Email updates

Keep up to date with the latest news and content from AIDS Research and Therapy and BioMed Central.

Open Access Highly Accessed Research

A possible role for CCR5 in the progression of atherosclerosis in HIV-infected patients: a cross-sectional study

Laura Fernández-Sender1, Carlos Alonso-Villaverde12, Anna Rull1, Esther Rodríguez-Gallego1, Marta Riera-Borrull1, Anna Hernández-Aguilera1, Jordi Camps1, Raúl Beltrán-Debón1, Gerard Aragonès1, Javier A Menendez3 and Jorge Joven1*

Author Affiliations

1 Unitat de Recerca Biomèdica, Hospital Universitari Sant Joan, Institut d’Investigació Sanitaria Pere Virgili (IISPV), Universitat Rovira i Virgili, Reus, Spain, carrer Sant Llorenç 21, Reus 43201, Spain

2 Pressent address: Servei de Medicina Interna, Hospital Sant Pau i Santa Tecla, carrer Rambla Vella 14, Tarragona 43003, Spain

3 Translational Research Laboratory, Catalan Institute of Oncology (ICO) and Girona Biomedical Research Institute (IdIBGi), Avda de França s/n 17007, Girona, Spain

For all author emails, please log on.

AIDS Research and Therapy 2013, 10:11  doi:10.1186/1742-6405-10-11

The electronic version of this article is the complete one and can be found online at: http://www.aidsrestherapy.com/content/10/1/11


Received:12 December 2012
Accepted:7 May 2013
Published:9 May 2013

© 2013 Fernández-Sender et al.; licensee BioMed Central Ltd.

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background

Chemokines can block viral entry by interfering with HIV co-receptors and are recognised mediators of atherosclerosis development. A number of experimental drugs that inhibit HIV entry arrest the development of atherosclerosis in animal models. We hypothesised that the expression of chemokine receptors in circulating leukocytes is associated with the rate of atherosclerosis progression in HIV-infected patients.

Methods

The increase in intima-media thickness during a 2-year follow-up was used to classify HIV-infected patients (n = 178) as progressors (n = 142) or non-progressors (n = 36) with respect to atherosclerosis. Logistic regression was used to assess variables associated with atherosclerosis progression. Mutations in the CCR5Δ32, CCR2 64I, and CX3CR1 (T280M and V249I) co-receptors as well as the levels of CCR5, CXCR4, CX3CR1, and CCR2 mRNA expression in circulating leukocytes were analysed as independent variables.

Results

Among the baseline variables, only genetic variants explained the dichotomous outcome. The expression of CCR2 and CXCR4 did not discriminate between progressors and non-progressors. Conversely, CCR5 and CX3CR1 expression was higher in not only progressors but also patients with detectable viral load. The logistic regression, however, demonstrated a significant role for CCR5 expression as a predictor of atherosclerosis progression (B = 2.1, OR = 8.1, p = 0.04) and a negligible effect for CXC3R1 and CCR2 expression.

Conclusions

Available CCR5 antagonists should be investigated for their potential to delay the course of atherosclerosis in HIV-infected patients.

Keywords:
Cardiovascular risk factors; Chemokine receptors; Genetic variants; Inflammation; Maraviroc

Background

Current therapies achieve long-term remission and/or prevent morbid conditions associated with human immunodeficiency virus-1 (HIV-1) infection. Despite the ineffective elimination of the virus, correct management is accompanied by a growing increase in life expectancy that involves age-related complications. For example, atherosclerosis and other non-communicable diseases develop earlier and more rapidly in HIV patients compared with non-infected individuals of a similar age with similar risk factors [1-3].

Persistent immune activation may be the reason for this phenomenon, likely through host gene variations in chemokine responses to non-infectious particles or viral proteins [4-6]. Chemokines and chemokine receptors play a significant role in atherosclerosis, may influence susceptibility to HIV infection, and may affect the course of both diseases [6,7]. The CC chemokines, which contain two adjacent cysteines near the amino terminus, are particularly important, and the role of CCL2, a ligand for CCR2, in the development of atherosclerosis has been substantiated in animal models and humans [5,8]. Furthermore, orally bioavailable agents that inhibit the chemotaxis of primary CCR2-expressing human monocytes towards CCL2 are currently in various clinical trials [9,10]. More recently, the chemokine receptor CCR5 and its ligands (CCL3, CCL4 and CCL5) have been implicated in the pathogenesis of atherosclerosis [11], and a relatively common mutation with a corresponding lack of function (CCR5 Δ32) confers relative resistance to HIV infection [12] and a reduction in susceptibility to coronary artery disease [13]. These and other findings have facilitated the development and further approval of CCR5 antagonists (maraviroc) as antiretroviral agents in patients infected with strains that do not use CXCR4 as the co-receptor [14]. It remains to be established whether maraviroc influences the development of atherosclerosis; however, we have recently identified the beneficial effects of both lipid metabolism and inflammation [15]. Fractalkine (CX3CL1) and its receptor, CX3CR1, have also been implicated as modulators of both HIV infection and atherosclerosis, and functional polymorphisms in CXC3R1 (V249I and T280M) are clinically relevant during the course of these conditions [16,17].

The available data are difficult to interpret because of the high redundancy of the chemokine system, conflicting results for the cardiovascular risk predictions, and effects from possible interactions among receptors, which could be confounding factors [16,17]. In this study, we investigated for the first time whether the expression of chemokine receptors in circulating leukocytes was relevant for the assessment of atherosclerosis progression in HIV-infected patients. We determined that CCR5 expression in these cells might be a strong predictor of atherosclerosis progression, indicating a further therapeutic target for CCR5 antagonists.

Methods

Study design, population and standardised ultrasound protocol

This report was prepared in accordance with the STROBE guidelines described at http://www.strobe-statement.org/ webcite. The procedures were performed in accordance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) for experiments involving humans, and the study was approved by the ethics committee at the Hospital Universitari de Sant Joan de Reus. Patients who accepted the invitation to participate in the study provided full informed consent. HIV-infected patients who attended our outpatient clinic were routinely asked to be incorporated into a cohort (n = 523) in accordance with previously described procedures [1,6,18]. None of the included patients were treated with CCR5 antagonists. In a retrospective, longitudinal study, we sampled a cross-section of the patients to assess the intima-media thickness (IMT) at baseline (when incorporated into the cohort) and 2 years later.

We used the LOGIQ 700 ME system (General Electric) to obtain normalised values IMT [1,6]. We identified and digitally recorded the far wall of the common carotid artery (1 cm proximal to the bifurcation), the carotid bulb (in the bifurcation), and the internal carotid artery (1 cm distal from the bifurcation). The IMT measurements of each arterial segment were averaged and used in the statistical analyses as the combined IMT. We identified patients with a 2-year difference in the IMT value that was equal to or lower than the technical differences among examiners as non-progressors. This value was obtained via an intraclass correlation coefficient determined with 30 measurements (r = 0.89, p < 0.001) and established as 0.01 mm (standard deviation 0.02 mm). The progressors exhibited ΔIMT >0.01 mm and/or the presence of a previously unrecognised plaque in the second observation. The procedures were performed essentially as described previously [6,19,20]. To assess the reproducibility of the measurements, the images of 30 randomly selected patients were re-measured using the same protocol. The intraclass correlation coefficient between the 2 sets of measurements was 0.91, and the absolute difference in IMT was 0.007 mm (0.018). To assess the reproducibility of the rescanning and re-measurement, we also measured the inter-month correlation (r = 0.95; n = 15).

The other relevant data were collated from clinical records or obtained using standardised guidelines and routine laboratory methods [21,22]. The covariates used were obtained in the same time frame for each participant. To avoid sampling bias, we selected and presented data only from patients who did not exhibit changes in variables or episodes that were likely to contribute to the outcome during follow-up (n = 217). The patients were observed by their attending doctors every 3 months, and no major events were recorded. Changes in the clinical and laboratory markers of cardiovascular risk and/or HIV infection were considered not relevant (less than 5% of differences with respect to the normal inter-day coefficient of variation for each measurement). The resulting study population was used to determine whether chemokine receptor expression in blood cells was associated with atherosclerosis progression, and additional fasting venous blood samples were drawn immediately before the second IMT measurement under conditions that guaranteed RNA preservation (using TEMPUS blood RNA tubes from Applied Biosystems, Foster City, CA). Inappropriately documented IMT measurements (n = 16), inappropriately handled samples (n = 9), and changes in the antiretroviral treatment (n = 14) were detected and considered exclusion criteria. Therefore, the data for 178 patients are presented. This number was considered sufficiently higher than the minimum sample size obtained (n = 121) according to available data [6,19,20] and assuming a difference between groups exceeding 10%, an overall standard deviation of 20%, and 80% power with a two-sided 5% significance level.

DNA genotyping and mRNA expression

The methods used to isolate DNA and assess the presence of CCR-2 V64I, CCR-5 Δ32, and CX3CR-1 (V249I and T280M) variants have been described in detail [6,23] (see Additional file 1: Table S1 for additional information). RNA in circulating leukocytes was isolated using an ABI PRISM 6100 (Applied Biosystems), and the expression of selected receptors (CCR5, CCR2, CXCR4 and CX3CR1) was measured using the reagents and methods indicated in Table 1. The results were analysed using RQ Manager Software for automated data analysis. The expression values for the target genes were normalised to the values of a designated endogenous control (GAPDH), which was not affected by the HIV infection in our hands, and expressed in arbitrary units [24,25]. We hypothesised that there may be differences between the distribution of the mRNAs and the localisation of the actual proteins and that it was unlikely that surface cell receptors could be delivered to other tissues or undergo posttranslational rearrangements [26].

Additional file 1: Table S1. Summary of gene polymorphisms genotyped in this study.

Format: DOC Size: 35KB Download file

This file can be viewed with: Microsoft Word ViewerOpen Data

Table 1. Summary of taqman® gene expression assays used in this study*

Statistical analyses

The data were presented as the means plus the standard error of the mean (in parentheses). The normality of the distributions was assessed using the Kolmogorov-Smirnov method. The groups were compared using Student’s unpaired t-test or Kruskal–Wallis one-way analysis. There were no adjustments for multiple testing for genetic analyses because the variants were not rare and the correspondence for their phenotypes was absent according to the described procedures [27]. The χ2 test was used to compare categorical variables. Multivariate logistic regression stepwise analyses were performed to detect factors associated with the condition of progressors. Odds ratios were included when necessary. Allelic frequency descriptions and Hardy-Weinberg equilibrium tests were performed using freely available software (http://bioinfo.iconcologia.net/SNPstats webcite). To create a “quasi-randomised” experiment, we used the propensity score analyses described previously [28-30]. For other measurements, we used SPSS software version 18.0 (SPSS Inc., Chicago, IL).

Results and discussion

In accordance with our expectations, most of the patients included in the study were considered progressors (n = 142); however, a substantial number of patients demonstrated no evidence of increased IMT values during the 2-year study (n = 36). The patients who demonstrated progression of subclinical atherosclerosis were treated with either an efavirenz-based regimen (38%) or protease inhibitors (39%), and a number of patients were left untreated. The majority of the patients maintained a low viral load. The treatment regimens for patients who did not demonstrate progression were similar. We did not observe a between-group difference in the lipid-lowering and/or hypoglycaemic treatments, and to avoid confusion, none of the patients were taking CCR5 antagonists.

The treatment and other baseline clinical and laboratory variables (Table 2) did not allow the prediction of whether subclinical atherosclerosis would progress. However, this does not mean that any of these variables could be determinants of progression because according to our study design, only negligible changes were allowed. We appreciate that this is not feasible for normal clinical management procedures; however, we believe it would be helpful to search for other possible predisposing factors. Intervention and randomisation were not used in this study. The presence of bias was considered unlikely but could be a limitation of the study as discussed below. Despite these considerations, we reasonably excluded the robust influence of factors such as age, gender, smoking habits, lipoprotein disturbances, the presence of lipodystrophy (fat loss or accumulation perceived by the patient or the clinician) or HCV co-infection, inflammation and insulin resistance (Table 2).

Table 2. Baseline participants’ clinical and laboratory characteristics blindly collated from medical records at the end of the study

Arguably, a 2-year follow-up might not be sufficient to evaluate the full effect of the variables. A longer follow-up to ascertain the role of host-related, genetically determined variants, however, is not feasible because the progression of carotid atherosclerosis in these patients is faster than in non-infected patients, and the evaluation of non-classical factors requires shorter periods [19,20]. We have previously demonstrated non-concordance between subclinical atherosclerosis and the calculated Framingham risk score in HIV-infected patients [31]. However, the issue of non-concordance is under debate and in a recent study, increased Framingham risk scores were associated with abnormal early and late surrogate markers of atherosclerosis. However, low scores were also associated with significant subclinical atherosclerosis in these patients [32].

Despite the identification of several trends (Table 3), the distribution of selected chemokine-related genetic variants did not demonstrate significant differences between the progressors and non-progressors. Next, we measured the mRNA expression of chemokine receptors involved in HIV entry into leukocytes. The chemokine receptors were selected according to available data implicating these receptors in the course of atherosclerosis. Interestingly, we observed that the variant CCR5 Δ32 was responsible for the increased expression of these receptors, but only CCR2 and CCR5 reached statistical significance (Figure 1). Patients who expressed the CCR2 V62I gene variant also demonstrated a two-fold higher expression (p = 0.004) of CCR5 compared with non-carriers (data not shown). The expression of chemokine receptors, especially CCR5, did not correlate with increases in IMT. However, CX3CR1 expression demonstrated a marginal effect (ρ = 0.21, P = 0.053). The lack of significant correlations does not discard a quantitative relationship because the influence of high variability and the absence of normal distribution may mask the association between continuous variables.

thumbnailFigure 1. The presence of the CCR-5 Δ32 polymorphism in HIV-infected patients was associated with a significant increase in the expression of CCR2 and CCR5 in circulating leukocytes with respect to patients without the mutation. Similarly, the CCR2 V62I was also associated with a similarly higher CCR5 expression (data not shown).

Table 3. Allelic frequency for selected polymorphisms as segregated according to the progression in IMT measurements during a two-year period

We observed that the expression of CCR2 and CXCR4 did not discriminate between progressors and non-progressors, and the expression of CCR5 and CX3CR1 was significantly higher in the progressors (Figure 2). These results are plausible because the data obtained in humans and animal models indicate that CCR5 is crucial for monocyte recruitment, and CX3CR1 appears to sustain chronic monocyte adhesion and survival within the plaque in diseased arteries during atherosclerosis development [33,34]. Because the increase in CCR5 and CX3CR1 expression was higher in not only progressors but also the patients with detectable viral load, our data might support a role for the virus in determining the rapid development of atherosclerosis [35,36]. No differences were found in CXCR4; however, the expression of CCR2 was 3-fold higher in patients with a detectable viral load (p = 0.007), an effect that was considered independent of the condition of either progressors or non-progressors (Figure 3). Therefore, further studies will be needed to ascertain a relationship between relatively poor management of the infection and the development of vascular lesions. This interpretation is substantiated by the observation that a number of chemokines block or delay viral entry by interfering with HIV co-receptors [37]. There are multiple plausible mechanisms underlying the interference between the retroviral life cycle and chemokines. First, endothelial cells line the entire cardiovascular system and are frequently in contact with memory CD4+ T cells, which provide signals to HIV-1-infected CD4+ T cells to enhance HIV-1 production, an effect that persists despite antiretroviral therapy [36]. Second, infiltrating HIV-infected monocytes/macrophages promote proinflammatory effects per se. This process is important because HIV itself can infect vascular smooth muscle cells via a mechanism dependent on chemokine receptors, and this may partially explain the exacerbated atherosclerosis reported in infected individuals [37].

thumbnailFigure 2. The expression of CCR2 and CXCR4 in circulating leukocytes from progressors and non-progressors was similar but there were a significant increase in CCR5 and CX3CR1 in patients who showed progression in intima-media thickness.

thumbnailFigure 3. Detectable viral load (VL) was also a determinant factor in the rate of expression of chemokine receptors with the exception of CXCR4. The expression of CCR2 was higher in patients with detectable viral load but this difference was not related to the progression of atherosclerosis. Conversely, the increase in CCR5 and CX3CR1 expression was not only higher in progressors but also in those with detectable viral load.

The course of HIV infection, however, may also be associated with other factors, such as body mass index (BMI), high-density lipoproteins (HDLs) or reverse cholesterol transport from macrophages, the amount of circulating oxidised low-density lipoproteins (LDL-ox) and the number of CD8+ T cells in the blood [38-40]. We investigated this possibility and determined that when the values of these variables were divided into tertiles, a qualitatively similar effect on the expression of CCR5 and CX3CR1 was observed (Figure 4). The expression of both receptors was higher in patients with the highest BMI, LDL-ox and CD8+ T cells. Additionally, patients with the lowest value for HDL cholesterol demonstrated a higher increase in CCR5 and CX3CR1 expression. These findings support the hypothesis that several modifiable factors cannot be excluded in the assessment of a possible association between the course of accelerated atherosclerosis and the course of HIV infection [31-33,41-43]. Univariate analyses suggested that these assumptions were correct, and multivariate logistic regression analyses determined that the dichotomous model was explained by only a small number of variables (Table 4). Logistic regression was used rather than discriminant function analysis to include predictors lacking normal distribution, and all predictors were used to determine group membership according to outcome (progressors and non-progressors).

thumbnailFigure 4. Chemokine receptors and selected variables. The expression of CCR5 (A) and CX3CR1 (B) are affected by modifiable factors and increased in patients with the highest values of body mass index, the concentration of oxidized LDL-ox, and the number of circulating CD8+ T cells and the lowest value for HDL-cholesterol. The cutoff values for the first and second tertiles were respectively: BMI, 20.1 and 23.3; HDL-cholesterol, 0.84 and 1.11 mmol/L; ox-LDL, 51.1 and 80.2 ng/mL, and CD8, 592 and 920 cells/mm3.

Table 4. Significant predictor variables found in multivariate logistic regression stepwise analysis used for the binary outcome (progressors and non-progressors) with respect to subclinical atherosclerosis

Generally, we found that CCR5 expression is the best predictor of progression in atherosclerosis and that a number of host gene variants may have a significant effect. Although CCR2 and CX3CR1 are predisposing factors in atherosclerosis and inflammation [41,42], we also determined that under these conditions, the effects of the expression of these receptors appeared negligible. This is not surprising because the expression of chemokines in different tissues can change in response to multiple stimuli [44].

The predominant role of CCR5 expression in circulating leukocytes in HIV-infected patients as a predictive factor for the rate of progression of atherosclerosis suggests that drugs affecting chemokines should be investigated for their role not only as protective agents in HIV-infection but also in atherosclerosis-related complications. This suggestion is in accordance with the observation that a number of experimental drugs that inhibit HIV entry can arrest the progression of atheroma plaques in animal models [45-47] and that CCR5 antagonists can affect cardiovascular risk factors [48,49]. Therefore, we propose that available CCR5 antagonists that have been clinically validated should be considered as not only antiviral drugs but also potentially useful agents for the management of inflammation-related diseases.

Possible limitations of the study

Biases are particularly difficult to avoid in studies with these characteristics. However, in this study, recall bias and detection bias were essentially excluded from the design. We also excluded the possibility that the increase in the IMT measurement was sensitive to small, unmeasured confounders (hidden biases) because the patients were examined at least 8 times during the study according to a strict clinical protocol for the detection of the outcome and related variables. Additionally, covariate adjustment using propensity score analyses demonstrated good performance, with scores reflecting a low probability that the participant’s baseline characteristics played a role in the increase in IMT. Finally, we appreciate that the length of the follow-up may be important and should be considered carefully when replicating our findings.

Competing interests

The authors declare that they have no competing interests and have no conflict of interest to declare.

Authors’ contributions

All authors have contributed to the acquisition, analysis and interpretation of data and have been involved in drafting and revising the manuscript. The design was initially conceived by C A-V, L F-S and JJ. All authors have given final approval of the version to be published and may take public responsibility of the content.

Acknowledgements

The funding source and granting support played no role in the study design; in the collection, analysis and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication. The Unitat de Recerca Biomèdica is financially supported by the Instituto de Salud Carlos III (Ministerio de Sanidad y Consumo y Fondo de Investigación Sanitaria) through competitive grants PI11/00130, PI11/02187, PI08/01381 and PI08/01175.

References

  1. Alonso-Villaverde C, Coll B, Parra S, Montero M, Calvo N, Tous M, Joven J, Masana L: Atherosclerosis in patients infected with HIV is influenced by a mutant monocyte chemoattractant protein-1 allele.

    Circulation 2004, 110:2204-9. PubMed Abstract | Publisher Full Text OpenURL

  2. Önen NF, Overton ET: A review of premature frailty in HIV-infected persons; another manifestation of HIV-related accelerated aging.

    Curr Aging Sci 2011, 4:33-41. PubMed Abstract | Publisher Full Text OpenURL

  3. Piggott DA, Muzaale AD, Mehta SH, Brown TT, Patel KV, Leng SX, Kirk GD: Frailty, HIV Infection, and Mortality in an Aging Cohort of Injection Drug Users.

    PLoS One 2013, 8(1):e54910. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  4. Renga B, Francisci D, D’Amore C, Schiaroli E, Mencarelli A, Cipriani S, Baldelli F, Fiorucci S: The HIV Matrix Protein p17 Subverts Nuclear Receptors Expression and Induces a STAT1-Dependent Proinflammatory Phenotype in Monocytes.

    PLoS One 2012, 7(4):e35924. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  5. Coll B, Alonso-Villaverde C, Joven J: Monocyte chemoattractant protein-1 and atherosclerosis: is there room for an additional biomarker?

    Clin Chim Acta 2007, 383:21-9. PubMed Abstract | Publisher Full Text OpenURL

  6. Coll B, Parra S, Alonso-Villaverde C, Aragonés G, Montero M, Camps J, Joven J, Masana L: The role of immunity and inflammation in the progression of atherosclerosis in patients with HIV infection.

    Stroke 2007, 38:2477-84. PubMed Abstract | Publisher Full Text OpenURL

  7. Koenen RR, Weber C: Chemokines: established and novel targets in atherosclerosis.

    EMBO Mol Med 2011, 3:713-25. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  8. Kanzler I, Liehn EA, Koenen RR, Weber C: Anti-inflammatory therapeutic approaches to reduce acute atherosclerotic complications.

    Curr Pharm Biotechnol 2012, 13(1):37-45. PubMed Abstract | Publisher Full Text OpenURL

  9. Sullivan TJ, Dairaghi DJ, Krasinski A, Miao Z, Wang Y, Zhao BN, Baumgart T, Berahovich R, Ertl LS, Pennell A, Seitz L, Miao S, Ungashe S, Wei Z, Johnson D, Boring L, Tsou CL, Charo IF, Bekker P, Schall TJ, Jaen JC: Characterization of CCX140-B, an orally bioavailable antagonist of the CCR2 chemokine receptor, for the treatment of type 2 diabetes and associated complications.

    J Pharmacol Exp Ther 2012. Publisher Full Text OpenURL

  10. Yadav A, Saini V, Arora S: MCP-1: chemoattractant with a role beyond immunity: a review.

    Clin Chim Acta 2010, 411:1570-9. PubMed Abstract | Publisher Full Text OpenURL

  11. Jones KL, Maguire JJ, Davenport AP: Chemokine receptor CCR5: from AIDS to atherosclerosis.

    Br J Pharmacol 2011, 162:1453-69. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  12. Samson M, Libert F, Doranz BJ, Rucker J, Liesnard C, Farber CM, Saragosti S, Lapoumeroulie C, Cognaux J, Forceille C, Muyldermans G, Verhofstede C, Burtonboy G, Georges M, Imai T, Rana S, Yi Y, Smyth RJ, Collman RG, Doms RW, Vassart G, Parmentier M: Resistance to HIV-1 infection in Caucasian individuals bearing mutant alleles of the CCR-5 chemokine receptor gene.

    Nature 1996, 382:722-25. PubMed Abstract | Publisher Full Text OpenURL

  13. Afzal AR, Kiechl S, Daryani YP, Weerasinghe A, Zhang Y, Reindl M, Mayr A, Weger S, Xu Q, Willeit J: Common CCR5-del32 frameshift mutation associated with serum levels of inflammatory markers and cardiovascular disease risk in the Bruneck population.

    Stroke 2008, 39:1972-8. PubMed Abstract | Publisher Full Text OpenURL

  14. Dorr P, Westby M, Dobbs S, Griffin P, Irvine B, Macartney M, Mori J, Rickett G, Smith-Burchnell C, Napier C, Webster R, Armour D, Price D, Stammen B, Wood A, Perros M: Maraviroc (UK-427,857), a potent, orally bioavailable, and selective small-molecule inhibitor of chemokine receptor CCR5 with broad-spectrum anti-human immunodeficiency virus type 1 activity.

    Antimicrob Agents Chemother 2005, 49:4721-32. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  15. Parra J, Portilla J, Pulido F, Alonso-Villaverde C, Berenguer J, Blanco JL, Domingo P, Dronda F, Galera C, Gutiérrez F, Kindelán JM, Knobel H, Leal M, López-Aldeguer J, Mariño A, Miralles C, Moltó J, Ortega E, Oteo JA, Sánchez-de la Rosa R: Clinical utility of maraviroc.

    Clin Drug Investig 2011, 31:527-542. PubMed Abstract | Publisher Full Text OpenURL

  16. Umehara H, Bloom ET, Okazaki T, Nagano Y, Yoshie O, Imai T: Fractalkine in vascular biology: from basic research to clinical disease.

    Arterioscler Thromb Vasc Biol 2004, 24:34-40. PubMed Abstract | Publisher Full Text OpenURL

  17. Mc Dermott DH, Halcox JPJ, Schenke WH, Waclawiw MA, Merrell MN, Epstein N, Quyyumi AA, Murphy PM: Association between polymorphism in the chemokine receptor CX3CR1 and coronary vascular endothelial dysfunction and atherosclerosis.

    Circ Res 2001, 89:401-7. PubMed Abstract | Publisher Full Text OpenURL

  18. Pineda JA, González J, Ortega E, Tural C, Macías J, Griffa L, Burgos A, Grafihco Study Team: Prevalence and factors associated with significant liver fibrosis assessed by transient elastometry in HIV/hepatitis C virus-coinfected patients.

    J Viral Hepat 2010, 17:714-9. PubMed Abstract | Publisher Full Text OpenURL

  19. Mangili A, Polak JF, Skinner SC, Gerrior J, Sheehan H, Harrington A, Wanke CA: HIV infection and progression of carotid and coronary atherosclerosis: the CARE study.

    J Acquir Immune Defic Syndr 2011, 58(2):148-53. PubMed Abstract | Publisher Full Text OpenURL

  20. Papasavvas E, Hsue P, Reynolds G, Pistilli M, Hancock A, Martin JN, Deeks SG, Montaner LJ: Increased CD34(+)/KDR(+) cells are not associated with carotid artery intima-media thickness progression in chronic HIV-positive subjects.

    Antivir Ther 2012, 17(3):557-63. PubMed Abstract | PubMed Central Full Text OpenURL

  21. Martinez E, Mocroft A, García-Viejo MA, Perez-Cuevas JB, Blanco JL, Mallolas J, Bianchi L, Conget I, Blanch J, Phillips A, Gatell JM: Risk of lipodystrophy in HIV-1-infected patients treated with protease inhibitors: a prospective cohort study.

    Lancet 2001, 357:592-8. PubMed Abstract | Publisher Full Text OpenURL

  22. Simó JM, Castellano I, Ferré N, Joven J, Camps J: Evaluation of a homogeneous assay for high-density lipoprotein cholesterol: limitations in patients with cardiovascular, renal, and hepatic disorders.

    Clin Chem 1998, 44:1233-41. PubMed Abstract | Publisher Full Text OpenURL

  23. Faaij CM, Willemze AJ, Révész T, Balzarolo M, Tensen CP, Hoogeboom M, Vermeer MH, van Wering E, Zwaan CM, Kaspers GJ, Story C, van Halteren AG, Vossen JM, Egeler RM, van Tol MJ, Annels NE: Chemokine/chemokine receptor interactions in extramedullary leukaemia of the skin in childhood AML: differential roles for CCR2, CCR5, CXCR4 and CXCR7.

    Pediatr Blood Cancer 2010, 55(2):344-8. PubMed Abstract | Publisher Full Text OpenURL

  24. Alonso-Villaverde C, Aragonès G, Beltrán-Debón R, Fernández-Sender L, Rull A, Rodríguez-Sanabria F, Marsillach J, Pardo-Reche P, Camps J, Joven J: Host-pathogen interactions in the development of metabolic disturbances and atherosclerosis in HIV infection: the role of CCL2 genetic variants.

    Cytokine 2010, 51:251-8. PubMed Abstract | Publisher Full Text OpenURL

  25. Alonso-Villaverde C, Aragonès G, Beltrán-Debón R, Fernández-Sender L, Rull A, Camps J, Alegret JM, Joven J: Treatment of hypertriglyceridemia and HIV: fenofibrate-induced changes in the expression of chemokine genes in circulating leukocytes.

    AIDS Res Ther 2009, 6:26. PubMed Abstract | BioMed Central Full Text | PubMed Central Full Text OpenURL

  26. Mackness B, Beltran-Debon R, Aragones G, Joven J, Camps J, Mackness M: Human tissue distribution of paraoxonases 1 and 2 mRNA.

    IUBMB Life 2010, 62(6):480-2. PubMed Abstract | Publisher Full Text OpenURL

  27. Kang SJ, Gordon D, Finch SJ: What SNP genotyping errors are most costly for genetic association studies?

    Genet Epidemiol 2004, 26:132-41. PubMed Abstract | Publisher Full Text OpenURL

  28. Normand SL, Sykora K, Li P, Mamdani M, Rochon PA, Anderson GM: Readers guide to critical appraisal of cohort studies: 3.

    Analytical strategies to reduce confounding. BMJ 2005, 330(7498):1021-3. OpenURL

  29. Weitzen S, Lapane KL, Toledano AY, Hume AL, Mor V: Principles for modeling propensity scores in medical research: a systematic literature review.

    Pharmacoepidemiol Drug Saf 2004, 13(12):841-53. PubMed Abstract | Publisher Full Text OpenURL

  30. Shah BR, Laupacis A, Hux JE, Austin PC: Propensity score methods gave similar results to traditional regression modeling in observational studies: a systematic review.

    J Clin Epidemiol 2005, 58(6):550-9. PubMed Abstract | Publisher Full Text OpenURL

  31. Parra S, Coll B, Aragonés G, Marsillach J, Beltrán R, Rull A, Joven J, Alonso-Villaverde C, Camps J: Nonconcordance between subclinical atherosclerosis and the calculated Framingham risk score in HIV-infected patients: relationships with serum markers of oxidation and inflammation.

    HIV Med 2010, 11(4):225-31. PubMed Abstract | Publisher Full Text OpenURL

  32. Falcone EL, Mangili A, Skinner S, Alam A, Polak JF, Wanke CA: Framingham risk score and early markers of atherosclerosis in a cohort of adults infected with HIV.

    Antivir Ther 2011, 16(1):1-8. PubMed Abstract | Publisher Full Text OpenURL

  33. Zernecke A, Shagdarsuren E, Weber C: Chemokines in atherosclerosis: an update.

    Arterioscler Thromb Vasc Biol 2008, 28(11):1897-908. PubMed Abstract | Publisher Full Text OpenURL

  34. Gautier EL, Jakubzick C, Randolph GJ: Regulation of the migration and survival of monocyte subsets by chemokine receptors and its relevance to atherosclerosis.

    Arterioscler Thromb Vasc Biol 2009, 29(10):1412-8. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  35. Vicenzi E, Biswas P, Mengozzi M, Poli G: Role of pro-inflammatory cytokines and beta-chemokines in controlling HIV replication.

    J Leukoc Biol 1997, 62(1):34-40. PubMed Abstract | Publisher Full Text OpenURL

  36. Choi J, Walker J, Talbert-Slagle K, Wright P, Pober JS, Alexander L: Endothelial cells promote human immunodeficiency virus replication in nondividing memory T cells via Nef-, Vpr-, and T-cell receptor-dependent activation of NFAT.

    J Virol 2005, 79(17):11194-204. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  37. Eugenin EA, Morgello S, Klotman ME, Mosoian A, Lento PA, Berman JW, Schecter AD: Human immunodeficiency virus (HIV) infects human arterial smooth muscle cells in vivo and in vitro: implications for the pathogenesis of HIV-mediated vascular disease.

    Am J Pathol 2008, 172(4):1100-11. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  38. Rose H, Hoy J, Woolley I, Tchoua U, Bukrinsky M, Dart A, Sviridov D: HIV-infection and high density lipoprotein metabolism.

    Atherosclerosis 2008, 199(1):79-86. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  39. Mujawar Z, Rose H, Morrow MP, Pushkarsky T, Dubrovsky L, Mukhamedova N, Fu Y, Dart A, Orenstein JM, Bobryshev YV, Bukrinsky M, Sviridov D: Human immunodeficiency virus impairs reverse cholesterol transport from macrophages.

    PLoS Biol 2006, 4(11):e365. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  40. Aragonès G, García-Heredia A, Guardiola M, Rull A, Beltrán-Debón R, Marsillach J, Alonso-Villaverde C, Mackness B, Mackness M, Pedro-Botet J, Pardo-Reche P, Joven J, Camps J: Serum paraoxonase-3 concentration in HIV-infected patients.

    Evidence for a protective role against oxidation. J Lipid Res 2012, 53(1):168-74. OpenURL

  41. Postea O, Vasina EM, Cauwenberghs S, Projahn D, Liehn EA, Lievens D, Theelen W, Kramp BK, Butoi ED, Soehnlein O, Heemskerk JW, Ludwig A, Weber C, Koenen RR: Contribution of platelet CX(3)CR1 to platelet-monocyte complex formation and vascular recruitment during hyperlipidemia.

    Arterioscler Thromb Vasc Biol 2012, 32(5):1186-93. PubMed Abstract | Publisher Full Text OpenURL

  42. Suresh P, Wanchu A: Chemokines and chemokine receptors in HIV infection: role in pathogenesis and therapeutics.

    J Postgrad Med 2006, 52(3):210-7. PubMed Abstract | Publisher Full Text OpenURL

  43. Paul A, Calleja L, Camps J, Osada J, Vilella E, Ferré N, Mayayo E, Joven J: The continuous administration of aspirin attenuates atherosclerosis in apolipoprotein E-deficient mice.

    Life Sci 2000, 68(4):457-65. PubMed Abstract | Publisher Full Text OpenURL

  44. Tous M, Ferré N, Rull A, Marsillach J, Coll B, Alonso-Villaverde C, Camps J, Joven J: Dietary cholesterol and differential monocyte chemoattractant protein-1 gene expression in aorta and liver of apo E-deficient mice.

    Biochem Biophys Res Commun 2006, 340(4):1078-84. PubMed Abstract | Publisher Full Text OpenURL

  45. van Wanrooij EJ, Happé H, Hauer AD, de Vos P, Imanishi T, Fujiwara H, van Berkel TJ, Kuiper J: HIV entry inhibitor TAK-779 attenuates atherogenesis in low-density lipoprotein receptor-deficient mice.

    Arterioscler Thromb Vasc Biol 2005, 25(12):2642-7. PubMed Abstract | Publisher Full Text OpenURL

  46. Feng Y, Broder CC, Kennedy PE, Berger EA: HIV-1 entry cofactor: functional cDNA cloning of a seven-transmembrane, G protein-coupled receptor.

    Science 1996, 272:872-6. PubMed Abstract | Publisher Full Text OpenURL

  47. Wilen CB, Tilton JC, Doms RW: Molecular Mechanisms of HIV Entry.

    Adv Exp Med Biol 2012, 726:223-42. PubMed Abstract | Publisher Full Text OpenURL

  48. Funderburg N, Kalinowska M, Eason J, Goodrich J, Heera J, Mayer H, Rajicic N, Valdez H, Lederman MM: Effects of maraviroc and efavirenz on markers of immune activation and inflammation and associations with CD4+ cell rises in HIV-infected patients.

    PLoS One 2010, 5(10):e13188. PubMed Abstract | Publisher Full Text | PubMed Central Full Text OpenURL

  49. Aukrust P, Yndestad A, Smith C, Ueland T, Gullestad L, Damås JK: Chemokines in cardiovascular risk prediction.

    Thromb Haemost 2007, 97:748-54. PubMed Abstract | Publisher Full Text OpenURL