Pouchitis after ileal pouch-anal anastomosis for ulcerative colitis occurs with increased frequency in patients with associated primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC), present in 5% of patients with ulcerative colitis, may be associated with pouchitis after ileal pouch-anal anastomosis. The cumulative frequency of pouchitis in patients with and without PSC who underwent ileal pouch-anal anastomosis for ulcerative colitis was determined. A total of 1097 patients who had an ileal pouch-anal anastomosis for ulcerative colitis, 54 with associated PSC, were studied. Pouchitis was defined by clinical criteria in all patients and by clinical, endoscopic, and histological criteria in 83% of PSC patients and 85% of their matched controls. PSC was defined by clinical, radiological, and pathological findings. One or more episodes of pouchitis occurred in 32% of patients without PSC and 63% of patients with PSC. The cumulative risk of pouchitis at one, two, five, and 10 years after ileal pouch-anal anastomosis was 15.5%, 22.5%, 36%, and 45.5% for the patients without PSC and 22%, 43%, 61%, and 79% for the patients with PSC. In the PSC group, the risk of pouchitis was not related to the severity of liver disease. In conclusion, the strong correlation between PSC and pouchitis suggest a common link in their pathogenesis.

Regulation of biliary secretion through apical purinergic receptors in cultured rat cholangiocytes

To evaluate whether ATP in bile serves as a signaling factor regulating ductular secretion, voltage-clamp studies were performed using a novel normal rat cholangiocyte (NRC) model. In the presence of amiloride (100 microM) to block Na+ channels, exposure of the apical membrane to ATP significantly increased the short-circuit current (Isc) from 18.2 +/- 5.9 to 52.8 +/- 12.7 microA (n = 18). The response to ATP is mediated by basolateral-to-apical Cl- transport because it is inhibited by 1) the Cl- channel blockers 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (1 mM), diphenylanthranilic acid (1.5 mM), or 5-nitro-2-(3-phenylpropylamino)benzoic acid (50 or 100 microM) in the apical chamber, 2) the K+ channel blocker Ba2+ (5 mM), or 3) the Na(+)-K(+)-2Cl- cotransport inhibitor bumetanide (200 microM) in the basolateral chamber. Other nucleotides stimulated an increase in Isc with a rank order potency of UTP = ATP = adenosine 5'-O-(3)-thiotriphosphate, consistent with P2u purinergic receptors. ADP, AMP, 2-methylthioadenosine 5'-triphosphate, and adenosine had no effect. A cDNA encoding a rat P2u receptor (rP2uR) was isolated from a liver cDNA library, and functional expression of the corresponding mRNA in Xenopus laevis oocytes resulted in the appearance of ATP-stimulated currents with a similar pharmacological profile. Northern analysis identified hybridizing mRNA transcripts in NRC as well as other cell types in rat liver. These findings indicate that exposure of polarized cholangiocytes to ATP results in luminal Cl- secretion through activation of P2u receptors in the apical membrane. Release of ATP into bile may serve as an autocrine or paracrine signal regulating cholangiocyte secretory function.