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Macrophage-derived nitric oxide regulates T cell activation via reversible disruption of the Jak3/STAT5 signaling
R M Bingisser1, P A Tilbrook, P G Holt
1TVW Telethon Institute for Child Health Research, Division of Cell Biology, West Perth, Australia.
Abstract:
Nitric oxide (NO) has been invoked as an important pathogenic factor in a wide range of immunologically mediated diseases. The present study demonstrates that macrophage-derived NO may conversely function to fine tune T cell-mediated inflammation via reversible dephosphorylation of intracellular signaling molecules, which are involved in the control of T cell proliferation. Thus, T cells activated in the presence of alveolar macrophages are unable to proliferate despite expression of IL-2R and secretion of IL-2. This process is reproduced by the NO generator S-nitroso-N-acetylpenicillamine and is inhibitable by the NO synthase inhibitor N(G)-methyl-L-arginine. Analysis of T cell lysates by immunoprecipitation with specific Abs and subsequent immunoblotting indicated marked reduction of tyrosine phosphorylation of Jak3 and STAT5 mediated by NO. Further studies indicated that NO-mediated T cell suppression was reversible by the guanylate cyclase inhibitors methylene blue and LY-83583 and was reproduced by a cell-permeable analogue of cyclic GMP, implicating guanylate cyclase activation as a key step in the inhibition of T cell activation by NO.
Insights
Nitric oxide (NO) can suppress T cell proliferation, a key immune response. This study reveals NO fine-tunes inflammation by dephosphorylating signaling molecules, impacting T cell activation.
Area of Science:
- Immunology
- Cell Biology
- Molecular Biology
Background:
- Nitric oxide (NO) is implicated in various immune-mediated diseases.
- Its role in regulating T cell responses requires further elucidation.
Purpose of the Study:
- To investigate the role of macrophage-derived NO in T cell proliferation and inflammation.
- To identify the molecular mechanisms underlying NO's effect on T cells.
Main Methods:
- T cell activation assays in the presence of alveolar macrophages or NO donors.
- Inhibition studies using NO synthase and guanylate cyclase inhibitors.
- Immunoprecipitation and immunoblotting to analyze protein phosphorylation (Jak3, STAT5).
Main Results:
- Macrophage-derived NO inhibited T cell proliferation, even with IL-2 receptor expression.
- NO reduced tyrosine phosphorylation of Jak3 and STAT5 signaling molecules.
- NO-mediated T cell suppression was reversible and involved guanylate cyclase activation.
Conclusions:
- Macrophage-derived NO plays a regulatory role in T cell-mediated inflammation.
- NO suppresses T cell activation by dephosphorylating key signaling proteins via guanylate cyclase.
- This mechanism highlights NO's complex role in immune responses.