The development of autoimmune diseases such as Systemic Lupus Erythematosus (SLE) is associated with both genetic and environmental factors. It has been shown that Epstein-Barr virus (EBV) is able to alter the immune response towards self-antigens and may enhance risk of autoimmune diseases such as systemic lupus erythematosus (SLE) in genetically predisposed individuals. We have previously shown in an Italian cohort that, anti-EBV-VCA and EA IgG titers were significantly higher in ANA-positive patients in comparison to the controls as well as in those ANA-positive patients that showed a concomitant ENA positivity. Interestingly, an elevated anti-EBNA-1 IgG titer was found in a group of patients who had anti SSA/Ro antibodies. Anti-VCA IgM Abs were more frequently found in those patients with a very high titer of ANA ; moreover detection of anti-VCA IgM/IgG in absence of anti-EBNA-1 IgG was more frequent in the patient than in the control group.
MicroRNAs (miRNAs) are small noncoding regulatory RNAs which bind to 3¿ UTR of target mRNA to regulate gene expression post-transcriptionally. Their stability, small size and ability to circulate in blood makes them ideal diagnostic and prognostic biomarkers. Lytic reactivation of EBV is associated with SLE but if viral miRNAs are altered in the process and if they can be found in circulation is completely unknown. The present proposal will test both cellular and viral miRNAs in serum of a large cohort of Italian SLE patients and healthy controls. The results obtained from this proposal will provide, for the first time, novel viral miRNA based diagnostic and prognostic markers for SLE.
Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterized by the production of an array of pathogenic autoantibodies against nuclear self-antigens, including high-affinity anti-dsDNA, anti-histone, and anti-ribonucleoprotein (RNP) autoantibodies, which mediate widespread tissue and organ injury (1). These autoantibodies are mutated and class-switched, mainly to IgG, and are secreted by a large number of plasma cells, indicating that immunoglobulin (Ig) somatic hypermutation (SHM), class switch DNA recombination (CSR) and plasma cell differentiation are important in their generation
Systematic exploration of miRNAs expression patterns has proven successful in classifying human cancer [87]. MiRNA expression profiling studies in SLE patients or SLE mouse models are anticipated to generate some unique miRNA signatures that are associated with disease activity and severity, providing novel insights into pathogenic mechanism and contributing to development of novel biomarkers for SLE.
Presently available SLE diagnostic markers include evaluation of the anti-Ana and ENA antibodies. The diagnostic procedure is both laborious, subject to false positive and time consuming. The economic burden of these expensive diagnostic tests is also considerable.
There are a few studies which have addressed the role of cellular miRNAs in SLE. However, the role of viral miRNAs in pathogenesis of SLE has never been addressed before. Furthermore, this proposal is unique because for the first time, viral miRNAs will be tested in sera derived from SLE patients. AS for cellular miRNAs
alteration in SLE patients, miR-146 downregulation has been noted at cellular level but the expression of this miRNA has not been evaluated in sera. Furthermore, in view of the fact that our previous studies have clearly indicated how EBNA2, a viral protein, downregulates miR-146a, we will test expression of EBNA2 by evaluating antibody titers against this viral protein in different phases of the disease in selected patients.
In summary, for the first time ever, novel viral miRNA based diagnostic markers for SLE will be developed by:
1: Identification of viral miRNAs in SLE pathogenesis by analysis of circulating miRNAs.
2: understanding the role of miR-146a in pathogenesis of SLE in sera.
3: Establishment of immortalized LCLs from SLE patients which carry endogenous EBV genome to identify disease specific viral strain and polymorphisms in viral miRNA encoding genes.