title: Differential cytokine response from dendritic cells to commensal and pathogenic bacteria in different lymphoid compartments in humans.
abstract: Resident host microflora condition and prime the immune system. However, systemic and mucosal immune responses to bacteria may be divergent. Our aim was to compare, in vitro, cytokine production by human mononuclear and dendritic cells (DCs) from mesenteric lymph nodes (MLNs) and peripheral blood mononuclear cells (PBMCs) to defined microbial stimuli. Mononuclear cells and DCs isolated from the MLN (n = 10) and peripheral blood (n = 12) of patients with active colitis were incubated in vitro with the probiotic bacteria Lactobacillus salivarius UCC118 or Bifidobacterium infantis 35624 or the pathogenic organism Salmonella typhimurium UK1. Interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and IL-10 cytokine levels were quantified by ELISA. PBMCs and PBMC-derived DCs secreted TNF-alpha in response to the Lactobacillus, Bifidobacteria, and Salmonella strains, whereas MLN cells and MLN-derived DCs secreted TNF-alpha only in response to Salmonella challenge. Cells from the systemic compartment secreted IL-12 after coincubation with Salmonella or Lactobacilli, whereas MLN-derived cells produced IL-12 only in response to Salmonella. PBMCs secreted IL-10 in response to the Bifidobacterium strain but not in response to the Lactobacillus or Salmonella strain. However, MLN cells secreted IL-10 in response to Bifidobacteria and Lactobacilli but not in response to Salmonella. In conclusion, commensal bacteria induced regulatory cytokine production by MLN cells, whereas pathogenic bacteria induce T cell helper 1-polarizing cytokines. Commensal-pathogen divergence in cytokine responses is more marked in cells isolated from the mucosal immune system compared with PBMCs.
authors.affiliation: Alimentary Pharmabiotic Centre, University College Cork, National University of Ireland.
authors.forename: Liam
authors.initials: L
authors.lastname: O'Mahony
authors.forename: Louise
authors.initials: L
authors.lastname: O'Callaghan
authors.forename: Jane
authors.initials: J
authors.lastname: McCarthy
authors.forename: David
authors.initials: D
authors.lastname: Shilling
authors.forename: Paul
authors.initials: P
authors.lastname: Scully
authors.forename: Shomik
authors.initials: S
authors.lastname: Sibartie
authors.forename: Eamon
authors.initials: E
authors.lastname: Kavanagh
authors.forename: William O
authors.initials: WO
authors.lastname: Kirwan
authors.forename: Henry Paul
authors.initials: HP
authors.lastname: Redmond
authors.forename: John Kevin
authors.initials: JK
authors.lastname: Collins
authors.forename: Fergus
authors.initials: F
authors.lastname: Shanahan
mesh_terms: D000328:Adult; D001644:Bifidobacterium / Q000302:isolation & purification; D016207:Cytokines / Q000378:metabolism*; D003713:Dendritic Cells / Q000378:metabolism*; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000378:metabolism* / Q000382:microbiology*; D007778:Lactobacillus / Q000302:isolation & purification; D008198:Lymph Nodes / Q000378:metabolism* / Q000382:microbiology*; D008297:Male; D008643:Mesentery / Q000378:metabolism / Q000382:microbiology; D008875:Middle Aged; D012486:Salmonella typhimurium / Q000302:isolation & purification
chemical_list: D016207:Cytokines