Association of serum uric acid with cardiovascular disease in rheumatoid arthritis

A Systematic Review and Meta-Analysis of the Association between Uric Acid and Allantoin and Rheumatoid Arthritis

Alterations in the circulating concentrations of uric acid and its degradation product, allantoin, might account for the systemic pro-oxidant state and the increased cardiovascular risk in rheumatoid arthritis (RA). We sought to address this issue by conducting a systematic review and meta-analysis of the association between the plasma/serum concentrations of uric acid and allantoin and RA. We searched PubMed, Scopus, and Web of Science from inception to 20 June 2023 for studies comparing plasma/serum concentrations of uric acid and allantoin between RA patients and healthy controls. We assessed the risk of bias with the JBI Critical Appraisal Checklist for analytical studies and the certainty of evidence with the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) Working Group system. In the 19 studies selected for analysis, there were non-significant differences in uric acid concentrations between RA patients and controls (standard mean difference, SMD = 0.11, 95% CI -0.07 to 0.30, p = 0.22; I2 = 87.9%, p < 0.001; low certainty of evidence). By contrast, the concentrations of allantoin were significantly higher in RA patients (SMD = 1.10, 95% CI 0.66 to 1.55, p < 0.001; I2 = 55.6%, p = 0.08; extremely low certainty of evidence). In meta-regression, a significant association was observed between the SMD of uric acid concentrations and body mass index, a risk factor for atherosclerosis and cardiovascular disease (t = 3.35, p = 0.007). Our study has shown a significant increase in the concentrations of the oxidative stress biomarker allantoin in patients with RA. Further research is warranted to investigate the interplay between uric acid, allantoin, redox balance, and cardiovascular disease in this group. (PROSPERO registration number: CRD42023441127).

Hyperuricemia during Pregnancy Leads to a Preeclampsia-Like Phenotype in Mice

Hyperuricemia is a common feature in pregnancies compromised by pre-eclampsia, a pregnancy disease characterized by hypertension and proteinuria. The role of uric acid in the pathogenesis of pre-eclampsia remains largely unclear. The aim of this study was to investigate the effect of elevated uric acid serum levels during pregnancy on maternal blood pressure and neonatal outcome using two different murine knockout models. Non-pregnant liver-specific GLUT9 knockout (LG9KO) mice showed elevated uric acid serum concentrations but no hypertensive blood pressure levels. During pregnancy, however, blood pressure levels of these animals increased in the second and third trimester, and circadian blood pressure dipping was severely altered when compared to non-pregnant LG9KO mice. The impact of hyperuricemia on fetal development was investigated using a systemic GLUT9 knockout (G9KO) mouse model. Fetal hyperuricemia caused distinctive renal tissue injuries and, subsequently an impaired neonatal growth pattern. These findings provide strong evidence that hyperuricemia plays a major role in the pathogenesis of hypertensive pregnancy disorders such as pre-eclampsia. These novel insights may enable the development of preventive and therapeutic strategies for hyperuricemia-related diseases.

Prevalence and influence of hypouricemia on cardiovascular diseases in patients with rheumatoid arthritis

BACKGROUND

Serum uric acid (SUA) acts as an antioxidant and abnormally low SUA may raise the risk of developing atherosclerotic disorders. There is a U-shaped association between SUA with cardiovascular diseases (CVDs) in general population. However, the prevalence of hypouricemia and its influence on CVDs in rheumatoid arthritis (RA) remains unclear.

METHODS

This cross-sectional study collected clinical data from a Chinese RA cohort. Hypouricemia was defined as SUA ≤ 3.0 mg/dL, and hyperuricemia was defined as SUA ≥ 7.0 mg/dL. CVDs were defined as a history of angina pectoris, myocardial infarction, heart failure, stroke and peripheral arterial disease. Restricted cubic spline regression and logistic regression analysis were conducted to evaluate the associations between SUA levels and CVDs.

RESULTS

Among 1130 RA patients recruited, the mean age was 53.2 years and 79.0% were female. The prevalence of hypouricemia and hyperuricemia were 10.6% and 12.0%, respectively. RA patients with hyperuricemia had a higher rate of CVDs than normouricemic patients (27.9% vs. 7.1%, P < 0.05). Surprisingly, RA patients with hypouricemia also had a higher rate of CVDs (20.7% vs. 7.1%, P < 0.05) even without higher traditional cardiovascular risk factors. A U-shaped association between SUA levels and total CVDs was found (P_non-linear < 0.001). Multivariate logistic regression analysis revealed that compared with normouricemia, both hypouricemia [adjusted OR (AOR) = 4.707, 95% CI 2.570-8.620] and hyperuricemia (AOR = 3.707, 95% CI 2.174-6.321) were associated with higher risk of CVDs.

CONCLUSIONS

Hypouricemia may be a potential risk factor of CVDs in RA patients.

Biolabel-led research pattern reveals serum profile in rats after treatment with Herba Lysimachiae: Combined analysis of metabonomics and proteomics

In traditional Chinese medicine, Herba Lysimachiae (HL) is mainly used to treat rheumatic arthralgia. Current pharmacological studies also showed that HL has therapeutic potential for synovial diseases. HL is an oral drug, whose compounds need to enter the blood circulation before reaching the injured tissue, thus potentially causing activity or toxicity to the blood system. In this study, the biolabel-led research pattern was used to analyze the serum profile after HL intervention, based on which the safety and efficacy of HL were explored. Metabonomics and proteomics were combined to analyze the biolabels responsible for the interventions of HL on serum. Bioinformatics databases were used to screen for the material basis that may interfere with biolabels. Omics analysis showed that differentially expressed 19 proteins and 5 metabolites were identified and considered as the potential biolabels, which were involved in 8 biochemical processes (platelet activation and aggregation, blood glucose release, immune and inflammatory regulation, oxidative stress, endoplasmic reticulum stress, tumor progression, blood pressure regulation, and uric acid synthesis). Thirty-one compounds may be the material basis to interfere with eleven biolabels. The present research reveals that the potential activities and toxicities of HL can be explored based on the biolabel-led research pattern.

Glucose Transporter 9 (GLUT9) Plays an Important Role in the Placental Uric Acid Transport System

Background: Hyperuricemia is a common laboratory finding in pregnant women compromised by preeclampsia. A growing body of evidence suggests that uric acid is involved in the pathogenesis of preeclampsia. Glucose transporter 9 (GLUT9) is a high-capacity uric acid transporter. The aim of this study was to investigate the placental uric acid transport system, and to identify the (sub-) cellular localization of GLUT9. Methods: Specific antibodies against GLUT9a and GLUT9b isoforms were raised, and human villous (placental) tissue was immunohistochemically stained. A systemic GLUT9 knockout (G9KO) mouse model was used to assess the placental uric acid transport capacity by measurements of uric acid serum levels in the fetal and maternal circulation. Results: GLUT9a and GLUT9b co-localized with the villous (apical) membrane, but not with the basal membrane, of the syncytiotrophoblast. Fetal and maternal uric acid serum levels were closely correlated. G9KO fetuses showed substantially higher uric acid serum concentrations than their mothers. Conclusions: These findings demonstrate that the placenta efficiently maintains uric acid homeostasis, and that GLUT9 plays a key role in the placental uric acid transport system, at least in this murine model. Further studies investigating the role of the placental uric acid transport system in preeclampsia are eagerly needed.

The Association between Serum Uric Acid Levels and 10-Year Cardiovascular Disease Risk in Non-Alcoholic Fatty Liver Disease Patients

Non-alcoholic fatty liver disease (NAFLD) and serum uric acid (SUA) levels are risk factors for developing cardiovascular disease (CVD). Additionally, previous studies have suggested that high SUA levels increase the risk of having NAFLD. However, no study has investigated the relationship between SUA and CVD risk in NAFLD. This study analyzed the relationship between SUA and CVD in NAFLD. Data for this study used the 2016–2018 Korean National Health and Nutrition Examination Survey, which represents the Korean population. A total of 11,160 NAFLD patients were included. Participants with hepatic steatosis index ≥ 30 were considered to have NAFLD. Ten-year CVD risk was estimated using an integer-based Framingham risk score. Estimated 10-year CVD risk ≥ 20% was considered high risk. Multiple logistic regression was conducted to calculate the odds ratios (ORs) associated with SUA level and CVD risk. High CVD risk OR increases by 1.31 (95% CI 1.26–1.37) times per 1 mg/dL of SUA. After adjustment, SUA still had an increased risk (OR 1.44; 95% CI 1.38–1.51) of CVD. Compared with the lowest SUA quartile group, the highest quartile group showed a significantly higher risk of having CVD before (OR 2.76; 95% CI 2.34–3.25) and after (OR 4.01; 95% CI 3.37–4.78) adjustment. SUA is independently associated with CVS risk in NAFLD.

Hyperuricemia and Cardiovascular Risk

As the prevalence of hyperuricemia (elevated uric acid levels in the blood) increases, the relationship between serum uric acid levels and cardiovascular risk has garnered increased interest. Several studies have highlighted that elevated uric acid levels are likely tied to increased cardiovascular disease risk. Specifically, the presence of hyperuricemia is well-established to contribute to the onset of gout (an inflammatory condition characterized by painful/swollen joints). Several studies have shown that the risk of developing gout is strongly associated with the degree of hyperuricemia. In this review, we will provide insight into the association between gout and cardiovascular disease risk. It is also important to gain insight into the pathophysiology of gout to understand the contributions to cardiovascular disease risk as well as improve diagnosis and target treatment more effectively. An interdisciplinary approach for gout management and areas for further investigation will be discussed in this review.

Cardiovascular Risk in Rheumatoid Arthritis: Literature Review

Rheumatoid arthritis (RA) is the most common inflammatory arthritis disease with a worldwide prevalence of 1-3%. RA patients are at higher risk of atherosclerosis than their matched age-sex controls. Cardiovascular diseases (CVDs) account for a 50% risk of increased mortality and morbidity in RA. The pattern of CVD in RA patients differs from that in the general population; RA patients are more likely to have silent ischemic heart disease, sudden death, heart failure, and die early. RA patients tend to have a 5-10 years reduction in their life span than their matched healthy population. Traditional (classical) CV risk factors work separately or synergistically with the underlying inflammation to increase CVD risk in RA. Moreover, inflammation is defined as an independent CVD risk factor. This literature review aims to discuss the traditional CVD risk factors and their association with inflammation in RA.

Atherogenic Index of Plasma in Women with Rheumatoid Arthritis and Systemic Lupus Erythematosus: A 10-Year Potential Predictor of Cardiovascular Disease

BACKGROUND

Women with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are at high risk of cardiovascular diseases (CVD). The atherogenic index of plasma (AIP) is a new marker for the assessment of CVD.

OBJECTIVE

This study aimed to determine the predictive value of AIP with long-term CVD risk among women with RA and SLE.

METHODS

This is a cross-sectional study of 99 RA and 59 SLE women. Demographic, clinical, and biochemical data were obtained, and disease activities were calculated. For each patient, the longterm risk of CVD was calculated using the Framingham risk score (FRS); AIP was derived according to the logarithmic (triglycerides/high-density lipoproteins cholesterol).

RESULTS

The mean age of the RA and SLE patients was 47.97 ± 8.78 and 36.75 ± 9.09 years, respectively. The median (interquartile range) of AIP values in RA and SLE patients were 0.34 (-0.15, 1.02) and 0.33 (-0.53, 0.96), respectively, while FRS values of RA patients and SLE patients were 6.38 ± 5.58 and 4.86 ± 4.5, respectively (p >0.05). There was a moderate correlation between AIP and FRS in RA and SLE patients (r=0.42, p=0.002 and r=0.33, p=0.007, respectively). According to the multivariate regression analyses, we found that AIP value is an independent factor for FRS in RA (β: 4.13, 95% confidence interval; 1.71, 6.18; p=0.008) and in SLE patients (β: 6.19, 95% confidence interval; 2.58, 9.81; p<0.001).

CONCLUSIONS

We reported that AIP can be used as an independent indicator for long-term CVD risk in RA and SLE patients.

Serum uric acid increases in patients with systemic autoimmune rheumatic diseases after 3 months of treatment with TNF inhibitors

In patients with gout, the serum uric acid (SUA) is usually lower during acute gouty attacks than during intercritical periods. It has been suggested that systemic inflammatory response can cause this phenomenon. The objective is to determine whether therapy with TNF inhibitors (TNFis) affects SUA levels in patients with systemic autoimmune rheumatic diseases (SARDs) and whether SUA changes correlate with pro-inflammatory cytokines or with the oxidative stress marker allantoin. In this study, SUA, CRP, creatinine, MCP-1, IFN-α2, IFN-γ, Il-1β, IL-6, IL-8, IL-10, IL-12, IL-17a, IL-18, IL-23, IL-33, TNF-α, and allantoin levels were measured prior to and after 3 months of TNFis treatment in patients with SARDs. The values obtained in the biochemical assays were then tested for associations with the patients' demographic and disease-related data. A total of 128 patients (rheumatoid arthritis, n = 44; ankylosing spondylitis, n = 45; psoriatic arthritis, n = 23; and adults with juvenile idiopathic arthritis, n = 16) participated in this study. Among the entire patient population, SUA levels significantly increased 3 months after starting treatment with TNFis (279.5 [84.0] vs. 299.0 [102.0] μmol/l, p < 0.0001), while the levels of CRP, IL-6, IL-8, and MCP-1 significantly decreased. Male sex was the most powerful baseline predictor of ΔSUA in univariate and multivariate models. None of the measured laboratory-based parameters had statistically significant effects on the magnitude of ΔSUA. 3 months of anti-TNF therapy increased the levels of SUA in patients with SARDs, but neither the measured pro-inflammatory cytokines nor the oxidation to allantoin appeared responsible for this effect.

Biomarkers of subclinical atherosclerosis in patients with psoriatic arthritis

Background: Psoriatic arthritis (PsA) is a chronic immune-mediated disease. It is associated with an increase in cardiovascular risk factors (obesity, hypertension, diabetes, and dyslipidemia), giving a higher risk of major adverse cardiovascular events. Patients with PsA have an increased incidence of subclinical atherosclerosis and endothelial dysfunction. The aim of this study is to perform a review of the biomarkers of subclinical atherosclerosis in patients with PsA.

Methods: A search was performed in the electronic databases (PubMed, Web of Science, Scopus, and Embase) up until July 2017. Studies were considered if they included data on biomarkers of subclinical atherosclerosis in PsA, and each article was then reviewed for quality and clinical relevance. After completing the literature search, all screened literature was summarized and discussed in our study group (CaRRDs study group).

Results: The initial search produced 532 abstracts, which were limited to 258 potentially relevant articles by preliminary review of the titles and by excluding review articles and case reports (n=274). A further 102 articles were deemed ineligible after examining the abstracts. Full texts of the remaining 156 articles were retrieved. Most articles were excluded because they were not relevant to the biomarkers of subclinical atherosclerosis in psoriasis and/or PsA. In the end, 54 articles were deemed eligible for this review.

Conclusion: Patients with PsA showed more severe atherosclerotic disease compared with patients with only psoriasis. This may have been due to the higher systemic inflammatory burden from the combination of both diseases. In patients with PsA some molecules may be considered as markers of atherosclerotic disease, and their detection may be a prognostic marker, in addition to imaging procedures, for the development of atherosclerotic disease, and could be suitable for the management of patients with PsA.

Superhydrophobic silver film as a SERS substrate for the detection of uric acid and creatinine

Superhydrophobic silver films were fabricated by silver-mirror reaction and surface functionalization with thiol. The thiol-functionalization significantly improved the hydrophobic property of the Ag films (AFS), and their contact angle values slightly increased with the extension of a thiol alkyl chain, reaching about 160°. The surface-enhanced Raman scattering (SERS) detection capacity of these films were investigated, and AFS-Dodec showed the best substrate for R6G molecule detection with the concentration limit of 10^-11 M. AFS functionalized with dodecanethiol (AFS-Dodec) was applied for the SERS detection of uric acid and creatinine, it exhibited good linear dependence relationship between the Raman intensity and analyte concentration in the concentration range of 5~1000 μM.

Impact of obesity on autoimmune arthritis and its cardiovascular complications

Obesity can instigate and sustain a systemic low-grade inflammatory environment that can amplify autoimmune disorders and their associated comorbidities. Metabolic changes and inflammatory factors produced by the adipose tissue have been reported to aggravate autoimmunity and predispose the patient to cardiovascular disease (CVD) and metabolic comorbidities. Rheumatoid arthritis (RA) and psoriatic arthritis (PsA) are autoimmune arthritic diseases, often linked with altered body mass index (BMI). Severe joint inflammation and bone destruction have a debilitating impact on the patient's life; there is also a staggering risk of cardiovascular morbidity and mortality. Furthermore, these patients are at risk of developing metabolic symptoms, including insulin resistance resulting in type 2 diabetes mellitus (T2DM). In addition, arthritis severity, progression and response to therapy can be markedly affected by the patient's BMI. Hence, a complex integrative pathogenesis interconnects autoimmunity with metabolic and cardiovascular disorders. This review aims to shed light on the network that connects obesity with RA, PsA, systemic lupus erythematosus and Sjӧgren's syndrome. We have focused on clarifying the mechanism by which obesity affects different cell types, inflammatory factors and traditional therapies in these autoimmune disorders. We conclude that to further optimize arthritis therapy and to prevent CVD, it is imperative to uncover the intricate relation between obesity and arthritis pathology.

Metabolic syndrome and the decreased levels of uric acid by leflunomide favor redox imbalance in patients with rheumatoid arthritis

Oxidative stress plays a role in the pathophysiology of rheumatoid arthritis (RA). The aim of the present study was to verify the influence of metabolic syndrome (MetS) and disease-modifying antirheumatic drugs on nitrosative and oxidative biomarkers in patients with RA. A total of 177 patients with RA and 150 healthy volunteers participated in this study, which measured lipid hydroperoxides, advanced oxidation protein products (AOPP), nitric oxide metabolites (NOx), carbonyl protein, total radical-trapping antioxidant parameter (TRAP), uric acid (UA), and C-reactive protein (CRP). NOx and the NOx/TRAP ratio were significantly increased in RA, while no significant differences in lipid hydroperoxides, AOPP, UA, and TRAP levels were found between both groups. Treatment with leflunomide was associated with increased levels of carbonyl protein, and lowered levels in TRAP and UA, while the NOx/TRAP ratio further increased. NOx and the NOx/TRAP ratio were significantly higher in women than in men, while TRAP and UA were significantly lower in women. MetS was accompanied by increased AOPP and UA levels. RA was best predicted by increased NOx/TRAP ratio, CRP, and BMI. In conclusion, our data demonstrated that NOx and NOx/TRAP are strongly associated with RA physiopathology. Our findings suggest that inhibition of iNOS may become an interesting therapeutic approach for the treatment of RA. In addition, the presence of MetS and a decrease in levels of UA by leflunomide favor redox imbalance in RA patients. More studies are needed to evaluate the impact of antioxidant capacity reduction on RA progression.

Uric acid is independent cardiovascular risk factor, as manifested by increased carotid intima-media thickness in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is associated with increased cardiovascular disease (CVD) mortality and morbidity, due to the combined effects of traditional and non-traditional cardiovascular risk factors (CV). A serum uric acid (SUA) level has been suggested as one of the non-traditional cardiovascular risk factors. Cardiovascular risk can be assessed by looking at the subclinical atherosclerosis such as ultrasound (US)-measured carotid intima-media thickness (cIMT). This paper aimed to determine the role of SUA as a cardiovascular risk factor, along with the traditional cardiovascular risk factors and inflammation, among RA population. RA patients with no clinically evident CV or renal disease were studied. cIMT US, SUA, traditional cardiovascular, and inflammatory markers were obtained and correlated with cIMT. Among 53 RA patients (5 males, 48 females, mean age 48 ± 14 years), univariate linear-regression showed a positive linear relationship between cIMT and age (p < 0.001), age at RA symptoms onset and diagnosis (p = 0.010 and 0.003, respectively), number of cigarettes/day (p < 0.001), systolic and diastolic blood pressure (p = 0.005 and 0.030, respectively), and SUA (p = 0.007). Rheumatoid factor positivity and level were associated with thicker cIMT (p = 0.042 and 0.039, respectively). SUA maintained a significant correlation with cIMT in the multivariate analysis together with age, low-density lipoprotein, and triglyceride level. The model explained 55% (R2 55) of the causes of thick cIMT among RA population. SUA seems to be a cardiovascular risk factor in RA, as manifested by increase in the cIMT.

URIC ACID AND TISSUE REPAIR

Uric acid, a metabolic product of purines, may exert a role in tissue healing. In this review we will explore its role as an alarm initiating the inflammatory process that is necessary for tissue repair, as a scavenger of oxygen free radicals, as a mobilizer of progenitor endothelial cells and as supporter of adaptive immune system.

Patients with Rheumatoid Arthritis Show Altered Lipoprotein Profiles with Dysfunctional High-Density Lipoproteins that Can Exacerbate Inflammatory and Atherogenic Process

Objective

In order to identify putative biomarkers in lipoprotein, we compared lipid and lipoprotein properties between rheumatoid arthritis (RA) patients and control with similar age.

Methods

We analyzed four classes of lipoproteins (VLDL, LDL, HDL₂, HDL₃) from both male (n = 8, 69±4 year-old) and female (n = 25, 53±7 year-old) rheumatoid arthritis (RA) patients as well as controls with similar age (n = 13).

Results

Although RA group showed normal levels of total cholesterol (TC), low-density lipoprotein (LDL)-cholesterol, and glucose, however, the RA group showed significantly reduced high-density lipoprotein (HDL)-C level and ratio of HDL-C/TC. The RA group showed significantly elevated levels of blood triglyceride (TG), uric acid, and cholesteryl ester transfer protein (CETP) activity. The RA group also showed elevated levels of advanced glycated end (AGE) products in all lipoproteins and severe aggregation of apoA-I in HDL. As CETP activity and TG contents were 2-fold increased in HDL from RA group, paraoxonase activity was reduced upto 20%. Electron microscopy revealed that RA group showed much less HDL₂ particle number than control. LDL from the RA group was severely oxidized and glycated with greater fragmentation of apo-B, especially in female group, it was more atherogenic via phagocytosis.

Conclusion

Lipoproteins from the RA patients showed severely altered structure with impaired functionality, which is very similar to that observed in coronary heart patients. These dysfunctional properties in lipoproteins from the RA patients might be associated with high incidence of cardiovascular events in RA patients.

Assessment of genetic polymorphisms associated with hyperuricemia or gout in the Hmong

AIM

Hyperuricemia commonly causes gout. Minnesota Hmong exhibit a two- to fivefold higher prevalence of gout versus non-Hmong. To elucidate a possible genomic contribution to this disparity, prevalence of risk alleles for hyperuricemia in Hmong was compared with European (CEU) and Han-Chinese (CHB).

METHODS

In total, 235 Hmong were genotyped for eight SNPs representing five candidate genes (SLC22A12, SLC2A9, ABCG2, SLC17A1 and PDZK1).

RESULTS

The frequency of seven out of eight risk alleles in the Hmong was significantly different than CEU; six higher and one with lower prevalence. The frequency of three out of eight risk alleles in the Hmong was significantly different than CHB; two higher and one with lower prevalence.

CONCLUSION

Hyperuricemia risk alleles are more prevalent in the Hmong than CEU and HB.

Cardiovascular comorbidity in rheumatic diseases. Nat Rev Rheumatol. 2015;11:693-704. [PMID: 26282082 DOI: 10.1038/nrrheum.2015.112]

Patients with rheumatoid arthritis (RA) and other inflammatory joint diseases (IJDs) have an increased risk of premature death compared with the general population, mainly because of the risk of cardiovascular disease, which is similar in patients with RA and in those with diabetes mellitus. Pathogenic mechanisms and clinical expression of cardiovascular comorbidities vary greatly between different rheumatic diseases, but atherosclerosis seems to be associated with all IJDs. Traditional risk factors such as age, gender, dyslipidaemia, hypertension, smoking, obesity and diabetes mellitus, together with inflammation, are the main contributors to the increased cardiovascular risk in patients with IJDs. Although cardiovascular risk assessment should be part of routine care in such patients, no disease-specific models are currently available for this purpose. The main pillars of cardiovascular risk reduction are pharmacological and nonpharmacological management of cardiovascular risk factors, as well as tight control of disease activity.

Prevention of cardiovascular disease in rheumatoid arthritis

The increased risk of cardiovascular disease (CVD) in rheumatoid arthritis (RA) has been recognized for many years. However, although the characteristics of CVD and its burden resemble those in diabetes, the focus on cardiovascular (CV) prevention in RA has lagged behind, both in the clinical and research settings. Similar to diabetes, the clinical picture of CVD in RA may be atypical, even asymptomatic. Therefore, a proactive screening for subclinical CVD in RA is warranted. Because of the lack of clinical trials, the ideal CVD prevention (CVP) in RA has not yet been defined. In this article, we focus on challenges and controversies in the CVP in RA (such as thresholds for statin therapy), and propose recommendations based on the current evidence. Due to the significant contribution of non-traditional, RA-related CV risk factors, the CV risk calculators developed for the general population underestimate the true risk in RA. Thus, there is an enormous need to develop adequate CV risk stratification tools and to identify the optimal CVP strategies in RA. While awaiting results from randomized controlled trials in RA, clinicians are largely dependent on the use of common sense, and extrapolation of data from studies on other patient populations. The CVP in RA should be based on an individualized evaluation of a broad spectrum of risk factors, and include: 1) reduction of inflammation, preferably with drugs decreasing CV risk, 2) management of factors associated with increased CV risk (e.g., smoking, hypertension, hyperglycemia, dyslipidemia, kidney disease, depression, periodontitis, hypothyroidism, vitamin D deficiency and sleep apnea), and promotion of healthy life style (smoking cessation, healthy diet, adjusted physical activity, stress management, weight control), 3) aspirin and influenza and pneumococcus vaccines according to current guidelines, and 4) limiting use of drugs that increase CV risk. Rheumatologists should take responsibility for the education of health care providers and RA patients regarding CVP in RA. It is immensely important to incorporate CV outcomes in testing of anti-rheumatic drugs.

Evaluation of serum magnesium, lipid profile and various biochemical parameters as risk factors of cardiovascular diseases in patients with rheumatoid arthritis

BACKGROUND

Rheumatoid arthritis (RA) is chronic inflammatory disease, associated with increased risk of cardiovascular diseases (CVD) than the general population. Chronic inflammatory conditions are likely to alter magnesium level and various biochemical parameters.

OBJECTIVES

To study the probable changes in serum magnesium, lipid profile and various biochemical parameters and to assess risk factors of CVD in newly diagnosed RA patients compared to controls.

MATERIALS AND METHODS

We studied 50 newly diagnosed RA adult patients and 50 healthy individuals as controls. Serum magnesium, calcium, lipid profile, uric acid and other biochemical parameters were measured in study subjects. Results were expressed as Mean ± SD and compared between RA subjects and controls by Independent sample t-test and Pearson correlation.

RESULTS

We found decreased serum magnesium and calcium in RA subjects compared to the controls (p < 0.001). RA subjects had atherogenic lipid profile characterized by elevated total cholesterol (p = 0.054), LDL cholesterol (p = 0.008) and decreased HDL cholesterol (p <0.001). Serum uric acid was higher in RA cases compared to controls (p = 0.025). Serum magnesium was negatively correlated with total cholesterol, LDL cholesterol and positively correlated with HDL cholesterol in RA cases.

CONCLUSION

Decreased magnesium level, dyslipidemia and increased uric acid observed in our study together may be more potent risk factors for CVD in newly diagnosed RA subjects. We recommend that serum magnesium should be investigated as a part of cardiovascular risk management in RA. We suggest that decreased serum magnesium and increased serum uric acid may be considered as nontraditional risk factors of CVD in RA. Further prospective studies are needed to confirm the impact of inflammation on various biochemical parameters and cardiovascular outcomes in patients with RA.

Association between corrected QT interval and inflammatory cytokines in rheumatoid arthritis

OBJECTIVE

Corrected QT (QTc) interval predicts all-cause and cardiovascular mortality and may contribute to the increased mortality risk in rheumatoid arthritis (RA). Animal experiments have shown that proinflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin 1 (IL-1)] can prolong cardiomyocyte action potential. We sought to determine whether elevations in circulating inflammatory cytokines were independently associated with QTc prolongation in patients with RA.

METHODS

One hundred twelve patients [median age 62 (interquartile range 17) yrs; 80 women (71%)] from a well-characterized RA cohort underwent baseline 12-lead electrocardiograms for QT interval measurement and contemporary blood sampling to assess concentrations of inflammatory markers including C-reactive protein (CRP), TNF-α, and interleukins (IL-1α, IL-1β, IL-6, IL-10). QTc was calculated using the Bazett (QTBAZ = QT ÷ √RR) and Framingham Heart Study (QTFHS = QT + 0.154 × [1 - RR]) heart rate correction formulas.

RESULTS

Inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-10) were positively correlated with QTBAZ (Spearman rank correlation coefficient rho = 0.199, 0.210, 0.222, 0.333; all p < 0.05). In multivariable regression analysis, these associations were all confounded by age except IL-10, where higher tertile groups were independently and positively associated with QTBAZ (β = 0.202, p = 0.023) and QTFHS (β = 0.223, p = 0.009) when compared to the lower tertile. CRP (per unit increase) was independently associated with QTBAZ (β = 0.278, p = 0.001), but not QTFHS.

CONCLUSION

To our knowledge, ours is the first study demonstrating a contemporary link between inflammatory cytokines and QT interval in humans. Our results suggest that a lower inflammatory burden may protect against QTc prolongation in patients with RA. However, further studies are required to confirm the effects of pro- and antiinflammatory cytokines on QTc interval.

Hyperuricemia and incident cardiovascular disease and noncardiac vascular events in patients with rheumatoid arthritis

Objective. To evaluate whether hyperuricemia is a risk factor for cardiovascular disease (CVD) in patients with rheumatoid arthritis (RA). Methods. A population-based inception cohort of patients diagnosed between 1980 and 2007 with adult-onset RA was assembled. A comparison cohort of age- and sex-matched subjects without RA (non-RA) was also assembled. All clinically obtained uric acid values were collected. CVD and noncardiac vascular events were recorded for each patient. Cox proportional hazards models were used to assess the impact of hyperuricemia on development of CVD, mortality, and noncardiac vascular disease. Results. In patients without RA, hyperuricemia was associated with heart failure (HR: 1.95; 95% CI: 1.13–3.39) and CVD (HR: 1.59; 95% CI: 0.99–2.55). In patients with RA, hyperuricemia was not significantly associated with CVD but was significantly associated with peripheral arterial events (HR: 2.52; 95% CI: 1.17–5.42). Hyperuricemia appeared to be more strongly associated with mortality among RA patients (HR: 1.96; 95% CI: 1.45–2.65) than among the non-RA subjects (HR: 1.57; 95% CI: 1.09–2.24). Conclusion. In patients with RA, hyperuricemia was a significant predictor of peripheral arterial events and mortality but not of CVD.

Hyperuricaemia: a marker of increased cardiovascular risk in rheumatic patients: analysis of the ACT-CVD cohort

BACKGROUND

Gout and hyperuricaemia may be associated with increased cardiovascular risk, but analyses in different populations show conflicting results. This study investigates the impact of serum uric acid, inflammation and traditional CV risk parameters on CV event risk in patients with gouty arthritis and patients with non-gouty rheumatic disease.

METHODS

cross-sectional and prospective multivariate analysis of the relation between tertiles of serum uric acid and individual traditional CV risk factors in a cohort of gouty arthritis (GA, n=172), rheumatoid arthritis (RA, n=480) and osteoarthritis (OA, n=206) patients.

MAIN OUTCOME MEASURES

systolic blood pressure, TC/HDL ratio, GlyHb, BMI and first CV events.

RESULTS

Individual CV risk factors were significantly less favourable in GA (systolic blood pressure, TC/HDL ratio, BMI, p<0.05). In RA and OA, but not in GA, individual cardiometabolic parameters correlated with serum uric acid values (OA: RA: systolic blood pressure, TC/HDL ratio, BMI; systolic blood pressure, TC/HDL ratio, GlyHb, BMI; p<0.05). In non-GA individuals the highest tertile of serum uric acid (>0.34 mmol/L) and NT proBNP level were independent predictors of first CV events, against age and GlyHb level in GA (p<0.05). The hazard of first CV events was equally significantly increased in GA patients (HR 3.169, 95% CI 1.287-7.806) and non-GA individuals with a serum uric acid ≥ 0.34 mmol/L (HR 3.721, 95% CI 1.603-8.634) compared to non-GA individuals with a serum uric acid < 0.27.

CONCLUSIONS

GA is associated with a 3.1-fold hazard of first CV events. In non-GA rheumatic patients increasing serum uric acid is associated with increased CV risk, whereas CV risk in GA is independent of serum uric acid values. The presence of GA or a baseline serum uric acid in the upper range are possibly stronger predictors of first CV events than some traditional CV risk factors or parameters of inflammation.

Serum uric acid: relationships with biomarkers in adolescents and changes over 1 year

OBJECTIVES

To (1) elucidate the range of serum uric acid (UA) levels in adolescent sample; (2) examine the relationships of serum UA and 1-year change with gender, anthropometric and cardiometabolic factors.

MATERIALS AND METHODS

Measurements (anthropometrics, fasting venipuncture and blood pressure) were performed at the beginning of the seventh and eighth grades. Descriptive data, differences according to weight, correlations and changes over time were examined.

FINDINGS

In 77 adolescents, BMI and serum UA had relationships with several cardiometabolic measures. Males had higher serum UA at follow-up compared to baseline; female change was minimal. Time-by-gender interaction was significant, as were the main effects of gender and BMI classification. Males had lower HDL-C at follow-up than at baseline; females had higher HDL-C at follow-up.

CONCLUSIONS

Serum UA has importance in cardiometabolic examination of youth risk factors. It should be examined in youth with elevated BMI and/or hypertension. Early adolescence is the period when gender-related metabolic changes occur.

Review of hyperuricemia as new marker for metabolic syndrome

Hyperuricemia has long been established as the major etiologic factor in gout. In recent years, a large body of evidence has accumulated that suggests that hyperuricemia may play a role in the development and pathogenesis of a number of metabolic, hemodynamic, and systemic pathologic diseases, including metabolic syndrome, hypertension, stroke, and atherosclerosis. A number of epidemiologic studies have linked hyperuricemia with each of these disorders. In some studies, therapies that lower uric acid may prevent or improve certain components of the metabolic syndrome. There is an association between uric acid and the development of systemic lupus erythematosus; the connection between other rheumatic diseases such as rheumatoid arthritis and osteoarthritis is less clear. The mechanism for the role of uric acid in disorders other than gout is not well established but recent investigations point towards systemic inflammation induced by urate, as the major pathophysiological event common to systemic diseases, including atherosclerosis.

Prolonged QTc interval predicts all-cause mortality in patients with rheumatoid arthritis: an association driven by high inflammatory burden

OBJECTIVE

RA associates with an increased rate of sudden cardiac death (SCD). A prolonged QTc interval has been associated with arrhythmogenic and SCD in patients with long QT syndrome. Despite the previously reported contemporary association of CRP with SCD, thus far no studies have examined the association of QTc with mortality in RA, a condition characterized by high inflammatory burden. The aim of this study was to examine the role of electrocardiography (QT corrected interval) in predicting all-cause mortality in patients with RA who have an increased rate of SCD and a high inflammatory burden.

METHODS

Three hundred and fifty-seven RA patients with detailed baseline clinical characterization and 12-lead ECGs were followed up for a mean of 73.0 (S.D. 18.3) months. Linear and Cox regression analyses were used to identify variables that associate with QTc and examine its association with all-cause mortality.

RESULTS

The patients' mean age was 60.6 (S.D. 12.0) years, 267 (74.8%) were females and 54 (15.1%) died during the follow-up period. Age (β = 0.231, P < 0.001), gender (β = 0.137, P = 0.008) and CRP (β = 0.144, P = 0.006) associated independently with QTc in RA patients. The crude hazard ratio (HR) for total mortality per 50-ms increase in QTc was 2.17 (95% CI 1.21, 3.90). This association remained significant [HR = 2.18 (95% CI 1.09, 4.35)] after adjustment for identified confounders (cardiovascular and RA specific), but was lost [HR = 1.73 (95% CI 0.83, 3.62)] when CRP was included in the model.

CONCLUSION

A 50-ms increase in QTc interval associates with a doubling of the hazard for all-cause mortality in patients with RA. The observed contemporary association of QTc with CRP levels indicates a potentially hazardous interplay between inflammation and arrhythmogenesis. Future studies are needed to confirm the above findings and explore underlying mechanisms.

Increased arterial stiffness is independently associated with metabolic syndrome and damage index in systemic lupus erythematosus patients

OBJECTIVES

We evaluated whether traditional or non-traditional cardiovascular (CV) risk factors and systemic lupus erythematosus (SLE)-related risk factors were associated with pathological arterial stiffness measured by pulse wave velocity (PWV) adjusted for patients' age and blood pressure.

METHOD

CV risk factors were measured in the 46 SLE female patients studied. Activity and organ damage were assessed by the SLE Disease Activity Index (SLEDAI) and the Systemic Lupus International Collaborative Clinics/American College of Rheumatology (SLICC/ACR) Damage Index, respectively. Other lupus-related parameters and information concerning treatment were recorded. Subclinical atherosclerosis was assessed by PWV calculated from pulse wave recording by Doppler, a non-invasive method to measure arterial stiffness. Multivariate logistic regression analysis was used to identify independent determinants of increased PWV.

RESULTS

PWV was categorized as normal or pathological arterial stiffness following the reference values adjusted by age and blood pressure recently published by the European Society of Cardiology. Pathological PWV was associated with CV risk factors including homocysteine (p = 0.01), high-sensitivity C-reactive protein (hs-CRP; p = 0.03), uric acid (p = 0.01), and metabolic syndrome (p = 0.007). With regard to SLE-specific risk factors, a significant association was found between PWV and SLICC/ACR score (p = 0.006). Multivariate analysis showed that increased PWV was independently associated with metabolic syndrome [odds ratio (OR) 6.6, 95% confidence interval (CI) 1.2-38, p = 0.03] and SLICC/ACR score (OR 1.5, 95% CI 1-2.32, p = 0.05).

CONCLUSIONS

We have found a close link between metabolic syndrome and SLICC/ACR score with increased aortic stiffness. These variables might be an indicator of subclinical atherosclerosis in SLE women without clinical evidence of atherosclerotic cardiovascular disease (CVD).

A potential role for plasma uric acid in the endothelial pathology of Plasmodium falciparum malaria

Background

Inflammatory cytokinemia and systemic activation of the microvascular endothelium are central to the pathogenesis of Plasmodium falciparum malaria. Recently, ‘parasite-derived’ uric acid (UA) was shown to activate human immune cells in vitro, and plasma UA levels were associated with inflammatory cytokine levels and disease severity in Malian children with malaria. Since UA is associated with endothelial inflammation in non-malaria diseases, we hypothesized that elevated UA levels contribute to the endothelial pathology of P. falciparum malaria.

Methodology/Principal Findings

We measured levels of UA and soluble forms of intercellular adhesion molecule-1 (sICAM-1), vascular cell adhesion molecule-1 (sVCAM-1), E-selectin (sE-Selectin), thrombomodulin (sTM), tissue factor (sTF) and vascular endothelial growth factor (VEGF) in the plasma of Malian children aged 0.5–17 years with uncomplicated malaria (UM, n = 487) and non-cerebral severe malaria (NCSM, n = 68). In 69 of these children, we measured these same factors once when they experienced a malaria episode and twice when they were healthy (i.e., before and after the malaria transmission season). We found that levels of UA, sICAM-1, sVCAM-1, sE-Selectin and sTM increase during a malaria episode and return to basal levels at the end of the transmission season (p<0.0001). Plasma levels of UA and these four endothelial biomarkers correlate with parasite density and disease severity. In children with UM, UA levels correlate with parasite density (r = 0.092, p = 0.043), sICAM-1 (r  = 0.255, p<0.0001) and sTM (r = 0.175, p = 0.0001) levels. After adjusting for parasite density, UA levels predict sTM levels.

Conclusions/Significance

Elevated UA levels may contribute to malaria pathogenesis by damaging endothelium and promoting a procoagulant state. The correlation between UA levels and parasite densities suggests that parasitized erythrocytes are one possible source of excess UA. UA-induced shedding of endothelial TM may represent a novel mechanism of malaria pathogenesis, in which activated thrombin induces fibrin deposition and platelet aggregation in microvessels. This protocol is registered at clinicaltrials.gov (NCT00669084).

Human SLC2A9a and SLC2A9b isoforms mediate electrogenic transport of urate with different characteristics in the presence of hexoses

Human SLC2A9 (GLUT9) is a novel high-capacity urate transporter belonging to the facilitated glucose transporter family. In the present study, heterologous expression in Xenopus oocytes has allowed us to undertake an in-depth radiotracer flux and electrophysiological study of urate transport mediated by both isoforms of SLC2A9 (a and b). Addition of urate to SLC2A9-producing oocytes generated outward currents, indicating electrogenic transport. Urate transport by SLC2A9 was voltage dependent and independent of the Na(+) transmembrane gradient. Urate-induced outward currents were affected by the extracellular concentration of Cl(-), but there was no evidence for exchange of the two anions. [(14)C]urate flux studies under non-voltage-clamped conditions demonstrated symmetry of influx and efflux, suggesting that SLC2A9 functions in urate efflux driven primarily by the electrochemical gradient of the cell. Urate uptake in the presence of intracellular hexoses showed marked differences between the two isoforms, suggesting functional differences between the two splice variants. Finally, the permeant selectivity of SLC2A9 was examined by testing the ability to transport a panel of radiolabeled purine and pyrimidine nucleobases. SLC2A9 mediated the uptake of adenine in addition to urate, but did not function as a generalized nucleobase transporter. The differential expression pattern of the two isoforms of SLC2A9 in the human kidney's proximal convoluted tubule and its electrogenic transport of urate suggest that these transporters play key roles in the regulation of plasma urate levels and are therefore potentially important participants in hyperuricemia and hypouricemia.

Effect of xinfeng capsule on the cardiac function in patients with rheumatoid arthritis

OBJECTIVE

To study the changes in cardiac function of rheumatoid arthritis (RA) patients and: to observe the effect of xinfeng capsule ( XFC) on them.

METHODS

Sixty-eight RA patients were: randomly assigned to two groups by a lottery: 38 patients in the treatment group treated orally with XFC, 3 capsules, thrice a day, and 30 in the control group treated with fengshi gutong capsule (FSGTC), 4 capsules, twice a day, 30 days as one course of treatment, and two courses were given for both groups. A normal control (NC) group including 20 healthy subjects was set up. The clinical efficacy was compared between the two treated groups. The changes in cardiac function, including early diastolic peak flow velocity (E), late diastolic peak flow velocity (A), left ventricular fraction shortening (FS), and E/A, as well as uric acid (UA), erythrocyte sedimentation rate (ESR), α-acid glycoprotein (α-AGP), and hypersensitive C-reaction protein (hs-CRP), were observed. The regulation T cell was determined with flow cytometry.

RESULTS

(1) The total effective rate in the treatment group and the control group was 92.1%: (35/38) and 70.0% (21/30), respectively. Significant difference was shown between them (P<0.05). (2) <Compared with those of the NC group, E peak, E/A ratio, and FS of RA patients were lower (P<0.01), while <A peak was higher (P<0.01). Moreover, A peak of the treatment group after treatment was significantly lower <(P<0.05) and E/A ratio was significantly higher (<P<0.05) as compared with those of the control group. (3) The <improvement in the treatment group in reducing UA and hs-CRP was superior to those of the control group (P<0.05). In addition, the improvement in α-AGP, CD4 <CD4(+)CD25 CD25(+) Treg, and CD4 CD4(+)CD25 CD25(+)CD127 CD127(-)Treg of the treatment group was obvious as compared with the control group, although the difference was not statistically significant.

CONCLUSIONS

The descendent of cardiac function exists in RA patients. XFC could improve cardiac: function of RA patients, which is superior to FSGTC. Its mechanism may be related to its effect on raising CD4 CD4(+)CD25 CD25(+)Treg and CD4 CD4(+)CD25 CD25(+)CD127(-) Treg cells, decreasing UA, α-AGP, and hs-CRP levels, reducing immune inflammation, adjusting the overall balance of immune response, and thus improving the cardiac function of RA patients.

Rheumatoid arthritis: is it a coronary heart disease equivalent?

PURPOSE OF REVIEW

This review examines current evidence to address the question whether rheumatoid arthritis (RA) is a coronary heart disease equivalent, similar to type 2 diabetes mellitus (DM2).

RECENT FINDINGS

Cross-sectional and longitudinal epidemiological studies show a two-fold higher risk of cardiovascular disease (CVD) in patients with RA, and the magnitude of this increased risk is comparable to the risk associated with DM2. However, the mechanisms responsible for this appear to be different in the two conditions, with RA-related CVD being attributed to 'high-grade' systemic inflammation as well as classical CVD risk factors. Several classical risk factors are affected by RA or its medications, and there are some paradoxical associations between obesity or lipid abnormalities and CVD death in RA.

SUMMARY

Management of RA-related CVD is likely to require both aggressive control of inflammation and systematic screening and management of classical CVD risk factors. It remains unknown whether primary prevention strategies applied successfully in DM2 would be equally easy to implement and demonstrate similar benefits in people with RA.

Serum uric acid and self-reported rheumatoid arthritis in a multiethnic adult female population

OBJECTIVE

Studies suggest that serum uric acid (SUA) is significantly associated with cardiovascular disease (CVD) mortality among women and blacks. CVD rates are higher among patients with rheumatoid arthritis (RA) than the normal population. The objective of this study was to determine if there was an association between SUA levels and self-reported RA in a multiethnic female population in the United States.

METHODS

This cross-sectional study was conducted using data for 7374 women above 20 years of age in the Third National Health and Nutrition Examination Survey. Multiple and logistic regression methods were used to determine an association between SUA levels and self-reported RA.

RESULTS

Women self-reporting RA had significantly higher SUA levels (p < 0.0001) compared to women not self-reporting RA, also when adjusted for age and race (p < 0.0001). In a regression analysis, significant predictors of SUA levels were: self-reporting RA, race/ethnicity, being married, smoking, use of alcohol, high body mass index, high C-Reactive protein, elevated diastolic or systolic blood pressure, and increased glomerular filtration rate. Education and age were removed from the model. The model explained 24.0% of the variability seen in SUA levels (F = 208.62, p < 0.0001) in this multiethnic female population. When the analyses were repeated stratified by race, self-reporting RA was retained in the model as associated with SUA in white and Mexican American, but not in black women.

CONCLUSION

Despite the limitations imposed by self-reporting of RA on self-administered questionnaires and in-person interviews, practitioners should be aware that women self-reporting RA are at risk of having high SUA levels as well as more traditional CVD risk factors. These women should be offered appropriate preventive interventions related to their increased risk for CVD events.

Microalbuminuria in rheumatoid arthritis in the post penicillamine/gold era: association with hypertension, but not therapy or inflammation

Rheumatoid arthritis (RA) associates with excess cardiovascular (CV) morbidity and mortality. New screening tools are needed to better identify patients at increased CV risk. Microalbuminuria (MA) has been shown to associate with inflammation and future cardiovascular disease (CVD). In the present study, we assessed the prevalence of MA in a secondary care cohort of RA patients, aimed to identify factors associated with its presence and addressed its relationship to CVD and the metabolic syndrome (MetS). A total of 342 RA patients were studied. MA was defined as an albumin-creatinine ratio ≥22 (males) or ≥31 (females) milligrams per gram creatinine. The independence of the associations of MA was evaluated using binary logistic regression analysis. Prevalence of MA was 11.9%. Subjects with MA had increased prevalence of hypertension (HT), insulin resistance and type 2 diabetes. In binary logistic regression, only HT (OR = 5.22, 95%CI: 1.51-18.07, p = 0.009) was significantly associated with MA. There was no association between prevalent CVD and MA, but patients with MA had twofold increased odds of having the MetS. MA is relatively common in RA patients and is independently associated with the presence of HT. Given the association of MA with MetS, future prospective studies are needed to establish the use of MA as a screening tool for RA patients at increased CVD risk.

Correlation of asymptomatic hyperuricaemia and serum uric acid levels with arterial stiffness in women with systemic lupus erythematosus without clinically evident atherosclerotic cardiovascular disease

The objective of this article was to evaluate whether serum uric acid (SUA) correlates with arterial stiffness and inflammation markers in a cohort of women with systemic lupus erythematosus (SLE) without overt atherosclerotic cardiovascular diseases, who attended a community hospital. One hundred and two women with SLE were assessed as part of this cross-sectional study. Carotid-femoral pulse wave velocity (PWV) was measured using an automatic device (Complior). C-reactive protein (CRP), fibrinogen and homocysteine levels as well as other metabolic results were recorded. Duration and activity of SLE, damage accrual and treatments were recorded. SLE women were categorized as having or not having hyperuricaemia (HU) according to SUA levels (greater than or up to 6.2 mg/dl, respectively). A multiple linear regression analysis was used to determine the independent link between SUA levels and other variables. Women with SLE and HU (n = 15, 15%) had a worse cardiovascular risk profile that included ageing, hypertension, obesity, higher total cholesterol levels, renal failure and presence of metabolic syndrome. Also, the duration of SLE was increased and damage accrual was greater. In the unadjusted analysis, SUA levels correlated with PWV, CRP, fibrinogen and homocysteine. However, in a multivariate linear regression analysis, SUA levels independently correlated with the duration of SLE, creatinine, total cholesterol and homocysteine levels but did not correlate with PWV. In conclusion, SUA was associated with arterial stiffness, but not independently of age and homocysteine levels. Nevertheless, SUA might be an ancillary indicator of subclinical atherosclerosis in SLE women without clinically evident atherosclerotic cardiovascular disease.

Lack of an association of GNB3 C825T polymorphism and blood pressure in patients with rheumatoid arthritis

G-protein beta 3 subunit (GNB3) C825T (rs5443) single nucleotide polymorphism (SNP) has been implicated as a risk factor for essential hypertension in the general population. The effects of this SNP may be more prominent in subjects with endothelial dysfunction (ED). Rheumatoid arthritis (RA) is associated with ED and has a high prevalence of hypertension. Thus far, this SNP has not been studied in RA patients. We genotyped 383 RA patients and 432 controls. GNB3 C825T was identified using real-time polymerase chain reaction (PCR) and melting curve analysis. There were no differences in the frequencies of the GNB3 C825T genotype and alleles between RA and controls. Within RA patients, prevalence of hypertension did not differ across genotypes. The TT versus CC+CT contrast yielded an adjusted odds ratio (OR) of 0.92 (95% CI: 0.49 to 1.76, p = 0.813), the contrast of TT+CT versus CC an adjusted OR of 2.17 (95% CI: 0.885 to 5.30, p = 0.091), whereas that of the T allele versus C allele an adjusted OR of 1.11 (95% CI: 0.76 to 1.61, p = 0.604). Systolic and diastolic blood pressure levels were not significantly different across the three genotypic groups. No significant interaction was observed between GNB3 825C/T polymorphism and serum endothelin levels. Data from the present study suggest that the T825 variant of the G protein beta 3 subunit gene is unlikely to constitute major susceptibility loci for essential hypertension in Caucasian RA patients. Further larger studies are required to confirm our findings and assess the interaction of rs5443 with environmental factors.

Solute carrier family 2, member 9 and uric acid homeostasis

PURPOSE OF REVIEW

The goal of this article is to review the possible physiological roles of the recently identified urate transporter, solute carrier family 2 (facilitated glucose transporter), member 9 (SLC2A9), in the renal handling of urate.

RECENT FINDINGS

Glucose transporter 9 is a high affinity hexose transporter encoded by the SLC2A9 gene found on human chromosome 4. The two splice variants SLC2A9b and SLC2A9a are expressed in the apical and basolateral membranes, respectively, of the proximal convoluted tubule. Recent reports have found significant correlations between two different sets of single nucleotide polymorphisms in SLC2A9. In one case, they are associated with increases in plasma urate levels and/or the incidence of hypertension or gout. The second set of single nucleotide polymorphisms correlate with hypouricaemia in Japanese patients. Expression of SLC2A9a and b in Xenopus laevis oocytes shows that these proteins mediate rapid urate fluxes and can exchange glucose for urate. Indirect evidence also suggests that the transporter is electrogenic.

SUMMARY

This review proposes that SLC2A9 contributes significantly in two ways to the fluxes of urate across the proximal convoluted tubule. Firstly, the apical expression of SLC2A9b secretes urate back into the urine in exchange for lumenal glucose. Secondly, the basolateral membrane SLC2A9a could be the primary route for urate movement out of the epithelium into the peritubular space.

Target organ damage in patients with rheumatoid arthritis: the role of blood pressure and heart rate

BACKGROUND

Rheumatoid arthritis (RA) is characterised by increased cardiovascular morbidity and mortality. Even though hypertension (HT) is highly prevalent in RA, the extent of target organ damage (TOD) caused by it remains unknown. Inflammation and sympathetic overdrive may also associate with TOD. We investigated the prevalence and associations of TOD in RA.

METHODS

In this cross-sectional, observational study, 251 RA patients with no overt cardiovascular or renal disease had extensive clinical and laboratory evaluations, including a 12-lead electrocardiogram and urine albumin:creatinine ratio. Pulse pressure (PP) was used as a proxy of arterial stiffness and heart rate (HR) of autonomic activity. TOD was defined as described in the European guidelines for the management of arterial hypertension. Binary logistic regression analysis was used to evaluate the independence of the variables that associated with the presence of TOD.

RESULTS

TOD prevalence was 23.5% (59/251). Of the 59 patients with TOD, 45.8% had suboptimally controlled HT, whereas 32.3% had undiagnosed HT. In univariable analysis, TOD was significantly associated with higher age (64.2+/-11.7 years vs. 58.0+/-12.4 years, p=0.001), HT prevalence (89.8% vs. 60.4%, p<0.001), systolic blood pressure (SBP) (150.3+/-18.8mmHg vs. 139.7+/-20.7mmHg, p=0.001), PP (70.6+/-16.6mmHg vs. 60.3+/-17.3mmHg, p<0.001), HR (77.1+/-15.4bpm vs. 72.2+/-12.2bpm, p<0.001), serum uric acid (320.6+/-88.8mumol/l vs. 285.0+/-74.9mumol/l, p=0.03) and type 2 diabetes mellitus prevalence (13.6% vs. 4.7%, p=0.019). Binary logistic regression analysis revealed that only hypertension indices and HR associated independently with TOD.

CONCLUSIONS

TOD is highly prevalent in patients with RA and associates independently with hypertension, arterial stiffness and heart rate. Further prospective studies are needed to confirm these findings and examine the role of beta-blockers in this particular population.

Uric acid is a strong independent predictor of renal dysfunction in patients with rheumatoid arthritis

Introduction

Recent evidence suggests that uric acid (UA), regardless of crystal deposition, may play a direct pathogenic role in renal disease. We have shown that UA is an independent predictor of hypertension and cardiovascular disease (CVD), and that CVD risk factors associate with renal dysfunction, in patients with rheumatoid arthritis (RA). In this study we investigated whether UA associates with renal dysfunction in patients with RA and whether such an association is independent or mediated through other comorbidities or risk factors for renal impairment.

Methods

Renal function was assessed in 350 consecutive RA patients by estimated glomerular filtration rate (GFR) using the six-variable Modification of Diet in Renal Disease equation. Risk factors for renal dysfunction were recorded or measured in all participants. Linear regression was used to test the independence of the association between GFR and UA.

Results

Univariable analysis revealed significant associations between GFR and age, systolic blood pressure, total cholesterol, triglycerides, RA duration and UA. UA had the most powerful association with renal dysfunction (r = -0.45, P < 0.001). A basic model was created, incorporating all of the above parameters along with body mass index and gender. UA ranked as the first correlate of GFR (P < 0.001) followed by age. Adjustments for the use of medications (diuretics, low-dose aspirin, cyclooxygenase II inhibitors and nonsteroidal anti-inflammatory drugs) and further adjustment for markers of inflammation and insulin resistance did not change the results.

Conclusions

UA is a strong correlate of renal dysfunction in RA patients. Further studies are needed to address the exact causes and clinical implications of this new finding. RA patients with elevated UA may require screening for renal dysfunction and appropriate management.

Methotrexate therapy associates with reduced prevalence of the metabolic syndrome in rheumatoid arthritis patients over the age of 60- more than just an anti-inflammatory effect? A cross sectional study

INTRODUCTION

The metabolic syndrome (MetS) may contribute to the excess cardiovascular burden observed in rheumatoid arthritis (RA). The prevalence and associations of the MetS in RA remain uncertain: systemic inflammation and anti-rheumatic therapy may contribute. Methotrexate (MTX) use has recently been linked to a reduced presence of MetS, via an assumed generic anti-inflammatory mechanism. We aimed to: assess the prevalence of the MetS in RA; identify factors that associate with its presence; and assess their interaction with the potential influence of MTX.

METHODS

MetS prevalence was assessed cross-sectionally in 400 RA patients, using five MetS definitions (National Cholesterol Education Programme 2004 and 2001, International Diabetes Federation, World Health Organisation and European Group for Study of Insulin Resistance). Logistic regression was used to identify independent predictors of the MetS. Further analysis established the nature of the association between MTX and the MetS.

RESULTS

MetS prevalence rates varied from 12.1% to 45.3% in RA according to the definition used. Older age and higher HAQ scores associated with the presence of the MetS. MTX use, but not other disease modifying anti-rheumatic drugs (DMARDs) or glucocorticoids, associated with significantly reduced chance of having the MetS in RA (OR = 0.517, CI 0.33-0.81, P = 0.004).

CONCLUSIONS

The prevalence of the MetS in RA varies according to the definition used. MTX therapy, unlike other DMARDs or glucocorticoids, independently associates with a reduced propensity to MetS, suggesting a drug-specific mechanism, and makes MTX a good first-line DMARD in RA patients at high risk of developing the MetS, particularly those aged over 60 years.