Where Epigenetics Meets Food Intake: Their Interaction in the Development/Severity of Gout and Therapeutic Perspectives

The changing burden of gout in adults aged 70 and above based on the global burden of disease 2019

Introduction

Gout is a significant global health issue, particularly among adults aged 70 and above. Understanding its epidemiological evolution and associated factors is crucial for guiding interventions and improving management.

Methods

This study analyzed data from the Global Burden of Disease study to assess the prevalence and trends of gout among adults aged 70 and above from 1990 to 2019. We evaluated temporal trends and regional disparities by calculating the estimated annual percentage change (EAPCs).

Results

Globally, the number of older adults individuals affected by gout increased from 5,316,210 cases in 1990 to 15,666,063 cases in 2019. It is noteworthy that the global burden of gout among the older adults continued to rise from 1990 to 2019, with an EAPC of 1.17 (95% CI: 1.02 to 1.32). In 2019, the prevalence rates among individuals aged 70-74, 75-79, 80-84, and 85 and above were 3,121.31 per 100,000, 3,437.17 per 100,000, 3,592.38 per 100,000, and 3,726.91 per 100,000, respectively. The regions with the highest prevalence rates of gout in 2019 were Australasia, High-income North America, and Southern Latin America, with rates of 8,500.73, 8,351.33, and 4,666.87 per 100,000, respectively. At the national level, some developed countries such as New Zealand, the United States of America, and Australia had the highest prevalence rates, reaching 8,893.74, 8,508.06, and 8,427.94 per 100,000, respectively. It is noteworthy that regions with higher levels of Socio-Demographic Index tended to have relatively higher burden of gout among the older adults, and the prevalence rates varied across different regions and age groups.

Conclusion

The study underscores the persistent burden of gout among the older adults, emphasizing the need for targeted interventions to address this issue and improve public health outcomes in this demographic.

Chemical Characterization of Alphitonia neocaledonica (Schltr.) Guillaumin Bark Extract and Its Anti-Inflammatory Activities

Alphitonia neocaledonica (Schltr.) Guillaumin is a small forest tree endemic of New Caledonia traditionally used to treat rheumatic pain and dermatoses. Very few studies described biological activities and phytochemical composition of this plant. This study aims to investigate the anti-inflammatory and anti-gout activities of A. neocaledonica bark extract (ANBE) and its chemical composition. Lipopolysaccharide (LPS)-induced phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 macrophages and LPS/monosodium urate (MSU)-treated THP-1 model reproducing gout in vitro were used. Chemical analyses were undertaken using liquid chromatography-high resolution mass spectrometry (LC-HRMS) approaches. Dose-dependent inhibitory effects of ANBE on inflammatory cytokines interleukin-(IL-)1β, IL-6, and tumor necrosis factor-α (TNF-α) were observed. Inhibition of LPS/MSU-dependent IL-1β at 1 and 10 µg/mL was also reported. Chemical analyses by LC-HRMS allowed us to putatively identify some features such as epigallocatechin, iridoid- and flavonoid-glycosides, oligopeptides, and triterpenoids in ANBE. These results provide some cues in favor of traditional uses of ANBE and support the need of further bioactivities and chemical investigations.

Epigenetics-targeted drugs: current paradigms and future challenges

Epigenetics governs a chromatin state regulatory system through five key mechanisms: DNA modification, histone modification, RNA modification, chromatin remodeling, and non-coding RNA regulation. These mechanisms and their associated enzymes convey genetic information independently of DNA base sequences, playing essential roles in organismal development and homeostasis. Conversely, disruptions in epigenetic landscapes critically influence the pathogenesis of various human diseases. This understanding has laid a robust theoretical groundwork for developing drugs that target epigenetics-modifying enzymes in pathological conditions. Over the past two decades, a growing array of small molecule drugs targeting epigenetic enzymes such as DNA methyltransferase, histone deacetylase, isocitrate dehydrogenase, and enhancer of zeste homolog 2, have been thoroughly investigated and implemented as therapeutic options, particularly in oncology. Additionally, numerous epigenetics-targeted drugs are undergoing clinical trials, offering promising prospects for clinical benefits. This review delineates the roles of epigenetics in physiological and pathological contexts and underscores pioneering studies on the discovery and clinical implementation of epigenetics-targeted drugs. These include inhibitors, agonists, degraders, and multitarget agents, aiming to identify practical challenges and promising avenues for future research. Ultimately, this review aims to deepen the understanding of epigenetics-oriented therapeutic strategies and their further application in clinical settings.

Mechanism of macrophages in gout: Recent progress and perspective

Gout represents an autoinflammatory disorder instigated by monosodium urate crystals. Its primary manifestation involves the recruitment of diverse immune cell populations, including neutrophils and macrophages. Macrophages assume a pivotal role in the initiation of acute gouty inflammation and subsequent inflammatory cascades. However, recent investigations have revealed that the impact of macrophages on gout is nuanced, extending beyond a solely detrimental influence. Macrophages, characterized by different subtypes, exhibit distinct functionalities that either contribute to the progression or regression of gout. A strategy aimed at modulating macrophage polarization, rather than merely inhibiting inflammation, holds promise for enhancing the efficacy of acute gout treatment. This review centres on elucidating potential mechanisms underlying macrophage polarization in the onset and resolution of gouty inflammation, offering novel insights into the immune equilibrium of macrophages in the context of gout.

Effect of low-purine diet on the serum uric acid of gout patients in different clinical subtypes: a prospective cohort study

BACKGROUND

The pathogenic causes of primary gout include urate overproduction and/or renal or extra-renal urate underexcretion. The aim of this study was to evaluate the association of gout subtypes with the response to low-purine diet (LPD).

METHODS

This is a single-center prospective clinical study. Gout patients visiting from 2019 to 2022, from Shandong Gout Clinic Center at the Affiliated Hospital of Qingdao University, China, assigned to three groups according to clinical subtypes, were enrolled and all treated with 2-week low-purine diet. General characteristics, serum uric acid (sUA) and other clinical biochemical variables before and after the diet were evaluated.

RESULTS

A total of 626 gout patients (age 41.20 ± 13.41 years, male 98.0%) were included. Of these, 69 (11.0%) were overproduction type, 428 (68.37%) were underexcretion type, and 129 (20.61%) were combined type. Overall, there was a substantial decrease in sUA after a 2-week LPD (p < 0.001). In addition, systolic blood pressure (SBP), diastolic blood pressure (DBP), body mass index (BMI), serum alanine aminotransferase (ALT), serum aspartate aminotransferase (AST), serum triglycerides (TG), serum total cholesterol (TC), blood urea nitrogen (BUN) and serum creatinine (Scr) levels were lower than those at baseline (p < 0.05). On the other hand, there were significant differences in the reduction of sUA among different types, the rank order being overproduction type (- 88.81 ± 63.01 μmol/L) > combined type (- 65.22 ± 44.13 μmol/L) > underexcretion type (- 57.32 ± 61.19 μmol/L). After adjusting for age, BMI and baseline sUA and eGFR, there were still significant differences in the decline of serum uric acid among different types. Higher baseline sUA (95%CI - 0.285, - 0.191; p < 0.001) and BUN (95%CI - 6.751, - 0.602; p < 0.001) were correlated with greater decrease of sUA.

CONCLUSIONS

Our findings support the protective role of low-purine diet on sUA levels in gout patients, especially overproduction type. Furthermore, LPD could exert a beneficial effect on gout patients' blood pressure, BMI, blood lipid, BUN and Scr levels. Trial registration Registered with ChiCTR, No. ChiCTR1900022981 at 06/05/2019.

Revisiting the Immunometabolic Basis for the Metabolic Syndrome from an Immunonutritional View

Metabolic syndrome (MetS) implies different conditions where insulin resistance constitutes a major hallmark of the disease. The disease incurs a high risk for the development of cardiovascular complications, and takes its toll in regard to the gut-liver axis (pancreas, primary liver and colorectal)-associated immunity. The modulation of immunometabolic responses by immunonutritional factors (IFs) has emerged as a key determinant of the gut-liver axis' metabolic and immune health. IFs from plant seeds have shown in vitro and pre-clinical effectiveness primarily in dealing with various immunometabolic and inflammatory diseases. Only recently have immunonutritional studies established the engagement of innate intestinal immunity to effectively control immune alterations in inflamed livers preceding the major features of the MetS. However, integrative analyses and the demonstration of causality between IFs and specific gut-liver axis-associated immunometabolic imbalances for the MetS remain ill-defined in the field. Herein, a better understanding of the IFs with a significant role in the MetS, as well as within the dynamic interplay in the functional differentiation of innate immune key effectors (i.e., monocytes/macrophages), worsening or improving the disease, could be of crucial relevance. The development of an adequate intermediary phenotype of these cells can significantly contribute to maintaining the function of Tregs and innate lymphoid cells for the prevention and treatment of MetS and associated comorbidities.

Fish Oil Supplementation Mitigates High-Fat Diet-Induced Obesity: Exploring Epigenetic Modulation and Genes Associated with Adipose Tissue Dysfunction in Mice

This study investigated the effects of fish oil (FO) treatment, particularly enriched with eicosapentaenoic acid (EPA), on obesity induced by a high-fat diet (HFD) in mice. The investigation focused on elucidating the impact of FO on epigenetic modifications in white adipose tissue (WAT) and the involvement of adipose-derived stem cells (ASCs). C57BL/6j mice were divided into two groups: control diet and HFD for 16 weeks. In the last 8 weeks, the HFD group was subdivided into HFD and HFD + FO (treated with FO). WAT was removed for RNA and protein extraction, while ASCs were isolated, cultured, and treated with leptin. All samples were analyzed using functional genomics tools, including PCR-array, RT-PCR, and Western Blot assays. Mice receiving an HFD displayed increased body mass, fat accumulation, and altered gene expression associated with WAT inflammation and dysfunction. FO supplementation attenuated these effects, a potential protective role against HFD-induced obesity. Analysis of H3K27 revealed HFD-induced changes in histone, which were partially reversed by FO treatment. This study further explored leptin signaling in ASCs, suggesting a potential mechanism for ASC dysfunction in the obesity-rich leptin environment of WAT. Overall, FO supplementation demonstrated efficacy in mitigating HFD-induced obesity, influencing epigenetic and molecular pathways, and shedding light on the role of ASCs and leptin signaling in WAT dysfunction associated with obesity.

Dihydroartemisinin is an inhibitor of trained immunity through Akt/mTOR/HIF1α signaling pathway

Trained immunity is mechanistically defined as the metabolically and epigenetically mediated long-term functional adaptation of the innate immune system, characterized by a heightened response to a secondary stimulation. Given appropriate activation, trained immunity represents an attractive anti-infective therapeutic target. Nevertheless, excessive immune response and subsequent inflammatory cascades may contribute to pathological tissue damage, indicating that the negative impacts of trained immunity appear to be significant. In this study, we show that innate immune responses such as the production of extracellular traps, pro-inflammatory cytokines, and autophagy-related proteins were markedly augmented in trained BMDMs. Furthermore, heat-killed C. albicans priming promotes the activation of the AIM2 inflammasome, and AIM2-/- mice exhibit impaired memory response induced by heat-killed C. albicans. Therefore, we establish that the AIM2 inflammasome is involved in trained immunity and emerges as a promising therapeutic target for potentially deleterious effects. Dihydroartemisinin can inhibit the memory response induced by heat-killed C. albicans through modulation of mTOR signaling and the AIM2 inflammasome. The findings suggest that dihydroartemisinin can reduce the induction of trained immunity by heat-killed C. albicans in C57BL/6 mice. Dihydroartemisinin is one such therapeutic intervention that has the potential to treat of diseases characterized by excessive trained immunity.

Lipidomics Analysis Deepen Understanding the Molecular Mechanisms in a Gouty Model Induced by Combination of MSU Crystals Injection and High-Fat Diet Feeding and the Intervention Mechanisms of Allopurinol

Background

Gouty arthritis (GA) is a common inflammatory disease caused by deposition of monosodium urate (MSU) crystals in diarthrodial joints. GA attacks commonly involved in joint with red, swollen, heat and pain, and often happened in unilateral foot-first metatarsophalangeal. Accumulated studies have proved that lipids play critical roles in biological processes and lipids biomarkers can substitute for the diagnosis of various diseases.

Methods

Herein, shotgun lipidomics was used to quantitatively analyze serum lipidomes of a gouty model which was induced by injecting MSU crystals and feeding high-fat diet with/without treatment with allopurinol. Meanwhile, ELISA kit was used to detect mouse serum levels of inflammatory cytokines (eg, tumor necrosis factor-α, interleukin 1 beta) and HE staining was used to observe the infiltration of inflammatory cells in the foot pad.

Results

A total of 9 types of serum lipids were detected in lipidomics by shotguns, and the result of NMDS' analysis demonstrated significant differences in lipids profiles between the control and model group. It is worth noting that lipid abnormality in GA (such as Ceramide (Cer), sphingomyelin (SM), 4-hydroxyalkenals (HNE), phosphatidylinositol (PI), ethanolamine glycerophospholipid (PE), etc.) is related with phospholipid and energy metabolism, and allopurinol treatment could correct the aberrant metabolism of lipid to some extent.

Conclusion

Our results indicated that various aberrant lipid metabolisms were present in the established gouty model, and allopurinol treatment could relief this aberrant metabolism of lipids to some degree.

Genetic and Epigenetic Regulation of the Innate Immune Response to Gout

Gout is a disease caused by uric acid (UA) accumulation in the joints, causing inflammation. Two UA forms - monosodium urate (MSU) and soluble uric acid (sUA) have been shown to interact physically with inflammasomes, especially with the nod-like receptor (NLR) family pyrin domain containing 3 (NLRP3), albeit the role of the immune response to UA is poorly understood, given that asymptomatic hyperuricemia does also exist. Macrophage phagocytosis of UA activate NLRP3, lead to cytokines release, and ultimately, lead to chemoattract neutrophils and lymphocytes to the gout flare joint spot. Genetic variants of inflammasome genes and of genes encoding their molecular partners may influence hyperuricemia and gout susceptibility, while also influencing other comorbidities such as metabolic syndrome and cardiovascular diseases. In this review, we summarize the inflammatory responses in acute and chronic gout, specifically focusing on innate immune cell mechanisms and genetic and epigenetic characteristics of participating molecules. Unprecedently, a novel UA binding protein - the neuronal apoptosis inhibitor protein (NAIP) - is suggested as responsible for the asymptomatic hyperuricemia paradox.Abbreviation: β2-integrins: leukocyte-specific adhesion molecules; ABCG2: ATP-binding cassete family/breast cancer-resistant protein; ACR: American college of rheumatology; AIM2: absent in melanoma 2, type of pattern recognition receptor; ALPK1: alpha-protein kinase 1; ANGPTL2: angiopoietin-like protein 2; ASC: apoptosis-associated speck-like protein; BIR: baculovirus inhibitor of apoptosis protein repeat; BIRC1: baculovirus IAP repeat-containing protein 1; BIRC2: baculoviral IAP repeat-containing protein 2; C5a: complement anaphylatoxin; cAMP: cyclic adenosine monophosphate; CARD: caspase activation and recruitment domains; CARD8: caspase recruitment domain-containing protein 8; CASP1: caspase 1; CCL3: chemokine (C-C motif) ligand 3; CD14: cluster of differentiation 14; CD44: cluster of differentiation 44; Cg05102552: DNA-methylation site, usually cytosine followed by guanine nucleotides; contains arbitrary identification code; CIDEC: cell death-inducing DNA fragmentation factor-like effector family; CKD: chronic kidney disease; CNV: copy number variation; CPT1A: carnitine palmitoyl transferase - type 1a; CXCL1: chemokine (CXC motif) ligand 1; DAMPs: damage associated molecular patterns; DC: dendritic cells; DNMT(1): maintenance DNA methyltransferase; eQTL: expression quantitative trait loci; ERK1: extracellular signal-regulated kinase 1; ERK2: extracellular signal-regulated kinase 2; EULAR: European league against rheumatism; GMCSF: granulocyte-macrophage colony-stimulating factor; GWAS: global wide association studies; H3K27me3: tri-methylation at the 27th lysine residue of the histone h3 protein; H3K4me1: mono-methylation at the 4th lysine residue of the histone h3 protein; H3K4me3: tri-methylation at the 4th lysine residue of the histone h3 protein; HOTAIR: human gene located between hoxc11 and hoxc12 on chromosome 12; IκBα: cytoplasmatic protein/Nf-κb transcription inhibitor; IAP: inhibitory apoptosis protein; IFNγ: interferon gamma; IL-1β: interleukin 1 beta; IL-12: interleukin 12; IL-17: interleukin 17; IL18: interleukin 18; IL1R1: interleukin-1 receptor; IL-1Ra: interleukin-1 receptor antagonist; IL-22: interleukin 22; IL-23: interleukin 23; IL23R: interleukin 23 receptor; IL-33: interleukin 33; IL-6: interleukin 6; IMP: inosine monophosphate; INSIG1: insulin-induced gene 1; JNK1: c-jun n-terminal kinase 1; lncRNA: long non-coding ribonucleic acid; LRR: leucine-rich repeats; miR: mature non-coding microRNAs measuring from 20 to 24 nucleotides, animal origin; miR-1: miR followed by arbitrary identification code; miR-145: miR followed by arbitrary identification code; miR-146a: miR followed by arbitrary identification code, "a" stands for mir family; "a" family presents similar mir sequence to "b" family, but different precursors; miR-20b: miR followed by arbitrary identification code; "b" stands for mir family; "b" family presents similar mir sequence to "a" family, but different precursors; miR-221: miR - followed by arbitrary identification code; miR-221-5p: miR followed by arbitrary identification code; "5p" indicates different mature miRNAs generated from the 5' arm of the pre-miRNA hairpin; miR-223: miR followed by arbitrary identification code; miR-223-3p: mir followed by arbitrary identification code; "3p" indicates different mature miRNAs generated from the 3' arm of the pre-miRNA hairpin; miR-22-3p: miR followed by arbitrary identification code, "3p" indicates different mature miRNAs generated from the 3' arm of the pre-miRNA hairpin; MLKL: mixed lineage kinase domain-like pseudo kinase; MM2P: inductor of m2-macrophage polarization; MSU: monosodium urate; mTOR: mammalian target of rapamycin; MyD88: myeloid differentiation primary response 88; n-3-PUFAs: n-3-polyunsaturated fatty-acids; NACHT: acronym for NAIP (neuronal apoptosis inhibitor protein), C2TA (MHC class 2 transcription activator), HET-E (incompatibility locus protein from podospora anserina) and TP1 (telomerase-associated protein); NAIP: neuronal apoptosis inhibitory protein (human); Naip1: neuronal apoptosis inhibitory protein type 1 (murine); Naip5: neuronal apoptosis inhibitory protein type 5 (murine); Naip6: neuronal apoptosis inhibitory protein type 6 (murine); NBD: nucleotide-binding domain; Nek7: smallest NIMA-related kinase; NET: neutrophil extracellular traps; Nf-κB: nuclear factor kappa-light-chain-enhancer of activated b cells; NFIL3: nuclear-factor, interleukin 3 regulated protein; NIIMA: network of immunity in infection, malignancy, and autoimmunity; NLR: nod-like receptor; NLRA: nod-like receptor NLRA containing acidic domain; NLRB: nod-like receptor NLRA containing BIR domain; NLRC: nod-like receptor NLRA containing CARD domain; NLRC4: nod-like receptor family CARD domain containing 4; NLRP: nod-like receptor NLRA containing PYD domain; NLRP1: nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 1; NLRP12: nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 12; NLRP3: nod-like receptor family pyrin domain containing 3; NOD2: nucleotide-binding oligomerization domain; NRBP1: nuclear receptor-binding protein; Nrf2: nuclear factor erythroid 2-related factor 2; OR: odds ratio; P2X: group of membrane ion channels activated by the binding of extracellular; P2X7: p2x purinoceptor 7 gene; p38: member of the mitogen-activated protein kinase family; PAMPs: pathogen associated molecular patters; PBMC: peripheral blood mononuclear cells; PGGT1B: geranylgeranyl transferase type-1 subunit beta; PHGDH: phosphoglycerate dehydrogenase; PI3-K: phospho-inositol; PPARγ: peroxisome proliferator-activated receptor gamma; PPARGC1B: peroxisome proliferative activated receptor, gamma, coactivator 1 beta; PR3: proteinase 3 antigen; Pro-CASP1: inactive precursor of caspase 1; Pro-IL1β: inactive precursor of interleukin 1 beta; PRR: pattern recognition receptors; PYD: pyrin domain; RAPTOR: regulatory associated protein of mTOR complex 1; RAS: renin-angiotensin system; REDD1: regulated in DNA damage and development 1; ROS: reactive oxygen species; rs000*G: single nuclear polymorphism, "*G" is related to snp where replaced nucleotide is guanine, usually preceded by an id number; SLC2A9: solute carrier family 2, member 9; SLC7A11: solute carrier family 7, member 11; SMA: smooth muscular atrophy; Smac: second mitochondrial-derived activator of caspases; SNP: single nuclear polymorphism; Sp3: specificity protein 3; ST2: serum stimulation-2; STK11: serine/threonine kinase 11; sUA: soluble uric acid; Syk: spleen tyrosine kinase; TAK1: transforming growth factor beta activated kinase; Th1: type 1 helper T cells; Th17: type 17 helper T cells; Th2: type 2 helper T cells; Th22: type 22 helper T cells; TLR: tool-like receptor; TLR2: toll-like receptor 2; TLR4: toll-like receptor 4; TNFα: tumor necrosis factor alpha; TNFR1: tumor necrosis factor receptor 1; TNFR2: tumor necrosis factor receptor 2; UA: uric acid; UBAP1: ubiquitin associated protein; ULT: urate-lowering therapy; URAT1: urate transporter 1; VDAC1: voltage-dependent anion-selective channel 1.

Epigenetic regulation in metabolic diseases: mechanisms and advances in clinical study

Epigenetics regulates gene expression and has been confirmed to play a critical role in a variety of metabolic diseases, such as diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), osteoporosis, gout, hyperthyroidism, hypothyroidism and others. The term 'epigenetics' was firstly proposed in 1942 and with the development of technologies, the exploration of epigenetics has made great progresses. There are four main epigenetic mechanisms, including DNA methylation, histone modification, chromatin remodelling, and noncoding RNA (ncRNA), which exert different effects on metabolic diseases. Genetic and non-genetic factors, including ageing, diet, and exercise, interact with epigenetics and jointly affect the formation of a phenotype. Understanding epigenetics could be applied to diagnosing and treating metabolic diseases in the clinic, including epigenetic biomarkers, epigenetic drugs, and epigenetic editing. In this review, we introduce the brief history of epigenetics as well as the milestone events since the proposal of the term 'epigenetics'. Moreover, we summarise the research methods of epigenetics and introduce four main general mechanisms of epigenetic modulation. Furthermore, we summarise epigenetic mechanisms in metabolic diseases and introduce the interaction between epigenetics and genetic or non-genetic factors. Finally, we introduce the clinical trials and applications of epigenetics in metabolic diseases.

Restoring Epigenetic Reprogramming with Diet and Exercise to Improve Health-Related Metabolic Diseases

Epigenetic reprogramming predicts the long-term functional health effects of health-related metabolic disease. This epigenetic reprogramming is activated by exogenous or endogenous insults, leading to altered healthy and different disease states. The epigenetic and environmental changes involve a roadmap of epigenetic networking, such as dietary components and exercise on epigenetic imprinting and restoring epigenome patterns laid down during embryonic development, which are paramount to establishing youthful cell type and health. Nutrition and exercise are among the most well-known environmental epigenetic factors influencing the proper developmental and functional lifestyle, with potential beneficial or detrimental effects on health status. The diet and exercise strategies applied from conception could represent an innovative epigenetic target for preventing and treating human diseases. Here, we describe the potential role of diet and exercise as therapeutic epigenetic strategies for health and diseases, highlighting putative future perspectives in this field.

Potential Biological Markers and Treatment Implications for Binge Eating Disorder and Behavioral Addictions

The reward system is highly relevant to behavioral addictions such as gambling disorder (GD), internet gaming disorder (IGD), and food addiction/binge eating disorder (FA/BED). Among other brain regions, the ventral striatum (VS) has been implicated in reward processing. The main objective of the present state-of-the-art review was to explore in depth the specific role of the VS in GD, IGD and FA/BED, understanding it as a possible biomarker of these conditions. Studies analyzing brain changes following interventions for these disorders, and especially those that had explored possible treatment-related changes in VS, are discussed. More evidence is needed on how existing treatments (both pharmacological and psychobehavioral) for behavioral addictions affect the activation of the VS and related circuitry.

Mediation by DNA methylation on the association of BMI and serum uric acid in Chinese monozygotic twins

Obesity is an established risk factor for hyperuricemia, but the mechanisms are only partially understood. We examined whether BMI-related DNA methylation (DNAm) variation would mediate the association of BMI with serum uric acid (SUA). We first conducted an epigenome-wide association analysis (EWAS) in 64 monozygotic twin pairs to detect BMI-related DNAm variation and then evaluated the mediated effect of DNAm using mediation analysis. Ontology enrichments analysis was performed for CpGs using GREAT tool. The genes where the candidate CpG mediators mapped were validated using gene expression data. BMI was positively associated with log10 transformed SUA level (β = 0.01, P < 0.001). The association between BMI and DNAm of 138 CpGs reached P < 1 × 10-4 level. Twenty BMI-related differentially methylated regions within MAP2K2, POU4F2, AGAP2, MRGPRE, ADM5, and NKX1-1 were found. Of the 138 CpGs, 4 within VENTX (involved in cellular responses to stress pathway), SMOC2 (enable calcium ion binding), and FSCN2 (a member of fascin protein family) mediated the association between BMI and SUA, with a mediating effect of 0.002-μmol/L lower log10 transformed SUA levels and a proportion of 18.89 %-24.92 % negative mediating effect. BMI × DNAm interactions on SUA were observed for 2 CpGs within VENTX. The gene expression level of VENTX was also negatively associated with SUA level. BMI-related DNAm variation may partially mediate the association of BMI with SUA.

Mitochondrial Dysfunction and Oxidative Stress in Rheumatoid Arthritis

Control of excessive mitochondrial oxidative stress could provide new targets for both preventive and therapeutic interventions in the treatment of chronic inflammation or any pathology that develops under an inflammatory scenario, such as rheumatoid arthritis (RA). Increasing evidence has demonstrated the role of mitochondrial alterations in autoimmune diseases mainly due to the interplay between metabolism and innate immunity, but also in the modulation of inflammatory response of resident cells, such as synoviocytes. Thus, mitochondrial dysfunction derived from several danger signals could activate tricarboxylic acid (TCA) disruption, thereby favoring a vicious cycle of oxidative/mitochondrial stress. Mitochondrial dysfunction can act through modulating innate immunity via redox-sensitive inflammatory pathways or direct activation of the inflammasome. Besides, mitochondria also have a central role in regulating cell death, which is deeply altered in RA. Additionally, multiple evidence suggests that pathological processes in RA can be shaped by epigenetic mechanisms and that in turn, mitochondria are involved in epigenetic regulation. Finally, we will discuss about the involvement of some dietary components in the onset and progression of RA.