Uric acid induced hepatocytes lipid accumulation through regulation of miR-149-5p/FGF21 axis

HepG2 cells do not express xanthine oxidoreductase (XOR): Implications for XOR and uric acid-related research

Although the relative extent of xanthine oxidoreductase (XOR) varies considerably in human tissues, the greatest specific activity is reported in the liver and intestines. Unlike murine models, where primary hepatocytes are readily available, human counterparts are not. As such, investigators often utilize the human carcinoma cell line HepG2 for in vitro experimentation as these cells proliferate well in culture medium. Some of the studies using HepG2 cells for proof-of-principal experimentation focus on uric acid (UA) and/or XOR activity. However, it has been reported that hepatocellular carcinoma diminishes XOR expression to nearly unmeasurable levels when compared to normal cell counterparts which posits the question of validity in the context of using HepG2 cells for XOR/UA assessments. As such, we closely examined XOR expression, protein abundance, and enzymatic activity in HepG2 cells and compared these results to an immortalized murine hepatocyte line (AML12) as well as murine liver homogenate. We report the absence of detectable XOR message, protein, and enzymatic activity in HepG2 cells. Since cellular XOR expression has been reported to be stimulated by hypoxia and serum starvation, we then exposed both AML12 and HepG2 cells to hypoxia (1% O2) for 24 h or serum starvation which impacted XOR activity in AML12 cells, but not in HepG2 cells. Knowing that several studies report XOR activity in HepG2 cells, we compared a commonly used non-selective XOR assay kit to our sensitive and selective HPLC/electrochemical assay. The kit assay indicated XOR activity in HepG2 cells; however, XOR inhibition did not diminish this activity. To account for alternative enzymatic oxidization of hypo/xanthine to UA, we investigated HepG2 cells for aldehyde oxidase (AO) abundance and found immunodetectable AO protein as well as AO-inhibitable conversion of hypoxanthine to UA; albeit, at a much slower rate when compared to XOR. In toto, these data confirm that HepG2 cells do not demonstrate XOR activity and thus commonly used kit assays for XOR, in the absence of XOR inhibitor controls, may indicate a positive response induced by an alternative source of peroxide and UA such as AO.

Association between the uric acid-to-HDL-cholesterol ratio (UHR) and the risk of cardiovascular disease and dyslipidemia: a population-based study

BACKGROUND AND AIMS

The uric acid-to-HDL-cholesterol ratio (UHR), a novel marker of metabolism and inflammation, has been investigated in various diseases. However, its potential associations with the incidence of cardiovascular disease (CVD) and dyslipidemia remain unclear. This study aimed to examine the relationships between the UHR and the incidence of CVD and dyslipidemia. The primary objective was to evaluate the role of the UHR in predicting CVD and dyslipidemia, whereas the secondary objective was to analyze the predictive effects of the UHR in different subgroups.

METHODS

We conducted a cross-sectional analysis using data from the 2001-2018 National Health and Nutrition Examination Survey (NHANES), which included 6,370 adults aged 18-80 years. Weighted binary logistic regression and subgroup analyses were performed to evaluate the independent associations between the UHR and the risk of various cardiovascular conditions, including overall CVD, congestive heart failure, myocardial infarction, angina, coronary heart disease, and dyslipidemia. To investigate potential nonlinear relationships between the UHR and these outcomes, restricted cubic spline modeling was applied to further elucidate the associations.

RESULTS

Among the 6,370 participants included in the study, 559 were diagnosed with CVD. Elevated UHR values were strongly associated with a greater incidence of CVD and its subtypes, including congestive heart failure, myocardial infarction, angina, and coronary heart disease (all P < 0.001). After accounting for weighted factors, participants in the higher UHR quartiles presented progressively higher rates of CVD: Quartile 1 (4.7%), Quartile 2 (6.3%), Quartile 3 (7.4%), and Quartile 4 (11%). A nonlinear relationship between the UHR and the risk of developing CVD was identified through restricted cubic spline (RCS) analysis. Among the subgroup of 4,117 participants with dyslipidemia, multivariable linear regression analysis demonstrated a significant positive association between the UHR and dyslipidemia (OR 17.38, 95% CI 16.24-18.60). This association remained robust even after adjusting for covariates (OR 11.65, 95% CI 8.995-15.17). RCS analysis further confirmed the nonlinear nature of this relationship. Subgroup analysis revealed no significant interaction between the UHR and overall CVD or CVD-related variables, such as congestive heart failure, myocardial infarction, angina, or coronary heart disease. However, for dyslipidemia, BMI showed a significant interaction, indicating that the positive association between the UHR and dyslipidemia risk is influenced by participants' BMI.

CONCLUSION

A high UHR is associated with an increased risk of various cardiovascular conditions and dyslipidemia. The incorporation of routine UHR monitoring into clinical practice can support the early identification of high-risk individuals, facilitate timely interventions, and reduce the burden of cardiovascular and metabolic diseases.

NAFPD exacerbation by hyperlipidemia combined with hyperuricemia: a pilot rat experiment in lipidomics

Background

Hyperuricemia and non-alcoholic fatty pancreas disease (NAFPD) are prevalent metabolic diseases, but the relationship between them remains underexplored.

Methods

Eighteen Sprague-Dawley rats were randomly assigned to three groups: normal (CON), high-fat (PO), and high-fat high-uric acid (PH). After 12 weeks, serum uric acid (SUA) and triacylglycerol levels were measured. Pathological changes in the pancreas were assessed using hematoxylin-eosin (HE) staining. Serum samples were analyzed using lipidomics technology, and multivariate statistical analysis was employed to identify differences in lipid metabolism.

Results

SUA levels in the PO group were not significantly different from those in the CON group (p > 0.05). However, from the 4th week onward, SUA levels in the PH group were significantly higher than those in both the PO and CON groups (p < 0.05). HE staining revealed that most rats in the CON group exhibited normal pancreatic islet and acinar cell morphology. The pathological NAFPD score in the PH group was higher than that in the PO group. Lipidomics analysis identified 34 potential serum biomarkers in the CON and PO groups, 38 in the CON and PH groups, and 32 in the PH and PO groups. These metabolites primarily included sphingolipids, cholesterol esters, fatty acids, triacylglycerols, phosphatidylcholines, lysophosphatidylcholine, phosphatidylethanolamine, and lysophosphatidylethanolamine.

Conclusion

Hyperlipidemia combined with hyperuricemia might exacerbates NAFPD. Glycerophospholipids may serve as key biomarkers in this process, potentially linked to a chronic inflammatory response mediated by glycerophospholipids.

A microRNA signature for valproate-induced steatosis in human hepatocytes and its application to predict fatty liver in paediatric epileptic patients on valproate therapy

Valproate (VPA) has been the first-line, most frequently prescribed antiepileptic drug in children over the past 50 years. VPA causes, idiosyncratic hepatotoxicity in some patients, who often presents with hepatic steatosis. Experimental studies also support that VPA has high potential to induce steatosis. However, there is an apparent lack of significant hepatic problems in neuropediatric units, likely because iatrogenic liver steatosis lacks specific biomarkers. Thus, it is possible that a relevant number of children under VPA have asymptomatic fatty liver. AIMS: 1) to demonstrate VPA-induced triglyceride (TG) accumulation in cultured human upcyte hepatocytes, 2) to identify miRNAs that are deregulated by VPA and associated with TG levels in these cells, and 3) to test these miRNAs, as potential non-invasive biomarkers, in plasma of paediatric epileptic patients on VPA, to identify those with a potential risk of liver steatosis. Human upcyte hepatocytes were exposed to subcytotoxic VPA concentrations. Hepatocytes increased intracellular TGs by 27 % and 45 % after 2 and 4 mM VPA for 24 h. The profiling of cellular miRNAs by microarray analysis after 4 mM VPA identified 43 deregulated human miRNAs (fold-change > 1.5 or < -1.5; FDR p<0.05). Some of them (n=11), which were validated by RTqPCR and showed correlation (Pearson r≥ 0.6) with intracellular TG levels, were selected as potential VPA-induced steatosis biomarkers. Next, we investigated the expression of these miRNAs in human plasma and found that 9 of them could be reliably quantified by RTqPCR: miR-485-3p, miR-127-3p, miR-30a-3p, miR-92b-3p, miR-212-3p, miR-182-5p, miR-183-5p, miR-500a-5p and miR-675-5p. Screening of this 9-miRNA signature in 80 paediatric epileptic patients on VPA identified 18 patients (23 %) that clustered separately because of important alterations in the selected plasma miRNAs. These patients were younger and had higher VPA blood concentrations and serum liver enzyme levels. In conclusion, VPA induced both TG accumulation and deregulation of a set of miRNAs in cultured human hepatocytes. Nine of these miRNAs have demonstrated potential as circulating biomarkers to identify VPA-induced steatosis in epileptic patients, which should require closer clinical follow-up.

Serum uric acid and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is characterized by over 5% hepatic fat accumulation without secondary causes. The prevalence of NAFLD has escalated in recent years due to shifts in dietary patterns and socioeconomic status, making it the most prevalent chronic liver disease and a significant public health concern globally. Serum uric acid (SUA) serves as the end product of purine metabolism in the body and is intricately linked to metabolic syndrome. Elevated SUA levels have been identified as an independent risk factor for the incidence and progression of NAFLD. This paper reviews the relationship between SUA and NAFLD, the underlying mechanisms of SUA involved in NAFLD, and the potential benefits of SUA-lowering therapy in treating NAFLD. The aim is to raise awareness of SUA management in patients with NAFLD, and to encourage further investigation into pharmacological interventions in this area.

Association of hyperuricemia with risk of cardiovascular disease according to the number of risk factors within target range

BACKGROUND AND AIMS

Risk factor modification may decrease the risk of cardiovascular disease (CVD). Whether risk factor modification can mitigate the effect of hyperuricemia on CVD is unclear. This study aimed to investigate the risk of CVD among individuals with hyperuricemia, according to risk factors on target, compared with controls without hyperuricemia.

METHODS AND RESULTS

This prospective study included 91,722 participants free of CVD at baseline (2006-2007) of the Kailuan study. Individuals with hyperuricemia were categorized according to the number of seven selected risk factors within the guideline-recommended target range (nonsmoking, physical activity, healthy diet, guideline-recommended levels of body mass index, blood pressure, fasting blood glucose, and total cholesterol). During a median follow-up of 13.00 years, 671 out of 6740 individuals (9.96%) with hyperuricemia and 6301 out of 84,982 control subjects (7.41%) had incident CVD. Compared with control subjects without hyperuricemia, individuals with hyperuricemia who had 4 or 5 to 7 risk factors on target had no significant excess CVD risk, the hazard ratio (HR) (95% confidence internal [CI]) was 0.93 (0.79-1.10) and 0.88 (0.71-1.10), respectively. Among individuals with hyperuricemia, excess CVD risk decreased stepwise for a higher number of risk factors on target, the HR of CVD associated with per additional risk factor within target range was 0.82 (95% CI, 0.77-0.87). Similar results were yielded for CVD subtypes.

CONCLUSIONS

Among individuals with hyperuricemia, excess CVD risk decreased stepwise for a higher number of risk factors within target.

Association Between Serum Uric Acid Levels and Metabolic-Associated Fatty Liver Disease in Southeast China: A Cross-Sectional Study

Objective

This study aimed to explore the association between serum uric acid (sUA) levels and metabolic-associated fatty liver disease (MAFLD) in Southeast China.

Methods

We performed a cross-sectional study of 2605 subjects who underwent physical examination between 2015 and 2017 in Southeast China. To explore the association between sUA levels and the risk of MAFLD, we employed logistic regression, restricted cubic spline (RCS), subgroups and multiplicative interaction analysis.

Results

Logistic regression analysis showed a positive association between sUA and MAFLD [aOR total population (95% CI)= 1.90 (1.49 ~ 2.42)], [aOR male (95% CI)= 2.01 (1.54 ~ 2.62)], [aOR female (95% CI)= 1.15 (0.62 ~ 2.11)], respectively. The RCS plot presented a significant nonlinear dose-response relationship between sUA levels and MAFLD risk, and the risk of MAFLD increased significantly when sUA> 5.56 mg/dL (P nonlinear< 0.001). Subgroups analysis revealed that the positive association between sUA and MAFLD was consistent across strata of gender, age, BMI, drinking status, smoking status and tea drinking status. Significant associations between sUA and MAFLD were not only found in males but also existed in subjects whose age ≤60, BMI ≥24 kg/m2, drinkers, smokers and tea-drinkers. Adjusted ORs were estimated to be 2.01, 1.95, 2.11, 2.29, 2.64 and 2.20, respectively. Multiplicative interactions were not observed between gender, age, drinking status, smoking status, tea drinking status and sUA (all P interaction> 0.05).

Conclusion

According to our study, sUA was positively associated with the risk of MAFLD. Additionally, the risk of MAFLD increased significantly when sUA levels exceeded 5.56 mg/dL. Our study may help clarify whether sUA plays a diagnostic role in MAFLD.

Hepatic miR-149-5p upregulation fosters steatosis, inflammation and fibrosis development in mice and in human liver organoids

Background & Aims

The incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing worldwide. Alterations of hepatic microRNA (miRNA) expression/activity significantly contribute to the development and progression of MASLD. Genetic polymorphisms of miR-149 are associated with an increased susceptibility to MASLD development in humans. Aberrant expression of miR-149 was also associated with metabolic alterations in several organs, but the impact of hepatic miR-149-5p deregulation in MASLD remains poorly characterized.

Methods

MiR-149-5p was downregulated in the livers of mice by in vivo transduction with hepatotropic adeno-associated virus 8 harboring short-hairpin RNAs (shRNAs) specific for miR-149-5p (shmiR149) or scrambled shRNAs (shCTL). MASLD was then induced with a methionine/choline-deficient (MCD, n = 7 per group) diet or a fructose/palmitate/cholesterol-enriched (FPC, n = 8-12 per group, per protocol) diet. The impact of miR-149-5p modulation on MASLD development was assessed in vivo and in vitro using multi-lineage 3D human liver organoids (HLOs) and Huh7 cells.

Results

MiR-149-5p expression was strongly upregulated in mouse livers from different models of MASLD (2-4-fold increase in ob/ob, db/db mice, high-fat and FPC-fed mice). In vivo downregulation of miR-149-5p led to an amelioration of diet-induced hepatic steatosis, inflammation/fibrosis, and to increased whole-body fatty acid consumption. In HLOs, miR-149-5p overexpression promoted lipid accumulation, inflammation and fibrosis. In vitro analyses of human Huh7 cells overexpressing miR-149-5p indicated that glycolysis and intracellular lipid accumulation was promoted, while mitochondrial respiration was impaired. Translatomic analyses highlighted deregulation of multiple potential miR-149-5p targets in hepatocytes involved in MASLD development.

Conclusions

MiR-149-5p upregulation contributes to MASLD development by affecting multiple metabolic/inflammatory/fibrotic pathways in hepatocytes. Our results further demonstrate that HLOs are a relevant 3D in vitro model to investigate hepatic steatosis and inflammation/fibrosis development.

Impact and implications

Our research shows compelling evidence that miR-149-5p plays a pivotal role in the development and progression of MASLD. By employing in vivo and innovative in vitro models using multi-lineage human liver organoids, we demonstrate that miR-149-5p upregulation significantly impacts hepatocyte energy metabolism, exacerbating hepatic steatosis and inflammation/fibrosis by modulating a wide network of target genes. These findings not only shed light on the intricate miR-149-5p-dependent molecular mechanisms underlying MASLD, but also underscore the importance of human liver organoids as valuable 3D in vitro models for studying the disease's pathogenesis.

Xanthine oxidase promotes hepatic lipid accumulation through high fat absorption by the small intestine

Background & Aims

There are no studies investigating the direct effects of elevated xanthine oxidase (XO) on lipid metabolism disorders. Here, we aimed to clarify the role of XO in lipid metabolism in a prospective cohort study and elucidate the underlying mechanisms.

Methods

The association between serum XO activity and metabolic associated steatotic liver disease (MASLD) was examined in Cox proportional hazard models in a population-based cohort of 3,358 participants (20-75 years) at baseline. In addition, mouse models were used to investigate the underlying mechanism for the association between overexpression of XO and the lipid metabolism disorders.

Results

After an average 5.8 years of follow up, we found elevated serum XO activity was associated with an increased risk of developing MASLD (hazard ratio [HR]: 2.08; 95% CI: 1.44-3.01; p-trend <0.001). Moreover, serum XO activity was significantly associated with serum triglyceride levels (r = 0.68, p <0.001). We demonstrated that hepatic XO expression increased in liver samples from patients with MASLD. Using tissue-specific Xdh knockin mice, we observed rapid lipid metabolism disorders under a high-fat diet rather than a normal chow diet. We found that XO overexpression promotes the absorption of excess dietary fat in the small intestine. Inhibition of XO also significantly reduced the absorption of fat in mice fed a high-fat diet.

Conclusions

Our study clarified the association between serum XO activity levels and the development of MASLD in a large population-based prospective cohort study. Furthermore, our mouse models demonstrated that XO overexpression promotes lipid accumulation through mechanisms involving excessive fat absorption by the small intestine.

Impact and implications

Using a prospective population-based cohort and various animal models, we have identified novel mechanisms by which xanthine oxidase regulates lipid metabolism. Our findings indicate that xanthine oxidase overexpression promotes lipid accumulation by increasing the absorption of excess dietary fat and possibly facilitating lipid transport in vivo. These results could be important for the development of therapies to treat diseases associated with lipid metabolism disorders.

Association of serum uric acid with hypertriglyceridemia in children and adolescents: a cross-sectional study

BACKGROUND

Uric acid (UA), a liver-derived metabolite, is intimately tied to metabolic disorders. Although ample research underscores its connection with hypertriglyceridemia (HTG), studies focusing on adolescents remain limited. To fill the gaps in epidemiology,this study focused on analyzing the relationship between the levels of uric acid and HTG in a demographic sample comprising adolescents from the United States.

METHODS

In this study, a total of 4,435 participants through the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2020. The exposure variable was serum uric acid (SUA), the effect variable was HTG, and the covariates included demographic, questionnaire, physical examination and laboratory indicators. We utilized weighted logistic regression and meticulous subgroup evaluations to discern the intrinsic link between SUA and HTG. Stratified analyses augmented the validation of this association, while smooth curve fitting probed for potential nonlinear correlations.

RESULTS

The study included 4,435 participants. Male adolescents exhibit elevated SUA levels. After adjusting for all variables, the weighted multiple logistic regression model revealed that SUA was positively correlated with HTG risk (OR = 1.006, 95% CI: 1.005-1.007). This relationship was consistent across the three tertiles group of SUA (T1: OR = 1.006 [95% CI: 1.005-1.007]; T2: OR = 1.006 [95% CI: 1.005-1.007]; T3: OR = 1.004 [95% CI: 1.003-1.006]; P for trend < 0.001). Stratified analyses confirmed that the positive correlation between SUA and HTG risk was significant, irrespective of sex, age or race.

CONCLUSIONS

In American children and adolescents aged 12 to 18 years, there was a pronounced association between SUA and HTG. SUA could serve as a risk indicator for HTG. It is recommended that children diagnosed with HTG should be regularly tested for SUA levels. In addition, it is recommended that SUA be included in the comprehensive care of children diagnosed with HTG.

Involvement of the vagus nerve and hepatic gene expression in serum adiponectin concentrations in mice

Several humoral factors, such as adiponectin and urate, have been suggested to affect metabolic syndromes. Previously, we reported a reduction in blood adiponectin concentrations after a high-fructose diet partially via the vagus nerve in rats. Although a lithogenic diet (LD), i.e., supplementation of a normal control diet (CT) with 0.6% cholesterol and 0.2% sodium cholate, reduced blood adiponectin concentrations, the involvement of the vagus nerve in this mechanism remains unclear. To estimate the involvement of the vagus nerve in the regulation of blood adiponectin concentrations using an LD, male imprinting control region mice that had been vagotomized (HVx) or only laparotomized (Sham) were administered a CT or an LD for 10 weeks. Serum adiponectin concentrations in the Sham-LD, HVx-CT, and HVx-LD groups were reduced by half compared with the Sham-CT group. The hepatic mRNA levels of fibroblast growth factor 21 (Fgf21), which reportedly stimulates adiponectin secretion from white adipose tissue, were lower in the LD groups compared with the CT groups. HepG2 hepatoma cells showed that various bile acids reduced the mRNA expression of FGF21. Moreover, the LD increased serum urate concentrations and reduced hepatic expressions of the acyl-CoA oxidase 1 (Acox1) mRNA and glucokinase, suggesting insufficient regeneration of ATP from AMP. In conclusion, serum adiponectin concentration may be regulated via the vagus nerve in normal mice, whereas a reduction of hepatic Fgf21 mRNA by bile acids may also lower serum adiponectin levels. Moreover, the LD may promote hepatic AMP accumulation and subsequently increase the serum urate concentration in mice.

Role of MicroRNAs in Inflammatory Joint Diseases: A Review

Inflammatory arthritis commonly initiates in the soft tissues lining the joint. This lining swells, as do the cells in it and inside the joint fluid, producing chemicals that induce inflammation signs such as heat, redness, and swelling. MicroRNA (miRNA), a subset of non-coding small RNA molecules, post-transcriptionally controls gene expression by targeting their messenger RNA. MiRNAs modulate approximately 1/3 of the human genome with their multiple targets. Recently, they have been extensively studied as key modulators of the innate and adaptive immune systems in diseases such as allergic disorders, types of cancer, and cardiovascular diseases. However, research on the different inflammatory joint diseases, such as rheumatoid arthritis, gout, Lyme disease, ankylosing spondylitis, and psoriatic arthritis, remains in its infancy. This review presents a deeper understanding of miRNA biogenesis and the functions of miRNAs in modulating the immune and inflammatory responses in the above-mentioned inflammatory joint diseases. According to the literature, it has been demonstrated that the development of inflammatory joint disorders is closely related to different miRNAs and their specific regulatory mechanisms. Furthermore, they may present as possible prognostic and diagnostic biomarkers for all diseases and may help in developing a therapeutic response. However, further studies are needed to determine whether manipulating miRNAs can influence the development and progression of inflammatory joint disorders.

Chinese herbal compound Huangqin Qingrechubi capsule reduces lipid metabolism disorder and inflammatory response in gouty arthritis via the LncRNA H19/APN/PI3K/AKT cascade

CONTEXT

Gouty arthritis (GA) is a characteristically inflammatory disease often associated with lipid metabolism disorder. Huangqin Qingrechubi capsule (HQC) has been used for the treatment of GA.

OBJECTIVE

To explore the mechanism of HQC in the treatment of GA.

MATERIALS AND METHODS

A total of 30 GA patients (GA group) and 30 healthy subjects [normal control (NC) group] were recruited. The GA group was treated with HQC (3.6 g/d) for 10 days. Lipid metabolism and inflammation indexes were detected. Five herbal names of HQC, or 'gouty arthritis', 'hyperlipidemia' and 'inflammation' were used as key words to search related databases for network pharmacological analysis. Subsequently, GA-fibroblast-like synoviocytes (FLSs) were stimulated with GA-peripheral blood mononuclear cells (PBMCs) (3:1) and treated with HQC drug-containing serum (20%). RT-qPCR, Western blot, and ELISA were conducted to further explore the mechanism of HQC in improving GA.

RESULTS

In clinical observation, HQC decreased the expression of lncRNA H19 and IL-1β, and increased the expression of adiponectin (APN) and IL-4 in the GA group (about half). Through network pharmacology, the PI3K/AKT signaling pathway was identified. Cell experiments showed that HQC treatment reduced the viability of GA-FLSs (49.61%), up-regulated the expression of IL-4 (155.18%), IL-10 (165.13%), and APN (31.24%), and down-regulated the expression of lncRNA H19 (33.70%), IL-1β (64.70%), TNF-α (78.32%), p-PI3K (48.80%), and p-AKT (53.48%).

DISCUSSION AND CONCLUSIONS

HQC improved lipid metabolism disorder and inflammatory response of GA by regulating the lncRNA H19/APN/PI3K/AKT. Maintaining the stability of lipid metabolism may be an effective way to alleviate GA.

Association between serum ferritin and uric acid levels and nonalcoholic fatty liver disease in the Chinese population

Background

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. Accumulating evidence suggests that serum ferritin and uric acid (UA) are strongly associated with the risk of NAFLD, but no consensus has been reached.

Objective

We sought to demonstrate the association between serum ferritin, UA levels, and NAFLD risk in a large cohort study.

Methods

We separated 2,049 patients into non-NAFLD and NAFLD groups. The NAFLD group had four subgroups based on serum ferritin and four subgroups based on UA quartile levels. We used binary logistic regression to evaluate the correlation between serum ferritin, UA, and NAFLD. Additionally, an area under the curve (AUC) of receiver operating characteristic analysis (ROC) was used to predict the diagnostic value of combined serum ferritin and UA for NAFLD.

Results

Serum ferritin and UA levels were higher in the NAFLD group compared with the non-NAFLD group. Serum lipid and liver transaminase concentrations were elevated with the increase of serum ferritin and UA. The logistic regression results showed an independent correlation between serum ferritin, UA, and NAFLD. In the NAFLD group, the AUC value of serum ferritin and UA was 0.771.

Conclusions

Increased serum ferritin and UA levels are independent risk factors for NAFLD. Increased serum UA is a stronger risk factor for NAFLD than elevated serum ferritin. Serum ferritin and UA can be important predictors of NAFLD risk.

The regulatory role of differential microRNA expressions on cellular inflammatory factors IL-6 and IL-10 in Echinococcus granulosus-induced anaphylaxis

OBJECTIVE

To determine the pathogenesis and molecular targets of anaphylaxis caused by hydatid cyst fluid leakage.

METHODS

First, Balb/c mice were infected with Echinococcus granulosus, and then the anaphylaxis model was developed. The mice were separated into: anaphylaxis caused by the cystic echinococcosis group (ANPC), the cystic echinococcosis without anaphylaxis group (CE group), and the normal control group (CTRL). Following this, the spleen tissue was collected for microRNA (miRNA) sequencing. Using bioinformatics analysis, differentially expressed miRNAs (DEMs) were identified. Then, through the use of protein-protein interaction (PPI) networks, the key target genes for miRNA regulation associated with echinococcosis-induced anaphylaxis were identified.

RESULTS

ANPC and CE groups have 29 and 39 DEMs compared to the CTRL group, respectively. Based on these 25 DEMs, interactions between miRNA and mRNA were screened, and 174 potential target genes were identified. We performed gene ontology (GO) function and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis on these 174 target genes, and the results revealed that the three pathways with the highest enrichment were the PI3K-Akt signaling pathway, FoxO signaling pathway, and Focal adhesion. The interaction analysis of PPI and miRNA-hub gene networks revealed that interleukin 6 (IL-6) was regulated by miR-146a-5p and miR-149-5p, while IL-10 was regulated by miR-29b-3p and miR-29c-3. Using reverse transcription polymerase chain reaction, we found that the miRNAs regulating IL-6 and IL-10 were significantly upregulated in the ANPC group, and there are three pathways involved in that process: Pathways of PI3K-Akt signaling, FoxO signaling, and Focal adhesion. IL-6 and IL-10 play an important role in cellular pyroptosis and apoptosis. Therefore, the aforementioned results provide significant reference value for elucidating the mechanism of cellular pyroptosis and apoptosis in echinococcosis-induced anaphylaxis, and for formulating tissue and organ protection strategies for patients with cystic echinococcosis when anaphylaxis is triggered by hydatid cyst rupture.

Characterizations of microRNAs involved in the molecular mechanisms underlying the therapeutic effects of noni (Morinda citrifolia L.) fruit juice on hyperuricemia in mice

BACKGROUND

Hyperuricemia is generally defined as the high level of serum uric acid and is well known as an important risk factor for the development of various medical disorders. However, the medicinal treatment of hyperuricemia is frequently associated with multiple side-effects.

METHODS

The therapeutic effect of noni (Morinda citrifolia L.) fruit juice on hyperuricemia and the underlying molecular mechanisms were investigated in mouse model of hyperuricemia induced by potassium oxonate using biochemical and high-throughput RNA sequencing analyses.

RESULTS

The levels of serum uric acid (UA) and xanthine oxidase (XOD) in mice treated with noni fruit juice were significantly decreased, suggesting that the noni fruit juice could alleviate hyperuricemia by inhibiting the XOD activity and reducing the level of serum UA. The contents of both serum creatinine and blood urine nitrogen of the noni fruit juice group were significantly lower than those of the model group, suggesting that noni fruit juice promoted the excretion of UA without causing deleterious effect on the renal functions in mice. The differentially expressed microRNAs involved in the pathogenesis of hyperuricemia in mice were identified by RNA sequencing with their target genes further annotated based on both Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases to explore the metabolic pathways and molecular mechanisms underlying the therapeutic effect on hyperuricemia by noni fruit juice.

CONCLUSION

Our study provided strong experimental evidence to support the further investigations of the potential application of noni fruit juice in the treatment of hyperuricemia.

Therapeutic Effects of microRNAs on Nonalcoholic Fatty Liver Disease (NAFLD) and Nonalcoholic Steatohepatitis (NASH): A Systematic Review and Meta-Analysis

Nonalcoholic fatty liver disease (NAFLD) has emerged as a global health problem that affects people even at young ages due to unhealthy lifestyles. Without intervention, NAFLD will develop into nonalcoholic steatohepatitis (NASH) and eventually liver cirrhosis and hepatocellular carcinoma. Although lifestyle interventions are therapeutic, effective implementation remains challenging. In the efforts to establish effective treatment for NAFLD/NASH, microRNA (miRNA)-based therapies began to evolve in the last decade. Therefore, this systematic review aims to summarize current knowledge on the promising miRNA-based approaches in NAFLD/NASH therapies. A current systematic evaluation and a meta-analysis were conducted according to the PRISMA statement. In addition, a comprehensive exploration of PubMed, Cochrane, and Scopus databases was conducted to perform article searches. A total of 56 different miRNAs were reported as potential therapeutic agents in these studies. miRNA-34a antagonist/inhibitor was found to be the most studied variant (n = 7), and it significantly improved the hepatic total cholesterol, total triglyceride, Aspartate Aminotransferase (AST), and Alanine Transaminase (ALT) levels based on a meta-analysis. The biological processes mediated by these miRNAs involved hepatic fat accumulation, inflammation, and fibrosis. miRNAs have shown enormous therapeutic potential in the management of NAFLD/NASH, wherein miRNA-34a antagonist has been found to be an exceptional potential agent for the treatment of NAFLD/NASH.

THE THERAPEUTIC EFFECT OF ALLOPURINOL IN FATTY LIVER DISEASE IN RATS

Background

Hyperuricemia is associated with non-alcoholic fatty liver disease (NAFLD).

Aim

We therefore aimed at evaluating the influence of allopurinol on the course of NAFLD in rats.

Study Design

We divided 21 mature albino Sprague Dawley rats into three groups: controls (n = 7, normal diet for 12 weeks); NAFLD rat models (by feeding water containing 30% fructose for first 8 weeks) treated with allopurinol subsequently for the next 4 weeks (n = 7); and similar case treated with placebo (saline) subsequently for the next 4 weeks (n = 7).

Methods

We compared the histopathological scores, IL-1 and IL-2 immunoexpression levels across the groups. Liver histopathological score was determined by observing the steatosis (the percentage of liver cells containing fat): <25% = 1+, 25% - 50% = 2+, 51% - 75% = 3+, >75% = 4+; inflammation and necrosis: 1 focus per low-power field = 1+; and 2 or more foci = 2+. The number of liver IL-1 and IL-2 positive cells was measured by systematically scoring at least 100 hepatocyte cells per field in 10 fields of tissue sections by a magnification of 100.

Results

Xanthine oxidase (XO) activity and lipid peroxidation was significantly different in the allopurinol group compared to the saline group (XO; 0.098 ± 0.006 mU/mg vs. 0.162 ± 0.008 mU/mg, p = 0.01, 0.116 ± 0.040 nmol malondialdehyde/mg versus 0.246 ± 0.040 nmol malondialdehyde /mg, p = 0.01). The allopurinol group had lower histopathological scores, IL-1 and IL-2 immunoexpression levels in the liver compared to the saline group (2.13 ± 0.35 against 5.45 ± 0.24, p = 0.003, IL-1; 5.76 ± 0.43 against 12.85 ± 3.26, p = 0.023, IL-2; 8.55 ± 1.14 against 56.23 ± 7.12, p = 0.002).

Conclusions

Allopurinol has a therapeutic role against the progression of NAFLD of the rats.

HDAC Inhibitors Alleviate Uric Acid-Induced Vascular Endothelial Cell Injury by Way of the HDAC6/FGF21/PI3K/AKT Pathway

ABSTRACT

Uric acid (UA) accumulation triggers endothelial dysfunction, oxidative stress, and inflammation. Histone deacetylase (HDAC) plays a vital role in regulating the pathological processes of various diseases. However, the influence of HDAC inhibitor on UA-induced vascular endothelial cell injury (VECI) remains undefined. Hence, this study aimed to investigate the effect of HDACs inhibition on UA-induced vascular endothelial cell dysfunction and its detailed mechanism. UA was used to induce human umbilical vein endothelial cell (HUVEC) injury. Meanwhile, potassium oxonate-induced and hypoxanthine-induced hyperuricemia mouse models were also constructed. A broad-spectrum HDAC inhibitor trichostatin A (TSA) or selective HDAC6 inhibitor TubastatinA (TubA) was given to HUVECs or mice to determine whether HDACs can affect UA-induced VECI. The results showed pretreatment of HUVECs with TSA or HDAC6 knockdown-attenuated UA-induced VECI and increased FGF21 expression and phosphorylation of AKT, eNOS, and FoxO3a. These effects could be reversed by FGF21 knockdown. In vivo, both TSA and TubA reduced inflammation and tissue injury while increased FGF21 expression and phosphorylation of AKT, eNOS, and FoxO3a in the aortic and renal tissues of hyperuricemia mice. Therefore, HDACs, especially HDAC6 inhibitor, alleviated UA-induced VECI through upregulating FGF21 expression and then activating the PI3K/AKT pathway. This suggests that HDAC6 may serve as a novel therapeutic target for treating UA-induced endothelial dysfunction.

Coronary artery disease patient-derived iPSC-hepatocytes have distinct miRNA profile that may alter lipid metabolism

Metabolic dysfunction, partly driven by altered liver function, predisposes to coronary artery disease (CAD), but the role of liver in vulnerable atherosclerotic plaque development remains unclear. Here we produced hepatocyte-like cells (HLCs) from 27 induced pluripotent stem cell (iPSC) lines derived from 15 study subjects with stable CAD (n = 5), acute CAD (n = 5) or healthy controls (n = 5). We performed a miRNA microarray screening throughout the differentiation, as well as compared iPSC-HLCs miRNA profiles of the patient groups to identify miRNAs involved in the development of CAD. MicroRNA profile changed during differentiation and started to resemble that of the primary human hepatocytes. In the microarray, 35 and 87 miRNAs were statistically significantly deregulated in the acute and stable CAD patients, respectively, compared to controls. Down-regulation of miR-149-5p, -92a-3p and -221-3p, and up-regulation of miR-122-5p was verified in the stable CAD patients when compared to other groups. The predicted targets of deregulated miRNAs were enriched in pathways connected to insulin signalling, inflammation and lipid metabolism. The iPSC-HLCs derived from stable CAD patients with extensive lesions had a distinct genetic miRNA profile possibly linked to metabolic dysfunction, potentially explaining the susceptibility to developing CAD. The iPSC-HLCs from acute CAD patients with only the acute rupture in otherwise healthy coronaries did not present a distinct miRNA profile, suggesting that hepatic miRNAs do not explain susceptibility to plaque rupture.

Liver-derived metabolites as signaling molecules in fatty liver disease

Excessive fat accumulation in the liver has become a major health threat worldwide. Unresolved fat deposition in the liver can go undetected until it develops into fatty liver disease, followed by steatohepatitis, fibrosis, cirrhosis, and eventually hepatocellular carcinoma. Lipid deposition in the liver is governed by complex communication, primarily between metabolic organs. This can be mediated by hormones, organokines, and also, as has been more recently discovered, metabolites. Although how metabolites from peripheral organs affect the liver is well documented, the effect of metabolic players released from the liver during the development of fatty liver disease or associated comorbidities needs further attention. Here we focus on interorgan crosstalk based on metabolites released from the liver and how these molecules act as signaling molecules in peripheral tissues. Due to the liver's specific role, we are covering lipid and bile mechanism-derived metabolites. We also discuss the high sucrose intake associated with uric acid release from the liver. Excessive fat deposition in the liver during fatty liver disease development reflects disrupted metabolic processes. As a response, the liver secretes a variety of signaling molecules as well as metabolites which act as a footprint of the metabolic disruption. In the coming years, the reciprocal exchange of metabolites between the liver and other metabolic organs will gain further importance and will help to better understand the development of fatty liver disease and associated diseases.

MicroRNA-376b-3p ameliorates nonalcoholic fatty liver disease by targeting FGFR1 and regulating lipid oxidation in hepatocytes

AIMS

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease whose molecular mechanisms remain unclear. This study aimed to explore the role and mechanisms of microRNA-376b-3p in NAFLD.

MATERIALS AND METHODS

We used a microarray to reveal hepatic microRNA expression profiles and validated their expression in cellular and mouse models via qRT-PCR. In vitro, the expression of microRNA-376b-3p was increased by a microRNA-376b-3p mimic and decreased by a microRNA-376b-3p inhibitor. The role and potential mechanisms of microRNA-376b-3p in NAFLD were investigated in mice injected with lentiviral vectors before high-fat diet (HFD) feeding, and the direct target gene was explored using a dual-luciferase reporter gene assay and confirmed by Western blotting.

KEY FINDINGS

Microarray analysis and subsequent validation showed that the expression of microRNA-376b-3p was downregulated by nearly 90 % in the livers of HFD-fed mice and by >50 % in free fatty acid-stimulated hepatocytes. Overexpression of microRNA-376b-3p markedly ameliorated hepatic lipid accumulation, which was attributable to an increase in fatty acid oxidation. Conversely, inhibition of miR-376b-3p exhibited the opposite effects. The luciferase reporter assay indicated that Fgfr1 is a direct target gene of miR-376b-3p. Fgfr1 intervention eliminated the effect of miR-376b-3p on the lipid oxidation pathway and hepatocyte steatosis, which suggests that miR-376b-3p regulates fatty acid oxidation by targeting Fgfr1 to influence NAFLD development.

SIGNIFICANCE

miR-376b-3p was downregulated in NAFLD and has a novel regulatory role in lipid oxidation through a miR-376b-3p-Fgfr1-dependent mechanism. Thus, miR-376b-3p may serve as a potential diagnostic marker or therapeutic target for NAFLD.

Potential Mechanisms of Gut-Derived Extracellular Vesicle Participation in Glucose and Lipid Homeostasis

The intestine participates in the regulation of glucose and lipid metabolism in multiple facets. It is the major site of nutrient digestion and absorption, provides the interface as well as docking locus for gut microbiota, and harbors hormone-producing cells scattered throughout the gut epithelium. Intestinal extracellular vesicles are known to influence the local immune response, whereas their roles in glucose and lipid homeostasis have barely been explored. Hence, this current review summarizes the latest knowledge of cargo substances detected in intestinal extracellular vesicles, and connects these molecules with the fine-tuning regulation of glucose and lipid metabolism in liver, muscle, pancreas, and adipose tissue.

CircSETBP1 Acts as a MiR-149-5p Sponge to Promote Intramuscular Fat Deposition by Regulating CRTCs

Circular RNAs (circRNAs) appear to be crucial in the process of adipogenesis according to mounting data. CircSETBP1 is a newly discovered circRNA associated with adipogenesis. Sequencing verification and RNase R treatment have confirmed the circular nature of circSETBP1 in porcine tissue. The precise function and mechanism of circSETBP1 in adipocyte biology are still unclear. Cell counting kit-8 (CCK8), Oil red O staining, and quantitative real-time polymerase chain reaction (qRT-PCR) were employed in this investigation to reveal the functions of circSETBP1 and miR-149-5p in the growth and development of porcine intramuscular (IM) preadipocytes. CircSETBP1 overexpression accelerated cell differentiation while reducing cell proliferation. The opposite outcome was produced by overexpressing miR-149-5p. Meanwhile, circSETBP1 down-regulated the expression of miR-149-5p and miR-149-5p restrained the expression of CRTC1/CRTC2. CircSETBP1 was directly targeted by miR-149-5p, and CRTC1/CRTC2 were the target genes of miR-149-5p using bioinformatic analysis, the dual-Luciferase reporter system, and qRT-PCR. In conclusion, circSETBP1 controls the proliferation and differentiation of porcine IM preadipocytes and 3T3-L1 cells by regulating the miR-149-5p/CRTCs axis. The results of this study not only illuminate the molecular mechanism of circSETBP1/miR-149-5p involved in the deposition of porcine intramuscular fat (IMF), but they also provide a significant theoretical reference for raising quality of pork.

Angiopoietin-Like Protein 4 May Be an Interplay Between Serum Uric Acid and Triglyceride-Rich Lipoprotein Cholesterol

Background

Although the available evidence has indicated a link between elevated serum uric acid (SUA) level and dyslipidemia, the potential contribution of SUA on lipid profiles remains unclear. Experimental and clinical studies have revealed several mechanisms through which high serum angiopoietin-like protein 4 (ANGPTL4) level exerts deleterious effects on lipid metabolism, but the role of ANGPTL4 in SUA-associated dyslipidemia has not been well studied, so far.

Methods

A total of 80 subjects were classified into high SUA group (n = 40) and low SUA group (n = 40) by the median value of SUA in the whole study population. Serum ANGPTL4 levels were determined by enzyme-linked immunosorbent assays.

Results

In our study, we observed that not only serum triglyceride level [1.03 (0.78, 1.50) mmol/L vs. 1.59 (1.18, 2.37) mmol/L, p = 0.001] but also serum triglyceride-rich lipoprotein cholesterol (TRL-C) level [0.38 (0.32, 0.45) mmol/L vs. 0.46 (0.34, 0.54) mmol/L, p = 0.012] were significantly elevated in high SUA group. Additionally, serum ANGPTL4 in high SUA group was higher than in low SUA group [15.81 (11.88, 20.82) ng/ml vs. 22.13 (17.88, 32.09) ng/ml, p = 0.000]. Moreover, in all subjects, TRL-C levels were positively associated with SUA (r = 0.26, p = 0.023, n = 80) and ANGPTL4 levels (r = 0.24, p = 0.036, n = 80). Using stepwise multiple regression analysis to adjust for potential confounders, SUA was discovered to be an independent contributor to serum ANGPTL4 (p = 0.023). At the same time, serum ANGPTL4 was an independent contributor to the level of TRL-C (p = 0.000). However, the correlation between SUA and TRL-C disappeared after controlling for ANGPTL4 level.

Conclusion

Serum uric acid was positively correlated to TRL-C. ANGPTL4 may be an interplay between SUA and associated elevation of TRL-C.

Identification and Validation of Novel Diagnostic Biomarkers for Keloid Based on GEO Database

Introduction

Keloid is a pathological scar type, which invades normal surrounding tissue without self-limiting to cause pain, itching, cosmetic disfigurement, etc. Knowledge of the molecular mechanisms underlying keloid remains unclear. This dilemma leads to no biomarker available for diagnosis. Thus, to seek accurate diagnosis, biomarkers are necessary for keloid diagnosis to help control its incidence.

Methods

Gene Expression Omnibus (GEO) database was used to select differentially expressed miRNAs (DE-miRNAs) in GSE113620. miRTarBase miRNA–target tools were used to predict the interactions between miRNAs and their target mRNAs. Target mRNAs that were differentially expressed in keloid were selected by analyzing differentially expressed genes (DEGs) in GSE44270 and GSE92566. PPI network analysis, gene enrichment analysis, cell-specific and tissue-specific expression analyses of DE-target mRNAs were conducted. RT-PCR analysis was conducted to validate our results.

Results

Three novel miRNAs (miR-30b-5p, miR-212-3p, miR-149-5p) and five target mRNAs (SIX1, CCNA2, CCNB1, FOXM1, RUNX2) were identified as potential biomarkers for keloid patients. Additionally, the potential functions of those miRNAs-mRNAs pathways were analyzed.

Discussion

These findings of keloid-related miRNAs, mRNAs, and miRNA–mRNAs regulatory networks may provide insights into the underlying pathogenesis of keloid and serve as potential biomarkers for keloid diagnosis.

Role of microRNA alternation in the pathogenesis of gouty arthritis

Gouty arthritis is a common inflammatory disease. The condition is triggered by a disorder of uric acid metabolism, which causes urate deposition and gout flares. MicroRNAs are a class of conserved small non-coding RNAs that bind to the 3' untranslated region (UTR) of mRNA and regulate the expression of a variety of proteins at the post-transcriptional level. In recent years, attention has been focused on the role of miRNAs in various inflammatory diseases, including gouty arthritis. It is thought that miRNAs may regulate immune function and inflammatory responses, thereby influencing the onset and progression of the disease. This article mainly reviewed the roles of miRNAs in the pathogenesis of gouty arthritis and prospected their potential as diagnostic and prognostic relevant biomarkers and as possible therapeutic targets.

Xanthine oxidase inhibitor urate-lowering therapy titration to target decreases serum free fatty acids in gout and suppresses lipolysis by adipocytes

OBJECTIVE

Linked metabolic and cardiovascular comorbidities are prevalent in hyperuricemia and gout. For mechanistic insight into impact on inflammatory processes and cardiometabolic risk factors of xanthine oxidase inhibitor urate-lowering therapy (ULT) titration to target, we performed a prospective study of gout serum metabolomes from a ULT trial.

METHODS

Sera of gout patients meeting the 2015 ACR/EULAR gout classification criteria (n = 20) and with hyperuricemia were studied at time zero and weeks 12 and 24 of febuxostat or allopurinol dose titration ULT. Ultrahigh performance liquid chromatography-tandem mass spectroscopy acquired the serum spectra. Data were assessed using the Metabolon and Metaboloanalyst software. Lipolysis validation assays were done in febuxostat and/or colchicine-treated 3T3-L1 differentiated adipocytes.

RESULTS

Serum urate decreased from time zero (8.21 ±1.139 SD) at weeks 12 (5.965 ± 1.734 SD) and 24 (5.655 ±1.763 SD). Top metabolites generated by changes in nucleotide and certain amino acid metabolism and polyamine pathways were enriched at 12 and 24 weeks ULT, respectively. Decreases in multiple fatty acid metabolites were observed at 24 weeks, linked with obesity. In cultured adipocytes, febuxostat significantly decreased while colchicine increased the lipolytic response to β-adrenergic-agonism or TNF.

CONCLUSION

Metabolomic profiles linked xanthine oxidase inhibitor-based ULT titration to target with reduced serum free fatty acids. In vitro validation studies revealed that febuxostat, but not colchicine, reduced lipolysis in cultured adipocytes. Since soluble urate, xanthine oxidase inhibitor treatment, and free fatty acids modulate inflammation, our findings suggest that by suppressing lipolysis, ULT could regulate inflammation in gout and comorbid metabolic and cardiovascular disease.

FGF21 attenuates high uric acid‑induced endoplasmic reticulum stress, inflammation and vascular endothelial cell dysfunction by activating Sirt1

Uric acid (UA) is the final oxidation product of purine metabolism. Hyperuricemia has been previously reported to contribute to vascular endothelial dysfunction and the development of cardiovascular diseases, metabolic syndrome and chronic kidney diseases. In addition, it has been reported that fibroblast growth factor 21 (FGF21) can exert regulatory effects on UA‑induced lipid accumulation. Therefore, the present study aimed to investigate the possible role of FGF21 in HUVEC cell injury induced by UA. The study used UA to induce HUVEC cell injury, inhibited sirtuin 1 (Sirt1) expression using EX527 and overexpressed FGF21 by transfection. Subsequently, reverse transcription‑quantitative PCR was performed to measure the mRNA expression levels of FGF21, Sirt1 and inflammatory cytokines TNF‑α, IL‑1β and IL‑6, whereas western blotting was performed to measure their corresponding protein expression levels including FGF21, Sirt1, NLR family pyrin domain containing 3, pro‑caspase1, apoptosis‑associated speck‑like protein containing a CARD, activating transcription factor 4, C/EBP homologous protein and eukaryotic initiation factor 2. Furthermore, dichloro‑dihydro‑fluorescein diacetate staining was performed to measure intracellular reactive oxygen species (ROS) generation in HUVECs. The levels of ROS and nitric oxide were also quantified using commercial assay kits. The results demonstrated that overexpression of FGF21 significantly inhibited UA treatment‑induced endoplasmic reticulum (ER) stress, inflammation and oxidative stress in HUVECs. Furthermore, overexpression of FGF21 significantly activated Sirt1. The sirt1 inhibitor, EX527, significantly abrogated the suppressive effects of FGF21 overexpression on ER stress, inflammation and oxidative stress in UA‑stimulated HUVECs. To conclude, results of the present study suggested that FGF21 may attenuate UA‑induced ER stress, inflammation and vascular endothelial cell dysfunction by activating Sirt1. Therefore, FGF21 may be a potential effective target for the future treatment of vascular endothelial cell dysfunction.

Concerted regulation of non-alcoholic fatty liver disease progression by microRNAs in apolipoprotein E-deficient mice

The prevalence of non-alcoholic fatty liver disease (NAFLD) is constantly increasing, and altered expression of microRNAs (miRNAs) fosters the development and progression of many pathologies, including NAFLD. Therefore, we explored the role of new miRNAs involved in the molecular mechanisms that trigger NAFLD progression and evaluated them as biomarkers for diagnosis. As a NAFLD model, we used apolipoprotein E-deficient mice administered a high-fat diet for 8 or 18 weeks. We demonstrated that insulin resistance and decreased lipogenesis and autophagy observed after 18 weeks on the diet are related to a concerted regulation carried out by miR-26b-5p, miR-34a-5p, miR-149-5p and miR-375-3p. We also propose circulating let-7d-5p and miR-146b-5p as potential biomarkers of early stages of NAFLD. Finally, we confirmed that circulating miR-34a-5p and miR-375-3p are elevated in the late stages of NAFLD and that miR-27b-3p and miR-122-5p are increased with disease progression. Our results reveal a synergistic regulation of key processes in NAFLD development and progression by miRNAs. Further investigation is needed to unravel the roles of these miRNAs for developing new strategies for NAFLD treatment.

This article has an associated First Person interview with the joint first authors of the paper.

Summary:Apoe^−/− mice administered a high-fat diet represent a model of non-alcoholic fatty liver disease, revealing the synergistic regulation of key processes in disease progression by miRNAs and indicating some miRNAs as biomarkers for diagnosis.

An extensive and dynamic trans-omic network illustrating prominent regulatory mechanisms in response to insulin in the liver

An effective combination of multi-omic datasets can enhance our understanding of complex biological phenomena. To build a context-dependent network with multiple omic layers, i.e., a trans-omic network, we perform phosphoproteomics, transcriptomics, proteomics, and metabolomics of murine liver for 4 h after insulin administration and integrate the resulting time series. Structural characteristics and dynamic nature of the network are analyzed to elucidate the impact of insulin. Early and prominent changes in protein phosphorylation and persistent and asynchronous changes in mRNA and protein levels through non-transcriptional mechanisms indicate enhanced crosstalk between phosphorylation-mediated signaling and protein expression regulation. Metabolic response shows different temporal regulation with transient increases at early time points across categories and enhanced response in the amino acid and nucleotide categories at later time points as a result of process convergence. This extensive and dynamic view of the trans-omic network elucidates prominent regulatory mechanisms that drive insulin responses through intricate interlayer coordination.

Causal Associations of Urate With Cardiovascular Risk Factors: Two-Sample Mendelian Randomization

Background

Mendelian Randomization (MR) studies show conflicting causal associations of genetically predicted serum urate with cardiovascular risk factors (i.e., hypertension, diabetes, lipid profile, and kidney function). This study aimed to robustly investigate a causal relationship between urate and cardiovascular risk factors considering single nucleotide polymorphisms (SNPs) as instrumental variables using two-sample MR and various sensitivity analyses.

Methods

Data on SNP-urate associations were taken from the Global Urate Genetics Consortium and data on SNP-cardiovascular risk factor associations were taken from various consortia/UK Biobank. SNPs were selected by statistically and biologically driven approaches as instrumental variables. Various sensitivity analyses were performed using different MR methods including inverse variance weighted, MR-Egger, weighted median/mode, MR-PRESSO, and the contamination mixture method.

Results

The statistically driven approach showed significant causal effects of urate on HDL-C and triglycerides using four of the six MR methods, i.e., every 1 mg/dl increase in genetically predicted urate was associated with 0.047 to 0.103 SD decrease in HDL-C and 0.034 to 0.207 SD increase in triglycerides. The biologically driven approach to selection of SNPs from ABCG2, SLC2A9, SLC17A1, SLC22A11, and SLC22A12 showed consistent causal effects of urate on HDL-C from all methods with 0.038 to 0.057 SD decrease in HDL-C per 1 mg/dl increase of urate, and no evidence of horizontal pleiotropy was detected.

Conclusion

Our study suggests a significant and robust causal effect of genetically predicted urate on HDL-C. This finding may explain a small proportion (7%) of the association between increased urate and cardiovascular disease but points to urate being a novel cardiac risk factor.

Purine metabolites and complex diseases: role of genes and nutrients

PURPOSE OF REVIEW

Purines have several important physiological functions as part of nucleic acids and as intracellular and extracellular signaling molecules. Purine metabolites, particularly uric acid, have been implicated in congenital and complex diseases. However, their role in complex diseases is not clear and they have both beneficial and detrimental effects on disease pathogenesis. In addition, the relationship between purines and complex diseases is affected by genetic and nutritional factors. This review presents latest findings about the relationship between purines and complex diseases and the effect of genes and nutrients on this relationship.

RECENT FINDINGS

Evidence from recent studies show strong role of purines in complex diseases. Although they are causal in only few diseases, our knowledge about their role in other diseases is still evolving. Of all the purines, uric acid is the most studied. Uric acid acts as an antioxidant as well as a prooxidant under different conditions, thus, its role in disease also varies. Other purines, adenosine and inosine have been less studied, but they have neuroprotective properties which are valuable in neurodegenerative diseases.

SUMMARY

Purines are molecules with great potential in disease pathogenesis as either metabolic markers or therapeutic targets. More studies need to be conducted to understand their relevance for complex diseases.

Incidence and Risk Factors of Hyperuricemia among 2.5 Million Chinese Adults during the Years 2017-2018

Objective: To assess the incidence and risk factors of hyperuricemia among Chinese adults in 2017-2018. Methods: A total of 2,015,847 adults (mean age 41.2 ± 12.7, 53.1% men) with serum uric acid concentrations assayed on at least two separate days in routine health examinations during 2017-2018 were analyzed. Hyperuricemia was defined as fasting serum urate concentration >420 μmol/L in men and >360 μmol/L in women. The overall and sex-specific incidence rate were stratified according to age, urban population size, geographical region, annual average temperature and certain diseases. Logistic regression analyses were performed to explore risk factors associated with hyperuricemia. Results: 225,240 adults were newly diagnosed with hyperuricemia. The age- and sex-standardized incidence rate per 100 person-years was 11.1 (95%CI: 11.0-11.1) (15.2 for men and 6.80 for women). The risk of hyperuricemia was positively associated with younger age, being male, larger urban population size, higher annual temperature, higher body mass index, lower estimate glomerular filtration rate, hypertension, dyslipidemia and fat liver. Conclusions: The incidence of hyperuricemia was substantial and exhibited a rising trend among younger adults, especially among men. Socioeconomic and geographic variation in incidence were observed. The risk of hyperuricemia was associated with estimate glomerular filtration rate, fat liver and metabolic factors.

Determining the role for uric acid in non-alcoholic steatohepatitis development and the utility of urate metabolites in diagnosis: An opinion review

There has long been a recognised association between non-alcoholic fatty liver disease (NAFLD) and the composite aspects of the metabolic syndrome. Part of this association highlighted the supposed co-existence of elevated uric acid levels in those with NAFLD. There is interest in exploitation of this as a putative diagnostic and prognostic biomarker in NAFLD. Given the increased economic and health burden associated with the NAFLD epidemic, improved methods of population-based, minimally-invasive methods and biomarkers are clearly highly sought and necessary. In this opinion review we review the proposed role of uric acid in the pathogenesis of NAFLD and its potential utilisation in the diagnosis and monitoring of the disease process.

Effect of circulating exosomes derived from normal-weight and obese women on gluconeogenesis, glycogenesis, lipogenesis and secretion of FGF21 and fetuin A in HepG2 cells

BACKGROUND

It is generally accepted that obesity can lead to metabolic disorders such as NAFLD and insulin resistance. However, the underlying mechanism has been poorly understood. Moreover, there is evidence to support the possible role of exosomes in the metabolic homeostasis regulation. Accordingly, we aimed to determine the effect of plasma circulating exosomes derived from obese and normal-weight women on insulin signaling and the secretion of hepatokines in human liver cells.

METHODS

Plasma exosomes isolated from four obese (O-Exo) women and four normal-weight (N-Exo) female candidates were characterized for size, zeta potential, and CD63 protein expression and were used for stimulation of HepG2 cells. Then, cell viability, as well as levels of glycogen and triglyceride (TG), were evaluated. Levels of fetuin-A and FGF21 were measured using the ELISA kit. Expression of glucose 6-phosphatase (G6pase) and phosphoenolpyruvate carboxykinase (PEPCK) genes were determined using qRT-PCR. Western blot analysis was carried out to evaluating the phosphorylation of GSK3β.

RESULTS

The TG levels increased significantly in the cells treated with O-Exo than the control (vehicle) group (P = 0.005) and normal-weight group (P = 0.018). Levels of p-GSK3β and glycogen were significantly reduced by O-Exo in comparison with control (P = 0.002, P = 0.018, respectively). The mRNA expression of G6pase and PEPCK enzymes increased in the cells treated with O-Exo in comparison with the vehicle group (P = 0.017, P = 0.010, respectively). The levels of FGF21 in the supernatant of cells treated with O-Exo and N-Exo were significantly lower than the control group (P = 0.007).

CONCLUSION

It appears that obesity-related circulating exosomes can impair insulin signaling pathways and associated components, increase intracellular TG content, and decrease FGF21 secretion in the hepatocytes.