Fig 2: GroEL induces M1 macrophage polarization via TM and IRF5 expression. (A) THP-1 cells were stimulated with 10 μM PMA for 24 h to differentiate into attached cells (M0 macrophages), then cells were transfected with TM siRNA for 24–48 h, and the TM in total cell lysate was analyzed using western blot analysis. The scramble siRNA (SC siRNA) was used as a control. (B) THP-1 cells were transfected with or without TM siRNA, followed by 10 μM PMA treatment for 24–48 h. (C) THP-1 cells were stimulated with 10 μM PMA for 24 h to differentiate into M0 macrophages. The upper panel shows M0 macrophages transfected with or without TM siRNA, followed by 1 μg/mL LPS treatment for 24–48 h. The lower panel shows M0 macrophages transfected with or without TM siRNA, followed by 25 ng/mL IL-4 plus 25 ng/mL IL-13 treatment for 24–48 h. The total proteins were extracted, and western blot analyses of TM, CD68, CD86, and CD206 expressions were performed. (D) M0 macrophages were transfected with or without TM siRNA, followed by 10 μg/mL GroEL treatment for 24–48 h. (E) The upper panel shows M0 macrophages transfected with or without TM siRNA, followed by 1 μg/mL LPS or 10 μg/mL GroEL treatment for 48 h. The lower panel shows M0 macrophages transfected with or without TM siRNA, followed by 25 ng/mL IL-4 plus 25 ng/mL IL-13 combined with or without 10 μg/mL GroEL treatment. The total proteins were extracted, and western blot analyses of IRF5 or IRF4 expressions were performed. Treatment with 10 μg/mL GST for 48 h was used to exclude the effect of the tag protein on the recombinant GroEL protein. The expression of total β-actin was used as a loading control in this study.