Increased carotid intima-media thickness in HIV patients is associated with increased cytomegalovirus-specific T-cell responses

The hemostatic balance in HIV-infected patients with and without antiretroviral therapy: partial restoration with antiretroviral therapy

The incidence of arterial and venous thrombosis in HIV-infected patients is increased compared to healthy controls. In this cross-sectional analysis we measured markers of endothelial cell activation, thrombin generation, fibrinolysis and anticoagulation combined with endogenous thrombin potential (ETP) and activated protein C sensitivity ratio (APCsr) as more global markers. We included 160 consecutive HIV-infected patients with a median age of 46 years (range, 27-77), of whom 92% were male, 74% Caucasian, 11% African American, 9% Hispanic, and 6% Asian. Homosexual contact was the main transmission mode. Seventy percent of patients were using combined antiretroviral therapy (cART). In 83% of patients laboratory markers outside the normal range for a non-HIV-infected population were observed. Significant lower levels of von Willebrand factor (vWF; p = 0.03), factor VIII (p < 0.0001), D-dimer (p = 0.01), and ETP (p = 0.01) were observed in HIV-infected patients on cART compared to patients not on cART. Significant lower levels of protein C (p = 0.05) and free protein S (p < 0.0001), and increased APCsr (p < 0.0001) were found in the HIV-infected patients not on cART. A single association was observed between raised levels of fibrinogen and use of a protease inhibitor (p = 0.002). No significant difference was observed in the percentage of patients with laboratory markers outside the normal range between patients using cART-regimens containing abacavir, stavudine, or didanosine and those with other nucleoside reverse transcriptase inhibitors. Although the prevalence of coagulation abnormalities was lower in HIV-infected patients using cART, a considerable proportion of HIV-infected patients on cART show endothelial cell activation and increased APCsr, suggestive of a persistent procoagulant state.

Impact of HIV infection on diastolic function and left ventricular mass

BACKGROUND

Patients with HIV have increased risk for cardiovascular disease, but the underlying mechanisms remain unknown. The purpose of this study was to determine the prevalence of echocardiographic abnormalities among asymptomatic HIV-infected individuals compared with HIV-uninfected individuals. Methods/Results- We performed echocardiography in 196 HIV-infected adults and 52 controls. Left ventricular ejection fraction, left ventricular mass indexed to the body surface area, and diastolic function were assessed according to American Society of Echocardiography standards. Left ventricular mass index was higher in HIV-infected patients (77.2 g/m(2) in patients with HIV versus 66.5 g/m(2) in controls, P<0.0001). Left ventricular ejection fraction was similar in both groups. Eight (4%) of the patients with HIV had evidence of left ventricular systolic dysfunction (defined as an EF <50%) versus none of the controls; 97 (50%) had mild diastolic dysfunction compared with 29% of the HIV-uninfected subjects (P=0.008). After adjustment for hypertension and race, HIV-infected participants had a mean 8 g/m(2) larger left ventricular mass index compared with controls (P=0.001). Higher left ventricular mass index was independently associated with lower nadir CD4 T-cell count, suggesting that immunodeficiency may play a role in this process. After adjustment for age and traditional risk factors, patients with HIV had a 2.4 greater odds of having diastolic dysfunction as compared with controls (P=0.019).

CONCLUSIONS

HIV-infected patients had a higher prevalence of diastolic dysfunction and higher left ventricular mass index compared with controls. These differences were not readily explained by differences in traditional risk factors and were independently associated with HIV infection. These results suggest that contemporary asymptomatic patients with HIV manifest mild functional and morphological cardiac abnormalities, which are independently associated with HIV infection.

Increased tissue factor expression on circulating monocytes in chronic HIV infection: relationship to in vivo coagulation and immune activation

HIV infection is associated with an increased risk of thrombosis; and as antiretroviral therapy has increased the lifespan of HIV-infected patients, their risk for cardiovascular events is expected to increase. A large clinical study found recently that all-cause mortality for HIV(+) patients was related to plasma levels of interleukin-6 and to D-dimer products of fibrinolysis. We provide evidence that this elevated risk for coagulation may be related to increased proportions of monocytes expressing cell surface tissue factor (TF, thromboplastin) in persons with HIV infection. Monocyte TF expression could be induced in vitro by lipopolysaccharide and flagellin, but not by interleukin-6. Monocyte expression of TF was correlated with HIV levels in plasma, with indices of immune activation, and with plasma levels of soluble CD14, a marker of in vivo lipopolysaccharide exposure. TF levels also correlated with plasma levels of D-dimers, reflective of in vivo clot formation and fibrinolysis. Thus, drivers of immune activation in HIV disease, such as HIV replication, and potentially, microbial translocation, may activate clotting cascades and contribute to thrombus formation and cardiovascular morbidities in HIV infection.

Association of abacavir and impaired endothelial function in treated and suppressed HIV-infected patients

BACKGROUND

HIV-infected patients have accelerated atherosclerosis. Abacavir has been associated with increased risk of cardiovascular events, for reasons that remain to be elucidated. As endothelial dysfunction is central to the pathogenesis of atherosclerosis, we tested the hypothesis that current treatment with abacavir is associated with impaired endothelial function.

METHODS

We studied a cohort of 61 antiretroviral-treated patients who had undetectable plasma HIV RNA levels. Endothelial function was assessed by measuring flow-mediated dilation (FMD) of the brachial artery. We compared FMD in patients treated with or without abacavir, while adjusting for traditional risk factors and HIV-specific characteristics.

RESULTS

The median age was 50 years (interquartile range 45-57). The median duration of HIV infection was 18 years, and the median CD4 cell count was 369 cells/microl. Thirty patients (49%) were receiving abacavir. Overall, the median FMD in the HIV-infected patients was low (3.5%; interquartile range 2.3-5.6%). The FMD was lower in the abacavir-treated patients than those not on abacavir (2.8 vs. 4.9%, P = 0.01). After adjustment for traditional risk factors, HIV-specific factors, and baseline brachial artery diameter, current abacavir use was independently associated with lower FMD (P = 0.017). Duration of therapy and CD4 cell count were not associated with reduced FMD.

CONCLUSION

Endothelial function, a central mechanism in atherosclerosis and a marker of cardiovascular risk, is impaired among antiretroviral-treated patients with undetectable viral loads. Current use of abacavir was independently associated with impaired endothelial function. This finding suggests that abnormal endothelial function may underlie the clinically observed increased risk in myocardial infarction among abacavir-treated patients.

Reduced thymus activity and infection prematurely age the immune system

The aging process affects all aspects of the immune system, particularly the T cells. The immune system in older individuals is often characterized by lower T cell numbers, lower naive/memory T cell ratios, and lower T cell diversity. Most measures of inflammation increase with age. Why this happens, and why there is so much person-to-person variability in these changes, is not known. In this issue of the JCI, Sauce and colleagues show that removal of the thymus during infancy results in premature onset of many of these age-associated changes to the immune system (see the related article beginning on page 3070). The effect of thymectomy was particularly notable in those individuals who acquired CMV infection. Data from this study, as well as data from other observational settings, suggest that reduced thymic function and persistent viral infections combine to accelerate a decline in immunologic function.

Role of viral replication, antiretroviral therapy, and immunodeficiency in HIV-associated atherosclerosis

OBJECTIVE

HIV-seropositive patients are at higher risk for atherosclerosis than HIV-seronegative persons. This has been variably attributed to antiretroviral drug toxicity, immunodeficiency, and/or HIV-associated inflammation. To evaluate the contributions of these factors to HIV-associated atherosclerosis, we assessed carotid artery intima-media thickness in a diverse cohort of HIV-seronegative and seropositive adults, including a unique group of HIV-infected patients who were untreated, had undetectable viral loads, and had preserved CD4 T-cell counts (HIV controllers).

METHODS AND RESULTS

Carotid intima-media thickness was measured in 494 participants, including 33 HIV controllers and 93 HIV-seronegative controls. HIV controllers had higher intima-media thickness than seronegative controls even after adjustment for traditional risk factors (P = 0.003). Intima-media thickness in controllers was similar to antiretroviral-untreated patients with detectable viremia. Across all participants, intima-media thickness was strongly associated with the presence of HIV disease rather than viral load or CD4 T-cell count. C-reactive protein was higher in HIV controllers than HIV-seronegative persons. Antiretroviral drug exposure was also associated with higher intima-media thickness.

CONCLUSIONS

Increased atherosclerosis with HIV infection can occur in the absence of antiretroviral therapy, detectable viremia, or overt immunodeficiency. Chronic inflammation - which is higher in controllers than in HIV-uninfected persons - may account for early atherosclerosis in these patients.

Human herpesvirus replication and abnormal CD8+ T cell activation and low CD4+ T cell counts in antiretroviral-suppressed HIV-infected patients

Background

Most HIV-infected patients receiving virologically suppressive antiretroviral therapy continue to have abnormal, generalized T cell activation. We explored whether the degree of ongoing cytomegalovirus (CMV), Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV) replication was associated with higher virus-specific T cell activation and the failure to achieve normal absolute CD4+ T cell counts in the face of long-term suppressive antiretroviral therapy.

Methodology

Longitudinally collected PBMC and saliva specimens obtained from HIV-infected patients on effective antiretroviral therapy for at least one year (plasma HIV RNA <75 copies/mL) were examined using a multiplex CMV, EBV and KSHV DNA PCR assay. Eleven cases were chosen who had CD8+ T cell CD38+HLA-DR+ expression >10% and plateau absolute CD4+ T cell counts <500 cells/µL. Five controls from the same study had CD8+ T cell CD38 expression <10% and plateau absolute CD4+ T cell counts >500 cells/µL.

Results and Conclusions

Among all subjects combined, 18% of PMBC samples were positive for CMV DNA, and 27%, 73% and 24% of saliva samples were positive for CMV, EBV and KSHV DNA, respectively. No significant differences or trends were observed between cases and controls in proportions of all CMV, EBV or KSHV DNA positive specimens, proportions of subjects in each group that intermittently or continuously shed CMV, EBV or KSHV DNA in saliva, or the median number of genome copies of CMV, EBV and KSHV DNA in saliva. Overall, number of genome copies in saliva were lower for KSHV than for CMV and lower for CMV than for EBV. Although replication of CMV, EBV and KSHV persists in many antiretroviral-suppressed, HIV-infected patients, we observed no evidence in this pilot case-control study that the magnitude of such human herpesvirus replication is associated with abnormally increased CD8+ T cell activation and sub-normal plateau absolute CD4+ T cell counts following virologically suppressive antiretroviral therapy.

Cardiovascular complications in HIV management: past, present, and future

Highly active antiretroviral therapy (HAART) has significantly improved the prognosis for many individuals with HIV infection. Consequently, HIV infection has become a chronic and manageable disease. The focus on long-term management of patients with HIV infection has broadened to include comorbid conditions, most notably cardiovascular disease. Patients with HIV infection share many cardiovascular risk factors with the general population, and HIV infection itself may increase cardiovascular risk. Changes in lipid profiles associated with increased cardiovascular risk that have been observed with some HAART regimens have been a cause for concern among clinicians who treat HIV-infected patients. However, the lipid effects of HAART seem to depend on the type and duration of regimens employed. They can be managed effectively according to current guidelines that recommend lifestyle changes (eg, improved diet, increased exercise, smoking cessation) and pharmacologic therapy described in established treatment paradigms for patients on antiretroviral therapy and similar to measures currently used by the general population. A review of the clinical data indicates that the virologic and immunologic benefits of HAART clearly outweigh any metabolic effects observed in some patients over time and that preexisting, established cardiovascular risk factors contribute significantly to the potential development of cardiovascular events. These benefits of antiretroviral therapy have been demonstrated in studies comparing the superior efficacy of continuous vs. intermittent HAART.

Endothelial activation markers are linked to HIV status and are independent of antiretroviral therapy and lipoatrophy

OBJECTIVES

To assess the association of inflammatory and endothelial activation biomarkers with the presence of lipoatrophy in HIV-infected subjects and to examine the role of HIV, antiretroviral therapy (ART), and metabolic parameters in endothelial activation and inflammation.

DESIGN

Prospective, cross-sectional study including 4 groups: HIV+ on ART with HIV-1 RNA<1000 copies/mL with and without clinical lipoatrophy, HIV+ ART naive, and healthy controls.

METHODS

We measured plasma levels of inflammatory cytokines (tumor necrosis factor-alpha, soluble tumor necrosis factor receptors I and II, interleukin-6, C-reactive protein, and myeloperoxidase) and endothelial activation markers (soluble intercellular and vascular cell adhesion molecules and von Willebrand factor).

RESULTS

We enrolled 182 subjects. Limb fat and lipoatrophy status were not correlated with endothelial markers. Endothelial markers were higher in HIV+ ART naive when compared with healthy controls and with HIV+ on ART but were similar between HIV+ on ART and healthy controls. Neither endothelial nor inflammatory markers were correlated with HIV duration, CD4 count, lipids, glucose, or specific ART. Strong correlations were found between some inflammatory cytokines and endothelial markers.

CONCLUSIONS

There is enhanced endothelial activation in ART naive, whereas HIV+ on ART has similar values to healthy controls. Lipoatrophy did not seem to affect endothelial activation. Results highlight a potential association between heightened inflammation and endothelial activation.

Cardiovascular complications and atherosclerotic manifestations in the HIV-infected population: type, incidence and associated risk factors

Before the introduction of successful antiretroviral therapy (ART), cardiovascular complications in HIV-infected patients were largely those resulting from immunosuppression (e.g. myocarditis, pericarditis, tamponade). With the advent of ART, there has been a spectacular decrease in morbidity and mortality in HIV-infected individuals. However, alongside metabolic complications caused by ART such as insulin resistance, dyslipidemia and lipodystrophy syndrome have been observed, which potentially increase the risk of cardiovascular complications, in particular coronary artery disease. Whether HIV infection and ART are independent and individual coronary risk factors is still controversial. More and more data are available demonstrating that increasing the duration of exposure to ART, and in particular protease inhibitors, increases the risk of myocardial infarction. At the same time, chronic infection, inflammation and the disruption of immune balance as a result of HIV infection itself may have the potential to alter vascular structure and function. In this article, we will review cardiovascular complications in HIV-infected patients before and after the advent of ART, focusing on coronary artery disease, its diagnosis, prognosis and therapy.

Low CD4+ T-cell count as a major atherosclerosis risk factor in HIV-infected women and men

OBJECTIVE

To assess the association of HIV infection, HIV disease parameters (including CD4+ T-cell counts, HIV viral load, and AIDS) and antiretroviral medication use with subclinical carotid artery atherosclerosis.

DESIGN

Cross-sectional study nested within a prospective cohort study.

METHODS

Among participants in the Women's Interagency HIV Study (1331 HIV-infected women, 534 HIV-uninfected women) and Multicenter AIDS Cohort Study (600 HIV-infected men, 325 HIV-uninfected men), we measured subclinical carotid artery lesions and common carotid artery intima-media thickness using B-mode ultrasound. We estimated adjusted mean carotid artery intima-media thickness differences and prevalence ratios for carotid lesions associated with HIV-related disease and treatments, with multivariate adjustment to control for possible confounding variables.

RESULTS

Among HIV-infected individuals, a low CD4+ T-cell count was independently associated with an increased prevalence of carotid lesions. Compared with the reference group of HIV-uninfected individuals, the adjusted prevalence ratio for lesions among HIV-infected individuals with CD4+ T-cell count less than 200 cells/mul was 2.00 (95% confidence interval, 1.22-3.28) in women and 1.74 (95% confidence interval, 1.04-2.93) in men. No consistent association of antiretroviral medications with carotid atherosclerosis was observed, except for a borderline significant association between protease inhibitor use and carotid lesions in men (with no association among women). History of clinical AIDS and HIV viral load were not significantly associated with carotid atherosclerosis.

CONCLUSION

Beyond traditional cardiovascular disease risk factors, low CD4+ T-cell count is the most robust risk factor for increased subclinical carotid atherosclerosis in HIV-infected women and men.

Association of HIV infection and HIV/HCV coinfection with C-reactive protein levels: the fat redistribution and metabolic change in HIV infection (FRAM) study

OBJECTIVE

Inflammation is a potential mechanism to explain the accelerated atherosclerosis observed in HIV- and hepatitis C virus (HCV)-infected persons. We evaluated C-reactive protein (CRP) in HIV-infected and HIV/HCV-coinfected individuals in the era of effective antiretroviral (ARV) therapy.

DESIGN

Cross-sectional study of Fat Redistribution and Metabolic Change in HIV Infection (FRAM) cohort and controls from the Coronary Artery Risk Development in Young Adults (CARDIA) study.

METHODS

CRP levels were measured in 1135 HIV-infected participants from the FRAM cohort and 281 controls from the CARDIA study. The associations of HIV and HIV/HCV infection with CRP levels were estimated by multivariable linear regression.

RESULTS

Compared with controls, HIV monoinfection was associated with an 88% higher CRP level in men (P < 0.0001) but with no difference in women (5%; P = 0.80) in multivariate analysis. CRP levels were not associated with ARV therapy, HIV RNA level, or CD4 cell count. Compared with controls, HIV/HCV coinfection was associated with a 41% lower CRP level in women (P = 0.012) but with no difference in men (+4%; P = 0.90). Among HIV-infected participants, HCV coinfection was associated with 50% lower CRP levels after multivariable analysis (P < 0.0001) in men and women. Greater visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were strongly associated with CRP levels. Among HIV-infected participants, CRP levels were 17% (P < 0.001) and 21% (P = 0.002) higher per doubling of VAT and SAT; among controls, CRP levels were 34% (P < 0.001) and 61% (P = 0.009) higher, respectively.

CONCLUSIONS

In the absence of HCV coinfection, HIV infection is associated with higher CRP levels in men. HCV coinfection is associated with lower CRP levels in men and women.

Increased carotid intima-media thickness in HIV patients treated with protease inhibitors as compared to non-nucleoside reverse transcriptase inhibitors

BACKGROUND

Prolonged exposure to protease inhibitor (PI)-, but not non-nucleoside reverse transcriptase inhibitor (NNRTI)-containing combination antiretroviral therapy (CART) has been associated with an increased cardiovascular risk, partly explained by the different effects of these drugs on plasma lipids. Most markedly, NNRTIs have been associated with increases in high density lipoprotein cholesterol (HDL-C), which may be atheroprotective.

METHODS

In a cross-sectional study we investigated the impact of PI- vs. NNRTI-based CART in 130 HIV-1-infected patients with plasma virus suppressed to below the limit of detection, whom had been continuously exposed for at least 2 years to either one of such regimens, but not both. Carotid intima-media thickness (C-IMT) and fasting metabolic parameters were measured.

RESULTS

Mean (+/-S.D.) C-IMT in patients treated with PI-based CART was 0.81 (+/-0.17) mm as compared to 0.71 (+/-0.14)mm in NNRTI treated patients (p=0.0003). HDL-C and apolipoprotein A-I (apoA-I) levels were higher in the NNRTI than in the PI group (1.39 mmol/L vs. 1.03 mmol/L; p<0.0001, and 1.44 mmol/L vs. 1.33 mmol/L; p=0.0008, respectively). Framingham Risk Score, body mass index, duration of CART, and use of PI-based CART were positively correlated with C-IMT whereas HDL-C and apoA-I were inversely correlated with C-IMT.

CONCLUSIONS

Treatment of HIV-1-infected patients for 2 years or more with PI-based compared to NNRTI-based CART is associated with greater C-IMT, consistent with the reported higher risk of CVD in patients using PI. However, this difference seems not fully explained by a more favorable impact of NNRTI-based CART on HDL-C and apoA-I levels.

Protease Inhibitors as Immunomodulatory Drugs for HIV Infection

More than 20 drugs from four therapeutic drug classes are widely available for the management of human immunodeficiency virus (HIV) infection, with promising drugs from two new drug classes expected to be approved by the US Food and Drug Administration (FDA) in mid-to-late 2007 (Table 1). When used in combination, these drugs can lead to durable and perhaps indefinite suppression of viral replication.

Can mTOR inhibitors reduce the risk of late kidney allograft failure?

The most frequent causes of late kidney allograft failure are chronic rejection, nonalloimmune injury and death, all of which may depend on the characteristics of the donor and recipient, but may also be influenced by the type of immunosuppression. Combining calcineurin inhibitors (CNIs) and corticosteroids offers potent immunosuppression, but may also cause side effects leading to progressive graft dysfunction or an increased risk of death. New immunosuppressive strategies may come from the availability of inhibitors of mTOR, a downstream effector of phosphatidylinositol-3 kinase that provides the signal for cell proliferation by phosphorylating a cascade of kinases. Recent trials have shown that it is possible to minimize the dose or withdraw CNIs a few weeks after transplantation when they are combined with mTOR inhibitors and their combination may also make it possible to minimize or avoid the use of corticosteroids. Moreover, by inhibiting the signal for cell proliferation, mTOR inhibitors may reduce the replication of cytomegalovirus inside host cells, prevent transplant vasculopathy, and exert anti-oncogenic activity. All of these characteristics offer a ray of hope for reducing the risk of long-term allograft failure.