Figure 3. Overexpression of Klotho suppresses the IS-induced inflammatory response in macrophages by stimulating M2 polarization. (A) THP-1 cells were exposed to PMA (160 nM) for 48 h, incubated in PMA-free medium for 24 h, and then transfected with the Klotho expression plasmid for 24 h. Klotho expression in cells was evaluated by western blotting. (B) Klotho expression was normalized to GAPDH. (C–F) THP-1 cells were exposed to PMA (160 nM) for 48 h, incubated in PMA-free medium for 24 h. Subsequently, cells were transfected with Klotho expression plasmid or treated with 2 mM IS for 24 h respectively. Meanwhile, cells were transfected with Klotho expression plasmid for 24 h in the presence of 2 mM IS. The levels of IL-10, IL-6, TNFα, and IL-1β in cells were evaluated by ELISA. (G) The expression of iNOS and Arginase1 in cells was analyzed by western blotting. (H) The expression of iNOS and Arginase1 in cells was normalized to GAPDH. (I) Representative FACS plots for HLA-DR, a marker of M1 macrophages, and CD206, a marker of M2 macrophages. (J) The percentages of HLA-DR- and CD206+ cells were detected by FACS. *P < 0.05 and **P < 0.01.