Drug abuse and HIV-related pulmonary hypertension: double hit injury

Treatment algorithm for pulmonary arterial hypertension

Pulmonary arterial hypertension leads to significant impairment in haemodynamics, right heart function, exercise capacity, quality of life and survival. Current therapies have mechanisms of action involving signalling via one of four pathways: endothelin-1, nitric oxide, prostacyclin and bone morphogenetic protein/activin signalling. Efficacy has generally been greater with therapeutic combinations and with parenteral therapy compared with monotherapy or nonparenteral therapies, and maximal medical therapy is now four-drug therapy. Lung transplantation remains an option for selected patients with an inadequate response to therapies.

Investigating the "sex paradox" in pulmonary arterial hypertension: Results from the Pulmonary Hypertension Association Registry (PHAR)

BACKGROUND

Female sex is a significant risk factor for pulmonary arterial hypertension (PAH), yet males with PAH have worse survival - a phenomenon referred to as the "sex paradox" in PAH.

METHODS

All adult PAH patients in the Pulmonary Hypertension Association Registry (PHAR) with congruent sex and gender were included. Baseline differences in demographics, hemodynamics, functional parameters, and quality of life were assessed by sex. Kaplan-Meier survival analysis was used to evaluate survival by sex. Mediation analysis was conducted with Cox proportional hazards regression by comparing the unadjusted hazard ratios for sex before and after adjustment for covariates. The plausibility of collider-stratification bias was assessed by modeling how large an unmeasured factor would have to be to generate the observed sex-based mortality differences. Subgroup analysis was performed on idiopathic and incident patients.

RESULTS

Among the 1,891 patients included, 75% were female. Compared to men, women had less favorable hemodynamics, lower 6-minute walk distance, more PAH therapies, and worse functional class; however, sex-based differences were less pronounced when accounting for body surface area or expected variability by gender. On multivariate analysis, women had a 48% lower risk of death compared to men (Hazard Ratio 0.52, 95% Confidence interval 0.36 - 0.74, p < 0.001). Modeling found that under reasonable assumptions collider-stratification could account for sex-based differences in mortality.

CONCLUSIONS

In this large registry of PAH patients new to a care center, men had worse survival than women despite having more favorable baseline characteristics. Collider-stratification bias could account for the observed greater mortality among men.

HIV and Drug Use: A Tale of Synergy in Pulmonary Vascular Disease Development

Over the past two decades, with the advent and adoption of highly active anti-retroviral therapy, HIV-1 infection, a once fatal and acute illness, has transformed into a chronic disease with people living with HIV (PWH) experiencing increased rates of cardio-pulmonary vascular diseases including life-threatening pulmonary hypertension. Moreover, the chronic consequences of tobacco, alcohol, and drug use are increasingly seen in older PWH. Drug use, specifically, can have pathologic effects on the cardiovascular health of these individuals. The "double hit" of drug use and HIV may increase the risk of HIV-associated pulmonary arterial hypertension (HIV-PAH) and potentiate right heart failure in this population. This article explores the epidemiology and pathophysiology of PAH associated with HIV and recreational drug use and describes the proposed mechanisms by which HIV and drug use, together, can cause pulmonary vascular remodeling and cardiopulmonary hemodynamic compromise. In addition to detailing the proposed cellular and signaling pathways involved in the development of PAH, this article proposes areas ripe for future research, including the influence of gut dysbiosis and cellular senescence on the pathobiology of HIV-PAH. © 2023 American Physiological Society. Compr Physiol 13:4659-4683, 2023.

HIV status and survival of patients with pulmonary hypertension due to left heart disease: the Pan African Pulmonary Hypertension Cohort

In sub-Saharan Africa, little is known about pulmonary hypertension in left heart disease (PH-LHD). We used multivariate logistic and cox-hazard proportional regression models to examine factors associated with increased right ventricular systolic pressure (RVSP) and the effect of real-world HIV status scenarios on 6-month survival rate in the Pan African Pulmonary Hypertension Cohort (PAPUCO) study, a prospective cohort from four African countries. Exposure to biomass fuel smoke (aOR, 95%CI 3.07, 1.02-9.28), moderate to severe NYHA/FC III/IV (aOR, 95%CI 4.18, 1.01-17.38), and unknown HIV status (aOR, 95%CI 2.73, 0.96-7.73) predicted moderate to severe RVSP at the time of presentation. Six months later, HIV infection, moderate-to-severe NYHA/FC, and alcohol consumption were associated with decreased survival probabilities. Upon adjusting for HIV infection, it was observed that an incremental rise in RVSP (1 mmHg) and inter-ventricular septal thickness (1 mm) resulted in an 8% (aHR, 95%CI 1.08, 1.02-1.13) and 20% (aHR, 95%CI 1.2, 1.00-1.43) increase in the probability of mortality due to PH-LHD. In contrast, the risk of death from PH-LHD was reduced by 23% for each additional unit of BMI. (aHR, 95%CI 0.77, 0.59-1.00). In conclusion, the present study offers insights into the determinants that are notably linked to unfavorable survival outcomes in patients with pulmonary hypertension due to left heart disease. Certain factors identified in this study are readily evaluable and amenable to modification, even in settings with limited resources.

Potential long-term effects of SARS-CoV-2 infection on the pulmonary vasculature: Multilayered cross-talks in the setting of coinfections and comorbidities

The Coronavirus Disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and its sublineages pose a new challenge to healthcare systems worldwide due to its ability to efficiently spread in immunized populations and its resistance to currently available therapies. COVID-19, although targeting primarily the respiratory system, is also now well established that later affects every organ in the body. Most importantly, despite the available therapy and vaccine-elicited protection, the long-term consequences of viral infection in breakthrough and asymptomatic individuals are areas of concern. In the past two years, investigators accumulated evidence on how the virus triggers our immune system and the molecular signals involved in the cross-talk between immune cells and structural cells in the pulmonary vasculature to drive pathological lung complications such as endothelial dysfunction and thrombosis. In the review, we emphasize recent updates on the pathophysiological inflammatory and immune responses associated with SARS-CoV-2 infection and their potential long-term consequences that may consequently lead to the development of pulmonary vascular diseases.

An Outlook on the Etiopathogenesis of Pulmonary Hypertension in HIV

Although overall survival rates of patients infected with human immunodeficiency virus (HIV) have been significantly improved by antiretroviral therapy (ART), chronic comorbidities associated with HIV result in a worsening quality of life. Pulmonary arterial hypertension (PAH) is the most prevalent comorbidity associated with HIV infection. Despite low viremia and a non-replicative state maintained by ART, few people develop PAH. Previous data from animal models and human pulmonary microvascular endothelial cells (HPMVECs) suggests a constellation of events occurring during the propagation of HIV-associated PAH (HIV-PAH). However, these studies have not successfully isolated HIV virions, HIV-DNA, protein 24 antigen (p24), or HIV-RNA from the pulmonary endothelial cells (ECs). It provides an insight into an ongoing inflammatory process that could be attributed to viral proteins. Several studies have demonstrated the role of viral proteins on vascular remodeling. A composite of chronic inflammatory changes mediated by cytokines and growth factors along with several inciting risk factors such as Hepatitis C virus (HCV) co-infection, genetic factors, male predominance, illegal drug usage, and duration of HIV infection have led to molecular changes that result in an initial phase of apoptosis followed by the formation of apoptotic resistant hyperproliferative ECs with altered phenotype. This study aims to identify the risk factors and mechanisms behind HIV-PAH pathobiology at the host-pathogen interface at the intracellular level.

Extracellular Vesicle TGF-β1 Is Linked to Cardiopulmonary Dysfunction in Human Immunodeficiency Virus

Extracellular vesicles (EVs) have emerged as important mediators in cell-cell communication; however, their relevance in pulmonary hypertension (PH) secondary to human immunodeficiency virus (HIV) infection is yet to be explored. Considering that circulating monocytes are the source of the increased number of perivascular macrophages surrounding the remodeled vessels in PH, this study aimed to identify the role of circulating small EVs and EVs released by HIV-infected human monocyte-derived macrophages in the development of PH. We report significantly higher numbers of plasma-derived EVs carrying higher levels of TGF-β1 (transforming growth factor-β1) in HIV-positive individuals with PH compared with individuals without PH. Importantly, levels of these TGF-β1-loaded, plasma-derived EVs correlated with pulmonary arterial systolic pressures and CD4 counts but did not correlate with the Dl CO or viral load. Correspondingly, enhanced TGF-β1-dependent pulmonary endothelial injury and smooth muscle hyperplasia were observed. HIV-1 infection of monocyte-derived macrophages in the presence of cocaine resulted in an increased number of TGF-β1-high EVs, and intravenous injection of these EVs in rats led to increased right ventricle systolic pressure accompanied by myocardial injury and increased levels of serum ET-1 (endothelin-1), TNF-α, and cardiac troponin-I. Conversely, pretreatment of rats with TGF-β receptor 1 inhibitor prevented these EV-mediated changes. Findings define the ability of macrophage-derived small EVs to cause pulmonary vascular modeling and PH via modulation of TGF-β signaling and suggest clinical implications of circulating TGF-β-high EVs as a potential biomarker of HIV-associated PH.

Exercise-induced pulmonary hypertension in HIV patients: Association with poor clinical and immunological status

BACKGROUND AND AIM

Exercise-induced pulmonary hypertension (Ex-PH) may represent the earliest sign of pulmonary arterial hypertension (PAH) in human immunodeficiency virus (HIV) patients. We investigated its association with clinical and immunological status, virologic control, and response to antiviral therapy.

METHODS

In 32 consecutive HIV patients with either low (n = 29) or intermediate probability (n = 3) of PH at rest, we evaluated the association of isolated ExPH with: time to HIV diagnosis; CD4+ T-cell count; clinical progression to acquired immunodeficiency syndrome (AIDS); development of resistance to antiretroviral therapy (ART); HIV RNA levels; time to beginning of ART; current use of protease inhibitors; combination of ART with boosters (ritonavir or cobicistat); immuno-virologic response to ART; and ART discontinuation. Isolated ExPH at stress echocardiography (ESE) was defined as absence of PH at rest and systolic pulmonary arterial pressure (sPAP) >45 mmHg or a >20 mmHg increase during low-intensity exercise cardiac output (<10 L/min).

RESULTS

In our cohort, 22% (n = 7) of the enrolled population developed ExPH which was inversely related to CD4+ T-cell count (p = 0.047), time to HIV diagnosis (p = 0.014) and time to onset of ART (p = 0.041). Patients with ExPH had a worse functional class than patients without ExPH (p < 0.001). ExPH and AIDS showed a trend (p = 0.093) to a direct relationship. AIDS patients had a higher pulmonary vascular resistance compared to patients without ExPH (p = 0.020) at rest echocardiography.

CONCLUSIONS

The presence of isolated ExPH associates with a worse clinical status and poor immunological control in HIV patients. Assessment of ExPH by ESE may help identify subgroups of HIV patients with a propensity to develop subclinical impairment of pulmonary circulation following poor control of HIV infection.

Preterm Birth and Antiretroviral Exposure in Infants HIV-exposed Uninfected

BACKGROUND

Infants HIV-exposed and uninfected (IHEU) who are born to women living with HIV are at an increased risk of preterm birth (PTB). Antenatal exposure to certain maternal antiretroviral therapy (ART) regimens has been associated with PTB, although existing studies in this domain are limited and report discordant findings. We determined odds of PTB among IHEU by antenatal ART regimens and timing of exposure, adjusting for maternal risk factors.

METHODS

We retrospectively studied IHEU born in British Columbia (BC), Canada between 1990 and 2012 utilizing provincial health administrative databases. We included data from a control group of infants HIV-unexposed and uninfected (IHUU) matched ~3:1 for each IHEU on age, sex and geocode.

RESULTS

A total of 411 IHEU and 1224 IHUU were included in univariable analysis. PTB was more frequent among IHEU (20%) compared with IHUU (7%). IHEU were more often antenatally exposed to alcohol, tobacco, as well as prescription, nonprescription, and illicit drugs (IHEU: 36%, 8% and 35%; vs. IHUU: 3%, 1% and 9%, respectively). After adjusting for maternal substance use and smoking exposure, IHEU remained at increased odds of PTB [adjusted odds ratio (aOR) (95% CI): 2.66; (1.73, 4.08)] compared with matched IHUU controls. ART-exposed IHEU (excluding those with NRTIs only ART) had lower adjusted odds of PTB compared with IHEU with no maternal ART exposure, regardless of regimen [aOR range: 0.16-0.29 (0.02-0.95)]. Odds of PTB between IHEU exposed to ART from conception compared with IHEU exposed to ART postconception did not differ [aOR: 0.91 (0.47, 1.76)]; however, both groups experienced lower odds of PTB compared with IHEU with no maternal ART [preconception: aOR: 0.28 (0.08, 0.89); postconception: aOR 0.30 (0.11, 0.83)].

CONCLUSIONS

BC IHEU were over twice as likely to be born preterm compared with demographically matched controls. Maternal substance use in pregnancy modulated this risk; however, we found no adverse associations of PTB with exposure to antenatal ART.

NADPH oxidase-mediated endothelial injury in HIV- and opioid-induced pulmonary arterial hypertension

We previously demonstrated that the combined exposure of human pulmonary microvascular endothelial cells (HPMECs) to morphine and viral protein(s) results in the oxidative stress-mediated induction of autophagy, leading to shift in the cells from early apoptotic to apoptosis-resistant proliferative status associated with the angioproliferative remodeling observed in pulmonary arterial hypertension (PAH). In this study, we tried to delineate the major source of HIV-1 protein Tat and morphine induced oxidative burst in HPMECs and its consequences on vascular remodeling and PAH in an in vivo model. We observed switch from the initial increased expression of NADPH oxidase (NOX) 2 in response to acute treatment of morphine and HIV-Tat to later increased expression of NOX4 on chronic treatment in the endoplasmic reticulum of HPMECs without any alterations in the mitochondria. Furthermore, NOX-dependent induction of autophagy was observed to play a pivotal role in regulating the endothelial cell survival. Our in vivo findings showed significant increase in pulmonary vascular remodeling, right ventricular systolic pressure, and Fulton index in HIV-transgenic rats on chronic administration of morphine. This was associated with increased oxidative stress in lung tissues and rat pulmonary microvascular endothelial cells. Additionally, endothelial cells from morphine-treated HIV-transgenic rats demonstrated increased expression of NOX2 and NOX4 proteins, inhibition of which ameliorated their increased survival upon serum starvation. In conclusion, this study describes NADPH oxidases as one of the main players in the oxidative stress-mediated endothelial dysfunction on the dual hit of HIV-viral protein(s) and opioids.

Sugen-morphine model of pulmonary arterial hypertension

Pulmonary arterial hypertension is a fatal disease associated with pulmonary vascular remodeling and right ventricular hypertrophy. Pre-clinical animal models that reproduce the human pulmonary arterial hypertension process and pharmacological response to available therapies are critical for future drug development. The most prevalent animal model reproducing many aspects of angioobliterative forms of pulmonary arterial hypertension is the rat Sugen/hypoxia model in which Sugen, a vascular endothelial growth factor receptor antagonist, primarily causes initiation of endothelial injury and later in the presence of hypoxia promotes proliferation of apoptosis-resistant endothelial cells. We previously demonstrated that exposure of human pulmonary microvascular endothelium to morphine and HIV-proteins results in initial apoptosis followed by increased proliferation. Here, we demonstrate that the double-hit of morphine and Sugen 5416 (Sugen–morphine) in rats leads to the development of pulmonary arterial hypertension with significant medial hypertrophy of pre-acinar pulmonary arteries along with neo-intimal thickening of intra-acinar vessels. In addition, the pulmonary smooth muscle and endothelial cells isolated from Sugen–morphine rats showed hyperproliferation and apoptotic resistance, respectively, in response to serum starvation. Our findings support that the dual hit model of Sugen 5416 and morphine provides another experimental strategy to induce significant pulmonary vascular remodeling and development of severe pulmonary arterial hypertension pathology in rats without exposure to hypoxia.