CD169+ Monocyte and Regulatory T Cell Subsets Are Associated with Disease Activity in Rheumatoid Arthritis.

Area of Science:

• Immunology
• Rheumatology

Background:

• Rheumatoid arthritis (RA) pathogenesis involves immune cell activation.
• Regulatory T cells (Tregs) and monocytes are critical in driving RA inflammation.

Purpose of the Study:

• To investigate the relationship between RA disease activity and circulating Treg/monocyte numbers and phenotypes.
• To explore a potential sialic acid (Sia)-mediated link between Tregs and monocytes in vitro.

Main Methods:

• Peripheral blood mononuclear cells (PBMCs) isolated from RA patients and healthy controls.
• Flow cytometry used for Treg and monocyte subset enumeration and phenotyping.
• In vitro experiments assessed Sia effects on Treg activation markers and cytokine release.

Main Results:

• High disease activity RA patients showed significantly lower relative numbers of Tregs (CD4+CD25+CD127− and memory CD45RA−FoxP3+).
• Non-classical CD169+ monocytes were associated with RA disease activity (p = 0.012).
• Sialic acid reduced Treg expression of FoxP3, NFκB, and cytokine secretion in vitro.

Conclusions:

• Reduced Treg numbers and altered monocyte phenotypes are linked to RA disease activity.
• Non-classical CD169+ monocytes correlate with post-treatment RA disease activity.
• Sialic acid may dampen Treg activation and cytokine release, potentially via CD169+ monocyte interactions.