Gliadin activates HLA class I-restricted CD8+ T cells in celiac disease intestinal mucosa and induces the enterocyte apoptosis.
OBJECTIVE
The extensive infiltration of CD8(+) T cells in the intestinal mucosa of celiac disease (CD) patients is a hallmark of the disease. We identified a gliadin peptide (pA2) that is selectively recognized by CD8(+) T cells infiltrating intestinal mucosa of HLA-A2(+) CD patients. Herein, we investigated the phenotype, the tissue localization, and the effector mechanism of cells responsive to pA2 by using the organ culture of CD intestinal mucosa. The target of pA2-mediated cytotoxicity was also investigated by using the intestinal epithelial cell lines Caco2 and HT29, A2(+) and A2(-), respectively, as target cells.


METHODS
Jejunal biopsy specimens from CD patients were cultured in vitro with pA2, and cellular activation was evaluated by immunohistochemistry and cytofluorimetric analysis. Cytotoxicity of pA2-specific, intestinal CD8(+) T cells was assayed by granzyme-B and interferon-gamma release and by apoptosis of target cells.


RESULTS
pA2 challenge of A2(+) CD mucosa increased the percentage of CD8(+)CD25(+) and of CD80(+) cells in the lamina propria, the former mainly localized beneath the epithelium, as well as the number of terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling-positive cells (TUNEL(+)) in the epithelium. Intraepithelial CD3(+) cells and enterocyte expression of Fas were also increased. CD8(+)CD25(+) and CD8(+)FASL(+) T cells were significantly increased in cell preparations from biopsy specimens cultured with pA2. CD8(+) T-cell lines released both granzyme-B and interferon-gamma following recognition of pA2 when presented by Caco2 and not by HT29.


CONCLUSIONS
These data indicate that gliadins contain peptides able to activate, through a TCR/HLA class I interaction, CD8-mediated response in intestinal CD mucosa and to induce the enterocyte apoptosis.
Mazzarella
Giuseppe
G
Institute of Food Sciences, CNR, Avellino, Italy.
Stefanile
Rosita
R
Camarca
Alessandra
A
Giliberti
Paolo
P
Cosentini
Elena
E
Marano
Caterina
C
Iaquinto
Gaetano
G
Giardullo
Nicola
N
Auricchio
Salvatore
S
Sette
Alessandro
A
Troncone
Riccardo
R
Gianfrani
Carmen
C
D000328:Adult; D018122:B7-1 Antigen / Q000276:immunology; D001706:Biopsy; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002446:Celiac Disease / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D002478:Cells, Cultured; D020895:Enterocytes / Q000473:pathology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D005903:Gliadin / Q000009:adverse effects / Q000378:metabolism*; D015789:HLA-A2 Antigen / Q000276:immunology*; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000276:immunology; D007583:Jejunum / Q000473:pathology*; D008213:Lymphocyte Activation / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009924:Organ Culture Techniques; D019014:fas Receptor / Q000276:immunology
D018122:B7-1 Antigen; D015789:HLA-A2 Antigen; D053645:Interleukin-2 Receptor alpha Subunit; D019014:fas Receptor; D005903:Gliadin