IFITM3 Interacts with the HBV/HDV Receptor NTCP and Modulates Virus Entry and Infection

The Na⁺/taurocholate co-transporting polypeptide (NTCP, gene symbol SLC10A1) is both a physiological bile acid transporter and the high-affinity hepatic receptor for the hepatitis B and D viruses (HBV/HDV). Virus entry via endocytosis of the virus/NTCP complex involves co-factors, but this process is not fully understood. As part of the innate immunity, interferon-induced transmembrane proteins (IFITM) 1–3 have been characterized as virus entry-restricting factors for many viruses. The present study identified IFITM3 as a novel protein–protein interaction (PPI) partner of NTCP based on membrane yeast-two hybrid and co-immunoprecipitation experiments. Surprisingly, IFITM3 knockdown significantly reduced in vitro HBV infection rates of NTCP-expressing HuH7 cells and primary human hepatocytes (PHHs). In addition, HuH7-NTCP cells showed significantly lower HDV infection rates, whereas infection with influenza A virus was increased. HBV-derived myr-preS1 peptide binding to HuH7-NTCP cells was intact even under IFITM3 knockdown, suggesting that IFITM3-mediated HBV/HDV infection enhancement occurs in a step subsequent to the viral attachment to NTCP. In conclusion, IFITM3 was identified as a novel NTCP co-factor that significantly affects in vitro infection with HBV and HDV in NTCP-expressing hepatoma cells and PHHs. While there is clear evidence for a direct PPI between IFITM3 and NTCP, the specific mechanism by which this PPI facilitates the infection process remains to be identified in future studies.     

Surface phenotypic changes of spleen cells on acquisition of encephalitogenicity

The relationship between surface marker expression and encephalitogenicity of spleen cells was studied in Lewis rats. Donors were sensitized with either BP/CFA or BP/IFA, or given BP-cultured naive spleen cells. The adoptive transfer of EAE was successfully achieved in every case after culture with BP, although only spleen cells from BP/CFA-sensitized rats proliferated significantly in response to BP. The observed encephalitogenicities were BP/CFA-sensitized cells greater than BP/IFA-sensitized cells much greater than cells from recipients of BP-cultured naive cells in descending order. In BP/CFA-sensitized cells, the expression of both W3/25 and OX-3 antigens on T cells increased markedly after culture with BP, but the expression of neither OX-19 nor OX-8 antigen increased significantly. Cells from neither BP/IFA-sensitized rats nor recipients of BP-cultured naive cells showed a significant change in the surface marker expression after culture with BP. Therefore, the generation of T cells coexpressing large amounts of both W3/25 and OX-3 antigens after culture with BP seems to correspond to the acquisition of the strong encephalitogenicity in vivo.     

Intrahepatic cholangiocarcinoma in a worker at an offset color proof‐printing company: An autopsy case report

A 40‐year‐old Japanese man visited our hospital after test results indicated elevated hepatobiliary enzymes. He had worked at a printing plant for 8 years and been exposed to organic solvents, including 1,2‐dichloropropane (1,2‐DCP) and dichloromethane (DCM). Abdominal computed tomography (CT) showed an intrahepatic tumor with dilation of the intrahepatic bile duct. He was diagnosed with intrahepatic cholangiocarcinoma. He had no known risk factors for cholangiocarcinoma. Extended left hepatectomy with lymph node dissection was performed and the tumor was histologically diagnosed as well‐differentiated adenocarcinoma. A histological examination also showed biliary intraepithelial preneoplastic lesions in non‐cancerous liver areas. Two years after surgery, the patient developed jaundice, esophageal varices and ascites. A CT examination showed liver cirrhosis without recurrence of the cholangiocarcinoma. Although a liver transplantation was planned as a therapeutic option for his liver cirrhosis, his liver failure progressed rapidly and he died before transplantation could be performed. At autopsy, fibrosis was found in the whole liver, especially in the wall of the bile duct and periductal area suggesting chronic bile duct injury due to exposure to organic solvents. Taken together, the current case may suggest that exposure to organic solvents, including 1,2‐DCP and DCM, is a risk factor for cholangiocarcinoma. Identifying risk factors for cholangiocarcinoma will help identify the mechanism and help prevent development of the disease.     

CT and MRI in the diagnosis of cardiomyopathy

Two new noninvasive imaging modalities, electron beam computed tomography (EBCT) and magnetic resonance imaging(MRI), have emerged in recent years and have provided images of the heart with high temporal and spatial resolution. They provides accurate information of myocardial thickness, ventricular shape and volume, wall motion, and ventricular function in patients with cardiomyopathy. In addition, myocardial damage can be evaluated using contrast media. They can give unique diagnostic information above and beyond that of more traditional noninvasive modalities such as two-dimensional echocardiography, left ventriculography and radionuclide technique because both modalities acquire images in three dimensions. They have a possibility to become an alternative modality of the left ventriculography in the diagnosis of cardiomyopathy.     

Variability in the Spatial Structure of the Central Loop in Cobra Cytotoxins Revealed by X-ray Analysis and Molecular Modeling

Cobra cytotoxins (CTs) belong to the three-fingered protein family and possess membrane activity. Here, we studied cytotoxin 13 from Naja naja cobra venom (CT13Nn). For the first time, a spatial model of CT13Nn with both “water” and “membrane” conformations of the central loop (loop-2) were determined by X-ray crystallography. The “water” conformation of the loop was frequently observed. It was similar to the structure of loop-2 of numerous CTs, determined by either NMR spectroscopy in aqueous solution, or the X-ray method. The “membrane” conformation is rare one and, to date has only been observed by NMR for a single cytotoxin 1 from N. oxiana (CT1No) in detergent micelle. Both CT13Nn and CT1No are S-type CTs. Membrane-binding of these CTs probably involves an additional step—the conformational transformation of the loop-2. To confirm this suggestion, we conducted molecular dynamics simulations of both CT1No and CT13Nn in the Highly Mimetic Membrane Model of palmitoiloleoylphosphatidylglycerol, starting with their “water” NMR models. We found that the both toxins transform their “water” conformation of loop-2 into the “membrane” one during the insertion process. This supports the hypothesis that the S-type CTs, unlike their P-type counterparts, require conformational adaptation of loop-2 during interaction with lipid membranes.     

The effects of cardiac resynchronization therapy on left ventricular function, myocardial energetics, and metabolic reserve in patients with dilated cardiomyopathy and heart failure

OBJECTIVES: The effects of long-term cardiac resynchronization therapy (CRT) on left ventricular (LV) energetics and metabolic reserve were evaluated. BACKGROUND: Cardiac resynchronization therapy is a new therapy for patients with drug-refractory severe heart failure (HF). METHODS: Ten patients with idiopathic dilated cardiomyopathy who had undergone implantation of biventricular pacemaker 8 +/- 5 months earlier were studied during two conditions: CRT switched on, and after CRT was switched off for 24 h. Left ventricular function was measured using echocardiography and oxidative metabolism using [(11)C]acetate positron emission tomography. Both measurements were performed at rest and during dobutamine-induced stress (5 microg/kg/min). Basal- and adenosine-stimulated (140 microg/kg/min) myocardial blood flow were quantitated using [(15)O]water. RESULTS: During CRT off, LV stroke volume was significantly reduced at rest (72 +/- 18 ml vs. 63 +/- 15 ml, p < 0.05), but LV oxidative metabolism (K(mono)) remained unchanged (0.046 +/- 0.008 vs. 0.054 +/- 0.016 min(-1)) leading to a significant deterioration of myocardial efficiency of forward work (from 48.2 +/- 16.7 to 36.6 +/- 11.7 mm Hg.l/g, p < 0.05). During dobutamine-induced stress, stroke volume and K(mono) values were not different whether CRT was on or off. However, myocardial efficiency (56.1 +/- 16.1 vs. 49.8 +/- 18.0 mm Hg.ml.g(-1).min(-1), p = 0.099) and metabolic reserve, the response of K(mono) to dobutamine (0.023 +/- 0.014 vs. 0.013 +/- 0.014 min(-1), p = 0.09), tended to reduce when CRT was switched off. Cardiac resynchronization therapy had no effects on myocardial perfusion. Natriuretic peptides increased significantly during CRT-off period. CONCLUSIONS: Long-term CRT has beneficial effects on LV function and myocardial efficiency at rest in patients with HF. These effects are not associated with changes in myocardial perfusion or oxygen consumption. During dobutamine-induced stress, CRT does not affect functional parameters, but myocardial efficiency and metabolic reserve may be increased.