Peptide-based immunoassays: a challenge for high performance diagnostics & prognostics of autoimmune diseases

Autoimmune diseases are considered now as a plague. In fact some autoimmune diseases previously considered rare are actually increasing their frequency because of an earlier diagnosis (e.g. celiac disease). Possibly also an environmental factor (bacterial and/or viral infection) should contribute to autoimmune diseases. The idea we have been investigating for years and more recently proposed by others, is that aberrant post-translational modifi cations, i.e. glycosylation, deimination etc., create neoantigens triggering autoantibodies. This could explain why proteins (both recombinant and isolated), components of target organs or tissues, are failing. Anyway, it is evident that one single biomarker will never enable to reach successful diagnostic & prognostic tools. On the contrary, synthetic peptides specifi cally modifi ed (with sugars, citrulline, lipoyl moieties, etc.) are interesting tools to fi shing out of patients’ sera these autoantibodies. We have recently reported that this can be effi ciently done following a “Chemical Reverse Approach” 1.. We successfully applied this strategy in the development of the fi rst Multiple Sclerosis Antigenic Probe [MSAP]: an N-glucosylated peptide characterised by a -hairpin structure exposing at the best the minimal epitope Asn(-Glc) involved in antibody recognition (2). A wider application of our SAP is obtained by its citrullinatation and/or galactosylation (3) useful for rheumatoid arthritis or lipoylation for investigating primary biliary cirrhosis.