Influenza A virus and TLR7 activation potentiate NOX2 oxidase-dependent ROS production in macrophages

Eunice To, Bradley R S Broughton, Keshia S Hendricks, Ross Vlahos, Stavros Selemidis

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Influenza A virus infects resident alveolar macrophages in the respiratory tract resulting in Toll like receptor 7 (TLR7) activation that triggers an inflammatory response to resolve the infection. Macrophages are also major sources of reactive oxygen species (ROS) via the NOX2-containing NADPH oxidase. Although ROS are crucial for pathogen clearance, in response to influenza A virus, ROS are touted as being culprit mediators of the lung tissue injury. The aim of the present study was to determine whether influenza A virus infection and TLR7 activation of macrophages, results in alterations in their ROS production. Here we demonstrate using immunofluorescence that influenza A virus (Hong Kong X-31 strain; H3N2) internalizes in RAW264.7 cells and mouse alveolar macrophages within 1 h, resulting in a significant enhancement in the stimulated NOX2 oxidase-dependent oxidative burst, although virus had no effect on basal ROS. The specific TLR7 agonist imiquimod (10 mug/ml) elevated basal superoxide production and, in a similar fashion to influenza A virus, enhanced NOX2 oxidase-dependent oxidative burst. By contrast, the TLR3 agonist, poly I:C (1-100 mug/ml) failed to influence the oxidative burst to NOX2 oxidase. A peptide corresponding to the region 337-348 on p47phox conjugated to a HIV-tat, designed to inhibit the phosphorylation of Ser346 on p47phox suppressed the influenza A virus- and imiquimod-induced enhancement in the oxidative burst. In conclusion, this study demonstrates for the first time that influenza A virus and TLR7 activation enhance the NOX2 oxidase-dependent oxidative burst in macrophages, which might underpin the acute lung injury to influenza A virus infection.
Original languageEnglish
Pages (from-to)940 - 947
Number of pages8
JournalFree Radical Research
Volume48
Issue number8
DOIs
Publication statusPublished - 2014

Cite this

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title = "Influenza A virus and TLR7 activation potentiate NOX2 oxidase-dependent ROS production in macrophages",
abstract = "Influenza A virus infects resident alveolar macrophages in the respiratory tract resulting in Toll like receptor 7 (TLR7) activation that triggers an inflammatory response to resolve the infection. Macrophages are also major sources of reactive oxygen species (ROS) via the NOX2-containing NADPH oxidase. Although ROS are crucial for pathogen clearance, in response to influenza A virus, ROS are touted as being culprit mediators of the lung tissue injury. The aim of the present study was to determine whether influenza A virus infection and TLR7 activation of macrophages, results in alterations in their ROS production. Here we demonstrate using immunofluorescence that influenza A virus (Hong Kong X-31 strain; H3N2) internalizes in RAW264.7 cells and mouse alveolar macrophages within 1 h, resulting in a significant enhancement in the stimulated NOX2 oxidase-dependent oxidative burst, although virus had no effect on basal ROS. The specific TLR7 agonist imiquimod (10 mug/ml) elevated basal superoxide production and, in a similar fashion to influenza A virus, enhanced NOX2 oxidase-dependent oxidative burst. By contrast, the TLR3 agonist, poly I:C (1-100 mug/ml) failed to influence the oxidative burst to NOX2 oxidase. A peptide corresponding to the region 337-348 on p47phox conjugated to a HIV-tat, designed to inhibit the phosphorylation of Ser346 on p47phox suppressed the influenza A virus- and imiquimod-induced enhancement in the oxidative burst. In conclusion, this study demonstrates for the first time that influenza A virus and TLR7 activation enhance the NOX2 oxidase-dependent oxidative burst in macrophages, which might underpin the acute lung injury to influenza A virus infection.",
author = "Eunice To and Broughton, {Bradley R S} and Hendricks, {Keshia S} and Ross Vlahos and Stavros Selemidis",
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Influenza A virus and TLR7 activation potentiate NOX2 oxidase-dependent ROS production in macrophages. / To, Eunice; Broughton, Bradley R S; Hendricks, Keshia S; Vlahos, Ross; Selemidis, Stavros.

In: Free Radical Research, Vol. 48, No. 8, 2014, p. 940 - 947.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Influenza A virus and TLR7 activation potentiate NOX2 oxidase-dependent ROS production in macrophages

AU - To, Eunice

AU - Broughton, Bradley R S

AU - Hendricks, Keshia S

AU - Vlahos, Ross

AU - Selemidis, Stavros

PY - 2014

Y1 - 2014

N2 - Influenza A virus infects resident alveolar macrophages in the respiratory tract resulting in Toll like receptor 7 (TLR7) activation that triggers an inflammatory response to resolve the infection. Macrophages are also major sources of reactive oxygen species (ROS) via the NOX2-containing NADPH oxidase. Although ROS are crucial for pathogen clearance, in response to influenza A virus, ROS are touted as being culprit mediators of the lung tissue injury. The aim of the present study was to determine whether influenza A virus infection and TLR7 activation of macrophages, results in alterations in their ROS production. Here we demonstrate using immunofluorescence that influenza A virus (Hong Kong X-31 strain; H3N2) internalizes in RAW264.7 cells and mouse alveolar macrophages within 1 h, resulting in a significant enhancement in the stimulated NOX2 oxidase-dependent oxidative burst, although virus had no effect on basal ROS. The specific TLR7 agonist imiquimod (10 mug/ml) elevated basal superoxide production and, in a similar fashion to influenza A virus, enhanced NOX2 oxidase-dependent oxidative burst. By contrast, the TLR3 agonist, poly I:C (1-100 mug/ml) failed to influence the oxidative burst to NOX2 oxidase. A peptide corresponding to the region 337-348 on p47phox conjugated to a HIV-tat, designed to inhibit the phosphorylation of Ser346 on p47phox suppressed the influenza A virus- and imiquimod-induced enhancement in the oxidative burst. In conclusion, this study demonstrates for the first time that influenza A virus and TLR7 activation enhance the NOX2 oxidase-dependent oxidative burst in macrophages, which might underpin the acute lung injury to influenza A virus infection.

AB - Influenza A virus infects resident alveolar macrophages in the respiratory tract resulting in Toll like receptor 7 (TLR7) activation that triggers an inflammatory response to resolve the infection. Macrophages are also major sources of reactive oxygen species (ROS) via the NOX2-containing NADPH oxidase. Although ROS are crucial for pathogen clearance, in response to influenza A virus, ROS are touted as being culprit mediators of the lung tissue injury. The aim of the present study was to determine whether influenza A virus infection and TLR7 activation of macrophages, results in alterations in their ROS production. Here we demonstrate using immunofluorescence that influenza A virus (Hong Kong X-31 strain; H3N2) internalizes in RAW264.7 cells and mouse alveolar macrophages within 1 h, resulting in a significant enhancement in the stimulated NOX2 oxidase-dependent oxidative burst, although virus had no effect on basal ROS. The specific TLR7 agonist imiquimod (10 mug/ml) elevated basal superoxide production and, in a similar fashion to influenza A virus, enhanced NOX2 oxidase-dependent oxidative burst. By contrast, the TLR3 agonist, poly I:C (1-100 mug/ml) failed to influence the oxidative burst to NOX2 oxidase. A peptide corresponding to the region 337-348 on p47phox conjugated to a HIV-tat, designed to inhibit the phosphorylation of Ser346 on p47phox suppressed the influenza A virus- and imiquimod-induced enhancement in the oxidative burst. In conclusion, this study demonstrates for the first time that influenza A virus and TLR7 activation enhance the NOX2 oxidase-dependent oxidative burst in macrophages, which might underpin the acute lung injury to influenza A virus infection.

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M3 - Article

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JO - Free Radical Research

JF - Free Radical Research

SN - 1071-5762

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ER -