Synthetic peptides as tools for diagnosis and therapeutic strategies to treat systemic lupus erythematous

Peptides Bearing Multiple Post-Translational Modifications as Antigenic Targets for Severe Rheumatoid Arthritis Patients

Rheumatoid arthritis (RA) is characterized by the presence of autoantibodies that are of paramount importance for the diagnosis and prognosis of the disease and have been implicated in its pathogenesis. Proteins resulting from post-translational modifications (PTMs) are capable of triggering autoimmune responses important for the development of RA. In this work, we investigate serum antibody reactivity in patients with an established RA against a panel of chimeric peptides derived from fibrin and filaggrin proteins and bearing from one to three PTMs (citrullination, carbamylation and acetylation) by home-designed ELISA tests (anti-AMPA autoantibodies). The role of anti-AMPAs as biomarkers linked to the presence of a more severe RA phenotype (erosive disease with radiological structural damage) and to the presence of interstitial lung disease (ILD), a severe extra-articular manifestation in RA patients entailing a high mortality, was also analyzed. In general, the association with the clinical phenotype of RA was confirmed with the different autoantibodies, and especially for IgA and IgM isotypes. The prevalence of severe joint damage was only statistically significant for the IgG isotype when working with the peptide bearing three PTMs. Furthermore, the median titers were significantly higher in patients with RA-ILD, a finding not observed for the IgG isotype when working with the single- and double-modified peptides.

Isolation, polarization, and expansion of CD4⁺ helper T cell lines and clones using magnetic beads

Autoreactive CD4⁺ helper T cells specific for a range of nucleoprotein-derived autoantigens are an important feature of systemic lupus erythematosus, driving B cell differentiation and autoantibody production and contributing to the inflammatory lesions caused by immune complex deposition. Several peptide epitopes from nucleoprotein antigens have been identified and offer a means selectively to manipulate T cell responses by skewing toward a profile of cytokines that is less pro-inflammatory. Antigen-specific T cell lines and clones can be useful in the study of helper T cell subsets because their life span is prolonged and many individual cells can be generated, allowing particular phenotypes to be studied in detail. Magnetic beads offer a robust and convenient method for the isolation, polarization, and expansion of T cells, which can be adapted for a broad range of applications.

Altered patterns of epigenetic changes in systemic lupus erythematosus and auto-antibody production: is there a link?

The prominent feature of immunological defects in systemic lupus erythematosus (SLE) is the production of autoantibodies (auto-Abs) to nuclear antigens including DNA, histones and RNP. In addition, there is growing evidence that epigenetic changes play a key role in the pathogenesis of SLE. Autoreactive CD4(+) T cells and B cells in patients with SLE have evidence of altered patterns of DNA methylation as well as post-translational modifications of histones and ribonucleoproteins (RNP). A key question that has emerged from these two characteristic features of SLE is whether the two processes are linked. New data provide support for such a link. For example, there is evidence that hypomethylated DNA is immunogenic, that anti-histone auto-Abs in patients with SLE bind epigenetic-sensitive hot spots and that epigenetically-modified RNP-derived peptides can modulate lupus disease. All in all, the available evidence indicates that a better understanding of dysregulation in epigenetics in SLE may offer opportunities to develop new biomarkers and novel therapeutic strategies.