Pathogenesis of gout: Exploring more therapeutic target

Gout is a chronic metabolic and immune disease, and its specific pathogenesis is still unclear. When the serum uric acid exceeds its saturation in the blood or tissue fluid, it is converted to monosodium urate crystals, which lead to acute arthritis of varying degrees, urinary stones, or irreversible peripheral joint damage, and in severe cases, impairment of vital organ function. Gout flare is a clinically significant state of acute inflammation in gout. The current treatment is mostly anti-inflammatory analgesics, which have numerous side effects with limited treatment methods. Gout pathogenesis involves many aspects. Therefore, exploring gout pathogenesis from multiple perspectives is conducive to identifying more therapeutic targets and providing safer and more effective alternative treatment options for patients with gout flare. Thus, this article is of great significance for further exploring the pathogenesis of gout. The author summarizes the pathogenesis of gout from four aspects: signaling pathways, inflammatory factors, intestinal flora, and programmed cell death, focusing on exploring more new therapeutic targets.

Rare Case of Gout Leading to Septic Arthritis, Osteomyelitis, and Septic Shock in an Elderly Patient

Gout is a common, chronic inflammatory arthritis that oftentimes accompanies an initial acute and painful attack characterized by intense pain and swelling. Although it may present in different sites such as the ankles, wrists, knees, elbows, and fingers, the lower extremities are the most common site of involvement. The pathophysiology of gout is complex, but typically, the deposition of monosodium urate crystals within the joint space and the subsequent acute inflammatory response play an important role. Following an acute attack, chronic gout can present with tophi or nests of monosodium urate crystals surrounded by macrophages and multinucleated giant cells that trigger granulomatous inflammation. Progressively, chronic gout can lead to several other complications including joint destruction, gout nephropathy, spinal compression, and secondary infections. In this case report, we present an elderly female patient with chronic gout and multiple tophi formations in all digits of both of her hands. The tophi led to an ulceration and secondary septic arthritis and osteomyelitis of the right second digit. By the time the patient presented and was admitted to the hospital, she was in septic shock. We will review the pathogenesis of gout and other cases of concomitant septic arthritis and gout, as well as medical management and necessary surgical intervention as a means of treatment.

An Atypical Presentation of a Polyarticular Gout Flare: Case Report

A 54-year-old man with a history of hypertension, atrial fibrillation, chronic kidney disease, nonischemic cardiomyopathy, osteoarthritis, and gout presented to the emergency department (ED) with dysuria, painful scrotal swelling, severe bilateral flank pain, back pain, atraumatic right arm (elbow and distally) pain and swelling, and bilateral knee pain. His physical exam was notable for fever, tachycardia, bilateral costovertebral angle (CVA) tenderness, exquisite pain, erythema, and swelling of bilateral knees and the right arm (elbow and distally). He met Systemic Inflammatory Response Syndrome (SIRS) criteria, was placed on Ceftriaxone for presumed septic pyelonephritis, and was admitted to the medicine team. With initially unremarkable imaging studies, the differential diagnosis was broadened, and subsequent infectious workups yielded grossly normal results. At the end of hospital day one, the patient remained febrile and without symptomatic improvement. Rheumatology was consulted and empirically treated; the patient with a dose of Anakinra due to concerns about a polyarticular flare of crystalline arthropathy. Subsequent arthrocentesis confirmed a final diagnosis of a polyarticular gout flare. This case highlights the diagnostic challenges a polyarticular gout flare poses and the importance of early involvement of specialists for prompt recognition, treatment, and avoidance of unnecessary interventions.

Elevated serum CA72-4 predicts gout flares during urate lowering therapy initiation: a prospective cohort study

OBJECTIVE

Gout flares during urate-lowering therapy (ULT) initiation are common, but predictors of these flares are poorly understood. The aim of this study was to determine whether serum CA72-4 is an independent predictor for gout flares during ULT initiation.

METHODS

A prospective cohort study was conducted between March 2021 and January 2022. Men with gout, at least one gout flare in the past year, and at least three serum CA72-4 measurements in the previous six months were enrolled. Participants were grouped according to their highest recorded serum CA72-4 levels (above or within the normal range). All participants took oral febuxostat 20 mg daily without flare prophylaxis therapy, and attended face-to-face visits every four weeks until 24 weeks. The incidence of gout flare was compared between the two groups. Backward stepwise logistic regression analyses were used to identify risk factors associated with flares. Receiver operating characteristic curve analysis was used to evaluate prediction efficacy.

RESULTS

A total of 193 completed the study (79 with high CA72-4; 114 with normal CA72-4). The cumulative incidence of at least one gout flare was 48.1% (62.1% in the high CA72-4 group, 38.4% in the normal CA72-4 group, P = 0.001), and recurrent (≥2) flares was 33.0% (47.1% in the high CA72-4 group, 23.2% in the normal CA72-4, P < 0.001). High CA72-4, disease duration, intra-articular tophus size, glucose, high-density lipoprotein-cholesterol and ESR were independent risk factors for gout flares. Serum CA72-4 alone predicted recurrent flares with an area under the curve of 0.63 (95% CI = 0.54, 0.71), and 0.78 (95% CI = 0.71, 0.85) when combined with other independent variables.

CONCLUSION

High serum CA72-4 predicts the risk of gout flares during ULT initiation.

TRIAL REGISTRATION

ChiCTR; https://www.chictr.org.cn/; ChiCTR2100043573.

A 55-Year-Old Male With Systemic Gout Complicated by Septic Shock

Tophaceous gout is the systemic deposition of uric acid which can induce cutaneous ulceration. We present the case of a 55-year-old male with chronic tophaceous gout whose initial presentation was complicated by septic shock due to methicillin-sensitive Streptococcus aureus bacteremia and superinfection of many of his affected joints. The case and discussion will focus on the extent of his infections and approaches to preventative care.

Gout in an Obese Patient with Nonalcoholic Steatohepatitis on a Thiazide Diuretic and Association Between Hyperuricemia and Nonalcoholic Steatohepatitis: A Case Report

Gout is a common inflammatory arthritis caused by increased uric acid crystals in and around various joints, mainly the big toe in adults. It happens due to the increase of urate or uric acid levels either because of increased production or decreased excretion from the body. Uric acid is the final product of purine metabolism, and many patients with hyperuricemia may remain asymptomatic. We present a case of a 46-year-old male who presented to the ambulatory care unit with the clinical features of acute pharyngitis and left toe pain for the past three days. On further questioning, he added that he had pain in the left lumber region and left side of the toe for the past few months. He also had a known case of type 2 diabetes mellitus, hypertension, and gastritis, for which he has been taking the thiazide diuretic, angiotensin-converting enzyme (ACE) inhibitors, metformin, sitagliptin, aspirin, and atorvastatin. Laboratory tests showed elevated uric acid along with raised inflammatory markers. As a result, he was referred to the specialist for arthrocentesis in order to confirm the diagnosis, and the thiazide diuretic was replaced with calcium channel blockers. He also suffered from nonalcoholic steatohepatitis (NASH) based on his ultrasound abdomen. On the follow-up visit, his symptoms had resolved, and his uric acid level had normalized.

Dual-Energy Computed Tomography (DECT) Resolves the Diagnostic Dilemma in an Atypically Presenting Case of Gout

Gout is a common inflammatory arthropathy that presents as acute monoarthritis, most commonly of the first metatarsophalangeal (MTP) joint. Chronic polyarticular involvement may lead to confusion with other inflammatory arthropathies, including rheumatoid arthritis (RA). A thorough history, physical examination, synovial fluid analysis, and imaging are keys to establishing a correct diagnosis. Although a synovial fluid analysis remains the gold standard, the affected joints may be difficult to access by arthrocentesis. In cases where a large monosodium urate (MSU) crystal deposition is in the soft tissues - the ligaments, bursae, and tendons, it becomes a clinical impossibility. In such cases, dual-energy computed tomography (DECT) can assist in differentiating gout from other inflammatory arthropathies, including RA. Additionally, DECT can perform quantitative analysis of tophaceous deposits and, therefore, assess response to treatment.

Effectiveness and safety of anakinra in gouty arthritis: A case series and review of the literature

Background

Gout is the most common type of inflammatory arthritis. Nonsteroidal anti-inflammatory drugs, corticosteroids, and colchicine are the first-line agents, although they are contraindicated in many patients. Blockade of IL-1 with anakinra can be an alternative.

Objective

To present a case series of 10 difficult-to-treat gout patients treated with anakinra and perform a scoping review of the effectiveness and safety of anakinra in gout patients.

Methods

A total of 1,519 citations were screened. The reviewers ran a two-stage screening process by title/abstract and full-text reading. Thirty-eight articles finally met the selection criteria and were included for data extraction and synthesis. Experience in difficult-to treat and complex clinical scenarios, such as active infection, hemodialysis, and transplantation, were specifically described.

Results

The study sample comprised 551 patients, from whom 648 flares were finally analyzed. The mean age was 57.9 years, and 82.9% were men. The clinical presentation was polyarticular in 47.5% and tophaceous in 66.9%. Sixty-five patients with an active infection, 41 transplanted patients and 14 in haemodyalisis treated with anakinra are described. More than half of the patients had >1 associated comorbidity. Anakinra was effective both for flares (94%) and for long-term treatment (91%) and well tolerated. In the case of flares, 34 (6.7%) adverse effects were registered. Adverse events were more prevalent in long-term treatment.

Conclusion

Anakinra was effective and safe for management of gout flares in difficult-to-treat patients. It has been used in multiple complex scenarios, such as active infections, dialysis, transplantation, chronic kidney disease, and polyarticular gout. Anakinra has also proven effective as long-term treatment, although there are more concerns about its safety.

Purinergic Signaling in the Regulation of Gout Flare and Resolution

Gout flares require monosodium urate (MSU) to activate the NLRP3 inflammasome and secrete sufficient IL-1β. However, MSU alone is not sufficient to cause a flare. This is supported by the evidence that most patients with hyperuricemia do not develop gout throughout their lives. Recent studies have shown that, besides MSU, various purine metabolites, including adenosine triphosphate, adenosine diphosphate, and adenosine bind to different purine receptors for regulating IL-1β secretion implicated in the pathogenesis of gout flares. Purine metabolites such as adenosine triphosphate mainly activate the NLRP3 inflammasome through P2X ion channel receptors, which stimulates IL-1β secretion and induces gout flares, while some purine metabolites such as adenosine diphosphate and adenosine mainly act on the G protein-coupled receptors exerting pro-inflammatory or anti-inflammatory effects to regulate the onset and resolution of a gout flare. Given that the purine signaling pathway exerts different regulatory effects on inflammation and that, during the inflammatory process of a gout flare, an altered expression of purine metabolites and their receptors was observed in response to the changes in the internal environment. Thus, the purine signaling pathway is involved in regulating gout flare and resolution. This study was conducted to review and elucidate the role of various purine metabolites and purinergic receptors during the process.

A Man With Intractable Back Pain, Spondylodiscitis: A Case Report of Uncommon Site of Spinal Gout

Gout typically affects the peripheral joints but uncommonly can involve the axial skeleton and rarely the intervertebral discs. We present a rare case of gouty spondylodiscitis affecting the intervertebral disc in the lumbar spine. Our patient with a gout history not on any maintenance therapy presented intractable right-sided back pain radiating to the right lower extremity. Computed tomography scan findings were consistent with spondylosis, while magnetic resonance imaging showed concern of infectious discitis. Initially, he was treated for infectious discitis with IV antibiotics. Biopsy of the L5-S1 disc space revealed monosodium urate crystals, confirming the diagnosis of gouty spondylodiscitis. He was managed with IV dexamethasone and recovered well on a tapering dose of steroids and colchicine followed by allopurinol once acute flare resolved.

The GOUT-36 prediction rule for inpatient gout flare in people with comorbid gout: derivation and external validation

OBJECTIVES

To develop and validate a gout flare risk stratification tool for people with gout hospitalised for non-gout conditions.

METHODS

The prediction rule for inpatient gout flare was derived from a cohort of 625 hospitalised people with comorbid gout from New Zealand. The rule had four items: (1) no pre-admission GOut flare prophylaxis, (2) no pre-admission Urate-lowering therapy, (3) Tophus and (4) pre-admission serum urate >0.36 mmol/l within the previous year (GOUT-36 rule). Two or more items are required for the classification of high risk for developing inpatient gout flare. The GOUT-36 rule was validated in a prospective cohort of 284 hospitalised people with comorbid gout from Thailand and China.

RESULTS

The GOUT-36 rule had a sensitivity of 75%, specificity of 67% and AUC of 0.71 for classifying people at high risk for developing inpatient gout flare. Four risk groups were developed: low (no items), moderate (one item), high (two items) and very high risk (three or four items). In a population with frequent (overall 34%) in-hospital gout flare, 80% of people with very high risk people developed flare, while 11% of low-risk people had inpatient flare.

CONCLUSION

GOUT-36 rule is simple and sensitive for classifying people with high risk for inpatient gout flare. The rule may help inform clinical decision and future research on the prevention of inpatient gout flare.

Cardiovascular safety risks associated with gout treatments

INTRODUCTION

Uric acid is the final byproduct of purine metabolism. The loss of the enzyme that hydrolyzes uric acid to allantoin was lost, leading to a decrease in uric acid excretion and its further accumulation. The buildup of uric acid leads to damage in different organ systems, including the cardiovascular system. With the increasing burden of cardiovascular disease worldwide, a growing body of evidence has addressed the relationship between urate, cardiovascular outcomes, and gout medication cardiovascular safety. Areas covered: We discuss the most common gout therapies used for the reduction of serum urate and management of gout flares in different observational and clinical trials and their effects on different aspects of cardiovascular disease. We selected the most representative clinical studies that evaluated cardiovascular outcomes with each gout therapy as well as recommendation given by the most representative guidelines from Rheumatology societies for the management of gout.

EXPERT OPINION

The treatment of gout reduces joint damage and it can also lessen CV morbidity. Allopurinol shows CV safety profile when compared to other ULTs. Evidence supporting CV safety with the use of colchicine and IL-1 agents is promising and research needs to be conducted to further assess this outcome.

Successful Treatment of Covid-19 Associated Cytokine Release Syndrome with Colchicine. A Case Report and Review of Literature

We describe the case of a 42 year old, healthy patient with Covid-19 who despite improvement in his respiratory symptoms developed a mild to moderate cytokine release syndrome (CRS) and an associated monoarticular gout flare. Since the patient refused admission to the hospital and had stable vital signs, we chose to treat him with a safe anti-inflammatory and non-immunosuppressive therapy. To hit two birds with one stone, we considered colchicine, as it has systemic anti-inflammatory effects and is also effective in gout flare. Unexpectedly, 48 hours after treatment, not only did his ongoing fever and toe pain disappear, he also had significant improvements in his general state of health and all his inflammatory markers including fibrinogen, ferritin, D-dimer, and IL-6 levels normalized. To our knowledge, the use of colchicine in Covid-19 and CRS has not been reported. This observation merits the consideration of colchicine as a safe, inexpensive and oral medication for the treatment of mild to moderate CRS in Covid-19 patients. More importantly, in Covid-19 patients with early lung involvement colchicine may be an appropriate candidate to prevent CRS in adjunction with routine antiviral agents. Indeed, multicenter, randomized controlled studies are required to evaluate the benefits of this therapy.

Development of a prediction model for inpatient gout flares in people with comorbid gout

OBJECTIVES

Hospitalisation is a risk factor for flares in people with gout. However, the predictors of inpatient gout flare are not well understood. The aim of this study was to develop a prediction model for inpatient gout flare among people with comorbid gout.

METHODS

We used data from a retrospective cohort of hospitalised patients with comorbid gout from Wellington, Aotearoa/New Zealand, in 2017 calendar year. For the development of a prediction model, we took three approaches: (A) a clinical knowledge-driven model, (B) a statistics-driven model and (C) a decision tree model. The final model was chosen based on practicality and performance, then validated using bootstrap procedure.

RESULTS

The cohort consisted of 625 hospitalised patients with comorbid gout, 87 of whom experienced inpatient gout flare. Model A yielded 9 predictors of inpatient gout flare, while model B and C produced 15 and 5, respectively. Model A was chosen for its simplicity and superior C-statistics (0.82) and calibration slope (0.93). The final nine-item set of predictors were pre-admission urate >0.36 mmol/L, tophus, no pre-admission urate-lowering therapy (ULT), no pre-admission gout prophylaxis, acute kidney injury, surgery, initiation or increase of gout prophylaxis, adjustment of ULT and diuretics prior to flare. Bootstrap validation of the final model showed adequate C-statistics and calibration slope (0.80 and 0.78, respectively).

CONCLUSION

We propose a set of nine predictors of inpatient flare for people with comorbid gout. The predictors are simple, practical and are supported by existing clinical knowledge.

Trans-Chalcone Attenuates Pain and Inflammation in Experimental Acute Gout Arthritis in Mice

Gouty arthritis is characterized by an intense inflammatory response to monosodium urate crystals (MSU), which induces severe pain and reduction in the life quality of patients. Trans-Chalcone (1,3-diphenyl-2-propen-1-one) is a flavonoid precursor presenting biological activities such as anti-inflammatory and antioxidant proprieties. Thus, the aim of this work was to evaluate the protective effects of trans-Chalcone in experimental gout arthritis in mice. Mice were treated with trans-Chalcone (3, 10, or 30 mg/kg, per oral) or vehicle (Tween 80 20% plus saline) 30 min before intra-articular injection of MSU (100 μg/knee joint, intra-articular). We observed that trans-Chalcone inhibited MSU-induced mechanical hyperalgesia, edema, and leukocyte recruitment (total leukocytes, neutrophils, and mononuclear cells) in a dose-dependent manner. Trans-Chalcone also decreased inflammatory cell recruitment as observed in Hematoxylin and Eosin (HE) staining and the intensity of fluorescence of LysM-eGFP+ cells in the confocal microscopy. Trans-Chalcone reduced MSU-induced oxidative stress as observed by an increase in the antioxidant defense [Glutathione (GSH), Ferric Reducing (FRAP), and 2,2’-Azinobis-3-ethylbenzothiazoline 6-sulfonic acid (ABTS assays)] and reduction in reactive oxygen and nitrogen species production [superoxide anion (NBT assay) and nitrite (NO assay)]. Furthermore, it reduced in vivo MSU-induced interleukin-1β (IL-1β), Tumor necrosis factor-α (TNF-α), and IL-6 production, and increased Transforming growth factor-β (TGF-β) production. Importantly, trans-Chalcone reduced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation and thereby the mRNA expression of the inflammasome components Nlrp3 (cryopyrin), Asc (apoptosis-associated speck-like protein containing a CARD), Pro-caspase-1 and Pro-IL-1β. In vitro, trans-Chalcone reduced the MSU-induced release of IL-1β in lipopolysaccharide (LPS)-primed macrophages. Therefore, the pharmacological effects of trans-Chalcone indicate its therapeutic potential as an analgesic and anti-inflammatory flavonoid for the treatment of gout.

Management of Gout and Hyperuricemia in CKD

Hyperuricemia and gout, the clinical manifestation of monosodium urate crystal deposition, are common in patients with chronic kidney disease (CKD). Although the presence of CKD poses additional challenges in gout management, effective urate lowering is possible for most patients with CKD. Initial doses of urate-lowering therapy are lower than in the non-CKD population, whereas incremental dose escalation is guided by regular monitoring of serum urate levels to reach the target level of <6mg/dL (or <5mg/dL for patients with tophi). Management of gout flares with presently available agents can be more challenging due to potential nephrotoxicity and/or contraindications in the setting of other common comorbid conditions. At present, asymptomatic hyperuricemia is not an indication for urate-lowering therapy, though emerging data may support a potential renoprotective effect.

Validation of claims-based algorithms for gout flares

PURPOSE

Gout is a common inflammatory arthritis characterized by repeated acute flares. The ability to accurately identify gout flares is critical for comparative effectiveness studies of gout treatments. We developed and examined the accuracy of a claims-based algorithm to identify gout flares.

METHODS

Patients receiving care at an academic medical center between 2006 and 2010 with a diagnosis of gout or hyperuricemia were selected using an electronic medical record-Medicare claims linked dataset. Gout flares were identified by several claims-based algorithms using a diagnosis of gout combined with gout-related medication claims and/or procedure codes for arthrocentesis or joint injection. We calculated positive predictive value of these algorithms based on physician documentation of gout flare in medical record as the gold standard. Negative predictive value of the gout flare algorithm was calculated in a randomly selected subgroup of 200 patients with gout.

RESULTS

Among 3952 subjects with gout or hyperuricemia, 503 flares were identified using the medication-based algorithm, and 290 were identified using the procedure-based algorithm. The positive predictive value for gout flares ranged from 50-54% for the medication-based algorithms and 59-68% for the procedure-based algorithms. The negative predictive value of the algorithm combining both medication and procedure claims was high (85.2%).

CONCLUSION

Use of gout diagnosis codes in combination with medication dispensing or procedure codes did not appear to accurately capture gout flares in patients with gout in a claims database. However, the claims-based flare algorithm could be useful in identifying a cohort of gout patients with no flares. Copyright © 2016 John Wiley & Sons, Ltd.