Background Accumulating evidence shows that humoral autoimmunity might play an important role in cardiovascular disease (CVD). Some autoantibodies, present in patients with antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE), may possibly represent emerging CV risk factors. MicroRNAs markedly affect the immune system and seem to have a relevant role in the pathogenesis of both CVD and autoimmune diseases. Yet, no study has analyzed the involvement of miRNAs in atherothrombotic disease induced by autoantibodies in APS and SLE patients.
Objectives To evaluate the effect of specific autoantibodies of APS (anti-phospholipid antibodies, APLs) and SLE (anti-ds-DNA) in the regulation of miRNAs related to pro-atherothrombotic proteins in both autoimmune diseases.
Methods Monocytes and neutrophils isolated from healthy donors were treated in vitro with anticardiolipin IgG isotype antibodies (ACA-IgG) and anti-dsDNA antibodies purified from SLE and APS patients' serum, respectively, or with IgG from healthy donors (IgG -NHS). Levels of various microRNAs associated with inflammation, oxidative stress and atherosclerosis (miR-124a, -125a, -125b, -146a, -155 and -222) and their target molecules were determined by RT-PCR. Expression of key proteins involved in miRNAs biogenesis process (Drosha, Dicer, Ago-1, Ago-2 and 2, and Xpo-5) were analyzed at gene and protein levels. Transfections were also performed with precursors of miRNAs altered by the treatment with these autoantibodies to identify key target proteins in both pathologies.
Results The expression levels of all miRNAs analyzed were significantly reduced in neutrophils treated with ACA-IgG and anti-dsDNA compared to those treated with IgG-NHS. Both autoantibodies also caused a significant decrease in the expression of exportin-5 and DICER in this cell type. In monocytes, treatment with ACA-IgG and anti-dsDNA promoted a significant reduction in the levels of miR-124a and miR-125a, as well as increased expression of miR-146a and miR-155. Monocyte transfections with pre-miR-124a and miR-125a, either separately or simultaneously, caused a reduction in the expression of target molecules related to the atherothrombotic process in APS and SLE (ie MCP-1, IL-6, IL6R, IL-8, ERK, STAT-3, p38 MAPK and peroxides).
Conclusions 1) The anti-cardiolipin and anti-dsDNA antibodies modify the expression of microRNAs regulators of proinflammatory and prothrombotic molecules in neutrophils and monocytes, as well as of genes involved in their biogenesis. 2) Transfection with pre-miRNAs 124a and -125a promotes a reduction in the expression of molecules associated with atherothrombosis in SLE and APS.
Taken together, the results indicate that autoantibodies could act as direct regulators of atherothrombotic process in APS and SLE, through epigenetic mechanisms such as modulation of microRNAs.
Acknowledgements Supported by CTS-7940, PI12/01511, SER.
Disclosure of Interest None declared