Cardiomyocytes undergo apoptosis in human immunodeficiency virus cardiomyopathy through mitochondrion- and death receptor-controlled pathways

HIV-Associated Cardiovascular Disease Pathogenesis: An Emerging Understanding Through Imaging and Immunology

Cardiac abnormalities were identified early in the epidemic of AIDS, predating the isolation and characterization of the etiologic agent, HIV. Several decades later, the causation and pathogenesis of cardiovascular disease (CVD) linked to HIV infection continue to be the focus of intense speculation. Before the widespread use of antiretroviral therapy, HIV-associated CVD was primarily characterized by HIV-associated cardiomyopathy linked to profound immunodeficiency. With increasing antiretroviral therapy use, viral load suppression, and establishment of immune competency, the effects of HIV on the cardiovascular system are more subtle. Yet, people living with HIV still face an increased incidence of cardiovascular pathology. Advances in cardiac imaging modalities and immunology have deepened our understanding of the pathogenesis of HIV-associated CVD. This review provides an overview of the pathogenesis of HIV-associated CVD integrating data from imaging and immunologic studies with particular relevance to the HIV population originating from high-endemic regions, such as sub-Saharan Africa. The review highlights key evidence gaps in the field and suggests future directions for research to better understand the complex HIV-CVD interactions.

A new perspective on HIV: effects of HIV on brain-heart axis

The human immunodeficiency virus (HIV) infection can cause damage to multiple systems within the body, and the interaction among these various organ systems means that pathological changes in one system can have repercussions on the functions of other systems. However, the current focus of treatment and research on HIV predominantly centers around individual systems without considering the comprehensive relationship among them. The central nervous system (CNS) and cardiovascular system play crucial roles in supporting human life, and their functions are closely intertwined. In this review, we examine the effects of HIV on the CNS, the resulting impact on the cardiovascular system, and the direct damage caused by HIV to the cardiovascular system to provide new perspectives on HIV treatment.

Multimodality Imaging in HIV-Associated Cardiovascular Complications: A Comprehensive Review

Human immunodeficiency virus (HIV) infection is a leading cause of mortality and morbidity worldwide. The introduction of antiretroviral therapy (ART) has significantly reduced the risk of developing acquired immune deficiency syndrome and increased life expectancy, approaching that of the general population. However, people living with HIV have a substantially increased risk of cardiovascular diseases despite long-term viral suppression using ART. HIV-associated cardiovascular complications encompass a broad spectrum of diseases that involve the myocardium, pericardium, coronary arteries, valves, and systemic and pulmonary vasculature. Traditional risk stratification tools do not accurately predict cardiovascular risk in this population. Multimodality imaging plays an essential role in the evaluation of various HIV-related cardiovascular complications. Here, we emphasize the role of multimodality imaging in establishing the diagnosis and aetiopathogenesis of various cardiovascular manifestations related to chronic HIV disease. This review also provides a critical appraisal of contemporary data and illustrative cases.

A Comprehensive Outlook on Dilated Cardiomyopathy (DCM): State-Of-The-Art Developments with Special Emphasis on OMICS-Based Approaches

Dilated cardiomyopathy (DCM) remains an enigmatic cardiovascular disease (CVD) condition characterized by contractile dysfunction of the myocardium due to dilation of the ventricles. DCM is one of the major forms of CVD contributing to heart failure. Dilation of the left or both ventricles with systolic dysfunction, not explained by known causes, is a hallmark of DCM. Progression of DCM leads to heart failure. Genetic and various other factors greatly contribute to the development of DCM, but the etiology has still remained elusive in a large number of cases. A significant number of studies have been carried out to identify the genetic causes of DCM. These candidate-gene studies revealed that mutations in the genes of the fibrous, cytoskeletal, and sarcomeric proteins of cardiomyocytes result in the development of DCM. However, a significant proportion of DCM patients are idiopathic in nature. In this review, we holistically described the symptoms, causes (in adults and newborns), genetic basis, and mechanistic progression of DCM. Further, we also summarized the state-of-the-art diagnosis, available biomarkers, treatments, and ongoing clinical trials of potential drug regimens. DCM-mediated heart failure is on the rise worldwide including in India. The discovery of biomarkers with a better prognostic value is the need of the hour for better management of DCM-mediated heart failure patients. With the advent of next-generation omics-based technologies, it is now possible to probe systems-level alterations in DCM patients pertaining to the identification of novel proteomic and lipidomic biomarkers. Here, we also highlight the onset of a systems-level study in Indian DCM patients by applying state-of-the-art mass-spectrometry-based “clinical proteomics” and “clinical lipidomics”.

Human Immunodeficiency Virus Increases the Risk of Incident Heart Failure

BACKGROUND

Although the HIV can cause myocardial inflammation, the association of HIV infection with subsequent development of heart failure (HF) has not been extensively studied. This nationwide cohort study aimed to determine the risk of incident HF in people living with HIV/AIDS (PLWHA).

METHODS

We identified PLWHA using the Taiwan Centers for Disease Control and Prevention HIV Surveillance System. An age- and sex-matched control group without HIV infection was selected from the Taiwan National Health Insurance Research Database for comparison. All patients were followed up until December 2014 and were observed for a new diagnosis of HF. A time-dependent Cox proportional hazards model was used to determine the association of HIV and highly active antiretroviral therapy with incident HF, with death as a competing risk event.

RESULTS

Of the 120,765 patients (24,153 PLWHA and 96,612 matched controls), 641 (0.53%) had incident HF during a mean follow-up period of 5.84 years, including 192 (0.79%) PLWHA and 449 (0.46%) controls. Time to diagnosis of incident HF was significantly shorter in PLWHA than in those without HIV infection (P < 0.001, the log-rank test). After adjusting for age, sex, and comorbidities, HIV infection was found to be an independent risk factor for incident HF (adjusted hazard ratio, 1.52; 95% confidence interval: 1.27 to 1.82). As the duration of highly active antiretroviral therapy increased, the risk of HF decreased (P = 0.014).

CONCLUSIONS

HIV infection was an independent risk factor for incident HF. Clinicians need to be aware of the higher risk of HF in PLWHA.

Heart health in the age of highly active antiretroviral therapy: a review of HIV cardiomyopathy

PURPOSE OF REVIEW

Advancements in highly active antiretroviral therapy (HAART) for human immunodeficiency virus (HIV) has led to increased survival, approaching that of the general population. These patients are at an increased risk for heart disease, specifically HIV-associated cardiomyopathy.

RECENT FINDINGS

Initially, HIV-associated cardiomyopathy was predominantly noted as systolic dysfunction, but diastolic dysfunction has become more common with increased use of HAART. The pathogenesis of HIV-associated cardiomyopathy involves direct viral infection, cytokine activity, focal myocarditis, HAART side effects, immune system dysregulation, and/or ischemia. If cardiomyopathy is diagnosed, an HIV patient should be started, or continued, on HAART and initiated on guideline-directed medical therapy (GDMT) per the ACC/AHA guidelines. The safety and efficacy of mechanical circulatory support and heart transplant in this population has been repeatedly demonstrated, but it remains less available compared with the general advanced heart failure population.

SUMMARY

The widespread use of HAART has led to prolonged survival in HIV patients to the point that cardiac disease has become the most common cause of death. Patients should be treated with HAART for HIV and GDMT for heart failure. Patients progressing to end-stage heart failure should be referred for advanced therapies to centers with experience treating HIV patients.

HIV Proteins and Endothelial Dysfunction: Implications in Cardiovascular Disease

With the success of antiretroviral therapy (ART), a dramatic decrease in viral burden and opportunistic infections and an increase in life expectancy has been observed in human immunodeficiency virus (HIV) infected individuals. However, it is now clear that HIV- infected individuals have enhanced susceptibility to non-AIDS (Acquired immunodeficiency syndrome)-related complications such as cardiovascular disease (CVD). CVDs such as atherosclerosis have become a significant cause of morbidity and mortality in individuals with HIV infection. Though studies indicate that ART itself may increase the risk to develop CVD, recent studies suggest a more important role for HIV infection in contributing to CVD independently of the traditional risk factors. Endothelial dysfunction triggered by HIV infection has been identified as a critical link between infection, inflammation/immune activation, and atherosclerosis. Considering the inability of HIV to actively replicate in endothelial cells, endothelial dysfunction depends on both HIV-encoded proteins as well as inflammatory mediators released in the microenvironment by HIV-infected cells. Indeed, the HIV proteins, gp120 (envelope glycoprotein) and Tat (transactivator of transcription), are actively secreted into the endothelial cell micro-environment during HIV infection, while Nef can be actively transferred onto endothelial cells during HIV infection. These proteins can have significant direct effects on the endothelium. These include a range of responses that contribute to endothelial dysfunction, including enhanced adhesiveness, permeability, cell proliferation, apoptosis, oxidative stress as well as activation of cytokine secretion. This review summarizes the current understanding of the interactions of HIV, specifically its proteins with endothelial cells and its implications in cardiovascular disease. We analyze recent in vitro and in vivo studies examining endothelial dysfunction in response to HIV proteins. Furthermore, we discuss the multiple mechanisms by which these viral proteins damage the vascular endothelium in HIV patients. A better understanding of the molecular mechanisms of HIV protein associated endothelial dysfunction leading to cardiovascular disease is likely to be pivotal in devising new strategies to treat and prevent cardiovascular disease in HIV-infected patients.

Incidence of cardiovascular diseases in a nationwide HIV/AIDS patient cohort in Taiwan from 2000 to 2014

The purpose of the study was to determine the incidence of cardiovascular disease (CVD) among people living with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (PLWHA) in Taiwan. PLWHA were identified from the Taiwan Centers for Disease Control HIV Surveillance System between 2000 and 2014. To examine the effect of active antiretroviral therapy (HAART) on CVD incidence, incidence densities and standardised incidence rates (SIRs) of CVD were calculated after stratifying PLWHA by HAART. Of 26 272 PLWHA (mean age, 32.3 years) identified, 73.4% received HAART. Compared with general population, SIRs (95% confidence interval) were higher for incident coronary artery disease (1.11 (1.04-1.19)), percutaneous coronary intervention (1.32 (1.18-1.47)), coronary artery bypass surgery (1.47 (1.29-1.66)), sudden cardiac death (3.01 (2.39-3.73)), heart failure (1.50 (1.31-1.70)) and chronic kidney disease (1.95 (1.81-2.10)), but was lower for incident atrial fibrillation (0.53 (0.37-0.73)). Considering the effect of HAART on incident CVD, the SIRs for all-cause, ischaemic and haemorrhagic stroke were higher in PLWHA who did not receive HAART, but were lower in PLWHA who received HAART. PLWHA had higher risks of incident coronary artery disease, percutaneous coronary intervention, coronary artery bypass surgery, sudden cardiac death, heart failure and chronic kidney disease. HAART reduces risks of incident CVD in PLWHA.

HIV-1 Nef-induced cardiotoxicity through dysregulation of autophagy

Cardiovascular disease is a leading cause of co-morbidity in HIV-1 positive patients, even those in whom plasma virus levels are well-controlled. The pathogenic mechanism of HIV-1-associated cardiomyopathy is unknown, but has been presumed to be mediated indirectly, owing to the absence of productive HIV-1 replication in cardiomyocytes. We sought to investigate the effect of the HIV-1 auxiliary protein, Nef, which is suspected of extracellular release by infected CD4+ T cells on protein quality control and autophagy in cardiomyocytes. After detection of Nef in the serum of HIV-1 positive patients and the accumulation of this protein in human and primate heart tissue from HIV-1/SIV-infected cells we employed cell and molecular biology approaches to investigate the effect of Nef on cardiomyocyte-homeostasis by concentrating on protein quality control (PQC) pathway and autophagy. We found that HIV-1 Nef-mediated inhibition of autophagy flux leads to cytotoxicity and death of cardiomyocytes. Nef compromises autophagy at the maturation stage of autophagosomes by interacting with Beclin 1/Rab7 and dysregulating TFEB localization and cellular lysosome content. These effects were reversed by rapamycin treatment. Our results indicate that HIV-1 Nef-mediated inhibition of cellular PQC is one possible mechanism involved in the development of HIV-associated cardiomyopathy.

Dysregulation of mitochondrial bioenergetics and quality control by HIV-1 Tat in cardiomyocytes

Cardiovascular disease remains a leading cause of morbidity and mortality in HIV-positive patients, even in those whose viral loads are well controlled with antiretroviral therapy. However, the underlying molecular events responsible for the development of cardiac disease in the setting of HIV remain unknown. The HIV-encoded Tat protein plays a critical role in the activation of HIV gene expression and profoundly impacts homeostasis in both HIV-infected cells and uninfected cells that have taken up released Tat via a bystander effect. Since cardiomyocyte function, including excitation-contraction coupling, greatly depends on energy provided by the mitochondria, in this study, we performed a series of experiments to assess the impact of Tat on mitochondrial function and bioenergetics pathways in a primary cell culture model derived from neonatal rat ventricular cardiomyocytes (NRVCs). Our results show that the presence of Tat in cardiomyocytes is accompanied by a decrease in oxidative phosphorylation, a decline in the levels of ATP, and an accumulation of reactive oxygen species (ROS). Tat impairs the uptake of mitochondrial Ca²⁺ ([Ca²⁺ ]_m ) and the electrophysiological activity of cardiomyocytes. Tat also affects the protein clearance pathway and autophagy in cardiomyocytes under stress due to hypoxia-reoxygenation conditions. A reduction in the level of ubiquitin along with dysregulated degradation of autophagy proteins including SQSTM1/p62 and a reduction of LC3 II were detected in cardiomyocytes harboring Tat. These results suggest that, by targeting mitochondria and protein quality control, Tat significantly impacts bioenergetics and autophagy resulting in dysregulation of cardiomyocyte health and homeostasis.

Signaling Pathways in Cardiac Myocyte Apoptosis

Cardiovascular diseases, the number 1 cause of death worldwide, are frequently associated with apoptotic death of cardiac myocytes. Since cardiomyocyte apoptosis is a highly regulated process, pharmacological intervention of apoptosis pathways may represent a promising therapeutic strategy for a number of cardiovascular diseases and disorders including myocardial infarction, ischemia/reperfusion injury, chemotherapy cardiotoxicity, and end-stage heart failure. Despite rapid growth of our knowledge in apoptosis signaling pathways, a clinically applicable treatment targeting this cellular process is currently unavailable. To help identify potential innovative directions for future research, it is necessary to have a full understanding of the apoptotic pathways currently known to be functional in cardiac myocytes. Here, we summarize recent progress in the regulation of cardiomyocyte apoptosis by multiple signaling molecules and pathways, with a focus on the involvement of these pathways in the pathogenesis of heart disease. In addition, we provide an update regarding bench to bedside translation of this knowledge and discuss unanswered questions that need further investigation.

Human Immunodeficiency Virus and Heart Failure in Low- and Middle-Income Countries

Successful combination therapy for human immunodeficiency virus (HIV) has transformed this disease from a short-lived infection with high mortality to a chronic disease associated with increasing life expectancy. This is true for high- as well as low- and middle-income countries. As a result of this increased life expectancy, people living with HIV are now at risk of developing other chronic diseases associated with aging. Heart failure has been common among people living with HIV in the eras of pre- and post- availability of antiretroviral therapy; however, our current understanding of the pathogenesis and approaches to management have not been systematically addressed. HIV may cause heart failure through direct (e.g., viral replication, mitochondrial dysfunction, cardiac autoimmunity, autonomic dysfunction) and indirect (e.g., opportunistic infections, antiretroviral therapy, alcohol abuse, micronutrient deficiency, tobacco use) pathways. In low- and middle-income countries, 2 large observational studies have recently reported clinical characteristics and outcomes in these patients. HIV-associated heart failure remains a common cardiac diagnosis in people living with heart failure, yet a unifying set of diagnostic criteria is lacking. Treatment patterns for heart failure fall short of society guidelines. Although there may be promise in cardiac glycosides for treating heart failure in people living with HIV, clinical studies are needed to validate in vitro findings. Owing to the burden of HIV in low- and middle-income countries and the concurrent rise of traditional cardiovascular risk factors, strategic and concerted efforts in this area are likely to impact the care of people living with HIV around the globe.

The Causes of HIV-Associated Cardiomyopathy: A Tale of Two Worlds

Antiretroviral therapy (ART) has transformed the clinical profile of human immunodeficiency virus (HIV) from an acute infection with a high mortality into a treatable, chronic disease. As a result, the clinical sequelae of HIV infection are changing as patients live longer. HIV-associated cardiomyopathy (HIVAC) is a stage IV, HIV-defining illness and remains a significant cause of morbidity and mortality among HIV-infected individuals despite ART. Causes and clinical manifestations of HIVAC depend on the degree of host immunosuppression. Myocarditis from direct HIV toxicity, opportunistic infections, and nutritional deficiencies are implicated in causing HIVAC when HIV viral replication is unchecked, whereas cardiac autoimmunity, chronic inflammation, and ART cardiotoxicity contribute to HIVAC in individuals with suppressed viral loads. The initiation of ART has dramatically changed the clinical manifestation of HIVAC in high income countries from one of severe, left ventricular systolic dysfunction to a pattern of subclinical cardiac dysfunction characterized by abnormal diastolic function and strain. In low and middle income countries, however, HIVAC is the most common HIV-associated cardiovascular disease. Clear diagnostic and treatment guidelines for HIVAC are currently lacking but should be prioritized given the global burden of HIVAC.

A Novel Role of Proline Oxidase in HIV-1 Envelope Glycoprotein-induced Neuronal Autophagy

Proline oxidase (POX) catalytically converts proline to pyrroline-5-carboxylate. This catabolic conversion generates reactive oxygen species (ROS) that triggers cellular signaling cascades including autophagy and apoptosis. This study for the first time demonstrates a role of POX in HIV-1 envelope glycoprotein (gp120)-induced neuronal autophagy. HIV-1 gp120 is a neurotoxic factor and is involved in HIV-1-associated neurological disorders. However, the mechanism of gp120-mediated neurotoxicity remains unclear. Using SH-SY5Y neuroblastoma cells as a model, this study demonstrates that gp120 treatment induced POX expression and catalytic activity. Concurrently, gp120 also increased intracellular ROS levels. However, increased ROS had a minimal effect on neuronal apoptosis. Further investigation indicated that the immediate cellular response to increased ROS paralleled with induction of autophagy markers, beclin-1 and LC3-II. These data lead to the hypothesis that neuronal autophagy is activated as a cellular protective response to the toxic effects of gp120. A direct and functional role of POX in gp120-mediated neuronal autophagy was examined by inhibition and overexpression studies. Inhibition of POX activity by a competitive inhibitor "dehydroproline" decreased ROS levels concomitant with reduced neuronal autophagy. Conversely, overexpression of POX in neuronal cells increased ROS levels and activated ROS-dependent autophagy. Mechanistic studies suggest that gp120 induces POX by targeting p53. Luciferase reporter assays confirm that p53 drives POX transcription. Furthermore, data demonstrate that gp120 induces p53 via binding to the CXCR4 co-receptor. Collectively, these results demonstrate a novel role of POX as a stress response metabolic regulator in HIV-1 gp120-associated neuronal autophagy.

Increased cardiovascular disease risk in the HIV-positive population on ART: potential role of HIV-Nef and Tat

With effective antiretroviral therapy (ART), many HIV-infected people die of diseases other than acquired immune deficiency syndrome (AIDS). In particular, coronary artery disease has emerged as one of most critical complications of HIV infection and a major cause of morbidity and mortality. Although reportedly antiretroviral combination therapy itself may accelerate atherosclerosis by enhancing dyslipidemia, most recent epidemiological studies support the notion that HIV infection itself contributes to cardiovascular disease. However, it is still a mystery how the virus can contribute to cardiovascular disease development even while suppressed by ARTs. This review discusses the current understanding of interactions between HIV infection and cardiovascular diseases in both clinical and experimental studies with special focus on those viral proteins that are still produced by HIV. This will help infectious disease/vascular biology experts to gain insights into the pathophysiological mechanisms of HIV-associated cardiovascular disease and new trends to treat and prevent cardiovascular disease in the HIV-infected population.

HIV-1 subtype C unproductively infects human cardiomyocytes in vitro and induces apoptosis mitigated by an anti-Gp120 aptamer

HIV-associated cardiomyopathy (HIVCM) is of clinical concern in developing countries because of a high HIV-1 prevalence, especially subtype C, and limited access to highly active antiretroviral therapy (HAART). For these reasons, we investigated the direct and indirect effects of HIV-1 subtype C infection of cultured human cardiomyocytes and the mechanisms leading to cardiomyocytes damage; as well as a way to mitigate the damage. We evaluated a novel approach to mitigate HIVCM using a previously reported gp120 binding and HIV-1 neutralizing aptamer called UCLA1. We established a cell-based model of HIVCM by infecting human cardiomyocytes with cell-free HIV-1 or co-culturing human cardiomyocytes with HIV-infected monocyte derived macrophages (MDM). We discovered that HIV-1 subtype C unproductively (i.e. its life cycle is arrested after reverse transcription) infects cardiomyocytes. Furthermore, we found that HIV-1 initiates apoptosis of cardiomyocytes through caspase-9 activation, preferentially via the intrinsic or mitochondrial initiated pathway. CXCR4 receptor-using viruses were stronger inducers of apoptosis than CCR5 utilizing variants. Importantly, we discovered that HIV-1 induced apoptosis of cardiomyocytes was mitigated by UCLA1. However, UCLA1 had no protective effective on cardiomyocytes when apoptosis was triggered by HIV-infected MDM. When HIV-1 was treated with UCLA1 prior to infection of MDM, it failed to induce apoptosis of cardiomyocytes. These data suggest that HIV-1 causes a mitochondrial initiated apoptotic cascade, which signal through caspase-9, whereas HIV-1 infected MDM causes apoptosis predominantly via the death-receptor pathway, mediated by caspase-8. Furthermore the data suggest that UCLA1 protects cardiomyocytes from caspase-mediated apoptosis, directly by binding to HIV-1 and indirectly by preventing infection of MDM.

CCR5 inhibition prevents cardiac dysfunction in the SIV/macaque model of HIV

Background

Diastolic dysfunction is a highly prevalent cardiac abnormality in asymptomatic as well as ART‐treated human immunodeficiency virus (HIV) patients. Although the mechanisms underlying depressed cardiac function remain obscure, diastolic dysfunction in SIV‐infected rhesus macaques is highly correlated with myocardial viral load. As cardiomyocytes are not productively infected, damage may be an indirect process attributable to a combination of pro‐inflammatory mediators and viral proteins.

Methods and Results

Given the diverse roles of CCR5 in mediating recruitment of leukocytes to inflammatory sites and serving as a receptor for HIV entry into cells, we investigated the role of CCR5 in the SIV/macaque model of diastolic dysfunction. We found that in SIV‐infected macaques, CCR5 inhibition dramatically impacted myocardial viral load measured by qRT‐PCR and prevented diastolic dysfunction measured by echocardiography. Complementary in vitro experiments using fluorescence microscopy showed that CCR5 ligands impaired contractile function of isolated cardiomyocytes, thus identifying CCR5 signaling as a novel mediator of impaired cardiac mechanical function.

Conclusions

Together, these findings incriminate SIV/HIV gp120‐CCR5 as well as chemokine‐CCR5 interactions in HIV‐associated cardiac dysfunction. These findings also have important implications for the treatment of HIV‐infected individuals: in addition to antiviral properties and reduced chemokine‐mediated recruitment and activation of inflammatory cells, CCR5 inhibition may provide a cardioprotective benefit by preventing cardiomyocyte CCR5 signaling.

Myocardial infarction caused by pharmacological substances - case description and literature review

Myocardial infarction (MI) is most commonly caused by atherosclerosis and/or inflammatory processes of coronary artery walls. The consequence of those phenomena is instability of the atherosclerotic plaque, activation of the coagulation cascade and thrombus formation which occludes the lumen of the vessel. Vasospasm and microembolisation may participate in MI pathogenesis. In young individuals with diagnosis of MI, coronarography often reveals no pathologies. Is reported that MIs without significant changes of the coronary arteries occur in 1% to 12% of patients. In this article we focus on chemical substances, medicines among them, which can be a cause of MI.

Isothiocyanates ameliorate the symptom of heart dysfunction and mortality in a murine AIDS model by inhibiting apoptosis in the left ventricle

Cardiac involvement has been reported in as many as 45-55% of patients with human immunodeficiency virus (HIV) infection and acquired immune deficiency syndrome (AIDS), and significant cardiac morbidity is reported in 6-7% of HIV patients. We investigated the inhibitory effects of isothiocyanates (ITCs) on heart dysfunction and mortality by regulating apoptosis in the left ventricle of the heart in a murine AIDS model. Mice were divided into six groups: an uninfected group, an untreated LP-BM5 retrovirus-infected group, and four LP-BM5 retrovirus-infected groups treated with one of four ITCs (sulforaphane [SUL], indolo[3,2-b]carbazole, benzyl isothiocyanate [BITC], or phenethyl isothiocyanate [PEITC]). After 16 weeks, the median survival time of the LP-BM5 retrovirus-infected mice was 87 days, whereas that of the uninfected control group and all ITC treatment groups was over 112 days. SUL, PEITC, and BITC significantly inhibited apoptosis in the left ventricle by increasing the Bcl-2/Bax ratio compared with LP-BM5-infected mice. In addition, SUL and PEITC suppressed inducible nitric oxide synthase (iNOS) expression at both the mRNA and protein levels in the left ventricle of heart tissue infected with the LP-BM5 retrovirus by inactivating cytoplasmic nuclear factor κB (NF-κB). In conclusion, LP-BM5 retrovirus infection was related to survival of murine AIDS mice, and NF-κB-mediated iNOS expression may be an important mediator of left ventricle dysfunction of the heart. Furthermore, certain ITCs may have the potential to improve AIDS-related heart dysfunction due to their inhibition of apoptosis by decreasing iNOS and Bax expression through suppression of NF-κB.

The impact of HAART on cardiomyopathy among children and adolescents perinatally infected with HIV-1

OBJECTIVE

Previous studies of cardiomyopathy among children perinatally infected with HIV were conducted before the routine use of HAART. Nucleoside analogs [nucleoside reverse transcriptase inhibitors (NRTIs)], the backbone of HAART, have been associated with mitochondrial toxicity, which can lead to cardiomyopathy. We evaluated the association of HAART and specific NRTIs associated with mitochondrial toxicity, on development of cardiomyopathy among perinatally HIV-infected children.

DESIGN

Three thousand and thirty-five perinatally HIV-infected children enrolled in a US-based multicenter prospective cohort study were followed for cardiomyopathy, defined as a clinical diagnosis or initiation of digoxin, from 1993 to 2007.

METHODS

Cox models were used to estimate the effects of HAART and NRTIs on cardiomyopathy, identify predictors of cardiomyopathy among HAART users, and estimate the association between development of cardiomyopathy and mortality.

RESULTS

Ninety-nine cases of cardiomyopathy were identified over follow-up (incidence rate: 5.6 cases per 1000 person-years) at a median age of 9.4 years. HAART was associated with a 50% lower incidence of cardiomyopathy compared with no HAART use (95% confidence interval: 20%, 70%). Zalcitabine (ddC) use, however, was associated with an 80% higher incidence of cardiomyopathy. Among HAART users, older age at HAART initiation, ddC use before HAART initiation, initiating a HAART regimen containing zidovudine (ZDV), and a nadir CD4 percentage less than 15% were independently associated with a higher rate of cardiomyopathy. Cardiomyopathy was associated with a six-fold higher mortality rate.

CONCLUSION

HAART has dramatically decreased the incidence of cardiomyopathy among perinatally HIV-infected children. However, they remain at increased risk for cardiomyopathy and ongoing ZDV exposure may increase this risk.

Soluble mediators of inflammation in HIV and their implications for therapeutics and vaccine development

From early in the HIV epidemic it was appreciated that many inflammatory markers such as neopterin and TNF-α were elevated in patients with AIDS. With the advent of modern technology able to measure a broad array of cytokines, we now know that from the earliest points of infection HIV induces a cytokine storm. This review will focus on how cytokines are disturbed in HIV infection and will explore potential therapeutic uses of cytokines. These factors can be used directly as therapy during HIV infection, either to suppress viral replication or prevent deleterious immune effects of infection, such as CD4+ T cell depletion. Cytokines also show great promise as adjuvants in the development of HIV vaccines, which would be critical for the eventual control of the epidemic.

Human immunodeficiency virus & cardiovascular risk

Highly active antiretroviral therapy (HAART) significantly changed the prevalence of the cardiovascular manifestations of human immunodeficiency virus (HIV)/AIDS. In developed countries, a 30 per cent reduction in the prevalence of cardiomyopathy and pericardial effusion was observed, possibly related to a reduction of opportunistic infections and myocarditis. In developing countries, however, where the availablity of HAART is limited, and the pathogenic impact of nutritional factors is significant, a 32 per cent increase was seen in the prevalence of cardiomyopathy and related high mortality rate from congestive heart failure. Also, some HAART regimens in developed countries, especially those including protease inhibitors, may cause, in a high proportion of HIV-infected patients, a lipodystrophy syndrome that is associated with an increased risk of cardiovascular events related to a process of accelerated atherosclerosis. Careful cardiac screening is warranted for patients who are being evaluated for, or who are receiving HAART regimens, particularly for those with known underlying cardiovascular risk factors, according to the most recent clinical guidelines.

Diastolic dysfunction is associated with myocardial viral load in simian immunodeficiency virus-infected macaques

OBJECTIVE

To establish the relationship between HIV-induced cardiac diastolic dysfunction, immune responses, and virus replication in the heart using the simian immunodeficiency virus (SIV)/macaque model.

DESIGN

Cardiac diastolic dysfunction is common in HIV-infected individuals including asymptomatic patients and those treated with combination antiretroviral therapy. SIV-infected macaques develop cardiac dysfunction, serving as a useful model to establish mechanisms underlying HIV-induced cardiac dysfunction. To understand the relationship between functional cardiac impairment, viral replication in the heart, and associated host inflammatory responses, cardiac function was evaluated in SIV-infected macaques and functional decline was correlated with features of the host immune response and the extent of viral replication in both the myocardium and plasma.

METHODS

Cardiac function was evaluated longitudinally in 22 SIV-infected and eight uninfected macaques using mitral inflow and tissue Doppler echocardiography. Myocardial macrophage populations were evaluated by CD68 and CD163 immunostaining. SIV RNA levels in both myocardium and plasma were measured by qRT-PCR.

RESULTS

Echocardiographic abnormalities developed in SIV-infected macaques that closely resembled diastolic dysfunction reported in asymptomatic HIV-infected individuals. Although CD68 and CD163 were upregulated in the myocardium of SIV-infected animals, neither macrophage marker correlated with functional decline. SIV-induced diastolic dysfunction was strongly correlated with extent of SIV replication in the myocardium, implicating virus or viral proteins in the initiation and progression of cardiac dysfunction.

CONCLUSION

This study demonstrated a strong correlation between cardiac functional impairment and extent of SIV replication in the myocardium, suggesting that persistent viral replication in myocardial macrophages induces cardiomyocyte damage manifest as diastolic dysfunction.

Apoptosis in cardiovascular diseases: mechanism and clinical implications

Apoptosis is a tightly regulated, cell deletion process that plays an important role in various cardiovascular diseases, such as myocardial infarction, reperfusion injury, and heart failure. Since cardiomyocyte loss is the most important determinant of patient morbidity and mortality, fully understanding the regulatory mechanisms of apoptotic signaling is crucial. In fact, the inhibition of cardiac apoptosis holds promise as an effective therapeutic strategy for cardiovascular diseases. Caspase, a critical enzyme in the induction and execution of apoptosis, has been the main potential target for achieving anti-apoptotic therapy. Studies suggest, however, that a caspase-independent pathway may also play an important role in cardiac apoptosis, although the mechanism and potential significance of caspase-independent apoptosis in the heart remain poorly understood. Herein we discuss the role of apoptosis in various cardiovascular diseases, provide an update on current knowledge about the molecular mechanisms that govern apoptosis, and discuss the clinical implications of anti-apoptotic therapies.

Caspase-dependent induction of apoptosis in barramundi, Lates calcarifer (Bloch), muscle cells by grouper iridovirus

We recently reported that grouper iridovirus (GIV) can induce apoptosis in barramundi, Lates calcarifer, muscle (BM) and swim bladder (BSB) cell lines. In this paper, we further characterize the molecular mechanism underlying apoptotic death in BM cells triggered by GIV. DNA-laddering and apoptotic cells were observed in BM cells infected with UV-irradiated or untreated GIV but was absent in cells infected with heat-inactivated GIV, indicating the involvement of viral protein in the apoptosis event. In GIV-infected BM cells, the conversion of procaspase-3 to caspase-3 was evident and the level of caspase-8 and -9 increased as early as 30 min post-infection. When treated with a pancaspase inhibitor, the GIV-induced apoptosis event was abolished. These observations indicate that GIV-induced apoptosis is caspase-dependent, and that both the external and internal routes in the caspase-dependent pathway are likely involved in the apoptosis process.

A rat model of human immunodeficiency virus 1 encephalopathy using envelope glycoprotein gp120 expression delivered by SV40 vectors

Human immunodeficiency virus 1 (HIV-1) encephalopathy is thought to result in part from the toxicity of HIV-1 envelope glycoprotein gp120 for neurons. Experimental systems for studying the effects of gp120 and other HIV proteins on the brain have been limited to the acute effects of recombinant proteins in vitro or in vivo in simian immunodeficiency virus-infected monkeys. We describe an experimental rodent model of ongoing gp120-induced neurotoxicity in which HIV-1 envelope is expressed in the brain using an SV40-derived gene delivery vector, SV(gp120). When it is inoculated stereotaxically into the rat caudate putamen, SV(gp120) caused a partly hemorrhagic lesion in which neuron and other cell apoptosis continues for at least 12 weeks. Human immunodeficiency virus gp120 is expressed throughout this time, and some apoptotic cells are gp120 positive. Malondialdehyde and 4-hydroxynonenal assays indicated that there was lipid peroxidation in these lesions. Prior administration of recombinant SV40 vectors carrying antioxidant enzymes, copper/ zinc superoxide dismutase or glutathione peroxidase, was protective against SV(gp120)-induced oxidative injury and apoptosis. Thus, in vivo inoculation of SV(gp120) into the rat caudate putamen causes ongoing oxidative stress and apoptosis in neurons and may therefore represent a useful animal model for studying the pathogenesis and treatment of HIV-1 envelope-related brain damage.

HIV-1 viral genes and mitochondrial apoptosis

The mitochondrion is an organelle that regulates various cellular functions including the production of energy and programmed cell death. Aberrant mitochondrial function is often concomitant with various cytopathies and medical disorders. The mitochondrial membrane plays a key role in the induction of cellular apoptosis, and its destabilization, as triggered by both intracellular and extracellular stimuli, results in the release of proapoptotic factors into the cytosol. Not surprisingly, proteins from the human immunodeficiency virus type 1 (HIV) have been implicated in exploiting this organelle to promote the targeted depletion of key immune cells, which assists in viral evasion of the immune system and contributes to the characteristic global immunodeficiency observed during progression of disease. Here we review the mechanisms by which HIV affects the mitochondrion, and suggest that various viral-associated genes may directly regulate apoptotic cell death.

Human immunodeficiency virus (HIV) infects human arterial smooth muscle cells in vivo and in vitro: implications for the pathogenesis of HIV-mediated vascular disease

Human immunodeficiency virus (HIV) infection is associated with accelerated atherosclerosis and vasculopathy, although the mechanisms underlying these findings have not been determined. Hypotheses for these observations include: 1) an increase in the prevalence of established cardiac risk factors observed in HIV-infected individuals who are currently experiencing longer life expectancies; 2) the dyslipidemia reported with certain HIV anti-retroviral therapies; and/or 3) the proinflammatory effects of infiltrating HIV-infected monocytes/macrophages. An unexplored possibility is whether HIV itself can infect vascular smooth muscle cells (SMCs) and, by doing so, whether SMCs can accelerate vascular disease. Our studies demonstrate that human SMCs can be infected with HIV both in vivo and in vitro. The HIV protein p24 was detected by fluorescence confocal microscopy in SMCs from tissue sections of human atherosclerotic plaques obtained from HIV-infected individuals. Human SMCs could also be infected in vitro with HIV by a mechanism dependent on CD4, the chemokine receptors CXCR4 or CCR5, and endocytosis, resulting in a marked increase in SMC secretion of the chemokine CCL2/MCP-1, which has been previously shown to be a critical mediator of atherosclerosis. In addition, SMC proliferation appeared concentric to the vessel lumen, and minimal inflammation was detected, unlike typical atherosclerosis. Our data suggest that direct infection of human arterial SMCs by HIV represents a potential mechanism in a multifactorial paradigm to explain the exacerbated atherosclerosis and vasculopathy reported in individuals infected with HIV.

Diffuse-regressive alterations and apoptosis of myocytes: possible causes of myocardial dysfunction in HIV-related cardiomyopathy

OBJECTIVE

To determine the frequency of cardiac alterations in necropsies of AIDS patients in pre-HAART era and better understand the pathogenesis of HIV-related cardiomyopathy.

DESIGN

Retrospective study of 94 complete necropsies.

METHOD

Macroscopic, histopathologic (histochemical, immunohistochemical and in situ hybridization techniques) and ultra structural myocardial evaluation (23 cases).

RESULTS

Cardiac alterations were observed in 94.4%; 74% showed variable degrees of cardiac dilation not related to known cardiovascular diseases. Eighty-two percent (81.8%) of patients with biventricular dilation showed diffuse-regressive alterations (thinning and waving cardiomyocytes with increase of lipofuscin pigment granules). Myocarditis was diagnosed in 27 cases (28.7%), 16 (59.3%) of known etiology. The ultra structural study has revealed cardiomyocytes alterations (mitochondriosis, loss of myofibrils, increase in the amount of perinuclear-lipofuscin pigment granules) associated to activation signals of capillary-endothelial cells (enhancement of pseudopodia and transcellular channels). Cardiomyocytes' apoptosis was demonstrated at structural level in 10 (43.5%) patients; tumor necrosis factor alpha (TNF alpha) was detected in 17/18 cases.

CONCLUSIONS

This pioneer study described the association of histopathological and ultra structural findings (thinning and waving cardiomyocytes with increase of lipofuscin pigment granules, mitochondriosis and loss of myofibrils) with different degrees of cardiac-chamber dilation probably representing a spectrum of alterations that would lead to myocardial dysfunction and development of HIV-related cardiomyopathy. Cardiomyocytes' apoptosis observed at ultra structural level and demonstration of TNF alpha associated to described alterations suggest that this cytokine plays an important role in both negative-inotropic effect and capacity to induce apoptosis through death receptor-controlled pathway.

Protecting neurons from HIV-1 gp120-induced oxidant stress using both localized intracerebral and generalized intraventricular administration of antioxidant enzymes delivered by SV40-derived vectors

Human immunodeficiency virus-1 (HIV-1) is the most frequent cause of dementia in adults under 40. We sought to use gene delivery to protect from HIV-1-related neuron loss. Because HIV-1 envelope (Env) gp120 elicits oxidant stress and apoptosis in cultured neurons, we established reproducible parameters of Env-mediated neurotoxicity in vivo, then tested neuroprotection using gene delivery of antioxidant enzymes. We injected 100-500 ng mul(-1)gp120 stereotaxically into rat caudate-putamens (CP) and assayed brains for apoptosis by terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) 6-h to 14-day post-injection. Peak apoptosis occurred 1 day after injection of 250 and 500 ng microl(-1)gp120. TUNEL-positive cells mostly expressed neuronal markers (NeuroTrace), although some expressed CD68 and so were most likely microglial cells. Finally, we compared neuroprotection from gp120-induced apoptosis provided by localized and generalized intra-central nervous system (CNS) gene delivery. Recombinant SV40 vectors carrying Cu/Zn superoxide dismutase (SOD1) or glutathione peroxidase (GPx1) were injected into the CP, where gp120 was administered 4-24 weeks later. Alternatively, we inoculated the vector into the lateral ventricle (LV), with or without prior intraperitoneal (i.p.) administration of mannitol. Intracerebral injection of SV(SOD1) or SV(GPx1) significantly protected neurons from gp120-induced apoptosis throughout the 24-week study. Intraventricular vector administration protected from gp120 neurotoxicity comparably, particularly if preceded by mannitol i.p. Thus, HIV-1 gp120 is neurotoxic in vivo, and intracerebral or intra-ventricular administration of rSV40 vectors carrying antioxidant enzymes is neuroprotective. These findings suggest the potential utility of both localized and widespread gene delivery in treating neuroAIDS and other CNS diseases characterized by excessive oxidative stress.

Infection of cardiomyocytes and induction of left ventricle dysfunction by neurovirulent polytropic murine retrovirus

Viral infections of the heart are a causative factor of myocarditis as well as of sudden, unexpected deaths of children, yet the mechanisms of pathogenesis remain unclear, in part due to the relatively few animal models of virus-induced myocarditis. In the current study, we examined the ability of polytropic murine retroviruses to infect the heart and induce cardiac dysfunction. In situ hybridization and immunohistochemistry analysis detected virus-infected cardiomyocytes and macrophages in the heart. A significant decrease in left ventricle function, as measured by fractional shortening, was detected in mice infected with the neurovirulent retrovirus Fr98 but not in mice infected with the nonneurovirulent retrovirus Fr54. Virus infection was not associated with consistent findings of fibrosis or substantial cellular infiltrate. Fr98-induced left ventricle dysfunction was associated with a higher virus load, increased mRNA expression of the macrophage marker F4/80, increased chemokine production, and a small number of apoptotic cells in the heart.

Management of antiretroviral treatment-related complications

Antiretroviral therapy for HIV restores immune function, controls viral replication, decreases opportunistic infections, and extends lifespan to near-normal for infected individuals. However, successful HIV therapy has been accompanied by the emergence of treatment-related complications, with an impact not yet fully understood. This article reviews six common complications of antiretroviral therapy, including hyperlactatemia/lactic acidosis, hypersensitivity reactions, abnormal glucose metabolism, dyslipidemia, body composition changes, and cardiovascular disease. A comprehensive approach to management of antiretroviral-related complications includes awareness of (1) risk factors for adverse reactions, (2) clinical syndromes suggestive of an evolving complication, and (3) evidence-based monitoring and treatment strategies. Fluency in options for preventing and managing complications can provide maximal opportunity to balance treatment effects with quality of life.

Metabolic complications of HIV infection and its therapy in children

HIV infection has become a chronic disease in pediatric patients, with the potential for longer term survival and exposure to combination antiretroviral therapy for two decades longer than HIV-positive adults. However, body shape and metabolic abnormalities are frequently observed during antiretroviral therapy. These abnormalities have been poorly evaluated in HIV-infected children and their long-term consequences are not yet well assessed. This review summarizes our current understanding of the epidemiology, diagnosis and management of body shape abnormalities, dyslipidemia, disorders of glucose metabolism and vascular dysfunction in HIV-infected children and adolescents.

Glycoprotein 120 binding to CXCR4 causes p38-dependent primary T cell death that is facilitated by, but does not require cell-associated CD4

HIV-1 infection causes the depletion of host CD4 T cells through direct and indirect (bystander) mechanisms. Although HIV Env has been implicated in apoptosis of uninfected CD4 T cells via gp120 binding to either CD4 and/or the chemokine receptor 4 (CXCR4), conflicting data exist concerning the molecular mechanisms involved. Using primary human CD4 T cells, we demonstrate that gp120 binding to CD4 T cells activates proapoptotic p38, but does not activate antiapoptotic Akt. Because ligation of the CD4 receptor alone or the CXCR4 receptor alone causes p38 activation and apoptosis, we used the soluble inhibitors, soluble CD4 (sCD4) or AMD3100, to delineate the role of CD4 and CXCR4 receptors, respectively, in gp120-induced p38 activation and death. sCD4 alone augments gp120-induced death, suggesting that CXCR4 signaling is principally responsible. Supporting that model, AMD3100 reduces death caused by gp120 or by gp120/sCD4. Finally, prevention of gp120-CXCR4 interaction with 12G5 Abs blocks p38 activation and apoptosis, whereas inhibition of CD4-gp120 interaction with Leu-3a has no effect. Consequently, we conclude that gp120 interaction with CXCR4 is required for gp120 apoptotic effects in primary human T cells.

Heparin-mimicking sulfonic acid polymers as multitarget inhibitors of human immunodeficiency virus type 1 Tat and gp120 proteins

Human immunodeficiency virus (HIV) Tat and gp120 intriguingly share the feature of being basic peptides that, once released by HIV(+) cells, bind to polyanionic heparan sulfate proteoglycans (HSPGs) on target uninfected cells, contributing to the onset of AIDS-associated pathologies. To identify multitarget anti-HIV prodrugs, we investigated the gp120 and Tat antagonist potentials of a series of polyanionic synthetic sulfonic acid polymers (SSAPs). Surface plasmon resonance revealed that SSAPs inhibit with a competitive mechanism of action the binding of Tat and gp120 to surface-immobilized heparin, an experimental condition that resembles binding to cellular HSPGs. Accordingly, SSAPs inhibited HSPG-dependent cell internalization and the transactivating activity of Tat. Little is known about the binding of free gp120 to target cells. Here, we identified two classes of gp120 receptors expressed on endothelial cells, one of which was consistent with an HSPG-binding, low-affinity/high-capacity receptor that is inhibited by free heparin. SSAPs inhibited the binding of free gp120 to endothelial cells, as well as its capacity to induce apoptosis in the same cells. In all the assays, poly(4-styrenesulfonic acid) (PSS) proved to be the most potent antagonist of Tat and gp120. Accordingly, PSS bound both proteins with high affinity. In conclusion, SSAPs represent an interesting class of compounds that bind both gp120 and Tat and inhibit their HSPG-dependent cell surface binding and pathological effects. As these activities contribute to both AIDS progression and associated pathologies, SSAPs can be considered prototypic molecules for the development of multitarget drugs for the treatment of HIV infection and AIDS-associated pathologies.

Cytokines in HIV-associated cardiomyopathy

Among the multiple cardiac manifestations occurring in HIV-infected patients, cardiomyopathy is one of the most challenging. Its incidence has only slightly decreased since the introduction of highly active antiretroviral therapy (HAART). Also, its pathogenesis remains relatively unclear. Although several studies demonstrated the presence of HIV genome in the heart of patients, more recent developments found that viral infection plays an indirect role only, as well as they recognized the contribution of proinflammatory cytokines in the progression of the disease. Experimental studies on animals and cultured myocytes have established the signalling pathway triggered by proinflammatory cytokines in heart failure and cardiomyopathy. Tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1) and IL-6 promote expression of inducible nitric oxide synthase (iNOS) in cardiomyocytes through activation of p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor kappaB (NFkappaB). TNF-alpha and high concentrations of NO also induce cardiomyocyte apoptosis by TNF type 1 receptor activation. This biological framework, which is also involved in progression of cardiomyopathy in humans, is more pronounced in HIV-infected patients, in whom proinflammatory cytokines TNF-alpha, IL-1 and IL-6 are increased, resulting in an enhanced expression of cardiac iNOS, especially in patients with a low CD4 T cell count. This may account for the worse outcome of heart failure in HIV-infected patients. However, there are only few data today to support future therapeutic implications of cytokines antagonism in treatment of HIV-infected patients with cardiomyopathy. Whether modulation of TNF production or selective inhibition of p38 MAPK pathway could be useful approaches remains uncertain.

Cell suicide and caspases

Programmed cell death or apoptosis is a well regulated physiological form of cellular autodestruction. It plays an essential role in embryonic development, homeostasis, remodeling, surveillance, and host defense mechanisms. Conversely dysregulation of apoptosis, resulting in either too less or excessive cell death is implicated in pathogenesis of stroke, myocardial infarction, neurodegenerative diseases, cancer and autoimmmune disorders. Apoptosis is coordinated by a family of cysteine proteinases called caspases, which dismantle the cell by targeting panoply of proteins. The mammalian caspase family contains 14 members, a subset participates in cellular demise and the remaining are involved in the processing of pro-inflammatory cytokines. We have tried to develop a simplified picture of basic apoptotic mechanisms on the basis of recent insights into the area.

Pathogenic role of anti-β2-glycoprotein I antibodies on human placenta: functional effects related to implantation and roles of heparin

Most of the clinical manifestations of the antiphospholipid syndrome (APS) can be related to thrombotic events; however, placental thrombosis cannot explain all of the pregnancy complications that occur in women with this syndrome. In this regard, it has been hypothesized that antiphospholipid (aPL) antibodies can directly attack trophoblasts, but it is still unclear what pathogenetic mechanisms play a role and which aPL antibodies subpopulations are involved. Although it has been assumed that aPL antibodies are directed against anionic phospholipids (PLs), current advances in the field suggest that antibodies to PL-binding plasma protein such as beta2-glycoprotein-I (beta2-GPI) are the clinically relevant aPL antibodies. It appears that following the attachment of beta2-GPI to PLs, both molecules undergo conformational changes that result in the exposure of cryptic epitopes within the structure of beta2-GPI allowing the subsequent binding of antibodies. aPL antibodies detected by anti-beta2-GPI assays are associated with fetal loss. However, there is still debate on how the antibodies might induce the obstetrical manifestations. The significantly improved outcome of pregnancies treated with heparin has stimulated interest in the drug's mechanisms of action. Several mechanisms could explain its beneficial effects, because in addition to a direct effect of heparin on the coagulation cascade, it might protect pregnancies by reducing the binding of aPL antibodies, reducing inflammation, facilitating implantation and/or inhibiting complement activation. Further investigations are needed to better understand how aPL antibodies induce obstetric complications and to better clarify the functional role of heparin in the human placenta leading to more successful therapeutic options.

Antioxidant enzyme gene delivery to protect from HIV-1 gp120-induced neuronal apoptosis

Human immunodeficiency virus-1 (HIV-1) infection in the central nervous system (CNS) may lead to neuronal loss and progressively deteriorating CNS function: HIV-1 gene products, especially gp120, induce free radical-mediated apoptosis. Reactive oxygen species (ROS), are among the potential mediators of these effects. Neurons readily form ROS after gp120 exposure, and so might be protected from ROS-mediated injury by antioxidant enzymes such as Cu/Zn-superoxide dismutase (SOD1) and/or glutathione peroxidase (GPx1). Both enzymes detoxify oxygen free radicals. As they are highly efficient gene delivery vehicles for neurons, recombinant SV40-derived vectors were used for these studies. Cultured mature neurons derived from NT2 cells and primary fetal neurons were transduced with rSV40 vectors carrying human SOD1 and/or GPx1 cDNAs, then exposed to gp120. Apoptosis was measured by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) assay. Transduction efficiency of both neuron populations was >95%, as assayed by immunostaining. Transgene expression was also ascertained by Western blotting and direct assays of enzyme activity. Gp120 induced apoptosis in a high percentage of unprotected NT2-N. Transduction with SV(SOD1) and SV(GPx1) before gp120 challenge reduced neuronal apoptosis by >90%. Even greater protection was seen in cells treated with both vectors in sequence. Given singly or in combination, they protect neuronal cells from HIV-1-gp120 induced apoptosis. We tested whether rSV40 s can deliver antioxidant enzymes to the CNS in vivo: intracerebral injection of SV(SOD1) or SV(GPx1) into the caudate putamen of rat brain yielded excellent transgene expression in neurons. In vivo transduction using SV(SOD1) also protected neurons from subsequent gp120-induced apoptosis after injection of both into the caudate putamen of rat brain. Thus, SOD1 and GPx1 can be delivered by SV40 vectors in vitro or in vivo. This approach may merit consideration for therapies in HIV-1-induced encephalopathy.

Highly Active Antiretroviral Therapy-Associated Metabolic Syndrome and Cardiovascular Risk

The introduction of highly active antiretroviral therapy (HAART) has significantly modified the course of human immunodeficiency virus (HIV) disease, with longer survival and improved quality of life of HIV-infected subjects. However, HAART regimens, especially those including protease inhibitors, have been shown to cause in a high proportion of HIV-infected patients a metabolic syndrome (lipodystrophy/lipoatrophy, dyslipidemia, type 2 diabetes mellitus, insulin resistance) that may be associated with an increased risk of cardiovascular disease (coronary artery disease and stroke). A careful stratification of the cardiovascular risk and cardiovascular monitoring of patients under HAART is needed according to the most recent clinical guidelines.

SIV-associated myocarditis: viral and cellular correlates of inflammation severity

Myocarditis is a common finding in HIV-infected people. Cardiac inflammatory lesions and functional abnormalities similar to those documented in HIV infection are frequently seen in SIV infection of rhesus monkeys, suggesting a shared disease mechanism. A retrospective analysis of cardiac tissue collected at necropsy was performed to assess correlates of myocardial inflammation in SIV-infected rhesus monkeys. Intramyocardial SIV-infected cells were identified in 7 of 21 hearts from SIV-infected animals, with viral protein consistently colocalizing with the macrophage marker HAM 56. Productively infected cells occurred in low numbers, and did not correlate with the presence or quantity of inflammation or necrosis. Intramyocardial CMV was identified in 6 of 21 hearts from SIV+ animals, but also did not correlate with the presence or quantity of inflammation or necrosis. In contrast, T cell infiltration correlated inversely with DC-SIGN+ cell numbers, which occurred in significantly higher numbers in SIV+ animals with histologically normal myocardium than in SIV+ animals with active or borderline myocarditis or in uninfected controls (p < 0.001), suggesting an important immunoregulatory role for this population within the myocardium.

Mechanisms of apoptosis induction by the HIV-1 envelope

The envelope glycoprotein complex (Env) of human immunodeficiency virus-1 (HIV-1) can induce apoptosis by a cornucopia of distinct mechanisms. A soluble Env derivative, gp120, can kill cells through signals that are transmitted by chemokine receptors such as CXCR4. Cell surface-bound Env (gp120/gp41), as present on the plasma membrane of HIV-1-infected cells, can kill uninfected bystander cells expressing CD4 and CXCR4 (or similar chemokine receptors, depending on the Env variant) by at least three different mechanisms. First, a transient interaction involving the exchange of lipids between the two interacting cells ('the kiss of death') may lead to the selective death of single CD4-expressing target cells. Second, fusion of the interacting cells may lead to the formation of syncytia which then succumb to apoptosis in a complex pathway involving the activation of several kinases (cyclin-dependent kinase-1, Cdk1; checkpoint kinase-2, Chk2; mammalian target of rapamycin, mTOR; p38 mitogen-activated protein kinase, p38 MAPK; inhibitor of NF-kappaB kinase, IKK), as well as the activation of several transcription factors (NF-kappaB, p53), finally resulting in the activation of the mitochondrial pathway of apoptosis. Third, if the Env-expressing cell is at an early stage of imminent apoptosis, its fusion with a CD4-expressing target cell can precipitate the death of both cells, through a process that may be considered as contagious apoptosis and which does not involve Cdk1, mTOR, p38 nor p53, yet does involve mitochondria. Activation of some of the above- mentioned lethal signal transducers have been detected in patients' tissues, suggesting that HIV-1 may indeed trigger apoptosis through molecules whose implication in Env-induced killing has initially been discovered in vitro.

Highly Active Antiretroviral Therapy–Associated Metabolic Syndrome: Pathogenesis and Cardiovascular Risk*

The introduction of highly active antiretroviral therapy (HAART) has significantly modified the course of HIV disease, with longer survival and improved quality of life of HIV-infected subjects. However, HAART regimens, especially those including protease inhibitors (PIs) have been shown to cause in a high proportion of HIV-infected patients a metabolic syndrome that may be associated with an increased risk of cardiovascular disease (about 1.4 cardiac events per 1,000 years of therapy according to the Framingham score). Metabolic features associated with somatic changes (lipodystrophy/lipoatrophy) include dyslipidemia (about 70% of patients), insulin resistance (elevated C-peptide and insulin), type 2 diabetes mellitus (8%-10% of the patients), hypertension (up to 75% of patients), coagulation abnormalities (25% of patients), lactic acidemia, and elevated hepatic transaminases (nonalcoholic steatohepatitis). HAART-associated metabolic syndrome is an increasingly recognized clinical entity. A better understanding of the molecular mechanisms responsible for this syndrome will lead to the discovery of new drugs that will reduce the cardiovascular risk in patients under HAART. A careful stratification of the cardiovascular risk and cardiovascular monitoring of patients under HAART is needed according to the most recent clinical guidelines.