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Updated: Aug 1, 2025
Isolation and In Vitro Culture of Murine and Human Alveolar Macrophages
Published on: April 20, 2018
Pseudomonas-dominant microbiome elicits sustained IL-1β upregulation in alveolar macrophages from lung transplant
Noel Britton1, Andres Villabona-Rueda1, Samantha A Whiteside2
1Division of Pulmonary and Critical Care, School of Medicine, Johns Hopkins University, Baltimore, Maryland.
Background:
Isolation of Pseudomonas aeruginosa (PsA) is associated with increased BAL (bronchoalveolar lavage) inflammation and lung allograft injury in lung transplant recipients (LTR). However, the effect of PsA on macrophage responses in this population is incompletely understood. We examined human alveolar macrophage (AMΦ) responses to PsA and Pseudomonas dominant microbiome in healthy LTR.
Methods:
We stimulated THP-1 derived macrophages (THP-1MΦ) and human AMΦ from LTR with different bacteria and LTR BAL derived microbiome characterized as Pseudomonas-dominant. Macrophage responses were assessed by high dimensional flow cytometry, including their intracellular production of cytokines (TNF-α, IL-6, IL-8, IL-1β, IL-10, IL-1RA, and TGF-β). Pharmacological inhibitors were utilized to evaluate the role of the inflammasome in PsA-macrophage interaction.
Results:
We observed upregulation of pro-inflammatory cytokines (TNF-α, IL-6, IL-8, IL-1β) following stimulation by PsA compared to other bacteria (Staphylococcus aureus (S.Aur), Prevotella melaninogenica, Streptococcus pneumoniae) in both THP-1MΦ and LTR AMΦ, predominated by IL-1β. IL-1β production from THP-1MΦ was sustained after PsA stimulation for up to 96 hours and 48 hours in LTR AMΦ. Treatment with the inflammasome inhibitor BAY11-7082 abrogated THP-1MΦ IL-1β production after PsA exposure. BAL Pseudomonas-dominant microbiota elicited an increased IL-1β, similar to PsA, an effect abrogated by the addition of antibiotics.
Conclusion:
PsA and PsA-dominant lung microbiota induce sustained IL-1β production in LTR AMΦ. Pharmacological targeting of the inflammasome reduces PsA-macrophage-IL-1β responses, underscoring their use in lung transplant recipients.
Insights
Pseudomonas aeruginosa (PsA) and PsA-dominant lung microbiota trigger sustained IL-1β release from lung transplant recipient alveolar macrophages. Targeting the inflammasome effectively reduces these PsA-induced responses, offering potential therapeutic strategies for lung transplant recipients.
Area of Science:
- Immunology
- Microbiology
- Transplantation Science
Background:
- Pseudomonas aeruginosa (PsA) isolation correlates with increased lung allograft inflammation and injury in lung transplant recipients (LTR).
- The impact of PsA on macrophage responses in LTR is not fully understood.
- This study investigates human alveolar macrophage (AMΦ) responses to PsA and Pseudomonas-dominant microbiomes in LTR.
Purpose of the Study:
- To analyze human alveolar macrophage (AMΦ) responses to Pseudomonas aeruginosa (PsA).
- To investigate the effect of PsA-dominant lung microbiota on AMΦ.
- To explore the role of the inflammasome in PsA-macrophage interactions in lung transplant recipients (LTR).
Main Methods:
- THP-1 derived macrophages (THP-1MΦ) and LTR AMΦ were stimulated with bacteria and LTR BAL-derived microbiome.
- Macrophage responses, including intracellular cytokine production (TNF-α, IL-6, IL-8, IL-1β, IL-10, IL-1RA, TGF-β), were measured using high-dimensional flow cytometry.
- Pharmacological inflammasome inhibitors were used to assess the inflammasome's role in PsA-macrophage interactions.
Main Results:
- PsA stimulation led to increased pro-inflammatory cytokine production (TNF-α, IL-6, IL-8, IL-1β) in both THP-1MΦ and LTR AMΦ, with IL-1β predominating.
- Sustained IL-1β production was observed for up to 96 hours in THP-1MΦ and 48 hours in LTR AMΦ post-PsA stimulation.
- Inflammasome inhibition (BAY11-7082) abrogated IL-1β production, and PsA-dominant microbiota induced similar IL-1β responses, which were reduced by antibiotics.
Conclusions:
- PsA and PsA-dominant lung microbiota induce sustained IL-1β production in LTR AMΦ.
- Targeting the inflammasome effectively reduces PsA-induced IL-1β responses in macrophages.
- These findings highlight the potential therapeutic value of inflammasome inhibitors for lung transplant recipients.
