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Interferon-gamma increases cytoplasmic motility of alveolar macrophages via nitric oxide-dependent signaling pathways
T Fukushima1, K Sekizawa, Y Jin
1Department of Geriatric Medicine, Tohoku University School of Medicine, Sendai, Japan.
Abstract:
The effects of interferon-gamma (IFN-gamma) were investigated on cytoplasmic motility of alveolar macrophages (AM) from rat lungs in vitro. Cytoplasmic motility was examined by measuring remnant field strength from the cell surface of AM containing Fe3O4 particles, and the relaxation rate (lambda 0; min-1), which is related to cytoplasmic motility, was determined. IFN-gamma caused an increase in lambda 0 in a concentration-dependent fashion with the maximal effect at 1,000 U. Dibutyryl cyclic GMP (db cyclic GMP; 10(-3) M) mimicked IFN-gamma-induced effects, but db cyclic AMP (10(-3) M) decreased lambda 0. IFN-gamma (1,000 U)-induced increases in lambda 0 were concentration-dependently inhibited by NG-monomethyl-L-arginine (L-NMMA) with complete inhibition of a concentration of 10(-4) M and were also completely inhibited by either methylene blue (10(-5) M) or KT 5823 (10(-5) M), a specific inhibitor of protein kinase G. IFN-gamma (1,000 U) caused significant nitrite (NO2-) production from the control values of 0.2 +/- 0.1 to 10.0 +/- 0.2 microM/24 h per 10(6) cells (P < 0.001, n = 10), and this increase in NO2- production by IFN-gamma (1,000 U) was completely inhibited by L-NMMA (10(-4) M). IFN-gamma caused a concentration-dependent increase in a filamentous-actin (F-actin) content with the maximal effect at 1,000 U. db cyclic GMP (10(-3) M) mimicked IFN-gamma induced effects on F-actin formation.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Interferon-gamma (IFN-gamma) enhances rat alveolar macrophage (AM) cytoplasmic motility and filamentous-actin (F-actin) content. This effect is mediated by cyclic GMP and nitric oxide production, suggesting a role for IFN-gamma in regulating macrophage function.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- Alveolar macrophages (AM) are crucial immune cells in the lungs.
- Interferon-gamma (IFN-gamma) is a key cytokine involved in immune responses.
- Cytoplasmic motility and F-actin content are critical for macrophage function.
Purpose of the Study:
- To investigate the effects of IFN-gamma on the cytoplasmic motility of rat AM in vitro.
- To elucidate the signaling pathways involved in IFN-gamma-mediated effects on AM.
Main Methods:
- Measurement of cytoplasmic motility using remnant field strength of Fe3O4 particle-containing AM.
- Determination of relaxation rate (lambda 0) as an indicator of cytoplasmic motility.
- Assessment of nitrite (NO2-) production and filamentous-actin (F-actin) content.
Main Results:
- IFN-gamma increased lambda 0 and F-actin content in a concentration-dependent manner.
- Dibutyryl cyclic GMP mimicked IFN-gamma's effects, while dibutyryl cyclic AMP decreased lambda 0.
- IFN-gamma significantly increased NO2- production, which was inhibited by L-NMMA and methylene blue.
Conclusions:
- IFN-gamma enhances rat AM cytoplasmic motility and F-actin content via a cyclic GMP-dependent pathway.
- Nitric oxide production is involved in IFN-gamma's effects on AM.
- IFN-gamma plays a role in modulating macrophage cytoskeletal dynamics and function.