Double blind, placebo controlled trial of two probiotic strains in interleukin 10 knockout mice and mechanistic link with cytokine balance
- J McCarthy1,
- L O’Mahony2,
- L O’Callaghan2,
- B Sheil2,
- E E Vaughan3,
- N Fitzsimons3,
- J Fitzgibbon4,
- G C O’Sullivan1,
- B Kiely2,
- J K Collins2,
- F Shanahan1
- 1Department of Medicine, University College Cork, National University of Ireland, Cork, Ireland
- 2Department of Microbiology, University College Cork, National University of Ireland, Cork, Ireland
- 3Laboratory of Microbiology, Wageningen University, the Netherlands
- 4Department of Pathology, University College Cork, National University of Ireland, Cork, Ireland
- Correspondence to:
Professor F Shanahan, Department of Medicine, Cork University Hospital, Cork, Ireland;
- Accepted 17 December 2002
Background: Prophylactic efficacy against colitis following lactobacillus consumption in interleukin 10 (IL-10) knockout (KO) mice has been reported. Whether this applies equally to other probiotic strains is unknown, and the mechanism is unclear.
Aims: (1) To compare the effect of feeding Lactobacillus salivarius subspecies salivarius 433118 and Bifidobacterium infantis 35624 against placebo on enterocolitis, the intestinal microflora, and (2) to compare the systemic immunological response to in vitro microbial challenge in probiotic fed and control IL-10 KO mice.
Methods: Three groups of 10 IL-10 KO mice were fed fermented milk products containing Lb salivarius 433118 at 109 CFU/ml, B infantis 35624 at 108 CFU/ml, and unmodified milk, respectively, for 19 weeks. Faecal samples were taken at regular intervals to confirm gut transit, recovery of fed probiotics, and to assess the impact on the microflora. At sacrifice, the bowels were histologically scored. Cytokine production from Peyers’ patches and splenocytes was measured in vitro by ELISA.
Results: Faecal recovery of probiotics was confirmed in all probiotic fed mice but not in controls. Colonic and caecal inflammatory scores were significantly decreased in both groups of probiotic fed mice (p<0.05). Proinflammatory cytokine production by Peyers’ patches and splenocytes was significantly reduced in probiotic fed animals whereas transforming growth factor β (TGF-β) levels were maintained.
Conclusion: Both Lactobacillus salivarius 433118 and Bifidobacterium infantis 35624 significantly attenuate colitis in this murine model. Attenuation of colitis is associated with a reduced ability to produce Th1-type cytokines systemically and mucosally, while levels of TGF-β are maintained.
- IL-10, interleukin 10
- KO, knockout
- Th1, T helper 1
- IFN-γ, interferon γ
- MRS broth, de Man, Rogosa, Sharpe broth
- VRBA, violet red bile agar
- DGGE, denaturing gradient gel electrophoresis
- PCR, polymerase chain reaction
- TNF-α, tumour necrosis factor α
- TGF-β, transforming growth factor β
- CFU, colony forming units