Persistently Elevated Levels of von Willebrand Factor Antigen in HIV Infection

HIV Infection, Antiretroviral Drugs, and the Vascular Endothelium

Endothelial cell activation, injury, and dysfunction underlies the pathophysiology of vascular diseases and infections associated with vascular dysfunction, including human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome. Despite viral suppression with combination antiretroviral therapy (ART), people living with HIV (PLWH) are prone to many comorbidities, including neurological and neuropsychiatric complications, cardiovascular and metabolic diseases, premature aging, and malignancies. HIV and viral proteins can directly contribute to the development of these comorbidities. However, with the continued high prevalence of these comorbidities despite viral suppression, it is likely that ART or some antiretroviral (ARVs) drugs contribute to the development and persistence of comorbid diseases in PLWH. These comorbid diseases often involve vascular activation, injury, and dysfunction. The purpose of this manuscript is to review the current literature on ARVs and the vascular endothelium in PLWH, animal models, and in vitro studies. I also summarize evidence of an association or lack thereof between ARV drugs or drug classes and the protection or injury/dysfunction of the vascular endothelium and vascular diseases.

Plasma Interleukin-6 (IL-6), Angiopoietin-2, and C-Reactive Protein Levels Predict Subsequent Type 1 Myocardial Infarction in Persons With Treated HIV Infection

BACKGROUND

HIV infection leads to endothelial activation, promoting platelet adhesion, and accelerating atherosclerosis. Our goal was to determine whether biomarkers of endothelial activation and hemostasis/thrombosis were elevated in people with treated HIV (PWH) before myocardial infarction (MI).

METHODS

In a case-control study nested within the CFAR Network of Integrated Clinical Systems (CNICS) cohort, we compared 69 adjudicated cases with type 1 MI with 138 controls matched for antiretroviral therapy regimen. We measured angiopoietin-1, angiopoietin-2 (ANG-2), intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), von Willebrand factor, C-reactive protein (CRP), interleukin-6 (IL-6), plasminogen activation inhibitor-1, P-selectin, serum amyloid-A, soluble CD14, and apolipoprotein A1 in stored plasma. Conditional logistic regression identified associations with subsequent MI, with and without adjustment for Atherosclerotic Cardiovascular Disease (ASCVD) and Veterans Aging Cohort Study (VACS) scores.

RESULTS

Higher IL-6 was associated with MI after adjustment for ASCVD score (adjusted odds ratio [AOR] 1.51, 95% confidence interval [95% CI]: 1.05 to 2.17 per standard-deviation-scaled log 2 increment). In a separate model adjusting for VACS score, higher ANG-2 (AOR 1.49, 95% CI: 1.04 to 2.14), higher CRP (AOR 1.45, 95% CI: 1.06 to 2.00), and higher IL-6 (AOR 1.68, 95% CI: 1.17 to 2.41) were associated with MI. In a sensitivity analysis excluding PWH with viral load ≥400 copies/mL, higher IL-6 remained associated with MI after adjustment for ASCVD score and after adjustment for VACS score.

CONCLUSIONS

Among PWH, higher levels of plasma IL-6, CRP, and ANG-2 predict subsequent type 1 MI, independent of conventional risk scores. IL-6 had the most consistent associations with type 1 MI, regardless of viral load suppression.

Cardiovascular Disease and Thrombosis in HIV Infection

HIV infection has transitioned from an acute, fatal disease to a chronic one managed by antiretroviral therapy. Thus, the aging population of people living with HIV (PLWH) continues to expand. HIV infection results in a dysregulated immune system, wherein CD4+ T cells are depleted, particularly in the gastrointestinal tract, disrupting the gut epithelial barrier. Long-term HIV infection is associated with chronic inflammation through potentially direct mechanisms caused by viral replication or exposure to viral proteins and indirect mechanisms resulting from increased translocation of microbial products from the intestine or exposure to antiretroviral therapy. Chronic inflammation (as marked by IL [interleukin]-6 and CRP [C-reactive protein]) in PLWH promotes endothelial cell dysfunction and atherosclerosis. PLWH show significantly increased rates of cardiovascular disease, such as myocardial infarction (risk ratio, 1.79 [95% CI, 1.54-2.08]) and stroke (risk ratio, 2.56 [95% CI, 1.43-4.61]). In addition, PLWH have increased levels of the coagulation biomarker D-dimer and have a two to ten-fold increased risk of venous thromboembolism compared with the general population. Several small clinical trials analyzed the effect of different antithrombotic agents on platelet activation, coagulation, inflammation, and immune cell activation. Although some markers for coagulation were reduced, most agents failed to reduce inflammatory markers in PLWH. More studies are needed to understand the underlying mechanisms driving inflammation in PLWH to create better therapies for lowering chronic inflammation in PLWH. Such therapies can potentially reduce atherosclerosis, cardiovascular disease, and thrombosis rates in PLWH and thus overall mortality in this population.

Challenges in Platelet Functions in HIV/AIDS Management

The interest in platelet functions in HIV/AIDS is due to the high incidence of microvascular thrombosis in these individuals. A lot of laboratory data have been generated regarding platelet functions in this population. The tests demonstrate platelet hyperactivity but decreased aggregation, though results are inconsistent depending on the study design. Antiretroviral treatments currently in use display complex interactions. Many studies on platelet functions in these patients have been for research purposes, but none have found utility in guiding drug treatment of thrombosis.

Coagulation Parameters in Human Immunodeficiency Virus Infected Patients: A Systematic Review and Meta-Analysis

Background

Coagulation abnormalities are common complications of human immunodeficiency virus (HIV) infection. Highly active antiretroviral treatment (HAART) decreased the mortality of HIV but increased coagulopathies. HIV-related thrombocytopenia, prolonged prothrombin time (PT), activated partial thromboplastin time (APTT), and high D-dimer level commonly manifested in patients with HIV. Thus, this study is aimed to compare coagulation parameters of HAART-treated and HAART-naïve HIV-infected patients with HIV-seronegative controls.

Methods

A systematic literature search was conducted using the databases PubMed/MEDLINE, Embase, Web of Science, and Google Scholar of studies published until July 2021. The primary outcome of interest was determining the pooled mean difference of coagulation parameters between HIV-infected patients and seronegative controls. The Joana Briggs Institute (JBI) critical appraisal tool was used for quality appraisal. Statistical analyses were performed using Stata11.0 software. The statistical results were expressed as the effect measured by standardized mean difference (SMD) with their related 95% confidence interval (CI).

Results

A total of 7,498 participants (1,144 HAART-naïve patients and 2,270 HAART-treated HIV-infected patients and 3,584 HIV-seronegative controls) from 18 studies were included. HIV-infected patients (both on HAART and HAART-naive) exhibited significantly higher levels of PT than HIV-seronegative controls (SMD = 0.66; 95% CI: 0.53–0.80 and SMD = 1.13; 95% CI: 0.60–2.0, respectively). The value of APTT was significantly higher in patients with HIV on HAART than in seronegative controls. However, the values of PLT count, APTT, and fibrinogen level were significantly higher in seronegative controls. Besides, the level of fibrinogen was significantly higher in HAART-treated than treatment-naïve patients (SMD = 0.32; 95%CI: 0.08, 0.57). Moreover, the level of APTT and PT had no statistical difference between HAART and HAART-naïve HIV-infected patients.

Conclusions

This study identified that HIV-infected patients are more likely to develop coagulation abnormalities than HIV-seronegative controls. Therefore, coagulation parameters should be assessed regularly to prevent and monitor coagulation disorders in HIV-infected patients.

Interactions of HIV and Antiretroviral Therapy With Neutrophils and Platelets

Neutrophils are important components of the innate immune system that mediate pathogen defense by multiple processes including phagocytosis, release of proteolytic enzymes, production of reactive oxygen species, and neutrophil extracellular trap formation. Abnormalities of neutrophil count and function have been described in the setting of HIV infection, with the majority of antiretroviral agents (ARVs), excluding zidovudine, having been reported to correct neutropenia. Questions still remain, however, about their impact on neutrophil function, particularly the possibility of persistent neutrophil activation, which could predispose people living with HIV to chronic inflammatory disorders, even in the presence of virally-suppressive treatment. In this context, the effects of protease inhibitors and integrase strand transfer inhibitors, in particular, on neutrophil function remain poorly understood and deserve further study. Besides mediating hemostatic functions, platelets are increasingly recognized as critical role players in the immune response against infection. In the setting of HIV, these cells have been found to harbor the virus, even in the presence of antiretroviral therapy (ART) potentially promoting viral dissemination. While HIV-infected individuals often present with thrombocytopenia, they have also been reported to have increased platelet activation, as measured by an upregulation of expression of CD62P (P-selectin), CD40 ligand, glycoprotein IV, and RANTES. Despite ART-mediated viral suppression, HIV-infected individuals reportedly have sustained platelet activation and dysfunction. This, in turn, contributes to persistent immune activation and an inflammatory vascular environment, seemingly involving neutrophil-platelet-endothelium interactions that increase the risk for development of comorbidities such as cardiovascular disease (CVD) that has become the leading cause of morbidity and mortality in HIV-infected individuals on treatment, clearly underscoring the importance of unraveling the possible etiologic roles of ARVs. In this context, abacavir and ritonavir-boosted lopinavir and darunavir have all been linked to an increased risk of CVD. This narrative review is therefore focused primarily on the role of neutrophils and platelets in HIV transmission and disease, as well as on the effect of HIV and the most common ARVs on the numbers and functions of these cells, including neutrophil-platelet-endothelial interactions.

Hemostasis in elderly patients with human immunodeficiency virus (HIV) infection-Cross-sectional study

Introduction: Aging and chronic HIV infection are clinical conditions that share the states of inflammation and hypercoagulability. The life expectancy of the world population has increased in the last decades, bringing as complications the occurrence of diseases that undergoing metabolic, bone, cardiological, vascular and neurological alterations. HIV-infected patients experience these changes early and are living longer due to the success of antiretroviral therapy. The objectives of this study was to evaluate some changes in the plasma hemostatic profile of 115 HIV-reactive elderly individuals over 60 years old in the chronic phase of infection, and compare with 88 healthy uninfected elderly individuals. Plasma determinations of D-dimers, Fibrinogen, von Willebrand Factor, Antithrombin, Prothrombin Time, Activated Partial Thromboplastin Time, and platelet count were performed. In the HIV-reactive group, these variables were analyzed according to viral load, protease inhibitor use and CD4⁺ T lymphocyte values. After adjusted values for age and sex, the results showed higher levels of Antithrombin (103%; 88%, p = 0.0001) and Prothrombin Time activities (92.4%; 88.2%, p = 0.019) in the HIV group compared to the control group. We observed higher values of Fibrinogen in protease inhibitor users in both the male (p = 0.043) and female (p = 0.004) groups, and in the female HIV group with detected viral load (p = 0.015). The male HIV group with a CD4⁺ count> 400 cells / mm³ presented higher von Willebrand Factor values (p = 0.036). D-Dimers had higher values in the older age groups (p = 0.003; p = 0.042, respectively). Conclusion: Our results suggest that the elderly with chronic HIV infection with few comorbidities had a better hemostatic profile than negative control group, reflecting the success of treatment. Protease inhibitor use and age punctually altered this profile.

Interactions of viruses and the humoral innate immune response

The innate immune response is crucial for defense against virus infections where the complement system, coagulation cascade and natural antibodies play key roles. These immune components are interconnected in an intricate network and are tightly regulated to maintain homeostasis and avoid uncontrolled immune responses. Many viruses in turn have evolved to modulate these interactions through various strategies to evade innate immune activation. This review summarizes the current understanding on viral strategies to inhibit the activation of complement and coagulation cascades, evade natural antibody-mediated clearance and utilize complement regulatory mechanisms to their advantage.

Radionuclide imaging of inflammation in atherosclerotic vascular disease among people living with HIV infection: current practice and future perspective

People living with human immunodeficiency virus (HIV) infection have twice the risk of atherosclerotic vascular disease compared with non-infected individuals. Inflammation plays a critical role in the development and progression of atherosclerotic vascular disease. Therapies targeting inflammation irrespective of serum lipid levels have been shown to be effective in preventing the occurrence of CVD. Radionuclide imaging is a viable method for evaluating arterial inflammation. This evaluation is useful in quantifying CVD risk and for assessing the effectiveness of anti-inflammatory treatment. The most tested radionuclide method for quantifying arterial inflammation among people living with HIV infection has been with F-18 FDG PET/CT. The level of arterial uptake of F-18 FDG correlates with vascular inflammation and with the risk of development and progression of atherosclerotic disease. Several limitations exist to the use of F-18 FDG for PET quantification of arterial inflammation. Many targets expressed on macrophage, a significant player in arterial inflammation, have the potential for use in evaluating arterial inflammation among people living with HIV infection. The review describes the clinical utility of F-18 FDG PET/CT in assessing arterial inflammation as a risk for atherosclerotic disease among people living with HIV infection. It also outlines potential newer probes that may quantify arterial inflammation in the HIV-infected population by targeting different proteins expressed on macrophages.

HIV infection rather than concurrent opportunistic infections drives most systemic procoagulant, vascular and damage responses - a prospective cohort study in central Africa

BACKGROUND

HIV infection is accompanied by various systemic host responses, including activation of coagulation and the vascular endothelium. We sought to determine the impact of opportunistic coinfections in a central African setting.

METHODS

This prospective study included 98 HIV-infected individuals in Gabon initiating combination antiretroviral therapy (cART) and followed them up for 6 months. Patients were stratified according to the presence of active tuberculosis (TB; n=19), mucocutaneous opportunistic infection (n=9) or no opportunistic infection (n=70). HIV-uninfected subjects were included as controls (n=32). Plasma concentrations of 14 markers of coagulation, endothelial activation, extracellular matrix formation and tissue damage were measured with a multiplex assay at baseline and months 3 and 6 after cART initiation.

RESULTS

HIV-infected patients showed elevated plasma levels of all biomarkers measured with exception of protein C, which was reduced. Concurrent TB was only associated with elevated concentrations of D-dimer, metallopeptidase inhibitor 1 and Tenascin-C. Mucocutaneous coinfection did not alter HIV-associated responses. Most markers measured declined but remained elevated despite response to cART.

CONCLUSIONS

HIV infection is associated with systemic pro-coagulant, vascular and damage responses. In an ambulatory setting, concurrent opportunistic infections have little if any influence on these responses and normalization is incomplete after response to cART. This suggests that these responses are mainly driven by HIV-associated immune activation and less so by opportunistic infections.

Immune activation in the course of HIV-1 infection: Causes, phenotypes and persistence under therapy

Systemic immune activation is a striking consequence of HIV-1 infection. Even in virologically suppressed patients, some hyperactivity of the immune system and even of the endothelium and of the coagulation pathway may persist. Apart from immune deficiency, this chronic activation may contribute to various morbidities including atherothrombosis, neurocognitive disorders, liver steatosis and osteoporosis, which are currently main challenges. It is therefore of major importance to better understand the causes and the phenotypes of immune activation in the course of HIV-1 infection. In this review we will discuss the various causes of immune activation in HIV-1 infected organisms: the presence of the virus together with other microbes, eventually coming from the gut, CD4+ T cell lymphopenia, senescence and dysregulation of the immune system, and/or genetic factors. We will also describe the activation of the immune system: CD4+ and CD8+ T cells, B cells, NKT and NK cells, dendritic cells, monocytes and macrophages, and neutrophils of the inflammation cascade, as well as of the endothelium and the coagulation system. Finally, we will see that antiretroviral therapy reduces the hyperactivity of the immune and coagulation systems and the endothelial dysfunction, but often does not abolish it. A better knowledge of this phenomenon might help us to identify biomarkers predictive of non AIDS-linked comorbidities, and to define new strategies aiming at preventing their emergence.

Markers of coagulation and inflammation often remain elevated in ART-treated HIV-infected patients

PURPOSE OF REVIEW

Current antiretroviral therapies have dramatically changed the disease course of HIV infection. Although antiretroviral therapy is effective at decreasing viral replication and preserving CD4 T-cell numbers, low-level immune activation and inflammation persist in virally suppressed HIV-infected patients. This chronic immune activation/inflammation may contribute to an increased risk for venous and arterial thrombosis.

RECENT FINDINGS

Several markers of coagulation and inflammation are increased in HIV-infected patients. The Strategies for the Management of Antiretroviral Therapy study reported that plasma D-dimer levels, a marker of fibrinolysis, independently predicted morbidity in HIV-infected patients. Increased plasma and cell surface levels of the procoagulant tissue factor have also been reported in patients with HIV disease. Fibrinogen, von Willebrand factor, and P-selectin are likewise increased in plasma samples of HIV-infected patients; all of these markers suggest HIV-infection results in a procoagulant state. Treatment with antiretroviral therapy reduces, but does not always normalize, levels of biomarkers associated with inflammation and coagulation in HIV+ patients.

SUMMARY

HIV-infected patients are at greater risk for both venous and arterial thrombosis. Chronic immune activation and inflammation in these patients appears to contribute to coagulation risk. Antiretroviral therapy reduces viral replication, immune activation, and markers of coagulation, but these indices do not always return to normal, even after several years of viremic control.

Clinical utility of biomarkers of endothelial activation and coagulation for prognosis in HIV infection: a systematic review

Introduction: HIV infection is associated with vascular dysfunction and adverse cardiovascular outcomes. Our objective was to review the evidence regarding the clinical utility of endothelial activation and coagulation biomarkers for the prognosis of HIV-infected patients.

Methods: We searched PubMed and Embase for publications using the keywords “HIV” or “HIV infection” and “endothelium” or “coagulation”. We reviewed reference lists and hand-searched for additional relevant articles. All clinical studies that enrolled non-pregnant, HIV-infected adults, measured biomarkers reflecting endothelial activation or coagulation, and prospectively evaluated their associations with vascular dysfunction or clinical outcomes were included.

Results: Seventeen studies were identified that fulfilled the inclusion criteria, of which 11 investigated endothelial activation biomarkers and 12 investigated coagulation biomarkers. Biomarkers and outcomes varied widely across studies. Overall, published studies support an association between P-selectin and venous thromboembolism in HIV-infected patients, an association between tissue-type plasminogen activator and death, and associations between D-dimer and several clinical outcomes, including venous thromboembolism, cardiovascular disease, and all-cause mortality.

Conclusions: Several studies have demonstrated associations between biomarkers of endothelial activation and coagulation and clinically important outcomes in HIV-1 infection. Additional large-scale prospective investigations to determine the utility of endothelial activation and coagulation biomarkers for risk stratification and prediction of adverse outcomes are clearly warranted.

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.

The consequences of HIV infection and antiretroviral therapy use for cardiovascular disease risk: shifting paradigms

PURPOSE OF REVIEW

To explore the mechanisms by which HIV infection and antiretroviral therapy (ART) may increase risk for atherosclerotic cardiovascular disease (CVD), with attention to the implications of earlier initiation of ART (i.e. at higher CD4 cell counts than currently recommended by guidelines).

RECENT FINDINGS

Compared with the general population, HIV-infected patients who receive ART have a greater burden of subclinical and clinical atherosclerotic disease. Findings from a recent international treatment interruption trial (SMART) have redirected attention from ART-related drug toxicity toward a better appreciation for the consequences of untreated HIV infection, which may increase CVD risk through inflammation, upregulation of thrombotic pathways, and ultimately early vascular damage and dysfunction. In addition, CVD risk may increase with some ART, and this risk may be class-specific and/or drug-specific.

SUMMARY

Compared with untreated HIV, ART may increase or decrease risk of CVD. Reliable data on the relative risk do not exist. A randomized trial of early ART will provide the best data for assessment of the net risks and benefits of ART use on CVD.

Relationship between Progression to AIDS and Thrombophilic Abnormalities in HIV Infection

Background: HIV-infected patients are at increased risk of venous and arterial thrombosis. We hypothesized that acquired thrombophilic abnormalities that could predispose to thrombosis are most pronounced in patients in advanced stages of HIV infection.

Methods: We included 109 consecutive HIV-infected patients in the study and tested them twice for currently known thrombophilic abnormalities at an interval of at least 3 months (median, 3 months; range, 3–12 months). Detailed information was collected about the date of diagnosis of HIV infection, HIV treatment, and previous episodes of venous and arterial thrombosis.

Results: After HIV infection was diagnosed, 16% of the patients experienced symptomatic thrombosis (venous, 10%; arterial, 6%). Repeated measurements established protein C deficiency in 9% of the patients, increased factor VIII concentrations in 41%, high fibrinogen concentrations in 22%, and free protein S deficiency in 60%. Median factor VIII concentrations were higher in patients with AIDS (CD4 cell counts &lt;2 × 108/L) than in patients with a non–AIDS-defining illness (2260 IU/L vs 1 490 IU/L; P &lt; 0.001), whereas median free protein S concentrations were lower (450 IU/L vs 580 IU/L; P &lt; 0.001). Developing AIDS was associated with increasing factor VIII concentrations and decreasing free protein S concentrations. Increasing factor VIII concentrations were correlated with increasing fibrinogen concentrations and decreasing free protein S concentrations.

Conclusions: Multiple acquired and persistent thrombophilic abnormalities are more frequently observed in HIV-infected patients than in the healthy population. The frequencies of these thrombophilic abnormalities increase with the progression to AIDS. These findings may contribute to the high prevalence of venous and arterial thrombosis in HIV-infected patients.

Increased soluble vascular cell adhesion molecule-1 plasma levels and soluble intercellular adhesion molecule-1 during antiretroviral therapy interruption and retention of elevated soluble vascular cellular adhesion molecule-1 levels following resumption of antiretroviral therapy

OBJECTIVE

We investigated the effect of short viremic episodes on soluble markers associated with endothelial stress and cardiovascular disease risk in chronically HIV-1-infected patients followed during continuous antiretroviral therapy, antiretroviral therapy interruption and antiretroviral therapy resumption.

DESIGN AND METHODS

We assessed changes in plasma levels of von Willebrand factor, soluble vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 by enzyme-linked immunosorbent assay, as well as T-cell activation (CD8+/CD38+, CD8+/HLA-DR+ and CD3+/CD95+) by flow cytometry, in 36 chronically HIV-1-infected patients participating in a randomized study. Patients were divided into the following three groups: a, on continuous antiretroviral therapy; b, on a 6-week antiretroviral therapy interruption; or c, on antiretroviral therapy interruption extended to the achievement of viral set point.

RESULTS

Although all measurements remained stable over a 40-week follow-up on antiretroviral therapy, plasma levels of soluble vascular cell adhesion molecule-1 (P < 0.0001) and soluble intercellular adhesion molecule-1 (P = 0.003) increased during treatment interruption in correlation with viral rebound and T-cell activation. No significant changes in von Willebrand factor were observed in any of the groups. After resuming antiretroviral therapy, soluble vascular cell adhesion molecule-1 levels remained elevated even after achievement of viral suppression to less than 50 copies/ml.

CONCLUSION

The prompt rise in plasma soluble vascular cell adhesion molecule-1 and soluble intercellular adhesion molecule-1 upon viral rebound suggests an acute increase in endothelial stress upon treatment interruption, which may persists after viral resuppression of virus. Thus, viral replication during short-term treatment interruption may increase the overall cardiovascular risk during and beyond treatment interruption.

Effect of smoking cessation on markers of inflammation and endothelial cell activation among individuals with high risk for cardiovascular disease

OBJECTIVE

To prospectively determine the effect of smoking cessation on markers of inflammation and endothelial cell activation.

MATERIAL AND METHODS

Thirty male and 22 female smokers of >7 cigarettes daily, aged 32-64 years with cardiovascular disease (CVD) or additional risk factors to smoking, participated in a program of smoking cessation with a follow-up period of 1 year. Cessation was validated by carbon monoxide measurement in expired breath, and 41 of the patients completed the study (17 quitters and 24 non-quitters). Plasma samples were drawn at baseline and after 1 year, and inflammatory markers were analyzed by enzyme immunoassays. Peripheral blood mononuclear cells (PBMCs) were isolated at baseline and 1 year in 6 quitters and 6 smokers and mRNA levels of interleukin-8 (IL-8), tumor necrosis factor x (TNFx) and intercellular adhesion molecule 1 (ICAM-1) were analyzed by real-time quantitative RT-PCR.

RESULTS

Our main findings were: (i) While the concentration of soluble (s) ICAM-1 decreased in quitters, it increased in smokers, with a significant difference in changes between the groups (p=0.04). (ii) While there was only minor change in mRNA levels of IL-8 in smokers, those who stopped smoking showed a decrease in the gene expression of IL-8 (p < 0.09; comparing difference in changes). (iii) Concentrations of the other measured parameters (E-selectin, IL-6, sCD40 ligand, TNFx, von Willebrand factor, and C-reactive protein) were unchanged during follow-up in both groups.

CONCLUSION

Smoking cessation induced a reduction in ICAM-1, suggesting a novel mechanism for the rapid reduction in the risk of CVD following smoking cessation.

Functional Synergy between CD40 Ligand and HIV-1 Tat Contributes to Inflammation: Implications in HIV Type 1 Dementia

HIV type 1 (HIV-1)-associated dementia (HAD) is believed to occur due to aberrant activation of monocyte-derived macrophages and brain-resident microglial cells by viral proteins as well as by the proinflammatory mediators released by infected cells. To investigate the inflammatory aspects of the disease, we examined the levels of soluble CD40L (sCD40L) in paired samples of plasma and cerebrospinal fluid obtained from 25 HIV-infected individuals. A significantly higher level of sCD40L was detected in both cerebrospinal fluid and plasma from HIV-infected patients with cognitive impairment, compared with their nonimpaired counterparts. The contribution of sCD40L to the pathogenesis of HAD was then examined by in vitro experiments. rCD40L synergized with HIV-1 Tat to increase TNF-alpha release from primary human monocytes and microglia, in an NF-kappaB-dependent manner. The mechanistic basis for this synergism was attributed to a Tat-mediated up-regulation of CD40 in monocytes and microglia. Finally, the CD40L-mediated increase in TNF-alpha production by monocytes was shown to be biologically important; immunodepletion experiments revealed that TNF-alpha was essential for the neurotoxic effects of conditioned medium recovered from Tat/CD40L-treated monocytes. Taken together, our results show that CD40 signaling in microglia and monocytes can synergize with the effects of Tat, further amplifying inflammatory processes within the CNS and influencing neuronal survival.

Endothelial dysfunction in HIV infection

Highly active antiretroviral therapy (HAART) has significantly improved the prognosis of patients with HIV infection; however, the use of protease inhibitors has been associated with increased cardiovascular events and worsening of multiple coronary heart disease risk factors including dyslipidemia, insulin resistance, and endothelial dysfunction. Endothelial dysfunction may be caused by the infection itself, the immunologic responses due to the HIV virus, and also by the effects of HAART through their effects on both lipid and glucose metabolism. The study of endothelial function in HIV infection and its modifications by HAART is an exciting new field in clinical research, limited by multiple factors such as viral factors, immunologic conditions, and metabolic drug effects that could affect the interpretation of endothelial impairment. Further studies are still needed to understand the significance of endothelial dysfunction in the cardiovascular risk assessment of patients with HIV infection.

Increased Levels of Soluble CD40L in African Tick Bite Fever: Possible Involvement of TLRs in the Pathogenic Interaction betweenRickettsia africae, Endothelial Cells, and Platelets

The pathophysiological hallmark of spotted fever group rickettsioses comprises infection of endothelial cells with subsequent infiltration of inflammatory cells. Based on its ability to promote inflammation and endothelial cell activation, we investigated the role of CD40L in African tick bite fever (ATBF), caused by Rickettsia africae, using different experimental approaches. Several significant findings were revealed. 1) Patients with ATBF (n = 15) had increased serum levels of soluble CD40 ligand (sCD40L), which decreased during follow-up. 2) These enhanced sCD40L levels seem to reflect both direct and indirect (through endothelial cell activation involving CX3CL1-related mechanisms) effects of R. africae on platelets. 3) In combination with sCD40L, R. africae promoted a procoagulant state in endothelial cells by up-regulating tissue factor and down-regulating thrombomodulin expression. 4) Although the R. africae-mediated activation of platelets involved TLR2, the combined procoagulant effects of R. africae and sCD40L on endothelial cells involved TLR4. 5) Doxycycline counteracted the combined procoagulant effects of R. africae and sCD40L on endothelial cells. Our findings suggest an inflammatory interaction between platelets and endothelial cells in ATBF, involving TLR-related mechanisms. This interaction, which includes additive effects between sCD40L and R. africae, may contribute to endothelial inflammation and hypercoagulation in this disorder.

Interventional approach to recurrent myocardial infarction in HIV-1 infection

We report a case of recurrent myocardial infarction occurring in two different coronary territories in a man with HIV-1 infection. On each occasion, clinical and angiographic success was obtained by intracoronary stent placement.

Changing patterns in the neuropathogenesis of HIV during the HAART era

Rapid progress in the development of highly active antiretroviral therapy has changed the observed patterns in HIV encephalitis and AIDS-related CNS opportunistic infections. Early in the AIDS epidemic, autopsy studies pointed to a high prevalence of these conditions. With the advent of nucleoside reverse transcriptase inhibitors, the prevalence at autopsy of opportunistic infections, such as toxoplasmosis and progressive multifocal leukoencephalopathy, declined while that of HIV encephalitis increased. After the introduction of protease inhibitors, a decline in both HIV encephalitis and CNS opportunistic infections was observed. However, with the increasing resistance of HIV strains to antiretrovirals, there has been a resurgence in the frequency of HIV encephalitis and HIV leukoencephalopathy. HIV leukoencephalopathy in AIDS patients failing highly active antiretroviral therapy is characterized by massive infiltration of HIV infected monocytes/macrophages into the brain and extensive white matter destruction. This condition may be attributable to interactions of anti-retrovirals with cerebrovascular endothelium, astroglial cells and white matter of the brain. These interactions may lead to cerebral ischemia, increased blood-brain barrier permeability and demyelination. Potential mechanisms of such interactions include alterations in host cell signaling that may result in trophic factor dysregulation and mitochondrial injury. We conclude that despite the initial success of combined anti-retroviral therapy, more severe forms of HIV encephalitis appear to be emerging as the epidemic matures. Factors that may contribute to this worsening include the prolonged survival of HIV-infected patients, thereby prolonging the brain's exposure to HIV virions and proteins, the use of increasingly toxic combinations of poorly penetrating drugs in highly antiretroviral-experienced AIDS patients, and selection of more virulent HIV strains with higher replication rates and greater virulence in neural tissues.

What a Cardiologist Needs to Know About Patients With Human Immunodeficiency Virus Infection

Patient case: A 48-year-old man with human immunodeficiency virus (HIV) infection developed chronic chest pain that started after a bout of pneumonia. He has hypertension and has smoked cigarettes in the past. His current medications include Kaletra and Combivir. His total cholesterol was 331 mg/L, his HDL cholesterol was 27 mg/L, his triglycerides were 935 mg/L, and his LDL cholesterol could not be calculated. How should this patient be evaluated and managed?

HIV infection, HAART, and endothelial adhesion molecules: current perspectives

In this review we summarise the data on the effects of HIV infection and its therapy with antiretroviral drugs on adhesion molecules, considered to be potential biomarkers of endothelial cell function. This is a recent area of interest, given the unexpected associations between antiretroviral therapy, metabolic alterations of lipid profile, and the risk of cardiovascular disease in the absence of clear pathogenetic links. Although convincing prospective data are still scarce, it seems timely to elucidate the potential value of non-invasive, inexpensive tests for predicting cardiovascular risk in HIV-infected patients undergoing highly active antiretroviral therapy (HAART). Endothelial function, the most plausible link between infection, inflammation, and atherosclerosis, has been investigated since the beginning of the HIV epidemic. Increased concentrations of soluble adhesion molecules, such as those from the selectin and immunoglobulin families, have consistently been reported in HIV-positive patients. The introduction of HAART has renewed interest in the study of endothelial function in HIV-positive patients, in view of some HAART-related metabolic abnormalities (hyperlipidaemia, hyperglycaemia, fat redistribution) and several large reports of premature coronary artery disease. Whether HAART reduces endothelial injury associated with HIV infection or contributes to further endothelial cell activation is still a matter of controversy. Also unclear is whether HAART acts directly or indirectly, and if protease inhibitors and other classes of antiretroviral drugs differ in their proatherosclerotic effects. This article attempts to define the state of these emerging issues, identifies areas of controversy and of potential clinical relevance, and suggests some directions for future research.

Induction of pathogenic sets of genes in macrophages and neurons in NeuroAIDS

The etiology of the central nervous system (CNS) alterations after human immunodeficiency virus (HIV) infection, such as dementia and encephalitis, remains unknown. We have used microarray analysis in a monkey model of neuroAIDS to identify 98 genes, many previously unrecognized in lentiviral CNS pathogenesis, whose expression is significantly up-regulated in the frontal lobe of simian immunodeficiency virus-infected brains. Further, through immunohistochemical illumination, distinct classes of genes were found whose protein products localized to infiltrating macrophages, endothelial cells and resident glia, such as CD163, Glut5, and ISG15. In addition we found proteins induced in cortical neurons (ie, cyclin D3, tissue transglutaminase, alpha1-antichymotrypsin, and STAT1), which have not previously been described as participating in simian immunodeficiency virus or HIV-related CNS pathology. This molecular phenotyping in the infected brains revealed pathways promoting entry of macrophages into the brain and their subsequent detrimental effects on neurons. These data support the hypothesis that in HIV-induced CNS disease products of activated macrophages and astrocytes lead to CNS dysfunction by directly damaging neurons, as well as by induction of altered gene and protein expression profiles in neurons themselves which are deleterious to their function.

Endothelial markers and HIV infection in the era of highly active antiretroviral treatment

Many circumstances can induce activation and/or injury of the endothelium that plays a role in the development of vascular complications. Raised plasma levels of endothelial markers such as von Willebrand factor (vWF), soluble thrombomodulin (sTM) and soluble vascular cell adhesion molecule-1 (sVCAM-1) have a prognostic and/or diagnostic value. Human immunodeficiency virus-infected patients (HIV+) have a clustering of conditions that activate or injure the endothelium. Highly active antiretroviral treatment produces adverse effects such as dyslipemia, insulin resistance (IR) and body fat changes (named lipodystrophy syndrome) which may contribute to aggravate their endothelial perturbation. The aim of this study was to measure lipid profile, insulin resistance status, and endothelial markers in 38 HIV+ naive of antiretroviral treatment and 63 HIV+ under highly active antiretroviral treatment (33 with lipodystrophy syndrome and 30 without it). Body fat distribution was also evaluated by dual-energy X-ray absorptiometry (DEXA) analysis. Thirty-one HIV negative subjects were used as controls. We looked for association between variables. Insulin resistance status was a common finding in the four groups. Lipodystrophic patients presented an atherothrombotic lipid profile [elevated levels of triglycerides (TG), low-density lipoprotein cholesterol (LDL-chol) and apolipoprotein-B (APO-B)] and a strong loss of fat in legs and arms (lipoatrophy). All endothelial markers evaluated in our naive patients were higher as compared to control group. sVCAM-1 in HIV+ under therapy without lipodystrophy syndrome showed significantly decreased levels as compared to naive group (487 vs. 666 ng/ml) and vWF and sTM tended to diminish although they did not show a significant difference (130% vs. 170%, 41 vs. 45 ng/ml, respectively). Lipodystrophic patients showed a tendency to increased levels of endothelial activation markers (sVCAM-1: 500 ng/ml and vWF: 154%) together with significantly increased levels of an endothelial injury marker (sTM: 50 ng/ml) with respect to HIV+ under therapy without lipodystrophy syndrome. Plasma levels of sTM, as an endothelial injury marker, correlated with peripheral lipoatrophy (rho = -0.357) in lipodystrophic patients. In conclusion, despite the beneficial immunology effect of highly active antiretroviral treatment and the apparent decrease in the endothelial perturbation, the patients who develop lipodystrophy present altered endothelial markers and other risk factors, such as IR and dyslipemia, which turn them into a high atherothrombotic risk group.

Viral load and disease progression as responsible for endothelial activation and/or injury in human immunodeficiency virus-1-infected patients

The endothelium participates in haemostasis, inflammation, blood pressure regulation and other physiological systems. Consequently, endothelial dysfunction has been related to hypertension, thrombosis and atherosclerosis. Both von Willebrand factor (vWF) and tissue-type plasminogen activator (t-PA) are synthesized by the endothelium and their plasma levels increased during endothelium activation or injury. So far, they are well-known markers of endothelial cell function. Many circumstances activate or damage the endothelium, such as viruses, bacterium and inflammation. Circulating vWF and t-PA were studied in 92 unselected human immunodeficiency virus-1 (HIV-1)-infected patients [27 patients with and 65 patients without acquired immunodeficiency syndrome (AIDS)] and correlated with plasma levels of pro-inflammatory cytokines (tumour necrosis factor-alpha, interleukin-6), viral load, CD4 T-cell count and infectious status. HIV-1-infected patients had significantly higher plasma levels of vWF (152 versus 90%), tumour necrosis factor-alpha (31.3 versus 9.0 pg/ml) and interleukin-6 (3.5 versus 1.9 pg/ml) but not t-PA (5.9 versus 4.2 ng/ml) than the control group. These two endothelial markers correlated significantly with viral load and interleukin-6 levels in HIV-1-infected patients. The highest levels of vWF and t-PA were found in patients with AIDS. In conclusion, endothelial cell perturbation is present in HIV infection and may be a consequence of different mechanisms such as viral load, cytokines and advanced diseases.