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Modulation of fas-ligand (Fas-L) on human microglial cells: an in vitro study
S Frigerio1, V Silei, E Ciusani
1Istituto Nazionale Neurologico 'C. Besta', Via Celoria 11, 20133, Milan, Italy.
Abstract:
The expression of Fas-Ligand (Fas-L) on microglia could be relevant in multiple sclerosis immunopathology. The present study was performed to evaluate in vitro the expression of Fas-L in human microglial cells both unstimulated and after stimulation with IFN-gamma, beta-IFN-1b and beta-IFN-1b+IFN-gamma. Cells were stimulated for 6,12, 24 and 48 h. Surface Fas-L was evaluated by flow cytometry, total Fas-L by Western blot, whereas mRNA for Fas-L was measured by RT-PCR. We also evaluated the capacity of microglial cells to induce, in vitro, apoptosis on Fas-positive T leukemia Jurkat cells. Our results showed a constitutive expression of Fas-L on microglia. IFN-gamma downregulated the expression of the molecule, while beta-IFN-1b and beta-IFN-1b+IFN- gamma did not. The amount of surface Fas-L was related to the ability of microglial cells to induce apoptosis in Fas-positive target cells, which was partly inhibited by blockade of the Fas-Fas-L pathway.
Insights
Fas-Ligand (Fas-L) is present on microglia and can trigger apoptosis in T cells. Interferon-gamma downregulates Fas-L expression, impacting multiple sclerosis immunopathology.
Area of Science:
- Neuroimmunology
- Cellular Immunology
- Molecular Biology
Background:
- Microglia play a key role in the central nervous system's immune response.
- Fas-Ligand (Fas-L) expression on immune cells is implicated in autoimmune diseases like multiple sclerosis.
- Understanding microglial Fas-L regulation is crucial for neuroinflammation research.
Purpose of the Study:
- To investigate the in vitro expression of Fas-L on human microglial cells.
- To determine the effect of Interferon-gamma (IFN-γ) and beta-Interferon (β-IFN-1b) on microglial Fas-L expression.
- To assess the functional capacity of microglial cells to induce apoptosis in Fas-positive T cells.
Main Methods:
- Human microglial cells were stimulated with IFN-γ, β-IFN-1b, or a combination.
- Fas-L expression was measured at the surface (flow cytometry), total protein (Western blot), and mRNA (RT-PCR) levels.
- Apoptosis induction in Jurkat T cells was assessed, with and without Fas-Fas-L pathway blockade.
Main Results:
- Microglial cells constitutively express Fas-L.
- IFN-γ significantly downregulated Fas-L expression, while β-IFN-1b alone or in combination with IFN-γ did not.
- Surface Fas-L levels correlated with the ability of microglia to induce apoptosis in Jurkat cells, partially inhibited by pathway blockade.
Conclusions:
- Microglial Fas-L is constitutively expressed and can mediate T cell apoptosis.
- IFN-γ downregulates microglial Fas-L, suggesting a regulatory role in neuroinflammation.
- These findings highlight the complex interplay between interferons, microglia, and T cell-mediated apoptosis in multiple sclerosis.