TLR4 Polymorphism, Nasopharyngeal Bacterial Colonization, and the Development of Childhood Asthma: A Prospective Birth-Cohort Study in Finnish Children.

We aimed to explore the role of TLR4 (rs4986790) polymorphism in the nasopharyngeal (NP) bacterial colonization and its consequent impact on the development of childhood asthma. A semi-quantitative culture of NP swabs was performed on 473 children at 2 months of age and on 213 children at 13 months of age. TLR4 polymorphism was analyzed for 396 children. Children were followed from birth to the age of 7.5 years and the final outcome was physician-diagnosed asthma. The associations between TLR4 genotype, bacterial colonization, and asthma were analyzed. Children with TLR4 AG or GG genotype were more often colonized with Moraxella catarrhalis at 2 months of age (p = 0.009) and Haemophilus influenzae at 13 months of age (p = 0.018). Children who were colonized with H. influenzae at 13 months of age had a significantly higher risk of later development of asthma (p = 0.004). M. catarrhalis or H. Influenzae colonization at 2 months of age or TLR4 genotype Asp299Gly were not associated with the development of childhood asthma. TLR4 Asp299Gly polymorphism was associated with an increased risk of colonization of M. catarrhalis and H. influenzae in children. The colonization with H. influenzae at 13 months of age was associated with a higher risk of later development of childhood asthma.

IL-33/ST2 immune responses to respiratory bacteria in pediatric asthma.

Here we investigated the relationship between local bacterial colonization and anti-bacterial immune responses in pre-school asthmatic and control children within the EU-wide study PreDicta. In this cohort of pre-school asthmatic children, nasopharyngeal colonization with Gram-negative bacteria such as Haemophilus influenzae and Moraxella catarrhalis was found to be associated with the highest interferon beta (IFNß) and IL-33 levels in the nasal pharyngeal fluids (NPF). IL33R-ST2 was found induced in the blood of asthmatic children with additional Gram + bacteria in the nasopharynx (Gr+/-). Furthermore, asthmatic children had more episodes of infection that required antibiotic therapy than the control group. Treatment with antibiotics associated with reduced ST2 in blood cells of both asthmatic and control children and reduced IL-33 levels in the airways of asthmatic children. In the absence of Staphylococcus (S.) aureus in NPF, antibiotic therapy associated with decreased IL-33 levels in the NPF and lower ST2 values in the blood of control children but not of asthmatic children. These data suggest that, in asthmatic children, Gram- bacteria, which persist after antibiotic therapy, contributes to IL-33 locally and associated with Gr + bacteria colonization in the airways, inhibited IFN-ß and in the absence of Staphylococcus (S.) aureus, induced ST2 bearing cells in their blood.

Immune response of the Antarctic teleost Trematomus bernacchii to immunization with Psychrobacter sp. (TAD1).

Adult Trematomus bernacchii have been immunized intraperitoneally with heat-killed cells of the Antarctic marine bacterium Psychrobacter sp. (TAD1) up to 60 days. After immunizations and sampling at various times, fish sera were tested for specific IgM by ELISA, and different tissues (head kidney and spleen) were investigated for transcription of master genes of the acquired immune response (IgM, IgT, TRß, TRγ). Results from ELISA assays showed a time-dependent induction of specific serum anti-TAD1 IgM, and western blot analysis of TAD1 lysates probed with fish sera revealed enhanced immunoreactivity in immunized animals compared to controls. Quantitative PCR analysis of transcripts coding for IgM, IgT, TRß, TRγ was performed in T. bernacchii tissues to assess basal expression, and then on cDNAs of cells from head kidney and spleen of fish injected for 8, 24, and 72 h with inactivated TAD1. The results showed a differential basal expression of transcripts in the examined tissues, and a time-dependent strong up-regulation of IgT, TRß, TRγ genes upon in vivo stimulation with TAD1. These results represent a first in vivo study on the mounting of a specific immune response in an Antarctic teleost species.

Acute eosinophilic pneumonia occurring in a dedicator of cytokinesis 8 (DOCK8) deficient patient.

Dedicator of cytokinesis 8 (DOCK8) deficiency is an autosomal recessive type of combined immunodeficiency with elevated IgE. In this report, we describe a Japanese girl of non-consanguineous family suffering from acute eosinophilic pneumonia (AEP) as a presenting feature of DOCK8 deficiency. Although AEP was self-limiting, consecutively experienced recurrent respiratory infections, severe atopic dermatitis, and vulnerability to viral infections, prompted us to evaluate the possibility of DOCK8 deficiency. Immunological assessments demonstrated decreased IgM, increased IgE, T lymphocytepenia, especially in CD4 T cells, decreased PHA blastogenesis, and decreased CD27(+) CD19(+) memory B cells. Western blotting revealed the absence of DOCK8 protein. Investigation of genomic DNA by multiplex ligation-dependent probe amplification (MLPA) revealed a heterozygous large deletion of 77 kb spanning from intron 5 to exon 22. DOCK8 cDNA sequencing revealed a nonsense mutation at position 740 (E740X). As far as we know, this is the first Japanese case of DOCK8 deficiency.

Risk of repeated Moraxella catarrhalis colonization is increased in children with Toll-like receptor 4 Asp299Gly polymorphism.

BACKGROUND: Moraxella catarrhalis is a common causative agent of acute otitis media and other respiratory infections in children. Toll-like receptor (TLR) 4 is an important protein of human innate immunity. One polymorphic site Asp299Gly of TLR4 is proven to result in an impaired response to lipopolysaccharide from Gram-negative bacteria. We investigated whether Finnish children who carry Asp299Gly had increased risk of M. catarrhalis colonization during their first 2 years of life. METHODS: This was a prospective cohort study carried out in Turku, Finland. We studied M. catarrhalis colonization in 161 Finnish children, whose nasopharyngeal specimens were taken at 2, 12 and 24 months of age. The semiquantitative culture method was used for identification of different bacterial species and the pyrosequencing-based method for detection of TLR4 Asp299Gly. RESULTS: Of 161 subjects, 126 (78%) were TLR4 A/A wild type and 35 (22%) were A/G heterozygote variants. The prevalence of M. catarrhalis increased from 24% at 2 months to 48% at 12 months and to 58% at 24 months of age. Of the 35 subjects with TLR4 variant, 15 (43%) were M. catarrhalis positive at all 3 time points, whereas only 11 (9%) subjects with TLR4 wild type were positive at these time points (relative risk 4.91, 95% confidence interval: 2.482-9.711, P=0.0001). Moreover, subjects with TLR4 variant had significantly higher bacterial load of M. catarrhalis in their nasopharynx than those with TLR4 wild type (P=0.0032). CONCLUSIONS: Our results indicate that children with TLR4 Asp299Gly polymorphism have an increased risk of repeated M. catarrhalis colonization.

Role of the zinc uptake ABC transporter of Moraxella catarrhalis in persistence in the respiratory tract.

Moraxella catarrhalis is a human respiratory tract pathogen that causes otitis media in children and lower respiratory tract infections in adults with chronic obstructive pulmonary disease. We have identified and characterized a zinc uptake ABC transporter that is present in all strains of M. catarrhalis tested. A mutant in which the znu gene cluster is knocked out shows markedly impaired growth compared to the wild type in medium that contains trace zinc; growth is restored to wild-type levels by supplementing medium with zinc but not with other divalent cations. Thermal-shift assays showed that the purified recombinant substrate binding protein ZnuA binds zinc but does not bind other divalent cations. Invasion assays with human respiratory epithelial cells demonstrated that the zinc ABC transporter of M. catarrhalis is critical for invasion of respiratory epithelial cells, an observation that is especially relevant because an intracellular reservoir of M. catarrhalis is present in the human respiratory tract and this reservoir is important for persistence. The znu knockout mutant showed marked impairment in its capacity to persist in the respiratory tract compared to the wild type in a mouse pulmonary clearance model. We conclude that the zinc uptake ABC transporter mediates uptake of zinc in environments with very low zinc concentrations and is critical for full virulence of M. catarrhalis in the respiratory tract in facilitating intracellular invasion of epithelial cells and persistence in the respiratory tract.

Modeling the spread of infectious disease using genetic information within a marked branching process.

Accurate assessment of disease dynamics requires a quantification of many unknown parameters governing disease transmission processes. While infection control strategies within hospital settings are stringent, some disease will be propagated due to human interactions (patient-to-patient or patient-to-caregiver-to-patient). In order to understand infectious transmission rates within the hospital, it is necessary to isolate the amount of disease that is endemic to the outside environment. While discerning the origins of disease is difficult when using ordinary spatio-temporal data (locations and time of disease detection), genotypes that are common to pathogens, with common sources, aid in distinguishing nosocomial infections from independent arrivals of the disease. The purpose of this study was to demonstrate a Bayesian modeling procedure for identifying nosocomial infections, and quantify the rate of these transmissions. We will demonstrate our method using a 10-year history of Morexella catarhallis. Results will show the degree to which pathogen-specific, genotypic information impacts inferences about the nosocomial rate of infection.