From circadian clocks to non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease and sleep disorders

Studies have shown that non-alcoholic fatty liver disease (NAFLD) may be associated with sleep disorders. In order to explore the explicit relationship between the two, we systematically reviewed the effects of sleep disorders, especially obstructive sleep apnea (OSA), on the incidence of NAFLD, and analyzed the possible mechanisms after adjusting for confounding factors. NAFLD is independently associated with sleep disorders. Different sleep disorders may be the cause of the onset and aggravation of NAFLD. An excessive or insufficient sleep duration, poor sleep quality, insomnia, sleep-wake disorders, and OSA may increase the incidence of NAFLD. Despite that some research suggests a unidirectional causal link between the two, specifically, the onset of NAFLD is identified as a result of changes in sleep characteristics, and the reverse relationship does not hold true. Nevertheless, there is still a lack of specific research elucidating the reasons behind the higher risk of developing sleep disorders in individuals with NAFLD. Further research is needed to establish a clear relationship between NAFLD and sleep disorders. This will lay the groundwork for earlier identification of potential patients, which is crucial for earlier monitoring, diagnosis, effective prevention, and treatment of NAFLD.

Shift work and nonalcoholic fatty liver disease incidence among Chinese rail workers: a 4-year longitudinal cohort study

PURPOSE

Occupational harmful factors, such as shift work, are attracting increasing attention as a potential cause of nonalcoholic fatty liver disease (NAFLD). In this study, we aimed to identify the association between shift work and NAFLD incidence in Chinese rail population.

METHODS

A cohort study was conducted among 14,112 rail workers for 4-year follow-up. Shift work frequency and other potential variables were recorded by questionnaires, including demographic, lifestyle, and occupation information. Besides, body mass index, blood pressure, fasting blood glucose, total cholesterol, triglyceride, alanine aminotransferase, and aspartate aminotransferase were measured by anthropometric measurement and blood test. Diagnosis of new NAFLD case was based on abdominal ultrasonography. Cox proportional hazards regression model was used to determine whether shift work has effect on occurrence of NAFLD.

RESULTS

The incidence of NAFLD was 30.43% in total subjects. After adjustment for possible confounders, the RRs of NAFLD were 1.069 (95% CI 0.998-1.146) and 1.179 (95% CI 1.059-1.312) in occasionally shift work group and frequently shift work group respectively, compared to the seldom shift work group. In stratified analyses, the RRs of NAFLD incidence linked to shift work exposure seems increase among female and elder. The results of three sensitivity analyses were similar with main analysis.

CONCLUSIONS

This research provided further evidence of positive harmful effect of shift work on NAFLD incidence in Chinese rail workers, particularly in frequently shift work population. The risk estimate of shift work on NAFLD was higher in female and elder.

PPAR-γ Agonist Pioglitazone Restored Mouse Liver mRNA Expression of Clock Genes and Inflammation-Related Genes Disrupted by Reversed Feeding

Introduction

The master clock, which is located in the suprachiasmatic nucleus (SCN), harmonizes clock genes present in the liver to synchronize life rhythms and bioactivity with the surrounding environment. The reversed feeding disrupts the expression of clock genes in the liver. Recently, a novel role of PPAR-γ as a regulator in correlating circadian rhythm and metabolism was demonstrated. This study examined the influence of PPAR-γ agonist pioglitazone (PG) on the mRNA expression profile of principle clock genes and inflammation-related genes in the mouse liver disrupted by reverse feeding.

Methods

Mice were randomly assigned to daytime-feeding and nighttime-feeding groups. Mice in daytime-feeding groups received food from 7 AM to 7 PM, and mice in nighttime-feeding groups received food from 7 PM to 7 AM. PG was administered in the dose of 20 mg/kg per os as aqueous suspension 40 μl at 7 AM or 7 PM. Each group consisted of 12 animals. On day 8 of the feeding intervention, mice were sacrificed by cervical dislocation at noon (05 hours after light onset (HALO)) and midnight (HALO 17). Liver expressions of Bmal1, Clock, Rev-erb alpha, Cry1, Cry2, Per1, Per2, Cxcl5, Nrf2, and Ppar-γ were determined by quantitative reverse transcription PCR. Liver expression of PPAR-γ, pNF-κB, and IL-6 was determined by Western blotting. Glucose, ceruloplasmin, total cholesterol, triglyceride concentrations, and ALT and AST activities were measured in sera by photometric methods. The null hypothesis tested was that PG and the time of its administration have no influence on the clock gene expression impaired by reverse feeding.

Results

Administration of PG at 7 AM to nighttime-feeding mice did not reveal any influence on the expression of the clock or inflammation-related genes either at midnight or at noon. In the daytime-feeding group, PG intake at 7 PM led to an increase in Per2 and Rev-erb alpha mRNA at noon, an increase in Ppar-γ mRNA at midnight, and a decrease in Nfκb (p65) mRNA at noon. In general, PG administration at 7 PM slightly normalized the impaired expression of clock genes and increased anti-inflammatory potency impaired by reversed feeding. This pattern was supported by biochemical substrate levels—glucose, total cholesterol, ALT, and AST activities. The decrease in NF-κB led to the inhibition of serum ceruloplasmin levels as well as IL-6 in liver tissue. According to our data, PG intake at 7 PM exerts strong normalization of clock gene expression with a further increase in Nrf2 and, especially, Ppar-γ and PPAR-γ expression with inhibition of Nfκb and pNF-κB expression in daytime-feeding mice. These expression changes resulted in decreased hyperglycemia, hypercholesterolemia, ALT, and AST activities. Thus, PG had a potent chronopharmacological effect when administered at 7 PM to daytime-feeding mice.

Conclusions

Our study indicates that reversed feeding induced the disruption of mouse liver circadian expression pattern of clock genes accompanied by increasing Nfκb and pNF-κB and IL-6 expression and decreasing Nrf2 and PPAR-γ. Administration of PG restored the clock gene expression profile and decreased Nfκb, pNF-κB, and IL-6, as well as increased Nrf2, Ppar-γ, and PPAR-γ expression. PG intake at 7 PM was more effective than at 7 AM in reversed feeding mice.

Top-down stepwise refinement identifies coding and noncoding RNA-associated epigenetic regulatory maps in malignant glioma

With the emergence of the molecular era and retreat of the histology epoch in malignant glioma, it is becoming increasingly necessary to research diagnostic/prognostic/therapeutic biomarkers and their related regulatory mechanisms. While accumulating studies have investigated coding gene-associated biomarkers in malignant glioma, research on comprehensive coding and noncoding RNA-associated biomarkers is lacking. Furthermore, few studies have illustrated the cross-talk signalling pathways among these biomarkers and mechanisms in detail. Here, we identified DEGs and ceRNA networks in malignant glioma and then constructed Cox/Lasso regression models to further identify the most valuable genes through stepwise refinement. Top-down comprehensive integrated analysis, including functional enrichment, SNV, immune infiltration, transcription factor binding site, and molecular docking analyses, further revealed the regulatory maps among these genes. The results revealed a novel and accurate model (AUC of 0.91 and C-index of 0.84 in the whole malignant gliomas, AUC of 0.90 and C-index of 0.86 in LGG, and AUC of 0.75 and C-index of 0.69 in GBM) that includes twelve ncRNAs, 1 miRNA and 6 coding genes. Stepwise logical reasoning based on top-down comprehensive integrated analysis and references revealed cross-talk signalling pathways among these genes that were correlated with the circadian rhythm, tumour immune microenvironment and cellular senescence pathways. In conclusion, our work reveals a novel model where the newly identified biomarkers may contribute to a precise diagnosis/prognosis and subclassification of malignant glioma, and the identified cross-talk signalling pathways would help to illustrate the noncoding RNA-associated epigenetic regulatory mechanisms of glioma tumorigenesis and aid in targeted therapy.

Sleep disruption in nonalcoholic fatty liver disease: What is the role of lifestyle and diet?

BACKGROUND

Patients with nonalcoholic fatty liver disease (NAFLD) have sleep disruption. The aim of this study is to understand how underlying factors such as diet, degree of liver disease and morningness-eveningness tendencies contribute to this sleep disruption.

METHODS

Patients with NAFLD were recruited from liver clinics at a University and Veterans Affairs practice. Patients with decompensated cirrhosis were excluded. Patients completed self-reported surveys to evaluate sleep disturbance using the Epworth Sleepiness Scale (ESS) and chronotype (circadian preference) using the morningness-eveningness questionnaire (MEQ). Information on occupation, physical activity and dietary intake were collected at clinic intake. Dietary intake was evaluated via food-frequency questionnaire and analyzed as individual categories or grouped on the basis of dietary composition.

RESULTS

A 54 patients completed the survey; 37% were female. Median ESS was 8 ± 4.2 and 37% of NAFLD patients were found to have sleep disturbance as defined by ESS >10. Sleep disturbance was common in NAFLD regardless of the liver disease stage. Dietary factors, including higher added sugar (P = 0.01), candy intake (P = 0.01), elevated Ferritin level (P = 0.04) and elevated platelet count (P = 0.05), were significantly associated with sleep disturbance. Chronotype, time to sleep, and duration of sleep were not associated with sleep disruption.

CONCLUSIONS

Sleep disruption is present in NAFLD regardless of underlying cirrhosis. Interventions aimed at improving dietary and lifestyle practices such as reduced sugar intake may help mitigate the risk for sleep disruption in NAFLD. Further longitudinal studies are needed to further delineate these links.

Role of circadian rhythm and autonomic nervous system in liver function: a hypothetical basis for improving the management of hepatic encephalopathy

Hepatic encephalopathy (HE) is a common, incapacitating complication of cirrhosis that affects many patients with cirrhosis. Although several therapies have proven effective in the treatment and prevention of this condition, several patients continue to suffer from covert disease or episodes of relapse. The circadian rhythm has been demonstrated to be pivotal for many body functions, including those of the liver. Here, we explore the impact of circadian rhythm-dependent signaling on the liver and discuss the evidence of its impact on liver pathology and metabolism. We describe the various pathways through which circadian influences are mediated. Finally, we introduce a novel method for improving patient response to drugs aimed at treating HE by utilizing the circadian rhythm. A digital system that introduces a customization-based technique for improving the response to therapies is presented as a hypothetical approach for improving the effectiveness of current medications used for the treatment of recurrent and persistent hepatic encephalopathy.

The effects of Ramadan intermittent fasting on liver function in healthy adults: A systematic review, meta-analysis, and meta-regression

INTRODUCTION

Growing evidence is suggestive that intermittent fasting likely to improve liver function; however, still the evidences are controversial to draw a definitive conclusion. Therefore, we conducted a systematic review and meta-analysis to estimate the effect size for changes in liver function tests (LFT) in healthy people practicing Ramadan diurnal intermittent fasting (RDIF), and to examine the impact of different covariates using subgroup analysis and meta-regression.

METHODS

Scientific databases were searched from date of inception in 1950 to the end of July 2020. The liver function tests searched and analyzed were aspartate transaminase (AST), alanine transaminase (ALT), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), bilirubin (BLU), L-lactate dehydrogenase (LDH) and prothrombin time (PT).

RESULTS

Twenty studies (601 adult participants in total, aged 18-57 years) conducted in 10 countries between 1987 and 2020 were identified. RDIF-induced effect sizes for the LFT expressed as standardized mean difference (SMD) [95% confidence interval] were: AST (no. of studies K = 16, number of subjects N = 502, SMD = -0.257 [-0.381, -0.133], I² = 42%); ALT (K = 16, N = 502, SMD = -0.105 [-0.282, 0.07], I² = 71%); GGT (K = 2, N = 46, SMD = -0.533 [-0.842, -0.224], I² = 0%); ALP (K = 10, N = 312, SMD = -0.318 [-0.432, -0.204], I² = 0.0%); BLU (K = 10, N = 325, SMD = -0.264 [-0.520, -0.007], I² = 70.1%); LDH (K = 5, N = 145, SMD = -0.041 [-0.380, 0.298], I² = 72%); PT (K = 2, N = 74, SMD = -0.027 [-0.732, 0.678], I² = 87%).

CONCLUSION

RDIF induces significant but small (AST, ALP, BLU) to medium (GGT) positive changes on LFT, and may confer a transient, short-term protection against fatty liver disease in healthy subjects.

Unraveling the Role of Leptin in Liver Function and Its Relationship with Liver Diseases

Since its discovery twenty-five years ago, the fat-derived hormone leptin has provided a revolutionary framework for studying the physiological role of adipose tissue as an endocrine organ. Leptin exerts pleiotropic effects on many metabolic pathways and is tightly connected with the liver, the major player in systemic metabolism. As a consequence, understanding the metabolic and hormonal interplay between the liver and adipose tissue could provide us with new therapeutic targets for some chronic liver diseases, an increasing problem worldwide. In this review, we assess relevant literature regarding the main metabolic effects of leptin on the liver, by direct regulation or through the central nervous system (CNS). We draw special attention to the contribution of leptin to the non-alcoholic fatty liver disease (NAFLD) pathogenesis and its progression to more advanced stages of the disease as non-alcoholic steatohepatitis (NASH). Likewise, we describe the contribution of leptin to the liver regeneration process after partial hepatectomy, the mainstay of treatment for certain hepatic malignant tumors.

Nonalcoholic Fatty Liver Disease Pandemic Fuels the Upsurge in Cardiovascular Diseases

Cardiovascular diseases (CVDs) remain a leading cause of death worldwide. Among the major risk factors for CVD, obesity and diabetes mellitus have received considerable attention in terms of public policy and awareness. However, the emerging prevalence of nonalcoholic fatty liver disease (NAFLD), as the most common liver and metabolic disease and a cause of CVD, has been largely overlooked. Currently, the number of individuals with NAFLD is greater than the total number of individuals with diabetes mellitus and obesity. Epidemiological studies have established a strong correlation between NAFLD and an increased risk of CVD and CVD-associated events. Although debate continues over the causal relationship between NAFLD and CVD, many mechanistic and longitudinal studies have indicated that NAFLD is one of the major driving forces for CVD and should be recognized as an independent risk factor for CVD apart from other metabolic disorders. In this review, we summarize the clinical evidence that supports NAFLD as a risk factor for CVD epidemics and discuss major mechanistic insights regarding the acceleration of CVD in the setting of NAFLD. Finally, we address the potential treatments for NAFLD and their potential impact on CVD.