Epstein-Barr Virus Lytic Reactivation Induces IgG4 Production by Host B Lymphocytes in Graves' Disease Patients and Controls: A Subset of Graves' Disease Is an IgG4-Related Disease-Like Condition

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.

Clinical significance of the detection of serum IgG4 and IgG4/IgG ratio in patients with thyroid-associated ophthalmopathy

To evaluate the clinical significance of detecting serum IgG4 and the IgG4/IgG ratio in patients with thyroid-associated ophthalmopathy (TAO) and to explore whether high serum IgG4 levels and the IgG4/IgG ratio are associated with the severity and activity of TAO, we retrospectively assessed the records of 78 TAO patients and 32 controls collected in our hospital from July 2020 to July 2022. The TAO patients were divided into TAO inactive and TAO active phase groups according to the clinical activity score (CAS), and we evaluated the association between the serum IgG4 levels, the IgG4/IgG ratio, and the clinical data of the participants. The levels of IgG4 significantly increased in the TAO active group compared to those in the inactive and control groups (P < 0.05). Additionally, the number of patients with increased IgG4 levels (≥135 mg/dL) in the TAO active group was markedly higher than that in the inactive and control groups (P < 0.05). The IgG4/IgG ratio was also significantly enhanced in the TAO active group compared to the inactive and control groups (P < 0.05). CAS was identified as an independent factor influencing IgG4 levels in patients with TAO. The levels of serum IgG4, as well as the IgG4/IgG ratio, were significantly increased in some patients with active TAO, and they were related to the CAS, suggesting that the pathogenesis of TAO may be heterogeneous.

Epstein-Barr Virus-Positive Inflammatory Follicular Dendritic Cell Sarcoma Presenting as a Colonic Polyp: Report of a Case with a Literature Review

Background: Follicular dendritic cell (FDC) sarcoma is an uncommon mesenchymal origin neoplasm derived from the abnormal proliferation and differentiation of FDCs. Epstein‒Barr virus-positive inflammatory follicular dendritic cell sarcoma (EBV+ iFDCS), which used to be known as the inflammatory pseudotumour (IPT)-like variant, occurs exclusively in the liver and spleen and has rarely been reported in the gastrointestinal tract. Case study: Here, we report a case of a 52-year-old woman with a special family history undergoing a routine physical examination. The colonoscope revealed an approximately 18 mm transverse colonic polyp, and the endoscopic polypectomy was performed. Microscopically, the excised polypoid mass was composed predominantly of inflammatory cells scattered with atypical ovoid to spindle tumor cells. Interestingly, there was a remarkable infiltration of IgG4+ cells. Immunohistochemistry showed that the tumor cells were positive for CD21, CD23 and CD35. EBV-encoded mRNA (EBER) in situ hybridization also gave positive signals. These histopathology features supported the diagnosis of EBV+ iFDCS. The patient was free of disease over 1-year follow-up. Conclusion: Identification of the potential pathogenesis sites of EBV+ iFDCS in extra-hepatosplenic regions is necessary for correct and timely diagnosis, and we consider it very meaningful to share our experience of diagnosing this tumor type. Furthermore, we summarize the clinicopathological features of EBV+ iFDCS presenting as a colon polyp after a thorough review of the literature.

High Prevalence of Common Human Viruses in Thyroid Tissue

INTRODUCTION

Evidence points to viral infections as possible triggers of autoimmune thyroid disease (AITD), but little is known about the prevalence of common viruses in the thyroid gland. Using a novel approach based on virus enrichment in multiple cell lines followed by detection of the viral genome and visualization of viral proteins, we investigated the presence of multiple human viruses in thyroid tissue from AITD patients and controls.

METHODS

Thyroid tissue was collected by core needle biopsy or during thyroid surgery from 35 patients with AITD (20 Graves' disease and 15 Hashimoto's thyroiditis). Eighteen thyroid tissue specimens from patients undergoing neck surgery for reasons other than thyroid autoimmunity served as controls. Specimens were tested for the presence of ten different viruses. Enteroviruses and human herpesvirus 6 were enriched in cell culture before detection by PCR and immunofluorescence, while the remaining viruses were detected by PCR of biopsied tissue.

RESULTS

Forty of 53 cases (75%) carried an infectious virus. Notably, 43% of all cases had a single virus, whereas 32% were coinfected by two or more virus types. An enterovirus was found in 27/53 cases (51%), human herpesvirus 6 in 16/53 cases (30%) and parvovirus B19 in 12/53 cases (22%). Epstein-Barr virus and cytomegalovirus were found in a few cases only. Of five gastroenteric virus groups examined, only one was detected in a single specimen. Virus distribution was not statistically different between AITD cases and controls.

CONCLUSION

Common human viruses are highly prevalent in the thyroid gland. This is the first study in which multiple viral agents have been explored in thyroid. It remains to be established whether the detected viruses represent causal agents, possible cofactors or simple bystanders.

IgG4-related chronic sclerosing sialadenitis in a child with recurrent parotitis: a case report

Background

IgG4-related disease (IgG4-RD) includes a group of immune-mediated diseases histologically characterized by lymphoplasmacytic infiltrate with a prevalence of IgG4-positive plasma cells, storiform fibrosis and obliterative phlebitis. Autoimmune pancreatitis, sialadenitis, dacryoadenitis and retroperitoneal fibrosis are the most frequent manifestations. IgG4-related sialadenitis usually affects submandibular glands and is very rare in children.

Here we report the case of IgG4-related sialadenitis in a six-year-old patient previously diagnosed as juvenile recurrent parotitis.

Case presentation

A six-year-old patient was referred to our Centre for left parotid swelling of 4 × 3 cm, that was tender, soft in consistency, with overlying red and warm skin. His general condition was good but he was subfebrile; general examination revealed mild enlargement of left cervical lymph nodes. In the last 2 years he had had five episodes of parotitis, diagnosed by another pediatric Center as juvenile recurrent parotitis.

On ultrasound examination the left parotid gland appeared enlarged, inhomogeneous, with a colliquative intraparotid lymph node and no evidence of sialolithiasis. Laboratory tests showed an increase of white blood cells and anti-VCA IgM and IgG positivity, with anti-EBNA e anti-EA I negativity.

The patient was initially treated with oral antibiotics, but after 10 days the parotid became fluctuating, requiring surgical biopsy and drainage. Postoperative course was regular, with complete remission under oral antibiotic and steroid therapy. Microbiological tests, including cultures for aerobic and anaerobic bacteria, mycobacteria and Bartonella, were negative.

Surprisingly, histology showed marked fibrosis and histiocytic and lymphoplasmacellular infiltrate with polyclonal plasma cells mostly expressing IgG4 immunoglobulins. Thus, the diagnosis of IgG4 related chronic sialadenitis in recurrent parotitis and recent EBV infection was made.

Conclusions

IgG4-related sialadenitis is very unusual in children. Histology plays a key role in diagnosis, considering that up to 30% of patients have normal serum IgG4 levels, as shown in our case.

The lack of previous histological data makes it impossible to attribute our patient’s previous episodes of parotitis to IgG4-RD, though it is a very consistent possibility.

Stress-Induced Epstein-Barr Virus Reactivation

Epstein-Barr virus (EBV) is typically found in a latent, asymptomatic state in immunocompetent individuals. Perturbations of the host immune system can stimulate viral reactivation. Furthermore, there are a myriad of EBV-associated illnesses including various cancers, post-transplant lymphoproliferative disease, and autoimmune conditions. A thorough understanding of this virus, and the interplay between stress and the immune system, is essential to establish effective treatment. This review will provide a summary of the interaction between both psychological and cellular stressors resulting in EBV reactivation. It will examine mechanisms by which EBV establishes and maintains latency and will conclude with a brief overview of treatments targeting EBV.

IgG4 as a Biomarker in Graves' Orbitopathy

Immunoglobulin G4-related disease (IgG4-RD) is a chronic inflammatory disorder associated with fibrosis and abundant tissue lymphoplasmacytic infiltrations. It typically affects the pancreas, the salivary glands, and the retroperitoneal space. However, it might also involve multiple other organs, including the orbit and the thyroid. Recent studies have suggested that IgG4 plays a role in the pathophysiology of autoimmune thyroid diseases. This ultimately led to the establishment of new clinical entities called IgG4-related thyroid disease and thyroid disease with an elevation of IgG4. The aim of this paper is to describe the pathophysiological, histopathological, and clinical features of Graves' Disease (GD) and Graves' Orbitopathy (GO) with elevated IgG4 levels. Multiple studies have demonstrated higher IgG4 serum concentrations in GD patients than in healthy euthyroid controls. Depending on the studied population, elevated serum IgG4 levels occur in 6.4-23% (average: 10.3%) of all patients with GD, 8.3-37.5% (average: 17.6%) of patients with GO, and 0-9.8% (average: 5.4%) of patients with GD without GO, while GO patients comprise 37.5-100% (average: 65.8%) of all GD patients with elevated IgG4 levels. Characteristic features of GD with elevated IgG4 levels include lower echogenicity of the thyroid gland on ultrasound examination, peripheral blood eosinophilia, higher prevalence of orbitopathy, and better response to antithyroid drugs with a tendency to develop hypothyroidism when compared to patients with GD and normal levels of IgG4. Typical signs of GO accompanied by increased concentration of IgG4 include younger age at diagnosis, and more severe course of the disease with a higher Clinical Activity Score (CAS).. We strongly recommend considering the diagnosis of GO with elevated IgG4 in patients with an established diagnosis of GD, elevated serum IgG4 levels, and clinical features of ophthalmic disease overlapping with those of IgG4-related orbital disease.

HLA Class I Upregulation and Antiviral Immune Responses in Graves Disease

CONTEXT

The origin of Graves disease (GD) remains elusive. However, evidence of an association between GD and viral infections is emerging. Human leukocyte antigen (HLA) class I presents viral antigens to circulating immune cells and plays a crucial role in the defense against viral infections.

OBJECTIVE

This work aimed to investigate HLA class I expression, enterovirus presence, and the viral immune response proteins signal transducer and activation of transcription 1 (STAT1) and protein kinase R (PKR) in thyroid tissue from GD patients.

METHODS

We collected thyroid tissue from core needle biopsies or surgical specimens from 48 GD patients and 24 controls. Standard immunohistochemistry was used to detect HLA class I and enteroviral capsid protein 1 (VP1) on formalin-fixed and paraffin-embedded tissue. STAT1 and PKR were examined by combined immunofluorescence staining. HLA class I expression score was the main outcome measure.

RESULTS

The HLA class I expression score, which takes both proportion and intensity of immunostaining into account, was significantly higher in GD patients (3.1 ± 3.3) than in controls (0.5 ± 0.9) (P < .001). Significantly more VP1 positive thyroid cells were found GD samples (50.1 ± 30.5%) than in controls (14.9 ± 10.5%) (P < .001). STAT1 and HLA class I were found within the same thyroid cells and PKR and VP1 were also colocalized within thyroid cells.

CONCLUSION

HLA class I is upregulated in GD and enterovirus protein is prevalent in thyroid tissue. The colocalization of HLA class I with STAT1 and VP1 with PKR indicates an antiviral tissue response. These findings support the concept of a link between viral infections and GD.

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.

Upregulation of HLA Class I and Antiviral Tissue Responses in Hashimoto's Thyroiditis

Background: Hashimoto's thyroiditis (HT) is a common autoimmune disease of unknown origin. However, viral infections have been implicated as triggers for autoimmunity. Human leukocyte antigen (HLA) class I presents antigens to circulating immune cells and plays a crucial role in the defense against viral infections. This study aimed to investigate the presence of enterovirus and HLA class I expression in one of the largest HT thyroid tissue cohorts to date. In addition, viral receptors and viral immune response proteins were examined. Methods: Thyroid tissue samples from 46 HT patients were obtained using core needle biopsy. Thyroid tissue collected during neck surgery for other reasons than thyroid autoimmunity served as controls. Standard immunohistochemistry on formalin-fixed, paraffin-embedded tissue samples were used to detect HLA class I, enteroviral capsid protein 1 (VP1), and coxsackie and adenovirus receptor (CAR) in thyroid cells. A subset of the samples was examined with combined immunofluorescence staining for signal transducer and activator of transcription 1 (STAT1) and protein kinase R (PKR). Results: Significantly more HLA class I-positive samples were found in the HT group (31 out of 46 [67.4%]) than in the control group (5 out of 24 [20.8%]) (p < 0.001). Moreover, the semiquantitative score assessing the grade of HLA class I expression was significantly higher in the HT group (3.9 ± 3.1) than in the control group (0.5 ± 0.9) (p < 0.001). In addition, STAT1 was colocalized with HLA class I, and PKR and VP1 were also found and were colocalized together. VP1 was detected in both controls and the HT samples, with slightly more VP1⁺ thyroid cells in the HT samples (20.1% ± 16.4%) than in controls (14.9% ± 10.5%). Finally, the presence of CAR in thyroid cells was confirmed. Conclusion: The current study confirmed that HLA class I hyperexpression is a defining feature of HT. Thyroid cells express CAR, thus making them susceptible to enterovirus infection. The colocalization of HLA class I with STAT1 and VP1 with PKR indicates an intracellular, antiviral host response. These findings support the concept of a firm link between viral infection and autoimmune thyroid diseases.

Serum immunoglobulin G4 in Sjögren’s syndrome: a pilot study

Immunoglobulin IgG4 plays a role in the pathogenesis of the Mikulicz disease previously considered a form of primary Sjögren's syndrome (pSS). We investigated serum levels of IgG4, total IgG, C3, and C4 serum complementary components in patients suspected of Sjögren’s syndrome. Basic laboratory and immunological tests, including IgG4 and IgG concentration, were performed on 20 healthy and 68 suspected of pSS individuals. We distinguished: group I: 48 pSS patients; group II (sicca): 20 patients with dryness without pSS. We revealed: statistical differences between groups I and II concerning hypergammaglobulinemia, ESR, RF, ANA, Ro, and La antibodies; lower IgG4 levels and IgG4/IgG ratio in group I compared to healthy individuals (p < 0.0435; 0.0035, respectively); no significant differences in the concentrations of IgG4 and IgG4/IgG ratio between sicca and control groups. significantly lower (p < 0.0002) C4 levels in group I compared to other groups; significant differences in C4 concentration and IgG4/IgG ratio between three groups (p = 0.0002 and p = 0.0090, respectively); a weak negative correlation between C4 and IgG (r =− 0.274) in the whole database; weak positive correlation between C4 and IgG4/IgG ratio (r = 0.237); a negative correlation of IgG4, IgG4/Ig ratio and C4 with focus score (r = − 0.281; r = − 0.327; r = − 0.406, respectively). IgG4 serum levels were significantly decreased compared to healthy subjects. IgG4 and C4 levels correlated with infiltrations in minor salivary glands. Hypergammaglobulinemia and decreased serum C4 component levels are typical for pSS.

Graves' disease: Epidemiology, genetic and environmental risk factors and viruses

Graves' disease (GD) is the most common cause of hyperthyroidism in developed Countries. It is more common between 30 and 60 years; 5-10 times more frequent in women. The genetic predisposition accounts for 79% of the risk for GD, while environmental factors for 21%. About 70% of genes associated with autoimmune thyroid disorders (AITD) are implicated in T-cell function. Among GD endogenous factors, estrogens, X-inactivation and microchimerism are important. Among environmental risk factors, smoking, iodine excess, selenium and vitamin D deficiency, and the occupational exposure to Agent Orange have been associated with GD. Many studies showed that HCV is associated with thyroid autoimmunity and hypothyroidism, in patients with chronic HCV hepatitis (CHC); a significant link has been shown also between HCV-related mixed cryoglobulinemia and risk for GD. Moreover, IFN-α-treated CHC patients develop GD more frequently. Novel studies are needed about possible risk factors to reduce the occurence of GD in West Countries.