More Evidence That RA Can Arise in the Lungs

Individuals with rheumatoid arthritis (RA) who are positive for antibodies to citrullinated proteins (ACPA) have highly activated lymphocytes and an enriched population of ACPA in their bronchial tissues early in the disease, researchers from Stockholm's Karolinska University Hospital have found.

Some citrullinated targets for these antibodies, as well as the antibodies themselves, are shared between lungs and synovial tissues of patients with RA, their study finds. The researchers believe this confirms that early inflammatory events in the lungs may trigger RA in some patients.

Presented by rheumatologist Anca Catrina MD PhD at the 2014 annual meeting of the European Union League Against Rheumatism (EULAR), the study analyzed bronchial biopsies from 24 patients with less than a year's duration of symptomatic RA as yet untreated by disease-modifying drugs (DMARDs), and compared them to biopsies from healthy individuals. Histology and immunohistochemistry characterized immune cell populations and citrullinated protein targets in the tissues. The subjects were also assessed for relevant HLA subtypes. 

Mass spectometry identified 8 citrullinated peptides in the synovium and 7 in the bronchial biopsies, two of which (derived from vimentin) were present in most lung and synovial samples from the ACPA-positive RA patients

The study follows a report by the same team published in Arthritis & Rheumatology last January, which found ACPAs associated with parenchymal lung abnormalities and antibody enrichment in the lungs of patients with early ACPA-positive RA..