Detection of carcinogenic etheno-DNA adducts in children and adolescents with non-alcoholic steatohepatitis (NASH)

Epigenetic Biomarkers of Transition from Metabolically Healthy Obesity to Metabolically Unhealthy Obesity Phenotype: A Prospective Study

Background: Identifying those parameters that could potentially predict the deterioration of metabolically healthy phenotype is a matter of debate. In this field, epigenetics, in particular DNA methylation deserves special attention. Results: The aim of the present study was to analyze the long-term evolution of methylation patterns in a subset of metabolically healthy subjects in order to search for epigenetic markers that could predict the progression to an unhealthy state. Twenty-six CpG sites were significantly differentially methylated, both at baseline and 11-year follow-up. These sites were related to 19 genes or pseudogenes; a more in-depth analysis of the methylation sites of these genes showed that CYP2E1 had 50% of the collected CpG sites differently methylated between stable metabolically healthy obesity (MHO) and unstable MHO, followed by HLA-DRB1 (33%), ZBTB45 (16%), HOOK3 (14%), PLCZ1 (14%), SLC1A1 (12%), MUC2 (12%), ZFPM2 (12.5%) and HLA-DQB2 (8%). Pathway analysis of the selected 26 CpG sites showed enrichment in pathways linked to th1 and th2 activation, antigen presentation, allograft rejection signals and metabolic processes. Higher methylation levels in the cg20707527 (ZFPM2) could have a protective effect against the progression to unstable MHO (OR: 0.21, 95%CI (0.067–0.667), p < 0.0001), whilst higher methylation levels in cg11445109 (CYP2E1) would increase the progression to MUO; OR: 2.72, 95%CI (1.094–6.796), p < 0.0014; respectively). Conclusions: DNA methylation status is associated with the stability/worsening of MHO phenotype. Two potential biomarkers of the transition to an unhealthy state were identified and deserve further investigation (cg20707527 and cg11445109). Moreover, the described differences in methylation could alter immune system-related pathways, highlighting these pathways as therapeutic targets to prevent metabolic deterioration in MHO patients.

Pediatric Non-Alcoholic Fatty Liver Disease: Nutritional Origins and Potential Molecular Mechanisms

Non-alcoholic fatty liver disease (NAFLD) is the number one chronic liver disease worldwide and is estimated to affect nearly 40% of obese youth and up to 10% of the general pediatric population without any obvious signs or symptoms. Although the early stages of NAFLD are reversible with diet and lifestyle modifications, detecting such stages is hindered by a lack of non-invasive methods of risk assessment and diagnosis. This absence of non-invasive means of diagnosis is directly related to the scarcity of long-term prospective studies of pediatric NAFLD in children and adolescents. In the majority of pediatric NAFLD cases, the mechanisms driving the origin and rapid progression of NAFLD remain unknown. The progression from NAFLD to non-alcoholic steatohepatitis (NASH) in youth is associated with unique histological features and possible immune processes and metabolic pathways that may reflect different mechanisms compared with adults. Recent data suggest that circulating microRNAs (miRNAs) are important new biomarkers underlying pathways of liver injury. Several factors may contribute to pediatric NAFLD development, including high-sugar diets, in utero exposures via epigenetic alterations, changes in the neonatal microbiome, and altered immune system development and mitochondrial function. This review focuses on the unique aspects of pediatric NAFLD and how nutritional exposures impact the immune system, mitochondria, and liver/gastrointestinal metabolic health. These factors highlight the need for answers to how NAFLD develops in children and for early stage-specific interventions.

Silybin Alleviates Hepatic Steatosis and Fibrosis in NASH Mice by Inhibiting Oxidative Stress and Involvement with the Nf-κB Pathway

BACKGROUND AND AIM

Silybin is the major biologically active compound of silymarin, the standardized extract of the milk thistle (Silybum marianum). Increasing numbers of studies have shown that silybin can improve nonalcoholic steatohepatitis (NASH) in animal models and patients; however, the mechanisms underlying silybin's actions remain unclear.

METHODS

Male C57BL/6 mice were fed a methionine-choline deficient (MCD) diet for 8 weeks to induce the NASH model, and silybin was orally administered to the NASH mice. The effects of silybin on lipid accumulation, hepatic fibrosis, oxidative stress, inflammation-related gene expression and nuclear factor kappa B (NF-κB) activities were evaluated by biochemical analysis, immunohistochemistry, immunofluorescence, quantitative real-time PCR and western blot.

RESULTS

Silybin treatment significantly alleviated hepatic steatosis, fibrosis and inflammation in MCD-induced NASH mice. Moreover, silybin inhibited HSC activation and hepatic apoptosis and prevented the formation of MDBs in the NASH liver. Additionally, silybin partly reversed the abnormal expression of lipid metabolism-related genes in NASH. Further study showed that the nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway played important roles in the silybin-derived antioxidant effect, as evidenced by the upregulation of Nrf2 target genes in the silybin treatment group. In addition, silybin significantly downregulated the expression of inflammation-related genes and suppressed the activity of NF-κB signaling.

CONCLUSIONS

Silybin was effective in preventing the MCD-induced increases in hepatic steatosis, fibrosis and inflammation. The effect was related to alteration of lipid metabolism-related gene expression, activation of the Nrf2 pathway and inhibition of the NF-κB signaling pathway in the NASH liver.

DNA damage by lipid peroxidation products: implications in cancer, inflammation and autoimmunity

Oxidative stress and lipid peroxidation (LPO) induced by inflammation, excess metal storage and excess caloric intake cause generalized DNA damage, producing genotoxic and mutagenic effects. The consequent deregulation of cell homeostasis is implicated in the pathogenesis of a number of malignancies and degenerative diseases. Reactive aldehydes produced by LPO, such as malondialdehyde, acrolein, crotonaldehyde and 4-hydroxy-2-nonenal, react with DNA bases, generating promutagenic exocyclic DNA adducts, which likely contribute to the mutagenic and carcinogenic effects associated with oxidative stress-induced LPO. However, reactive aldehydes, when added to tumor cells, can exert an anticancerous effect. They act, analogously to other chemotherapeutic drugs, by forming DNA adducts and, in this way, they drive the tumor cells toward apoptosis. The aldehyde-DNA adducts, which can be observed during inflammation, play an important role by inducing epigenetic changes which, in turn, can modulate the inflammatory process. The pathogenic role of the adducts formed by the products of LPO with biological macromolecules in the breaking of immunological tolerance to self antigens and in the development of autoimmunity has been supported by a wealth of evidence. The instrumental role of the adducts of reactive LPO products with self protein antigens in the sensitization of autoreactive cells to the respective unmodified proteins and in the intermolecular spreading of the autoimmune responses to aldehyde-modified and native DNA is well documented. In contrast, further investigation is required in order to establish whether the formation of adducts of LPO products with DNA might incite substantial immune responsivity and might be instrumental for the spreading of the immunological responses from aldehyde-modified DNA to native DNA and similarly modified, unmodified and/or structurally analogous self protein antigens, thus leading to autoimmunity.

The effect of polyene phosphatidyl choline intervention on nonalcoholic steatohepatitis and related mechanism

Nonalcoholic steatohepatitis (NASH) has similar clinical pathological changes to alcoholic hepatitis. It shows increased incidence and young trend year by year. Polyene phosphatidyl choline (PPC) is widely used in clinic for liver disease treatment. The effect and mechanism of PPC on NASH have not been fully elucidated. Thirty healthy male Wistar rats were randomly equally divided into control, NASH group, and PPC group. NASH model was established by high fat diet. PPC was intraperitoneal injected to NASH rat from the second week at 80 mg/kg·d for three weeks. Body weight, liver weight index, ALT, AST, TG, and TC were tested. TNF-α and IL-1β levels were detected by ELISA. NF-κB mRNA and protein expression in liver tissue were determined by real time PCR and Western blot. SOD activity and ROS content were measured by colorimetry. NASH rat presented significantly elevated body weight and liver weight index, increased ROS content, declined SOD activity, enhanced liver function and inflammatory factors expression, and upregulated NF-κB mRNA and protein levels compared with control (P < 0.05). PPC intervention obviously reduced body weight and liver weight index, declined ROS content, amplified SOD activity, decreased liver function, weakened inflammatory factor TNF-α and IL-1β expression, and downregulated NF-κB mRNA and protein levels compared with NASH group (P < 0.05). PPC can play a treatment effect on NASH through regulating oxidative balance, inhibiting inflammatory factors and NF-κB signaling pathway.