia being a particular problem in Sjögren's syndrome and after radiation to the head and neck region. Xerostomia is usually managed with saliva substitutes, but a large number of potential systemic therapies of long-standing xerostomia now exist. Some-particularly immunosuppressants-are of fundamental interest for the potential reduction of gland damage in Sjögren's syndrome but as yet are of limited clinical usefulness. Others, particularly pilocarpine and cevimeline, are, or have the potential to be, clinically useful in stimulating salivation by virtue of their action on cholinergic receptors.

Human autoantibodies directed against the RNA recognition motif of La (SS-B) bind to a conformational epitope present on the intact La (SS-B)/Ro (SS-A) ribonucleoprotein particle

In systemic autoimmunity, the human B cell response to the La (SS-B) autoantigen is polyclonal and directed to both conserved and human-specific epitopes. This study has further characterized the B cell epitope(s) present within the conserved central region of the La protein, LaC (amino acids 111-242) containing the RNA recognition motif (RRM, aa 111-187). Ten overlapping and non-overlapping protein fragments spanning LaC were expressed in bacteria as NH2-terminal fusions with glutathione-S-transferase. The fusion proteins were tested by ELISA for reactivity with a panel of human anti-La sera in order to define the nature of the epitopes. Ninety-two percent of patient sera containing anti-La antibodies reacted with the region of La containing the RRM. Fine mapping of this reactivity using deletion mutants indicated that the deletion of 19 amino acids from either the NH2-terminal or COOH-terminal region of the RRM was associated with loss of antibody reactivity, suggesting that the immunodominant epitope expressed in this region is discontinuous. Autoantibodies affinity-purified from the La RRM fragment to remove other specificities immunoprecipitated newly synthesized native La (SS-B)/Ro (SS-A) complexes, providing additional evidence that autoantibodies were recognizing a conformational epitope. The findings indicate that the human autoantibody response to La involves recognition of a conformational determinant involving the conserved RRM region without necessarily interfering with the RNA-dependent association of the La/Ro ribonucleoprotein.

Cytokine production in response to Epstein-Barr virus infection of peripheral blood mononuclear cells in vitro

To obtain a better understanding of the immune response to Epstein-Barr virus (EBV), we measured the cytokines tumour necrosis factor (TNF)-alpha/beta, interleukin-2 (IL-2), interferon-gamma (IFN-gamma), IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF) in the conditioned medium of peripheral blood mononuclear cells from 10 healthy adults before and at 48 h and at 1, 2, 3 and 4 weeks following infection in vitro with EBV. Cultures were examined for regression of outgrowths of nascent virus-transformed B cells, and populations of cells in the cultures were analysed by flow cytometry. TNF-alpha/beta was not detected in infected or non-infected cultures. In infected cultures assayed at the nominated times, the highest levels of IL-2 were detected at 48 hours, IFN-gamma at 1 week, IL-6 at 2 weeks and GM-CSF between 2 and 4 weeks. IL-6 and GM-CSF, but not IL-2 or IFN-gamma, were detected in non-infected cultures but at lower levels than in infected cultures. Nine of the 10 healthy adults showed regression of outgrowths of virus-transformed B cells and, of these, seven had antibodies to the EBV capsid antigen (VCA). Strong regression was associated with sequential increases in IL-2, IFN-gamma, and low levels of IL-6 and GM-CSF. Absent or weak regression was associated with an undetectable level of IL-2, a low level of IFN-gamma, high levels of IL-6 and GM-CSF and an increased frequency of cells bearing the phenotype CD20 and HLA-DR in the final weeks of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased antibody reactivity to Epstein-Barr virus capsid antigen in type 1 (insulin-dependent) diabetes mellitus

In this study, antibody levels to Epstein-Barr virus (EBV) capsid antigen (VCA) and EBV early antigens (EA) were analysed by enzyme immunoassay in 54 newly diagnosed type 1 diabetic children and in matched controls. The patients had significantly lower EBV VCA IgG-class antibody levels (p less than 0.02). This was true particularly in young patients and in boys (p less than 0.005). VCA IgA-class antibody levels were also decreased in young patients (p less than 0.02). VCA IgM-class antibodies were observed in two of the patients only. IgG- and IgA-class antibodies to EBV EA or rubella virus antigen showed no differences between patients and controls. The results suggest that EBV infections coincide with the onset of clinical diabetes relatively rarely. However, the abnormally low antibody response to EBV VCA in diabetic children suggests abnormalities in the EBV-specific immune response.

The role of infections in the rheumatic diseases: molecular mimicry between bacterial and human stress proteins?

Infections can cause or exacerbate the rheumatic diseases in several ways, including immune cross-reactivity between bacterial heat shock proteins and similar proteins in normal human tissues. This may lead to autoimmunity in rheumatoid arthritis and systemic lupus. In addition, increased activation of the gene regulating the synthesis of a heat shock protein has been found in scleroderma fibroblasts. As an infection-induced model for other rheumatic diseases, rheumatic fever (RF), with its well-established link to prior group A streptococcal infection, will be revisited. The lessons learned from RF and other rheumatic diseases directly linked to infection will be applied to ankylosing spondylitis, rheumatoid arthritis, Sjogren's syndrome and polymyositis, for which a mounting body of circumstantial evidence suggests a probable infectious cause. The interplay of genetic susceptibility and infection with particular organisms and the implications of this new information for present and future therapy of the rheumatic diseases will also be presented.

Autoepitopes reactive with anti-SS-B/La

Sera from 120 patients with suspected autoimmune rheumatic disease and antinuclear antibodies of anti-SS-B/La specificity were examined by Western blotting for reactivity with the SS-B/La polypeptide of HeLa cells and recombinant SS-B/La derived from a 1.4 kilobase (kb) cDNA encoding approximately 90% of the SS-B/La molecule. All sera reacted with the HeLa cell and the recombinant SS-B/La. One hundred and fourteen (95%) reacted with a set of three Staph. aureus V8 protease-resistant peptides of Mr 30,000, 29,00 and 28,000 from a methionine-rich region of HeLa cell SS-B/La designated the X domain, and 98 (82%) reacted with another set of two protease-resistant peptides of Mr 24,000 and 23,000 from a phosphorylated region of HeLa cell La designated the Y domain. One reacted weakly with the Y domain only. All sera that reacted with X and Y reacted more strongly with X, suggesting that X was the major epitope. Antibodies affinity purified from the X domain reacted strongly with the X peptides but not with the Y peptides and conversely, antibodies affinity purified from the Y domain reacted with the Y peptides but not with the X peptides. Both antibodies reacted with a fusion protein comprising 102 amino acids at the carboxyl terminus of the SS-B/La molecule. This protein contained no methionine, demonstrating that methionines were not involved in the antibody-binding site. Over 80% of patients whose only criteria for selection was the presence of anti-SS-B/La had the clinical, histologic, serologic and phenotypic features of Sjögren's syndrome whilst the remaining 20% had at least two of the features.(ABSTRACT TRUNCATED AT 250 WORDS)

A novel EBV-related nucleo-cytoplasmic antigen in a null cell-line (HLN-STL-C) reactive to antibodies in the sera from patients with Sjögren's syndrome

We have established a non-T- and non-B-cell line, HLN-STL-C(STL-C), which harbors the EBV genome, from the lymph node cells of a Japanese ATL patient. This cell line expresses a unique Epstein-Barr virus (EBV)-related nucleo-cytoplasmic (N-C) antigen which is detected by indirect immunofluorescence (IF) with the sera from patients with nasopharyngeal cancer (NPC), infectious mononucleosis (IM) or adult T-cell leukemia (ATL). One of the molecular components of this antigen is proved to be STL-C specific 125 kD molecule by immunoblot analysis (IB). To study the involvement of EBV in Sjögren's syndrome (SS), we examined the reactivity of the N-C antigen with the sera of SS patients by IF and IB. Among 24 cases examined, the sera of 21 cases (87.5%) positively stained the N-C antigen by IF. The staining patterns were divided into two types. Type I, (seven cases) showed positive staining for only N-C antigen, and Type II, (14 cases) was positive for N-C antigen associated with diffuse nuclear staining due to antinuclear antibodies in the SS patient's sera. Only one out of 11 non-Sjögren's patients' sera, which were almost all healthy controls, was positive for N-C antigen in this study. By IB, however, only two out of 15 IF-positive SS patients' sera reacted with STL-C specific 125 kD molecule. These results suggested the presence of heterogenous components in the N-C antigen. Our findings may support the hypothetical conception that EBV plays an etiological role in SS.

Epstein-Barr virus as a cause of autoimmune disease and other medical morbidity in patients with affective disorders

We hypothesize that psychiatric patients suffering from the major affective disorders (depression and manic-depressive illness) may commonly also suffer from a chronic active infection with the Epstein-Barr virus. This infection would be a consequence of the immune dysfunction known to be associated with these disorders of mood. According to this hypothesis, the increased medical morbidity and mortality reported in these psychiatric patients would be attributable in part to diseases in which Epstein-Barr virus is implicated or suspected as a cause.

Hepatic and biliary autoantigens

Chronic active hepatitis (CAH) and primary biliary cirrhosis (PBC) are two enigmatic liver diseases in which autoimmunity is implicated. Provisional criteria to separate the autoimmune type of CAH (A-CAH) from others are specified. Western immunoblotting using disease sera and antibody screening of a rat liver gene expression library were used to identify hepatic and biliary autoantigens relevant to the pathogenesis of A-CAH or PBC. With all reported putative liver-specific autoantigen preparations, serum reactivity in A-CAH and CAH due to infection with hepatitis B virus tends to be similar. In A-CAH, immunoblotting showed multiple reactivities with all liver preparations used, including hepatocyte membrane. In PBC, immunoblotting showed two disease-specific polypeptide antigens of MW 70 and 45 kD. A cDNA clone derived from a rat liver gene expression library was shown to encode the antigenic site of the 70 kD polypeptide. Recently published work in two other laboratories has established that the 70 kD autoantigen is the E2 component of the pyruvate dehydrogenase enzyme (PDH), and a proposed antibody-binding site (autoepitope) is a conserved decapeptide, corresponding to residues 83-92 of the deduced amino acid sequence of M2, which is the binding site of lipoic acid to the E2 component of PDH.

Antinuclear antibodies as molecular and diagnostic probes

Much progress has been made in the past decade in defining the specificities of antinuclear antibodies (ANA) that are present in the blood of patients with multi-system autoimmune rheumatic diseases, and ANA now have an important place in diagnostic immunology. Disease-specific ANA have been defined and the intracellular autoantigens against which they react have been characterized. ANA have also established an important place in cell biology. Their use as probes has enabled molecular biologists to isolate, purify and assay the function of the highly conserved molecules with which they react, revealing new insights into the role these molecules play in gene transcription and translation. Cloning of the genes encoding these molecules in addition to providing information on primary structure has also provided human recombinant proteins for use as pure substrates for the development of simple and highly sensitive diagnostic assays in rheumatology. Studies on the epitopes with binding sites for ANA should provide new knowledge on how the immune response to these molecules evolves, how it is maintained and what role ANA play in the pathogenesis of disease.