Intraepithelial gammadelta+ lymphocytes maintain the integrity of intestinal epithelial tight junctions in response to infection.
OBJECTIVE
Intestinal epithelial integrity and permeability is dependent on intercellular tight junction (TJ) complexes. How TJ integrity is regulated remains unclear, although phosphorylation and dephosphorylation of the integral membrane protein occludin is an important determinant of TJ formation and epithelial permeability. We have investigated the role intestinal intraepithelial lymphocytes (iIELs) play in regulating epithelial permeability in response to infection.


METHODS
Recombinant strains of Toxoplasma gondii were used to assess intestinal epithelial barrier function and TJ integrity in mice with intact or depleted populations of iIELs. Alterations in epithelial permeability were correlated with TJ structure and the state of phosphorylation of occludin. iIEL in vivo reconstitution experiments were used to identify the iIELs required to maintain epithelial permeability and TJ integrity.


RESULTS
In the absence of gammadelta+ iIELs, intestinal epithelial barrier function and the ability to restrict epithelial transmigration of Toxoplasma and the unrelated intracellular bacterial pathogen Salmonella typhimurium was severely compromised. Leaky epithelium in gammadelta+ iIEL-deficient mice was associated with the absence of phosphorylation of serine residues of occludin and lack of claudin 3 and zona occludens-1 proteins in TJ complexes. These deficiencies were attributable to the absence of a single subset of gammadelta T-cell receptor (TCR-Vgamma7+) iIELs that, after reconstituting gammadelta iIEL-deficient mice, restored epithelial barrier function and TJ complexes, resulting in increased resistance to infection.


CONCLUSIONS
These findings identify a novel role for gammadelta+ iIELs in maintaining TJ integrity and epithelial barrier function that have implications for understanding the pathogenesis of intestinal inflammatory diseases associated with disruption of TJ complexes.
Dalton
Jane E
JE
Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom.
Cruickshank
Sheena M
SM
Egan
Charlotte E
CE
Mears
Rainy
R
Newton
Darren J
DJ
Andrew
Elizabeth M
EM
Lawrence
Beth
B
Howell
Gareth
G
Else
Kathryn J
KJ
Gubbels
Marc-Jan
MJ
Striepen
Boris
B
Smith
Judith E
JE
White
Stanley J
SJ
Carding
Simon R
SR
D000818:Animals; D015153:Blotting, Western; D002463:Cell Membrane Permeability / Q000276:immunology*; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D007365:Intercellular Junctions / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000276:immunology / Q000378:metabolism* / Q000469:parasitology; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D062793:Occludin; D010766:Phosphorylation; D012313:RNA / Q000235:genetics; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014122:Toxoplasma / Q000302:isolation & purification / Q000472:pathogenicity; D014124:Toxoplasmosis, Animal / Q000276:immunology / Q000378:metabolism / Q000473:pathology
D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; D016692:Receptors, Antigen, T-Cell, gamma-delta; D012313:RNA