Effects of Electronic (e)-Cigarette Vapor on Staphylococcal Virulence: Are E-Cigarettes Safer than Conventional Cigarettes?

In recent years, electronic (e)‐cigarettes have dramatically increased in popularity as an alternative to conventional cigarettes. Little is known about the effects of e‐cigarette vapor (EV) on bacteria that colonize the nasopharynx, including methicillin‐resistant Staphylococcusaureus (MRSA). As most cases of pneumonia can be traced to bacteria in a patient\u27s nasopharynx, increased virulence in potential pathogens could have direct consequences clinically for these patients. And because bacterial colonizers are spread between humans, increased virulence in one subject has implications for the community. There is accumulating evidence that exposure to cigarette smoke (CS) increases the pathogenicity of MRSA, as well as its dampening effects on the host immune system. EV exposure has also been demonstrated to increase MRSA virulence both invitro and in a murine model of pneumonia. In this chapter, we will compare the virulence changes reported in MRSA exposed to CS vs. those exposed to EV, as well as proposed mechanisms and therapeutic targets

Transcriptomic responses in the blood and sputum of cigarette smokers compared to e-cigarette vapers.

RATIONALE: Electronic (e)-cigarettes are popular among youth and cigarette smokers attempting to quit. Studies to date have focused on the utility of e-cigarettes as a smoking cessation tool, but the biological effects are largely unknown. OBJECTIVES: To identify transcriptomic differences in the blood and sputum of e-cigarette users compared to conventional cigarettes smokers and healthy controls and describe biological pathways affected by these tobacco products. METHODS: Cross-sectional analysis of whole blood and sputum RNA-sequencing data from 8 smokers, 9 e-cigarette users (e-cigs) and 4 controls. Weighted gene co-network analysis (WGCNA) identified gene module associations. Ingenuity Pathway Analysis (IPA) identified canonical pathways associated with tobacco products. MAIN RESULTS: In blood, a three-group comparison showed 16 differentially expressed genes (DEGs); pair-wise comparison showed 7 DEGs between e-cigs and controls, 35 DEGs between smokers and controls, and 13 DEGs between smokers and e-cigs. In sputum, 438 DEGs were in the three-group comparison. In pair-wise comparisons, there were 2 DEGs between e-cigs and controls, 270 DEGs between smokers and controls, and 468 DEGs between smokers and e-cigs. Only 2 genes in the smokers vs. control comparison overlapped between blood and sputum. Most gene modules identified through WGCNA associated with tobacco product exposures also were associated with cotinine and exhaled CO levels. IPA showed more canonical pathways altered by conventional cigarette smoking than by e-cigarette use. CONCLUSION: Cigarette smoking and e-cigarette use led to transcriptomic changes in both blood and sputum. However, conventional cigarettes induced much stronger transcriptomic responses in both compartments

Myeloid Cell Sirtuin-1 Expression Does Not Alter Host Immune Responses to Gram-Negative Endotoxemia or Gram-Positive Bacterial Infection

The role of sirtuin-1 (SIRT1) in innate immunity, and in particular the influence of SIRT1 on antimicrobial defense against infection, has yet to be reported but is important to define since SIRT1 inhibitors are being investigated as therapeutic agents in the treatment of cancer, Huntington’s disease, and autoimmune diseases. Given the therapeutic potential of SIRT1 suppression, we sought to characterize the role of SIRT1 in host defense. Utilizing both pharmacologic methods and a genetic knockout, we demonstrate that SIRT1 expression has little influence on macrophage and neutrophil antimicrobial functions. Myeloid SIRT1 expression does not change mortality in gram-negative toxin-induced shock or gram-positive bacteremia, suggesting that therapeutic suppression of SIRT1 may be done safely without suppression of myeloid cell-specific immune responses to severe bacterial infections.American Asthma Foundation (Stephen Silberstein Senior Fellowship Awards

Electronic cigarette inhalation alters innate immunity and airway cytokines while increasing the virulence of colonizing bacteria.

UnlabelledElectronic (e)-cigarette use is rapidly rising, with 20 % of Americans ages 25-44 now using these drug delivery devices. E-cigarette users expose their airways, cells of host defense, and colonizing bacteria to e-cigarette vapor (EV). Here, we report that exposure of human epithelial cells at the air-liquid interface to fresh EV (vaped from an e-cigarette device) resulted in dose-dependent cell death. After exposure to EV, cells of host defense-epithelial cells, alveolar macrophages, and neutrophils-had reduced antimicrobial activity against Staphylococcus aureus (SA). Mouse inhalation of EV for 1 h daily for 4 weeks led to alterations in inflammatory markers within the airways and elevation of an acute phase reactant in serum. Upon exposure to e-cigarette vapor extract (EVE), airway colonizer SA had increased biofilm formation, adherence and invasion of epithelial cells, resistance to human antimicrobial peptide LL-37, and up-regulation of virulence genes. EVE-exposed SA were more virulent in a mouse model of pneumonia. These data suggest that e-cigarettes may be toxic to airway cells, suppress host defenses, and promote inflammation over time, while also promoting virulence of colonizing bacteria.Key messageAcute exposure to e-cigarette vapor (EV) is cytotoxic to airway cells in vitro. Acute exposure to EV decreases macrophage and neutrophil antimicrobial function. Inhalation of EV alters immunomodulating cytokines in the airways of mice. Inhalation of EV leads to increased markers of inflammation in BAL and serum. Staphylococcus aureus become more virulent when exposed to EV

HIF2α-arginase axis is essential for the development of pulmonary hypertension.

Hypoxic pulmonary vasoconstriction is correlated with pulmonary vascular remodeling. The hypoxia-inducible transcription factors (HIFs) HIF-1α and HIF-2α are known to contribute to the process of hypoxic pulmonary vascular remodeling; however, the specific role of pulmonary endothelial HIF expression in this process, and in the physiological process of vasoconstriction in response to hypoxia, remains unclear. Here we show that pulmonary endothelial HIF-2α is a critical regulator of hypoxia-induced pulmonary arterial hypertension. The rise in right ventricular systolic pressure (RVSP) normally observed following chronic hypoxic exposure was absent in mice with pulmonary endothelial HIF-2α deletion. The RVSP of mice lacking HIF-2α in pulmonary endothelium after exposure to hypoxia was not significantly different from normoxic WT mice and much lower than the RVSP values seen in WT littermate controls and mice with pulmonary endothelial deletion of HIF-1α exposed to hypoxia. Endothelial HIF-2α deletion also protected mice from hypoxia remodeling. Pulmonary endothelial deletion of arginase-1, a downstream target of HIF-2α, likewise attenuated many of the pathophysiological symptoms associated with hypoxic pulmonary hypertension. We propose a mechanism whereby chronic hypoxia enhances HIF-2α stability, which causes increased arginase expression and dysregulates normal vascular NO homeostasis. These data offer new insight into the role of pulmonary endothelial HIF-2α in regulating the pulmonary vascular response to hypoxia

M1T1 group A streptococcal pili promote epithelial colonization but diminish systemic virulence through neutrophil extracellular entrapment

Group A Streptococcus is a leading human pathogen associated with a diverse array of mucosal and systemic infections. Cell wall anchored pili were recently described in several species of pathogenic streptococci, and in the case of GAS, these surface appendages were demonstrated to facilitate epithelial cell adherence. Here we use targeted mutagenesis to evaluate the contribution of pilus expression to virulence of the globally disseminated M1T1 GAS clone, the leading agent of both GAS pharyngitis and severe invasive infections. We confirm that pilus expression promotes GAS adherence to pharyngeal cells, keratinocytes, and skin. However, in contrast to findings reported for group B streptococcal and pneumococcal pili, we observe that pilus expression reduces GAS virulence in murine models of necrotizing fasciitis, pneumonia and sepsis, while decreasing GAS survival in human blood. Further analysis indicated the systemic virulence attenuation associated with pilus expression was not related to differences in phagocytic uptake, complement deposition or cathelicidin antimicrobial peptide sensitivity. Rather, GAS pili were found to induce neutrophil IL-8 production, promote neutrophil transcytosis of endothelial cells, and increase neutrophil release of DNA-based extracellular traps, ultimately promoting GAS entrapment and killing within these structures

The Precision Interventions for Severe and/or Exacerbation-Prone (PrecISE) Asthma Network: an overview of Network organization, procedures and interventions

Asthma is a heterogeneous disease, with multiple underlying inflammatory pathways and structural airway abnormalities that impact disease persistence and severity. Recent progress has been made in developing targeted asthma therapeutics, especially for subjects with eosinophilic asthma. However, there is an unmet need for new approaches to treat patients with severe and exacerbation prone asthma, who contribute disproportionately to disease burden. Extensive deep phenotyping has revealed the heterogeneous nature of severe asthma and identified distinct disease subtypes. A current challenge in the field is to translate new and emerging knowledge about different pathobiologic mechanisms in asthma into patient-specific therapies, with the ultimate goal of modifying the natural history of disease. Here we describe the Precision Interventions for Severe and/or Exacerbation Prone Asthma (PrecISE) Network, a groundbreaking collaborative effort of asthma researchers and biostatisticians from around the U.S. The PrecISE Network was designed to conduct phase II/proof of concept clinical trials of precision interventions in the severe asthma population, and is supported by the National Heart Lung and Blood Institute of the National Institutes of Health. Using an innovative adaptive platform trial design, the Network will evaluate up to six interventions simultaneously in biomarker-defined subgroups of subjects. We review the development and organizational structure of the Network, and choice of interventions being studied. We hope that the PrecISE Network will enhance our understanding of asthma subtypes and accelerate the development of therapeutics for of severe asthma