Silicon-based peptide microarrays for epitope mapping of serum autoantibodies from patients with systemic lupus erythematosus with single-amino acid resolution (P4030)

Abstract

Abstract We have developed a silicon-based peptide microarray with >5,700 features, corresponding to 891 unique peptides derived from the U1-70 protein, a well-known target of autoantibodies in systemic lupus erythematosus (SLE). U1-70 is a component of the U1-small nuclear ribonucleoprotein (U1-snRNP) complex, which is one of five snRNPs that comprise the spliceosome. The peptides on the microarray represent every possible overlapping peptide, up to 21 amino acids in length, spanning amino acids 110 to 170 within the U1-70 RNA binding domain. The microarray includes regions of U1-70 targeted by SLE patient autoantibodies, although the precise epitopes are not known. Additionally, the region includes a peptide (131-150) that our lab recently identified as a target of autoreactive CD4+ T cells. We have validated the microarray using commercial anti-U1-70 antibodies, and have shown that this array is capable of sensitive and specific determination of their minimal epitopes. We went on to evaluate a cohort of SLE (n=24) patients and identified two minimal reactive epitopes, peptides 116-121 (n=3) and 143-148 (n=1), of their U1-70 autoantibodies. Further analysis of a larger SLE cohort (n=80) by peptide ELISA revealed additional patients with reactivity to peptides 116-121 (1/80) and 143-148 (5/80). Currently we are correlating reactivity to these peptides with patient clinical information in an effort to better understand the development and function of anti-U1-70 autoantibodies in SLE.