Figure 1.

Schematic depicting possible biologic mechanisms linking obstructive lung disease with increased risk for rheumatoid arthritis. Mechanisms of airway obstruction include bronchoconstriction, thickened airways with secretions, loss of airways, and distal air trapping. A combination of genetic and environmental factors may contribute to many biologic processes that could increase local inflammation, recruit immune cells, produce neoantigens, produce RA-related autoantibodies, and form lymphoid aggregates in lung tissue prior to systemic involvement. Abbreviations: ACPA, anti-citrullinated protein antibodies; APC, antigen-presenting cell; COPD, chronic obstructive pulmonary disease; ILD, interstitial lung disease; PAD, peptidylarginine deiminase; PTM, post-translational modifications; RA, rheumatoid arthritis; ROS, reactive oxygen species.