ATF3 inhibits the inflammation induced by Mycoplasma pneumonia in vitro and in vivo.
OBJECTIVES
Activating transcription factor-3 (ATF3) is a key regulator of inflammatory responses. We aimed to investigate the effects and mechanisms of ATF3 on the inflammatory cytokines are induced by Mycoplasma pneumonia (MP).


STUDY DESIGN
RAW264.7 and mouse peritoneal macrophages were exposed to various time with or without MP infection (3, 6, 12, 24, and 48 h), and detect the expression of ATF3. Adenovirus-expression of ATF3 (Ad/ATF3) or Ad/βgal was transfected into cells which were exposed to MP for 48 h, RT-PCR and ELISA was used to evaluate the expression and secretion of TNF-α, IL-1β, IL-6, and IL-18. In addition, intravenous administration Ad/ATF3 or Ad/βgal into the mice, the secretion of inflammatory cytokines were detected using ELISA. ChIP assay was used to determine whether ATF3 can bind to the promoter of Early growth response protein 1 (Egr-1). Western blot was used to detect the expression of Egr-1 and Fyn.


RESULTS
ATF3 was increased at 3, 6, 12, and 24 h and the highest expression levels occurs in 6 h, there is no significant differences at 24 and 48 h compared with 0 h or CON group in RAW 264.7. Similar results were seen in mouse peritoneal macrophages. Overexpression of ATF3 resulted in the reduction of inflammatory cytokines. ChIP assay revealed that ATF3 can bind to the promoter of Egr-1. Overexpression of ATF3 inhibited the protein expression of Egr-1 and Fyn; conversely, ATF3-deficiency promoted the expression of Egr-1 and Fyn. Overexpression of Egr-1 reduced the anti-inflammatory action of ATF3.


CONCLUSIONS
ATF3 inhibit the expression and release of TNF-α, IL-1β, IL-6, and IL-18 induced by MP in vitro and in vivo, which is associated with its negative regulation of Egr-1/Fyn signaling pathway.
['Wang|Jing|J|0000-0003-1937-649X', 'Cheng|Wei|W|', 'Wang|Zhen|Z|', 'Xin|Lihong|L|', 'Zhang|Wen|W|']
D051700:Activating Transcription Factor 3 D000256:Adenoviridae D000818:Animals D002478:Cells, Cultured D016207:Cytokines D051766:Early Growth Response Protein 1 D005260:Female D007249:Inflammation D017737:Macrophages, Peritoneal D051379:Mice D008807:Mice, Inbred BALB C D008810:Mice, Inbred C57BL D011019:Pneumonia, Mycoplasma D011401:Promoter Regions, Genetic D051076:Proto-Oncogene Proteins c-fyn D000067996:RAW 264.7 Cells D015398:Signal Transduction
inflammation activating transcription factor-3 (ATF3) Mycoplasma pneumonia (MP)