Oxidoreductase Inhibitor Research Articles

Comparison of the incidence of proteinuria and changes in eGFR among febuxostat and topiroxostat users.

Febuxostat and topiroxostat are non-purine selective xanthine oxidoreductase inhibitors commonly used for hyperuricaemia treatment in Japan. However, comparative data on the effects of febuxostat and topiroxostat on renal function and proteinuria are limited. This study compared proteinuria incidence and changes in the estimated glomerular filtration rate (eGFR) among prevalent febuxostat and topiroxostat users. We conducted a retrospective cohort study using databases provided by DeSC Healthcare, Inc. (Tokyo, Japan). We identified 17,446 individuals (11.8% women; mean age 67.4 years) with eGFR ≥ 30 mL/min/1.73 m2 and no history of cardiovascular disease or proteinuria at baseline. Separate analyses were performed for individuals with eGFR < 60 mL/min/1.73 m2 and those with eGFR ≥ 60 mL/min/1.73 m2. The adjusted hazard ratio (HR) for proteinuria incidence in topiroxostat users compared with febuxostat users was assessed using the Cox model. Changes in eGFR were compared between the two groups using multiple regression analysis. During the mean follow-up period of 1.79 years, 1,433 participants developed proteinuria. In non-diabetic individuals with eGFR ≥ 60 mL/min/1.73 m2, the adjusted HR for proteinuria incidence in topiroxostat users compared with febuxostat users was 0.60 (95% confidence interval, 0.40-0.91; p = 0.016). No significant differences were observed in eGFR changes between the two groups with eGFR < 60 and ≥ 60 mL/min/1.73 m2. Topiroxostat prevalent users had a lower risk of proteinuria than febuxostat prevalent users in non-diabetic individuals with eGFR ≥ 60mL/min/1.73 m2. Our findings suggest that topiroxostat might be more effective than febuxostat in preventing proteinuria in non-diabetic individuals with eGFR ≥ 60 mL/min/1.73 m2.

A non-purine inhibitor of xanthine oxidoreductase mitigates adenosine triphosphate degradation under hypoxic conditions in mouse brain.

The brain is an organ that consumes a substantial amount of oxygen, and a reduction in oxygen concentration can rapidly lead to significant and irreversible brain injury. The progression of brain injury during hypoxia involves the depletion of intracellular adenosine triphosphate (ATP) due to decreased oxidative phosphorylation in the inner mitochondrial membrane. Allopurinol is a purine analog inhibitor of xanthine oxidoreductase that protects against hypoxic/ischemic brain injury; however, its underlying mechanism of action remains unclear. In addition, febuxostat is a non-purine xanthine oxidoreductase inhibitor with a different inhibitory mechanism from allopurinol. The impact of febuxostat on brain injury has not been well investigated. Therefore, this study aimed to examine brain ATP and its catabolite levels in the presence or absence of allopurinol and febuxostat under hypoxic conditions by inactivating brain metabolism using focal microwave irradiation. The hypoxic treatment caused a decrease in the adenylate energy charge and ATP levels and an increase in its catabolic products in mouse brains. The febuxostat group showed higher energy charge and ATP levels and lower ATP catabolites than the control group. Notably, despite the comparable suppression of uric acid production in both inhibitor groups, allopurinol treatment was less effective than febuxostat. These results suggest that febuxostat effectively prevents hypoxia-induced ATP degradation in the brain and that its effect is more potent than allopurinol. This study will contribute to developing therapies for improving hypoxia-induced brain dysfunction.

Optimizing Gout Treatment: A Comprehensive Review of Current and Emerging Uricosurics

Gout is the most common inflammatory arthritis, affecting approximately 5.1% of adults in the United States (US) population. Gout is a metabolic and autoinflammatory disease. Elevated uric acid pools lead to the precipitation of monosodium urate (MSU) crystals in and around joints, as well as other tissues, and the subsequent autoinflammatory response. Since elevated serum urate (SU) levels (hyperuricemia) correspond with gout severity, urate-lowering therapies (ULTs) are the cornerstone of gout treatment.ULTs include xanthine oxidoreductase inhibitors, uricosurics, less commonly used in the US but widely used in Europe and Asia, including benzbromarone, dotinurad, and probenecid (the only US Food and Drug Administration (FDA) approved uricosuric in the US), and uricases, including rasburicase and pegloticase (available only in the US).Over 90% of the daily load of uric acid filtered by the kidneys is reabsorbed through renal transporters. These urate transporters include uric acid transporter 1 (URAT1), glucose transporter 9, and organic anion transporters 1, 3, and 4 (OAT1, OAT3, OAT4). They are the target of approved and in-the-pipeline uricosurics.Any drug that increases renal excretion of uric acid, independently of the mechanism through which it exerts its effect, may be considered a uricosuric drug. This review discusses drugs that increase renal excretion of uric acid, either approved or in development, as well as off-label drugs with uricosuric properties.

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

Rationale & ObjectiveAllopurinol 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 DesignRetrospective observational cohort study. Setting & ParticipantsData 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. ExposureAllopurinol, febuxostat, and non-treatment. OutcomesAll-cause mortality, cardiovascular disease (CVD) events, heart failure (HF), acute myocardial infarction (AMI), and stroke. Analytical ApproachFor the main analyses, marginal structural Cox proportional hazards models were used to estimate hazard ratios (HRs) adjusted for time-varying confounding and selection bias due to censoring. ResultsAllopurinol and febuxostat showed significantly better survival than non-treatment for all-cause mortality (HR: 0.40, 95% confidence interval [CI]: 0.30–0.54; HR: 0.49, 95% CI: 0.38–0.63, respectively), without significant difference between allopurinol and febuxostat. Allopurinol showed significantly better survival than non-treatment, whereas febuxostat did not for CVD events (HR: 0.89, 95% CI: 0.84–0.95; HR: 1.01, 95% CI: 0.96–1.07, respectively), HF (HR: 0.71, 95% CI: 0.56–0.90; HR: 1.03, 95% CI: 0.87–1.21, respectively), and AMI (HR: 0.48, 95% CI: 0.25–0.91; HR: 0.76, 95% CI: 0.49–1.19, respectively). No comparisons showed significant results for stroke. LimitationsThe 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. ConclusionsAllopurinol and febuxostat improved survival for all-cause mortality. Allopurinol, and not febuxostat, reduced the risk of CVD events, HF, and AMI.

Topiroxostat improves glomerulosclerosis in type 2 diabetic Nagoya Shibata Yasuda mice with early diabetic kidney disease

Reactive oxygen species production might be prevented by xanthine oxidoreductase (XOR) inhibitors, which can cause glomerulosclerosis. We aimed to investigate whether topiroxostat, an XOR inhibitor, prevents diabetic kidney disease development in mice. Six-week-old control Institute of Cancer Research (ICR) mice and type 2 diabetic Nagoya Shibata Yasuda (NSY) mice were divided into the ICR group (ICR mice which received a lard-containing high-fat diet [HFD] based on the AIN-93G diet), NSY control group (NSY mice which received the same aforementioned diet), and NSY + topiroxostat group (NSY mice which received the same aforementioned diet with addition of 0.0012% topiroxostat). After 20 weeks, plasma biomarkers, XOR activity and oxidative stress levels, which were assessed using malondialdehyde (MDA), were measured through enzyme-linked immunosorbent assay or enzymatic methods. Renal pathology was evaluated using periodic acid–Schiff staining. Redox gene and protein expression were determined using RT-qPCR and western blotting, respectively. Plasma XOR activity was lower in NSY mice treated with topiroxostat than those without. Plasma cystatin C and creatinine levels did not differ between the ICR and NSY control groups or between the NSY control and NSY + topiroxostat groups. The NSY + topiroxostat group showed a smaller mesangial area than the NSY control group. The mRNA expression of Sod3, Prdx1, Gpx2, and Gpx3 was higher in the NSY + topiroxostat group than in the NSY control group. Renal MDA levels were lower in the NSY + topiroxostat group than in the NSY control group. Topiroxostat can reduce glomerulosclerosis, and the reduction is associated with renal oxidative markers.

Association of xanthine oxidoreductase inhibitor use with insulin secretory capacity in patients with type 2 diabetes.

Xanthine oxidoreductase (XOR) inhibitor treatment, which reduces reactive oxygen species (ROS) production and increases adenosine triphosphate (ATP) synthesis, has been reported to improve glycemic control. The possible protective effects of XOR inhibitor treatment on insulin secretory capacity were investigated in patients with type 2 diabetes. This retrospective cross-sectional study included 428 patients with type 2 diabetes. Insulin secretory capacity was assessed based on fasting serum C-peptide concentration (CPR) and C-peptide index (CPI) in all subjects, while insulin resistance in non-insulin users (n = 312) was determined using the homeostasis model assessment of insulin resistance (HOMA-IR) index. Median values for CPR and CPI in all subjects were 2.4 ng/mL and 1.5, respectively, while that for HOMA-IR in non-insulin users was 3.2. The XOR inhibitor users (n = 72) had significantly (P < 0.001) higher CPR and CPI levels than non-users (n = 356). Multivariable regression analyses showed XOR inhibitor use was positively associated with CPR (β = 0.153, P = 0.001) and CPI (β = 0.144, P = 0.001). Similar results were observed in propensity score analyses. In subgroup analyses of patients with a preserved estimated glomerular filtration rate (≥60 mL/min/1.73 m2) and non-insulin users, these associations remained significant. Furthermore, the associations were significant in patients with lower (≤6.0 mg/dL) but not with higher (>6.0 mg/dL) uric acid levels (P for interaction <0.05). On the other hand, XOR inhibitor use showed no significant association with HOMA-IR. The results of XOR inhibitor treatment, especially a sufficient reduction in serum uric acid level, may provide protective effects on insulin secretory capacity in patients with type 2 diabetes.

#2556 Therapeutic monitoring in patients with APRT deficiency using UPLC-MS/MS-based plasma assay

Abstract Background and Aims Adenine phosphoribosyltransferase (APRT) deficiency is a rare disorder of purine metabolism, characterized by urinary excretion of the poorly soluble 2,8-dihydroxyadenine (DHA), leading to nephrolithiasis and chronic kidney disease (CKD). Treatment with xanthine oxidoreductase (XOR) inhibitor, allopurinol or febuxostat, reduces DHA excretion and slows or halts CKD progression. The aim of the study was to optimize and validate an ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS)-based assay for simultaneous quantification of DHA, adenine, allopurinol, oxypurinol and febuxostat in human plasma, for monitoring of pharmacotherapy in patients with APRT deficiency. Method The UPLC-MS/MS-based assay was optimized employing the chemometric approach design of experiments, using the software Modde Pro 13 (Sartorius, Umeå, Sweden). The assay was validated and used for absolute quantification of DHA, adenine, allopurinol, oxypurinol and febuxostat in plasma samples from both untreated and treated APRTd patients and healthy controls. Results Accuracy and precision were within ±15% for all analytes, and the analytes were stable in plasma for 12 months at −80°C. The median (range) concentration of DHA in plasma samples from six APRT deficiency patients was 204.0 (187.2–315.8) ng/mL when they were untreated and 69.2 (below the limit of quantification [BLQ]–131.6) ng/mL when treated with allopurinol (400 mg/day), and BLQ when febuxostat (80 mg/day) was the therapeutic agent. The median (range) plasma adenine concentration was 238.1 (218–502) ng/mL in the untreated patients, and 561.1 (418–2104) and 856.0 (726–1711) ng/mL in those on treatment with allopurinol and febuxostat, respectively. DHA was not detected in plasma samples from healthy controls. The median (range) plasma concentration of allopurinol, oxypurinol and febuxostat in patients receiving XOR inhibitor therapy was 1657 (BLQ-3266) ng/mL, 8102 (4778–34906) ng/mL and 109 (BLQ-1657) ng/mL, respectively. Conclusion The UPLC-MS/MS-based assay provides accurate and precise quantification of DHA, adenine, allopurinol, oxypurinol and febuxostat in human plasma. Measurement of plasma DHA is being implemented as a diagnostic test for APRT deficiency and the full assay for monitoring of XOR inhibitor treatment in patients with the disorder.

#838 Comparison of the incidence of proteinuria and eGFR change between febuxostat and topiroxostat users

Abstract Background and Aims Febuxostat and topiroxostat are novel non-purine selective xanthine oxidoreductase (XOR) inhibitors, commonly available for the treatment of hyperuricemia in Japan. The previous studies suggested that febuxostat and topiroxostat might have renoprotective effects. It is important to compare febuxostat with topiroxostat on the renoprotective effects for the selection of the XOR inhibitors in clinical settings. However, comparative data between febuxostat and topiroxostat on renal function and proteinuria are limited. Therefore, the present study aimed to compare renal function and proteinuria between febuxostat and topiroxostat. Method We conducted a retrospective cohort study using databases provided by DeSC Healthcare Inc. (Tokyo, Japan). We identified 17,446 individuals (11.8% women; mean age 67.4 years) without estimated glomerular filtration rate (eGFR) &amp;lt;30 mL/min/1.73 m2, a history of cardiovascular disease and proteinuria at baseline. The claims database includes all inpatient, outpatient, and pharmacy claims received from insurers during the study period. The use of febuxostat and topiroxostat was defined as having claims of dispensing (or prescribing) febuxostat and topiroxostat within 1 year before the baseline health check-up, respectively. Analyses were performed for the individuals with eGFR &amp;lt;60 mL/min/1.73 m2 and those with eGFR ≥60 mL/min/1.73 m2 separately. The Cox proportional hazard model was used to assess the adjusted hazard ratio (HR) for the incidence of proteinuria in the topiroxostat users compared with the febuxostat users. We calculated the annual rate of eGFR change as the slope of the linear regression between eGFR and year for each participant. Changes in eGFR were compared between the febuxostat users and the topiroxostat users using multiple regression analysis. We performed stratified analyses according to sex, age (&amp;lt;75 and ≥75 years), body mass index (BMI) (&amp;lt;25 and ≥25 kg/m2), hypertension, and diabetes mellitus. Covariates included sex, age, BMI, current smoker, current drinker, diabetes mellitus, dyslipidemia, systolic blood pressure, use of angiotensin-converting enzyme inhibitor, angiotensin II receptor blocker, dihydropyridine calcium channel blocker, or the other antihypertensive drugs, serum uric acid level, and baseline eGFR. Results During a mean follow-up of 1.79 years, 1,433 participants developed proteinuria. In the non-diabetic individuals with eGFR ≥60 mL/min/1.73 m2, the fully adjusted HRs (95% confidence interval, p-value) for the incidence of proteinuria in the topiroxostat users compared with in the febuxostat users were 0.60 (0.40–0.91, p= 0.016). We found a significant interaction between diabetes mellitus and the use of topiroxostat on the incidence of proteinuria. No significant differences were observed in eGFR change between the two treatment groups with eGFR &amp;lt;60 and ≥60 mL/min/1.73 m2. When we evaluated the eGFR change between the two groups with eGFR &amp;lt;60 and ≥60 mL/min/1.73 m2 using the eGFRCKD-EPI, we found no significant differences in eGFR change between the two groups with eGFR &amp;lt;60 and ≥60 mL/min/1.73 m2. Conclusion The topiroxostat prevalent-users had a lower risk of the incidence of proteinuria than the febuxostat prevalent-users in the non-diabetic individuals with eGFR ≥60 mL/min/1.73 m2. Our findings suggested that topiroxostat might be more effective than febuxostat in preventing proteinuria in non-diabetic individuals with eGFR ≥60 mL/min/1.73 m2.

Xanthine oxidoreductase inhibition ameliorates high glucose-induced glomerular endothelial injury by activating AMPK through the purine salvage pathway

Xanthine oxidoreductase (XOR) contributes to reactive oxygen species production. We investigated the cytoprotective mechanisms of XOR inhibition against high glucose (HG)-induced glomerular endothelial injury, which involves activation of the AMP-activated protein kinase (AMPK). Human glomerular endothelial cells (GECs) exposed to HG were subjected to febuxostat treatment for 48 h and the expressions of AMPK and its associated signaling pathways were evaluated. HG-treated GECs were increased xanthine oxidase/xanthine dehydrogenase levels and decreased intracellular AMP/ATP ratio, and these effects were reversed by febuxostat treatment. Febuxostat enhanced the phosphorylation of AMPK, the activation of peroxisome proliferator-activated receptor (PPAR)-gamma coactivator (PGC)-1α and PPAR-α and suppressed the phosphorylation of forkhead box O (FoxO)3a in HG-treated GECs. Febuxostat also decreased nicotinamide adenine dinucleotide phosphate oxidase (Nox)1, Nox2, and Nox4 expressions; enhanced superoxide dismutase activity; and decreased malondialdehyde levels in HG-treated GECs. The knockdown of AMPK inhibited PGC-1α–FoxO3a signaling and negated the antioxidant effects of febuxostat in HG-treated GECs. Despite febuxostat administration, the knockdown of hypoxanthine phosphoribosyl transferase 1 (HPRT1) also inhibited AMPK–PGC-1α–FoxO3a in HG-treated GECs. XOR inhibition alleviates oxidative stress by activating AMPK–PGC-1α–FoxO3a signaling through the HPRT1-dependent purine salvage pathway in GECs exposed to HG conditions.

WN1703 alleviates gout symptoms via inflammatory signaling pathways in an acute gout rat model

We previously synthesized the xanthine oxidoreductase (XOR) inhibitor WN1703. In addition to showing XOR inhibitory effects, WN1703 also showed anti-inflammatory effects in a rat hyperuricemia model. Here, we studied WN1703's anti-inflammatory effects on gout and explored the underlying mechanisms. Tohoku Hospital Pediatrics-1 (THP-1) cells were stimulated by lipopolysaccharide/interferon-γ/monosodium urate (MSU). The levels of inflammatory cytokines in the supernatant and protein expression in THP-1 cells were detected using enzyme-linked immunosorbent assay (ELISA) kits and western blotting, respectively, to verify the inhibitory effects of WN1703 and its mechanism. Potassium oxonate, hypoxanthine, and MSU were administered to establish a hyperuricemia rat model complicated by acute gouty arthritis. At 1–24 h after MSU injection, the degree of ankle swelling was recorded to compare the anti-inflammatory effects at each time point. The potential mechanism was further explored using immunohistochemistry and ELISA. WN1703 significantly downregulated expression of nucleotide-binding oligomerization domain-like receptor thermal protein domain associated protein 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, toll-like receptor-4 (TLR4), myeloid differentiation primary response protein 88 (MyD88), nuclear factor-kappa B (NF-κB), and relevant cytokine levels in THP-1 cells. Identical doses of WN1703 and febuxostat had comparable effects on these proteins and cytokines. In the gout rats, the same dose of WN1703 and febuxostat showed equivalent inhibitory effects on NLRP3, ASC, and NF-κB; however, WN1703 showed weaker impacts on alleviating ankle swelling than febuxostat showed. In conclusion, WN1703 showed significant anti-inflammatory effects in hyperuricemic rats with acute gout. Such effects were related to the inhibition of the NLRP3/ASC/Caspase-1 and TLR4/MyD88/NF-κB signaling pathways, thereby downregulating inflammation-related protein expression and decreasing inflammatory cytokine secretion.

Biological properties of caffeine, (+)-catechin, and theobromine: an in silico study.

We analyzed here thein silicobiological activities of caffeine, (+)-catechin, and theobromine. For this, the PubChem database of the NIH (National Institutes of Health) was used to obtain the SMILE canonical form of the bioactive molecules, and the free software PASS Online (Prediction of Activity Spectra for Substances) from the Way2Drug portal. Also, we conducted an in vitro experiment using a chronic myeloid leukemia (CML) cell line (K562) to confirm some results found in in silico investigation. These cells were exposed to different concentrations of caffeine, (+)-catechin, and theobromine for 72h. The results found in this in silico study suggested that caffeine, (+)-catechin, and theobromine showed excellent biological properties, such as antioxidant, anti-inflammatory, and anticarcinogenic, as well as protection against cardiovascular, diabetes, neurological, allergic, respiratory, and other therapeutic activities. These findings can be elucidated through the modulation exerted by these bioactive molecules in many biochemical pathways involved in organism homeostasis, such as free radical scavenger action, oxidoreductase inhibitor, membrane permeability inhibitor, and lipid peroxidase inhibitor. In addition, we have found here that caffeine, (+)-catechin, and theobromine have a remarkable anti-inflammatory activity which plays an important role in the therapeutic approach of COVID-19. Moreover, our in vitro findings confirmed the in silico results regarding anticancer activity since these molecules reduce cell proliferation at all tested concentrations. Therefore, since these molecules exhibit important medicinal activities, further investigations should be conducted to reveal new therapies to improve the treatments and prevention of numerous disorders and, consequently, promote human health.

Effect of the Xanthine Oxidase Inhibitor Febuxostat on the Cardio-Ankle Vascular Index in Asymptomatic Patients with Hyperuricemia and Liver Dysfunction: A Sub-Analysis of the PRIZE Study

The effect of uric acid (UA)-lowering therapy with xanthine oxidoreductase (XOR) inhibitors on the development of cardiovascular disease requires further investigation. This study aimed to evaluate the long-term effects of febuxostat on arterial stiffness, focusing on liver function. The PRIZE study involved random assignment of patients with asymptomatic hyperuricemia to receive either add-on febuxostat treatment (febuxostat group) or non-pharmacological treatment (control group). Of the 514 participants, 23 and 14 patients in the febuxostat and control groups, respectively, underwent assessment of arterial stiffness using the cardio-ankle vascular index (CAVI). The participants in each group were further grouped on the basis of their baseline alanine aminotransferase (ALT) or aspartate aminotransferase (AST) levels (above or below the media value or 30 U/L). The primary endpoint was the change in the CAVI from baseline to 12 and 24 months. Overall, no significant differences were found between the control and febuxostat groups in the least-squares mean estimates of changes in CAVI at 24 months (mean between-group difference, -0.41 [95% CI, -1.05 to 0.23]; p=0.204). However, there were significant differences in participants with higher baseline ALT or AST levels above 30 U/L at 24 months (mean between-group difference, -1.12 [95% CI, -2.23 to -0.01]; p=0.048 for ALT ≥ 30 U/L and -1.08 [95% CI, -2.13 to -0.03]; p=0.044 for AST ≥ 30 U/L). Two-year treatment with febuxostat demonstrated a beneficial effect on CAVI in patients with hyperuricemia and liver dysfunction.

Sources of Reactive Oxygen Species in Normoxic and Hypoxic Naked Mole-Rat Brain

Oxygen availability dictates the rate of reactive oxygen species production from various cellular sources; excessive ROS accumulation can be cytotoxic. Mitochondria are usually the primary contributors to basal reactive oxygen species generation in the brain; however, xanthine oxidoreductase and nicotinamide adenine dinucleotide phosphate oxidase can also produce considerable reactive oxygen species during hypoxia/reoxygenation. In the brains of most mammals, cellular death accompanies hypoxia-mediated surges in reactive oxygen species production, but this is avoided in the cortex of hypoxia-tolerant naked mole-rats (Heterocephalus glaber). However, the contributions of various reactive oxygen species generators towards total reactive oxygen species homeostasis in naked mole-rat brain is unknown. We hypothesized that mitochondria remain the primary reactive oxygen species generators in naked mole-rat cortex and predicted that pharmacological inhibition of mitochondrial complex I would induce greater fluctuations in superoxide (O2•-) and hydrogen peroxide (H2O2) than inhibition of xanthine oxidoreductase or nicotinamide adenine dinucleotide phosphate oxidase. To test this, we used fluorescence microscopy to measure H2O2 and O2•- production from cortical slices during normoxia and hypoxia while pharmacologically inhibiting mitochondrial complex I, xanthine oxidoreductase, or nicotinamide adenine dinucleotide phosphate oxidase. Unexpectedly, we found xanthine oxidoreductase inhibition induced the greatest increase in O2•- during normoxia and hypoxia (~100% and 70%, respectively). Hypoxic inhibition of nicotinamide adenine dinucleotide phosphate oxidase induced the greatest decrease in H2O2 by ~35% below baseline. Finally, although inhibition of mitochondrial complex I during hypoxia yielded significant fluctuations in O2•- and H2O2, these changes were considerably smaller than fluctuations induced by inhibiting xanthine oxidoreductase or nicotinamide adenine dinucleotide phosphate oxidase. Together, and unlike in other rodent brain, our results suggest that xanthine oxidoreductase is the primary contributor to reactive oxygen species production in naked mole-rat cortex.

Paradigm shift: Bacterial quorum sensing and possible control targets

QS Designates a cell-to-cell communication process that enables bacteria to collectively modify their behaviour in response to changes in the cell density and species composition of the surrounding microbial community. These processes involve the production, release and group-wide detection of extracellular signalling molecules, which are generically called Autoinducers (AIs). It controls various genes which are responsible for various phenotypes like bioluminescence, the secretion of virulence factors, and the formation of biofilms in bacteria. Quorum quenching inhibits QS and the substances that inhibit it are called quorum sensing inhibitors. Several chemical compounds and enzymes mediate inhibition of QS, such as, lactonases, acylases and oxidoreductases. Other than these, there are some non-enzymatic methods for quorum quenching and also some plant phytochemicals have been found to inhibit it. Blocking of QS by QS Inhibition (QSI) may play an important role to disrupt biofilm formation in a device associated infection and chronic drug resistant infection. More researches are required in this area related with QS and QSI. However, some chemicals have been found to be mimicking the quorum sensing AIs activities like serotonin and rosmaric acid.

Association of plasma xanthine oxidoreductase activity with vascular endothelial function independent of serum uric acid level: MedCity21 health examination registry.

Xanthine oxidoreductase (XOR) inhibitor administration, known to reduce uric acid and reactive oxygen species (ROS) production, also improves vascular endothelial function (VEF). This cross-sectional study examined our hypothesis that XOR contributes to impaired VEF through ROS but not uric acid production. In 395 subjects (196 males, 199 females) without urate-lowering agent administration who underwent a health examination, plasma XOR activity was determined using our highly sensitive assay based on [13C2,15N2] xanthine and liquid chromatography/triple quadrupole mass spectrometry. For VEF evaluation, flow-mediated dilatation (FMD) in the brachial artery was determined by ultrasound, with physical and laboratory measurements also obtained. The median values for plasma XOR activity, serum uric acid, and FMD were 26.6pmol/h/mL, 5.4mg/dL, and 6.2%, respectively. Simple regression analysis showed weak correlations of both log plasma XOR activity and serum uric acid level with FMD (r=-0.213, p<0.001 and r=-0.139, p=0.006, respectively). However, multivariable linear regression analyses revealed that log plasma XOR activity but not serum uric acid level remained associated with FMD (β=-0.116, p=0.037 and β=0.041, p=0.549, respectively) after adjustments for various clinical parameters, with no remarkable inconsistencies for the association observed in subgroups divided based on sex or uric acid level. Finally, a series of mediation analyses showed that serum uric acid level did not meet the criteria for mediator of the association of plasma XOR activity with FMD (p=0.538). These findings suggest the possibility that XOR contributes to the pathophysiology of impaired VEF through ROS but not uric acid production.

Possible Use of Non-purine Selective Xanthine Oxidoreductase Inhibitors for Prevention of Exercise-induced Acute Kidney Injury Associated with Renal Hypouricemia

Exercise-induced acute kidney injury (EIAKI) is frequently complicated with renal hypouricemia (RHUC). In patients with RHUC, limiting anaerobic exercise can prevent EIAKI. However, it is challenging to reduce exercise intensity in athletes. We herein report a 16-year-old Japanese football player with familial RHUC with compound heterozygous mutations in urate transporter 1 (URAT1) who presented with recurrent EIAKI. As prophylaxis (hydration during exercise) could not prevent EIAKI, febuxostat was initiated. EIAKI was not observed for 16 months despite exercising intensively. Hence, non-purine-selective xanthine oxidoreductase inhibitors may decrease the incidence of EIAKI in athletes with RHUC.

Adenine phosphoribosyl transferase (APRT) deficiency and a novel sequence variant in APRT with phenotypic diversity and a literature review.

Adenine phosphoribosyl transferase (APRT) deficiency is an autosomal recessive disorder and a rare cause of urolithiasis due to mutations in APRT (OMIM #102600). APRT deficiency results in increased urinary excretion of 2,8-dihydroxyadenine (DHA) which can cause urolithiasis and kidney failure. However, with prompt diagnosis, patients with APRT deficiency can be treated with xanthine oxidoreductase inhibitors which decrease urinary DHA excretion and improve outcomes. We report a pair of siblings, an 11-year-old brother and his 14-year-old sister with compound heterozygous variants c.270del (p.Lys91Serfs*46) and c.484_486del (p.Leu162del) in APRT with variable clinical presentation of APRT deficiency. The brother presented at 17 months of age with urolithiasis and severe acute kidney injury. His elder sister remained well and asymptomatic with normal kidney function and did not develop renal calculi. Brownish disk or sphere-like crystals with both concentric and radial markings were reported on urine microscopy in the sister on screening. The sister's diagnosis was confirmed with further laboratory evidence of absent red cell lysate APRT activity with corresponding elevated levels of urinary DHA. In conclusion, we identified a novel mutation in the APRT gene in a pair of siblings with greater phenotypic severity in the male.

Hyperuricaemia Does Not Interfere with Aortopathy in a Murine Model of Marfan Syndrome.

Redox stress is involved in the aortic aneurysm pathogenesis in Marfan syndrome (MFS). We recently reported that allopurinol, a xanthine oxidoreductase inhibitor, blocked aortopathy in a MFS mouse model acting as an antioxidant without altering uric acid (UA) plasma levels. Hyperuricaemia is ambiguously associated with cardiovascular injuries as UA, having antioxidant or pro-oxidant properties depending on the concentration and accumulation site. We aimed to evaluate whether hyperuricaemia causes harm or relief in MFS aortopathy pathogenesis. Two-month-old male wild-type (WT) and MFS mice (Fbn1C1041G/+) were injected intraperitoneally for several weeks with potassium oxonate (PO), an inhibitor of uricase (an enzyme that catabolises UA to allantoin). Plasma UA and allantoin levels were measured via several techniques, aortic root diameter and cardiac parameters by ultrasonography, aortic wall structure by histopathology, and pNRF2 and 3-NT levels by immunofluorescence. PO induced a significant increase in UA in blood plasma both in WT and MFS mice, reaching a peak at three and four months of age but decaying at six months. Hyperuricaemic MFS mice showed no change in the characteristic aortic aneurysm progression or aortic wall disarray evidenced by large elastic laminae ruptures. There were no changes in cardiac parameters or the redox stress-induced nuclear translocation of pNRF2 in the aortic tunica media. Altogether, the results suggest that hyperuricaemia interferes neither with aortopathy nor cardiopathy in MFS mice.

Raising Awareness Towards Underdiagnosed Renal Hypouricemia: A Case Report

Renal hypouricemia (RHUC) is an autosomal recessive disease caused by the dysfunction of uric acid (UA) transporters in the proximal tubule causing increased fractional excretion of uric acid (FEUA). It is associated with mutations of SLC22A12 that codifies for URAT1, involved in RHUC type 1, or SLC2A9 which codifies for GLUT9 and is involved in RHUC type 2. We present the case of a man diagnosed with RHUC type 2 following hospitalization for acute kidney injury (AKI). A 43-year-old was hospitalized due to AKI after a 20 km walk at an outdoor temperature of 30°C. On the objective examination, he was dehydrated. Blood tests presented severe azotemia (creatininemia 16.43 mg/dL, uremia 254 mg/dL), UA 3.6 mg/dL, fosfatemia 6 mg/dL, Na 138 mEq/L, K 4.2 mEq/L, Cl 102 mEq/l, arterial gasometry with pH 7.35, pCO2 36 mmHg, HCO3 20 mmol/L, lactates 1.4 mmol/L. Urine test with proteinuria and unremarkable sediment. His kidneys had foci of microlithiasis. He started vigorous fluid therapy and sustained improvement in renal function was seen, with no need for renal function replacement therapy. The subsequent evaluation showed hypouricemia &lt;1.5 mg/dL and FEUA of 32.5% (normal range 5.5%-8.5%). The molecular study identified the variant c.1221del p.(His407Glnfs*8) in the SLC2A9 gene in homozygosis, which established the diagnosis of RHUC type 2. This case highlights the importance of recognizing hereditary RHUC to prevent its manifestations, including exercise-induced AKI, nephrolithiasis, nephrocalcinosis, and more rarely, progression to stage 5 CKD. Its diagnosis should be considered in individuals with serum UA &lt;2 mg/dL and elevated FEUA. Additionally, it should be confirmed by the identification of mutations in homozygous or compound heterozygous in SLC22A12 or SCL2A9. Treatment includes xanthine oxidoreductase inhibitors and adequacy of physical activity. The use of uricosuric antihypertensive drugs whose mechanism of action involves blocking the URAT1 transporter should be avoided.

CDBN-YGXZ, a Novel Small-Molecule Drug, Shows Efficacy against Clostridioides difficile Infection and Recurrence in Mouse and Hamster Infection Models.

Clostridioides difficile infection (CDI) causes severe diarrhea and colitis, leading to significant morbidity, mortality, and high medical costs worldwide. Oral vancomycin, a first-line treatment for CDI, is associated with a high risk of recurrence, necessitating novel therapies for primary and recurrent CDI. A novel small-molecule compound, CDBN-YGXZ, was synthesized by modifying the benzene ring of nitazoxanide with lauric acid. The mechanism of action of CDBN-YGXZ was validated using a pyruvate:ferredoxin/flavodoxin oxidoreductase (PFOR) inhibition assay. The efficacy of CDBN-YGXZ was evaluated using the MIC test and CDI infection model in mice and hamsters. Furthermore, metagenomics was used to reveal the underlying reasons for the effective reduction or prevention of CDI after CDBN-YGXZ treatment. The inhibitory activity against PFOR induced by CDBN-YGXZ. MIC tests showed that the in vitro activity of CDBN-YGXZ against C. difficile ranging from 0.1 to 1.5 μg/mL. In the mouse and hamster CDI models, CDBN-YGXZ provided protection during both treatment and relapse, while vancomycin treatment resulted in severe relapse and significant clinical scores. Compared with global effects on the indigenous gut microbiota induced by vancomycin, CDBN-YGXZ treatment had a mild influence on gut microbes, thus resulting in the disappearance or reduction of CDI recurrence. CDBN-YGXZ displayed potent activity against C. difficile in vitro and in vivo, reducing or preventing relapse in infected animals, which could merit further development as a potential drug candidate for treating CDI.