Soluble galectin-3 is a strong, colonic epithelial-cell-derived, lamina propria fibroblast-stimulating factor.
BACKGROUND
Colonic lamina propria fibroblasts (CLPFs) play an important role in the pathogenesis of fibrosis and strictures in Crohn's disease.


OBJECTIVE
To identify colonic epithelial cell (CEC)-derived factors that activate CLPFs.


METHODS
Primary human CECs and CLPFs were isolated from control mucosa and interleukin 8 (IL8) of CLPF cultures was quantified by ELISA. Activation of nuclear factor kappaB (NF-kappaB) was shown, and translocation of NF-kappaB was inhibited by a dominant-negative IkappaB-expressing adenovirus. The major CLPF-activating and IL8 inducing protein was purified using fast-performance liquid chromatography (HiPrep 16/60 Sephacryl S-200 High Resolution Column) and sodium dodecyl sulphate gel electrophoresis.


RESULTS
A considerable increase in IL8 secretion by CLPFs cultured in CEC-conditioned media compared with that in unconditioned media (155.00 (10.00) pg/microg v 1.434 (0.695) pg/microg) was found. The effect of CEC-conditioned media on CLPF IL8 secretion was NF-kappaB dependent. A protein or DNA array confirmed the involvement of NF-kappaB and activator protein-1. Purification of a candidate band isolated with the use of sodium dodecyl sulphate-polyacrylamide gel electrophoresis and subsequent sequencing showed soluble galectin-3 to be a strong CLPF-activating factor. Depletion of galectin-3 from conditioned media by immunoprecipitation abolished the CLPF stimulatory effect.


CONCLUSIONS
Using a classical biochemical approach, soluble galectin-3 was identified as a strong activator of CLPFs produced by CEC. Galectin-3 induced NF-kappaB activation and IL8 secretion in these cells and may be a target for future therapeutic approaches to reduce or avoid stricture formation.
Lippert
E
E
Department of Internal Medicine I, University of Regensburg, Regensburg 93042, Germany.
Falk
W
W
Bataille
F
F
Kaehne
T
T
Naumann
M
M
Goeke
M
M
Herfarth
H
H
Schoelmerich
J
J
Rogler
G
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018938:Caco-2 Cells; D002460:Cell Line; D002478:Cells, Cultured; D003106:Colon / Q000737:chemistry*; D015179:Colorectal Neoplasms / Q000473:pathology; D017077:Culture Media, Conditioned; D004238:Diverticulitis / Q000473:pathology; D004847:Epithelial Cells / Q000737:chemistry; D005260:Female; D005347:Fibroblasts / Q000187:drug effects*; D037502:Galectin 3 / Q000032:analysis*; D019073:HT29 Cells; D006801:Humans; D016209:Interleukin-8 / Q000032:analysis; D007410:Intestinal Diseases / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000737:chemistry*; D016328:NF-kappa B / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism
D017077:Culture Media, Conditioned; D037502:Galectin 3; D016209:Interleukin-8; D016328:NF-kappa B; D018808:Transcription Factor AP-1