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Updated: Jul 8, 2026
Isolation and Culture of Primary Synovial Macrophages and Fibroblasts from Murine Arthritis Tissue
Published on: February 24, 2023
Expression of mucin 3 and mucin 5AC in arthritic synovial tissue
Michael V Volin1, Shiva Shahrara, G Kenneth Haines
1Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, Illinois 60515, USA. mvolin@midwestern.edu
Objective:
Rheumatoid arthritis (RA) is a chronic inflammatory disease that is characterized by hypertrophy of the synovial tissue, leukocyte infiltration, angiogenesis, and ultimately joint destruction. Mucins (MUCs) are a family of heavily glycosylated proteins that protect epithelial membranes and are used as ligands for cell adhesion. MUC gene expression has been found to be altered in many cancers and inflammatory states. This study was undertaken to examine its expression in synovial tissue (ST) and role in arthritis.
Methods:
We performed immunohistochemistry, Western blotting, and reverse transcriptase-polymerase chain reaction to determine expression patterns of MUC1, MUC2, MUC3, and MUC5AC in RA, osteoarthritic (OA), and normal human ST.
Results:
MUC3 was expressed in synovial lining cells, macrophages, and fibroblasts. Significantly more RA (n=12) and OA (n=13) synovial lining cells expressed MUC3 than did normal synovial lining cells (n=7) (22% and 24% versus 0.4%, respectively; P<0.05). Additionally, macrophages in RA and OA ST expressed significantly more MUC3 than did macrophages in normal ST (50% and 51% versus 10%, respectively; P<0.05). MUC5AC was expressed at low levels in synovial lining cells, macrophages, and endothelial cells in RA and OA ST, and was barely expressed in normal ST. MUC1 and MUC2 proteins were not detected in ST. Messenger RNA (mRNA) for MUC3 and MUC5AC was detected in ST, and mRNA for MUC3 was detected in cultured ST fibroblasts.
Conclusion:
These data demonstrate up-regulated MUC expression by ST cells and suggest a novel role of MUC3 and MUC5AC in the pathogenesis of arthritis.
Insights
Mucin 3 (MUC3) and Mucin 5AC (MUC5AC) expression is increased in the synovial tissue of patients with rheumatoid arthritis and osteoarthritis. This suggests a role for these mucins in the development of arthritis.
Area of Science:
- Immunology
- Molecular Biology
- Rheumatology
Background:
- Rheumatoid arthritis (RA) is a chronic inflammatory joint disease.
- Mucins (MUCs) are glycoproteins involved in epithelial protection and cell adhesion.
- Altered MUC gene expression is observed in various inflammatory conditions.
Purpose of the Study:
- To investigate mucin expression patterns in synovial tissue (ST) from patients with RA, osteoarthritis (OA), and healthy individuals.
- To determine the role of mucins in the pathogenesis of arthritis.
Main Methods:
- Immunohistochemistry, Western blotting, and RT-PCR were used to analyze MUC1, MUC2, MUC3, and MUC5AC expression in human ST.
- Expression was assessed in synovial lining cells, macrophages, fibroblasts, and endothelial cells.
Main Results:
- Mucin 3 (MUC3) expression was significantly elevated in synovial lining cells and macrophages of RA and OA patients compared to controls.
- Mucin 5AC (MUC5AC) showed low-level expression in RA and OA ST, with minimal presence in normal ST.
- MUC1 and MUC2 proteins were undetectable in ST; however, MUC3 and MUC5AC mRNA were detected.
Conclusions:
- Synovial tissue cells exhibit upregulated mucin expression in arthritis.
- MUC3 and MUC5AC are implicated as novel players in the pathogenesis of arthritis.
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