Antibodies to Epstein—Barr Viral Antigens in Early Rheumatoid Arthritis

Systematic review and meta-analysis of the sero-epidemiological association between Epstein-Barr virus and rheumatoid arthritis

Introduction

Infection with Epstein-Barr virus (EBV) has been suggested to contribute to the pathogenesis of autoimmune diseases, including rheumatoid arthritis (RA). We sought to determine whether prior infection with the virus occurs more frequently in patients with RA compared to controls.

Methods

We performed a systematic review and meta-analyses of studies that reported the prevalence of anti-EBV antibodies in the sera of cases with RA and controls by searching Medline and Embase databases from 1946 to 2014, with no language restriction. Mantel-Haenszel odds ratios for the detection of anti-EBV antibodies were calculated, and meta-analyses conducted. Quality assessments were performed using a modified version of the Newcastle-Ottawa scale.

Results

Twenty-three studies were included. Quality assessment found most studies reported acceptable selection criteria but poor descriptions of how cases and controls were recruited. When all studies were included, there was a statistically significant higher seroprevalence of anti-VCA IgG in patients with RA compared to controls with an odds ratio (OR) of 1.61 (95 % confidence interval (CI) 1.05–2.46, p = 0.03), which is a similar-sized summary OR to that reported for systemic lupus erythematosus (SLE). However, when studies were restricted to those reporting more plausible levels of exposure to EBV in the control groups, no significant association was apparent, OR 1.47 (95 % CI 0.88–2.46, p = 0.14). Using anti-EBNA 1 or anti-EA IgG as markers of previous infection also did not yield significant associations (OR 1.05, 95 % CI 0.68–1.61, p = 0.82; OR 2.2, 95 % CI 0.86–5.65, p = 0.10 respectively).

Conclusions

Overall, these findings do not demonstrate an association between EBV seroprevalence and RA and therefore do not support the hypothesis that prior infection with EBV predisposes to the development of RA. This contrasts with meta-analyses that indicate EBV infection is associated with multiple sclerosis and SLE.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0755-6) contains supplementary material, which is available to authorized users.

Association analysis of anti-Epstein-Barr nuclear antigen-1 antibodies, anti-cyclic citrullinated peptide antibodies, the shared epitope and smoking status in Brazilian patients with rheumatoid arthritis

INTRODUCTION

Epstein-Barr virus exposure appears to be an environmental trigger for rheumatoid arthritis that interacts with other risk factors. Relationships among anti-cyclic citrullinated peptide antibodies, the shared epitope, and smoking status have been observed in patients with rheumatoid arthritis from different populations.

OBJECTIVE

To perform an association analysis of anti-Epstein-Barr nuclear antigen-1 antibodies, anti-cyclic citrullinated peptide antibodies, the shared epitope, and smoking status in Brazilian patients with rheumatoid arthritis.

METHODS

In a case-control study, 140 rheumatoid arthritis patients and 143 healthy volunteers who were matched for age, sex, and ethnicity were recruited. Anti-Epstein-Barr nuclear antigen-1 antibodies and anti-cyclic citrullinated peptide antibodies were examined using an enzyme-linked immunosorbent assay, and shared epitope alleles were identified by genotyping. Smoking information was collected from all subjects. A comparative analysis of anti-Epstein-Barr nuclear antigen-1 antibodies, anti-cyclic citrullinated peptide antibodies, the shared epitope, and smoking status was performed in the patient group. Logistic regression analysis models were used to analyze the risk of rheumatoid arthritis.

RESULTS

Anti-Epstein-Barr nuclear antigen-1 antibodies were not associated with anti-cyclic citrullinated peptide antibodies, shared epitope alleles, or smoking status. Anti-cyclic citrullinated peptide antibody positivity was significantly higher in smoking patients with shared epitope alleles (OR = 3.82). In a multivariate logistic regression analysis using stepwise selection, only anti-cyclic citrullinated peptide antibodies were found to be independently associated with rheumatoid arthritis (OR = 247.9).

CONCLUSION

Anti-Epstein-Barr nuclear antigen-1 antibodies did not increase the risk of rheumatoid arthritis and were not associated with the rheumatoid arthritis risk factors studied. Smoking and shared epitope alleles were correlated with anti-cyclic citrullinated peptide-antibody-positive rheumatoid arthritis. Of the risk factors, only anticyclic citrullinated peptides antibodies were independently associated with rheumatoid arthritis susceptibility.

Pathophysiological links between rheumatoid arthritis and the Epstein–Barr virus: An update

Numerous associations have been documented between the Epstein-Barr virus (EBV) and rheumatoid arthritis (RA). Thus, anti-EBV antibody titers are higher in RA patients than in healthy controls. Lymphocytes from RA patients show impaired responses to EBV. Several EBV antigens share similarities with self antigens; more specifically, the glycine/alanine repeats in EBNA-1 resemble synovial proteins and the EBV gp110 glycoprotein contains a copy of the shared epitope. Cell-mediated responses to EBV replicative cycle proteins and to gp110 have been documented in joint fluid from RA patients. In situ hybridization and PCR techniques have identified EBV antigens and genetic material within the rheumatoid synovium, albeit with variable yields. The EBV burden in peripheral blood mononuclear cells is higher in RA patients than in controls. EBNA-1 can undergo citrullination, and the EBV can induce antibodies to citrullinated peptides. RA patients are at increased risk for lymphoma, including EBV-associated lymphoma. Despite these multiple and complex links between EBV and RA, proof of a causal association is lacking. EBV infection may contribute indirectly to the pathophysiology of RA by impairing immune control of EBV replication, causing increased exposure to EBV antigens and, thereby, chronic inflammation. The effect of biotherapies for RA on EBV-host relations needs to be investigated.

EBV Gene Expression Not Altered in Rheumatoid Synovia Despite the Presence of EBV Antigen-Specific T Cell Clones

T cells infiltrating the rheumatoid arthritis (RA) joint are oligoclonal, implicating an Ag-driven process, but the putative joint-specific Ags remain elusive. Here we examine expression of selected EBV genes in RA synovia and find no abnormal expression in RA. DNA of CMV and EBV was detectable by PCR in the synovial tissue of RA. RNA of several latent and lytic EBV genes was also detectable. However, there were no differences in EBV gene expression in synovial tissues or peripheral blood when comparing RA with osteoarthritis, Gulf War syndrome, and other disease controls. RA synovia with highly expanded CD8 T cell clones reactive with defined EBV peptide Ags presented by HLA class I alleles lacked evidence of abnormal mRNA expression for the relevant EBV Ag (BZLF1) or lacked amplifiable mRNA (BMLF1). Thus, local production of EBV Ags in synovial tissues may not be the cause of the accumulation of T cell clones specific for these Ags. Instead, APCs loaded with processed EBV peptides may migrate to the synovium. Alternatively, EBV-specific T cell clones may be generated in other tissues and then migrate to synovia, perhaps due to cross-reactive joint-specific Ags or because of expression of homing receptors.

Detection of herpesviruses by polymerase chain reaction in lymphocytes from patients with rheumatoid arthritis

OBJECTIVE

To investigate the occurrence of herpesviruses, including Epstein-Barr virus (EBV), herpes simplex viruses types 1 and 2 (HSV-1; HSV-2), and human herpesvirus 6 (HHV-6), in lymphocytes from patients with rheumatoid arthritis (RA) of less than 1 year's duration.

METHODS

The polymerase chain reaction was applied to cells isolated from synovial fluid and peripheral blood. Indirect immunofluorescence and enzyme immunoassay techniques were used to detect antibodies against EBV and HSV, respectively.

RESULTS

EBV DNA was present in synovial fluid lymphocytes from 19% (7 of 37) of the RA patients and 33% (5 of 15) of the patients with reactive arthritis (ReA). Peripheral blood lymphocytes harbored EBV DNA in 39% of the RA patients, 39% of the ReA patients, 27% of the patients with other arthropathies, and in 31% of the healthy control subjects. HSV-1, HSV-2, and HHV-6 viral DNA was not detected in cells from the synovial fluid or peripheral blood.

CONCLUSION

Our findings do not support the participation of EBV, HSV-1, HSV-2, or HHV-6 in the pathogenesis of RA. A role for the highly prevalent EBV cannot be excluded, however, since potential contributions may become manifest only when other necessary factors are involved. RA pathogenesis caused by an overproduction of the EBV virus is nevertheless highly unlikely.

Antibodies in rheumatoid synovial fluids bind to a restricted series of protein antigens in rheumatoid synovial tissue

OBJECTIVE

By searching the synovial fluid of patients with rheumatoid arthritis (RA) for antibodies that react to protein antigens in synovial tissue, we sought to identify putative antigens present in RA synovial tissue that might drive the pathologic immune response believed to be responsible for the joint inflammation.

METHODS

Synovial tissue was homogenized in sodium dodecyl sulfate polyacrylamide gel buffer, electrophoresed, and analyzed by immunoblotting.

RESULTS

Antibodies from synovial fluids of patients with RA bound to several proteins in rheumatoid synovial tissues, including a series of low (27.5-, 29-, and 30-kd), middle (43- and 53-kd), and high (140-, 164-, and 182-kd) molecular weight proteins. Most of these antigens were also detected in normal synovial tissue, and the high molecular weight proteins were also present in normal dermal, muscle, and liver tissues. The low and middle molecular weight proteins were detected in some, but not all, of the other normal tissues and in Jurkat cell lysates. Antibodies to the low and high series of proteins were present in all rheumatoid synovial fluids tested, but were generally absent from synovial fluids from patients with other arthritic diseases.

CONCLUSION

These results show that antibodies in synovial fluids consistently react to several proteins in RA and normal synovial tissues. These antigens are possibly the same antigens provoking the T cell response in RA; therefore, understanding the mechanism of the immune response against these proteins will likely lead to important insight into the etiology of RA.

Epstein-Barr virus and human autoimmune diseases: possibilities and pitfalls

Epidemiologic studies suggest that human autoimmune disease involves both genetic and environmental components. Although a great deal has been learned about genetic components (i.e. histocompatibility antigens), little is known about the environmental factors. Because of its ubiquitous nature and ability to stimulate lymphoid responses, Epstein-Barr virus (EBV) has been examined as a potential candidate, particularly in rheumatoid arthritis and systemic lupus erythematosus. No convincing evidence has been produced that it plays a primary etiologic role in these disorders. Nevertheless, EBV or a related herpesvirus may play an indirect role in perpetuating the disorder or in the development of extra-articular manifestations such as Sjögren's syndrome (an autoimmune disorder involving the salivary glands). Current data indicates increased EBV reactivation in some patients with autoimmune diseases, as evidenced by increased viral DNA in their saliva and increased number of circulating B-cells containing EBV in their blood. These patients also have modestly elevated anti-EBV antibody titers and altered antiviral T-cell responses, as measured by the ability to prevent outgrowth of autologous EBV infected B-cells. However, the relevance of these 'abnormalities' to pathogenesis remains unknown. It is hoped that new techniques such as polymerase chain reaction will provide new insights into these questions by allowing detection of viral DNA from tissue biopsies obtained early in the course of disease and by providing a method to identify viral isolates that do not grow well in vitro.

Immunocytological studies of Epstein-Barr viral antigen and antibody in rheumatoid synovial fluids

Evidence for intra-articular immunity to Epstein-Barr virus (EBV) was sought in synovial fluids (SF) and SF phagocytes derived from patients with and without rheumatoid arthritis (RA). Antibody titres to EBV were not significantly different in SF of 32 RA and 25 non-RA patients. Whereas the majority of RA patients (69%) showed Ig-containing complexes (IC) in SF phagocytes, fluorescent antibody staining of these by anti-EBV serum was negative except with 6 RA patients. Extended analysis of the SF phagocytes of the latter, however, showed no EBV specificity in their IC, suggesting that these represented non-specific "pseudo-IC'. These studies do not support a role for EBV-containing IC in the propagation of rheumatoid synovitis and demonstrate that not all immunofluorescent inclusions in RA phagocytes (ragocytes) represent immune complexes.

Antibodies to Epstein-Barr virus associated antigens in Pima Indians with and without rheumatoid arthritis

We investigated anti-rheumatoid arthritis-associated nuclear antigens (RANA) and other anti-Epstein-Barr virus (EBV) antibodies in a uniquely controlled study in female Pima Indians of Arizona, an RA prone population. Four groups of age and sex-matched individuals were formulated: (1) individuals positive for rheumatoid factor (RF) who had clinical evidence of rheumatoid arthritis (RA); (2) individuals seropositive for RF, but without arthritis; (3) individuals seronegative for RF, but with various kinds of arthritis; (4) those seronegative without arthritis. The mean anti-RANA in the seropositive RA group was significantly above those of the other groups but the anti-VCA and anti-EBNA titers did not differ. The anti-RANA was shown to be independent of RF. Comparing the Pima Indians to Caucasians in La Jolla, we found the mean anti-RANA titers of the Pimas to be significantly higher than those of the Caucasians. This study thus establishes clearly that elevated anti-RANA titers are characteristics of this American Indian group, just as they are of Caucasian groups. The elevated anti-RANA titers in RA patients may represent a unique hyperresponsiveness to this antigen, since there is no consistency in the reported levels of antibodies to other EBV-related antigens.