Colchicine: the good, the bad, the ugly and how to minimize the risks

Colchicine has an important role in managing various conditions, including gout, familial Mediterranean fever, amyloidosis, Behçet's syndrome, recurrent pericarditis and calcium pyrophosphate deposition disease. The adverse effect profile of colchicine is well understood. However, due to its narrow therapeutic index, colchicine has been associated with overdose and fatalities. When ingested in toxic amounts, the mainstay of management is supportive care. Strategies to minimize the risk of colchicine poisoning can focus on three broad causes: unauthorized access, intentional overdose and inappropriate dosing. Culturally safe and appropriate education about storage and appropriate use of colchicine is essential to minimize the risk of overdose.

Long-term exposure to ambient air pollution and incident gout: A prospective cohort study in the UK Biobank

Gout is a chronic disorder characterized by the accumulation of uric acid in the body, leading to recurrent episodes of joint inflammation and pain. There remains a lack of studies investigating the association between long-term exposure to ambient air pollution and the incidence of gout. We conducted this prospective cohort study involving participants aged 38-70 from the UK Biobank who were enrolled in 2006-2010 and followed until 2023. Baseline residential concentrations of fine particulate matter (PM2.5), inhalable particulate matter (PM10), nitrogen dioxide (NO2) and nitrogen oxides (NOx) were predicted using land-use regression models. Cox proportional hazards models were employed to examine the relationship between air pollution and incident gout events. A total of 443,587 individuals were included in the analyses and a total of 6589 incident gout cases were identified over a follow-up of 6,130,439 person-years. There were significant associations between higher levels of air pollution and an increased incidence risk of gout. Higher risk of incident gout was associated with each interquartile range increase in concentrations of PM2.5 (hazard ratio:1.05, 95% confidence intervals: 1.02-1.09), PM10 (1.04, 1.00-1.07), NO2 (1.08, 1.05-1.12) and NOx (1.04, 1.02-1.07). The magnitude of associations was larger at higher concentrations. The association was more prominent among older adults, smokers, and individuals with lower and moderate physical activity. This prospective cohort study provides novel and compelling evidence of increased risk of incident gout associated with long-term air pollution exposures.

Protocol to create a murine subcutaneous air pouch for the study of monosodium urate crystal-induced gout

Monosodium urate (MSU) crystal deposition in articular joints and bursal tissue causes acute joint inflammation, which is a hallmark of gout. Here, we describe the steps necessary to create a subcutaneous air pouch on the back of mice that resembles this bursa-like space with a synovial lining-like membrane. We then detail the injection of MSU crystals into this pouch, which induces a localized inflammatory response reminiscent of gout and approaches to quantify the inflammatory response. For complete details on the use and execution of this protocol, please refer to Devi et al. (2023),1 de Almeida et al. (2022),2 and Ratsimandresy et al. (2017).3.

Comparative studies of xanthine oxidase inhibitors viz. allopurinol and febuxostat against induced hyperuricaemia in a poultry model

In this study, an attempt was made to evaluate the relative efficacy of two important anti-gout agents, viz. allopurinol and febuxostat, in the control of hyperuricaemia/gout using a poultry model. A 21-day study was conducted on 48 Vencobb-400 broiler chicks randomly divided into four groups. In one group hyperuricaemia/gout was induced by the oral administration of diclofenac (group D); in two other groups the ameliorative effect of the two drugs under study was investigated by providing both simultaneously, i.e. diclofenac and allopurinol (group DA), diclofenac and febuxostat (group DF); and the fourth group was kept un-induced and untreated as a control (group C). Both allopurinol and febuxostat inhibit xanthine oxidase enzymes, thereby reducing the production of uric acid. The birds kept on diclofenac alone exhibited the highest level of hyperuricaemia, clinical signs of gout, and overt adverse changes in the visceral organs, whereas these changes were lesser in allopurinol- and febuxostat-treated groups. Furthermore, haematological, biochemical, patho-morphological, and ultra-structural studies using transmission electron microscopy were carried out to evaluate the pathology and, thus, the ameliorative effect of allopurinol and febuxostat. The findings proved that allopurinol and febuxostat carry definite ameliorative potential as anti-hyperuricemic and anti-gout agents in poultry, which was better expressed by febuxostat compared to allopurinol.

The relationship of organophosphate flame retardants with hyperuricemia and gout via the inflammatory response: An integrated approach

BACKGROUND

Evidence regarding the relationships between organophosphate flame retardants (OPFRs) and hyperuricemia and gout as well as the underlying mechanisms remains scarce, but some evidence indicates that inflammation might play a key role.

OBJECTIVES

Using an integrated approach, we aim to elucidate the associations of urinary metabolite OPFRs (m-OPFRs) with hyperuricemia and gout.

METHODS

Cross-sectional analyses using data from the National Health and Nutrition Examination Survey were performed to reveal the associations. Adults with complete data on five m-OPFRs with high detection frequencies and outcomes were enrolled. We used multivariate logistic regression, restricted cubic spline (RCS), and Bayesian kernel machine regression (BKMR) methods to account for single, nonlinear, and joint effects. The mediating effect of the inflammatory response was also estimated. Moreover, adverse outcome pathways (AOPs) based on network analysis were further constructed to reveal the underlying mechanism.

RESULTS

Multivariate logistic models revealed that bis(2-chloroethyl) phosphate (BCEP) significantly increased risk of hyperuricemia (OR [95 % CI]: 1.165 [1.047, 1.296]) in the fully adjusted model. Elevated levels of bis(1-chloro-2-propyl) phosphate were associated with gout (OR [95 % CI]: 1.293 [1.015, 1.647]). No nonlinear relationship was observed in RCS. There was a positive association between mixed m-OPFRs and hyperuricemia risk in BMKR, with bis(1,3-dichloro-2-propyl) phosphate and BCEP being the main contributors (PIP > 0.5). We found that the inflammatory response significantly mediated the association between BCEP and hyperuricemia (P < 0.05). Network topology analysis identified seven genes and six phenotypes related to OPFR exposure and hyperuricemia. The AOP framework suggested that the inflammatory response, especially the activation of the TNF pathway, played a core role in the above relationships.

CONCLUSION

Our results first revealed that individual and mixed OPFRs were associated with hyperuricemia, in which the inflammatory response plays an important role. Further longitudinal studies are warranted to consolidate or refute our main findings.

Activation of Nrf2 antioxidant signaling alleviates gout arthritis pain and inflammation

Excessive deposition of monosodium urate (MSU) crystal in the joint results in gout arthritis, which triggers severe pain and affects life quality. Oxidative stress is a pivotal mechanism that contributes to etiology of gout pain and inflammation. Here we investigated whether activating Nrf2, which plays important roles in regulating endogenous antioxidant response, would attenuate gout arthritis via promoting antioxidant signaling in joint tissues. Gout arthritis model was established by intra-articular injection of MSU (500 μg/ankle) into the right ankle joint of mouse. Pharmacologically activating Nrf2 by activator oltipraz (50, 100 or 150 mg/kg, intraperitoneal) at 1 h before and 5, 23, 47 h after model establishment dose-dependently inhibited joint inflammation, mechanical and heat hypersensitivities in model mice. Oltipraz (100 mg/kg) reversed gait impairments without altering locomotor activity and reduced neutrophil infiltrations in ankle joints. In vitro studies revealed oltipraz (25 μM) inhibited MSU-induced ROS production in mouse macrophages and improved mitochondrial bioenergetics impairments caused by MSU. In vivo ROS imaging combined with biochemical assays confirmed the antioxidant effects of oltipraz on model mice. Nrf2 activation inhibited pro-inflammatory cytokine overproduction in ankle joint and attenuated the overexpression and enhancement in TRPV1 channel in DRG neurons innervating hind limb. Therapeutic effects of oltipraz were abolished by inhibiting Nrf2 or in Nrf2 knockout mice. These results suggest pharmacologically activating Nrf2 alleviates gout pain, gait impairments, inflammation and peripheral sensitization via Nrf2-dependent antioxidant mechanism. Targeting Nrf2 may represent a novel treatment option for gout arthritis.

The role of acid-sensing ion channels in monosodium urate-induced gouty pain in mice

Acid-sensing ion channels (ASICs) in dorsal root ganglion (DRG) neurons play an important role in inflammatory pain. The objective of this study is to observe the regulatory role of ASICs in monosodium urate (MSU) crystal-induced gout pain and explore the basis for ASICs in DRG neurons as a target for gout pain treatment. The gout arthritis model was induced by injecting MSU crystals into the ankle joint of mice. The circumference of the ankle joint was used to evaluate the degree of swelling; the von Frey filaments were used to determine the withdrawal threshold of the paw. ASIC currents and action potentials (APs) were recorded by patch clamp technique in DRG neurons. The results displayed that injecting MSU crystals caused ankle edema and mechanical hyperalgesia of the paw, which was relieved after amiloride treatment. The ASIC currents in DRG neurons were increased to a peak on the second day after injecting MSU crystals, which were decreased after amiloride treatment. MSU treatment increased the current density of ASICs in different diameter DRG cells. MSU treatment does not change the characteristics of AP. The results suggest that ASICs in DRG neurons participate in MSU crystal-induced gout pain.

Safety and efficacy of bempedoic acid: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND AND AIMS

Bempedoic Acid (BA) is a novel Lipid-Lowering Therapy (LLT). We performed a systematic review and meta-analysis to assess the efficacy and safety of BA in patients with hypercholesterolemia.

METHODS

PubMed, Scopus, and Cochrane library databases were searched for randomised controlled trials evaluating the efficacy and/or safety of BA compared with placebo. Trials investigating dosages other than 180 mg/die were excluded. Major adverse cardiovascular events (MACE) were the primary efficacy endpoint. LDL-cholesterol reduction was the primary laboratory endpoint. Pre-specified safety endpoints included muscle-related adverse events, new-onset diabetes, and gout. The protocol was registered on PROSPERO (temporary ID:399,867).

RESULTS

Study search identified 275 deduplicated results. 11 studies, encompassing 18,315 patients (9854 on BA vs 8461 on placebo/no treatment) were included. BA was associated with a reduced risk of MACE (OR 0.86, 95% CI 0.79-0.95), myocardial infarction (OR 0.76, 95% CI 0.64-0.88) and unstable angina (OR 0.69, 95% CI 0.54-0.88) compared to control, over a median follow up of 87 (15-162) weeks. BA was associated with a reduction of LDL-Cholesterol (mean difference [MD]-22.42,95% CI - 24.02% to - 20.82%), total cholesterol (- 16.50%,95% - 19.21% to - 13.79%), Apo-B lipoprotein (- 19.55%, - 22.68% to - 16.42%) and high-sensitivity CRP (- 27.83%, - 31.71% to - 23.96%) at 12 weeks. BA was associated with a higher risk of gout (OR 1.55, 95% CI 1.27-1.90) as compared with placebo. Efficacy on laboratory endpoints was confirmed, with a variable extent, across patients on statin or ezetimibe background therapy.

CONCLUSIONS

The improved cholesterol control achieved with BA translates into a reduced risk of MACE, including myocardial infarction and coronary revascularisation. The drug has a satisfactory safety profile except for an increased risk of gout.

Serum uric acid lowering and effects of sodium-glucose cotransporter-2 inhibitors on gout: A meta-analysis and meta-regression of randomized controlled trials

AIMS

To pool the effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors on gout and to investigate the association of these effects with baseline serum uric acid (SUA), SUA lowering, and underlying conditions, such as type 2 diabetes mellitus (T2DM)/heart failure (HF).

METHODS

PubMed, Embase, Web of Science, Cochrane Library and clinical trial registry websites were searched for randomized controlled trials (RCTs) or post hoc analyses (≥1-year duration; PROSPERO:CRD42023418525). The primary outcome was a composite of gouty arthritis/gout flares and commencement of anti-gout drugs (SUA-lowering drugs/colchicine). Hazard ratios (HRs) with 95% confidence interval (CI) were pooled using a generic inverse-variance method with a random-effects model. Mixed-effects model univariate meta-regression analysis was performed.

RESULTS

Five RCTs involving 29 776 patients (T2DM, n = 23 780) and 1052 gout-related events were identified. Compared to placebo, SGLT2 inhibitor use was significantly associated with reduced risk of composite gout outcomes (HR 0.55, 95% CI 0.45-0.67; I2  = 61%, P < 0.001). Treatment benefits did not differ between trials being conducted exclusively in baseline HF versus those conducted in patients with T2DM (P-interaction = 0.37), but were greater with dapagliflozin 10 mg and canagliflozin 100/300 mg (P < 0.01 for subgroup differences). Sensitivity analysis excluding trials that evaluated the effects of empagliflozin 10/25 mg (HR 0.68, 95% CI 0.57-0.81; I2  = 0%) accentuated the benefits of SGLT2 inhibitors with no between-trial heterogeneity (HR 0.46, 95% CI 0.39-0.55; I2  = 0%). Univariate meta-regression found no impact of baseline SUA, SUA lowering on follow-up, diuretic use, or other variables on their anti-gout effects.

CONCLUSION

We found that SGLT2 inhibitors significantly reduced the risk of gout in individuals with T2DM/HF. Lack of an association with SUA-lowering effects suggests that metabolic and anti-inflammatory effects of SGLT2 inhibitors may predominantly mediate their anti-gout benefits.

Proton pump inhibitor use associated with an increased risk of gout: A population-based case-control study

OBJECTIVES

In previous reports, proton pump inhibitor (PPI) use increased the risk of gout. However, there is no epidemiological study investigating this association. We aimed to examine the potential impact of PPI treatment on the risk of developing gout.

METHODS

A population-based case-control study was performed using a Longitudinal Health Insurance Database 2000 from Taiwan (population 23 million). We identified gout cases and non-gout controls through propensity score matching at 1:1, which was matched by sex and age. We used a conditional logistic regression model to estimate an odds ratio and 95% confidence intervals (CI) for gout population versus controls.

RESULTS

Esomeprazole increased the risk of gout after adjusting confounding variables (adjusted odds ratio [aOR] 1.3; 95% CI 1.0-1.6). The risk of gout was highest within 30 days of PPI treatment (aOR 1.7; 95% CI 1.4-1.9) and attenuated thereafter. The risk of gout was increased among female users of PPI compared with male users (aOR 2.2; 95% CI 1.7-2.8). The aOR of gout in people with PPI use was higher in middle-aged individuals (41-60 years: aOR 2.1; 95% CI 1.7-2.7) than in the older group (≥60 years: aOR 1.8; 95% CI 1.5-2.2).

CONCLUSIONS

Our findings provide population-level evidence for the hypothesis that PPI treatment is positively associated with the risk of developing gout. Further research on the mechanism underlying this association is warranted.

Pegloticase in Uncontrolled Gout: The Infusion Nurse Perspective

Infused biologics, such as pegloticase, are a core component of managing uncontrolled gout, which is increasing in prevalence. Pegloticase is often the last line of therapy for patients with uncontrolled gout; therefore, achieving a successful course of treatment is critical. The infusion nurse's role in patient education, serum uric acid monitoring, and patient medication compliance is essential for ensuring patient safety and maximizing the number of patients who benefit from a full treatment course of pegloticase. Infusion nurses are on the front lines with patients and need to be educated on potential negative effects associated with the medications they infuse, such as infusion reactions, as well as risk management methods like patient screening and monitoring. Further, patient education provided by the infusion nurse plays a large role in empowering the patient to become their own advocate during pegloticase treatment. This educational overview includes a model patient case for pegloticase monotherapy, as well as one for pegloticase with immunomodulation and a step-by-step checklist for infusion nurses to refer to throughout the pegloticase infusion process. A video abstract is available for this article at http://links.lww.com/JIN/A105.

Colchicine Drug Interaction Errors and Misunderstandings: Recommendations for Improved Evidence-Based Management

Colchicine is useful for the prevention and treatment of gout and a variety of other disorders. It is a substrate for CYP3A4 and P-glycoprotein (P-gp), and concomitant administration with CYP3A4/P-gp inhibitors can cause life-threatening drug-drug interactions (DDIs) such as pancytopenia, multiorgan failure, and cardiac arrhythmias. Colchicine can also cause myotoxicity, and coadministration with other myotoxic drugs may increase the risk of myopathy and rhabdomyolysis. Many sources of DDI information including journal publications, product labels, and online sources have errors or misleading statements regarding which drugs interact with colchicine, as well as suboptimal recommendations for managing the DDIs to minimize patient harm. Furthermore, assessment of the clinical importance of specific colchicine DDIs can vary dramatically from one source to another. In this paper we provide an evidence-based evaluation of which drugs can be expected to interact with colchicine, and which drugs have been stated to interact with colchicine but are unlikely to do so. Based on these evaluations we suggest management options for reducing the risk of potentially severe adverse outcomes from colchicine DDIs. The common recommendation to reduce the dose of colchicine when given with CYP3A4/P-gp inhibitors is likely to result in colchicine toxicity in some patients and therapeutic failure in others. A comprehensive evaluation of the almost 100 reported cases of colchicine DDIs is included in table form in the electronic supplementary material. Colchicine is a valuable drug, but improvements in the information about colchicine DDIs are needed in order to minimize the risk of serious adverse outcomes.

cis-Aconitic Acid, a Constituent of Echinodorus grandiflorus Leaves, Inhibits Antigen-Induced Arthritis and Gout in Mice

cis-Aconitic acid is a constituent from the leaves of Echinodorus grandiflorus, a medicinal plant traditionally used in Brazil to treat inflammatory conditions, including arthritic diseases. The present study aimed to investigate the anti-arthritic effect of cis-aconitic acid in murine models of antigen-induced arthritis and monosodium urate-induced gout. The possible underlying mechanisms of action was evaluated in THP-1 macrophages. Oral treatment with cis-aconitic acid (10, 30, and 90 mg/kg) reduced leukocyte accumulation in the joint cavity and C-X-C motif chemokine ligand 1 and IL-1β levels in periarticular tissue. cis-Aconitic acid treatment reduced joint inflammation in tissue sections of antigen-induced arthritis mice and these effects were associated with decreased mechanical hypernociception. Administration of cis-aconitic acid (30 mg/kg p. o.) also reduced leukocyte accumulation in the joint cavity after the injection of monosodium urate crystals. cis-Aconitic acid reduced in vitro the release of TNF-α and phosphorylation of IκBα in lipopolysaccharide-stimulated THP-1 macrophages, suggesting that inhibition of nuclear factor kappa B activation was an underlying mechanism of cis-aconitic acid-induced anti-inflammatory effects. In conclusion, cis-aconitic acid has significant anti-inflammatory effects in antigen-induced arthritis and monosodium urate-induced arthritis in mice, suggesting its potential for the treatment of inflammatory diseases of the joint in humans. Additionally, our findings suggest that this compound may contribute to the anti-inflammatory effect previously reported for E. grandiflorus extracts.

Appraisal of anti-gout potential of colchicine-loaded chitosan nanoparticle gel in uric acid-induced gout animal model

Present study is aimed at transdermal delivery of colchicine-loaded chitosan nanoparticles. The nanoformulations were prepared utilising spontaneous emulsification method and optimised through 2³ factorial designs. The optimised formulation (CHNP-OPT) displayed an average particle size of 294 ± 3.75 nm, entrapment efficiency 92.89 ± 1.1% and drug content 83.45 ± 2.5%, respectively. In vitro release study demonstrated 89.34 ± 2.90% release over a period of 24 h. Further, CHNP-OPT incorporated into HPMC-E4M (hydroxypropyl methylcellulose) to form transdermal gel. CHNP_gel displayed 74.65 ± 1.90% permeation and stability over a period of 90 days. The anti-gout potential of CHNP_gel formulation was evaluated in vivo against monosodium urate (MSU) crystal-induced gout in animal model. There was significant reduction in uric acid level, during MSU administration, when compared with the conventional gel of colchicine. The enhanced therapeutic potential was witnessed through X-ray. The study revealed that colchicine-loaded CHNP_gel proved their supremacy over plain colchicine and can be an efficient delivery system for gout treatment.

Effect of air pollution on gout development: a nationwide population-based observational study

OBJECTIVE

To investigate the effect of air pollution on gout development.

METHODS

A total of 170318 participants were enrolled. These pollutants were considered: carbon monoxide (CO), fine particulate matter 2.5 (PM2.5), total hydrocarbons (THC) and methane (CH4). The yearly average concentrations were calculated from 2000 to 2011. Univariate and multivariate analyses by Cox proportional hazard regression models were adopted to estimate hazard ratios for gout in the Q2-Q4 concentrations of air pollutants compared with the Q1 concentration.

RESULTS

In THC, relative to the Q1 concentration, the risk of gout was higher in participants exposed to the Q2-Q4 concentrations [adjusted hazard ratio (aHR), 1.10 with 95% confidence interval (CI), 1.01-1.19 in the Q2 concentration of THC; aHR, 4.20 with 95% CI, 3.93-4.49 in the Q3 concentration of THC; aHR, 5.65 with 95% CI, 5.29-6.04 in the Q4 concentration of THC]. In regard to CH4, when the Q1 concentration was defined as the reference, the risks of gout were increased for participants exposed to the Q2, Q3 and Q4 concentrations (aHR, 1.16 with 95% CI, 1.06-1.26 in the Q2 concentration of CH4; aHR, 2.37 with 95% CI, 2.20-2.55 in the Q3 concentration of CH4; aHR, 8.73 with 95% CI, 8.16-9.34 in the Q4 concentration of CH4).

CONCLUSIONS

Association between air pollution and risk of gout was noted.

Association of Sodium-Glucose Transport Protein 2 Inhibitor Use for Type 2 Diabetes and Incidence of Gout in Taiwan

IMPORTANCE

The use of sodium-glucose transport protein 2 (SGLT2) inhibitors is currently a standard intervention in patients with type 2 diabetes (T2DM) and exerts favorable pleiotropic effects to consistently lower blood urate levels. However, to date, no association between SGLT2 inhibitor use and the incidence of gout have been established.

OBJECTIVE

To investigate whether prescribed SGLT2 inhibitors are associated with lower gout incidence in patients with T2DM.

DESIGN, SETTING, AND PARTICIPANTS

In a cohort study, all patients with incident T2DM in Taiwan National Health Institution databases between May 1, 2016, and December 31, 2018, were retrospectively analyzed. As a comparator, patients using dipeptidyl peptidase 4 (DPP4) inhibitors were included. A total of 47 905 individuals receiving an SGLT2 inhibitor and 183 303 receiving a DPP4 inhibitor were evaluated, along with 47 405 pairs of patients using an SGLT2 inhibitor or DPP4 inhibitor in 1:1 propensity score-matched analyses. Data analysis was conducted from April 1 to June 30, 2021.

MAIN OUTCOMES AND MEASURES

A gout diagnosis was based on the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) and the International Statistical Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM). Multiple Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% CIs.

RESULTS

In total, 231 208 patients with T2DM were included in the population; 113 812 individuals (49.22%) were women, and the mean (SD) age was 61.53 (12.86) years. The overall gout incidence was 20.26 per 1000 patient-years for SGLT2 inhibitor users and 24.30 per 1000 patient-years for DPP4 inhibitor users. When potential risk factors were adjusted in the propensity score-matched population, use of SGLT2 inhibitors was associated with a lower risk of gout (HR, 0.89; 95% CI, 0.82-0.96) compared with DPP4 inhibitors, particularly for patients receiving dapagliflozin (HR, 0.86; 95% CI, 0.78-0.95). A sensitivity analysis, performed when a gout diagnosis was ascertained using the ICD-9-CM or ICD-10-CM code with gout-related medication, also showed a significantly lower risk for gout incidence of 15% with SGLT2 inhibitors (HR, 0.85; 95% CI, 0.74-0.97). Subgroup analysis indicated that SGLT2 inhibitor benefits in patients with T2DM to achieve a lower gout risk were not different across subgroups.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that patients with T2DM who are receiving SGLT2 inhibitors may have a lower risk for gout compared with those receiving DPP4 inhibitors.

Association of low-level environmental exposure to cadmium and lead with gout flare using a cohort study design

Cadmium (Cd) and lead (Pb) are toxic heavy metals with endocrine-disrupting properties. We investigated the associations of low-level environmental exposure to Cd/Pb and gout status (intercritical gout, gout flare and combined gout) in a cohort study. We measured by ICP-MS the levels of Cd and Pb in blood (Cd-B and Pb-B) and urine (Cd-U and Pb-U) from 408 participants with blood and 346 participants with urine samples recruited from a hospital gout clinic. The median levels of Cd-B and Pb-B (in μg/L) in the gout flare group were 0.87 (range 0.41-2.49) and 31.54 (25.38-41.46), respectively, and the median levels of Cd-U and Pb-U in the gout flare group were 1.05 (0.69-1.91) and 3.86 (3.49-4.44), respectively. These medians were significantly higher than those in the control or intercritical groups (P < 0.05). For Cd-B in tertile 2 (T2) and Cd-U in tertile 3, Cd levels were significantly associated with gout flare status compared to the reference tertile 1 (OR = 4.3, P = 0.041 and OR = 25.1, P = 0.002, respectively) after adjustment under Model 3. For Pb-U, the risk of gout flare status was significantly higher in T2 (OR = 51.0, P = 0.002) compared to the T1 under Model 3. Our results show that median levels of Cd-B, Pb-B, Cd-U and Pb-U in the gout flare group were significantly higher than participants without gout or with gout but in the intercritical period. We provide evidence that the risk of gout flare status is associated with increased Cd levels, and that blood and urine levels of Cd are a risk factor for gout flare status.

Tanshinones inhibit NLRP3 inflammasome activation by alleviating mitochondrial damage to protect against septic and gouty inflammation

Tanshinones, the active ingredients derived from the roots of Salvia miltiorrhiza, have been widely used as traditional medicinal herbs for treating human diseases. Although tanshinones showed anti-inflammatory effects in many studies, large knowledge gaps remain regarding their underlying mechanisms. Here, we identified 15 tanshinones that suppressed the activation of NLRP3 inflammasome and studied their structure-activity relationships. Three tanshinones (tanshinone IIA, isocryptotanshinone, and dihydrotanshinone I) reduced mitochondrial reactive-oxygen species production in lipopolysaccharide (LPS)/nigericin-stimulated macrophages and correlated with altered mitochondrial membrane potentials, mitochondria complexes activities, and adenosine triphosphate and protonated-nicotinamide adenine dinucleotide production. The tanshinones may confer mitochondrial protection by promoting autophagy and the AMP-activated protein kinase pathway. Importantly, our findings demonstrate that dihydrotanshinone I improved the survival of mice with LPS shock and ameliorated inflammatory responses in septic and gouty animals. Our results suggest a potential pharmacological mechanism whereby tanshinones can effectively treat inflammatory diseases, such as septic and gouty inflammation.

Suppression of monosodium urate crystal-induced inflammation by inhibiting TGF-β-activated kinase 1-dependent signaling: role of the ubiquitin proteasome system

Monosodium urate (MSU) crystals activate inflammatory pathways that overlap with interleukin-1β (IL-1β) signaling. However, the post-translational mechanisms involved and the role of signaling proteins in this activation are unknown. In the present study, we investigated the intracellular signaling mechanisms involved in MSU-induced activation of THP-1 macrophages and human nondiseased synovial fibroblasts (NLSFs) and the in vivo efficacy of an inhibitor of tumor growth factor-β (TGF-β)-activated kinase 1 (TAK1), 5Z-7-oxozeaenol, in MSU-induced paw inflammation in C57BL/6 mice. THP-1 macrophage activation with MSU crystals (25-200 µg/ml) resulted in the rapid and sustained phosphorylation of interleukin-1 receptor-activated kinase 1 (IRAK1 Thr209) and TAK1 (Thr184/187) and their association with the E3 ubiquitin ligase TRAF6. At the cellular level, MSU inhibited the deubiquitinases A20 and UCHL2 and increased 20s proteasomal activity, leading to a global decrease in K63-linked ubiquitination and increase in K48-linked ubiquitination in THP-1 macrophages. While MSU did not stimulate cytokine production in NLSFs, it significantly amplified IL-1β-induced IL-6, IL-8, and ENA-78/CXCL5 production. Docking studies and MD simulations followed by TAK1 in vitro kinase assays revealed that uric acid molecules are capable of arresting TAK1 in an active-state conformation, resulting in sustained TAK1 kinase activation. Importantly, MSU-induced proinflammatory cytokine production was completely inhibited by 5Z-7-oxozeaenol but not IRAK1/4 or TRAF6 inhibitors. Administration of 5Z-7-oxozeaenol (5 or 15 mg/kg; orally) significantly inhibited MSU-induced paw inflammation in C57BL/6 mice. Our study identifies a novel post-translational mechanism of TAK1 activation by MSU and suggests the therapeutic potential of TAK1 in regulating MSU-induced inflammation.

Protective effects of Rhizoma smilacis glabrae extracts on potassium oxonate- and monosodium urate-induced hyperuricemia and gout in mice

BACKGROUND

Rhizoma smilacis glabrae (RSG, tufuling) has been widely used in traditional Chinese medicine for deoxidation, dampness relief, and easing joint movement. The chemical composition of RSG has been systematically confirmed, and some of its compounds have been revealed to possess antioxidant, anti-inflammatory, immunomodulatory, hypouricemic, and hepatoprotective effects.

PURPOSE

We aimed to clarify whether a RSG extract attenuates hyperuricemia, paw edema, and renal injury in mice with potassium oxonate (PO)- and monosodium urate (MSU)-induced chronic hyperuricemia and gout.

METHODS

RSG water extract was obtained and analyzed by HPLC-DAD-MS/MS. To establish a murine model with chronic hyperuricemia and gout, PO was orally administered daily from day 0 to day 24, whereas MSU was injected into the tibiotarsal joint on day 21. The mice in the drug intervention groups were treated once daily with doses of allopurinol or RSG extract from day 21 to day 24. The diameter of the ankle joints was measured with calipers. Serum TNF-α and IL-1β concentrations, hepatic XOD activity, and uric acid, creatinine, and blood urea nitrogen (BUN) levels were also determined. The right kidney and articular cavities were fixed, cut into sections, and stained with hematoxylin and eosin.

RESULTS

Nine compounds in the RSG water extract were unambiguously identified as 5-O-caffeoylshikimic acid, neoastilbin, astilbin, taxifolin, neoisoastilbin, isoastilbin, engeletin, isoengeletin, and trans-resveratrol. The RSGE treatment dose-dependently reduced PO- and MSU-induced paw edema, serum TNF-α, IL-1β, IL-6, IL-12, uric acid, and BUN, while significantly elevated serum IL-10, urinary uric acid and creatinine levels as compared with the respective values in the hyperuricemic and gouty mice group (vehicle group). Moreover, the hepatic XOD activity was dose-dependently reduced by the RSGE treatment. In addition, RSGE treatment not only ameliorated the infiltration of inflammatory cells, tubular dilation and vacuole formation in renal tubular, but also improved the synovial hyperplasia, reduced inflammatory cells infiltration into the synovium, and diminished the erosive damage in the cartilage.

CONCLUSION

The murine model with chronic hyperuricemia and gout be built in present study is consistent with the clinical symptoms of patients with long-standing hyperuricemia and acute gouty arthritis. RSG water extract has potent efficacy in ameliorating murine hyperuricemia and gout induced by PO and MSU.

Death of captive-bred vultures caused by flunixin poisoning in Italy

Among non steroidal anti-inflammatory drugs (NSAIDs) diclofenac is considered the main cause for the decline of vulture populations in the Indian subcontinent since the '90 s. Chemical analysis showed high levels of flunixin (31,350 μg/kg) in beef which three captive Gyps vultures fed on, later dying with severe visceral gout. Levels in dead vultures' organs and tissues ranged from 4 to 38.5 μg/kg. The typical lesions and the concentrations found in beef indicate flunixin as the cause of death. This is the first observational study which correlates the concentration of flunixin in the meat ingested with that found in tissues of vultures.

Evaluation of Turmeric Nanoparticles as Anti-Gout Agent: Modernization of a Traditional Drug

Background and objectives: Turmeric has assisted in the control of inflammation and pain for decades and has been used in combination with other nutraceuticals to treat acute and chronic osteoarthritis pain. Recently, the effect of turmeric, turmeric extract, or curcuminoids on musculoskeletal pain, either by themselves or in conjunction with other substances, has been reported. The aim of this study was to develop and characterize turmeric nanoparticles (T-NPs) for various parameters, both in vitro and in vivo. Materials and Methods: The T-NPs were successfully synthesized and characterized using particle size analysis, solubility improvement, SEM, EDX, X-ray diffraction, and in vivo antigout activity in mice model. Results: The T-NPs were of about 46 nm in size with a positive zeta potential +29.55 ± 3.44 and low polydispersity index (PDI) (0.264). Furthermore, the diseased mice, with induced gout via monosodium urate crystals, were treated with 5, 10, and 20 ppm T-NPs, administered orally, and the anti-gout potential was observed through measurement of joint diameter and changes in biochemical parameters, including lipid profile, renal function test, and liver function tests which significantly reduced the levels of these biochemical parameters. Conclusions: Uric acid levels were significantly reduced after the treatment with T-NPs. indicating that T-NPs show superior potential against gout management. Thus, T-NPs can be developed as an efficient antigout agent with minimum toxicities.

Metoprolol Increases Uric Acid and Risk of Gout in African Americans With Chronic Kidney Disease Attributed to Hypertension

BACKGROUND

There is little evidence guiding selection of nondiuretic, antihypertensive agents with a goal of lowering uric acid (SUA) and minimizing gout risk.

METHODS

In the African American Study of Kidney Disease and Hypertension (AASK) trial, African Americans with chronic kidney disease were randomly assigned to metoprolol (a beta-blocker), ramipril (an angiotensin-converting enzyme inhibitors [ACEi]), or amlodipine (a dihydropyridine calcium-channel blocker). SUA was measured at baseline and 12 months. Gout-related hospitalizations were based on ICD9 codes. Gout-related medication use (GRMs) was based on active prescriptions of allopurinol, colchicine, or probenecid during the baseline visit of the AASK cohort phase. We examined the effect of drug assignment on 12-month SUA (linear regression), gout-related hospitalization (Cox regression), and GRM (logistic regression).

RESULTS

Of the 630 participants, 40% were female with a mean age of 55 years (SD, 10), mean SUA of 8.2 mg/dl (2.0), and mean serum creatinine of 1.8 mg/dl (0.6). After 12 months, metoprolol increased SUA by 0.3 mg/dl, while ramipril or amlodipine had no effect on SUA. Compared to ramipril, metoprolol significantly increased 12-month SUA (0.40; 0.10, 0.70 mg/dl; P = 0.009), nonsignificantly increased risk of gout-related hospitalization (hazard ratio: 3.87; 0.82, 18.26; P = 0.09), and significantly increased the odds of GRM (odds ratio: 1.62; 1.03, 2.54; P = 0.04). While metoprolol was associated with a higher 12-month SUA compared with amlodipine (0.57; 0.18, 0.95; P = 0.004), there was no difference in gout-related hospitalizations or GRM.

CONCLUSIONS

Metoprolol increased SUA and GRM in African American adults. Health professionals treating patients with kidney disease at risk for gout should avoid metoprolol and possibly consider an ACEi.

CLINICAL TRIALS REGISTRATION

Trial Number NCT00582777.

A Comparative Study of Treatment-Emergent Adverse Events Following Use of Common Bowel Preparations Among a Colonoscopy Screening Population: Results from a Post-Marketing Observational Study

BACKGROUND

Colonoscopy may be one of the most frequent elective procedures in older adults and is associated with a low occurrence of complications. However, reduction of risks attributable to the bowel preparation may be achieved with the use of effective and safer products.

AIM

The aim of this study was to examine the incidence of treatment-emergent adverse events (TEAEs) associated with SUPREP(®) [oral sulfate solution (OSS)] and other common prescription bowel preparations (non-OSS).

METHODS

This real-world, observational study used de-identified health insurance claims and laboratory results to identify TEAEs in the 3 months following screening colonoscopy in adults with a prescription for a bowel preparation in the prior 60 days. The unadjusted and adjusted (controlling for patient risk factors) cumulative incidences of TEAEs were estimated using Kaplan-Meier and Poisson regression, respectively.

RESULTS

Among patients ≥45 years, the overall cumulative incidence was significantly lower (p < 0.001) in the OSS cohort than in the non-OSS cohort (unadjusted: 2.31 vs. 2.89 %; adjusted: 1.61 vs. 1.95 %), with significantly lower acute cardiac conditions (1.56 vs. 1.90 %; p < 0.001), renal failure/other serious renal diseases (OSS: 0.21 %, non-OSS: 0.32 %; p < 0.001), and serum electrolyte abnormalities (OSS: 0.39 %, non-OSS: 0.49 %; p = 0.017). There were no significant differences between cohorts in death, seizure disorders, aggravation of gout, and ischemic colitis. Results were similar in the adjusted cumulative incidences.

CONCLUSIONS

In actual use, the overall cumulative incidence of TEAEs was significantly lower in the OSS cohort, demonstrating that OSS is as safe as, or possibly safer than, non-OSS prescription bowel preparations.

The molecular insight into the antihyperuricemic and renoprotective effect of Shuang Qi gout capsule in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Shuang-Qi gout capsule, a traditional Chinese medicine prescription, has been used in the treatment of, gout arthritis, arthralgia and inflammation. Since renal urate overload associated with severe disability including gout, elimination of excess renal uric acid is highly essential. Therefore, in this study we evaluated the antihyperuricemic and the renoprotective effect of the Shuang Qi gout capsule (SQ) with elucidation of its mechanism.

MATERIALS AND METHODS

We assessed the antihyperuricemic activity of SQ on urinary and serum uric acid, creatinine, blood urea nitrogen, fractional excretion of uric acid (FEUA) and glomerular filtration rate of creatinine and uric acid in potassium oxonate (PO) - induced mice as well as in non-induced mice. To illuminate the mechanism of antihyperuricemic activity, we investigated renal transport activity and the expression of mRNA levels in PO-induced and non-induced mice by western blot and RT-PCR methods.

RESULTS

SQ showed significant reduction in serum uric acid, creatinine and blood urea nitrogen levels and marked elevation of urine uric acid, creatinine and FEUA levels only in hyperuricemic mice. Furthermore, SQ could recover the altered expressions of proteins and mRNA levels of all the main renal transporters significantly in dose dependent manner.

CONCLUSIONS

SQ could effectively regulate the main renal transporters denoted its denote probable antihyperuricemic mechanism of SQ and its dose dependent uricosuric effect. In addition, SQ attenuated the deleterious effects of hyperuricemia with renal dysfunction. Thus SQ could be a potent antihyperuricemic agent which can perform as a safer and effective agent in the management of hyperuricemia via regulating the renal transporters.

Arsenic exposure, hyperuricemia, and gout in US adults

BACKGROUND

There is very limited information on the association between arsenic and serum uric acid levels or gout. The aim of this study was to investigate the association of arsenic with hyperuricemia and gout in US adults.

METHODS

A cross-sectional study was conducted in 5632 adults aged 20years or older from the National Health and Nutrition Examination Survey (NHANES) 2003-2010 with determinations of serum uric acid and urine total arsenic and dimethylarsinate (DMA). Hyperuricemia was defined as serum uric acid higher than 7.0mg/dL for men and 6.0mg/dL for women. Gout was defined based on self-reported physician diagnosis and medication use.

RESULTS

After adjustment for sociodemographic factors, comorbidities and arsenobetaine levels, the increase in the geometric means of serum uric acid associated with one interquartile range increase in total arsenic and DMA levels was 3% (95% CI 2-5) and 3% (2-5), respectively, in men and 1% (0-3) and 2% (0-4), respectively, in women. In men, the adjusted odds ratio for hyperuricemia comparing the highest to lowest quartiles of total arsenic was 1.84 (95% CI, 1.26-2.68) and for DMA it was 1.41 (95% CI, 1.01-1.96). The corresponding odds ratios in women were 1.26 (0.77, 2.07) and 1.49 (0.96, 2.31), respectively. The odds ratio for gout comparing the highest to lowest tertiles was 5.46 (95% CI, 1.70-17.6) for total arsenic and 1.98 (0.64-6.15) for DMA among women older than 40years old. Urine arsenic was not associated with gout in men.

CONCLUSION

Low level arsenic exposures may be associated with the risk of hyperuricemia in men and with the prevalence of gout in women. Prospective research focusing on establishing the direction of the relationship among arsenic, hyperuricemia, and gout is needed.

Urate crystal induced inflammation and joint pain are reduced in transient receptor potential ankyrin 1 deficient mice--potential role for transient receptor potential ankyrin 1 in gout

Introduction

In gout, monosodium urate (MSU) crystals deposit intra-articularly and cause painful arthritis. In the present study we tested the hypothesis that Transient Receptor Poten-tial Ankyrin 1 (TRPA1), an ion channel mediating nociceptive signals and neurogenic in-flammation, is involved in MSU crystal-induced responses in gout by utilizing three experi-mental murine models.

Methods

The effects of selective pharmacological inhibition (by HC-030031) and genetic depletion of TRPA1 were studied in MSU crystal-induced inflammation and pain by using 1) spontaneous weight-bearing test to assess MSU crystal-induced joint pain, 2) subcutaneous air-pouch model resembling joint inflammation to measure MSU crystal-induced cytokine production and inflammatory cell accumulation, and 3) MSU crystal-induced paw edema to assess acute vascular inflammatory responses and swelling.

Results

Intra-articularly injected MSU crystals provoked spontaneous weight shift off from the affected limb in wild type but not in TRPA1 knock-out mice referring alleviated joint pain in TRPA1 deficient animals. MSU crystal-induced inflammatory cell infiltration and accumulation of cytokines MCP-1, IL-6, IL-1beta, MPO, MIP-1alpha and MIP-2 into subcu-taneous air-pouch (resembling joint cavity) was attenuated in TRPA1 deficient mice and in mice treated with the selective TRPA1 inhibitor HC-030031 as compared to control animals. Further, HC-030031 treated and TRPA1 deficient mice developed tempered inflammatory edema when MSU crystals were injected into the paw.

Conclusions

TRPA1 mediates MSU crystal-induced inflammation and pain in experimental models supporting the role of TRPA1 as a potential mediator and a drug target in gout flare.

Comparison of new-onset gout in adults prescribed chlorthalidone vs. hydrochlorothiazide for hypertension

This study assessed the risk of new-onset gout following prescribing of hydrochlorothiazide (HCTZ) compared with chlorthalidone (CTD). This retrospective cohort analysis used administrative claims from 2000 to 2012 to identify patients aged 18 to 89 years with hypertension who were prescribed CTD or HCTZ. Patients were excluded if they had a prior diagnosis of gout, conditions or prescription claims for medications that alter risk of gout, or if they switched between these two diuretics. A total of 1011 patients prescribed CTD were matched with 2022 patients prescribed HCTZ based on age, sex, and Chronic Condition Indicator. New-onset gout occurred in 17 of 1011 (1.68%) patients in the CTD group and in 26 of 2022 (1.29%) patients in the HCTZ group (P=.27). The number of days to first occurrence of gout was 183.6 days and 152.7 days in the CTD and HCTZ groups, respectively (P=.39). The mean daily dose was 22.7 mg for CTD and 24.3 mg for HCTZ, and the median dose of both CTD and HCTZ was 25 mg at the time of new-onset gout. Patients prescribed CTD for hypertension have a similar risk of developing new-onset gout compared with patients prescribed similar doses of HCTZ.

[Alcoholism, an addiction leading to multiple somatic complications]

Alcoholism is, after smoking, the most common addiction in our society. It is associated with multiple familial, social and professional negative consequences. In addition, alcohol disturbs cellular metabolism and its excessive chronic consumption may lead to multiple dysfunctions that can provoke somatic complications targeting numerous tissues or organs. The present article describes the most important ones involving the liver, the digestive tract, the heart, both the central and peripheral nervous system, and bone marrow. We also discuss the metabolic disturbances associated with chronic alcohol consumption, among which those affecting glucose regulation, lipid profile, uric acid and various vitamins. Finally, we describe the nutritional deficiencies that may be observed in alcoholic people and may contribute to aggravate somatic complications.

Antihypertensive drugs and risk of incident gout among patients with hypertension: population based case-control study

OBJECTIVE

To determine the independent associations of antihypertensive drugs with the risk of incident gout among people with hypertension.

DESIGN

Nested case-control study.

SETTING

UK general practice database, 2000-7.

PARTICIPANTS

All incident cases of gout (n = 24,768) among adults aged 20-79 and a random sample of 50,000 matched controls.

MAIN OUTCOME MEASURE

Relative risk of incident gout associated with use of antihypertensive drugs.

RESULTS

After adjusting for age, sex, body mass index, visits to the general practitioner, alcohol intake, and pertinent drugs and comorbidities, the multivariate relative risks of incident gout associated with current use of antihypertensive drugs among those with hypertension (n = 29,138) were 0.87 (95% confidence interval 0.82 to 0.93) for calcium channel blockers, 0.81 (0.70 to 0.94) for losartan, 2.36 (2.21 to 2.52) for diuretics, 1.48 (1.40 to 1.57) for β blockers, 1.24 (1.17 to 1.32) for angiotensin converting enzyme inhibitors, and 1.29 (1.16 to 1.43) for non-losartan angiotensin II receptor blockers. Similar results were obtained among those without hypertension. The multivariate relative risks for the duration of use of calcium channel blockers among those with hypertension were 1.02 for less than one year, 0.88 for 1-1.9 years, and 0.75 for two or more years and for use of losartan they were 0.98, 0.87, and 0.71, respectively (both P<0.05 for trend).

CONCLUSIONS

Compatible with their urate lowering properties, calcium channel blockers and losartan are associated with a lower risk of incident gout among people with hypertension. By contrast, diuretics, β blockers, angiotensin converting enzyme inhibitors, and non-losartan angiotensin II receptor blockers are associated with an increased risk of gout.

High versus low dosing of oral colchicine for early acute gout flare: Twenty-four-hour outcome of the first multicenter, randomized, double-blind, placebo-controlled, parallel-group, dose-comparison colchicine study

OBJECTIVE

Despite widespread use of colchicine, the evidence basis for oral colchicine therapy and dosing in acute gout remains limited. The aim of this trial was to compare low-dose colchicine (abbreviated at 1 hour) and high-dose colchicine (prolonged over 6 hours) with placebo in gout flare, using regimens producing comparable maximum plasma concentrations in healthy volunteers.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, parallel-group study compared self-administered low-dose colchicine (1.8 mg total over 1 hour) and high-dose colchicine (4.8 mg total over 6 hours) with placebo. The primary end point was > or = 50% pain reduction at 24 hours without rescue medication.

RESULTS

There were 184 patients in the intent-to-treat analysis. Responders included 28 of 74 patients (37.8%) in the low-dose group, 17 of 52 patients (32.7%) in the high-dose group, and 9 of 58 patients (15.5%) in the placebo group (P = 0.005 and P = 0.034, respectively, versus placebo). Rescue medication was taken within the first 24 hours by 23 patients (31.1%) in the low-dose group (P = 0.027 versus placebo), 18 patients (34.6%) in the high-dose group (P = 0.103 versus placebo), and 29 patients (50.0%) in the placebo group. The low-dose group had an adverse event (AE) profile similar to that of the placebo group, with an odds ratio (OR) of 1.5 (95% confidence interval [95% CI] 0.7-3.2). High-dose colchicine was associated with significantly more diarrhea, vomiting, and other AEs compared with low-dose colchicine or placebo. With high-dose colchicine, 40 patients (76.9%) had diarrhea (OR 21.3 [95% CI 7.9-56.9]), 10 (19.2%) had severe diarrhea, and 9 (17.3%) had vomiting. With low-dose colchicine, 23.0% of the patients had diarrhea (OR 1.9 [95% CI 0.8-4.8]), none had severe diarrhea, and none had vomiting.

CONCLUSION

Low-dose colchicine yielded both maximum plasma concentration and early gout flare efficacy comparable with that of high-dose colchicine, with a safety profile indistinguishable from that of placebo.

Gout Induced by Intoxication of Sodium Bicarbonate in Korean Native Broilers

Gout is a metabolic disorder that results in hyperuricemia and the deposition of positively birefringent monosodium urate crystals in various parts of the body. Intoxication of sodium bicarbonate (SBC) for 35 days in Korean native broilers was investigated. Sixty birds, aged 2 weeks, divided into 5 groups were exposed to excess SBC: 2 g/L (group A), 7.5 g/L (group B), 20 g/L (group C), 40 g/L (group D). Toxicopathological examination of all exposed birds revealed the manifestation of visceral and articular gout in group C, while birds of group D showed acute kidney damage with manifestation of excessive visceral gout. Interestingly, few birds in group D also showed signs of rare condition of acute articular gout. Dose-dependent increments in erythrocytic count, hematocrit values, and hemoglobin levels of the exposed birds were observed. Hypernatremia, hyperuricemia, hypokalemia, and hypochloremia were common findings among exposed birds. Microscopic examination of birds that manifested visceral gout revealed significant urate deposit, tubular necrosis, and tophi formation in renal interstitium. These findings provide a pathophysiological link that SBC intoxication may support hyperuricemia, which is an independent risk factor for gout and other renal dysfunctions. Further study is required to delineate the effect of lowering uric acid on progression of gout and other renal diseases.

Iatrogenic rheumatic syndromes in the elderly

Rheumatic complaints are common in the geriatric population. However, uncommonly autoimmune or musculoskeletal complaints and disorders may arise as a consequence of pharmacotherapy. These rare events include stain myopathy, drug-induced lupus, arthralgias, vasculitis, or tight skin syndromes. This article discusses the possible iatrogenic causes of rheumatic conditions, potential inciting agents, and the various types of rheumatic manifestations seen in the elderly.

Recent advances in crystal-induced acute inflammation

PURPOSE OF REVIEW

The aim of this article is to highlight recent advances suggesting essential involvement of the innate immune system in crystal-induced acute inflammation.

RECENT FINDINGS

Gout is a disease caused by the deposition of monosodium urate monohydrate crystals. Precise mechanisms underlying the initiation of monosodium urate monohydrate crystal-induced acute inflammation, however, are not known. Recent investigations provided novel evidence in the pathology of acute gout. Immunological study indicated that monosodium urate monohydrate crystals can act as a 'danger signal' that resembles exogenous adjuvants. Two laboratories have documented interesting findings that Toll-like receptor-mediated pathways or MyD88-dependent pathways are involved in monosodium urate monohydrate crystal-induced acute inflammation. Upregulation of the triggering receptor expressed on myeloid cells 1 (TREM-1) in phagocytes by the stimulation with monosodium urate monohydrate crystals has been demonstrated. Furthermore, pathological significance of NALP 3 inflammasome in gout has been shown. These findings provide a new concept that the innate immune system may play a crucial role on the triggering of crystal-induced acute inflammation. Spontaneous resolution is a characteristic feature of acute gout. Involvement of nuclear hormone receptors, peroxisome proliferator-activated receptor gamma and liver X receptor alpha, during the termination of acute gout has been also shown.

SUMMARY

These studies provided a new insight into the mechanisms underlying the initiation and the termination of monosodium urate monohydrate crystal-induced acute inflammation.

[Gout and diuretics; still an issue]

A recent case-control study on the effect of diuretics on the incidence ofgout included 70 cases, i.e. patients who had experienced their first attack of gout during a period of 8 years and 210 matched controls without gout. Of the 70 new gout cases, 14 had been using diuretics during the 8-year period for at least 3 consecutive months preceding the gouty attack. Regression analyses suggested that diuretics did not independently increase the risk of gout, and that the association between diuretics and gout was completely confounded by cardiovascular indications for diuretic therapy. It may be argued, however, that, taking into account the earlier reported relatively small increases in the incidence of gout at increasing levels of uric acid, the reviewed study lacks the statistical power needed to prove that diuretic therapy is not an independent risk factor for gout. Therefore, the generally accepted guideline still stands that if gout develops during diuretic therapy, this medication should be stopped if possible.

MyD88-dependent IL-1 receptor signaling is essential for gouty inflammation stimulated by monosodium urate crystals

While it is known that monosodium urate (MSU) crystals cause the disease gout, the mechanism by which these crystals stimulate this inflammatory condition has not been clear. Here we find that the Toll/IL-1R (TIR) signal transduction adaptor myeloid differentiation primary response protein 88 (MyD88) is required for acute gouty inflammation. In contrast, other TIR adaptor molecules, TIRAP/Mal, TRIF, and TRAM, are not required for this process. The MyD88-dependent TLR1, -2, -4, -6, -7, -9, and -11 and IL-18 receptor (IL-18R) are not essential for MSU-induced inflammation. Moreover, MSU does not stimulate HEK cells expressing TLR1-11 to activate NF-kappaB. In contrast, mice deficient in the MyD88-dependent IL-1R showed reduced inflammatory responses, similar to those observed in MyD88-deficient mice. Similarly, mice treated with IL-1 neutralizing antibodies also showed reduced MSU-induced inflammation, demonstrating that IL-1 production and IL-1R activation play essential roles in MSU-triggered inflammation. IL-1R deficiency in bone marrow-derived cells did not affect the inflammatory response; however, it was required in non-bone marrow-derived cells. These results indicate that IL-1 is essential for the MSU-induced inflammatory response and that the requirement of MyD88 in this process is primarily through its function as an adaptor molecule in the IL-1R signaling pathway.

Alcohol consumption as a trigger of recurrent gout attacks

BACKGROUND

Alcohol consumption has long been considered a trigger for recurrent gout attacks; however, this hypothesis has not been formally tested.

METHODS

We conducted an Internet-based case-crossover study to assess several putative risk factors, including alcohol consumption, thought to trigger recurrent gout attacks. Subjects who had an attack within the past year were recruited online and asked to provide access to medical records pertaining to their gout. Data were obtained on the amount and type of alcoholic beverage consumed on each day over the 2-day period before a gout attack and on each day over a 2-day period during the intercritical period. We examined the amount and type of alcohol consumption and the risk of recurrent gout attacks using a conditional logistic regression adjusting for diuretic use and purine intake.

RESULTS

A total of 197 subjects were recruited online over a 10-month period. Of those, 179 (91%) fulfilled the American College of Rheumatology Criteria for gout. Compared with no alcohol consumption, odds ratios for recurrent gout attacks were 1.1, 0.9, 2.0, and 2.5 for 1 to 2, 3 to 4, 5 to 6, and 7 or more drinks consumed over the 2-day period, respectively (P<.005). A dose-response relationship of risk of gout attacks was more evident for alcohol consumed over the last 24 hours. An increased risk of recurrent gout attacks was found for each type of beverage consumed.

CONCLUSION

Alcohol consumption triggers recurrent gout attacks. This effect was likely to occur within 24 hours after its consumption.

Recent diuretic use and the risk of recurrent gout attacks: the online case-crossover gout study

OBJECTIVE

To assess several putative risk factors, including thiazide and loop diuretics use, thought to trigger recurrent gout attacks.

METHODS

We conducted an internet-based case-crossover study involving subjects who had a gout attack within the past year. Patients were recruited online and asked to provide access to medical records. Data were obtained on specific diuretic use on each day over the 2-day period prior to an acute gout attack (hazard period) and on each day of 2 days during the intercritical period (control period). We examined the relation of all diuretic use and use of specific diuretics, i.e., thiazide and loop, to the risk of recurrent gout attacks using a conditional logistic regression model adjusting for alcohol consumption and purine intake.

RESULTS

One hundred ninety-seven subjects completed both control and hazard period questionnaires. Participants were predominantly male (80%) and over half had a college education. The median time between onset of gout attack and logging on to the website was 2 days. Adjusting for alcohol consumption and purine intake, the odds ratio (OR) for recurrent gout attacks from all diuretic use over the last 48 h was 3.6 (95% confidence interval 1.4-9.7). OR of recurrent gout attacks were 3.2 and 3.8 for use of thiazide and loop, respectively.

CONCLUSION

Recent use of diuretics is associated with a significantly increased risk for recurrent gouty arthritis. The increased risk of gout attacks from either thiazide or possibly loop diuretic therapies represents an important modifiable risk factor in patients with gout.

Clinicopathology of gout in growing layers induced by high calcium and high protein diets

1. An experiment was conducted to test the independent and combined effects of high dietary calcium and protein concentrations on the induction of visceral gout in growing birds of a layer strain. 2. One hundred and sixty healthy birds were randomly divided into 4 groups at 35 d of age. The different groups were given 4 diets containing normal or high concentrations of dietary calcium or crude protein in a 2 x 2 factorial experiment for 30 d. The diets contained normal calcium (Ca) and crude protein (CP) (NCNP, 8.5 g Ca/kg and 175g CP/kg), high calcium and normal protein (HC, 36.3 g Ca/kg and 175 g CP/kg), normal calcium and high protein (HP, 8.8 g Ca/kg and 245 g CP/kg) or high calcium and high protein (HCHP, 36.8 g Ca/kg and 242 g CP/kg), respectively. 3. Typical visceral gout was induced by the HCHP diet. The HCHP and HC diet caused severe kidney damage. The HP diet did not cause kidney damage, but significantly increased plasma uric acid and inorganic phosphorus concentrations. 4. The HC diet significantly increased plasma uric acid, calcium and sodium, but significantly decreased plasma inorganic phosphorus, potassium and magnesium concentrations. The HCHP diet significantly increased plasma uric acid, calcium and sodium. 5. Urine volumes were significantly higher on the HCHP and HC diets than on the control. The growers raised on HC and HCHP diets had significantly higher total quantity of 24 h urinary excretion of uric acid, calcium, magnesium, inorganic phosphorus and potassium and a significantly lower 24 h urinary excretion of sodium. The growers fed on the HP diet had a higher 24 h urinary excretion of uric acid and inorganic phosphorus than the control. 6. It is concluded that growing layer birds should not be fed on layer rations.

Gout-associated uric acid crystals activate the NALP3 inflammasome

Development of the acute and chronic inflammatory responses known as gout and pseudogout are associated with the deposition of monosodium urate (MSU) or calcium pyrophosphate dihydrate (CPPD) crystals, respectively, in joints and periarticular tissues. Although MSU crystals were first identified as the aetiological agent of gout in the eighteenth century and more recently as a 'danger signal' released from dying cells, little is known about the molecular mechanisms underlying MSU- or CPPD-induced inflammation. Here we show that MSU and CPPD engage the caspase-1-activating NALP3 (also called cryopyrin) inflammasome, resulting in the production of active interleukin (IL)-1beta and IL-18. Macrophages from mice deficient in various components of the inflammasome such as caspase-1, ASC and NALP3 are defective in crystal-induced IL-1beta activation. Moreover, an impaired neutrophil influx is found in an in vivo model of crystal-induced peritonitis in inflammasome-deficient mice or mice deficient in the IL-1beta receptor (IL-1R). These findings provide insight into the molecular processes underlying the inflammatory conditions of gout and pseudogout, and further support a pivotal role of the inflammasome in several autoinflammatory diseases.

New-Onset Gout after Kidney Transplantation: Incidence, Risk Factors and Implications

BACKGROUND

Although cyclosporine use has been associated with an increased risk of new-onset gout after renal transplantation, the incidence and risk factors for new-onset gout have not been reported in the era of modern immunosuppression.

METHODS

We conducted a retrospective cohort study of Medicare primary renal transplant patients reported in the United States Renal Data System (USRDS), using Medicare claims data to determine the incidence of new-onset gout. Cox regression analysis was used to calculate adjusted hazard ratios (AHR) for cyclosporine (including separate analysis of Neoral) compared directly with tacrolimus, for the risk of new-onset gout, adjusted for baseline demographic factors and posttransplant renal function.

RESULTS

The cumulative incidence of new-onset gout was 7.6% at 3 years posttransplant. The following factors were independently associated with an increased risk of new-onset gout: use of Neoral (vs. tacrolimus, AHR 1.25, 95% CI 1.07-1.47) at discharge, recipient male sex (AHR 1.44, 95% CI 1.25-1.67), older age, higher body mass index, and more recent year of transplant. No other immunosuppressive medications were associated with new-onset gout. Diabetes was associated with a significantly lower risk of new-onset gout. The development of new-onset gout was independently associated with decreased patient survival (AHR 1.26, 95% CI 1.08-1.47) as well as death-censored graft survival.

CONCLUSIONS

Cyclosporine is an independent risk factor for new-onset gout after transplantation. The incidence of new-onset gout appears to be increasing even while the use of cyclosporine is decreasing, and the development of new-onset gout was an independent predictor for death and graft loss in this population.

Gout, not induced by diuretics? A case-control study from primary care

BACKGROUND

It is taken for granted that diuretics may induce gout, but there is a general lack of evidence on this topic.

OBJECTIVES

To determine the incidence of gout in patients who use diuretics, taking into account concurrent hypertension and cardiovascular diseases.

METHODS

A case-control study was designed. From a primary care population all patients with a first gout registration (59 men, 11 women; mean (SD) age 55.1 (13.5)) were identified as cases. To relate the occurrence of gout to diuretic use a matched reference series of three controls for each case was compiled. Conditional logistic regression analyses were applied to estimate incidence rate ratios (IRRs) of gout, and 95% confidence intervals (CIs), in subjects with and without diuretic treatment, hypertension, and cardiovascular diseases. Additional stratification analyses were made, particularly in the subjects not using diuretics.

RESULTS

The IRRs of gout in subjects with v those without diuretic treatment, hypertension, heart failure, and myocardial infarction were 2.8 (95% CI 1.2 to 6.6), 2.6 (95% CI 1.2 to 5.6), 20.9 (95% CI 2.5 to 173.8), and 1.9 (95% CI 0.7 to 4.7), respectively. After adjustment, the IRR of gout for diuretic use dropped to 0.6 (95% CI 0.2 to 2.0), while the IRRs of gout for hypertension, heart failure, and myocardial infarction were still >1. This was also the case for subjects with hypertension or myocardial infarction, who had not used diuretics.

CONCLUSION

The results suggest that diuretics do not actually increase the risk of gout. Cardiovascular indications for treatment may have confounded previous inferences.