Adherence to the Dietary Approaches to Stop Hypertension (DASH) and Serum Urate Concentrations: A Longitudinal Analysis from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

BACKGROUND: Increased serum urate (SU) and hyperuricemia (HU) are associated with chronic noncommunicable diseases and mortality. SU concentrations are affected by several factors, including diet, and are expected to rise with age. We investigated whether the Dietary Approaches to Stop Hypertension (DASH) diet alter this trend. OBJECTIVE: The objective was to assess whether adherence to the DASH diet predicts a longitudinal change in SU concentrations and risk of HU in 8 y of follow-up. METHODS: Longitudinal analyses using baseline (2008-2010, aged 35-74 y), second (2012-2014), and third (2016-2018) visits data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). The inclusion criteria were having complete food frequency questionnaire (FFQ) and urinary sodium measurement, in addition to having SU measurement at the 1st visit and at least 1 of the 2 follow-up visits. For the HU incidence analyses, participants had also to be free from HU at baseline. The final samples included 12575 individuals for the SU change analyses and 10549 for the HU incidence analyses. Adherence to DASH diet was assessed as continuous value. HU was defined as SU>6.8 mg/dL and/or urate-lowering therapy use. Mixed-effect linear and Poisson regressions (incidence rate ratio [IRR] and 95% confidence interval [CI]) were used in the analyses, adjusted for confounders. RESULTS: The mean age was 51.4 (8.7) y, and 55.4% were females. SU means (standard deviation) were 5.4 (1.4) at 1st visit, 5.2 (1.4) at 2nd visit, and 5.1(1.3) mg/dL at 3rd visit. The HU incidence rate was 8.87 per 1000 person-y. Each additional point in adherence to the DASH diet accelerated SU decline (P< 0.01) and lowered the incidence of HU by 4.3% (IRR: 0.957; 95% CI: 0.938,0.977) in adjusted model. CONCLUSION: The present study findings reinforce the importance of encouraging the DASH diet as a healthy dietary pattern to control and reduce the SU concentrations and risk of HU.

Pathogenesis of an experimental mycobacteriosis in an apple snail.

In this work, we aimed at investigating cell and tissue responses of the apple snail Pomacea canaliculata, following the inoculation of the zoonotic pathogen Mycobacterium marinum. Different doses were tested (10, 20, 65, and 100 M CFU) and the mortality rate was negligible. The histopathogenesis was followed at 4, 9, and 28 days after inoculation. Overt histopathological lesions were consistently observed after the two largest doses only. In the lung, marked hemocyte aggregations, including intravascular nodule formation, were observed within the large blood veins that run along the floor and roof of this organ. Hemocyte aggregations were found occluding many of the radial sinuses supplying the respiratory lamina. Acid-fast bacilli were contained in the different hemocyte aggregations. In addition, hemocytes were observed infiltrating the storage tissue, which makes up most of the lung wall, and the connective tissue of the mantle edge. Additionally, signs of degradation in the storage tissue were observed in the lung wall on day 28. In the kidney, nodules were formed associated with the constitutive hemocyte islets and with the subpallial hemocoelic space, in whose hemocytes the acid-fast structures were found. Electron microscopy analysis revealed the presence of bacteria-containing phagosomes within hemocytes located in the surface zone of the islets. Additionally, electron-dense spheroidal structures, which are likely remnants of digested mycobacteria, were observed in close proximity to the hemocytes' nuclei. The size attained by the hemocyte nodules varied during the observation period, but there was no clear dependence on dose or time after inoculation. Nodules were also formed subpallially. Some of these nodules showed 2-3 layers with different cellular composition, suggesting they may also form through successive waves of circulating cells reaching them. Nodular cores, including those formed intravascularly in the lung, would exhibit signs of hemocyte dedifferentiation, possibly proliferation, and death. Hemocyte congestion was observed in the hemocoelic spaces surrounding the pallial ends of the renal crypts, and the renal crypts themselves showed de-epithelization, particularly on day 28. The diverse cellular responses of P. canaliculata to M. marinum inoculation and the high resilience of this snail to the pathogen make it a suitable species for studying mycobacterial infections and their effects on cellular and physiological processes.

Antiphagocytic Properties of Polygallic Acid with Implications in Gouty Inflammation.

Polygallic acid (PGAL) has been used in vitro to protect synoviocytes from monosodium urate (MSU) crystals due to its anti-inflammatory properties. However, MSU crystals can also activate other cells of the synovial fluid (SF). We studied the impact of PGAL on the phagocytosis of MSU crystals, inflammation, and oxidative stress using an in vitro model with SF leukocytes and THP-1 monocyte cells. SF leukocytes were stimulated with PGAL and MSU crystals, proinflammatory cytokines and phagocytosis were assessed. In THP-1 cells, the effect of PGAL on the phagocytosis of MSU crystals and the levels of IL-1ß, IL-6, TNF-α, and reactive oxygen species (ROS) was evaluated. PGAL was added to THP-1 cultures 24 h before MSU crystal addition as a pre-treatment, and IL-1ß was measured. One-way ANOVA with Tukey's post hoc test was performed, and a P value < 0.05 was considered statistically significant. PGAL (100 µg/mL) decreased phagocytosis in SF leukocytes by 14% compared to cells exposed to crystals without PGAL. In THP-1 cells, 100 and 200 µg/mL PGAL reduced phagocytosis by 17% and 15%, respectively. In SF cells, there was a tendency to decrease IL-1ß and IL-6. In THP-1 cells, decreases in IL-1ß and TNF-α, as well as a slight decrease in ROS, were identified. PGAL pre-treatment resulted in a reduction of IL-1ß. PGAL inhibits MSU phagocytosis by exerting an anti-inflammatory effect on cells exposed to crystals. The use of PGAL before an acute attack of gout suggests an important protective factor to control the inflammation.

Relationship between rs4349859 and rs116488202 polymorphisms close to MHC-I region and serum urate levels in patients with gout.

BACKGROUND: Gout is the most common inflammatory rheumatic disease and elevated levels of serum urate (SU) are the main cause for its development. Major histocompatibility complex class 1 (MHC-1) plays an important role in the development of multiple inflammatory diseases; however, there is little evidence of its involvement in gout. The present study focused on evaluating the association of the rs4349859 and rs116488202 single nucleotide polymorphisms (SNPs) close to the MHC-1 region in patients with gout. METHODS AND RESULTS: One hundred and seventy-six individuals of Mexican origin were included, of which 81 were patients with primary gout and 95 were healthy controls. The rs4349859 and rs116488202 SNPs were genotyped using TaqMan probes by allelic discrimination by real-time PCR. Serum concentrations of biochemical parameters were measured with enzymatic methods. Descriptive statistics were applied and P-values < 0.05 were considered significant. It was observed that the rs4349859 and rs116488202 SNPs showed significant association with the risk of gout (OR = 146, 95%CI = 44.8-480.2, P < 0.01; OR = 2885, 95%CI = 265-31398, P < 0.01, respectively). Our results also showed significantly higher serum SU levels in gout patients with respect to controls (P < 0.01) in the carriers of the GA genotype compared with the GG genotype of the rs4349859 variant, and in the carriers of the CT genotype compared with the CC genotype of the rs116488202 variant. CONCLUSION: The study revealed that rs4349859 and rs116488202 SNPs close to MHC-I region confers strong susceptibility to gout in Mexican population, and the heterozygous genotypes of both were associated with higher levels of SU.

Osteogenic Potential of Monosodium Urate Crystals in Synovial Mesenchymal Stem Cells.

Background and Objectives: Deposits of monosodium urate (MSU) crystals due to increased levels of uric acid (UA) have been associated with bone formation and erosion, mainly in patients with chronic gout. The synovial membrane (SM) comprises several types of cells, including mesenchymal stem cells (SM-MSCs); however, it is unknown whether UA and MSU induce osteogenesis through SM-MSCs. Materials and Methods: Cultures of SM were immunotyped with CD44, CD69, CD90, CD166, CD105, CD34, and CD45 to identify MSCs. CD90+ cells were isolated by immunomagnetic separation (MACS), colony-forming units (CFU) were identified, and the cells were exposed to UA (3, 6.8, and 9 mg/dL) and MSU crystals (1, 5, and 10 µg/mL) for 3 weeks, and cellular morphological changes were evaluated. IL-1ß and IL-6 were determined by ELISA, mineralization was assessed by alizarin red, and the expression of Runx2 was assessed by Western blot. Results: Cells derived from SM and after immunomagnetic separation were positive for CD90 (53 ± 8%) and CD105 (52 ± 18%) antigens, with 53 ± 5 CFU identified. Long-term exposure to SM-MSCs by UA and MSU crystals did not cause morphological damage or affect cell viability, nor were indicators of inflammation detected. Mineralization was observed at doses of 6.8 mg/dL UA and 5 µg/mL MSU crystals; however, the differences were not significant with respect to the control. The highest dose of MSU crystals (10 µg/mL) induced significant Runx2 expression with respect to the control (1.4 times greater) and SM-MSCs cultured in the osteogenic medium. Conclusions: MSU crystals may modulate osteogenic differentiation of SM-MSCs through an increase in Runx2.

Angiotensin type 2 receptor antagonism as a new target to manage gout.

BACKGROUND: There is a growing search for therapeutic targets in the treatment of gout. The present study aimed to evaluate the analgesic and anti-inflammatory potential of angiotensin type 2 receptor (AT2R) antagonism in an acute gout attack mouse model. METHODS: Male wild-type (WT) C57BL/6 mice either with the AT2R antagonist, PD123319 (10 pmol/joint), or with vehicle injections, or AT2R KO mice, received intra-articular (IA) injection of monosodium urate (MSU) crystals (100 µg/joint), that induce the acute gout attack, and were tested for mechanical allodynia, thermal hyperalgesia, spontaneous nociception and ankle edema development at several times after the injections. To test an involvement of AT2R in joint pain, mice received an IA administration of angiotensin II (0.05-5 nmol/joint) with or without PD123319, and were also evaluated for pain and edema development. Ankle joint tissue samples from mice undergoing the above treatments were assessed for myeloperoxidase activity, IL-1ß release, mRNA expression analyses and nitrite/nitrate levels, 4 h after injections. RESULTS: AT2R antagonism has robust antinociceptive effects on mechanical allodynia (44% reduction) and spontaneous nociception (56%), as well as anti-inflammatory effects preventing edema formation (45%), reducing myeloperoxidase activity (54%) and IL-1ß levels (32%). Additionally, Agtr2tm1a mutant mice have largely reduced painful signs of gout. Angiotensin II administration causes pain and inflammation, which was prevented by AT2R antagonism, as observed in mechanical allodynia 4 h (100%), spontaneous nociception (46%), cold nociceptive response (54%), edema formation (83%), myeloperoxidase activity (48%), and IL-1ß levels (89%). PD123319 treatment also reduces NO concentrations (74%) and AT2R mRNA levels in comparison with MSU untreated mice. CONCLUSION: Our findings show that AT2R activation contributes to acute pain in experimental mouse models of gout. Therefore, the antagonism of AT2R may be a potential therapeutic option to manage gout arthritis.

Mineral composition and clinical aspects of urolithiasis in cats in Brazil / Composição mineral e aspectos clínicos da urolitíase em gatos no Brasil

Between October 2016 and October 2017, 63 feline uroliths were analyzed at Universidade Federal de Goiás (UFG) by using both chemical analysis and energy dispersive spectroscopy (EDS). The most frequent mineral type found was struvite (53.9%), followed by urate (39.7%), calcium oxalate (30.1%) and calcium phosphate (25.3%). Calculus containing xanthine, cystine and silica were not observed. Uroliths classified as simple, comprised a total of 34/63. Amongst the 42 animals present in the study, 26 were male and 16 were female. Pure breed animals comprised 14.4% of the total, and the breeds observed within the study were the Persian, Himalayan, Siamese, and Angora. Cats between 25-72 months old were more frequently diagnosed with uroliths. The clinical signs varied between systemic and urinary signs and the most found were anorexia, vomiting, hematuria and dysuria. All patients were either spayed or neutered and 34 patients had no outdoor access. Familial information was unknown in almost 100% of the cases. The results observed in the present study serve as a basis for future comparisons related to the epidemiology of urinary lithiasis in Brazil, especially for the feline species.

Entre outubro de 2016 e outubro de 2017, 63 urólitos felinos foram analisados na Universidade Federal de Goiás (UFG), usando-se tanto análise química quanto espectroscopia por energia dispersiva (EDS). O tipo de mineral mais encontrado foi o estruvita (53,9%), seguido pelo urato (39,7%), oxalato de cálcio (30,1%) e fosfato de cálcio (25,3%). Cálculos contendo xantina, cistina e sílica não foram observados. Urólitos classificados como simples comprometeram um total de 34/63. Entre os 42 animais presentes no estudo, 26 eram machos e 16 eram fêmeas. Dos animais comprometidos, 14,4% eram de raças puras, sendo observadas as raças Persa, Himalaio, Siamês e Angorá. Gatos com idade entre 25-72 meses foram mais frequentemente diagnosticados com urólitos. Os sinais clínicos variaram entre sinais sistêmicos e urinários, sendo anorexia, vômito, hematúria e disúria os mais encontrados. Todos os pacientes eram castrados, e 34 deles não tinham acesso à rua. Histórico familiar era desconhecido em quase 100% dos casos. Os resultados observados no presente estudo servem como base para comparações futuras relacionadas à epidemiologia da litíase urinária no Brasil, especialmente em espécies felinas.

Lycopodium as a treatment for Urate Deposition (gout) in birds: case report

A 3-year-old male cockatiel (Nymphicus hollandicus) was diagnosed with joint arthritis due to hyperucemiasyndrome. The bird presented deposition of urate crystals on the synovial membrane with inflammation of joints and tendons (tufts), causing listlessness, anorexia and lameness, with difficulty in keeping perched or moving. Laboratory tests displayed an increase in uric acid and creatinine phosphokinase levels, and leukocytosis despite lymphopenia. Unsucessfully, the animal had been treated with allopathic medicine for 2 months, without a favorable response and still developing stressful reaction to handling.Methodology:High dilution therapy was attempted with 2 globules of Lycopodiumclavatum30 cH /bid and Arnica montana30 cH /bid /oral. The most expressive tufts were removed with daily cleaning of the affected area; a new diet was established and perches were removed, allowing the bird to remain on a flat surface until regression of symptoms. The medication was continued for 30 days. On the second appointment, although the caregiver reported episodes of probable pain, there was an improvement in behavior with normal appetite. Lyc30cH /sid was continued and Arn30cH /bid to qid, depending on pain episodes, for over 30 days. The tutor authorized the case report through a consent form. Results and discussion:Follow-up laboratory tests were performed everythree months for one year, reaching normal levels for uric acid (3.5-11 mg/dL) and CK (30-245mg/dL) on the third measurement. The bird presented no formation of new tufts along the second month of treatment. After 12 months, the animal ingests homeopathic globules spontaneously and presents stable clinical presentation (Lyc30cH / sid / 3 times a week) with no recurrence and without side effects nor stressful behavior. Conclusion: In view of these results, it is considered that homeopathic treatment is an option to be considered in the treatment of joint arthritis from hyperuricemia syndrome in birds.

The effect of initiation of urate-lowering treatment during a gout flare on the current episode: a meta-analysis of randomized controlled trials

Abstract Objective: The objective was to evaluate whether initiation of urate-lowering treatment (ULT) during an acute gout flare prolonged the current episode. Methods: A comprehensive search of MEDLINE and Web of Science databases was conducted from their inception to 15 March 2021. Five randomized controlled trials (RCTs) with 381 patients met the inclusion criteria. Standardized mean difference (SMD), odds ratio (OR), and 95% confidence interval (CI) were used for estimating the clinical efficacy of ULT in acute gout. Results: There was no statistical difference in days to resolution (intent-to-treat analysis) (SMD, 0.68; 95% CI — 0.42 to 1.78; I2, 49%; p = 0.22), the pain visual analogue score (VAS) by day 10 (SMD, — 0.07; 95% CI — 0.30 to 0.16; I2, 0%; p = 0.53), C-reactive protein (CRP) from day 7 to 10 (SMD, — 1.14; 95% CI — 5.63 to 3.36; I2, 55%; p = 0.62), erythrocyte sedimentation rate (ESR) from day 7 to 10 (SMD, — 2.51; 95% CI — 5.46 to 0.45; I2, 0%; p = 0.10) and the recurrence of gout flares within 28-30 days (OR 0.78; 95% CI 0.29 to 2.09; I2, 0%; p = 0.62). Conclusion: Initiation of ULT during an acute gout flare did not prolong the duration of the flare. However, larger sample size studies are needed to confirm this finding. Trial registration number PROSPERO (CRD42021234581).

Peroxiredoxin AhpC1 protects Pseudomonas aeruginosa against the inflammatory oxidative burst and confers virulence.

Pseudomonas aeruginosa is an opportunistic bacterium in patients with cystic fibrosis and hospital acquired infections. It presents a plethora of virulence factors and antioxidant enzymes that help to subvert the immune system. In this study, we identified the 2-Cys peroxiredoxin, alkyl-hydroperoxide reductase C1 (AhpC1), as a relevant scavenger of oxidants generated during inflammatory oxidative burst and a mechanism of P. aeruginosa (PA14) escaping from killing. Deletion of AhpC1 led to a higher sensitivity to hypochlorous acid (HOCl, IC50 3.2 ± 0.3 versus 19.1 ± 0.2 µM), hydrogen peroxide (IC50 91.2 ± 0.3 versus 496.5 ± 6.4 µM) and the organic peroxide urate hydroperoxide. ΔahpC1 strain was more sensitive to the killing by isolated neutrophils and less virulent in a mice model of infection. All mice intranasally instilled with ΔahpC1 survived as long as they were monitored (15 days), whereas 100% wild-type and ΔahpC1 complemented with ahpC1 gene (ΔahpC1 attB:ahpC1) died within 3 days. A significantly lower number of colonies was detected in the lung and spleen of ΔahpC1-infected mice. Total leucocytes, neutrophils, myeloperoxidase activity, pro-inflammatory cytokines, nitrite production and lipid peroxidation were much lower in lungs or bronchoalveolar liquid of mice infected with ΔahpC1. Purified AhpC neutralized the inflammatory organic peroxide, urate hydroperoxide, at a rate constant of 2.3 ± 0.1 × 106 M-1s-1, and only the ΔahpC1 strain was sensitive to this oxidant. Incubation of neutrophils with uric acid, the urate hydroperoxide precursor, impaired neutrophil killing of wild-type but improved the killing of ΔahpC1. Hyperuricemic mice presented higher levels of serum cytokines and succumbed much faster to PA14 infection when compared to normouricemic mice. In summary, ΔahpC1 PA14 presented a lower virulence, which was attributed to a poorer ability to neutralize the oxidants generated by inflammatory oxidative burst, leading to a more efficient killing by the host. The enzyme is particularly relevant in detoxifying the newly reported inflammatory organic peroxide, urate hydroperoxide.

"Urate and NOX5 Control Blood Digestion in the Hematophagous Insect Rhodnius prolixus".

Low levels of reactive oxygen species (ROS) are now recognized as essential players in cell signaling. Here, we studied the role of two conserved enzymes involved in redox regulation that play a critical role in the control of ROS in the digestive physiology of a blood-sucking insect, the kissing bug Rhodnius prolixus. RNAi-mediated silencing of RpNOX5 and RpXDH induced early mortality in adult females after a blood meal. Recently, a role for RpNOX5 in gut motility was reported, and here, we show that midgut peristalsis is also under the control of RpXDH. Together with impaired peristalsis, silencing either genes impaired egg production and hemoglobin digestion, and decreased hemolymph urate titers. Ultrastructurally, the silencing of RpNOX5 or RpXDH affected midgut cells, changing the cells of blood-fed insects to a phenotype resembling the cells of unfed insects, suggesting that these genes work together in the control of blood digestion. Injection of either allopurinol (an XDH inhibitor) or uricase recapitulated the gene silencing effects, suggesting that urate itself is involved in the control of blood digestion. The silencing of each of these genes influenced the expression of the other gene in a complex way both in the unfed state and after a blood meal, revealing signaling crosstalk between them that influences redox metabolism and nitrogen excretion and plays a central role in the control of digestive physiology.

What is the diagnostic value of dual-energy computed tomography in patients with clinical diagnosis of gout?

Abstract Objectives: To investigate the frequency of monosodium urate (MSU) crystal deposits on dual-energy computed tomography (DECT) in patients with clinical diagnosis of gout and the factors associated MSU crystal positivity. Methods: This study was conducted in patients with clinical diagnosis of gout who underwent DECT. Clinical features were compared between patients with positive and those with negative DECT results. A logistic regression analysis was performed to determine the factors associated with MSU crystal positivity on DECT. Results: A total of 148 patients with clinical diagnosis of gout were included, and MSU crystal deposition on DECT was observed in 64 patients (43.3%). The patients with positive DECT results were more likely to have renal insufficiency, longer disease duration, and higher serum urate level than those with negative. In the multivariable analysis, first gout attack (odds ratio 0.462; 95% confidence interval 0.229-0.931, p = 0.031) was associated with a less likely MSU crystal deposit-positive DECT result. In the subgroup analysis of patients with first attack, serum urate level > 8 mg/dL was associated with DECT positivity. Conclusion: Of the patients with clinical diagnosis of gout, those with renal insufficiency, longer disease duration, and high serum urate level were more likely to be positive of gout on DECT. First gout attack was associated with less likely to be positive for MSU crystal on DECT. Thus, performing DECT scan in the selected patients who had characteristics that highly probability of DECT positivity could increase positive predictive value.

Visceral gout in coastal and oceanic seabirds in Paraná, Southern of Brazil

Background: Owing to the abundance, wide distribution, long life cycles and higher positions in the trophic levels, seabirds are considered sentinels of hazards and negative anthropogenic impacts to marine ecosystems. Gout is a common disease affecting birds, but also occurs in other taxa, including mammals and reptiles. The aim of this study was to elucidate the occurrence and pathological findings of gout cases in different species of seabirds, including biological and ecological factors that may contribute to disease. Cases: The urate crystals were observed in ten seabirds stranded, classified in eight species: four oceanic species two Puffinus puffinus, one Macronectis giganteus, one Thalassarche melanophris, one Calonectris sp. and four coastal species - one Fregata magnifiscens, two Sula leucogaster, one Phalacrocorax brasilianus and one Rynchops niger. A total of seven animals were stranded alive and three were found dead; four animals were male and six were female; six were juveniles and four were mature. The nutritional condition was cachectic in four animals, poor in five and fair in one. The main clinical sign in alive animals was dehydration (7/7; 100%). The treatment consisted of standard support including fluid therapy and temperature stabilization; in addition, vitamins, amino acids, minerals and antibiotics (sulfonamide or enrofloxacin) were given, but the animals died between 1 and 13 days after rehabilitation entrance. Gout was associated with cachectic condition and autumn stranding (in comparison with summer stranding). The main macroscopic findings were observed in the kidneys, which were whitish and enlarged and all had microscopic evidence of multifocal, mild to marked renal crystal urate deposition. In two cases, urates deposition were observed…(AU)

Visceral gout in coastal and oceanic seabirds in Paraná, Southern of Brazil

Background: Owing to the abundance, wide distribution, long life cycles and higher positions in the trophic levels, seabirds are considered sentinels of hazards and negative anthropogenic impacts to marine ecosystems. Gout is a common disease affecting birds, but also occurs in other taxa, including mammals and reptiles. The aim of this study was to elucidate the occurrence and pathological findings of gout cases in different species of seabirds, including biological and ecological factors that may contribute to disease. Cases: The urate crystals were observed in ten seabirds stranded, classified in eight species: four oceanic species – two Puffinus puffinus, one Macronectis giganteus, one Thalassarche melanophris, one Calonectris sp. and four coastal species - one Fregata magnifiscens, two Sula leucogaster, one Phalacrocorax brasilianus and one Rynchops niger. A total of seven animals were stranded alive and three were found dead; four animals were male and six were female; six were juveniles and four were mature. The nutritional condition was cachectic in four animals, poor in five and fair in one. The main clinical sign in alive animals was dehydration (7/7; 100%). The treatment consisted of standard support including fluid therapy and temperature stabilization; in addition, vitamins, amino acids, minerals and antibiotics (sulfonamide or enrofloxacin) were given, but the animals died between 1 and 13 days after rehabilitation entrance. Gout was associated with cachectic condition and autumn stranding (in comparison with summer stranding). The main macroscopic findings were observed in the kidneys, which were whitish and enlarged and all had microscopic evidence of multifocal, mild to marked renal crystal urate deposition. In two cases, urates deposition were observed

Urate hydroperoxide oxidizes endothelial cell surface protein disulfide isomerase-A1 and impairs adherence.

BACKGROUND: Extracellular surface protein disulfide isomerase-A1 (PDI) is involved in platelet aggregation, thrombus formation and vascular remodeling. PDI performs redox exchange with client proteins and, hence, its oxidation by extracellular molecules might alter protein function and cell response. In this study, we investigated PDI oxidation by urate hydroperoxide, a newly-described oxidant that is generated through uric acid oxidation by peroxidases, with a putative role in vascular inflammation. METHODS: Amino acids specificity and kinetics of PDI oxidation by urate hydroperoxide was evaluated by LC-MS/MS and by stopped-flow. Oxidation of cell surface PDI and other thiol-proteins from HUVECs was identified using impermeable alkylating reagents. Oxidation of intracellular GSH and GSSG was evaluated with specific LC-MS/MS techniques. Cell adherence, detachment and viability were assessed using crystal violet staining, cellular microscopy and LDH activity, respectively. RESULTS: Urate hydroperoxide specifically oxidized cysteine residues from catalytic sites of recombinant PDI with a rate constant of 6 × 103 M-1 s-1. Incubation of HUVECs with urate hydroperoxide led to oxidation of cell surface PDI and other unidentified cell surface thiol-proteins. Cell adherence to fibronectin coated plates was impaired by urate hydroperoxide, as well as by other oxidants, thiol alkylating agents and PDI inhibitors. Urate hydroperoxide did not affect cell viability but significantly decreased GSH/GSSG ratio. CONCLUSIONS: Our results demonstrated that urate hydroperoxide affects thiol-oxidation of PDI and other cell surface proteins, impairing cellular adherence. GENERAL SIGNIFICANCE: These findings could contribute to a better understanding of the mechanism by which uric acid affects endothelial cell function and vascular homeostasis.

Hypouricemia: what the practicing rheumatologist should know about this condition.

We presented an update in the field of hypouricemia, which is defined as a serum urate concentration of < 2 mg/dL (119 µmol/L), for the practicing rheumatologist, who usually is the consulting physician in cases of disorders of urate metabolism. We performed a narrative review through a literature search for original and review articles in the field of human hypouricemia published between January 1950 and July 2018. We divided the etiology of hypouricemia into two main categories: those associated with a decrease in urate production and those promoting the elimination of urate via the kidneys. The most common conditions associated with these categories are discussed. Furthermore, the etiology of hypouricemia may be associated with certain medications prescribed by the practicing rheumatologists, such as the following: urate-lowering drugs (allopurinol and febuxostat); recombinant uricase (pegloticase); uricosuric agents (probenecid, benzbromarone); urate transporter URAT1 inhibitor (lesinurad); angiotensin II receptor blocker (losartan); fenofibrate; high-dose trimethoprim-sulfamethoxazole; some NSAID; and high-dose salicylate therapy. The rheumatologist is considered an expert in the metabolism of urate and its associated pathological conditions. Therefore, specialists must recognize hypouricemia as a biomarker of various pathological and potentially harmful conditions, highlighting the importance of conducting a deeper clinical investigation to reach a more accurate diagnosis and treatment.

Are Target Urate and Remission Possible in Severe Gout? A Five-year Cohort Study.

OBJECTIVE: Determine the proportion of patients achieving target serum urate (SU), defined as < 6 mg/dl for patients with non-severe gout and < 5 mg/dl for patients with severe gout, as well as the proportion of patients achieving remission after 5 years of followup. METHODS: Patients from the Gout Study Group (GRESGO) cohort were evaluated at 6-month intervals. Demographic and clinical data were obtained at baseline. Visits included assessments of serum urate, flares, tophus burden, health-related quality of life using the EQ-5D, activity limitations using the Health Assessment Questionnaire adapted for gout, and pain level and patient's global assessment using visual analog scales. Treatment for gout and associated diseases was prescribed according to guidelines and available drugs. RESULTS: Of 500 patients studied, 221 had severe gout (44%) and 279 had non-severe gout (56%) at baseline. No significant differences were observed across the study in percentages of severe gout versus non-severe gout patients achieving SU 6 mg/dl or 5 mg/dl. The highest proportion of patients achieving target SU (50-70%) and remission (39%) were found after 3-4 years of followup. In the fifth year, these proportions decreased and 28% of the patients were in remission, but only 40 patients remained in the study. None of the patients with severe gout achieved remission. CONCLUSION: In patients with severe gout, target SU was hard to achieve and remission was not possible. The main obstacles for target SU and gout remission include poor medication adherence, persistent tophi, and loss to followup.

Simultaneous use of oxalate-degrading bacteria and herbal extract to reduce the urinary oxalate in a rat model: A new strategy

ABSTRACT Objective: Urinary stones with oxalate composition can cause kidney failure. Recent findings evidenced that probiotics are effective in reducing oxalate absorption in these subjects based on their high colonic absorption levels at baseline. The purpose of this study was to evaluate the effect of the simultaneous use of oxalate-degrading bacteria, Urtica dioica and T. terrestris extract in reducing urinary oxalate. Materials and Methods: Anti-urolithiatic activity of Urtica dioica and T. terrestris extract and probiotic by using ethylene glycol induced rat model. In this study, 4 strains of Lactobacillus and 2 strains of Bifidobacterium and also 2 strains of L. paracasei (that showed high power in oxalate degrading in culture media) were used. Male Wistar rats were divided into four groups (n=6). The rats of group-I received normal diet (positive control group) and groups-II (negative control group), III, IV rats received diet containing ethylene glycol (3%) for 30 days. Groups III rats received Urtica dioica and T. terrestris extract. Groups IV rats received extracts + probiotic for 30 days. Findings: The results show that the use of herbal extracts (Urtica dioica and T. terrestris) reduced the level of urinary oxalate and other parameters of urine and serum. Also, the accumulation of calcium oxalate crystals in the kidney tissue was significantly reduced. Conclusion: Considering that the formation of calcium oxalate crystals can cause inflammation and tissue damage in the kidney, the use of herbal extracts with oxalate degrading bacteria can be a new therapeutic approach to preventing the formation of kidney stones.

Allantoin reduces cell death induced by cisplatin: possible implications for tumor lysis syndrome management.

Massive lysis of tumor mass in cancer patients under chemotherapy regimens generates high levels of uric acid, leading to what is known as tumor lysis syndrome (TLS). Rasburicase, a recombinant urate oxidase, converts urate to allantoin, which is readily excreted by the kidneys. Even though there is a high production of allantoin from urate in cancer patients following rasburicase treatment, there are no studies on how allantoin excess could interfere with chemotherapy. We have evaluated allantoin interference with cisplatin efficiency on the lung cancer cell line H460 in vitro. The cells were treated with cisplatin (33 µM), with or without allantoin, for 48 h, in the presence or absence of UV light, and N-acetyl-L-cysteine (NAC) for 24 h. Cell viability, cell cycle, ROS production, apoptosis and immunoblot assays were performed. We showed that allantoin reduced the apoptosis induced by cisplatin in the H460 cell line. However, the activity of carboplatin and oxaliplatin, betulinic acid, TIBA, UV and H2O2 was not affected by allantoin. NMR spectroscopy showed that allantoin reduces cisplatin activity through direct interaction with cisplatin.

Silibinin Downregulates the NF-κB Pathway and NLRP1/NLRP3 Inflammasomes in Monocytes from Pregnant Women with Preeclampsia.

Preeclampsia (PE) is a human pregnancy-specific syndrome with abnormal activation of cells from the innate immune system. The present study evaluated whether silibinin (SB) treatment of monocytes from preeclamptic women could modulate NLRP1 and NLRP3 inflammasomes as well as TLR4/NF-κB pathway activation. Peripheral blood monocytes from 20 preeclamptic and 20 normotensive (NT) pregnant women, as well as the THP-1 cell line, were cultured with or without monosodium urate (MSU) or SB. NLRP1, NLRP3, Caspase-1, TLR4, MyD88, NF-κB, IL-1ß, IL-18, TNF-α and IL-10 gene expression by monocytes was analysed by quantitative real-time polymerase chain reaction (qPCR), while inflammatory cytokine production and p65NF-κB activity were determined by enzyme-linked immunosorbent assays (ELISAs). TLR4/MyD88/NF-κB and NLRP1/NLRP3 inflammasomes pathways in THP-1 cells were evaluated by flow cytometry and western blot respectively. Compared with NT women, monocytes from preeclamptic women showed The Ethics Committee of the Botucatu Medical School approved the study (protocol number 2.333.216)higher endogenous activation of NLRP1/NLRP3 inflammasomes and the TLR4/NF-κB pathway as well as higher gene and protein expression of IL-1ß, IL-18 and TNF-α, and lower expression of IL-10. Monocyte stimulation with MSU increased inflammation-related genes as well as NF-κB activity. In vitro, SB treatment of monocytes from preeclamptic women reduced the basal activation of these cells by decreasing NLRP1/NLRP3 inflammasomes and p65NF-κB activity. THP-1 cells exhibited a similar immunological response profile to monocytes from preeclamptic women when cultured with or without MSU or SB. These results suggest uric acid participates in the systemic inflammatory response characteristic of preeclampsia and that in vitro SB treatment can modulate the sterile inflammation established in monocytes from preeclamptic women.