Related Experiment Video
Updated: Jul 16, 2026
Generation and Multi-phenotypic High-content Screening of Coxiella burnetii Transposon Mutants
Published on: May 13, 2015
Coxiella burnetii strains elicit distinct inflammatory responses in human macrophages
Madhur Sachan1, Amanda Dragan2, Het Adhvaryu2
1Department of Medicine, Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA 02115.
Abstract:
Coxiella burnetii, the causative agent of human Q fever, subverts macrophage antimicrobial functions to establish an intracellular replicative niche. To better understand the host-pathogen interactions, we investigated the transcriptional responses of human alveolar macrophages (hAMs) infected with virulent (NMI, G), attenuated (NMII), and avirulent (Dugway) strains of C. burnetii. RNA sequencing analysis revealed that all strains activated proinflammatory pathways, particularly IL-17 signaling, though the magnitude and nature of the response varied by strain. Dugway infection induced the most robust transcriptional response and consistent M1-like macrophage polarization, while responses to NMI and NMII were more variable. Cytokine assays confirmed significant secretion of effectors downstream of IL-17 signaling, but only at later stages of infection. Single-cell RNA sequencing further revealed heterogeneity in macrophage response to C. burnetii infection, with distinct subpopulations exhibiting divergent inflammatory profiles. These findings highlight the complexity of macrophage responses to C. burnetii and underscore the importance of strain-specific and cell-specific factors in shaping host immunity. Understanding these dynamics may inform the development of targeted therapies for Q fever.
Insights
Coxiella burnetii causes Q fever by disrupting macrophage defenses. Different bacterial strains elicit varied immune responses in human alveolar macrophages, impacting inflammation and polarization.
Area of Science:
- Immunology
- Microbiology
- Genomics
Background:
- Coxiella burnetii is the bacterium responsible for Q fever.
- It infects macrophages, subverting their antimicrobial functions to replicate intracellularly.
- Understanding host-pathogen interactions is crucial for Q fever treatment.
Purpose of the Study:
- To investigate the transcriptional responses of human alveolar macrophages (hAMs) upon infection with different C. burnetii strains.
- To elucidate the impact of virulent, attenuated, and avirulent C. burnetii strains on macrophage immune signaling.
- To explore the heterogeneity of macrophage responses at a single-cell level.
Main Methods:
- RNA sequencing (RNA-seq) was employed to analyze transcriptional changes in hAMs.
- Cytokine assays were performed to measure the secretion of inflammatory mediators.
- Single-cell RNA sequencing (scRNA-seq) was utilized to assess cellular heterogeneity.
Main Results:
- All C. burnetii strains induced proinflammatory pathways, notably IL-17 signaling, with strain-dependent variations.
- The avirulent Dugway strain elicited the strongest transcriptional response and M1-like macrophage polarization.
- Single-cell analysis revealed diverse inflammatory profiles among hAM subpopulations responding to C. burnetii.
Conclusions:
- Macrophage responses to C. burnetii infection are complex and strain-specific.
- Cell-specific factors significantly influence the host immune landscape during Q fever.
- These insights may guide the development of targeted Q fever therapies.
More Related Videos
10:29Applying Fluorescence Resonance Energy Transfer FRET to Examine Effector Translocation Efficiency by Coxiella burnetii during siRNA Silencing
Published on: July 6, 2016
08:34Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages
Published on: February 22, 2017
