Heterogeneous accumulation of fluorescent bile acids in primary rat hepatocytes does not correlate with their homogenous expression of ntcp.

Sodium taurocholate-cotransporting polypeptide (ntcp) is considered to be a major determinant of bile acid uptake into hepatocytes. However, the regulation of ntcp and the degree that it participates in the accumulation of specific substrates are not well understood. We utilized fluorescent bile acid derivatives and direct quantitation of fluorescent microscopy images to examine the regulation of ntcp and its role in the cell-to-cell variability of fluorescent bile acid accumulation. Primary-cultured rat hepatocytes rapidly accumulated the fluorescent bile acids, chenodeoxycholylglycylamidofluorescein (CDCGamF), 7-ß- nitrobenzoxadiazole 3-α hydroxy 5-ß cholan-24-oic acid (NBD-CA), and cholyl-glycylamido-fluorescein (CGamF). However, in stably transfected HeLa cells, ntcp preferred CDCGamF, whereas the organic anion transporter, organic anion transporting polypeptide 1 (oatp1a1), preferred NBD-CA, and neither ntcp nor oatp1a1 showed strong accumulation of CGamF by these methods. Ntcp-mediated transport of CDCGamF was inhibited by taurocholate, cyclosporin, actin depolymerization, and an inhibitor of atypical PKC-ζ. The latter two agents altered the cellular distribution of ntcp as visualized in ntcp-green fluorescent protein-transfected cells. Although fluorescent bile acid accumulation was reproducible by the imaging assays, individual cells showed variable accumulation that was not attributable to changes in membrane permeability or cell viability. In HeLa cells, this was accounted for by variable levels of ntcp, whereas, in hepatocytes, ntcp expression was uniform, and low accumulation was seen in a large portion of cells despite the presence of ntcp. These studies indicate that single-cell imaging can provide insight into previously unrecognized details of anion transport in the complex environment of polarized hepatocytes.

Effectiveness of hepatitis C treatment with pegylated interferon and ribavirin in urban minority patients.

Randomized controlled trials of hepatitis C virus (HCV) therapy with pegylated interferon and ribavirin have demonstrated sustained viral response rates (SVRs) of 54%-63% (efficacy). Treatment results in clinical practice (effectiveness) may not be equivalent. The goal of this study was to assess the effectiveness of HCV treatment with pegylated interferon and ribavirin in a treatment-naïve, human immunodeficiency virus (HIV)-negative, United States urban population with many ethnic minority patients. We evaluated 2,370 outpatients for HCV therapy from 2001 to 2006 in the Faculty Practice of the Albert Einstein College of Medicine or the attending-supervised Montefiore Medical Center Liver Clinic. Care was supervised by one experienced physician under conditions of everyday clinical practice, and appropriate ancillary resources were made available to all patients. Two hundred fifty-five patients were treated with a mean age of 50 years (60% male, 40% female; 58% Hispanic, 20% African American, 9% Caucasian, 13% other; 68% genotype 1, the remainder genotypes 2 or 3). Patients had at least one liver biopsy. Intention-to-treat analysis (ITT) showed SVR in 14% of genotype 1 patients and 37% in genotype 2/3 patients (P < 0.001). SVR was significantly higher in faculty practice (27%) than in clinic patients (15%) by intention-to-treat (P = 0.01) but not per-protocol analysis (46% faculty practice, 34% clinic). 3.3% of 1,656 treatment-naïve, HIV antibody-negative individuals ultimately achieved SVR. Current hepatitis C therapies may sometimes be unavailable to, inappropriate for, and ineffective in United States urban patients. Treatment with pegylated interferon and ribavirin was less effective in this population than is implied by multinational phase III controlled trials. New strategies are needed to care for such patients.