AB0143 PERIODONTITIS AND SALIVA ANTIBODIES TO CITRULLINATED PEPTIDES IN RHEUMATOID ARTHRITIS
Authors: Anna Svärd, Stefan Renvert, Johan Berglund, Maria Söderlin
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Mucosal immunity, involving antibodies against citrullinated peptides (ACPA), is a prevailing hypothesis concerning the pathogenesis of rheumatoid arthritis (RA). The oral mucosa is a possible site that is involved. Several epidemiological studies have found an association between RA and periodontitis, and periodontal inflammation has been suggested as a possible pathogenic factor. In established RA, periodontitis has been associated with ACPA positivity (1) although a recent large study (2) did not find any association between periodontitis and IgG ACPA. Previous studies only evaluate ACPA in serum, and as local mucosal immune responses are likely involved in periodontitis, saliva antibodies are of interest to investigate. Saliva IgA ACPA has in a pilot study of RA patients been associated with lower disease activity and less erosions(3), but has not previously been evaluated in relation to periodontitis. <h3>Objectives</h3> To evaluate if saliva or serum ACPA is associated to periodontitis, in patients with RA. <h3>Methods</h3> In this population-based cohort of patients with RA (n=132), we included all patients with RA older than 61 years, living in Karlskrona in southern Sweden, between October 21, 2013 and January 7, 2015. The patients underwent a clinical examination by a rheumatologist, a dental clinical examination by a dental nurse and a panorama radiograph of the jaws and teeth. Periodontitis was defined as a distance from the cement-enamel junction (CEJ) to the bone level ≥ 5 mm, as defined by the radiographic assessment, at ≥ 30% of interproximal sites. We analysed antibodies against second generation cyclic citrullinated peptides (anti-CCP) in enzyme immunoassays in serum and saliva. Saliva samples were analysed in parallel for anti-CCP and anti-CAP, the arginine containing control peptide. Serum ACPA positivity was defined as the 99<sup>th</sup> percentile of healthy controls. In saliva, a positive test was defined as a difference in optical density (OD) for IgA anti-CCP and IgA anti-CAP (delta OD)&gt; 0. <h3>Results</h3> Saliva IgA ACPA was found in 11% of RA patients with periodontitis and in 24% of RA patients with no periodontitis (p=0.052). There was no difference between the groups concerning IgG or IgA ACPA in serum. A logistic regression analysis adjusting for gender, age and smoking showed an Odds Ratio of 0.299 (95% CI=0.096-0.929, p=0.037) for RA patients with periodontitis to be positive for saliva IgA ACPA, compared to RA patients with no periodontitis. <h3>Conclusion</h3> A weak, negative, correlation was observed between periodontitis and saliva IgA ACPA, when adjusting for age, sex and smoking. No correlation was observed between periodontitis and IgA or IgG ACPA in serum. In this cohort of patients with established RA, our findings do not support the hypothesis that periodontitis leads to increased formation of IgA ACPA in saliva or serum. <h3>References</h3> [1],Dissick A, et al. J Periodontol. 2010;81(2):223-30. [2] Eriksson K, et al. PloS one. 2016;11(5):e0155956. [3] Svärd A, et al. Immunobiology. 2013;218(2):232-7. <h3>Disclosure of Interests</h3> None declared