An official ATS workshop report: Emerging issues and current controversies in HIV-associated pulmonary diseases

Bacteriology of community-acquired pneumonia, antimicrobial susceptibility pattern and associated risk factors among HIV patients, Northeast Ethiopia: cross-sectional study

Objective

Pneumonia is an opportunistic infection and it is a major cause of mortality and morbidity among human immunodeficiency virus/acquired immune deficiency syndrome-positive patients. Previous studies have shown the dominant pathogens bacterial isolates were K. pneumoniae 27.0%, S. aureus 20.8%, S. pneumoniae 18.8% and E. coli 8.3%. This study aimed to determine bacteriology of community-acquired pneumonia, antimicrobial susceptibility pattern and associated risk factors among human immunodeficiency virus patients in the Northeast Ethiopia: cross-sectional study.

Methods

A health facility-based cross-sectional study was conducted from January to April 2021 at six health facilities in Dessie Town. A total of 378 community-acquired pneumonia patients suspected to be human immunodeficiency virus-positive were recruited using a consecutive sampling technique. Sociodemographic and clinical data were collected using a structured questionnaire. A two-milliliter sputum specimen was collected aseptically from each study participant. Samples were cultivated on blood agar, chocolate agar and MacConkey agar to isolate bacterial pathogens. To identify bacteria pathogens Gram stain, colony morphology and biochemical tests were performed. The Kirby-Bauer Disc Diffusion method was used to perform the antimicrobial susceptibility test. Descriptive statistics, logistic regression analysis was carried out using Statistical package for social science version 25 software. p-value < 0.05 with a corresponding 95% confidence interval (CI) was considered for statistical significance.

Result

The overall prevalence of bacterial pneumonia was 175 (46.3%). Gram-negative bacteria accounted for 119 (68%) and the predominant isolates identified were Streptococcus pneumoniae 49 (28%) followed by Klebsiella pneumoniae 46 (26.3%), Pseudomonas aeruginosa 34 (19.4%). There were 148 (84.6%) multidrug-resistant bacteria overall. Statistically significant factors included viral load, cigarette smoking, cluster of differentiation 4 count, alcohol use, World Health Organization clinical stages III and IV and low white blood cell count.

Conclusion

The study found that both multidrug resistance and bacterial pneumonia were high. Thus, bacterial culture and antimicrobial susceptibility tests should be routinely performed in health facilities in order to prevent and control the spread of bacterial infection and concurrent drug resistance.

Impaired differentiation of small airway basal stem/progenitor cells in people living with HIV

With highly active anti-retroviral therapy (HAART), higher incidence of airway abnormalities is common in the HIV population consistent with the concept of accelerated lung "aging". Our previous findings demonstrated that HIV induces human airway basal cells (BC) into destructive and inflammatory phenotypes. Since BC function as stem/progenitor cells of the small airway epithelium (SAE), responsible for self-renewal and differentiation of SAE, we hypothesized that BC from people living with HIV (PLWH) may have altered differentiation capacity that contribute to premature aging. The data demonstrates that BC from PLWH have impaired capacity to differentiate in vitro and senescent phenotypes including shortened telomeres, increased expression of β-galactosidase and cell cycle inhibitors, and mitochondrial dysfunction. In vitro studies demonstrated that BC senescence is partly due to adverse effects of HAART on BC. These findings provide an explanation for higher incidence of airway dysfunction and accelerated lung aging observed in PLWH.

Pulmonary Immune Dysregulation and Viral Persistence During HIV Infection

Despite the success of antiretroviral therapy (ART), people living with HIV continue to suffer from high burdens of respiratory infections, lung cancers and chronic lung disease at a higher rate than the general population. The lung mucosa, a previously neglected HIV reservoir site, is of particular importance in this phenomenon. Because ART does not eliminate the virus, residual levels of HIV that remain in deep tissues lead to chronic immune activation and pulmonary inflammatory pathologies. In turn, continuous pulmonary and systemic inflammation cause immune cell exhaustion and pulmonary immune dysregulation, creating a pro-inflammatory environment ideal for HIV reservoir persistence. Moreover, smoking, gut and lung dysbiosis and co-infections further fuel the vicious cycle of residual viral replication which, in turn, contributes to inflammation and immune cell proliferation, further maintaining the HIV reservoir. Herein, we discuss the recent evidence supporting the notion that the lungs serve as an HIV viral reservoir. We will explore how smoking, changes in the microbiome, and common co-infections seen in PLWH contribute to HIV persistence, pulmonary immune dysregulation, and high rates of infectious and non-infectious lung disease among these individuals.

Targeting Tat-TAR RNA Interaction for HIV-1 Inhibition

The HIV-1 Tat protein interacts with TAR RNA and recruits CDK9/cyclin T1 and other host factors to induce HIV-1 transcription. Thus, Tat–TAR RNA interaction, which is unique for HIV-1, represents an attractive target for anti-HIV-1 therapeutics. To target Tat–TAR RNA interaction, we used a crystal structure of acetylpromazine bound to the bulge of TAR RNA, to dock compounds from the Enamine database containing over two million individual compounds. The docking procedure identified 173 compounds that were further analyzed for the inhibition of HIV-1 infection. The top ten inhibitory compounds with IC₅₀ ≤ 6 µM were selected and the three least toxic compounds, T6780107 (IC₅₀ = 2.97 μM), T0516-4834 (IC₅₀ = 0.2 μM) and T5628834 (IC₅₀ = 3.46 μM), were further tested for HIV-1 transcription inhibition. Only the T0516-4834 compound showed selective inhibition of Tat-induced HIV-1 transcription, whereas the T6780107 compound inhibited equally basal and Tat-induced transcription and the T5628834 compound only inhibited basal HIV-1 transcription. The compounds were tested for the inhibition of translation and showed minimal (<25%) effect. The T0516-4834 compound also showed the strongest inhibition of HIV-1 RNA expression and p24 production in CEM T cells and peripheral blood mononuclear cells infected with HIV-1 IIIB. Of the three compounds, only the T0516-4834 compound significantly disrupted Tat–TAR RNA interaction. Additionally, of the three tested compounds, T5628834 and, to a lesser extent, T0516-4834 disrupted Tat–CDK9/cyclin T1 interaction. None of the three compounds showed significant inhibition of the cellular CDK9 and cyclin T1 levels. In silico modelling showed that the T0516-4834 compound interacted with TAR RNA by binding to the bulge formed by U23, U25, C39, G26,C39 and U40 residues. Taken together, our study identified a novel benzoxazole compound that disrupted Tat–TAR RNA interaction and inhibited Tat-induced transcription and HIV-1 infection, suggesting that this compound might serve as a new lead for anti-HIV-1 therapeutics.

Impact of human immunodeficiency virus on pulmonary vascular disease

With the advent of anti-retroviral therapy, non-AIDS-related comorbidities have increased in people living with HIV. Among these comorbidities, pulmonary hypertension (PH) is one of the most common causes of morbidity and mortality. Although chronic HIV-1 infection is independently associated with the development of pulmonary arterial hypertension, PH in people living with HIV may also be the outcome of various co-morbidities commonly observed in these individuals including chronic obstructive pulmonary disease, left heart disease and co-infections. In addition, the association of these co-morbidities and other risk factors, such as illicit drug use, can exacerbate the development of pulmonary vascular disease. This review will focus on these complex interactions contributing to PH development and exacerbation in HIV patients. We also examine the interactions of HIV proteins, including Nef, Tat, and gp120 in the pulmonary vasculature and how these proteins alter the endothelial and smooth muscle function by transforming them into susceptible PH phenotype. The review also discusses the available infectious and non-infectious animal models to study HIV-associated PAH, highlighting the advantages and disadvantages of each model, along with their ability to mimic the clinical manifestations of HIV-PAH.

HIV induces airway basal progenitor cells to adopt an inflammatory phenotype

Despite the introduction of anti-retroviral therapy, chronic HIV infection is associated with an increased incidence of other comorbidities such as COPD. Based on the knowledge that binding of HIV to human airway basal stem/progenitor cells (BC) induces a destructive phenotype by increased MMP-9 expression through MAPK signaling pathways, we hypothesized that HIV induces the BC to express inflammatory mediators that contribute to the pathogenesis of emphysema. Our data demonstrate that airway BC isolated from HAART-treated HIV+ nonsmokers spontaneously release inflammatory mediators IL-8, IL-1β, ICAM-1 and GM-CSF. Similarly, exposure of normal BC to HIV in vitro up-regulates expression of the same inflammatory mediators. These HIV-BC derived mediators induce migration of alveolar macrophages (AM) and neutrophils and stimulate AM proliferation. This HIV-induced inflammatory phenotype likely contributes to lung inflammation in HIV+ individuals and provides explanation for the increased incidence of COPD in HIV+ individuals.

HIV-1 Transcription Inhibitor 1E7-03 Restores LPS-Induced Alteration of Lung Leukocytes' Infiltration Dynamics and Resolves Inflammation in HIV Transgenic Mice

Human immunodeficiency virus (HIV)-infected individuals treated with anti-retroviral therapy often develop chronic non-infectious lung disease. To determine the mechanism of HIV-1-associated lung disease we evaluated the dynamics of lung leukocytes in HIV-1 transgenic (Tg) mice with integrated HIV-1 provirus. In HIV-Tg mice, lipopolysacharide (LPS) induced significantly higher levels of neutrophil infiltration in the lungs compared to wild-type (WT) mice. In WT mice, the initial neutrophil infiltration was followed by macrophage infiltration and fast resolution of leukocytes infiltration. In HIV-Tg mice, resolution of lung infiltration by both neutrophils and macrophages was significantly delayed, with macrophages accumulating in the lumen of lung capillaries resulting in a 45% higher rate of mortality. Trans-endothelial migration of HIV-Tg macrophages was significantly reduced in vitro and this reduction correlated with lower HIV-1 gene expression. HIV-1 transcription inhibitor, 1E7-03, enhanced trans-endothelial migration of HIV-Tg macrophages in vitro, decreased lung neutrophil infiltration in vivo, and increased lung macrophage levels in HIV-Tg mice. Moreover, 1E7-03 reduced levels of inflammatory IL-6 cytokine, improved bleeding score and decreased lung injury. Together this indicates that inhibitors of HIV-1 transcription can correct abnormal dynamics of leukocyte infiltration in HIV-Tg, pointing to the utility of transcription inhibition in the treatment of HIV-1 associated chronic lung disease.

Role of the lung microbiome in HIV pathogenesis

PURPOSE OF REVIEW

The purpose of this review is to summarize recent findings on the lung microbiome in HIV-infected patients and associated pulmonary diseases, and the relationship of airway microbial communities to metabolic and immune signatures within this patient population.

RECENT FINDINGS

The lung microbiome in HIV infection is a relatively new and rapidly developing field; early studies in the field produced inconclusive evidence as to whether HIV-infection changes the lower airway microbiome. More recent microbiome investigations have addressed these inconsistencies by incorporating systems biology approaches and laboratory models. Several investigations have now identified enrichment of Prevotella, Veillonella, and Streptococcus in the lower airways as consistent correlates of advanced HIV-infection and HIV-associated pulmonary diseases. These bacteria are associated with specific metabolic and immune profiles within the lung and circulation, providing the first indication that the lung microbiome may play a functional role in the pathogenesis of HIV-infection and HIV-associated pulmonary disease.

SUMMARY

This review summarizes knowledge to date on the lung microbiome in HIV infection, as well as challenges and accomplishments in the field within the last 2 years. Although the lung microbiome in HIV infection is still an emerging field, recent studies have formed a framework for future functional analysis of microbes in HIV pathogenesis.

HIV Reprograms Human Airway Basal Stem/Progenitor Cells to Acquire a Tissue-Destructive Phenotype

While highly active anti-retroviral therapy has dramatically improved the survival of HIV-infected individuals, there is an increased risk for other co-morbidities, such as COPD, manifesting as emphysema. Given that emphysema originates around the airways and that human airway basal cells (BCs) are adult airway stem/progenitor cells, we hypothesized that HIV reprograms BCs to a distinct phenotype that contributes to the development of emphysema. Our data indicate that HIV binds to but does not replicate in BCs. HIV binding to BCs induces them to acquire an invasive phenotype, mediated by upregulation of MMP-9 expression through activation of MAPK signaling pathways. This HIV-induced "destructive" phenotype may contribute to degradation of extracellular matrix and tissue damage relevant to the development of emphysema commonly seen in HIV⁺ individuals.

The respiratory microbiome of HIV-infected individuals

INTRODUCTION

The respiratory tract is constantly exposed to various environmental and endogenous microbes; however, unlike other similar mucosal surfaces, there has been limited investigation of the microbiome of the respiratory tract.

AREAS COVERED

In this review, we summarize the current state of knowledge of the bacterial, fungal, and viral respiratory microbiomes during HIV infection and how the microbiome might relate to HIV-associated lung disease. Expert commentary: HIV infection is associated with alterations in the respiratory microbiome. The clinical implications of lung microbial dysbiosis are however currently unknown. Mechanistic studies are needed to establish causality between shifts in the respiratory microbiome and pulmonary complications in HIV-infected individuals.

Effect of Advanced HIV Infection on the Respiratory Microbiome

RATIONALE

Previous work found the lung microbiome in healthy subjects infected with HIV was similar to that in uninfected subjects. We hypothesized the lung microbiome from subjects infected with HIV with more advanced disease would differ from that of an uninfected control population.

OBJECTIVES

To measure the lung microbiome in an HIV-infected population with advanced disease.

METHODS

16s RNA gene sequencing was performed on acellular bronchoalveolar lavage (BAL) fluid from 30 subjects infected with HIV with advanced disease (baseline mean CD4 count, 262 cells/mm(3)) before and up to 3 years after starting highly active antiretroviral therapy (HAART) and compared with 22 uninfected control subjects.

MEASUREMENTS AND MAIN RESULTS

The lung microbiome in subjects infected with HIV with advanced disease demonstrated decreased alpha diversity (richness and diversity) and greater beta diversity compared with uninfected BAL. Differences improved with HAART, but still persisted up to 3 years after starting therapy. Population dispersion in the group infected with HIV was significantly greater than in the uninfected cohort and declined after treatment. There were differences in the relative abundance of some bacteria between the two groups at baseline and after 1 year of therapy. After 1 year on HAART, HIV BAL contained an increased abundance of Prevotella and Veillonella, bacteria previously associated with lung inflammation.

CONCLUSIONS

The lung microbiome in subjects infected with HIV with advanced disease is altered compared with an uninfected population both in diversity and bacterial composition. Differences remain up to 3 years after starting HAART. We speculate an altered lung microbiome in HIV infection may contribute to chronic inflammation and lung complications seen in the HAART era.

The Differential Impact of Emphysema on Respiratory Symptoms and 6-Minute Walk Distance in HIV Infection

BACKGROUND

Emphysema is more prevalent in HIV-infected (HIV+) patients independent of smoking behavior. Nonetheless, health effects of emphysema in this population are poorly understood. We determined whether emphysema is associated with a greater burden of pulmonary symptoms and a lower 6-minute walk distance (6MWD) in HIV+ compared with HIV-uninfected (HIV-) subjects.

METHODS

We performed a cross-sectional analysis of 170 HIV+ and 153 HIV- subjects in the Examinations of HIV-Associated Lung Emphysema (EXHALE) cohort study. Subjects completed a self-assessment of respiratory symptoms, pulmonary function testing, and 6MWD testing as well as a chest computed tomography to determine emphysema severity. We used regression models to determine the association of emphysema with respiratory symptoms and 6MWD in HIV+ subjects and compared this to HIV- subjects.

RESULTS

Models stratified by HIV status demonstrated an association between >10% radiographic emphysema and chronic cough and/or phlegm and 6MWD in HIV+ subjects. These associations persisted among the subset without airflow obstruction: those with emphysema had 4.2 (95% confidence interval: 1.3 to 14) times the odds of chronic cough and/or phlegm and walked 60 m (95% confidence interval: 26 to 93) less distance than those without emphysema. There was no association between >10% emphysema and symptoms or 6MWD in HIV- subjects.

CONCLUSIONS

In our cohort, >10% radiographic emphysema was associated with chronic cough and/or phlegm and lower 6MWD in HIV+ but not HIV- subjects. These findings were robust even among HIV+ subjects with milder forms of emphysema and those without airflow obstruction, highlighting the clinical impact of emphysema in these patients.

Lung microbiome in human immunodeficiency virus infection

The lung microbiome plays a significant role in normal lung function and disease. Because microbial colonization is likely influenced by immunodeficiency, one would speculate that infection with human immunodeficiency virus (HIV) alters the lung microbiome. Furthermore, how this alteration might impact pulmonary complications now seen in HIV-infected patients on antiretroviral therapy (ART), which has shifted from opportunistic infections to diseases associated with chronic inflammation, is not known. There have been limited publications on the lung microbiome in HIV infection, many of them emanating from the Lung HIV Microbiome Project. Current evidence suggests that the lung microbiome in healthy HIV-infected individuals with preserved CD4 counts is similar to uninfected individuals. However, in individuals with more advanced disease, there is an altered alveolar microbiome characterized by a loss of richness and evenness (alpha diversity) within individuals. Furthermore, as a group the taxa making up the HIV-infected and uninfected lung microbiome are different (differences in beta diversity), and the HIV-infected population is more spread out (greater dispersion) than the uninfected population. These differences decline with ART, but even after effective therapy the alveolar microbiome in HIV-infected individuals contains increased amounts of signature bacteria, some of which have previously been associated with chronic lung inflammation. Furthermore, more recent investigations into the lung virome in HIV infection suggest that perturbations in lung viral communities also exist in HIV infection, and that these too are associated with evidence of lung inflammation. Thus, it is likely both microbiome and virome alterations in HIV infection contribute to lung inflammation in these individuals, which has important implications on the changing spectrum of pulmonary complications in patients living with HIV.

[Endobronchial ultrasonography (EBUS) for the internist]

Endobronchial ultrasonography (EBUS) is a recent mini-invasive technique allowing transbronchial needle aspiration (TBNA) of mediastinal lymph nodes as well as peribronchial lesions. EBUS was initially developed for lung cancer mediastinal staging. Over the years, indications for EBUS have been progressively extended to the scope of inflammatory disorders, mediastinal lymphomas, and infectious diseases. Particularly in immunosuppressed patients, including HIV-infected patients, EBUS allows the diagnosis of several diseases that involve the mediastinum, avoiding invasive surgical explorations such as mediastinoscopy or thoracoscopy. This review aims at discussing the technical aspects, and specifies indications, results, and limits of EBUS for the internist.

Chronic alcohol abuse and HIV disease progression: studies with the non-human primate model

The populations at risk for HIV infection, as well as those living with HIV, overlap with populations that engage in heavy alcohol consumption. Alcohol use has been associated with high-risk sexual behavior and an increased likelihood of acquiring HIV, as well as poor outcome measures of disease such as increased viral loads and declines in CD4+ T lymphocytes among those living with HIV-infections. It is difficult to discern the biological mechanisms by which alcohol use affects the virus:host interaction in human populations due to the numerous variables introduced by human behavior. The rhesus macaque infected with simian immunodeficiency virus has served as an invaluable model for understanding HIV disease and transmission, and thus, provides an ideal model to evaluate the effects of chronic alcohol use on viral infection and disease progression in a controlled environment. In this review, we describe the different macaque models of chronic alcohol consumption and summarize the studies conducted with SIV and alcohol. Collectively, they have shown that chronic alcohol consumption results in higher levels of plasma virus and alterations in immune cell populations that potentiate SIV replication. They also demonstrate a significant impact of chronic alcohol use on SIV-disease progression and survival. These studies highlight the utility of the rhesus macaque in deciphering the biological effects of alcohol on HIV disease. Future studies with this well-established model will address the biological influence of alcohol use on susceptibility to HIV, as well as the efficacy of anti-retroviral therapy.

Pulmonary Function in HIV-Infected Recreational Drug Users in the Era of Anti-Retroviral Therapy

BACKGROUND

Individuals with HIV infection commonly have pulmonary function abnormalities, including airflow obstruction and diffusion impairment, which may be more prevalent among recreational drug users. To date, the relationship between drug use and pulmonary function abnormalities among those with HIV remains unclear.

OBJECTIVE

To determine associations between recreational drug use and airflow obstruction, diffusion impairment, and radiographic emphysema in men and women with HIV.

METHODS

Cross-sectional analysis of pulmonary function and self-reported recreational drug use data from a cohort of 121 men and 63 women with HIV. Primary outcomes were the presence (yes/no) of: 1) airflow obstruction, (pre- or post-bronchodilator forced expiratory volume in 1 second/forced vital capacity<0.70); 2) moderate diffusion impairment (diffusing capacity for carbon monoxide <60% predicted); and 3) radiographic emphysema (>1% of lung voxels <-950 Hounsfield units). Exposures of interest were frequency of recreational drug use, recent (since last study visit) drug use, and any lifetime drug use. We used logistic regression to determine associations between recreational drug use and the primary outcomes.

RESULTS

HIV-infected men and women reported recent recreational drug use at 56.0% and 31.0% of their study visits, respectively, and 48.8% of men and 39.7% of women reported drug use since their last study visit. Drug use was not associated with airway obstruction or radiographic emphysema in men or women. Recent crack cocaine use was independently associated with moderate diffusion impairment in women (odds ratio 17.6; 95% confidence interval 1.3-249.6, p=0.03).

CONCLUSIONS

In this cross-sectional analysis, we found that recreational drug use was common among HIV-infected men and women and recent crack cocaine use was associated with moderate diffusion impairment in women. Given the increasing prevalence of HIV infection, any relationship between drug use and prevalence or severity of chronic pulmonary diseases could have a significant impact on HIV and chronic disease management.

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.

HIV and noncommunicable cardiovascular and pulmonary diseases in low- and middle-income countries in the ART era: what we know and best directions for future research

With the advent of effective antiretroviral therapy (ART), HIV is becoming a chronic disease. HIV-seropositive (+) patients on ART can expect to live longer and, as a result, they are at risk of developing chronic noncommunicable diseases related to factors, such as aging, lifestyle, long-term HIV infection, and the potential adverse effects of ART. Although data are incomplete, evidence suggests that even in low- and middle-income countries (LMICs), chronic cardiovascular and pulmonary diseases are increasing in HIV-positive patients. This review summarizes evidence-linking HIV infection to the most commonly cited chronic cardiovascular and pulmonary conditions in LMICs: heart failure, hypertension, coronary artery disease/myocardial infarction, stroke, obstructive lung diseases, and pulmonary arterial hypertension. We describe the observed epidemiology of these conditions, factors affecting expression in LMICs, and key populations that may be at higher risk (ie, illicit drug users and children), and finally, we suggest that strategic areas of research and training intended to counter these conditions effectively. As access to ART in LMICs increases, long-term outcomes among HIV-positive persons will increasingly be determined by a range of associated chronic cardiovascular and pulmonary complications. Actions taken now to identify those conditions that contribute to long-term morbidity and mortality optimize early recognition and diagnosis and implement effective prevention strategies and/or disease interventions are likely to have the greatest impact on limiting cardiovascular and pulmonary disease comorbidity and improving population health among HIV-positive patients in LMICs.

Community-Acquired Pneumonia in HIV-Infected Individuals

Community-acquired pneumonia continues to be an important complication of HIV infection. Rates of pneumonia decrease with the use of antiretroviral therapy but continue to be higher than in HIV uninfected individuals. Risk factors for pneumonia include low blood CD4+ count, unsuppressed plasma HIV load, smoking, injection drug use and renal impairment. Immunization against Streptococcus pneumoniae and smoking cessation can reduce this risk. It is unclear whether newly reported viral respiratory pathogens (such as the Middle East respiratory syndrome coronavirus, will be more of a problem in HIV-infected individuals than the general population.

Proteomic landscape of bronchoalveolar lavage fluid in human immunodeficiency virus infection

The lung is an important reservoir of human immunodeficiency virus (HIV). Individuals infected with HIV are more prone to pulmonary infections and chronic lung disorders. We hypothesized that comprehensively profiling the proteomic landscape of bronchoalveolar lavage fluid (BALF) in patients with HIV would provide insights into how this virus alters the lung milieu and contributes to pathogenesis of HIV-related lung diseases. BALF was obtained from five HIV-negative (HIV(-)) and six asymptomatic HIV-positive (HIV(+)) subjects not on antiretroviral therapy. Each sample underwent shotgun proteomic analysis based on HPLC-tandem mass spectrometry. Differentially expressed proteins between the groups were identified using statistical methods based on spectral counting. Mechanisms of disease were explored using functional annotation to identify overlapping and distinct pathways enriched between the BALF proteome of HIV(+) and HIV(-) subjects. We identified a total of 318 unique proteins in BALF of HIV(-) and HIV(+) subjects. Of these, 87 were differentially up- or downregulated between the two groups. Many of these differentially expressed proteins are known to interact with key HIV proteins. Functional analysis of differentially regulated proteins implicated downregulation of immune responses in lungs of HIV(+) patients. Combining shotgun proteomic analysis with computational methods demonstrated that the BALF proteome is significantly altered during HIV infection. We found that immunity-related pathways are underrepresented in HIV(+) patients. These findings implicate mechanisms whereby HIV invokes local immunosuppression in the lung and increases the susceptibility of HIV(+) patients to develop a wide range of infectious and noninfectious pulmonary diseases.

Respiratory infections in HIV-infected adults: epidemiology, clinical features, diagnosis and treatment

PURPOSE OF REVIEW

Using the evidence published over the last 2 years, this review discusses the epidemiology, diagnosis, treatment and prevention of HIV-related pulmonary infections other than mycobacterial disease.

RECENT FINDINGS

Longstanding, vertically acquired and apparently stable HIV infection is associated with significant and symptomatic small airways disease in African adolescents. The use of population-based pneumococcal vaccination in children is changing the severity and serotypes associated with HIV-related pneumococcal disease. Data on the use of blood 1,3,β-D-glucan show it has promise as a rule-out test for Pneumocystis pneumonia (PCP).

SUMMARY

With widespread antiretroviral medication usage, the pattern of HIV-associated pulmonary disease is changing. Whereas opportunistic infections such as PCP still occur in people not using antiretroviral therapy (ART), HIV-related infections are similar to those present in the general population. Chronic lung disease is more prevalent, leading to its own infectious complications. The use of specific immunizations against infections is important, though their precise benefit with concomitant widespread ART and population-based vaccination programmes in the non-HIV community is undetermined.

HIV-associated bacterial pneumonia

Community-acquired bacterial pneumonia (CAP) remains one of the most common opportunistic infections in patients who are infected with the human immunodeficiency virus (HIV). The risk of CAP increases as the CD4 cell count decreases. The common bacterial pathogens that cause CAP in HIV-infected persons are similar to those in HIV-uninfected individuals, with the pneumococcus being the most common pathogen. Prevention of CAP remains critical and necessitates a comprehensive approach addressing, among many other factors, cigarette smoking cessation strategies, antiretroviral therapy adherence, and immunization against those infections for which effective vaccinations are available.

Impact of antiretroviral therapy on lung immunology and inflammation

Human immunodeficiency virus (HIV) infection causes profound changes in the lung compartment characterized by macrophage and lymphocyte activation, secretion of proinflammatory cytokines and chemokines, and accumulation of CD8 T cells in the alveolar space, leading to lymphocytic alveolitis. Because many of the changes seen in the lung can be attributed to the direct effect of HIV on immune cells, therapy to reduce the HIV burden should have significant beneficial effects. Indeed, antiretroviral therapy rapidly reduces the viral burden in the lung, number of CD8 T cells in the alveolar space, and amount of proinflammatory cytokines and chemokines in bronchoalveolar lavage.

Effect of bacterial pneumonia on lung simian immunodeficiency virus (SIV) replication in alcohol consuming SIV-infected rhesus macaques

BACKGROUND

Opportunistic infections in human immunodeficiency virus (HIV)-infected persons have been shown to increase the rate of HIV replication. In populations where prophylaxis against Pneumocystis pneumonia is utilized, bacterial pneumonia is now the leading cause of lower respiratory tract infection in HIV+ patients. Our prior studies have shown that chronic alcohol consumption in demarcated simian immunodeficiency virus (SIV)-infected rhesus macaques increases plasma viral load set point and accelerates progression to end-stage acquired immune deficiency syndrome. While chronic alcohol abuse is well known to increase the incidence and severity of bacterial pneumonia, the impact of alcohol consumption on local and systemic SIV/HIV burden during lung infection is unknown. Therefore, we utilized the macaque SIV infection model to examine the effect of chronic ethanol (EtOH) feeding on SIV burden during the course of pulmonary infection with Streptococcus pneumoniae, the most commonly identified etiology of bacterial pneumonia in HIV+ and HIV- persons in developed countries.

METHODS

Alcohol was administered starting 3 months before SIVmac251 inoculation to the end of the study via an indwelling intragastric catheter to achieve a plasma alcohol concentration of 50 to 60 mM. Control animals received isocaloric sucrose. Four months after SIV infection, the right lung was inoculated with 2 × 10(6) CFU S. pneumoniae.

RESULTS

Leukocyte recruitment into the lung, pulmonary bacterial clearance, and clinical course were similar between EtOH and control groups. While plasma SIV viral load was similar between groups postpneumonia, chronic EtOH-fed macaques showed a prolonged increase in SIV RNA in bronchoalveolar lavage fluid. Alveolar macrophages isolated from EtOH-fed macaques 1 day post-pneumonia showed greater nuclear factor kappa beta (NF-κB) activation.

CONCLUSIONS

This study indicates that chronic EtOH feeding results in enhanced local, but not systemic, SIV replication following pneumococcal pneumonia. Increased NF-κB activity in the setting of chronic EtOH ingestion may play a mechanistic role in this observation.

A comparison of seriously ill patients with or without AIDS requiring prolonged mechanical ventilation

PURPOSE

The aim of this study was to compare differences in underlying diagnoses, weaning outcomes, discharge disposition, and survival in prolonged mechanical ventilator (PMV)-dependent patients with and without AIDS.

METHODS

Ninety consecutive AIDS patients requiring PMV were retrospectively matched with 90 clinically similar non-AIDS patients to form matched cohorts to determine differences in their outcomes.

RESULTS

AIDS patients had more acute diagnoses requiring PMV, whereas non-AIDS patients had more chronic diagnoses (P < .001). Weaning outcomes were alike with 31 (35%) AIDS and 37 (41%) non-AIDS patients successfully weaned. More AIDS patients went home, and fewer, to nursing facilities (P = .04). In each cohort, successfully weaned patients had significantly longer survival than their unweaned counterparts (all P < .001). Successful weaning reduced the risk of death in AIDS and non-AIDS patients (hazard ratios, 0.29 and 0.20; 95% confidence intervals, 0.17-0.50 and 0.11-0.36, respectively; all P < .001).

CONCLUSIONS

AIDS had little effect on weaning success or survival. Successful weaning increased survival regardless of a diagnosis of AIDS. The AIDS patients had more home discharges and fewer to nursing facilities, which likely resulted from the AIDS patients having more acute illnesses leading to PMV than the non-AIDS patients.

Lung cancer: epidemiology, etiology, and prevention

Lung cancer is the leading cause of cancer death in the United States and around the world. A vast majority of lung cancer deaths are attributable to cigarette smoking, and curbing the rates of cigarette smoking is imperative. Understanding the epidemiology and causal factors of lung cancer can provide additional foundation for disease prevention. This article focuses on modifiable risk factors, including tobacco smoking, occupational carcinogens, diet, and ionizing radiation. It also discusses briefly the molecular and genetic aspects of lung carcinogenesis.

Lung cancer: epidemiology, etiology, and prevention

Lung cancer is the leading cause of cancer death in the United States and around the world. A vast majority of lung cancer deaths are attributable to cigarette smoking, and curbing the rates of cigarette smoking is imperative. Understanding the epidemiology and causal factors of lung cancer can provide additional foundation for disease prevention. This article focuses on modifiable risk factors, including tobacco smoking, occupational carcinogens, diet, and ionizing radiation. It also discusses briefly the molecular and genetic aspects of lung carcinogenesis.