title: Differential regulation of TNF-alpha production by listeriolysin-producing versus nonproducing strains of Listeria monocytogenes.
abstract: Only Listeria monocytogenes that produce listeriolysin O (LLO) elicit protective immunity. Given the importance of tumor necrosis factor alpha (TNF-alpha) in anti-Listeria immunity, we have investigated TNF-alpha production by macrophages after they ingested live LLO-producing compared to LLO-non-producing bacteria. We used two genetically engineered strains of Listeria that differed only in their ability (Ly+) or inability (Ly-) to produce LLO. Ly+ and Ly- caused the same kinetics of increased mRNA abundance for TNF-alpha during the first 90 min after phagocytosis. However, only Ly+ caused sustained transcription of TNF-alpha mRNA, and this may account for the increased release of TNF-alpha. The transcriptional inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) prevented the sustained abundance of cytokine mRNA 20 h after ingestion of Ly+. In addition, nuclear run-on assays indicated sustained transcription of TNF-alpha genes only after ingestion of Ly+. LLO itself was not responsible for the ability of Ly+ to stimulate the sustained transcription of the TNF-alpha genes. Instead, LLO may allow Listeria to survive within macrophages so that other bacterial products cause sustained TNF-alpha gene transcription. Both Ly+ and Ly- produced molecules, isolated by 50% ammonium sulfate, that induced cytokine production. In conclusion, we now report that Ly+ causes sustained transcription of the TNF-alpha gene and production of TNF-alpha by macrophages in vitro. We speculate that the TNF-alpha may activate endothelium and thus allow the recruitment of T cells to sites of infection. This may contribute to the ability of only LLO-producing Listeria to induce protective immunity.
authors.affiliation: Department of Internal Medicine, University of Texas, Southwestern Medical School, Dallas 75235-8856, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Vazquez
authors.forename: S C
authors.initials: SC
authors.lastname: Sicher
authors.forename: W J
authors.initials: WJ
authors.lastname: Wright
authors.forename: M L
authors.initials: ML
authors.lastname: Proctor
authors.forename: S R
authors.initials: SR
authors.lastname: Schmalzried
authors.forename: K R
authors.initials: KR
authors.lastname: Stallworth
authors.forename: J C
authors.initials: JC
authors.lastname: Crowley
authors.forename: C Y
authors.initials: CY
authors.lastname: Lu
mesh_terms: D000818:Animals; D001427:Bacterial Toxins; D005260:Female; D015870:Gene Expression; D006360:Heat-Shock Proteins / Q000276:immunology*; D006460:Hemolysin Proteins / Q000276:immunology*; D008089:Listeria monocytogenes / Q000472:pathogenicity*; D008088:Listeriosis / Q000276:immunology*; D017737:Macrophages, Peritoneal / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D010587:Phagocytosis; D012333:RNA, Messenger / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
chemical_list: D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C038705:hlyA protein, Listeria monocytogenes