Changes in the immunoregulatory gene profile in ibs subjects following probiotic treatment: investigating a mechanism of action

Aims: Previous studies have demonstrated the efficacy of Bifidobacterium infantis in providing relief in IBS. A randomised, double-blind, placebo controlled study was instigated to investigate possible immunological alterations following oral administration of Bifidobacterium infantis, to determine potential causes for this therapeutic response at the molecular level and establish a possible mechanism of action.

Methods: Bifidobacterium infantis or placebo were randomly administered to 51 female IBS patients for four weeks. Biopsies were taken at beginning and end of treatment. Following RNA extraction, expression of IL-1β, IL-8, IL-10, IL-12, CCL5, CCL20 and TGFβ were analysed using Real Time RT PCR.

Results: TGFβ was observed to have the greatest expression increase (p=0.0003) in the colonic tissue of IBS patients following probiotic treatment. Significant increases in the relative expression of IL1β (p=0.0022), and CCL5 (p=0.0010) were also observed. No alterations in the expression levels of IL-8, IL-10, IL-12, CCL5 and CCL20 were detected.

Conclusions: Increased TGFβ levels in IBS patients provides further evidence of the specific immunomodulatory potential of Bifidobacterium infantis. Modulation of the expression profile of inflammatory mediators towards a more normal range may provide valuable insights into the precise mechanism of action of Bifidobacterium infantis in IBS.