IL-17A impairs host tolerance during airway chronic infection by Pseudomonas aeruginosa

Resistance and tolerance mechanisms participate to the interplay between host and pathogens. IL-17-mediated response has been shown to be crucial for host resistance to respiratory infections, whereas its role in host tolerance during chronic airway colonization is still unclear. Here, we investigated whether IL-17-mediated response modulates mechanisms of host tolerance during airways chronic infection by P. aeruginosa. First, we found that IL-17A levels were sustained in mice at both early and advanced stages of P. aeruginosa chronic infection and confirmed these observations in human respiratory samples from cystic fibrosis patients infected by P. aeruginosa. Using IL-17a(-/-) or IL-17ra(-/-) mice, we found that the deficiency of IL-17A/IL-17RA axis was associated with: i) increased incidence of chronic infection and bacterial burden, indicating its role in the host resistance to P. aeruginosa; ii) reduced cytokine levels (KC), tissue innate immune cells and markers of tissue damage (pro-MMP-9, elastin degradation, TGF-β1), proving alteration of host tolerance. Blockade of IL-17A activity by a monoclonal antibody, started when chronic infection is established, did not alter host resistance but increased tolerance. In conclusion, this study identifies IL-17-mediated response as a negative regulator of host tolerance during P. aeruginosa chronic airway infection

In Vitro Synergism of Colistin and N-acetylcysteine against Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is an emerging global opportunistic pathogen, responsible for a wide range of human infections, including respiratory tract infections. Intrinsic multidrug resistance and propensity to form biofilms make S. maltophilia infections recalcitrant to treatment. Colistin is among the second-line options in case of difficult-to-treat S. maltophilia infections, with the advantage of being also administrable by nebulization. We investigated the potential synergism of colistin in combination with N-acetylcysteine (NAC) (a mucolytic agent with antioxidant and anti-inflammatory properties) against S. maltophilia grown in planktonic phase and biofilm. Eighteen S. maltophilia clinical isolates (comprising three isolates from cystic fibrosis (CF) and two trimethoprim-sulfamethoxazole (SXT)-resistant strains) were included. Checkerboard assays showed a synergism of colistin/NAC combinations against the strains with colistin Minimum Inhibitory Concentration (MIC) >2 µg/mL (n = 13), suggesting that NAC could antagonize the mechanisms involved in colistin resistance. Nonetheless, time-kill assays revealed that NAC might potentiate colistin activity also in case of lower colistin MICs. A dose-dependent potentiation of colistin activity by NAC was also clearly observed against S. maltophilia biofilms, also at sub-MIC concentrations. Colistin/NAC combinations, at concentrations likely achievable by topical administration, might represent a valid option for the treatment of S. maltophilia respiratory infections and should be examined further

How to Process Sputum Samples and Extract Bacterial DNA for Microbiota Analysis

Different steps and conditions for DNA extraction for microbiota analysis in sputum have been reported in the literature. We aimed at testing both dithiothreitol (DTT) and enzymatic treatments of sputum samples and identifying the most suitable DNA extraction technique for the microbiota analysis of sputum. Sputum treatments with and without DTT were compared in terms of their median levels and the coefficient of variation between replicates of both DNA extraction yield and real-time PCR for the 16S rRNA gene. Treatments with and without lysozyme and lysostaphin were compared in terms of their median levels of real-time PCR for S. aureus. Two enzyme-based and three beads-based techniques for DNA extraction were compared in terms of their DNA extraction yield, real-time PCR for the 16S rRNA gene and microbiota analysis. DTT treatment decreased the coefficient of variation between replicates of both DNA extraction yield and real-time PCR. Lysostaphin (either 0.18 or 0.36 mg/mL) and lysozyme treatments increased S. aureus detection. One enzyme-based kit offered the highest DNA yield and 16S rRNA gene real-time PCR with no significant differences in terms of alpha-diversity indexes. A condition using both DTT and lysostaphin/lysozyme treatments along with an enzymatic kit seems to be preferred for the microbiota analysis of sputum samples

italian national survey on molecular epidemiology of pseudomonas aeruginosa from pulmonary infection of cystic fibrosis patients

Pulmonary infection sustained by Pseudomonas aeruginosa is the leading cause of morbidity and mortality of patients affected by Cystic Fibrosis (FC), the most common inherited disease among Caucasian. P. aeruginosa is a ubiquitous microorganism, widely diffuse in the natural and nosocomial environment; however the initial source of acquisition and the way of transmission of this pathogen among CF patients are not yet elucidated. The acquisition of P. aeruginosa by the environment and/or patients to patients transmission was speculated. Moreover in some countries (Australia, United Kingdom) some highly virulent and transmissible strains, called epidemic strains, have spread within the CF care Centres. Aim of the present study was to determine the presence of possible diffuse lineages and the cross-infection degree of P. aeruginosa among Italian CF patients. For this purpose we carried out a national survey, determining the genetic relationship, by molecular typing of a collection of 530 strains recovered from respiratory specimens of 335 patients colonised in follow-up at 8 Regional Reference CF Care Centres located in 3 geographic Italian areas.To investigate a possible environmental acquisition of P. aeruginosa, the genetic relationship between strains from FC, from natural environment, household and nosocomial sources. The molecular epidemiological survey was assessed using DNAfingerprinting methods (Box-PCR e Multi Locus Sequence Typing)

Hypoxia Promotes Danger-mediated Inflammation via Receptor for Advanced Glycation End Products in Cystic Fibrosis

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Signal Transmission in the Auditory System

Contains table of contents for Section 3, an introduction and reports on six research projects.National Institutes of Health Grant R01-DC-00194National Institutes of Health Contract P01-DC-00119National Institutes of Health Fellowship F32-DC00073National Institutes of Health Grant R01-DC00238National Institutes of Health Grant R01-DC00473National Institutes of Health Grant T32-DC00006National Institutes of Health Grant T32-DC00038National Institutes of Health Contract P01-DC00361National Institutes of Health Grant R01-DC00235National Institutes of Health Contract N01-DC2240

Signal Transmission in the Auditory System

Contains table of contents for Section 3, an introduction and reports on six research projects.National Institutes of Health Grant R01-DC-00194-11National Institutes of Health Grant P01-DC00119 Sub-Project 1National Institutes of Health Grant F32-DC00073-2National Institutes of Health Contract P01-DC00119National Institutes of Health Grant R01-DC00238National Institutes of Health Gramt R01-DC00473National Institutes of Health Grant P01-DC00119National Institutes of Health Grant T32-DC00038PNational Institutes of Health Grant P01-DC00361National Institutes of Health Grant 2RO1 DC00235National Institutes of Health Contract NO1-DC2-240

Signal Transmission in the Auditory System

Contains table of contents for Section 3, an introduction and reports on five research projects.National Institutes of Health Grant R01-DC-00194National Institutes of Health Grant P01-DC-00119Charles S. Draper Laboratory Contract DL-H-496015National Institutes of Health Grant R01 DC00238National Institutes of Health Grant R01-DC02258National Institutes of Health Grant T32-DC00038National Institutes of Health Grant RO1 DC00235National Institutes of Health Grant P01-DC00361National Institutes of Health Contract N01-DC-6-210

Signal Transmission in the Auditory System

Contains table of contents for Section 3, an introduction and reports on six research projects.National Institutes of Health Grant RO1-DC-00194-11National Institutes of Health Grant PO1-DC00119 Sub-Project 1National Institutes of Health Grant F32-DC00073-3National Institutes of Health Contract P01-DC00119National Institutes of Health Grant R01 DC00238National Institutes of Health Grant P01-DC00119National Institutes of Health Grant T32-DC00038National Institutes of Health Contract P01-DC00361National Institutes of Health Grant R01-DC00235National Institutes of Health Contract NO1-DC2240

Signal Transmission in the Auditory System

Contains table of contents for Section 3, an introduction and reports on seven research projects.National Institutes of Health Grant P01-DC-00119National Institutes of Health Grant R01-DC-00194National Institutes of Health Grant R01 DC00238National Institutes of Health Grant R01-DC02258National Institutes of Health Grant T32-DC00038National Institutes of Health Grant P01-DC00361National Institutes of Health Grant 2RO1 DC00235National Institutes of Health Contract N01-DC2240