Fig. 4: Senescent cells (SC) induce senescence in macrophages.
A Schematic of the in vitro experimental protocol. B, C: Immunofluorescence staining of Ki67 and quantitative analysis of Ki67+ cells. The number of Ki67+ cells decreased after co-culture with senescent human renal proximal tubular epithelial cells (HRPTEpiC) (senescent cells, SC). Scale bar: 100 µm (B). The data are mean ± SD (n = 3/group). D–H: The effects of IFITM-3 and ITGB-3 on macrophage senescence. IFITM3 and ITGB3 were manipulated in SC HRPTEpiC and macrophages, respectively. Macrophages were subsequently collected for Western blot analysis of senescence markers p21Cip1/Waf1, p53, p-p53.S15, and γ-H2AX. Silencing ITGB3 or IFITM3 individually using siRNA reduced the expression of these senescence markers. However, this blunting effect was mitigated when IFITM3 was overexpressed in HRPTEpiC, indicating that IFITM3 plays a critical role in maintaining senescence signaling despite ITGB3 knockdown. Data are mean ± SD (n = 3/group). *P < 0.05 vs. Normal control (NC) and Non-SC groups; #P < 0.05 vs. SC group; and P < 0.05 vs. SC + IFITM3 over-expressing groups. I–K: Relative mRNA expression of the senescence markers p16INK-4a, p21Cip1/Waf1, and p53 increased in macrophages co-incubated with senescent cells. β-actin was used as loading control. Data are mean ± SD (n = 3/group). *P < 0.05 vs. Normal.
