Noninfectious pulmonary complications of HIV/AIDS

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.

Inflammatory Mechanisms and Cascades Contributing to Neurocognitive Impairment in HIV/AIDS

Neurocognitive impairment caused by chronic human immunodeficiency virus (HIV) infection is a growing concern. In this chapter we discuss the inflammatory mechanisms underlying the pathology of asymptomatic and mild neurocognitive impairment in the context of antiretroviral therapy. We discuss the role of HIV, viral proteins, and virally infected cells on the development of neuroinflammation and the effect of viral proteins on the cells of the central nervous system.We examine how these collective factors result in an inflammatory context that triggers the development of neurocognitive impairment in HIV. We assess the contribution of antiretrovirals and drugs of abuse, including methamphetamine, cannabis, and opioids, to the neurotoxic and neuroinflammatory milieu that leads to the development of neurocognitive impairment in HIV-infected individuals. We also examined circulating biomarkers, NF-L, sCD163, and sCD14, pertinent to identifying changes in the CNS that could indicate real-time changes in patient physiology. Lastly, we discuss future studies, such as exosomes and the microbiome, which could play a role in the HIV-induced neuroinflammation that eventually manifests as cognitive impairment.

Severe airflow obstruction in vertically acquired HIV infection

It is becoming increasingly clear that human immunodeficiency virus (HIV) infection, either independently or in concert with opportunistic infections like pulmonary tuberculosis, is a risk factor for the development of chronic airflow limitation. In the majority of patients the etiology of this obstructive ventilatory defect is multifactorial. Post-infectious obliterative bronchiolitis, post-tuberculous lung damage (including bronchiectasis), immune reconstitution and the direct effects of HIV viral infection may all play a role. With increases in life expectancy and decreases in infectious complications in patients taking antiretroviral medications, the importance of HIV-associated chronic lung disease as a cause of pulmonary disability is likely to increase. This is particularly relevant in regions like sub-Saharan Africa, where both HIV infection and tuberculosis are highly prevalent. Here, to illustrate the complexity of this interaction, we present the case of a 15-year-old girl with vertically acquired HIV infection, multiple episodes of pulmonary infection, and severe airflow obstruction.

Lung function abnormalities in HIV-infected adults and children

Despite the advent of antiretroviral therapy (ART), the human immunodeficiency virus (HIV) epidemic remains a global health crisis with a high burden of respiratory disease among infected persons. While the early complications of the epidemic were dominated by opportunistic infections, improved survival has led to the emergence of non-infectious conditions that are associated with chronic respiratory symptoms and pulmonary disability. Obstructive ventilatory defects and reduced diffusing capacity are common findings in adults, and the association between HIV and chronic obstructive pulmonary disease is increasingly recognized. There is synergism between viral factors, opportunistic infections, conventional influences like tobacco smoke and biomass fuel exposure, and potentially, the immunological effects of ART on the development of HIV-associated chronic obstructive lung disease. Pulmonary function data for HIV-infected infants and children are scarce, but shows that bronchiectasis and obliterative bronchiolitis with severe airflow limitation are major problems, particularly in the developing world. However, studies from these regions are sorely lacking. There is thus a major unmet need to understand the influences of chronic HIV infection on the lung in both adults and children, and to devise strategies to manage and prevent these diseases in HIV-infected individuals. It is important for clinicians working with HIV-infected individuals to have an appreciation of their effects on measurements of lung function. This review therefore summarizes the lung function abnormalities described in HIV-positive adults and children, with an emphasis on obstructive lung disease, and examines potential pathogenic links between HIV and the development of chronic pulmonary disability.

Clinical review: Respiratory failure in HIV-infected patients--a changing picture

Respiratory failure in HIV-infected patients is a relatively common presentation to ICU. The debate on ICU treatment of HIV-infected patients goes on despite an overall decline in mortality amongst these patients since the AIDS epidemic. Many intensive care physicians feel that ICU treatment of critically ill HIV patients is likely to be futile. This is mainly due to the unfavourable outcome of HIV patients with Pneumocystis jirovecii pneumonia who need mechanical ventilation. However, the changing spectrum of respiratory illness in HIV-infected patients and improved outcome from critical illness remain under-recognised. Also, the awareness of certain factors that can affect their outcome remains low. As there are important ethical and practical implications for intensive care clinicians while making decisions to provide ICU support to HIV-infected patients, a review of literature was undertaken. It is notable that the respiratory illnesses that are not directly related to underlying HIV disease are now commonly encountered in the highly active antiretroviral therapy (HAART) era. The overall incidence of P. jirovecii as a cause of respiratory failure has declined since the AIDS epidemic and sepsis including bacterial pneumonia has emerged as a frequent cause of hospital and ICU admission amongst HIV patients. The improved overall outcome of HIV patients needing ICU admission is related to advancement in general ICU care, including adoption of improved ventilation strategies. An awareness of respiratory illnesses in HIV-infected patients along with an appropriate diagnostic and treatment strategy may obviate the need for invasive ventilation and improve outcome further. HIV-infected patients presenting with respiratory failure will benefit from early admission to critical care for treatment and support. There is evidence to suggest that continuing or starting HAART in critically ill HIV patients is beneficial and hence should be considered after multidisciplinary discussion. As a very high percentage (up to 40%) of HIV patients are not known to be HIV infected at the time of ICU admission, the clinicians should keep a low threshold for requesting HIV testing for patients with recurrent pneumonia.

Other HIV-associated pneumonias

The incidence, mortality, and epidemiology of human immunodeficiency virus (HIV)-associated pulmonary infections have changed as a result of effective antiretroviral and prophylaxis antimicrobial therapy. The clinical presentation, radiographic abnormalities, and treatment of pneumonia from various uncommon pathogens in patients with AIDS can be different from those in immunocompetent patients. Advances in invasive and noninvasive testing and molecular biological techniques have improved the diagnosis and prognosis of pulmonary infections in patients infected with HIV. This review focuses on pulmonary infections from nontuberculosis mycobacteria, cytomegalovirus, fungi (aspergillosis, cryptococcosis, endemic fungi), and parasites (toxoplasmosis), and uncommon bacterial pneumonia (nocardiosis, rhodococcosis) in these patients.

A novel expression of exercise induced pulmonary hypertension in human immunodeficiency virus patients: a pilot study

Background:

Patients with the human immunodeficiency virus (HIV) are at risk for multiple pulmonary complications including pulmonary hypertension. Exercise induced pulmonary hypertension (EIPH) has been previously described in patients with scleroderma, sickle cell disease and chronic obstructive pulmonary disease, yet has not been associated with the HIV population.

Methods:

A prospective case-control study design was implemented. Four HIV patients with unexplained dyspnea and four healthy controls underwent symptom-limited stationary bicycle exercise. Transthoracic Doppler Echocardiography was used to measure tricuspid regurgitation velocity which was used to calculate the right ventricular to right atrial pressure (RV-RA) gradient at rest and at peak exercise using the simplified Bernoulli’s equation. Change in RV-RA gradient between rest and peak exercise was calculated and considered to represent change in pulmonary arterial systolic pressure.

Results:

The mean age was 41.25 years (±8.7) for patients and 33.5 years (±6.0) for controls. The mean CD4 count of patients was 191.5 cells/μL (±136.2). Patients had a significantly higher increase in RV-RA gradient as compared to controls (180.2% vs. 27.5%, p = 0.03).

Discussion:

This pilot study suggests that it is feasible to use recumbent bicycle and transthoracic Doppler echocardiography for the evaluation of EIPH among HIV patients with dyspnea of unknown etiology. The study is too small to draw any broad conclusion. Further evaluation of this concept with a larger study is warranted.

Sudden Death from Pulmonary Causes

This chapter seeks to survey many of the common pathological entities identified in the lungs at autopsy and the potential role of pulmonary disease in formulating an opinion regarding the cause of death. Appreciation of pulmonary pathology in the medicolegal context is important as it frequently contributes to the immediate or underlying mechanisms of death. The primacy of the lungs in breathing and their coordinated function with the cardiovascular system means that ­pulmonary failure can rapidly compromise tissue oxygenation and body chemistry, leading to an alteration in blood pH, hypoxic damage to downstream tissues and ultimately multiorgan failure and death. Moreover, given that the lungs have direct contact with the environment through inhalation and receive approximately 50% of the cardiac output with each beat of the heart, they may be adversely affected by hazardous agents from the outside world or other pathologic processes not primarily located in the lungs. The range of topics discussed herein is limited by design to deaths due to disease and largely foregoes discussion of more forensically relevant issues relating to toxicology or trauma. Furthermore, the content and format of this chapter is not intended to be encyclopedic, but rather attempts to highlight selected issues regarding pulmonary disease of potential relevance to surgical or forensic pathologists who perform medicolegal postmortem examinations.

Pulmonary involvement in Kaposi sarcoma: correlation between imaging and pathology

Kaposi sarcoma is a low-grade mesenchymal tumor involving blood and lymphatic vessels. There are four variants of this disease, each presenting a different clinical manifestation: classic or sporadic, African or endemic, organ transplant-related or iatrogenic, and AIDS-related or epidemic. Kaposi sarcoma is the most common tumor among patients with HIV infection, occurring predominantly in homosexual or bisexual men. The pulmonary involvement in Kaposi sarcoma occurs commonly in critically immunosupressed patients who commonly have had preceding mucocutaneous or digestive involvement.

The etiology of Kaposi sarcoma is not precisely established; genetic, hormonal, and immune factors, as well as infectious agents, have all been implicated. There is evidence from epidemiologic, serologic, and molecular studies that Kaposi sarcoma is associated with human herpes virus type 8 infection. The disease starts as a reactive polyclonal angioproliferative response towards this virus, in which polyclonal cells change to form oligoclonal cell populations that expand and undergo malignant transformation.

The diagnosis of pulmonary involvement in Kaposi sarcoma usually can be made by a combination of clinical, radiographic, and laboratory findings, together with the results of bronchoscopy and transbronchial biopsy. Chest high-resolution computed tomography scans commonly reveal peribronchovascular and interlobular septal thickening, bilateral and symmetric ill-defined nodules in a peribronchovascular distribution, fissural nodularity, mediastinal adenopathies, and pleural effusions. Correlation between the high-resolution computed tomography findings and the pathology revealed by histopathological analysis demonstrate that the areas of central peribronchovascular infiltration represent tumor growth involving the bronchovascular bundles, with nodules corresponding to proliferations of neoplastic cells into the pulmonary parenchyma. The interlobular septal thickening may represent edema or tumor infiltration, and areas of ground-glass attenuation correspond to edema and the filling of air spaces with blood. These findings are a result of the propensity of Kaposi sarcoma to grow in the peribronchial and perivascular axial interstitial spaces, often as continuous sheets of tumor tissue.

In conclusion, radiological findings can play a major role in the diagnosis of pulmonary Kaposi sarcoma since characteristic patterns may be observed. The presence of these patterns in patients with AIDS is highly suggestive of Kaposi sarcoma.

HIV-1 transgene expression in rats causes oxidant stress and alveolar epithelial barrier dysfunction

Background

HIV-infected individuals are at increased risk for acute and chronic airway disease even though there is no evidence that the virus can infect the lung epithelium. Although HIV-related proteins including gp120 and Tat can directly cause oxidant stress and cellular dysfunction, their effects in the lung are unknown. The goal of this study was to determine the effects of HIV-1 transgene expression in rats on alveolar epithelial barrier function. Alveolar epithelial barrier function was assessed by determining lung liquid clearance in vivo and alveolar epithelial monolayer permeability in vitro. Oxidant stress in the alveolar space was determined by measuring the glutathione redox couple by high performance liquid chromatography, and the expression and membrane localization of key tight junction proteins were assessed. Finally, the direct effects of the HIV-related proteins gp120 and Tat on alveolar epithelial barrier formation and tight junction protein expression were determined.

Results

HIV-1 transgene expression caused oxidant stress within the alveolar space and impaired epithelial barrier function even though there was no evidence of overt inflammation within the airways. The expression and membrane localization of the tight junction proteins zonula occludens-1 and occludin were decreased in alveolar epithelial cells from HIV-1 transgenic rats. Further, treating alveolar epithelial monolayers from wild type rats in vitro with recombinant gp120 or Tat for 24 hours reproduced many of the effects on zonula occludens-1 and occludin expression and membrane localization.

Conclusion

Taken together, these data indicate that HIV-related proteins cause oxidant stress and alter the expression of critical tight junction proteins in the alveolar epithelium, resulting in barrier dysfunction.

Lymphatics in lung disease

The lymphatic circulation appears to be a vital component in lung biology in health and in disease. Animal models have established the role of the lymphatic circulation in neoplastic and inflammatory diseases of the lung, such as asthma and cancer, and allowed for the understanding of the molecular controls of lymphangiogenesis in normal lung development. Understanding the role of lymphatics in human lung disease appears likely to contribute to the understanding of the pathogenesis of disease and the development of novel therapeutic targets.

Imagerie des pathologies thoraciques chez le patient VIH au stade sida

The imaging features of infectious and non-infectious pathologies in HIV patients with AIDS (less than 200 CD4/mm3) are illustrated. Opportunistic infections, tumors and vascular pathologies have variable appearances based on the degree of immunosuppression and patient compliance with opportunistic infection prophylaxis. Because of advances in retroviral treatments and wider use of anti-infectious prophylaxis, thoracic pathologies in AIDS patients are less frequent but must nonetheless be recognized, and diagnosis should be suggested in patients with unknown serologic status.

Pulmonary hypertension can be a sequela of prior Pneumocystis pneumonia

Improved treatment regimens have reduced fatalities from opportunistic diseases, such as Pneumocystis pneumonia, in AIDS patients. However, serious chronic conditions, including pulmonary hypertension (PH), are increasing in this group. We report here that when CD4 T cells in Pneumocystis-infected mice are temporally depleted and then allowed to return, the extended inflammation results in PH that persists after Pneumocystis is eliminated. Using this model of PH, we have found that i) the onset of PH is correlated with the return of CD4 T cells, but PH persists after CD4 levels diminish; ii) vascular remodeling accompanies PH, but whereas temporary medial hypertrophy is evident with transient PH in immunocompetent mice, persistent PH is associated with perivascular fibrosis; iii) elevated levels of the fibrotic mediator FIZZ1 are found in bronchoalveolar lavage fluid of mice with persistent PH; and iv) although Th2-related mechanisms may be involved in PH etiology, PH still occurs in interleukin-4 receptor-deficient mice under these conditions. Overall, the data presented here demonstrate that the immune response to an infectious disease pathogen, such as Pneumocystis, can, when perturbed and prolonged, lead to later development of a serious chronic condition such as PH.

Reversible right ventricular dysfunction in patients with HIV infection

Human immunodeficiency virus-related cardiomyopathy is characterized by global left ventricular (LV) dysfunction commonly associated with biventricular dilation. Human immunodeficiency virus (HIV) cardiomyopathy carries a poor prognosis, and the role of antiretroviral therapy in the reversal of heart failure is not very clear. We report two patients with HIV infection who presented with severe right ventricular (RV) dysfunction in the absence of pulmonary parenchymal, pulmonary arterial and left ventricular myocardial involvement. During the period of intensive antiretroviral therapy, the symptoms of right heart failure progressively and remarkably improved. This was accompanied by normalization of right ventricular size and RV function documented by repeat echocardiograms. Given that the serologic tests for opportunistic infections were negative, and the RV function improvement correlated with a decrement in the viral load, it is likely that the cardiomyopathy was due to direct infection by HIV. These cases illustrate that there can be isolated involvement of the right heart in the absence of lung, significant pulmonary vascular and left ventricular disease, and also that the antiretroviral therapy might reverse the cardiomyopathy.

Induction of apoptosis and endothelin-1 secretion in primary human lung endothelial cells by HIV-1 gp120 proteins

Pulmonary hypertension associated with human immunodeficiency virus (HIV) infection also involves injury to the lung endothelium. However, the pathogenesis of HIV-induced pulmonary hypertension is not known; we hypothesized that HIV or secreted viral proteins could play a role in vascular injury and the increased frequency of pulmonary hypertension observed in HIV-infected patients. Here, we report that exposure of HIV-1 gp120 proteins to primary human lung microvascular endothelial cells causes apoptosis, as assessed by TUNEL assay, Annexin-V staining, and DNA laddering. Using ribonuclease protection assay and Western blotting we find that gp120-induced apoptosis of lung endothelial cells involves a down-regulation in Bcl-xl mRNA and proteins. In addition, gp120 significantly increases secretion of the potent vasoconstrictor endothelin-1 by human lung endothelial cells. These data suggest that secreted HIV gp120 proteins induce lung endothelial cell injury and could contribute to the development of HIV-associated pulmonary hypertension.

Ortner syndrome and haemophilia

Compression and paralysis of the left recurrent laryngeal nerve by a dilated pulmonary artery is a rare complication of pulmonary hypertension. We here report the case of a patient with severe haemophilia A and HIV infection who presented with a persistent hoarseness of voice and a left vocal cord palsy caused by HIV-associated pulmonary hypertension. This case suggests that HIV-associated pulmonary hypertension should be suspected in any HIV patient presenting with unexplained left vocal cord palsy.