Nasopharyngeal colonization by pathogenic bacteria: effect of polymorphisms in innate immune genes of young children

Nasopharyngeal bacteria can asymptomatically colonize the nasopharynx of infants and young children but are also associated with the development of respiratory infections and diseases. Such nasopharyngeal bacteria include Streptococcus pneumoniae, Moraxella catarrhalis, Haemophilus influenzae and Staphylococcus aureus. The host defense against invading pathogens is largely relies germline-encoded pattern recognition receptors (PRR), which are expressed on the cells of innate immunity, and different cytokines. These include toll-like receptors (TLR), mannose-binding lectin (MBL) and different cytokines such as IL-17A. Single nucleotide polymorphisms (SNP) in these receptors and cytokines have been reported. The aim of this study was to investigate genetic polymorphisms in the genes for TLR2, 3 and 4, MBL as well as for IL-17A and their associations with nasopharyngeal pathogenic bacterial colonization during a two-year follow-up. The study revealed that polymorphisms in TLRs, MBL2 and IL17A are associated with the nasopharyngeal bacterial colonization in young children. Healthy young (2.6 months of age) children with variant types of MBL2, TLR2 R753Q or TLR4 D299G had an increased risk to be colonized by S. pneumonia, S. aureus or M. catarrhalis, respectively. Moreover, variant types of MBL2 in healthy children with might facilitate human rhinovirus (HRV)-induced S. pneumoniae colonization at 2.6 months of age. The polymorphism of TLR4 D299G was shown to be associated with M. catarrhalis colonization throughout the whole two-year follow-up (2.6, 13 and 24 months of age) and also with the bacterial load of this pathogen. Also, the polymorphism of IL17A G152A was shown to be associated with increased risk to be colonized by S. pneumoniae at 13 and 24 months of age. Furthermore, the results suggest that IL17A G152A has an effect on production of serum IL-17A already at young age. In conclusion, the results of this study indicate that polymorphisms in the key PRRs and IL17A seem to play an important role to colonization of S. pneumoniae, M. catarrhalis, and S. aureus in healthy young Finnish children. The nasopharyngeal colonization by these pathogenic bacteria may further promote the development of respiratory infections and may be related to development of asthma and allergy in the later life of children. These findings offer a possible explanation why some children have more respiratory infections than other children and provide a rational basis for future studies in this field.Luontaista immuniteettiä ohjaavien geenien vaihtelevuuden vaikutus tauteja aiheuttavien bakteereiden asustamiseen nuorten lasten nenänieluissa Turun yliopisto, Lääketieteellinen tiedekunta, Lastentautioppi; Turun yliopistollinen keskussairaala, Turun yliopiston kliininen tohtoriohjelma (TKT); Tartuntatautiseurannan ja – torjunnan osasto, Terveyden ja hyvinvoinnin laitos, Turku Annales Universitatis Turkuensis, Medica – Odontologica, Painosalama Oy, Turku, Suomi 2015 Nenänielu on erittäin monimuotoinen ekosysteemi, joka sisältää useita erilaisia bakteereja. Monet näistä bakteereista asustavat oireita aiheuttamatta nuorten lasten nenänielussa, mutta ne voivat usein aiheuttaa myös hengitystieinfektioita ja sairauksia. Yleisimmät taudinaiheuttajabakteerit nenänielussa lapsilla ovat Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis ja Staphylococcus aureus. Luontaisen immuniteetin reseptorit, jotka ilmentyvät luontaisen immuniteetin solujen pinnalla, kontrolloivat elimistön puolustusta bakteereja vastaan. Tällaisia molekyylejä ovat muun muassa Toll-proteiinin kaltaiset reseptorit (TLR), mannoosia sitova lektiini (MBL) ja erilaiset sytokiinit, kuten IL-17A. Useita erilaisia polymorfismeja eli mutaatioita on tunnistettu geeneissä, jotka koodittavat luontaisen immuniteetin reseptoreita ja sytokiinejä. Tämän väitöskirjatyön tarkoituksena oli tutkia luontaista immuniteettiä ohjaavien geenien vaihtelevuuden vaikutusta tauteja aiheuttavien bakteereiden asustamiseen terveiden suomalaisten lasten nenänieluissa lasten kahden ensimmäisen elinvuoden aikana. Tehty tutkimus osoitti, että TLR:ien, MBL2:n ja IL17A:n geneettiset polymorfismit vaikuttavat nuorten lasten nenänieluissa asustaviin bakteereihin. Terveillä 2.6 kuukauden ikäisillä lapsilla, joilla todettiin polymorfismeja MBL2:ssä, sekä polymorfismit TLR2 R753Q ja TLR4 D299G, oli suurempi riski kantaa S. pneumonia, S. aureus ja M. catarrhalis bakteereita nenänielussa, tässä järjestyksessä. Sen lisäksi tutkimuksessa havaittiin, että 2.6 kk ikäisillä lapsilla polymorfismit MBL2:ssa saattavat johtaa rinoviruksen indusoimaan S. pneumoniae nenänieluasustamiseen. Noin kahden vuoden seurannan aikana (2.6kk-24kk) huomattiin TLR4 D299G polymorfismin olevan mahdollisesti yhteydessä nenänielun kolonisoitumiseen M. catarrhalis bakteereilla ja mahdollisesti myös M. catarrhalis bakteerien kantajuuteen nenänielussa. Lisäksi tutkimus osoitti, että 13 ja 24 kuukauden ikäisillä lapsilla IL17A G152A polymorfismi oli yhteydessä nenänielun kolonisoitumiseen S. pneumoniae bakteereilla ja että IL-17A G152A polymorfismilla oli vaikutus IL-17A sytokiinin seerumipitoisuuteen. Johtopäätöksenä voidaan todeta tutkimuksessa saatujen tulosten viittaavan siihen, että luontaisen immuniteetin reseptoreiden ja sytokiinien polymorfismeilla on mahdollisesti yhteyttä terveiden nuorten suomalaisten lasten nenänielujen kolonisoitumiseen S. pneumoniae, M. catarrhalis ja S. aureus bakteereilla. Tästä voi lasten myöhemmässä elä- mässä olla seurauksena hengitystieinfektioiden lisääntyminen ja toisaalta se voi myös nostaa astman tai allergian kehittymisen riskiä. Tutkimuksessa havaitut polymorfismien ja nenänieluasustamisen mahdolliset yhteydet voivat antaa selityksen sille, minkä takia jotkut lapset saattavat sairastua hengitystieinfektioihin useammin kuin toiset lapset.Siirretty Doriast

TLR4Polymorphism, 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.TLR4polymorphism 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 betweenTLR4genotype, bacterial colonization, and asthma were analyzed. Children with TLR4 AG or GG genotype were more often colonized withMoraxella catarrhalisat 2 months of age (p= 0.009) andHaemophilus influenzaeat 13 months of age (p= 0.018). Children who were colonized withH. influenzaeat 13 months of age had a significantly higher risk of later development of asthma (p= 0.004).M. catarrhalisorH. Influenzaecolonization at 2 months of age orTLR4genotype Asp299Gly were not associated with the development of childhood asthma.TLR4Asp299Gly polymorphism was associated with an increased risk of colonization ofM. catarrhalisandH. influenzaein children. The colonization withH. influenzaeat 13 months of age was associated with a higher risk of later development of childhood asthma

Gene Polymorphism of Toll-Like Receptors and Lung Function at Five to Seven Years of Age after Infant Bronchiolitis

Toll-like receptors (TLR) play a crucial role in innate immunity, protecting the host from pathogens such as viruses. Genetic variations in TLRs have been associated with the severity of viral bronchiolitis in infancy and with the later occurrence of post-bronchiolitis asthma. The aim of the present study was to evaluate if there are any exploratory associations between TLR gene polymorphisms and lung function at 5 to 7 years of age in former bronchiolitis patients. METHODS: We performed impulse oscillometry (IOS) at the median age of 6.3 years for 103 children who had been hospitalized for bronchiolitis at less than six months of age. The main parameters evaluated were airway resistance and reactance at 5Hz in baseline and post-exercise measurements. Data on single nucleotide polymorphisms (SNP) of TLR1 rs5743618, TLR2 rs5743708, TLR6 rs5743810 and TLR10 rs4129009 (TLR2 subfamily) and TLR3 rs3775291, TLR4 rs4986790, TLR7 rs179008, TLR8 rs2407992 and TLR 9 rs187084 were available for analyses. RESULTS: The TLR4 rs4986790 wild genotype A/A was associated with a greater Rrs5 response (0.72 vs. -0.42, p = 0.03) to exercise. In TLR6 rs5743810, the minor allele T was associated with greater Rrs5 response (0.80 vs. -0.03, p = 0.04) to exercise. In TLR7 rs179008, the major allele A was associated with baseline decline in dRrs/df (-1.03 vs 0.61, p = 0.01) and increased Fres (2.28 vs. 0.89, p = 0.01) in girls. CONCLUSION: Among the nine studied TLRs, only TLR7 rs179008 showed some exploratory associations with post-bronchiolitis lung function deficiency, and polymorphisms of TLR4 rs4986790, and TLR6 rs5743810 in particular, with airway reactivity. These findings call for further confirmatory studies.Public Library of Science open acces

Pulmonary environmental cues drive group 2 innate lymphoid cell dynamics in mice and humans

Group 2 innate lymphoid cells (ILC2s) are enriched in mucosal tissues (e.g., lung) and respond to epithelial cell–derived cytokines initiating type 2 inflammation. During inflammation, ILC2 numbers are increased in the lung. However, the mechanisms controlling ILC2 trafficking and motility within inflamed lungs remain unclear and are crucial for understanding ILC2 function in pulmonary immunity. Using several approaches, including lung intravital microscopy, we demonstrate that pulmonary ILC2s are highly dynamic, exhibit amoeboid-like movement, and aggregate in the lung peribronchial and perivascular spaces. They express distinct chemokine receptors, including CCR8, and actively home to CCL8 deposits located around the airway epithelium. Within lung tissue, ILC2s were particularly motile in extracellular matrix–enriched regions. We show that collagen-I drives ILC2 to markedly change their morphology by remodeling their actin cytoskeleton to promote environmental exploration critical for regulating eosinophilic inflammation. Our study provides previously unappreciated insights into ILC2 migratory patterns during inflammation and highlights the importance of environmental guidance cues in the lung in controlling ILC2 dynamics

Haplotype of the Interleukin 17A gene is associated with osteitis after Bacillus Calmette-Guerin vaccination

Bacillus Calmette-Guerin (BCG) osteitis was more common in Finland than elsewhere at the time when universal BCG vaccinations were given to Finnish newborns. There is evidence that IL-17 plays a role in the defense against tuberculosis. The aim of this study was to evaluate the associations of IL17A rs4711998, IL17A rs8193036 and IL17A rs2275913 single-nucleotide polymorphisms (SNPs) with the risk of BCG osteitis after newborn vaccination. IL17A rs4711998, rs8193036 and rs2275913 SNPs were determined in 131 adults had presented with BCG osteitis after newborn BCG vaccination. We analyzed, using the HaploView and PLINK programs, whether allele or haplotype frequencies of these SNPs differ between the former BCG osteitis patients and Finnish population controls. Of the three IL17A SNPs studied, rs4711998 associated nominally with BCG osteitis; minor allele frequency was 0.215 in 130 BCG osteitis cases and 0.298 in 99 controls (p = 0.034). Frequency of the second common haplotype (GTA) differed significantly between BCG osteitis cases and controls (0.296 vs. 0.184, p = 0.040 after multi-testing correction). The GTA haplotype of the IL17A SNPs rs4711998, rs8193036 and rs2275913 was associated with osteitis after BCG vaccination

IL-10 Gene Polymorphisms Are Associated with Post-Bronchiolitis Lung Function Abnormalities at Six Years of Age

Aim Interleukin-10 (IL-10) has been associated with wheezing and asthma in children and the genetic variation of the IL-10 cytokine production may be linked to post-bronchiolitis lung function. We used impulse oscillometry (IOS) to evaluate the associations of IL10 polymorphisms with lung function at a median age of 6.3 years in children hospitalised for bronchiolitis before six months of age. Methods We performed baseline and post-exercise IOS on 103 former bronchiolitis patients. Data on single nucleotide polymorphisms (SNP) of IL10 rs1800896 (–1082G/A), rs1800871 (–819C/T), rs1800872 (–592C/A) were available for 99 children and of IL10 rs1800890 (–3575T/A) for 98 children. Results IL10 rs1800896, rs1800871 and rs1800872 combined genotype AA+CT+CA and carriage of haplotype ATA, respectively, were associated with higher resistance and lower reactance in baseline IOS in adjusted analyses. At IL10 rs1800890, the A/A-genotype and carriers of A-allele were associated with lower reactance in baseline IOS. There were no significant associations between the studied SNPs and airway hyper-reactivity to exercise. Conclusion Low-IL-10-producing polymorphisms in the IL-10 encoding gene were associated with obstructive lung function parameters, suggesting an important role for IL-10 in development of lung function deficit in early bronchiolitis patients.Public Library of Science open acces

Neutrophils restrain allergic airway inflammation by limiting ILC2 function and monocyte-dendritic cell antigen presentation

Neutrophil mobilization, recruitment, and clearance must be tightly regulated as overexuberant neutrophilic inflammation is implicated in the pathology of chronic diseases, including asthma. Efforts to target neutrophils therapeutically have failed to consider their pleiotropic functions and the implications of disrupting fundamental regulatory pathways that govern their turnover during homeostasis and inflammation. Using the house dust mite (HDM) model of allergic airway disease, we demonstrate that neutrophil depletion unexpectedly resulted in exacerbated T helper 2 (T 2) inflammation, epithelial remodeling, and airway resistance. Mechanistically, this was attributable to a marked increase in systemic granulocyte colony-stimulating factor (G-CSF) concentrations, which are ordinarily negatively regulated in the periphery by transmigrated lung neutrophils. Intriguingly, we found that increased G-CSF augmented allergic sensitization in HDM-exposed animals by directly acting on airway type 2 innate lymphoid cells (ILC2s) to elicit cytokine production. Moreover, increased systemic G-CSF promoted expansion of bone marrow monocyte progenitor populations, which resulted in enhanced antigen presentation by an augmented peripheral monocyte-derived dendritic cell pool. By modeling the effects of neutrophil depletion, our studies have uncovered previously unappreciated roles for G-CSF in modulating ILC2 function and antigen presentation. More broadly, they highlight an unexpected regulatory role for neutrophils in limiting T 2 allergic airway inflammation

The glucose transporter 2 regulates CD8⁺ T cell function via environment sensing

T cell activation is associated with a profound and rapid metabolic response to meet increased energy demands for cell division, differentiation and development of effector function. Glucose uptake and engagement of the glycolytic pathway are major checkpoints for this event. Here we show that the low-affinity, concentration-dependent glucose transporter 2 (Glut2) regulates the development of CD8+ T cell effector responses in mice by promoting glucose uptake, glycolysis and glucose storage. Expression of Glut2 is modulated by environmental factors including glucose and oxygen availability and extracellular acidification. Glut2 is highly expressed by circulating, recently primed T cells, allowing efficient glucose uptake and storage. In glucose-deprived inflammatory environments, Glut2 becomes downregulated, thus preventing passive loss of intracellular glucose. Mechanistically, Glut2 expression is regulated by a combination of molecular interactions involving hypoxia-inducible factor-1 alpha, galectin-9 and stomatin. Finally, we show that human T cells also rely on this glucose transporter, thus providing a potential target for therapeutic immunomodulation

Nasopharyngeal Bacterial Colonization and Gene Polymorphisms of Mannose-Binding Lectin and Toll-Like Receptors 2 and 4 in Infants

BACKGROUND: Human nasopharynx is often colonized by potentially pathogenic bacteria. Gene polymorphisms in mannose-binding lectin (MBL), toll-like receptor (TLR) 2 and TLR4 have been reported. The present study aimed to investigate possible association between nasopharyngeal bacterial colonization and gene polymorphisms of MBL, TLR2 and TLR4 in healthy infants. METHODOLOGY/PRINCIPAL FINDINGS: From August 2008 to June 2010, 489 nasopharyngeal swabs and 412 blood samples were taken from 3-month-old healthy Finnish infants. Semi-quantitative culture was performed and pyrosequencing was used for detection of polymorphisms in MBL structural gene at codons 52, 54, and 57, TLR2 Arg753Gln and TLR4 Asp299Gly. Fifty-nine percent of subjects were culture positive for at least one of the four species: 11% for Streptococcus pneumoniae, 23% for Moraxella catarrhalis, 1% for Haemophilus influenzae and 25% for Staphylococcus aureus. Thirty-two percent of subjects had variant types in MBL, 5% had polymorphism of TLR2, and 18% had polymorphism of TLR4. Colonization rates of S. pneumoniae and S. aureus were significantly higher in infants with variant types of MBL than those with wild type (p = .011 and p = .024). Colonization rates of S. aureus and M. catarrhalis were significantly higher in infants with polymorphisms of TLR2 and of TLR4 than those without (p = .027 and p = .002). CONCLUSIONS: Our study suggests that there is an association between nasopharyngeal bacterial colonization and genetic variation of MBL, TLR2 and TLR4 in young infants. This finding supports a role for these genetic variations in susceptibility of children to respiratory infections