Uric Acid - key ingredient in the recipe for cardiorenal metabolic syndrome

Elevated log uric acid-to-high-density lipoprotein cholesterol ratio (UHR) as a predictor of increased female infertility risk: insights from the NHANES 2013-2020

BACKGROUND

Infertility is a multifaceted condition influenced by metabolic and biochemical factors. Uric acid (UA) and high-density lipoprotein cholesterol (HDL-C) may individually affect reproductive health. The UA-to-HDL-C ratio (UHR), an emerging indicator of chronic inflammation and metabolic status, may be associated with infertility because of its connections to metabolic disorders, disrupted reproductive processes, and other related factors. Nevertheless, evidence of the relationship between the UHR and infertility remains limited and controversial. Therefore, potential associations were analyzed in this study.

METHODS

In this cross-sectional study, data from the 2013-2020 National Health and Nutrition Examination Survey (NHANES) were utilized, a nationally representative survey assessing the health and nutritional status of the U.S.

POPULATION

Female participants aged 18-45 years (n = 6502) whose infertility status was determined through self-reported responses to reproductive health questions were included. The primary outcome was infertility, defined on the basis of responses indicating difficulty in conceiving over the past year. Between-group differences were analyzed via Student's t test or the Mann‒Whitney U test for continuous variables or the chi-square test for categorical data. The independent association between infertility status and the log UHR was assessed by log computes logarithms by default natural logarithms. Subgroup analyses were performed to assess the strength of the results.

RESULTS

The mean log UHR of the women in the infertility group was significantly greater than that of the women in the noninfertility group (5.34 vs. 5.22, P < 0.001). Adjusted analyses revealed that an increase in the log UHR was associated with greater odds of infertility (odds ratio (OR) = 1.830, 95% confidence interval (CI) 1.396-2.401). Subgroup analysis revealed that women younger than 35 years with an elevated log UHR faced an even greater risk of infertility (OR = 2.716, 95% CI 1.784-4.162; P < 0.001).

CONCLUSIONS

An elevated UHR is associated with a higher risk of infertility, and this knowledge may be beneficial for developing a nonpharmacological intervention for improving fertility outcomes. Further research is needed to clarify the direct impact of the UHR on female infertility, which could inform future strategies for prevention and treatment.

Cross-sectional study on the association between serum uric acid levels and the risk of benign prostatic hyperplasia

OBJECTIVE

Serum uric acid (SUA), a non-protein antioxidant, exerts anti-inflammatory and antioxidative stress effects. This study aimed to investigate the association between SUA levels and the risk of benign prostatic hyperplasia (BPH).

METHODS

This cross-sectional study included 48 653 adult men who underwent health checkups at the Health Examination Center of the Affiliated Hospital of Yangzhou University in 2022. Data on demographics, clinical history and laboratory parameters were collected. Multivariable logistic regression models were used to analyse the relationship between SUA levels and BPH risk, with further exploration in different subgroups.

RESULTS

Logistic regression analysis revealed a significantly decreased risk of BPH among participants in the highest SUA quartile (Q4) compared with those in the lowest quartile (Q1) (fully adjusted OR=0.83, 95% CI: 0.78 to 0.90, p<0.0001). Subgroup analyses demonstrated that this inverse association was more pronounced in subgroups of age>60 years (Q4: OR=0.77, 95% CI: 0.68 to 0.87, p<0.0001), non-obesity (Q4: OR=0.81, 95% CI: 0.75 to 0.87, p<0.0001), without non-alcoholic fatty liver disease (NAFLD) (Q4: OR=0.81, 95% CI: 0.73 to 0.89, p<0.0001), hypertension (Q4: OR=0.81, 95% CI: 0.74 to 0.89, p<0.0001) and without diabetes (Q4: OR=0.84, 95% CI: 0.78 to 0.90, p<0.0001). Curve fitting revealed that higher SUA levels were associated with a lower risk of BPH even in the presence of increased BPH risk factors such as diabetes and hypertension.

CONCLUSIONS

This study demonstrates a significant inverse association between SUA levels and BPH risk, particularly in subgroups of older age, non-obesity, absence of NAFLD, hypertension and absence of diabetes. This suggests a potential protective role of SUA in BPH development, highlighting the potential value of maintaining SUA levels within a reasonable range for BPH prevention.

Isolation and Characterization of Highly Active Uricase from Alcaligenes spp. Strain UR1

For the first time, this study reports extracellular uricase enzyme isolation and characterization from strain UR1 of Alcaligenes spp. from Western Saudi Arabia. The strain efficiently produced highly active extracellular uricase for therapeutic applications. It offers a simplified enzyme purification approach rather than complicated intracellular enzyme purification from other microbes. Strain UR1 exhibited significantly higher uricase synthesis potential [916 U/mg (specific activities) and 275 U/ml (volume)]. The study optimized the conditions (37°C and pH 7.4) for 10% enhanced uricase production in the BT medium where sucrose served as the carbon source. Uricase enzyme remained stable at various pH levels (5-9) up to 50°C, however, the optimal activity was noted at 40°C and pH 7.5. The strain was sensitive to EDTA-like inhibitors. Ca2+ improved the strain activity, which could yield potent formulations for clinical and industrial applications. This novel aspect presents Alcaligenes spp. strain UR1 as a promising candidate for the treatment of hyperuricemia and gout. It offers an efficient and inexpensive alternative for uricase synthesis at the industrial scale. These findings encourage further investigations regarding genetic aspects of uricase for improved bioprocessing and therapeutic applications.

Two still unanswered questions about uric acid and cardiovascular prevention: Is a specific uric acid cut-off needed? Is hypouricemic treatment able to reduce cardiovascular risk?

AIMS

The most frequent consequence of elevated uric acid (UA) levels is the development of gout and urate kidney disease. Besides these effects, several studies have investigated the association between hyperuricemia and cardiovascular (CV) disease. High serum UA has been identified as an important determinant of all-cause and CV mortality and CV events (acute and chronic coronary syndrome, stroke and peripheral artery disease). Despite the high number of publications on this topic, there are two questions that are still unanswered: do we need a specific CV cut-off of serum UA to better refine the CV risk? Is urate lowering treatment (ULT) able to reduce CV risk in asymptomatic patients? In this review, we will focus on these two points.

DATA SYNTHESIS

Although no doubt exists that the relationship between CV events starts at lower levels than the actually used cut-off, different papers found dissimilar cut-offs. Furthermore, heterogeneity is present depending on the specific CV events evaluated and none of the found cut-off have been tested in external populations (in order to confirm its discriminatory capacity). Furthermore, only few randomized clinical trials on the role of hypouricemic agents in reducing the CV risk have been published giving heterogeneous results. The last published one (ALL-HEART) has strong limitations, that we will deeply discuss.

CONCLUSIONS

A definitive answer to the two questions is impossible with the actually published paper but, over identifying current gaps in knowledge we try to individuate how they can be overruled.

Clinical outcomes in patients with cardiorenal multimorbidity: the role of serum uric acid/serum creatinine ratio

INTRODUCTION

Serum uric acid (SUA), the final product of purine metabolism, is an independent risk factor for cardiovascular (CV) disease. Since SUA levels depend on renal function, SUA to serum creatinine ratio (SUA/sCr) is emerging as a more specific biomarker of CV risk.

AIM

To evaluate in hospitalized patients with cardiorenal multimorbidity (CRM) if the SUA/sCr ≥ 5.35 is associated with clinical outcomes. The primary outcome was in-hospital mortality. The secondary outcome was the composite of all-cause of mortality and adverse clinical events.

METHODS

We conducted a retrospective review of medical records from consecutive CRM inpatients admitted to the medical ward. The composite endpoint was calculated as all-cause mortality and adverse clinical events such as acute coronary syndrome, stroke, infections, and renal replacement therapy.

RESULTS

In our cohort, 141 patients (mean age of 75.6 ± 10.2 years) were identified with CRM. In-hospital mortality occurred in 17 patients (16%), and 64 patients (60.4%) experienced adverse clinical outcomes. Among the 106 patients, 20 (18.9%) had an SUA/sCr ≥ 5.35, while 86 (81.1%) had an SUA/sCr < 5.35. Male gender was significantly associated with SUA/sCr ≥ 5.35 (p = 0.007). In-hospital mortality was significantly higher in patients with SUA/sCr ≥ 5.35 (p = 0.010), and a positive correlation with adverse clinical outcomes was documented in this subgroup (p = 0.012).

CONCLUSION

in patients with CRM, SUA/sCr ≥ 5.35 is associated with increased in-hospital mortality and worse clinical outcomes. The ratio and related cut-off value of SUA/sCr could represent a useful biomarker to assess in-hospital complications in CRM patients.

Insights into renal damage in hyperuricemia: Focus on renal protection (Review)

The incidence of hyperuricemia has increased recently, posing a serious threat to public health. Hyperuricemia is associated with an increased risk of gout, chronic kidney disease (CKD), obesity, metabolic syndrome, type 2 diabetes mellitus, hypertension, hypertriglyceridaemia, metabolic dysfunction‑associated steatotic liver disease, acute kidney injury, coronary heart disease and cardiovascular disease (CVD). These diseases are commonly accompanied by varying degrees of kidney damage. A number of randomized controlled clinical trials have investigated the effectiveness of UA‑lowering therapies in preventing kidney disease progression. The present review provided fundamental insights into the pathogenesis, principles and therapeutic approaches for managing hyperuricemia in patients with aforementioned diseases and assesses the effect of uric acid‑lowering therapy on diabetic nephropathy, systemic lupus erythematosus, CKD, CVD and obesity progression.

Histochemical indications for a chemically complex signal produced by the cervical gill slit gland of the pygmy sperm whale (Kogia breviceps)

The pygmy sperm whale (Kogia breviceps) possesses an exocrine gland associated with its false gill slit pigmentation pattern. The cervical gill slit gland is a compound tubuloalveolar gland that produces a holocrine secretion and displays maturational changes in size and secretory histology. While the morphology of the cervical gill slit gland has been described in detail, to date, the chemical composition of its secretion remains uncharacterized. This study used histochemical staining techniques and quantitative lipid analysis to identify and characterize the constituents expressed in the secretory cells and secretion of the cervical gill slit gland. Results demonstrate that the secretion, like those of terrestrial artiodactyls that function in chemical communication, includes a complex mixture of carbohydrates, proteins, and lipids. Differences in staining intensity across germinal and secretory epithelial layers demonstrate differential expression, or maturation, of mucins and proteins. Additionally, a highly unusual and primary constituent of the secretion is uric acid. Uric acid was identified within the secretion using histochemical stains and polarized light imaging, and chemically verified using scanning electron microscopy with energy dispersive spectrometry. While uric acid is not a common constituent of mammalian exocrine glands, urate-based compounds are abundant in the secretions of marine organisms used in chemical communication. Thus, uric acid may contribute to the chemical message produced by K. breviceps in its marine environment. We hypothesize that the chemical signals produced by the gill slit gland may be shared at close-range by conspecifics, and that the mode of sensory reception is likely gustation.

U-shaped relationship between uric acid levels and all-cause mortality in patients with hypertension

A correlation between UA levels and the development of hypertension has been demonstrated. However, the relationship between UA and all-cause mortality in patients with hypertension remains underexplored. A nonlinear association between UA and all-cause mortality across sexes was observed through smoothed curve fitting. The correlation between UA and all-cause mortality was calculated by threshold and saturation effect analysis, along with Cox regression models. The stability of the results in the presence of different comorbidities was verified through stratified analysis for interaction testing. Smoothed curve fitting was also used to examine the association between UA and various diseases. The association between UA and all-cause mortality in patients with hypertension exhibited a U-shaped curve, with inconsistent inflection points between the sexes. In male patients with hypertension, all-cause mortality gradually decreased with increasing UA levels when UA levels were ≤ 7.2 mg/dL (HR  0.975; 95% CI 0.929-1.024) and gradually increased with increasing UA levels when UA levels were > 7.2 mg/dL (HR  1.204; 95% CI 1.120-1.294). Similar findings were observed in female patients with hypertension, with UA as a protective factor when UA levels were ≤ 5.1 mg/dL (HR 0.902; 95% CI 0.820-0.991) and a risk factor when UA levels were > 5.1 mg/dL (HR 1.120; 95% CI 1.072-1.169). The association between UA and all-cause mortality in patients with hypertension exhibits a U-shaped curve. All-cause mortality tends to decrease and then increase with increasing UA levels, with the inflection point varying between sexes.

Uric acid mediates kidney tubular inflammation through the LDHA/ROS/NLRP3 pathway

PURPOSE

Hyperuricemia (HUA) is an important factor leading to chronic kidney disease (CKD). The kidney tubular inflammatory response is activated in HUA. This study aimed to investigate whether lactate dehydrogenase A (LDHA) is involved in mediating uric acid-induced kidney tubular inflammatory response.

METHODS

In vivo, an HUA mouse model was established by continuous intraperitoneal injection of potassium oxonate (PO) for one week. A total of 18 C57BL/6J male adult mice were divided into three groups: control group, HUA group, and HUA+oxamate group, with six mice in each group. Oxamate was intraperitoneally injected into the mice one hour after PO injection. In vitro, an HUA model was simulated by stimulating HK-2 cells with uric acid. Oxamate and tempol inhibited LDHA and reactive oxygen species (ROS) in HK-2 cells.

RESULTS

In HUA mice, blood uric acid levels were significantly elevated. LDHA in kidney tubular cells was significantly increased in both in vivo and in vitro HUA models, accompanied by an increase in kidney tubular inflammation and ROS. Mechanistically, LDHA mediates uric acid-induced inflammation to kidney tubular cells through the ROS/NLRP3 pathway. Pharmacologic inhibition of LDHA or ROS in kidney tubular cells can significantly ameliorate inflammation response caused by uric acid.

CONCLUSIONS

LDHA in kidney tubular cells significantly was increased in HUA models. LDHA mediates kidney inflammation response induced by uric acid through the ROS/NLRP3 pathway. This study may provide a new intervention target for preventing kidney tubular inflammation caused by uric acid.

Serum uric acid and prediabetes progression and regression: a retrospective cohort study

BACKGROUND

The impact of serum uric acid (SUA) levels on metabolic disorders, particularly concerning the development or reversal of prediabetes, is not well understood. While high uric acid is recognized for its association with metabolic disturbances, its specific influence on prediabetes progression and regression has been insufficiently explored. This study investigates how SUA levels correlate with the natural course of prediabetes, shedding light on its management.

METHODS

A cohort of 3659 individuals diagnosed with prediabetes at Nanjing First Hospital was tracked over three years. Follow-up assessments included fasting plasma glucose and hemoglobin A1c (HbA1c) measurements. Serum uric acid was measured initially and categorized into quartiles (Q1 through Q4). To assess the impact of uric acid levels on shifting prediabetes status, methods such as restricted cubic spline, segmented regression, stratified analysis, and receiver operating characteristic curves were utilized in a multinomial logistic regression framework.

RESULTS

At baseline, all 3659 participants had prediabetes; by the three-year mark, 2626 remained in this category, 523 reverted to normal fasting glucose (NFG), and 510 advanced to diabetes. After adjustment for potential confounders, a positive correlation was found between higher SUA levels and progression to diabetes (Odds ratio [OR] 1.182, 95% confidence interval [CI]: 1.095-1.276), with no significant link to reversion to NFG (OR: 0.987, 95% CI: 0.909-1.073).

CONCLUSION

Elevated SUA levels are linked with a higher likelihood of progressing from prediabetes to diabetes but do not significantly forecast a regression to NFG.

Uric acid and metabolic syndrome: Importance of hyperuricemia cut-off

BACKGROUND

The relationship between HyperUricemia (HU) and Metabolic Sindrome (MS) and if Uric Acid (UA) should be inserted into MS definitions is a matter of debate. Aim of our study was to evaluate the correlation between UA and HU with Insulin Resistance (IR) and MS in a population of hypertensive patients. HU was defined with two cut-offs (the classic one of ≥6 mg/dL for women and ≥ 7 for men; the newly proposed URRAH one with ≥5.6 mg/dL for both sexes).

METHODS

We enrolled 473 Hypertensive patients followed by the Hypertension Unit of San Gerardo Hospital (Monza, Italy). IR was defined through TG/HDL ratio and NCEP-ATP-III criteria were used for MS diagnosis.

RESULTS

MS was found in 33.6 % while HU affected 14.8 % of subjects according to the traditional cut-off and 35.9 % with the URRAH cut-off. 9.7 % (traditional cut-off) and 17.3 % (URRAH's threshold) of the subjects had both HU and MS. UA level was significantly higher in MS group (5.7 vs 4.9 mg/dL, p < 0.0001) as well as for HU (29.0 vs 7.6 % and 51.6 vs 28.0 %, for classic and URRAH cut-off respectively, p < 0.0001 for both comparison). Logistic multivariable regression models showed that UA is related to MS diagnosis (OR = 1.608 for each 1 mg/dL), as well as HU with both cut-off (OR = 5.532 and OR = 3.379, p < 0.0001 for all comparison, for the classic cut-off and the URRAH one respectively).

CONCLUSIONS

The main finding of our study is that UA and HU significantly relate to IR and MS. The higher the values of UA and the higher the cut-off used, the higher the strength of the relationship.

Influence of Uric Acid on Vascular and Cognitive Functions: Evidence for an Ambivalent Relationship

The growing recognition of the public health impact of cognitive impairment and dementia has sparked a global initiative to identify risk factors and develop strategies to prevent or slow the progression of these cognitive disorders. Uric acid, the end product of the metabolism of purine nucleotides, has been reported as a key factor of many conditions potentially involved in cognitive dysfunction/dementia. In addition, some studies support the hypothesis that elevated uric acid levels could reduce the risk of Alzheimer's disease, slow down the decline of cognition, and delay the progression of Alzheimer's disease, while other evidence achieves opposite positions. These discrepancies might reflect a biological ambivalence for uric acid depending on a very complex interplay of factors that include its concentrations achieved in biological fluids, the nature, and concentration of free radicals, the presence and concentration of other antioxidant molecules, potentially responsible for bi-directional effects of uric acid on brain health/functioning. In this narrative review, we attempt to elucidate the influential role of uric acid metabolism in cognitive functioning by discussing pathophysiological mechanisms putatively involved, being well aware that none of them can be considered one-sided due to the complexity of the human organism.

Role of HIF1A gene polymorphisms with serum uric acid and HIF-1α levels in monosodium urate crystal-induced arthritis

BACKGROUND

Gouty arthritis is a metabolic disease characterized by the deposition of monosodium urate crystals in the joints, which triggers the release of interleukin-1β (IL-β) by activating the NLRP3 inflammasome. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor involved in IL-β production and as a regulator of NLRP3.

OBJECTIVES

The aims were to analyze the association of HIF1A rs11549465, rs11549467, and rs2057482 variants in patients with gouty arthritis, and to evaluate the correlation between urate and HIF-1α levels according to the associated genotypes.

METHODS

Cases and controls were genotyped using TaqMan probes, and urate and HIF-1α levels were quantified. Data were analyzed using SPSS v21 software and P-values < 0.05 were considered statistically significant.

RESULTS

Urate and HIF-1α levels were higher in patients than in controls (P < 0.05). Under the three inheritance models (codominant, dominant, and recessive), the AA genotype of the rs11549467 variant was associated with gout risk (OR = 5.74, P = 0.009, OR = 3.33, P = 0.024, and OR = 9.09, P = 0.003, respectively). There were significant differences in the distribution of serum levels of both HIF-1α (P < 0.0001) and urate (P = 0.016) according to the genotypes of the rs11549467 variant.

CONCLUSION

These results suggest that the HIF1A rs11549467 variant may play a key role in the pathogenesis of gouty arthritis. Key Points • The pathogenesis of gouty arthritis involves the HIF1A gene. • In patients with gout, the AA genotype of the rs11549467 (HIF1A) variant is associated with increased serum levels of urate and HIF-1α. • HIF-1α is involved in the regulation of IL-1β and NLRP3.

Many foods are more acid-forming than acid-alkaline formulas indicate

Foods contain substances impacting the acid-base balance. The Western diet is often viewed as being overly acid due to its high-level of animal-based protein and low-level of vegetable intake. Meanwhile, with ageing the ability to excrete acid compounds is reduced as kidney function declines and so there is a risk of acid retention and subsequent interstitial acidosis. Two systems used for calculating the Dietary Acid Load (DAL): the potential acid load of foods (PRAL) and the net endogenous acid production (NEAP). This report outlines weaknesses in these formulas and concludes that dietitians and nutritionists lack the necessary tools to research the acid-base hypothesis. Additionally, the report emphasizes the importance of food selection in the ageing population. Background: Foods contain substances impacting the acid-base balance. The Western diet is often viewed as being overly acid due to its high-level of animal-based protein and low-level of vegetable intake. There are concerns that the disproportionate acid intake promotes low-grade metabolic acidosis in the interstitial fluid, interstitial acidosis, and may lead to chronic disease. Two formulas are used for calculating the DAL: the PRAL and the NEAP. Both PRAL and NEAP are based on levels of protein and minerals. Aim: To identify additional food constituents that impact DAL. Methods: Review of the literature concerning the acid-forming and alkaline-forming constituents of foods. Results: Five additional food constituents were identified as potentially having a meaningful impact on DAL. The oxidation of taurine and the metabolism of fructose and purines increase acidity, whereas organic acids increase alkalinity. Additionally, polyphenols affect the microbiota which break down uric acid excreted in the intestinal tract. Conclusions: Neither PRAL nor NEAP provides complete assessments of the impact of foods on DAL. These formulas could be improved by the inclusion of dietary amino acids rather than protein, taurine, purines, fructose, organic acids and polyphenols. Currently, dietitians and nutritionists lack the necessary tools both to research the acid-base hypothesis and recommend managed diets. Managed diets are of particular importance for the elderly because of their reduced kidney function which increases the risk of acid retention and subsequent interstitial acidosis.

WWC1 upregulation accelerates hyperuricemia by reduction in renal uric acid excretion through Hippo signaling pathway

Hyperuricemia (HUA) is a metabolic disorder characterized by elevated serum uric acid (UA), primarily attributed to the hepatic overproduction and renal underexcretion of UA. Despite the elucidation of molecular pathways associated with this underexcretion, the etiology of HUA remains largely unknown. In our study, using by Uox knockout rats, HUA mouse, and cell line models, we discovered that the increased WWC1 levels were associated with decreased renal UA excretion. Additionally, using knockdown and overexpression approaches, we found that WWC1 inhibited UA excretion in renal tubular epithelial cells. Mechanistically, WWC1 activated the Hippo pathway, leading to phosphorylation and subsequent degradation of the downstream transcription factor YAP1, thereby impairing the ABCG2 and OAT3 expression through transcriptional regulation. Consequently, this reduction led to a decrease in UA excretion in renal tubular epithelial cells. In conclusion, our study has elucidated the role of upregulated WWC1 in renal tubular epithelial cells inhibiting the excretion of UA in the kidneys and causing HUA.

Plasma aldosterone concentrations elevation in hypertensive patients: the dual impact on hyperuricemia and gout

Background

Prior research has highlighted the association between uric acid (UA) and the activation of the renin-angiotensin-aldosterone system (RAAS). However, the specific relationship between aldosterone, the RAAS's end product, and UA-related diseases remains poorly understood. This study aims to clarify the impact of aldosterone on the development and progression of hyperuricemia and gout in hypertensive patients.

Methods

Our study involved 34534 hypertensive participants, assessing plasma aldosterone concentration (PAC)'s role in UA-related diseases, mainly hyperuricemia and gout. We applied multiple logistic regression to investigate the impact of PAC and used restricted cubic splines (RCS) for examining the dose-response relationship between PAC and these diseases. To gain deeper insights, we conducted threshold analyses, further clarifying the nature of this relationship. Finally, we undertook subgroup analyses to evaluate PAC's effects across diverse conditions and among different subgroups.

Results

Multivariate logistic regression analysis revealed a significant correlation between the occurrence of hyperuricemia and gout and the elevation of PAC levels. Compared to the first quartile (Q1) group, groups Q2, Q3, and Q4 all exhibited a significantly increased risk of occurrence. Moreover, the conducted RCS analysis demonstrated a significant nonlinear dose-response relationship, especially when PAC was greater than 14 ng/dL, with a further increased risk of hyperuricemia and gout. Finally, comprehensive subgroup analyses consistently reinforced these findings.

Conclusion

This study demonstrates a close association between elevated PAC levels and the development of UA-related diseases, namely hyperuricemia and gout, in hypertensive patients. Further prospective studies are warranted to confirm and validate this relationship.

The Role of Endothelial Cell Mitophagy in Age-Related Cardiovascular Diseases

Aging is a major risk factor for cardiovascular diseases (CVD), and mitochondrial autophagy impairment is considered a significant physiological change associated with aging. Endothelial cells play a crucial role in maintaining vascular homeostasis and function, participating in various physiological processes such as regulating vascular tone, coagulation, angiogenesis, and inflammatory responses. As aging progresses, mitochondrial autophagy impairment in endothelial cells worsens, leading to the development of numerous cardiovascular diseases. Therefore, regulating mitochondrial autophagy in endothelial cells is vital for preventing and treating age-related cardiovascular diseases. However, there is currently a lack of systematic reviews in this area. To address this gap, we have written this review to provide new research and therapeutic strategies for managing aging and age-related cardiovascular diseases.

High-performance liquid chromatography (HPLC) as a means of assessing the presence of uric acid in archeological human remains: Challenges and future directions

OBJECTIVES

This research aimed to replicate the Swinson, D., Snaith, J., Buckberry, J., & Brickley, M. (2010). High performance liquid chromatography (HPLC) in the investigation of gout in paleopathology. International Journal of Osteoarchaeology, 20, 135-143. https://doi.org/10.1002/oa.1009 method for detecting uric acid in archeological human remains to investigate gout in past populations and to improve the original High Performance Liquid Chromatography-ultraviolet (HPLC-UV) method by using HPLC-mass spectrometry (HPLC-MS), a more sensitive, compound-specific detection method.

MATERIALS AND METHODS

We used reference samples of uric acid to create a dilution series to assess the limits of quantification and detection. Samples from individuals with and without gout lesions were taken from foot bones and ribs from the English cemeteries of Tanyard, Hickleton, Gloucester, and Lincoln.

RESULTS

We could not replicate the results of Swinson and colleagues using HPLC-UV. Tests using a dilution series of uric acid showed HPLC-MS was approximately 100× more sensitive than HPLC-UV, with the additional benefit of being compound specific. A newly developed hydrophilic interaction chromatography (HILIC) method improved retention characteristics. Fourteen samples from eight individuals, five with skeletal lesions consistent with gout, were analyzed with the final method. None showed evidence of uric acid despite the newly developed method's improved sensitivity and specificity.

DISCUSSION

The lack of detectable uric acid extracted from these samples suggests that (1) urate crystals were not present in any of the bone samples, regardless of gout status; (2) urate crystals did not survive these specific archeological conditions; or (3) the concentration of uric acid in our bone extracts was low, and thus larger samples would be required.

The synergism of Lactobacillaceae, inulin, polyglucose, and aerobic exercise ameliorates hyperglycemia by modulating the gut microbiota community and the metabolic profiles in db/db mice

This study aimed to assess the impact of Lactobacillaceae (L or H represents a low or high dose), inulin (I), and polydextrose (P) combined with aerobic exercise (A) on the composition of the gut microbiota and metabolic profiles in db/db mice. After a 12-week intervention, LIP, LIPA, and HIPA groups exhibited significant improvements in hyperglycemia, glucose tolerance, insulin resistance, inflammatory response, and short-chain fatty acid (SCFA) and blood lipid levels compared to type 2 diabetes mice (MC). After treatment, the gut microbiota composition shifted favorably in the treatment groups which significantly increased the abundance of beneficial bacteria, such as Bacteroides, Blautia, Akkermansia, and Faecalibaculum, and significantly decreased the abundance of Proteus. Metabolomics analysis showed that compared to the MC group, the contents of 5-hydroxyindoleacetic acid, 3-hydroxysebacic acid, adenosine monophosphate (AMP), xanthine and hypoxanthine were significantly decreased, while 3-ketosphinganine, sphinganine, and sphingosine were significantly increased in the LIP and LIPA groups, respectively. Additionally, LIP and LIPA not only improved sphingolipid metabolism and purine metabolism pathways but also activated AMP-activated protein kinase to promote β-oxidation by increasing the levels of SCFAs. Faecalibaculum, Blautia, Bacteroides, and Akkermansia exhibited positive correlations with sphingosine, 3-ketosphinganine, and sphinganine, and exhibited negative correlations with hypoxanthine, xanthine and AMP. Faecalibaculum, Blautia, Bacteroides, and Akkermansia may have the potential to improve sphingolipid metabolism and purine metabolism pathways. These findings suggest that the synergism of Lactobacillaceae, inulin, polydextrose, and aerobic exercise provides a promising strategy for the prevention and management of type 2 diabetes.

New Dawn for Atherosclerosis: Vascular Endothelial Cell Senescence and Death

Endothelial cells (ECs) form the inner linings of blood vessels, and are directly exposed to endogenous hazard signals and metabolites in the circulatory system. The senescence and death of ECs are not only adverse outcomes, but also causal contributors to endothelial dysfunction, an early risk marker of atherosclerosis. The pathophysiological process of EC senescence involves both structural and functional changes and has been linked to various factors, including oxidative stress, dysregulated cell cycle, hyperuricemia, vascular inflammation, and aberrant metabolite sensing and signaling. Multiple forms of EC death have been documented in atherosclerosis, including autophagic cell death, apoptosis, pyroptosis, NETosis, necroptosis, and ferroptosis. Despite this, the molecular mechanisms underlying EC senescence or death in atherogenesis are not fully understood. To provide a comprehensive update on the subject, this review examines the historic and latest findings on the molecular mechanisms and functional alterations associated with EC senescence and death in different stages of atherosclerosis.

Significance of Kidney Disease in Cardiovascular Disease Patients

Cardiorenal syndrome is a condition where is a bidirectional and mutually detrimental relationship between the heart and kidneys. The mechanisms underlying cardiorenal syndrome are multifactorial and complex. Patients with kidney disease exhibit increased cardiovascular risk, presenting as coronary and peripheral artery disease, structural heart disease, arrhythmias, heart failure, and sudden cardiac death, largely occurring because of a systemic proinflammatory state, causing myocardial and vascular remodeling, manifesting as atherosclerotic lesions, vascular and valvular calcification, and myocardial fibrosis, particularly among those with advanced disease. This review summarizes the current understanding and clinical implications of kidney disease in patients with cardiovascular disease.

Effect of Intestinal Flora on Hyperuricemia-Induced Chronic Kidney Injury in Type 2 Diabetic Patients and the Therapeutic Mechanism of New Anti-Diabetic Prescription Medications

This article examined the current research on hyperuricemia (HUA) exacerbating diabetic kidney damage and novel anti-diabetic medications for treating these people. Hyperuricemia and type 2 diabetes (T2D), both of which are frequent metabolic disorders, are closely connected. Recent studies have shown that hyperuricemia can increase kidney injury in T2D patients by aggravating insulin resistance, by activating the renin-angiotensin-aldosterone system (RAAS), and by stimulating inflammatory factors, and the diversity, distribution, and metabolites of intestinal flora. Considering this, there are just a few of the research examining the effect of hyperuricemia on diabetic kidney injury via intestinal flora. Through the gut-kidney axis, intestinal flora primarily influences renal function. The primary mechanism is that variations in diversity, distribution, and metabolites of intestinal flora led to alterations in metabolites (such as short-chain fatty acids, Indoxyl sulfate and p-cresol sulfate, Trimethylamine N-oxide TMAO). This article reviewed the research and investigates the association between hyperuricemia and T2D, as well as the influence of hyperuricemia on diabetic kidney injury via intestinal flora. In addition, the current novel antidiabetic drugs are discussed, and their characteristics and mechanisms of action are reviewed. These novel antidiabetic drugs include SGLT2 inhibitors, GLP-1 receptor agonists, DDP-4 inhibitors, glucokinase (GK) enzyme activators (GK agonists), and mineralocorticoid receptor antagonists (MRA). Recent studies suggest that these new anti-diabetic medications may have a therapeutic effect on hyperuricemia-induced kidney impairment in diabetes patients via various mechanisms. Some of these medications may reduce blood uric acid levels, while others may improve kidney function by attenuating the overstimulation of RAAS or by decreasing insulin resistance and inflammation in the kidneys. These novel antidiabetic medicines may have a multifaceted approach to treating hyperuricemia-induced kidney impairment in diabetic patients; nevertheless, additional study is required to establish their efficacy and comprehend their specific mechanisms.

Correlation between serum uric acid and body fat distribution in patients with MAFLD

BACKGROUND

Metabolic dysfunction associated with fatty liver disease (MAFLD) is often correlated with obesity and hyperuricemia. The present study aimed to determine the association between serum uric acid (SUA) and central fat distribution in patients with MAFLD.

METHODS

A total of 485 patients were classified into the following groups: (1) controls without MAFLD and hyperuricemia (HUA), (2) MAFLD with normal SUA, and (3) MAFLD with HUA. DUALSCAN HDS-2000 was used to measure visceral fat (VAT) and subcutaneous fat (SAT). Dual-energy X-ray absorptiometry (DEXA) was used to measure body fat distribution.

RESULTS

MAFLD patients with HUA had remarkably higher BMI, fasting insulin, OGIRT AUC, ALT, AST, TG, VAT, SAT, Adipo-IR, trunk fat mass, android fat, and total body fat than MAFLD patients with normal SUA (all p < 0.05). The increase in VAT, SAT, CAP, Adipo-IR, upper limbs fat mass, trunk fat mass, and android fat, as well as the percentage of MAFLD, were significantly correlated with the increase in SUA. The percentage of MAFLD patients with HUA increased significantly with increasing VAT or SAT, as determined by the Cochran-Armitage trend test (all p < 0.05). Furthermore, VAT (OR = 1.01 CI: 1.00, 1.03; p < 0.05) and adipo-IR (OR = 1.09 CI: 1.00, 1.19; p < 0.05) were associated with circling SUA in MAFLD after adjusting for sex, age, TG, TC, HOMA-IR, and BMI.

CONCLUSION

Abdominal fat promotes the co-existence of HUA and MAFLD, while weight loss, especially, decreasing VAT, is of great importance to decrease SUA levels and manage MAFLD.

Clinicopathological characteristics and associated factors of idiopathic membranous nephropathy with hyperuricemia: a single-centered cross-sectional study

PURPOSE

This study was designed to investigate the clinicopathological features of idiopathic membranous nephropathy (IMN) with hyperuricemia (HUA), together with associated factors within 10 years in a single centre in Shandong Province.

METHODS

In this cross-sectional study, we analysed the clinical and pathological data of 694 IMN patients in our hospital from January 2010 to December 2019. Based on serum uric acid (UA) level, the patients were divided into hyperuricemia (HUA) group (n = 213) and normal serum uric acid (NUA) group (n = 481). Multi-variate logistic regression analysis was conducted on to screen the associated factors of HUA.

RESULTS

213 (30.69%) IMN patient were complicated with HUA. Compared with the patients with NUA, significant increase was noticed in the proportion of patients showing edema, concurrent hypertensive disease or diabetes mellitus (DM), as well as the proportion of positive glomerular capillary loop IgM and positive C1q in the HUA group (P < 0.05). In addition, significant increase was noticed in the 24 h urine protein, serum creatinine, triglycerides, complement C3 and complement C4 in HUA group compared with those of NUA group (all P < 0.05). With gender as a control factor, multi-variate logistic regression analysis showed positive glomerular capillary loops C1q, serum albumin, serum phosphorus were associated with IMN combined with HUA in male, while triglycerides and serum creatinine were associated with IMN combined with HUA in female counterparts.

CONCLUSION

About 30.69% of IMN patients had HUA, with a male predominance than female. In male patients with IMN, higher serum albumin level and serum phosphorus level were associated with higher incidence of HUA, while in female IMN patients, higher serum triglyceridemia and serum creatinine level were associated with higher incidence of HUA. Therefore, it can be targeted to prevent the occurrence of HUA in IMN.

The effects of boron on some biochemical parameters: A review

BACKGROUND

Boron; It is used mainly in glass and ceramics, in the defense industry, in jet and rocket fuel, as a disinfectant, and even in the agricultural sector to increase or prevent vegetation development. Its use in the health field has become more widespread when studies in recent years are reviewed. Although it has been reported that boron has essential biological effects on minerals, some enzymes, and hormones, the mechanism of these biological effects has yet to be fully elucidated. This review aims to bring a new perspective to researchers by combining the results of experimental studies in the literature on the effects of boron on some biochemical parameters.

METHODS

Works of literature on boron were brought together using more than one database (WOS, PubMed, Scopus, Google Scholar). The animal, boron type and dose used in the experimental study, and biochemical parameters (glucose, urea, BUN (blood urea nitrogen), uric acid, creatinine, creatine kinase, blood lipid profile, minerals, liver function tests) were systematically compiled.

RESULTS

It was observed that the studies mainly focused on glucose and lipid profiles and had a lowering effect on these parameters. From a mineral point of view, the studies are mostly related to the bone matrix.

CONCLUSION

Although the mechanism of action of boron on biochemical parameters has not yet been clarified, it would be beneficial to examine its relationship with hormones in more depth. A good understanding and analysis of the effect of boron, which is widely used, on biochemical parameters will be beneficial in taking necessary precautions for human and environmental health.

Detecting uric acid base on the dual inner filter effect using BSA@Au nanoclusters as both peroxidase mimics and fluorescent reporters

Fluorescent bovine serum albumin-protected gold nanoclusters (BSA@Au NCs) can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue oxTMB for its peroxidase-like activity. The two absorption peaks of oxTMB overlapped with the excitation and emission peaks of BSA@Au NCs, respectively, causing efficient quenching on the fluorescence of BSA@Au NCs. The quenching mechanism can be attributed to the dual inner filter effect (IFE). Based on the dual IFE, BSA@Au NCs were utilized as both peroxidase mimics and fluorescent reporters for H₂O₂ detection and further for uric acid detection with uricase. Under optimal detection conditions, the method can be used to detect H₂O₂ ranging 0.50-50 μM with a detection limit of 0.44 μM and UA ranging 0.50-50 μM with a detection limit of 0.39 μM. The established method had been successfully utilized for the determination of UA in human urine, with massive potential in biomedical applications.

Intracellular Antioxidant and Anti-Inflammatory Effects and Bioactive Profiles of Coffee Cascara and Black Tea Kombucha Beverages

Kombucha is a functional beverage obtained through fermentation of sweetened Camellia sinensis infusion by a symbiotic culture of bacteria and yeasts that exerts many beneficial biological effects, mostly related to its antioxidant and anti-inflammatory effects. Alternative raw materials have been used to create new kombucha or kombucha-like products. Coffee is the most important food commodity worldwide and generates large amounts of by-products during harvest and post-harvest processing. The main coffee by-product is the dried fruit skin and pulp, popularly known as cascara. To date, no studies have evaluated the potential bioactivity of coffee cascara kombucha. In this study, we aimed to measure and compare the effects of infusions and kombuchas made with arabica coffee cascaras (n = 2) and black tea leaves (n = 1), fermented for 0, 3, 6, and 9 days on the intracellular production of Reactive Oxygen Species (ROS) and Nitric Oxide (NO) in model cells. Oxidative stress was induced in HK-2 cells with indoxyl sulfate (IS) and high glucose (G). Inflammation was induced with lipopolysaccharide (LPS) in RAW 264.7 macrophage. The contents of phenolic compounds, caffeine, and other physicochemical parameters were evaluated. To the best of our knowledge, this is the first study providing information on the bioactive profile and on the potential biological effects of coffee cascara kombucha. Fermentation caused the release of bound phenolic compounds from the infusions, especially total chlorogenic acids, with an average increase from 5.4 to 10.7 mg/100 mL (98%) and 2.6-3.4 mg/100 mL (30%) in coffee cascara and black tea kombucha, respectively, up to day 9. All evaluated beverages reduced (p < 0.0001) similarly the intracellular ROS (41% reduction, on average) and uric acid (10-55%) concentrations in HK-2 model cells, reversing the induced oxidative stress. All beverages also reduced (p < 0.0001, 81-90%) NO formation in LPS-induced macrophages, exhibiting an anti-inflammatory effect. These potential health benefits may be mostly attributed to polyphenols and caffeine, whose contents were comparable in all beverages. Coffee cascara showed similar potential to C. sinensis to produce healthy beverages and support sustainable coffee production.

Occupational stress is associated with insulin resistance and incident type 2 diabetes: a prospective cohort study of functional community

BACKGROUND

To exploit the association of occupational stress with the development of insulin resistance (IR) and type 2 diabetes (T2D) in a Chinese population-based cohort.

METHODS

A total of 6109 participants from a functional community cohort in Beijing were enrolled in 2015 and followed up until 2021. Copenhagen Psychosocial Questionnaire (COPSOQ) were used to evaluate occupational stress.

RESULTS

At baseline, increase values of all five scales of COPSOQ and total COPSOQ were significantly associated with IR. During an average 5.63 y follow-up, 732 individuals developed T2D. Increasing in values of "Demands at work", "Insecurity at work", "Job satisfaction" and total COPSOQ were significantly associated with incident T2D (P<0.01). Mediation analysis showed that subjectively perceived occupational stress promoted T2D mainly by affecting plasma cortisol and the mediation effects of HOMA-IR, SBP, DBP, TG, Urea and UA were significant on the association between cortisol and incident T2D, with proportion mediated of 37.1%, 8.12%, 2.02%, 2.94%, 2.35% and 2.70%.

CONCLUSION

Occupational stress was independently associated with the development of IR and T2D. IR, BP, TG, Urea and UA all partly mediated the association between occupational stress and incident T2D.

Purine Metabolism Dysfunctions: Experimental Methods of Detection and Diagnostic Potential

Purines, such as adenine and guanine, perform several important functions in the cell. They are found in nucleic acids; are structural components of some coenzymes, including NADH and coenzyme A; and have a crucial role in the modulation of energy metabolism and signal transduction. Moreover, purines have been shown to play an important role in the physiology of platelets, muscles, and neurotransmission. All cells require a balanced number of purines for growth, proliferation, and survival. Under physiological conditions, enzymes involved in purines metabolism maintain a balanced ratio between their synthesis and degradation in the cell. In humans, the final product of purine catabolism is uric acid, while most other mammals possess the enzyme uricase that converts uric acid to allantoin, which can be easily eliminated with urine. During the last decades, hyperuricemia has been associated with a number of human extra-articular diseases (in particular, the cardiovascular ones) and their clinical severity. In this review, we go through the methods of investigation of purine metabolism dysfunctions, looking at the functionality of xanthine oxidoreductase and the formation of catabolites in urine and saliva. Finally, we discuss how these molecules can be used as markers of oxidative stress.

Hypertension and cellular senescence

Essential or primary hypertension is a wordwide health problem. Elevated blood pressure (BP) is closely associated not only with increased chronological aging but also with biological aging. There are various common pathways that play a role in cellular aging and BP regulation. These include but not limited to inflammation, oxidative stress, mitochondrial dysfunction, air pollution, decreased klotho activity increased renin angiotensin system activation, gut dysbiosis etc. It has already been shown that some anti-hypertensive drugs have anti-senescent actions and some senolytic drugs have BP lowering effects. In this review, we have summarized the common mechanisms underlying cellular senescence and HT and their relationships. We further reviewed the effect of various antihypertensive medications on cellular senescence and suggest further issues to be studied.

Vegan Diet Is Associated with a Lower Risk of Chronic Kidney Disease in Patients with Hyperuricemia

Hyperuricemia is a well-known risk factor for chronic kidney disease (CKD). Little is known about whether a vegetarian diet is associated with a lower risk of CKD in patients with hyperuricemia. From 5 September 2005, to 31 December 2016, we retrospectively included clinically stable patients with hyperuricemia who received health check-ups at Taipei Tzu Chi Hospital. All participants completed a dietary habits questionnaire to determine whether they were omnivorous, lacto-ovo vegetarian, or vegan. CKD was defined as an estimated glomerular filtration rate <60 mL/min/1.73 m2 or the presence of proteinuria. A total of 3618 patients with hyperuricemia were recruited for this cross-sectional study, consisting of 225 vegans, 509 lacto-ovo vegetarians, and 2884 omnivores. After adjusting for age and sex, vegans had a significantly lower odds ratio (OR) of CKD than omnivores (OR, 0.62; p = 0.006). The OR of CKD remained significantly lower in vegans after adjusting for additional confounders (OR, 0.69; p = 0.04). Additionally, age (per year OR, 1.06; p < 0.001), diabetes mellitus (OR, 2.12; p < 0.001), hypertension (OR, 1.73; p < 0.001), obesity (OR, 1.24; p = 0.02), smoking (OR, 2.05; p < 0.001), and very high uric acid levels (OR, 2.08; p < 0.001) were independent risk factors for CKD in patients with hyperuricemia. Moreover, structural equation modeling revealed that a vegan diet was associated with a lower OR of CKD (OR, 0.69; p < 0.05). A vegan diet is associated with a 31% lower risk of CKD in patients with hyperuricemia. A vegan diet may be beneficial in reducing the occurrence of CKD in patients with hyperuricemia.

Elevated serum uric acid level is associated with adverse reproductive outcomes in women with polycystic ovary syndrome undergoing in vitro fertilization or intracytoplasmic sperm injection embryo transfer cycles: a retrospective cohort study

BACKGROUND

Serum uric acid levels are elevated in polycystic ovary syndrome, however, the relationship between serum uric acid level and reproductive outcomes in women with polycystic ovary syndrome remains unclear.

OBJECTIVE

This study aimed to investigate the association between serum uric acid level and the reproductive outcomes in women with polycystic ovary syndrome undergoing in vitro fertilization or intracytoplasmic sperm injection embryo transfer cycles.

STUDY DESIGN

This was a retrospective cohort study performed at a university-affiliated reproductive medicine center. A total of 1903 women with polycystic ovary syndrome undergoing their first in vitro fertilization or intracytoplasmic sperm injection embryo transfer cycles between January 2010 and January 2021 were initially included. The trends for reproductive outcomes in polycystic ovary syndrome across quartiles of serum uric acid levels were assessed. A logistic regression analysis was performed to obtain the odds ratios for in vitro fertilization outcomes based on the quartiles of serum uric acid with or without adjusting for potential confounding variables. Using generalized additive models, serum uric acid was further treated as its original continuous property to visualize its nonlinear relationship with in vitro fertilization outcomes. The live birth rate was the main outcome.

RESULTS

After exclusions, a total of 883 women with polycystic ovary syndrome with their first fresh-embryo transfer cycles were included. In quartiles of serum uric acid levels, there was a significant decreasing trend in the live birth rate from the lowest quartile (Q1: 61.8%) to the highest (Q4: 45.9%) (P_trend=.002). The percentage of low birthweight increased from Q1 (22.3%) to Q4 (31.7%) (P_trend=.049). Compared with those in Q1, women in Q4 showed a significant lower probability of live birth and clinical pregnancy and a higher risk for low birthweight (all P<.05). Both the unadjusted and adjusted generalized additive models indicated that as the serum uric acid level increased, the probability of clinical pregnancy and the live birth rate exhibited an overall decreasing profile, and the risk for low birthweight showed an increasing profile.

CONCLUSION

An elevated serum uric acid level is associated with decreased probabilities of live birth and clinical pregnancy and an increased risk for low birthweight in women with polycystic ovary syndrome. However, these associations may be confounded by other factors and more well-designed studies are needed to confirm these findings in the future.

TGF-β is elevated in hyperuricemic individuals and mediates urate-induced hyperinflammatory phenotype in human mononuclear cells

BACKGROUND

Soluble urate leads to a pro-inflammatory phenotype in human monocytes characterized by increased production of IL-1β and downregulation of IL-1 receptor antagonist, the mechanism of which remains to be fully elucidated. Previous transcriptomic data identified differential expression of genes in the transforming growth factor (TGF)-β pathway in monocytes exposed to urate in vitro. In this study, we explore the role of TGF-β in urate-induced hyperinflammation in peripheral blood mononuclear cells (PBMCs).

METHODS

TGF-β mRNA in unstimulated PBMCs and protein levels in plasma were measured in individuals with normouricemia, hyperuricemia and gout. For in vitro validation, PBMCs of healthy volunteers were isolated and treated with a dose ranging concentration of urate for assessment of mRNA and pSMAD2. Urate and TGF-β priming experiments were performed with three inhibitors of TGF-β signalling: SB-505124, 5Z-7-oxozeaenol and a blocking antibody against TGF-β receptor II.

RESULTS

TGF-β mRNA levels were elevated in gout patients compared to healthy controls. TGF-β-LAP levels in serum were significantly higher in individuals with hyperuricemia compared to controls. In both cases, TGF-β correlated positively to serum urate levels. In vitro, urate exposure of PBMCs did not directly induce TGF-β but did enhance SMAD2 phosphorylation. The urate-induced pro-inflammatory phenotype of monocytes was partly reversed by blocking TGF-β.

CONCLUSIONS

TGF-β is elevated in individuals with hyperuricemia and correlated to serum urate concentrations. In addition, the urate-induced pro-inflammatory phenotype in human monocytes is mediated by TGF-β signalling. Future studies are warranted to explore the intracellular pathways involved and to assess the clinical significance of urate-TGF-β relation.

Uric acid promotes myocardial infarction injury via activating pyrin domain-containing 3 inflammasome and reactive oxygen species/transient receptor potential melastatin 2/Ca2+pathway

Cardiomyocytes injury has been considered as a key contributor for myocardial infarction (MI). Uric acid (UA) can induce cardiomyocytes injury, which is closely related to NLRP3 activation and inflammatory factor generation. However, the mechanism how UA modulates cardiomyocytes remains elusive. Western blotting and qRT-PCR were applied for measuring protein and mRNA expression, respectively. ROS production and Ca²⁺ influx were measured by flow cytometry. Patch clamp technique was used for measuring transient receptor potential melastatin 2 (TRPM2) channel. Ligation of left anterior descending for 2 h was performed to induce MI animal model. The rats were treated by different concentration of uric acid. The artery tissues were stained by HE and collected for measurement of NLRP3 and inflammatory factors. Supplementation of UA significantly promoted apoptosis, and augmented the expression of intercellular adhesion molecule-1, chemoattractant protein-1, vascular cell adhesion molecule-1, and NLRP3 inflammasome. Knockdown of NLRP3 reversed the influence of UA on MI by decreasing collagen deposition, fibrotic area, apoptosis. The expression of NLRP3 inflammasome increased markedly after treatment of UA. UA activated ROS/TRPM2/Ca²⁺ pathway through targeting NLRP3. UA activated NLRP3 inflammasome and augments inflammatory factor production, which in turn exacerbates cardiomyocytes injury. Knockdown of NLRP3 reversed the influence of UA on apoptosis and cell cycle. UA may promote cardiomyocytes injury through activating NLRP3 inflammasome and ROS/TRPM2 channel/Ca²⁺ pathway.

Risk factors and management of hyperuricemia after renal transplantation

Hyperuricemia (HUA) is a common complication after renal transplantation. Currently, there is no uniform consensus on factors which increase the risk for and treatment of HUA in renal transplant recipients. The purpose of this review is to summarize current and proposed risk factors and strategies to manage HUA after renal transplantation in order to assist renal function protection and prolong graft survival time.

Associations of waist-to-height ratio with the incidence of type 2 diabetes and mediation analysis: Two independent cohort studies

AIM

To assess the relationship between waist-to-height ratio (WHtR) and the incidence of type 2 diabetes (T2D)/impaired fasting glucose (IFG) and to explore to what extent these associations are mediated by blood pressure, lipids and other indicators related to liver and kidney metabolism.

MATERIALS AND METHODS

This study was based on a functional community cohort included 6109 participants which were divided into two sub-cohorts. One sub-cohort included participants with normal fasting glucose (n = 5563), another included IFG individuals at baseline (n = 546). Cox regression models were used to evaluate the relationships of WHtR with T2D/IFG. Four-year time-dependent receiver operating characteristic (ROC) curve and area under curve (AUC) were calculated to estimate the discriminatory power of WhtR and other anthropometric indices on T2D. Mediation analysis was performed to estimate which risk factors mediate the association between WHtR and T2D.

RESULTS

Significant positive associations were found between WHtR and the incidence of T2D/IFG in both sub-cohort. WhtR was a useful predictor of T2D (P < 0.05). Mediation analysis showed that HOMA-IR (0.45 %), SBP (5.10 %), triglycerides (11.02 %), creatinine (9.36 %) and combined kidney indicators (17.48 %) partly mediated the effect of WHtR on T2D in men. For women, this association was partly mediated by SBP (13.86 %), HDL (24.54 %), ALT (6.29 %), UA (22.58 %) and combined kidney indicators (39.51 %).

CONCLUSIONS

WHtR was an independent risk factor for the development of T2D and IFG. This association was partly mediated by HOMA-IR, SBP, lipids and other liver and kidney metabolism indicators.

The Good, the Bad and the New about Uric Acid in Cancer

Simple Summary

The concentration of uric acid in blood is sex-, age- and diet-dependent and is maintained close to its maximal solubility, indicating that it plays some important role. Indeed, it has been demonstrated that, at physiological concentrations, uric acid is a powerful antioxidant and is a scavenger of singlet oxygen and radicals. At high intracellular concentration, uric acid has been demonstrated to act as a pro-oxidant molecule. Recently, uric acid has been reported to affect the properties of several proteins involved in metabolic regulation and signaling, and the relationship between uric acid and cancer has been extensively investigated. In this review, we present the most recent results on the positive and negative effects played by uric acid in cancer and some new findings and hypotheses about the implication of this metabolite in the pathogenesis of several diseases such as metabolic syndrome, diabetes, and inflammation, thus favoring the development of cancer.

Abstract

Uric acid is the final product of purine catabolism in man and apes. The serum concentration of uric acid is sex-, age- and diet-dependent and is maintained close to its maximal solubility, indicating that it plays some important role. Indeed, it has been demonstrated that, at physiological concentrations, uric acid is a powerful antioxidant, while at high intracellular concentrations, it is a pro-oxidant molecule. In this review, we describe the possible causes of uric acid accumulation or depletion and some of the metabolic and regulatory pathways it may impact. Particular attention has been given to fructose, which, because of the complex correlation between carbohydrate and nucleotide metabolism, causes uric acid accumulation. We also present recent results on the positive and negative effects played by uric acid in cancer and some new findings and hypotheses about the implication of this metabolite in a variety of signaling pathways, which can play a role in the pathogenesis of diseases such as metabolic syndrome, diabetes, and inflammation, thus favoring the development of cancer. The loss of uricase in Homo sapiens and great apes, although exposing these species to the potentially adverse effects of uric acid, appears to be associated with evolutionary advantages.

Hyperuricemia, a Non-Independent Component of Metabolic Syndrome, Only Predicts Renal Outcome in Chronic Kidney Disease Patients without Metabolic Syndrome or Diabetes

Uric acid (UA) is elevated in metabolic syndrome (MS) and diabetes (DM). UA is associated with central obesity and blood glucose and is proposed as a criterion of MS. Previous reports showed that UA could predict renal outcome in CKD. However, recent clinical trials did not demonstrate the benefits of urate-lowering agents (ULA) for renal outcome. Whether the prognostic value of UA for renal outcome is independent of MS or secondary to MS in CKD patients is unknown. Our study included 2500 CKD stage 1−4 Asian patients divided by UA tertiles and MS/DM. In linear regression, UA was associated with obesity, C-reactive protein, and renal function. In Cox regression, high UA was associated with worse renal outcome in non-MS/DM, but not in MS/DM: hazard ratio (95% confidence interval) of UA tertile 3 was 3.86 (1.87−7.97) in non-MS/DM and 1.00 (0.77−1.30) in MS/DM (p for interaction < 0.05). MS was associated with worse renal outcome, but redefined MS (including hyperuricemia as the 6th criteria) was not. In conclusion, hyperuricemia is associated with worse renal outcome in non-MS/DM and is not an independent component of MS in CKD stage 1−4 patients. Hyperuricemia secondary to MS could not predict renal outcome.

The Influence of Serum Uric Acid on the Brain and Cognitive Dysfunction

Uric acid is commonly known for its bad reputation. However, it has been shown that uric acid may be actively involved in neurotoxicity and/or neuroprotection. These effects could be caused by oxidative stress or inflammatory processes localized in the central nervous system, but also by other somatic diseases or systemic conditions. Our interest was to summarize and link the current data on the possible role of uric acid in cognitive functioning. We also focused on the two putative molecular mechanisms related to the pathological effects of uric acid-oxidative stress and inflammatory processes. The hippocampus is a prominent anatomic localization included in expressing uric acid's potential impact on cognitive functioning. In neurodegenerative and mental disorders, uric acid could be involved in a variety of ways in etiopathogenesis and clinical presentation. Hyperuricemia is non-specifically observed more frequently in the general population and after various somatic illnesses. There is increasing evidence to support the hypothesis that hyperuricemia may be beneficial for cognitive functioning because of its antioxidant effects but may also be a potential risk factor for cognitive dysfunction, in part because of increased inflammatory activity. In this context, gender specificities must also be considered.

Hypouricemia and Urate Transporters

Hypouricemia is recognized as a rare disorder, defined as a serum uric acid level of 2.0 mg/dL or less. Hypouricemia is divided into an overexcretion type and an underproduction type. The former typical disease is xanthinuria, and the latter is renal hypouricemia (RHUC). The frequency of nephrogenic hypouricemia due to a deficiency of URAT1 is high in Japan, accounting for most asymptomatic and persistent cases of hypouricemia. RHUC results in a high risk of exercise-induced acute kidney injury and urolithiasis. It is vital to promote research on RHUC, as this will lead not only to the elucidation of its pathophysiology but also to the development of new treatments for gout and hyperuricemia.

Cardiorenal syndrome: long road between kidney and heart

Almost 200 years ago, the first evidence described by Robert Bright (1836) showed the strong interaction between the kidneys and heart and, since then, the scientific community has dedicated itself to better understanding the mechanisms involved in the kidney-heart relationship, known in recent decades as cardiorenal syndrome (CRS). This syndrome includes a wide clinical variety that affects the kidneys and heart, in an acute or chronic manner. Moreover, it is well established in the literature that the immune system, the sympathetic nervous system, the renin-angiotensin-aldosterone, and the oxidative stress actively play a strong role in the cellular and molecular processes present in CRS. More recently, uremic molecules and epigenetic factors have been also shown to be key mediators in the development of syndrome. The present review intends to present the state of the art regarding CRS and to show the paths known, until now, in the long road between the kidneys and heart.

Increased Impact of Serum Uric Acid on Arterial Stiffness and Atherosclerosis in Females

AIMS

Serum uric acid increases with metabolic disorders; however, whether the effects of uric acid on atherosclerosis are different in females and males has not been sufficiently evaluated. Therefore, this study compared the impact of uric acid on arterial stiffness and atherosclerosis between females and males.

METHODS

We enrolled 10196 untreated middle-aged subjects (46±8 years, 3021 females and 7175 males) who underwent periodic health check-ups. Serum uric acid levels were measured and arterial stiffness and atherosclerosis were assessed by the cardio-ankle vascular index (CAVI), carotid intima-media thickness (IMT), and plaque, using ultrasound imaging.

RESULTS

Females with increased arterial stiffness (CAVI ≥ 8.0) or carotid plaques had higher uric acid than those without (P＜0.0001), but males did not. In multivariable regression analyses including overall participants, uric acid was significantly associated with the CAVI, where sex interacted with uric acid. In sex-specific analyses, uric acid was significantly associated with the CAVI, but not with carotid IMT, in both sexes. However, logistic regression analyses revealed that serum uric acid was independently associated with the presence of carotid plaques in females. The exclusion of subjects with abdominal obesity or metabolic syndrome from the analysis did not alter the results in females.

CONCLUSIONS

Serum uric acid was significantly associated with the CAVI in both sexes, but the interaction of sex was confirmed and associated with a carotid plaque only in females. These findings support the increased impact of serum uric acid on arterial stiffness and atherosclerosis in females.

A novel uric acid biosensor based on regular Prussian blue nanocrystal/ upright graphene oxide array nanocomposites

Objective:

Regular Prussian blue nanocrystals (RPB) were grown upright on graphene oxide flakes (GO), which were on the surface of a custom screen-printed carbon electrode (SPCE), using a spray method assisted by a constant magnetic field (CMF).

Method:

After immobilizing uricase, the uric acid biosensor Uricase/RPB/CMF-GO/SPCE was obtained. The detection range of the sensor response to UA was 0.005~2.525 mM, and the detection limit was as low as 3.6 μM. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that compared to amorphous electrodeposited Prussian blue (EDPB), RPB more favorably accelerated electron transport.

Result:

This novel uric acid biosensor exhibits high sensitivity over, a wide concentration range, strong anti- interference ability, and good stability and reproducibility.

Conclusion:

Thus, it has good application prospects for determining uric acid in physiological samples

In vivo effects of aflatoxin B1 and benzo[a]pyrene on the heart muscle of chicken embryos

The purpose of the present study was to evaluate the effects of aflatoxin B1 (AFB1) and benzo[a]pyrene (BaP) on the heart muscle of chicken embryos of the broiler line Ross 308. The benzo[a]pyrene in the organic oil solution was injected in ovo on the 6th day of the incubation in doses of: 0.1, 0.5, and 1 mg/kg weight of eggs; the aflatoxin B1 in the organic oil solution was injected in ovo on the 6th day of the incubation into the yolk in doses of 80, 120 and 240 ng/kg weight of eggs. Multiple biochemical and hepatic parameters have been observed, including sodium, potassium, chloride, cholesterol, uric acid, total proteins, aminotransferase aspartate, and aminotransferase alanine. A low dose of AFB1 and BaP administered in ovo during early embryonic development had a significant impact on chicken embryonic development, as demonstrated by alterations in biochemical, mineral, and hepatic parameters.

Berberrubine attenuates potassium oxonate- and hypoxanthine-induced hyperuricemia by regulating urate transporters and JAK2/STAT3 signaling pathway

Phellodendri Chinensis Cortex (PC) is a traditional medicinal material used to treat gout and hyperuricemia (HUA) in China. Berberine (BBR), the main component of PC, possesses anti-hyperuricemic and anti-gout effects. However, BBR exhibits low bioavailability due to its extensive metabolism and limited absorption. Thus, the metabolites of BBR are believed to be the potential active forms responsible for its in vivo biological activities. Berberrubine (BRB), one of the major metabolites of BBR, exhibits appreciable biological activities even superior to BBR. In this work, the anti-hyperuricemic efficacy of BRB was investigated in HUA model mice induced by co-administration with intraperitoneal potassium oxonate (PO) and oral hypoxanthine (HX) for 7 days. Results showed that administration with BRB (6.25, 12.5, and 25.0 mg/kg) significantly decreased the serum levels of uric acid (UA) by 49.70%, 75.35%, and 75.96% respectively, when compared to the HUA group. In addition, BRB sharply decreased the levels of blood urea nitrogen (BUN) (by 19.62%, 28.98%, and 38.72%, respectively) and serum creatinine (CRE) (by 16.19%, 25.07%, and 52.08%, respectively) and reversed the PO/HX-induced renal histopathological damage dose-dependently. Additionally, BRB lowered the hepatic XOD activity, downregulated the expressions of glucose transporter 9 (GLUT9) and urate transporter 1 (URAT1), upregulated expressions of organic anion transporter 1/3 (OAT1/3) and ATP-binding cassette transporter subfamily G member 2 (ABCG2) at both protein and mRNA levels, and suppressed the activation of the JAK2/STAT3 signaling pathway. In addition, BRB significantly decreased the levels of inflammatory mediators (IL-1β, IL-6, and TNF-α). In conclusion, our study indicated that BRB exerted anti-hyperuricemic effect, at least in part, via regulating the urate transporter expressions and suppressing the JAK2/STAT3 signaling pathway. BRB was believed to be promising for further development into a potential therapeutic agent for HUA treatment.

Dapagliflozin and xanthine oxidase inhibitors improve insulin resistance and modulate renal glucose and urate transport in metabolic syndrome

Disturbance in glucose and uric acid metabolism is the major disorder of metabolic syndrome (MetS). The kidneys play an important role in the management of glucose and uric acid. The aim of our study was to investigate alterations in renal glucose and uric acid transporters in animals with MetS after treatment with dapagliflozin and xanthine oxidase inhibitors (allopurinol and febuxostat). Sprague-Dawley rats were fed normal chow or a high fructose diet for the first 3 months. The fructose-fed animals were then treated with dapagliflozin, allopurinol, febuxostat, or no treatment for the next 3 months. Fasting glucose, insulin resistance, and hyperuricaemia were improved in all treatment groups except that in the fructose group (all p < 0.05). Both allopurinol and febuxostat reversed the increase in levels of sodium glucose cotransporter (SGLT) 1, SGLT2, and glucose transporter (GLUT) 2 (all p < 0.05). Dapagliflozin alleviated hyperuricaemia and induced uricosuria without affecting serum xanthine oxidase activity. Dapagliflozin suppressed the expression of GLUT9, urate transporter, and urate anion exchanger 1 (all p < 0.05), which was similar to the effects of allopurinol and febuxostat. The results suggest that treatment with dapagliflozin and xanthine oxidase inhibitors improved insulin resistance and reversed the increased expression of glucose and urate transporters in the kidney.

Extracellular Vesicles and Their Relationship with the Heart-Kidney Axis, Uremia and Peritoneal Dialysis

Cardiorenal syndrome (CRS) is described as primary dysfunction in the heart culminating in renal injury or vice versa. CRS can be classified into five groups, and uremic toxin (UT) accumulation is observed in all types of CRS. Protein-bound uremic toxin (PBUT) accumulation is responsible for permanent damage to the renal tissue, and mainly occurs in CRS types 3 and 4, thus compromising renal function directly leading to a reduction in the glomerular filtration rate (GFR) and/or subsequent proteinuria. With this decrease in GFR, patients may need renal replacement therapy (RRT), such as peritoneal dialysis (PD). PD is a high-quality and home-based dialysis therapy for patients with end-stage renal disease (ESRD) and is based on the semi-permeable characteristics of the peritoneum. These patients are exposed to factors which may cause several modifications on the peritoneal membrane. The presence of UT may harm the peritoneum membrane, which in turn can lead to the formation of extracellular vesicles (EVs). EVs are released by almost all cell types and contain lipids, nucleic acids, metabolites, membrane proteins, and cytosolic components from their cell origin. Our research group previously demonstrated that the EVs can be related to endothelial dysfunction and are formed when UTs are in contact with the endothelial monolayer. In this scenario, this review explores the mechanisms of EV formation in CRS, uremia, the peritoneum, and as potential biomarkers in peritoneal dialysis.