Modulating ferroptosis and mycobactericidal activity in lung epithelial cells via YY1/iNOS pathway.

Background: Mycobacterium tuberculosis infection triggers various forms of host cell death, including ferroptosis in lung epithelial cells; YY1, a critical transcription factor, plays a pivotal role in regulating ferroptosis, however, the underlying mechanisms are not fully understood.

Methods: To investigate Mycobacterium marinum (M.marinum) infection in lung epithelial cells A549 and H1299, we utilized flow cytometry to evaluate cell death and measure reactive oxygen species (ROS). Colony-forming unit (CFU) assays determined the intracellular bacterial load. Ferroptosis was analyzed using a specific detection kit to measure malondialdehyde (MDA) and glutathione (GSH) levels. The interaction between the transcription factor YY1 and the iNOS promoter was assessed through a dual-luciferase reporter assay.

Results: M.marinum induced ferroptosis in lung epithelial cells through invasion. This effect is most pronounced at 8 h of infection and decreases over time but increased with a higher multiplicity of infection (MOI). YY1 knockdown decreases the expression of SLC7A11 and GPX4, attenuates cellular ferroptosis, while YY1 overexpression has the opposite phenomenon, enhancing the expression of bactericidal molecules such as iNOS and MPEG1, thereby markedly reducing the intracellular bacterial load. We identified substantial binding of YY1 to the iNOS promoter region (-655 to -1018 bp), enhancing mycobactericidal activity in YY1-overexpressing cells.

Conclusions: Our study demonstrates that YY1 inhibits ferroptosis induced by Mycobacterium marinum infection and reduces intracellular bacterial proliferation in lung epithelial cells. These findings provide a crucial basis for developing anti-tuberculosis therapies that target YY1 modulation, potentially offering new clinical avenues for the treatment of tuberculosis.