Session Title: Rheumatoid Arthritis - Human Etiology and Pathogenesis
Session Type: Abstract Submissions (ACR)
Background/Purpose: The lung has been implicated in the pathogenesis of rheumatoid arthritis (RA). The aim of this study was to evaluate the presence of autoantibodies to citrullinated (Cit) and non-citrullinated (Arg) forms of 2 cyclic synthetic peptides (ACPA) in the sputum of patients with long standing rheumatoid arthritis.
Methods: Twenty RA patients (80% female, mean age 62 years) and 15 age/gender matched healthy controls (81% female, mean age 58 years) participated in this study. Demographic and epidemiological data, including age, gender, disease duration and smoking habits, were collected. All the subjects underwent complete lung function tests, and provided induced sputum. The severity of the disease was evaluated in the RA patients by means of DAS score, and hand and feet X rays. Antibodies to Cit and Arg peptides in the sputum of the RA patients and healthy controls, as well as in the serum of the RA patients, were determined by ELISA.
Results: The RA patients suffered from long standing disease (mean disease duration of 12 years), displayed moderate disease activity (mean DAS 3.44), and showed a mean Sharp van der Heijde score of 57.5. Seventy % of the patients were on DMARDs and 65% on biologics, mainly TNF alpha blockers. Sixty % and 68 % of the RA and healthy controls, respectively, were defined as “ever smoker”. Eleven of the 20 RA patients showed in most cases high titers of ACPA in their sera. Six of the seropositive (55%) and none of the seronegative RA patients and none of the healthy controls showed detectable levels of ACPA in their sputum. The ratio between the reactivity with Cit and Arg peptides in the sputum was significantly higher in RA sputum than in control sputum (1.33 +/- 1.2 vs. 0.64 +/- 0.14, p=0.02). A positive correlation was found between sputum ACPA and age and serum ACPA in RA patients, as well as between sputum anti-Cit/Arg reactivity ratio and the proportion of neutrophils and lymphocytes in the sputum. No significant correlation was found between sputum ACPA and disease severity, smoking or lung function tests.
Conclusion: ACPA can be detected in the sputum of RA patients and are correlated with the presence in the serum. These findings further strengthen the hypothesized role of the lungs in RA pathogenesis.
W. Vree Egberts,
G. J. Pruijn,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/sputum-anti-citrullinated-protein-antibodies-in-patients-with-long-standing-rheumatoid-arthritis/