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Atherosclerosis 224 (2012) 283e290

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Atherosclerosis

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Review

Vascular calcification in rheumatoid arthritis: Prevalence, pathophysiologicalaspects and potential targets

J. Paccou a,b,*, M. Brazier b, R. Mentaverri b, S. Kamel b, P. Fardellone a,b, Z.A. Massy b,c,d

aDepartment of Rheumatology, University Hospital of Amiens, FR-80054 Amiens, Franceb INSERM U1088 “Pathophysiological mechanisms and consequences of cardiovascular calcification: role of cardiovascular and bone remodelling”, Avenue René Laennec, UniversityHospital of Amiens, FR-80054 Amiens, FrancecDepartment of Clinical Pharmacology, University Hospital of Amiens, FR-80054 Amiens, FrancedDepartment of Nephrology, University Hospital of Amiens, FR-80054 Amiens, France

a r t i c l e i n f o

Article history:Received 19 October 2011Received in revised form29 March 2012Accepted 13 April 2012Available online 8 May 2012

Keywords:Vascular calcificationAtherosclerosisRheumatoid arthritisCalcium sensing receptor

* Corresponding author. Department of RheumatoAmiens, FR-80054 Amiens, France. Tel.: þ33 3 22 82 7

E-mail address: julienpaccou@yahoo.fr (J. Paccou).

0021-9150/$ e see front matter � 2012 Elsevier Ireladoi:10.1016/j.atherosclerosis.2012.04.008

a b s t r a c t

Individuals with rheumatoid arthritis (RA) are at increased risk for morbidity and mortality fromcardiovascular disease. Excess cardiovascular mortality in RA patients cannot be fully explained byconventional cardiovascular risk factors. The purpose of this review is to discuss recent progress con-cerning the prevalence and pathophysiological aspects of vascular calcification in RA. RA patients haveearly-onset diffuse calcification involving multiple vascular beds compared to age and sex-matchedcontrols. Pathogenesis of vascular calcification in RA patients is not fully understood, but specificmediators such as proinflammatory cytokines and not global inflammation could be involved. Thepossible link between osteoporosis and vascular calcification in RA will not be discussed. Finally,potential targets to reduce vascular calcification in RA will be discussed.

� 2012 Elsevier Ireland Ltd. All rights reserved.

Contents

1. Rheumatoid arthritis patients present excess cardiovascular mortality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2842. Types of vascular calcification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2843. Genetic disorders associated with vascular calcifications and atherosclerosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2844. Prevalence and extent of vascular calcification in rheumatoid arthritis patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2855. Pathophysiological aspects of vascular calcification and atherosclerosis in rheumatoid arthritis: molecular levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285

5.1. Inflammatory mediators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2855.2. Insulin resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2855.3. Endothelial dysfunction: adhesion molecules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2855.4. RANKL/OPG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2865.5. Neopterin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2865.6. Adipocytokines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2865.7. Oxidative stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2865.8. Other potential mediators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286

6. Pathophysiological aspects of vascular calcification and atherosclerosis in rheumatoid arthritis: cellular levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2866.1. Calcium sensing receptor (CaR) and vascular smooth muscle cells (VSMCs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2866.2. Monocytes/macrophages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

7. Potential targets to reduce vascular calcification in RA (Fig. 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2877.1. Modulation of proinflammatory cytokines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2877.2. Modulation of RANKL/OPG pathway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2877.3. Calcimimetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

logy, University Hospital of7 90; fax: þ33 3 22 82 74 69.

nd Ltd. All rights reserved.

J. Paccou et al. / Atherosclerosis 224 (2012) 283e290284

8. Perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2889. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

1. Rheumatoid arthritis patients present excesscardiovascular mortality

It has been clearly established that the excess mortality associ-ated with rheumatoid arthritis (RA) is mainly due to cardiovasculardisease, especially coronary heart disease [1e5]. A meta-analysiswas recently conducted to evaluate the incidence of fatal myocar-dial infarction and stroke events in RA patients [6]. The incidence offatal myocardial infarction was 13.3 per 1000 RA patient-years (CI:13e13.6) and the incidence of fatal stroke was 4.5 per 1000 RApatient-years (CI: 4.3e4.7). The relative risk of fatal myocardialinfarction in RA patients was about 1.63 compared to the generalpopulation (OR ¼ 1.63, CI: 1.34e2). No excess risk was observed forfatal stroke in RA patients [6]. Furthermore, the increased risk forcardiovascular disease cannot be fully explained by conventionalcardiovascular risk factors [1,2]. Conventional cardiovascular riskstratification tools, such as the Framingham risk score [7], widelyused in primary prevention in the general population, may be lesssuitable in patients with RA.

Another tool to improve cardiovascular risk stratification iscoronary artery calcium (CAC) scoring by computed tomography[8]. High CAC scores have also been associated with increased all-cause mortality, cardiovascular mortality and coronary events [9].Moreover patients with RA have a higher prevalence and a greaterburden of coronary calcification than non-RA controls [10,11].

It may be useful to identify RA patients at high risk for coronaryartery disease in order to adopt a more aggressive risk-reducingstrategy. However, the clinical value of the CAC risk score as a riskstratification tool has not been clearly validated in the generalpopulation and in RA patients. It is noteworthy that coronary heartdisease can occur in the absence of coronary artery calcification[12], particularly at the beginning of RA disease [13]. However,vascular calcification used in most studies as subclinical marker ofatherosclerosis also constitute an important risk factor formortality in chronic kidney disease (CKD) and diabetes mellituspatients and many studies have indicated that the risk for cardio-vascular events is increased in the presence of vascular calcification[14,15].

Excess cardiovascular mortality in RA patients cannot be fullyexplained by conventional cardiovascular risk factors. Evaluatingcoronary artery calcification in RA could help to identify patients athigh risk for coronary artery disease, indicating the need for a moreaggressive risk-reducing strategy.

2. Types of vascular calcification

Ectopic mineral deposition occurs in many pathologic condi-tions, including vascular calcification characterized by convergenceof bone biology with chronic vascular inflammation. There areconflicting theories about the mechanisms underlying vascularcalcification but two main types of vascular calcification aredescribed: atherosclerotic calcification and medial artery calcifi-cation [16]. These different types are the consequence of distinctyet overlapping pathological mechanisms, and they are by nomeans mutually exclusive of one another. Medial and atheroscle-rotic calcification occur frequently in concert and contributesynergistically to disease [17]. Atherosclerotic calcification occurs atsites of atherosclerotic plaques, where there is a combination of

cellular necrosis, inflammation, and cholesterol deposition.Atherosclerotic calcification forms via a process similar to endo-chondral ossification; chondrogenesis precedes osteoblast induc-tion and lamellar bone formation. As the lesion progresses,osteogenesis is evident [18]. Several studies support the idea thatcalcium deposition in atherosclerotic plaque is an active andregulated process [19]. In contrast, medial artery calcificationproceeds through a process similar to matrix vesicleemediatedintramembranous bone formation, with no cartilage intermediaterequired [20]. This condition is common in diabetes, chronic kidneydisease, aging and probably in rheumatoid arthritis [21]. Thesefeatures distinguish atherosclerotic calcification and medial arterycalcification (organized as bone-like regions) from the dystrophiccalcium deposition also frequently observed in vessels in condi-tions involving chronic inflammation and necrosis.

As we have seen before, the prognostic importance of vascularcalcification is also amatter of debate [17]. In atherosclerotic plaque(more than 90% of atherosclerosis fatty plaques undergo calcifica-tion), the contribution of focal calcification to plaque vulnerabilityremains unclear but atherosclerotic plaque calcification is currentlyused as subclinical marker of atherosclerosis. Medial artery calci-fication contributes to vascular stiffness and is strongly correlatedwith coronary artery disease and future cardiovascular events inpatients with CKD and in diabetic subjects [14,15]. One of the mostimportant limitations CAC scoring by current techniques, such aselectron beam computed tomography, is the difficulty to distin-guish between superficial, focal atherosclerotic calcification anddeep, concentric medial calcification [17].

3. Genetic disorders associated with vascular calcificationsand atherosclerosis

Genetic factors clearly contribute to variation in amounts ofmedia and intimal arterial calcification. Genome-Wide AssociationStudies (GWAS) have substantially increased our knowledge on riskstratification in CAC and atherosclerosis [22]. Major insight hasbeen provided through rare monogenic human disorders associ-ated with spontaneous, premature artery media calcification:mutations in ABCC6 in pseudoxanthoma elasticum (PXE), muta-tions in ENPP1 in generalized arterial calcification of infancy (GACI)and, most recently, mutations in NT5E in another rare diseasephenotype consisting of peripheral artery calcification with distaljoint calcification caused by CD73 deficiency [23e25]. The under-lying disease genes appear to prevent spontaneous calcificationwithin an arterial molecular pathophysiology network modulatedby ATP metabolism, inorganic pyrophosphate (PPi), adenosine, andinorganic phosphate (Pi) generation [22]. Since methotrexateincreases extracellular adenosine, it would be worthwhile to eval-uate its role in the genesis of vascular calcification in future studiesin RA patients [26]. No relation of these monogenetic humandisorders has been studied in RA but it is known that not all RApatients have the same cardiovascular outcome, and it has beenspeculated that genetic susceptibility to atherosclerosis may playa role. The HLA-DRB1*0404 is a predisposition gene for RA and ithas been associated with the severity of RA. However, RA patientswith HLA-DRB1*0404 gene shared epitope-positive have moreendothelial dysfunction and particularly increased cardiovascularmortality compared to the epitope-negative RA patients [27,28].

J. Paccou et al. / Atherosclerosis 224 (2012) 283e290 285

4. Prevalence and extent of vascular calcification inrheumatoid arthritis patients

Recent advances in multi-detector computed tomography allowrapid, effective and non-invasive detection of the extent andseverity of atherosclerosis in various arterial beds by imagingarterial calcification reflecting the presence of calcified athero-sclerotic plaque but also medial calcification [10,11,29].

Computed tomography was used to measure the extent ofcoronary artery calcification in 227 subjects, 70 of whom had earlyRA (duration of disease <5 years, mean age: 51 years), 71 hadestablished RA (duration of disease >10 years, mean age: 58 years),and 86were controls (matched for age, sex, and race) [10]. Coronaryartery calcification, calculated according to the Agatston calciumscore [29], was compared in patients and controls, and its rela-tionship to clinical characteristics was examined. Coronary arterycalcification occurred more frequently in patients with establishedRA (60.6%) than in patients with early RA (42.9%) and controlsubjects (38.4%) (p ¼ 0.016). The OR for the likelihood of havingmore severe coronary artery calcification (defined as an Agatstonscore >109) in patients with established disease compared to earlyRA was 2.32 [CI: 1.05e5.13] (p ¼ 0.037) after adjusting for cardio-vascular risk factors. Among patients with RA, smoking andelevated erythrocyte sedimentation rate were associated withmore severe coronary artery calcification after adjustment for ageand sex (no association with C-reactive protein). The OR was 1.02[CI: 1.00e1.04] (p ¼ 0.04) for smoking, and 1.02 [CI: 1.00e1.04](p ¼ 0.05) for elevated erythrocyte sedimentation rate.

Computed tomography of the thoracic aorta, coronary arteriesand carotid arteries was used to measure the distribution andextent of arterial calcification in 85 RA patients and 85 age and sex-matched controls [11]. After adjusting for age and sex, RA patientshad a significantly higher relative risk of developing calcification inthe aorta [OR¼ 19.5, CI: 8.0e47.6] (p< 0.01), and also in the carotidarteries (OR ¼ 5.7, CI: 1.7e18.7) (p ¼ 0.004) and coronary arteries(OR ¼ 5.0, CI: 2.2e11.1) (p < 0.01) compared to controls. AmongstRA patients aged >60 years, 90% had diffuse arterial calcification,especially in the thoracic aorta, compared with 55% of controls whohad arterial calcification clustered in the coronary arteries(p < 0.05). The prevalence of arterial calcification observed inpatients with RA aged<40 years old was similar to that observed incontrols aged >60 years (Fig. 1). RA patients with arterial calcifi-cation were older with higher levels of both urea (no difference forcreatinine levels) and C-reactive protein (no available data forerythrocyte sedimentation rate) than those without arterial calci-fication. However, after adjustment for age and sex, no factor wasfound to be independently predictive for arterial calcification (allp > 0.05).

Fig. 1. Prevalence and extent of calcification over aorta, coronary and carotid arteriesin patients with rheumatoid arthritis (CCS ¼ coronary calcium score; CACS ¼ carotidarteries calcium score; ACS ¼ aorta calcium score). Figure derived from [11].

RA patients have early-onset diffuse calcification involvingmultiple vascular beds compared to age and sex-matched controls.The prevalence of arterial calcification observed in patients with RAaged < 40 years was similar to that observed in controls aged > 60years.

5. Pathophysiological aspects of vascular calcification andatherosclerosis in rheumatoid arthritis: molecular levels

The increased risk for cardiovascular disease cannot be fullyexplained by conventional cardiovascular risk factors [1,2] and canbe attributed to chronic inflammation [10,11,30]. The pathogenesisof atherosclerosis and vascular calcification inRApatients is not fullyunderstood, but specific inflammatorymediators rather than globalinflammation could be involved in this pathological process [31].

5.1. Inflammatory mediators

Clinical variables, concentrations of inflammatory mediators,and coronary artery calcification were measured in 169 patientswith RA and 92 control subjects [31]. Differences in concentrationsof inflammatory mediators were compared and the relationship ofinflammatory mediators with severity of coronary calcification inRA and control subjects was examined. Median concentrations ofinterleukin-6 (IL-6), tumor necrosis factor alpha (TNFa), serumamyloid A (SAA), peripheral blood neutrophil count, IL-1, myelo-peroxidase (MPO), E-selectin, and intercellular adhesion molecule(ICAM-1) were higher in serum of patients with RA than controls(all p < 0.05), independently of the Framingham risk score anddiabetes mellitus (DM). However, only IL-6 (OR ¼ 1.72; CI: 1.12,2.66) and TNFa (OR ¼ 1.49; CI: 1.16, 1.90) concentrations weresignificantly associated with higher coronary calcium levelsmeasured by Agatston score, independently of the Framingham riskscore and DM, and these main effects were significantly differentfrom controls (p ¼ 0.001 and 0.03 for interaction, respectively).

5.2. Insulin resistance

Insulin could be considered as a crucial factor in RA-inducedatherosclerosis acceleration [32]. In RA patients, glucose intoler-ance is mainly due to the increase of peripheral insulin resistance,which is mediated by proinflammatory cytokines as TNFa and freefatty acids [33,34]. Insulin resistance has also been associated withthe increase of cardiovascular disease [33,34]. Insulin increaseatherosclerosis in humans by the direct induction of proin-flammatory activities on leucocytes, endothelial cells and vascularsmooth muscle cells [35,36].

5.3. Endothelial dysfunction: adhesion molecules

Endothelial dysfunction is considered as an early step in theinitial phases of the atherosclerotic process. In RA patients,a marked decrease in arterial compliance (measured as pulse-waveanalysis) has been showed in the absence of traditional cardio-vascular risk factors [36]. In addition, soluble biomarkers of endo-thelial dysfunction, such as vascular cell adhesion molecules(VCAM)-1, intercellular adhesion molecule (ICAM)-1 and endo-thelial leucocyte adhesion molecule (ELAM)-1, are increased in RApatients in comparisonwith healthy controls [37]. In a recent study,ICAM-1 was higher in serum of patients with RA than controls butwas not significantly associated with higher coronary calciumlevels [31]. The molecular mechanisms, that generate endothelialdysfunction in RA patients, are still unclear but endothelialdysfunction is characterized by decreased production of nitricoxide (NO) and increased expression of cytokines. Endothelial

J. Paccou et al. / Atherosclerosis 224 (2012) 283e290286

progenitor cells have also been investigated, but more evidence isneeded to support their implications in atherosclerotic processes.

5.4. RANKL/OPG

Osteoprotegerin (OPG) is implicated in the pathogenesis ofatherosclerosis. Its expression and production are regulated byseveral inflammatory cytokines including.

Interleukin-1 and TNFa. Recent clinical studies in the generalpopulation have demonstrated that increased concentrations ofOPG were associated with the presence and severity of coronaryartery disease [38,39]. Serum OPG concentrations and coronaryartery calcification, determined by electron beam computertomography, weremeasured in 157 patients with RA and 87 controlsubjects [40]. OPG concentrations were higher in patients withlongstanding RA (>10 years of disease, mean age: 59 years, n ¼ 67),andearlyRA (<6years of disease,meanage:51years,n¼90), than incontrols (p < 0.001). In patients with RA, OPG concentrations wereassociated with erythrocyte sedimentation rate (p < 0.001), homo-cysteine (p ¼ 0.001), disease duration (p ¼ 0.02), coronary calciumscore (p ¼ 0.03), and cumulative dose of corticosteroids (p ¼ 0.04)after adjustment for age and sex. In patients with longstanding RA,OPG was associated with coronary artery calcification indepen-dently of cardiovascular risk factors and disease activity (p< 0.001).Indeed, recent data suggest that OPG is a marker of inflammation inRA [41,42]. In addition to its associationwith inflammatorymarkersin RA, OPG is associatedwith an increased burdenof atherosclerosis.

Correlations between circulating serum levels of the receptoractivator of nuclear factor-kappa B ligand (RANKL) and cardiovas-cular risk have been evaluated in humans. Serum levels of RANKLwere shown to be independent predictors of acute cardiovascularevents in a general population [43]. Although a correlation betweenRANKL levels and CAC score has not been directly proven, serumRANKL levels and vascular calcification scores in patients withchronic kidney disease undergoing hemodialysis were independentdeterminants of cardiovascular events in a 2-year study [44]. Itcould be relevant to determine whether RANKL concentrations areassociated with the presence and severity of coronary arterydisease in RA patients.

5.5. Neopterin

Activation of macrophages may contribute to increasedatherosclerosis and coronary artery disease in RA. Neopterin isa marker of monocytes and macrophage activation. Higherconcentrations of neopterin are associated with increased cardio-vascular risk and atherosclerosis in the general population [45]. Ina recent study in RA, the neopterin level was not associated withcoronary atherosclerosis measured by CAC score [45].

5.6. Adipocytokines

Adipocytokines (leptin, adiponectin, resistin, and visfatin) havebeen linked to obesity, insulin resistance, inflammation, and coro-nary heart disease in the general population. Adiponectin isconsidered one of the most promising targets against chronicinflammatory diseases, including atherosclerosis and RA [30].Adiponectin has been shown to induce anti-inflammatory activitiesin both humans and animalmodels and clinical studies suggest thatadiponectin could reduce atherosclerosis [46,47]. A study wasconducted to examine the hypothesis that adipocytokines mayaffect coronary atherosclerosis (CAC determined by electron beamcomputed tomography) in 169 patients with RA [48]. None of theadipocytokines was independently associated with the coronarycalcium score (all p > 0.05).

5.7. Oxidative stress

Oxidative stress is increased in patients with RA due toincreased inflammation and could contribute to the pathogenesisof atherosclerosis. The independent association between urinaryF2-isoprostane excretion, a measure of oxidative stress, and RAwastested in 169 patients with RA and 92 control subjects, frequencymatched for age, race, and sex [49]. F2-isoprostane urinary excre-tionwas higher in patients with RA than in control subjects. Amongpatients with RA, higher F2-isoprostane excretion and HDLcholesterol concentrations interacted significantly and were posi-tively associated with the severity of coronary calcification.

5.8. Other potential mediators

Several other mediators, such as uncarboxylated matrix Glaprotein (ucMGP), TRAIL and homocysteine [50,51], are probablyinvolved in the pathogenesis of atherosclerosis and vascular calci-fication in RA patients, but, to our knowledge, no interaction withvascular calcification has been demonstrated specifically in RApatients.

Pathogenesis of vascular calcification in RA patients is not fullyunderstood, but specific mediators such as TNFa, IL-6, OPG andoxidative stress (urinary F2-isoprostane) and not general inflam-mation could be involved.

6. Pathophysiological aspects of vascular calcification andatherosclerosis in rheumatoid arthritis: cellular levels

Cells such as circulating monocytes and vascular smooth musclecells (VSMCs) are also involved in the pathogenesis ofatherosclerosis.

6.1. Calcium sensing receptor (CaR) and vascular smooth musclecells (VSMCs)

Calcium is a divalent ion and a ubiquitous primary messengerplaying a complex and varied role in the body. Given the calciumconcentration present in calcified vessel walls, it seemed importantto clarify the role of the Calcium Sensing Receptor (CaR) in thepathological process leading to vascular calcification in vitro andin vivo. Studies have demonstrated the importance of stimulation ofthe CaR and its expression in the prevention of vascular calcifica-tion in vitro and in vivo. Effects resulting from stimulation of the CaRby calcium (the natural agonist) and a calcimimetic (Cinacalcet�)appear to be associated with: i) a direct effect on VSMCs ii) inhi-bition of migration of VSMCs and iii) blocking part of the trans-differentiation of calcifying vascular cells in VSMCs [52].

This beneficial local effect could be associated with the benefi-cial systemic effect exerted by calcimimetics (regulation of circu-lating levels of PTH) and may be associated with regulation of theactivity of VSMCs, osteoclast precursors such as monocytes orendothelial cells in the development of disease [52]. In CKD, theprevalence of arterial calcification is correlated with disease stageand progression of arterial calcification is also more rapid. In thiscontext, vascular calcification is associated with increased cardio-vascular mortality [14]. The expression of CaR on VSMCs wasdecreased in the arteries of patients with CKD compared to controls[53]. Modulation of CaR expression on VSMCs in CKD by calcimi-metic agents (R-568) was recently demonstrated to effectivelydelay progression of vascular calcification and atherosclerosis inuremic apolipoprotein E-deficient mice [54]. No data are availableconcerning CaR expression on VSMCs in RA patients.

J. Paccou et al. / Atherosclerosis 224 (2012) 283e290 287

6.2. Monocytes/macrophages

Other cells, such as monocytes/macrophages, are also implicatedin the pathogenesis of atherosclerosis and vascular calcification, but,to our knowledge, no specific study has been conducted in RApatients. The presence of the CaR has been demonstrated on mono-cytes, cells that play an important role in atherosclerotic progression[55,56]. Chronic inflammatoryconditions, suchasatherosclerosis, areassociatedwith calciumdeposition. The tissue calciumconcentrationin such settings can be substantially higher than in the serum andthese extracellular calcium gradients actively participate in modu-lating the immune response, acting via the CaR. This receptor wasoriginally defined by its role in mediating systemic calcium homeo-stasis; however, it has since been shown to have pleiotropic effectsincluding modification of cellular proliferation, differentiation, andapoptosis [57e59]. However, the physiological role of the CaR inmononuclear cells is largely unknown. It has recently been shownthat ionic calcium is a chemokinetic agent for humanmonocytes. Theactivity of calcium is mediated via the G proteinecoupled CaR, andinteractions with other chemokinetic agents are induced by CaRactivation [60]. Monocytes/macrophages also modulate vascularcalcification in vitro. Calcifying vascular cells (CVCs), a subpopulationof osteoblast-like cells derived from the arterywall,were co-culturedwith humanperipheral bloodmonocytes. Results of co-cultured cellssuggest that, in vitro, monocytes enhance vascular calcification via 2independent mechanisms: cellecell interaction and production ofsoluble factors such as tumor necrosis factor alpha [61]. These resultssuggest that the calcium gradient present adjacent to vascularcalcification in atherosclerosismay be one of the initiating factors forhoming of monocytes/macrophages and could therefore possiblyplay a role in initiation of atherosclerosis [62].

Pathogenesis of vascular calcification in RA patients is not fullyunderstood, but cells such as monocytes/macrophages and VSMCscould be involved.

7. Potential targets toreducevascular calcification inRA (Fig. 2)

7.1. Modulation of proinflammatory cytokines

Tumor necrosis factor alpha (TNFa) antagonists constituteamajor advance in the treatment of RA,with randomized controlled

Fig. 2. Potential targets of vascular cal

trials demonstrating significant reductions in pain and improve-ment in function [63].Moreover, promising results on improvementof cardiovascular outcomes have been reportedwith the use of TNFaantagonists in two European studies [64,65]. A recent longitudinalandobservational studywasdesigned to investigate the incidence ofcardiovascular events among RA patients treated with TNFa antag-onists, methotrexate, other non-biological disease-modifying anti-rheumatic drugs (DMARDs) and prednisone in a large US-basedcohort (CORRONA registry) [66]. This study showed that treatmentwith TNFa antagonists, but not methotrexate, was associated witha reduced risk of cardiovascular events compared with non-biological DMARDs [66]. In summary, these data indicate thatTNFa antagonists may represent a therapeutic strategy to attenuatethe heightened cardiovascular risk experienced by RA patients. Themechanism underlying these data is unknown, but TNFa has beendetected in the endothelium, smoothmuscle cells andmacrophagesassociatedwith coronary atherosclerotic plaques [67]. A key role forTNFa in atherosclerosis is also supported by the observations thatanti-TNFa agents reduce carotid intima-media thickness, improveendothelial function in RA, reduce insulin resistance in RA patients[68e71]. Recent data are available concerning the impact of anti-TNFa on vascular calcification in RA. Anti-TNFawas associated withan important reduction of vascular calcification in a study on 150 RApatients [72].

The finding of an association between IL-6 concentrations andcoronary artery calcification in RA is intriguing because a new drugfor RA, tocilizumab, targets IL-6 receptors [31]. No studies havebeen conducted in humans on the effects of IL-6 inhibition onatherosclerosis or cardiovascular outcomes, and whether inhibitionof IL-6 will affect the pathogenesis or progression of atherosclerosisand improve cardiovascular mortality in RA remains an important,open question.

7.2. Modulation of RANKL/OPG pathway

In a recent study in patients with longstanding RA, OPG wasassociated with coronary artery calcification independently ofcardiovascular risk factors and disease activity (p < 0.001) [40].Indeed, recent data suggest that OPG and RANKL are markers ofinflammation in RA influenced by anti-TNFa [41,42]. In a murinemodel, inhibition of RANKL by denosumab attenuated vascular

cification in rheumatoid arthritis.

J. Paccou et al. / Atherosclerosis 224 (2012) 283e290288

calcium deposition [73]. This therapeutic approach might be ofparticular benefit in RA patients with increased cardiovascular risk[74]. Phase 3 clinical studies have been carried out to evaluate theefficacy and safety of denosumab in patients with osteoporosis [75],rheumatoid arthritis [76], solid tumors with bone metastasis [77]and multiple myeloma [78,79]. Despite encouraging results in thetreatment of these diseases, the effect of denosumab on cardio-vascular diseases has not yet been investigated as primary outcomemeasure. No differences in terms of cardiovascular adverse eventswere observed in patients with osteoporosis treated by denosumabor placebo [75]. It is worthwhile to explore if in RA patients, RANKLantagonism might induce a double direct benefit by improvingboth rheumatoid arthritis and associated cardiovascular disease. Inthe future, larger clinical studies are needed to evaluate thepotential effects of denosumab in cardiovascular calcifications andassociated cardiovascular events.

7.3. Calcimimetics

Cells involved in the pathogenesis of atherosclerosis, such asmonocytes and VSMCs, express a functional CaR [53,55,56]. Inexperimental CKD, in vitro and in vivo data have recently demon-strated that modulation of the CaR by calcimimetics limits theprogression of aortic calcification and atherosclerosis [54]. TheADVANCE trial (Study to Evaluate Cinacalcet Plus LowDose VitaminD on Vascular Calcification in SubjectsWith Chronic Kidney DiseaseReceiving Hemodialysis) was conducted in dialysis patients [80]. Itshowed that calcimimetics (Cinacalcet�) can slow the progressionof cardiovascular calcification in subjects with chronic kidneydisease receiving hemodialysis [80]. No data are available forpatients with RA, but CaR could be a very promising target.

8. Perspectives

Inflammatory cytokines such as TNFa and IL-6, are associatedwith the severity of coronary atherosclerosis measured by electronbeam computed tomography in patients with RA and are alsoimplicated in the pathogenesis of RA [31]. These data are consistentwith the concept that inflammation promotes atherosclerosis andvascular calcification, as suggested by animal models and epide-miological studies [81]. Moreover, a key role for TNFa in athero-sclerosis is also supported by data concerning anti-TNFa therapy, asanti-TNFa therapy may decrease cardiovascular morbidity andmortality in RA but little is known about its capacity to preventvascular calcification [64e66,72].

However, several issues remain to be elucidated:

- Specific mechanisms by which inflammation promotesatherosclerosis and vascular calcification in RA.

- The role of other inflammatory cytokines, such as IL-6 and IL-1in both.

Processes

- The effects of other therapies used in RA, apart from anti-TNFatherapy, such as methotrexate, on atherosclerosis and vascularcalcification in RA. It is noteworthy that, in a prospective studyon mortality in RA, cardiovascular deaths were reduced by 70%among individuals treated with methotrexate [82].

Additional studies are therefore necessary to investigate thespecific mechanisms by which inflammatory cytokines play a rolein differentiation of calcifying vascular cells and mineralization. Forexample, it would be interesting to investigate whether CaR isinvolved in this process, as CaR is expressed on VSMCs, andwe have

recently demonstrated that modulation of CaR limits progression ofcalcification in vivo [54].

Moreover, since monocytes and macrophages can enhancevascular calcification in vitro via both cellecell interactions and theproduction of inflammatory cytokines, it is would be important toevaluate the effects of TNFa on monocytes themselves, and theregulation of cell responses to TNFa [61,83].

Since there are no human studies of the effects of IL-6 inhibitionon cardiovascular outcomes, while adverse effects on lipid profileshave been reported [84], additional in vitro and in vivo studiesdesigned to test whether IL-6 inhibition affects the progression ofatherosclerosis, vascular calcification, and improves cardiovascularmortality in RA are needed.

A recentmeta-analysis clearly illustrated that renal dysfunction isa strong and independent cardiovascular risk factor in the generalpopulation [85]. Interestingly, the CARRE study showed thatsubclinical renal dysfunction is independently associated withcardiovascularevents inRA[86]. This resultneeds tobeconfirmedbutmoderate renal dysfunctionmay play a pivotal role in atherosclerosisin RA [87]. It could be relevant to studywhether vascular calcificationis correlated with subclinical renal dysfunction in RA patients.

Finally, further prospective studies must be conducted withthe main outcomes of prevention of vascular calcificationprogression, atherosclerosis development, and reduced cardiovas-cular morbidity and mortality in RA patients not only with anti-TNFa therapy, tocilizumab but also with the other therapies used inRA, such as methotrexate, abatacept and rituximab.

9. Conclusion

Atherosclerotic plaque calcification represents a commonpathophysiological process in RA disease. Inflammatory processesunderlying plaque calcification are regulated by soluble mediatorssuch as proinflammatory cytokines (TNFa and IL-6) and by mono-cytes/macrophages, endothelial progenitor cells and VSMCs. Abetter knowledge of pathophysiological aspects is needed toexplore potential targets in RA patients with increased cardiovas-cular risk. Inhibition of RANKL, calcimimetics and particularly anti-TNFa agents represent very promising therapeutic approaches.

References

[1] Del Rincon I, Williams K, Stern MP, Freeman GL, Escalante A. High incidence ofcardiovascular events in a rheumatoid arthritis cohort not explained bytraditional cardiac risk factors. Arthritis Rheum 2001;44:2737e45.

[2] Wolfe F, Freundlich B, Straus WL. Increase in cardiovascular and cerebrovas-cular disease prevalence in rheumatoid arthritis. J Rheumatol 2003;30:36e40.

[3] Solomon DH, Karlson EW, Rimm EB, Cannuscio CC, Mandl LA, Manson JE, et al.Cardiovascular morbidity and mortality in women diagnosed with rheuma-toid arthritis. Circulation 2003;107:1303e7.

[4] Maradit-Kremers H, Nicola PJ, Crowson CS, Ballman KV, Gabriel SE. Cardio-vascular death in rheumatoid arthritis: a population-based study. ArthritisRheum 2005;52:722e32.

[5] Goodson N, Marks J, Lunt M, Symmons D. Cardiovascular admissions andmortality in an inception cohort of patients with rheumatoid arthritis withonset in the 1980s and 1990s. Ann Rheum Dis 2005;64:1595e601.

[6] Levy L, Fautrel B, Barnetche T, Schaeverbeke T. Incidence and risk of fatalmyocardial infarction and stroke events in rheumatoid arthritis patients. Asystematic review of the literature. Clin Exp Rheumatol 2008;26:673e9.

[7] Wilson PW, D’Agostino RB, Levy D, Belanger AM, Silbershatz H, Kannel WB.Prediction of coronary heart disease using risk factor categories. Circulation1998;97:1837e47.

[8] Ahmadi N, Hajsadeghi F, Blumenthal RS, Budoff MJ, Stone GW, Ebrahimi R.Mortality in individuals without known coronary artery disease but withdiscordance between the Framingham risk score and coronary artery calcium.Am J Cardiol 2011;107:799e804.

[9] Rennenberg RJ, Kessels AG, Schurgers LJ, van Engelshoven JM, de Leeuw PW,Kroon AA. Vascular calcifications as a marker of increased cardiovascular risk:a meta-analysis. Vasc Health Risk Manage 2009;5:185e97.

[10] Chung CP, Oeser A, Raggi P, Gebretsadik T, Shintani AK, Sokka T, et al. Increasedcoronary-artery atherosclerosis in rheumatoid arthritis: relationship to diseaseduration and cardiovascular risk factors. Arthritis Rheum 2005;52:3045e53.

J. Paccou et al. / Atherosclerosis 224 (2012) 283e290 289

[11] Wang S, Yiu KH, Mok MY, Ooi GC, Khong PL, Mak KF, et al. Prevalence andextent of calcification over aorta, coronary and carotid arteries in patientswith Rheumatoid arthritis. J Intern Med 2009;266:445e52.

[12] Drosch T, Brodoefel H, Reimann A, Thomas C, Tsiflikas I, Heuschmid M, et al.Prevalence and clinical characteristics of symptomatic patients withobstructive coronary artery disease in the absence of coronary calcifications.Acad Radiol 2010;17:1254e8.

[13] Arts EEA, Fransen J, den Broeder AA, van Riel PLCM. Cardiovascular risk inrheumatoid arthritis is independent of disease duration and the level ofdisease activity. Ann Rheum Dis 2011;70(Suppl. 3):122.

[14] London GM, Marchais SJ, Guérin AP, Métivier F. Arteriosclerosis, vascularcalcifications and cardiovascular disease in uremia. Curr Opin NephrolHypertens 2005;14:525e31.

[15] Niskanen L, Siitonen O, Suhonen M, Uusitupa MI. Medial artery calcificationpredicts cardiovascular mortality in patients with NIDDM. Diabetes Care1994;17:1252e6.

[16] Vattikuti R, Towler DA. Osteogenic regulation of vascular calcification: anearly perspective. Am J Physiol Endocrinol Metab 2004;286:E686e96.

[17] Johnson RC, Leopold JA, Loscalzo J. Vascular calcification: pathobiologicalmechanisms and clinical implications. Circ Res 2006;99:1044e59.

[18] Dhore CR, Cleutjens JP, Lutgens E, et al. Differential expression of bone matrixregulatory proteins in human atherosclerotic plaques. Arterioscler ThrombVasc Biol 2001;21:1998e2003.

[19] Doherty TM. Calcification in atherosclerosis: bone biology and chronicinflammation at the arterial crossroads. PNAS 2003;20:11201e6.

[20] Schinke T, McKee MD, Kiviranta R, et al. Molecular determinants of arterialcalcification. Ann Med 1998;30:538e41.

[21] Davies MR, Hruska KA. Pathophysiological mechanisms of vascular calcifica-tion in end-stage renal disease. Kidney Int 2001;60:472e9.

[22] Rutsch F, Nitschke Y, Terkeltaub R. Genetics in arterial calcification: pieces ofa Puzzle and Cogs in a Wheel. Circ Res 2011 August 19;109(5):578e92.

[23] Bergen AA, Plomp AS, Schuurman EJ, et al. Mutations in ABCC6 cause pseu-doxanthoma elasticum. Nat Genet 2000;25:228e31.

[24] St Hilaire C, Ziegler SG, Markello TC, et al. NT5E mutations and arterialcalcifications. N Engl J Med 2011;364:432e42.

[25] Lorenz-Depiereux B, Schnabel D, Tiosano D, et al. Loss-of-function ENPP1mutations cause both generalized arterial calcification of infancy andautosomal-recessive hypophosphatemic rickets. Am J Hum Genet 2010;86:267e72.

[26] Wessels J, Huizinga T, Guchelaar HJ. Recent insights in the pharmacologicalactions of methotrexate in the treatment of rheumatoid arthritis. Rheuma-tology 2008;47:249e55.

[27] Gonzalez-Gay MA, Gonzalez-Juanatey C, Lopez-Diaz MJ, et al. HLA-DRB1 andpersistant chronic inflammation contribute to cardiovascular events andcardiovascular mortality in patients with rheumatoid arthritis. ArthritisRheum 2007;15:125e32.

[28] González-Juanatey C, González-Gay MA, Llorca J, et al. HLA-DRB1 statusaffects endothelial function in treated patients with rheumatoid arthritis. Am JMed 2003;1:647e52.

[29] Agatston AS, Janowitz WR, Hildner FJ, Zusmer NR, Vaimonte Jr M, Detrano R.Quantification of coronary artery calcium using ultrafast computed tomog-raphy. J Am Coll Cardiol 1990;15:827e32.

[30] Montecucco F, Mach F. Common inflammatory mediators orchestrate patho-physiological processes in rheumatoid arthritis and atherosclerosis. Rheu-matology 2009;48:11e22.

[31] Rho YH, Chung CP, Oeser A, et al. Inflammatory mediators and prematurecoronary atherosclerosis in rheumatoid arthritis. Arthritis Rheum 2009;61:1580e5.

[32] La Montagna G, Cacciapuoti F, Buono R, et al. Insulin resistance is an inde-pendent risk factor for atherosclerosis in rheumatoid arthritis. Diab Vasc DisRes 2007;4:130e5.

[33] Svenson KL, Pollare T, Lithell H, et al. Impaired glucose handling in activerheumatoid arthritis: relationship to peripheral insulin resistance. Metabo-lism 1988;37:125e30.

[34] Kappert K, Meyborg H, Clemenz M, et al. Insulin facilitates monocyte migra-tion: a possible link to tissue inflammation in insulin-resistance. BiochemBiophys Res Commun 2008;365:503e8.

[35] Madonna R, Massaro M, De Caterina R. Insulin potentiates cytokine-inducedVCAM-1 expression in human endothelial cells. Biochim Biophys Acta 2008;1782:511e6.

[36] Wong M, Toh L, Wilson A, et al. Reduced arterial elasticity in rheumatoidarthritis and the relationship to vascular disease risk factors and inflamma-tion. Arthritis Rheum 2003;48:81e9.

[37] Dessein PH, Joffe BI, Singh S. Biomarkers of endothelial dysfunction, cardio-vascular risk factors and atherosclerosis in rheumatoid arthritis. Arthritis ResTher 2005;7:634e43.

[38] JonoS, Ikari Y, ShioiA, et al. Serumosteoprotegerin levels are associatedwith thepresence and severity of coronary artery disease. Circulation 2002;106:1192e4.

[39] Schoppet M, Sattler AM, Schaefer JR, Herzum M, Maisch B, Hofbauer LC.Increased osteoprotegerin serum levels in men with coronary artery disease.J Clin Endocrinol Metab 2003;88:1024e8.

[40] Asanuma Y, Chung CP, Oeser A, Solus JF, Avalos I, Gebretsadik T. Serumosteoprotegerin is increased and independently associated with coronary-artery atherosclerosis in patients with rheumatoid arthritis. Atherosclerosis2007;195:135e41.

[41] Ziolkowska M, Kurowska M, Radzikowska A, et al. High levels of osteopro-tegerin and soluble receptor activator of nuclear factor kappa B ligand inserum of rheumatoid arthritis patients and their normalization after anti-tumor necrosis factor alpha treatment. Arthritis Rheum 2002;46:1744e53.

[42] Kubota A, Hasegawa K, Suguro T, Koshihara Y. Tumor necrosis factor-alphapromotes the expression of osteoprotegerin in rheumatoid synovial fibro-blasts. J Rheumatol 2004;31:426e35.

[43] Kiechl S, Schett G, Schwaiger J, Seppi K, Eder P, Egger G, et al. Soluble receptoractivator of nuclear factor-kappa B ligand and risk for cardiovascular disease.Circulation 2007;116:385e91.

[44] Wei T, Wang M, Wang M, Gan LY, Li X. Relationship of sRANKL level andvascular calcification score to cardiovascular events in maintenance hemo-dialysis patients. Blood Purif 2009;28:342e5.

[45] Rho YH, Solus J, Raggi P, Oeser A, Gebretsadik T, Shintani A, et al. Macrophageactivation and coronary atherosclerosis in systemic lupus erythematosus andrheumatoid arthritis. Arthritis Care Res 2011;63:535e41.

[46] Lee SW, Kim JH, Park MC, et al. Adiponectin mitigates the severity of arthritisin mice with collagen-induced arthritis. Scand J Rheumatol 2008;37:260e8.

[47] Tan W, Wang F, Zhang M, et al. High adiponectin and adiponectin receptor 1expression in synovial fluids and synovial tissues of patients with rheumatoidarthritis. Semin Arthritis Rheum 2009;38:420e7.

[48] Rho YH, Chung CP, Solus JF, Raggi P, Oeser A, Gebretsadik T, et al. Adipocy-tokines, insulin resistance, and coronary atherosclerosis in rheumatoidarthritis. Arthritis Rheum 2010;62:1259e64.

[49] Rho YH, Chung CP, Oeser A, Solus JF, Gebretsadik T, Shintani A, et al. Inter-action between oxidative stress and high-density lipoprotein cholesterol isassociated with severity of coronary artery calcification in rheumatoidarthritis. Arthritis Care Res (Hoboken) 2010;62:1473e80.

[50] Cranenburg EC, Brandenburg VM, Vermeer C, Stenger M, Mühlenbruch G,Mahnken AH, et al. Uncarboxylated matrix Gla protein (ucMGP) is associatedwith coronary artery calcification in haemodialysis patients. Thromb Haemost2009;101:359e66.

[51] Mori K, Ikari Y, Jono S, Shioi A, Ishimura E, Emoto M, et al. Association ofserum TRAIL level with coronary artery disease. Thromb Res 2010;125:322e5.

[52] Caudrillier A, Mentaverri R, Brazier M, Kamel S, Massy ZA. Calcium-sensingreceptor as a potential modulator of vascular calcification in chronic kidneydisease. J Nephrol 2010;23:17e22.

[53] Alam MU, Kirton JP, Wilkinson FL, Towers E, Sinha S, Rouhi M, et al. Calcifi-cation is associated with loss of functional calcium-sensing receptor invascular smooth muscle cells. Cardiovasc Res 2009;81:260e8.

[54] Ivanovski O, Nikolov IG, Joki N, Caudrillier A, Phan O, Mentaverri R, et al. Thecalcimimetic R-568 retards uremia-enhanced vascular calcification andatherosclerosis in apolipoprotein E deficient (apoE-/-) mice. Atherosclerosis2009;205:55e62.

[55] Yamaguchi T, Olozak I, Chattopadhyay N, Butters RR, Kifor O, Scadden DT,et al. Expression of extracellular calcium (Ca2þo)-sensing receptor in humanperipheral blood monocytes. Biochem Biophys Res Commun 1998;246:501e6.

[56] House MG, Kohlmeier L, Chattopadhyay N, Kifor O, Yamaguchi T, Leboff MS,et al. Expression of an extracellular calcium sensing receptor in human andmouse bone marrow cells. J Bone Miner Res 1997;12:1959e70.

[57] Brown EM, Quinn S, Vassilev PM, Hebert S. G-protein-coupled, extracellularCa2þ-sensing receptor: a versatile regulator of diverse cellular functions.Vitam Horm 1999;55:1e71.

[58] Lin KI, Chattopadhyay N, Bai M, Alvarez R, Dang CV, Baraban JM, et al. Elevatedextracellular calcium can prevent apoptosis via the calcium-sensing receptor.Biochem Biophys Res Commun 1998;249:325e31.

[59] Freichel M, Zink-Lorenz A, Holloschi A, Hafner M, Flockerzi V, Raue F.Expression of a calcium-sensing receptor in a human medullary thyroidcarcinoma cell line and its contribution to calcitonin secretion. Endocrinology1996;137:3842e8.

[60] Olszak IT, Poznansky MC, Evans RH, Olson D, Kos C, Pollak MR, et al. Extra-cellular calcium elicits a chemokinetic response from monocytes in vitro andin vivo. J Clin Investing 2000;105:1299e305.

[61] Tintut Y, Patel J, Territo M, Saini T, Parhami F, Demer LL. Monocyte/macro-phage regulation of vascular calcification in vitro. Circulation 2002;105:650e5.

[62] Boudot C, Saidak Z, Boulanouar AK, Petit L, Gouilleux F, Massy Z, et al.Implication of the calcium sensing receptor and the Phosphoinositide 3-kinase/Akt pathway in the extracellular calcium-mediated migration of RAW264.7 osteoclast precursor cells. Bone 2010;46:1416e23.

[63] Hochberg MC, Lebwohl MG, Plevy SE, et al. The benefit/risk profile of TNF-blocking agents: findings of a consensus panel. Semin Arthritis Rheum2005;34:819e36.

[64] Jacobsson LT, Turesson C, Gülfe A, et al. Treatment with tumor necrosis factorblockers is associated with a lower incidence of first cardiovascular events inpatients with rheumatoid arthritis. J Rheumatol 2005;32:1213e8.

[65] Carmona L, Descalzo MA, Perez-Pampin E, , et alBIODASER and EMECARGroups. All-cause and cause-specific mortality in rheumatoid arthritis are notgreater than expected when treated with tumour necrosis factor antagonists.Ann Rheum Dis 2007;66:880e5.

[66] Greenberg JD, Kremer JM, Curtis JR, Hochberg MC, Reed G, Tsao P, ,et alCORRONA Investigators. Tumour necrosis factor antagonist use andassociated risk reduction of cardiovascular events among patients withrheumatoid arthritis. Ann Rheum Dis 2011;70:576e82.

J. Paccou et al. / Atherosclerosis 224 (2012) 283e290290

[67] Barath P, Fishbein MC, Cao J, et al. Detection and localization of tumor necrosisfactor in human atheroma. Am J Cardiol 1990;65:297e302.

[68] Hurlimann D, Forster A, Noll G, Enseleit F, Chenevard R, Distler O, et al. Anti-tumor necrosis factor-a treatment improves endothelial function in patientswith rheumatoid arthritis. Circulation 2002;106:2184e7.

[69] Gonzalez-Gay MA, De Matias JM, Gonzalez-Juanatey C, et al. Anti-tumornecrosis factor-alpha blockade improves insulin resistance in patients withrheumatoid arthritis. Clin Exp Rheumatol 2006;24:83e6.

[70] Seriolo B, Paolino S, Ferrone C, Cutolo M. Impact of long-term anti-TNF-alphatreatment on insulin resistance in patients with rheumatoid arthritis. Clin ExpRheumatol 2008;26:159e60.

[71] Del Porto F, Lagana B, Lai S, Nofroni I, Tinti F, Vitale M, et al. Response to anti-tumour necrosis factor blockade is associated with reduction of carotidintima-media thickness in patients with active rheumatoid arthritis. Rheu-matology (Oxford) 2007;46:1111e5.

[72] Karpouzas GA, Malpeso J, Li D, et al. Differential predictors of mixed and fullycalcified coronary claque in coronary artery disease-naïve patients withrheumatoid arthritis. Arthritis Rheum 2011;63:S297.

[73] Helas S, Goettsch C, Schoppet M, et al. Inhibition of receptor activator of NF-KB ligand by denosumab attenuates vascular calcium deposition in mice. Am JPathol 2009;175:473e8.

[74] Quercioli A, Luciano Viviani G, Dallegri F, Mach F, Montecucco F. Receptoractivator of nuclear factor kappa B ligand/osteoprotegerin pathway isa promising target to reduce atherosclerotic plaque calcification. Crit PathwCardiol 2010;9:227e30.

[75] Cummings SR, San Martin J, McClung MR, et al. Denosumab for prevention offractures in postmenopausal women with osteoporosis. N Engl J Med 2009;361:756e65.

[76] Deodhar A, Dore RK, Mandel DM, et al. Denosumab-mediated increase in handbone mineral density associated with decreased progression of bone erosion inrheumatoid arthritis patients. Arthritis Care Res (Hoboken) 2010;62:569e74.

[77] Fizazi K, Lipton A, Mariette X, et al. Randomized phase II trial of denosumab inpatients with bone metastases from prostate cancer, breast cancer, or otherneoplasms after intravenous bisphosphonates. J Clin Oncol 2009;27:1564e71.

[78] Fizazi K, Carducci M, Smith M, Damião R, Brown J, Karsh L, et al. Denosumabversus zoledronic acid for treatment of bone metastases in men withcastration-resistant prostate cancer: a randomised, double-blind study. Lancet2011;377:813e22.

[79] Henry DH, Costa L, Goldwasser F, Hirsh V, Hungria V, Prausova J, et al.Randomized, double-blind study of denosumab versus zoledronic acid in thetreatment of bone metastases in patients with advanced cancer (excludingbreast and prostate cancer) or multiple myeloma. J Clin Oncol 2011;29:1125e32.

[80] Raggi P, Chertow GM, Torres PU, Csiky B, Naso A, Nossuli K, , et alADVANCEStudy Group. The ADVANCE study: a randomized study to evaluate the effectsof cinacalcet plus low-dose vitamin D on vascular calcification in patients onhemodialysis. Nephrol Dial Transplant 2011;26:1327e39.

[81] Aikawa E, Nahrendorf M, Figueiredo JL, Swirski FK, Shtatland T, Kohler RH,et al. Osteogenesis associates with inflammation in early-stage athero-sclerosis evaluated by molecular imaging in vivo. Circulation 2007;116:2841e50.

[82] Choi HK, Hernán MA, Seeger JD, Robins JM, Wolfe F. Methotrexate andmortality in patients with rheumatoid arthritis: a prospective study. Lancet2002;9313:1173e7.

[83] Rushworth SA, Shah S, MacEwan DJ. TNF mediates the sustained activation ofNrf2 in human monocytes. J Immunol 2011;187:702e7.

[84] Kawashiri SY, Kawakami A, Yamasaki S, et al. Effects of the anti-interleukin-6receptor antibody, tocilizumab, on serum lipid levels in patients with rheu-matoid arthritis. Rheumatol Int 2011;31:451e6.

[85] Matsushita K, van der Velde M, Astor BC, et al. Association of estimatedglomerular filtration rate and albuminuria with all-cause and cardiovascularmortality in general population cohorts: a collaborative meta-analysis. Lancet2010;375:2073e81.

[86] Van Sijl AM, van den Oever IA, Peters MJ, et al. Subclinical renal dysfunction isindependently associated with cardiovascular events in rheumatoid arthritis:the CARRÉ Study. Ann Rheum Dis 2012;3:341e4.

[87] Libby P. Role of inflammation in atherosclerosis associated with rheumatoidarthritis. Am J Med 2008;121(10 Suppl. 1):S21e31.