EBV and systemic lupus erythematosus: a new perspective

Genetic susceptibility to polyI:C-induced IFNalpha/beta-dependent accelerated disease in lupus-prone mice

Systemic lupus erythematosus (SLE) is an autoimmune disease of unknown etiology. Associations between viral infections and the onset of SLE have been suggested, and recent studies have provided evidence that type I interferons (IFNalpha/beta) might play a role in the SLE disease process. Viruses and interferons have also been implicated in mouse models of SLE. We generated a model of accelerated proteinuria, in which lupus-prone mice were injected repeatedly with polyinosinic:polycytidylic acid (polyI:C), mimicking exposure to virus-derived double stranded RNA (dsRNA), leading to the production of IFNalpha/beta. PolyI:C-treated (B6.Nba2 x NZW)F1 and (B6 x NZW)F1 hybrid mice developed significantly increased levels of anti-dsDNA autoantibodies, characteristic of lupus. Most significantly, polyI:C-treated (B6.Nba2 x NZW)F1 mice, but not (B6 x NZW)F1 or parental strains, developed lupus-like nephritis in an accelerated fashion, which was dependent on IFNalpha/beta and associated with elevated deposition of total IgG, IgG2a and complement factor C3 in the glomerular capillary walls. These data suggest that reagents, which increase the levels of endogenous IFNalpha/beta (directly or indirectly), can accelerate the course of lupus-like nephritis, the development of which is dependent on the presence of both NZW- and Nba2-encoded genes.

[The role of cell stress in systemic autoimmune disease]

Anti-DNA antibody is a characteristic feature of systemic lupus erythematosus (SLE) and plays an important role in pathogenesis of lupus nephritis. However, the mechanism of anti-DNA antibody production, which may directly link to the etiology of SLE, remains uncertain. Mammalian DNA alone is not immunogenic. However, some anti-DNA antibodies cross-react with self antigens, and immunization of mice with a certain peptide could induce anti-DNA antibodies. These facts raise a question as to whether an antigenic trigger of anti-DNA antibodies production is DNA itself. Therefore, molecular mimicry of DNA by non DNA antigen is a possibility for the initial production of anti-DNA antibodies. We found that the human monoclonal nephritogenic anti-DNA antibody, O-81, specifically bound to an endoplasmic reticulum stress response protein, Herp. This suggests that lupus nephritogenic anti-DNA antibody cross-react with Herp and an epitope on Herp mimics DNA. Each time cells receive stress (for example, viral infection), the synthesis of Herp protein is induced. If the epitope is immunogenic, repetitive cell stress can be a trigger of anti-DNA antibodies production.

Could 2'5'-oligoadenylate synthetase isoforms be biomarkers to differentiate between disease flare and infection in lupus patients? A pilot study

2'5'-Oligoadenylate synthetase (OAS) was shown to be related to systemic lupus erythematosus (SLE) 20 years ago, and was rediscovered to be involved in type I interferon pathway in SLE by several microarray gene expression studies recently. The goal of this study was to investigate OAS isoform expressions in lupus patients, to evaluate whether they could become biomarkers to differentiate between disease flare and infection. Fifty-four SLE patients presented with fever or systemic inflammatory syndrome, or both, were enrolled. Gene expressions of OAS1, OAS2, and OASL were studied by using real time PCR in active SLE (SLEDAI >or=9, n=29) and in those complicated with infections (n=25). The latter group was composed of 19 patients with invasive bacterial infections, and six patients with viral infections. C reactive protein (CRP) and other clinical parameters were also measured. Twenty-nine healthy individuals made up a normal control group. The mRNA expressions of OAS1, OAS2, and OASL were higher in patients with lupus flares than those with infections (p<0.03), or normal controls (p<0.001). SLE complicated with infections have higher OAS1 expression level (P=0.002), lower OASL (P=0.004), and equivalent OAS2 (P=0.135), when compared with those of normal controls. OASL expression level was negatively correlated with infection in lupus by logistic regression analysis (p=0.008). Area under the receiver operating characteristic curve for the prediction of infection was 0.92 (p<0.0001) for OASL, and 0.77 (p=0.007) for CRP. Therefore, our preliminary data suggest that the pattern of OAS isoform expressions, OASL in particular, may provide useful information in differentiating disease flares from certain infections in SLE.

Infections and SLE

Viral and bacterial infections may serve as an environmental trigger for the development or exacerbation of systemic lupus erythematosus (SLE) in the genetically predetermined individual. In addition, SLE patients are more prone to develop common (pneumonia, urinary tract infection, cellulitis, sepsis), chronic (tuberculosis), and opportunistic infections possibly due to inherit genetic and immunologic defects (complement deficiencies, mannose-binding lectin [MBL] polymorphisms, elevated Fcgamma III and GM-CSF levels, osteopontion polymorphism), but also due to the broad spectrum immunosuppressive agents that are part of therapy for severe manifestations of the disease. Hence, SLE patients are considered a high-risk population, where identification and treatment of chronic infections such as tuberculosis, hepatitis B or human immunodeficiency virus, are important prior to the institution of immunosuppression so as to prevent reactivation or exacerbation of the infection. Infections in SLE patients remain a source of morbidity and mortality. A caveat often encountered is to distinguish between a lupus flare and an acute infection; in such cases parameters including elevated CRP (and adhesion molecules) may aid in the diagnosis of infection. Recent research has provided convincing evidence that EBV infection may play a major role not only in molecular mimicry but also in aberrations of B cells and apoptosis leading to a state of perpetual heightened immune response in SLE.

Epstein-Barr virus and rheumatoid arthritis: is there a link?

Rheumatoid arthritis is a systemic autoimmune disease characterized by chronic, destructive, debilitating arthritis. Its etiology is unknown; it is presumed that environmental factors trigger development in the genetically predisposed. Epstein–Barr virus, a nearly ubiquitous virus in the human population, has generated great interest as a potential trigger. This virus stimulates polyclonal lymphocyte expansion and persists within B lymphocytes for the host's life, inhibited from reactivating by the immune response. In latent and replicating forms, it has immunomodulating actions that could play a role in the development of this autoimmune disease. The evidence linking Epstein–Barr virus and rheumatoid arthritis is reviewed.

Autoimmune mechanisms in children with systemic lupus erythematosus

Although the pathogenesis of SLE remains poorly understood, there is consensus that it involves a combination of genetic, hormonal, and environmental factors. New technologies applied to genomic and gene expression studies have revealed novel gene mutations and cytokine alterations in this disease. Recently, advances in monoclonal antibodies and recombinant DNA technology have resulted in the development of new drugs to arrest disease progression and restore physiologic immune responses without major side effects. Clinical trials to test several of these novel therapies are currently underway.