Gender effect of hyperuricemia on the development of nonalcoholic fatty liver disease (NAFLD): A clinical analysis and mechanistic study

Unlocking the Therapeutic Potential of Ellagic Acid for Non-Alcoholic Fatty Liver Disease and Non-Alcoholic Steatohepatitis

Obesity is in epidemic proportions in many parts of the world, contributing to increasing rates of non-alcoholic fatty liver disease (NAFLD). NAFLD represents a range of conditions from the initial stage of fatty liver to non-alcoholic steatohepatitis (NASH), which can progress to severe fibrosis, through to hepatocellular carcinoma. There currently exists no treatment for the long-term management of NAFLD/NASH, however, dietary interventions have been investigated for the treatment of NASH, including several polyphenolic compounds. Ellagic acid is one such polyphenolic compound. Nutraceutical food abundant in ellagic acid undergoes initial hydrolysis to free ellagic acid within the stomach and small intestine. The proposed mechanism of action of ellagic acid extends beyond its initial therapeutic potential, as it is further broken down by the gut microbiome into urolithin. Both ellagic acid and urolithin have been found to alleviate oxidative stress, inflammation, and fibrosis, which are associated with NAFLD/NASH. While progress has been made in understanding the pharmacological and biological activity of ellagic acid and its involvement in NAFLD/NASH, it has yet to be fully elucidated. Thus, the aim of this review is to summarise the currently available literature elucidating the therapeutic potential of ellagic acid and its microbial-derived metabolite urolithin in NAFLD/NASH.

Protein posttranslational modifications in health and diseases: Functions, regulatory mechanisms, and therapeutic implications

Protein posttranslational modifications (PTMs) refer to the breaking or generation of covalent bonds on the backbones or amino acid side chains of proteins and expand the diversity of proteins, which provides the basis for the emergence of organismal complexity. To date, more than 650 types of protein modifications, such as the most well-known phosphorylation, ubiquitination, glycosylation, methylation, SUMOylation, short-chain and long-chain acylation modifications, redox modifications, and irreversible modifications, have been described, and the inventory is still increasing. By changing the protein conformation, localization, activity, stability, charges, and interactions with other biomolecules, PTMs ultimately alter the phenotypes and biological processes of cells. The homeostasis of protein modifications is important to human health. Abnormal PTMs may cause changes in protein properties and loss of protein functions, which are closely related to the occurrence and development of various diseases. In this review, we systematically introduce the characteristics, regulatory mechanisms, and functions of various PTMs in health and diseases. In addition, the therapeutic prospects in various diseases by targeting PTMs and associated regulatory enzymes are also summarized. This work will deepen the understanding of protein modifications in health and diseases and promote the discovery of diagnostic and prognostic markers and drug targets for diseases.

Berberine Ameliorates Metabolic-Associated Fatty Liver Disease Mediated Metabolism Disorder and Redox Homeostasis by Upregulating Clock Genes: Clock and Bmal1 Expressions

Metabolic-associated fatty liver disease (MAFLD) is one of the most common chronic liver diseases, which in turn triggers mild inflammation, metabolic dysfunction, fibrosis, and even cancer. Accumulating evidence has suggested that Berberine (BBR) could significantly improve MAFLD progression. Clock and Bmal1 as heterodimer proteins highly participated in the development of MAFLD, but whether BBR targets Clock and Bmal1 in MAFLD remains poorly understood. The result suggested that the protein levels of Clock and Bmal1 were decreased in MAFLD mice, which was negatively correlated with elevated reactive oxygen species (ROS) accumulation, the H₂O₂ level, liver inflammation, metabolic dysfunction, and insulin resistance. The mRNA and protein levels of Clock and Bmal1 were also decreased in glucosamine-induced HepG2 cells, which were are negatively related to glucose uptake, the ROS level, and the H₂O₂ level. More importantly, Bmal1 siRNA could mimic the effect of glucosamine in HepG2 cells. Interestingly, Berberine (BBR) could rescue metabolism disorder and redox homeostasis through enhancing Clock and Bmal1 expression in vivo and in vitro. Therefore, BBR might be an effective natural compound for alleviating redox homeostasis, metabolism disorder, and liver pathological changes in MAFLD by activating Clock and Bmal1 expression.

Gender-Specific and U-Shaped Relationship Between Serum Uric Acid and All-Cause Mortality Among Chinese Older Adults: A National Population-Based Longitudinal Study

Objectives: This study aimed to prospectively investigate gender-specific relationship between hyperuricemia and all-cause mortality among Chinese older adults. Methods: The study was based on the Chinese Longitudinal Healthy Longevity Survey (CLHLS) 2008-2018, a prospective nationwide cohort of older adults in China. Multivariate Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs for all-cause mortality. Restricted cubic splines (RCS) were conducted to explore the dose-response relationship between SUA levels and all-cause mortality. Results: For older women, compared to the participants in the third quartile of SUA level, those in the highest quartile of SUA was associated with significantly higher risk of all-cause mortality in the fully adjusted model (HR: 1.41, 95% CI: 1.03-1.92). No significant associations between SUA levels and all-cause mortality were observed in older men. The present study further found a U-shaped non-linear relationship between SUA levels and all-cause mortality in both sexes of older population (P for non-linear <0.05). Conclusions: This study provided prospective epidemiological evidence for the predictive role of SUA on all-cause mortality among the Chinese aging population over 10 years of follow-up, while revealing considerable gender-related differences.

Ellagic acid ameliorates high fructose-induced hyperuricemia and non-alcoholic fatty liver in Wistar rats: Focusing on the role of C1q/tumor necrosis factor-related protein-3 and ATP citrate lyase

AIMS

High-fructose intake (HF) represents an inducible risk factor for non-alcoholic fatty liver disease (NAFLD). Present study aimed to illustrate the effect of HF diet (HFD) on the induction of NAFLD, hyperuricemia and role of ellagic acid as modulator.

MAIN METHODS

Twenty-four adult male albino rats were randomly divided into four groups (6/each). The first group received normal chow diet only while the others received 60 % HFD for 4 weeks and subdivided later into 3 groups. The first and second groups received allopurinol and ellagic acid, respectively while the third group received HFD only for extra 4 weeks.

KEY FINDINGS

Rats fed on HFD for 8 weeks displayed body weight gain, insulin resistance (IR), hyperglycemia, dyslipidemia, hyperuricemia with increased oxidative stress and hepatic lipogenic enzymes such as ATP citrate lyase (ACL), aldolase B, and fatty acid synthase (FAS), sterol regulatory element-binding protein 1 (SERBP-1c). C1q /tumor necrosis factor-related protein -3 (CTRP3), and phosphorylated AMP-activated protein kinase (p-AMPK) however showed significant decreases. Ellagic acid or allopurinol administration significantly decreased serum lipids, uric acid, glucose, insulin levels and hepatic contents of enzymes. Malondialdehyde (MDA), FAS, aldolase B, SERBP-1c, and xanthine oxidase (XO) hepatic contents showed significant decreases along with glutathione (GSH) increase as compared to fructose group where ellagic acid was more remarkable compared to allopurinol.

SIGNIFICANCE

Our findings indicated that ellagic acid had alleviated HFD-induced hyperuricemia, its associated NAFLD pattern as mediated through activation of CTRP3 and inhibition of ACL activities in a pattern more remarkable than allopurinol.

Noninvasive and Individual-Centered Monitoring of Uric Acid for Precaution of Hyperuricemia via Optical Supramolecular Sensing

Characterized by an excessively increased uric acid (UA) level in serum, hyperuricemia induces gout and also poses a great threat to renal and cardiovascular systems. It is urgent and meaningful to perform early warning by noninvasive diagnosis, thus conducing to blockage of disease aggravation. Here, guanidinocalix[5]arene (GC5A) is successfully identified from the self-built macrocyclic library to specifically monitor UA from urine by the indicator displacement assay. UA is strongly bound to GC5A at micromolar-level, while simultaneously excluding fluorescein (Fl) from the GC5A·Fl complex in the "switch-on" mode. This method successfully differentiates patients with hyperuricemia from volunteers except for those with kidney dysfunction and targets a volunteer at high risk of hyperuricemia. In order to meet the trend from hospital-centered to individual-centered testing, visual detection of UA is studied through a smartphone equipped with a color-scanning feature, whose adaptability and feasibility are demonstrated in sensing UA from authentic urine, leading to a promising method in family-centered healthcare style. A high-throughput and visual detection method is provided here for alarming hyperuricemic by noninvasive diagnosis.

Association of metabolic dysfunction-associated fatty liver disease with kidney disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by the accumulation of fat in more than 5% of hepatocytes in the absence of excessive alcohol consumption and other secondary causes of hepatic steatosis. In 2020, the more inclusive term metabolic (dysfunction)-associated fatty liver disease (MAFLD) - defined by broader diagnostic criteria - was proposed to replace the term NAFLD. The new terminology and revised definition better emphasize the pathogenic role of metabolic dysfunction and uses a set of definitive, inclusive criteria for diagnosis. Diagnosis of MAFLD is based on evidence of hepatic steatosis (as assessed by liver biopsy, imaging techniques or blood biomarkers and scores) in persons who are overweight or obese and have type 2 diabetes mellitus or metabolic dysregulation, regardless of the coexistence of other liver diseases or excessive alcohol consumption. The known association between NAFLD and chronic kidney disease (CKD) and our understanding that CKD can occur as a consequence of metabolic dysfunction suggests that individuals with MAFLD - who by definition have fatty liver and metabolic comorbidities - are at increased risk of CKD. In this Perspective article, we discuss the clinical associations between MAFLD and CKD, the pathophysiological mechanisms by which MAFLD may increase the risk of CKD and the potential drug treatments that may benefit both conditions.

Stearoyl-CoA desaturase 1: A potential target for non-alcoholic fatty liver disease?-perspective on emerging experimental evidence

Non-alcoholic fatty liver disease (NAFLD) is a progressive disease and one of the leading causes of death. An unnamed disease has become a global epidemic disease of public health concern. This spectrum of diseases manifests itself with initial accumulation of excessive triglycerides (due to de novo lipogenesis) in the hepatocytes, leading to simple steatosis. Although its aetiology is multi-factorial, lifestyle changes (diet and physical activity) are considered to be the key thriving factors. In this context, high fructose consumption is associated with an increased risk for developing NAFLD in humans, while high-fructose feeding to experimental animals results in hepatic steatosis and non-alcoholic steatohepatitis, by increasing hepatic lipogenesis. Among several lipogenic genes, the endoplasmic reticulum-bound stearoyl-CoA desaturase 1 (SCD1) is the key determinant of triglycerides biosynthesis pathway, by providing monounsaturated fatty acids, through the incorporation of a double bond at the delta-9 position of saturated fatty acids, specifically, palmitic (C16:0) and stearic (C18:0) acids, yielding palmitoleic (C16:1) and oleic (C18:1) acids, respectively. Various experimental studies involving SCD1 gene knockout and diet-induced rodent models have demonstrated that SCD1 plays a key role in the development of NAFLD, by modulating hepatic lipogenesis and thus triglyceride accumulation in the liver. Several pharmacological and dietary intervention studies have shown the benefits of inhibiting hepatic SCD1 in the pathogenesis of NAFLD. In this review, we give an overview of SCD1 in NAFLD, based on the current experimental evidence and the translational applicability of SCD1 inhibition in human NAFLD conditions, besides discussing the limitations and way-forward.

A multi-targeting strategy to ameliorate high-fat-diet- and fructose-induced (western diet-induced) non-alcoholic fatty liver disease (NAFLD) with supplementation of a mixture of legume ethanol extracts

NAFLD (non-alcoholic fatty liver disease) is a multifactorial liver disease related to multiple causes or unhealthy conditions, including obesity and chronic inflammation. The accumulation of excess triglycerides, called steatosis, is known as a hallmark of an imbalance between the rates of hepatic fatty acid uptake/synthesis and oxidation/export. Furthermore, occurrence of NAFLD may lead to a cocktail of disease consequences caused by the altered metabolism of glucose, lipids, and lipoproteins, for instance, insulin resistance, type II diabetes, nonalcoholic steatohepatitis (NASH), liver fibrosis, and even hepatocarcinogenesis. Due to the complexity of the occurrence of NAFLD, a multi-targeting strategy is highly recommended to effectively address the issue and combat the causal loop. Ethanol extracts of legumes are popular supplements due to their richness and diversity in phytochemicals, especially isoflavones and anthocyanins. Although many of them have been reported to have efficacy in the treatment of different metabolic syndromes and obesity, there have not been many studies on them as a supplemental mixture. In this study, the alleviative effects of selected legume ethanol extracts (CrE) on high-fat-diet- and fructose-induced obesity, liver steatosis, and hyperglycemia are discussed. As revealed by the findings, CrE not only ameliorated obesity in terms of weight gained and enlargement of adipose tissue, but also significantly reduced the incidence of steatosis via phosphorylation of AMPK, resulting in inhibition of the downstream SREBP-1c/FAS pathway and an increase in an indicator of β-oxidation (carnitine palmitoyl transferase 1a, CPT1A). Furthermore, CrE dramatically alleviated inflammatory responses, including both plasma and hepatic TNF-α, IL-6, and MCP-1 levels. CrE also had attenuating effects on hyperglycemia and insulin resistance and significantly reduced the fasting glucose level, fasting insulin level, and plasma leptin, and it exhibited positive effects in the Oral glucose tolerance test (OGTT) and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). At the molecular level, CrE could activate the PI3K/Akt/Glut2 pathway, which indicated an increase in insulin sensitivity and glucose uptake. Taken together, these results suggest that ethanol extracts of legumes could be potential supplements for metabolic syndromes, and their efficacy and effectiveness might facilitate the multi-targeting strategy required to mitigate NAFLD.

Serum untargeted metabolomics delineates the metabolic status in different subtypes of non-alcoholic fatty liver disease

AIMS

The aim of this study was to identify novel serum metabolites associated with non-alcoholic fatty liver disease (NAFLD), and to explore the metabolic discrepancies between Lean-NAFLD and Obese-NAFLD.

METHODS

Serum samples from patients with NAFLD (n = 161) and healthy participants (n = 149) were collected, and metabolites were analyzed with UPLC-Q-TOF MS/MS. Subgroup analyses were performed to explore the metabolic differences among Lean-NAFLD, Obese-NAFLD and healthy controls RESULTS: A total of 24 differentially present metabolites were found between patients with NAFLD and healthy controls. Marked metabolic pathway differences were observed among the NAFLD subtypes, including in fatty acid and amino acid metabolism. Ultimately, five metabolites (prasterone, indoxylsulfuric acid, sebacic acid, arachidonic acid and pregnenolone sulfate) were used to establish a diagnostic model to distinguish patients with NAFLD regardless of Lean- or Obese-NAFLD type.

CONCLUSIONS

This study suggested that significant metabolic differences existed among subtypes of NAFLD, and our model might be useful to distinguish patients with NAFLD. These findings may lay a foundation for the detection and treatment of NAFLD subtypes.

Serum Uric Acid Is a Mediator of the Association Between Obesity and Incident Nonalcoholic Fatty Liver Disease: A Prospective Cohort Study

OBJECTIVE

Obesity has been demonstrated to show a consistent link with the increased possibility of nonalcoholic fatty liver disease (NAFLD). Since both serum uric acid (SUA) and obesity are essential components of metabolic syndrome (MetS), it is uncertain whether the incidence of NAFLD results from serum uric acid, obesity, or other potential factors based on previous studies.

PATIENTS AND METHODS

This study enrolled 16,839 participants with no history of alcohol consumption and no fatty liver disease in 2010. All participants completed a survey which included health and lifestyle questionnaires, and underwent physical examination, ultrasonography, and laboratory examinations of blood samples. After the four-year follow up, 5,104 (30.31%) participants were diagnosed with NAFLD. The associations between SUA, BMI or obesity, and incident NAFLD were assessed by multivariate linear regression, logistic regression analysis, and mediation analysis, respectively.

RESULTS

By adjusting demographic and serum characteristics, linear correlation coefficients between obesity and SUA were 20.26 [95% confidence interval (CI)]: 15.74, 24.77), 13.31 (95% CI: 6.63, 19.99) and 22.21 (95% CI: 16.41, 28.02) in the total population, and in the female and male groups, respectively. The odds ratios were 2.49 (95% CI: 1.61, 3.87) in the total population, 5.71 (95% CI: 2.25, 14.45) in the female group and 1.99 (95% CI: 1.15, 3.45) in the male group for the correlation between obesity and incident NAFLD. The mediation analysis showed that SUA contributed to 10.03%, 0.58%, and 12.54% of obesity-related NAFLD development in the total population, females and males, respectively.

CONCLUSION

The findings showed mediation linkages of both obesity and SUA with the incident NAFLD. The role of SUA as a mediator constitutes clinical significance that should be recognized and considered.

Gender differences in liver fibrosis among patients younger than 50 years: A retrospective cohort study

BACKGROUND & AIMS

Liver fibrosis is a metabolic disease associated with several factors, mainly age, gender, immune suppression, viral hepatitis, alcohol and metabolic diseases. Here, we are assessing the gender impact on liver status in NAFLD patients younger than 50 years.

METHODS

All males younger than 50 years and premenopausal females diagnosed with NAFLD were included in this study. Fibroscan results, demographics and clinical data were collected and analyzed by SPSS software. Patients were stratified based on fibrosis scores as mild or no fibrosis for F0-F1-F2 and severe fibrosis for F3 and F4. Data was analyzed and compared based on gender.

RESULTS

A total of 221 patients 134 males and 80 premenopausal females were included. Factors that affected liver fibrosis scores were different between males and females, where only body-mass index (BMI), white blood cells (WBC) count, and glucose level were associated with severe liver fibrosis in females. Also, liver fibrosis scores were associated with severe liver fibrosis in males only, no difference in these scores was observed in premenopausal females with severe or mild liver fibrosis.

CONCLUSIONS

Gender differences are prominent in NAFLD and different factors are associated with liver status in males as compared to females. Besides, fibrosis score could predict liver status in males but not in females. Further larger-scale studies are necessary to verify gender impact on liver fibrosis development.

Macrophages in the pathophysiology of NAFLD: The role of sex differences

Nonalcoholic fatty liver disease (NAFLD) is a multifactorial pathological condition, which recognizes a certain sexual dimorphism. Experimental and clinical studies provided evidence for a critical role of macrophages in NAFLD development and progression. Especially, liver-resident macrophages (also known as Kupffer cells) are likely the common final pathway of several pro-steatosic signals. A huge amount of danger-associated molecular patterns recognized by Kupffer cells is provided within the liver by lipid and glucose toxicity. Other pro-inflammatory signals come from surrounding tissues into the portal vein, directly to the liver: they come from dysfunctional adipocytes, adipose tissue macrophages and gut dysbiosis. These complex crosstalks are differently represented across sexes, as sexual hormones control many of these processes. Sexual dimorphism then modulates metabolic and inflammatory cascades driving the liver from a simple steatosis to NAFLD and beyond. Here, metabolic and inflammatory mechanisms underlying NALFD pathophysiology will be updated. A special attention will be paid to describe sex-related differences that could provide insights for patient stratification and more tailored therapeutic approaches.

Uricostatic and uricosuric effect of grapefruit juice in potassium oxonate-induced hyperuricemic mice

The aim of this study was to examine the preventive action of grapefruit juice (GFJ) against potassium oxonate-induced hyperuricemic mice. The results showed that GFJ significantly (p < .05) inhibit the serum and hepatic xanthine oxidase enzyme, lower uric acid level, serum creatinine, uromodulin, and blood urea nitrogen levels to normal and lower inflammation related genes IL-1β, caspase-1, NLRP3, and ASC. Furthermore, histopathology analysis revealed that GFJ markedly improve the renal and intestinal morphology. The mRNA expression of urate transporter 1, glucose transporter 9 were downregulated, whereas ATP-binding cassette transporter (ABCG2) was upregulated in the GFJ-treated group. The results of immunohistochemistry revealed that the ABCG2 protein expression in the small and large intestine was significantly upregulated after the GFJ administration. These results suggested that GFJ can be used as a urate lowering agent and future mechanistic studies should be conducted. PRACTICAL APPLICATIONS: The results of current study indicated that utilization of GFJ as an anti-hyperuricemic agent for the treatment of hyperuricemia. This article will be very valuable for all those peoples which are directly or indirectly linked with this disease.

Association of serum uric acid with visceral, subcutaneous and hepatic fat quantified by magnetic resonance imaging

Elevated serum uric acid (SUA) is associated with a variety of medical conditions, such as hypertension, diabetes and obesity. Analyses investigating uric acid and obesity were primarily conducted using anthropometric measures like BMI and waist circumference. However, different adipose tissue depots might be differentially affected in uric acid metabolism. We analyzed the relation of SUA with visceral, subcutaneous and hepatic fat as quantified by Magnetic Resonance Imaging in N = 371 individuals from a cross-sectional sample of a population-based cohort. Associations of SUA and fat depots were calculated by regressions adjusted for potential confounders. We found that SUA was correlated with all fat measures (e.g. Pearson’s r between SUA and hepatic fat: 0.50, 95%-CI: 0.42, 0.57). Associations with visceral and hepatic fat, but not with subcutaneous fat, remained evident after adjustment for anthropometric measures (e.g. visceral fat: β = 0.51 l, 95%-CI: 0.30 l, 0.72 l). In conclusion, these results show how different adipose tissue compartments are affected by SUA to varying degrees, thus emphasizing the different physiological roles of these adipose tissues in uric acid metabolism.

Constituents and Anti-Hyperuricemia Mechanism of Traditional Chinese Herbal Formulae Erding Granule

Erding granule (EDG) is a traditional Chinese medicine that has recently been identified as having anti-hypouricemic effects. However, the active components and underlying mechanism for this new indication have not been elucidated. Therefore, we compared the effects of different EDG extracts (water, 50% ethanol and 95% ethanol) on serum uric acid concentrations in the hyperuricemia model mouse. We also analyzed the constituents of different extracts by ultra-high performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) to observe the variation between the active and inactive products. Extract activity and target site were evaluated by assessing uric acid- and inflammation-suppressing effects along with evaluating ability to regulate the uric acid transporter. The results showed that the 50% ethanol extract (EDG-50) had an obvious serum uric acid concentration lowering effect compared with water (EDG-S) and the 95% ethanol extract (EDG-95). UHPLC-Q-TOF-MS/MS analysis showed that EDG-50 was compositionally different to EDG-S and EDG-95. EDG-50 showed dose-dependent effects on reducing uric acid, suppressing inflammation and regulating uric acid transporters. Moreover, western blot analysis showed that EDG-50 down-regulated GLUT9 and URAT1 expression, and up-regulated OAT1 expression. Therefore, our findings enable the preliminarily conclusion that EDG-50 lowers serum uric acid concentrations, mainly by down-regulating the expression of GLUT9 and URAT1 proteins and up-regulating the expression of OAT1 proteins. This provides a research basis for clinical use of EDG as an anti-hyperuricemic agent.