Year in Review: Advances in Research in Gout Pathophysiology in 2024

Abstract

This review provides an overview of the most significant developments in gout pathophysiology research published in 2024. Thirteen studies were selected based on originality, scientific rigor, and potential clinical impact and grouped into four major categories: inflammation and pain mechanisms (LRRC8 anion channels, CXCL5-CXCR2 axis, CD38 and NAD⁺ metabolism, PLK1 and NLRP3 inflammasome localization, and IFN1 suppression), biomarkers and proteomics (scRNA-seq reveals monocyte and T-cell flare signatures, and Olink serum profiling reveals a proinflammatory signature in hyperuricemia and also identifies TNFSF14 as a novel flare biomarker, while a multi-omics integrative study implicates TRIM46 as a key causal gene), gut virome, and novel therapies (vagus nerve stimulation, biomimetic nanosystem, and restoration of Urate Oxidase (Uox) function). The studies selected focused primarily on work on subjects other than on hyperuricemia. The findings collectively expand our understanding of gout’s complex pathophysiology and highlight potential strategies for diagnosis, management, and innovative treatments.

1. Introduction

Gout is a common inflammatory arthritis that results from elevated serum urate levels and the subsequent formation of monosodium urate (MSU) crystals in the joints. Despite the availability of therapies, many patients experience recurrent painful episodes, suggesting that current treatment approaches require improvement. Continuing research is crucial for revealing new disease mechanisms and improving patient outcomes. Rather than following a single overarching narrative, this review is organized into four thematic sections, highlighting insights from 2024 into inflammation and pain mechanisms (LRRC8 anion channels [1], CXCL5-CXCR2 axis [2], CD38 and NAD⁺ metabolism [3], PLK1 and NLRP3 inflammasome localization [4], and IFN1 suppression [5]), biomarkers and proteomics (scRNA-seq reveals monocyte and T-cell flare signatures [6], and Olink serum profiling reveals a proinflammatory signature in hyperuricemia [7] and identifies TNFSF14 as a novel flare biomarker [8], while a multi-omics integrative study implicates TRIM46 as a key causal gene [9]), gut virome [10], and novel therapies (vagus nerve stimulation [11], biomimetic nanosystem [12], and restoration of Uox function [13]). Each section showcases key contributions that reflect the evolving and multifaceted nature of the field.

2. New Insights into Inflammation and Pain Mechanisms

Recent advances have uncovered novel mechanisms driving both inflammation and pain in gout, expanding our understanding of disease pathogenesis and revealing promising therapeutic targets.

2.1. Osmo-Sensitive LRRC8 Anion Channels in Macrophages—Chirayath et al. [1]

A pivotal discovery highlights the role of osmo-sensitive Leucine-Rich Repeat Containing 8 (LRRC8) anion channels in crystal-mediated inflammasome activation in both human and murine macrophages [1]. LRRC8 proteins form volume-regulated anion channels (VRACs) that maintain the cellular ion balance in response to osmotic stress. LRRC8 channels are permeable to a broad range of anions and osmolites, including chloride (Cl⁻), ATP, glutamate, cGAMP, glutathione, and other small anionic molecules. In gout, exposure to MSU crystals triggers LRRC8 channel activation, regulating cell volume changes and ion fluxes essential for NOD-like receptor protein 3 (NLRP3) inflammasome activation and interleukin-1 beta (IL-1β) release. Changes in extracellular osmolarity, such as the reduction caused by MSU or CPP crystals, led to cell swelling and activation of LRRC8 channels, which are permeable to ATP. The released ATP acts autocrinally and paracrinally on macrophage P2Y receptors, primarily P2Y2 and P2Y6, which are key mediators of crystal-induced inflammation. Their activation triggers calcium mobilization via the PLC pathway. The resulting intracellular Ca²⁺ increase, together with coordinated ion efflux (K⁺, Cl⁻), promotes NLRP3 inflammasome activation and IL-1β release. Notably, both genetic silencing and pharmacological inhibition of LRRC8 channels in vitro and in murine models abolished crystal-induced inflammasome activation, significantly reducing joint inflammation and damage. LRRC8 activation also promoted adenosine triphosphate (ATP) release, leading to P2Y receptor activation and intracellular calcium influx—further supporting NLRP3 inflammasome activation and IL-1β maturation. While the association between osmolarity and inflammation has been previously noted [14,15,16], the translational relevance remains underexplored. This study identifies LRRC8 as a critical mediator of osmolarity-driven inflammation in crystal-induced joint disease and positions it as a novel therapeutic target to suppress gout flares [1].

This is not the first instance where ion channels have been associated with gout. Chloride ion (Cl⁻) efflux was recently implicated in NLRP3 inflammasome activation. A decrease in intracellular Cl⁻ concentration promoted the processing and secretion of IL-1β. Hypotonic conditions induce IL-1β release by activating the NLRP3 inflammasome, with regulatory volume decrease (RVD) achieved by reducing intracellular Potassium ion (K⁺) and Cl⁻ concentrations. This process underscores the importance of ion fluxes in inflammasome activation [17].

2.2. CXCL5-CXCR2 in Nociceptive Sensory Neurons Drives Joint Pain in Gout—Yin et al. [2]

In mice, C-X-C motif chemokine 5 (CXCL5), which is released at increased levels by fibroblasts, macrophages, and mast cells after crystal injection, binds to C-X-C motif chemokine receptor 2 (CXCR2) on dorsal root ganglion (DRG) neurons, leading to Transient receptor potential ankyrin 1 (TRPA1) ion-channel activation causing neuronal excitation, increased pain sensitivity, and attracting neutrophils [2]. This chemokine–receptor interaction coordinates with neutrophil recruitment via CXCR2, amplifying both pain and inflammation. Notably, deletion of neuronal CXCR2 in mice dramatically reduced pain sensitivity, swelling, and neutrophil infiltration, suggesting this neuroimmune axis as a novel therapeutic approach. The confirmation of CXCR2 expression in human DRG neurons, together with the observation of elevated serum CXCL5 levels in patients with acute gouty arthritis, supports the translational relevance of the inflammatory mechanisms demonstrated in murine models. CXCL5 was mainly linked to neutrophil recruitment via CXCR2 in immune cells [18].

Importantly, this study also reveals that the increase in neutrophil influx is not driven by a humoral-like spread of CXCL5 from the DRG to the joint, but rather by descending peripheral nerve signals initiated by local CXCL5 within the inflamed joint. Upon CXCR2 activation in nociceptive neurons, signals are relayed to the DRG, where enhanced TRPA1 activity increases neuronal excitability. This results in the local release of neuropeptides at the joint, which act on vascular receptors to promote vasodilation and increased permeability, thereby facilitating neutrophil extravasation. This neurogenic inflammatory loop highlights the coordinated action of neuronal and immune CXCR2 signaling in amplifying joint inflammation.

This paper identifies a novel mechanism in which CXCL5 promotes pain and neuroinflammation in gout by enhancing CXCL5-CXCR2 signaling in DRG neurons [2]. Of note, this work also emphasizes the role of fibroblast-derived chemokines in joint pain. Other inflammatory mediators from macrophages have been described to contribute to gout-associated pain: Interleukin-33 (IL-33) is significantly increased in inflamed joints and promotes pain by enhancing neutrophil-dependent reactive oxygen species (ROS) production and TRPA1 activation through the IL-33 receptor [19]. IL-1β, generated via NLRP3 inflammasome activation, contributes to pain by promoting TRPV1 channel overexpression in sensory neurons [20]. Macrophage transient receptor potential vanilloid 4 (TRPV4) is also involved in gout pain and inflammation [21].

2.3. CD38 and NAD⁺ Metabolism in Gout—Alabarse et al. [3]

The metabolic regulation of inflammation has garnered increasing attention, highlighted by the identification of key metabolic regulators such as CD38. CD38 is a multifunctional ectoenzyme that catalyzes the degradation of nicotinamide adenine dinucleotide (NAD⁺)—a necessary cofactor and key metabolite in pathways involved in cellular energy homeostasis and adaptive responses of cells to bioenergetic stressors including inflammation and aging. In macrophages, CD38 activity directly modulates the intracellular NAD⁺ pool, with downstream effects on transcription, mitochondrial function, and inflammatory signaling [3]. As a central modulator of NAD⁺ metabolism and inflammatory responses in macrophages, CD38 has now been implicated as a critical driver of gouty inflammation.

A recent study identifies CD38 as a central pathogenic link between metabolic dysregulation and MSU-crystal-induced inflammation in gout [3]. In patients with acute gout, plasma NAD⁺ levels are significantly reduced compared with healthy individuals, together with increased CD38 expression in peripheral blood mononuclear cells (PBMCs). In vitro, stimulation of murine bone marrow–derived macrophages (BMDMs) with MSU crystals induced strong upregulation of CD38. This induction was associated with a marked decline in intracellular NAD⁺/NADH levels and enhanced secretion of cytokines such as IL-1β and CXCL1. Inhibition of CD38 with apigenin or 78c, as well as genetic deletion (CD38KO), reversed MSU-induced NAD⁺ depletion and attenuated cytokine release. Consistently, in vivo experiments using the murine subcutaneous air pouch model showed that both CD38KO and apigenin treatment reduced MSU-driven inflammation, evidenced by decreased leukocyte recruitment and cytokine production. Mechanistic analyses revealed that CD38 inhibition suppressed MSU-induced activation of the NLRP3 inflammasome and enhanced the SIRT3–SOD2 pathway, thereby limiting mitochondrial oxidative stress. Moreover, oral supplementation with nicotinamide riboside (NR), a NAD⁺ precursor, elevated plasma NAD⁺ levels and significantly reduced MSU-induced inflammatory responses in vivo. Collectively, these findings underscore the role of CD38 in linking NAD⁺ metabolism to gout-related inflammation, highlighting both CD38 and NAD⁺ metabolic pathways as promising therapeutic targets in gout.

Interestingly, a recent study [22] using enzyme assays and both in vitro and in vivo metabolic analyses demonstrated that soluble urate (sUA) directly inhibits the hydrolase and cyclase activities of CD38 through a reversible, non-competitive mechanism, thereby limiting NAD⁺ degradation. At physiological concentrations, sUA also prevented MSU-crystal-induced peritonitis in mice by targeting CD38. These findings reveal an unexpected physiological role for sUA in regulating NAD⁺ availability through CD38 inhibition, and show that CD38 is the key mediator underlying the opposing effects of sUA and MSU crystals on inflammation and innate immunity in gout

2.4. Polo-like Kinase 1 (PLK1) and Inflammasome Localization—Baldrighi et al. [4]

Polo-like kinase 1 (PLK1), a serine/threonine kinase traditionally associated with mitosis, has now been implicated in regulating inflammasome activation during interphase [4]. This study demonstrates that PLK1 maintains centrosome integrity and modulates microtubule dynamics necessary for proper intracellular positioning of the NLRP3 inflammasome in macrophages. The centrosome, as the main microtubule-organizing center (MTOC), plays a pivotal role in orchestrating the innate immune response by guiding the subcellular localization of the NLRP3 inflammasome to specific regions of the cell that support its activation. PLK1 facilitates this process by promoting the recruitment of γ-tubulin and organizing the pericentriolar matrix, ensuring efficient microtubule nucleation and directional transport. The loss of PLK1 disrupts the localization of the NLRP3 inflammasome to the membrane and cytoskeletal compartments, impairing inflammasome assembly and subsequent IL-1β production. In murine models, pharmacologic inhibition of PLK1 suppressed crystal-induced inflammasome activation and significantly reduced joint inflammation.

In addition to its impact on inflammasome dynamics, PLK1 may also influence mitochondrial homeostasis and ROS production—two upstream signals that modulate NLRP3 inflammasome activation. Some studies suggest that PLK1 inhibition can enhance mitochondrial quality control mechanisms, such as mitophagy, which reduces ROS levels and further dampens inflammasome signaling.

Together, these findings position PLK1 as a multifaceted regulator of gout inflammation, integrating cytoskeletal dynamics, organelle function, and cytokine maturation. Given its druggable kinase domain and established pharmacological inhibitors (developed for cancer therapy), PLK1 represents a promising target for therapeutic intervention in gout and other inflammasome-driven diseases [4].

2.5. Suppressed Type I Interferon Signaling in Gout—Badii et al. [5]

While MSU crystals are known to drive inflammation via NLRP3 inflammasome activation, recent studies have identified a parallel immunomodulatory role for soluble urate. Specifically, elevated urate levels suppress type I interferon (IFN1) signaling, a pathway vital for antiviral defense and immune regulation [5]. In a cohort of 52 gout patients, pre-treatment of peripheral blood mononuclear cells (PBMCs) with soluble urate followed by LPS stimulation led to marked downregulation of IFN1-related genes. Monocytes from these patients also showed reduced Signal transducer and activator of transcription 1 (STAT1) phosphorylation after LPS and MSU crystal stimulation. In vitro stimulation with Toll-like receptor ligands mimicking microbial infection revealed an inverse correlation between serum urate levels and the expression of interferon-stimulated genes and IL-1 receptor antagonist. These results suggest that chronic hyperuricemia suppresses IFN1 responses, potentially contributing to increased susceptibility to infections and the persistence of inflammation. Although previous studies have hinted at links between hyperuricemia and IFN1 pathway modulation, this work provides mechanistic insight and positions IFN1 suppression as a key contributor to gout pathogenesis, offering a novel therapeutic angle beyond inflammasome inhibition.

3. Advances in Gout Biomarkers

Significant progress has been made in identifying biomarkers to improve gout prognosis and disease monitoring, providing new insights into its molecular pathogenesis through cutting-edge omics approaches such as Olink proteomics and single-cell transcriptomics. These technologies have enabled a more detailed understanding of the inflammatory and immune mechanisms driving disease activity and treatment response. While serum urate remains the primary clinical parameter used for diagnosis and therapeutic monitoring, its limitations as a marker of inflammation or flare risk have become increasingly evident. The studies summarized in this section highlight how integrative, multi-layered analyses can reveal novel cellular, protein, and molecular signatures across different clinical states of gout. Key discoveries include the identification of specific immune cell subsets involved in the transition between flare and remission, proinflammatory protein signatures in hyperuricemia even in the absence of clinical symptoms, and the emergence of treatment-responsive proteomic networks during long-term urate-lowering therapy. Biomarkers such as tumor necrosis factor superfamily member 14 (TNFSF14) and fibroblast growth factor 21 (FGF-21) are emerging not only as indicators of disease activity but also as potential therapeutic targets. Together, these findings support the development of more personalized strategies in gout management, grounded in molecular profiling.

3.1. Immune Cell Subtypes as Key Mediators of Gout—Yu et al. [6]

This study aimed to elucidate the immune mechanisms underlying the transition between acute gout flares and remission by applying single-cell RNA sequencing (scRNA-seq) to PBMCs [6]. The primary analysis was conducted on paired PBMCs from three patients with gout collected during both flare and remission phases (total n = 6), and the main results were validated in non-paired independent cohorts. This study complements a prior scRNA-seq study by the same authors that mapped the systemic immune landscape of gout in remission [23]. Its main limitation was the exclusive focus on PBMCs and the absence of neutrophil profiling.

Surprisingly, no significant differences in the overall immune cell composition were found between gout flares and remission. Therefore, the authors proceeded with a more detailed analysis of the major immune cell subtypes to elucidate differences between the flare and remission states. From myeloid cells, the monocytes were the majority, so the analysis revealed that classical (CMs) and intermediate monocytes (IMs), along with circulating dendritic cells, exhibit strong proinflammatory activity during flares, showing enrichment in TNF, IL-1β, and the NLRP3 inflammasome. Gene ontology analysis indicated that upregulated genes in CMs and IMs were primarily associated with TNF and Toll-like receptor (TLR) signaling pathways. These results suggest that circulating CMs and IMs, but not NCMs, are key contributors to systemic inflammation during gout flares, potentially via these innate immune pathways. In addition, non-classical monocytes (NCMs) expressing high levels of HLA-DQA1 were significantly increased during flares. These cells were implicated in antigen processing and presentation and the upregulation of HLA-DQA1 appeared to be linked to damage-associated molecular patterns (DAMPs) rather than urate crystals alone. This finding is supported by evidence of HLA-DQA1 upregulation during the transition from CMs to NCMs and by the activation of major histocompatibility complex class II (MHC-II)–related signaling pathways. The authors propose that the increase in circulating NCMs expressing high levels of HLA-DQA1 may reflect their mobilization from bone marrow or peripheral reservoirs in response to systemic inflammation.

Of note, the same study also showed interesting results regarding T cell dynamics. T regulatory cells (Tregs) were significantly increased during remission and displayed enhanced suppressive capacity in vitro compared to those from the flare phase. Tregs in the remission phase highly expressed cytotoxic T-lymphocyte associated protein 4 (CTLA4) and inducible T-cell costimulator (ICOS), supporting their role in suppressing immune responses through antigen processing and presentation pathways. Moreover, the pathway analysis showed that the flare patient group exhibited enrichment for the interleukin-17 (IL-17) signaling pathway in many T/NK cell subtypes. So, they suggest that the IL-17 signaling pathway within the T and NK subtypes triggers adaptive immune responses in flares. These findings align with other studies highlighting the critical role of T cells in gout. One study showed that perforin (PRF1)—a cytotoxic protein produced by CD8⁺ T and NK cells—limits inflammation in MSU-crystal-induced gout. In a mouse model, perforin deficiency led to increased ankle swelling, greater immune cell infiltration, and prolonged survival of pro-inflammatory M0/M1 macrophages, resulting in excessive TNFα release. In contrast, perforin promoted macrophage apoptosis and helped control TNFα levels [24].

Finally, results from the metabolic analyses suggested that all monocyte subsets showed increased activity in the arachidonic acid (AA) pathway during flares, particularly CMs and IMs, which exhibited high expression of PTGS2 (COX2), which aligns with the use of COX2-selective inhibitors as first-line therapy in acute gout. Liquid chromatography–mass spectrometry (LC-MS) analysis also revealed elevated levels of leukotriene B4 (LTB4) in blood during flares, further supporting the role of AA-derived inflammatory mediators in gout pathogenesis.

3.2. Hyperuricemia Shifts the Serum Proteome Toward a more Proinflammatory Profile—Cabău et al. [7]

A targeted proteomic analysis was performed using the Olink Target 96 Inflammation panel. The study included serum samples from 193 gout patients (65 were in flare and 128 were in the intercritical phase), 154 individuals with asymptomatic hyperuricemia (AH), and 215 normouricemic controls (NU) [7]. The inflammatory proteome of these groups was directly compared, revealing an underlying inflammatory state in asymptomatic hyperuricemia. Several cytokines, chemokines, and growth factors were elevated in this group. Notably, the work identifies fibroblast growth factor 21 (FGF-21) as a potential regulator of inflammation in hyperuricemic gout, supported by in vitro evidence showing that FGF-21 may dampen cytokine production. FGF21 is an endocrine hormone that protects against obesity-related metabolic diseases, nonalcoholic fatty liver disease, and cardiovascular disorders [25], and also plays a role in maintaining skeletal integrity [26,27]. In addition, the findings demonstrate that the inflammatory profile linked to hyperuricemia can be partially reversed by hypouricemic therapy in gout patients, underscoring the therapeutic value of such treatments for reducing both clinical symptoms and systemic inflammation. Together, these results reinforce the proinflammatory role of hyperuricemia even in the absence of clinical gout and open new avenues for exploring pathogenic mechanisms and identifying novel therapeutic targets for gout and its associated cardiometabolic complications.

3.3. Proteome in Gout Flare Inflammation: TNFSF14 as New Biomarker—Stamp et al. [8]

This new longitudinal study complemented the prior cross-sectional study [7]. The GOUTROS prospective cohort provided the first longitudinal plasma profiling of systemic inflammation across the three main clinical phases of gout: flare (T1, n = 71), intercritical period (T2, n = 71), and post-treatment after urate-lowering therapy (T3, n = 36) [8]. The analysis of 92 inflammation-related plasma proteins using Olink proteomics identified 21 novel biomarkers that varied significantly across these stages. Among these, tumor necrosis factor superfamily member 14 (TNFSF14), or LIGHT, emerged as a promising biomarker, showing the highest elevated concentration during acute flares compared to both the intercritical periods and gout controls, with stable low urate levels after therapy [8]. TNFSF14 is known to bind herpesvirus entry mediator (HVEM), a receptor highly expressed on macrophages and T cells, and the TNFSF14-HVEM interaction drives cell activation and proliferation and the increased secretion of pro inflammatory mediators [28]. Alongside TNFSF14, three other inflammatory markers, interleukin-6 (IL-6), colony stimulating factor 1 (CSF-1), and vascular endothelial growth factor A (VEGFA), were validated in an independent cohort, with IL-6 and TNFSF14 showing the largest changes during flares. TNFSF14 was also found to be locally produced in inflamed joints. Its blockade reduced cytokine release, while supplementation enhanced it, confirming its utility as a novel biomarker and therapeutic target in gout. Genetic variation (SNPs) in TNFSF14 was linked to differences in IL1β and IL-6 production by myeloid cells, but not to changes in TNFSF14 protein expression. This study highlights alternative inflammatory pathways that may explain persistent disease despite effective urate-lowering therapy. The authors noted limitations such as the use of a predefined proteomic panel and the potential influence of flare treatment on biomarker levels. Further investigation is needed to clarify the cellular sources of TNFSF14, which is also elevated in the synovial fluid of other inflammatory arthritides like rheumatoid arthritis (RA) and psoriatic arthritis [29].

This inflammatory protein profile is supported by another study that characterized proteomic changes in serum using untargeted mass-spectrometry-based proteomics from two independent cohorts of gout patients (n = 19 and n = 30) before and after 48 weeks of xanthine oxidase inhibitor (XOI) urate-lowering therapy (ULT) [30]. The results revealed that although serum urate achieved normal levels in all patients, the decline in gout flare frequency was associated with significant alterations in both serum and PBMC proteomes, including complement component 5 (C5), IL-1β, IL-6, and interleukin-8 (IL-8/CXCL8). In addition, febuxostat directly attenuated IL-1β-induced inflammatory changes in macrophages. Moreover, sustained ULT was associated with increased serum levels of transforming growth factor beta 1 (TGFB1), a factor that promotes gout flare resolution in experimental models by suppressing macrophage activation by crystals, and reduced insulin-like growth factor I (IGF-I), which interacts with TGFB1. These changes suggest that XOI therapy not only reduces urate levels but also actively modulates inflammatory pathways, potentially promoting resolution (via TGFB1) and altering regulatory networks.

Despite variations in study design, all investigations consistently identified a shared set of inflammatory markers that were upregulated during gout flares, including IL-6, VEGFA, matrix metalloproteinase-1 (MMP-1), C-C motif chemokine ligand 23 (CCL23), hepatocyte growth factor (HGF), C-X-C motif chemokine ligand 1 (CXCL1), CXCL8, and members of the transforming growth factor beta (TGF-β) family. Notably, these studies also demonstrated a significant decline in systemic inflammation during the intercritical period and following ULT, indicating that well-controlled gout—irrespective of treatment status—is associated with a reduced inflammatory burden.

3.4. GWAS and ‘Omics’ Integration in Gout—Yang et al. [9]

An integrative analysis [9] of GWAS data (4607 gout cases; 335,038 controls; data from the Finnish database (https://www.finngen.fi/en, accessed on 26 May 2025)), scRNA-seq from paired PBMCs samples during flare and remission (GSE211783 GEO database, discussed in Section 3.1. [6]), methylation quantitative trait locus (mQTL) data (genetic variant that influences DNA methylation levels) from two European cohorts (the Brisbane Systems Genetics Study (BSGS) [31] (n = 614) and the Lothian Birth Cohorts (LBC) [32] (n = 1366)), and protein (p) QTL data (genetic variant that influences protein abundance) from five proteomic repositories including plasma protein measurements in 35,559 participants was performed in this study [33]. Promising results revealed seventeen association signals at unique genetic loci. Four interrelated genes (tripartite motif containing 46 (TRIM46), thrombospondin 3 (THBS3), metaxin 1 (MTX1), and keratinocyte-associated protein 2 (KRTCAP2)) formed a protein–protein interaction network, while mQTL analysis revealed twenty-two methylation sites associated with gout in genes such as TRIM46, mitogen-activated protein kinase 11 (MAP3K11), KRTCAP2, and transmembrane 7 superfamily member 2 (TM7SF2). Mendelian randomization identified three proteins—Alcohol dehydrogenase 1B (ADH1B), bone morphogenetic protein 1 (BMP1), and histone cluster 1 H3 family member A (HIST1H3A)—as causally linked to gout. Single-cell data showed eight risk alleles predominantly expressed in monocytes/macrophages, plasma cells, mast cells, and myeloid dendritic cells; that MAP3K11, KRTCAP2, and pecanex 3 (PCNX3) could modulate these cells’ functions; and that transmembrane 7 superfamily member 2 (TM7SF2) expression in mast cells correlated with increased gout risk. Finally, Bayesian colocalization analyses were used to evaluate whether gene expression and gout risk share the same causal genetic variant within a given locus. This method estimates the probability that gene expression and disease risk are influenced by the same single nucleotide polymorphism (SNP), rather than by independent but nearby variants.

Using this approach, the study identified TRIM46 as a key causal gene and found strong evidence of shared variant associations for THBS3, glucosidase beta acid pseudogene 1 (GBAP1), MTX1, thrombospondin 3 antisense RNA 1 (THBS3-AS1), fucosyltransferase 8 (FUT8), Unc-13 homolog D (UNC13D), Ly6/PLAUR domain containing 2 (LYPD2), and guanine nucleotide-binding protein gamma-T2 subunit (GNGT2). These findings indicate that variation in these loci is likely to contribute to both gene expression and gout susceptibility through a common genetic mechanism.

Authors suggest that genetic variants in TRIM46 may contribute to gout susceptibility by affecting both urate metabolism and inflammatory responses. TRIM46 encodes a protein involved in microtubule organization and neuronal polarity, and its altered expression or function could impair urate excretion by the kidney or intestine, leading to elevated serum urate levels. In addition, TRIM46 may modulate the inflammatory response in gout through its role in microtubule dynamics in macrophages. By influencing phagocytosis and signaling pathways such as JNK, TRIM46 could affect the production of proinflammatory cytokines in response to monosodium urate crystals, thereby linking cellular polarization, urate handling, and inflammation in the pathogenesis of gout.

4. Emerging Roles of Gut Microbiota and Metabolomics in Gout

Growing recognition of the complex interplay between host metabolism, immune responses, and the gut ecosystem has shifted attention toward the microbiome and metabolome as key contributors to gout pathogenesis. Beyond traditional views centered on hyperuricemia, recent studies underscore the relevance of gut microbial and metabolic signatures in urate homeostasis, inflammation, and disease onset. A fascinating paper published in 2023 identified a widely distributed bacterial gene cluster that encodes a pathway for urate degradation. This pathway metabolizes urate to xanthine or short-chain fatty acids and was shown to cause severe hyperuricemia following microbiota ablation in uricase-deficient mice [34]. Among other gut bacterial taxa, Collinsella was suggested to have a putative causal role in modulating serum urate levels—a potentially modifiable factor in uric acid metabolism—an observation also supported by another manuscript published in 2024 [35]. This section explores a distinct yet complementary facet of this emerging field: alterations in the gut virome as potential contributors to joint inflammation and gout.

Distinct Gut Virome Profiles in Gout—Chen et al. [10]

The human virome—the collection of viruses inhabiting the body—is an emerging area of microbiome research. While bacterial diversity in healthy individuals is well known, the complexity of the viral community has only recently gained attention. Viruses, particularly bacteriophages, significantly influence bacterial diversity and horizontal gene transfer within the gut microbiota, indirectly affecting essential functions such as nutrient metabolism (including urate metabolism), immune responses, pathogen defense, and intestinal immunity and epithelial barrier integrity [10]. Although viral metagenomics was first applied in 2002 [36], meaningful links between the virome and disease have only recently emerged. Studies now suggest that virome composition is shaped by factors like age, diet, geography, and disease, with alterations associated with conditions such as RA, systemic lupus erythematosus, ankylosing spondylitis, inflammatory bowel disease (IBD), metabolic syndrome, and osteoarthritis (OA) [37,38,39,40,41,42].

The primary aim of this study was to characterize the intestinal virome in 20 patients with OA, 26 patients with gouty arthritis (GA), and 31 healthy controls [10]. Researchers employed virus-like particle (VLP)-based metagenomic sequencing. Significant differences were identified in the intestinal virome composition between GA patients and healthy controls. GA-associated viruses were linked to Bacteroidaceae or Lachnospiraceae phages. This finding suggests a specific viral dysbiosis in GA, potentially linked to critical alterations in the bacterial community, although the exact roles of these viruses remain to be elucidated. Additionally, the study identified 94 viral operational taxonomic units (vOTUs) significantly associated with GA, with 51 vOTUs enriched in GA patients. Notably, one Quimbyviridae vOTU harbored a gene encoding a hemolysin-related protein, which may cause chondrocyte cell death and could contribute mechanistically to gout pathogenesis. Furthermore, a classification model based on these viral signatures demonstrated high diagnostic accuracy, achieving an area under the curve (AUC) greater than 0.97, highlighting the potential of intestinal virome profiling as a complementary diagnostic tool.

5. Innovative Therapeutic Approaches in Gout

The limitations of current gout treatments have driven the search for alternative therapeutic strategies. Recent preclinical studies have explored novel avenues ranging from neuromodulation to nanotechnology and gene-based therapies, reflecting an exciting shift in the therapeutic landscape of gout. These experimental approaches include transcutaneous vagus nerve stimulation (VNS) to modulate inflammation, multifunctional nanosystems that simultaneously reduce urate levels and reprogram immune cells, and atavistic mRNA therapies designed to restore lost enzymatic functions. While the results are promising and mark a substantial step forward in innovation, it is important to note that all the findings in these studies are from animal models. Continued research and translational efforts will be essential to determine whether these strategies can be safely and effectively applied in humans and, ultimately, improve the quality of life for patients living with gout.

5.1. Vagus Nerve Stimulation as an Anti-Inflammatory Therapeutic Strategy in Gout—Shin et al. [11]

Recent research into non-pharmacological strategies for gout has spotlighted neuroimmune modulation, particularly via vagus nerve stimulation (VNS), as a promising alternative. Traditional treatments like NSAIDs, colchicine, and corticosteroids, while effective, often carry significant side effects, especially with long-term use. This has driven interest in targeting inflammatory pathways through neuromodulatory approaches. A recent experimental study explored the anti-inflammatory potential of transcutaneous auricular VNS (taVNS) in a mouse model of acute gout [11]. Gout-like inflammation was induced by injecting MSU crystals into the ankle joints of BALB/c mice, mimicking human gout flares. taVNS was applied at varying frequencies, and its effects on joint inflammation were evaluated using PCR, Western blotting, histology, and immunohistochemistry, with a focus on cytokine expression, neutrophil infiltration, and α7 nicotinic acetylcholine receptor (α7nAChR) involvement, key mediators of the cholinergic anti-inflammatory pathway. The study found that taVNS at 25 Hz significantly reduced neutrophil infiltration and proinflammatory cytokine expression. Blocking α7nAChRs reversed these effects, confirming the receptor’s role in mediating the anti-inflammatory response. Notably, 25 Hz stimulation was more effective than 15 Hz, highlighting a frequency-dependent mechanism. Histological and molecular data supported a reduction in neutrophil activation and chemoattraction, underscoring taVNS’s ability to modulate innate immune responses. Further clinical research is needed to evaluate its safety, efficacy, and optimal stimulation parameters in humans. Of interest, an open-label clinical trial investigated the safety and efficacy of non-invasive stimulation of the auricular branch of the vagus nerve for the treatment of patients with moderately to severely active RA with clinically meaningful reductions in arthritis scores [43], although meaningful improvements in disease activity were not reached in a recent randomized and double-blind clinical trial [44]. Pilot studies in IBD [45,46] also support the potential of VNS as a therapeutic strategy in inflammatory conditions.

5.2. A Novel Biomimetic Nanosystem for Simultaneous Urate Reduction and Inflammation Resolution—Xu et al. [12]

A recent preclinical study introduced a novel biomimetic nanosystem, D-N [EM2], as a potential therapy for gouty arthritis (GA), aiming to simultaneously reprogram inflammatory macrophages, reduce urate levels, and promote tissue repair—overcoming the limitations of current treatments that often act in isolation and may cause side effects. The system consists of a liposome-based platform encapsulating uricase (URI), platinum nanozymes (PtHD), and resveratrol, all enclosed within a hybrid membrane derived from M2 macrophages and exosomes (EM2). This design enables selective targeting of inflamed joints, immune evasion, and macrophage repolarization toward an anti-inflammatory phenotype. Uricase (URI) is incorporated for its direct enzymatic role in degrading urate into allantoin, a more soluble and easily excreted compound, thereby reducing uric acid levels. PtHD enables photothermal-induced tissue repair when activated by near-infrared light, while reveratrol helps reduce immunogenic responses. In vitro, D-N [EM2] demonstrated superior enzymatic stability, ROS scavenging, and macrophage modulation. In vivo, it significantly reduced urate levels, inflammation, and joint damage in GA rat models compared to free URI, and improved pain and mobility outcomes. Histological analysis showed lowered pro-inflammatory cytokines and enhanced IL-10 expression. Importantly, the nanosystem showed low immunogenicity and good joint retention. These findings support D-N [EM2] as a promising multifunctional nanotherapeutic platform for GA, offering a synergistic approach that integrates urate degradation, immune modulation, and tissue repair [12].

5.3. Restoration of Urate Oxidase Activity to Target Hyperuricemia—Zhang et al. [13]

Hyperuricemia, a key risk factor for gout, results from the loss of urate oxidase (Uox) activity in humans, an enzyme that converts poorly soluble urate into soluble allantoin. A recent study proposed restoring Uox function using mRNA-based therapy delivered via ionizable lipid nanoparticles (iLAND). This approach aims to overcome the limitations of current treatments like allopurinol, which can have adverse effects. In vitro and in vivo experiments showed that mUox@iLAND effectively expressed Uox in hepatocytes, reduced serum urate levels, and reversed metabolic disturbances in mouse models of hyperuricemia, with good safety and liver targeting. A single dose of mUox@iLAND provided sustained serum urate lowering, prevented renal damage, and avoided the side effects seen with traditional drugs. These findings support mUox@iLAND as a promising, safer therapeutic strategy for long-term management and prevention of gout [13].

6. Conclusions

Research conducted in 2024 advanced the understanding of gout by uncovering new inflammatory pathways, identifying novel biomarkers, elucidating the critical roles of gut microbiota and metabolites, and exploring innovative therapies. These breakthroughs promise meaningful improvements in gout diagnosis, disease monitoring, prevention, and treatment, ultimately enhancing patient care and definitively defining new directions for future research.