Effect of mTOR inhibitors on sodium taurocholate cotransporting polypeptide (NTCP) function in vitro

The sodium taurocholate cotransporting polypeptide (NTCP; gene name SLC10A1) is the primary hepatic basolateral uptake transporter for conjugated bile acids and the entry receptor for the hepatitis B and D virus (HBV/HDV). Regulation of human NTCP remains a knowledge gap due to significant species differences in substrate and inhibitor selectivity and plasma membrane expression. In the present study, various kinase inhibitors were screened for inhibition of NTCP function and taurocholate (TCA) uptake using NTCP-transfected HuH-7 cells. This study identified everolimus, an mTOR inhibitor and macrocyclic immunosuppressive drug, as an NTCP inhibitor with modest potency (IC50 = 6.7-8.0 µM). Further investigation in differentiated HuH-7 cells expressing NTCP and NTCP-overexpressing Flp-In T-REx 293 cells revealed that the mechanism of action of everolimus on NTCP is direct inhibition and mTOR-independent. Structural analogs of everolimus inhibited NTCP-mediated TCA uptake, however, functional analogs did not affect NTCP-mediated TCA transport, providing further evidence for direct inhibition. This work contributes to the growing body of literature suggesting that NTCP-mediated bile acid uptake may be inhibited by macrocyclic peptides, which may be further exploited to develop novel medications against HBV/HDV.

Evidence that decreased expression of sinusoidal bile acid transporters accounts for the inhibition by rapamycin of bile flow recovery following liver ischemia

Rapamycin is employed as an immunosuppressant following organ transplant and, in patients with hepatocellular carcinoma, to inhibit cancer cell regrowth following liver surgery. Preconditioning the liver with rapamycin to induce the expression of antioxidant enzymes is a potential strategy to reduce ischemia reperfusion (IR) injury. However, pre-treatment with rapamycin inhibits bile flow, especially following ischemia. The aim was to investigate the mechanisms involved in this inhibition. In a rat model of segmental hepatic ischemia and reperfusion, acute administration of rapamycin by intravenous injection did not inhibit the basal rate of bile flow. Pre-treatment of rats with rapamycin for 24 h by intraperitoneal injection inhibited the expression of mRNA encoding the sinusoidal influx transporters Ntcp, Oatp1 and 2 and the canalicular efflux transporter Bsep, and increased expression of canalicular Mrp2. Dose-response curves for the actions of rapamycin on the expression of Bsep and Ntcp in cultured rat hepatocytes were biphasic, and monophasic for effects on Oatp1. In cultured tumorigenic H4IIE liver cells, several bile acid transporters were not expressed, or were expressed at very low levels compared to hepatocytes. In H4IIE cells, rapamycin increased expression of Ntcp, Oatp1 and Mrp2, but decreased expression of Oatp2. It is concluded that the inhibition of bile flow recovery following ischemia observed in rapamycin-treated livers is principally due to inhibition of the expression of sinusoidal bile acid transporters. Moreover, in tumorigenic liver tissue the contribution of tumorigenic hepatocytes to total liver bile flow is likely to be small and is unlikely to be greatly affected by rapamycin.

Stauffer's syndrome: A comprehensive review and proposed updated diagnostic criteria

BACKGROUND

Stauffer's syndrome corresponds to a set of clinical and analytical changes of paraneoplastic nature firstly recognized more than 50 years ago, in association to renal cell carcinoma. A definitive review including universal diagnostic criteria and updated knowledge since the original description is lacking.

BASIC PROCEDURES

The authors conducted a comprehensive bibliographical review and propose updated diagnostic criteria to standardize diagnosis for clinical practice purposes and avoid misclassification.

MAIN FINDINGS

Although having been described in association with renal cell carcinoma, the syndrome has been reported in correlation with other malignancies-either solid or hematological tumors. Additionally, a variant syndrome presenting with jaundice has also been characterized, but appears to have a similar clinical course to that of the classical Stauffer's syndrome. Although often described as rare, it may be more frequent than previously recognized. Stauffer's syndrome etiopathogenesis is still poorly understood, but immune mechanisms seem to play a role underscored by the malignancies to which the syndrome is associated, several of which having immunotherapy drugs approved for their treatment.

PRINCIPAL CONCLUSIONS

A set of diagnostic criteria should be used to simplify, broaden and standardized diagnosis, under the entity characterized by reversible paraneoplastic intrahepatic cholestasis. Clinicians should be aware of the syndrome, namely consider further investigation if a plausible cause for unexplained intrahepatic cholestasis in an otherwise healthy patient is not found. Even though no universal approach is available, investigation should be considered regarding metastatic disease after resection of a primary tumor which has revealed persistence or recurrence of symptoms.

Biliary and pancreatic complications of molecular targeted therapies in cancer imaging

The purpose of this review is to familiarize radiologists with the different imaging manifestations of biliary and pancreatic toxicity of molecular targeted therapies. The advent of molecular targeted therapies for cancer treatment has prompted radiologists to be familiar with these new molecules, their patterns of response, and their class-specific toxicities. While liver and bowel toxicities have been extensively reported in literature, less is known about the pathogenesis and imaging of toxicity involving the pancreatobiliary system. Biliary and pancreatic toxicity of molecular targeted therapies present with variable manifestations and varying degrees of severity, from asymptomatic liver function tests elevation to acute pancreatitis or cholecystitis. Management of these conditions depends on the clinical scenario and the severity of the findings. In this article, we will (1) present the various classes of molecular targeted therapies most commonly associated with biliary and pancreatic toxicity; (2) illustrate imaging findings of drug-associated biliary and pancreatic injuries and their possible differential diagnosis; and (3) provide a guide for management of these conditions.

First human face transplantation: 5 years outcomes

BACKGROUND

The first human facial allotransplantation, a 38-year-old woman, was performed on November 27, 2005. The aesthetic aspect and functional recovery and the risk-to-benefit ratio are evaluated 5 years later.

MATERIALS AND METHODS

The facial transplantation included nose, chin, part of cheeks, and lips. The immunosuppressive protocol included tacrolimus, mycophenolate mofetil, prednisone, and antithymocyte globulins. In addition, donor bone marrow cells were infused on days 4 and 11 after transplantation.

RESULTS

The aesthetic aspect is satisfying. The patient has normal protective and discriminative sensibility. She showed a rapid motion recovery, which has remained stable for 3 years posttransplantation. She can smile, chew, swallow, and blow normally whereas pouting and kissing is still difficult. Phonation recovery was impressive therefore the patient can talk normally. Two episodes of acute rejection developed during the first year. Donor-specific anti-human leukocyte antigen antibodies were never detected. Five-year mucosal biopsy showed a slight perivascular inflammatory infiltrate while skin biopsy was normal. The main side effect of the immunosuppressive treatment was a progressive decrease in renal function, which improved after switching from tacrolimus to sirolimus. Moreover, she developed arterial hypertension, an increase in lipid levels, and in situ cervix carcinoma treated by conization. Since 2008, she showed mild cholangitis possibly caused by sirolimus. In September 2010, bilateral pneumopathy occurred and was successfully treated with antibiotics.

CONCLUSION

Despite some long-term complications, which are similar to those reported after solid organ transplantation, the patient is satisfied of her new face and has normal social interaction.