Induction of trefoil factor (TFF)1, TFF2 and TFF3 by hypoxia is mediated by hypoxia inducible factor-1: implications for gastric mucosal healing.
OBJECTIVE
Mucosal microcirculation is compromised during gastric damage induced by non-steroidal anti-inflammatory drugs, such as aspirin. Consequently, oxygen supply to epithelial cells is decreased. The trefoil factor (TFF) peptides are involved in mechanisms of defence and repair in the gastrointestinal tract but their regulation at sites of gastric injury is unknown.


METHODS
Hypoxia and expression of TFF genes and peptides were measured in the damaged stomach of aspirin-treated rats. In a human gastric cell line (AGS cells), the effects of hypoxia and of hypoxia inducible factor (HIF)-1 (through transient transfection of HIF-1alpha siRNA or over-expression of HIF-1alpha) on TFF gene expression were evaluated.


RESULTS
Hypoxyprobe immunostaining, up-regulation of TFF2 (1.9-fold) and TFF3 (1.8-fold) and a non-significant increase of TFF1 (1.5-fold) mRNA were observed in the damaged stomach of aspirin-treated rats, compared with control animals. Hypoxia (3% O(2), 16 h) induced mRNA for TFF1 (5.8-fold), TTF2 (9.1-fold) and TFF3 (9.3-fold) in AGS cells, an effect mediated by HIF-1, as transient transfection of HIF-1alpha siRNA reduced the effects of hypoxia. Over-expression of HIF-1alpha by transfection in non-hypoxic epithelial cells produced a similar pattern of TFF induction to that observed with hypoxia and transactivated a TFF1 reporter construct.


CONCLUSIONS
Hypoxia inducible factor-1 mediated the induction of TFF gene expression by hypoxia in gastric epithelial cells. Low oxygen levels and up-regulation of TFF gene expression in the damaged stomach of aspirin-treated rats suggest that hypoxia induced expression of TFF genes at sites of gastric injury.
Hernández
C
C
Departamento de Farmacología and CIBEREHD, Valencia, Spain.
Santamatilde
E
E
McCreath
K J
KJ
Cervera
A M
AM
Díez
I
I
Ortiz-Masiá
D
D
Martínez
N
N
Calatayud
S
S
Esplugues
J V
JV
Barrachina
M D
MD
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000633:toxicity; D001241:Aspirin / Q000633:toxicity; D015687:Cell Hypoxia; D002460:Cell Line; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D005753:Gastric Mucosa / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D051793:Hypoxia-Inducible Factor 1 / Q000235:genetics / Q000502:physiology*; D008297:Male; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D000071164:Trefoil Factor-2; D015854:Up-Regulation
D000894:Anti-Inflammatory Agents, Non-Steroidal; D051793:Hypoxia-Inducible Factor 1; D010455:Peptides; D012333:RNA, Messenger; C000604007:TFF2 protein, human; C000604008:Tff2 protein, rat; D000071164:Trefoil Factor-2; D001241:Aspirin