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

Simian immunodeficiency virus-infected rhesus macaques with AIDS co-develop cardiovascular pathology and encephalitis

Despite effective antiretroviral therapy, HIV co-morbidities remain where central nervous system (CNS) neurocognitive disorders and cardiovascular disease (CVD)-pathology that are linked with myeloid activation are most prevalent. Comorbidities such as neurocogntive dysfunction and cardiovascular disease (CVD) remain prevalent among people living with HIV. We sought to investigate if cardiac pathology (inflammation, fibrosis, cardiomyocyte damage) and CNS pathology (encephalitis) develop together during simian immunodeficiency virus (SIV) infection and if their co-development is linked with monocyte/macrophage activation. We used a cohort of SIV-infected rhesus macaques with rapid AIDS and demonstrated that SIV encephalitis (SIVE) and CVD pathology occur together more frequently than SIVE or CVD pathology alone. Their co-development correlated more strongly with activated myeloid cells, increased numbers of CD14+CD16+ monocytes, plasma CD163 and interleukin-18 (IL-18) than did SIVE or CVD pathology alone, or no pathology. Animals with both SIVE and CVD pathology had greater numbers of cardiac macrophages and increased collagen and monocyte/macrophage accumulation, which were better correlates of CVD-pathology than SIV-RNA. Animals with SIVE alone had higher levels of activated macrophage biomarkers and cardiac macrophage accumulation than SIVnoE animals. These observations were confirmed in HIV infected individuals with HIV encephalitis (HIVE) that had greater numbers of cardiac macrophages and fibrosis than HIV-infected controls without HIVE. These results underscore the notion that CNS and CVD pathologies frequently occur together in HIV and SIV infection, and demonstrate an unmet need for adjunctive therapies targeting macrophages.

Functional Cardiovascular Characterization of the Common Marmoset (Callithrix jacchus)

Appropriate cardiovascular animal models are urgently needed to investigate genetic, molecular, and therapeutic approaches, yet the translation of results from the currently used species is difficult due to their genetic distance as well as their anatomical or physiological differences. Animal species that are closer to the human situation might help to bridge this translational gap. The common marmoset (Callithrix jacchus) is an interesting candidate to investigate certain heart diseases and cardiovascular comorbidities, yet a basic functional characterization of its hemodynamic system is still missing. Therefore, cardiac functional analyses were performed by utilizing the invasive intracardiac pressure-volume loops (PV loop) system in seven animals, magnetic resonance imaging (MRI) in six animals, and echocardiography in five young adult male common marmosets. For a direct comparison between the three methods, only data from animals for which all three datasets could be acquired were selected. All three modalities were suitable for characterizing cardiac function, though with some systemic variations. In addition, vena cava occlusions were performed to investigate the load-independent parameters collected with the PV loop system, which allowed for a deeper analysis of the cardiac function and for a more sensitive detection of the alterations in a disease state, such as heart failure or certain cardiovascular comorbidities.

Echocardiographic assessment of left cardiac structure and function in antiretroviral therapy (ART)-naïve people living with HIV/AIDS

BACKGROUND

Patients with human immunodeficiency virus (HIV) are at a significantly higher risk of cardiovascular disease (CVD) compared to HIV-negative people. Left heart dysfunction is the most common cardiac complication in people living with HIV/acquired immune deficiency syndrome (PLWHA), and diastolic dysfunction is an important predictor of cardiovascular events. The aims of this study were (1) to detect changes in left cardiac structure and function in antiretroviral therapy (ART)-naive PLWHA using echocardiography; and (2) to investigate the risk factors for the development of left ventricular diastolic dysfunction (LVDD) in ART-naive PLWHA.

METHODS

We retrospectively included 105 ART-naïve PLWHA and included 90 healthy subjects as controls to compare the differences in left heart structure and function between the two groups. Univariate and multifactorial logistic regression were employed to explore the risk factors of the development of LVDD in ART-naive PLWHA.

RESULTS

The left ventricular end-diastolic internal diameter (LVEDD), left ventricular mass index (LVMI), and left atrial volume index (LAVI) were significantly greater in PLWHA than in controls (p < .05). The E/A ratio, lateral e' velocity, and mitral deceleration time were significantly lower in PLWHA than in controls (p < .05). Average E/e' ratio was significantly higher in PLWHA than in controls (p < .05). Left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were not significantly different between PLWHA and controls (p > .05). Multifactorial logistic regression analysis showed that age, body mass index (BMI), and CD4⁺ count <200 cells/μL were independent risk factors for LVDD in ART-naive PLWHA (OR = 1.781, 1.228, 3.683, p < .05).

CONCLUSIONS

Left ventricular systolic function did not differ between PLWHA and controls, and left ventricular diastolic function was lower in PLWHA than in controls. Age, BMI, and CD4⁺ count were independent factors affecting LVDD in ART-naive PLWHA.

Right ventricular load and contractility in HIV-associated pulmonary hypertension

Background

People living with human immunodeficiency virus (PLWH) are at risk of developing pulmonary hypertension (PH) and right ventricular (RV) dysfunction, but understanding of the relationship of RV function to afterload (RV-PA coupling) is limited. We evaluated the clinical and hemodynamic characteristics of human immunodeficiency virus (HIV)-associated PH.

Methods

We performed a retrospective review of patients with a diagnosis of HIV undergoing right heart catheterization (RHC) from 2000–2016 in a tertiary care center. Inclusion criteria were diagnosis of HIV, age ≥ 18 years and availability of RHC data. PH was classified as either pulmonary arterial hypertension (PAH; mean pulmonary arterial pressure [mPAP] ≥ 25mmHg with pulmonary artery wedge pressure [PAWP] ≤ 15mmHg) or pulmonary venous hypertension (PVH; mPAP ≥ 25mmHg with PAWP > 15). We collected demographics, CD4 cell count, HIV viral load, RHC and echocardiographic data. The single beat method was used to calculate RV-PA coupling from RHC.

Results

Sixty-two PLWH with a clinical likelihood for PH underwent RHC. Thirty-two (52%) met PH criteria (15 with PAH, 17 with PVH). Average time from diagnosis of HIV to diagnosis of PH was 11 years. Eleven of 15 individuals with PAH were on antiretroviral therapy (ART) while all 17 patients with PVH were on ART. Compared to PLWH without PH, those with PH had an increased likelihood of having a detectable HIV viral load and lower CD4 cell counts. PLWH with PAH or PVH had increased RV afterload with normal RV contractility, and preserved RV-PA coupling.

Conclusion

PLWH with PH (PAH or PVH) were more likely to have a detectable HIV viral load and lower CD4 count at the time of RHC. PLWH with PAH or PVH had increased RV afterload, normal RV contractility, with preserved RV-PA coupling suggestive of an early onset, mild, and compensated form of PH. These results should be confirmed in larger studies.

Left ventricular diastolic dysfunction in HIV-uninfected infants exposed in utero to antiretroviral therapy

OBJECTIVES

To longitudinally measure LV diastolic function in HIV-exposed but uninfected (HEU) children perinatally exposed to ART.

DESIGN

HEU children who were perinatally exposed to antiretroviral therapy (ART) may be at risk for adverse cardiac effects. We have previously reported that those children have decreased left ventricular (LV) mass, dimension, and septal thickness with increased contractility.

METHODS

Serial echocardiograms were obtained at specific times from birth to 48 months from two groups of HIV-uninfected children: 148 HIV-negative children who were perinatally exposed to ART and 130 non-ART-exposed HIV-unexposed healthy controls. The following LV diastolic indices were obtained: mitral valve early and late diastolic velocity (E and A), tissue Doppler-derived LV-free wall and septal early diastolic velocity (LV e' and sep e').

RESULTS

All echocardiographic indices were significantly different in ART-exposed children compared with ART-unexposed healthy controls. Both E and A were overall lower at all ages by 8.28 cm/s (P = 0.0002) and 13.46 cm/s (P < 0.0001) respectively. E/A ratio was higher by 0.27, 0.46, and 0.28 units at birth, 1 year and 2 years of age, respectively (all P ≤ 0.01). Moreover, LV e' and sep e' were overall lower at all ages by 0.84 cm/s (P = 0.01) and 0.47 cm/s (P = 0.02), respectively.

CONCLUSION

Children who were exposed to ART in utero have subclinical yet significant differences in specific LV diastolic indices. Follow-up with serial echocardiograms are recommended in this population to further assess the potential cardiac toxicity of perinatal exposure to ART.

HIV-Associated Cardiovascular Disease: Role of Connexin 43

Chronic HIV infection due to effective antiretroviral treatment has resulted in a broad range of clinical complications, including accelerated heart disease. Individuals with HIV infection have a 1.5 to 2 times higher incidence of cardiovascular diseases than their uninfected counterparts; however, the underlying mechanisms are poorly understood. To explore the link between HIV infection and cardiovascular diseases, we used postmortem human heart tissues obtained from HIV-infected and control uninfected individuals to examine connexin 43 (Cx43) expression and distribution and HIV-associated inflammation. Here, we demonstrate that Cx43 is dysregulated in the hearts of HIV-infected individuals. In all HIV heart samples analyzed, there were areas where Cx43 was overexpressed and found along the lateral membrane of the cardiomyocyte and in the intercalated disks. Areas of HIV tissue with anomalous Cx43 expression and localization also showed calcium overload, sarcofilamental atrophy, and accumulation of collagen. All these changes were independent of viral replication, CD4 counts, inflammation, and type of antiretroviral treatment. Overall, we propose that HIV infection increases Cx43 expression in heart, resulting in tissue damage that likely contributes to the high rates of cardiovascular disease in HIV-infected individuals.

Direct Targeting of Macrophages With Methylglyoxal-Bis-Guanylhydrazone Decreases SIV-Associated Cardiovascular Inflammation and Pathology

BACKGROUND

Despite effective combination antiretroviral therapy, HIV-infected individuals develop comorbidities, including cardiovascular disease, where activated macrophages play a key role. To date, few therapies target activated monocytes and macrophages.

METHODS

We evaluated a novel oral form of the polyamine biosynthesis inhibitor methylglyoxal-bis-guanylhydrazone (MGBG) on cardiovascular inflammation, carotid artery intima-media thickness (cIMT), and fibrosis in a simian immunodeficiency virus infection model of AIDS. Eleven simian immunodeficiency virus-infected animals received MGBG (30 mg/kg) once daily and 8 received a placebo control both beginning at 21 days postinfection (dpi). Animals were time sacrificed at 49 days post infection (dpi), when their matched placebo controls developed AIDS (63, 70, 77, 80), or at the study end-point (84 dpi). Aorta, carotid artery, and cardiac tissues were analyzed. Quantitative analyses of macrophage populations and T lymphocytes were done and correlated with cIMT and fibrosis.

RESULTS

MGBG treatment resulted in 2.19-fold (CD163), 1.86-fold (CD68), 2.31-fold (CD206), and 2.12-fold (MAC387) decreases in macrophages in carotid arteries and significant 2.07-fold (CD163), 1.61-fold (CD68), 1.95-fold (MAC387), and 1.62-fold (CD206) decreases in macrophages in cardiac tissues. cIMT (1.49-fold) and fibrosis (2.05-fold) also were significantly decreased with MGBG treatment. Numbers of macrophage and the degree of fibrosis in treated animals were similar to uninfected animals. A positive correlation between decreased macrophage in the carotid artery and cIMT, and cardiac macrophages and fibrosis was found.

CONCLUSIONS

These data demonstrate that directly targeting macrophages with MGBG can reduce cardiovascular inflammation, cIMT, and fibrosis. They suggest that therapies targeting macrophages with HIV could be used in conjunction with combination antiretroviral therapy.

Tracking Epidermal Nerve Fiber Changes in Asian Macaques: Tools and Techniques for Quantitative Assessment

Quantitative assessment of epidermal nerve fibers (ENFs) has become a widely used clinical tool for the diagnosis of small fiber neuropathies such as diabetic neuropathy and human immunodeficiency virus-associated sensory neuropathy (HIV-SN). To model and investigate the pathogenesis of HIV-SN using simian immunodeficiency virus (SIV)-infected Asian macaques, we adapted the skin biopsy and immunostaining techniques currently employed in human patients and then developed two unbiased image analysis techniques for quantifying ENF in macaque footpad skin. This report provides detailed descriptions of these tools and techniques for ENF assessment in macaques and outlines important experimental considerations that we have identified in the course of our long-term studies. Although initially developed for studies of HIV-SN in the SIV-infected macaque model, these methods could be readily translated to a range of studies involving peripheral nerve degeneration and neurotoxicity in nonhuman primates as well as preclinical investigations of agents aimed at neuroprotection and regeneration.

Quantitation of Productively Infected Monocytes and Macrophages of Simian Immunodeficiency Virus-Infected Macaques

Despite the success of combined antiretroviral therapy (ART), human immunodeficiency virus (HIV) infection remains a lifelong infection because of latent viral reservoirs in infected patients. The contribution of CD4⁺ T cells to infection and disease progression has been extensively studied. However, during early HIV infection, macrophages in brain and other tissues are infected and contribute to tissue-specific diseases, such as encephalitis and dementia in brain and pneumonia in lung. The extent of infection of monocytes and macrophages has not been rigorously assessed with assays comparable to those used to study infection of CD4⁺ T cells and to evaluate the number of CD4⁺ T cells that harbor infectious viral genomes. To assess the contribution of productively infected monocytes and macrophages to HIV- and simian immunodeficiency virus (SIV)-infected cells in vivo, we developed a quantitative virus outgrowth assay (QVOA) based on similar assays used to quantitate CD4⁺ T cell latent reservoirs in HIV- and SIV-infected individuals in whom the infection is suppressed by ART. Myeloid cells expressing CD11b were serially diluted and cocultured with susceptible cells to amplify virus. T cell receptor β RNA was measured as a control to assess the potential contribution of CD4⁺ T cells in the assay. Virus production in the supernatant was quantitated by quantitative reverse transcription-PCR. Productively infected myeloid cells were detected in blood, bronchoalveolar lavage fluid, lungs, spleen, and brain, demonstrating that these cells persist throughout SIV infection and have the potential to contribute to the viral reservoir during ART.

IMPORTANCE Infection of CD4⁺ T cells and their role as latent reservoirs have been rigorously assessed; however, the frequency of productively infected monocytes and macrophages in vivo has not been similarly studied. Myeloid cells, unlike lymphocytes, are resistant to the cytopathic effects of HIV. Moreover, tissue-resident macrophages have the ability to self-renew and persist in the body for months to years. Thus, tissue macrophages, once infected, have the characteristics of a potentially stable viral reservoir. A better understanding of the number of productively infected macrophages is crucial to further evaluate the role of infected myeloid cells as a potential viral reservoir. In the study described here we compared the frequency of productively infected CD4⁺ T cells and macrophages in an SIV-infected macaque model. We developed a critical assay that will allow us to quantitate myeloid cells containing viral genomes that lead to productive infection in SIV-infected macaques and assess the role of macrophages as potential reservoirs.

Anti-α4 Integrin Antibody Blocks Monocyte/Macrophage Traffic to the Heart and Decreases Cardiac Pathology in a SIV Infection Model of AIDS

Background

Cardiovascular disease (CVD), myocarditis and fibrosis are comorbidities of HIV⁺ individuals on durable antiretroviral therapy (ART). Although mechanisms for these vary, monocytes/macrophages are increasingly demonstrated to be key players.

Methods and Results

We directly blocked monocyte/macrophage traffic to the heart in an SIV model of AIDS using an anti-alpha-4 integrin antibody (natalizumab). Nineteen Rhesus macaques were SIVmac251 infected and CD8-lymphocyte depleted for the development of rapid AIDS. Ten animals received natalizumab once a week, for 3 weeks, and were sacrificed 1 week later. Six animals began treatment at the time of infection (early) and the remaining 4 began treatment 28 days post-infection (late), a time point we have previously established when significant cardiac inflammation occurs. Nine animals were untreated controls; of these, 3 were sacrificed early and 6 were sacrificed late. At necropsy, we found decreased SIV-associated cardiac pathology in late natalizumab-treated animals, compared to untreated controls. Early and late treatment resulted in significant reductions in numbers of CD163⁺ and CD68⁺ macrophages in cardiac tissues, compared to untreated controls, and a trend in decreasing numbers of newly recruited MAC387⁺ and BrdU⁺ (recruited) monocytes/macrophages. In late treated animals, decreased macrophage numbers in cardiac tissues correlated with decreased fibrosis. Early and late treatment resulted in decreased cardiomyocyte damage.

Conclusions

These data demonstrate a role for macrophages in the development of cardiac inflammation and fibrosis, and suggest that blocking monocyte/macrophage traffic to the heart can alleviate HIV- and SIV-associated myocarditis and fibrosis. They underscore the importance of targeting macrophage activation and traffic as an adjunctive therapy in HIV infection.

Molecular imaging of inflammation in the ApoE -/- mouse model of atherosclerosis with IodoDPA

BACKGROUND

Atherosclerosis is a common and serious vascular disease predisposing individuals to myocardial infarction and stroke. Intravascular plaques, the pathologic lesions of atherosclerosis, are largely composed of cholesterol-laden luminal macrophage-rich infiltrates within a fibrous cap. The ability to detect those macrophages non-invasively within the aorta, carotid artery and other vessels would allow physicians to determine plaque burden, aiding management of patients with atherosclerosis.

METHODS AND RESULTS

We previously developed a low-molecular-weight imaging agent, [(125)I]iodo-DPA-713 (iodoDPA), which selectively targets macrophages. Here we use it to detect both intravascular macrophages and macrophage infiltrates within the myocardium in the ApoE -/- mouse model of atherosclerosis using single photon emission computed tomography (SPECT). SPECT data were confirmed by echocardiography, near-infrared fluorescence imaging and histology. SPECT images showed focal uptake of radiotracer at the aortic root in all ApoE -/- mice, while the age-matched controls were nearly devoid of radiotracer uptake. Focal radiotracer uptake along the descending aorta and within the myocardium was also observed in affected animals.

CONCLUSIONS

IodoDPA is a promising new imaging agent for atherosclerosis, with specificity for the macrophage component of the lesions involved.

Elevated numbers of CD163+ macrophages in hearts of simian immunodeficiency virus-infected monkeys correlate with cardiac pathology and fibrosis

The role of macrophage activation, traffic, and accumulation on cardiac pathology was examined in 23 animals. Seventeen animals were simian immunodeficiency virus (SIV) infected, 12 were CD8 lymphocyte depleted, and the remaining six were uninfected controls (two CD8 lymphocyte depleted, four nondepleted). None of the uninfected controls had cardiac pathology. One of five (20%) SIV-infected, non-CD8 lymphocyte-depleted animals had minor cardiac pathology with increased numbers of macrophages in ventricular tissue compared to controls. Seven of the 12 (58%) SIV-infected, CD8 lymphocyte-depleted animals had cardiac pathology in ventricular tissues, including macrophage infiltration and myocardial degeneration. The extent of fibrosis (measured as the percentage of collagen per tissue area) was increased 41% in SIV-infected, CD8 lymphocyte-depleted animals with cardiac pathology compared to animals without pathological abnormalities. The number of CD163+ macrophages increased significantly in SIV-infected, CD8 lymphocyte-depleted animals with cardiac pathology compared to ones without pathology (1.66-fold) and controls (5.42-fold). The percent of collagen (percentage of collagen per total tissue area) positively correlated with macrophage numbers in ventricular tissue in SIV-infected animals. There was an increase of BrdU+ monocytes in the heart during late SIV infection, regardless of pathology. These data implicate monocyte/macrophage activation and accumulation in the development of cardiac pathology with SIV infection.

TGFβ-Mediated Downregulation of Thrombopoietin Is Associated With Platelet Decline in Asymptomatic SIV Infection

BACKGROUND

Thrombocytopenia is a known consequence of HIV infection, and decreased production of platelets has been previously implicated in the pathogenesis of platelet decline during asymptomatic infection. Thrombopoietin (THPO) drives platelet production by stimulating the maturation of bone marrow megakaryocytes and can be transcriptionally downregulated by cytokines that are increased during infection such as transforming growth factor β (TGFβ) and platelet factor 4 (pf4).

DESIGN

To determine whether transcriptional downregulation of THPO contributed to decreased platelet production during asymptomatic infection in the simian immunodeficiency virus (SIV)/macaque model of HIV, we compared hepatic THPO mRNA levels to platelet number and megakaryocyte density. To identify potential inhibitory factors that decrease THPO transcription during asymptomatic infection, we measured TGFβ and pf4 plasma levels. To determine whether combined antiretroviral therapy (cART) could correct platelet decline by altering cytokine levels, we measured TGFβ and pf4 in cART-treated SIV-infected macaques and compared these values to cART-untreated SIV-infected macaques.

RESULTS

Hepatic THPO transcription was downregulated during asymptomatic SIV infection concurrent with platelet decline. Hepatic THPO mRNA levels correlated with bone marrow megakaryocyte density. In contrast, plasma TGFβ levels were inversely correlated with hepatic THPO transcription and bone marrow megakaryocyte density. With cART treatment, plasma TGFβ levels and platelet count returned to values similar to those in uninfected macaques.

CONCLUSIONS

TGFβ-mediated downregulation of hepatic THPO may lead to decline in platelet number during asymptomatic SIV infection, and cART may prevent platelet decline by normalizing plasma TGFβ levels.

Loss of corneal sensory nerve fibers in SIV-infected macaques: an alternate approach to investigate HIV-induced PNS damage

Peripheral neuropathy is the most frequent neurological complication of HIV infection, affecting more than one-third of infected patients, including patients treated with antiretroviral therapy. Although emerging noninvasive techniques for corneal nerve assessments are increasingly being used to diagnose and monitor peripheral neuropathies, corneal nerve alterations have not been characterized in HIV. Here, to determine whether SIV infection leads to corneal nerve fiber loss, we immunostained corneas for the nerve fiber marker βIII tubulin. We developed and applied both manual and automated methods to measure nerves in the corneal subbasal plexus. These counting methods independently indicated significantly lower subbasal corneal nerve fiber density among SIV-infected animals that rapidly progressed to AIDS compared with slow progressors. Concomitant with decreased corneal nerve fiber density, rapid progressors had increased levels of SIV RNA and CD68-positive macrophages and expression of glial fibrillary acidic protein by glial satellite cells in the trigeminal ganglia, the location of the neuronal cell bodies of corneal sensory nerve fibers. In addition, corneal nerve fiber density was directly correlated with epidermal nerve fiber length. These findings indicate that corneal nerve assessment has great potential to diagnose and monitor HIV-induced peripheral neuropathy and to set the stage for introducing noninvasive techniques to measure corneal nerve fiber density in HIV clinical settings.

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.

Immunopathogenesis of simian immunodeficiency virus infection in nonhuman primates

PURPOSE OF REVIEW

Soon after the discovery of HIV-infected humans, rhesus macaques in a colony at the New England Primate Research Center showed similar signs of a progressive immune suppression. The discovery of the simian immunodeficiency virus (SIV)-associated disease opened the door to study an AIDS-like illness in nonhuman primates (NHP). Even after 3 decades, this animal model remains an invaluable tool to provide a greater insight into HIV immunopathogenesis. In this review, recent progress in deciphering pathways of immunopathogenesis in SIV-infected NHP is discussed.

RECENT FINDINGS

The immense diversity of mutations in SIV stocks prepared at different laboratories has recently been realized. The massive expansion of the enteric virome is a key finding in SIV-induced immunopathogenesis. Defining the function of host restriction factors, like the recently discovered SAMHD1, helps to evaluate the impact of the innate immune responses on virus replication. Utilization of pyrosequencing and defining molecular mechanisms of major histocompatibility complex (MHC) class I restriction helps to understand how the virus evades CD8 T-cell responses. The definition of MHC class I molecules in different NHP species provides new animal models to study SIV immunopathogenesis. T follicular helper cells have gained major interest in characterizing humoral immune responses in SIV infection and AIDS vaccine strategies. The ability of natural hosts to remain disease-free despite ongoing replication of SIV is continuing to puzzle the field.

SUMMARY

The HIV research field continues to realize the immense complexity of the host virus interaction. NHP present an invaluable tool to make progress towards an effective AIDS vaccine.

Neuroprotective maraviroc monotherapy in simian immunodeficiency virus-infected macaques: reduced replicating and latent SIV in the brain

OBJECTIVE

HIV-associated neurocognitive deficits remain a challenge despite suppressive combined antiretroviral therapy. Given the association between HIV-induced central nervous system (CNS) disease and replication of HIV in immune-activated macrophages, CCR5 antagonists may attenuate CNS disease by modulating inflammatory signaling and by limiting viral replication.

DESIGN

To establish whether initiating CCR5 inhibition during early infection altered CNS disease progression, outcomes were compared between simian immunodeficiency virus (SIV)-infected macaques treated with maraviroc (MVC) versus untreated SIV-infected macaques.

METHODS

Six SIV-infected rhesus macaques were treated with MVC monotherapy for 5 months beginning 24 days postinoculation; 22 SIV-infected animals served as untreated controls. SIV RNA levels in plasma, cerobrospinal fluid, and brain, and CNS expression of TNFα and CCL2 were measured by qRT-PCR. Immunostaining for CD68 and amyloid precursor protein in the brain was measured by image analysis. Plasma sCD163 was measured by ELISA.

RESULTS

SIV RNA and proviral DNA levels in brain were markedly lower with MVC treatment, demonstrating CCR5 inhibition reduces CNS replication of SIV and may reduce the CNS latent viral reservoir. MVC treatment also lowered monocyte and macrophage activation, represented by CNS CD68 immunostaining and plasma sCD163 levels, and reduced both TNFα and CCL2 RNA expression in brain. Treatment also reduced axonal amyloid precursor protein immunostaining to levels present in uninfected animals, consistent with neuroprotection.

CONCLUSION

CCR5 inhibitors may prevent neurologic disorders in HIV-infected individuals by reducing inflammation and by limiting viral replication in the brain. Furthermore, CCR5 inhibitors may reduce the latent viral reservoir in the CNS. Adding CCR5 inhibitors to combined antiretroviral regimens may offer multiple neuroprotective benefits.

Relationships among HIV infection, metabolic risk factors, and left ventricular structure and function

Our objective was to determine if the presence of metabolic complications (MC) conveyed an additional risk for left ventricular (LV) dysfunction in people with HIV. HIV⁺ and HIV⁻ men and women were categorized into four groups: (1) HIV⁺ with MC (43±7 years, n=64), (2) HIV⁺ without MC (42±7 years, n=59), (3) HIV⁻ with MC (44±8 years, n=37), or (4) HIV⁻ controls without MC (42±8 years, n=41). All participants underwent two-dimensional (2-D), Doppler, and tissue Doppler echocardiography. Overall, the prevalence of systolic dysfunction (15 vs. 4%, p=0.02) and LV hypertrophy (9 vs. 1%, p=0.03) was greater in HIV⁺ than in HIV⁻ participants. Participants with MC had a greater prevalence of LV hypertrophy (10% vs. 1%). Early mitral annular velocity during diastole was significantly (p<0.005) lower in groups with MC (HIV⁺/MC⁺: 11.6±2.3, HIV⁻/MC⁺: 12.0±2.3 vs. HIV⁺/MC⁻: 12.4±2.3, HIV⁻/MC⁻: 13.1±2.4 cm/s) and tended to be lower in groups with HIV (p=0.10). However, there was no interaction effect of HIV and MC for any systolic or diastolic variable. Regardless of HIV status, participants with MC had reduced LV diastolic function. Although both the presence of MC and HIV infection were associated with lower diastolic function, there was no additive negative effect of HIV on diastolic function beyond the effect of MC. Also, HIV was independently associated with lower systolic function. Clinical monitoring of LV function in individuals with metabolic risk factors, regardless of HIV status, is warranted.

Monocyte/macrophages and their role in HIV neuropathogenesis

Neurological sequelae of human immunodeficiency virus (HIV) infection have been and remain a significant problem. Monocytes and macrophages in humans and monkeys are susceptible to infection by HIV and simian immunodeficiency virus (SIV), and are considered to be a main mechanism by which the central nervous system (CNS) is infected. Within the infected CNS, perivascular macrophages and, in some cases, parenchymal microglia are infected as are multinucleated giant cells when present. While neurons are not themselves directly infected, neuronal damage occurs within the infected CNS. Despite the success of antiretroviral therapy (ART) in limiting virus in plasma to non-detectable levels, neurological deficits persist. This review discusses the continued neurological dysfunctions that persist in the era of ART, focusing on the roles of monocyte and macrophage as targets of continued viral infection and as agents of pathogenesis in what appears to be emergent macrophage-mediated disease resulting from long-term HIV infection of the host. Data discussed include the biology of monocyte/macrophage activation with HIV and SIV infection, traffic of cells into and out of the CNS with infection, macrophage-associated biomarkers of CNS and cardiac disease, the role of antiretroviral therapy on these cells and CNS disease, as well as the need for effective adjunctive therapies targeting monocytes and macrophages.

Cardiac effects in perinatally HIV-infected and HIV-exposed but uninfected children and adolescents: a view from the United States of America

Introduction

Human immunodeficiency virus (HIV) infection is a primary cause of acquired heart disease, particularly of accelerated atherosclerosis, symptomatic heart failure, and pulmonary arterial hypertension. Cardiac complications often occur in late-stage HIV infections as prolonged viral infection is becoming more relevant as longevity improves. Thus, multi-agent HIV therapies that help sustain life may also increase the risk of cardiovascular events and accelerated atherosclerosis.

Discussion

Before highly active antiretroviral therapy (HAART), the two-to-five-year incidence of symptomatic heart failure ranged from 4 to 28% in HIV patients. Patients both before and after HAART also frequently have asymptomatic abnormalities in cardiovascular structure. Echocardiographic measurements indicate left ventricular (LV) systolic dysfunction in 18%, LV hypertrophy in 6.5%, and left atrial dilation in 40% of patients followed on HAART therapy. Diastolic dysfunction is also common in long-term survivors of HIV infection. Accelerated atherosclerosis has been found in HIV-infected young adults and children without traditional coronary risk factors. Infective endocarditis, although rare in children, has high mortality in late-stage AIDS patients with poor nutritional status and severely compromised immune systems. Although lymphomas have been found in HIV-infected children, the incidence is low and cardiac malignancy is rare. Rates of congenital cardiovascular malformations range from 5.6 to 8.9% in cohorts of HIV-uninfected and HIV-infected children with HIV-infected mothers. In non-HIV-infected infants born to HIV-infected mothers, foetal exposure to ART is associated with reduced LV dimension, LV mass, and septal wall thickness and with higher LV fractional shortening and contractility during the first two years of life.

Conclusions

Routine, systematic, and comprehensive cardiac evaluation, including a thorough history and directed laboratory assays, is essential for the care of HIV-infected adults and children as cardiovascular illness has become a part of care for long-term survivors of HIV infection. The history should include traditional risk factors for atherosclerosis, prior opportunistic infections, environmental exposures, and therapeutic and illicit drug use. Laboratory tests should include a lipid profile, fasting glucose, and HIV viral load. Asymptomatic cardiac disease related to HIV can be fatal, and secondary effects of HIV infection often disguise cardiac symptoms, so systematic echocardiographic monitoring is warranted.

Cardiac disease in adolescents with delayed diagnosis of vertically acquired HIV infection

BACKGROUND

At least one-third of human immunodeficiency virus (HIV)-infected infants survive to adolescence even without antiretroviral therapy (ART), but are at high risk of complications including cardiac disease. We investigated the characteristics of cardiac disease among adolescents with HIV infection diagnosed in late childhood who were receiving ambulatory HIV care in Harare, Zimbabwe.

METHODS

Consecutive adolescents with vertically acquired HIV attending 2 HIV outpatient treatment clinics were studied. Assessment included clinical history and examination, and 2-dimensional, M-mode, pulsed- and continuous-wave Doppler echocardiography.

RESULTS

Of 110 participants (47% male; median age, 15 years; interquartile range, 12-17 years), 78 (71%) were taking ART. Exertional dyspnea, chest pain, palpitations, and ankle swelling were reported by 47 (43%), 43 (39%), 10 (9%), and 7 (6%), respectively. The New York Heart Association score was ≥ 2 in 41 participants (37%). Echocardiography showed that 74 participants (67%) had left ventricular (LV; septal and/or free wall) hypertrophy and 27 (24%) had evidence of impaired LV relaxation or restrictive LV physiology. The estimated pulmonary artery systolic pressure (ePASP) was >30 mm Hg in 4 participants (3.6%); of these 2 also had right ventricular (RV) dilatation. Another 32 participants (29%), without elevated ePASP, had isolated RV dilatation.

CONCLUSIONS

A significant burden of cardiac disease was seen among adolescents with vertically acquired HIV infection. More than half were asymptomatic yet had significant echocardiographic abnormalities. These findings highlight the need to screen this population in order to better define the geography, natural history, etiopathogenic mechanisms, and management (including the timing and choice of optimal therapeutic ART and cardiac drug interventions) to prevent development and/or progression of HIV-associated cardiac disease.

Reduced diastolic function and left ventricular mass in HIV-negative preadolescent children exposed to antiretroviral therapy in utero

OBJECTIVE

Abnormalities in left ventricular morphology and function have been reported in HIV-negative infants exposed to antiretroviral therapy (ART) in utero that persists throughout preschool age. The objective of this study was to determine if these abnormalities persist, resolve, or worsen during preadolescence.

DESIGN

Cross-sectional observation study.

METHODS

Thirty HIV-negative children born to HIV-positive women and exposed to ART in utero (mean age 8 ± 2 years, 37% female, 74% African-American) and 30 HIV-negative children born to HIV-negative women (mean age 8 ± 3 years, 37% female, 76% African-American) underwent two-dimensional Doppler, tissue Doppler, and strain echocardiography to evaluate left ventricular systolic and diastolic function.

RESULTS

Weight, body surface area, heart rate and blood pressure were similar between groups. For the ART-exposed group, left ventricular mass index was lower (60 ± 9 vs. 67 ± 12 g/m, P < 0.02) and early diastolic annular velocity was lower (15.0 ± 2.2 vs. 16.3 ± 2.5 cm/s, P < 0.03) compared to controls. Left ventricular systolic function did not differ between groups. Lower maternal third trimester CD4 count was associated with lower early diastolic annular velocity; other non-HIV-related variables including cocaine use and increased maternal age correlated with lower left ventricular mass index.

CONCLUSIONS

Abnormalities in left ventricular systolic performance previously reported in HIV-negative infants and preschool aged children exposed to ART in utero were not apparent in preadolescent children. Left ventricular diastolic relaxation was reduced compared with controls suggesting residual effects of ART exposure on left ventricular diastolic function. Larger, longitudinal studies are necessary to confirm these observations.