When and where does inflammation begin in rheumatoid arthritis?

Area of Science:

• Rheumatology
• Immunology
• Pathogenesis of Autoimmune Diseases

Background:

• The exact cause, timing, and initiation site of rheumatoid arthritis (RA) related autoimmunity remain unknown.
• Understanding RA's early development is crucial for improving treatments and prevention strategies.

Purpose of the Study:

• To explore the initial steps in rheumatoid arthritis (RA) development.
• To gain insights into RA pathogenesis for enhanced therapeutic and preventive approaches.

Main Methods:

• Review of emerging data on systemic inflammation and autoimmunity in RA.
• Analysis of evidence suggesting mucosal sites as potential origins of RA-related autoimmunity.
• Consideration of candidate mucosal sites including oral, lung, and gastrointestinal mucosa.

Main Results:

• Systemic inflammation and autoimmunity in RA precede detectable joint inflammation.
• RA-related autoimmunity may initiate at mucosal sites years before joint symptoms.
• Evidence supports oral, lung, and gastrointestinal mucosa as potential initiation sites, with individual variations possible.

Conclusions:

• Prospective studies are essential to determine the precise onset and location of RA.
• Research should focus on the preclinical period of RA to understand mucosal inflammation's role.
• Investigating the link between mucosal inflammation, autoantibody generation, and joint inflammation is critical for RA insights.