Deciphering Endothelial Dysfunction in the HIV-Infected Population

Update on Central Nervous System Effects of the Intersection of HIV-1 and SARS-CoV-2

PURPOSE OF REVIEW

Research has shown myriad neurologic and mental health manifestations during the acute and subsequent stages of COVID-19 in people with HIV (PWH). This review summarizes the updates on central nervous system (CNS) outcomes following SARS-CoV-2 infection in PWH and highlight the existing knowledge gaps in this area.

RECENT FINDINGS

Studies leveraging electronic record systems have highlighted the excess risk of developing acute and lingering neurological complications of COVID-19 in PWH compared to people without HIV (PWoH). However, there is a notable scarcity of neuroimaging as well as blood and cerebrospinal fluid (CSF) marker studies that can confirm the potential synergy between these two infections, particularly in PWH receiving suppressive antiretroviral therapy. Considering the unclear potential interaction between SARS-CoV-2 and HIV, clinicians should remain vigilant regarding new-onset or worsening neurological symptoms in PWH following COVID-19, as they could be linked to either infection.

Serum E-selectin and endothelial cell-specific Molecule-1 levels among people living with HIV on long term ART in Uganda: a pilot cross-sectional study

BACKGROUND

Prolonged exposure to HIV and anti-retroviral therapy (ART) has been linked with endothelial cell activation which subsequently predisposes people living with HIV (PLWH) to cardiovascular diseases. Serum biomarkers of endothelial cell activation such as E-Selectin and endothelial cell-specific molecule-1 (ESM-1) could aid in early detection of PLWH at a risk of cardiovascular diseases. However, there is a paucity of data on these biomarkers like E-selectin and endothelial cell-specific molecule-1 (ESM-1) among PLWH on long term ART (≥ 10 years) in Uganda. The aim of this study is to determine the serum levels of these biomarkers in this population.

METHODS

This was a cross-sectional study where we randomly sampled 73 stored serum samples of PLWH who were enrolled in the Infectious Diseases Institute (IDI) ART long term (ALT cohort). We measured serum levels of E-selectin and ESM-1 by ELISA. Data was summarized using median and interquartile range. Inferential statistics were performed to determine predictors of elevated levels of E-selectin.

RESULTS

Of the 73 samples analyzed, 38 (52.1%) were from female participants. The mean age was 54 ± 9.0 years. Twenty participants (27.4%) had a history of smoking while 52 (71.2%) had a history of alcohol intake. Twenty-five (34.3%) of the participants were overweight whereas 4 (5.6%) were obese. Fifty-four (74%) had an undetectable viral load (≤ 0 copies/ml) and the mean duration of ART at the time of sampling (2014/2015) was 10.4 ± 0.4 years. While serum levels of ESM-1 were not detectable in any of our samples, the median E-selectin levels was 147.6 μm/L ranging from 8.44 μm/L and 1,979.36 μm/L. Sixty-seven participants (91.8%) had elevated levels of E-selectin (> 39 μm/L). CD4 count > 500 cells/µl compared to lower counts was a predictor of elevated levels of E-Selectin (adjusted Odd Ratio 12.5, 95% CI (1.03 - 149.95, p < 0.05).

CONCLUSIONS

The majority (91.8%) of PLWH on long term ART had elevated levels of E-selectin. Having high CD4 count (> 500 cells/µl) was predictive of elevated levels of E-Selectin. Future work should longitudinally assess the trend of levels of E-selectin and ESM-1 while assessing for cardiovascular diseases endpoint.

Selected inflammatory and coagulation biomarkers pre-viral suppression in people with human immunodeficiency virus (HIV) infection without overt cardiovascular disease: Is there a need to redefine reference indices?

BACKGROUND

Human immunodeficiency virus (HIV) infection is prevalent in Africa and causes morbidity and mortality despite antiretroviral therapy (ART). Non-communicable complications of HIV infection include cardiovascular disease (CVD) with thromboses throughout the vascular tree. Ongoing inflammation and endothelial dysfunction in people living with HIV (PLWH) probably contribute significantly to HIV-related CVD.

OBJECTIVES

A systematic review was conducted to inform interpretation of 5 biomarkers commonly measured in PLWH namely interleukin-6 (IL-6), tumour necrosis factor alpha (TNF-α), D-dimers, and soluble intracellular and vascular adhesion molecules-1 (sICAM-1 and sVCAM-1) to attempt to define a range for these values in ART naïve PLWH without overt CVD or additional comorbid diseases.

METHODS

A systematic search was conducted for all studies documenting the levels of the above biomarkers in ART naïve PLWH published on the PubMed database from 1994 to 2020.

RESULTS

The number of publications that reported medians above the assay values was: 4/15 for D-dimer; 0/5 for TNF-α, 8/16 for IL-6, 3/6 for sVCAM-1, and 4/5 for sICAM-1.

CONCLUSION

The clinical utility of biomarkers is reduced by the lack of standardisation of the measurement of these parameters, absence of normal reference indices and the lack of uniformity of study protocols in different research centres. This review supports the ongoing use of D-dimers to predict thrombotic and bleeding events in PLWH since the weighted averages across study assays suggest that the median levels do not exceed the reference range. The role of inflammatory cytokine monitoring and measurement of endothelial adhesion markers is less clear.

HIV-associated thrombotic thrombocytopenic purpura (HIV-TTP): A practical guide and review of the literature

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP), a serious thrombotic microangiopathy (TMA), is prevalent in the South African HIV-infected population. The exact pathogenesis of HIV-associated TTP (HIV-TTP) is however still unclear with diagnostic and therapeutic inconsistancies.

METHODS

A systematic review of the published literature regarding HIV-TTP was performed.

RESULTS

HIV-TTP is still associated with significant morbidity and mortality in Africa despite the availability of anti-retroviral therpy (ART). Diagnosis of HIV-TTP requires the presence of a micro-angiopathic haemolytic anaemia with significant red blood cell schistocytes and thrombocytopenia in the absence of another TMA but background activation of the coagulation system and inflammation in HIV infected people can result in diagnostic anbiguity. Plasma therapy in the form of infusion or exchange is successful but expensive, associated with side-effects and not widely available. Adjuvant immunosuppression therapy may of benefit in patients with HIV-TTP and ART must always be optimised. Endothelial dysfunction caused by chronic inflammation and complement activation most likely contributes to the development of HIV-TTP.

CONCLUSION

The role of adjuvant immunomodulating therpy, the therapeutic targets and pathogenic contribution from endothelial dysfunction in HIV-TTP requires further investigation.

Methadone use is associated with increased levels of sCD14, immune activation, and inflammation during suppressed HIV infection

Opioid use has negative effects on immune responses and may impair immune reconstitution in persons living with HIV (PLWH) infection undergoing antiretroviral treatment (ART). The effects of treatment with μ opioid receptor (MOR) agonists (e.g., methadone, MET) and antagonists (e.g., naltrexone, NTX) on immune reconstitution and immune activation in ART-suppressed PLWH have not been assessed in-depth. We studied the effects of methadone or naltrexone on measures of immune reconstitution and immune activation in a cross-sectional community cohort of 30 HIV-infected individuals receiving suppressive ART and medications for opioid use disorder (MOUD) (12 MET, 8 NTX and 10 controls). Plasma markers of inflammation and immune activation were measured using ELISA, Luminex, or Simoa. Plasma IgG glycosylation was assessed using capillary electrophoresis. Cell subsets and activation were studied using whole blood flow cytometry. Individuals in the MET group, but no in the NTX group, had higher plasma levels of inflammation and immune activation markers than controls. These markers include soluble CD14 (an independent predictor of morbidity and mortality during HIV infection), proinflammatory cytokines, and proinflammatory IgG glycans. This effect was independent of time on treatment. Our results indicate that methadone-based MOUD regimens may sustain immune activation and inflammation in ART-treated HIV-infected individuals. Our pilot study provides the foundation and rationale for future longitudinal functional studies of the impact of MOUD regimens on immune reconstitution and residual activation after ART-mediated suppression.

Coronary Endothelial Dysfunction in People Living With HIV Is Related to Body Fat Distribution

BACKGROUND

People living with HIV (PLWH) on antiretroviral therapy (ART) are at increased risk of atherosclerotic disease. Abnormal adipose distribution is common in PLWH and may contribute to atherosclerosis. Because coronary artery endothelial function (CEF) is impaired in early atherosclerosis, predicts future cardiovascular events, and is reduced in PLWH, we investigated associations between body fat distribution and CEF in PLWH.

SETTING

Prospective cohort study.

METHODS

PLWH on stable ART underwent MRI to quantify CEF, measured as change in coronary cross-sectional area from rest to that during isometric handgrip exercise, an endothelial-dependent stressor. Abdominal visceral and subcutaneous fat area (axial L4 level) and liver fat fraction were quantified using MRI. Linear regression was used to determine associations between CEF and independent variables.

RESULTS

Among 84 PLWH (52 ± 11 years; 33% women), mean cross-sectional area change was 0.74 ± 11.7%, indicating impaired CEF. On univariable regression analysis, CEF was inversely related to waist circumference (R = -0.31, P = 0.014), hip circumference (R = -0.27, P = 0.037), and subcutaneous fat area (R = -0.25, P = 0.031). We did not observe significant relationships between CEF and liver fat fraction, waist/hip ratio, or visceral fat area. On multivariable regression adjusted for age, sex, and race, CEF was associated with waist circumference, hip circumference, subcutaneous fat, and liver fat fraction.

CONCLUSION

Waist and hip circumference and subcutaneous fat area are associated with impaired CEF, an established metric of abnormal vascular health in PLWH on stable ART, and may contribute to the increased rate of heart disease in this population.

Thrombotic thrombocytopenic purpura (TTP) in Human immunodeficiency virus (HIV) infected patients: New twists on an old disease

OBJECTIVE

Investigate the presence of inflammation, endothelial dysfunction and complement activation in patients with HIV-associated thrombotic thrombocytopenic purpura (HIV-TTP) to support the hypothesis that these processes probably contribute to the development of this thrombotic microangiopathy.

DESIGN

A prospective, investigational cohort study of 35 consecutive patients diagnosed with HIV-associated TTP presenting to three academic, tertiary care hospitals in Johannesburg, South Africa over 2 years.

METHODS

The patients with HIV-TTP received therapeutic plasma therapy and supportive treatment. Demographic data, the results of routine investigations and patient outcomes were recorded. Peripheral blood samples were collected prior to and on completion of plasma therapy and the following additional parameters were assessed at both time points: activity of the von Willebrand factor (VWF) cleaving protease, a-disintegrin-and-metalloproteinase-with-thrombospondin-motifs 13 (ADAMTS-13) and the presence of ADAMTS-13 autoantibodies, levels of pro-inflammatory cytokines, interleukin-6 and tumour necrosis factor-alpha, and two endothelial cell adhesion molecules. Complement activation was assessed by sequential measurement of C3 and C4 as well as levels of the complement inhibitor, factor H.

RESULTS

The inflammatory and endothelial activation markers were significantly (P < 0.001) elevated in the cohort of patients prior to plasma therapy compared with levels on discharge. Complement was activated and normalized with therapy. The ADAMTS-13 levels were reduced with significant auto-antibodies to this protease at presentation.

CONCLUSION

Inflammation in HIV mediates endothelial damage and complement activation. This study proposes that these processes are probably contributory to the development of HIV-TTP, which can therefore be characterized in part as a complementopathy, resembling TTP-like syndrome.

Cardiovascular disease (CVD) risk assessment of HIV medication regimens using hematopoietic CD34+ progenitor cells

Background

To determine the effects of integrase inhibitor (INSTI) in comparison with non-INSTI-based regimens such as non-nucleoside reverse transcriptase inhibitors (NNRTIs)-based regimens on cardiovascular disease (CVD) risk in HIV+ patients without overt history of CVD or diabetes, with normal CD4:CD8 count. For CVD risk assessment we primarily used hematopoietic CD34+ progenitor cells, as a biomarker.

Methods

Nineteen male subjects, ages 32–61 years with BMI 21.0–36.0, were enrolled. This was a single time point, cross-sectional, observational study. Subjects were enrolled under 2 groups (either on INSTI-based regimen with 13 subjects or NNRTI (non-INSTI)-based regimens with 6 subjects) who were taking stable doses of HAART. The medication regimens were a combination of one NRTI (typically tenofovir–emtricitabine) plus one INSTI or NNRTI. Our outcome measures were focused on cardiovascular and endothelial cell function and systemic inflammation. Our primary outcome measures were peripheral blood-derived hematopoietic progenitor cell number (CD34 and CD133 positive), CD34+ cell function and gene expression studies. Our secondary outcomes were arterial stiffness measures and serum-based markers of inflammation.

Results

A significant increase in percentage number of progenitor cells, CD133+ cells (p = 0.004), was noted along with an increase of double progenitor mark positive CD133+/CD34+ progenitor cell population being observed in INSTI group as compared to NNRTI group, by flow cytometry. mRNA gene expression for antioxidant gene catalase was noted along with a trend toward a decrease in gene expression of inflammatory marker IL6 (p = 0.06) being observed in CD34+ from INSTI group vs NNRTI group. The plasma IL-6 and CRP levels did not change significantly between the groups. Neutrophil–Lymphocyte ratio (NLR), an important marker of inflammation, was noted to be lower in INSTI group. A mean fasting glucose level was also lower in the INSTI group compared to NNRTI group (p = 0.03). Interestingly, urine microalbumin levels were higher in the INSTI group compared to NNRTI group (p = 0.08), while eGFR levels were significantly lower in the INSTI group (p = 0.002). The arterial stiffness measures did not show statistically significant differences between the two groups.

Conclusion

We conclude that the INSTI regimen may provide a better CVD risk profile compared to NNRTI-based HAART regimen; however, the increased albuminuria along with lower eGFR, noted in INSTI group, is of concern. Because of the small size, these results would need replication in additional studies before changing clinical practice.

Clinical trial registrationhttps://clinicaltrials.gov/ct2/show/NCT03782142?cond=Hiv&spons=Sabyasachi+sen&cntry=US&state=US%3ADC&city=Washington&draw=2&rank=1. ClinicalTrials.gov Identifier: NCT03782142.

Biomarkers of Endothelial Activation in Black South African HIV-Positive Subjects are Associated with Both High Viral Load and Low CD4 Counts

The prevalence of cardiovascular death in the HIV-infected population is higher than in uninfected individuals. Growing evidence suggests that HIV infection itself is directly linked to endothelial activation and dysfunction. Therefore, the aim of this study was to investigate whether endothelial activation is present in African subjects with HIV infection and identify its possible determinants. Eighty HIV-infected treatment-naive cases, categorized into two groups based on CD4 count (38 subjects with CD4 count ≤350 cells/mm³ and 42 subjects with CD4 count >350 cells/mm³), were compared with 60 HIV-uninfected controls. A small subgroup of the HIV-infected participants (n = 13) were followed up for 18 months following initiation of antiretroviral therapy (ART). Anthropometric data, fasting lipid and glucose levels, viral load, and CD4 counts were measured as were serum levels of intercellular adhesion molecule-1 (ICAM-1), endothelial leukocyte adhesion molecule-1, vascular cell adhesion molecule-1 (VCAM-1), monocyte chemoattractant protein-1, von Willebrand factor (vWF), tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8). The HIV-infected low CD4 group had higher levels of ICAM-1 (p < .05), VCAM-1 (p < .0005), TNF-α (p < .005), and vWF (p < .005), compared with the controls. In the HIV-infected cohort, VCAM-1 levels were negatively associated with CD4 counts (β = -0.474; p < .0005), whereas vWF levels were positively associated with viral load (β = 0.344; p < .01). Levels of ICAM-1 and VCAM-1 were reduced by ART (p < .05 vs. baseline for both), however, levels of IL-6, IL-8, and TNF-α increased (p < .005 vs. baseline for all). Endothelial activation and inflammation are evident in African ART-naive HIV-infected patients; the former is attenuated, and the latter is increased after 18 months of ART. In HIV-infected subjects, both immunological dysregulation and viral load are associated with biomarkers of endothelial activation.

Urinary SARS-CoV-2 RNA Is an Indicator for the Progression and Prognosis of COVID-19

Background: We aimed to analyze clinical characteristics and find potential factors to predict poor prognosis in patients with coronavirus disease 2019 (COVID-19). Methods: We analyzed the clinical characteristics and laboratory tests of COVID-19 patients and detected SARS-CoV-2 RNA in urine sediments collected from 53 COVID-19 patients enrolled in Renmin Hospital of Wuhan University from 31 January 2020 to 18 February 2020 with qRT-PCR analysis. Then, we classified those patients based on clinical conditions (severe or non-severe syndrome) and urinary SARS-CoV-2 RNA (U_RNA⁻ or U_RNA⁺). Results: We found that COVID-19 patients with severe syndrome (severe patients) showed significantly higher positive rate (11 of 23, 47.8%) of urinary SARS-CoV-2 RNA than non-severe patients (4 of 30, 13.3%, p = 0.006). U_RNA⁺ patients or severe U_RNA⁺ subgroup exhibited higher prevalence of inflammation and immune discord, cardiovascular diseases, liver damage and renal dysfunction, and higher risk of death than U_RNA⁻ patients. To understand the potential mechanisms underlying the viral urine shedding, we performed renal histopathological analysis on postmortems of patients with COVID-19 and found severe renal vascular endothelium lesion characterized by an increase of the expression of thrombomodulin and von Willebrand factor, markers to assess the endothelium dysfunction. We proposed a theoretical and mathematic model to depict the potential factors that determine the urine shedding of SARS-CoV-2. Conclusions: This study indicated that urinary SARS-CoV-2 RNA detected in urine specimens can be used to predict the progression and prognosis of COVID-19 severity.

Endothelial Dysfunction as a Primary Consequence of SARS-CoV-2 Infection

A number of different viral species are known to have effects on the endothelium. These include dengue, Ebola, Marburg, Lassa fever, yellow fever and influenza viruses, cytomegalovirus and coronaviruses. There are currently seven human endemic coronaviruses, all of which cause respiratory diseases and bind to receptors found within the endothelium. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes the coronavirus disease 2019 (COVID-19) is highly infectious. Like its predecessor, SARS-CoV, it binds to angiotensin-converting enzyme-2 (ACE-2), which is expressed in many cell types, particularly in the lung, including endothelial cells. The initiation of a cytokine storm by the virus along with infection of endothelial cells leads to apoptosis and structural and functional changes that attenuate vascular integrity in many organs including the lungs, heart, liver and kidney. Endothelial damage also enhances the coagulation pathway leading to thrombus formation in major vessels and capillaries. Infection with SARS-CoV-2 has an adverse outcome for individuals with particular comorbid diseases, e.g. hypertension, obesity, type 2 diabetes and cardiovascular disease. It is possible that this is due to the presence of pre-existing endothelial dysfunction and systemic inflammation in subjects with these diseases. Therapies for COVID-19 that target the endothelium, the inflammatory response and the coagulation pathway are currently under trial.

Noninvasive detection of impaired pulmonary artery endothelial function in people living with HIV

OBJECTIVE

People living with HIV (PLWH) have an increased risk of pulmonary vascular disease and pulmonary hypertension. Endothelial cell dysfunction is thought to contribute, but human studies have been limited by the invasive nature of conventional measures of pulmonary artery endothelial function (PAEF). We report here a noninvasive MRI approach to measure nitric oxide mediated PAEF by quantifying changes in pulmonary artery area and blood flow during isometric handgrip exercise (IHE), an endothelial nitric oxide dependent stressor. We used this to test the hypothesis that PLWH have impaired PAEF, even before development of pulmonary hypertension.

DESIGN

A prospective cohort study.

METHODS

We enrolled 25 HIV-positive viral-suppressed individuals on stable antiretroviral therapy without known or suspected pulmonary hypertension and 19 matched seronegative control individuals (HIV-negative). Pulmonary artery area and blood flow changes in response to IHE were measured with noncontrast MRI. Data previously collected during nitric oxide-synthase inhibition were analysed to determine the role of nitric oxide in the pulmonary artery response to IHE.

RESULTS

Seronegative individuals exhibited the anticipated PA vasodilatory response to IHE, but this was completely absent in HIV-positive individuals who exhibited an impaired area change (-1.1 ± 1.2 vs. +7.7 ± 2.2%, HIV-positive vs. HIV-negative, mean ± SEM, respectively, P = 0.002) and blood flow response (0.2 ± 2.3 vs. 13.5 ± 4.8%, P = 0.005). The pulmonary artery vasodilatory effect of IHE in healthy individuals was fully blocked by nitric oxide-synthase, demonstrating this pulmonary artery response is predominantly nitric oxide mediated.

CONCLUSION

Using noninvasive MRI methods to quantify PAEF, we observed significantly impaired PAEF in PLWH compared with matched HIV-negative controls. Noninvasive PAEF testing may be useful in evaluating early HIV-related pulmonary vascular disease.

The regional pattern of abnormal cerebrovascular reactivity in HIV-infected, virally suppressed women

The purpose of this study was to assess whole brain and regional patterns of cerebrovascular reactivity (CVR) abnormalities in HIV-infected women using quantitative whole brain arterial spin labeling (ASL). We hypothesized that HIV-infected women would demonstrate decreased regional brain CVR despite viral suppression. This cross-sectional study recruited subjects from the Bay Area Women's Interagency Health Study (WIHS)-a cohort study designed to investigate the progression of HIV disease in women. In addition to conventional noncontrast cerebral MRI sequences, perfusion imaging was performed before and after the administration of intravenous acetazolamide. CVR was measured by comparing quantitative ASL brain perfusion before and after administration of intravenous acetazolamide. In order to validate and corroborate ASL-based whole brain and regional perfusion, phase-contrast (PC) imaging was also performed through the major neck vessels. FLAIR and susceptibility weighted sequences were performed to assess for white matter injury and microbleeds, respectively. Ten HIV-infected women and seven uninfected, age-matched controls were evaluated. Significant group differences were present in whole brain and regional CVR between HIV-infected and uninfected women. These regional differences were significant in the frontal lobe and basal ganglia. CVR measurements were not significantly impacted by the degree of white matter signal abnormality or presence of microbleeds. Despite complete viral suppression, dysfunction of the neurovascular unit persists in the HIV population. Given the lack of association between CVR and traditional imaging markers of small vessel disease, CVR quantification may provide an early biomarker of pre-morbid vascular disease.