Related Experiment Video
Updated: Jul 19, 2026
Isolation and Culture of Primary Synovial Macrophages and Fibroblasts from Murine Arthritis Tissue
Published on: February 24, 2023
Regulation of Mcl-1 expression in rheumatoid arthritis synovial macrophages
Hongtao Liu1, QiQuan Huang, Bo Shi
1Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA.
Objective:
Resistance to apoptosis may be an important mechanism contributing to the persistence of rheumatoid arthritis (RA). This study was undertaken to characterize the expression, regulation, and function of the antiapoptotic Bcl-2 family member Mcl-1 in macrophages isolated from the joints of patients with RA.
Methods:
Mononuclear cells were isolated from the synovial fluid (SF) of patients with RA. Mcl-1 expression was documented by intracellular staining of CD14+ cells using flow cytometry, and by real-time polymerase chain reaction or immunoblot analysis of isolated macrophages. The expression of Mcl-1 was suppressed with small interfering RNA (siRNA) or chemical inhibitors of the phosphatidylinositol 3-kinase (PI 3-kinase)/Akt-1 and signal transducer and activator of transcription 3 (STAT-3) pathways. Apoptosis was defined by the loss of mitochondrial transmembrane potential and by DNA fragmentation.
Results:
The expression of Mcl-1 was increased in CD14+ macrophages from the SF of patients with RA compared with normal in vitro-differentiated macrophages. Inhibition of the PI 3-kinase/Akt-1 or STAT-3 pathways significantly reduced the percentage of CD14+ cells within the SF and resulted in the reduction of Mcl-1 and the induction of apoptosis of synovial macrophages. Transfection of RA synovial macrophages with Mcl-1 siRNA resulted in apoptotic cell death.
Conclusion:
Mcl-1 is critical for the survival of macrophages in the joints of patients with RA, and is therefore a potential therapeutic target in this disease.
Insights
Mcl-1 protein is elevated in rheumatoid arthritis (RA) joint macrophages, promoting their survival. Inhibiting Mcl-1 or its signaling pathways induces apoptosis, suggesting Mcl-1 as a therapeutic target for RA.
Area of Science:
- Immunology
- Molecular Biology
- Rheumatology
Background:
- Rheumatoid arthritis (RA) persistence may involve resistance to apoptosis.
- Mcl-1, an antiapoptotic protein from the Bcl-2 family, is investigated in RA.
Purpose of the Study:
- To characterize Mcl-1 expression, regulation, and function in RA synovial macrophages.
- To explore Mcl-1 as a potential therapeutic target in RA.
Main Methods:
- Isolated mononuclear cells from RA synovial fluid (SF).
- Quantified Mcl-1 expression via flow cytometry, PCR, and immunoblotting.
- Inhibited Mcl-1 using siRNA and PI 3-kinase/STAT-3 pathway inhibitors.
Main Results:
- Mcl-1 expression was higher in RA synovial macrophages compared to controls.
- Inhibiting PI 3-kinase/Akt-1 or STAT-3 pathways reduced Mcl-1 and induced apoptosis.
- Mcl-1 siRNA transfection led to apoptotic cell death in RA synovial macrophages.
Conclusions:
- Mcl-1 is crucial for RA synovial macrophage survival.
- Mcl-1 represents a potential therapeutic target for rheumatoid arthritis.
Related Concept Videos
01:24T Cell Types and Functions
Th1 cells stimulate dendritic cells to express necessary co-stimulatory molecules on their surfaces for...
01:20The JAK-STAT Signaling Pathway