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Methotrexate suppresses nitric oxide production ex vivo in macrophages from rats with adjuvant-induced arthritis
1Department of Pharmacology, Zeria Pharmaceutical Co. Ltd, Saitama, Japan.
Abstract:
We examined the effects of methotrexate (MTX) on the level of nitric oxide (NO) produced by peritoneal macrophages from rats with adjuvant-induced arthritis (AA) ex vivo. During the development of AA, paw swelling increased and LPS enhanced the capacity of peritoneal macrophages to produce NO and prostaglandin E2 (PGE2). MTX (0.1 mg/kg, p.o.) treatment for 21 days reduced the paw swelling, and inhibited the increased NO and PGE2 production. However, when MTX (0.1 mg/kg, p.o.) was administered to rats with established AA, these parameters were not significantly influenced. In normal rats, MTX (0.1 mg/kg, p.o.) treatment for 21 days did not change NO and PGE2 production of LPS-stimulated macrophages. On the other hand, macrophages from normal and AA rats cultured in the presence of MTX (1, 10 and 100 microM), were activated by LPS in vitro. MTX did not influence NO or PGE2 production by LPS-stimulated macrophages in normal and AA rats. By contrast, indomethacin (IM) (1.0 mg/kg, p.o.) treatment for 21 days reduced the paw swelling, and inhibited NO and PGE2 production in AA rats. IM inhibited significantly PGE2 production, but did not influence NO production by LPS-stimulated macrophages in vitro. These results suggest that MTX treatment reduces NO production in peritoneal macrophages in AA rats, and these actions of MTX may have an inhibitory effect without the modulation of PGE2.
Insights
Methotrexate (MTX) treatment in rats with adjuvant-induced arthritis (AA) reduced paw swelling and nitric oxide (NO) production. However, MTX did not affect established AA or NO production in vitro.
Area of Science:
- Immunology
- Pharmacology
- Rheumatology
Background:
- Adjuvant-induced arthritis (AA) in rats is characterized by increased paw swelling, nitric oxide (NO), and prostaglandin E2 (PGE2) production by macrophages.
- Methotrexate (MTX) is a common treatment for inflammatory conditions, but its specific effects on macrophage-derived mediators in AA require further investigation.
Purpose of the Study:
- To investigate the impact of methotrexate (MTX) on nitric oxide (NO) production by peritoneal macrophages in rats with adjuvant-induced arthritis (AA).
- To compare the effects of MTX with indomethacin (IM) on inflammatory markers in AA.
Main Methods:
- Rats with AA were treated with MTX (0.1 mg/kg, p.o.) for 21 days, and peritoneal macrophages were isolated.
- Macrophages were stimulated with lipopolysaccharide (LPS) ex vivo and in vitro to measure NO and PGE2 production.
- In vitro experiments also included MTX (1, 10, 100 microM) and IM (1.0 mg/kg, p.o.) treatments.
Main Results:
- MTX treatment reduced paw swelling and inhibited increased NO and PGE2 production in developing AA.
- MTX did not significantly influence these parameters in established AA or in normal rats.
- In vitro, MTX did not affect NO or PGE2 production by LPS-stimulated macrophages from normal or AA rats.
- Indomethacin (IM) reduced paw swelling and inhibited NO and PGE2 in AA rats, with a significant effect on PGE2 but not NO in vitro.
Conclusions:
- MTX treatment in AA rats reduces NO production in peritoneal macrophages, potentially contributing to its anti-inflammatory effects.
- The observed anti-inflammatory action of MTX in AA appears to occur independently of PGE2 modulation.
- MTX's efficacy may be time-dependent, with greater effects during the development rather than established phase of AA.