CD, AK, and uSpA share serum reactivity to yeast

An immunological study has provided more evidence that vertebral disease and coeliac disease (CD) are related. For the first time patients with ankylosing spondylitis (AS) and undifferentiated spondyloarthropathy (uSpA) have been shown to share a serum marker for CD.

The study compared serum IgA and IgG antibodies to Saccharomyces cerevisciae in patients with joint diseases and in patients with CD, with rheumatoid arthritis (RA) patients acting as controls for general inflammation, and with healthy controls. Serum IgA antibody was significantly raised in patients with AK and uSpA versus both controls, but not as high as in CD. These high antibody titres persisted over 12 weeks in a subgroup of 19 patients tested. Both IgG and IgA antibodies were significantly higher in CD than normal or RA controls. IgA antibody and bowel inflammation or intestinal lymphoid follicles were not related in AS or uSpA, but large prospective studies should tell whether high IgA leads eventually to CD, say the authors.

The study looked at 108 patients with joint disease: 43 with AS, 20 uSpA, and 45 PsA; 26 patients with CD; 56 patients with RA; and 45 healthy controls.

Evidence of a link between vertebral disease and CD has been mounting. Over two thirds of patients with joint disease have subclinical bowel inflammation and some develop CD. Their gut lining has more lymphoid follicles, regardless of its inflammatory state. Conversely, over a third of patients with CD has joint disease and meets criteria for SpA. So a common serum marker seemed likely.