FGF9-induced proliferative response to eosinophilic inflammation in oesophagitis.
BACKGROUND
Oesophagitis is characterised by basal cell hyperplasia and activated eosinophils, which release mediators including major basic protein (MBP). MBP and its mimetic polyarginine activate the calcium sensing receptor (CaSR) on oesophageal epithelium. Fibroblast growth factor 9 (FGF9) is implicated in epithelial homeostasis and proliferative response to injury, but has not been characterised in the oesophagus.


OBJECTIVE
To characterise FGF9 in oesophageal epithelium and oesophagitis, as the result of MBP activation of the CaSR.


METHODS
Human oesophageal epithelial cells (HET-1A) were used to compare affects of calcium, polyarginine and MBP-peptide on FGF9. HET-1A were transfected with interfering RNA (siRNA(CaSR)). FGF9, FGF receptors 2 and 3, bone morphogenetic protein (BMP)-2, BMP-4 and noggin mRNA expression were detected by reverse transcriptase polymerase chain reaction. FGF9 was measured from HET-1A and from normal, gastro-oesophageal reflux and eosinophilic oesophagitis (EoE) patient biopsies using ELISA and immunohistochemistry. HET-1A proliferation was studied using bromodeoxyuridine and MTT.


RESULTS
FGF9 was secreted by HET-1A cells treated with polyarginine and MBP-peptide, but not calcium. This effect was abrogated by siRNA(CaSR). FGF9 receptor mRNA was present. HET-1A cells proliferated following rhFGF9, but not MBP-peptide treatment, and rhFGF9 altered transcription of downstream proliferation-related genes (noggin, BMP-2 and BMP-4). FGF9 was increased in biopsies from patients with eosinophilic oesophagitis, which correlated with basal hyperplasia.


CONCLUSIONS
Eosinophil-released MBP acts on the CaSR to increase FGF9 in oesophageal epithelial cells, leading to proliferation. Increased FGF9 is found in biopsies of EoE patients and may play a role in the pathogenesis of oesophagitis.
Mulder
D J
DJ
Department of Anatomy and Cell Biology, Queen's University, Kingston, ON, Canada.
Pacheco
I
I
Hurlbut
D J
DJ
Mak
N
N
Furuta
G T
GT
MacLeod
R J
RJ
Justinich
C J
CJ
D000293:Adolescent; D019485:Bone Morphogenetic Proteins / Q000235:genetics; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D047093:Eosinophil Major Basic Protein / Q000378:metabolism / Q000494:pharmacology; D004802:Eosinophilia / Q000378:metabolism* / Q000473:pathology; D004847:Epithelial Cells / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D004941:Esophagitis / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D004947:Esophagus / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D005260:Female; D051525:Fibroblast Growth Factor 9 / Q000032:analysis / Q000235:genetics / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D034741:RNA, Small Interfering / Q000494:pharmacology; D051497:Receptor, Fibroblast Growth Factor, Type 2 / Q000235:genetics; D051498:Receptor, Fibroblast Growth Factor, Type 3 / Q000235:genetics; D044169:Receptors, Calcium-Sensing / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014158:Transcription, Genetic / Q000187:drug effects
D019485:Bone Morphogenetic Proteins; D051525:Fibroblast Growth Factor 9; D010455:Peptides; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D044169:Receptors, Calcium-Sensing; D011994:Recombinant Proteins; C015462:polyarginine; C496353:FGFR2 protein, human; C496365:FGFR3 protein, human; D051497:Receptor, Fibroblast Growth Factor, Type 2; D051498:Receptor, Fibroblast Growth Factor, Type 3; D047093:Eosinophil Major Basic Protein; D002118:Calcium