Association of gut inflammation with increased serum IgA class Klebsiella antibody concentrations in patients with axial ankylosing spondylitis (AS): implication for diVerent aetiopathogenetic mechanisms for axial and peripheral AS?

Objectives—A role for Klebsiella pneumoniae in ankylosing spondylitis (AS) has been suggested because faecal carriage of Klebsiella and serum Klebsiella specific antibodies may be increased in this disease. This study has extended the earlier findings by comparing Klebsiella specific serum IgA class antibodies with inflammatory changes in the gut. Methods—IgA antibodies to K pneumoniae, Escherichia coli, and Proteus mirabilis in serum samples of 25 patients with AS, of eight control patients, and of 100 healthy blood donors were measured by enzyme immunoassay. Gut inflammation of the patients was studied by ileocolonoscopy. Results—Increased IgA antibody concentrations to K pneumoniae associated with gut inflammation in patients with axial form of AS. Such association was not seen in patients with peripheral form of AS. Conclusions—These findings may provide further evidence for the role of K pneumoniae in the pathogenesis of AS. However, at least some of the patients with axial AS without gut inflammation, as well as patients with peripheral AS did not have increased K pneumoniae antibody concentrations, which may be regarded as evidence against the direct role of K pneumoniae in the pathogenesis. The aetiopathogenetic mechanisms in the axial and peripheral form of AS may be diVerent. (Ann Rheum Dis 1997;56:180–183) The aetiology of ankylosing spondylitis (AS) is still unknown but the Gram negative microorganism Klebsiella pneumoniae has been suggested to play an important part in the pathogenesis, although this association between Klebsiella and AS is still a subject of controversy. A high frequency of inflammatory changes 7 and increased permeability of the gut, as well as high serum concentrations of total IgA and secretory IgA support the role of gut and mucosal immune defence mechanisms. Furthermore, AS can be divided into two forms: (a) patients who have pure axial form of the disease and (b) patients with not only axial, but also peripheral joint arthritides. There have been suggestions for diVerent aetiopathogenetic mechanisms for these two forms. For example, ileocolonoscopic diVerences have been reported between patients with axial and peripheral form of AS. 7 In addition, sulphasalazine, a drug used to treat inflammatory bowel disease, seems to be especially eVective in patients with the peripheral type of AS. We have extended the earlier findings by comparing Klebsiella specific serum IgA class antibodies with inflammatory changes in the gut in patients with axial and peripheral types of AS. Methods Twenty five patients with AS (only axial form, 14; also peripheral arthritides, 11; with mean (SD) duration of disease 7.1 (4.9) and 6.3 (5.3) years, respectively) and, as controls, eight patients with miscellaneous rheumatic diseases (rheumatoid arthritis, 3; low back pain, 3; fibromyalgia, 1; psoriatic arthritis, 1), and 100 healthy blood donors were studied. In patients with axial and peripheral AS the mean (range) erythrocyte sedimentation rates (ESR) were 36 (5-80) and 47 (6-86) mm/h, respectively; the corresponding figures for C reactive protein (CRP) were 27 (0-103) and 41 (0-160). The ESR and CRP values for control patients were 39 (2-88) and 18 (2-57). Of the AS patients all 23 tested were HLA-B27 positive; of the control patients three were HLA-B27 positive. Eleven (79%) of the patients with axial AS, nine (82%) of the patients with peripheral AS, and six (75%) of the control patients received non-steroidal anti-inflammatory drugs within one month before the ileocolonoscopy. Ileocolonoscopies were performed for patients as described earlier for a clinical indication of silent gut inflammation. Patients with previously diagnosed inflammatory bowel disease or with chronic diarrhoea were excluded from the study. Of the AS patients, eight were identified as having inflammation in ileum (four patients with axial and four with peripheral form of AS), nine in colon (three with axial and six with peripheral form of AS), and 14 in ileum or in colon (six with axial and eight with peripheral form of AS). Thirteen Annals of the Rheumatic Diseases 1997;56:180–183 180 National Public Health Institute, Department in Turku, Turku, Finland O Mäki-Ikola K Granfors Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland U Turunen M Leirisalo-Repo Correspondence to: Dr O Mäki-Ikola, National Public Health Institute, Department in Turku, Kiinamyllynkatu 13, FIN-20520 Turku, Finland. Accepted for publication 9 December 1996 group.bmj.com on April 15, 2017 Published by http://ard.bmj.com/ Downloaded from