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Cellular Physiology and Biochemistry :... Oct 2020Sphingosine, a sphingoid long chain base, is a natural lipid with antimicrobial properties. Recent animal studies have shown that preventive sphingosine inhalation can...
BACKGROUND/AIMS
Sphingosine, a sphingoid long chain base, is a natural lipid with antimicrobial properties. Recent animal studies have shown that preventive sphingosine inhalation can rescue susceptible mice, such as cystic fibrosis-, burn injured- or aged mice from bacterial pulmonary infection. While preventing lung infections in susceptible patients has obvious clinical merit, treatment strategies for an established infection are also direly needed, particularly in the times of rising antibiotic resistance. Here, we tested the potential of sphingosine in treating an established pulmonary infection.
METHODS
We used a cecal ligation and puncture (CLP) model in male CF-1 mice and a Pseudomonas aeruginosa strain that was isolated from a septic patient (P. aeruginosa 762). We determined susceptibility to intranasal infection and ascertained when the pulmonary infection was established by continuous core body temperature monitoring. We quantified sphingosine levels in the tracheal epithelium by immunohistochemistry and studied the effects on sphingosine on bacterial membrane permeabilization and intracellular acidification using fluorescent probes.
RESULTS
We first determined that septic mice are highly susceptible to P. aeruginosa infection 2 days after indu-cing sepsis. Additionally, at this time, sphingosine levels in the tracheal epithelium are significantly reduced as compared to levels in healthy mice. Secondly, upon intranasal Pseudomonas inoculation, we ascertained that pulmonary infection was established as early as 2.5 h after inoculation as evidenced by a significant drop in core body temperature. Using these times of infection susceptibility and detection (2 days post CLP, 2.5h after inoculation) we treated with inhaled sphingosine and observed pulmonary bacterial loads reduced to levels found in infected healthy mice after inoculation and decreased infection-associated mortality. Further, our data demonstrate that sphingosine induces outer membrane permeabilization, disrupting the membrane potential and leading to intracellular acidification of the bacteria.
CONCLUSION
Sphingosine shows efficacy in treating P. aeruginosa lung infections not only prophylactically, but also therapeutically.
Topics: Administration, Inhalation; Animals; Critical Illness; Cystic Fibrosis; Disease Models, Animal; Lung; Male; Mice; Pseudomonas Infections; Pseudomonas aeruginosa; Sepsis; Sphingosine; Trachea
PubMed: 33080125
DOI: 10.33594/000000287 -
Frontiers in Cellular and Infection... 2021SARS-CoV-2 infection can cause fatal inflammatory lung pathology, including thrombosis and increased pulmonary vascular permeability leading to edema and hemorrhage. In...
SARS-CoV-2 infection can cause fatal inflammatory lung pathology, including thrombosis and increased pulmonary vascular permeability leading to edema and hemorrhage. In addition to the lung, cytokine storm-induced inflammatory cascade also affects other organs. SARS-CoV-2 infection-related vascular inflammation is characterized by endotheliopathy in the lung and other organs. Whether SARS-CoV-2 causes endotheliopathy by directly infecting endothelial cells is not known and is the focus of the present study. We observed 1) the co-localization of SARS-CoV-2 with the endothelial cell marker CD31 in the lungs of SARS-CoV-2-infected mice expressing hACE2 in the lung by intranasal delivery of adenovirus 5-hACE2 (Ad5-hACE2 mice) and non-human primates at both the protein and RNA levels, and 2) SARS-CoV-2 proteins in endothelial cells by immunogold labeling and electron microscopic analysis. We also detected the co-localization of SARS-CoV-2 with CD31 in autopsied lung tissue obtained from patients who died from severe COVID-19. Comparative analysis of RNA sequencing data of the lungs of infected Ad5-hACE2 and Ad5-empty (control) mice revealed upregulated KRAS signaling pathway, a well-known pathway for cellular activation and dysfunction. Further, we showed that SARS-CoV-2 directly infects mature mouse aortic endothelial cells (AoECs) that were activated by performing an aortic sprouting assay prior to exposure to SARS-CoV-2. This was demonstrated by co-localization of SARS-CoV-2 and CD34 by immunostaining and detection of viral particles in electron microscopic studies. Moreover, the activated AoECs became positive for ACE-2 but not quiescent AoECs. Together, our results indicate that in addition to pneumocytes, SARS-CoV-2 also directly infects mature vascular endothelial cells and , which may contribute to cardiovascular complications in SARS-CoV-2 infection, including multipleorgan failure.
Topics: Animals; COVID-19; Disease Models, Animal; Endothelial Cells; Humans; Lung; Mice; Mice, Transgenic; SARS-CoV-2
PubMed: 34307198
DOI: 10.3389/fcimb.2021.701278 -
The American Journal of Pathology Dec 2019Influenza virus infection causes a spectrum of diseases, ranging from mild upper respiratory tract infection to severe lower respiratory tract infection, that can lead...
Influenza virus infection causes a spectrum of diseases, ranging from mild upper respiratory tract infection to severe lower respiratory tract infection, that can lead to diffuse alveolar damage, interstitial and airspace inflammation, or acute respiratory failure. Mechanisms instructing disease severity are not completely understood, but host, viral, and bacterial factors influence disease outcome. With age being one host factor associated with a higher risk of severe influenza, we investigated regional pulmonary distribution and severity of pneumonia after 2009 H1N1 influenza virus infection in newly weaned, adult, and aged ferrets to better understand age-dependent susceptibility and pathology. Aged ferrets exhibited greater weight loss and higher rates of mortality than adult ferrets, whereas most newly weaned ferrets did not lose weight but had a lack of weight gain. Newly weaned ferrets exhibited minimal pneumonia, whereas adult and aged ferrets had a spectrum of pneumonia severity. Influenza virus-induced pneumonia peaked earliest in adult ferrets, whereas aged ferrets had delayed presentation. Bronchial severity differed among groups, but bronchial pathology was comparable among all cohorts. Alveolar infection was strikingly different among groups. Newly weaned ferrets had little alveolar cell infection. Adult and aged ferrets had alveolar infection, but aged ferrets were unable to clear infection. These different age-related pneumonia and infection patterns suggest therapeutic strategies to treat influenza should be tailored contingent on age.
Topics: Aging; Animals; Disease Models, Animal; Female; Ferrets; Influenza A Virus, H1N1 Subtype; Lung; Male; Orthomyxoviridae Infections; Respiratory Tract Infections; Severity of Illness Index
PubMed: 31585069
DOI: 10.1016/j.ajpath.2019.08.017 -
Virology Journal Dec 2015Middle-East Respiratory Syndrome coronavirus (MERS-CoV) was identified to cause severe respiratory infection in humans since 2012. The continuing MERS epidemic with a... (Review)
Review
Middle-East Respiratory Syndrome coronavirus (MERS-CoV) was identified to cause severe respiratory infection in humans since 2012. The continuing MERS epidemic with a case-fatality of more than 30% poses a major threat to public health worldwide. Currently, the pathogenesis of human MERS-CoV infection remains poorly understood. We reviewed experimental findings from human primary cells and ex vivo human lung tissues, as well as those from animal studies, so as to understand the pathogenesis and high case-fatality of MERS. Human respiratory epithelial cells are highly susceptible to MERS-CoV and can support productive viral replication. However, the induction of antiviral cytokines and proinflammatory cytokines/chemokines are substantially dampened in the infected epithelial cells, due to the antagonistic mechanisms evolved by the virus. MERS-CoV can readily infect and robustly replicate in human macrophages and dendritic cells, triggering the aberrant production of proinflammatory cytokines/chemokines. MERS-CoV can also effectively infect human primary T cells and induce massive apoptosis in these cells. Although data from clinical, in vitro and ex vivo studies suggested the potential for virus dissemination, extrapulmonary involvement in MERS patients has not been ascertained due to the lack of autopsy study. In MERS-CoV permissive animal models, although viral RNA can be detected from multiple organs of the affected animals, the brain of human DPP4-transgenic mouse was the only extrapulmonary organ from which the infectious virus can be recovered. More research findings on the pathogenesis of MERS and the tissue tropisms of MERS-CoV may help to improve the treatment and infection control of MERS.
Topics: Animals; Apoptosis; Coronavirus Infections; Dendritic Cells; Disease Models, Animal; Epithelial Cells; Host-Pathogen Interactions; Humans; Lung; Macrophages; Middle East Respiratory Syndrome Coronavirus; T-Lymphocytes; Virus Replication
PubMed: 26690369
DOI: 10.1186/s12985-015-0446-6 -
European Respiratory Review : An... Apr 2024Respiratory viral infections represent one of the major causes of death worldwide. The recent coronavirus disease 2019 pandemic alone claimed the lives of over 6 million... (Review)
Review
Respiratory viral infections represent one of the major causes of death worldwide. The recent coronavirus disease 2019 pandemic alone claimed the lives of over 6 million people around the globe. It is therefore crucial to understand how the immune system responds to these threats and how respiratory infection can be controlled and constrained. Dendritic cells (DCs) are one of the key players in antiviral immunity because of their ability to detect pathogens. They can orchestrate an immune response that will, in most cases, lead to viral clearance. Different subsets of DCs are present in the lung and each subset can contribute to antiviral responses through various mechanisms. In this review, we discuss the role of the different lung DC subsets in response to common respiratory viruses, with a focus on respiratory syncytial virus, influenza A virus and severe acute respiratory syndrome coronavirus 2. We also review how lung DC-mediated responses to respiratory viruses can lead to the worsening of an existing chronic pulmonary disease such as asthma. Throughout the review, we discuss results obtained from animal studies as well as results generated from infected patients.
Topics: Dendritic Cells; Humans; Animals; Respiratory Tract Infections; Lung; Host-Pathogen Interactions; COVID-19; Virus Diseases; SARS-CoV-2
PubMed: 38811032
DOI: 10.1183/16000617.0250-2023 -
American Journal of Physiology. Lung... Nov 2020Antiretroviral therapy in HIV patients has lengthened lifespan but led to an increased risk for secondary comorbidities, such as pulmonary complications characterized by...
Antiretroviral therapy in HIV patients has lengthened lifespan but led to an increased risk for secondary comorbidities, such as pulmonary complications characterized by vascular dysfunction. In the lung, PDGFRβ+ mesenchymal cells known as pericytes intimately associate with endothelial cells and are key for their survival both structurally and through the secretion of prosurvival factors. We hypothesize that in HIV infection there are functional changes in pericytes that may lead to destabilization of the microvasculature and ultimately to pulmonary abnormalities. Our objective in this study was to determine whether lung pericytes could be directly infected with HIV. We leveraged lung samples from macaque lungs with or without SIV infection and normal human lung for in vitro experiments. Pericytes were isolated based on the marker platelet-derived growth factor receptor-β (PDGFRβ). We determined that lung PDGFRβ-positive (PDGFRβ+) pericytes from both macaques and humans express CD4, the primary receptor for SIV/HIV, as well as the major coreceptors CXCR4 and CCR5. We found cells positive for both PDGFRβ and SIV in lungs from infected macaques. Lung pericytes isolated from these animals also harbored detectable SIV. To confirm relevance to human disease, we demonstrated that human lung pericytes are capable of being productively infected by HIV in vitro, with the time course of infection suggesting development of viral latency. In summary, we show for the first time that SIV/HIV directly infects lung pericytes, implicating these cells as a novel target and potential reservoir for the virus in vivo.
Topics: CD4-Positive T-Lymphocytes; Endothelial Cells; HIV Infections; Humans; Lung; Macrophages; Receptors, CXCR4; Simian Immunodeficiency Virus; Virus Latency; Virus Replication
PubMed: 32901522
DOI: 10.1152/ajplung.00296.2020 -
The Journal of Infectious Diseases Aug 2023Acinetobacter baumannii causes a wide range of dangerous infections due to the emergence of pandrug-resistant strains. Therefore, there is a need for alternative...
BACKGROUND
Acinetobacter baumannii causes a wide range of dangerous infections due to the emergence of pandrug-resistant strains. Therefore, there is a need for alternative therapeutics to treat these infections, including those targeting the host immune responses. However, immune responses, especially the humoral response against this pathogen, are poorly understood.
METHODS
This study investigated the lymphocyte-mediated innate immune resistance to A. baumannii AB5075 pulmonary infection using B- and T-cell-deficient (Rag2-/-) mice, the protective effect of natural antibodies (NAbs), and the expression of complement-mediated responses using a mouse pneumonia model.
RESULTS
Our results showed that intranasally infected Rag2-/- mice are impaired in clearing bacteria from lung, liver, and spleen at 24 hours postinfection compared to wildtype mice. Animal pretreatment with normal mouse serum or purified antibodies from naive mice rescued Rag2-/- mice from infection. Analysis of C3 complement protein binding demonstrated that NAbs increased C3 protein deposition on A. baumannii cells, indicating the activation of the classical complement pathway by NAbs.
CONCLUSIONS
Overall, our study shows that NAbs mediate innate immune resistance against A. baumannii, a finding that may lead to the development of effective therapies against human infections caused by this antibiotic-resistant A. baumannii.
Topics: Humans; Animals; Mice; Acinetobacter baumannii; Pneumonia; Lung; Respiratory Tract Infections; Anti-Bacterial Agents; Antibodies
PubMed: 36951192
DOI: 10.1093/infdis/jiad069 -
Scientific Reports Mar 2021Mesenchymal stem/stromal cells (MSCs) have demonstrated efficacy in pre-clinical models of inflammation and tissue injury, including in models of lung injury and...
Mesenchymal stem/stromal cells (MSCs) have demonstrated efficacy in pre-clinical models of inflammation and tissue injury, including in models of lung injury and infection. Rolling, adhesion and transmigration of MSCs appears to play a role during MSC kinetics in the systemic vasculature. However, a large proportion of MSCs become entrapped within the lungs after intravenous administration, while the initial kinetics and the site of arrest of MSCs in the pulmonary vasculature are unknown. We examined the kinetics of intravascularly administered MSCs in the pulmonary vasculature using a microfluidic system in vitro and intra-vital microscopy of intact mouse lung. In vitro, MSCs bound to endothelium under static conditions but not under laminar flow. VCAM-1 antibodies did not affect MSC binding. Intravital microscopy demonstrated MSC arrest at pulmonary micro-vessel bifurcations due to size obstruction. Retention of MSCs in the pulmonary microvasculature was increased in Escherichia coli-infected animals. Trapped MSCs deformed over time and appeared to release microvesicles. Labelled MSCs retained therapeutic efficacy against pneumonia. Our results suggest that MSCs are physically obstructed in pulmonary vasculature and do not display properties of rolling/adhesion, while retention of MSCs in the infected lung may require receptor interaction.
Topics: Administration, Intravenous; Animals; Blood Vessels; Cardiovascular System; Disease Models, Animal; Humans; Kinetics; Lung; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Mice; Pneumonia
PubMed: 33664277
DOI: 10.1038/s41598-021-83894-7 -
Frontiers in Cellular and Infection... 2017Influenza A virus (IAV) infects millions of people annually and predisposes to secondary bacterial infections. Inhalation of fungi within the complex causes pulmonary...
Influenza A virus (IAV) infects millions of people annually and predisposes to secondary bacterial infections. Inhalation of fungi within the complex causes pulmonary disease with secondary meningo-encephalitis. Underlying pulmonary disease is a strong risk factor for development of cryptococcosis though the effect of concurrent infection with IAV has not been studied. We developed an model of Influenza A H1N1 and co-infection. Co-infection resulted in a major increase in morbidity and mortality, with severe lung damage and a high brain fungal burden when mice were infected in the acute phase of influenza multiplication. Furthermore, IAV alters the host response to , leading to recruitment of significantly more neutrophils and macrophages into the lungs. Moreover, IAV induced the production of type 1 interferons (IFN-α4/β) and the levels of IFN-γ were significantly reduced, which can be associated with impairment of the immune response to during co-infection. Phagocytosis, killing of cryptococci and production of reactive oxygen species (ROS) by IAV-infected macrophages were reduced, independent of previous IFN-γ stimulation, leading to increased proliferation of the fungus within macrophages. In conclusion, IAV infection is a predisposing factor for severe disease and adverse outcomes in mice co-infected with .
Topics: Acetylglucosaminidase; Animals; Behavior, Animal; Brain; Causality; Cell Proliferation; Chemokines; Coinfection; Cryptococcosis; Cryptococcus gattii; Cryptococcus neoformans; Cytokines; Disease Models, Animal; Disease Susceptibility; Dogs; Female; Humans; Influenza A Virus, H1N1 Subtype; Interferon-gamma; Lung; Macrophages; Madin Darby Canine Kidney Cells; Mice; Mice, Inbred C57BL; Neutrophils; Nitric Oxide; Orthomyxoviridae Infections; Peroxidase; Peroxynitrous Acid; Phagocytosis; Reactive Oxygen Species; Survival Rate
PubMed: 29018774
DOI: 10.3389/fcimb.2017.00419 -
Mediators of Inflammation 2019Infection is a common cause of hospitalization and mortality in patients with systemic lupus erythematosus (SLE). How the underlying immune dysfunctions affect the...
Infection is a common cause of hospitalization and mortality in patients with systemic lupus erythematosus (SLE). How the underlying immune dysfunctions affect the antimicrobial immunity remains largely unknown. In the present study, employing the pulmonary infection model, we determined the antimicrobial defence of lupus-prone mice. After infecting with opportunistic bacterium (Hi), lupus-prone mice (B6/lpr) exhibited inefficient bacterial elimination and recovered slowly. They generated severer inflammation at the early stage of infection, as excessive accumulation of neutrophils and enhanced production of proinflammatory cytokines were observed in the lung. In addition, a large number of apoptotic cells were detected in the lungs of B6/lpr mice. For adaptive immune responses, B6/lpr mice were capable to generate enough protective Hi-specific Th17 cells. They evoked stronger Hi-specific T17 response in both lungs and spleens. Unexpectedly, both CD4 and T cells from lupus-prone mice showed deficiency in IFN- production. For humoral immune responses, compared with those of WT mice, the concentrations of Hi-specific IgA, IgM, and IgG, especially IgG, were significantly higher in the B6/lpr mice. Our findings suggest that lupus mice are capable to generate antibacterial immune responses; however, the overwhelming inflammation and overactivated immune responses increase the severity of infection.
Topics: Animals; Apoptosis; Bacteria; Cells, Cultured; Disease Models, Animal; Female; Flow Cytometry; Lung; Lupus Erythematosus, Systemic; Mice; Mice, Inbred C57BL; Opportunistic Infections; Pneumonia
PubMed: 31565032
DOI: 10.1155/2019/1701367