Chronic alcohol use primes bronchial cells for altered inflammatory response and barrier dysfunction during SARS-CoV-2 infection.

Alcohol use disorder (AUD) is a significant public health concern and people with AUD are more likely to develop severe acute respiratory distress syndrome (ARDS) in response to respiratory infections. To examine whether AUD was a risk factor for more severe outcome in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, we examined early responses to infection using cultured differentiated bronchial epithelial cells derived from brushings obtained from people with AUD or without AUD. RNA-seq analysis of uninfected cells determined that AUD cells were enriched for expression of epidermal genes as compared with non-AUD cells. Bronchial epithelial cells from patients with AUD showed a significant decrease in barrier function 72 h postinfection, as determined by transepithelial electrical resistance. In contrast, barrier function of non-AUD cells was enhanced 72 h after SARS-CoV-2 infection. AUD cells showed claudin-7 that did not colocalize with zonula occludens-1 (ZO-1), indicative of disorganized tight junctions. However, both AUD and non-AUD cells showed decreased ß-catenin expression following SARS-CoV-2 infection. To determine the impact of AUD on the inflammatory response to SARS-CoV-2 infection, cytokine secretion was measured by multiplex analysis. SARS-CoV-2-infected AUD bronchial cells had enhanced secretion of multiple proinflammatory cytokines including TNFα, IL-1ß, and IFNγ as opposed to non-AUD cells. In contrast, secretion of the barrier-protective cytokines epidermal growth factor (EGF) and granulocyte macrophage-colony stimulating factor (GM-CSF) was enhanced for non-AUD bronchial cells. Taken together, these data support the hypothesis that AUD is a risk factor for COVID-19, where alcohol primes airway epithelial cells for increased inflammation and increased barrier dysfunction and increased inflammation in response to infection by SARS-CoV-2.NEW & NOTEWORTHY Alcohol use disorder (AUD) is a significant risk factor for severe acute respiratory distress syndrome. We found that AUD causes a phenotypic shift in gene expression in human bronchial epithelial cells, enhancing expression of epidermal genes. AUD cells infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had higher levels of proinflammatory cytokine secretion and barrier dysfunction not present in infected non-AUD cells, consistent with increased early COVID-19 severity due to AUD.

Alcohol impairs recognition and uptake of Mycobacterium tuberculosis by suppressing toll-like receptor 2 expression.

BACKGROUND: Alcohol impairs pulmonary innate immune function and is associated with an increased risk of tuberculosis (TB). Toll-like receptor 2 (TLR2) is a pattern recognition receptor on alveolar macrophages that recognizes Mycobacterium tuberculosis (Mtb). The expression of TLR2 depends, in part, on granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling. Given our prior work demonstrating the suppression of GM-CSF signaling following chronic alcohol ingestion, we hypothesized that alcohol impairs TLR2 expression via the suppression of GM-CSF and thereby reduces the ability of the macrophage to recognize and phagocytose Mtb. METHODS: Primary alveolar macrophages were isolated from control-fed and alcohol-fed rats. Prior to cell isolation, some alcohol-fed rats were treated with intranasal GM-CSF and then endotracheally inoculated with an attenuated strain of Mtb. Primary macrophages were then isolated and immunofluorescence was used to determine phagocytic efficiency and TLR2 expression in the presence and absence of GM-CSF treatment and phagocytic efficiency in the presence and absence of TLR2 neutralization. RESULTS: TLR2 expression and phagocytosis of Mtb were significantly lower in the alveolar macrophages of alcohol-fed rats than control-fed rats. In parallel, blocking TLR2 signaling recapitulated this decreased phagocytosis of Mtb. In contrast, intranasal GM-CSF treatment restored TLR2 expression and Mtb phagocytosis in the alveolar macrophages of alcohol-fed rats to levels comparable to those of control-fed rats. CONCLUSIONS: Chronic alcohol ingestion reduces TLR2 protein expression and phagocytosis of Mtb, likely due to impaired GM-CSF signaling. GM-CSF restores membrane-bound TLR2 expression and phagocytic function.

HIV and the tuberculosis "set point": how HIV impairs alveolar macrophage responses to tuberculosis and sets the stage for progressive disease.

As HIV has fueled a global resurgence of tuberculosis over the last several decades, there is a growing awareness that HIV-mediated impairments in both innate and adaptive immunity contribute to the heightened risk of tuberculosis in people with HIV. Since early immune responses to Mycobacterium tuberculosis (Mtb) set the stage for subsequent control or progression to active tuberculosis disease, early host-pathogen interactions following Mtb infection can be thought of as establishing a mycobacterial "set point," which we define as the mycobacterial burden at the point of adaptive immune activation. This early immune response is impaired in the context of HIV coinfection, allowing for a higher mycobacterial set point and greater likelihood of progression to active disease with greater bacterial burden. Alveolar macrophages, as the first cells to encounter Mtb in the lungs, play a critical role in containing Mtb growth and establishing the mycobacterial set point. However, a number of key macrophage functions, ranging from pathogen recognition and uptake to phagocytosis and microbial killing, are blunted in HIV coinfection. To date, research evaluating the effects of HIV on the alveolar macrophage response to Mtb has been relatively limited, particularly with regard to the critical early events that help to dictate the mycobacterial set point. A greater understanding of alveolar macrophage functions impacted by HIV coinfection will improve our understanding of protective immunity to Mtb and may reveal novel pathways amenable to intervention to improve both early immune control of Mtb and clinical outcomes for the millions of people worldwide infected with HIV.

MiR-144 mediates Nrf2 inhibition and alveolar epithelial dysfunction in HIV-1 transgenic rats.

Chronic HIV infection causes redox stress and increases the risk of acute and chronic lung injury, even when individuals are adherent to antiretroviral therapy. HIV-1 transgene expression in rats inhibits nuclear factor (erythroid-derived 2)-like 2 (Nrf2), which regulates antioxidant defenses and alveolar epithelial cell (AEC) barrier function, but the mechanism is unknown. In this study, we present novel evidence that these pathological effects of HIV are mediated by microRNA-144 (miR-144). HIV-1 transgene expression in vivo increases the expression of miR-144 in the alveolar epithelium, and this can be replicated by direct exposure of naïve primary AECs to either Tat or gp120 ex vivo. Further, treating naïve primary AECs with a miR-144 mimic decreased the expression and activity of Nrf2 and inhibited their barrier formation. In contrast, treatment with a miR-144 antagomir increased the expression and activity of Nrf2 and improved barrier function in primary AECs isolated from HIV-1 transgenic rats. Importantly, either delivering the miR-144 antagomir intratracheally, or directly activating Nrf2 by dietary treatment with PB123, increased Nrf2 expression and barrier formation in HIV-1 transgenic rat AECs. This study provides new experimental evidence that HIV-induced inhibition of Nrf2 and consequent AEC barrier dysfunction are mediated via miR-144, and that these pathophysiological effects can be mitigated in vivo by either directly antagonizing miR-144 or activating Nrf2. Our findings suggest that targeting the inhibition of Nrf2 in individuals living with HIV could enhance their lung health and decrease the lung-specific morbidity and mortality that persists despite antiretroviral therapy.

Alcohol-Induced Interleukin-17 Expression Causes Murine Lung Fibroblast-to-Myofibroblast Transdifferentiation via Thy-1 Down-Regulation.

BACKGROUND: Alcohol exposure induces TGFß1 and renders the lung susceptible to injury and disrepair. We determined that TGFß1 regulates myofibroblast differentiation through the loss of Thy-1 expression and consequent induction of α-SMA. TGFß1 is important for T helper 17 (Th17) differentiation and IL-17 secretion, which in turn participates in tissue repair. We hypothesized that alcohol induces Th17 differentiation via TGFß1 and that IL-17 produced by these cells contributes to the development of profibrotic lung myofibroblasts. METHODS: Primary lung fibroblasts (PLFs) were treated with alcohol, TGFß1, and IL-17 and then analyzed for Thy-1 expression and cell morphology. Naïve and Th17-polarized CD4+ T cells were exposed to alcohol and assessed for IL-17 expression. CD4+ T cells from alcohol-fed mice were analyzed for Th17 and IL-17 expression. Lungs of control-fed, bleomycin-treated and alcohol-fed, bleomycin-treated mice were analyzed for IL-17 protein expression. RESULTS: Alcohol-treated PLFs expressed lower levels of Thy-1 than untreated cells. TGFß1 or IL-17 exposure suppressed PLF Thy-1 expression. When administered together, TGFß1 and IL-17 additively down-regulated Thy-1 expression. Exposure of naïve and Th17-polarized CD4+ T cells to alcohol induced the Th17 phenotype and augmented their production of IL-17. CD4+ Th17+ levels are elevated in the peripheral compartment but not in the lungs of alcohol-fed animals. Treatment of the PLFs with IL-17 and alcohol induced α-SMA expression. Induction of α-SMA and myofibroblast morphology by IL-17 occurred selectively in a Thy-1- fibroblast subpopulation. Chronic alcohol ingestion augmented lung-specific IL-17 expression following bleomycin-induced lung injury. CONCLUSIONS: Alcohol exposure skews T cells toward a Th17 immune response that in turn primes the lung for fibroproliferative disrepair through loss of Thy-1 expression and induction of myofibroblast differentiation. These effects suggest that IL-17 and TGFß1 contribute to fibroproliferative disrepair in the lung and targeting these proteins could limit morbidity and mortality following lung injury in alcoholic individuals.

Pulmonary Innate Immune Dysfunction in Human Immunodeficiency Virus.

The advent of antiretroviral therapy has transformed infection by the type 1 human immunodeficiency virus (HIV) from a rapidly fatal disease to a chronic illness with excellent long-term survival rates. Although HIV primarily targets the adaptive arm of host immunity, it simultaneously impacts the innate immune system, and has profound implications for lung health, even when viral suppression is achieved with antiretroviral therapy. The lung has evolved a unique array of innate immune defenses, and the pathophysiological interactions between HIV and the pulmonary innate immune system deserve particular attention. In this review, we discuss work that elucidates how the components of innate immunity both respond to and are perturbed by infection with HIV.

TGF-ß1 epigenetically modifies Thy-1 expression in primary lung fibroblasts.

Idiopathic pulmonary fibrosis is a progressive lung disease that increases in incidence with age. We identified a profibrotic lung phenotype in aging mice characterized by an increase in the number of fibroblasts lacking the expression of thymocyte differentiation antigen 1 (Thy-1) and an increase in transforming growth factor (TGF)-ß1 expression. It has been shown that Thy-1 expression can be epigenetically modified. Lung fibroblasts (PLFs) were treated with TGF-ß1 ± DNA methyltransferase (DNMT) inhibitor 5-aza-2'-deoxycytidine (5-AZA) and analyzed for Thy-1 gene and protein expression, DNMT protein expression, and activity. α-Smooth muscle actin (α-SMA) and collagen type 1 (Col1A1) gene and protein expression was assessed. PLFs were transfected with DNMT1 silencing RNA ± TGF-ß1. TGF-ß1 inhibited Thy-1 gene and protein expression in PLFs, and cotreatment with 5-AZA ameliorated this effect and appeared to inhibit DNMT1 activation. TGF-ß1 induced Thy-1 promoter methylation as assessed by quantitative methyl PCR. Treatment with 5-AZA attenuated TGF-ß1-induced Col1A1 gene and protein expression and α-SMA gene expression (but not α-SMA protein expression). Inhibiting DNMT1 with silencing RNA attenuated TGF-ß1-induced DNMT activity and its downstream suppression of Thy-1 mRNA and protein expression as well as inhibited α-SMA mRNA and Col1A1 mRNA and protein expression, and showed a decreased trend in Thy-1 promoter methylation. Immunofluorescence for α-SMA suggested that 5-AZA inhibited stress fiber formation. These findings suggest that TGF-ß1 epigenetically regulates lung fibroblast phenotype through methylation of the Thy-1 promoter. Targeted inhibition of DNMT in the right clinical context might prevent fibroblast to myofibroblast transdifferentiation and collagen deposition, which in turn could prevent fibrogenesis in the lung and other organs.

Nrf2 regulates PU.1 expression and activity in the alveolar macrophage.

Alveolar macrophage (AM) immune function depends on the activation of the transcription factor PU.1 by granulocyte macrophage colony-stimulating factor. We have determined that chronic alcohol ingestion dampens PU.1 signaling via an unknown zinc-dependent mechanism; specifically, although PU.1 is not known to be a zinc-dependent transcription factor, zinc treatment reversed alcohol-mediated dampening of PU.1 signaling. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2), a zinc-dependent basic leucine zipper protein essential for antioxidant defenses, is also impaired by chronic alcohol ingestion and enhanced by zinc treatment. We hypothesized that the response of PU.1 to zinc treatment may result from the action of Nrf2 on PU.1. We first performed Nrf2/PU.1 protein coimmunoprecipitation on a rat AM cell line (NR8383) and found no evidence of protein-protein interactions. We then found evidence of increased Nrf2 binding to the PU.1 promoter region by chromatin immunoprecipitation. We next activated Nrf2 using either sulforaphane or an overexpression vector and inhibited Nrf2 with silencing RNA to determine whether Nrf2 could actively regulate PU.1. Nrf2 activation increased protein expression of both factors as well as gene expression of their respective downstream effectors, NAD(P)H dehydrogenase[quinone] 1 (NQO1) and cluster of differentiation antigen-14 (CD14). In contrast, Nrf2 silencing decreased the expression of both proteins, as well as gene expression of their effectors. Activating and inhibiting Nrf2 in primary rat AMs resulted in similar effects. Taken together, these findings suggest that Nrf2 regulates the expression and activity of PU.1 and that antioxidant response and immune activation are coordinately regulated within the AM.

Comparison of Web-Based and On-Site Lung Simulators for Education in Mechanical Ventilation.

BACKGROUND: Training in mechanical ventilation is a key goal in critical care fellowship education. Web-based simulators offer a cost-effective and readily available alternative to traditional on-site simulators. However, it is unclear how effective they are as teaching tools. In this study, we evaluated the test scores of fellows who underwent mechanical ventilation training by using a web-based simulator compared with fellows who used an on-site simulator during a mechanical ventilation course. METHODS: This was a nonrandomized controlled trial conducted as part of a mechanical ventilation course that involved 70 first-year critical care fellows. The course was identical except for the simulation technology used. One group of instructors used a traditional on-site simulator, the ASL 5000 Lung Solution (n = 39). The second group was instructed in using a web-based simulator, VentSim (n = 31). Each fellow completed a pre-course test and a post-course test by using a validated, case-based ventilator waveform examination that consisted of 5 questions with a total possible score of 100. The primary outcome was a comparison of the mean scores on the posttest between the 2 groups. The study was designed as a non-inferiority trial with a predetermined margin of 10 points. RESULTS: There was no significant difference in the mean ± SD pretest scores between the web-based and the on-site groups (21.1 ± 12.6 and 26.9 ± 13.6 respectively; P = .11). The mean ± SD posttest scores were 45.6 ± 25.0 for the web-based simulator and 43.4 ± 16.5 for on-site simulator (mean difference 2.2; one-sided 95% CI -7.0 to ∞; P non-inferiority = .02 [non-inferiority confirmed]). Changes in mean ± SD scores (posttest - pretest) were 25.9 ± 20.9 for the web-based simulator and 16.5 ± 15.9 for the on-site simulator (mean difference 9.4, one-sided 95% CI 0.9 to ∞; P non-inferiority < .001 [non-inferiority confirmed]). CONCLUSIONS: In the education of first-year critical care fellows on mechanical ventilation waveform analysis, a web-based mechanical ventilation simulator was non-inferior to a traditional on-site mechanical ventilation simulator.

Brief Report: Alternative Pulmonary Function Measures of Emphysema in People With HIV.

INTRODUCTION: People with HIV (PWH) have nearly twice the risk of emphysema than people without HIV. This risk, which has been associated with HIV-mediated changes in the lung immune environment and more extensive radiographic emphysema, may result in different patterns of airflow limitation on pulmonary function testing (PFT) than those traditionally used in people without HIV. METHODS: In this prospective cohort of PWH in Atlanta, Georgia, we analyzed PFT and chest computed tomography data from July 2013 through June 2018. After comparing the prevalence of PFT measures of airflow limitation for those with and without radiographic emphysema, we used binary recursive partitioning to identify PFT measures that differentiated between PWH with and without radiographic emphysema. RESULTS: Among 167 PWH who had both PFT and computed tomography data during the study period, 89 (53%) had radiographic emphysema. Those with radiographic emphysema were more likely to have airflow limitations on PFTs. Recursive partitioning identified partitions at a forced expiratory volume in 1 second to forced vital capacity ratio (FEV1/FVC) of 0.78 and a residual volume of 116% predicted. These partitions enabled the identification of 84 (94%) PWH with radiographic emphysema, in contrast to the traditional diagnostic criteria of an FEV1/FVC ratio of 0.7, which only identified 49 (55%) of those with radiographic emphysema. CONCLUSIONS: Emphysema in PWH may have different patterns of airflow limitation on PFTs that are not adequately captured by traditional diagnostic criteria. Future studies can seek to validate these findings and determine optimal thresholds for diagnosing HIV-associated emphysema.

Postinfectious Pulmonary Complications: Establishing Research Priorities to Advance the Field: An Official American Thoracic Society Workshop Report.

Continued improvements in the treatment of pulmonary infections have paradoxically resulted in a growing challenge of individuals with postinfectious pulmonary complications (PIPCs). PIPCs have been long recognized after tuberculosis, but recent experiences such as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic have underscored the importance of PIPCs following other lower respiratory tract infections. Independent of the causative pathogen, most available studies of pulmonary infections focus on short-term outcomes rather than long-term morbidity among survivors. In this document, we establish a conceptual scope for PIPCs with discussion of globally significant pulmonary pathogens and an examination of how these pathogens can damage different components of the lung, resulting in a spectrum of PIPCs. We also review potential mechanisms for the transition from acute infection to PIPC, including the interplay between pathogen-mediated injury and aberrant host responses, which together result in PIPCs. Finally, we identify cross-cutting research priorities for the field to facilitate future studies to establish the incidence of PIPCs, define common mechanisms, identify therapeutic strategies, and ultimately reduce the burden of morbidity in survivors of pulmonary infections.

Activating the Nrf2-mediated antioxidant response element restores barrier function in the alveolar epithelium of HIV-1 transgenic rats.

The master transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) regulates the expression of antioxidant and phase II-metabolizing enzymes by activating the antioxidant response element (ARE) and thereby protects cells and tissues from oxidative stress. Pulmonary complications remain the leading cause of death in human immunodeficiency virus (HIV)-1-infected individuals, who display systemic oxidative stress and glutathione deficiency that can be modeled in transgenic rats where HIV-1-related viral proteins decrease glutathione levels and cause epithelial barrier dysfunction within the alveolar space by as yet unknown mechanisms. We hypothesized that HIV-1-related proteins inhibit Nrf2-mediated antioxidant defenses and thereby disrupt the normally tight alveolar epithelial barrier. Nrf2 RNA silencing dampened Nrf2/ARE activity, decreased the expression of the tight junction proteins zonula occludens-1, occludin, and claudin-18, increased paracellular permeability of alveolar epithelial monolayers derived from wild-type rats, and therefore reproduced the effects of HIV-1 transgene expression on the epithelial barrier that we had previously described. In contrast, upregulating Nrf2 activity, either by plasmid-mediated overexpression or treatment with the Nrf2 activator sulforaphane, increased the expression of ARE-dependent antioxidants, including NAD(P)H dehydrogenase, quinone 1 and glutathione, improved the expression of tight junction proteins, and restored the ability to form tight barriers in alveolar epithelial cells from HIV-1 transgenic rats. Taken together, these new findings argue that HIV-1-related proteins downregulate Nrf2 expression and/or activity within the alveolar epithelium, which in turn impairs antioxidant defenses and barrier function, thereby rendering the lung susceptible to oxidative stress and injury. Furthermore, this study suggests that activating the Nrf2/ARE pathway with the dietary supplement sulforaphane could augment antioxidant defenses and lung health in HIV-1-infected individuals.

Paired ATAC- and RNA-seq offer insight into the impact of HIV on alveolar macrophages: a pilot study.

People with HIV remain at greater risk for both infectious and non-infectious pulmonary diseases even after antiretroviral therapy initiation and CD4 cell count recovery. These clinical risks reflect persistent HIV-mediated defects in innate and adaptive immunity, including in the alveolar macrophage, a key innate immune effector in the lungs. In this proof-of-concept pilot study, we leveraged paired RNA-seq and ATAC-seq analyses of human alveolar macrophages obtained with research bronchoscopy from people with and without HIV to highlight the potential for recent methodologic advances to generate novel hypotheses about biological pathways that may contribute to impaired pulmonary immune function in people with HIV. In addition to 35 genes that were differentially expressed in macrophages from people with HIV, gene set enrichment analysis identified six gene sets that were differentially regulated. ATAC-seq analysis revealed 115 genes that were differentially accessible for people with HIV. Data-driven integration of the findings from these complementary, high-throughput techniques using xMWAS identified distinct clusters involving lipoprotein lipase and inflammatory pathways. By bringing together transcriptional and epigenetic data, this analytic approach points to several mechanisms, including previously unreported pathways, that warrant further exploration as potential mediators of the increased risk of pulmonary disease in people with HIV.

Mycobacterium tuberculosis-specific cytokine responses according to HIV status among household contacts of people with TB.

Following exposure to Mycobacterium tuberculosis (Mtb), a coordinated host response comprising both pro- and anti-inflammatory cytokines is critical for pathogen control. Although tuberculosis (TB) remains the leading cause of death among people with human immunodeficiency virus (HIV), the impact of HIV infection on Mtb-specific immune responses remains unclear. In this cross-sectional study of TB-exposed household contacts with and without HIV, we collected remaining supernatant from interferon-gamma release assay (IGRA) testing (QuantiFERON-TB Gold Plus [QFT-Plus]) and measured Mtb-specific pro-inflammatory, anti-inflammatory, and regulatory cytokine responses with a multiplex assay of 11 analytes. While people with HIV had lower responses to mitogen stimulation for some cytokines (granulocyte-macrophage colony-stimulating factor [GM-CSF], interleukin [IL]-2, IL-10, IL-17A, IL-22), there was no difference in cytokine levels for people with and without HIV following stimulation with Mtb-specific antigens. Future studies are necessary to explore whether changes in Mtb-specific cytokine responses over time are associated with distinct clinical outcomes following exposure to TB.

HIV Increases the Risk of Cigarette Smoke-Induced Emphysema Through MMP-9.

BACKGROUND: HIV is associated with an increased risk for emphysema. Matrix metalloproteinase 9 (MMP-9) is a lung tissue remodeling enzyme associated with emphysema. We previously found MMP-9 activity increases with increases in oxidative stress and that HIV increases alveolar oxidative stress. We hypothesized that HIV proteins would increase the risk of cigarette smoke-induced emphysema due to MMP-9. METHODS: HIV-1 transgenic rats and wild-type littermates were exposed to cigarette smoke or sham for 8 weeks. Lung compliance and histology were assessed. Bronchoalveolar lavage (BAL), primary alveolar macrophages (AM), and serum samples were obtained. A rat alveolar macrophage cell line was exposed to the HIV protein Tat, and MMP-9 levels were assessed by Western immunoblotting. MMP-9 protein expression and activity were assessed in AM from the HIV rat model by ELISA and cytoimmunofluoresence, respectively. Serum from human subjects with and without HIV and tobacco dependence was assessed for MMP-9 levels. RESULTS: MMP-9 expression was significantly increased in rat alveolar macrophages after Tat exposure. HIV-1 transgenic rats developed emphysema while wild-type littermates did not. MMP-9 expression was also increased in the serum, BAL, and AM of HIV-1 transgenic rats after exposure to cigarette smoke compared with wild-type rats. In parallel, serum samples from HIV+ smokers had higher levels of MMP-9 than subjects without HIV and those who did not smoke. CONCLUSION: The combination of HIV and cigarette smoke increases MMP-9 expression in experimental rat HIV models and human subjects. HIV and cigarette smoke both induce alveolar oxidative stress and thereby increase MMP-9 activity.

MYOSIN LIGHT CHAIN KINASE DELETION WORSENS LUNG PERMEABILITY AND INCREASES MORTALITY IN PNEUMONIA-INDUCED SEPSIS.

ABSTRACT: Increased epithelial permeability in sepsis is mediated via disruptions in tight junctions, which are closely associated with the perijunctional actin-myosin ring. Genetic deletion of myosin light chain kinase (MLCK) reverses sepsis-induced intestinal hyperpermeability and improves survival in a murine model of intra-abdominal sepsis. In an attempt to determine the generalizability of these findings, this study measured the impact of MLCK deletion on survival and potential associated mechanisms following pneumonia-induced sepsis. MLCK -/- and wild-type mice underwent intratracheal injection of Pseudomonas aeruginosa . Unexpectedly, survival was significantly worse in MLCK -/- mice than wild-type mice. This was associated with increased permeability to Evans blue dye in bronchoalveolar lavage fluid but not in tissue homogenate, suggesting increased alveolar epithelial leak. In addition, bacterial burden was increased in bronchoalveolar lavage fluid. Cytokine array using whole-lung homogenate demonstrated increases in multiple proinflammatory and anti-inflammatory cytokines in knockout mice. These local pulmonary changes were associated with systemic inflammation with increased serum levels of IL-6 and IL-10 and a marked increase in bacteremia in MLCK -/- mice. Increased numbers of both bulk and memory CD4 + T cells were identified in the spleens of knockout mice, with increased early and late activation. These results demonstrate that genetic deletion of MLCK unexpectedly increases mortality in pulmonary sepsis, associated with worsened alveolar epithelial leak and both local and systemic inflammation. This suggests that caution is required in targeting MLCK for therapeutic gain in sepsis.

The Impact of Alcohol Use Disorder on Tuberculosis: A Review of the Epidemiology and Potential Immunologic Mechanisms.

Globally, an estimated 107 million people have an alcohol use disorder (AUD) leading to 2.8 million premature deaths each year. Tuberculosis (TB) is one of the leading causes of death globally and over 8% of global TB cases are estimated to be attributable to AUD. Social determinants of health such as poverty and undernutrition are often shared among those with AUD and TB and could explain the epidemiologic association between them. However, recent studies suggest that these shared risk factors do not fully account for the increased risk of TB in people with AUD. In fact, AUD has been shown to be an independent risk factor for TB, with a linear increase in the risk for TB with increasing alcohol consumption. While few studies have focused on potential biological mechanisms underlying the link between AUD and TB, substantial overlap exists between the effects of alcohol on lung immunity and the mechanisms exploited by Mycobacterium tuberculosis (Mtb) to establish infection. Alcohol misuse impairs the immune functions of the alveolar macrophage, the resident innate immune effector in the lung and the first line of defense against Mtb in the lower respiratory tract. Chronic alcohol ingestion also increases oxidative stress in the alveolar space, which could in turn facilitate Mtb growth. In this manuscript, we review the epidemiologic data that links AUD to TB. We discuss the existing literature on the potential mechanisms by which alcohol increases the risk of TB and review the known effects of alcohol ingestion on lung immunity to elucidate other mechanisms that Mtb may exploit. A more in-depth understanding of the link between AUD and TB will facilitate the development of dual-disease interventions and host-directed therapies to improve lung health and long-term outcomes of TB.

Granulocyte Macrophage-Colony Stimulating Factor Reverses HIV Protein-Induced Mitochondrial Derangements in Alveolar Macrophages.

Despite the advent of antiretroviral therapy, people living with HIV suffer from a range of infectious and noninfectious pulmonary complications. HIV impairs antioxidant defenses and innate immune function of the alveolar macrophage by diminishing granulocyte macrophage-colony stimulating factor (GM-CSF) signaling. Since GM-CSF may be linked to mitochondria, we sought to determine the effects of HIV on GM-CSF receptor expression and alveolar macrophage mitochondrial function. At an academic medical center, studies were completed on alveolar macrophages isolated from both wild-type and HIV transgenic (HIV Tg) rats and human subjects with and without HIV. Primary macrophages were plated and evaluated for expression of GM-CSF receptor beta, phagocytic index, and mitochondrial function in the presence and absence of GM-CSF treatment. GM-CSF receptor expression and mitochondrial function were impaired in macrophages isolated from HIV Tg rats, and treatment with GM-CSF restored GM-CSF receptor expression and mitochondrial function. GM-CSF treatment of HIV Tg rats also increased alveolar macrophage levels of the mitochondrial proteins voltage-dependent anion-selective channel 1 (VDAC) and glucose-regulated protein 75 (Grp75). Similar to the HIV Tg rat model, impairments in mitochondrial bioenergetics were confirmed in alveolar macrophages isolated from human subjects with HIV. HIV-associated impairments in alveolar macrophage mitochondrial bioenergetics likely contribute to innate immune dysfunction in HIV infection, and GM-CSF treatment may offer a novel therapeutic strategy for mitigating these deleterious effects.

HIV Impairs Alveolar Macrophage Function via MicroRNA-144-Induced Suppression of Nrf2.

BACKGROUND: Despite anti-retroviral therapy, HIV-1 infection increases the risk of pneumonia and causes oxidative stress and defective alveolar macrophage (AM) immune function. We have previously determined that HIV-1 proteins inhibit antioxidant defenses and impair AM phagocytosis by suppressing nuclear factor (erythroid-derived 2)-like 2 (Nrf2). Given its known effects on Nrf2, we hypothesize miR-144 mediates the HIV-1 induced suppression of Nrf2. METHODS: Primary AMs isolated from HIV-1 transgenic (HIV-1 Tg) rats and wild type littermates (WT) as well as human monocyte-derived macrophages (MDMs) infected ex vivo with HIV-1 were used. We modulated miR-144 expression using a miR-144 mimic or an inhibitor to assay its effects on Nrf2/ARE activity and AM functions in vitro and in vivo. RESULTS: MiR-144 expression was increased in AMs from HIV-1 Tg rats and in HIV-1-infected human MDMs compared to cells from WT rats and non-infected human MDMs, respectively. Increasing miR-144 with a miR-144 mimic inhibited the expression of Nrf2 and its downstream effectors in WT rat macrophages and consequently impaired their bacterial phagocytic capacity and H2O2 scavenging ability. These effects on Nrf2 expression and AM function were reversed by antagonizing miR-144 ex vivo or in the airways of HIV-1 Tg rats in vivo, but this protection was abrogated by silencing Nrf2 expression. CONCLUSIONS: Our results suggest that inhibiting miR-144 or interfering with its deleterious effects on Nrf2 attenuates HIV-1-mediated AM immune dysfunction and improves lung health in individuals with HIV.

Diagnosis and Management of HIV-Associated Pulmonary Diseases in a Ryan White-Funded Primary Care Setting.

Despite widespread use of antiretroviral therapy (ART), people with HIV (PWH) continue to suffer substantial morbidity and mortality from pulmonary diseases. We sought to evaluate the prevalence of pulmonary symptoms, evaluations, and diagnoses (both infectious and noninfectious) among PWH receiving care at one of the largest HIV clinics in the United States. All PWH seen at the Infectious Disease Program in Atlanta, Georgia, from July 2013 to June 2018 were included. Multivariable logistic regression was used to assess the odds of all-cause mortality. Among 8387 patients, median age was 48 years, 35% had documented smoking, 74% were male, and the 47% with ≥1 pulmonary symptom or diagnosis were older and had higher rates of smoking compared to those without any symptoms or diagnoses (p-values <0.0001). Percent on ART was 97% and 81% for individuals with and without symptoms or diagnoses, respectively (p-value <0.0001). Patients with an infectious diagnosis were more likely to have a diagnostic test ordered than those with a noninfectious diagnosis (p-value <0.0001). After adjustment for demographic and clinical risk factors, odds of death were 2.1 times greater [95% confidence interval (CI) = 1.3-3.5] among those with a pulmonary symptom or diagnosis compared to those without. Despite a high prevalence of pulmonary symptoms and diagnoses in this large cohort of PWH, many did not have a complete diagnostic evaluation, particularly those with noninfectious diagnoses. Greater awareness of evaluation and treatment of noninfectious pulmonary diseases among HIV care providers will be critical to improving long-term outcomes for PWH.