Induction of cytokine formation by human intestinal bacteria in gut epithelial cell lines.
OBJECTIVE
To investigate the effects of human gut micro-organisms on cytokine production by human intestinal cell lines.


RESULTS
Quantitative real-time PCR assays were developed to measure the production of pro-inflammatory (IL-1α, IL-6, IL-18 and TNFα) and anti-inflammatory (TGF-β1, TGF-β2, TGF-β3, IL-4 and IL-10) cytokines in HT-29 and Caco-2 cell lines. They were co-cultured with a range of mucosal bacteria isolated from ulcerative colitis patients, together with lactobacilli and bifidobacteria obtained from healthy people. HT-29 cells were also co-cultured with Campylobacter jejuni, enterotoxigenic Escherichia coli (ETEC), enteropathogenic E. coli and Salmonella typhimurium. The majority of commensal bacteria tested suppressed the expression of anti-inflammatory cytokine mRNA, increased IL-18, reduced IL-1α, and with the exception of nonpathogenic E. coli, reduced TNF-α. All overtly pathogenic species increased both pro-inflammatory and anti-inflammatory cytokine mRNA.


CONCLUSIONS
Commensal and pathogenic species induced fundamentally different cytokine responses in human intestinal epithelial cell lines.


CONCLUSIONS
Interactions between commensal bacteria tested in this study and the innate immune system were shown to be anti-inflammatory in nature, in contrast to the pathogenic organisms investigated. These data contribute towards our understanding of how potential probiotic species can be used to suppress the pro-inflammatory response in inflammatory bowel disease.
Microbiology and Gut Biology Group, University of Dundee, Dundee, UK.
B
B
Bahrami
S
S
Macfarlane
G T
GT
Macfarlane
D018407:Bacterial Physiological Phenomena; D001644:Bifidobacterium / Q000502:physiology; D018938:Caco-2 Cells; D016123:Campylobacter jejuni / Q000502:physiology; D018920:Coculture Techniques; D003093:Colitis, Ulcerative / Q000382:microbiology; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D004847:Epithelial Cells / Q000276:immunology / Q000382:microbiology; D004926:Escherichia coli / Q000502:physiology; D019073:HT29 Cells; D006801:Humans; D007378:Interleukins / Q000096:biosynthesis / Q000235:genetics; D007413:Intestinal Mucosa / Q000276:immunology* / Q000382:microbiology*; D007778:Lactobacillus / Q000502:physiology; D019936:Probiotics; D012486:Salmonella typhimurium / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis / Q000235:genetics
D016207:Cytokines; D007378:Interleukins; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha