Non-Alcoholic Fatty Liver Disease (NAFLD) is now the most prevalent form of chronic liver disease, affecting 10%-20% of the general paediatric population. Within the next 10 years it is expected to ...become the leading cause of liver pathology, liver failure and indication for liver transplantation in childhood and adolescence in the Western world. While our understanding of the pathophysiological mechanisms underlying this disease remains limited, it is thought to be the hepatic manifestation of more widespread metabolic dysfunction and is strongly associated with a number of metabolic risk factors, including insulin resistance, dyslipidaemia, cardiovascular disease and, most significantly, obesity. Despite this, "paediatric" NAFLD remains under-studied, under-recognised and, potentially, undermanaged. This article will explore and evaluate our current understanding of NAFLD in childhood and adolescence and how it differs from adult NAFLD, in terms of its epidemiology, pathophysiology, natural history, diagnosis and clinical management. Given the current absence of definitive radiological and histopathological diagnostic tests, maintenance of a high clinical suspicion by all members of the multidisciplinary team in primary and specialist care settings remains the most potent of diagnostic tools, enabling early diagnosis and appropriate therapeutic intervention.
Sympathetic nervous system (SNS) signalling regulates murine hepatic fibrogenesis through effects on hepatic stellate cells (HSC), and obesity-related hypertension with SNS activation accelerates ...progression of non-alcoholic fatty liver disease (NAFLD), the commonest cause of chronic liver disease. NAFLD may lead to cirrhosis. The effects of the SNS neurotransmitters norepinephrine (NE), epinephrine (EPI) and neuropeptide Y (NPY) on human primary HSC (hHSC) function and in NAFLD pathogenesis are poorly understood.
to determine the mechanistic effects of NE/EPI/NPY on phenotypic changes in cultured hHSC, and to study SNS signalling in human NAFLD livers.
Freshly isolated hHSC were assessed for expression of cathecholamine/neuropeptide Y receptors and for the synthesis of NE/EPI. The effects of NE/EPI/NPY and adrenoceptor antagonists prazosin (PRZ)/propranolol (PRL) on hHSC fibrogenic functions and the involved kinases and interleukin pathways were examined. Human livers with proven NAFLD were then assessed for upregulation of SNS signalling components.
Activated hHSC express functional α/β-adrenoceptors and NPY receptors, which are upregulated in the livers of patients with cirrhotic NAFLD. hHSC in culture synthesize and release NE/EPI, required for their optimal basal growth and survival. Exogenous NE/EPI and NPY dose-dependently induced hHSC proliferation, mediated via p38 MAP, PI3K and MEK signalling. NE and EPI but not NPY increased expression of collagen-1α2 via TGF-β without involvement of the pro-fibrogenic cytokines leptin, IL-4 and IL-13 or the anti-fibrotic cytokine IL-10.
hHSC synthesize and require cathecholamines for optimal survival and fibrogenic functionality. Activated hHSC express directly fibrogenic α/β-adrenoceptors and NPY receptors, upregulated in human cirrhotic NAFLD. Adrenoceptor and NPY antagonists may be novel anti-fibrotic agents in human NAFLD.
ObjectiveTo assess medium-term organ impairment in symptomatic individuals following recovery from acute SARS-CoV-2 infection.DesignBaseline findings from a prospective, observational cohort ...study.SettingCommunity-based individuals from two UK centres between 1 April and 14 September 2020.ParticipantsIndividuals ≥18 years with persistent symptoms following recovery from acute SARS-CoV-2 infection and age-matched healthy controls.InterventionAssessment of symptoms by standardised questionnaires (EQ-5D-5L, Dyspnoea-12) and organ-specific metrics by biochemical assessment and quantitative MRI.Main outcome measuresSevere post-COVID-19 syndrome defined as ongoing respiratory symptoms and/or moderate functional impairment in activities of daily living; single-organ and multiorgan impairment (heart, lungs, kidneys, liver, pancreas, spleen) by consensus definitions at baseline investigation.Results201 individuals (mean age 45, range 21–71 years, 71% female, 88% white, 32% healthcare workers) completed the baseline assessment (median of 141 days following SARS-CoV-2 infection, IQR 110–162). The study population was at low risk of COVID-19 mortality (obesity 20%, hypertension 7%, type 2 diabetes 2%, heart disease 5%), with only 19% hospitalised with COVID-19. 42% of individuals had 10 or more symptoms and 60% had severe post-COVID-19 syndrome. Fatigue (98%), muscle aches (87%), breathlessness (88%) and headaches (83%) were most frequently reported. Mild organ impairment was present in the heart (26%), lungs (11%), kidneys (4%), liver (28%), pancreas (40%) and spleen (4%), with single-organ and multiorgan impairment in 70% and 29%, respectively. Hospitalisation was associated with older age (p=0.001), non-white ethnicity (p=0.016), increased liver volume (p<0.0001), pancreatic inflammation (p<0.01), and fat accumulation in the liver (p<0.05) and pancreas (p<0.01). Severe post-COVID-19 syndrome was associated with radiological evidence of cardiac damage (myocarditis) (p<0.05).ConclusionsIn individuals at low risk of COVID-19 mortality with ongoing symptoms, 70% have impairment in one or more organs 4 months after initial COVID-19 symptoms, with implications for healthcare and public health, which have assumed low risk in young people with no comorbidities.Trial registration numberNCT04369807; Pre-results.
Hepatic stellate cells (HSCs), also known as perisinusoidal cells, are pericytes found in the perisinusoidal space of the liver. HSCs are the major cell type involved in liver fibrosis, which is the ...formation of scar tissue in response to liver damage. When the liver is damaged, stellate cells can shift into an activated state, characterized by proliferation, contractility and chemotaxis. The activated HSCs secrete collagen scar tissue, which can lead to cirrhosis. Recent studies have shown that in vivo activation of HSCs by fibrogenic agents can eventually lead to senescence of these cells, which would contribute to reversal of fibrosis although it may also favor the insurgence of liver cancer. HSCs in their non-active form store huge amounts of retinoic acid derivatives in lipid droplets, which are progressively depleted upon cell activation in injured liver. Retinoic acid is a metabolite of vitamin A (retinol) that mediates the functions of vitamin A, generally required for growth and development. The precise function of retinoic acid and its alterations in HSCs has yet to be elucidated, and nonetheless in various cell types retinoic acid and its receptors (RAR and RXR) are known to act synergistically with peroxisome proliferator-activated receptor gamma (PPAR-gamma) signaling through the activity of transcriptional heterodimers. Here, we review the recent advancements in the understanding of how retinoic acid signaling modulates the fibrogenic potential of HSCs and proposes a synergistic combined action with PPAR-gamma in the reversal of liver fibrosis.
After the study of the gene code as a trigger for obesity, epigenetic code has appeared as a novel tool in the diagnosis, prognosis and treatment of obesity, and its related comorbidities. This ...review summarizes the status of the epigenetic field associated with obesity, and the current epigenetic-based approaches for obesity treatment.
Thanks to technical advances, novel and key obesity-associated polymorphisms have been described by genome-wide association studies, but there are limitations with their predictive power. Epigenetics is also studied for disease association, which involves decoding of the genome information, transcriptional status and later phenotypes. Obesity could be induced during adult life by feeding and other environmental factors, and there is a strong association between obesity features and specific epigenetic patterns. These patterns could be established during early life stages, and programme the risk of obesity and its comorbidities during adult life. Furthermore, recent studies have shown that DNA methylation profile could be applied as biomarkers of diet-induced weight loss treatment.
High-throughput technologies, recently implemented for commercial genetic test panels, could soon lead to the creation of epigenetic test panels for obesity. Nonetheless, epigenetics is a modifiable risk factor, and different dietary patterns or environmental insights during distinct stages of life could lead to rewriting of the epigenetic profile.
The global prevalence of obesity‐induced liver disease (nonalcoholic fatty liver disease; NAFLD) is rising. Suggested causes include a role for in utero influences of maternal obesity compounded by ...the availability of energy‐dense foods throughout postnatal life. Using a physiologically relevant model, we investigated the role of the innate immune system in liver injury induced by maternal obesity followed by a postnatal obesogenic diet. Female C57BL/6J mice were fed a standard or obesogenic diet before and throughout pregnancy and during lactation. Female offspring were weaned onto a standard or obesogenic diet at 3 weeks postpartum. Biochemical and histological indicators of dysmetabolism, NAFLD and fibrosis, analysis of profibrotic pathways, liver innate immune cells, and reactive oxygen species (ROS) were investigated at 3, 6, and 12 months. Female offspring exposed to a postweaning obesogenic diet (OffCon‐OD) demonstrated evidence of liver injury, which was exacerbated by previous exposure to maternal obesity (OffOb‐OD), as demonstrated by raised alanine aminotransferase, hepatic triglycerides, and hepatic expression of interleukin (IL)‐6, tumor necrosis factor alpha, transforming growth factor beta, alpha smooth muscle actin, and collagen (P < 0.01). Histological evidence of hepatosteatosis and a more‐robust NAFLD phenotype with hepatic fibrosis was observed at 12 months in OffOb‐OD. A role for the innate immune system was indicated by increased Kupffer cell numbers with impaired phagocytic function and raised ROS synthesis (P < 0.01), together with reduced natural killer T cells and raised interleukin (IL)‐12 and IL‐18. Conclusion: Maternal obesity in the context of a postnatal hypercalorific obesogenic diet aggressively programs offspring NAFLD associated with innate immune dysfunction, resulting in a comprehensive phenotype that accurately reflects the human disease. (HEPATOLOGY 2013)
Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent and represents a growing challenge in terms of prevention and treatment. A minority of affected patients develops inflammation, ...subsequently fibrosis, cirrhosis and hepatocellular carcinoma (HCC). HCC is a leading cause of cancer-related death. An increased number of senescent cells correlate with age-related tissue degeneration during NAFLD-induced HCC. Senolytics are promising agents that target selectively senescent cells. Previous studies showed that whereas a combination of the senolytic drugs dasatinib and quercetin (D + Q) reduced NAFLD in mice, D + Q lacked efficacy in removing doxorubicin-induced β-gal-positive senescent cells in human HCC xenografted mice. Whether D + Q has an effect on the age-associated spectrum of NAFLD-inflammation-HCC remains unknown.
Here, we utilized an established model of age- and obesity-associated HCC, the low dose diethylnitrosamine (DEN)/high fat diet (HFD), a regimen promoting liver inflammation and tumorigenesis over a long period of 9 months. Four groups of mice each were created: group 1 included control untreated mice; group 2 included mice treated with D + Q; group 3 included mice undergoing the DEN/HFD protocol; group 4 included mice undergoing the DEN/HFD protocol with the administration of D + Q. At the end of the chemical/dietary regimen, we analyzed liver damage and cell senescence by histopathology, qPCR and immunoblotting approaches.
Unexpectedly, D + Q worsened liver disease progression in the DEN/HFD mouse model, slightly increasing histological damage and tumorigenesis, while having no effect on senescent cells removal.
In summary, using an animal model that fully recapitulates NAFLD, we demonstrate that these compounds are ineffective against age-associated NAFLD-induced HCC. Video Abstract.
Background & Aims Obesity induced, non-alcoholic fatty liver disease (NAFLD), is now the major cause in affluent countries, of the spectrum of steatosis-to-cirrhosis. Obesity and NAFLD rates in ...reproductive age women, and adolescents, are rising worldwide. Our hypothesis was that maternal obesity and lactation transmit to the offspring a pre-disposition to dysmetabolism, obesity and NAFLD. Methods Female mice were fed standard or obesogenic chow, before, throughout pregnancy, and during lactation. The critical developmental period was studied by cross-fostering offspring of lean and obese dams. Offspring were then weaned onto standard chow and studied at 3 months. Read-outs included markers of metabolic dysfunction, biochemical and histological indicators of NAFLD, induction of liver fibrogenesis, and activation of pro-fibrotic pathways. Mechanisms involved in programming a dysmetabolic and NAFLD phenotype were investigated by assaying breast milk components. Results Offspring of obese dams had a dysmetabolic, insulin resistant and NAFLD phenotype compared to offspring of lean dams. Offspring of lean dams that were suckled by obese dams showed an exaggerated dysmetabolic and NAFLD phenotype, with increased body weight, as well as increased levels of insulin, leptin, aspartate transaminase, interleukin-6, tumour necrosis factor-α, liver triglycerides, steatosis, hepatic fibrogenesis, renal norepinephrine, and liver α1-D plus β1-adrenoceptors, indicative of sympathetic nervous system activation. Obese dams also had raised breast milk leptin levels compared to lean dams. Conclusions Maternal obesity programs development of a dysmetabolic and NAFLD phenotype, which is critically dependent on the early postnatal period and possibly involving alteration of hypothalamic appetite nuclei signalling by maternal breast milk and neonatal adipose tissue derived, leptin.
Sorafenib is a small molecular inhibitor of intracellular tyrosine and serine/threonine protein kinases (VEGFR, PDGFR, CRAF and BRAF), and is thought also to induce autophagy, a chief mechanism ...influencing tumor growth. Sorafenib shows efficacy in the management of non-resectable hepatocellular carcinoma (HCC), which is refractory to other chemotherapeutic drugs. HCC represents a major end point of chronic liver diseases and the third leading cause of cancer-related death. In HCC patients Sorafenib increases overall survival compared to placebo. The most common chronic liver disease affecting up to 30% of the population in Western countries is non-alcoholic fatty liver disease (NAFLD), an intra-hepatic amassing of triglycerides deemed as the hepatic manifestation of insulin resistance and obesity. NAFLD encompasses a range of disorders with grades of liver damage varying from steatosis to non-alcoholic steatohepatitis (NASH), hallmarked by hepatocellular injury/inflammation in the presence or not of fibrosis. NAFLD patients progress to NASH in 10% of cases, which may progress to cirrhosis and HCC. Recent exciting studies uncovered a potential therapeutic role for Sorafenib that goes beyond HCC, and extends to cirrhotic portal hypertensive syndrome during cirrhosis, and to selective anti-fibrotic effects mediated through direct inhibition of activated hepatic stellate cells (HSC), the cellular mediators of intra-hepatic matrix deposition. The aim of this review is to concisely summarize our current knowledge of the biology, epidemiology and clinical aspects of HCC, as well as the previously under-appreciated therapeutic efficacy of Sorafenib beyond HCC. The review therefore utilizes data along the spectrum of liver diseases, including from experimental via pre-clinical to clinical.
Aging is a major risk factor for progression of liver diseases to hepatocellular carcinoma (HCC). Cellular senescence contributes to age-related tissue dysfunction, but the epigenetic basis ...underlying drug-induced senescence remains unclear. macroH2A1, a variant of histone H2A, is a marker of senescence-associated heterochromatic foci that synergizes with DNA methylation to silence tumor-suppressor genes in human fibroblasts. In this study, we investigated the relationship between macroH2A1 splice variants, macroH2A1.1 and macroH2A1.2, and liver carcinogenesis. We found that protein levels of both macroH2A1 isoforms were increased in the livers of very elderly rodents and humans, and were robust immunohistochemical markers of human cirrhosis and HCC. In response to the chemotherapeutic and DNA-demethylating agent 5-aza-deoxycytidine (5-aza-dC), transgenic expression of macroH2A1 isoforms in HCC cell lines prevented the emergence of a senescent-like phenotype and induced synergistic global DNA hypomethylation. Conversely, macroH2A1 depletion amplified the antiproliferative effects of 5-aza-dC in HCC cells, but failed to enhance senescence. Senescence-associated secretory phenotype and whole-transcriptome analyses implicated the p38 MAPK/IL8 pathway in mediating macroH2A1-dependent escape of HCC cells from chemotherapy-induced senescence. Furthermore, chromatin immunoprecipitation sequencing revealed that this hepatic antisenescence state also required active transcription that could not be attributed to genomic occupancy of these histones. Collectively, our findings reveal a new mechanism by which drug-induced senescence is epigenetically regulated by macroH2A1 and DNA methylation and suggest macroH2A1 as a novel biomarker of hepatic senescence that could potentially predict prognosis and disease progression.
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