An Overview of Adenoid Microbiome Using 16S rRNA Gene Sequencing-Based Metagenomic Analysis.

Background and Objectives: the upper respiratory tract harbors the highest bacterial density in the whole respiratory system. Adenoids, which are located in the nasopharynx, are a major site of bacterial colonies in the upper airways. Our goal was to use culture-independent molecular techniques to identify the breadth of bacterial diversity in the adenoid vegetations of children suffering from chronic rhinosinusitis and obstructive sleep apnea. Materials and methods: in total, 21 adenoid samples were investigated using amplification and sequencing of the V3-V4 hypervariable region of the bacterial 16S rRNA gene. Results: among the most common bacterial species found were Veillonella atypica, Fusobactrium nucelatum, Shaalia odontolytica, and Moraxella catarrhalis. Veillonella atypica and Fusbacteriumnucelatum dominated the microbiome in all 21 samples, attributing to more than 60% of all detected genetic material. Conclusions: since both Veillonella atypica and Fusobacterium nucleatum are, predominantly, oral cavity and dental microorganisms, our findings may suggest oral microbiome migration deeper into the oropharynx and nasopharynx where these bacteria colonize adenoid vegetations.

Profiling of heat shock proteins 27 and 70 in adenoids of children.

PURPOSE: Heat shock protein (HSP)27 and 70 are molecular chaperones that may have immunomodulatory functions. We determined if and at what levels each are expressed in the adenoids of pediatric subjects. We also examined tissue distributions, associated clinical characteristics, and antibacterial effects. METHODS: Western blot, enzyme-linked immunosorbent assay (ELISA), and immunohistochemistry were applied to adenoidal tissues and lavage fluids obtained from children (N = 40) undergoing adenotonsillectomy. RESULTS: Via western blot and ELISA, both HSP27 and 70 were regularly detected in adenoidal tissue and in lavage fluid samples. HSP27 was highly expressed in epithelium, whereas HSP70 showed strong subepithelial positivity and bore a significant relation to adenoidal size. Assayed levels of HSP27 and 70 correlated inversely, and their addition to culture media independently increased bacterial numbers (Staphylococcus aureus). Upon the precipitation of each from adenoidal lavage fluids, bacterial counts declined. CONCLUSIONS: HSP27 and 70 are readily expressed in the adenoids of children and may be implicated in immunologic responses.

Histology, histochemistry and ultrastructure of the nasopharyngeal tonsil of the buffalo (Bubalus bubalis).

The light microscopic appearance and ultrastructure of the nasopharyngeal tonsil (tonsilla pharyngea), collected from 12 adult buffaloes of local mixed breed, were explored for the distribution of different types of epithelia, lymphoid tissue and high endothelial venules. The tonsillar mucosa was lined by pseudostratified columnar ciliated epithelium having goblet cells. The respiratory epithelium associated with the underlying lymphoid tissue formed the lymphoepithelium. The epithelium was further modified into follicle-associated epithelium (FAE) characterized by reduced epithelial height, presence of a few dome-shaped cuboidal cells equivalent of the M-cells and absence of goblet and ciliated cells. The lymphoid tissue was distributed in the form of isolated lymphoid cells, diffuse lymphoid tissue and lymphoid follicles, mainly distributed within the propria-submucosa along with the sero-mucous glandular tissue. The goblet cells of the respiratory epithelium and the acinar cells contained different mucopolysaccharides. Scanning electron microscopy of the surface mucosa demonstrated a dense mat of cilia, island-like arrangement of microvillus cells, M-cells and a few brush-like cells. The transmission electron microscopy revealed the different cell organelles of the respiratory epithelium and the FAE. Lymphocyte migration via the high endothelial venules in the propria-submucosa was also observed.

[Expression of CysLTR-1 and CysLTR-2 in adenoid tissues from children with adenoid hypertrophy].

OBJECTIVE: To examine the expression of cysteinyl leukotriene receptor-1 (CysLTR-1) and cysteinyl leukotriene receptor-2 (CysLTR-2) in the adenoid tissues from children with adenoid hypertrophy (AH) and to explore the role of leukotrienes in the pathogenesis of AH. METHODS: Sixty children with AH who were treated by adenoidectomy and/or tonsillectomy were classified into two groups: simple AH and AH plus allergic rhinitis (n=30 each). Twenty children who underwent tonsillectomy due to recurrent purulent tonsillitis were selected as the control group. The expression of CysLTR-1 and CysLTR-2 in the excised tonsil and/or adenoid tissues was determined by immunofluorescence histochemical labeling and integrated optical density measurement. RESULTS: The expression of CysLTR-1 and CysLTR-2 in the adenoid and tonsil tissues increased significantly in both the simple AH group and AH plus allergic rhinitis group compared with the control group (P<0.01). The expression of CysLTR-1 and CysLTR-2 in the AH plus allergic rhinitis group increased more significantly compared with the simple AH group (P<0.01). CONCLUSIONS: CysLTR-1 and CysLTR-2 are highly expressed in the adenoid tissues from children with AH, suggesting that leukotrienes are involved in the pathogenesis of AH.

Beryllium concentration in pharyngeal tonsils in children.

Power plant dust is believed to be the main source of the increased presence of the element beryllium in the environment which has been detected in the atmospheric air, surface waters, groundwater, soil, food, and cigarette smoke. In humans, beryllium absorption occurs mainly via the respiratory system. The pharyngeal tonsils are located on the roof of the nasopharynx and are in direct contact with dust particles in inhaled air. As a result, the concentration levels of beryllium in the pharyngeal tonsils are likely to be a good indicator of concentration levels in the air. The presented study had two primary aims: to investigate the beryllium concentration in pharyngeal tonsils in children living in southern Poland, and the appropriate reference range for this element in children's pharyngeal tonsils. Pharyngeal tonsils were extracted from a total of 379 children (age 2-17 years, mean 6.2 ± 2.7 years) living in southern Poland. Tonsil samples were mineralized in a closed cycle in a pressure mineralizer PDS 6, using 65% spectrally pure nitric acid. Beryllium concentration was determined using the ICP-AES method with a Perkin Elmer Optima 5300DVTM. The software Statistica v. 9 was used for the statistical analysis. It was found that girls had a significantly greater beryllium concentration in their pharyngeal tonsils than boys. Beryllium concentration varies greatly, mostly according to the place of residence. Based on the study results, the reference value for beryllium in pharyngeal tonsils of children is recommended to be determined at 0.02-0.04 µg/g.

Role of pepsin and pepsinogen: linking laryngopharyngeal reflux with otitis media with effusion in children.

OBJECTIVES/HYPOTHESIS: To analyze the relationship between laryngopharyngeal reflux (LPR) represented by pepsin and pepsinogen, and pathogenesis of otitis media with effusion (OME). STUDY DESIGN: Prospective case-control study. METHODS: Children with OME who required adenoidectomy and tympanostomy/tympanostomy tubes placement were enrolled in OME group, whereas children with adenoid hypertrophy (AH) who required adenoidectomy and individuals who required cochlear implantation (CI) were enrolled in AH and CI groups, respectively. Pepsinogen mRNA and protein levels were assessed by real-time fluorescence-based quantitative polymerase chain reaction and immunohistochemistry in adenoid specimens from the OME and AH groups. Pepsin and pepsinogen concentrations were evaluated by enzyme-linked immunosorbent assay in middle ear fluid and plasma from the OME and CI groups. RESULTS: The levels of pepsinogen protein expressed in cytoplasm of epithelial cells and clearance under epithelial cells in adenoid specimens from the OME group were significantly higher than those in the AH group. Furthermore, the concentrations of pepsin and pepsinogen in the OME group were 51.93±11.58 ng/mL and 728±342.6 ng/mL, respectively, which were significantly higher than those in the CI group (P<.001). In addition, the concentrations of pepsin in dry ears were significantly lower than those in serous and mucus ears in the OME group (F=22.77, P<.001).Finally, the concentration of pepsinogen in middle ear effusion was positively correlated with the expression intensity of pepsinogen protein in cytoplasm of epithelial cells (r=0.73, P<.05) in the OME group. CONCLUSIONS: Pepsin and pepsinogen in middle ear effusion are probably caused by LPR and may be involved in the pathogenesis of OME. LEVEL OF EVIDENCE: 3b.

Genetic and functional evidence for a role for SLC11A1 in susceptibility to otitis media in early childhood in a Western Australian population.

Otitis media (OM) is a common disease in early childhood characterised by inflammation of the middle ear. Susceptibility to recurrent acute OM (rAOM; ≥3 episodes AOM in 6 months) and chronic OM with effusion (COME; middle ear effusion ≥3 months) is 40-70% heritable. Three bacterial pathogens commonly associated with OM, Streptococcus pneumoniae (Sp), non-typeable Haemophilus influenzae (NTHi) and Moraxella catarrhalis (Mc), have been observed within adenoids and as facultative intracellular pathogens that invade and survive in mononuclear cells. Case/pseudo-control conditional logistic regression analysis of variants in the SLC11A1 gene, initially identified for its role in resistance to intra-macrophage pathogens in mice, revealed association with OM at four polymorphisms (Pbest=0.025) in 531 families (660 affected children) from the Western Australian Family Study of Otitis Media. This included association at the functional promoter GTn polymorphism (rs34448891) with alleles that regulate high (allele 3; odds ratio=1.2, 95% CI 1.00-1.44, P=0.04) versus low (allele 2; odds ratio=0.83, 95% CI 0.69-0.99, P=0.04) SLC11A1 expression. Haplotype and stepwise conditional logistic regression analyses support a single genetic effect in the proximal region of SLC11A1, with the haplotype 3_C_C_G across rs34448891_rs2276631_rs3731865_rs2695343 significantly (P=0.008) over-transmitted to affected offspring. Stratified analysis showed no association with OM in children who had undergone adenoidectomy (296 children), whereas children with adenoids intact (364 children) showed improved significance at the GTn polymorphism (allele 3: odds ratio=1.38, 95% CI=1.10-1.75, P=0.006). Quantitative RT/PCR demonstrated high expression of SLC11A1 in mononuclear cells isolated from adenoid tissue, with a trend for decreased expression with increasing copies of GTn allele 2. Expression of SLC11A1 was enhanced at 12 (P=1.2×10(-3)) and 24h (P<1.0×10(-4)) after infection of Mono-Mac-6 cells with NTHi. This study identifies SLC11A1 as a novel candidate for OM susceptibility, particularly in children with adenoids intact. Further analysis in other cohorts is required to validate these observations.

Short communication: preferential concentration of hydroxychloroquine in adenoid tissue of HIV-infected subjects.

Hydroxychloroquine (HCQ) anti-HIV activity is well documented. To evaluate its distribution in lymphoid tissues, which are considered sanctuaries of HIV reservoirs and targets of early massive depletion of CD4(+) T cells, we assessed HCQ concentrations in adenoid tissue and plasma of HIV-infected subjects. A daily oral dose of 400 or 800 mg of HCQ was administered to eight HIV-infected subjects for 8 days. HCQ concentrations were measured in plasma and adenoid tissue by high-performance liquid chromatography. Mean concentrations of HCQ in adenoid tissue of subjects treated with 400 and 800 mg were 87,210 +/- 17,817 and 167,472 +/- 93,793 ng/g, respectively. In plasma, these values corresponded to 329 +/- 133 and 278 +/- 68 ng/g, respectively. HCQ concentrations were significantly higher in adenoid tissue than in plasma in both groups. The potential use of HCQ as adjuvant in the therapy of HIV deserves to be explored, as the drug accumulates in relevant tissues for HIV replication and immunopathogenesis.

[Effect of passive smoking on the occurrence of Cu and Ca in the tonsils of children with an area of Tychy]. / Wplyw biernego palenia na wystepowanie Cu i Ca w migdalkach dzieci z obszaru miasta Tychy.

In this paper the results of concentration of Cu and Ca in pharyngeal tonsils from children exposed and unexposed to tobacco smoke. Concentration of Ca and Cu determination of ICP-AES method with the apparatus Solaar M6 (PJA Solutions). Geometric mean of content of Cu in pharyngeal tonsils girls and boys exposure and unexposure to tobacco smoking was in similar level--2.69-2.99 microg/g. Concentration of Ca in investigated samples was higher in pharyngeal tonsils from children unexposure to tobacco (boys about 200 microg/g, girls about 30 microg/g) in comparison to children exposure to tobacco smoking. In our study was presented cross-correlation analysis between Cu and Ca and other elements and Cluster Analysis.

[Changing the contents of Fe and Mn in the tonsils of children exposed to passive smoking and their local imission example Chorzow]. / Zmiana zawartosci Fe i Mn w migdalkach dzieci narazonych na bierne palenie i ich lokalna imisje na przykladzie Chorzowa.

The subject of the research were samples of overgrown adenoids removed by adenoidectomy 56 children, including 30 boys and 26 girls, exposure and unexposure from passive smoking, living in the administrative area of Chorzów. The statistic characteristic of Fe and Mn occurrence is presented in the thesis. The studies were carried out on the changes of Fe and Mn and other elements, (B, Al, La, Cd, Co, Cr, Cu, Ni, Pb, Zn, As, Se, Hg, V, Be, Mo, Sn, V, Ti, Sb, Bi, TI, Zr, Ca, Mg, Na, Ba, Sr, Li) respectively. The elemental composition of adenoids was determined with ICP-AES method (Inductively Coupled Plasma - Atomic Emission Spectroscopy). The studies on Fe and Mn occurrence in adenoids showed the presence of its higher concentrations in exposure boys (Fe - 116.13 microg/g; Mn - 0.70 microg/g), in comparison with exposure girls from passive smoking (93.06 microg/g; Mn - 0.57 microg/g).

[Influence of age in content of trace elements in pharyngeal tonsils from exposure and unexposure children]. / Rola wieku w ksztaltowaniu sie obecnosci pierwiastków fizjologicznych w migdalakch gardlowych dzieci w aspekcie biernego palenia.

This project is aimed to estimate the effect of passive smoke on the levels of selected trace elements (Ca, Mg, K, Na) in pharyngeal tonsils of children in several group of age (2-5 years, 6-9 years, 10-15 years). This trace elements were determined using ICP-AES method. It was concluded that the exposure to the cigarette smoke in pharyngeal tonsils is a factor producing the changes in the levels of essential elements: geometric mean of Ca was the highest in pharyngeal tonsils of children in 10-15 years old unexposure to ETS (410 microg/g). The least level of Ca - 281 microg/g was observed in this samples in the same group of age, but in children exposure by ETS. High levels of K was observed in pharyngeal tonsils of children exposure to passive smoking in all of group of age to comparison to unexposure by ETS. The greatest content - 27479 microg/g was in pharyngeal tonsils in exposure to ETS in 6-9 years old was observed, but the least - 16478 microg/g in 10-15 years old. Change of content of Mg was from 764 to 784 microg/g in samples from children exposure by ETS to comparison 720-744 microg/g in children unexposure by ETS. High level of Na was observed in pharyngeal tonsils from children exposure to ETS in all of group of age to comparison to unexposure. This study showed that the kind of interaction dependent on age and exposed by ETS. The changes of given elements were different for children passive smoking and no passive smoking in several group of age.

[Trace elements concentration in pharyngeal tonsils from exposed and unexposed to ETS children in refer to sex and places of living]. / Wplyw biernego palenia na zawartosc pierwiastków fizjologicznych w migdalkach gardlowych w nawiazaniu do plci i miejsca zamieszkania.

The aim of this study was investigation influence sex and place living (industrial region or village) to concentration of: Ca, K, Mg and Na in pharyngeal tonsils (n = 84) from children exposed and unexposed to tobacco smoke and analysis kind of interactions between trace elements. Determination of these elements contents were performed by ICP-AES. It was found higher concentrations of Ca and Na in pharyngeal tonsils from boys (389 microg//g) and girls (356 microg/g) unexposed to tobacco smoke to comparison to expose to ETS boys (304 microg/g) and girls (298 microg/g). Higher concentrations of Ca and Na was found in this samples from children unexposed on ETS, living in industrial area to comparison to unexposed to ETS children living in village region. Higher concentration of K and Mg was found in exposed to ETS girls and boys in comparison to unexposed to ETS children, and higher level of these metals were found in exposed to tobacco smoke children living in industrial region and village.

[Accumulation of Cu in pharyngeal tonsils from children exposed and unexposed to smoke of tobacco]. / Kumulacja Cu w migdalkach gardlowych dzieci narazonych i nienarazonych na dzialanie dymu tytoniowego.

The characteristic of occurrence Cu content in pharyngeal tonsils from girls and boys exposed to tobacco smoke and unexposed to tobacco smoke living in Southern Poland is presented in this article. Analysis of content of Cu in pharyngeal tonsils was observed in eight groups of children: girls exposed to tobacco smoke and unexposed to tobacco smoke living in industrial region and village, boys exposed to tobacco smoke and unexposed to tobacco smoke living in industrial region and village. Geometric mean of contents of copper in pharyngeal tonsils from girls exposed to ETS living in industrial region was 1.35 microg/g and no exposed girls was 1.31 microg/g, in girls exposed to ETS living in village region was 0.72 microg/g and no exposed to ETS girls was 0.66 microg/g. Geometric mean of contents of copper in pharyngeal tonsils from boys exposed to ETS living in industrial region was 1.76 microg/g and no exposed to ETS boys was 1.10 microg/g, in boys exposed to ETS living in village region was 0.71 microg/g and no exposed girls was 0.30 microg/g and this differences was statistically important. The cross-correlation analysis between content of Cu and other metals Ba, Ca, Cr, Al, Fe, Mg, Mn, Zn, K, Na in eight groups of children was observed.

[Co-occurrence Fe in relationships to other metals in pharyngeal tonsil of children in view of sex, age and expose to passive smoking]. / Wspólwystepowanie Fe z innymi metalami w migdalkach gardlowych dzieci ze wzgledu na plec, wiek i narazenie na dym tytoniowy.

The aim of this study was analysis of kind of interactions between Fe and the other metals: Al, Ba, Ca, Cr, Cu, Mg, Mn, Zn, K i Na in pharyngeal tonsils from girls and boys in several group of age (2-5 years, 6-9 years and 10-15 years) exposed and no exposed to tobacco smoking. This study showed that the kind of interaction dependent on sex, age and exposed to ETS.

The Bak protein expression in germinal centers of hypertrophied adenoids in children.

The aim of this study was to evaluate pro-apoptotic Bak expression in the germinal centers of adenoid in children on the assumption of the potential usefulness of Bak as adenoid function marker. The study involved 95 children undergoing adenoidectomy; divided into three age groups: aged up to 5 years (25 children), 5-10 years (54 children) and over 10 years (16 children). The analyzed material was adenoids removed on the ground of hypertrophy. Immunohistochemical analyses were carried out using goat polyclonal Bak antibodies (DAKO) directed against human Bak protein. The presence of Bak positive lymphocytes within germinal centers and Bak immunostaining were scored. The immunohistochemical staining showed the Bak positive lymphocytes mainly within the germinal centers of the lymphoid follicles. The Bak reactivity was also present in hyperplastic lymphoid tissue within the subepithelial B lymphocytes. We have not found statistically significant correlation between Bak expression and clinical status and change in Bak expression level according to age. The apoptotic presence within the germinal centers are the manifestation of which is Bak expression and its lack in the mantle zone, what we confirmed in our former study by describing Bcl-2 expression, seems to be a proper B cells maturation marker within lymphoid follicles. Our finding shows that these processes are not influenced by age and supports our thesis that adenoid involution is rather the effect of changes in the number of lymphoid follicles that changes in them.

Neurotrophins and tonsillar hypertrophy in children with obstructive sleep apnea.

Enlarged adenotonsillar tissue (AT) is a major determinant of obstructive sleep apnea (OSA) severity in children; however, mechanisms of AT proliferation are poorly understood. We hypothesized that early exposure to respiratory syncytial virus (RSV) may modify AT proliferation through up-regulation of nerve growth factor (NGF)-neurokinin 1 (NK1) receptor dependent pathways. AT harvested from 34 children with OSA and 25 children with recurrent tonsillitis (RI) were examined for mRNA expression of multiple growth factors and their receptors. In addition, NK1 receptor expression and location, and substance P tissue concentrations were compared in AT from OSA and RI children. NGF mRNA and its high-affinity tyrosine kinase receptor (trkA) expression were selectively increased in OSA (p<0.001). NK1 receptor mRNA and protein expression were also enhanced in OSA (p<0.01), and substance P concentrations in OSA patients were higher than in RI (p<0.0001). AT from OSA children exhibit distinct differences in the expression of NGF and trkA receptors, NK1 receptors, and substance P. The homology between these changes and those observed in the lower airways following RSV infection suggests that RSV may have induced neuro-immunomodulatory changes within AT, predisposing them to increased proliferation, and ultimately contribute to emergence of OSA.

Squamous metaplasia and BCL-6 in pediatric adenoid accompanied by otitis media with effusion.

PURPOSE: Deterioration of local immunity in the adenoids may make them vulnerable to infection by microorganisms, resulting in otitis media with effusion. To determine the factors associated with this condition, we evaluated adenoid size, mucosal barrier, squamous changes of ciliated epithelium, IgA secretion, and BCL-6 expression in adenoids. MATERIALS AND METHODS: Seventeen children diagnosed with otitis media with effusion (OME group) and 20 children without any history of OME (control group) were enrolled. Their adenoids were sized by lateral view X-ray and stained with hematoxylin and eosin to detect squamous metaplasia. The adenoids were also stained with cytokeratin to evaluate mucosal barriers, and with anti- IgA antibody and anti- BCL-6 antibody to determine expression of IgA and BCL-6. RESULTS: The OME group showed greater incidence of squamous metaplasia, fewer ciliated cells, and lower expression of BCL-6 (p < 0.05 each). Deterioration of the mucosal barrier was detected in the OME group (p > 0.05). IgA secretion and adenoid size were the same for the OME and the control groups. CONCLUSION: These results suggest that increased squamous metaplasia and lower BCL-6 expression in adenoids may be associated with increased susceptibility to OME.

[Influence of passive smoking on content of aluminium in pharyngeal tonsils from children living in Southern Poland]. / Wplyw biernego palenia na zawartosc glinu w migdalkach gardlowych dzieci zamieszkujacych rejony poludniowej Polski.

The characteristic of occurrence Al content in pharyngeal tonsils from girls and boys living in Southern Poland is presented in this article. Analysis of content of Al in pharyngeal tonsils was observed in four groups of children: girls exposed to tobacco smoke and unexposed to tobacco smoke, boys exposed to tobacco smoke and unexposed to tobacco smoke. Arithmetic mean of contents of aluminium in pharyngeal tonsils from exposed girls was 15.94+/-8.08 microg/g, in unexposed girls was 14.11+/-5.08 microg/g, in exposed to tobacco smoke boys--16.68+/-11.17 microg/g and unexposed boys 18.08+/-10.56 microg/g was observed. Differences between analysed groups of children were not statistically important. The cross-correlation analysis between content of Al and other metals Ba, Ca, Cr, Cu, Fe, Mg, Mn, Zn, K, Na showed repeating co-dependences between Al and Fe, Mg and Zn in pharyngeal tonsils from children exposed to tobacco smoke. In unexposed children was only one co-dependence between Al and Ca.

[Influence of environmental tobacco smoking on different barium contents in pharyngeal tonsils]. / Wplyw biernego palenia na zrónicowanie wystepowania baru w migdalkach gardlowych dzieci.

The aim of this study was analysis of content of barium in pharyngeal tonsils from children living on Southern Poland in during exposure on ETS. Barium contents in pharyngeal tonsils were higher for no exposure ETS children (0.099 microg/g) in comparison to exposure by ETS (0.033 microg/g), p=0.0042. The interaction between Ba and Ca, Fe, K or higher arithmetic and geometric mean, statistical range of changes contributed the role ETS in relation to children.

Squamous Metaplasia and BCL-6 in Pediatric Adenoid Accompanied by Otitis Media with Effusion

PURPOSE: Deterioration of local immunity in the adenoids may make them vulnerable to infection by microorganisms, resulting in otitis media with effusion. To determine the factors associated with this condition, we evaluated adenoid size, mucosal barrier, squamous changes of ciliated epithelium, IgA secretion, and BCL-6 expression in adenoids. MATERIALS AND METHODS: Seventeen children diagnosed with otitis media with effusion (OME group) and 20 children without any history of OME (control group) were enrolled. Their adenoids were sized by lateral view X-ray and stained with hematoxylin and eosin to detect squamous metaplasia. The adenoids were also stained with cytokeratin to evaluate mucosal barriers, and with anti- IgA antibody and anti- BCL-6 antibody to determine expression of IgA and BCL-6. RESULTS: The OME group showed greater incidence of squamous metaplasia, fewer ciliated cells, and lower expression of BCL-6 (p 0.05). IgA secretion and adenoid size were the same for the OME and the control groups. CONCLUSION: These results suggest that increased squamous metaplasia and lower BCL-6 expression in adenoids may be associated with increased susceptibility to OME.