Objective:To explore the effect of exosomes released by Mycobacterium tuberculosis ( Mtb) Rv1983-stimulated macrophages on tuberculosis infection and its potential mechanism. Methods:Exosomes (Rv1983-M-Exo) released by macrophages following Mtb Rv1983 stimulation were extracted by hypervelocity centrifugation and then co-cultured with uninfected macrophages. Macrophage activity was detected by prodium iodide (PI) staining. The level of lipid reactive oxygen species (ROS) was detected by lipid peroxidation fluorescence probe. The expression of ferrous ions (Fe 2+ ) and malondialdehyde (MDA) were detected by colorimetry assay. The protein expression of acyl-CoA synthetase long chain family member 4 (ACSL4) in Rv1983-M-Exo was detected by Western blot. Exosomes (Rv1983-M+ siACSL4-Exo) were isolated from Rv1983-stimulated macrophages with interfered ACSL4 expression Rv1983 and co-cultured with uninfected macrophages. The effect of exosomes on the polarization of macrophages was detected by flow cytometry and Western blot. The effects of exosomes on phagocytosis and killing ability of macrophages were analyzed by plate colony assay and BCG-phagocytosis lysosome co-localization assay. Results:Compared with macrophage-derived exosomes (M-Exo), Rv1983-M-Exo promoted ferroptosis in uninfected macrophages, manifested by increased levels of intracellular lipid ROS, MDA and Fe 2+, which were significantly inhibited by ferroptosis inhibitor Fer-1. Rv1983 induced macrophages to release exosomes with high expression of ACSL4. Interfering the expression of ACSL4 in macrophages, the concentration of ACSL4 in the Rv1983-M+ siACSL4-Exo was significantly reduced. When the Rv1983-M+ siACSL4-Exo was co-cultured with uninfected macrophages, the ferroptosis of macrophages was significantly reduced. Rv1983-M-Exo promoted M2 macrophage polarization which showed up-regulation of CD206 and Arg1 expression, and decreased the phagocytosis and killing ability of macrophages, while Rv1983-M+ siACSL4-Exo or Fer-1 in combination with Rv1983-M-Exo reduced the expression of CD206 and Arg1 in macrophages, and promoted the phagocytosis and killing ability. Conclusions:Mtb Rv1983 protein up-regulates the level of ACSL4 in the exosomes secreted by macrophages, thereby inducing ferroptosis in uninfected macrophages, causing M2 polarization of macrophages, weakening phagocytosis and killing ability, and promoting Mtb infection.

Objective:To explore the effect of exosomes released by Mycobacterium tuberculosis ( Mtb) Rv1983-stimulated macrophages on tuberculosis infection and its potential mechanism. Methods:Exosomes (Rv1983-M-Exo) released by macrophages following Mtb Rv1983 stimulation were extracted by hypervelocity centrifugation and then co-cultured with uninfected macrophages. Macrophage activity was detected by prodium iodide (PI) staining. The level of lipid reactive oxygen species (ROS) was detected by lipid peroxidation fluorescence probe. The expression of ferrous ions (Fe 2+ ) and malondialdehyde (MDA) were detected by colorimetry assay. The protein expression of acyl-CoA synthetase long chain family member 4 (ACSL4) in Rv1983-M-Exo was detected by Western blot. Exosomes (Rv1983-M+ siACSL4-Exo) were isolated from Rv1983-stimulated macrophages with interfered ACSL4 expression Rv1983 and co-cultured with uninfected macrophages. The effect of exosomes on the polarization of macrophages was detected by flow cytometry and Western blot. The effects of exosomes on phagocytosis and killing ability of macrophages were analyzed by plate colony assay and BCG-phagocytosis lysosome co-localization assay. Results:Compared with macrophage-derived exosomes (M-Exo), Rv1983-M-Exo promoted ferroptosis in uninfected macrophages, manifested by increased levels of intracellular lipid ROS, MDA and Fe 2+, which were significantly inhibited by ferroptosis inhibitor Fer-1. Rv1983 induced macrophages to release exosomes with high expression of ACSL4. Interfering the expression of ACSL4 in macrophages, the concentration of ACSL4 in the Rv1983-M+ siACSL4-Exo was significantly reduced. When the Rv1983-M+ siACSL4-Exo was co-cultured with uninfected macrophages, the ferroptosis of macrophages was significantly reduced. Rv1983-M-Exo promoted M2 macrophage polarization which showed up-regulation of CD206 and Arg1 expression, and decreased the phagocytosis and killing ability of macrophages, while Rv1983-M+ siACSL4-Exo or Fer-1 in combination with Rv1983-M-Exo reduced the expression of CD206 and Arg1 in macrophages, and promoted the phagocytosis and killing ability. Conclusions:Mtb Rv1983 protein up-regulates the level of ACSL4 in the exosomes secreted by macrophages, thereby inducing ferroptosis in uninfected macrophages, causing M2 polarization of macrophages, weakening phagocytosis and killing ability, and promoting Mtb infection.

Rats ; Animals ; Adipose Tissue, Brown/physiology* ; Adipose Tissue