Immunological synapse formation inhibits the apoptosis of macrophages in rheumatoid arthritis / 中华风湿病学杂志

ABSTRACT

Objective To determine whether macrophages can behave as antigen presenting cells participating the formation of immunological synapse in rheumatoid arthritis (RA) and whether this process can affect the apoptosis. Moreover, this study was aimed to observe the function of cyclophilin A (CypA) in immunological synapse formation and its role in regulating the apoptosis of macrophages. Methods human acute monocytic leukemia cell line (THP-1) induced macrophages were coated with staphylococcal enterotoxin B(SEB) (100 ng/ml) and co-cultured with activated Jurkat T cells (human acute T-cell leukemia cell line), then incubated in the RPMI-1640 for 16 hours to induce apoptosis. The apoptosis of the macrophages were analyzed by flow cytometry by Annexin V-PI staining. The macrophages cultured in the RPMI-1640 alone were used as control. Meanwhile, CypA (200 ng/ml) were added to or not added in order to observe the apoptosis of macrophages. The function of CypA and the apoptosis of macrophages isolated from RA peripheral blood were also investigated through co-culture with CD4+T cells isolated by immunomagnetic beads. Comparisons between groups were performed by two-sample t-tests. Results In the peripheral blood of healthy people and RA patients, the apoptosis of macrophages which participated immunological synapse was (32.9±2.8)%, (24.7±1.6)%, (14.5±1.2)% respectively, which was significantly lower than the apoptosis of macrophages cultured alone [ respectively for (61.4±2.4)%, (45.5±2.6)%, (22.9±1.5)%, (P<0.05) ]. After CypA was added, the apoptosis of macrophages in cell lines, healthy people and RA patients decreased to (27.2±2.1)%, (20.1±1.1)%, (12.9±1.0)%, lower than the apoptosis of macrophages which participated immunological synapse formation (P<0.05). Conclusion In RA, the macrophages participate in the formation of immunological synapse by interacting with CD4+ T cells. They can significantly reduce the apoptosis on themselves. CypA can enhance this effect. These results provide a new theoretical foundation for prolonged survival of macrophages in RA, which can secrete a variety of cytokines to enhance inflammation and joint destruction.