Gout. Novel therapies for treatment of gout and hyperuricemia

Simple assay for quantifying xanthine oxidase activity

This paper reports a sensitive method for assaying xanthine oxidase (XO) enzyme activity. XO produces hydrogen peroxide (H₂O₂) and superoxide anion radicals (O₂^•-), promoting the development of oxidative stress-related diseases, and is inhibited by various plant extracts. XO activity is quantified by incubating enzyme samples with an appropriate xanthine concentration as the substrate. The proposed method requires XO activity to be quantified based on H₂O₂ generation using a 3,3',5,5'-tetramethylbenzidine (TMB)-H₂O₂ system catalyzed by cupric ions. After a 30-minute incubation at 37 °C, sufficient cupric ion and TMB amounts are added. The assay produces optical signals that can be visually recognized or detected with a UV-visible spectrometer. A direct correlation was found between XO activity and the absorbance at 450 nm of the resulting di-imine (dication) yellow product. The proposed method uses sodium azide to prevent catalase enzyme interference. The new assay's function was confirmed using the TMB-XO assay and a Bland-Altman plot. The resulting correlation coefficient was 0.9976. The innovative assay was relatively precise and comparable to the comparison protocols. In conclusion, the presented method is very efficient at measuring XO activity.

Carvacrol Alleviates Hyperuricemia-Induced Oxidative Stress and Inflammation by Modulating the NLRP3/NF-κB Pathwayt

Purpose

Gouty arthritis is generally induced by the accumulation of monosodium urate (MSU) crystals in the joints due to elevated serum uric acid levels, potentially leading to serious pathological disorders such as nephrolithiasis, renal failure, and acute gouty arthritis. In this study, we aimed to validate the anti-gout effects of carvacrol, a phenolic monoterpene.

Materials and Methods

Male Sprague–Dawley rats were divided into normal saline, disease group by injecting potassium mono-oxonate (PO) at a dose of 250 mg/kg, and three treatment groups, either with carvacrol 20 mg/kg or 50 mg/kg and 10 mg/kg allopurinol. The blood and tissue samples were subsequently collected and analyzed using different biochemical and histopathological techniques.

Results

Our results revealed a significant increase in the serum levels of oxidative stress-related markers, namely, uric acid and C-reactive protein (CRP), and NLRP3 inflammasome-dependent inflammatory mediators, including nuclear factor kappa B (NF-κB) and tumor necrosis factor-alpha (TNF-α). Carvacrol administration for seven consecutive days exhibited significant anti-hyperuricemic and anti-inflammatory effects in a dose-dependent manner. Notably, the 50 mg/kg carvacrol treatment was observed to produce results similar to the allopurinol treatment. Furthermore, the renal safety of carvacrol was confirmed by the renal function test.

Conclusion

Carvacrol potentially alleviates hyperuricemia-induced oxidative stress and inflammation by regulating the ROS/NRLP3/NF-κB pathway, thereby exerting protective effects against joint degeneration.

Sonneratia apetala seed oil attenuates potassium oxonate/hypoxanthine-induced hyperuricemia and renal injury in mice

Sonneratia apetala seeds are considered as prospective nutraceuticals with a high content of unsaturated fatty acids (UFAs) which are mainly distributed in the oil. It is well-known that UFAs could exhibit urate-lowering potency and protect against renal injury, indicating that S. apetala seed oil (SSO) may possess hypouricemic and nephroprotective effects. Consequently, the present work attempted to probe into the effects and mechanisms of SSO on potassium oxonate/hypoxanthine-induced hyperuricemia and associated renal injury. The results indicated that SSO treatment prominently inhibited the increase of serum uric acid (UA), creatinine (CRE), and urea nitrogen (BUN) levels and hepatic xanthine oxidase (XOD) activity in hyperuricemia mice. Kidney indexes and histopathological lesions were also remarkably ameliorated. Additionally, SSO treatment improved the renal anti-oxidant status in hyperuricemia mice by significantly reversing the increase in ROS and MDA levels as well as the decline in SOD, CAT and GSH-Px activities. SSO dramatically downregulated the expression and secretion of pro-inflammatory factors involving MCP-1, IL-1β, IL-6, IL-18 and TNF-α elicited by hyperuricemia. Furthermore, after SSO treatment, increased protein expressions of GLUT9, URAT1 and OAT1 in the hyperuricemia mice were obviously reversed. SSO treatment enormously restored Nrf2 activation and subsequent translation of related anti-oxidative enzymes in the kidneys. TXNIP/NLRP3 inflammasome activation was also obviously suppressed by SSO. In conclusion, SSO exerted favorable hypouricemic effects owing to its dual functions of downregulating the XOD activity and modulating the expressions of renal urate transport-associated proteins, and it also could alleviate hyperuricemia-induced renal injury by restoring the Keap1-Nrf2 pathway and blocking the TXNIP/NLRP3 inflammasome activation.

Dosage individualization proposed for anti-gout medications among the patients with gout

BACKGROUND

The conventional one-size-fits-all approach has been criticized for almost all drugs used especially for chronic diseases, including gout. The present study was aimed to explore the need of individualization and optimization of the dose of anti-gout medications among gout patients.

METHODS

Cross-sectional study was carried out among 384 randomly selected new gout patients visiting two gout treatment centers at Lalitpur Metropolitan City, Nepal and who were taking antigout medications. Patients not taking anti-gout medications and not showing willingness to participate were excluded. The eGFR was calculated with the CKD Epidemiology Collaboration (CKD-EPI) creatinine equation (2009). Doses to be individualized were decided based on the Renal Drug Handbook and verified with the BNF 80. Data were analyzed via R 4.0.3 by applying the multinomial logistic regression to analyze statistical significance of risk with various predictors, and considering a p-value <0.05 statistically significant. Comorbidities were coded as per the ICD-11 coding and medicines were coded according to the WHO Guidelines for ATC classification and DDD assignment 2020.

RESULTS

The high risk of progression to CKD increased in the age range 54-63 and ≥84 years by 17.77 and 43.02 times, respectively. Also, high risk increased by 29.83 and 20.2 times for the overweight and the obese respectively. Aceclofenac 100mg was prescribed for maximum patients (30.5%). Need of dose individualization was realized in 30 patients, with maximum (7) in case of etoricoxib 90mg. Various glucocorticoids were prescribed for 36.9% patients, out of whom 3.8%required dose individualization and 15.9% patients with xanthine oxidase inhibitors, out of whom 1.3% required dose individualization.

CONCLUSION

Thirty cases required dose individualization, which was although minimal but could have meaningful impact on the clinical success of the individual patient. Based on the recommendation on dose individualization, those patients could be optimized on their therapy on future follow ups.

Individualized homeopathic medicines and Urtica urens mother tincture in treatment of hyperuricemia: an open, randomized, pragmatic, pilot trial

OBJECTIVES

The quality of management of hyperuricemia has remained sub-optimal owing to unavoidable toxicities, limitations, and dearth of novel advances. Homeopathy has remained under-researched in hyperuricemia. We investigated the clinical effectiveness of three treatment regimens - individualized homeopathy (IH), Urtica urens mother tincture (UUMT), and both (IH + UUMT) along with lifestyle modifications in a sample of 90 patients with hyperuricemia.

METHODS

An open, randomized (1:1:1), 3 parallel arms (IH, UUMT, and IH + UUMT), pragmatic trial was conducted at National Institute of Homoeopathy, Kolkata. Outcome measures were serum uric acid (primary), Gout Assessment Questionnaire version 2 (GAQ2, secondary), and Measure Yourself Medical Outcome Profile version 2 (MYMOP2, secondary); all measured at baseline, and after 3 and 6 months. Intention- to-treat sample was analyzed to detect group differences by unpaired t tests.

RESULTS

Attrition rate was 8.9% (IH: 3, UUMT: 3, IH + UUMT: 2). Groups were comparable at baseline. Reductions in serum uric acid over 3 months were comparatively higher (p=0.057) in the UUMT group than others, however, the differences were narrowed over 6 months (p=0.119). Per protocol analysis of serum uric acid level revealed similar trend of significantly higher reduction in the UUMT group than the other two (3 months: p=0.001; 6 months: p=0.007). No significant differences existed in reductions of GAQ2 scores among the three groups. Few significant differences were detected in MYMOP scores over 3 months favoring IH against others (symptom 2, p=0.001 and wellbeing score, p=0.002), and also over 6 months favoring IH + UUMT against others (symptom 1, p<0.001).

CONCLUSION

Although all three therapies showed similar improvements, the IH + UUMT group had more positive direction of effects than IH or UUMT alone; however, no definite conclusion could be arrived at. Further trials are warranted with larger sample size. Trial registration: CTRI/2018/05/014026.

Coxsackievirus A6-induced Hand-Foot-and-Mouth Disease Mimicking Stevens-Johnson Syndrome in an Immunocompetent Adult

Hand-foot-and-mouth disease, a highly contagious viral infection, occurs more common in children than in adults. However, there was a recent outbreak of Coxsackievirus A6-induced infection with an atypical presentation among the adult population. Stevens–Johnson syndrome is a severe mucocutaneous disease characterized by extensive necrosis and detachment of the epidermis, and this condition is commonly caused by medications. Herein, we describe a 30-year-old male patient taking allopurinol for the management of gout. The patient presented with numerous erythematous papules, vesicles, and patches with mucosal eruptions on the whole body, oral mucositis, and fever, and he was finally diagnosed with hand-foot-and-mouth disease.

Construction and expression of recombinant uricase‑expressing genetically engineered bacteria and its application in rat model of hyperuricemia

At present, the treatment of hyperuricemia is designed primarily to decrease the production of uric acid using xanthine oxidase inhibitors; however, the therapeutic effect is not satisfactory. Therefore, the key to the successful treatment of hyperuricemia is to increase the excretion of uric acid. The aim of present study was to construct uricase-expressing genetically engineered bacteria and analyze the effects of these engineered bacteria on the lowering of uric acid levels in a rat model of hyperuricemia. The uricase expression vector was constructed by gene recombination technology and transfected into Escherichia coli. The expression and activity of uricase were analyzed by SDS-PAGE analysis and Bradford assay. The water consumption, food intake, body weight, eosinophil count and intestinal histology, in addition to the levels of serum uric acid (SUA) and allantoin in the feces of the rats, were assessed. The intestinal contents of the rats were analyzed by 16S rDNA sequencing technology. The results demonstrated that uricase-expressing genetically engineered bacteria secreted active uricase. All rats exhibited a natural growth trend during the entire experiment, and the SUA of hyperuricemic rats treated with uricase-expressing engineered bacteria was significantly decreased. In conclusion, these results indicate that uricase secreted by recombinant uricase-expressing genetically engineered bacteria served an important role in decreasing SUA levels in a rat model of hyperuricemia.

N-Butyrylated hyaluronic acid ameliorates gout and hyperuricemia in animal models

Context: Hyaluronic acid (HA) plays critical roles in the structural skeleton, joint lubrication, renal function and cell signaling. We previously showed that partially N-butyrylated, low molecular weight, hyaluronic acid (BHA) exhibited an anti-inflammatory effect in cultured human macrophage, where inflammation was induced either by a TL-4 agonist or the low molecular weight HA itself, in dose-dependent fashion. Objectives: To investigate the anti-inflammatory, antioxidative, and antihyperuricemic effects of BHA using animal models of acute gouty arthritis and hyperuricemia. Materials and methods: The anti-inflammatory effect of articular BHA (10 and 50 μg) injections was evaluated by measuring joint swelling and the serum levels of inflammatory cytokines in a model of acute gouty arthritis induced by intra-articular injection of monosodium urate crystals in Wistar rats (n = 10/group), in comparison to the control group with saline injection. Antioxidative and antihyperuricemic activities were investigated using intraperitoneal injections of oteracil potassium and yeast extract hyperuricemic Balb/C mice, which were treated with intraperitoneal injection of BHA at day 6-8 in the model. Results: In the gouty arthritis rat model, BHA at a higher dosage (50 μg) demonstrated a strong anti-inflammatory effect by reducing the degree of articular swelling and the serum levels of IL-1β, IL-8, IFN-γ, and MCP-1 by 5.56%, 6.55%, 15.58% and 33.18%. In the hyperuricemic mouse model, lower dosage BHA (10 μg) was sufficient to provide antioxidative activities by significantly decreasing the ROS levels in both serum and liver by 14.87% and 8.04%, while improving liver SOD by 12.77%. Intraperitoneal injection of BHA suppressed uric acid production through reducing liver XO activity by 19.78% and decreased the serum uric acid level in hyperuricemic mice by 30.41%. Conclusions: This study demonstrated for the first time that BHA exhibits anti-inflammatory, antioxidative and antihyperuricemic effects in vivo, suggesting a potential therapeutic application of BHA in gouty arthritis and hyperuricemia.

The association between serum uric acid level and changes of MRI findings in knee osteoarthritis: A retrospective study (A STROBE-compliant article)

The objective of this study was to examine whether Magnetic resonance imaging (MRI) features of knee osteoarthritis (OA) had an association with the level of serum uric acid (SUA). The MRI of the OA patients from June 2015 to July 2017 were studied. The patients fulfilled the following inclusion criteria: 1) meet American College of Rheumatology (ACR) radiological and clinical criteria for OA of the knee, 2) age ≤ 65years old, 3) Body mass index (BMI) < 25 kg/m. Patients with OA were categorized into two groups based on the level of SUA. Patients with SUA level lower than 360 umol/L were recruited into the first group and the others were the second group. Odds ratios (OR) and 95% confidence intervals (CI) for SUA level and different MRI patterns were estimated with multivariable logistic regression.71 patients were included in this research. The mean age of the first group was 54.5 ± 8.4 and the second group was 55.6 ± 6.4. The Body Mass Index (BMI) of two groups was 22.7 ± 1.3 and 23.23 ± 1.9 separately. The mean SUA and creatinine (CR) level of the second group were 433.8 ± 70.6 umol/L and 80.1 ± 23.9 umol/L. There were statistically more focal erosions, osteophytes, bone marrow lesions and synovitis in the MRIs of the second group. A positive association between SUA level and synovitis as well as soft tissue swelling in MRIs was observed in patients with knee OA (OR = 1.017; 1.008, 95% CI: 1.007-1.028; 1.000-1.016). In conclusion, subjects with higher SUA level were more likely to have MRI abnormalities. OA patients need to lower their SUA level in order to keep the disease from progressing.

Protective effects of luteolin on injury induced inflammation through reduction of tissue uric acid and pro-inflammatory cytokines in rats

Background and aim

Luteolin belongs to flavone group of flavonoids, present in many plants with potent antioxidant, anti-inflammatory and anti-proliferative effects. The objective of present study was to investigate protective effect of luteolin on injury induced inflammation via Monosodium urate (MSU) crystals induced and Acetaminophen (AMP) induced liver injury in rats.

Experimental procedure

Protective effect of luteolin was observed by measurement of rat paw edema, lysosomal enzymes, antioxidants status and cytokine level. Measurement of uric acid level and neutrophil infiltration were done in AMP induced liver injury in rats. Luteolin was tested at 30 and 50 mg/kg doses and compare with colchicine.

Results and conclusion

Luteolin significantly decreases paw edema in dose dependent manner compare to control group in MSU crystal-induced rats. Luteolin (50 mg/kg) was showed significant decrease in serum level of oxidative and lysosomal enzymes, proinflammatory cytokines i.e. tumor necrosis factor (TNF)-α (39.28 ± 3.17), interleukin (IL)-1β (12.07 ± 1.24), and IL-6 (24.72 ± 2.52) in MSU crystal-induced rats. In AMP induced liver injury, tissue uric acid level and myeloperoxidase were decreased significantly after treatment with luteolin as well as N-acetylcysteine. Serum level of liver enzymes was significantly reduced after treatment with luteolin. Histological observation of ankle joints and liver was support to protective effect of luteolin at both doses. In conclusion, luteolin showed anti-inflammatory effect through restoration of cytokine level, lysosomal enzymes level and antioxidants status. The reduction of liver tissue uric acid content may be one of the mechanisms for protective effect of luteolin. It can contribute to reduce injury induced inflammation.

Emergent nanotherapies in microcrystal-induced arthritis

The anti-inflammatory and immunomodulatory effects of nanoparticles in several chronic diseases have been extensively researched. The aim of this review is to examine how nanoparticles modulate the inflammatory pathways that characterize the most prevalent forms of microcrystal-induced arthritis, including gout, pseudogout, and BCP-induced arthritis. The nanoparticles of chitosan-coated calcium phosphate, uricase, aceclofenac, and gold have been investigated in crystal-inducedarthritis. The most important results of the studies outlined in this review show that nanoparticles can inhibit the expression and the release of some pro-inflammatory mediators and proteolytic enzymes, and the activity of different transcriptional factors in vitro, as well as decrease the uric acid levels in several studies of in vitro and in vivo models of gout, which show interesting results in terms of decreasing the amount of crystals and tissue damage, respectively. In view of their multiple beneficial effects, nanoparticles can be considered a valuable therapy that contributes to the pharmacological treatment in crystalinduced arthritis.

Optimization of novel and greener approach for the coproduction of uricase and alkaline protease in Bacillus licheniformis by Box-Behnken model

This study explores a novel concept of coproduction of uricase and alkaline protease by Bacillus licheniformis using single substrate in single step. Seven local bacterial strains were screened for uricase production, amongst which B. licheniformis is found to produce highest uricase along with alkaline protease. Optimization of various factors influencing maximum enzyme coproduction by B. licheniformis is performed. Maximum enzyme productivity of 0.386 U/mL uricase and 0.507 U/mL alkaline protease is obtained at 8 hr of incubation period, 1% (v/v) inoculum, and at 0.2% (w/v) uric acid when the organism is cultivated at 25°C, 180 rpm, in a media containing xylose as a carbon source, urea as a nitrogen source, and initial pH of 9.5. The statistical experimental design method of Box-Behnken was further applied to obtain optimal concentration of significant parameters such as pH (9.5), uric acid concentration (0.1%), and urea concentration (0.05%). The maximum uricase and alkaline protease production by B. licheniformis using Box-Behnken design was 0.616 and 0.582 U/mL, respectively, with 1.6- and 1.13-fold increase as compared to one factor at a time optimized media. This study will be useful to develop an economic, commercially viable, and scalable process for simultaneous production of uricase and protease enzymes.

Antihyperuricemic effect of liquiritigenin in potassium oxonate-induced hyperuricemic rats

The aim is to investigate the anti-hyperuricemic and renal protective effects of liquiritigenin in potassium oxonate-induced hyperuricemic rats. Hyperuricemia in rats was induced were induced with potassium oxonate (250mg/kg) intragastrically for 7 days, and liquiritigenin (20, 40mg/kg) and allopurinol (5mg/kg) were daily administrated to the rats orally 1h after the potassium oxonate exposure. Liquiritigenin significantly reversed the elevated productions of uric acid in serum and urine and pro-inflammation cytokines in serum and kidney, which shown that liquiritigenin has renal protective effects. Histological study shows that liquiritigenin inhibited severe necrosis and inflammatory cell infiltration in potassium oxonate-treated rats. Furthermore, liquiritigenin mediated the activities of aquaporins 4 (AQP4), and regulated the activation of NF-κB p65 and the degradation of IκBα. Finally, significant increases of nod-like receptor protein 3 (NLRP3) inflammasome, apoptosis-associated speck-like protein adaptor (ASC) adaptor and cleaved caspased-1 were restored by liquiritigenin. Therefore, liquiritigenin might improve renal inflammation by suppressing renal AQP4/NF-κB/IκBα and NLRP3 inflammasome activation in hyperuricemic rats.

Functional and Structural Characterization of Purine Nucleoside Phosphorylase from Kluyveromyces lactis and Its Potential Applications in Reducing Purine Content in Food

Consumption of foods and beverages with high purine content increases the risk of hyperuricemia, which causes gout and can lead to cardiovascular, renal, and other metabolic disorders. As patients often find dietary restrictions challenging, enzymatically lowering purine content in popular foods and beverages offers a safe and attractive strategy to control hyperuricemia. Here, we report structurally and functionally characterized purine nucleoside phosphorylase (PNP) from Kluyveromyces lactis (KlacPNP), a key enzyme involved in the purine degradation pathway. We report a 1.97 Å resolution crystal structure of homotrimeric KlacPNP with an intrinsically bound hypoxanthine in the active site. KlacPNP belongs to the nucleoside phosphorylase-I (NP-I) family, and it specifically utilizes 6-oxopurine substrates in the following order: inosine > guanosine > xanthosine, but is inactive towards adenosine. To engineer enzymes with broad substrate specificity, we created two point variants, KlacPNP^N256D and KlacPNP^N256E, by replacing the catalytically active Asn256 with Asp and Glu, respectively, based on structural and comparative sequence analysis. KlacPNP^N256D not only displayed broad substrate specificity by utilizing both 6-oxopurines and 6-aminopurines in the order adenosine > inosine > xanthosine > guanosine, but also displayed reversal of substrate specificity. In contrast, KlacPNP^N256E was highly specific to inosine and could not utilize other tested substrates. Beer consumption is associated with increased risk of developing gout, owing to its high purine content. Here, we demonstrate that KlacPNP and KlacPNP^N256D could be used to catalyze a key reaction involved in lowering beer purine content. Biochemical properties of these enzymes such as activity across a wide pH range, optimum activity at about 25°C, and stability for months at about 8°C, make them suitable candidates for food and beverage industries. Since KlacPNP^N256D has broad substrate specificity, a combination of engineered KlacPNP and other enzymes involved in purine degradation could effectively lower the purine content in foods and beverages.

Gout Prophylaxis Evaluated According to the 2012 American College of Rheumatology Guidelines: Analysis from the CORRONA Gout Registry

OBJECTIVE

To analyze prophylaxis using the CORRONA (COnsortium of Rheumatology Researchers Of North America) Gout Registry according to the American College of Rheumatology (ACR) guidelines, and to evaluate whether differences in disease characteristics influenced prophylaxis.

METHODS

All patients with gout in the CORRONA Gout Registry between November 1, 2012, and November 26, 2013, were included. They were divided into 2 groups: "receiving prophylaxis" versus "not receiving prophylaxis" at the time of enrollment. Patients having a flare at time of visit were excluded. Descriptive statistics and multivariable logistic regression models were performed to evaluate the factors associated with prophylaxis.

RESULTS

There were 1049 patients with gout available for analysis. There were 441 patients (42%) receiving prophylaxis and 608 (58%) not receiving prophylaxis. The most common drugs used for prophylaxis were colchicine (78%) and nonsteroidal antiinflammatory drugs (32%). Prophylaxis drug combination was used by 45 patients (10.2%). Patients in the "receiving prophylaxis" group were more likely to have a gout duration of ≤ 1 year (n = 68, p < 0.001), ≥ 1 flare in the year previous to enrollment (p < 0.001), ≥ 1 healthcare uses in the last year [Emergency Department (p = 0.029); outpatient visit to primary care, rheumatologist, or urgent care clinic (p < 0.001)], have tophi (p < 0.001), report pain > 3 (p = 0.001), and have disease activity > 10 (p < 0.001) compared with patients in the "not receiving prophylaxis" group.

CONCLUSION

Forty-two percent of patients with gout in the CORRONA Gout Registry were receiving prophylaxis. Prophylaxis was significantly more common in patients with a higher disease burden and activity, which is in agreement with the ACR guidelines. Our study highlights disease characteristics influencing prophylaxis and furthers our knowledge on current use of flare prophylaxis.

Oral treatment with Bifidobacterium longum 51A reduced inflammation in a murine experimental model of gout

Gout is an acute inflammatory disease characterised by the presence of uric acid crystals in the joint. This event promotes neutrophil infiltration and activation that leads to tissue damage. We investigated here whether the oral administration of the probiotic strain Bifidobacterium longum 5(1A) (BL) could ameliorate monosodium urate crystal (MSU)-induced inflammation in a murine model of gout. Mice received oral administration of BL or saline daily for 7 days and then were injected with MSU in the knee cavity. Treatment with BL significantly alleviated the inflammatory parameters, as seen by reduced hypernociception, reduced neutrophil accumulation in the joint and myeloperoxidase activity in periarticular tissue. There was inhibition of the production of CXCL1 and interleukin(IL)-1β in joints. Levels of the anti-inflammatory cytokine IL-10 were significantly higher in the knee tissue of mice treated with than control mice injected with MSU. In conclusion, oral BL treatment reduced the inflammatory response in an experimental murine model of gout, suggesting it may be useful as an adjuvant treatment in patients with gout.

Protective Effects of Catechin against Monosodium Urate-Induced Inflammation through the Modulation of NLRP3 Inflammasome Activation

Gouty inflammation results from the stimulation of monosodium urate (MSU). Interleukin-1β (IL-1β) secretion is the primary clinical manifestation of MSU attack, and MSU activates IL-1β through a nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome. This study investigated the protective effect and underlying mechanism of naturally occurring phenolic compounds on MSU-induced inflammation in vivo and in vitro. A screening of phenolic compounds revealed that gallic acid and catechin exhibited the most potent free radical scavenging activities. Subcutaneous injection of gallic acid or catechin significantly reduced MSU-induced IL-1β and IL-6 secretion in C57BL/6 mice. However, only catechin inhibited MSU-induced IL-1β secretion and NLRP3 inflammasome activation in MSU-challenged THP-1 cells. MSU-triggered mitochondrial reactive oxygen species (MtROS) production and intracellular calcium levels were significantly decreased by treatment with catechin in THP-1 cells. Catechin treatment also up-regulated Bcl-2 levels and restored MSU-induced mitochondrial transmembrane potential impairment. These results indicate that the protective effects of catechin on MSU-induced IL-1β secretion are associated with modulation of mitochondrial damage. It also suggests that catechin has the potential to protect gout attack by modulation of NLRP3 inflammasome activation.

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.

Allopurinol, benzbromarone, or a combination in treating patients with gout: analysis of a series of outpatients

Objective. To profile a sample of gouty patients treated with allopurinol, benzbromarone, or a combination of these two drugs and to describe the impact of this therapy in reducing uric acid levels. Methods. An observational, transversal study was performed. We evaluated 48 patients diagnosed with gout who were seen at the Outpatient Rheumatology Clinic of the Federal University of Paraná between January 2009 and November 2010. Clinical data, creatinine serum levels, and basal and posttreatment levels of serum urates, transaminases, and bilirubins were recorded. Uric acid levels were measured in a 24-hour urine sample. Patients were divided into three groups: patients given only allopurinol (A), only benzbromarone (B), and both in combined therapy (A + B). Results. The average age of these patients was 56.6 ± 11.4 years, varying from 35 to 81 years. The entire patient group experienced a significant drop in serum urate levels, from 8.5 ± 1.8 mg/dL (0.472 ± 0.1 mmol/L) to 6.7 ± 2.1 mg/dL (0.372 ± 0.116 mmol/L) (P < 0.001), regardless of the prescribed medication. The number of patients taking both drugs whose serum uric acid values fell within normal range (men <7 mg/dL (0.38 mmol/L) and women <6 mg/dL (0.33 mmol/L)) was 85.7% (6/7) while this value for the group taking benzbromarone alone was 75% (3/4) and for the group taking allopurinol alone this number was 51.8% (14/27). Conclusions. The therapeutic combination of benzbromarone and allopurinol significantly decreased serum urate levels in patients with gout when compared to individual use of each of these agents. This finding is especially important in treating patients who cannot control hyperuricemia with monotherapy. Benzbromarone alone or in combination with allopurinol has an important clinical role in controlling hyperuricemia in patients with gout.

A broader view: microbial enzymes and their relevance in industries, medicine, and beyond

Enzymes are the large biomolecules that are required for the numerous chemical interconversions that sustain life. They accelerate all the metabolic processes in the body and carry out a specific task. Enzymes are highly efficient, which can increase reaction rates by 100 million to 10 billion times faster than any normal chemical reaction. Due to development in recombinant technology and protein engineering, enzymes have evolved as an important molecule that has been widely used in different industrial and therapeutical purposes. Microbial enzymes are currently acquiring much attention with rapid development of enzyme technology. Microbial enzymes are preferred due to their economic feasibility, high yields, consistency, ease of product modification and optimization, regular supply due to absence of seasonal fluctuations, rapid growth of microbes on inexpensive media, stability, and greater catalytic activity. Microbial enzymes play a major role in the diagnosis, treatment, biochemical investigation, and monitoring of various dreaded diseases. Amylase and lipase are two very important enzymes that have been vastly studied and have great importance in different industries and therapeutic industry. In this review, an approach has been made to highlight the importance of different enzymes with special emphasis on amylase and lipase in the different industrial and medical fields.

Current concepts in the treatment of gouty arthritis

Gouty arthritis is an extremely painful condition that causes functional impairment. Gouty arthritis has become increasingly complex because of multiple comorbidities, iatrogenic factors and hyperuricemia that is refractory to treatment. In this review, we present a general overview of gouty arthritis including its pathophysiology, clinical presentations, diagnosis, predisposing factors and prophylactic therapy for preventing gouty arthritis flares.

Genetics of hyperuricemia and gout: implications for the present and future

Gout is the most common inflammatory arthropathy and occurs in the setting of elevated serum urate levels. Gout is also known to be associated with multiple comorbidities including cardiovascular disease and the metabolic syndrome. Recent advances in research have increased our understanding and improved our knowledge of the pathophysiology of gout. Genome-wide association studies have permitted the identification of several new and common genetic factors that contribute to hyperuricemia and gout. Most of these are involved with the renal urate transport system (the uric acid transportasome), generally considered the most influential regulator of serum urate homeostasis. Thus far, SCL22A12, SCL2A9, and GLUT9 have been found to have the greatest variation and most influence on serum urate levels. However, genetics are only a part of the explanation in the development of hyperuricemia and gout. As results have been mixed, the role of known urate influential genes in gout's associated comorbidities remains unclear. Regardless, GWAS findings have expanded our understanding of the pathophysiology of hyperuricemia and gout, and will likely play a role in the development of future therapies and treatment of this ancient disease.

Rilonacept in the treatment of acute gouty arthritis: a randomized, controlled clinical trial using indomethacin as the active comparator

Introduction

In phase-3 clinical trials, the interleukin (IL-1) blocker, rilonacept (IL-1 Trap), demonstrated efficacy for gout flare prevention during initiation of urate-lowering therapy. This trial evaluated rilonacept added to a standard-of-care, indomethacin, for treatment of acute gout flares.

Methods

Adults, aged 18-70 years, with gout presenting within 48 hours of flare onset and having at least moderate pain as well as swelling and tenderness in the index joint were randomized to subcutaneous (SC) rilonacept 320 mg at baseline plus oral indomethacin 50 mg TID for 3 days followed by 25 mg TID for up to 9 days (n = 74); SC placebo at baseline plus oral indomethacin as above (n = 76); or SC rilonacept 320 mg at baseline plus oral placebo (n = 75). The primary efficacy endpoint was change in pain in the index joint (patient-reported using a Likert scale (0 = none; 4 = extreme)) from baseline to the average of values at 24, 48 and 72 hours (composite time point) for rilonacept plus indomethacin versus indomethacin alone. Comparison of rilonacept monotherapy with indomethacin monotherapy was dependent on demonstration of significance for the primary endpoint. Safety evaluation included clinical laboratory and adverse event (AE) assessments.

Results

Patient characteristics were comparable among the groups; the population was predominantly male (94.1%), white (75.7%), with mean ± SD age of 50.3 ± 10.6 years. All treatment groups reported within-group pain reductions from baseline (P < 0.0001). Although primary endpoint pain reduction was greater with rilonacept plus indomethacin (-1.55 ± 0.92) relative to indomethacin alone (-1.40 ± 0.96), the difference was not statistically significant (P = 0.33), so formal comparison between monotherapy groups was not performed. Pain reduction over the 72-hour period with rilonacept alone (-0.69 ± 0.97) was less than that in the other groups, but pain reduction was similar among groups at 72 hours. Treatment with rilonacept was well-tolerated with no reported serious AEs related to rilonacept. Across all groups, the most frequent AEs were headache and dizziness.

Conclusions

Although generally well-tolerated, rilonacept in combination with indomethacin and rilonacept alone did not provide additional pain relief over 72 hours relative to indomethacin alone in patients with acute gout flare.

Trial registration

ClinicalTrials.gov registration number NCT00855920.

Tocilizumab in a patient with tophaceous gout resistant to treatment

Gout is a disease characterized by acute episodes of pain, which occurs as the result of monosodic urate crystal deposit in the joint and periarticular tissue. In some cases, gout behaves as a severe inflammatory arthopathy that is difficult to manage, generating structural joint damage and functional impairment. We report the case of a 44 years old man with gouty arthritis for 12 years, not responding to NSAIDs, alopurinol, colchicine or corticosteroids. Tocilizumab was started with favorable clinical and laboratory results after treatment.

Xanthine oxidase inhibitory activity of the methanolic extracts of selected Jordanian medicinal plants

Background:

The search for novel xanthine oxidase (XO) inhibitors with a higher therapeutic activity and fewer side effects are desired not only to treat gout but also to combat various other diseases associated with the XO activity. At present, the potential of developing successful natural products for the management of XO-related diseases is still largely unexplored. In the present study, we have screened the methanolic extracts of various Jordanian medicinal plants for their XO inhibitory activities using an optimized protocol.

Materials and Methods:

The methanolic extracts of 23 medicinal plants, belonging to 12 families, were tested in vitro, at 200 μg/ml concentrations, for their XO inhibitory potential. The dose-dependent inhibition profiles of the most active plants were further evaluated by estimating the IC₅₀ values of their corresponding extracts.

Results:

Six plants were found most active (% inhibition more than 39%). These plants are Salvia spinosa L. (IC₅₀ = 53.7 μg/ml), Anthemis palestina Boiss. (168.0 μg/ml), Chrysanthemum coronarium L. (199.5 μg/ml), Achillea biebersteinii Afansiev (360.0 μg/ml), Rosmarinus officinalis L. (650.0 μg/ml), and Ginkgo biloba L. (595.8 μg/ml). Moreover, four more plants, namely Lavandula angustifolia Mill. (28.7% inhibition), Helianthemum ledifolium (L.) Mill. (28.4%), Majorana syriaca (L.) Kostel. (25.1%), and Mentha spicata L. (22.5%) showed a XO inhibitory activity in the range of 22–30%.

Conclusion:

The study showed that many of the tested plant species are potential sources of natural XO inhibitors that can be developed, upon further investigation, into successful herbal drugs for treatment of gout and other XO-related disorders.

Treatment of chronic gouty arthritis: it is not just about urate-lowering therapy

OBJECTIVES

The management of gouty arthritis is focused on treating pain and inflammation associated with acute flares and preventing further acute flares and urate crystal deposition. A challenge associated with the successful management of gouty arthritis is an increased risk of acute flares during the first months after initiation of urate-lowering therapy (ULT). This increase in flare frequency can occur regardless of the choice of ULT and is linked to suboptimal patient adherence to ULT. Current treatment recommendations for the use of prophylaxis are limited. There are no definitive recommendations as to which agents should be used or for how long therapy is beneficial after starting ULT. This article aims to improve awareness of the importance of gouty arthritis flare prophylaxis when initiating ULT and to summarize current recommendations and clinical findings related to the efficacy and safety of currently available and investigational new therapies.

METHODS

This review discusses the pathophysiology of acute gouty arthritis flares during initiation of ULT and examines the literature on the use of anti-inflammatory prophylaxis for reduction of these flares.

RESULTS

It has recently become clear that, even when the patient is asymptomatic, chronic inflammation is often present in patients with chronic gouty arthritis. Chronic anti-inflammatory therapy should therefore be added to chronic ULT. Prophylaxis with colchicine as well as with nonsteroidal anti-inflammatory drugs (NSAIDs) during ULT initiation can reduce the incidence and severity of gouty arthritis flares substantially; however, safety concerns associated with colchicine and NSAIDs may limit their use.

CONCLUSION

When colchicine and NSAIDs are contraindicated or poorly tolerated, rilonacept and canakinumab, interleukin-1 inhibitors in trials, may prove to be useful alternatives for flare prevention. (Of note, although both inhibit the IL-1β pathway, rilonacept also binds to IL-1α and IL-1RA, in contrast to canakinumab, which binds selectively to IL-1β.).

Gout, genetics and ABC transporters

Gout is a chronic arthritic disease associated with high levels of urate in blood. Recent advances in research have permitted the identification of several new and common genetic factors underlying the disease. Among them, a polymorphism in the ABC transporter gene ATP-binding cassette transporter isoform G2 has been highlighted. ATP-binding cassette transporter isoform G2 was found to be involved in renal urate elimination, and the presence of the Q141K polymorphism to induce a 2-fold decrease in urate efflux. The Q141K variant has been shown to have impaired trafficking, leading to its intracellular retention, whereas the wild type protein is expressed on the cell surface. Several agents are being studied for the purpose of improving folding, trafficking and function of various ABC transporters, including ATP-binding cassette transporter isoform G2. If successful, this strategy opens doors to potential new therapies for gout.

2011 recommendations for the diagnosis and management of gout and hyperuricemia

Gout is a major health problem in the United States; it affects 8.3 million people, which is approximately 4% of the adult population. Gout is most often diagnosed and managed in primary care practices; thus, primary care physicians have a significant opportunity to improve patient outcomes. Following publication of the 2006 European League Against Rheumatism (EULAR) gout guidelines, significant new evidence has accumulated, and new treatments for patients with gout have become available. It is the objective of these 2011 recommendations to update the 2006 EULAR guidelines, paying special attention to the needs of primary care physicians. The revised 2011 recommendations are based on the Grading of Recommendations Assessment, Development, and Evaluation approach as an evidence-based strategy for rating quality of evidence and grading the strength of recommendation formulated for use in clinical practice. A total of 26 key recommendations, 10 for diagnosis and 16 for management, of patients with gout were evaluated, resulting in important updates for patient care. The presence of monosodium urate crystals and/or tophus and response to colchicine have the highest clinical diagnostic value. The key aspect of effective management of an acute gout attack is initiation of treatment within hours of symptom onset. Low-dose colchicine is better tolerated and is as effective as a high dose. When urate-lowering therapy (ULT) is indicated, the xanthine oxidase inhibitors allopurinol and febuxostat are the options of choice. Febuxostat can be prescribed at unchanged doses for patients with mild-to-moderate renal or hepatic impairment. The target of ULT should be a serum uric acid level that is ≤ 6 mg/dL. For patients with refractory and tophaceous gout, intravenous pegloticase is a new treatment option. This article is a summary of the 2011 clinical guidelines published in Postgraduate Medicine. This article provides a streamlined, accessible overview intended for quick review by primary care physicians, with the full guidelines being a resource for those seeking additional background information and expanded discussion.

Management of asymptomatic hyperuricaemia in patients with chronic kidney disease by Japanese nephrologists: a questionnaire survey

AIM

Hyperuricaemia is associated with chronic kidney disease (CKD) progression and cardiovascular events (CVE). In a US study, only 4% of rheumatologists initiated urate-lowering therapy in patients with asymptomatic hyperuricaemia (AHU). The present study aimed to clarify how Japanese board-certified nephrologists manage AHU in CKD patients.

METHODS

Questionnaires on management of AHU in CKD stage 3 or more were mailed to 1500 Japanese board-certified nephrologists, excluding paediatricians and urologists, randomly selected from the directory of the Japanese Society of Nephrology (n = 2976).

RESULTS

Five hundred and ninety-five nephrologists (40%) responded. Most nephrologists (84-89%) recommended that AHU in patients in CKD stages 3-5 should be treated, but fewer nephrologists (63%) recommended that AHU in patients of CKD stage 5D should be treated. The serum urate level to start urate-lowering therapy and the target serum urate level to be achieved (mg/dL) were 8.2 ± 0.9 and 6.9 ± 0.9, 8.4 ± 0.9 and 7.0 ± 1.0, 8.6 ± 1.0 and 7.3 ± 1.1, and 9.1 ± 1.2 and 7.8 ± 1.3 at stages 3, 4, 5 and 5D, respectively. The most frequently used maximal dosage of allopurinol was 100 mg/day at each stage. Benzbromarone was used in 52% of patients at stage 3, but only in 29%, 13% and 5% of patients at stages 4, 5 and 5D, respectively. The most important reasons to treat AHU at CKD stages 3-5 were prevention of CKD progression (45%), CVE (33%), gout (18%) and urolithiasis (3%).

CONCLUSION

Most Japanese nephrologists treat AHU in pre-dialysis CKD with an aim to prevent CKD progression or CVE mainly by allopurinol.

Gout therapeutics: new drugs for an old disease

The approval of febuxostat, a non-purine-analogue inhibitor of xanthine oxidase, by the European Medicines Agency and the US Food and Drug Administration heralds a new era in the treatment of gout. The use of modified uricases to rapidly reduce serum urate concentrations in patients with otherwise untreatable gout is progressing. Additionally, advances in our understanding of the transport of uric acid in the renal proximal tubule and the inflammatory response to monosodium urate crystals are translating into potential new treatments. In this Review, we focus on the clinical trials of febuxostat. We also review results from studies of pegloticase, a pegylated uricase in development, and we summarise data for several other pipeline drugs for gout, such as the selective uricosuric drug RDEA594 and various interleukin-1 inhibitors. Finally, we issue a word of caution about the proper use of the new drugs and the already available drugs for gout. At a time of important advances, we need to recommit ourselves to a rational approach to the treatment of gout.

New and improved strategies for the treatment of gout

The Western world appears to be in the midst of the third great gout epidemic of all time. In this century, gout is increasing in prevalence despite an increased understanding of its risk factors and pathophysiology, and the availability of reasonably effective treatment. The main cultural factors responsible for this appear to be diet, obesity, ethanol use and medications. Excess fructose consumption is a newly recognized modifiable risk factor. The debate has been renewed concerning hyperuricemia as an independent risk factor for renal insufficiency and cardiovascular disease. Prevention is still rooted in lifestyle choices. Existing treatments have proven to be unsatisfactory in many patients with comorbidities. New treatments are available today and on the horizon for tomorrow, which offer a better quality of life for gout sufferers. These include febuxostat, a nonpurine inhibitor of xanthine oxidase with a potentially better combination of efficacy and safety than allopurinol, and investigational inhibitors of URAT-1, an anion exchanger in the proximal tubule that is critical for uric acid homeostasis. New abortive treatments include interleukin-1 antagonists that can cut short the acute attack in 1 to 2 days in persons who cannot take nonsteroidal anti-inflammatory drugs, colchicine or corticosteroids. Lastly, newer formulations of uricase have the ability to dissolve destructive tophi over weeks or months in patients who cannot use currently available hypouricemic agents. Diagnostically, ultrasound and magnetic resonance imaging offer advanced ways to diagnose gout noninvasively, and just as importantly, a way to follow the progress of tophus dissolution. The close association of hyperuricemia with metabolic syndrome, hypertension and renal insufficiency ensures that nephrologists will see increasing numbers of gout-afflicted patients.

Treating gout with pegloticase, a PEGylated urate oxidase, provides insight into the importance of uric acid as an antioxidant in vivo

A high plasma urate concentration (PUA), related to loss of urate oxidase in evolution, is postulated to protect humans from oxidative injury. This hypothesis has broad clinical relevance, but support rests largely on in vitro data and epidemiologic associations. Pegloticase therapy generates H(2)O(2) while depleting urate, offering an in vivo test of the antioxidant hypothesis. We show that erythrocytes can efficiently eliminate H(2)O(2) derived from urate oxidation to prevent cell injury in vitro; during therapy, disulfide-linked peroxiredoxin 2 dimer did not accumulate in red blood cells, indicating that their peroxidase capacity was not exceeded. To assess oxidative stress, we monitored F2-Isoprostanes (F2-IsoPs) and protein carbonyls (PC), products of arachidonic acid and protein oxidation, in plasma of 26 refractory gout patients receiving up to five infusions of pegloticase at 3-wk intervals. At baseline, PUA was markedly elevated in all patients, and plasma F2-IsoP concentration was elevated in most. Pegloticase infusion rapidly lowered mean PUA to < or = 1 mg/dL in all patients, and PUA remained low in 16 of 21 patients who completed treatment. F2-IsoP levels did not correlate with PUA and did not increase during 15 wk of sustained urate depletion. There also was no significant change in the levels of plasma PC. Because refractory gout is associated with high oxidative stress in spite of high PUA, and profoundly depleting uric acid did not increase lipid or protein oxidation, we conclude that urate is not a major factor controlling oxidative stress in vivo.

Update on gout: new therapeutic strategies and options

Gout, a disease recognized since antiquity, has increased in prevalence in recent years and the clinical profile of this disease has become increasingly complex, owing to large numbers of cases with iatrogenic factors, multiple comorbidities, advanced age, and hyperuricemia and arthritis refractory to treatment. In this Review, key advances in gout research made during the past decade are summarized. Revised strategies for safe and effective employment of dietary measures and pharmacologic treatments for active gouty arthritis, prevention of gout flares and urate lowering are also reviewed, with an emphasis on dosing of colchicine and allopurinol, and the evidence-based approach to systemic glucocorticosteroid treatment of acute gout. Also discussed are new and emerging treatments for gout and hyperuricemia, and the potential influence of dual energy CT imaging on treatment. In this context, the therapeutic role of febuxostat, and clinical development of pegylated uricase urate-lowering therapy and interleukin 1 antagonism for gouty inflammation are reviewed. Collectively, novel approaches will hopefully lead to improved management of hyperuricemia and gout, and also to improvements in patient-centered outcomes, even for those who have previously failed to respond to treatment.