Alveolar macrophage apoptosis-associated bacterial killing helps prevent murine pneumonia

Julie A Preston; Martin A Bewley; Helen M Marriott; A McGarry Houghton; Mohamed Mohasin; Jamil Jubrail; Lucy Morris; Yvonne L Stephenson; Simon Cross; David R Greaves; Ruth W Craig; Nico van Rooijen; Colin D Bingle; Robert C Read; Timothy J Mitchell; Moira K. B. Whyte; Steven D Shapiro; David H. Dockrell

doi:10.1164/rccm.201804-0646OC

Alveolar macrophage apoptosis-associated bacterial killing helps prevent murine pneumonia

Julie A Preston, Martin A Bewley, Helen M Marriott, A McGarry Houghton, Mohamed Mohasin, Jamil Jubrail, Lucy Morris, Yvonne L Stephenson, Simon Cross, David R Greaves, Ruth W Craig, Nico van Rooijen, Colin D Bingle, Robert C Read, Timothy J Mitchell, Moira K. B. Whyte, Steven D Shapiro, David H. Dockrell

Research output: Contribution to journal › Article › peer-review

Abstract

Rationale: Antimicrobial resistance challenges therapy of pneumonia. Enhancing macrophage microbicidal responses would combat this problem but is limited by our understanding of how alveolar macrophages (AM) kill bacteria.

Objectives: To define the role and mechanism of AM apoptosis-associated bacterial killing in the lung.

Methods: We generated a unique CD68.hMcl-1 transgenic mouse with macrophage-specific over-expression of the human anti-apoptotic Mcl-1 protein, a factor upregulated in AM from patients at increased risk of community-acquired pneumonia, to address the requirement for apoptosis-associated killing.

Measurements and Main Results: Wild-type and transgenic macrophages demonstrated comparable ingestion and initial phagolysosomal killing of bacteria. Continued ingestion (for > 12 h) overwhelmed initial killing and a second late-phase microbicidal response killed viable bacteria in wild-type macrophages, but this response was blunted in CD68.hMcl-1 transgenic macrophages. The late-phase of bacterial killing required both caspase-induced generation of mitochondrial reactive oxygen species (mROS) and nitric oxide (NO), whose peak generation coincided with the late-phase of killing. The CD68.hMcl-1 transgene prevented mROS but not NO generation. Apoptosis-associated killing enhanced pulmonary clearance of Streptococcus pneumoniae and Haemophilus influenzae in wild-type but not CD68.hMcl-1 transgenic mice. Bacterial clearance was enhanced in vivo in CD68.hMcl-1 transgenic mice by reconstitution of apoptosis with BH3 mimetics or clodronate-encapsulated liposomes. Apoptosis-associated killing was not activated during Staphylococcus aureus lung infection.

Conclusions: Mcl-1 upregulation prevents macrophage apoptosis-associated killing and establishes that apoptosis-associated killing is required to allow AM to clear ingested bacteria. Engagement of macrophage apoptosis should be investigated as a novel host-based antimicrobial strategy.

Original language	English
Pages (from-to)	84–97
Number of pages	14
Journal	American Journal of Respiratory and Critical Care Medicine
Volume	200
Issue number	1
Early online date	16 Jan 2019
DOIs	https://doi.org/10.1164/rccm.201804-0646OC
Publication status	Published - 1 Jul 2019

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David Dockrell
- Deanery of Clinical Sciences - Chair of Infection Medicine
- Centre for Inflammation Research - Chair of Infection Medicine
Person: Academic: Research Active

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Preston, J. A., Bewley, M. A., Marriott, H. M., Houghton, A. M., Mohasin, M., Jubrail, J., Morris, L., Stephenson, Y. L., Cross, S., Greaves, D. R., Craig, R. W., van Rooijen, N., Bingle, C. D., Read, R. C., Mitchell, T. J., Whyte, M. K. B., Shapiro, S. D., & Dockrell, D. H. (2019). Alveolar macrophage apoptosis-associated bacterial killing helps prevent murine pneumonia. American Journal of Respiratory and Critical Care Medicine, 200(1), 84–97. https://doi.org/10.1164/rccm.201804-0646OC

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title = "Alveolar macrophage apoptosis-associated bacterial killing helps prevent murine pneumonia",

abstract = "Rationale: Antimicrobial resistance challenges therapy of pneumonia. Enhancing macrophage microbicidal responses would combat this problem but is limited by our understanding of how alveolar macrophages (AM) kill bacteria.Objectives: To define the role and mechanism of AM apoptosis-associated bacterial killing in the lung.Methods: We generated a unique CD68.hMcl-1 transgenic mouse with macrophage-specific over-expression of the human anti-apoptotic Mcl-1 protein, a factor upregulated in AM from patients at increased risk of community-acquired pneumonia, to address the requirement for apoptosis-associated killing.Measurements and Main Results: Wild-type and transgenic macrophages demonstrated comparable ingestion and initial phagolysosomal killing of bacteria. Continued ingestion (for > 12 h) overwhelmed initial killing and a second late-phase microbicidal response killed viable bacteria in wild-type macrophages, but this response was blunted in CD68.hMcl-1 transgenic macrophages. The late-phase of bacterial killing required both caspase-induced generation of mitochondrial reactive oxygen species (mROS) and nitric oxide (NO), whose peak generation coincided with the late-phase of killing. The CD68.hMcl-1 transgene prevented mROS but not NO generation. Apoptosis-associated killing enhanced pulmonary clearance of Streptococcus pneumoniae and Haemophilus influenzae in wild-type but not CD68.hMcl-1 transgenic mice. Bacterial clearance was enhanced in vivo in CD68.hMcl-1 transgenic mice by reconstitution of apoptosis with BH3 mimetics or clodronate-encapsulated liposomes. Apoptosis-associated killing was not activated during Staphylococcus aureus lung infection.Conclusions: Mcl-1 upregulation prevents macrophage apoptosis-associated killing and establishes that apoptosis-associated killing is required to allow AM to clear ingested bacteria. Engagement of macrophage apoptosis should be investigated as a novel host-based antimicrobial strategy.",

author = "Preston, {Julie A} and Bewley, {Martin A} and Marriott, {Helen M} and Houghton, {A McGarry} and Mohamed Mohasin and Jamil Jubrail and Lucy Morris and Stephenson, {Yvonne L} and Simon Cross and Greaves, {David R} and Craig, {Ruth W} and {van Rooijen}, Nico and Bingle, {Colin D} and Read, {Robert C} and Mitchell, {Timothy J} and Whyte, {Moira K. B.} and Shapiro, {Steven D} and Dockrell, {David H.}",

year = "2019",

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day = "1",

doi = "10.1164/rccm.201804-0646OC",

language = "English",

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journal = "American Journal of Respiratory and Critical Care Medicine",

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Preston, JA, Bewley, MA, Marriott, HM, Houghton, AM, Mohasin, M, Jubrail, J, Morris, L, Stephenson, YL, Cross, S, Greaves, DR, Craig, RW, van Rooijen, N, Bingle, CD, Read, RC, Mitchell, TJ, Whyte, MKB, Shapiro, SD & Dockrell, DH 2019, 'Alveolar macrophage apoptosis-associated bacterial killing helps prevent murine pneumonia', American Journal of Respiratory and Critical Care Medicine, vol. 200, no. 1, pp. 84–97. https://doi.org/10.1164/rccm.201804-0646OC

TY - JOUR

T1 - Alveolar macrophage apoptosis-associated bacterial killing helps prevent murine pneumonia

AU - Preston, Julie A

AU - Bewley, Martin A

AU - Marriott, Helen M

AU - Houghton, A McGarry

AU - Mohasin, Mohamed

AU - Jubrail, Jamil

AU - Morris, Lucy

AU - Stephenson, Yvonne L

AU - Cross, Simon

AU - Greaves, David R

AU - Craig, Ruth W

AU - van Rooijen, Nico

AU - Bingle, Colin D

AU - Read, Robert C

AU - Mitchell, Timothy J

AU - Whyte, Moira K. B.

AU - Shapiro, Steven D

AU - Dockrell, David H.

PY - 2019/7/1

Y1 - 2019/7/1

N2 - Rationale: Antimicrobial resistance challenges therapy of pneumonia. Enhancing macrophage microbicidal responses would combat this problem but is limited by our understanding of how alveolar macrophages (AM) kill bacteria.Objectives: To define the role and mechanism of AM apoptosis-associated bacterial killing in the lung.Methods: We generated a unique CD68.hMcl-1 transgenic mouse with macrophage-specific over-expression of the human anti-apoptotic Mcl-1 protein, a factor upregulated in AM from patients at increased risk of community-acquired pneumonia, to address the requirement for apoptosis-associated killing.Measurements and Main Results: Wild-type and transgenic macrophages demonstrated comparable ingestion and initial phagolysosomal killing of bacteria. Continued ingestion (for > 12 h) overwhelmed initial killing and a second late-phase microbicidal response killed viable bacteria in wild-type macrophages, but this response was blunted in CD68.hMcl-1 transgenic macrophages. The late-phase of bacterial killing required both caspase-induced generation of mitochondrial reactive oxygen species (mROS) and nitric oxide (NO), whose peak generation coincided with the late-phase of killing. The CD68.hMcl-1 transgene prevented mROS but not NO generation. Apoptosis-associated killing enhanced pulmonary clearance of Streptococcus pneumoniae and Haemophilus influenzae in wild-type but not CD68.hMcl-1 transgenic mice. Bacterial clearance was enhanced in vivo in CD68.hMcl-1 transgenic mice by reconstitution of apoptosis with BH3 mimetics or clodronate-encapsulated liposomes. Apoptosis-associated killing was not activated during Staphylococcus aureus lung infection.Conclusions: Mcl-1 upregulation prevents macrophage apoptosis-associated killing and establishes that apoptosis-associated killing is required to allow AM to clear ingested bacteria. Engagement of macrophage apoptosis should be investigated as a novel host-based antimicrobial strategy.

AB - Rationale: Antimicrobial resistance challenges therapy of pneumonia. Enhancing macrophage microbicidal responses would combat this problem but is limited by our understanding of how alveolar macrophages (AM) kill bacteria.Objectives: To define the role and mechanism of AM apoptosis-associated bacterial killing in the lung.Methods: We generated a unique CD68.hMcl-1 transgenic mouse with macrophage-specific over-expression of the human anti-apoptotic Mcl-1 protein, a factor upregulated in AM from patients at increased risk of community-acquired pneumonia, to address the requirement for apoptosis-associated killing.Measurements and Main Results: Wild-type and transgenic macrophages demonstrated comparable ingestion and initial phagolysosomal killing of bacteria. Continued ingestion (for > 12 h) overwhelmed initial killing and a second late-phase microbicidal response killed viable bacteria in wild-type macrophages, but this response was blunted in CD68.hMcl-1 transgenic macrophages. The late-phase of bacterial killing required both caspase-induced generation of mitochondrial reactive oxygen species (mROS) and nitric oxide (NO), whose peak generation coincided with the late-phase of killing. The CD68.hMcl-1 transgene prevented mROS but not NO generation. Apoptosis-associated killing enhanced pulmonary clearance of Streptococcus pneumoniae and Haemophilus influenzae in wild-type but not CD68.hMcl-1 transgenic mice. Bacterial clearance was enhanced in vivo in CD68.hMcl-1 transgenic mice by reconstitution of apoptosis with BH3 mimetics or clodronate-encapsulated liposomes. Apoptosis-associated killing was not activated during Staphylococcus aureus lung infection.Conclusions: Mcl-1 upregulation prevents macrophage apoptosis-associated killing and establishes that apoptosis-associated killing is required to allow AM to clear ingested bacteria. Engagement of macrophage apoptosis should be investigated as a novel host-based antimicrobial strategy.

U2 - 10.1164/rccm.201804-0646OC

DO - 10.1164/rccm.201804-0646OC

M3 - Article

C2 - 30649895

SN - 1073-449X

VL - 200

SP - 84

EP - 97

JO - American Journal of Respiratory and Critical Care Medicine

JF - American Journal of Respiratory and Critical Care Medicine

IS - 1

ER -

Alveolar macrophage apoptosis-associated bacterial killing helps prevent murine pneumonia

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