Pegloticase and lowering blood pressure in refractory gout; is it uric acid or hydrogen peroxide?

Biomimetic bioreactor for potentiated uricase replacement therapy in hyperuricemia and gout

Introduction

Uricase replacement therapy is a promising approach for managing hyperuricemia and gout but is hindered by challenges such as short blood circulation time, reduced catalytic activity, and excessive hydrogen peroxide (H2O2) production. These limitations necessitate innovative strategies to enhance therapeutic efficacy and safety.

Methods

We designed and synthesized RBC@SeMSN@Uri, a red blood cell-coated biomimetic self-cascade bioreactor, which encapsulates uricase (Uri) and a selenium-based nano-scavenger (SeMSN) within RBC membranes. This design aims to reduce immunogenicity, extend systemic circulation, and maintain enzymatic activity. In vitro assays were conducted to evaluate biocompatibility, anti-inflammatory effects, and oxidative stress protection. In vivo experiments in hyperuricemia and gout models assessed therapeutic efficacy, biodistribution, and biosafety.

Results

RBC@SeMSN@Uri effectively degraded uric acid (UA) into allantoin and converted H2O2 into water, preventing oxidative damage and inflammation. In vitro assays demonstrated excellent biocompatibility and reduced H2O2-induced inflammatory responses compared to free uricase. In vivo, the bioreactor prolonged circulation time, significantly reduced uric acid levels, alleviated kidney damage, and mitigated symptoms of hyperuricemia and gout. It also targeted inflamed joints, reducing swelling and inflammation in gouty arthritis models.

Discussion

This study presents RBC@SeMSN@Uri as a novel biomimetic strategy for enzyme replacement therapy in hyperuricemia and gout. By integrating uricase and selenium-based nano-scavenger within RBC membranes, the bioreactor addresses key limitations of traditional therapies, offering enhanced stability, reduced immunogenicity, and superior therapeutic efficacy. This platform holds potential for broader applications in protein or antibody delivery for enzyme replacement therapies in other diseases.

U-shaped association of uric acid to overall-cause mortality and its impact on clinical management of hyperuricemia

Serum uric acid (SUA) is significantly elevated in obesity, gout, type 2 diabetes mellitus, and the metabolic syndrome and appears to contribute to the renal, cardiovascular and pulmonary comorbidities that are associated with these disorders. Most previous studies have focused on the pathophysiologic effects of high levels of uric acid (hyperuricemia). More recently, research has also shifted to the impact of hypouricemia, with multiple studies showing the potentially damaging effects that can be caused by abnormally low levels of SUA. Along with these observations, recent inconclusive data from human studies evaluating the treatment of hyperuricemia with xanthine oxidoreductase (XOR) inhibitors have added to the debate about the causal role of UA in human disease processes. SUA, which is largely derived from hepatic degradation of purines, appears to exert both systemic pro-inflammatory effects that contribute to disease and protective antioxidant properties. XOR, which catalyzes the terminal two steps of purine degradation, is the major source of both reactive oxygen species (O2.-, H2O2) and UA. This review will summarize the evidence that both elevated and low SUA may be risk factors for renal, cardiovascular and pulmonary comorbidities. It will also discuss the mechanisms through which modulation of either XOR activity or SUA may contribute to vascular redox hemostasis. We will address future research studies to better account for the differential effects of high versus low SUA in the hope that this will identify new evidence-based approaches for the management of hyperuricemia.

A Novel Cascade Nanoreactor Integrating Two-Dimensional Pd-Ru Nanozyme, Uricase and Red Blood Cell Membrane for Highly Efficient Hyperuricemia Treatment

Nanozyme-based cascade reaction has emerged as an effective strategy for disease treatment because of its high efficiency and low side effects. Herein, a new and highly active two-dimensional Pd-Ru nanozyme is prepared and then integrated with uricase and red blood cell (RBC) membrane to fabricate a tandem nanoreactor, Pd-Ru/Uricase@RBC, for hyperuricemia treatment. The designed Pd-Ru/Uricase@RBC nanoreactor displayed not only good stability against extreme pH, temperature and proteolytic degradation, but also long circulation half-life and excellent safety. The nanoreactor can effectively degrade UA by uricase to allantoin and H₂ O₂ and remove H₂ O₂ by using Pd-Ru nanosheets (NSs) with the catalase (CAT)-like activity. More importantly, the finally produced O₂ from H₂ O₂ decomposition can in turn facilitate the catalytic oxidation of UA, as the degradation of UA is an O₂ consumption process. By integrating the high-efficiency enzymatic activity, long circulation capability, and good biocompatibility, the designed Pd-Ru/Uricase@RBC can effectively and safely treat hyperuricemia without side effects. The study affords a new alternative for the exploration of clinical treatment of hyperuricemia.

A nanostructured microfluidic device for plasmon-assisted electrochemical detection of hydrogen peroxide released from cancer cells

Non-invasive liquid biopsies offer hope for a rapid, risk-free, real-time glimpse into cancer diagnostics. Recently, hydrogen peroxide (H₂O₂) was identified as a cancer biomarker due to its continued release from cancer cells compared to normal cells. The precise monitoring and quantification of H₂O₂ are hindered by its low concentration and the limit of detection (LOD) in traditional sensing methods. Plasmon-assisted electrochemical sensors with their high sensitivity and low LOD make a suitable candidate for effective detection of H₂O₂, yet their electrical properties need to be improved. Here, we propose a new nanostructured microfluidic device for ultrasensitive, quantitative detection of H₂O₂ released from cancer cells in a portable fashion. The fluidic device features a series of self-organized gold nanocavities, enhanced with graphene nanosheets having optoelectrical properties, which facilitate the plasmon-assisted electrochemical detection of H₂O₂ released from human cells. Remarkably, the device can successfully measure the released H₂O₂ from breast cancer (MCF-7) and prostate cancer (PC3) cells in human plasma. Briefly, direct amperometric detection of H₂O₂ under simulated visible light illumination showed a superb LOD of 1 pM in a linear range of 1 pM-10 μM. We thoroughly studied the formation of self-organized plasmonic nanocavities on gold electrodes via surface and photo-electrochemical characterization techniques. In addition, the finite-difference time domain (FDTD) simulation of the electric field demonstrates the intensity of charge distribution at the nanocavity structure edges under visible light illumination. The superb LOD of the proposed electrode combining gold plasmonic nanocavities and graphene sheets paves the way for the development of non-invasive plasmon-assisted electrochemical sensors that can effectively detect low concentrations of H₂O₂ released from cancer cells.

Pharmacologic Management of Gout in Patients with Cardiovascular Disease and Heart Failure

Gout is the most common inflammatory arthritis and is often comorbid with cardiovascular disease (CVD). Hyperuricemia and gout are also independent risk factors for cardiovascular events, worsening heart failure (HF), and death. The recommended treatment modalities for gout have important implications for patients with CVD because of varying degrees of cardiovascular and HF benefit and risk. Therefore, it is critical to both manage hyperuricemia with urate-lowering therapy (ULT) and treat acute gout flares while minimizing the risk of adverse cardiovascular events. In this review, the evidence for the safety of pharmacologic treatment of acute and chronic gout in patients with CVD and/or HF is reviewed. In patients with CVD or HF who present with an acute gout flare, colchicine is considered safe and potentially reduces the risk of myocardial infarction. If patients cannot tolerate colchicine, short durations of low-dose glucocorticoids are efficacious and may be safe. Nonsteroidal anti-inflammatory drugs should be avoided in patients with CVD or HF. The use of canakinumab and anakinra for acute gout flares is limited by the high cost, risk of serious infection, and relatively modest clinical benefit. For long-term ULT, allopurinol, and alternatively probenecid, should be considered first-line treatments in patients with CVD or HF given their safety and potential for reducing cardiovascular outcomes. An increased risk of cardiovascular death and HF hospitalization limit the use of febuxostat and pegloticase as ULT in this population. Ultimately, the selection of agents used for acute gout management and long-term ULT should be individualized according to patient and agent cardiovascular risk factors.

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.