title: CpG-ODN promotes phagocytosis and autophagy through JNK/P38 signal pathway in Staphylococcus aureus-stimulated macrophage.
abstract: OBJECTIVE
  Phagocytic and autophagic responses are critical for effective host defense against bacterial infection. Bacterial DNA which contains unmethylated Cytosine-phosphate-Guanine (CpG) motifs can trigger a variety of defense mechanisms via Toll-like receptor 9 (TLR9). Here, we aimed to investigate the underlying mechanism of TLR9-mediated phagocytosis and autophagy in Staphylococcus aureus (S.aureus)-stimulated macrophages.
  
  
  METHODS
  The macrophage cell line RAW264.7 or primary peritoneal macrophage was pretreated with CpG-ODN and then stimulated by S. aureus, where some of them were pretreated with SP600125 or SB203580 simultaneously. The protein expressions of TLR9, MyD88, SR-A, CD36, LC3, Beclin-1, and phosphorylated level of c-Jun N-terminal kinase (JNK), P38 and extracellular-regulated protein kinase (ERK) were detected by western blotting. The phagocytosis and LC3 punctate-structures of macrophage were observed by confocal laser scanning microscope.
  
  
  RESULTS
  CpG-ODN significantly amplified S. aureus-induced phagocytosis and autophagy of RAW264.7 and TLR9(+/+) primary peritoneal macrophage as compared to that of Non-CpG treated cells, while such effect was abolished in TLR9(-/-) primary peritoneal macrophages. Meanwhile, CpG-ODN significantly enhanced S. aureus-induced phosphorylation of JNK and P38 but not ERK in RAW264.7. Specific inhibition of JNK or P38 by SP600125 or SB203580, dramatically down-regulated CpG-induced phagocytosis and autophagy in S. aureus-stimulated RAW264.7 and TLR9(+/+) primary peritoneal macrophage, while they showed no further down-regulation of phagocytosis and autophagy in TLR9(-/-) primary peritoneal macrophages.
  
  
  CONCLUSIONS
  Our data indicated that CpG-ODN activates TLR9-JNK/P38 signaling to promote phagocytosis and autophagy in S. aureus-stimulated macrophages, these findings provide novel insights into how innate immune cells defend bacterial infection via TLR9.
authors.affiliation: Anhui Geriatric Institute, The First Affiliated Hospital of Anhui Medical University, Jixi Road 218, Hefei, Anhui 230022, PR China.
authors.forename: Hui-Mei
authors.initials: HM
authors.lastname: Wu
authors.affiliation: Anhui Geriatric Institute, The First Affiliated Hospital of Anhui Medical University, Jixi Road 218, Hefei, Anhui 230022, PR China.
authors.forename: Jiong
authors.initials: J
authors.lastname: Wang
authors.affiliation: Anhui Geriatric Institute, The First Affiliated Hospital of Anhui Medical University, Jixi Road 218, Hefei, Anhui 230022, PR China.
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Anhui Geriatric Institute, The First Affiliated Hospital of Anhui Medical University, Jixi Road 218, Hefei, Anhui 230022, PR China.
authors.forename: Lei
authors.initials: L
authors.lastname: Fang
authors.affiliation: Anhui Geriatric Institute, The First Affiliated Hospital of Anhui Medical University, Jixi Road 218, Hefei, Anhui 230022, PR China.
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.affiliation: Anhui Geriatric Institute, The First Affiliated Hospital of Anhui Medical University, Jixi Road 218, Hefei, Anhui 230022, PR China. Electronic address: rongyuliu@hotmail.com.
authors.forename: Rong-Yu
authors.initials: RY
authors.lastname: Liu
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D002460:Cell Line; D048670:MAP Kinase Kinase 4 / Q000378:metabolism*; D008264:Macrophages / Q000187:drug effects* / Q000201:enzymology / Q000276:immunology / Q000382:microbiology; D051379:Mice; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology*; D010587:Phagocytosis / Q000187:drug effects*; D015398:Signal Transduction; D013211:Staphylococcus aureus / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: C408982:CPG-oligonucleotide; D009838:Oligodeoxyribonucleotides; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4
keywords: Autophagy; Bacterial defense; CpG; Macrophage; Phagocytosis; Toll-like receptor 9