Pathogenesis of HIV-Related Lung Disease: Immunity, Infection, and Inflammation.

Despite anti-retroviral therapy (ART), human immunodeficiency virus-1 (HIV)-related pulmonary disease continues to be a major cause of morbidity and mortality for people living with HIV (PLWH). The spectrum of lung diseases has changed from acute opportunistic infections resulting in death to chronic lung diseases for those with access to ART. Chronic immune activation and suppression can result in impairment of innate immunity and progressive loss of T cell and B cell functionality with aberrant cytokine and chemokine responses systemically as well as in the lung. HIV can be detected in the lungs of PLWH and has profound effects on cellular immune functions. In addition, HIV-related lung injury and disease can occur secondary to a number of mechanisms including altered pulmonary and systemic inflammatory pathways, viral persistence in the lung, oxidative stress with additive effects of smoke exposure, microbial translocation, and alterations in the lung and gut microbiome. Although ART has had profound effects on systemic viral suppression in HIV, the impact of ART on lung immunology still needs to be fully elucidated. Understanding of the mechanisms by which HIV-related lung diseases continue to occur is critical to the development of new preventive and therapeutic strategies to improve lung health in PLWH.

Differentiation of Prior SARS-CoV-2 Infection and Postacute Sequelae by Standard Clinical Laboratory Measurements in the RECOVER Cohort.

BACKGROUND: There are currently no validated clinical biomarkers of postacute sequelae of SARS-CoV-2 infection (PASC). OBJECTIVE: To investigate clinical laboratory markers of SARS-CoV-2 and PASC. DESIGN: Propensity score-weighted linear regression models were fitted to evaluate differences in mean laboratory measures by prior infection and PASC index (≥12 vs. 0). (ClinicalTrials.gov: NCT05172024). SETTING: 83 enrolling sites. PARTICIPANTS: RECOVER-Adult cohort participants with or without SARS-CoV-2 infection with a study visit and laboratory measures 6 months after the index date (or at enrollment if >6 months after the index date). Participants were excluded if the 6-month visit occurred within 30 days of reinfection. MEASUREMENTS: Participants completed questionnaires and standard clinical laboratory tests. RESULTS: Among 10 094 participants, 8746 had prior SARS-CoV-2 infection, 1348 were uninfected, 1880 had a PASC index of 12 or higher, and 3351 had a PASC index of zero. After propensity score adjustment, participants with prior infection had a lower mean platelet count (265.9 × 109 cells/L [95% CI, 264.5 to 267.4 × 109 cells/L]) than participants without known prior infection (275.2 × 109 cells/L [CI, 268.5 to 282.0 × 109 cells/L]), as well as higher mean hemoglobin A1c (HbA1c) level (5.58% [CI, 5.56% to 5.60%] vs. 5.46% [CI, 5.40% to 5.51%]) and urinary albumin-creatinine ratio (81.9 mg/g [CI, 67.5 to 96.2 mg/g] vs. 43.0 mg/g [CI, 25.4 to 60.6 mg/g]), although differences were of modest clinical significance. The difference in HbA1c levels was attenuated after participants with preexisting diabetes were excluded. Among participants with prior infection, no meaningful differences in mean laboratory values were found between those with a PASC index of 12 or higher and those with a PASC index of zero. LIMITATION: Whether differences in laboratory markers represent consequences of or risk factors for SARS-CoV-2 infection could not be determined. CONCLUSION: Overall, no evidence was found that any of the 25 routine clinical laboratory values assessed in this study could serve as a clinically useful biomarker of PASC. PRIMARY FUNDING SOURCE: National Institutes of Health.

Lung Function in Women With and Without Human Immunodeficiency Virus.

BACKGROUND: Prior studies have found that human immunodeficiency virus (HIV) infection is associated with impaired lung function and increased risk of chronic lung disease, but few have included large numbers of women. In this study, we investigate whether HIV infection is associated with differences in lung function in women. METHODS: This was a cross-sectional analysis of participants in the Women's Interagency HIV Study, a racially and ethnically diverse multicenter cohort of women with and without HIV. In 2018-2019, participants at 9 clinical sites were invited to perform spirometry. Single-breath diffusing capacity for carbon monoxide (DLCO) was also measured at selected sites. The primary outcomes were the post-bronchodilator forced expiratory volume in 1 second (FEV1) and DLCO. Multivariable regression modeling was used to analyze the association of HIV infection and lung function outcomes after adjustment for confounding exposures. RESULTS: FEV1 measurements from 1489 women (1062 with HIV, 427 without HIV) and DLCO measurements from 671 women (463 with HIV, 208 without HIV) met standards for quality and reproducibility. There was no significant difference in FEV1 between women with and without HIV. Women with HIV had lower DLCO measurements (adjusted difference, -0.73 mL/min/mm Hg; 95% confidence interval, -1.33 to -.14). Among women with HIV, lower nadir CD4 + cell counts and hepatitis C virus infection were associated with lower DLCO measurements. CONCLUSIONS: HIV was associated with impaired respiratory gas exchange in women. Among women with HIV, lower nadir CD4 + cell counts and hepatitis C infection were associated with decreased respiratory gas exchange.

Development of a Definition of Postacute Sequelae of SARS-CoV-2 Infection.

Importance: SARS-CoV-2 infection is associated with persistent, relapsing, or new symptoms or other health effects occurring after acute infection, termed postacute sequelae of SARS-CoV-2 infection (PASC), also known as long COVID. Characterizing PASC requires analysis of prospectively and uniformly collected data from diverse uninfected and infected individuals. Objective: To develop a definition of PASC using self-reported symptoms and describe PASC frequencies across cohorts, vaccination status, and number of infections. Design, Setting, and Participants: Prospective observational cohort study of adults with and without SARS-CoV-2 infection at 85 enrolling sites (hospitals, health centers, community organizations) located in 33 states plus Washington, DC, and Puerto Rico. Participants who were enrolled in the RECOVER adult cohort before April 10, 2023, completed a symptom survey 6 months or more after acute symptom onset or test date. Selection included population-based, volunteer, and convenience sampling. Exposure: SARS-CoV-2 infection. Main Outcomes and Measures: PASC and 44 participant-reported symptoms (with severity thresholds). Results: A total of 9764 participants (89% SARS-CoV-2 infected; 71% female; 16% Hispanic/Latino; 15% non-Hispanic Black; median age, 47 years [IQR, 35-60]) met selection criteria. Adjusted odds ratios were 1.5 or greater (infected vs uninfected participants) for 37 symptoms. Symptoms contributing to PASC score included postexertional malaise, fatigue, brain fog, dizziness, gastrointestinal symptoms, palpitations, changes in sexual desire or capacity, loss of or change in smell or taste, thirst, chronic cough, chest pain, and abnormal movements. Among 2231 participants first infected on or after December 1, 2021, and enrolled within 30 days of infection, 224 (10% [95% CI, 8.8%-11%]) were PASC positive at 6 months. Conclusions and Relevance: A definition of PASC was developed based on symptoms in a prospective cohort study. As a first step to providing a framework for other investigations, iterative refinement that further incorporates other clinical features is needed to support actionable definitions of PASC.

Use of Baricitinib in Patients With Moderate to Severe Coronavirus Disease 2019.

Hyperinflammation is associated with increased mortality in coronavirus disease 2019 (COVID-19). In this retrospective, uncontrolled patient cohort with moderate -severe COVID-19, treatment with baricitinib plus hydroxychloroquine was associated with recovery in 11 of 15 patients. Baricitinib for the treatment of COVID-19 should be further investigated in randomized, controlled clinical trials.

Twelve tips for developing and implementing a medical education Twitter chat.

Live discussions on the social media site Twitter or Twitter chats are gaining popularity as powerful tools for engaging a broad audience in an interactive discussion. Medical education, in particular, is experiencing an increase in the use of this modality to support informal learning, as a means to encourage collaboration and share best practices, and as a platform for large-scale mentorship. Despite this growth in popularity, there are limited data to guide medical educators on the fundamentals of organizing a Twitter chat. In this Twelve Tips article, we discuss strategies relevant to potential Twitter chat organizers. We have arranged the tips chronologically, beginning with a discussion of initial considerations when planning and formulating a chat topic and publicizing the chat to potentially interested people and groups, followed by practical considerations while hosting the chat, and finally strategies for evaluating and extending a Twitter chat's impact.

The Impact of Antiretroviral Therapy on Lung Immunology.

Despite the introduction of antiretroviral therapy (ART), human immunodeficiency virus-1 (HIV) continues to cause a major impact worldwide. HIV-induced lung disease continues to represent a significant source of morbidity and mortality, although the spectrum of pulmonary diseases has changed. HIV significantly affects the lung, causing acute and chronic cellular changes in the alveolar space. The impact of ART on lung immunology still needs to be fully elucidated. Similar to the periphery, ART affects HIV viral load and reconstitutes CD4(+) T cells in the lung. ART has been associated with significant decreases in bronchoalveolar lavage lymphocytes and increases in B-cell numbers and functionality, resulting in improved immune responses to vaccinations. There are substantial clinical implications of these ART-induced alterations, including the emergence of immune reconstitution inflammatory syndrome and the increased incidences of noninfectious lung diseases, such as lung cancer and chronic obstructive lung disease. There continues to be many unanswered questions regarding the effects of ART on lung health and, in particular, the immune system. Growing knowledge in this area will hopefully diminish the incidence of these noninfectious lung diseases and further improve the health of individuals living with HIV.

Characteristics and Outcomes of HIV-Infected Patients With Severe Sepsis: Continued Risk in the Post-Highly Active Antiretroviral Therapy Era.

OBJECTIVES: Although highly active antiretroviral therapy has led to improved survival in HIV-infected individuals, outcomes for HIV-infected patients with sepsis in the post-highly active antiretroviral therapy era are conflicting. Access to highly active antiretroviral therapy and healthcare disparities continue to affect outcomes. We hypothesized that HIV-infected patients with severe sepsis would have worse outcomes compared with their HIV-uninfected counterparts in a large safety-net hospital where access to healthcare is low and delivery of critical care is delayed. DESIGN: Secondary analysis of an ongoing prospective observational study between 2006 and 2010. SETTING: Three adult ICUs (medical ICU, surgical ICU, and neurologic ICU) at Grady Memorial Hospital, Atlanta, GA. PATIENTS: Adult patients with severe sepsis in the ICU. INTERVENTIONS: Baseline patient characteristics and clinical outcomes were collected. HIV-infected and HIV-uninfected patients with sepsis were compared using t tests, chi-square tests, and logistic regression; p values less than 0.05 indicated significance. MEASUREMENTS AND MAIN RESULTS: Of 1,095 patients with severe sepsis enrolled, 165 (15%) were positive for HIV, with a median CD4 count of 41 (8-167). Twenty-two percent of HIV-infected patients were on highly active antiretroviral therapy prior to admission, and 80% had a CD4 count less than 200. HIV-infected patients had a greater hospital mortality (50% vs 38%; p < 0.01). HIV infection (odds ratio = 1.78; p = 0.005) was an independent predictor of mortality by multivariate regression modeling after adjusting for age, history of pneumonia, history of hospital-acquired infection, and history of sepsis. CONCLUSIONS: HIV-infected patients with severe sepsis continue to suffer worse outcomes compared with HIV-uninfected patients in a large urban safety-net hospital caring for patients with limited access to medical care. Further studies need to be done to investigate the effect of socioeconomic status and mitigate healthcare disparities among critically ill HIV-infected patients.

Navigating the institutional review board approval process in a multicenter observational critical care study.

OBJECTIVE: To characterize variation in the institutional review board application process of a multicenter, observational critical care study. DESIGN, SETTING, AND SUBJECTS: Survey analysis of 36 investigators who applied for participation in the United States Critical Illness and Injury Trials Group: Critical Illness and Outcomes Study, an observational study of 69 adult ICUs. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Analysis of investigator-specific characteristics, institutional review board process, application and approval dates, and level of difficulty in obtaining approval. Surveys were analyzed from 36 sites (95%) that applied for institutional review board approval. Level of review ranged from full board, expedited, to exempt. Seventy-five percent of applications were submitted by an experienced investigator while 25% were submitted by a less experienced investigator. Median time to institutional review board approval was 30 days (interquartile range, 14-54) and ranged from 5 days to 5.5 months. Time to approval was 29 days (interquartile range, 17-48) for applications submitted by an experienced investigator compared with 97 days (interquartile range, 25-159) for those submitted by a less experienced investigator (p = 0.08). Subjective level of difficulty was significantly higher for less experienced investigators (4 of 10; interquartile range, 2-8) vs experienced investigators (2 of 10; interquartile range, 1-3) (p = 0.04). Four sites cited institutional review board concern regarding waiver of consent as a major barrier to approval and were required to perform revisions or participate in board meetings regarding this concern. CONCLUSIONS: In a multicenter, observational critical care study, significant variation was observed between sites in all aspects of the institutional review board evaluation and approval process. The level of difficulty was significantly higher for less experienced investigators with a trend toward longer time to institutional review board approval. Variation in institutional review board interpretation of waiver of informed consent regulations was cited as a major barrier to approval.

Researching COVID to Enhance Recovery (RECOVER) adult study protocol: Rationale, objectives, and design.

IMPORTANCE: SARS-CoV-2 infection can result in ongoing, relapsing, or new symptoms or other health effects after the acute phase of infection; termed post-acute sequelae of SARS-CoV-2 infection (PASC), or long COVID. The characteristics, prevalence, trajectory and mechanisms of PASC are ill-defined. The objectives of the Researching COVID to Enhance Recovery (RECOVER) Multi-site Observational Study of PASC in Adults (RECOVER-Adult) are to: (1) characterize PASC prevalence; (2) characterize the symptoms, organ dysfunction, natural history, and distinct phenotypes of PASC; (3) identify demographic, social and clinical risk factors for PASC onset and recovery; and (4) define the biological mechanisms underlying PASC pathogenesis. METHODS: RECOVER-Adult is a combined prospective/retrospective cohort currently planned to enroll 14,880 adults aged ≥18 years. Eligible participants either must meet WHO criteria for suspected, probable, or confirmed infection; or must have evidence of no prior infection. Recruitment occurs at 86 sites in 33 U.S. states, Washington, DC and Puerto Rico, via facility- and community-based outreach. Participants complete quarterly questionnaires about symptoms, social determinants, vaccination status, and interim SARS-CoV-2 infections. In addition, participants contribute biospecimens and undergo physical and laboratory examinations at approximately 0, 90 and 180 days from infection or negative test date, and yearly thereafter. Some participants undergo additional testing based on specific criteria or random sampling. Patient representatives provide input on all study processes. The primary study outcome is onset of PASC, measured by signs and symptoms. A paradigm for identifying PASC cases will be defined and updated using supervised and unsupervised learning approaches with cross-validation. Logistic regression and proportional hazards regression will be conducted to investigate associations between risk factors, onset, and resolution of PASC symptoms. DISCUSSION: RECOVER-Adult is the first national, prospective, longitudinal cohort of PASC among US adults. Results of this study are intended to inform public health, spur clinical trials, and expand treatment options. REGISTRATION: NCT05172024.

Optimal Lung Cancer Screening Criteria Among Persons Living With HIV.

BACKGROUND: The US Preventive Services Task Force (USPSTF) 2021 updated recommendations on lung cancer screening with chest computed tomography to apply to individuals 50-80 years of age (previously 55-80 years), with a ≥20 pack-year history (previously ≥30), whether currently smoking or quit ≤15 years ago. Despite being at higher risk for lung cancer, persons with HIV (PWH) were not well-represented in the National Lung Screening Trial, which informed the USPSTF 2013 recommendations. It is unknown or unclear how PWH are affected by the 2021 recommendations. SETTING: This study was a retrospective analysis of PWH with and without lung cancer in the Women's Interagency HIV Study and the Multicenter AIDS Cohort Study. METHODS: We identified PWH, ages 40-80 years, who currently or previously smoked, with (cases) and without lung cancer (noncases). The sensitivity and specificity of the old, new, and alternative screening criteria were evaluated in each cohort. RESULTS: We identified 52 women and 19 men with lung cancer and 1950 women and 1599 men without lung cancer. Only 11 women (22%) and 6 men (32%) with lung cancer met 2013 screening criteria; however, more women (22; 44%) and men (12; 63%) met 2021 criteria. Decreased age and tobacco exposure thresholds in women further increased sensitivity of the 2021 criteria. CONCLUSIONS: The 2021 USPSTF lung cancer screening recommendations would have resulted in more PWH with lung cancer being eligible for screening at the time of their diagnosis. Further investigation is needed to determine optimal screening criteria for PWH, particularly in women.

Association of Poor Sleep With Depressive and Anxiety Symptoms by HIV Disease Status: Women's Interagency HIV Study.

BACKGROUND: Sleep disturbances are prevalent in women living with HIV (WLWH) and can affect mental health and overall quality of life. We examined the prevalence and predictors of poor sleep quality in a US cohort of WLWH and HIV-uninfected controls and the relationship between sleep quality and mental health symptom burden stratified by HIV disease status (viremic WLWH, aviremic WLWH, and HIV-uninfected women). METHODS: Sleep quality was assessed using the Pittsburgh Sleep Quality Index in 1583 (400 viremic WLWH, 723 aviremic WLWH, and 460 HIV-uninfected women) Women's Interagency HIV Study participants. Depressive and anxiety symptoms were concurrently assessed using the Center for Epidemiological Studies-Depression (CES-D) scale and General Anxiety Disorder (GAD-7) scale. Associations between poor sleep quality (global Pittsburgh Sleep Quality Index >5) and both high depressive (CES-D ≥16) and anxiety (GAD-7 ≥10) symptoms were each assessed by HIV disease status using multivariable logistic regression models. RESULTS: Prevalence of poor sleep quality in the overall sample was 52%, differed by HIV disease status (P = 0.045), and was significantly associated with high depressive and anxiety symptoms in (1) viremic WLWH, (2) aviremic WLWH, and (3) HIV-uninfected women [CES-D: (1) adjusted odds ratio (aOR) = 7.50, 95% confidence interval (CI): 4.10 to 13.7; (2) aOR = 4.54, 95% CI: 3.07 to 6.73; and (3) aOR = 6.03, 95% CI: 3.50 to 10.4; GAD-7: (1) aOR = 5.20; 95% CI: 2.60 to 10.4, (2) aOR = 6.03; 95% CI: 3.67 to 9.91, and (3) aOR = 6.24; 95% CI: 3.11 to 12.6]. CONCLUSIONS: Poor sleep quality is highly prevalent, as is mental health symptom burden, among WLWH and HIV-uninfected controls. Future longitudinal studies are necessary to clarify the directionality of the relationship.

Pulmonary Function Trajectories in People with HIV: Analysis of the Pittsburgh HIV Lung Cohort.

Rationale: Human immunodeficiency virus (HIV) infection is associated with chronic lung disease and impaired pulmonary function; however, longitudinal pulmonary function phenotypes in HIV are undefined. Objectives: To identify pulmonary function trajectories, their determinants, and outcomes. Methods: We used data from participants with HIV in the Pittsburgh HIV Lung Cohort with three or more pulmonary function tests between 2007 and 2020. We analyzed post-bronchodilator forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and FEV1/FVC, and diffusing capacity of the lung for carbon monoxide (DlCO) using group-based trajectory modeling to identify subgroups of individuals whose measurements followed a similar pattern over time. We examined the association between participant characteristics and trajectories using multivariable logistic regression. In exploratory adjusted analyses restricted to individuals with available plasma cytokine data, we investigated the association between 18 individual standardized cytokine concentrations and trajectories. We compared mortality, dyspnea prevalence, respiratory health status, and 6-minute-walk distance between phenotypes. Results: A total of 265 participants contributed 1,606 pulmonary function measurements over a median follow-up of 8.1 years. We identified two trajectories each for FEV1 and FVC: "low baseline, slow decline" and "high baseline, rapid decline." There were three trajectory groups for FEV1/FVC: "rapid decline," "moderate decline," and "slow decline." Finally, we identified two trajectories for DlCO: "baseline low" and "baseline high." The low baseline, slow decline FEV1 and FVC, rapid decline, and moderate decline FEV1/FVC, and baseline low DlCO phenotypes were associated with increased dyspnea prevalence, worse respiratory health status, and decreased 6-minute-walk distance. The baseline low DlCO phenotype was also associated with worse mortality. Current smoking and pack-years of smoking were associated with the adverse FEV1, FEV1/FVC, and DlCO phenotypes. Detectable viremia was the only HIV marker associated with the adverse DlCO phenotype. C-reactive protein and endothelin-1 were associated with the adverse FEV1 and FVC phenotypes, and endothelin-1 trended toward an association with the adverse DlCO phenotype. Conclusions: We identified novel, distinct longitudinal pulmonary function phenotypes with significant differences in characteristics and outcomes. These findings highlight the importance of lung dysfunction over time in people with HIV and should be validated in additional cohorts.

Association Between HIV and Prevalence and Manifestations of Asthma: Analysis of the Multicenter AIDS Cohort Study and Women's Interagency HIV Study.

BACKGROUND: The association between HIV and asthma prevalence and manifestations remains unclear, with few studies including women. SETTING: A retrospective observational cohort study from the Multicenter AIDS Cohort Study and Women's Interagency HIV Study. METHODS: Asthma was defined in 2 ways: (1) self-report and (2) robust criteria requiring all the following: lack of fixed airflow obstruction, presence of wheeze on the St. George's Respiratory Questionnaire (SGRQ), and report of asthma therapies. Estimates of asthma prevalence and asthma-related manifestations were compared by HIV serostatus. RESULTS: A total of 1815 men and 2122 women were included. Asthma prevalence did not differ between people with HIV (PWH) and people without HIV regardless of definition: self-report (men, 12.0% vs. 11.2%; women, 24.3% vs. 27.5%) and robust criteria (men, 5.0% vs. 3.4%; women, 12.8% vs. 13.2%). Among men with asthma, worse respiratory symptom burden was reported among those with HIV, regardless of asthma definition. Among women with self-reported asthma, those with HIV had less respiratory symptom burden. Regardless of serostatus, women with robust-defined asthma had similar respiratory symptoms across SGRQ domains and similar frequencies of phlegm, shortness of breath, and wheezing. CONCLUSIONS: Among PWH and people without HIV, asthma prevalence was 2-fold to 3-fold higher using self-reported definition rather than robust definition. In men and women, HIV was not associated with increased asthma prevalence. In men, HIV was associated with more respiratory symptoms when asthma was self-reported; the relationship was attenuated with the robust criteria. Further studies are needed to explore asthma phenotypes among PWH.

An International Virtual COVID-19 Critical Care Training Forum for Healthcare Workers.

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic resulted in redeployment of non-critical care-trained providers to intensive care units across the world. Concurrently, traditional venues for delivery of medical education faced major disruptions. The need for a virtual forum to fill knowledge gaps for healthcare workers caring for patients with coronavirus disease (COVID-19) was apparent in the early stages of the pandemic. Objective: The weekly, open-access COVID-19 Critical Care Training Forum (CCCTF) organized by the American Thoracic Society (ATS) provided a global audience access to timely content relevant to their learning needs. The goals of the forum were threefold: to aid healthcare providers in assessment and treatment of patients with COVID-19, to reduce provider anxiety, and to disseminate best practices. Methods: The first 13 ATS CCCTF sessions streamed live from April to July 2020. Structured debriefs followed each session and participant feedback was evaluated in planning of subsequent sessions. A second set of 14 sessions streamed from August to November 2020. Content experts were recruited from academic institutions across the United States. Results: As of July 2020, the ATS CCCTF had 2,494 live participants and 7,687 downloads for a total of 10,181 views. The majority of participants had both completed training (58.6%) and trained in critical care (53.8%). Physicians made up a majority (82.2%) of the audience that spanned the globe (61% were international attendees). Conclusion: We describe the rapid and successful implementation of an open-access medical education forum to address training and knowledge gaps among healthcare personnel caring for patients with COVID-19.

Stem cells in sepsis and acute lung injury.

OBJECTIVE: Sepsis and acute lung injury continue to be major causes of morbidity and mortality worldwide despite advances in our understanding of pathophysiology and the discovery of new management strategies. Recent investigations show that stem cells may be beneficial as prognostic biomarkers and novel therapeutic strategies in these syndromes. This article reviews the potential use of endogenous adult tissue-derived stem cells in sepsis and acute lung injury as prognostic markers and also as exogenous cell-based therapy. DATA SOURCES: A directed systematic search of the medical literature using PubMed and OVID, with particular emphasis on the time period after 2002, was done to evaluate topics related to 1) the epidemiology and pathophysiology of sepsis and acute lung injury; and 2) the definition, characterization, and potential use of stem cells in these diseases. DATA SYNTHESIS AND FINDINGS: When available, preferential consideration was given to prospective nonrandomized clinical and preclinical studies. CONCLUSIONS: Stem cells have shown significant promise in the field of critical care both for 1) prognostic value and 2) treatment strategies. Although several recent studies have identified the potential benefit of stem cells in sepsis and acute lung injury, further investigations are needed to more completely understand stem cells and their potential prognostic and therapeutic value.

HIV X4 Variants Increase Arachidonate 5-Lipoxygenase in the Pulmonary Microenvironment and are associated with Pulmonary Arterial Hypertension.

Pulmonary Arterial Hypertension (PAH) is overrepresented in People Living with Human Immunodeficiency Virus (PLWH). HIV protein gp120 plays a key role in the pathogenesis of HIV-PAH. Genetic changes in HIV gp120 determine viral interactions with chemokine receptors; specifically, HIV-X4 viruses interact with CXCR4 while HIV-R5 interact with CCR5 co-receptors. Herein, we leveraged banked samples from patients enrolled in the NIH Lung HIV studies and used bioinformatic analyses to investigate whether signature sequences in HIV-gp120 that predict tropism also predict PAH. Further biological assays were conducted in pulmonary endothelial cells in vitro and in HIV-transgenic rats. We found that significantly more persons living with HIV-PAH harbor HIV-X4 variants. Multiple HIV models showed that recombinant gp120-X4 as well as infectious HIV-X4 remarkably increase arachidonate 5-lipoxygenase (ALOX5) expression. ALOX5 is essential for the production of leukotrienes; we confirmed that leukotriene levels are increased in bronchoalveolar lavage fluid of HIV-infected patients. This is the first report associating HIV-gp120 genotype to a pulmonary disease phenotype, as we uncovered X4 viruses as potential agents in the pathophysiology of HIV-PAH. Altogether, our results allude to the supplementation of antiretroviral therapy with ALOX5 antagonists to rescue patients with HIV-X4 variants from fatal PAH.

Monitoring of endothelial dysfunction in critically ill patients: the role of endothelial progenitor cells.

PURPOSE OF REVIEW: This review provides an overview of sepsis as a prototypical critical illness and discusses the role of the endothelium in the pathophysiology of sepsis and sepsis-related organ dysfunction, the characterization and functions of endothelial progenitor cells, and investigates these cells both as a prognostic and therapeutic strategy in critically ill patients. RECENT FINDINGS: Sepsis continues to be a major cause of morbidity and mortality worldwide. Preclinical and clinical sepsis studies have shown that the acute systemic inflammatory and procoagulant response results in structural and functional alterations in the endothelium, which may lead to organ failure and ultimately, death. In the last decade, the concept of postnatal vasculogenesis has been revolutionized to include angiogenesis by mature endothelial cells and vasculogenesis by endothelial progenitor cells. These cells are recruited from the bone marrow to areas of endothelial injury, at which point they differentiate and promote revascularization of the endothelium, which has been shown to have significant prognostic and therapeutic implications in a variety of ischemic vascular disorders. SUMMARY: Circulating endothelial progenitor cells may be an important mechanism of vascular repair, and thus shows significant promise for prognostic and therapeutic strategies in critical illness, namely sepsis and sepsis-related organ dysfunction.

Microbiome in the pathogenesis of cystic fibrosis and lung transplant-related disease.

Significant advances in culture-independent methods have expanded our knowledge about the diversity of the lung microbial environment. Complex microorganisms and microbial communities can now be identified in the distal airways in a variety of respiratory diseases, including cystic fibrosis (CF) and the posttransplantation lung. Although there are significant methodologic concerns about sampling the lung microbiome, several studies have now shown that the microbiome of the lower respiratory tract is distinct from the upper airway. CF is a disease characterized by chronic airway infections that lead to significant morbidity and mortality. Traditional culture-dependent methods have identified a select group of pathogens that cause exacerbations in CF, but studies using bacterial 16S rRNA gene-based microarrays have shown that the CF microbiome is an intricate and dynamic bacterial ecosystem, which influences both host immune health and disease pathogenesis. These microbial communities can shift with external influences, including antibiotic exposure. In addition, there have been a number of studies suggesting a link between the gut microbiome and respiratory health in CF. Compared with CF, there is significantly less knowledge about the microbiome of the transplanted lung. Risk factors for bronchiolitis obliterans syndrome, one of the leading causes of death, include microbial infections. Lung transplant patients have a unique lung microbiome that is different than the pretransplanted microbiome and changes with time. Understanding the host-pathogen interactions in these diseases may suggest targeted therapies and improve long-term survival in these patients.

Dysregulation of Alveolar Macrophage PPARγ, NADPH Oxidases, and TGFß1 in Otherwise Healthy HIV-Infected Individuals.

Despite antiretroviral therapy (ART), respiratory infections increase mortality in individuals living with chronic human immunodeficiency virus (HIV) infection. In experimental and clinical studies of chronic HIV infection, alveolar macrophages (AMs) exhibit impaired phagocytosis and bacterial clearance. Peroxisome proliferator-activated receptor (PPAR)γ, NADPH oxidase (Nox) isoforms Nox1, Nox2, Nox4, and transforming growth factor-beta 1 (TGFß1) are critical mediators of AM oxidative stress and phagocytic dysfunction. Therefore, we hypothesized that HIV alters AM expression of these targets, resulting in chronic lung oxidative stress and subsequent immune dysfunction. A cross-sectional study of HIV-infected (n = 22) and HIV-uninfected (n = 6) subjects was conducted. Bronchoalveolar lavage (BAL) was performed, and AMs were isolated. Lung H2O2 generation was determined by measuring H2O2 in the BAL fluid. In AMs, PPARγ, Nox1, Nox2, Nox4, and TGFß1 mRNA (quantitative real-time polymerase chain reaction) and protein (fluorescent immunomicroscopy) levels were assessed. Compared with HIV-uninfected (control) subjects, HIV-infected subjects were relatively older and the majority were African American; ∼86% were on ART, and their median CD4 count was 445, with a median viral load of 0 log copies/ml. HIV infection was associated with increased H2O2 in the BAL, decreased AM mRNA and protein levels of PPARγ, and increased AM mRNA and protein levels of Nox1, Nox2, Nox4, and TGFß1. PPARγ attenuation and increases in Nox1, Nox2, Nox4, and TGFß1 contribute to AM oxidative stress and immune dysfunction in the AMs of otherwise healthy HIV-infected subjects. These findings provide novel insights into the molecular mechanisms by which HIV increases susceptibility to pulmonary infections.