Early childhood adiposity, lifestyle and gut microbiome are linked to steatotic liver disease development in adolescents
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The role of Neuregulin-1 in steatotic and non-steatotic liver transplantation from donors after cardiocirculatory death
Liver grafts from donors after cardiocirculatory death (DCDs) are sometimes not considered for liver transplantation (LT). Plasma Neuregulin-1 (NRG1) is altered in cardiac abnormalities and the liver is one of the most important targets of NRG1. We study the role of NRG1 in DCD LT. Under these conditions, NRG1 was pharmacologically modulated and their pathways were characterized. NRG1 levels were increased in steatotic and non-steatotic grafts from DCDs; NRG1 was derived from adipose tissue. When NRG1 was inhibited, injury and inflammation were exacerbated. The benefits of endogenous NRG1 in DCD grafts were associated with increased hepatic accumulation of adipocyte-derived vascular endothelial growth factor-A (VEGFA). The Id1-Wnt2 signaling pathway was involved in the action mechanisms of endogenous VEGFA. Exogenous NRG1 exacerbated damage and inflammation. Here differential role of NRG1 (endogenous versus exogenous) was demonstrated and VEGFA treatment was proposed as a highly protective strategy in steatotic and non-steatotic DCD LT.
Microbiome-based interventions to modulate gut ecology and the immune system
The gut microbiome lies at the intersection between the environment and the host, with the ability to modify host responses to disease-relevant exposures and stimuli. This is evident in how enteric microbes interact with the immune system, e.g., supporting immune maturation in early life, affecting drug efficacy via modulation of immune responses, or influencing development of immune cell populations and their mediators. Many factors modulate gut ecosystem dynamics during daily life and we are just beginning to realise the therapeutic and prophylactic potential of microbiome-based interventions. These approaches vary in application, goal, and mechanisms of action. Some modify the entire community, such as nutritional approaches or faecal microbiota transplantation, while others, such as phage therapy, probiotics, and prebiotics, target specific taxa or strains. In this review, we assessed the experimental evidence for microbiome-based interventions, with a particular focus on their clinical relevance, ecological effects, and modulation of the immune system.
A Consensus Statement on establishing causality, therapeutic applications and the use of preclinical models in microbiome research
The gut microbiome comprises trillions of microorganisms and profoundly influences human health by modulating metabolism, immune responses and neuronal functions. Disruption in gut microbiome composition is implicated in various inflammatory conditions, metabolic disorders and neurodegenerative diseases. However, determining the underlying mechanisms and establishing cause and effect is extremely difficult. Preclinical models offer crucial insights into the role of the gut microbiome in diseases and help identify potential therapeutic interventions. The Human Microbiome Action Consortium initiated a Delphi survey to assess the utility of preclinical models, including animal and cell-based models, in elucidating the causal role of the gut microbiome in these diseases. The Delphi survey aimed to address the complexity of selecting appropriate preclinical models to investigate disease causality and to study host–microbiome interactions effectively. We adopted a structured approach encompassing a literature review, expert workshops and the Delphi questionnaire to gather insights from a diverse range of stakeholders. Experts were requested to evaluate the strengths, limitations, and suitability of these models in addressing the causal relationship between the gut microbiome and disease pathogenesis. The resulting consensus statements and recommendations provide valuable insights for selecting preclinical models in future studies of gut microbiome-related diseases.
Clostridioides difficile infection induces a pro-inflammatory and pro-steatotic metabolic state in liver
Using a multi-omics approach, this study investigated Clostridioides difficile infection (CDI) as a direct contributor to hepatic dysmetabolism. Fifty-four C57BL/6 mice were divided into Control, Antibiotic control (Abx), and C. difficile-infected (C. diff) groups. The Abx and C. diff groups received antibiotics to induce gut dysbiosis, followed by C. difficile challenge in C. diff group. Mice were euthanized after 48 h to collect samples for multi-omics analyses. Liver metabolomics and transcriptomics pathway analyses revealed significant alterations in lipid metabolism, including dysregulation in glycerolipid, steroid, and energy metabolisms in C. difficile-infected mice. Metabolites and pathways associated with oxidative stress and inflammation were enriched. Gut metagenome-liver metabolome correlation analysis identified specific bacterial species correlating with differentially enriched liver metabolites involved in oxidative stress, amino acid, and uric acid metabolism. CDI triggers metabolic shifts that could facilitate steatosis and inflammation, suggesting that CDI could be a risk factor for metabolic liver diseases.
AAV capsid prioritization in normal and steatotic human livers maintained by machine perfusion
Therapeutic efficacy and safety of adeno-associated virus (AAV) liver gene therapy depend on capsid choice. To predict AAV capsid performance under near-clinical conditions, we established side-by-side comparison at single-cell resolution in human livers maintained by normothermic machine perfusion. AAV-LK03 transduced hepatocytes much more efficiently and specifically than AAV5, AAV8 and AAV6, which are most commonly used clinically, and AAV-NP59, which is better at transducing human hepatocytes engrafted in immune-deficient mice. AAV-LK03 preferentially transduced periportal hepatocytes in normal liver, whereas AAV5 targeted pericentral hepatocytes in steatotic liver. AAV5 and AAV8 transduced liver sinusoidal endothelial cells as efficiently as hepatocytes. AAV capsid and steatosis influenced vector episome formation, which determines gene therapy durability, with AAV5 delaying concatemerization. Our findings inform capsid choice in clinical AAV liver gene therapy, including consideration of disease-relevant hepatocyte zonation and effects of steatosis, and facilitate the development of AAV capsids that transduce hepatocytes or other therapeutically relevant cell types in the human liver with maximum efficiency and specificity.
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