Background The association between Seronegative spondyloarthropathies(SpA), especially ankylosing spondylitis (AS), and inflammatory bowel disease (IBD) has been previously reported. Anti-Saccharomyces cerevisiae antibodies (ASCA) and perinuclear antineutrophil cytoplasmic antibodies (pANCA), are serological markers for IBD, but their association with gut inflammation is controversial in AS, and has not been studied in rheumatoid arthritis (RA).

Objectives To investigate the prevalence of IBD serologies in AS and RA, and their relation to clinical manifestations, ileocolonoscopic and histologic findings.

Methods We included 40 consecutive AS patients fulfilling the 1984 modified New York criteria, 20 RA in addition to 20 healthy age and sex matched as a second control for the ASCA and ANCA serologies. Ileocolonoscopy and histologic examination of biopsies were performed in all patients. ASCA IgA and IgG (by ELIZA) and ANCA (by indirect immune-florescence) were determined in all patients and controls.

Results ASCA (IgA and/or IgG) was positive in 37.5% of AS, 20% of RA and 0% of controls. pANCA was positive in 25% of AS, 30% of RA and 0% of controls.

Macroscopic gut inflammation was revealed in 90% of AS. Whereas, histologic lesions were present in 95%, with chronic ileocolitis in 40% and crhon’s disease (CD) like lesions in 55%. These lesions were more frequent in HLA-B27 negative than B27 positive AS patients. In RA, no macroscopic lesions were detected, while microscopic lesions were detected in all patients, with 70% showing chronic ileocolitis and 30% showing CD-like lesions.

All ASCA (IgA and/or IgG) positive AS and RA patients had microscopic gut inflammation, with higher frequency of CD-like lesions than non-specific ileocolitis. Similarly, all pANCA positive AS and RA had microscopic gut lesions. There was no association between these seromarkers and the presence of clinical manifestations suggestive of IBD.

Conclusions The finding of association between gut inflammation and IBD-specific antibodies (ASCA and pANCA) in both AS and RA, confirms their use independently as markers of underlying subclinical bowel inflammation regardless of the primary disease.

The more frequent presence of CD-like lesions in B-27 negative AS supports the assumption that these cases may represent an early stage of IBD.

The detection of histologic gut inflammation and CD-like lesions in AS as well as in RA is a further confirmation of the link between the gut and inflammatory rheumatic diseases which may be related to their etiopathogenesis.

Disclosure of Interest None Declared