Saccharomyces cerevisiae is a common yeast used in the food industry. IgG and IgA antibodies against the phosphopeptidomannan of the S. cerevisiae cell wall (ASCA) are a well known marker of disease severity in Crohn's disease. Moreover, a number of studies assessed ASCA in several systemic and organ-specific autoimmune diseases postulating molecular mimicry as a possible link between ASCA and autoimmunity. However, since they have never been tested in primary Sjögren's syndrome (pSS), the purpose of this study was to investigate these antibodies in a large cohort of pSS patients, compared to healthy donors (HD), and their significance as potentially helpful biomarker in a clinical setting.
ASCA IgG+IgA were assessed with ASCA screen dot for Blue Diver instrument (Alphadia sa/nv, Belgium). The comparison between the aminoacid sequence of mannan of S. cerevisiae and well characterised auto-antigens peculiar to pSS (52kD and 60kD Ro/SSA, La/SSB) was performed with the Basic Local Alignment Search Tool (BLAST).
The prevalence of ASCA in our pSS cohort was 4.8%. We also reported that the ASCA target protein has a high similarity with Ro60/SSA protein further supporting the molecular mimicry hypothesis. Finally, we observed that ASCA positivity is associated with pSS specific clinical and serological features. ASCA+ pSS patients displayed a triple combination of circulating anti-Ro52/SSA, anti-Ro60/SSA and anti-La/SSB antibodies, associated with low complement and cutaneous involvement.
Our data suggest a possible pathogenic/prognostic significance of ASCA in pSS.