Increased Serum Uric Acid over five years is a Risk Factor for Developing Fatty Liver. Sci Rep. 2018;8:11735. [PMID: 30082907 PMCID: PMC6079004 DOI: 10.1038/s41598-018-30267-2]

Serum isthmin-1 is a potential biomarker for metabolic dysfunction associated fatty liver disease in patients with metabolic syndrome and type 2 diabetes mellitus

INTRODUCTION

Metabolic dysfunction associated fatty liver disease (MAFLD) is a prevalent condition in patients with type 2 diabetes mellitus (T2DM). Isthmin-1 (ISM1) is an adipokine that promotes glucose uptake and improves glucose tolerance and hepatic steatosis. Although ISM1 has been shown to be associated with T2DM, its role in patients with MAFLD and metabolic syndrome (MetS) remains insufficiently examined. This study aimed to investigate the relationship between serum ISM1 and MAFLD in patients with T2DM and the potential involvement of MetS in this association.

RESEARCH DESIGN AND METHODS

A total of 250 participants were divided into four groups: 60 patients with T2DM and MAFLD, 60 with newly diagnosed T2DM, 60 with MAFLD, and 70 healthy controls. Serum ISM1 levels were measured using ELISA. The distribution of ISM1 concentration in the combined data was divided into quartiles, and the Cochran-Armitage trend test was performed to estimate the significant trends across increasing quartiles.

RESULTS

Compared with the controls, patients with coexisting MAFLD, MetS, and T2DM exhibited significantly elevated serum ISM1 concentrations. Serum ISM1 levels in the overweight/obese group were also higher than those in the lean group. Serum ISM1 levels were positively correlated with body mass index (BMI), uric acid, alanine aminotransferase, aspartate aminotransferase, total cholesterol (TC), low-density lipoprotein cholesterol, fasting insulin, and homeostasis model assessment of insulin resistance and negatively associated with age and high-density lipoprotein cholesterol (HDL-C). BMI, TC, and HDL-C were independently associated with serum ISM1 concentration. The relative risks for MAFLD, T2DM, and T2DM with MAFLD increased significantly with higher ISM1 quartiles. Furthermore, a positive correlation was observed between serum ISM1 levels and the number of MetS components, with the elevated plasma levels of ISM1 escalating the risk of developing MetS to some extent.

CONCLUSIONS

The combination of ISM1 with TG and UA was identified as the best predictive factor for diagnosing MAFLD and MetS, potentially due to their contribution to aggravating the metabolic state.

Early onset of hyperuricemia is associated with the risk of nonalcoholic fatty liver disease across life course

BACKGROUND AND AIM

Hyperuricemia is associated with nonalcoholic fatty liver disease (NAFLD), whereas whether the association differed by hyperuricemia onset age remained unclear. This study sought to investigate the associations of hyperuricemia onset age with the risk of incident NAFLD across adulthood.

METHODS AND RESULTS

Based on Kailuan prospective cohort, our analysis comprised 3318 new-onset hyperuricemia cases from 2006 to 2015 and 3318 age- and sex-matched controls who were randomly selected from the general population. The risk of NAFLD across the onset age groups (<45, 45-54, 55-64, and ≥65 years) were compared using multivariable-adjusted Cox regression models. During a median follow-up of 6.78 years, 744 (22.42%) hyperuricemia participants and 586 (17.66%) normouricemia participants were diagnosed with incident NAFLD. After adjusted for potential confounders, the risk of NAFLD was gradually attenuated with each decade increase in hyperuricemia onset age. The adjusted hazard ratio (95% confidence interval) was 1.62 (1.33-1.97) for hyperuricemia onset age <45 years, 1.26 (1.01-1.57) for age of 45-54 years, 1.24 (1.00-1.59) for age of 55-64 years, and 1.19 (0.90-1.71) for age ≥65 years, respectively. The trend remained robust among the multiple sensitivity analyses.

CONCLUSIONS

The relative risk of incident NAFLD differed across hyperuricemia onset age-group, and the association was more evident in those with a younger age of hyperuricemia onset, highlighting the importance of performing early strategies on the prevention of NAFLD.

Uric acid plasma levels are associated with C-reactive protein concentrations and the extent of coronary artery lesions in patients with acute coronary syndromes

Many studies have pointed out that inflammation plays a pivotal role in pathophysiology of acute coronary syndromes (ACS) because several inflammatory molecules impair the endothelial functions in the coronary circulation and promote atherothrombotic events. Recently, many clinical/experimental evidences indicate that elevated plasma levels of uric acid (UA) might be considered a risk factor for developing ACS. It has been reported that elevated UA doses impair physiologic functions of endothelial cells, shifting them toward a pro atherothrombotic phenotype. In the present manuscript, we investigated the relationship between UA plasma levels, inflammatory burden, and extension of coronary atherosclerotic disease in patients with ACS. Patients with a clinical presentation of ACS (ST-elevated and non-ST-elevated myocardial infarction) admitted to the Vanvitelli Catheterization Laboratory at Monaldi Hospital in 2019, before the COVID-19 pandemia, were retrospectively analyzed. Biochemical profile, type of ACS presentation, as well as extension of coronary atherosclerosis were assessed. A total of 132 ACS patients were included in the analysis, and grouped into 3 tertiles according to the UA values (UA < 4.72 mg/dl, UA between 4.72 and 6.15 mg/dl, and UA > 6.15 mg/dl). Patients with UA plasma levels ≥ 6.15 mg/dL showed higher levels of C-reactive protein (mean of 5.1 mg/dL) as compared to patients with lower UA plasma levels. Moreover, the former group of patients showed higher levels of cardiac troponin and CPK, and presented more often with multivessel disease and complex coronary stenosis (type C of Ellis classification). Even though monocentric and with limited sample size, the present study shows that plasma levels of UA and hs-CRP are elevated in ACS patients and are associated with a more severe coronary disease, suggesting a potential role of UA in the pathophysiology of acute coronary events.

Uric acid and sCD163 as biomarkers for metabolic dysfunction and MAFLD in children and adolescents with overweight and obesity

OBJECTIVES

The prevalence of childhood obesity increases globally, and noninvasive methods are needed to identify metabolic dysfunction and obesity-related complications such as pediatric metabolic associated fatty liver disease (MAFLD). We investigated whether uric acid (UA) and the macrophage marker soluble form of cysteine scavenger receptor CD163 (sCD163) can be used as biomarkers for deteriorated metabolism or pediatric MAFLD in children with overweight or obesity.

METHODS

Cross-sectional clinical and biochemical data from 94 children with overweight or obesity was included. Surrogate liver markers were calculated, and correlations were investigated using Pearson's or Spearman's correlation test.

RESULTS

UA and sCD163 correlated with BMI standard deviation score (r=0.23, p<0.05; r=0.33, p<0.01) and body fat (r=0.24, p<0.05; r=0.27, p=0.01). UA correlated with triglycerides (ρ=0.21, p<0.05), fat free mass (r=0.33, p<0.01), and gamma-glutamyl transferase (r=0.39, p<0.01). sCD163 correlated with the pediatric NAFLD fibrosis score (r=0.28, p<0.01) and alanine aminotransferase (r=0.28, p<0.01). No correlation was found between UA and pediatric MAFLD.

CONCLUSIONS

UA and sCD163 was identified as markers of a deranged metabolic profile, thus acting as easily accessible biomarkers for obesity and an obesity-related deranged metabolism. Furthermore, increasing levels of sCD163 could be a useful biomarker of pediatric MAFLD. Future prospective studies are warranted.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

The risk of nonalcoholic fatty liver disease in gout patients with frequent flares: a retrospective cohort study

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is a common chronic disease that is related to high serum uric acid; however, the association between the frequency of gout flares and NAFLD risk remains unclear. This study aimed to investigate whether frequent gout flares were associated with incident NAFLD and analyze the interaction of frequency of gout flares and Adipo-IR on NAFLD in the gout Chinese population.

METHODS

A total of 350 cases of gout patients were enrolled in this retrospective cohort study. Cox proportional hazard regression analyses were performed to determine the association between frequent gout flares and NAFLD during follow-up and analyze the interaction of frequency of gout flares and Adipo-IR on NAFLD. Receiver operating curves (ROC) were plotted to explore the diagnostic value of frequent gout flares and Adipo-IR on the occurrence of NAFLD.

RESULTS

NAFLD developed in 78 participants (22.3%) during follow-up. Logistic regression showed that Adipo-IR was an independent factor associated with frequent gout flares risk. The multivariate Cox regression analysis revealed that frequent gout flares and Adipo-IR were associated with NAFLD risk (HR: 7.88, 95% CI: 2.11-29.48, p < 0.01; HR: 1.058, 95% CI: 1.01-1.2, p < 0.05). And ROC showed that both of them had a great discriminant ability to diagnose NAFLD.

CONCLUSIONS

Our data showed an independent association between the frequency of gout flares or Adipo-IR and incident NAFLD. Frequent gout flares and elevated Adipo-IR had a good predictive capability towards NAFLD development and played a synergistic role in the development of NAFLD.

KEY POINTS

• Frequent gout flares and elevated Adipo-IR had a good diagnostic capability towards NAFLD development. • Frequent gout flares and Adipo-IR played a synergistic role in the development of NAFLD.

Correlation between the Severity of Metabolic Dysfunction-Associated Fatty Liver Disease and Serum Uric Acid to Serum Creatinine Ratio

PURPOSE

As one of the most common chronic liver diseases, metabolic dysfunction-associated fatty liver disease (MAFLD) had different prognoses between mild and moderate-severe levels. Serum uric acid to serum creatinine ratio (sUA/Cr) can reflect the overall metabolic status of the body. To explore a convenient indicator to screen MAFLD and distinguish the severity of the disease, this study analyzed the correlation between sUA/Cr and the severity of MAFLD.

METHODS

228 participants were enrolled and divided into 2 groups, including mild MAFLD and non-MAFLD group and moderate-severe MAFLD group, based on liver/spleen computed tomography (CT) ratios. The correlations between sUA/Cr and the severity of MAFLD were analyzed by logistic and linear regression. Receiver operating characteristics (ROCs) analyzed the predictive ability of sUA/Cr for the severity of MAFLD expressed by the area under curve (AUC).

RESULTS

The level of sUA/Cr was higher in themoderate-severe MAFLD group than mild MAFLD and non-MAFLD group (6.14 ± 1.55 vs. 5.51 ± 1.19, P = 0.008). After adjustment for confounders, the correlation analysis showed that patients with elevated sUA/Cr had a higher risk of moderate-severe MAFLD (OR: 1.350, P = 0.036). A higher sUA/Cr level was associated with lower liver CT values (β = -0.133, P = 0.039) and liver/spleen CT ratio (β = -0.154, P = 0.016). sUA/Cr had the ability to discriminate the severity of MAFLD (AUC: 0.623).

CONCLUSION

sUA/Cr was positively associated with the risk of moderate-severe MAFLD and had the predictive ability to discriminate the moderate-severe MAFLD from mild MAFLD and non-MAFLD. The sUA/Cr level was suggested to be monitored and controlled in the screening and treatment of MAFLD.

Synergistic effect of serum uric acid and body mass index trajectories during middle to late childhood on elevation of liver enzymes in early adolescence: Findings from the Ewha Birth and Growth Study

BACKGROUND/OBJECTIVES

We aimed to determine whether serum uric acid (SUA) and body mass index (BMI) trajectories in childhood have longitudinal association with liver enzymes in adolescence.

METHODS

We conducted a study using data from the Ewha Birth and Growth Cohort. Individual trajectories of SUA (n = 203) and BMI (n = 206) from 5, 7, and 9 years were defined by group-based trajectory modeling. Also, liver function enzymes were collected at 11 to 12 year of age (Aspartate Aminotransferase [AST], Alanine transaminase [ALT], and Gamma-glutamyl transferase [γ-GTP]) (n = 206). Using a generalized linear model, the effects of SUA trajectory and BMI trajectory on liver function enzymes were assessed. We also assessed the interaction effect of SUA and BMI trajectories on liver enzymes.

RESULTS

For trajectory patterns, both SUA and BMI were classified into two distinct groups (High or Low). Both trajectory of SUA and BMI in childhood were positively associated with levels of liver enzymes at 11-12 years of age. The results showed that the combined effect of SUA and BMI trajectories on liver enzymes had a higher means in high-risk group (high SUA-high BMI trajectories group) than in low-risk group (low SUA-low BMI trajectories group) for ALT and γ-GTP, respectively. It remained significant association when adjusted for covariates. In addition, the interaction of BMI and SUA trajectories showed a significant synergistic effect.

CONCLUSION

Elevated childhood SUA and BMI trajectories are associated with increased liver enzymes in beginning of adolescent. This finding suggesting that early interventions in SUA and BMI may need for optimization of liver enzymes as potential marker for development of related disease in later life.

Uric Acid Induces a Proatherothrombotic Phenotype in Human Endothelial Cells by Imbalancing the Tissue Factor/Tissue Factor Pathway Inhibitor Pathway

BACKGROUND

 Several evidence show that elevated plasma levels of uric acid (UA) are associated with the increased risk of developing atherothrombotic cardiovascular events. Hyperuricemia is a risk factor for endothelial dysfunction (ED). ED is involved in the pathophysiology of atherothrombosis since dysfunctional cells lose their physiological, antithrombotic properties. We have investigated whether UA might promote ED by modulating the tissue factor (TF)/TF pathway inhibitor (TFPI) balance by finally changing the antithrombotic characteristics of endothelial cells.

METHODS

 Human umbilical vein endothelial cells were incubated with increasing doses of UA (up to 9 mg/dL). TF gene and protein expressions were evaluated by real-time polymerase chain reaction (PCR) and Western blot. Surface expression and procoagulant activity were assessed by FACS (fluorescence activated cell sorting) analysis and coagulation assay. The mRNA and protein levels of TFPI were measured by real-time PCR and Western blot. The roles of inflammasome and nuclear factor-κB (NF-κB) as possible mechanism(s) of action of the UA on TF/TFPI balance were also investigated.

RESULTS

 UA significantly increased TF gene and protein levels, surface expression, and procoagulant activity. In parallel, TFPI levels were significantly reduced. The NF-κB pathways appeared to be involved in modulating these phenomena. Additionally, inflammasome might also play a role.

CONCLUSION

 The present in vitro study shows that one of the mechanisms by which high levels of UA contribute to ED might be the imbalance between TF/TFPI levels in endothelial cells, shifting them to a nonphysiological, prothrombotic phenotype. These UA effects might hypothetically explain, at least in part, the relationship observed between elevated plasma levels of UA and cardiovascular events.

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.

Effect of Two Different Dietary Weight Loss Strategies on Risk Factors for Urinary Stone Formation and Cardiometabolic Risk Profile in Overweight Women

Overweight has been suggested to increase the risk of kidney stone formation. Although weight reduction might affect risk factors for urolithiasis, findings on the impact of different dietary weight loss strategies are limited. This randomized, controlled study evaluated the effect of a conventional energy-restricted modified diet with (MR group) or without meal replacement (C group) on risk factors for stone formation in overweight women without a history of urolithiasis. Of 105 participants, 78 were included into the per-protocol analysis. Anthropometric, clinical, biochemical, and 24 h urinary parameters were collected at baseline and after 12 weeks. Although both dietary interventions resulted in a significant weight reduction, relative weight loss and rate of responders were higher in the MR group. Weight loss improved cardiometabolic risk profile in both groups. Unfortunately, the benefit of decreased GPT activity in the C group was offset by a significant increase in homocysteine and a decline in GFR. While the relative supersaturation of calcium oxalate decreased significantly in both groups, a significant decline in serum uric acid concentration and relative supersaturation of uric acid was observed only in the MR group. Finally, the energy-restricted modified diet with meal replacement showed significant advantages over the energy-restricted modified diet alone.

Improving the accuracy of fatty liver index to reflect liver fat content with predictive regression modelling

Background

The fatty liver index (FLI) is frequently used as a non-invasive clinical marker for research, prognostic and diagnostic purposes. It is also used to stratify individuals with hepatic steatosis such as non-alcoholic fatty liver disease (NAFLD), and to detect the presence of type 2 diabetes or cardiovascular disease. The FLI is calculated using a combination of anthropometric and blood biochemical variables; however, it reportedly excludes 8.5-16.7% of individuals with NAFLD. Moreover, the FLI cannot quantitatively predict liver fat, which might otherwise render an improved diagnosis and assessment of fatty liver, particularly in longitudinal studies. We propose FLI+ using predictive regression modelling, an improved index reflecting liver fat content that integrates 12 routinely-measured variables, including the original FLI.

Methods and findings

We evaluated FLI+ on a dataset from the UK Biobank containing 28,796 individual estimates of proton density fat fraction derived from magnetic resonance imaging across normal to severe levels and interpolated to align with the original FLI range. The results obtained for FLI+ outperform the original FLI by delivering a lower mean absolute error by approximately 47%, a lower standard deviation by approximately 20%, and an increased adjusted R² statistic by approximately 49%, reflecting a more accurate representation of liver fat content.

Conclusions

Our proposed model predicting FLI+ has the potential to improve diagnosis and provide a more accurate stratification than FLI between absent, mild, moderate and severe levels of hepatic steatosis.

Weak Association Between Genetic Markers of Hyperuricemia and Cardiorenal Outcomes: Insights From the STANISLAS Study Cohort With a 20-Year Follow-Up

Background Hyperuricemia is associated with poor cardiovascular outcomes, although it is uncertain whether this relationship is causal in nature. This study aimed to: (1) assess the heritability of serum uric acid (SUA) levels, (2) conduct a genome-wide association study on SUA levels, and (3) investigate the association between certain single-nucleotide polymorphisms and target organ damage. Methods and Results The STANISLAS (Suivi Temporaire Annuel Non-Invasif de la Santé des Lorrains Assurés Sociaux) study cohort is a single-center longitudinal cohort recruited between 1993 and 1995 (visit 1), with a last visit (visit 4 [V4]) performed ≈20 years apart. Serum lipid profile, SUA, urinary albumin/creatinine ratio, estimated glomerular filtration rate, 24-hour ambulatory blood pressure monitoring, transthoracic echocardiography, pulse wave velocity, and genotyping for each participant were assessed at V4. A total of 1573 participants were included at V4, among whom 1417 had available SUA data at visit 1. Genome-wide association study results highlighted multiple single-nucleotide polymorphisms on the SLC2A9 gene linked to SUA levels. Carriers of the most associated mutated SLC2A9 allele (rs16890979) had significantly lower SUA levels. Although SUA level at V4 was highly associated with diabetes, prediabetes, higher body mass index, CRP (C-reactive protein) levels, estimated glomerular filtration rate variation (visit 1-V4), carotid intima-media thickness, and pulse wave velocity, rs16890979 was only associated with higher carotid intima-media thickness. Conclusions Our findings demonstrate that rs16890979, a genetic determinant of SUA levels located on the SLC2A9 gene, is associated with carotid intima-media thickness despite significant associations between SUA levels and several clinical outcomes, thereby lending support to the hypothesis of a link between SUA and cardiovascular disease.

A Population Based Study of Liver Function amongst Adults with Hyperuricemia and Gout in the United States

To examine the association between uric acid levels and liver enzyme functions amongst adults with hyperuricemia and gout in the United States. The National Health and Nutrition Examination Survey (NHANES) data from 2007 to 2016 was used to study the research objective. Data were analyzed for descriptive statistics and for differences using the t test, Chi-square test and ANOVA. A regression analysis was performed to determine association between demographics and liver enzymes. A p value of <0.05 or <0.001 was considered statistically significant. A total of 14,946 adults (≥20 yrs.) were included in this study. Sample mean age was 49 ± 0.15 yrs., and 54% were female. Overall, 15% adults had elevated uric acid levels (≥6.8 mg/dL), men had significantly higher uric acid levels than women (6 mg/dL vs. 4.8 mg/dL). High uric acid levels were associated with more than two times higher odds of elevated ALT, AST and GGT (p < 0.001). Similarly, gender-based target uric acid values were associated with two-fold increased odds of GGT, over one-and-a-half fold higher odds of ALT and AST (p < 0.001). Regression analysis showed significant association between age, gender, race/ethnicity, body mass index, and hypertension and ALT, AST, ALP, total bilirubin and GGT (p < 0.001). Adults with hyperuricemia and gout are most likely to develop liver dysfunctions and suffer associated morbidities. Such patients need to be appropriately monitored and managed for their liver functions and to prevent associated morbidities.

Negative interaction of fatty liver and hypertension on cardiovascular mortality in non-diabetic men: 34 years of follow-up

BACKGROUND AND OBJECTIVES

Fatty liver disease (FLD) and hypertension are separately associated with cardiovascular (CV) mortality. The two conditions are related in multiple ways. This work aimed to study the joint effect and interaction of FLD and hypertension in respect to overall and CV mortality.

METHODS

The population-based cohort, Kuopio Ischaemic Disease Risk Factor Study, followed 1569 middle-aged non-diabetic Finnish men for 34 years. Considering adjustment for age, body mass index, smoking and alcohol consumption, separate and combined effects of FLD and hypertension and their interaction at the multiplicative and additive scales regarding all-cause and CV death were assessed using Cox proportional hazards models.

RESULTS

FLD and hypertension coexisted in 8.54% of the men (n = 134). FLD and hypertension associated, independently and combined, with an increased hazard of all-cause and CV deaths. Non-CV mortality associated with FLD, but not with hypertension. We found a negative interaction between FLD and hypertension regarding the hazard of all-cause (relative excess risk due to interaction (RERI), -0.97; 95% confidence interval (CI), -1.65 to -0.28) and CV mortality (RERI, -1.74; 95% CI, -2.98 to -0.5). The interaction was also found on a multiplicative scale.

CONCLUSIONS

We found evidence of a negative interaction between FLD and hypertension in respect to CV mortality. We thus recommend adjusting for FLD or hypertension when studying the effect of the other condition on mortality or CV diseases in middle-aged men.

The Role of Uric Acid in the Acute Myocardial Infarction: A Narrative Review

Increased serum uric acid (SUA) levels have been associated with various pathologic processes such as increased oxidative stress, inflammation, and endothelial dysfunction. Thus, it is not surprising that increased SUA is associated with various adverse outcomes including cardiovascular (CV) diseases. Recent epidemiological evidence suggests that increased SUA may be related to acute myocardial infarction (AMI). Accumulating data also showed that elevated UA has pathophysiological role in the development of AMI. However, there are also studies showing that SUA is not related to the risk of AMI. In this narrative review, we summarized the recent literature data regarding SUA and AMI after providing some background information for the association between UA and coronary artery disease. Future studies will show whether decreasing SUA levels is beneficial for outcomes related to AMI and the optimum SUA levels for best outcomes in CV diseases.

Per- and Polyfluoroalkyl Substance Toxicity and Human Health Review: Current State of Knowledge and Strategies for Informing Future Research

Reports of environmental and human health impacts of per- and polyfluoroalkyl substances (PFAS) have greatly increased in the peer-reviewed literature. The goals of the present review are to assess the state of the science regarding toxicological effects of PFAS and to develop strategies for advancing knowledge on the health effects of this large family of chemicals. Currently, much of the toxicity data available for PFAS are for a handful of chemicals, primarily legacy PFAS such as perfluorooctanoic acid and perfluorooctane sulfonate. Epidemiological studies have revealed associations between exposure to specific PFAS and a variety of health effects, including altered immune and thyroid function, liver disease, lipid and insulin dysregulation, kidney disease, adverse reproductive and developmental outcomes, and cancer. Concordance with experimental animal data exists for many of these effects. However, information on modes of action and adverse outcome pathways must be expanded, and profound differences in PFAS toxicokinetic properties must be considered in understanding differences in responses between the sexes and among species and life stages. With many health effects noted for a relatively few example compounds and hundreds of other PFAS in commerce lacking toxicity data, more contemporary and high-throughput approaches such as read-across, molecular dynamics, and protein modeling are proposed to accelerate the development of toxicity information on emerging and legacy PFAS, individually and as mixtures. In addition, an appropriate degree of precaution, given what is already known from the PFAS examples noted, may be needed to protect human health. Environ Toxicol Chem 2021;40:606-630. © 2020 SETAC.

The role of uric acid in inflammasome-mediated kidney injury

PURPOSE OF REVIEW

Uric acid is produced after purine nucleotide degradation, upon xanthine oxidase catalytic action. In the evolutionary process, humans lost uricase, an enzyme that converts uric acid into allantoin, resulting in increased serum uric acid levels that may vary according to dietary ingestion, pathological conditions, and other factors. Despite the controversy over the inflammatory role of uric acid in its soluble form, crystals of uric acid are able to activate the NLRP3 inflammasome in different tissues. Uric acid, therefore, triggers hyperuricemic-related disease such as gout, metabolic syndrome, and kidney injuries. The present review provides an overview on the role of uric acid in the inflammasome-mediated kidney damage.

RECENT FINDINGS

Hyperuricemia is present in 20-35% of patients with chronic kidney disease. However, whether this increased circulating uric acid is a risk factor or just a biomarker of renal and cardiovascular injuries has become a topic of intense discussion. Despite these conflicting views, several studies support the idea that hyperuricemia is indeed a cause of progression of kidney disease, with a putative role for soluble uric acid in activating renal NLRP3 inflammasome, in reprograming renal and immune cell metabolism and, therefore, in promoting kidney inflammation/injury.

SUMMARY

Therapies aiming to decrease uric acid levels prevent renal NLRP3 inflammasome activation and exert renoprotective effects in experimental kidney diseases. However, further clinical studies are needed to investigate whether reduced circulating uric acid can also inhibit the inflammasome and be beneficial in human conditions.

Renal hyperfiltration, fatty liver index, and the hazards of all-cause and cardiovascular mortality in Finnish men

OBJECTIVES

Renal hyperfiltration (RHF) and fatty liver are separately associated with adverse health outcomes. In this study, we investigated the mortality hazard of coexisting RHF and fatty liver.

METHODS

Middle-aged men from the Kuopio Ischaemic Disease Risk Factor Study (n=1,552) were followed up for a median of 29 years. Associations among RHF, fatty liver index (FLI) score, age, body mass index, smoking status, alcohol consumption, and hypertension status were assessed using logistic regression. Cox proportional hazards models were used to determine the hazard ratios (HRs) for all-cause and cardiovascular disease (CVD) mortality with respect to RHF and fatty liver.

RESULTS

Of the men, 5% had RHF (n=73), whereas a majority had fatty liver (n=848). RHF was associated specifically with smoking, and fatty liver was associated specifically with overweight. The all-cause mortality hazard was highest (HR, 1.96; 95% confidence interval [CI], 1.27 to 3.01) among men with RHF and fatty liver (n=33). Among men with RHF but normal FLI (n=40), the HR of all-cause mortality was 1.67 (95% CI, 1.15 to 2.42). Among men with fatty liver but a normal estimated glomerular filtration rate (n=527), the HR of all-cause mortality was 1.35 (95% CI, 1.09 to 1.66). CVD mortality hazard was associated with RHF, but not fatty liver. We detected no interaction effect between RHF and fatty liver for all-cause (synergy index, 0.74; 95% CI, 0.21 to 2.67) or CVD (synergy index, 0.94; 95% CI, 0.34 to 2.60) mortality.

CONCLUSIONS

RHF and fatty liver are independently associated with all-cause and CVD mortality

Remodeling of whole-body lipid metabolism and a diabetic-like phenotype caused by loss of CDK1 and hepatocyte division

Cell cycle progression and lipid metabolism are well-coordinated processes required for proper cell proliferation. In liver diseases that arise from dysregulated lipid metabolism, hepatocyte proliferation is diminished. To study the outcome of CDK1 loss and blocked hepatocyte proliferation on lipid metabolism and the consequent impact on whole-body physiology, we performed lipidomics, metabolomics, and RNA-seq analyses on a mouse model. We observed reduced triacylglycerides in liver of young mice, caused by oxidative stress that activated FOXO1 to promote the expression of Pnpla2/ATGL. Additionally, we discovered that hepatocytes displayed malfunctioning β-oxidation, reflected by increased acylcarnitines (ACs) and reduced β-hydroxybutyrate. This led to elevated plasma free fatty acids (FFAs), which were transported to the adipose tissue for storage and triggered greater insulin secretion. Upon aging, chronic hyperinsulinemia resulted in insulin resistance and hepatic steatosis through activation of LXR. Here, we demonstrate that loss of hepatocyte proliferation is not only an outcome but also possibly a causative factor for liver pathology.

Impact of Uric Acid on Hypertension Occurrence and Target Organ Damage: Insights From the STANISLAS Cohort With a 20-Year Follow-up

BACKGROUND

Recent studies have shown that hyperuricemia may be associated with incident hypertension (HTN). We examined whether serum uric acid (SUA) is a predictor of HTN and target organ damage (TOD) 20 years later in initially healthy middle-aged individuals.

METHODS

Participants from the Suivi Temporaire Annuel Non-Invasif de la Santé des Lorrains Assurés Sociaux (STANISLAS) a single-center familial longitudinal cohort study (961 initially healthy adults and 570 children) underwent clinical and laboratory measurements at baseline and after approximately 20 years. Blood pressure (BP: using ambulatory BP measurements), urine albumin-to-creatinine ratio, estimated glomerular filtration rate (eGFR), left ventricular hypertrophy (LVH), diastolic dysfunction, and carotid-femoral pulse wave velocity (PWV) were measured at the end of follow-up.

RESULTS

In the parent population, higher baseline or last SUA levels and higher change in SUA (ΔUA) were significantly associated with an increased risk of HTN development, even after adjusting for known HTN risk factors (all P < 0.01). Higher baseline SUA was marginally associated with an increased risk of having high carotid-femoral PWV (P = 0.05). The association of SUA with BP increase was body mass index dependent (the increase in BP being greater in leaner subjects; interactionp < 0.05), and the association of SUA with eGFR decline was age dependent (the decline in eGFR being greater in older subjects; interactionp < 0.05). There was no significant association between SUA and diastolic dysfunction or LVH. In the whole population (i.e. including children), a significant association between SUA at baseline and the risk of HTN and higher carotid-femoral PWV was also found (both P < 0.02).

CONCLUSIONS

Increased SUA is associated with the development of HTN and vascular/renal TOD in initially healthy midlife subjects.

Extra-hepatic manifestations and complications of nonalcoholic fatty liver disease

This review article aims to synthesize the evidence regarding nonalcoholic fatty liver disease (NAFLD) as a systemic disorder. We critically discuss the metabolic syndrome and its components; the cardiovascular and the endocrine system; chronic respiratory disorders; the musculoskeletal system; the skin; and extra-hepatic tumors. We conclude that, while some of these extra-hepatic conditions clearly predispose to the development of secondary forms of NAFLD (typically hypothyroidism-induced NAFLD), others result from pre-existent NAFLD (e.g., certain extra-hepatic tumors) and others (such as Type 2 Diabetes) have, with NAFLD, mutual and bidirectional associations. Analyzed data imply that NAFLD is not merely a hepatic disease. It is also and possibly more importantly, a systemic disorder requiring a special awareness, a multidisciplinary approach and a multidimensional vision.

Uric acid and cardiometabolic diseases

Hyperuricemia, which has been considered as a cause of gout and nephrolithiasis has recently been suggested to be associated with hypertension, coronary heart disease, heart failure, atrial fibrillation, insulin resistance, and nonalcoholic fatty liver disease. Several clinical and experimental studies have supported uric acid (UA) as an independent risk factor for predicting disease development along with the traditional risk factors. The mechanism by which UA causes cardiometabolic disease has not been fully elucidated to date; however, it has been explained by several hypotheses such as oxidative stress, reduced nitric oxide bioavailability, inflammation, endothelial dysfunction, and so on. Although evidence of the preventive and therapeutic effects of UA lowering therapy on cardiometabolic diseases is still insufficient, it is expected to be considered as a new treatment strategy for such diseases through additional, carefully designed, large-scale clinical studies.

Therapeutic implications of shared mechanisms in non-alcoholic fatty liver disease and chronic kidney disease

The most common cause of liver disease worldwide is now non-alcoholic fatty liver disease (NAFLD). NAFLD refers to a spectrum of disease ranging from steatosis to non-alcoholic steatohepatitis, causing cirrhosis, and ultimately hepatocellular carcinoma. However, the impact of NAFLD is not limited to the liver. NAFLD has extra-hepatic consequences, most notably, cardiovascular and renal disease. NAFLD and chronic kidney disease share pathogenic mechanisms including insulin resistance, lipotoxicity, inflammation and oxidative stress. Not surprisingly, there has been a recent surge in efforts to manage NAFLD in an integrated way that not only protects the liver but also delays comorbidities such as chronic kidney disease. This concept of simultaneously addressing the main disease target and comorbidities is key to improve outcomes, as recently demonstrated by clinical trials of SGLT2 inhibitors and GLP1 receptor agonists in diabetes. HIF activators, already marketed in China, also have the potential to protect both liver and kidney, as suggested by preclinical data. This review concisely discusses efforts at identifying common pathogenic pathways between NAFLD and chronic kidney disease with an emphasis on potential paradigm shifts in diagnostic workup and therapeutic management.

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.

High uric acid, reduced glomerular filtration rate and non-alcoholic fatty liver in young people with obesity

OBJECTIVE

To evaluate the association between high uric acid (UA), reduced estimated glomerular filtration rate (eGFR), and non-alcoholic fatty liver disease (NAFLD) in outpatient children and adolescents with overweight (OW) or obesity (OB).

METHODS

Anthropometric, biochemical, hepatic ultrasound and eGFR data were available from 2565 young people with OW/OB (age 5-18 years). eGFR was calculated using the Schwartz's bedside formula and reduced eGFR (ReGFR⁺) was defined by a value < 90 mL/min/1.73 m². High UA was defined as ≥ 75th percentile by sex in children and adolescents.

RESULTS

The population was stratified in four categories: (1) normal eGFR and absence of NAFLD (ReGFR^-/NAFLD^-) (n = 1,236); (2) ReGFR⁺ and absence of NAFLD (ReGFR⁺/NAFLD^- (n = 155); (3) normal eGFR and presence of NAFLD (ReGFR^-/NAFLD⁺⁾ (n = 1019); (4) presence of both conditions (ReGFR⁺/NAFLD⁺) (n = 155). Proportions of youth with high UA across the four categories were 17%, 30%, 33% and 46%, respectively (P < 0.0001). Young people with high levels of UA had odds ratio (95% CI) of 2.11 (1.43-3.11) for ReGFR⁺; 2.82 (2.26-3.45) for NAFLD⁺; and 5.04 (3.45-7.39) for both conditions (P < 0.0001 for all), independently of major confounders.

CONCLUSIONS

High levels of UA were independently associated with ReGFR, NAFLD and the combination of both conditions in young people with OW/OB. The strength of this association was the highest in cases presenting both reduced eGFR and NAFLD. UA may serve as marker to identify patients at risk for these conditions.

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.

Increased plasma osteopontin levels are associated with nonalcoholic fatty liver disease in patients with type 2 diabetes mellitus

Nonalcoholic fatty liver disease (NAFLD) commonly occurs in patients with type 2 diabetes mellitus (T2DM). Osteopontin (OPN) is a multifunctional protein with pleiotropic physiological functions. This study aimed to investigate the interrelation between circulating OPN and NAFLD in T2DM patients. Overall, 249 subjects were classified into 4 groups: 53 patients with NAFLD and T2DM; 57 with newly diagnosed T2DM; 59 with NAFLD; and 80 healthy age- and sex-matched controls. Serum OPN was measured by ELISA. The OPN distribution in the pooled data was divided into quartiles; significant trends across increasing quartiles were estimated by the Cochran-Armitage trend test. Compared with the controls, circulating OPN concentrations were significantly elevated in NAFLD patients and T2DM patients with or without NAFLD. Serum OPN levels were higher in the overweight/obese group than that in the lean group. Circulating OPN levels were positively correlated with CRP, age, BMI, SBP, DBP, HbA1c, UA, TGs, WBCs, neutrophils, FBG, and HOMA-IR and negatively correlated with ADP, albumin and HDL. Age, albumin, HbA1c, HDL and hsCRP were independently related to circulating OPN. The relative risks for NAFLD, T2DM and T2DM with NAFLD increased significantly along with increasing OPN quartiles based on the Cochran-Armitage trend test. OPN is an optimal predictor in the diagnosis of T2DM with NAFLD and T2DM and may contribute to the aggravation of the metabolic state.

Uric acid activates aldose reductase and the polyol pathway for endogenous fructose and fat production causing development of fatty liver in rats

Dietary, fructose-containing sugars have been strongly associated with the development of nonalcoholic fatty liver disease (NAFLD). Recent studies suggest that fructose also can be produced via the polyol pathway in the liver, where it may induce hepatic fat accumulation. Moreover, fructose metabolism yields uric acid, which is highly associated with NAFLD. Here, using biochemical assays, reporter gene expression, and confocal fluorescence microscopy, we investigated whether uric acid regulates aldose reductase, a key enzyme in the polyol pathway. We evaluated whether soluble uric acid regulates aldose reductase expression both in cultured hepatocytes (HepG2 cells) and in the liver of hyperuricemic rats and whether this stimulation is associated with endogenous fructose production and fat accumulation. Uric acid dose-dependently stimulated aldose reductase expression in the HepG2 cells, and this stimulation was associated with endogenous fructose production and triglyceride accumulation. This stimulatory mechanism was mediated by uric acid-induced oxidative stress and stimulation of the transcription factor nuclear factor of activated T cells 5 (NFAT5). Uric acid also amplified the effects of elevated glucose levels to stimulate hepatocyte triglyceride accumulation. Hyperuricemic rats exhibited elevated hepatic aldose reductase expression, endogenous fructose accumulation, and fat buildup that was significantly reduced by co-administration of the xanthine oxidase inhibitor allopurinol. These results suggest that uric acid generated during fructose metabolism may act as a positive feedback mechanism that stimulates endogenous fructose production by stimulating aldose reductase in the polyol pathway. Our findings suggest an amplifying mechanism whereby soft drinks rich in glucose and fructose can induce NAFLD.

Joint associations of serum uric acid and ALT with NAFLD in elderly men and women: a Chinese cross-sectional study

Background

Epidemiological evidence suggests sex difference in serum uric acid (SUA) and alanine aminotransferase (ALT) might be a potential explanation for the gender difference in prevalence of non-alcoholic fatty liver disease (NAFLD). However, few epidemiology data in China have tested this hypothesis.

Methods

We conducted a cross-sectional study to assess the joint associations between SUA and serum ALT with NAFLD among elderly Chinese men and women.

Results

Among 7569 participants with a mean age of 59.8 years (± 13.4 years), 56.6% of women and 43.4% of men were diagnosed as NAFLD, respectively. A positive association between SUA and NAFLD prevalence was observed in both men and women. NAFLD prevalence was 2.74 times (95% CI 2.00–3.76) higher for men and 4.60 times (95% CI 3.39–6.24) higher for women with the highest quintiles of SUA levels compared to those with the lowest levels. SUA levels were significantly associated with prevalence of mild- and severe-steatosis (P < 0.01). In addition, the ORs of NAFLD among participants with high SUA levels and high serum ALT was 10.75 (95% CI 3.56–32.46) for men and 7.96 (95% CI 2.83–22.39) for women, compared with those with low SUA levels and low serum ALT.

Conclusions

SUA levels were positively associated with NAFLD prevalence, and the association was slightly stronger in women than in men. A significant joint association of SUA and serum ALT with NAFLD prevalence was observed in all participants, which was slightly stronger in men than in women.