Heme oxygenase-1 modulates ferroptosis by fine-tuning levels of intracellular iron and reactive oxygen species of macrophages in response to Bacillus Calmette-Guerin infection

Abstract

Macrophages are the host cells and the frontline defense against Mycobacterium tuberculosis (Mtb) infection, and the form of death of infected macrophages plays a pivotal role in the outcome of Mtb infections. Ferroptosis, a programmed necrotic cell death induced by overwhelming lipid peroxidation, was confirmed as one of the mechanisms of Mtb spread following infection and the pathogenesis of tuberculosis (TB). However, the mechanism underlying the macrophage ferroptosis induced by Mtb infection has not yet been fully understood. In the present study, transcriptome analysis revealed the upregulation of heme oxygenase-1 (HMOX1) and pro-ferroptosis cytokines, but downregulation of glutathione peroxidase 4 (GPX4) and other key anti-lipid peroxidation factors in the peripheral blood of both patients with extra-pulmonary tuberculosis (EPTB) and pulmonary tuberculosis (PTB). This finding was further corroborated in mice and RAW264.7 murine macrophage-like cells infected with Bacillus Calmette-Guerin (BCG). A mechanistic study further demonstrated that heme oxygenase-1 protein (HO-1) regulated the production of reactive oxygen species (ROS) and iron metabolism, and ferroptosis in BCG-infected murine macrophages. The knockdown of Hmox1 by siRNA resulted in a significant increase of intracellular ROS, Fe2+, and iron autophagy-mediated factor Ncoa4, along with the reduction of antioxidant factors Gpx4 and Fsp1 in macrophages infected with BCG. The siRNA-mediated knockdown of Hmox1 also reduced cell survival rate and increased the release of intracellular bacteria in BCG-infected macrophages. By contrast, scavenging ROS by N-acetyl cysteine led to the reduction of intracellular ROS, Fe2+, and Hmox1 concentrations, and subsequently inhibited ferroptosis and the release of intracellular BCG in RAW264.7 cells infected with BCG. These findings suggest that HO-1 is an essential regulator of Mtb-induced ferroptosis, which regulates ROS production and iron accretion to alter macrophage death against Mtb infections.

Biofilm-forming strains of P. aeruginosa and S. aureus isolated from cystic fibrosis patients differently affect inflammatory phenotype of macrophages

“…Likewise, the induction of these molecules was more pronounced in the PA57 group compared to MSSA60. Furthermore, we identified the molecular fingerprint suggesting increased ferroptosis in stimulated cells with induction of heme oxygenase 1 (HO-1) as a key marker and regulator of the process [ 35 ]. Similarly to other PCD programs, ferroptosis seems to be more induced in PA57-stimulated macrophages.…”

Host‐pathogen dialogues in different cell death modes during Mycobacterium tuberculosis infection

“…During Mtb infection, the accumulation of ROS and lipid peroxides can promote tissue damage and the spread of pathogenic bacteria. However, HO‐1 can increase the content of ferrous metals, thereby promoting the survival of Mtb 134,135 …”

Ferroptosis Is a Potential Therapeutic Target for Pulmonary Infectious Diseases

“…Meanwhile, ferroptosis-related gene suppressor of cytokine signaling 1 (SOCS1) is a biomarker for the diagnosis and treatment of MTB [96] (Table 2). A recent study found that heme oxygenase-1 (HMOX1) is an important regulator of MTB-induced ferroptosis, regulating ROS production and iron accretion, thus changing the outcome of macrophage death after MTB infection [97]. It is suggested that excess iron significantly reduces resistance to mycobacterial infection now that macrophages lose their ability to kill intracellular pathogens in a NO-mediated mechanism during iron overload [98][99][100].…”