Basic Research
Copyright ©2005 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 14, 2005; 11(22): 3375-3384
Published online Jun 14, 2005. doi: 10.3748/wjg.v11.i22.3375
Different cytokine response of primary colonic epithelial cells to commensal bacteria
Jing-Gang Lan, Sheena Margaret Cruickshank, Joy Carmelina Indira Singh, Mark Farrar, James Peter Alan Lodge, Peter John Felsburg, Simon Richard Carding
Jing-Gang Lan, Sheena Margaret Cruickshank, Joy Carmelina Indira Singh, Mark Farrar, Simon Richard Carding, School of Biochemistry and Microbiology, The University of Leeds, Leeds LS2 9JT, United Kingdom
James Peter Alan Lodge, General Surgery, Medicine and Anaesthesia, School of Medicine, The University of Leeds, Leeds LS2 9JT, United Kingdom
Peter John Felsburg, Department of Clinical Studies, University of Pennsylvania, Philadelphia, PA 19104, United States
Author contributions: All authors contributed equally to the work.
Correspondence to: Professor Simon Richard Carding, School of Biochemistry and Microbiology, The University of Leeds, Leeds LS2 9JT, United Kingdom. s.r.carding@leeds.ac.uk
Telephone: +44-113-3431404 Fax: +44-113-3431421
Received: July 31, 2004
Revised: August 1, 2004
Accepted: December 1, 2004
Published online: June 14, 2005
Abstract

AIM: 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-1α/β and β defensin3 whereas B. ovatus and L. rhamnosus exclusively induced MCP-1 and MIP-2α expression, respectively. TNFα, 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.

CONCLUSION: 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.

Keywords: Epithelial cells; Colon; Commensal bacteria; Cytokines; Chemokines