Effectiveness of oral semaglutide on glucose control and body weight up to 18 months: a multicenter retrospective real-world study.

AIM: Oral semaglutide, an innovative orally administered GLP-1 receptor agonist for type 2 diabetes (T2D) management was herein evaluated for its effectiveness in a multi-center retrospective real-world study. METHODS: We included new-users of oral semaglutide from 18 specialist care centres and collected retrospective data on baseline clinical characteristics. Updated values of HbA1c and body weight were analyzed using the mixed model for repeated measures. RESULTS: The study included 166 individuals with T2D, predominantly men (64.5%), with a mean age of 64.4 years and a mean diabetes duration of 10.1 years. In the majority of patients (68.3%) oral semaglutide was used as a second-line drug, mostly with metformin. At baseline, mean BMI was 28.9 kg/m2 and HbA1c was 7.5%. During the 18-month observation period, oral semaglutide demonstrated significant reductions in HbA1c, with a maximum change of - 0.9%, and 42.1% of patients achieved HbA1c values below 7.0%. Additionally, there was a substantial reduction in body weight, with an estimated change of - 3.4 kg at 18 months, and 30.3% of patients experienced a 5% or greater reduction in baseline body weight. Only 24.2% of patients reached the 14 mg dose. Subgroup analysis revealed that baseline HbA1c > 7%, persistence on drug, not being on a prior therapy with DPP-4 inhibitors, and loosing 5% or more the initial body weight were associated with greater HbA1c reductions. CONCLUSION: This study supports oral semaglutide as an effective option for T2D treatment, offering improved glucose control and weight management in a real-world setting.

The optimal timing of hepatitis C therapy in liver transplant-eligible patients: Cost-effectiveness analysis of new opportunities.

Different strategies of DAAs treatment are currently possible both pre- and postliver transplantation (LT). Clinical and economic consequences of these strategies still need to be adequately investigated; this study aims at assessing their cost-effectiveness. A decision analytical model was created to simulate the progression of HCV-infected patients listed for decompensated cirrhosis (DCC) or for hepatocellular carcinoma (HCC). Three DAAs treatment strategies were compared: (i) a 12-week course of DAAs prior to transplantation (PRE-LT), (ii) a 4-week course of DAAs starting at the time of transplantation (PERI-LT) and (iii) a 12-week course of DAAs administered at disease recurrence (POST-LT). The population was substratified according to HCC presence and, in those without HCC, according to the MELD score at listing. Data on DAAs effectiveness were estimated using a cohort of patients still followed by 11 transplant centres of the European Liver and Intestine Transplant Association and by data available in the literature. In this study, PRE-LT treatment strategy was dominant for DCC patients with MELD<16 and cost-effective for those with MELD16-20, while POST-LT strategy emerged as cost-effective for DCC patients with MELD>20 and for those with HCC. Sensitivity analyses confirmed PRE-LT as the cost-effective strategy for patients with MELD≤20. In conclusion, PRE-LT treatment is cost-effective for patients with MELD≤20 without HCC, while treatments after LT are cost-effective in cirrhotic patients with MELD>20 and in those with HCC. It is worth reminding, though, that the final choice of a specific regimen at the patient level will have to be personalized based on clinical, social and transplant-related factors.

Cost-Effectiveness of New Direct-Acting Antivirals to Prevent Post-Liver Transplant Recurrent Hepatitis.

Preliminary studies on HCV-cirrhotics listed for transplant suggest that sofosbuvir in combination with ribavirin is very effective in promoting viral clearance and preventing disease recurrence. Unfortunately, the high cost of such treatment (€46 500 per 12 weeks of treatment) makes its cost-effectiveness questionable. A semi-Markov model was developed to assess the cost-effectiveness of sofosbuvir/ribavirin treatment in cirrhotic patients without HCC (HCV-CIRRH) and with HCC (HCV-HCC) listed for transplant. In the base-case analysis, the incremental cost-effectiveness ratio for 24 weeks of sofosbuvir/ribavirin was €44 875 per quality-adjusted life-year gained in HCV-CIRRH and €60 380 in HCV-HCC patients. Both results were above the willingness to pay threshold of €37 000 per quality-adjusted life-year. Our data also show that in order to remain cost-effective (with a 24-week treatment), any novel interferon-free treatment endowed with ideal efficacy should cost less than €67 224 or €95 712 in HCV-cirrhotics with and without HCC, respectively. The results shows that sofosbuvir/ribavirin therapy, given to patients listed for transplant, is not cost-effective at current prices despite being very effective, and new, more effective treatments will have little economic margins to remain cost-effective. New interferon-free combinations have the potential to revolutionize the treatment and prognosis of HCV-positive patients listed for transplant; however, without sustainable prices, this revolution is unlikely to happen.

Management of treatment-naïve chronic hepatitis C genotype 1 patients: a cost-effectiveness analysis of treatment options.

New and more promising therapies for chronic hepatitis C (CHC) genotype 1 (G1) naive patients have recently been approved in the United States and Europe, and several more regimens are expected to become available within the next several years. While this scenario unfolds, it is necessary to develop a rational method to allocate current treatment in CHC G1 patients. We performed a cost-effectiveness analysis of boceprevir (BOC)- and telaprevir (TVR)-based triple therapy according to different patients' selection strategies. A semi-Markov model of CHC natural history and progression towards end-stage liver disease was built. We considered 3 selection strategies based on METAVIR fibrosis stage: (i) treat all patients with F1-F4 fibrosis, (ii) only F2-F4 and (iii) only F3-F4. For each strategy, TVR interleukin-28B-guided (IL28B-guided) and BOC rapid virologic response-guided (RVR-guided) therapies were applied. The model assessed the costs and outcomes, using a lifetime and 5-year time horizon, and adopting the Italian National Health System perspective. The incremental cost-effectiveness ratio (ICER) for F1-F4 strategy relative to F3-F4 was €5132 per quality-adjusted life years gained, across TVR IL-28B-guided therapy, and €7042 in the BOC RVR-guided therapy. Conversely, in the 5-year scenario, the ICER for F1-F4 strategy relative to F3-F4 was €1 818 679 (TVR IL28B-guided) and €1 866 437 (BOC RVR-guided) per end-stage liver disease or death (ESLD-D) avoided. In view of anticipated improvement in the efficacy of future regimens, selective treatment of only patients with advanced fibrosis and cirrhosis with TVR or BOC could represent the most cost-effective strategy to optimize resource utilization.

Intracellular pH regulation in isolated rat bile duct epithelial cells.

To evaluate ion transport mechanisms in bile duct epithelium (BDE), BDE cells were isolated from bile duct-ligated rats. After short-term culture pHi was measured with a single cell microfluorimetric set-up using the fluorescent pHi indicator BCECF, and calibrated with nigericin in high K+ concentration buffer. Major contaminants were identified using vital markers. In HCO3(-)-free media, baseline pHi (7.03 +/- 0.12) decreased by 0.45 +/- 0.18 pH units after Na+ removal and by 0.12 +/- .04 after amiloride administration (1 mM). After acid loading (20 mM NH4Cl) pHi recovery was inhibited by both Na+ removal and amiloride (JH+ = 0.74 +/- 1.1, and JH+ = 2.28 +/- 0.8, respectively, vs. 5.47 +/- 1.97 and 5.97 +/- 1.76 mM/min, in controls, respectively). In HCO3- containing media baseline pHi was higher (7.16 +/- 0.1, n = 36, P less than 0.05) and was decreased by Na+ substitution but not by amiloride. Na+ removal inhibited pHi recovery after an intracellular acid load (0.27 +/- 0.26, vs. 7.7 +/- 4.1 mM/min, in controls), whereas amiloride reduced JH+ only by 27%. pH recovery was inhibited by DIDS (0.5-1 mM), but not by Cl- depletion. Finally, acute Cl- removal increased pHi by 0.18 pH units in the absence but not presence of DIDS. These data indicate that BDE cells possess mechanisms for Na+/H+ exchange, Na+:HCO3- symport and Cl-/HCO3 exchange. Therefore BDE may be capable of transepithelial H+/HCO3- transport.

Quantitative assessment of canalicular bile formation in isolated hepatocyte couplets using microscopic optical planimetry.

Isolated rat hepatocyte couplets (IRHC) are primary units of bile secretion that accumulate fluid in an enclosed canalicular space with time in culture. We have quantitated the rate of canalicular secretion in IRHC cultured for 4-8 h by measuring the change in canalicular space volume by video-microscopic optical planimetry using high resolution Nomarski optics. Electron microscopic morphometric studies revealed significant increases in canalicular membrane area after 4-6 h in culture. Canalicular secretion in basal L-15 medium (3.8 +/- 1.3 fl/min) increased significantly with the choleretic bile salts (10 microM), taurocholate, and ursodeoxycholate (14 +/- 7 fl/min each). Secretion rates after exposure to bile acids correlated directly with the canalicular surface area before stimulation. In contrast, expansion times after stimulation varied inversely with initial canalicular volumes. Ursodeoxycholic acid failed to produce a hypercholeresis at 10-, 100-, or 200-microM concentrations compared with taurocholate, either in normal or taurine-depleted IRHC. The present findings establish that rates of canalicular bile secretion can be quantitated in IRHC by serial optical planimetry, both in the basal state and after stimulation with bile acids. Furthermore, ursodeoxycholate does not acutely induce hypercholeresis at the canalicular level in this model. Rather, both taurocholic and ursodeoxycholic acids induced secretion in proportion to the surface area of the canalicular membrane. The IRHC are a useful model to identify canalicular choleretics and for studies of canalicular bile formation.

Inheritance of hyperbilirubinemia: evidence for a major autosomal recessive gene.

BACKGROUND AND AIM: To clarify the precise mode of inheritance of Gilbert syndrome, an unconjugated familial hyperbilirubinemia, where impaired bilirubin conjugation is caused by reduced UGT1A1 activity determined by a defective function of the A(TA)6TAA promoter region of the UGT1A1 gene. SUBJECTS AND METHODS: Serum bilirubin levels were measured in a large, homogeneous resident population from North-Eastern Italy, consisting of 1.639 males (age 44.5+/-13.9, range 18-89 years), and 1.420 females (age 45.1+/-15.0, range 18-85). In 112 nuclear families from hyperbilirubinemic probands living in the same area a complex segregation analysis was then performed. In both samples we carefully excluded potentially confounding factors of bilirubin levels (alcohol abuse, excessive cigarette smoking, drug consumption, overt haemolysis and liver disease). RESULTS: Mean serum bilirubin concentrations are higher in males than in females, showing fluctuations through the different age periods in males. Complex segregation results demonstrate that unconjugated hyperbilirubinemia exhibits a precise mode of inheritance in which a major recessive gene with a frequency of 0.45 is responsible for higher serum bilirubin values. CONCLUSIONS: This major recessive gene accounts only for a part of the serum bilirubin concentration, thus implying additional, environmental factors for the clinical appearance of GS.

Integration of blood volume, blood pressure, heart rate and bioimpedance monitoring for the achievement of optimal dry body weight during chronic hemodialysis.

BACKGROUND: Achieving optimal dry body weight in hemodialysis is challenging. Clinical assessment alone is inadequate, and methods such as bioimpedance monitoring may be impractical for every patient treatment. Continuous blood volume monitoring, blood pressure and heart rate variability inform clinical decision-making, but integrated use of multiple methodologies to achieve dry weight and understand patient factors has not yet been described. METHODS: Nineteen chronic hemodialysis patients underwent thrice-weekly treatments for two weeks. Baseline hydration status and target weight were determined by bioimpedance. During subsequent treatments, ultrafiltration was adjusted and relative blood volume, blood pressure and pulse were recorded non-invasively. Bioimpedance was repeated to assess hydration. Response of variables to progressive change in weight was assessed and selected patients underwent additional autonomic function testing. RESULTS: Four distinct hemodynamic patterns emerged. Profile A: 4 patients demonstrated overhydration at baseline. With decreasing target, pulse and blood pressure remained stable while blood volume and bioimpedance demonstrated achievement of dry weight. Profile B: 8 patients demonstrated overhydration at baseline. With decreasing target, blood pressure remained stable while pulse increased. Profile C: 5 patients were overhydrated, but as weight decreased, blood pressure became unstable and heart rate failed to compensate. Further testing confirmed autonomic dysfunction. Profile D: 2 patients were dehydrated, and with increasing target demonstrated stable pulse and pressure, while blood volume and bioimpedance revealed achievement of dry weight. CONCLUSIONS: Integrating existing non-invasive, continuous monitoring during hemodialysis enabled achievement of dry weight and identified distinct profiles of the patients, some with autonomic dysfunction. This strategy may contribute to achieving optimum dry weight while improving cardiovascular tolerability of hemodialysis.

Practice of adult liver transplantation in Italy. Recommendations of the Italian Association for the Study of the Liver (A.I.S.F.).

Liver transplantation is an efficient procedure as performed in Italy, yet major differences are present in terms of practice. In an effort to facilitate an homogeneous practice of liver transplantation in Italy, the Italian Association for the Study of Liver Disease has instituted a Commission aimed at providing recommendations on non-urgent liver transplantation in adults, based on current evidence. This nation-wide commission which included experienced hepatologists, surgeons and pathologists with major interest in liver transplantation has drafted a final document in October 2004, approved by the Italian Association for the Study of Liver Governing Board, whose key arguments and main conclusions are summarised in the present paper. The Commission has made specific recommendations on the following topics: the current needs of liver transplantation in Italy; the indications to liver transplantation and re-liver transplantation, with special reference to controversial issues and the minimal listing criteria; the use of marginal donors and the need to optimise donor/recipient matching; the use of living donor liver transplantation; the management of the waiting list and the introduction of Model for End-Stage Liver Disease to define priorities; the clinical management of liver transplantation recipients and disease recurrence; the implementation of audits and outcome monitoring; the training of transplant surgeons and hepatologists and the requirements for Centre accreditation; the pathology of liver transplantation.

Use of extended right grafts from in situ split livers in adult liver transplantation: a comparison with whole-liver transplants.

INTRODUCTION: We report our experience of in situ split-liver transplantation (SLT) for adult patients and compare the results with those achieved with whole-liver transplantation (WLT). METHOD: From November 1997 to December 2003, 109 liver transplantation were performed in 104 adult patients including 90 WLT (83%) and 19 SLT (17%) grafts. Fifteen extended right grafts (ERG, segments I + IV to VIII) were obtained with in situ split-liver procedures, generating also left lateral segment grafts, which were transplanted at our institution or elsewhere. Four left lobe (LL, segments I to IV) and right lobe (segments V to VIII) grafts were obtained by a modified in situ procedure for adult recipients. UNOS status, percentage of primary or secondary transplantation, and underlying liver disease were similar among patients receiving whole versus split grafts. Donors were older in whole than ERG cohorts (53 vs 26 years, P < .001). Procurement parameters and intraoperative profiles of transplant procedure were comparable among the groups. RESULTS: Median follow-up was 18 months (range: 1 to 73). Four patients with whole (4%) and no patient with ERG underwent retransplantation (P = NS). One- and 3-year patient survivals were 86% and 79% with WLT versus 93% and 93% with ERG (P = NS). One- and 3-year graft survivals were 84% and 75% with WLT versus 93%, and 93% with ERG (P = NS). Incidence of vascular complications was 8% with WLT, 13% with ERG (P = NS). The incidence of biliary complications was 13% in WLT, 27% in ERG (P = NS). CONCLUSIONS: The use of ERG from in situ split livers for adult transplantation allowed us to obtain results comparable or even better than those obtained with WLT. Split-liver transplantation is an effective, safe mechanism to expand the cadaveric donor pool.

The effect of drugs on bile flow and composition. An overview.

Many drugs are eliminated via the hepatobiliary route, after biotransformation in the liver. Some of them may affect bile flow and/or the hepatic secretion of biliary lipids such as bile acids, cholesterol and phospholipids. Bile acids are the most potent agents which increase bile flow, especially unconjugated bile acids. Other drugs which increase bile flow include phenobarbitone (phenobarbital), theophylline, glucagon and insulin. In contrast, ethacrynic acid, amiloride, ouabain, oestrogens and chlorpromazine are among those agents which decrease bile flow. Biliary bile acid secretion is altered by a variety of drugs, including cheno- and ursodeoxycholic acids (CDCA and UCDA), the bile acid sequestrants cholestyramine and colestipol, and ethinyloestradiol. The composition of bile can also be altered by drug therapy. Thus, clofibrate increases biliary cholesterol secretion, and reduces bile acid concentrations, without altering biliary phospholipid concentrations. However, other clofibrate derivatives may produce changes of a different pattern, suggesting that the risk of developing gallstones may differ for each derivative. Nicotinic acid and d-thyroxine also increase biliary cholesterol saturation, while CDCA and UDCA reduce biliary cholesterol concentration. The potential consequences of drug-induced changes in bile flow and composition extend to the liver, the gallbladder and the intestine. If adverse effects are to be avoided, further study in this often overlooked area is required.

The monoethylglycinexylidide test for grading of liver cirrhosis.

BACKGROUND: Monoethylglycinexylidide (MEGX) formation following lignocaine injection has recently been proposed as a simple dynamic liver function test based on a single measurement of its serum concentration. AIM: To determine the optimal sampling time for MEGX determination. METHODS: A modelling analysis of lignocaine and MEGX kinetics was performed in seven normals and in four patients with compensated liver cirrhosis; a similar study was performed in 74 cirrhotic patients, divided into two groups according to disease severity (Pugh score). RESULTS: Only the MEGX fractional formation rate (kf) and formation delay (tau) were significantly altered in cirrhotic patients compared to normals: kf = 0.15 +/- 0.03 vs. 0.32 +/- 0.10 min-1 (mean +/- s.d.); tau = 7.7 +/- 2.0 vs. 3.9 +/- 2.9 min-1. A good correlation was found between kf and late (r = 0.82) but not early (r = 0.63) serum MEGX formation, suggesting that late measurements for the clinical MEGX test are preferred. In the second part of our investigation, by discriminant analysis of MEGX test data for 74 cirrhotic patients, the late MEGX concentrations gave the best discrimination between the two classes. In particular, the 60 min MEGX concentration showed the best diagnostic accuracy (81%), sensitivity (75%) and specificity (84%). The association of this with other MEGX parameters, either singly or derived from the whole curve measurements, did not improve the performance of the method. CONCLUSION: The MEGX test, based on a single determination 60 min after lignocaine injection, may be regarded as a simple and sensitive quantitative liver function test.

Advances in familial and congenital cholestatic diseases. Clinical and diagnostic implications.

Recent progress in liver cell biology and molecular genetics revealed that a number of familial and congenital cholestatic disorders are caused by mutations in genes coding for hepatobiliary-transporter or for signalling proteins involved in morphogenesis. The status of the field is reviewed in the light of its impact on current diagnostic and clinical practice. The heterogeneous progressive familial intrahepatic cholestasis can now be separated into different genetic diseases. FIC1-defective progressive familial intrahepatic cholestasis (previously Byler disease) is determined by mutations in the FIC1 gene, coding for P-type ATPases of unknown physiological function, while a second form (bile salt export pump defective progressive familial intrahepatic cholestatis) is caused by a defective function of the canalicular bile salt export pump. Furthermore, a group of progressive familial intrahepatic cholestasis patients with high serum gamma glutamyltranspeptidase have mutations in the gene (PGY3) coding for the MDR3 protein, a canalicular ATP-dependent phopshatidylcholine translocator. Recurrent intrahepatic cholestasis (previously benign recurrent cholestasis), is also linked to specific mutations in the FIC1 gene. Finally, in Alagille syndrome, mutations in the JAG1 gene cause deficiency Jagged 1, a ligand for Notch 1, a receptor determining cell fate during early embryogenesis. Diagnosis of Alagille syndrome, a condition that should be suspected in all patients with unexplained cholestasis, will thus be confirmed by genetic analysis for mutations of JAG1. In children with cholestasis and low serum bile acid levels, an inborn error of bile acid synthesis should be excluded by urinary bile acid analysis by means of fast atom bombardment-ionization mass-spectrometry. In contrast, in children with cholestasis and high serum bile acid concentrations, a high serum gamma glutamyltranspeptidase value would indicate MDR3 deficiency, which should be excluded through biliary phospholipid determination and genetic analysis of PGY3 gene. Finally, in those children with cholestasis, high serum bile acids and low gamma glutamyltranspeptidase activity, analysis of mutation in FIC1 and bile salt export pump genes may lead to the diagnosis of progressive familial intrahepatic cholestasis either from bile salt export pump or FIC1 deficiency.

Novel association of HLA-haplotypes with primary sclerosing cholangitis (PSC) in a southern European population.

AIMS: In patients with with primary sclerosing cholangitis we investigated the major histocompatibility complex (MHC) genes and mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. METHODS: In 64 PSC patients and 183 normal controls of the same population (Northern Italy), allelic polymorphisms at the DNA level were investigated in MHC region genes: HLA-DRB1, HLA-DQB1 and HLA-B, tumour necrosis factor A (TNFA), and in CFTR gene, with polymerase chain reaction-based methodologies. RESULTS: Frequencies of DRB1*01, DQA1*0101, DQB1*0102 (14 vs. 8%, p<0.05), DRB1*16, DQA1*0102, DQB1*0502 (8 vs. 3%, p<0.025) and DRB1*04, DQA1*03, DQB1*0301 (10 vs. 4%, p<0.005) haplotypes were more elevated in PSC patients. The frequency of patients positive for HLA DRB1*01, *1601 or *04 related haplotypes was significantly increased (32 vs. 14%, p<0.00025). DRB1*07, DQA1*0201, DQB1*02 haplotype frequency was significantly decreased (4 vs. 15%, p<0.001). After removing HLA-DRB1*01, *1601, *04 related haplotype sharing patients, HLA-DRB1*03, DQA1*0501, DQB1*02 haplotype frequency was significantly increased (32 vs. 14%, p<0.01). TNFA2 allele frequency was significantly increased in PSC patients (23 vs. 14%, p<0.025), as well as the TNFA2 homozygous genotype (9 vs. 0.5%, p=0.0013). No mutations were found on the CFTR gene and the allelic frequency of the 5T polymorphism in intron 8 was not increased. CONCLUSION: These data suggest that the role of genes in the HLA region is relevant, but not necessarily disease-specific and it might be different in populations with divergent ancestries.

Combined double lung-liver transplantation for cystic fibrosis without cardio-pulmonary by-pass.

Sequential bilateral single lung-liver transplantation (SBSL-LTx) is a therapeutic option for patients with end stage lung and liver disease (ESLLD) due to cystic fibrosis (CF). A few cases have been reported, all of them were performed with the use of cardio-pulmonary by-pass (CPB). We performed SBSL-LTx in three young men affected by CF. All the recipients had respiratory failure and portal hypertension with hypersplenism. Along with lung transplants, two patients received a whole liver graft and one an extended right graft from an in situ split liver. During transplantation neither CPB nor veno-venous by-pass (VVB) were employed. Immunosuppression was based on basiliximab, tacrolimus, steroids and azathioprine. The three recipients are alive with a median follow-up of 670 days (range 244-1,533). Combined SBSL-LTx is a complex but effective procedure for the treatment of ESLLD due to CF, not necessarily requiring the use of CPB or VVB.

Transport systems in cholangiocytes: their role in bile formation and cholestasis.

Formation of bile requires the coordinated function of two epithelial cell types: hepatocytes, that are responsible for secretion of the major osmolytes and biliary constituents and cholangiocytes that regulate the fluidity and alkalinity of bile through secretion of osmolytes such as Cl- and HCO3- Studies in isolated cholangiocyte preparations have elucidated the basic transport mechanisms involved in constitutive and stimulated secretory activities in the biliary epithelium. Basolateral Na+/H+ exchanger and Na+:HCO3- symporter mediate HCO3- uptake, while an apical cAMP-activated Cl-/HCO3- exchanger secretes bicarbonate into the lumen. Cholangiocytes also possess a cAMP-stimulated Cl- conductance (CFTR) and a Ca-activated Cl- channel, both likely located at the apical membrane. Cholangiocyte secretory functions are regulated by a complex network of hormones mainly acting via the cAMP system. In addition, recent data indicate that part of the regulation of ductular secretion may take place at the apical membrane of the cholangiocyte through factors present into the bile, such as ATP, bile acids and glutathione. Primary damage to the biliary epithelium is the cause of several chronic cholestatic disorders (cholangiopathies). From a pathophysiological point of view, common to all cholangiopathies is the coexistance of cholangiocyte death and proliferation and various degrees of portal inflammation and fibrosis. Cholestasis dominates the clinical picture and, pathophysiologically, may initiate or worsen the process. Alterations in biliary electrolyte transport could contribute to the pathogenesis of cholestasis in primary bile duct diseases. Cystic Fibrosis-related liver disease represents an example of biliary cirrhosis secondary to a derangement of cholangiocyte ion transport. Most primary cholangiopaties recognize an immune-mediated pathogenesis. Cytokines, chemokines, and proinflammatory mediators released in the portal spaces or produced by the cholangiocyte itself, likely activate fibrogenesis, stimulate apoptotic and proliferative responses, and alter the transport functions of the epithelium.

Ca2+-activated Cl- channels can substitute for CFTR in stimulation of pancreatic duct bicarbonate secretion.

This study addresses the mechanisms by which a defect in CFTR impairs pancreatic duct bicarbonate secretion in cystic fibrosis. We used control (PANC-1) and CFTR-deficient (CFPAC-1; DeltaF508 mutation) cell lines and measured HCO3- extrusion by the rate of recovery of intracellular pH after an alkaline load and recorded whole cell membrane currents using patch clamp techniques. 1) In PANC-1 cells, cAMP causes parallel activation of Cl- channels and of HCO3- extrusion by DIDS-sensitive and Na+-independent Cl-/HCO3- exchange, both effects being inhibited by Cl- channel blockers NPPB and glibenclamide. 2) In CFPAC-1 cells, cAMP fails to stimulate Cl-/HCO3- exchange and Cl- channels, except after promoting surface expression of DeltaF508-CFTR by glycerol treatment. Instead, raising intracellular Ca2+ concentration to 1 micromol/l or stimulating purinergic receptors with ATP (10 and 100 micromol/l) leads to parallel activation of Cl- channels and HCO3- extrusion. 3) K+ channel function is required for coupling cAMP- and Ca2+-dependent Cl- channel activation to effective stimulation of Cl-/HCO3- exchange in control and CF cells, respectively. It is concluded that stimulation of pancreatic duct bicarbonate secretion via Cl-/HCO3- exchange is directly correlated to activation of apical membrane Cl- channels. Reduced bicarbonate secretion in cystic fibrosis results from defective cAMP-activated Cl- channels. This defect is partially compensated for by an increased sensitivity of CF cells to purinergic stimulation and by alternative activation of Ca2+-dependent Cl- channels, mechanisms of interest with respect to possible treatment of cystic fibrosis and of related chronic pancreatic diseases.