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Infection duration and inflammatory imbalance are associated with atherosclerotic risk in HIV-infected never-smokers independent of antiretroviral therapy

Desvarieux, Moïsea,b; Boccara, Franckc,d,g; Meynard, Jean-Lucd,e; Bastard, Jean-Philliped,f,g; Mallat, Ziadh,j; Charbit, Benyi; Demmer, Ryan T.a; Haddour, Nabilac,d; Fellahi, Sorayad,f,g; Tedgui, Alainh; Cohen, Arielc,d; Capeau, Jacquelined,f,g; Boyd, Andersk; Girard, Pierre-Maried,e,k

doi: 10.1097/QAD.0b013e3283634819
Epidemiology and Social
Free
SDC

Objectives: To determine whether the reported increased atherosclerotic risk among HIV-infected individuals is related to antiretroviral therapy (ART) or HIV infection, whether this risk persists in never-smokers, and whether inflammatory profiles are associated with higher risk.

Design: Matched cross-sectional study.

Methods: A total of 100 HIV-infected patients (50 ART-treated >4 years, 50 ART-naive but HIV-infected >2 years) and 50 HIV-negative controls were recruited in age-matched never-smoking male triads (mean age 40.2 years). Carotid intima–media maximal thickness (c-IMT) was measured across 12 sites. Pro-inflammatory [highly sensitive C-reactive protein (hs-CRP), resistin, interleukin-6, interleukin-18, insulin, serum amyloid A, D-dimer) and anti-inflammatory (total and high molecular weight adiponectin, interleukin-27, interleukin-10) markers were dichotomized into high/low scores (based on median values). c-IMT was compared across HIV/treatment groups or inflammatory profiles using linear regression models adjusted for age, diabetes, hypertension, and, for HIV-infected patients, nadir CD4+ cell counts.

Results: Although adjusted c-IMT initially tended to be thicker in ART-exposed patients (P = 0.2), in post-hoc analyses stratifying by median HIV duration we observed significantly higher adjusted c-IMT in patients with longer (>7.9 years: 0.760 ± 0.008 mm) versus shorter prevalent duration of known HIV infection (<7.9 years: 0.731 ± 0.008 mm, P = 0.02), which remained significant after additionally adjusting for ART (P = 0.04). Individuals with low anti-inflammatory profile (<median versus >median score) had thicker c-IMT (0.754 ± 0.006 mm versus 0.722 ± 0.006 mm, P < 0.001), with anti-inflammatory markers declining as prevalent duration of HIV infection increased (P for linear trend <0.001).

Conclusion: Known HIV duration is related to thicker c-IMT, irrespective of ART, in these carefully selected age-matched never-smoking HIV-treated and ART-naive male individuals. Higher levels of anti-inflammatory markers appeared protective for atherosclerosis.

Supplemental Digital Content is available in the text

aDepartment of Epidemiology, Columbia University, Mailman School of Public Health, New York, USA

bInserm U-738 and École des Hautes Études en Santé Publique

cAP-HP Department of Cardiology, Hôpital Saint-Antoine, F-75012, Paris, France

dUPMC Univ Paris 06, Paris F75012

eAPHP Department of Infectious and Tropical Diseases, Hôpital Saint-Antoine

fAPHP Hôpital Tenon, Service de biochimie et hormonologie, Paris F75020

gInserm UMR_S938, Paris F-75012

hInserm U970, Paris-Cardiovascular Research Center, and Paris-Descartes University

iAP-HP Centre d’Investigation Clinique Paris-EST (9304), Hôpital Pitié-Salpêtrière, Paris, France

jDepartment of Medicine, University of Cambridge, Cambridge, UK

kInserm UMR-S707, Paris, France.

Correspondence to Moïse Desvarieux, MD, PhD, Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 W168th Street, Suite 525, New York, NY 10032, USA. Tel: +1 212 305 5172; fax: +1 212 342 2756; e-mail: mdesvarieux@columbia.edu;moise.desvarieux@ehesp.fr

Received 13 January, 2013

Revised 3 May, 2013

Accepted 15 May, 2013

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (http://www.AIDSonline.com).

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Introduction

A growing body of literature reports that patients infected with HIV suffer from an elevated risk for both subclinical atherosclerotic disease [1–3] and cardiovascular disease (CVD) events [4,5]. However, it remains unresolved to what extent HIV infection or combined antiretroviral therapy (ART) is involved in increasing this cardiovascular risk, and to what extent this increased risk is mediated by traditional cardiovascular risk factors. Chief among these is smoking, with prevalence levels known to be high (>50%) in HIV-infected patients [6,7]. The persistence of the relationship in the hard-to-obtain population of never-smokers would significantly bolster the hypothesis of an independent additional risk.

As atherosclerosis is an inflammatory disease [8], either infection or immuno-modulatory therapies, such as ART, may directly accelerate subclinical atherosclerosis via heightened or imbalanced immune/inflammatory response: increased levels of systemic pro-inflammatory markers [9,10] and, conversely, decreased levels of the anti-inflammatory insulin-sensitizing hormone, adiponectin, acting on the vascular wall [11] have been reported in HIV-infected individuals. However, although a number of studies have looked at specific inflammatory or immune markers, no study has specifically looked at immune/inflammatory response imbalance as a possible mechanism to this increased CVD risk; and no study has done so in the context of never-smokers.

The Collaboration on HIV, Inflammation and Cardiovascular Disease study was designed to determine whether the increased risk in subclinical atherosclerosis observed in HIV-infected patients exists independent of smoking; whether this increased risk correlated with HIV infection or ART; and whether the evaluation of pro-inflammatory/anti-inflammatory balance could illuminate the underlying subclinical mechanisms.

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Methods

Patients and study design

Between March 2008 and June 2009, 50 triads (n = 150 individuals) of never-smoking (defined as <100 cigarettes/lifetime) male individuals were enrolled in three groups: an index group of 50 HIV-infected patients older than 35 years; undergoing ART, defined as a combination of at least three antiretroviral drugs, for 4 years at least; and with HIV-1 viral load lower than 400 copies/ml; a second group of individually age-matched (±5 years) individuals, HIV-infected for 2 years at least, ART-naive and not meeting the indication for ART-initiation; and a third group of serology-confirmed, HIV-negative individuals individually age-matched (±5 years) to the index patient. HIV-negative individuals were recruited following advertisement published in a free local newspaper. HIV infections were western blot confirmed and a Karnofski score higher than 80 was required. All patients provided written informed consent and the protocol was approved by the Hôtel-Dieu Hospital Ethics Committee (Paris, France).

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Exclusion criteria

Participants were excluded for any of the following: current or former smokers (>100 cigarettes/lifetime); history of coronary disease or stroke; active/chronic viral hepatitis [confirmed by positive serological hepatitis B surface antigen and/or detectable hepatitis C virus RNA (>615 international unit/ml)]; requiring systemic steroids, chemotherapy, or radiotherapy; undergoing interferon or antiviral therapy for hepatitis; HIV-2 infection; or no social security affiliation.

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Cardiovascular risk factor assessment

Standardized questions on sociodemographics/cardiovascular risk factors adapted from the Behavioral Risk Factor Surveillance System [12], the Enquête sur la Santé et la Protection Sociale [13], and the Enquête Sociale et de Santé [14] were filled out by group-blinded research assistants. Hypertension was defined by prior physician diagnosis or SBP at least 140 mmHg or diastolic at least 90 mmHg, measured twice at study visit or treatment for hypertension. Diabetes mellitus was defined by a history of diagnosed diabetes, the use of insulin/hypoglycemic medication, or a fasting glucose higher than 126 mg/dl (7.0 mmol/l).

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HIV-related assessment

A complete history of ART was obtained by the treating physician and verified using medical records. Prevalent duration of known HIV infection was the time since first positive anti-HIV serology. CD4+/CD8+ cell counts were quantified using standard flow cytometry at study entry. Nadir CD4+ cell counts, performed in the same laboratory, were obtained from medical records.

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Assessment of carotid intima–media thickness

IMT scanning utilized the Oral Infections and Vascular Disease Epidemiology Study protocol [15]. Carotid intima–media thickness (c-IMT) in the common, internal carotids and bifurcation [15] was measured bilaterally outside of plaque (defined as a focal widening relative to adjacent segments (>50% of the adjacent IMT or IMT > 1.5 mm), using the GE Vivid 7 System (GPS Medical, Inc, Indianapolis, Indianapolis, USA) and a 10-MHz probe by an experienced vascular physician blinded to the groups.

c-IMT measurements were performed offline with IMT quality intima–media thickness automatic measurement software. Total c-IMT was calculated as a composite measure (mean of the 12 sites) combining near and far walls of the maximal/means carotid common artery IMT, bifurcation IMT and internal carotid artery IMT bilaterally.

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Metabolic measurements

Individuals were fasting (12 h) at visit. Glucose and lipid levels were measured using routine methods, with low-density lipoprotein (LDL) measured by direct precipitation. Insulin was measured by a specific insulin assay without proinsulin cross-reactivity (ARCHITECT Analyzer; Abbott laboratories, Abbott Park, Illinois, USA). Insulin resistance was assessed using the Quantitative Insulin Sensitivity Check Index (QUICKI) calculated as 1/[log(fasting insulinμU/ml) + log(mg/dl)].

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Inflammatory response profiles

We selected, in advance, the following markers for assessing immune/inflammatory balance because they are either considered involved in the pro-inflammatory and insulin-resistant profile [highly sensitive C-reactive protein (hs-CRP), resistin, interleukin-6, interleukin-18, insulin, serum amyloid A (SAA), D-dimer] or conversely with anti-inflammatory and insulin-sensitizing properties [total and high molecular weight (HMW) adiponectin, interleukin-27, interleukin-10].

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Pro-inflammatory markers

Serum interleukin-6 and serum interleukin-18 were analyzed using ELISA (Quantikine; R&D Systems, Minneapolis, Minnesota, USA) as was resistin (Bender Medsystems, Burlingame, California, USA). Serum hs-CRP and SAA were measured by immononephelometry on an IMMAGE Analyzer (Beckman-Coulter, Miami, Florida, USA). Plasma D-dimer was measured by enzyme linked fluorescent assay on a VIDAS Analyzer (Biomérieux, Durhum, North Carolina, USA).

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Anti-inflammatory markers

Serum interleukin-10 and serum interleukin-27 were quantified by ultrasensitive ELISA (Bender Medsystems). Total and HMW adiponectin levels were determined by ELISA (Bühlman, Düsseldorf, Germany). All inflammatory markers were quantified at the Biochemistry Department of Tenon Hospital and at George Pompidou Hospital.

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Statistical analysis

The study was powered to detect a 0.06-mm or greater difference in c-IMT between any of the three groups with a type 1 error at 0.05 and with 77% power. We based this number from previous research demonstrating c-IMT values between 0.68 and 0.71 mm with a 0.13-mm standard deviation (SD) in HIV-infected individuals, but reduced and less variable values among HIV-negative patients. The number of individuals was thus calculated at 50 per group.

For each inflammatory marker, values were natural-log-transformed and standardized by subtracting individual-level observations from the population mean, then dividing by the population SD. As a result, 1 SD on the natural-log scale was equivalent across inflammatory markers. Natural-log-standardized pro-inflammatory and anti-inflammatory values were summed for each individual creating pro-inflammatory and anti-inflammatory scores, which were then dichotomized into high/low scores (based on median values), creating four possible combinations of pro-inflammation/anti-inflammation profiles: low/low, low/high, high/low, and high/high.

Average c-IMT was compared across groups or inflammatory profiles using three linear regression models. We first adjusted on factors significantly associated with c-IMT in univariate analysis, that is, age, diabetes, and hypertension. Further models included nadir CD4+ cell count; and excluded one elite HIV-controller patient (HIV-RNA viral load < 50 copies/ml, without ART for 4 consecutive years). Post-hoc analyses stratified individuals by median prevalent duration of known HIV infection, reconstituting groups with longer (>7.9 years) and shorter (<7.9 years) infection duration, to elucidate the intertwined roles of prevalent duration of HIV infection versus duration of ART.

All statistical analyses were performed using STATA (v10.0, College Station, Texas, USA) and a P-value <0.05 was considered significant. P-values were not adjusted for multiple comparisons as the use of scores significantly alleviated multiple exposures testing and our endpoints were limited [16,17].

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Results

Demographics and HIV-related characteristics of the three groups are in Table 1. Briefly, among treated patients, HIV infection was well controlled: 47 patients (94.0%) with HIV viral load lower than 40 copies/ml and treated HIV-infected patients had significantly longer prevalent duration of HIV infection than nontreated patients. Population characteristics stratified by median HIV-infection duration can be found in Supplementary Table 1, http://links.lww.com/QAD/A368.

Table 1-a

Table 1-a

Table 1-b

Table 1-b

The distributions of metabolic parameters and pro-inflammatory and anti-inflammatory markers are in Table 1. Overall, a low number of patients had abnormal levels of high-density lipoprotein (HDL) (28.7%, <1.0 mmol/l), LDL (12.0%, >4.1 mmol/l), fasting glucose (1.3%, >6.1 mmol/l), insulin (17.3%, >10 mU/l), or homeostatic model assessment of insulin resistance score (10.7%, >3.0). Both treated and untreated HIV-infected patients had higher proportion with hs-CRP higher than 3.0 mg/l (43.2 and 38.7%, respectively) compared to HIV-negative controls (22.8%), after adjusting for age, diabetes, and hypertension. When further stratifying by median prevalent duration of known HIV infection (Supplementary Table 1, http://links.lww.com/QAD/A368), some significant differences were found in adjusted median triglycerides, LDL, interleukin-6, interleukin-18, HMW adiponectin, and interleukin-10. After adjusting for age, diabetes, and hypertension, waist-to-hip ratio and BMI were significantly correlated with insulin (r = 0.282, r = 0.454); QUICKI (r = −0.285, r = −0.437); total adiponectin (r = −0.316, r = −0.220); and HMW adiponectin (r = −0.257, r = −0.244) as expected.

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Relation between carotid intima–media thickness, HIV infection, and antiretroviral therapy

c-IMT values were significantly different in treated HIV-infected patients compared to untreated HIV-infected and HIV-negative individuals after adjusting for age, hypertension, and diabetes (Table 2a). Treated HIV-infected patients were further stratified on protease inhibitor use using the same adjustments, while showing no statistical difference in c-IMT (P = 0.6). As the initial trend could conceivably be explained by the severity of HIV infection, we additionally adjusted for nadir CD4+ cell count and found no significant difference between treated and untreated HIV-infected groups (Table 2a).

Table 2

Table 2

However, in a post-hoc analysis, we observed higher c-IMT in patients with longer (0.760 ± 0.008 mm) versus shorter HIV infection (0.731 ± 0.008 mm) in the fully adjusted model (Table 2b), remaining so after additionally adding ART (0.759 ± 0.009 and 0.731 ± 0.009, respectively, P = 0.04). In Supplementary Table 2, http://links.lww.com/QAD/A368, we aimed to further clarify the impact of prevalent duration of known HIV infection: after stratifying HIV-infected groups on both treatment status and median prevalent duration of HIV infection (7.9 years), adjusted mean [±standard error (SE)] c-IMT tended to be thicker with longer duration, irrespective of ART.

We further examined the distribution of prevalent HIV-infection duration, which was then placed in (2–4), (4–8), (8–16), and (16–25) years intervals to ensure more comparable groups with similar HIV-duration. Adjusted mean c-IMT levels increased with prevalent HIV-infection duration in both treated and untreated patients (Fig. 1).

Fig. 1

Fig. 1

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Relation between carotid intima–medial thickness and inflammatory profiles

Adjusting for age, diabetes and hypertension, patients with an anti-inflammatory score below the median had thicker c-IMT (0.754 ± 0.006 mm) than those above the median (0.722 ± 0.006 mm), irrespective of concomitant high or low pro-inflammatory scores (P < 0.001, Fig. 2a and b). This finding held when adding nadir CD4+ cell count to the model (P < 0.001) and while excluding the elite controller patient (P = 0.001). Furthermore, a significantly higher mean c-IMT level among patients with low versus high anti-inflammatory markers was still observed when adding prevalent duration of HIV infection (0.761 ± 0.008 versus 0.725 ± 0.008, respectively, P = 0.002), suggesting that the association between anti-inflammation and c-IMT is independent of HIV-infection duration.

Fig. 2

Fig. 2

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Patterns of pro-inflammatory and anti-inflammatory profiles according to prevalent duration of HIV infection

As a group, the prevalence of pro-inflammatory scores above the median remained stable across the reconstructed duration of known HIV infection (Fig. 3a). Conversely, anti-inflammatory markers declined with longer infection duration (P < 0.001, Fig. 3b). Among these inflammatory markers, median-adjusted adiponectin and HMW adiponectin levels carried most of that decline in which respective decreases of 2.67–2.00 μg/ml and 1.29–1.06 μg/ml were observed between patients with 2–4 years of HIV infection versus more than 16 years (P for trend across HIV-duration in four groups < 0.001). Each pro-inflammatory and anti-inflammatory marker is summarized across groups of prevalent duration of HIV infection in Supplemental Figure 1, http://links.lww.com/QAD/A368.

Fig. 3

Fig. 3

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Discussion

In these carefully selected triads of never-smoking men, we report the persistence of an increased risk of carotid atherosclerosis in HIV-infected patients compared to their age-matched controls. Further, when comparing age-matched HIV-infected ART-naive individuals to individuals receiving ART, increased carotid atherosclerosis was related to prevalent duration of known HIV infection, irrespective of ART. Importantly, the increased carotid atherosclerosis was associated with a low anti-inflammatory profile, irrespective of pro-inflammatory markers values. In the reconstructed HIV history, the values of anti-inflammatory markers declined over time, providing further validation to our findings.

We opted to analyze the inflammatory markers as a whole and were careful to standardize them to allow a comparable contribution to the ratio. This approach is important as it avoids the risk of having one marker with a high numeric value overshadow another one with low, but increased, levels.

We designed this study in never-smokers because smoking remains the most important confounder of the reported increased vascular risk in HIV-infected individuals, among whom smoking is known to be prevalent. Notably, Petoumenos et al.[18] showed that the risk of CVD events in HIV-infected patients decreased with increasing time since smoking cessation, a finding that could put to doubt the existence of a truly increased risk independent of smoking patterns among these patients. Our results determine that the increased risk of carotid atherosclerosis exists independent of smoking. When substituting our adjustment with the Framingham score, the difference remained (P = 0.09).

We carefully selected our two HIV-infected groups with the rationale that, as exposures, both HIV infection and ART were to be given sufficient opportunity to affect carotid atherosclerosis. Nevertheless, dissecting HIV-infection duration and ART duration has been particularly difficult because of their intricacy, aside from the difficulty of finding treatment-naive individuals with a sufficiently long known infection of duration, while not falling in the category of elite controllers.

Two factors are likely to contribute to the discrepancies across studies [19–22] relative to the contribution of infection versus ART toward carotid atherosclerosis in HIV-infected individuals. First, a number of studies did not adjust for nadir CD4+ cell counts [23]. The importance of taking into account nadir CD4+ cell counts is evidenced by Ho et al.[24] who studied 80 HIV-infected men treated with ART and with undetectable plasma RNA levels: after adjustment for cardiovascular risk factors, nadir CD4+ cell counts were independently associated with arterial stiffness. Similarly, Medina et al.[25] report that both nadir and current CD4+ cell counts were significantly elevated with increasing coronary age in HIV-infected patients.

Discrepancies in results across studies are also likely due to the confounding role of smoking. This confounding role is not simply related to the higher prevalence of smoking among HIV-infected versus HIV-negative individuals, but also and significantly to the differential prevalence of smoking between treated and untreated groups among HIV-infected individuals. In a case–control study of 77 HIV-infected men (including 22 ART-naive) and 52 controls, van Vonderen et al.[26] reported that patients exposed to ART had similar c-IMT compared with ART-naive patients. However, because so many of those ART-naive individuals smoked (77%) compared to those receiving ART (56 and 30%, without and with lipodystrophy, respectively, P < 0.05), one could not exclude that ART naive individuals had thicker IMT because of their higher smoking habits, even after statistical adjustment. Similarly, Mangili et al.[27] found a strong association between c-IMT, hs-CRP, and all-cause mortality, which was similar irrespective of exposure to ART. Once again, smoking levels were significantly higher (71%) in those who died compared to those who did not (46%, P < 0.001) raising the possibility of residual bias even after statistical adjustment [27].

Hsue et al.[28] have shown that increased atherosclerosis can occur in the absence of ART in HIV-infected patients. In their interesting study, c-IMT in controllers was not different than in HIV-infected untreated patients and higher than in seronegative controls [28], suggesting a role for chronic inflammation. However, 85% of the controllers in Hsue's study were former or current smokers compared to 53% of the controls. We provide the first evidence in never-smokers, thereby bolstering the validity of an independent association, rather than one mediated by smoking. Naturally, although the exclusion of smokers in our study limits generalizability, it provides validity.

Studies looking at the role of inflammation with regard to CVD in HIV-infected patients have largely focused on specific inflammatory markers, with, sometimes, conflicting results. Among pro-inflammatory markers, a report comprising the Strategies for Management of Anti-Retroviral Therapy (SMART), International Network for Strategic Initiatives in Global HIV Trials, Coronary Artery Development in Young Adults, and Multi-Ethnic Study of Atherosclerosis studies showed that hs-CRP, D-dimer, interleukin-6, and cystatin C levels are elevated in HIV-infected persons even with HIV-RNA suppressed [29]. Kuller et al. found that interleukin-6 and D-dimer levels increased when ART was discontinuous and were related to all-cause mortality, raising the possibility that interrupting ART may further increase the risk of death by elevating these inflammatory makers levels [29,30]. However, Baker et al.[31] subsequently reported that interleukin-6 and hs-CRP did not decline significantly after the introduction of ART. Further, it has been reported that both interleukin-6 and interleukin-18 levels are associated with an increased CVD risk in the general population, and that adipose tissue, including adipose tissue macrophages, produces resistin but also SAA associated with insulin resistance and systemic inflammation in the general population and in HIV-infected patients [32,33]. However, in the SMART study, SAA levels at study entry were not associated with an increased mortality rate, contrary to interleukin-6 and CRP [30]. Moreover, these two markers increased in patients with CVD as compared to those without cardiovascular events.

Among anti-inflammatory markers, activation of the innate and acquired immune system also results in the release of immunosuppressive anti-inflammatory cytokines as interleukin-10 and interleukin-27 [34,35], which were reported to be inversely related to HIV-viral load but a relationship with cardiovascular risk was not previously investigated [36,37]. Adipose tissue also releases adiponectin with insulin-sensitizing and anti-inflammatory properties, whose levels are inversely related to viral load in HIV-infected patients [36]. A relationship with subclinical cardiac damage and hypoadiponectinemia has been observed in HIV-infected patients [38].

Building on these previous works to guide our choice of markers, and conscious of the limitations of single marker studies and analyses, we surmised a priori that immune/inflammatory system imbalances might be a better barometer than isolated measures of systemic inflammation. Our finding of the increased risk of carotid atherosclerosis among individuals with low anti-inflammatory profile seems to validate that view and is consistent with reports that hypoadiponectinemia is a marker of vascular damage [33] and that individuals with lower adiponectin also had significantly lower HDL and higher triglycerides, for example [39]. We can only speculate about the reasons why anti-inflammatory mediators decline with prevalent duration of HIV infection and the association with higher risk as determined by c-IMT. In response to injury/infection, a first wave of pro-inflammatory cytokine production is initiated and followed by a second wave of anti-inflammatory mediators such as interleukin-10, which play an important role in resolution of inflammation/injury and the maintenance of homeostasis. It is plausible that a small defect in anti-inflammatory response during the first years of HIV infection would sustain a pro-inflammatory state and be self-perpetuating with time, leading to progressive and sustained decline in anti-inflammatory response. The latter has been linked to alterations in vascular function, increased atherosclerosis and prevalence of high-risk lesions, particularly in association with ageing [40–42].

Additionally, HIV-specific immune response decreases during HIV infection [43]. This phenomenon has been largely explained by exhausted HIV-specific T cells, which generally lose their polyfunctional capacity and are associated with decreased production of the pro-inflammatory marker interferon-γ and decreased responsiveness to interleukin-12, interleukin-18, and interleukin-21 [44,45]. The low pro-inflammatory and low anti-inflammatory profile, which had the highest c-IMT, could be the result of increased frequency of exhausted CD8 T cells in these patients. As data were not collected on these specific cellular functions, this hypothesis remains speculative. Nevertheless, our results suggest that the anti-inflammatory profile was relevant for c-IMT whereas the pro-inflammatory was not. This was unexpected and needs to be further explored prospectively; likewise, although the inflammatory markers were chosen a priori, we cannot naturally exclude that other pro-inflammatory/anti-inflammatory ratios might reveal different associations with c-IMT.

The magnitude of c-IMT differences reported here is in keeping with values considered clinically relevant in prior studies. A cross-sectional difference of 0.03 mm in c-IMT was associated with a 15-mmHg increase in SBP [46]; likewise, a cross-sectional difference of 0.04 mm in c-IMT was equivalent to a 10-year age difference in individuals without bulbar plaque [47]. Thus, notwithstanding obvious design differences, our finding of 0.03–0.04 mm mean difference between both individuals with longer (versus shorter) HIV infection duration and individuals with low anti-inflammatory profile (versus high) seems to meet the threshold of clinically relevant differences.

This study shares with others the limitations of cross-sectional data; therefore, although we were able to reconstruct a historical cohort through the known duration of HIV infection and treatment, inferences on causality cannot be made. In addition, the duration of HIV infection was based on first positive serology and not initial infection. Treated patients may have presented with later stages of HIV diagnoses and thus longer cumulative duration of inflammation prior to treatment. We did adjust our models by nadir CD4+ cell count as a means to correct for differences in HIV-infection severity. Finally, some caution should be heeded when interpreting results stratified by HIV duration, as these were not the originally intended groupings and resulted from post-hoc analyses.

In summary, and to our knowledge, this is the first study reporting the preponderent association of HIV infection (rather than ART) to increased atherosclerosis in never-smokers, thus determining the validity of the relationship independent of this important confounder. We also report that a low level of anti-inflammatory/insulin-sensitizing profile (irrespective of the pro-inflammatory profile) seems associated with increased carotid atherosclerosis. Larger studies should incorporate and validate the import of inflammatory imbalance in the occurrence of atherosclerosis.

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Acknowledgements

We are grateful to the patients. We acknowledge Ludivine Laurans, Lydie Houssou, and Marie-Christine Rincon for their respective technical assistance for quantifying inflammatory and metabolic markers; Manuela Sebire, Alina Ciuchete, Loïc Desquilbet, Nelly Desplanque, and Catherine Lupin for participant recruitment, management, and data collection; Dr Jürgen Tredup, Dr Pauline Campa, Dr Diane Bollens, Dr Bénédicte Lefebvre, Dr Marie-Caroline Meyohas, Dr Jérôme Pacanowski, Dr Zineb Ouazene, Dr Gilles Raguin, Dr Phillippe Tangre, Dr Laurent Fonquernie, and Dr Karine Lacombe for stellar patient recruitment; Dr David Jacobs for statistical discussions; Sandrine Couffin-Cadiergues and Maria Trumeau for administrative assistance.

This work was supported by the Agence Nationale de Recherche sur le Sida et les Hépatites (ANRS grant number 2007/303); and Sidaction (grant number AI 20). Moïse Desvarieux is also the recipient of a Chair in Chronic Disease from the École des Hautes Etudes en Santé Publique, France. This collaboration was rendered possible by a Contrat d’Interface (to M.D.) between Inserm and Hôpital Saint-Antoine. A.B. was awarded a postdoctoral fellowship from the ANRS.

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Conflicts of interest

No authors reported conflicts of interest with the present study.

F.B. reports receiving research grants from Boehringer-Ingelheim and Gilead Sciences.

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Keywords:

antiretroviral; carotid intima–media thickness; HIV; infection duration; inflammatory imbalance; smoking

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