Rheumatoid Lung Disease

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease that affects the synovial membrane of the joints in a symmetrical pattern, leading to cartilage and bone damage. It affects 0.5-1% of the general population, predominantly women in their fourth to fifth decades of life. In addition to its impact on the joints, RA has numerous extra-articular manifestations involving the skin, eyes, heart and lung. Among these, pulmonary manifestations play a pivotal role in morbidity and mortality. RA can affect all anatomical compartments of the lung such as the airways, lung parenchyma, pulmonary vasculature and pleura. Among these, parenchymal disease that manifests as interstitial ling disease (ILD) is the most serious. The etiopathogenesis of RA remains elusive with multiple underlying genetic and environmental risk factors implicated. Cigarette smoking has been strongly associated with an increased risk of developing RA in genetically susceptible individuals, particularly those carrying the shared epitope of the human leucocyte antigen (HLA) DRB1* alleles. Smoking induces chronic pulmonary inflammation, promotes protein citrullination in the lungs, leads to the generation of anti-citrullinated antibodies and contributes to the development of RA. In this review we discuss the various manifestations of RA associated lung disease, methods of screening, the pathophysiology of RA in relation to the lung and recent advances in treatment.