Role of Liver Stiffness and Alcohol on HBV Infection Pathogenesis

Hepatitis B Virus (HBV) is an infection that specifically targets hepatocytes and persistence of infection leads to inflammation and liver injury. The metabolism of alcohol is also known to cause injury and inflammation in the liver. The extent of liver damage can be analyzed by determining the pressure of the tissue with an ultrasound. As you go from a healthy liver to a fibrotic liver, the pressure increases from around 2 kPa to greater than 12.5 kPa. Previous studies have found that liver stiffness affects the primary hepatocyte function and cell interaction, but the exact mechanism behind the combined role of liver stiffness and alcohol in HBV infection is still unclear. This study aimed to determine the effect of liver stiffness and alcohol metabolism on HBV infection pathogenesis. To accomplish this aim, we used a soft and stiff liver model engineered specifically to a 2 kPa (healthy liver tissue) and 25 kPa pressure (fibrotic liver tissue). HBV transfected HepG2.2.15 cells were plated on these liver model plates. To mimic alcohol metabolism, the cells were exposed to Acetaldehyde Generating System (AGS). Results showed that liver stiffness significantly increased HBV infection markers and decreased the interferon alpha signaling by up regulating USP-18. In addition, liver stiffness increased inflammasome and pro-fibrotic markers in HBV transfected cells. The combination of alcohol metabolism with liver stiffness potentiated the HBV infection. We conclude that liver stiffness impairs interferon alpha signaling thereby increasing HBV persistence, which leads to liver inflammation and fibrosis. This study of the liver environment’s role in HBV infection and alcohol metabolism paves the way to new treatment options for patients as well as introduces more accurate lab models for research.https://digitalcommons.unmc.edu/surp2021/1023/thumbnail.jp

Increased liver stiffness promotes hepatitis B progression by impairing innate immunity in CCl4-induced fibrotic HBV\u3csup\u3e+\u3c/sup\u3e transgenic mice

Background: Hepatitis B virus (HBV) infection develops as an acute or chronic liver disease, which progresses from steatosis, hepatitis, and fibrosis to end-stage liver diseases such as cirrhosis and hepatocellular carcinoma (HCC). An increased stromal stiffness accompanies fibrosis in chronic liver diseases and is considered a strong predictor for disease progression. The goal of this study was to establish the mechanisms by which enhanced liver stiffness regulates HBV infectivity in the fibrotic liver tissue. Methods: For in vitro studies, HBV-transfected HepG2.2.15 cells were cultured on polydimethylsiloxane gels coated by polyelectrolyte multilayer films of 2 kPa (soft) or 24 kPa (stiff) rigidity mimicking the stiffness of the healthy or fibrotic liver. For in vivo studies, hepatic fibrosis was induced in C57Bl/6 parental and HBV+ transgenic (HBVTg) mice by injecting CCl4 twice a week for 6 weeks. Results: We found higher levels of HBV markers in stiff gel-attached hepatocytes accompanied by up-regulated OPN content in cell supernatants as well as suppression of anti-viral interferon-stimulated genes (ISGs). This indicates that pre-requisite “fibrotic” stiffness increases osteopontin (OPN) content and releases and suppresses anti-viral innate immunity, causing a subsequent rise in HBV markers expression in hepatocytes. In vitro results were corroborated by data from HBVTg mice administered CCl4 (HBVTg CCl4). These mice showed higher HBV RNA, DNA, HBV core antigen (HBcAg), and HBV surface antigen (HBsAg) levels after liver fibrosis induction as judged by a rise in Col1a1, SMA, MMPs, and TIMPs mRNAs and by increased liver stiffness. Importantly, CCl4-induced the pro-fibrotic activation of liver cells, and liver stiffness was higher in HBVTg mice compared with control mice. Elevation of HBV markers and OPN levels corresponded to decreased ISG activation in HBVTg CCl4 mice vs HBVTg control mice. Conclusion: Based on our data, we conclude that liver stiffness enhances OPN levels to limit anti-viral ISG activation in hepatocytes and promote an increase in HBV infectivity, thereby contributing to end-stage liver disease progression

Increased liver stiffness promotes hepatitis B progression by impairing innate immunity in CCl4-induced fibrotic HBV+ transgenic mice

BackgroundHepatitis B virus (HBV) infection develops as an acute or chronic liver disease, which progresses from steatosis, hepatitis, and fibrosis to end-stage liver diseases such as cirrhosis and hepatocellular carcinoma (HCC). An increased stromal stiffness accompanies fibrosis in chronic liver diseases and is considered a strong predictor for disease progression. The goal of this study was to establish the mechanisms by which enhanced liver stiffness regulates HBV infectivity in the fibrotic liver tissue.MethodsFor in vitro studies, HBV-transfected HepG2.2.15 cells were cultured on polydimethylsiloxane gels coated by polyelectrolyte multilayer films of 2 kPa (soft) or 24 kPa (stiff) rigidity mimicking the stiffness of the healthy or fibrotic liver. For in vivo studies, hepatic fibrosis was induced in C57Bl/6 parental and HBV+ transgenic (HBVTg) mice by injecting CCl4 twice a week for 6 weeks.ResultsWe found higher levels of HBV markers in stiff gel-attached hepatocytes accompanied by up-regulated OPN content in cell supernatants as well as suppression of anti-viral interferon-stimulated genes (ISGs). This indicates that pre-requisite “fibrotic” stiffness increases osteopontin (OPN) content and releases and suppresses anti-viral innate immunity, causing a subsequent rise in HBV markers expression in hepatocytes. In vitro results were corroborated by data from HBVTg mice administered CCl4 (HBVTg CCl4). These mice showed higher HBV RNA, DNA, HBV core antigen (HBcAg), and HBV surface antigen (HBsAg) levels after liver fibrosis induction as judged by a rise in Col1a1, SMA, MMPs, and TIMPs mRNAs and by increased liver stiffness. Importantly, CCl4-induced the pro-fibrotic activation of liver cells, and liver stiffness was higher in HBVTg mice compared with control mice. Elevation of HBV markers and OPN levels corresponded to decreased ISG activation in HBVTg CCl4 mice vs HBVTg control mice.ConclusionBased on our data, we conclude that liver stiffness enhances OPN levels to limit anti-viral ISG activation in hepatocytes and promote an increase in HBV infectivity, thereby contributing to end-stage liver disease progression

Towards a Discourse-Based Understanding of Sustainability Education and Decision Making

Based on the indeterminate character of the sustainability concept, a procedural and discursive understanding of sustainability decision making and corresponding approaches for education for sustainability (EFS) is proposed. A set of criteria for teaching strategies to promote sustainability decision making, taking into account the demands of deliberative democracy theory, are presented. These criteria (such as reason, complexity management, critical thinking, etc.) are used to argue for an educational approach that involves the development, justification, and weighting of arguments in combination with an instructional tool called Target-Mat. According to a consequent process orientation, structures for arguing or defining sustainability are not given as authorized standards. Suggestions from previous social discourse are only introduced as controversial pairings—for example, different definitions of sustainability. Examples of student decision-making processes are given to demonstrate the potential of the approach to encourage student reflection and cooperative negotiation that engenders a successive deepening of their argumentation