HCl-induced and ATP-dependent upregulation of TRPV1 receptor expression and cytokine production by human esophageal epithelial cells.
The pathogenesis of gastroesophageal reflux disease (GERD) remains elusive, but recent evidence suggests that early secretion of inflammatory cytokines and chemokines by the mucosa leads to influx of immune cells followed by tissue damage. We previously showed that exposure of esophageal mucosa to HCl causes ATP release, resulting in activation of acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase (lyso-PAF AT), the enzyme responsible for the production of platelet-activating factor (PAF). In addition, HCl causes release of IL-8 from the esophageal mucosa. We demonstrate that esophageal epithelial cells secrete proinflammatory mediators in response to HCl and that this response is mediated by ATP. Monolayers of the human esophageal epithelial cell line HET-1A were exposed to acidified cell culture medium (pH 5) for 12 min, a total of seven times over 48 h, to simulate the recurrent acid exposure clinically occurring in GERD. HCl upregulated mRNA and protein expression for the acid-sensing transient receptor potential cation channel, subfamily vanilloid member 1 (TRPV1), lyso-PAF AT, IL-8, eotaxin-1, -2, and -3, macrophage inflammatory protein-1α, and monocyte chemoattractant protein-1. The chemokine profile secreted by HET-1A cells in response to repeated HCl exposure parallels similar findings in erosive esophagitis patients. In HET-1A cells, the TRPV1 agonist capsaicin reproduced these findings for mRNA of the inflammatory mediators lyso-PAF AT, IL-8, and eotaxin-1. These effects were blocked by the TRPV1 antagonists iodoresiniferatoxin and JNJ-17203212. These effects were imitated by direct application of ATP and blocked by the nonselective ATP antagonist suramin. We conclude that HCl/TRPV-induced ATP release upregulated secretion of various chemoattractants by esophageal epithelial cells. These chemoattractants are selective for leukocyte subsets involved in acute inflammatory responses and allergic inflammation. The data support the validity of HET-1A cells as a model of the response of the human esophageal mucosa in GERD.
Department of Medicine, Rhode Island Hospital, Providence, Rhode Island, USA.
Jie
J
Ma
Annamaria
A
Altomare
Michele
M
Guarino
Michele
M
Cicala
Florian
F
Rieder
Claudio
C
Fiocchi
Dan
D
Li
Weibiao
W
Cao
Jose
J
Behar
Piero
P
Biancani
Karen M
KM
Harnett
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000368:Aged; D015153:Blotting, Western; D018929:Cell Culture Techniques; D016207:Cytokines / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D004947:Esophagus / Q000187:drug effects* / Q000378:metabolism; D005764:Gastroesophageal Reflux / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D006851:Hydrochloric Acid / Q000494:pharmacology*; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D016207:Cytokines; D012333:RNA, Messenger; D050916:TRPV Cation Channels; C494482:TRPV1 protein, human; D000255:Adenosine Triphosphate; D006851:Hydrochloric Acid