Aim: 

We earlier demonstrated that a cocktail of four different lactobacillus reuteri strains protected rats against DSS induced colitis. The aim of this study was to further investigate if two of these four strains (R2LC, rat-derived and ATCC PTA 4659, human-derived) could each separately protect mice against DSS induced colitis.

Methods: 

Colitis was induced by DSS, 3% in drinking water for 8 days, in C57 Bl/6 mice. Two groups were given L. reuteri R2LC or ATCC PTA 4659 by gavage once daily for 15 days with DSS the last 8 days. The severity of disease was assessed through clinical observations (disease activity index, DAI) and histological evaluation of hematoxylin and eosin stained sections of paraffin embedded colonic samples. ELISA measurements of myeloperoxidase (MPO) and MULTI-ARRAY (meso scale) measurements of the pro-inflammatory cytokines IL-1beta, IL-6, TNF-a, INF-g and mkc (mouse keratinocyte chemoattractant) were also performed in colonic samples.

Results: 

DSS induced colitis severity expressed as DAI is significantly reduced after both L. reuteri R2LC and ATCC PTA 4659 strains. The histology results showed that the colon tissues from mice treated with either of R2LC or ATCC PTA 4659 strain showed less signs of inflammation than those exposed to DSS alone. MPO was increased by DSS and significantly reduced by both strains of l.reuteri. All cytokines were also increased by DSS and significantly reduced by l. reuteri R2LC. Cytokine levels after l. reuteri ATCC PTA 4659 strain not yet analyzed.

Conclusion: 

These results demonstrate that each of the two different l. reuteri strains, one human-derived and one-ratderived, protects against IBD in mice.