title: Probiotic sonicates selectively induce mucosal immune cells apoptosis through ceramide generation via neutral sphingomyelinase.
abstract: BACKGROUND
  Probiotics appear to be beneficial in inflammatory bowel disease, but their mechanism of action is incompletely understood. We investigated whether probiotic-derived sphingomyelinase mediates this beneficial effect.
  
  
  RESULTS
  Neutral sphingomyelinase (NSMase) activity was measured in sonicates of the probiotic L. brevis (LB) and S. thermophilus (ST) and the non-probiotic E. coli (EC) and E. faecalis (EF). Lamina propria mononuclear cells (LPMC) were obtained from patients with Crohn's disease (CD) and Ulcerative Colitis (UC), and peripheral blood mononuclear cells (PBMC) from healthy volunteers, analysing LPMC and PBMC apoptosis susceptibility, reactive oxygen species (ROS) generation and JNK activation. In some experiments, sonicates were preincubated with GSH or GW4869, a specific NSMase inhibitor. NSMase activity of LB and ST was 10-fold that of EC and EF sonicates. LB and ST sonicates induced significantly more apoptosis of CD and UC than control LPMC, whereas EC and EF sonicates failed to induce apoptosis. Pre-stimulation with anti-CD3/CD28 induced a significant and time-dependent increase in LB-induced apoptosis of LPMC and PBMC. Exposure to LB sonicates resulted in JNK activation and ROS production by LPMC. NSMase activity of LB sonicates was completely abrogated by GW4869, causing a dose-dependent reduction of LB-induced apoptosis. LB and ST selectively induced immune cell apoptosis, an effect dependent on the degree of cell activation and mediated by bacterial NSMase.
  
  
  CONCLUSIONS
  These results suggest that induction of immune cell apoptosis is a mechanism of action of some probiotics, and that NSMase-mediated ceramide generation contributes to the therapeutic effects of probiotics.
authors.affiliation: Department of Gastroenterology, Hospital Clinic, IDIBAPS, CIBER Enfermedades Hepáticas y Digestivas (CIBERehd), Barcelona, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Angulo
authors.forename: Albert
authors.initials: A
authors.lastname: Morales
authors.forename: Silvio
authors.initials: S
authors.lastname: Danese
authors.forename: Laura
authors.initials: L
authors.lastname: Llacuna
authors.forename: Maria Carme
authors.initials: MC
authors.lastname: Masamunt
authors.forename: Nicole
authors.initials: N
authors.lastname: Pultz
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Cifone
authors.forename: Claudio
authors.initials: C
authors.lastname: De Simone
authors.forename: Salvadora
authors.initials: S
authors.lastname: Delgado
authors.forename: Jordi
authors.initials: J
authors.lastname: Vila
authors.forename: Julián
authors.initials: J
authors.lastname: Panés
authors.forename: Curtis
authors.initials: C
authors.lastname: Donskey
authors.forename: Jose C
authors.initials: JC
authors.lastname: Fernández-Checa
authors.forename: Claudio
authors.initials: C
authors.lastname: Fiocchi
authors.forename: Miquel
authors.initials: M
authors.lastname: Sans
mesh_terms: D000814:Aniline Compounds / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D001597:Benzylidene Compounds / Q000494:pharmacology; D002518:Ceramides / Q000096:biosynthesis* / Q000494:pharmacology; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000494:pharmacology; D006801:Humans; D018928:Immunity, Mucosal / Q000187:drug effects*; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D009092:Mucous Membrane / Q000166:cytology* / Q000201:enzymology; D010766:Phosphorylation / Q000187:drug effects; D019936:Probiotics / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013010:Sonication; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000814:Aniline Compounds; D001597:Benzylidene Compounds; D002518:Ceramides; D004791:Enzyme Inhibitors; C468773:GW 4869; D017382:Reactive Oxygen Species; D048031:JNK Mitogen-Activated Protein Kinases; D013108:Sphingomyelin Phosphodiesterase; D005978:Glutathione