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.

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.

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

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)

Quercetin inhibits gout arthritis in mice: induction of an opioid-dependent regulation of inflammasome.

We investigated the anti-inflammatory and analgesic effects of quercetin in monosodium urate crystals (MSU)-induced gout arthritis, and the sensitivity of quercetin effects to naloxone, an opioid receptor antagonist. Mice were treated with quercetin, and mechanical hyperalgesia was assessed at 1-24 h after MSU injection. In vivo, leukocyte recruitment, cytokine levels, oxidative stress, NFκB activation, and gp91phox and inflammasome components (NLRP3, ASC, Pro-caspase-1, and Pro-IL-1ß) mRNA expression by qPCR were determined in the knee joints at 24 h after MSU injection. Inflammasome activation was determined, in vitro, in lipopolysaccharide-primed macrophages challenged with MSU. Quercetin inhibited MSU-induced mechanical hyperalgesia, leukocyte recruitment, TNFα and IL-1ß production, superoxide anion production, inflammasome activation, decrease of antioxidants levels, NFκB activation, and inflammasome components mRNA expression. Naloxone pre-treatment prevented all the inhibitory effects of quercetin over MSU-induced gout arthritis. These results demonstrate that quercetin exerts analgesic and anti-inflammatory effect in the MSU-induced arthritis in a naloxone-sensitive manner.

Neutrophil Extracellular Traps Stimulate Proinflammatory Responses in Human Airway Epithelial Cells.

Tissue injury leads to the release of uric acid (UA). At high local concentrations, UA can form monosodium urate crystals (MSU). MSU and UA stimulate neutrophils to release extracellular traps (NET). Here, we investigated whether these NET could be involved in the development of inflammation by stimulating cytokine release by airway epithelial cells. We found that NET significantly increased the secretion of CXCL8/IL-8 and IL-6 by alveolar and bronchial epithelial cells. These effects were not observed when NETosis was inhibited by Diphenyleneiodonium, elastase inhibitor, or Cl-amidine. Similar findings were made with NET induced by cigarette smoke extract, suggesting that NET proinflammatory capacity is independent of the inducing stimulus. Furthermore, NET affected neither the viability and morphology of epithelial cells nor the barrier integrity of polarized cells. The epithelial stimulatory capacity of NET was not affected by degradation of DNA with micrococcal nuclease, treatment with heparin, or inhibition of the elastase immobilized to DNA, but it was significantly reduced by pretreatment with an anti-HMGB-1 blocking antibody. Altogether, our findings indicate that NET exert direct proinflammatory effects on airway epithelial cells that might contribute in vivo to the further recruitment of neutrophils and the perpetuation of inflammation upon lung tissue damage.

Monosodium urate crystals induce oxidative stress in human synoviocytes.

BACKGROUND: Gout is the most common inflammatory arthropathy of metabolic origin and it is characterized by intense inflammation, the underlying mechanisms of which are unknown. The aim of this study was to evaluate the oxidative stress in human fibroblast-like synoviocytes (FLS) exposed to monosodium urate (MSU) crystals, which trigger an inflammatory process. METHODS: Human FLS isolated from synovial tissue explants were stimulated with MSU crystals (75 µg/mL) for 24 h. Cellular viability was evaluated by crystal violet staining, apoptosis was assessed using Annexin V, and the cellular content of reactive oxygen species (ROS) and nitrogen species (RNS) (O2 (-), H2O2, NO) was assessed with image-based cytometry and fluorometric methods. In order to determine protein oxidation levels, protein carbonyls were detected through oxyblot analysis, and cell ultrastructural changes were assessed by transmission electron microscopy. RESULTS: The viability of FLS exposed to MSU crystals decreased by 30 % (P < 0.05), while apoptosis increased by 42 % (P = 0.01). FLS stimulated with MSU crystals exhibited a 2.1-fold increase in H2O2 content and a 1.5-fold increase in O2 (-) and NO levels. Oxyblots revealed that the spots obtained from FLS protein lysates exposed to MSU crystals exhibited protein carbonyl immunoreactivity, which reflects the presence of oxidatively modified proteins. Concomitantly, MSU crystals triggered the induction of changes in the morphostructure of FLS, such as the thickening and discontinuity of the endoplasmic reticulum, and the formation of vacuoles and misfolded glycoproteins. CONCLUSIONS: Our results prove that MSU crystals induce the release of ROS and RNS in FLS, subsequently oxidizing proteins and altering the cellular oxidative state of the endoplasmic reticulum, which results in FLS apoptosis.

Molecular basis of oxidative stress in gouty arthropathy.

Gout is a disorder of urate metabolism in which persistent high urate levels in the extracellular fluids result in the deposition of monosodium urate (MSU) crystal in joints and periarticular tissues. In recent years, this disease represents an increasingly common health problem, so the pace of investigation in the field has accelerated tremendously. New research advances in the pathogenesis of hyperuricemia and in the understanding of how MSU crystals induce an acute gouty attack have been focused in this review on the processes of inflammation and involvement of the innate immune response; in addition, we discuss new knowledge about the role of the reactive oxygen species in establishing oxidative stress in MSU crystal-induced arthritis.