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Archive - Mar 1, 2017

Exosome-Mediated Intercellular Communication Is Implicated in Activation of Hepatic Stellate Cells for Liver Fibrosis in Hepatitis C Virus Infection

Hepatitis C virus (HCV)-associated liver fibrosis is a critical step for end-stage liver disease progression in chronic HCV infection. Fibrogenic pathways in the liver are principally regulated by activation of hepatic stellate cells (HSC). The mechanism underlying the liver fibrosis associated with chronic HCV infection has heretofore been poorly understood. Now, scientists at St. Louis University in Missouri have conducted experiments indicating that microRNA-19a (miR-19a) is carried by exosomes from HCV-infected hepatocytes to HSC, where the miR-19a activates the HSC to produce liver fibrosis. In the HSC, miR-19a targets SOCS3, which in turn activates the STAT3-mediated transforming growth factor-beta (TGF-beta) signaling pathway and enhances fibrosis marker genes. The authors state that “Our results implicated a novel mechanism of exosome-mediated intercellular communication in the activation of HSC for liver fibrosis in HCV infection.” These results were published in the March 2017 issue of the Journal of Virology. The article is titled “Exosome-Mediated Intercellular Communication between Hepatitis C Virus-Infected Hepatocytes and Hepatic Stellate Cells.”

[Journal of Virology abstract]

Scientists Reveal Core Genes Involved in Immunity of Honey Bees

A core set of genes involved in the responses of honey bees to multiple diseases caused by viruses and parasites has been identified by an international team of researchers. The findings provide a better-defined starting point for future studies of honey-bee health, and may help scientists and beekeepers breed honey bees that are more resilient to stress. "In the past decade, honey-bee populations have experienced severe and persistent losses across the Northern Hemisphere, mainly due to the effects of pathogens, such as fungi and viruses," said Dr. Vincent Doublet, postdoctoral research fellow, University of Exeter (UK). "The genes that we identified offer new possibilities for the generation of honey-bee stocks that are resistant to these pathogens." According to the researchers, recent advances in DNA sequencing have prompted numerous investigations of the genes involved in honey-bee responses to pathogens. Yet, until now, this vast quantity of data has been too cumbersome and idiosyncratic to reveal overarching patterns in honey-bee immunity. "While many studies have used genomic approaches to understand how bees respond to viruses and parasites, it has been difficult to compare across these studies to find the core genes and pathways that help the bee fight off stressors," said Distinguished Professor of Entomology Christina Grozinger, Penn State.

Children with Particular Variation in Serotonin Transporter Gene Are Four Times More Likely to Develop Strong Attachment to Mother After Intervention; Attachment Is Measure of Psychological Security & Predictive of Future Well-Being

A child's genetic make-up can play a large, hidden role in the success of efforts to maximize his or her development, South African research suggests. The study, published online on February 28, 2017 in PLoS Medicine and supported by the Government of Canada through Grand Challenges Canada's Saving Brains program, sheds new light on why some children benefit more than others from interventions, and raises complex questions about psychosocial intervention programs in the future. The open-access article is titled “Serotonin Transporter Gene (SLC6A4) Polymorphism and Susceptibility to a Home-Visiting Maternal-Infant Attachment Intervention Delivered by Community Health Workers in South Africa: Reanalysis of a Randomized Controlled Trial.” In a study led by Professor Mark Tomlinson of Stellenbosch University in South Africa, the study followed-up on an intervention implemented between 1999 and 2003, in which expectant mothers underwent mentoring to improve attachment with their children -- attachment being a measure of a child's psychological security, and predictive of future wellbeing. In the original study, a control group of roughly equal size was composed of expectant mothers who did not receive mentoring. The original study concluded that the intervention had a small-to-moderate effect on mother-child attachment, evaluated once the children reached 18 months of age. The follow-up study, conducted thirteen years after the intervention, re-examined the original attachment results and revealed something surprising: the intervention had in fact worked well for toddlers who had a particular genetic characteristic.

Increased Expression of Immune-Stimulating Chemical Messenger LIGHT Causes Primary and Metastatic Colon Cancers to Shrink in Mouse Model

A chemical found in tumors may help stop tumor growth, according to a new study. Researchers at the University of Illinois at Chicago (UIC) report that increasing expression of a chemical cytokine called LIGHT in mice with colon cancer activated the immune system's natural cancer-killing T-cells and caused primary tumors and metastatic tumors in the liver to shrink. LIGHT is an immune-stimulating chemical messenger previously found to have low levels of expression in patients with colon cancer metastases. The results were published online on March 1, 2017 in Cancer Research. The article is titled “LIGHT Elevation Enhances Immune Eradication of Colon Cancer Metastases.” Colon cancer is the second-leading cause of cancer-related death in the U.S. and, despite advances in treatment, long-term survival of patients with liver metastases is rare. "For most patients with colon cancer that has spread to the liver, current treatments are palliative and not curative," says Dr. Ajay Maker, Associate Professor of Surgery in the UIC College of Medicine and corresponding author on the paper. "And while studies have suggested that immunotherapy may be a promising approach for advanced cancers, the use of such treatments for advanced gastrointestinal metastases has not yet been very successful." Dr. Maker, a surgical oncologist, says that this study is exciting because it looks at an immunotherapy intervention for a previously unresponsive gastrointestinal cancer. The intervention, he says, essentially trains the immune system to recognize and attack the tumor, and to protect against additional tumor formation--a significant issue in colon cancer. Dr. Maker and his colleagues established colon cancer tumors in a mouse model, in which the animals had an intact and unedited immune system.

Frogs & Toads Can See Color in Almost Total Darkness

The night vision of frogs and toads appears to be superior to that of all other animals. These amphibians have the ability to see color even when it is so dark that humans are not able to see anything at all. This has been shown in a new study by researchers from Lund University in Sweden, together with colleagues. Most vertebrates, including humans, have two types of visual cells located in the retina, namely cones and rods. The cones enable us to see color, but they usually require a significant amount of light and therefore stop working when it gets dark, in which case, the rods take over so that we can at least find our way home, albeit in black and white. In toads and frogs, the rods are a bit special, however. It was previously known that toads and frogs are unique in having rods with two different sensitivities. This has not been found in other vertebrates, and it is also the reason why researchers have long suspected that frogs and toads might be able to see color also in low-light conditions. The new study is the first to prove this to be true, and the results exceeded all expectations. "It's amazing that these animals can actually see color in extreme darkness, down to the absolute threshold of the visual system. These results were unexpected,” says Professor of Sensory Biology Almut Kelber at the Faculty of Science, Lund University. It was during the third of three experiments that the researchers discovered that frogs are able to use their rods to distinguish color in extreme darkness. The researchers studied the frogs in a situation that is as serious as it is common, namely, when frogs need to find their way out in case they are trapped in conditions of complete darkness. This is potentially an everyday occurrence, taking place in dark dens and passageways on the ground.