Affiliation:
1. Department of Laboratory Medicine, Second Medical Center and National Clinical Research Center for Geriatric Diseases, Chinese People’s Liberation Army General Hospital
2. Laboratory of Toxicant Analysis, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences
3. Department of Clinical Laboratory, Air Force Medical Center , Beijing , China
Abstract
Abstract
Background
Tuberculosis (TB), predominantly caused by Mycobacterium tuberculosis (MTB) infection, remains a prominent global health challenge. Macrophages are the frontline defense against MTB, relying on autophagy for intracellular bacterial clearance. However, MTB can combat and evade autophagy, and it influences macrophage polarization, facilitating immune evasion and promoting infection. We previously found that heparin-binding hemagglutinin (HBHA) inhibits autophagy in A549 cells; however, its role in macrophage autophagy and polarization remains unclear.
Methods
Bacterial cultures, cell cultures, Western blotting, immunofluorescence, macrophage infection assays, siRNA knockdown, and enzyme-linked immunosorbent assay were used to investigate HBHA's impact on macrophages and its relevance in Mycobacterium infection.
Results
HBHA inhibited macrophage autophagy. Expression of recombinant HBHA in Mycobacterium smegmatis (rMS-HBHA) inhibited autophagy, promoting bacterial survival within macrophages. Conversely, HBHA knockout in the Mycobacterium bovis bacillus Calmette-Guérin (BCG) mutant (BCG-ΔHBHA) activated autophagy and reduced bacterial survival. Mechanistic investigations revealed that HBHA may inhibit macrophage autophagy through the Toll-like receptor 4–dependent PI3K-AKT-mTOR signaling pathway. Furthermore, HBHA induced macrophage M2 polarization.
Conclusions
Mycobacterium may exploit HBHA to suppress the antimicrobial immune response in macrophages, facilitating intracellular survival and immune evasion through autophagy inhibition and M2 polarization induction. Our findings may help identify novel therapeutic targets and develop more effective treatments against MTB infection.
Funder
National Natural Science Foundation of China
Publisher
Oxford University Press (OUP)
Cited by
1 articles.
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