Vasculitis & polymyalgia rheumatica
Granulocyte-macrophage colony-stimulating factor (GM-CSF) drives IL-6 production by macrophages in polymyalgia rheumatica
Authors' conclusion
The monocyte compartment is expanded and activated in PMR. Macrophages in PMR-affected tissue produce abundant proinflammatory cytokines such as IL-6. A network of locally expressed cytokines, including GM-CSF, M-CSF, and IFN-γ, may drive the proinflammatory functions of these macrophages.
Study context
- Population
- Patients with polymyalgia rheumatica (PMR); blood, subacromial-subdeltoid (SASD) bursal fluid and bursa tissue
- Comparison
- PMR vs healthy controls / surgical controls
- Controls undergoing shoulder replacement surgeryn = 10reference
Methodological detailsflow cytometry, immunohistochemistry and immunofluorescence, macrophage differentiation cultures
- Flow cytometry
- Immunohistochemistry and immunofluorescence
- Macrophage differentiation cultures
Main finding
As reported in the abstract
- Monocytes (CD14highCD16- and CD14highCD16+) increased in blood of PMR patients and activated in bursal fluid
- Macrophages dominated immune infiltrates in PMR-affected tissue, expressing various proinflammatory cytokines
- IL-6 and IFN-γ expression abundant in both PMR and control tissue
- GM-CSF and macrophage colony-stimulating factor (M-CSF) significantly increased in PMR tissue
- Elevated CD206/folate receptor β ratio in PMR tissue macrophages, reflecting a GM-CSF skewed signature
- GM-CSF/M-CSF/IFN-γ combination significantly boosted IL-6 production in vitro; limited IL-6 production without GM-CSF
Original publication
GM-CSF drives IL-6 production by macrophages in polymyalgia rheumatica. Ann Rheum Dis. Published 5 February 2025. doi:10.
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