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Abstract:
Fragments of synovial membranes from three patients with rheumatoid arthritis were incubated in Dulbecco's modified Eagle's medium (DMEM). Histamine was released into the medium at rates up to 649.3 ng/g synovium/day. To investigate whether histamine in synovial fluid may have more than a vasoactive role, cells cultured from human trabecular bone adjacent to a rheumatoid joint and human adherent rheumatoid synovial cells were incubated with different concentrations of histamine for 5 min. Histamine increased the intracellular content of cyclic AMP up to three fold in a dose-related manner but had no effect on synovial cells. This offers preliminary evidence that cells grown from human trabecular bone have histamine receptors.
Insights
Histamine is released from rheumatoid arthritis synovium. Cells from human trabecular bone, but not synovial cells, showed increased cyclic AMP in response to histamine, suggesting histamine receptors on bone cells.
Area of Science:
- Rheumatology
- Cell Biology
- Pharmacology
Background:
- Rheumatoid arthritis (RA) involves synovial inflammation.
- Histamine's role in RA beyond vasodilation is unclear.
- Synovial fluid histamine levels can be elevated in RA.
Purpose of the Study:
- To investigate histamine release from RA synovial membranes.
- To determine if histamine affects cells from human trabecular bone and rheumatoid synovial cells.
- To explore potential non-vasoactive roles of histamine in the RA joint.
Main Methods:
- Incubation of synovial membrane fragments from RA patients.
- Measurement of histamine release into Dulbecco's modified Eagle's medium (DMEM).
- Incubation of human trabecular bone cells and rheumatoid synovial cells with histamine, followed by cyclic AMP measurement.
Main Results:
- Histamine was released from RA synovial membranes at significant rates (up to 649.3 ng/g synovium/day).
- Histamine increased intracellular cyclic AMP in a dose-dependent manner in human trabecular bone cells (up to threefold).
- Histamine had no significant effect on rheumatoid synovial cells.
Conclusions:
- Preliminary evidence suggests histamine receptors are present on human trabecular bone cells adjacent to rheumatoid joints.
- Histamine may play a direct role in modulating cellular function in the RA joint beyond its vasoactive properties.
- Further research is warranted to elucidate the specific functions of histamine signaling in bone cells within the context of rheumatoid arthritis.