Lactobacillus reuteri increases mucus thickness and ameliorates dextran sulphate sodium-induced colitis in mice.
The aim of this study was to investigate whether two Lactobacillus reuteri strains (rat-derived R2LC and human-derived ATCC PTA 4659 (4659)) could protect mice against colitis, as well as delineate the mechanisms behind this protection.



Mice were given L. reuteri R2LC or 4659 by gavage once daily for 14 days, and colitis was induced by addition of 3% DSS (dextran sulphate sodium) to drinking water for the last 7 days of this period. The severity of disease was assessed through clinical observations, histological evaluation and ELISA measurements of myeloperoxidase (MPO) and pro-inflammatory cytokines from colonic samples. Mucus thickness was measured in vivo with micropipettes, and tight junction protein expression was assessed using immunohistochemistry.



Colitis severity was significantly reduced by L. reuteri R2LC or 4659 when evaluated both clinically and histologically. The inflammation markers MPO, IL-1β, IL-6 and mKC (mouse keratinocyte chemoattractant) were increased by DSS and significantly reduced by the L. reuteri strains. The firmly adherent mucus thickness was reduced by DSS, but significantly increased by L. reuteri in both control and DSS-treated mice. Expression of the tight junction proteins occludin and ZO-1 was significantly increased in the bottom of the colonic crypts by L. reuteri R2LC.



These results demonstrate that each of the two different L. reuteri strains, one human-derived and one-rat-derived, protects against colitis in mice. Mechanisms behind this protection could at least partly be explained by the increased mucus thickness as well as a tightened epithelium in the stem cell area of the crypts.
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
D
D
Ahl
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
H
H
Liu
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
O
O
Schreiber
Department of Microbiology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden.
S
S
Roos
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
M
M
Phillipson
Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.
L
L
Holm
D000818:Animals; D003092:Colitis / Q000139:chemically induced / Q000473:pathology / Q000517:prevention & control*; D003106:Colon / Q000378:metabolism / Q000382:microbiology; D016207:Cytokines / Q000378:metabolism; D016264:Dextran Sulfate; D052200:Limosilactobacillus reuteri; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009093:Mucus / Q000502:physiology*; D009195:Peroxidase / Q000378:metabolism; D019936:Probiotics / Q000627:therapeutic use*; D051381:Rats; D062725:Tight Junction Proteins / Q000096:biosynthesis; D014783:Viscosity
D016207:Cytokines; D062725:Tight Junction Proteins; D016264:Dextran Sulfate; D009195:Peroxidase
colon; dextran sulphate sodium; inflammatory bowel disease; mucus thickness; probiotics; tight junctions