The influence of Epstein-Barr virus reactivation in patients with Graves' disease

The role of Epstein-Barr virus in autoimmune and autoinflammatory diseases

Epstein-Barr Virus (EBV), a dsDNA herpesvirus, is believed to play a significant role in exacerbating and potentially triggering autoimmune and autoinflammatory maladies. Around 90% of the world is infected with the virus, which establishes latency within lymphocytes. EBV is also known to cause infectious mononucleosis, a self-limited flu-like illness, in adolescents. EBV is often reactivated and it employs several mechanisms of evading the host immune system. It has also been implicated in inducing host immune dysfunction potentially resulting in exacerbation or triggering of inflammatory processes. EBV has therefore been linked to a number of autoimmune diseases, including systemic lupus erythematosus, multiple sclerosis, rheumatoid arthritis, and Sjögren's syndrome. The review examines the molecular mechanisms through which the virus alters host immune system components thus possibly resulting in autoimmune processes. Understanding the mechanisms underpinning EBV-associated autoimmunity is pivotal; however, the precise causal pathways remain elusive. Research on therapeutic agents and vaccines for EBV has been stagnant for a long number of years until recent advances shed light on potential therapeutic targets. The implications of EBV in autoimmunity underscore the importance of developing targeted therapeutic strategies and, potentially, vaccines to mitigate the autoimmune burden associated with this ubiquitous virus.

Pericardial Manifestations of Thyroid Diseases

PURPOSE OF REVIEW

Thyroid disorders, especially hypothyroidism, are known to be associated with pericardial diseases. The aim of this paper is to review the current knowledge of the pericardial manifestations of hypothyroidism and hyperthyroidism.

RECENT FINDINGS

Many reports have described associations between dysthyroidism, which encompasses hypothyroidism and hyperthyroidism, and several pericardial diseases, including acute pericarditis, constrictive pericarditis, pericardial effusion, and tamponade. The diagnosis of dysthyroidism-induced pericardial diseases consists of a combination of thyroid blood levels that fall outside of the normal range and the exclusion of other causes. Treatment of the thyroid disorder is key, along with treatment of the pericardial disease as recommended by the guidelines. Early recognition of the thyroid disorder is key in patients with pericardial diseases, since treating the underlying cause should assist resolution of the pericardial issues and ideally prevent recurrence and possible future complications of suboptimally treated pericarditis or pericardial effusions.

Double trouble - thyro-pericarditis: rare presentation of Graves' disease as pericarditis-a case report

Background

Acute pericarditis is frequently encountered in clinical practice; however, pericarditis as the first presentation of Graves' disease is rare and mainly limited to case reports in the literature. We hereby report a case in which a young patient presented with pericarditis as the first manifestation of Graves’ disease.

Case summary

A 24-year-old male was admitted to hospital with presenting complaint of left-sided chest pain, gradual in onset, 6/10 in intensity, sharp in character, increased by deep breathing and improved by leaning forward. Patient also gave a history of insomnia, unintentional weight loss despite a good appetite, heat intolerance, and anxiety. On clinical examination, the patient had features of thyrotoxicosis, i.e., tachycardia, high volume pulse, and sweaty palms with fine tremors. There was no associated pericardial rub. Neck examination shows diffuse, non-tender goitre. Electrocardiogram findings were consistent with acute pericarditis. His thyroid function tests demonstrated hyperthyroidism and anti-thyroglobulin antibodies were also significantly elevated. Echocardiogram showed preserved left ventricular systolic function and a small global pericardial effusion without any signs of tamponade. He was diagnosed with Graves’ disease revealing itself as pericarditis and was started on ibuprofen, beta-blockers, and carbimazole. Patient had marked clinical and biochemical improvement on 3 monthly follow-ups.

Discussion

Thyro-pericarditis is a rare entity, and limited literature is available regarding this combination. The exact aetiology of Graves associated pericarditis is unknown. There is a possibility of interaction of autoantibodies with receptors on pericardium. Diagnosis is based on a detailed history, clinical examination, supplemented by relevant investigations (elevated free T4 and thyroid receptor antibodies, suppressed thyroid stimulating hormone (TSH) and Imaging via ultrasound). Mainstay of treatment includes non-steroidal anti-inflammatory drugs, beta-blockers, and anti-thyroidal medications.

Epstein-Barr Virus Reactivation-Induced Immunoglobulin Production: Significance on Autoimmunity

Epstein–Barr virus (EBV) mainly persists in B cells, which differentiate into antibody-producing cells, and thus, EBV has been implicated in autoimmune diseases. We aimed to describe the EBV reactivation and its relevance to autoimmune disease, focusing on Graves’ disease, which is an autoimmune hyperthyroidism caused by thyrotropin receptor antibodies. Circulating autoreactive B cells that have evaded from the selection have difficulties differentiating to produce antibodies. However, once EBV infects such B cells and reactivates, the B cells may become plasma cells and produce autoantibody. We herein proposed an EBV reactivation-induced Ig production system, which is a distinct pathway from the antibody production system through germinal centers and bone marrow and has the following characteristics: 1. IgM dominance, 2. ubiquitous Ig production, and 3. the rescue of autoreactive B cells, which skews Ig production toward autoantigens. IgM autoantibodies induced by EBV reactivation may activate the classical complement pathway and injure healthy tissue, which supply autoantigens for the production of affinity-matured IgG autoantibodies. Antibodies induced by EBV reactivation may play important roles in the development and exacerbation of autoimmune diseases.

Does the Epstein-Barr Virus Play a Role in the Pathogenesis of Graves' Disease?

Graves’ disease (GD) it the most common chronic organ-specific thyroid disorder without a fully recognized etiology. The pathogenesis of the disease accounts for an interaction between genetic, environmental, and immunological factors. The most important environmental factors include viral and bacterial infections. The Epstein-Barr virus (EBV) is one of the most common latent human viruses. Literature has suggested its role in the development of certain allergic and autoimmune diseases. EBV also exhibits oncogenic properties. The aim of the study was to analyze and compare the presence of EBV DNA in peripheral blood mononuclear cells (PBMCs) in patients with newly recognized GD and to find a correlation between EBV infection and the clinical picture of GD. The study included 39 untreated patients with newly diagnosed GD and a control group of 20 healthy volunteers who were gender and age matched. EBV DNA was detected with reverse transcription polymerase chain reaction (RT PCR) assay. The studies showed a significantly higher incidence of EBV copies in PBMCs among GD patients compared to the control group. Whereas, no significant correlations were found between the incidence of EBV copies and the evaluated clinical parameters. Our results suggest a probable role of EBV in GD development. EBV infection does not affect the clinical picture of Graves’ disease.

Estradiol Affects Epstein-Barr Virus Reactivation-Induced Thyrotropin Receptor Antibody and Immunoglobulin Production in Graves' Disease Patients and Healthy Controls

Epstein-Barr virus (EBV) is a gamma-herpesvirus persisting mainly in human B lymphocytes. EBV reactivation induces host cells to differentiate into plasma cells and is related to autoimmune diseases. Graves' disease, an autoimmune hyperthyroidism, is caused by the thyrotropin receptor antibody (TRAb), which overstimulates thyroid stimulating hormone receptor. The disease occurs predominantly in women, which suggests involvement with estrogen. Graves' disease patients and healthy controls have EBV-infected lymphocytes with TRAb on the surface (TRAb(+)EBV(+) cells) in peripheral blood mononuclear cells (PBMCs). TRAb can be produced by reactivation of EBV in vitro, which is an alternative system of antibody production. In this study, we cultured PBMCs from Graves' disease patients and healthy controls with 0, 1, and 100 nM estradiol, corresponding to control, midluteal, and pregnancy levels, respectively, and analyzed the levels of TRAb, total-IgG, and total-IgM during EBV reactivation. We found that 1 nM estradiol increased TRAb levels and 100 nM estradiol slightly lowered them in both patients and controls. In patients, IgM production at 100 nM estradiol was significantly lower than that at 0 nM estradiol (p = 0.028). Estradiol increased the ratio of IgG production to immunoglobulin G (IgG) and immunoglobulin M (IgM) production (IgG/IgG + IgM), which suggested an increase in class switch recombination in the process of EBV reactivation-induced Ig production. Moreover, TRAb production was stimulated by a midluteal level of estradiol and was suppressed by a pregnancy level of estradiol in controls and patients. These results were consistent with premenstrual worsening and maternity improving of autoimmune diseases, including Graves' disease.

Investigation on the association between thyroid tumorigeneses and herpesviruses

Herpesviruses have been associated with various human malignancies and with thyroid autoimmunity. Aiming to investigate the presence of these viruses in thyroid nodules, we analyzed serum and thyroid tissue from 183 patients (83 benign and 100 malignant thyroid nodules). We also obtained 104 normal thyroid tissues extracted from the contralateral lobe of these patients. We used ELISA to screen the serology of all patients and a real-time quantitative PCR to analyze thyroid tissue viral load in antibody-positive patients. In addition, the presence of herpesviruses was tested by histological analysis in 20 EBV-positive tissues using the expression of LMP-1 by immunohistochemistry (IHC) and EBER by in situ hybridization (ISH). There was no evidence of HSV-2 or CMV DNA, but we found EBV DNA sequences in 29 (16%) thyroid tissue samples. We also found 7 positive EBV cases out of 104 normal tissues. Viral load was higher in tumors than in their respective normal tissues (p = 0.0002). ISH analysis revealed EBER expression in 11 out of 20 (52%) EBV-positive tissues, mostly in malignant cases (8/11, 73%). The presence of high EBV copy numbers in thyroid tumors and the expression of EBER only in malignant cases suggest an association between EBV and thyroid malignancies. However, we did not find any association between the presence of EBV and/or its viral load and any clinical or pathological tumor feature. Further studies aiming to clarify the mechanisms of EBV infection in thyroid cells are necessary to support a possible role in the development of thyroid cancer.

Seasonality and autoimmune diseases: The contribution of the four seasons to the mosaic of autoimmunity

Autoimmune diseases (ADs) are a heterogeneous groups of diseases that occur as a results of loss of tolerance to self antigens. While the etiopathogeneis remain obscure, different environmental factors were suggested to have a role in the development of autoimmunity, including infections, low vitamin D levels, UV radiation, and melatonin. Interestingly, such factors possess seasonal variation patterns that could influence disease development, severity and progression. Vitamin D levels which reach a nadir during late winter and early spring is correlated with increased disease activity, clinical severity as well as relapse rates in several disease entities including multiple sclerosis (MS), non-cutaneous flares of systemic lupus erythematosus (SLE), psoriasis, and rheumatoid arthritis (RA). Additionally, immunomodulatory actions of melatonin secretion ameliorate the severity of several ADs including MS and SLE. Melatonin levels are lowest during spring, a finding that correlates with the highest exacerbation rates of MS. Further, melatonin is postulated to be involved in the etiopathogenesis of inflammatory bowel diseases (IBD) through it influence on adhesion molecule and therefore transcription factor expression. Moreover, infections can mount to ADs through pro-inflammatory cytokine release and human antigen mimicry. Seasonal patterns of infectious diseases are correlated with the onset and exacerbation of ADs. During the winter, increased incidence of Epstein-Barr virus (EBV) infectious are associated with MS and SLE flares/onset respectively. In addition, higher Rotavirus infections during the winter precedes type 1 diabetes mellitus onset (T1DM). Moreover, Escherichia coli (E. coli) infection prior to primary biliary cirrhosis (PBC) and T1DM disease onset subsequent to Coxachievirus infections are seen to occur during late summer, a finding that correlate with infectious agents' pattern of seasonality. In this review, the effects of seasonality on the onset, relapses and activity of various ADs were discussed. Consideration of seasonal variation patterns of ADs can possibly provide clues to diseases pathogenesis and lead to development of new approaches in treatment and preventative care.

Epstein-Barr Virus Lytic Reactivation Activates B Cells Polyclonally and Induces Activation-Induced Cytidine Deaminase Expression: A Mechanism Underlying Autoimmunity and Its Contribution to Graves' Disease

Graves' disease is an autoimmune disease that results in and is the most common cause of hyperthyroidism, and the reactivation of persisting Epstein–Barr virus (EBV) in B lymphocytes induces the differentiation of host B cells into plasma cells. We previously reported that some EBV-infected B cells had thyrotropin receptor antibodies (TRAbs) as surface immunoglobulins (Igs), and EBV reactivation induced these TRAb+EBV+ cells to produce TRAbs. EBV reactivation induces Ig production from host B cells. The purpose of the present study was to examine total Ig productions from B cell culture fluids and to detect activation-induced cytidine deaminase (AID), nuclear factor kappa B (NF-κB), and EBV latent membrane protein (LMP) 1 in culture B cells during EBV reactivation induction and then we discussed the mechanisms of EBV reactivation-induced Ig production in relation to autoimmunity. We showed that the EBV reactivation induces the production of every isotype of Ig and suggested that the Ig production was catalyzed by AID through LMP1 and NF-κB. The results that the amount of IgM was significantly larger compared with IgG suggested the polyclonal B cell activation due to LMP1. We proposed the pathway of EBV reactivation induced Ig production; B cells newly infected with EBV are activated by polyclonal B cell activation and produce Igs through plasma cell differentiation induced by EBV reactivation. LMP1-induced AID enabled B cells to undergo class-switch recombination to produce every isotype of Ig. According to this mechanism, EBV rescues autoreactive B cells to produce autoantibodies, which contribute to the development and exacerbation of autoimmune diseases.

Thyrotropin Receptor Antibody (TRAb)-IgM Levels Are Markedly Higher Than TRAb-IgG Levels in Graves' Disease Patients and Controls, and TRAb-IgM Production Is Related to Epstein-Barr Virus Reactivation

Graves' disease is an autoimmune thyroid disorder that mainly presents as hyperthyroidism and is caused by thyrotropin receptor antibodies (TRAbs) that stimulate thyroid-stimulating hormone receptors. We previously reported that Graves' disease patients and healthy controls both had Epstein–Barr virus (EBV)-infected TRAb-positive B cells and the EBV-reactivated induction of these B cells in cultures may induce the production of TRAbs. In the present study, we quantified serum TRAb-IgG and TRAb-IgM levels in 34 Graves' disease patients and 15 controls using ELISA to elucidate the mechanisms underlying EBV-related antibody production. As expected, TRAb-IgG and TRAb-IgM levels were higher in Graves' disease patients than in controls; however, TRAb-IgM levels were significantly higher than those of TRAb-IgG levels, whereas total IgM levels were lower than total IgG levels. On the other hand, the enhanced production of TRAb-IgM was frequently observed in patients with EBV reactivation. These results are consistent with the fact that the percentage of autoreactive IgM B cells are higher than that of autoreactive IgG B cells, and support the EBV-related polyclonal B cell activation. It is necessary to clarify the biological characteristics of TRAb-IgM and the relationship between TRAb isotypes and the biology of Graves' disease.

A pre-eclampsia-associated Epstein-Barr virus antibody cross-reacts with placental GPR50

To characterize antibody specificities associated with pre-eclampsia (PE), bacterial displayed peptide library screening and evolution was applied to identify peptide epitopes recognized by plasma antibodies present in women with PE near the time of delivery. Pre-eclamptic women exhibited elevated IgG1 titers towards a peptide epitope KRPSCIGCK within the Epstein-Barr virus nuclear antigen 1 (EBNA-1). EBNA-1 epitope antibodies cross-reacted with a similar epitope within the extracellular N-terminus of the human G protein-coupled receptor, GPR50, expressed in human placental tissue and immortalized placental trophoblast cells. We observed increased antibody binding activity to epitopes from EBNA-1 and GPR50 among women with PE (n=42) compared to healthy-outcome pregnancies (n=43) and nulligravid samples (n=21). The EBNA-1 peptide potently blocked binding of the PE-associated antibody to the GPR50 epitope (IC50=58-81pM). These results reveal the existence of molecular mimicry between EBNA-1 and placental GPR50, supporting a mechanism for IgG1 deposition in the pre-eclamptic placenta.

Production of thyrotropin receptor antibodies in acute phase of infectious mononucleosis due to Epstein-Barr virus primary infection: a case report of a child

Various autoantibodies have been reported to be detected during the progression of infectious mononucleosis. We observed a case of infectious mononucleosis due to Epstein–Barr virus primary infection for 2 months, and noticed the transiently increased titer of thyrotropin receptor autoantibodies detected at the acute phase on the 3rd day after admission. At that time, real-time quantitative PCR also revealed the mRNA expressions of an immediate early lytic gene, BZLF1, and a latent gene, EBNA2. The expression of BZLF1 mRNA means that Epstein–Barr virus infects lytically, and EBNA2 protein has an important role in antibody production as well as the establishment of Epstein–Barr virus latency. These results suggest that Epstein–Barr virus lytic infection is relevant to thyrotropin receptor autoantibody production. Thyrotropin receptor autoantibodies stimulate thyroid follicular cells to produce excessive thyroid hormones and cause Graves’ disease. Recently, we reported the thyrotropin receptor autoantibody production from thyrotropin receptor autoantibody-predisposed Epstein–Barr virus-infected B cells by the induction of Epstein–Barr virus lytic infection in vitro. This case showed in vivo findings consistent with our previous reports, and is important to consider the pathophysiology of Graves’ disease and one of the mechanisms of autoimmunity.

Reactivation of persistent Epstein-Barr virus (EBV) causes secretion of thyrotropin receptor antibodies (TRAbs) in EBV-infected B lymphocytes with TRAbs on their surface

Epstein-Barr virus (EBV) is a ubiquitous virus that infects most adults latently. It persists in B lymphocytes and reactivates occasionally. Graves' disease is an autoimmune hyperthyroidism caused by thyrotropin receptor antibodies (TRAbs). We have reported that Graves' disease patients and healthy controls have EBV-infected lymphocytes that have TRAbs on their surface (TRAb(+)EBV(+) cells) in peripheral blood mononuclear cells (PBMCs). EBV reactivation is known to be associated with plasma cell differentiation and antibody production of B cells. In this study, we investigated whether TRAb(+)EBV(+) cells really produce TRAbs or not when persistent EBV is reactivated. We cultured PBMCs from 12 Graves' disease patients and 12 healthy controls for several days with cyclosporine A to expand the EBV-infected cell population, and then compared TRAb levels between EBV reactivation by 33 °C culture and EBV nonreactivation by 37 °C culture of PBMCs. Flow cytometry confirmed that all samples at day 0 (reactivation starting point) contained TRAb(+)EBV(+) cells. During 33 °C culture, EBV-reactivated cells with EBV-gp350/220 expression increased from about 1 to 4%. We quantified TRAb levels in culture fluids by radio-receptor assay, and detected an increased concentration for at least one sampling point at 33 °C (from days 0 to 12) for all patients and healthy controls. TRAb levels were significantly higher in supernatants of 33 °C culture than of 37 °C culture, and also significantly higher in supernatants from patients than those from controls. This study revealed TRAb production from TRAb(+)EBV(+) cells in response to reactivation induction of persistent EBV in different efficiencies between patients and controls.

Presence of Epstein-Barr virus-infected B lymphocytes with thyrotropin receptor antibodies on their surface in Graves' disease patients and in healthy individuals

Graves' disease is an autoimmune hyperthyroidism caused by thyrotropin receptor antibodies (TRAbs). Because Epstein-Barr virus (EBV) persists in B cells and is occasionally reactivated, we hypothesized that EBV contributes to TRAbs production in Graves' disease patients by stimulating the TRAbs-producing B cells. In order for EBV to stimulate antibody-producing cells, EBV must be present in those cells but that have not yet been observed. We examined whether EBV-infected (EBV(+)) B cells with TRAbs on their surface (TRAbs(+)) as membrane immunoglobulin were present in peripheral blood of Graves' disease patients. We analyzed cultured or non-cultured peripheral blood mononuclear cells (PBMCs) from 13 patients and 11 healthy controls by flow-cytometry and confocal laser microscopy, and confirmed all cultured PBMCs from 8 patients really had TRAbs(+) EBV(+) double positive cells. We unexpectedly detected TRAbs(+) cells in all healthy controls, and TRAbs(+) EBV(+) double positive cells in all cultured PBMC from eight healthy controls. The frequency of TRAbs(+) cells in cultured PBMCs was significantly higher in patients than in controls (p = 0.021). In this study, we indicated the presence of EBV-infected B lymphocytes with TRAbs on their surface, a possible player of the production of excessive TRAbs, the causative autoantibody for Graves' disease. This is a basic evidence for our hypothesis that EBV contributes to TRAbs production in Graves' disease patients. Our results further suggest that healthy controls have the potential for TRAbs production. This gives us an important insight into the pathogenesis of Graves' disease.

CD8+ T-Cell Deficiency, Epstein-Barr Virus Infection, Vitamin D Deficiency, and Steps to Autoimmunity: A Unifying Hypothesis

CD8+ T-cell deficiency is a feature of many chronic autoimmune diseases, including multiple sclerosis, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, systemic sclerosis, dermatomyositis, primary biliary cirrhosis, primary sclerosing cholangitis, ulcerative colitis, Crohn's disease, psoriasis, vitiligo, bullous pemphigoid, alopecia areata, idiopathic dilated cardiomyopathy, type 1 diabetes mellitus, Graves' disease, Hashimoto's thyroiditis, myasthenia gravis, IgA nephropathy, membranous nephropathy, and pernicious anaemia. It also occurs in healthy blood relatives of patients with autoimmune diseases, suggesting it is genetically determined. Here it is proposed that this CD8+ T-cell deficiency underlies the development of chronic autoimmune diseases by impairing CD8+ T-cell control of Epstein-Barr virus (EBV) infection, with the result that EBV-infected autoreactive B cells accumulate in the target organ where they produce pathogenic autoantibodies and provide costimulatory survival signals to autoreactive T cells which would otherwise die in the target organ by activation-induced apoptosis. Autoimmunity is postulated to evolve in the following steps: (1) CD8+ T-cell deficiency, (2) primary EBV infection, (3) decreased CD8+ T-cell control of EBV, (4) increased EBV load and increased anti-EBV antibodies, (5) EBV infection in the target organ, (6) clonal expansion of EBV-infected autoreactive B cells in the target organ, (7) infiltration of autoreactive T cells into the target organ, and (8) development of ectopic lymphoid follicles in the target organ. It is also proposed that deprivation of sunlight and vitamin D at higher latitudes facilitates the development of autoimmune diseases by aggravating the CD8+ T-cell deficiency and thereby further impairing control of EBV. The hypothesis makes predictions which can be tested, including the prevention and successful treatment of chronic autoimmune diseases by controlling EBV infection.