The gout epidemic in French Polynesia: a modelling study of data from the Ma'i u'u epidemiological survey

BACKGROUND

Gout is the most common cause of inflammatory arthritis worldwide, particularly in Pacific regions. We aimed to establish the prevalence of gout and hyperuricaemia in French Polynesia, their associations with dietary habits, their comorbidities, the prevalence of the HLA-B*58:01 allele, and current management of the disease.

METHODS

The Ma'i u'u survey was epidemiological, prospective, cross-sectional, and gout-focused and included a random sample of adults from the general adult population of French Polynesia. It was conducted and data were collected between April 13 and Aug 16, 2021. Participants were randomly selected to represent the general adult population of French Polynesia on the basis of housing data collected during the 2017 territorial census. Each selected household was visited by a research nurse from the Ma'i u'u survey who collected data via guided, 1-h interviews with participants. In each household, the participant was the individual older than 18 years with the closest upcoming birthday. To estimate the frequency of HLA-B*58:01, we estimated HLA-B haplotypes on individuals who had whole-genome sequencing to approximately 5× average coverage (mid-pass sequencing). A subset of individuals who self-reported Polynesian ancestry and not European, Chinese, or other ancestry were used to estimate Polynesian-ancestry specific allele frequencies. Bivariate associations were reported for weighted participants; effect sizes were estimated through the odds ratio (OR) of the association calculated on the basis of a logistic model fitted with weighted observations.

FINDINGS

Among the random sample of 2000 households, 896 participants were included, 140 individuals declined, and 964 households could not be contacted. 22 participants could not be weighted due to missing data, so the final weighted analysis included 874 participants (449 [51·4%] were female and 425 [48·6%] were male) representing the 196 630 adults living in French Polynesia. The estimated prevalence of gout was 14·5% (95% CI 9·9-19·2), representing 28 561 French Polynesian adults, that is 25·5% (18·2-32·8) of male individuals and 3·5% (1·0-6·0) of female individuals. The prevalence of hyperuricaemia was estimated at 71·6% (66·7-76·6), representing 128 687 French Polynesian adults. In multivariable analysis, age (OR 1·5, 95% CI 1·2-1·8 per year), male sex (10·3, 1·8-60·7), serum urate (1·6, 1·3-2·0 per 1 mg/dL), uraturia (0·8, 0·8-0·8 per 100 mg/L), type 2 diabetes (2·1, 1·4-3·1), BMI more than 30 kg/m2 (1·1, 1·0-1·2 per unit), and percentage of visceral fat (1·7, 1·1-2·7 per 1% increase) were associated with gout. There were seven heterozygous HLA-B*58:01 carriers in the full cohort of 833 individuals (seven [0·4%] of 1666 total alleles) and two heterozygous carriers in a subset of 696 individuals of Polynesian ancestry (two [0·1%]).

INTERPRETATION

French Polynesia has an estimated high prevalence of gout and hyperuricaemia, with gout affecting almost 15% of adults. Territorial measures that focus on increasing access to effective urate-lowering therapies are warranted to control this major public health problem.

FUNDING

Variant Bio, the French Polynesian Health Administration, Lille Catholic University Hospitals, French Society of Rheumatology, and Novartis.

Genetic testing for misclassified monogenic diabetes in Māori and Pacific peoples in Aōtearoa New Zealand with early-onset type 2 diabetes

Aims

Monogenic diabetes accounts for 1-2% of diabetes cases yet is often misdiagnosed as type 2 diabetes. The aim of this study was to examine in Māori and Pacific adults clinically diagnosed with type 2 diabetes within 40 years of age, (a) the prevalence of monogenic diabetes in this population (b) the prevalence of beta-cell autoantibodies and (c) the pre-test probability of monogenic diabetes.

Methods

Targeted sequencing data of 38 known monogenic diabetes genes was analyzed in 199 Māori and Pacific peoples with BMI of 37.9 ± 8.6 kg/m² who had been diagnosed with type 2 diabetes between 3 and 40 years of age. A triple-screen combined autoantibody assay was used to test for GAD, IA-2, and ZnT8. MODY probability calculator score was generated in those with sufficient clinical information (55/199).

Results

No genetic variants curated as likely pathogenic or pathogenic were found. One individual (1/199) tested positive for GAD/IA-2/ZnT8 antibodies. The pre-test probability of monogenic diabetes was calculated in 55 individuals with 17/55 (31%) scoring above the 20% threshold considered for diagnostic testing referral.

Discussion

Our findings suggest that monogenic diabetes is rare in Māori and Pacific people with clinical age, and the MODY probability calculator likely overestimates the likelihood of a monogenic cause for diabetes in this population.

Trends in Prevalence of Gout Among US Asian Adults, 2011-2018

Importance

Gout disparities among Black individuals in the US have recently been explained by socioclinical factors; however, no information is available among Asian individuals living in Western countries, despite their disproportionately worsening metabolic health.

Objective

To determine the prevalence of gout and serum urate concentrations according to race and ethnicity and to explore the association of social determinants of health and clinical factors.

Design, Setting, and Participants

This is a population-based, cross-sectional analysis. Data from a nationally representative sample of US adults were obtained from the National Health and Nutrition Examination Survey (NHANES) (2011-2018) in which Asian race data were collected (primary). Data from the UK Biobank (2006-2021) were used for replication of the Asian vs White differences. Data analysis was performed from December 2021 to September 2022.

Main Outcomes and Measures

Race-specific gout prevalence and serum urate levels.

Results

A total of 22 621 participants from NHANES (2011-2018) were included in the analysis (mean [SD] age, 49.8 [17.8] years; 10 948 male participants [48.4%]). In 2017 to 2018, gout affected 12.1 million US individuals, with its crude prevalence increasing from 3.6% (95% CI, 2.8%-4.5%) in 2011 to 2012 to 5.1% (95% CI, 4.2%-5.9%) in 2017 to 2018 (P for trend = .03); this trend was no longer significant after age adjustment (P for trend = .06) or excluding Asian individuals (P for trend = .11). During the same period, age- and sex-adjusted prevalence among Asian Americans doubled from 3.3% (95% CI, 2.1%-4.5%) to 6.6% (95% CI, 4.4%-8.8%) (P for trend = .007) to numerically exceed all other racial and ethnic groups in 2017 to 2018, with age- and sex-adjusted odds ratio (ORs) of 1.61 (95% CI, 1.03-2.51) and a socioclinical factor-adjusted multivariable OR of 2.62 (95% CI, 1.59-4.33) for Asian vs White individuals. The latest age- and sex-adjusted gout prevalence among US individuals aged 65 years and older was 10.0% among White individuals and 14.8% among Asian individuals (including 23.6% of Asian men). Serum urate concentrations also increased between 2011 and 2018 among US Asian individuals (P for trend = .009). The Asian vs White disparity was also present in the UK Biobank.

Conclusions and Relevance

The findings of this study suggest that the prevalence of gout among Asian individuals numerically surpassed that for all other racial and ethnic groups in 2017 to 2018. This Asian vs White disparity did not appear to be associated with socioclinical factors.

Folic acid and methotrexate use and their association with COVID-19 diagnosis and mortality: a case-control analysis from the UK Biobank

OBJECTIVE

To determine if methotrexate or folic acid prescription was associated with differential risk for COVID-19 diagnosis or mortality.

DESIGN

Case-control analysis.

SETTING

The population-based UK Biobank (UKBB) cohort.

PARTICIPANTS

Data from 380 380 UKBB participants with general practice prescription data for 2019-2021. Updated medical information was retrieved on 13 December 2021.

PRIMARY AND SECONDARY OUTCOME MEASURES

The outcomes of COVID-19 diagnosis and COVID-19-related mortality were analysed by multivariable logistic regression. Exposures evaluated were prescription of folic acid and/or methotrexate. Criteria for COVID-19 diagnosis were (1) a positive SARS-CoV-2 test or (2) ICD-10 code for confirmed COVID-19 (U07.1) or probable COVID-19 (U07.2) in hospital records, or death records. By these criteria, 26 003 individuals were identified with COVID-19 of whom 820 were known to have died from COVID-19. Logistic regression statistical models were adjusted for age sex, ethnicity, Townsend deprivation index, body mass index, smoking status, presence of rheumatoid arthritis, sickle cell disease, use of anticonvulsants, statins and iron supplements.

RESULTS

Compared with people prescribed neither folic acid nor methotrexate, people prescribed folic acid supplementation had increased risk of diagnosis of COVID-19 (OR 1.51 (1.42-1.61)). The prescription of methotrexate with or without folic acid was not associated with COVID-19 diagnosis (p≥0.18). People prescribed folic acid supplementation had positive association with death after a diagnosis of COVID-19 (OR 2.64 (2.15-3.24)) in a fully adjusted model. The prescription of methotrexate in combination with folic acid was not associated with an increased risk for COVID-19-related death (1.07 (0.57-1.98)).

CONCLUSIONS

We report an association of increased risk for COVID-19 diagnosis and COVID-19-related death in people prescribed folic acid supplementation. Our results also suggest that methotrexate might attenuate these associations.

POS0155 WHAT DRIVES RACIAL DISPARITIES IN GOUT IN THE US? – POPULATION-BASED, SEX-SPECIFIC, CASUAL MEDIATION ANALYSIS

Background

Traditionally viewed as a disease of White men, global frequency and disability burden of female gout are rising disproportionately to male gout.1 Moreover, emerging US cohort data suggest gout and hyperuricemia impart larger burdens on Black adults than Whites.2 These racial disparities may be largely attributable to differences in non-genetic, mainly modifiable gout risk factors e.g., BMI, diet,3,4 and chronic kidney disease (CKD). However, national-level, general population data on racial differences in burden of gout, and potential mediators, are lacking.

Objectives

To determine and quantify sex-specific mediators of racial disparities in gout prevalence among a nationally representative sample of US adults.

Methods

Using recent decadal data (2007-2016) on physician-diagnosed gout and hyperuricemia from the National Health and Nutrition Examination Survey, we compared contemporary sex- and race-specific prevalences and conducted sequential causal mediation analysis (adjusting for upstream mediators following causal pathways)5 to determine the proportion of the racial differences attributable to 7 potentially mediating social and clinical factors (see DAG in Figure 1): low education, poverty, body mass index (BMI), alcohol, poor quality diet (poor DASH adherence), diuretic use, and CKD (eGFR <60 mL/min, using the latest equations that do not include a coefficient for Black race6, per National Kidney Foundation and American Society of Nephrology recommendations.7)

Results

Age standardised prevalence of gout was 3.5% and 2.0% in Black and White women, respectively (age-adjusted OR =1.8 [95% CI: 1.3 to 2.5]), and 7.0% and 5.4% in Black and White men (age-adjusted OR =1.3 [1.0 to 1.6]). Most risk factors were more frequent/elevated in Blacks than Whites, except alcohol consumption, which was lower in Blacks (both sexes). BMI levels and poverty were higher in Black women, but similar between Black and White men.

Largest mediating factor of excess gout cases among Black women was excess BMI, accounting for 56% of the racial difference (independent of education, poverty, diet, and alcohol), followed by CKD (24%), poverty (17%), and poor diet (12%) (see Table 1).

Table 1.

Indirect (mediation) effects of potential mediators, using sequential mediation analysis, for the association between Black race and odds of gout in US women and men.

WOMENMENEffect Estimate (OR), 95% CIProportion Mediated, %Effect Estimate (OR), 95% CIProportion Mediated, %Indirect (Mediation) EffectEducation (high school or less)1.01 (0.98 to 1.03)2.4%1.01 (0.98 to 1.03)3.3%Poverty1.07 (1.04 to 1.10)16.9%1.00 (0.99 to 1.00)0.53%Alcohol consumption (# drinks/week, continuous)0.99 (0.96 to 1.01)-3.4%0.99 (0.98 to 1.00)-4.5%DASH diet score (continuous; higher scores = ↓ adherence)1.05 (0.96 to 1.01)12.0%1.05 (1.01 to 1.10)19.8%Body mass index (continuous)1.25 (1.14 to 1.37)55.9%1.03 (1.02 to 1.04)11.9%Diuretic use1.03 (1.01 to 1.05)7.6%1.04 (1.02 to 1.06)14.2%Chronic kidney disease1.10 (1.04 to 1.16)23.9%1.12 (1.08 to 1.17)45.6%Direct Effect0.94 (0.68 to 1.30)a−15.2%1.02 (0.83 to 1.26)b9.2%Total Effect1.49 (1.12 to 1.98)100%1.29 (1.05 to 1.57)100%

DASH=Dietary Approaches to Stop Hypertension;

ap=0.52,

bp=0.83

Among men, CKD was the largest mediator (46%), followed by poor diet (20%) and diuretic use (14%). BMI (12%) and poverty (0.5%) mediated smaller proportions of the racial difference among men compared to women. Mediators of racial differences in hyperuricemia closely agreed with gout results.

Conclusion

Contrasting with historical views, gout is more frequent among Black adults in the US than their White counterparts, especially women (two-times greater in Black women vs. White). Culturally informed efforts to reduce these disparities should focus on excess adiposity, diet quality, and kidney disease while recognising the impact of poverty in female gout.

References

[1]Xia; PMID 31624843

[2]PMID 24335384

[3]Rai BMJ PMID 28487277

[4]Yokose JAMA IM (2022)

[5]VanderWeele; PMID 25580377

[6]NEJM PMID 34554658

[7]JASN PMID 34556489

Disclosure of Interests

Natalie McCormick: None declared, Leo Lu: None declared, Chio Yokose: None declared, Amit Joshi: None declared, Tony Merriman: None declared, Kenneth Saag Consultant of: Arthrosi, Atom Bioscience, Horizon Therapeutics, LG Pharma, Mallinkrodt, SOBI, Takeda, Grant/research support from: Horizon Therapeutics, SOBI, Shanton, Yuqing Zhang: None declared, Hyon Choi Consultant of: Ironwood, Selecta, Horizon, Takeda, Kowa, and Vaxart.

Grant/research support from: Ironwood, Horizon

POS1222 FOLIC ACID AND METHOTREXATE USE AND THEIR ASSOCIATION WITH COVID-19 DIAGNOSIS AND MORTALITY: AN ANALYSIS FROM THE UK BIOBANK

Background

Folate metabolism is implicated in SARS-CoV-2 infectivity (Ref).

Objectives

To determine if methotrexate (an antifolate) or folic acid prescription were associated with a lowered and increased risk, respectively, for COVID-19 diagnosis or mortality in a large population-based cohort (UK Biobank).

Methods

Data from 380,380 UK Biobank participants with general practice prescription data were used. Criteria for COVID-19 diagnosis were 1) a positive SARS-CoV-2 test and / or 2) ICD-10 code for confirmed COVID-19 (U07.1) or probable COVID-19 (U07.2) in hospital records, or death records. This definition identified 26,003 individuals diagnosed with COVID-19 of whom 820 were known to have died from COVID-19. Logistic regression statistical models were adjusted for age group (4 categories), sex, ethnicity, Townsend deprivation index, BMI, smoking status, presence of rheumatoid arthritis, sickle cell disease, use of anticonvulsants, statins and iron supplements.

Results

Compared with people prescribed neither folic acid nor methotrexate, people prescribed folic acid supplementation had increased risk of diagnosis of COVID-19 (OR 1.51 [1.42; 1.61]). The prescription of methotrexate with or without folic acid was not associated with COVID-19 diagnosis (P≥0.18). Compared with people prescribed neither folic acid nor methotrexate, people prescribed folic acid supplementation had an increased risk of death after a diagnosis of COVID-19 (OR 2.64 [2.15; 3.24]) in a fully adjusted model. The prescription of methotrexate in combination with folic acid was not associated with an increased risk for death after a diagnosis of COVID-19 (1.07 [0.57; 1.98]). (Table 1)

Table 1.

COVID-19 diagnosis and associated death in people prescribed methotrexate and / or folic acid in the UKBB, compared to people not prescribed methotrexate or folic acid. Model 1 adjusted for age group, sex, ethnicity, Townsend deprivation index, BMI, smoking status Model 2 is model 1 plus adjustment by the presence of rheumatoid arthritis, sickle cell disease, use of statins, anticonvulsants and iron supplementation.

UnadjustedModel 1Model 2OR[95% CI]POR[95% CI]POR[95% CI]PNeither Folic acid nor Methotrexate1.0-1.0-1.0-COVID-19 diagnosisFolic acid only1.58[1.49; 1.68]<0.0011.60[1.50; 1.70]<0.0011.51[1.42; 1.61]<0.001Methotrexate and Folic acid1.09[0.96; 1.23]0.181.15[1.02; 1.30]0.0211.09[0.96; 1.23]0.18COVID-19 associated deathFolic acid only5.14 [4.23; 6.24]<0.0012.91 [2.38; 3.55]<0.0012.64[2.15; 3.24]<0.001Methotrexate and folic acid1.47 [0.81; 2.67]0.211.26 [0.70; 2.30]0.441.07 [0.57; 1.98]0.84

Conclusion

We report increased risk for COVID-19 diagnosis and COVID-19-related death for people prescribed folic acid supplementation. The prescription and use of supplemental folic acid may confer risk of infection with the SARS-CoV-2 virus as well as the risk of death resulting from COVID-19. Our results also suggest that methotrexate might attenuate an increased risk for COVID-19 diagnosis and death conferred by folic acid.

References

[1]Zhang Y, Guo R, Kim SH, et al. SARS-CoV-2 hijacks folate and one-carbon metabolism for viral replication. Nature Communications 2021;12(1):1676. doi: 10.1038/s41467-021-21903-z

Disclosure of Interests

Ruth Topless: None declared, Ralph Green: None declared, Sarah Morgan: None declared, Philip Robinson Consultant of: Abbvie, Atom Biosciences, Eli Lilly, Gilead, Janssen, Novartis, UCB, Roche, Pfizer, Grant/research support from: Janssen, Novartis, Pfizer and UCB Pharma, Tony Merriman: None declared, Angelo Gaffo Consultant of: SOBI, Selecta

694Metabolic conditions have high prevalence in CHamoru men in a hyperuricemia feasibility study in Guam

Background

One-third of adults in the U.S. have metabolic syndrome, a combination of risk factors of chronic diseases such as heart disease, kidney disease, diabetes, and gout. These diseases are a burden for ethnic minorities, including Pacific Island peoples. Here, the metabolic conditions were described for a group of Pacific Island people, the CHamorus or natives of Guam, a U.S. Territory in the Mariana Islands in the Western Pacific.

Methods

A cross-sectional survey was conducted in Guam from August 2019 to January 2020. A non-random sample of 152 adults, ≥18 years old, with CHamoru ancestry were recruited and consented. Information collected included socio-demographics, metabolic history, lifestyle behaviors, height and weight, blood pressure, and non-fasting blood and urine. Statistical analyses included frequencies of metabolic conditions and Pearson’s Chi-square test for gender differences, alpha=0.05.

Results

Of the 152 CHamorus, 49.3% were male, 50% were female, and 0.7% was transgender. The mean age was 43±15.1 years. Mean education was 14.4±3.6 years and hyperuricemia he majority (69.7%) pursued postsecondary studies. Self-reported metabolic conditions included: diabetes (19.7%), gout (28.9%), hypertension (34.9%), dyslipidemia (17.8%), and heart conditions (9.9%). Compared to females, more males reported gout (40.5% versus 18.7%; P=.003) and measured to be hypertensive (48% versus 21.1%; P&lt;.0001), hyperuricemic (58.9% versus 31.6%; P=.001), and obese (77.3% versus 46.1%; P&lt;.0001).

Conclusion

Metabolic conditions were common among CHamorus, though gout, hypertension, hyperuricemia, and obesity were predominant in the men.

Key messages

Strategies to reduce the burden of metabolic conditions may be targeted to CHamoru men in this community.

Associations Between Sugars Intakes and Urinary Sugars Excretion and Carbon Stable Isotope Ratios in Red Blood Cells as Biomarkers of Sugars Intake in a Predominantly Māori Population

Determining the extent to which added sugars intake contribute to non-communicable disease in various populations is challenging because it is difficult to accurately measure intakes. Biomarkers may provide a reliable and easily measured method of assessing intakes. In a predominantly Māori population we compared various sugars intake estimates derived from a 36 item sugar-specific food frequency questionnaire (FFQ) with biomarkers of sugars intake; urinary sugars excretion in random spot collections (n = 153) and carbon stable isotope ratios (n = 36) in red blood cells (RBCs, δ¹³C_RBC) and in the alanine fraction of the RBCs (δ¹³C_alanine). Estimated 24 h urinary sucrose+fructose excretion was statistically significantly correlated with intakes of total sugars (r = 0.23), sucrose (r = 0.26) and added sugars from sugar-sweetened beverages (SSBs; r = 0.26). δ¹³C_alanine was correlated with added sugars (r = 0.40). In log linear multiple regression models adjusted with HbA1C and eGFR δ¹³C_alanine predicted added sugars intakes (r ² = 0.29) and estimated 24 h urinary sucrose+fructose excretion predicted intakes of total sugars (r ² = 0.14), sucrose (r ² = 0.17), added sugars (r ² = 0.17) and sugars from SSBs (r ² = 0.14). These biomarkers have potential for improving assessment of sugars intake in New Zealand populations enabling monitoring of the effectiveness of sugar reduction strategies designed to reduce risk of NCDs. However, further validation is required to confirm these preliminary findings.

What predicts regression from pre-diabetes to normal glucose regulation following a primary care nurse-delivered dietary intervention? A study protocol for a prospective cohort study

INTRODUCTION

Pre-diabetes is a high-risk state for the development of type 2 diabetes mellitus (T2DM) and cardiovascular disease. Regression to normoglycaemia, even if transient, significantly reduces the risk of developing T2DM. The primary aim of this mixed-methods study is to determine if there are clinically relevant differences among those with pre-diabetes and excess weight who regress to normoglycaemia, those who have persistent pre-diabetes and those who progress to T2DM following participation in a 6-month primary care nurse-delivered pre-diabetes dietary intervention. Incidence of T2DM at 2 years will be examined.

METHODS AND ANALYSIS

Four hundred participants with pre-diabetes (New Zealand definition glycated haemoglobin 41-49 mmol/mol) and a body mass index >25 kg/m² will be recruited through eight primary care practices in Hawke's Bay, New Zealand. Trained primary care nurses will deliver a 6-month structured dietary intervention, followed by quarterly reviews for 18 months post-intervention. Clinical data, data on lifestyle factors and health-related quality of life (HR-QoL) and blood samples will be collected at baseline, 6 months, 12 months and 24 months. Sixty participants purposefully selected will complete a semi-structured interview following the 6-month intervention. Poisson regression with robust standard errors and clustered by practice will be used to identify predictors of regression or progression at 6 months, and risk factors for developing T2DM at 2 years. Qualitative data will be analysed thematically. Changes in HR-QoL will be described and potential cost savings will be estimated from a funder's perspective at 2 years.

ETHICS AND DISSEMINATION

This study was approved by the Northern A Health and Disability Ethics Committee, New Zealand (Ethics Reference: 17/NTA/24). Study results will be presented to participants, published in peer-reviewed journals and presented at relevant conferences.

TRIAL REGISTRATION NUMBER

ACTRN12617000591358; Pre-results.

Gout, Hyperuricaemia and Crystal-Associated Disease Network (G-CAN) consensus statement regarding labels and definitions of disease states of gout

OBJECTIVE

There is a lack of standardisation in the terminology used to describe gout. The aim of this project was to develop a consensus statement describing the recommended nomenclature for disease states of gout.

METHODS

A content analysis of gout-related articles from rheumatology and general internal medicine journals published over a 5-year period identified potential disease states and the labels commonly assigned to them. Based on these findings, experts in gout were invited to participate in a Delphi exercise and face-to-face consensus meeting to reach agreement on disease state labels and definitions.

RESULTS

The content analysis identified 13 unique disease states and a total of 63 unique labels. The Delphi exercise (n=76 respondents) and face-to-face meeting (n=35 attendees) established consensus agreement for eight disease state labels and definitions. The agreed labels were as follows: 'asymptomatic hyperuricaemia', 'asymptomatic monosodium urate crystal deposition', 'asymptomatic hyperuricaemia with monosodium urate crystal deposition', 'gout', 'tophaceous gout', 'erosive gout', 'first gout flare' and 'recurrent gout flares'. There was consensus agreement that the label 'gout' should be restricted to current or prior clinically evident disease caused by monosodium urate crystal deposition (gout flare, chronic gouty arthritis or subcutaneous tophus).

CONCLUSION

Consensus agreement has been established for the labels and definitions of eight gout disease states, including 'gout' itself. The Gout, Hyperuricaemia and Crystal-Associated Disease Network recommends the use of these labels when describing disease states of gout in research and clinical practice.

mTOR inhibition by metformin impacts monosodium urate crystal-induced inflammation and cell death in gout: a prelude to a new add-on therapy?

OBJECTIVE

Gout is the most common inflammatory arthritis worldwide, and patients experience a heavy burden of cardiovascular and metabolic diseases. The inflammation is caused by the deposition of monosodium urate (MSU) crystals in tissues, especially in the joints, triggering immune cells to mount an inflammatory reaction. Recently, it was shown that MSU crystals can induce mechanistic target of rapamycin (mTOR) signalling in monocytes encountering these crystals in vitro. The mTOR pathway is strongly implicated in cardiovascular and metabolic disease. We hypothesised that inhibiting this pathway in gout might be a novel avenue of treatment in these patients, targeting both inflammation and comorbidities.

METHODS

We used a translational approach starting from ex vivo to in vitro and back to in vivo.

RESULTS

We show that ex vivo immune cells from patients with gout exhibit higher expression of the mTOR pathway, which we can mimic in vitro by stimulating healthy immune cells (B lymphocytes, monocytes, T lymphocytes) with MSU crystals. Monocytes are the most prominent mTOR expressers. By using live imaging, we demonstrate that monocytes, on encountering MSU crystals, initiate cell death and release a wide array of proinflammatory cytokines. By inhibiting mTOR signalling with metformin or rapamycin, a reduction of cell death and release of inflammatory mediators was observed. Consistent with this, we show that patients with gout who are treated with the mTOR inhibitor metformin have a lower frequency of gout attacks.

CONCLUSIONS

We propose mTOR inhibition as a novel therapeutic target of interest in gout treatment.

Genomic Influences on Hyperuricemia and Gout

Genome-wide association studies (GWAS) have identified nearly 30 loci associated with urate concentrations that also influence the subsequent risk of gout. The ABCG2 Q141 K variant is highly likely to be causal and results in internalization of ABCG2, which can be rescued by drugs. Three other GWAS loci contain uric acid transporter genes, which are also highly likely to be causal. However identification of causal genes at other urate loci is challenging. Finally, relatively little is known about the genetic control of progression from hyperuricemia to gout. Only 4 small GWAS have been published for gout.

Elevated serum uric acid levels are associated with endothelial dysfunction in HIV patients receiving highly-active antiretroviral therapy

BACKGROUND AND AIMS

Elevated serum uric acid (SUA) levels may be associated with endothelial dysfunction. Increased rates of metabolic syndrome (MS) and elevated SUA levels were described in human immunodeficiency virus (HIV) infected patients. We investigated whether SUA levels are associated with endothelial dysfunction in HIV positive patients receiving highly-active antiretroviral therapy (HAART) irrespective of MS.

METHODS

In this cross-sectional study of 250 HIV positive patients receiving stable HAART, we evaluated the relationship between MS, SUA levels and endothelial function. SUA levels and brachial artery flow-mediated dilation (bFMD) were measured. The relationship between logarithmic (LG)-transformed SUA levels and bFMD was evaluated after correction for MS.

RESULTS

MS was detected in 28.4% of patients and elevated SUA levels (≥6 mg/dL) in 25.2%. MS was associated with higher LG-SUA levels (age-, gender- and glomerular filtration rate-adjusted beta = 0.204, p = 0.001). The crude linear association between LG-SUA levels and LG-bFMD (beta = -0.166, p = 0.008) was abolished after correction for MS (beta = -0.089, p = 0.172). When SUA levels were used as a categorical variable (≥6 mg/dL or <6 mg/dL and SUA quartiles, respectively), the association between LG-SUA levels and LG-bFMD remained significant after adjustment for MS (beta = -0.142, p = 0.022 and beta = -0.163, p = 0.010, respectively).

CONCLUSIONS

MS significantly affects SUA levels in HAART-treated HIV infected patients. The negative association between SUA and bFMD is independent of MS only for elevated SUA levels.

Brief Report: IRF4 Newly Identified as a Common Susceptibility Locus for Systemic Sclerosis and Rheumatoid Arthritis in a Cross-Disease Meta-Analysis of Genome-Wide Association Studies

OBJECTIVE

Systemic sclerosis (SSc) and rheumatoid arthritis (RA) are autoimmune diseases that have similar clinical and immunologic characteristics. To date, several shared SSc-RA genetic loci have been identified independently. The aim of the current study was to systematically search for new common SSc-RA loci through an interdisease meta-genome-wide association (meta-GWAS) strategy.

METHODS

The study was designed as a meta-analysis combining GWAS data sets of patients with SSc and patients with RA, using a strategy that allowed identification of loci with both same-direction and opposite-direction allelic effects. The top single-nucleotide polymorphisms were followed up in independent SSc and RA case-control cohorts. This allowed an increase in the sample size to a total of 8,830 patients with SSc, 16,870 patients with RA, and 43,393 healthy controls.

RESULTS

This cross-disease meta-analysis of the GWAS data sets identified several loci with nominal association signals (P < 5 × 10(-6) ) that also showed evidence of association in the disease-specific GWAS scans. These loci included several genomic regions not previously reported as shared loci, as well as several risk factors that were previously found to be associated with both diseases. Follow-up analyses of the putatively new SSc-RA loci identified IRF4 as a shared risk factor for these 2 diseases (Pcombined  = 3.29 × 10(-12) ). Analysis of the biologic relevance of the known SSc-RA shared loci identified the type I interferon and interleukin-12 signaling pathways as the main common etiologic factors.

CONCLUSION

This study identified a novel shared locus, IRF4, for the risk of SSc and RA, and highlighted the usefulness of a cross-disease GWAS meta-analysis strategy in the identification of common risk loci.

Culturally appropriate advisory and governance oversight for the study of rheumatic fever and rheumatic heart disease in New Zealand

Acute rheumatic fever (ARF) is an autoimmune condition caused by untreated Group A Streptococcal (GAS) infection of the upper respiratory tract (and possibly skin). Multiple or severe attacks of ARF can cause cardiac damage, known as Rheumatic Heart Disease (RHD). RHD remains a significant cause of morbidity and mortality is rare in developed countries. In New Zealand, the disease burden of ARF and RHD amongst Indigenous Maori and Pasifika communities is one of the highest in the world, usually affecting children and young adults. Previous work carried out in New Zealand sought to explore the immunogenetics of ARF and RHD and involved candidate gene analysis techniques utilizing samples from individuals diagnosed with RHD where a functional variant in the gene encoding the interleukin IL-6 cytokine known as IL-6 rs1800797 was found to be significantly associated with RHD. Current work seeks to explore the genetic susceptibility to ARF/RHD in greater depth using more advanced genome-wide technology. An international genome wide association study (GWAS) is currently underway to further understand the genetics of ARF/RHD using data obtained from global sources. To undertake the proposed GWAS work and amend the original New Zealand study, an Advisory team comprised of Pasifika and Māori representatives comprised of community leaders, researchers, scientists, and academics is providing the appropriate governance, cultural support and guidance essential for the project work.

Uric acid and bone mineral density in postmenopausal osteoporotic women: the link lies within the fat

The association between serum uric acid (SUA) levels and bone mineral density (BMD) is controversial. Fat accumulation is linked to SUA and BMD, thus possibly explaining the mixed results. We found that adiposity drives part of the association between SUA and BMD in women with postmenopausal osteoporosis.

INTRODUCTION

Both positive and negative associations between SUA and BMD have been reported. SUA levels and BMD increase with higher body weight and other indices of adiposity; hence, the association between SUA and BMD might be a consequence of the confounding effect of adiposity. We investigated in this cross-sectional study whether the association between SUA and BMD is independent of measures of fat accumulation and other potential confounders.

METHODS

SUA levels, femur BMD, markers of bone metabolism, body mass index (BMI), fat mass (FM), waist circumference (WC), and abdominal visceral fat area were measured in 180 treatment-naive postmenopausal osteoporotic women (mean age 66.3 ± 8.5 years, age range 48-81 years).

RESULTS

Women with higher SUA levels (third tertile) had significantly higher femur BMD and lower cross-linked C-terminal telopeptide of type I collagen (CTX) and bone alkaline phosphatase (bALP) levels. SUA levels were positively associated with all indices of adiposity. In multivariable analysis with femur BMD as dependent variable, the association between logarithmic (LG)-transformed SUA levels and BMD (beta = 0.42, p < 0.001) was lessened progressively by the different indices of adiposity, like LG-BMI (beta = 0.22, p = 0.007), LG-WC (beta = 0.21, p = 0.01), LG-FM (beta = 0.18, p = 0.01), and LG-abdominal visceral fat area (beta = 0.12, p = 0.05). The association between SUA levels and markers of bone metabolism was dependent on the effect of confounders.

CONCLUSION

In postmenopausal osteoporotic women, the strong univariable association between SUA levels and femur BMD is partly explained by the confounding effect of indices of adiposity.

Lack of gene-diuretic interactions on the risk of incident gout: the Nurses' Health Study and Health Professionals Follow-up Study

BACKGROUND

Diuretic-induced gout might occur only among those with a genetic predisposition to hyperuricaemia, as suggested by a recent study with 108 self-reported gout cases.

METHODS

We examined the role of urate genes on the risk of diuretic-induced incident gout in 6850 women from the Nurses' Health Study (NHS) and in 4223 men from the Health Professionals Follow-up Study (HPFS). Two published genetic risk scores (GRSs) were calculated using urate-associated single-nucleotide polymorphisms for 8 (GRS8) and 29 genes (GRS29).

RESULTS

Our analyses included 727 and 354 confirmed incident gout cases in HPFS and NHS, respectively. The multivariate relative risk (RR) for diuretic use was 2.20 and 1.69 among those with GRS8 < and ≥ the median (p for interaction=0.27). The corresponding RRs using GRS29 were 2.19 and 1.88 (p for interaction=0.40). The lack of interaction persisted in NHS (all p values >0.20) and in our analyses limited to those with hypertension in both cohorts. SLC22A11 (OAT4) showed a significant interaction only among women but in the opposite direction to the recent study.

CONCLUSIONS

In these large prospective studies, individuals with a genetic predisposition for hyperuricaemia are not at a higher risk of developing diuretic-induced gout than those without.

Fat storage syndrome in Pacific peoples: a combination of environment and genetics?

Pacific people (especially Micronesian and Polynesian) have some of the highest rates of obesity and diabetes in the world that largely developed since the introduction of western culture and diet. Recent studies suggest that much of the risk relates to the excessive intake of sugar (sucrose) and carbohydrates, leading to a type of fat storage syndrome (metabolic syndrome). Here we discuss some of the environmental. genetic and epigenetic reasons why this group might be especially prone to developing obesity and diabetes compared to other ethnic groups. Indirect evidence suggests that the higher endogenous uric acid levels in the Polynesian-Micronesian population may represent a predisposing factor for the development of obesity and diabetes in the context of Western diets and lifestyles. Pacific people may be an ideal group to study the role of "thrifty genes" in the pathogenesis of the current obesity epidemic.

Association of CD247 polymorphisms with rheumatoid arthritis: a replication study and a meta-analysis

Given the role of CD247 in the response of the T cells, its entailment in autoimmune diseases and in order to better clarify the role of this gene in RA susceptibility, we aimed to analyze CD247 gene variants previously associated with other autoimmune diseases (rs1052237, rs2056626 and rs864537) in a large independent European Caucasian population. However, no evidence of association was found for the analyzed CD247 single-nucleotide polymorphisms (SNPs) with RA and with the presence/absence of anti-cyclic citrullinated polypeptide. We performed a meta-analysis including previously published GWAS data from the rs864537 variant, revealing an overall genome-wide significant association between this CD247 SNP and RA with anti-CCP (OR = 0.90, CI 95% = 0.87-0.93, Poverall = 2.1×10(-10)). Our results show for first time a GWAS-level association between this CD247 polymorphism and RA risk.

Crystal ball gazing: new therapeutic targets for hyperuricaemia and gout

Recent studies in diverse disciplines have led to significant advances in the understanding of the basic biology of hyperuricaemia and gout, with important implications for future treatment. These findings include genetic variation within SLC2A9 as a key regulator of urate homeostasis, and identification of urate-anion exchanger urate transporter 1 (URAT1) and other renal uric acid transporters. Recognition of urate as an endogenous danger signal and activator of the adaptive immune response suggests an important role for urate crystals in non-microbial immune surveillance. The central role of NALP3 inflammasome activation and IL-1beta signalling in the initiation of the acute gout attack raises the possibility of new therapeutic targets. Disordered osteoclastogenesis in patients with chronic gout highlights potential therapies for prevention of joint damage. This review summarizes these findings and the potential relevance for future management of gout.

Debunking the myths to provide 21st Century management of gout

Epidemiologic and recent qualitative research suggests that the impact of under-treated gout is far more significant than many health professionals realise. The magnitude of this impact for Maaori and Pacific men of working age has been identified as a particular concern by the recently formed Maaori Gout Action Group in Counties Manukau District Health Board (South Auckland, New Zealand). The Group has identified that to achieve modern management of gout, those with gout need to be supported by primary care practitioners who are aware of the need for early intervention with allopurinol, as well as whaanau/families and communities who understand the impact and causes of gout and the lifestyle changes that are needed alongside long-term allopurinol. The Group wishes to support further research into the impact and causes of gout, particularly for Maaori, and to develop strategic alliances to ensure that the treatment and prevention of gout is advocated by those working with conditions such as diabetes and cardiovascular disease where gout is a frequent comorbidity.

A novel diffuse gastric cancer susceptibility variant in E-cadherin (CDH1) intron 2: a case control study in an Italian population

BACKGROUND

Inherited genetic factors such as E-cadherin (CDH1) promoter variants are believed to influence the risk towards sporadic diffuse gastric cancer (DGC). Recently, a new regulatory region essential for CDH1 transcription has been identified in CDH1 intron 2.

METHODS

We genotyped all known polymorphisms located within conserved sequences of CDH1 intron 2 (rs10673765, rs9932686, rs1125557, rs9282650, rs9931853) in an Italian population consisting of 134 DGC cases and 100 healthy controls (55 patient relatives and 45 unrelated, matched individuals). The influence of individual variants on DGC risk was assessed using chi2-tests and logistic regression. The relative contribution of alleles was estimated by haplotype analysis.

RESULTS

We observed a significant (p < 0.0004) association of the CDH1 163+37235G>A variant (rs1125557) with DGC risk. Odds ratios were 4.55 (95%CI = 2.09-9.93) and 1.38 (95%CI = 0.75-2.55) for AA and GA carriers, respectively. When adjusted for age, sex, smoking status, alcohol intake and H. pylori infection, the risk estimates remained largely significant for AA carriers. Haplotype analysis suggested the 163+37235A-allele contributes to disease risk independently of the other variants studied.

CONCLUSION

The CDH1 163+37235G>A polymorphism may represent a novel susceptibility variant for sporadic DGC if confirmed in other populations. Considering the broad expression of E-cadherin in epithelia, this exploratory study encourages further evaluation of the 163+37235A-allele as a susceptibility variant in other carcinomas.

Risk-taking: behind the warrior gene story

In 2006, the monoamine oxidase-A gene was widely reported in the media as being associated with risk-taking and aggressive behaviour in Māori. We examine the scientific evidence underlying this claim. Whilst there is credible evidence for a contribution of a monoamine oxidase-A genetic variant to antisocial behaviour in Caucasians, there is no direct evidence to support such an association in Māori. Insufficient rigour in interpreting and applying the relevant literature, and in generating new data, has (in conjunction with a lack of scientific investigative journalism) done science and Māori a disservice.

Association of CDH1 haplotypes with susceptibility to sporadic diffuse gastric cancer

Truncating mutations in the gene for the cell to cell adhesion protein E-cadherin are the most consistent genetic alterations observed in sporadic and hereditary diffuse gastric cancer (DGC). In addition to these inactivating mutations, a CDH1 promoter polymorphism at position -160 has been reported to lead to transcriptional downregulation of the gene in vitro. We therefore performed a case-control study to investigate whether this variant is associated with an increased susceptibility to DGC. The frequency of the -160A allele was significantly higher (P<0.005) in 53 diffuse gastric cancer cases compared to 70 matched controls. The odds ratio associated with the A-allele was 2.27 for CA-heterozygotes (95%CI 1.16-4.44) and 7.84 for AA-homozygotes (95%CI 2.89-21.24). Two additional polymorphisms (the 48+6T-->C and the 2076C-->T variant) were genotyped and shown to be equally distributed among cases and controls. Haplotype analysis with the three polymorphisms confirmed an association with disease (P<0.004). However, this analysis suggested the -160C-->A CDH1 promoter polymorphism may be in linkage disequilibrium with a distinct aetiological locus or acts in combination with other functional variants in or near the CDH1 region.

Novel germline CDH1 mutations in hereditary diffuse gastric cancer families

Hereditary diffuse gastric cancer (HDGC) is a recently defined cancer syndrome caused by inactivating, heterozygous germline mutations in the gene for the cell-to-cell adhesion protein E-cadherin (CDH1). Here, we describe the search for CDH1 mutations in 10 newly identified gastric cancer families. Seven of 10 families met the clinical criteria for HDGC. Germline mutations were identified in four of these seven families and one family that was borderline for the clinical criteria. Of the mutations identified in the five new families, four were previously unreported and consisted of two frameshift and two donor splice site mutations. One splice site mutation occurred at the 100% conserved +1 position. The second splice site mutation occurred at the +5 position and was shown to lead to abnormal splicing. Additional CDH1 variants detected include the heterozygous -160 C-->A promoter polymorphism, which has previously been reported to be associated with decreased CDH1 transcription. We, however, found this polymorphism to be common in a control population, suggesting that a major role for this polymorphism in gastric cancer susceptibility is unlikely.