title: Allograft inflammatory factor-1 (AIF-1) is crucial for the survival and pro-inflammatory activity of macrophages.
abstract: Our previous studies revealed that macrophages played an important role in linking injury, inflammatory and immune response in small-for-size liver transplantation. However, the molecular basis that promoted macrophage activation was not clear. In the present study, we explored the potential role of allograft inflammatory factor-1 (AIF-1) in mediating the survival and pro-inflammatory activity of macrophages in a macrophage cell line. First, the expression of AIF-1 was investigated with the stimulation of pro-inflammatory cytokines and anti-inflammatory treatment. Second, the level of inducible nitric oxide synthase (iNOS) and the survival and migration activity of macrophages were determined with the alterations of AIF-1 expression. Finally, a potential molecule that regulated AIF-1 expression was identified by the proteomic approach. The macrophage cell line expressed a certain level of endogenous AIF-1, which could be enhanced by pro-inflammatory cytokines IL-1beta or tumor necrosis factor-alpha and suppressed by anti-inflammatory drug sodium salicylate. AIF-1 augmentation induced by AIF-1/PCDNA3.1(+) transfection enhanced the levels of iNOS and monocyte chemoattractant protein-1, and promoted the cell migration. On the other hand, suppression of AIF-1 expression by AIF-1/short interference RNA (siRNA) inhibited iNOS production, induced macrophage cell apoptosis and blocked the cell migration. Using two-dimensional electrophoresis, a disintegrin and metalloproteinase domain 3 (ADAM3) was identified after AIF-1/siRNA transfection. Transfection of ADAM3/PCDNA3.1(+) up-regulated the expression of AIF-1 and iNOS, whereas suppression of ADAM3 expression down-regulated AIF-1 and iNOS expression. In conclusion, AIF-1 played an important role in the survival and pro-inflammatory activity of macrophages, and ADAM3 might be an upstream molecule that regulated AIF-1 expression.
authors.affiliation: Centre for the Study of Liver Disease and Department of Surgery, L9-41 Faculty of Medicine Building, University of Hong Kong, 21 Sassoon Road, Pokfulam, Hong Kong, China. zfyang@hkucc.hku.hk
authors.forename: Zhen Fan
authors.initials: ZF
authors.lastname: Yang
authors.forename: David W
authors.initials: DW
authors.lastname: Ho
authors.forename: Chi Keung
authors.initials: CK
authors.lastname: Lau
authors.forename: Chi Tat
authors.initials: CT
authors.lastname: Lam
authors.forename: Ching Tung
authors.initials: CT
authors.lastname: Lum
authors.forename: Ronnie T P
authors.initials: RT
authors.lastname: Poon
authors.forename: Sheung Tat
authors.initials: ST
authors.lastname: Fan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000276:immunology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D007375:Interleukin-1 / Q000276:immunology / Q000494:pharmacology; D016031:Liver Transplantation; D008262:Macrophage Activation / Q000235:genetics / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D008840:Microfilament Proteins; D052247:Nitric Oxide Synthase Type II / Q000276:immunology*; D034741:RNA, Small Interfering / Q000235:genetics / Q000276:immunology; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology / Q000494:pharmacology
chemical_list: C100745:Aif1 protein, rat; D002135:Calcium-Binding Proteins; D007375:Interleukin-1; D008840:Microfilament Proteins; D034741:RNA, Small Interfering; D014409:Tumor Necrosis Factor-alpha; D052247:Nitric Oxide Synthase Type II