Abstracts
1998 Digestive Disease Week
#1043
IL-1_ STIMULATES MUCUS SECRETION IN GALLBLADDER EPITHELIAL CELLS. C.H. Cheung, J.B. Prystowsky, E.W. Moore, R.V.Rege, Northwestern University Medical School. Chicago, IL and Medical College of Virginia, Richmond, VA.
We have previously shown that biliary crystals induce inflammation and increase IL-1 activity in the gallbladder (GB) wall and that increased IL-1 activity and mucus layer thickness (MLT) are prominent early during both cholesterol and pigment gallstone formation in mice and dogs. We hypothesized that inflammatory cytokines, & specifically IL-1, stimulate mucin secretion by the GB epithelial cell. Methods: Effects of IL-1_ were studied using human cultured GB epithelial (HCGE) cells derived from a well differentiated GB carcinoma. HCGE cells were grown to confluency on polycarbonate matrices and 10-15 cell monolayers/group were exposed to IL-1_ (1, 10, & 50 pg/ml), media alone (- Control), or 0.1 mM prostaglandinE2 PGE2 = + Control) for 12 hrs. IL-1_ (50 pg/ml) was also studied in the presence of its competitive receptor antagonist, IL-1_ ra (10ng/ml). Monolayers attached to matrices were cut into strips and mounted between 2 pieces of cork. MLT was measured by both darkfield microscopy and PAS staining. High molecular weight mucin glycoprotein in media was determined by a PAS method after ultracentrifugation on a CsCl2 gradient. Results: Values = Mean ± SEM
Group
|
MLT (µm)
|
Mucin (µg/ml)
|
Media alone (-) Control
|
49 ± 4
|
114 ± 6
|
PGE2 (+) Control
|
312 ± 8*
|
708 ± 11 *
|
IL-1_ 1 _g/ml
|
56 ± 5
|
161 ± 35
|
IL-1_ 10 _g/ml
|
251 ± 11*
|
400 ± 11*
|
IL-1_ 50 _g/ml
|
239 ± 8*
|
522 ± 10*
|
IL-1_ 50 _g/ml + IL-1_ ra 10 ng/ml
|
36 ± 5
|
52 ± 25
|
* statistically different from (-) Control by ANOVA at p < 0.001
MLT by darkfield and PAS did not differ significantly. All mucin layers stained with PAS indicating they were composed largely of mucin glycoprotein. As expected, PGE2 increased MLT and mucin secretion. IL-1_ (10 & 50 pg/ml) significantly increased MLT and mucin secretion. These effects were completely reversed IL-1_ ra. MLT and mucin secretion were directly correlated with the linear regression: MLT = 0.45 Glycoprotein + 14.86, r2 = 0.89. Conclusions: 1. HCGE cells secrete increased amounts of mucin and the mucus layer thickened in response to both PGE2 and IL-1_. 2. Effects of IL-1_ were receptor-mediated and specific since they were inhibitied by the receptor antagonist, IL-1_ ra. Significance: These studies indicate that mucin sercretion is, in part, mediated by the inflammatory cytokine, IL-1_.
Copyright 1996 - 1998, SSAT, Inc. Revised 29 June 1998.
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