Lung abnormalities may precede RA development
MedWire News: Patients with rheumatoid arthritis (RA)-related autoantibodies (Ab) show signs of lung inflammation even before the onset of inflammatory arthritis (IA), US research indicates.
"These findings suggest that the lung may be an early site of autoimmune-related injury, and potentially a site of generation of RA-related autoimmunity," say Kevin Deane (University of Colorado, Aurora) and co-authors in the journal Arthritis and Rheumatism.
The team used high-resolution computed tomography (CT) imaging to examine pulmonary abnormalities in 42 patients, aged an average of 54 years, with anti-cyclic citrullinated peptide antibodies and/or two or more rheumatoid factor types - an Ab profile strongly indicative of RA - but without IA. Around half (52%) were female and 38% of the group smoked.
The findings were compared with lung results for 15 individuals without RA-related Ab matched by age, gender, race, and smoking habit, and 12 patients who had been diagnosed with seropositive RA within the past year.
Overall, 76% of the RA-related Ab-positive patients had airway abnormalities visible on CT compared with just 33% of Ab-negative controls. The significant difference in the prevalence of abnormalities between Ab-positive and -negative patients remained after adjusting for chronic lung disease, joint tenderness, and smoking status.
Airway abnormalities were visible on CT in 76% of RA-related Ab-positive patients and 92% of early RA patients, but just 33% of Ab-negative controls.
Abnormalities detected included bronchial wall thickening and bronchiectasis, centrilobular opacities, and air trapping. Of note, the Ab-positive patients had comparable prevalence and type of lung abnormalities to the early RA patients, Deane et al report.
At approximately 13 months of follow-up, two of the Ab-positive patients had been diagnosed with IA and articular RA.
The researchers admit that it is not possible to prove that the remaining Ab-positive patients have preclinical RA but say: "The presence of RA-related autoimmunity regardless of progression to future symptomatic IA is still relevant to understanding the pathogenesis of RA."
The team recommends further research to determine whether lungs are an early target of IA or a site where RA-related autoimmunity is generated.
"These studies may include serial assessments examining the progression of lung abnormalities and circulating autoimmunity in relationship to the development of IA, tissue sampling to define the biology of lung injury and inflammation in relation to potential generation of RA-related Abs, and examination of genetic and environmental factors that may be associated with potential pulmonary generation of RA-related autoimmunity," Deane et al suggest.
By Lynda Williams