Dataset Information

Lung Surfactant Lipids Provide Immune Protection Against Haemophilus influenzae Respiratory Infection.

ABSTRACT: Non-typeable Haemophilus influenzae (NTHi) causes persistent respiratory infections in patients with chronic obstructive pulmonary disease (COPD), probably linked to its capacity to invade and reside within pneumocytes. In the alveolar fluid, NTHi is in contact with pulmonary surfactant, a lipoprotein complex that protects the lung against alveolar collapse and constitutes the front line of defense against inhaled pathogens and toxins. Decreased levels of surfactant phospholipids have been reported in smokers and patients with COPD. The objective of this study was to investigate the effect of surfactant phospholipids on the host-pathogen interaction between NTHi and pneumocytes. For this purpose, we used two types of surfactant lipid vesicles present in the alveolar fluid: (i) multilamellar vesicles (MLVs, > 1 ?m diameter), which constitute the tensioactive material of surfactant, and (ii) small unilamellar vesicles (SUVs, 0.1 ?m diameter), which are generated after inspiration/expiration cycles, and are endocytosed by pneumocytes for their degradation and/or recycling. Results indicated that extracellular pulmonary surfactant binds to NTHi, preventing NTHi self-aggregation and inhibiting adhesion of NTHi to pneumocytes and, consequently, inhibiting NTHi invasion. In contrast, endocytosed surfactant lipids, mainly via the scavenger receptor SR-BI, did not affect NTHi adhesion but inhibited NTHi invasion by blocking bacterial uptake in pneumocytes. This blockade was made possible by inhibiting Akt phosphorylation and Rac1 GTPase activation, which are signaling pathways involved in NTHi internalization. Administration of the hydrophobic fraction of lung surfactant in vivo accelerated bacterial clearance in a mouse model of NTHi pulmonary infection, supporting the notion that the lipid component of lung surfactant protects against NTHi infection. These results suggest that alterations in surfactant lipid levels in COPD patients may increase susceptibility to infection by this pathogen.

SUBMITTER: Garcia-Fojeda B

PROVIDER: S-EPMC6431623 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Lung Surfactant Lipids Provide Immune Protection Against <i>Haemophilus influenzae</i> Respiratory Infection.

García-Fojeda Belén B González-Carnicero Zoe Z de Lorenzo Alba A Minutti Carlos M CM de Tapia Lidia L Euba Begoña B Iglesias-Ceacero Alba A Castillo-Lluva Sonia S Garmendia Junkal J Casals Cristina C

Frontiers in immunology 20190318

Non-typeable <i>Haemophilus influenzae</i> (NTHi) causes persistent respiratory infections in patients with chronic obstructive pulmonary disease (COPD), probably linked to its capacity to invade and reside within pneumocytes. In the alveolar fluid, NTHi is in contact with pulmonary surfactant, a lipoprotein complex that protects the lung against alveolar collapse and constitutes the front line of defense against inhaled pathogens and toxins. Decreased levels of surfactant phospholipids have bee ...[more]

PMID: 30936871

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Project description:Objectives: Therapies being safe, effective and not vulnerable to develop resistance are highly desirable to counteract bacterial infections. Host-directed therapeutics is an alternative to conventional antibiotics based on perturbing host pathways subverted by pathogens during their life cycle by the use of host-directed drugs to counteract microbial infections. This study sought to identify cellular genes and pathways differentially expressed during airways epithelial infection by nontypable Haemophilus influenzae (NTHi). NTHi is an opportunistic pathogen that is an important cause of exacerbation of chronic obstructive pulmonary disease (COPD). Based on the proposed relationship between NTHi intracellular location and persistence, the antimicrobial potential of a panel of drugs perturbing host pathways used by NTHi to enter epithelial cells was investigated. Methods: We screened for host genes differentially expressed upon infection by the clinical isolate NTHi375 by analyzing A549 cell whole genome expression profiling, and identified a panel of host target candidates which were pharmacologically modulated. Interfering drugs were tested for their bactericidal effect, cytotoxicity, effect on the interplay NTHi-epithelial cell, and effect on NTHi respiratory infection in vivo, by assessing lung bacterial loads in a murine intranasal infection model. Results: The sirtuin-1 activator resveratrol showed a bactericidal effect against NTHi; the PDE4 inhibitor rolipram showed therapeutic efficacy by lowering NTHi375 counts both intracellularly and in the lungs of infected mice. Conclusions: PDE4 inhibition is currently prescribed in COPD; resveratrol is a geroprotector attractive for COPD treatment by preventing lung aging. This work provides evidence for the antimicrobial potential of rolipram and resveratrol against NTHi respiratory infection. Haemophilus influenzae clinical strain NTHi375 induced gene expression in A549 human type II pneumocyte cell line was measured at 2 h post-infection. Non infected cells were used as a control. Four independent experiments were performed for each condition.

Dataset Information

Lung Surfactant Lipids Provide Immune Protection Against Haemophilus influenzae Respiratory Infection.

Publications

Lung Surfactant Lipids Provide Immune Protection Against <i>Haemophilus influenzae</i> Respiratory Infection.

Similar Datasets

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