SAN DIEGO—In recognition of the growing interest in and importance of the preclinical phases of rheumatic diseases, a panel of experts convened at the 2013 ACR/ARHP Annual Meeting, held October 26–30, to discuss key issues to better understand the etiology and early pathology of rheumatic diseases. This article summarizes data from select presentations given at this conference, including current investigation into the mucosal biology in the etiology of rheumatic diseases and ways to detect early organ injury in preclinical rheumatic diseases. [Editor’s Note: These sessions were recorded and are available via ACR SessionSelect at www.rheumatology.org.]
Mucosal Biology in the Etiology of Rheumatic Diseases
Jose U. Scher, MD, assistant professor of medicine and director of the Microbiome Center for Rheumatology and Autoimmunity at NYU-Hospital for Joint Diseases in New York, and Anca I. Catrina, MD, PhD, in the department of rheumatology at the Karolinska University Hospital, Karolinska Institute, in Stockholm, provided an update on the long-discussed potential role of the human microbiome in the pathogenesis of rheumatoid arthritis (RA).
In his talk, “Microbiome and Initiation and Propagation of Rheumatoid Arthritis,” Dr. Scher emphasized that emerging data are implicating the human microbiome in the pathogenesis of RA, as evidenced by studies that find an association of RA with various mucosal sites. “Mucosal sites exposed to a high load of bacterial antigens, such as the periodontium, lung, and gut, may represent the initial site of autoimmune generation or even the ‘second hit’ leading to emergence of RA clinical manifestations,” he said.
Currently, evidence of this association is strongest between oral microbiota and RA, and Dr. Scher walked participants through a number of more recent studies that he said are advancing the evidence on the link between Porphyromonas gingivalis (P. gingivalis) and RA (see Table 1).
He also presented new data suggesting an association between gut dysbiosis and RA, highlighting key findings from a recently published study that found a high abundance of Prevotella in new-onset RA (NORA) patients, and an increased sensitivity to dextran sulfate sodium (DSS) colitis associated with the presence of Prevotella.1 Further evidence on an association between Prevotella and new-onset RA, he said, is a study that showed that humans can be clustered into three groups, or enterotypes, according to gut microbiota, of which Prevotella is one enterotype. The study showed that although only 13% of people belong to the Prevotella enterotype, 75% of new-onset RA belong to that enterotype.
