Activating transcription factor 3 involved in Pseudomonas aeruginosa PAO1-induced macrophage senescence

Abstract

Pseudomonas aeruginosa (PA) is one of the most prevalent pathogens that cause nosocomial infection in critical patients. Previously, we reported PA induced macrophage to senescence under the circumstance of infection. As an oxidative stress responsiveness element, activating transcription factor 3 (ATF3) might be involved in the macrophage senescence process. To test this presumption, we manipulated the expression of ATF3 in macrophage by using a PAO1 infection system. In the present study, ATF3 expression in macrophage was increased, following the duration and colony counts of PAO1 infection. Knockdown of ATF3 in macrophage resulted in increased percentage of senescent macrophage under PAO1 infection, while overexpressing ATF3 partly blocked PAO1-induced macrophage senescence. In accordance with the senescent phenotype, elevated reactive oxygen species (ROS) production was shown in ATF3 knockdown macrophages. Also, capacity of phagocytosis was also affected by manipulation of ATF3 expression in macrophages, and increased phagocytosed fluorescent beads was found in ATF3 knockdown macrophage. ATF3 might regulate the senescence process through influence on NF-κB translocation. During infection, the overexpression or downregulation of ATF3 in macrophage negatively modulated the translocation of NF-κB p65 and its phosphorylation at Ser-536. As a result, IL-6 and TNFα was elevated, while IL-10 decreased in case of ATF3 knockdown. In conclusion, ATF3 negatively regulates NF-κB translocation and activation, and participates in PA-induced macrophage senescence. As oxidative stress and inflammation induced element, ATF3 may modulate macrophage-related host defense.