Effect of Clinical Typing on Serum Urate Targets of Benzbromarone in Chinese Gout Patients: A Prospective Cohort Study

IntroductionAchieving a goal of serum urate levels in patients with gout is an important way to prevent gout and its complications while it remains difficult with a low targeting rate worldwidely. Currently, hyperuricemia classification has not been widely applied to the management of gout owing to insufficient clinical evidences. This study aimed to evaluate the effectiveness of achieving target urate based on hyperuricemia classification in Chinese patients with gout.MethodsIn this prospective study, patients with gout receiving urate lowering therapy with benzbromarone were assigned to two groups, a renal underexcretion and an unclassified type. The primary endpoint was the proportion of patients achieving the serum urate target (<360 μmol/L) during the 12-week study. The frequency of acute gout attacks as well as physical and chemical indicators were secondary endpoints.ResultsTarget serum urate level was achieved in 60.5% of underexcretors compared with 39.0% of patients of the unclassified type at week 12 (P = 0.002). Blood glucose and cholesterol levels were lower in the underexcretor group compared with the unclassified type group at the end of the trial, without significant different frequencies in gout flare during the study. In subgroup analysis, stratified by body mass index and estimated glomerular filtration rate, the proportion of patients with serum urate <360 μmol/L was greater in the underexcretion compared with the unclassified type group.ConclusionsThe increased achievement of target serum urate in the underexcretion group supports the use of a clinical hyperuricemia typing treatment strategy for gout.

Remission in Gout: Concepts From a Patient Perspective

Any human who has ever experienced an acute gout flare understands how painful and debilitating this condition is. Unfortunately, due to the episodic nature of these acute flares that occur randomly due to transient fluctuations in urate levels, patients often underreport these attacks.

Hospital admission risk stratification of patients with gout presenting to the emergency department

To characterise gout patients at high risk of hospitalisation and to develop a web-based prognostic model to predict the likelihood of gout-related hospital admissions. This was a retrospective single-centre study of 1417 patients presenting to the emergency department (ED) with a gout flare between 2015 and 2017 with a 1-year look-back period. The dataset was randomly divided, with 80% forming the derivation and the remaining forming the validation cohort. A multivariable logistic regression model was used to determine the likelihood of hospitalisation from a gout flare in the derivation cohort. The coefficients for the variables with statistically significant adjusted odds ratios were used for the development of a web-based hospitalisation risk estimator. The performance of this risk estimator model was assessed via the area under the receiver operating characteristic curve (AUROC), calibration plot, and brier score. Patients who were hospitalised with gout tended to be older, less likely male, more likely to have had a previous hospital stay with an inpatient primary diagnosis of gout, or a previous ED visit for gout, less likely to have been prescribed standby acute gout therapy, and had a significant burden of comorbidities. In the multivariable-adjusted analyses, previous hospitalisation for gout was associated with the highest odds of gout-related admission. Early identification of patients with a high likelihood of gout-related hospitalisation using our web-based validated risk estimator model may assist to target resources to the highest risk individuals, reducing the frequency of gout-related admissions and improving the overall health-related quality of life in the long term. Key points • We reported the characteristics of gout patients visiting a tertiary hospital in Singapore. • We developed a web-based prognostic model with non-invasive variables to predict the likelihood of gout-relatedhospital admissions.

Recombinant Human Proteoglycan 4 Regulates Phagocytic Activation of Monocytes and Reduces IL-1β Secretion by Urate Crystal Stimulated Gout PBMCs

ObjectivesTo compare phagocytic activities of monocytes in peripheral blood mononuclear cells (PBMCs) from acute gout patients and normal subjects, examine monosodium urate monohydrate (MSU) crystal-induced IL-1β secretion ± recombinant human proteoglycan 4 (rhPRG4) or interleukin-1 receptor antagonist (IL-1RA), and study the anti-inflammatory mechanism of rhPRG4 in MSU stimulated monocytes.MethodsAcute gout PBMCs were collected from patients in the Emergency Department and normal PBMCs were obtained from a commercial source. Monocytes in PBMCs were identified by flow cytometry. PBMCs were primed with Pam3CSK4 (1μg/mL) for 24h and phagocytic activation of monocytes was determined using fluorescently labeled latex beads. MSU (200μg/mL) stimulated IL-1β secretion was determined by ELISA. Reactive oxygen species (ROS) generation in monocytes was determined fluorometrically. PBMCs were incubated with IL-1RA (250ng/mL) or rhPRG4 (200μg/mL) and bead phagocytosis by monocytes was determined. THP-1 monocytes were treated with MSU crystals ± rhPRG4 and cellular levels of NLRP3 protein, pro-IL-1β, secreted IL-1β, and activities of caspase-1 and protein phosphatase-2A (PP2A) were quantified. The peritoneal influx of inflammatory and anti-inflammatory monocytes and neutrophils in Prg4 deficient mice was studied and the impact of rhPRG4 on immune cell trafficking was assessed.ResultsEnhanced phagocytic activation of gout monocytes under basal conditions (p<0.001) was associated with ROS generation and MSU stimulated IL-1β secretion (p<0.05). rhPRG4 reduced bead phagocytosis by normal and gout monocytes compared to IL-1RA and both treatments were efficacious in reducing IL-1β secretion (p<0.05). rhPRG4 reduced pro-IL-1β content, caspase-1 activity, conversion of pro-IL-1β to mature IL-1β and restored PP2A activity in monocytes (p<0.05). PP2A inhibition reversed rhPRG4’s effects on pro-IL-1β and mature IL-1β in MSU stimulated monocytes. Neutrophils accumulated in peritoneal cavities of Prg4 deficient mice (p<0.01) and rhPRG4 treatment reduced neutrophil accumulation and enhanced anti-inflammatory monocyte influx (p<0.05).ConclusionsMSU phagocytosis was higher in gout monocytes resulting in higher ROS and IL-1β secretion. rhPRG4 reduced monocyte phagocytic activation to a greater extent than IL-1RA and reduced IL-1β secretion. The anti-inflammatory activity of rhPRG4 in monocytes is partially mediated by PP2A, and in vivo, PRG4 plays a role in regulating the trafficking of immune cells into the site of a gout flare.

Effects of washed microbiota transplantation on serum uric acid levels, symptoms and intestinal barrier function in patients with acute and recurrent gout: a pilot study

Introduction: Gut dysbiosis has been reported to be closely associated with gout. Washed microbiota transplantation (WMT) is considered as an effective way to restore a healthy gut microbiota with less adverse events than the conventional fecal microbiota transplantation. In this study, we aimed to evaluate the effects of WMT on serum uric acid levels, symptoms and the intestinal barrier function in patients with acute and recurrent gout. Methods: We performed a pilot study of WMT for acute and recurrent gout. The primary outcome was the changes in serum uric acid level and gout symptoms. The secondary outcomes included the changes in levels of diamine oxidase (DAO), D-lactic acid and endotoxin. Results: Eleven patients received WMT treatment. The averaged serum uric acid levels in patients with gout reduced after WMT (P = 0.031), accompanied with a decrease in the frequency and duration time of acute gout flares (P < 0.01). The levels of DAO, D-lactic acid and endotoxin were higher in patients than in healthy donors (P < 0.05). After WMT treatment, the levels of DAO and endotoxin decreased (P < 0.05). Conclusions: WMT is effective for reducing serum uric acid levels and improving gout symptoms in patients with gout, and contributes to improve their impaired intestinal barrier function.

The Role of TGFβ1 and Macrophage Differentiation in MSU Crystal-Induced Inflammation

<p>Gout is a painful form of inflammatory arthritis that is caused by the deposition of monosodium urate (MSU) crystals in the joints. MSU crystals trigger a local inflammatory response initiated by resident macrophages followed by a large infiltration of leukocytes. The spontaneous resolution of acute gout is associated with the production of transforming growth factor β1 (TGFβ1). The overall objectives of this thesis were to investigate mechanisms that lead to TGFβ1 production and contribute to the resolution of acute gout, the effect of TGFβ1 on the functional phenotype of differentiated macrophages, and possible changes in surface marker expression by macrophages in response to MSU crystals. To determine macrophage-independent sources of TGFβ1 during the resolution of acute gout and how TGFβ1 production altered MSU crystal-recruited neutrophil functions, neutrophils were purified from MSU crystal-treated mice when levels of TGFβ1 were high. MSU crystal-recruited neutrophils and circulating blood neutrophils were identified as TGFβ1⁺ cells. The mechanism for TGFβ1 production by neutrophils was associated with their ability to phagocytose apoptotic neutrophils. TGFβ1 produced by canibalising neutrophils inhibited both respiratory burst and interleukin-1β (IL-1β) production by MSU crystal-activated neutrophils ex vivo. Importantly, neutrophils from MSU crystal-challenged mice treated with TGFβ1 neutralising antibody in vivo produced elevated levels of superoxide but neutrophil IL-1β production was unaffected. These results show that TGFβ1 produced by canibalising neutrophils can actively suppress neutrophil inflammatory functions and therefore make a significant contribution towards the resolution of gouty inflammation. To investigate the effect of TGFβ1 on macrophage differentiation in vitro, granulocyte macrophage colony-stimulating factor (GM-CSF) bone marrow macrophages (GM-BMMs) and macrophage colony-stimulating factor (M-CSF) bone marrow macrophages (M-BMMs) were generated in the presence of TGFβ1. TGFβ1 was found to drive a hyper-inflammatory GM-BMM phenotype, while contributing to the differentiation of a hypo-inflammatory M-BMM phenotype specifically in response to MSU crystals. Increased IL-1β production by TGFβ1-differentiated GM-BMMs was associated with enhanced NOD like receptor family, pyrin domain-containing 3 (NLRP3) in ammasome activation and caspase 1/caspase 8 interaction, and a down-regulation of receptor-interacting serine/threonine-protein kinase 3 (RIP3) triggered by MSU crystals. At the same, TGFβ1 inhibited antigen-specific T cell proliferation by GM-BMMs. In contrast, TGFβ1-treated M-BMMs down-regulated the expression of active IL-1β that correlated with decreased IL-1β production, and upregulated RIP3 expression in response to MSU crystals. These data indicate that TGFβ1-treated GM-BMMs exhibited a hyper-inflammatory response to MSU crystal stimulation, whereas M-BMMs were found to be hypo-responsive. Macrophages were found to upregulate the surface marker NK1.1, which is primarily expressed on natural killer (NK) cells, and occured as a consequence of phagocytosis. Following phagocytosis of MSU crystals, activated macrophages produced IL-1β and tumour necrosis factor ⍺ (TNF⍺), which triggered the upregulation of NK1.1 expression. Macrophage NK1.1 expression is an activation-driven event specifc to MSU crystals. However, phagocytosis of apoptotic neutrophils also triggered the upregulation of NK1.1 by macrophages, a non-inflammatory event that is characteristic for the resolution of acute inflammation. These findings suggest that macrophages may develop NK cell-like properties initiated by an activation-driven or apoptotic cell clearance mechanism. Taken together, the results of this thesis indicate that canibalising neutrophils self-regulate their inflammatory functions via TGFβ1 and that TGFβ1 drives a hyper-inflammatory GM-BMM phenotype, while shutting down inflammatory functions of M-BMMs. These data highlight a regulatory role for TGFβ1 during acute gouty inflammation.</p>