Influenza Coinfection Impairs Human Immune Control of Mycobacterial Growth, Increasing TB Risk
Background
Mycobacterium tuberculosis infection is a dynamic process, with clinical outcomes reflecting complex host-pathogen interactions. Progression from contained infection to active tuberculosis (TB) disease is a significant public health challenge. Epidemiological and animal studies have suggested influenza coinfection as a risk factor for this progression, yet human studies directly demonstrating this immunological impairment have been lacking. Understanding these interactions is crucial for identifying novel preventative strategies and improving outcomes in high-prevalence populations.
Study Design
Researchers utilized a human influenza challenge study to investigate the impact of influenza coinfection on mycobacterial control. They employed a whole blood luminescent mycobacterial growth inhibition assay to measure immunological control of mycobacterial growth in subjects' blood. Before and after influenza infection, transcriptome-wide RNA sequencing, cytokine, and cellular analyses were performed to identify changes in immune pathways. The study design focused on within-subject comparisons to assess the direct effects of influenza infection on subsequent immune responses to mycobacteria.
Results
Influenza infection significantly reduced the immunological control of mycobacterial growth in human subjects. The study revealed that innate immune pathways, including type 1 interferon signalling, were activated by influenza. However, this activation was accompanied by a reduced subsequent responsiveness of these pathways to mycobacteria. Specifically, multiple genes' responses to BCG lux infection were found to be repressed following influenza coinfection. This suggests a direct impairment of the immune mechanisms critical for containing mycobacterial growth. The findings highlight a novel mechanism by which viral infections can compromise host defense against bacterial pathogens. > Influenza infection reduces immunological control of mycobacterial growth and impairs innate immune responses, potentially increasing the risk of tuberculosis (TB) disease.
Key Findings
- Influenza infection reduces human immunological control of mycobacterial growth.
- Influenza activates innate immune pathways, including
type 1 interferon signalling. - Influenza reduces subsequent immune responsiveness to mycobacteria.
- Multiple genes' responses to
BCG lux infectionare repressed by influenza coinfection. - Influenza may be a risk factor for tuberculosis (TB) disease progression.
Why It Matters
This research provides critical human-level evidence that influenza infection directly compromises the immune system's ability to control Mycobacterium tuberculosis, suggesting it may be a significant risk factor for tuberculosis (TB) disease progression. Influenza vaccination could offer a practical and accessible strategy to protect high-risk, high-prevalence populations against TB disease, beyond its direct benefits against influenza itself. This finding emphasizes the interconnectedness of viral and bacterial immunity, suggesting that public health interventions targeting one pathogen can have broader, beneficial impacts on others. Clinicians and public health officials should consider influenza vaccination as a potential tool in TB prevention strategies.
influenza
mycobacterium-tuberculosis
tuberculosis
coinfection
innate-immunity
interferon