Different cytokine response of primary colonic epithelial cells to commensal bacteria.
OBJECTIVE
To determine if primary murine colonic epithelial cells (CEC) respond to commensal bacteria and discriminate between different types of bacteria.


METHODS
A novel CEC: bacteria co-culture system was used to compare the ability of the colonic commensal bacteria, Bacteroides ovatus, E. coli (SLF) and Lactobacillus rhamnosus (LGG) to modulate production of different cytokines (n = 15) by primary CEC. Antibody staining and flow cytometry were used to investigate Toll-like receptor (TLR) expression by CEC directly ex vivo and TLR responsiveness was determined by examining the ability of TLR ligands to influence CEC cytokine production.


RESULTS
Primary CEC constitutively expressed functional TLR2 and TLR4. Cultured in complete medium alone, CEC secreted IL-6, MCP-1 and IP-10 the levels of which were significantly increased upon addition of the TLR ligands peptidoglycan (PGN) and lipopolysaccharide (LPS). Exposure to the commensal bacteria induced or up-regulated different patterns of cytokine production and secretion. E. coli induced production of MIP-1alpha/beta and betadefensin3 whereas B. ovatus and L. rhamnosus exclusively induced MCP-1 and MIP-2alpha expression, respectively. TNFalpha, RANTES and MEC were induced or up-regulated in response to some but not all of the bacteria whereas ENA78 and IP-10 were up-regulated in response to all bacteria. Evidence of bacterial interference and suppression of cytokine production was obtained from mixed bacterial: CEC co-cultures. Probiotic LGG suppressed E. coli- and B. ovatus-induced cytokine mRNA accumulation and protein secretion.


CONCLUSIONS
These observations demonstrate the ability of primary CEC to respond to and discriminate between different strains of commensal bacteria and identify a mechanism by which probiotic bacteria (LGG) may exert anti-inflammatory effects in vivo.
Lan
Jing-Gang
JG
School of Biochemistry and Microbiology, The University of Leeds, Leeds LS2 9JT, United Kingdom.
Cruickshank
Sheena-Margaret
SM
Singh
Joy-Carmelina-Indira
JC
Farrar
Mark
M
Lodge
James-Peter-Alan
JP
Felsburg
Peter-John
PJ
Carding
Simon-Richard
SR
D000818:Animals; D001419:Bacteria / Q000254:growth & development / Q000276:immunology*; D002478:Cells, Cultured; D003106:Colon / Q000166:cytology / Q000276:immunology* / Q000382:microbiology*; D016207:Cytokines / Q000276:immunology*; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology* / Q000382:microbiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D019936:Probiotics; D013047:Specific Pathogen-Free Organisms
D016207:Cytokines