Chronic kidney disease: Which role for xanthine oxidoreductase activity and products?

The role of the estimated glomerular filtration rate and body roundness index in the risk assessment of uric acid-lowering therapy-resistant gout in U.S. adults: evidence from the National Health and Nutrition Examination Survey (2007-2018)

OBJECTIVE

To explore the risk factors for uric acid-lowering therapy-resistant gout (UALT-RG) and its relationships with the estimated glomerular filtration rate (eGFR), body roundness index (BRI), and visceral adiposity index (VAI) via 2007-2018 National Health and Nutrition Examination Survey (NHANES) data.

METHODS

We calculated the BRI using waist circumference and standing height; the VAI using triglycerides (TGs), high-density lipoprotein cholesterol (HDL-C), and body mass index (BMI); and the eGFR from serum creatinine levels. We also collected gout data. We explored the relationships of the eGFR, BRI, and VAI with UALT-RG risk via univariable and multivariable weighted logistic regression, trend analysis, and restricted cubic splines.

RESULTS

Among the 1,811 patients with gout, ∼9.08% had UALT-RG; these patients were more likely to have obesity, comorbid diabetes (36% [27-47%] vs. 25% [22-28%]) or impaired kidney function (eGFR < 60 mL/min/1.73 m2, 34.5% [27-43%] vs. 22.5% [20-26%]); be former smokers; and take colchicine (10% [5.6-19%] vs. 4.3% [2.8-6.7%]). Logistic regression and trend analysis suggested that an elevated BRI and decreased eGFR were independent risk factors and potential screening indicators for UALT-RG. Restricted cubic spline analysis revealed a negative linear trend between the eGFR and UALT-RG risk (p-overall < 0.0001) and a significant positive correlation between the BRI and UALT-RG risk (p-overall < 0.0001).

CONCLUSION

An increased BRI and decreased eGFR may be independent risk factors and assessment indicators for UALT-RG in U.S. adults. It is necessary to monitor serum urate levels more closely and conduct early multidisciplinary comanagement when gout is comorbid with visceral obesity and chronic kidney disease stages 3-5.

Metabolic crosstalk and therapeutic interplay between diabetes and hyperuricemia

Hyperuricemia and diabetes mellitus (DM) are prevalent metabolic disorders with high comorbidity, imposing a substantial global public health burden. Their coexistence is not merely additive but synergistic, exacerbating metabolic dysregulation through mechanisms such as insulin resistance and β-cell apoptosis, ultimately establishing a vicious cycle. Both disorders induce acute and chronic damage to vital organs, particularly the cardiovascular, renal systems. Hyperuricemia aggravates diabetic complications, notably diabetic cardiomyopathy, nephropathy and retinopathy via oxidative stress, inflammation, and metabolic dysregulation.Current urate-lowering therapies (ULTs), such as xanthine oxidase inhibitors and urate transporter 1 (URAT1, also known as SLC22A12) antagonists, demonstrate potential benefits in ameliorating diabetic complications but face challenges including safety concerns and dose adjustments. Similarly, several glucose-lowering drugs also exhibit the benefits of improving hyperuricemia. This review summarizes the metabolic crosstalk and therapeutic interplay between hyperuricemia and DM, examines the pathogenic role of uric acid in diabetic complications, and discusses the benefits and challenges of existing ULTs and glucose-lowering drugs in disrupting this cycle of metabolic dysregulation and concurrent organ damage. We hope our findings deepen the comprehension of the intricate metabolic crosstalk between glucose and urate homeostasis, providing novel therapeutic insights for patients with comorbid DM and hyperuricemia.

Xanthine Oxidoreductase: A Double-Edged Sword in Neurological Diseases

Non-communicable neurological disorders are the second leading cause of death, and their burden continues to increase as the world population grows and ages. Oxidative stress and inflammation are crucially implicated in the triggering and progression of multiple sclerosis, Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, Parkinson's disease, and even stroke. In this narrative review, we examine the role of xanthine oxidoreductase (XOR) activities and products in all the above-cited neurological diseases. The redox imbalance responsible for oxidative stress could arise from excess reactive oxygen and nitrogen species resulting from the activities of XOR, as well as from the deficiency of its main product, uric acid (UA), which is the pivotal antioxidant system in the blood. In fact, with the exception of stroke, serum UA levels are inversely related to the onset and progression of these neurological disorders. The inverse correlation observed between the level of uricemia and the presence of neurological diseases suggests a neuroprotective role for UA. Oxidative stress and inflammation are also caused by ischemia and reperfusion, a condition in which XOR action has been recognized as a contributing factor to tissue damage. The findings reported in this review could be useful for addressing clinical decision-making and treatment optimization.

Allopurinol attenuates development of Porphyromonas gingivalis LPS-induced cardiomyopathy in mice

Oxidative stress is involved in the progression of periodontitis, independently of confounding factors such as smoking, and numerous studies suggest that periodontitis is associated with increased risk of cardiovascular disease. In this study, therefore, we examined the effects of the xanthine oxidase inhibitor allopurinol on cardiac dysfunction in mice treated with Porphyromonas gingivalis lipopolysaccharide (PG-LPS) at a dose (0.8 mg/kg/day) equivalent to the circulating level in patients with periodontal disease. Mice were divided into four groups: 1) control, 2) PG-LPS, 3) allopurinol, and 4) PG-LPS +  allopurinol. After1 week, we evaluated cardiac function by echocardiography. The left ventricular ejection fraction was significantly decreased in PG-LPS-treated mice compared to the control (from 68 ±  1.3 to 60 ±  2.7%), while allopurinol ameliorated the dysfunction (67 ±  1.1%). The area of cardiac fibrosis was significantly increased (approximately 3.6-fold) and the number of apoptotic myocytes was significantly increased (approximately 7.7-fold) in the heart of the PG-LPS-treated group versus the control, and these changes were suppressed by allopurinol. The impairment of cardiac function in PG-LPS-treated mice was associated with increased production of reactive oxygen species by xanthine oxidase and NADPH oxidase 4, leading to calmodulin kinase II activation with increased ryanodine receptor 2 phosphorylation. These changes were also suppressed by allopurinol. Our results suggest that oxidative stress plays an important role in the PG-LPS-promoted development of cardiac diseases, and further indicate that allopurinol ameliorates Porphyromonas gingivalis LPS-induced cardiac dysfunction.

Attending an integrated nephrology and diabetology outpatient service can improve diabetic kidney disease treatment: a single-center experience

BACKGROUND

Glucose-lowering medications with established reno-protective effects are still underused in Italy. We explored whether attending an integrated nephrology and diabetology (NPD) outpatient service can improve clinical outcomes and adherence to treatment guidelines for diabetic kidney disease (DKD).

METHODS

We retrospectively included 110 DKD patients (aged 71.1 ± 10.1 years; 74.5% males) having attended the NPD outpatient service of CTO Hospital (Rome) between June and November 2023. Age- and gender-matched control group included DKD patients attending regular Diabetology outpatient service. Drugs prescriptions, clinical and biochemical parameters related to routine evaluation of DKD were collected at first and 6-months control visit.

RESULTS

This DKD population was made of 28.2% of patients with urine albumin-creatinine ratio (UACR) > 30 mg/gr, 33.6% with glomerular filtration rate (GFR) < 60 ml/min, 38.2% with both abnormalities. Proportion of patients prescribed with most recent anti-diabetic medications significantly increased after attending the NPD service (for SGLT-2 inhibitors, 54.5 vs. 25.5%, p < 0.01; for GLP1-R agonists, 28.3 vs. 21.8%, p = 0.01), as well as for statins (p < 0.01) and calcium channel-blockers (p = 0.01). During the same observation period we registered significant reduction in LDL cholesterol (p = 0.01) and UACR levels (p = 0.007), with a trend toward improvement in HbA1c and eGFR. Conversely, no significant differences in drugs prescriptions were reported in the control group, except for SGLT-2 inhibitors.

CONCLUSIONS

Enhanced real-time interaction and collaborative decision-making in an outpatient setting that integrates both diabetology and nephrology expertise can lead to better clinical outcomes and greater adherence to DKD management guidelines, ultimately providing a more comprehensive strategy for cardio-renal risk reduction.

Physical exercise improved the hematological effect of vitamin D in type 2 diabetes mellitus-induced nephrotoxicity in rats

Introduction

Globally, one of the major causes of renal dysfunction is diabetes mellitus (DM), and diabetic-induced nephrotoxicity has been linked with anemia. Presently, numerous antidiabetic drugs have been designed for the management of this disorder but they possess their undesirable effects such as anemia and acute kidney injury. Hence, we explore the use of vitamin D with or without exercise for the management of DM-induced renal dysfunction.

Methods

Thirty-six (36) Wistar rats were randomly separated into six (6) groups: control (vehicle treated), diabetes untreated (HFD + STZ), diabetes + vitamin D (HFD + STZ + vitamin D), diabetes + exercise (HFD + STZ + exercise), diabetes + vitamin D + exercise (HFD + STZ + vitamin D+ exercise), diabetes + metformin (HFD + STZ + metformin).

Results

Vitamin D with or without exercise significantly reduced T2DM-induced hyperglycemia. Also, a decrease in T2DM-induced increase in urea, creatinine, lactate dehydrogenase, lactate, cholesterol, and triglyceride and a rise in DM-associated reduction in high-density lipoprotein. These events were associated with a significant increase in red blood cells, hematocrit value, hemoglobin, erythropoietin, and a decrease in white blood cell count. Furthermore, vitamin D with or without exercise reversed T2DM-induced increase in pro-oxidant and pro-inflammatory markers. This observed oxido-inflammatory response was associated with a significant increase in xanthine oxidase activities and uric acid concentration. Interestingly, better recovery rates from DM-associated hematological imbalance were discovered in rats co-treated with vitamin D and exercise.

Conclusion

Our findings revealed that exercise enhanced the hematological effect of vitamin D in HFD + STZ-induced T2DM animals.

Allopurinol, Febuxostat, and Nonuse of Xanthine Oxidoreductase Inhibitor Treatment in Patients Receiving Hemodialysis: A Longitudinal Analysis

Rationale & Objective

Allopurinol and febuxostat, which are xanthine oxidoreductase inhibitors, have been widely used as uric acid-lowering medications. However, evidence regarding their cardiovascular effects in hemodialysis is insufficient. This study compared the effects of allopurinol and febuxostat on mortality and cardiovascular outcomes in patients receiving hemodialysis.

Study Design

A retrospective observational cohort study.

Setting & Participants

Data of 6,791 patients who had no history of topiroxostat usage and underwent maintenance hemodialysis between March 2016 and March 2019 at Yokohama Daiichi Hospital, Zenjinkai, and its affiliated dialysis clinics in Japan's Kanagawa and Tokyo metropolitan areas were collected.

Exposure

Allopurinol, febuxostat, and nontreatment.

Outcomes

All-cause mortality, cardiovascular disease (CVD) events, heart failure (HF), acute myocardial infarction (AMI), and stroke.

Analytical Approach

For the main analyses, marginal structural Cox proportional hazards models were used to estimate HRs adjusted for time-varying confounding and selection bias because of censoring.

Results

Allopurinol and febuxostat showed significantly better survival than nontreatment for all-cause mortality (HR, 0.40; 95% CI, 0.30-0.54 and HR, 0.49; 95% CI, 0.38-0.63, respectively), without significant difference between allopurinol and febuxostat. Allopurinol showed significantly better survival than nontreatment, whereas febuxostat did not for CVD events (HR, 0.89; 95% CI, 0.84-0.95 and HR, 1.01; 95% CI, 0.96-1.07, respectively), HF (HR, 0.71; 95% CI, 0.56-0.90 and HR, 1.03; 95% CI, 0.87-1.21, respectively), and AMI (HR, 0.48; 95% CI, 0.25-0.91 and HR, 0.76; 95% CI, 0.49-1.19, respectively). No comparisons showed significant results for stroke.

Limitations

The ratio of renal or intestinal excretion of uric acid and uremic toxins could not be elucidated, and we could not investigate gene polymorphism because of the large number of cases.

Conclusions

Allopurinol and febuxostat improved survival for all-cause mortality. Allopurinol and not febuxostat reduced the risk of CVD events, HF, and AMI.

Unconjugated bilirubin promotes uric acid restoration by activating hepatic AMPK pathway

Hyperuricemia and its development to gout have reached epidemic proportions. Systemic hyperuricemia is facilitated by elevated activity of xanthine oxidase (XO), the sole source of uric acid in mammals. Here, we aim to investigate the role of bilirubin in maintaining circulating uric acid homeostasis. We observed serum bilirubin concentrations were inversely correlated with uric acid levels in humans with new-onset hyperuricemia and advanced gout in a clinical cohort consisting of 891 participants. We confirmed that bilirubin biosynthesis impairment recapitulated traits of hyperuricemia symptoms, exemplified by raised circulating uric acid levels and accumulated hepatic XO, and exacerbated mouse hyperuricemia development. Bilirubin administration significantly decreased circulating uric acid levels in hyperuricemia-inducing (HUA) mice receiving potassium oxonate (a uricase inhibitor) or fed with a high fructose diet. Finally, we proved that bilirubin ameliorated mouse hyperuricemia by increasing hepatic autophagy, restoring antioxidant defense and normalizing mitochondrial function in a manner dependent on AMPK pathway. Hepatocyte-specific AMPKα knockdown via adeno-associated virus (AAV) 8-TBG-mediated gene delivery compromised the efficacy of bilirubin in HUA mice. Our study demonstrates the deficiency of bilirubin in hyperuricemia progression, and the protective effects exerted by bilirubin against mouse hyperuricemia development, which may potentiate clinical management of hyperuricemia.

Comparison of the predictive value of four insulin resistance surrogates and hyperuricemia in women with recurrent pregnancy loss: A cross-sectional study

BACKGROUND

Insulin resistance (IR), hyperuricemia (HUA), and recurrent pregnancy loss (RPL) elevate the risk of cardiovascular disease and metabolic disorders, while also impacting reproductive health. The relationship between IR, HUA, and RPL has not been thoroughly investigated. This study investigates the relationship between four IR surrogates and the risk of HUA in RPL patients.

METHODS

Data from a real-world study on RPL in China were analyzed using multivariable regression to determine the relationship between HUA and triglyceride and glucose (TyG) index, triglyceride glucose-body mass index (TyG-BMI), triglyceride to high-density lipoprotein cholesterol (TG/HDL-c) ratio, and metabolic score for insulin resistance (METS-IR). The predictive ability of these surrogates for detecting HUA in RPL patients was evaluated using the area under the curve and receiver operating characteristic analysis. Sensitivity analysis was performed using bootstrapping resampling.

RESULTS

The study included 769 patients with a mean age of 30 ± 4 years old, 8.32% of whom had HUA. Four IR surrogates were closely related to HUA in patients of RPL after adjusting for age, menstrual cycle, creatinine, alanine transaminase, aspartate transaminase, total cholesterol, homocysteine, and low-density lipoprotein, with area under the curve values of TyG index (OR = 0.693, 95% confidence interval [CI]: 0.626, 0.759), TyG-BMI (OR = 0.731 95% CI: 0.657, 0.805), TG/HDL-C (OR = 0.703, 95% CI: 0.641, 0.764), and METS-IR (OR = 0.728, 95% CI: 0.655, 0.799). Bootstrap resampling yielded similar results.

CONCLUSIONS

The TyG index, TyG-BMI, TG/HDL-c, and METS-IR significantly correlated with HUA in patients with RPL. The TyG-BMI had the highest predictive value of the four IR surrogates.

Assessing the causal relationship between obesity and hypothyroidism using Mendelian randomization

To explore the causal relationship between obesity and hypothyroidism and identify risk factors and the predictive value of subclinical hypothyroidism (SCH) in obese patients using Mendelian randomization, this study employed five Mendelian randomization methods (MR Egger, Weighted Median, Inverse Variance Weighted, Simple Mode, and Weighted Mode) to analyze clinical data from 308 obese patients at the People's Hospital of Xinjiang Uygur Autonomous Region, from January 2015 to June 2023. Patients were divided based on thyroid function tests into normal (n = 173) and SCH groups (n = 56). Comparative analyses, along with univariate and multivariate logistic regression, were conducted to identify risk factors for SCH in obese patients. A significant association between obesity and hypothyroidism was established, especially highlighted by the inverse variance weighted method. SCH patients showed higher ages, thyroid-stimulating hormone levels, and thyroid autoantibody positivity rates, with lower T4 and FT4 levels. Age, FT4, thyroid autoantibodies, TPO-Ab, and Tg-Ab were confirmed as risk factors. The predictive value of FT4 levels for SCH in obesity was significant, with an Area Under the Curve (AUC) of 0.632. The study supports a potential causal link between obesity and hypothyroidism, identifying specific risk factors for SCH in obese patients. FT4 level stands out as an independent predictive factor, suggesting its utility in early diagnosis and preventive strategies for SCH.

Hyperuricemia and its related diseases: mechanisms and advances in therapy

Hyperuricemia, characterized by elevated levels of serum uric acid (SUA), is linked to a spectrum of commodities such as gout, cardiovascular diseases, renal disorders, metabolic syndrome, and diabetes, etc. Significantly impairing the quality of life for those affected, the prevalence of hyperuricemia is an upward trend globally, especially in most developed countries. UA possesses a multifaceted role, such as antioxidant, pro-oxidative, pro-inflammatory, nitric oxide modulating, anti-aging, and immune effects, which are significant in both physiological and pathological contexts. The equilibrium of circulating urate levels hinges on the interplay between production and excretion, a delicate balance orchestrated by urate transporter functions across various epithelial tissues and cell types. While existing research has identified hyperuricemia involvement in numerous biological processes and signaling pathways, the precise mechanisms connecting elevated UA levels to disease etiology remain to be fully elucidated. In addition, the influence of genetic susceptibilities and environmental determinants on hyperuricemia calls for a detailed and nuanced examination. This review compiles data from global epidemiological studies and clinical practices, exploring the physiological processes and the genetic foundations of urate transporters in depth. Furthermore, we uncover the complex mechanisms by which the UA induced inflammation influences metabolic processes in individuals with hyperuricemia and the association with its relative disease, offering a foundation for innovative therapeutic approaches and advanced pharmacological strategies.

Structure-Activity Relationships and Changes in the Inhibition of Xanthine Oxidase by Polyphenols: A Review

Hyperuricemia (HUA), or elevated uric acid in the blood, has become more prevalent in recent years. Polyphenols, which are known to have good inhibitory activity on xanthine oxidoreductase (XOR), are effective in uric acid reduction. In this review, we address the structure-activity relationship of flavonoids that inhibit XOR activity from two perspectives: the key residues of XOR and the structural properties of flavonoids. Flavonoids' inhibitory effect is enhanced by their hydroxyl, methoxy, and planar structures, whereas glycosylation dramatically reduces their activity. The flavonoid structure-activity relationship informed subsequent discussions of the changes that occur in polyphenols' XOR inhibitory activity during their extraction, processing, gastrointestinal digestion, absorption, and interactions. Furthermore, gastrointestinal digestion and heat treatment during processing can boost the inhibition of XOR. Polyphenols with comparable structures may have a synergistic effect, and their synergy with allopurinol thus provides a promising future research direction.

Associations of oxidative balance score with hyperuricemia and gout among American adults: a population-based study

Objective

The current study aimed to assess the relationships between oxidative balance score (OBS) and OBS subclasses (dietary and lifestyle OBS) with risks of hyperuricemia (HUA) and gout among American adults.

Methods

Participants in the National Health and Nutrition Examination Survey from 2007 to 2018 were initially recruited and then the final sample was restricted to adults without missing values about serum uric acid, gout, OBS, and covariates. Rao-Scott adjusted chi-square test and analysis of variance were utilized to compare the baseline characteristics in adults of different quartiles of OBS, while the weighted stepped logistic regression models were used to explore the associations of overall, dietary, and lifestyle OBS with the risks of HUA and gout. Weighted restricted cubic spline analyses were conducted to explore the nonlinear dose-response associations.

Results

The final sample consisted of 22,705 participants aged 20 years and older, which was representative of approximately 197.3 million non-institutionalized American adults. HUA and gout prevalence decreased with OBS quartiles. Compared with adults in the first quartile of OBS, those in the second (OR: 0.85, 95% CI: 0.72-0.99), third (OR: 0.71, 95% CI: 0.58-0.85), and fourth (OR: 0.48, 95% CI: 0.38-0.61) quartiles of OBS had reduced risks of hyperuricemia. Similarly, adults in the second (OR: 0.70, 95% CI: 0.51-0.97) quartile of OBS was associated with lower gout risk in comparison to adults in the lowest quartile. Regarding OBS subclasses, dietary and lifestyle OBS were both negatively correlated with the risk of HUA, and only higher lifestyle OBS was significantly associated with lower gout risk. Furthermore, the subgroup analyses and interaction effects also substantiated similar effects. Significant nonlinear dose-response relationships were observed between overall, dietary, and lifestyle OBS with HUA risk as well as that of lifestyle OBS with gout risk.

Conclusion

This study strongly suggests the significant negative associations of OBS with HUA and gout in American adults and provides a dietary and lifestyle guideline to reduce the risks.

Cardiometabolic comorbidities and complications of obesity and chronic kidney disease (CKD)

Obesity and chronic kidney disease are two ongoing progressive clinical pandemics of major public health and clinical care significance. Because of their growing prevalence, chronic indolent course and consequent complications both these conditions place significant burden on the health care delivery system especially in developed countries like the United States. Beyond the chance coexistence of both of these conditions in the same patient based on high prevalence it is now apparent that obesity is associated with and likely has a direct causal role in the onset, progression and severity of chronic kidney disease. The causes and underlying pathophysiology of this are myriad, complicated and multi-faceted. In this review, continuing the theme of this special edition of the journal on " The Cross roads between Endocrinology and Nephrology" we review the epidemiology of obesity related chronic kidney disease (ORCKD), and its various underlying causes and pathophysiology. In addition, we delve into the consequent comorbidities and complications associated with ORCKD with particular emphasis on the cardio metabolic consequences and then review the current body of evidence for available strategies for chronic kidney disease modulation in ORCKD as well as the potential unique role of weight reduction and management strategies in its improvement and risk reduction.

Gender Influence on XOR Activities and Related Pathologies: A Narrative Review

Taking into account the patient's gender is the first step towards more precise and egalitarian medicine. The gender-related divergences observed in purine catabolism and their pathological consequences are good examples of gender medicine differences. Uric acid is produced by the activity of xanthine oxidoreductase (XOR). The serum levels of both XOR activity and uric acid differ physiologically between the genders, being higher in men than in women. Their higher levels have been associated with gout and hypertension, as well as with vascular, cardiac, renal, and metabolic diseases. The present review analyzes the gender-related differences in these pathological conditions in relation to increases in the serum levels of XOR and/or uric acid and the opportunity for gender-driven pharmacological treatment.

New concepts drive the development of delivery tools for sustainable treatment of diabetic complications

Diabetic complications, especially diabetic retinopathy, diabetic nephropathy and painful diabetic neuropathy, account for a large portion of patients with diabetes and display rising global prevalence. They are the leading causes of blindness, kidney failure and hypersensitivity to pain caused by diabetes. Current approved therapeutics against the diabetic complications are few and exhibit limited efficacy. The enhanced cell-specificity, stability, biocompatibility, and loading capacity of drugs are essential for the mitigation of diabetic complications. In the article, we have critically discussed the recent studies over the past two years in material sciences and biochemistry. The insightful concepts in these studies drive the development of novel nanoparticles and mesenchymal stem cells-derived extracellular vesicles to meet the need for treatment of diabetic complications. Their underlying biochemical principles, advantages and limitations have been in-depth analyzed. The nanoparticles discussed in the article include double-headed nanodelivery system, nanozyme, ESC-HCM-B system, soft polymer nanostars, tetrahedral DNA nanostructures and hydrogels. They ameliorate the diabetic complication through attenuation of inflammation, apoptosis and restoration of metabolic homeostasis. Moreover, mesenchymal stem cell-derived extracellular vesicles efficiently deliver therapeutic proteins to the retinal cells to suppress the angiogenesis, inflammation, apoptosis and oxidative stress to reverse diabetic retinopathy. Collectively, we provide a critical discussion on the concept, mechanism and therapeutic applicability of new delivery tools to treat these three devastating diabetic complications.

Association of circulatory PCSK-9 with biomarkers of redox imbalance and inflammatory cascades in the prognosis of diabetes and associated complications: a pilot study in the Indian population

AbstractsBesides the profound role of proprotein convertase subtilisin/kexin type-9 (PCSK-9) in LDL-C regulation, its association with other metabolic complications cannot be disregarded. The co-existence of redox imbalance and inflammatory cascades has greatly reflected the etiology of hyperglycemia. Therefore, we studied the association of PCSK-9 with inflammation and oxidative stress biomarkers to predict its role in the prognosis of diabetes and its associated complications in the Indian population. This pilot study examined a total of n = 187 subjects: healthy controls (HC; n = 50), diabetic without complication (T2DM; n = 49), diabetic nephropathy (T2DM-N; n = 43), and diabetic dyslipidemic (T2DM-DL; n = 45) subjects. The relationship between circulatory PCSK-9 levels and inflammation and redox imbalance biomarkers has been explored. The significant positive association of elevated PCSK-9 level with the inflammatory (i.e. IL-1β, IL-6, TNF-α, and CRP) and oxidative stress marker (i.e. XOD, CD, LOOH, and MDA) was observed in T2DM-N and T2DM-DL subjects. Whereas single regression analysis depicted that PCSK-9 was inversely associated with the FRAP and PON-1 in T2DM-N and T2DM-DL subjects. Furthermore, no significant correlation was detected in both T2DM and HC subjects. We found a significant relationship between these prognostic biomarkers with an elevated level of PCSK-9 in T2DM-N and T2DM-DL subjects. PCSK-9 is a nontraditional biomarker in diabetes that may help identify patients at risk of developing secondary complications of diabetes in the Indian population. However, further large cohort validation studies are needed.

Association between periodontitis and uric acid levels in blood and oral fluids: a systematic review and meta-analysis

BACKGROUND

Uric acid, a formerly-known antioxidant that has recently been linked to numerous inflammatory diseases as a pro-inflammatory and -oxidative mediator in pathological conditions. It is imperative to reassess the association between periodontitis and uric acid locally and systematically. The aim of this systematic review was to systemically evaluate the association between periodontitis and the uric acid (UA) levels in blood, saliva and gingival crevicular fluid (GCF).

METHODS

Relevant clinical studies up to January 28, 2023 were identified and retrieved from electronic databases including PubMed, Scopus, EMBASE and Web of Science, with periodontitis, uric acid, hyperuricemia and gout as the keywords. The weighted (WMD) or standardized mean difference (SMD) was calculated using fixed- or random-effect models. Methodological heterogeneity was assessed.

RESULTS

Sixteen eligible observational studies and one RCT were enrolled, which included 1354 patients with periodontitis and 989 controls. Three sample types for UA detection were involved, including blood (n = 8), saliva (n = 9) and GCF (n = 1). Meta-analysis demonstrated an enhanced plasma UA concentration (WMD = 1.00 mg/dL, 95% CI 0.63 to 1.37, P < 0.001) but a decreased salivary UA level (SMD = -0.95, 95% CI -1.23 to -0.68, P < 0.001) in periodontitis versus control. Statistical heterogeneity among the plasma- and saliva-tested studies were moderate (I² = 58.3%, P = 0.066) and low (I² = 33.8%, P = 0.196), respectively.

CONCLUSIONS

Within the limitations of the enrolled studies, it seems that there is an association between periodontitis and increased blood UA and decreased salivary UA. (Registration no. CRD42020172535 in Prospero).

Human Plasma Xanthine Oxidoreductase Activity in Cardiovascular Disease: Evidence from a Population-Based Study

Xanthine oxidoreductase (XOR) and its products contribute to the development of chronic inflammation and oxidative stress. Excessive XOR activity is believed to promote inflammatory responses and atherosclerotic plaque formation, which are major cardiovascular risk factors. The mechanisms of XOR activity in the development and progression of cardiovascular disease (CVD), coupled with the complexity of the relationship between XOR activity and the biological effects of uric acid; reactive oxygen species; and nitric oxide, which are the major products of XOR activity, have long been debated, but have not yet been clearly elucidated. Recently, a system for measuring highly sensitive XOR activity in human plasma was established, and there has been progress in the research on the mechanisms of XOR activity. In addition, there are accumulating findings about the relationship between XOR activity and CVD. In this narrative review, we summarize existing knowledge regarding plasma XOR activity and its relationship with CVD and discuss future perspectives.

Folic Acid Protects against Hyperuricemia in C57BL/6J Mice via Ameliorating Gut-Kidney Axis Dysfunction

Emerging lines of research evidence point to a vital role of gut-kidney axis in the development of hyperuricemia (HUA), which has been identified as an increasing burden worldwide due to the high prevalence. The involved crosstalk which links the metabolic and immune-related pathways is mainly responsible for maintaining the axial homeostasis of uric acid (UA) metabolism. Nowadays, the urate-lowering drugs only aim to treat acute gouty arthritis as a result of their controversial clinical application in HUA. In this study, we established the HUA model of C57BL/6J mice to evaluate the effectiveness of folic acid on UA metabolism and further explored the underlying mechanisms. Folic acid attenuated the kidney tissue injury and excretion dysfunction, as well as the typical fibrosis in HUA mice. Molecular docking results also revealed the structure-activity relationship of the folic acid metabolic unit and the UA transporters GLUT9 and URAT1, implying the potential interaction. Also, folic acid alleviated HUA-induced Th17/Treg imbalance and intestinal tissue damage and inhibited the active state of the TLR4/NF-κB signaling pathway, which is closely associated with the circulating LPS level caused by the impaired intestinal permeability. Furthermore, the changes of intestinal microecology induced by HUA were restored by folic acid, including the alteration in the structure and species composition of the gut microbiome community, and metabolite short-chain fatty acids. Collectively, this study revealed that folic acid intervention exerted improving effects on HUA by ameliorating gut-kidney axis dysfunction.