Phenotypic changes in colonocytes following acute stress or activation of mast cells in mice: implications for delayed epithelial barrier dysfunction.
OBJECTIVE
Stressful life events are known to modulate the development or relapse of disease in both inflammatory bowel disease and irritable bowel disease patients but underlying mechanisms remain unclear. Stress is known to effect mast cells, interferon gamma (IFN-gamma), and myosin light chain phosphorylation to trigger colonic epithelial barrier dysfunction. The aim of this study was to investigate whether acute stress induced or chemical mast cell activation impaired expression and function of epithelial tight junctions, and altered colonocyte differentiation in mice.


METHODS
Colonic paracellular permeability was assessed as the in vivo lumen to blood ratio of 51Cr-EDTA in different groups of mice (controls, stressed, mast cell degranulator BrX-537A treated), pretreated or not with the mast cell stabiliser doxantrazole. Involvement of mast cells and IFN-gamma was evaluated in wild-type and IFN-gamma deficient mice. Tight junction alteration was assessed by histology, transmission electron microscopy, and real time reverse transcription-polymerase chain reaction. Colonocyte differentiation was determined by protein kinase C zeta (PKCzeta) immunofluorescence and western blotting, and alkaline phosphatase activity assay.


RESULTS
Acute stress induced a three day delayed increase in colonic paracellular permeability which involved mast cell degranulation and overproduction of IFN-gamma. The colonic epithelial barrier was morphologically altered and expression of mRNA encoding tight junction proteins ZO-2 and occludin was decreased. Moreover, three days after acute stress, colonocyte differentiation was reduced, as shown by decreased expression of both PKCzeta isotype and alkaline phosphatase.


CONCLUSIONS
These data highlight new mechanisms whereby an acute stress acts on the gastrointestinal tract by inducing alterations in colonocyte differentiation and decreased expression of mRNA encoding tight junction proteins. Thus phenotypic changes in colonocytes could pave the way for stress related intestinal disorders.
Demaude
J
J
Neuro-Gastroenterology and Nutrition Unit, Institut National de la Recherche Agronomique, Toulouse, France.
Salvador-Cartier
C
C
Fioramonti
J
J
Ferrier
L
L
Bueno
L
L
D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D015550:Cell Degranulation; D002454:Cell Differentiation; D002463:Cell Membrane Permeability; D003106:Colon / Q000473:pathology*; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D008407:Mast Cells / Q000276:immunology; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D018994:Myosin Light Chains / Q000378:metabolism; D062793:Occludin; D010766:Phosphorylation; D011493:Protein Kinase C / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013315:Stress, Psychological / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D019108:Tight Junctions / Q000502:physiology; D013997:Time Factors; D062827:Zonula Occludens-2 Protein
D008565:Membrane Proteins; D018994:Myosin Light Chains; D062793:Occludin; C568986:Ocln protein, mouse; C569047:Tjp2 protein, mouse; D062827:Zonula Occludens-2 Protein; D007371:Interferon-gamma; C087857:protein kinase C gamma; D011493:Protein Kinase C; D000469:Alkaline Phosphatase