Abstracts
1999 Digestive Disease Week

# 3477 INFLAMMATORY CYTOKINES ALTER HUMAN GALLBLADDER EPITHELIAL ABSORPTION
R V Rege, The Univ of Texas Southwestern Med Ctr, Dallas, TX

Inflammation, mucus hypersecretion, and alterations in gallbladder absorption/secretion occur early during gallstone formation. Mucus hypersecretion and alterations in gallbladder absorption are key factors that contribute to the pathogenesis of all types of gallstones. We have previously shown that the inflammatory cytokines, IL-1a and TNFa, directly induce mucin secretion from human cultured gallbladder epithelial (HCGE) cells. We now hypothesize that IL-1a and TNFa also directly alter HCGE cell absorption/secretion. Methods: HCGE cell monolayers grown to confluence on polycarbonate matrices were studied in Ussing chambers with and without mucosal 125 rg/ml IL-1a or TNFa. Negative controls were exposed to media alone. Positive controls for inflammation were exposed to 100 mg/ml lipopolysaccharide (LPS) and 0.1 mM prostaglandin E2 (PGE2). Unidirectional "mucosal-to-serosal" (Jms) and "serosal-to-mucosal" (Jsm) fluxes were measured using 22Na or 36C1 under short-circuit, steadystate conditions. At steadystate, Net fluxes (Net J) for Na and C1 were calculated as Net J= Jms-Jsm and Net J of unmeasured ions (JR) as Net JNa-Net JC1. Results: Reported as mean ±sem flux in meq/hr-cm2. Cytokines caused significant decreases in NaC1 transport, increases in Jsm for Na (data not shown), and a negative JR indicating net secretion of another ion, likely bicarbonate (HCO3). Effects of cytokines were similar to those caused by the pro-inflammatory agents LPS and PGE2. In addition, effects of IL-1a were completely reversed by its competitive inhibitor IL-1ra (500 rg/ml) indicating that IL-1a effects were specific and receptor mediated. Conclusions: 1. IL-1a and TNFa decreased net NaCl absorption and 2. caused net secretion of another ion, probably HCO3, by HCGE cells. 3. Effects of cytokines were similar to those of the pro-inflammatory agents LPS and PGE2. Significance: These data demonstrate that inflammatory cytokines directly after HCGE absorptive function. Therefore, inflammatory cytokines directly affect two important aspects of gallbladder function, mucus secretion and electrolyte absorption. These results suggest that inflammation, uniformly noted early during gallstone formation, plays an important role in gallstone pathogenesis.

Net Flux	No IL-1	IL-1	No TNF	TNF	LPS	PGE2
Net JNa	8.1±0.6	4.0±0.2*	10.2±0.7	4.7±0.3*	3.8±0.3*	4.1±0.7*
Net JC1	8.1±0.5	6.4±0.3*	9.7±0.8	6.3±0.1*	6.1±0.7*	7.3±0.4
Net JR	0±0.9	-2.4±0.5*	0.4±1.1	-1.6±0.4	-2.3±0.4*	-3.2±0.3*
*Statistically significant (p<0.01) vs. controls by unpaired T-test

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