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Induction of IFN-alphabeta enables Listeria monocytogenes to suppress macrophage activation by IFN-gamma.

Rayamajhi M, Humann J, Penheiter K, Andreasen K, Lenz LL - J. Exp. Med. (2010)

Bottom Line: We found that cultured macrophages infected with L. monocytogenes were refractory to IFN-gamma treatment as a result of down-regulation of the IFN-gamma receptor (IFNGR).The soluble factor responsible for these effects was identified as host IFN-alphabeta.Such cross talk permits prioritization of IFN-alphabeta-type immune responses and may contribute to the beneficial effects of IFN-beta in treatment of inflammatory diseases such as multiple sclerosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Jewish Health, Denver, CO 80206, USA.

ABSTRACT
Production of type I interferon (IFN; IFN-alphabeta) increases host susceptibility to Listeria monocytogenes, whereas type II IFN (IFN-gamma) activates macrophages to resist infection. We show that these opposing immunological effects of IFN-alphabeta and IFN-gamma occur because of cross talk between the respective signaling pathways. We found that cultured macrophages infected with L. monocytogenes were refractory to IFN-gamma treatment as a result of down-regulation of the IFN-gamma receptor (IFNGR). The soluble factor responsible for these effects was identified as host IFN-alphabeta. Accordingly, macrophages and dendritic cells (DCs) showed reduced IFNGR1 expression and reduced responsiveness to IFN-gamma during systemic infection of IFN-alphabeta-responsive mice. Furthermore, the increased resistance of mice lacking the IFN-alphabeta receptor (IFNAR(-/-)) to L. monocytogenes correlated with increased expression of IFN-gamma-dependent activation markers by macrophages and DCs and was reversed by depletion of IFN-gamma. Thus, IFN-alphabeta produced in response to bacterial infection and other stimuli antagonizes the host response to IFN-gamma by down-regulating the IFNGR. Such cross talk permits prioritization of IFN-alphabeta-type immune responses and may contribute to the beneficial effects of IFN-beta in treatment of inflammatory diseases such as multiple sclerosis.

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L. monocytogenes infection suppresses macrophage responses to IFN-γ. (A) Cell surface MHC class II (MHCII) expression on live-gated C57BL/6 BMM treated with IFN-γ after mock infection (light shading) or infection with wt Lm (dark shading) at MOI = 1. The clear histogram depicts MHCII expression on mock-infected cells not treated with IFN-γ. (B) Semiquantitative RT-PCR was performed using complementary DNA template prepared from mock- or wt Lm–infected BMM at 10 hpi. Treatment with IFN-γ occurred 2 h after infection. (C) RAW264.7-CIITApIV reporter cells (Fortune et al., 2004) were mock or wt Lm infected. At 2 hpi, cells received fresh media containing 0 (none) or 100 U/ml IFN-γ. Luciferase reporter activity was measured 6 h later. (D) RAW264.7 cells were transfected with a GAS-luciferase reporter construct. A stable IFN-γ–responsive transfectant (RAW-GAS.6) was treated with IFN-γ at 2 hpi with wt Lm or a hemolysin-deficient L. monocytogenes strain (ΔHly Lm). Infected and control RAW-GAS.6 cells were lysed to assay luciferase activity at 10 hpi. (E) Immunoblotting for phospho-STAT1 after IFN-γ treatment of mock-infected or wt Lm–infected cells. Cells were treated with IFN-γ at the indicated times after infection and lysed 5, 15, or 30 min later. Similar results were seen using lysates prepared from four independent experiments. For C and D, bars show SE from three independent samples. Horizontal lines represent the level of expression on uninfected cells. Error bars indicate SEM. A Student’s t test was used to calculate p-values where indicated. Experiments in A–D were repeated at least three times.
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fig1: L. monocytogenes infection suppresses macrophage responses to IFN-γ. (A) Cell surface MHC class II (MHCII) expression on live-gated C57BL/6 BMM treated with IFN-γ after mock infection (light shading) or infection with wt Lm (dark shading) at MOI = 1. The clear histogram depicts MHCII expression on mock-infected cells not treated with IFN-γ. (B) Semiquantitative RT-PCR was performed using complementary DNA template prepared from mock- or wt Lm–infected BMM at 10 hpi. Treatment with IFN-γ occurred 2 h after infection. (C) RAW264.7-CIITApIV reporter cells (Fortune et al., 2004) were mock or wt Lm infected. At 2 hpi, cells received fresh media containing 0 (none) or 100 U/ml IFN-γ. Luciferase reporter activity was measured 6 h later. (D) RAW264.7 cells were transfected with a GAS-luciferase reporter construct. A stable IFN-γ–responsive transfectant (RAW-GAS.6) was treated with IFN-γ at 2 hpi with wt Lm or a hemolysin-deficient L. monocytogenes strain (ΔHly Lm). Infected and control RAW-GAS.6 cells were lysed to assay luciferase activity at 10 hpi. (E) Immunoblotting for phospho-STAT1 after IFN-γ treatment of mock-infected or wt Lm–infected cells. Cells were treated with IFN-γ at the indicated times after infection and lysed 5, 15, or 30 min later. Similar results were seen using lysates prepared from four independent experiments. For C and D, bars show SE from three independent samples. Horizontal lines represent the level of expression on uninfected cells. Error bars indicate SEM. A Student’s t test was used to calculate p-values where indicated. Experiments in A–D were repeated at least three times.

Mentions: To test whether L. monocytogenes infection might suppress macrophage responses to IFN-γ, mouse BM-derived macrophages (BMMs) were subjected to a low multiplicity (multiplicity of infection [MOI] = 1) of WT L. monocytogenes (wt Lm) 2 h before treatment with IFN-γ. 20 h later, the infected and control BMMs were harvested and cell surface MHCII expression on live-gated cells was analyzed by flow cytometry (Fig. 1 A). Mock-infected BMM treated with IFN-γ showed 50–100× higher MHCII staining than BMM not treated with IFN-γ. However, nearly 95% of this IFN-γ–induced MHCII increase was blocked in BMM cultures that had been infected with wt Lm. These data suggest that the infection either specifically impaired expression of cell surface MHCII expression or more generally impaired macrophage responsiveness to IFN-γ.


Induction of IFN-alphabeta enables Listeria monocytogenes to suppress macrophage activation by IFN-gamma.

Rayamajhi M, Humann J, Penheiter K, Andreasen K, Lenz LL - J. Exp. Med. (2010)

L. monocytogenes infection suppresses macrophage responses to IFN-γ. (A) Cell surface MHC class II (MHCII) expression on live-gated C57BL/6 BMM treated with IFN-γ after mock infection (light shading) or infection with wt Lm (dark shading) at MOI = 1. The clear histogram depicts MHCII expression on mock-infected cells not treated with IFN-γ. (B) Semiquantitative RT-PCR was performed using complementary DNA template prepared from mock- or wt Lm–infected BMM at 10 hpi. Treatment with IFN-γ occurred 2 h after infection. (C) RAW264.7-CIITApIV reporter cells (Fortune et al., 2004) were mock or wt Lm infected. At 2 hpi, cells received fresh media containing 0 (none) or 100 U/ml IFN-γ. Luciferase reporter activity was measured 6 h later. (D) RAW264.7 cells were transfected with a GAS-luciferase reporter construct. A stable IFN-γ–responsive transfectant (RAW-GAS.6) was treated with IFN-γ at 2 hpi with wt Lm or a hemolysin-deficient L. monocytogenes strain (ΔHly Lm). Infected and control RAW-GAS.6 cells were lysed to assay luciferase activity at 10 hpi. (E) Immunoblotting for phospho-STAT1 after IFN-γ treatment of mock-infected or wt Lm–infected cells. Cells were treated with IFN-γ at the indicated times after infection and lysed 5, 15, or 30 min later. Similar results were seen using lysates prepared from four independent experiments. For C and D, bars show SE from three independent samples. Horizontal lines represent the level of expression on uninfected cells. Error bars indicate SEM. A Student’s t test was used to calculate p-values where indicated. Experiments in A–D were repeated at least three times.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2822610&req=5

fig1: L. monocytogenes infection suppresses macrophage responses to IFN-γ. (A) Cell surface MHC class II (MHCII) expression on live-gated C57BL/6 BMM treated with IFN-γ after mock infection (light shading) or infection with wt Lm (dark shading) at MOI = 1. The clear histogram depicts MHCII expression on mock-infected cells not treated with IFN-γ. (B) Semiquantitative RT-PCR was performed using complementary DNA template prepared from mock- or wt Lm–infected BMM at 10 hpi. Treatment with IFN-γ occurred 2 h after infection. (C) RAW264.7-CIITApIV reporter cells (Fortune et al., 2004) were mock or wt Lm infected. At 2 hpi, cells received fresh media containing 0 (none) or 100 U/ml IFN-γ. Luciferase reporter activity was measured 6 h later. (D) RAW264.7 cells were transfected with a GAS-luciferase reporter construct. A stable IFN-γ–responsive transfectant (RAW-GAS.6) was treated with IFN-γ at 2 hpi with wt Lm or a hemolysin-deficient L. monocytogenes strain (ΔHly Lm). Infected and control RAW-GAS.6 cells were lysed to assay luciferase activity at 10 hpi. (E) Immunoblotting for phospho-STAT1 after IFN-γ treatment of mock-infected or wt Lm–infected cells. Cells were treated with IFN-γ at the indicated times after infection and lysed 5, 15, or 30 min later. Similar results were seen using lysates prepared from four independent experiments. For C and D, bars show SE from three independent samples. Horizontal lines represent the level of expression on uninfected cells. Error bars indicate SEM. A Student’s t test was used to calculate p-values where indicated. Experiments in A–D were repeated at least three times.
Mentions: To test whether L. monocytogenes infection might suppress macrophage responses to IFN-γ, mouse BM-derived macrophages (BMMs) were subjected to a low multiplicity (multiplicity of infection [MOI] = 1) of WT L. monocytogenes (wt Lm) 2 h before treatment with IFN-γ. 20 h later, the infected and control BMMs were harvested and cell surface MHCII expression on live-gated cells was analyzed by flow cytometry (Fig. 1 A). Mock-infected BMM treated with IFN-γ showed 50–100× higher MHCII staining than BMM not treated with IFN-γ. However, nearly 95% of this IFN-γ–induced MHCII increase was blocked in BMM cultures that had been infected with wt Lm. These data suggest that the infection either specifically impaired expression of cell surface MHCII expression or more generally impaired macrophage responsiveness to IFN-γ.

Bottom Line: We found that cultured macrophages infected with L. monocytogenes were refractory to IFN-gamma treatment as a result of down-regulation of the IFN-gamma receptor (IFNGR).The soluble factor responsible for these effects was identified as host IFN-alphabeta.Such cross talk permits prioritization of IFN-alphabeta-type immune responses and may contribute to the beneficial effects of IFN-beta in treatment of inflammatory diseases such as multiple sclerosis.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Jewish Health, Denver, CO 80206, USA.

ABSTRACT
Production of type I interferon (IFN; IFN-alphabeta) increases host susceptibility to Listeria monocytogenes, whereas type II IFN (IFN-gamma) activates macrophages to resist infection. We show that these opposing immunological effects of IFN-alphabeta and IFN-gamma occur because of cross talk between the respective signaling pathways. We found that cultured macrophages infected with L. monocytogenes were refractory to IFN-gamma treatment as a result of down-regulation of the IFN-gamma receptor (IFNGR). The soluble factor responsible for these effects was identified as host IFN-alphabeta. Accordingly, macrophages and dendritic cells (DCs) showed reduced IFNGR1 expression and reduced responsiveness to IFN-gamma during systemic infection of IFN-alphabeta-responsive mice. Furthermore, the increased resistance of mice lacking the IFN-alphabeta receptor (IFNAR(-/-)) to L. monocytogenes correlated with increased expression of IFN-gamma-dependent activation markers by macrophages and DCs and was reversed by depletion of IFN-gamma. Thus, IFN-alphabeta produced in response to bacterial infection and other stimuli antagonizes the host response to IFN-gamma by down-regulating the IFNGR. Such cross talk permits prioritization of IFN-alphabeta-type immune responses and may contribute to the beneficial effects of IFN-beta in treatment of inflammatory diseases such as multiple sclerosis.

Show MeSH
Related in: MedlinePlus