CTLA-4IG suppresses reactive oxygen species by preventing synovial adherent cell-induced inactivation of Rap1, a Ras family GTPASE mediator of oxidative stress in rheumatoid arthritis T cells.

Abstract

OBJECTIVE:

Oxidative stress contributes to the inflammatory properties of rheumatoid arthritis (RA) synovial T lymphocytes. This study was undertaken to investigate the mechanisms leading to production of reactive oxygen species (ROS) and oxidative stress in RA synovial T lymphocytes.

METHODS:

ROS production in T lymphocytes from the peripheral blood (PB) of healthy donors and from the PB and synovial fluid (SF) of RA patients was measured by ROS-dependent fluorescence of 6-carboxy-2',7'-dichlorofluorescein. Rap1 GTPase activation was assessed by activation-specific probe precipitation. Proliferation of RA PB and SF T lymphocytes was assayed by 3H-thymidine incorporation. In some experiments, RA PB T cells were preincubated with autologous SF or with PB or SF adherent cells. Experiments were performed in the absence or presence of transwell membranes or CTLA-4Ig fusion proteins. Short- and long-term stimulations of healthy donor PB T lymphocytes were performed with inflammatory cytokines, in the absence or presence of activating anti-CD28 antibodies.

RESULTS:

T lymphocyte ROS production and Rap1 inactivation were mediated by cell-cell contact with RA synovial adherent cells, and this correlated with T cell mitogenic hyporesponsiveness. CTLA4-Ig blockade of synovial adherent cell signaling to CD28 T cells reversed the inhibition of Rap1 activity and prevented induction of ROS. Introduction of active RapV12 into T cells also prevented induction of ROS production. Coincubation of T cells with stimulating anti-CD28 antibodies and inflammatory cytokines synergistically increased T cell ROS production.

CONCLUSION:

Cell-cell contact between T cells and RA synovial adherent cells mediates Rap1 inactivation and subsequent ROS production in T lymphocytes following exposure to inflammatory cytokines. This process can be blocked by CTLA4-Ig fusion protein.

• Authors: P H J Remans, C A Wijbrandts, M E Sanders, R E Toes, F C Breedveld, P P Tak, J M van Laar, K A Reedquist
• Journal: Arthritis and rheumatism (Arthritis Rheum) Vol. 54 Issue 10 Pg. 3135-43 (Oct 2006) ISSN: 0004-3591 [Print] United States
• PMID: 17009234 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antirheumatic Agents
• CD28 Antigens
• Immunoconjugates
• Reactive Oxygen Species
• Abatacept
• rap1 GTP-Binding Proteins
• ras Proteins

Topics

• Abatacept
• Antirheumatic Agents (pharmacology)
• Arthritis, Rheumatoid (genetics, metabolism, pathology, physiopathology)
• CD28 Antigens (genetics, metabolism)
• Cell Communication (physiology)
• Cells, Cultured
• Female
• Gene Expression Regulation (drug effects)
• Humans
• Immunoconjugates (pharmacology)
• Male
• Oxidative Stress (genetics, physiology)
• Reactive Oxygen Species (metabolism)
• Signal Transduction (genetics, physiology)
• Synovial Membrane (drug effects, metabolism, pathology)
• T-Lymphocytes (immunology, metabolism, pathology)
• rap1 GTP-Binding Proteins (genetics, metabolism)
• ras Proteins (genetics, metabolism)