Cysteinyl leukotriene receptors in tonsillar B- and T-lymphocytes from children with obstructive sleep apnea

Efficacy of montelukast for adenoid hypertrophy in paediatrics: A systematic review and meta-analysis

INTRODUCTION

Leukotrienes play a significant role in the pathogenesis of adenoid hypertrophy (A.H.). Therefore, we aimed to analyse the role of montelukast, a leukotriene receptor antagonist, alone or in combination with mometasone, a potent local intranasal steroid, for the treatment of A.H.

METHODS

Participants were children with A.H. were treated with montelukast alone or montelukast and mometasone furoate. The main outcome measures were effect of montelukast on clinical symptoms of A.H. A literature review was conducted using online search engines, Cochrane Library, PubMed, Web of Science and Scopus, for randomized clinical trials assessing children with A.H. treated with montelukast alone or montelukast and mometasone furoate. Seven randomized clinical trials (RCTs) were included with 742 children.

RESULTS

Our study reveals that montelukast alone or in combination with intranasal mometasone furoate significantly improves clinical symptoms of adenoid hypertrophy such as snoring, sleeping disturbance, mouth breathing and A/N ratio. Montelukast was superior to placebo in decreasing snoring (SMD = -1.00, 95% CI [-1.52, -0.49]), sleep discomfort (SMD = -1.26, 95% CI [-1.60, -0.93]), A/N ratio (MD = -0.11, 95% CI [-0.14, -0.09]) and mouth breathing (SMD = -1.36, 95% CI [-1.70, -1.02]). No difference was detected between montelukast and mometasone versus mometasone alone in snoring (SMD = -0.21, 95%CI [-0.69, 0.27]); however, the combination group was superior to the mometasone alone in mouth breathing (SMD = -0.46, 95% CI [-0.73, -0.19]).

CONCLUSIONS

The limitation of studies included a small sample size, with an overall low to medium quality. Thus, further larger, higher-quality RCTs are recommended to provide more substantial evidence.

The First-Line Approach in Children with Obstructive Sleep Apnea Syndrome (OSA)

Obstructive sleep apnea syndrome (OSA) is the main manifestation of sleep-disordered breathing in children. Untreated OSA can lead to a variety of complications and adverse consequences mainly due to intermittent hypoxemia. The pathogenesis of OSA is multifactorial. In children aged 2 years or older, adenoid and/or tonsil hypertrophy are the most common causes of upper airway lumen reduction; obesity becomes a major risk factor in older children and adolescents since the presence of fat in the pharyngeal soft tissue reduces the caliber of the lumen. Treatment includes surgical and non-surgical options. This narrative review summarizes the evidence available on the first-line approach in children with OSA, including clinical indications for medical therapy, its effectiveness, and possible adverse effects. Literature analysis showed that AT is the first-line treatment in most patients with adenotonsillar hypertrophy associated with OSA but medical therapy in children over 2 years old with mild OSA is a valid option. In mild OSA, a 1- to 6-month trial with intranasal steroids (INS) alone or in combination with montelukast with an appropriate follow-up can be considered. Further studies are needed to develop an algorithm that permits the selection of children with OSA who would benefit from alternatives to surgery, to define the optimal bridge therapy before surgery, to evaluate the long-term effects of INS +/- montelukast, and to compare the impact of standardized approaches for weight loss.

Correlations Between the Adenotonsillar Microbiome and Clinical Characteristics of Pediatric Patients With Snoring

Objectives

Few studies have reported combined analyses of the microbiome of the adenoids and tonsils in pediatric patients with snoring, and correlations of the adenotonsillar microbiome with clinical characteristics have not been evaluated to date. The aim of this study was to characterize the adenotonsillar microbiome and to determine its correlations with the subjective symptoms of pediatric patients with snoring and with levels of regional mucosal immune molecules.

Methods

Twenty-four children who underwent tonsillectomy with adenoidectomy owing to snoring were enrolled in this cross-sectional study conducted between August 2017 and December 2018. The microbiome of the adenoids and tonsils was characterized, and its alpha- and beta-diversity was determined. Clinical characteristics, including subjective discomfort during sleep (assessed using the obstructive sleep apnea-18 questionnaire), the presence of allergic rhinitis, concentrations of heat shock protein (Hsp)27, Hsp70, and interleukin-8 (IL-8) in lavage fluids, and white blood cell (WBC) counts, were measured.

Results

At the phylum level, the microbiome was not significantly different between the adenoids and tonsils; the alpha and beta indices were likewise not significantly different between these two regions. The alpha-diversity of the entire adenotonsillar microbiome was associated with sex, emotional stress, and IL-8 levels in the tonsil lavage fluids. Beta-diversity was associated with Hsp27 levels in the tonsil lavage fluids and WBC counts. Multiple allergen simultaneous test results were not significant, although total serum immunoglobulin E levels were significantly associated with the beta-diversity of the adenotonsillar microbiome.

Conclusion

The data reported herein suggest, for the first time, that the adenotonsillar microbiome interacts with the regional mucosal immune system. The observed association of the microbiome with subjective discomfort is a novel finding that warrants further investigation.

Prevalence of sleep-disordered breathing and associated risk factors in primary school children in urban and rural environments

INTRODUCTION

Sleep-disordered breathing (SDB) in primary school children is a significant problem, yet its prevalence is not well known outside large urban settings. Information on the burden and risk factors of SDB in children could be used to improve resource allocation when providing care across a large country. The objectives of this study were to assess the prevalence of SDB among school-aged children comparing rural and urban settings, and to investigate associated risk factors.

METHODS

In this cross-sectional study, a random sample of primary school students in Turkey were selected from urban and rural areas and data were collected using the Pediatric Sleep Questionnaire, asthma, and allergic rhinitis questionnaires completed by the parents.

RESULTS

Questionnaires were collected from a total of 139 schools from 58 provinces. A total of 11,013 students were contacted, and 9045 (73%) completed the study. There was no difference in the prevalence of SDB between rural and urban settings (16% vs. 15%, p = 0.612). Multivariate logistic regression analysis revealed that current wheezing, current rhinoconjunctivitis, being overweight, parental snoring, and current mold at home were significant risk factors for SDB in both rural and urban children. Current tobacco smoke exposure (OR = 1.48, 95%CI = 1.19-1.85), near roadway air pollution exposure (OR = 1.40, 95%CI = 1.108-1.791), and mold at home in the first year of life (OR = 1.68, 95%CI = 1.26-2.23) were associated with SDB in urban children. History of maternal/paternal adenotonsillectomy was a significant predictor of SDB in the rural setting (OR = 1.63, 95%CI = 1.12-2.39).

CONCLUSION

The prevalence of SDB is high in children living in both settings but associated risk factors may vary. Children residing in rural areas should also be screened for sleep-disordered breathing during routine health visits.

Treatment of Obstructive Sleep Apnea in Children: Handling the Unknown with Precision

Treatment approaches to pediatric obstructive sleep apnea (OSA) have remarkably evolved over the last two decades. From an a priori assumption that surgical removal of enlarged upper airway lymphadenoid tissues (T&A) was curative in the vast majority of patients as the recommended first-line treatment for pediatric OSA, residual respiratory abnormalities are frequent. Children likely to manifest persistent OSA after T&A include those with severe OSA, obese or older children, those with concurrent asthma or allergic rhinitis, children with predisposing oropharyngeal or maxillomandibular factors, and patients with underlying medical conditions. Furthermore, selection anti-inflammatory therapy or orthodontic interventions may be preferable in milder cases. The treatment options for residual OSA after T&A encompass a large spectrum of approaches, which may be complementary, and clearly require multidisciplinary cooperation. Among these, continuous positive airway pressure (CPAP), combined anti-inflammatory agents, rapid maxillary expansion, and myofunctional therapy are all part of the armamentarium, albeit with currently low-grade evidence supporting their efficacy. In this context, there is urgent need for prospective evidence that will readily identify the correct candidate for a specific intervention, and thus enable some degree of scientifically based precision in the current one approach fits all model of pediatric OSA medical care.

Adenoidal Immune Response in the Context of Inflammation and Allergy

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The mucosal-associated lymphoid tissues of the upper respiratory tract, including adenoids and palatine tonsils, are considered as the first line of defense against respiratory infections, being important effector organs in both mucosal-type and systemic-type adaptive immunity. They are strategically located for mediating both local and regional immune functions, as they are exposed to antigens from both the inhaled air (allergens and pathogens) and the alimentary tract. Adenoids play a major role in the early and effective immune responses against viral and bacterial upper airway infections, as well as in the development of allergic reactions to respiratory allergens, being influenced by several environmental antigens and pollutants, such as tobacco smoke. In addition, recent studies have focused on new immune-modulating strategies for adenoidal cells as a preventive and therapeutic approach for chronic upper airways inflammation.

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Herein, we aimed to summarize what is known about the cellular and molecular mechanisms regulating adenoidal immune responses in the context of inflammation and allergy, with particular reference to scientific literature published within the last five years.

Urine concentrations changes of cysteinyl leukotrienes in non-obese children with obstructive sleep apnea undergoing adenotonsillectomy

OBJECTIVE

The main objective of the study was to compare preoperative to postoperative levels of urine-Cysteinyl leukotrienes (uCysLT) in children undergoing adenotonsillectomy (AT) for obstructive sleep apnea (OSA) in order to investigate whether exaggerated leukotriene activity is the cause or consequence of OSA.

METHODS AND MATERIALS

A prospective study was conducted on non-obese children (4-10 years old) referred for overnight PSG. Children with moderate/severe OSA treated with AT were included. A second PSG study performed 2 months postoperatively to confirm OSA resolution, and those with residual OSA were excluded. Morning urine specimens after both PSG studies were obtained and pre-operative uCysLT levels were compared to postoperative levels.

RESULTS

27 children fulfilled the criteria and underwent a post-operative PSG study with three exclusions for residual OSA (postop-AHI>2), so the study group consisted of 24 children (mean age: 5.7 ± 2.1 years). Mean preoperative and postoperative AHI was 10.96 ± 5.93 and 1.44 ± 0.56 respectively. Mean preop-uCysLT were 21.14 ± 4.65, while after AT they significantly reduced to 12.62 ± 2.67 (P < 0.01).

CONCLUSION

uCysLT levels are significantly reduced after AT in non-obese children with moderate/severe OSA, suggesting that exaggerated leukotriene activity is mainly a consequence of OSA.

Serum leukotriene B4 levels, tonsillar hypertrophy and sleep-disordered breathing in childhood

OBJECTIVES

In children with snoring, increased production of leukotriene B₄ (LTB₄) may promote tonsillar hypertrophy and sleep-disordered breathing (SDB) or conversely SDB may enhance LTB₄ synthesis. We explored whether: i) high LTB₄ serum levels predict tonsillar hypertrophy; and ii) SDB severity correlates with LTB₄ serum concentration.

METHODS

Normal-weight children with SDB or controls underwent polysomnography and measurement of LTB₄ serum concentration. Tonsillar hypertrophy was the main outcome measure and high LTB₄ serum level (>75 t h percentile value in controls) was the primary explanatory variable. Odds ratio (OR) and the corresponding 95% confidence intervals (CI) for tonsillar hypertrophy in children with versus without high LTB₄ level were calculated. The control subgroup and subgroups of subjects with increasing SDB severity were compared regarding LTB₄ concentration by Kruskal-Wallis test. Spearman's correlation co-efficient was applied to assess the association of LTB₄ concentration with SDB severity.

RESULTS

A total of 104 children with SDB and mean obstructive apnea-hypopnea index-AHI of 4.8 ± 5.3 episodes/h (primary snoring: n = 19; mild SDB: n = 49; moderate/severe SDB: n = 36) and 13 controls (no snoring; AHI: 0.4 ± 0.2 episodes/h) were recruited. The four study subgroups were similar regarding LTB₄ serum concentration (P = 0.64). High LTB₄ (>170.3 pg/mL) was a significant predictor of tonsillar hypertrophy after adjustment for age and gender (OR 3.0 [1.2-7.2]; P = 0.01). There was no association between AHI or desaturation index and LTB₄ serum concentration (r = -0.08; P = 0.37 and r = -0.1; P = 0.30, respectively).

CONCLUSION

No association was identified between SDB severity and LTB₄ levels, but high LTB₄ concentration predicted tonsillar hypertrophy.

The bacterial community and local lymphocyte response are markedly different in patients with recurrent tonsillitis compared to obstructive sleep apnoea

INTRODUCTION

Obstructive sleep apnea (OSA) is now a more common indication for tonsillectomy than recurrent tonsillitis (RT) [1,2]. Few studies have addressed possible differences in pathogenesis between these two conditions. Children with RT and OSA are often being treated in the community with multiple courses of antibiotics before surgery. Current understanding of the role of bacteria in disorders of the tonsils is mainly based on the culture of tonsil swabs. Swab cultures reflect only a very small fraction of the bacteria present on the mucosal surface and may not represent the bacterial communities within the tonsil crypts [3,4]. This study aimed to evaluate the local lymphocyte response and associations with bacterial community composition using molecular techniques of the tonsils removed from children for RT or OSA.

METHOD

The palatine tonsils were removed by extracapsular dissection from 24 patients with age range one to ten years, 14 of whom had RT and 10 had OSA. The fixed tonsil tissues were evaluated for bacteria by Gram-staining and presence of connective tissue by safranin staining. B lymphocytes and T lymphocytes were also measured immunohistochemically. Finally, previously published bacterial community data for this cohort were reassessed for associations with RT and OSA, and with the observed lymphocyte patterns.

RESULTS

In tonsils from patients with RT, large micro-colonies of bacteria were observed in the tonsil crypts, and a large number of B and T lymphocytes were noted immediately adjacent to the tonsil crypt itself. In marked contrast, the tonsils from patients with OSA had no bacteria identified, and no significant skewing of lymphocytes based on site (such as follicles or crypts). We observed that the majority of lymphocytes surrounding the bacterial micro-colonies were B lymphocytes with a mean ratio of 109:55 (B lymphocytes: T lymphocytes). Bacterial community diversity was not different between the two cohorts; however, there were significant differences in bacterial community composition. Children with RT had a higher relative abundance of members from the genera Parvimonas, Prevotella, and Treponema. While children with OSA had a higher relative abundance of Haemophilus, and Capnocytophaga.

CONCLUSION

These results demonstrate significant differences in the local lymphocyte response and bacterial community composition in tonsil tissue between RT and OSA patients. It suggests that the response to antibiotics used in the treatment of these two conditions may be different. Furthermore, the presence of lymphocytes in RT within the tonsil crypt outside the tonsil epithelium is a unique observation of the location of these cells.

Urinary Leukotriene E4 as a Biomarker of Exposure, Susceptibility, and Risk in Asthma: An Update

Measurement of urinary leukotriene E₄ (uLTE₄) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene (CysLT) production and changes in CysLT production. Recent studies have reported on novel LTE4 receptor interactions and genetic polymorphisms causing CysLT variability. The applications of uLTE₄ as a biomarker continue to expand, including evaluation of environmental exposures, asthma severity risk, aspirin sensitivity, predicting atopy in preschool age children, obstructive sleep apnea, and predicting susceptibility to leukotriene receptor antagonists.

The relationship between allergic status and adenotonsillar regrowth: a retrospective research on children after adenotonsillectomy

Adenotonsillar regrowth in children after adenotonsillectomy (T&A) for obstructive sleep apnea (OSA) is often seen in clinical treatment, however, the relationship between allergic disease and adenotonsillar regrowth remains unclear. In this retrospective study, children were assigned to either the recurrence or control group, and subdivided by age at operation. Among children over 36 months, those in the recurrence group had more allergic disease and higher IgE, IL-4, and IL-5 levels than the same-aged children in control group. The Paediatric Allergic Disease Quality of Life Questionnaire (PADQLQ) scores for nasal symptoms and activity were higher in children older than 36 months in recurrence group. The results of immunohistochemistry and immunofluorescence showed that FoxP3+ cells (Tregs) were less, while GATA3+ cells (Th2 cells) were more in recurrence group for all ages. Allergic status and low levels of FoxP3 were proved as independent risk factors for adenotonsillar regrowth by multivariate logistic regression. These results indicate that allergic disease is a risk factor for adenotonsillar regrowth in children following T&A for OSA, and this risk increases with age. The decreased level of Tregs and subsequent changes in immune function play an important role in the pathogenesis of adenotonsillar regrowth.

Expression of CysLTR1 and 2 in Maturating Lymphocytes of Hyperplasic Tonsils Compared to Peripheral Cells in Children

Cysteinyl-leukotriene receptors 1 and 2 (CysLTR1 and 2) are related to allergic inflammatory responses. Recent studies demonstrated their role in lymphocyte division and maturation in the bone marrow. Few data are available about CysLTRs function in lymphocyte maturation in tonsils. The objectives of this study are to compare CysLTRs expression in peripheral blood lymphocytes with expression in maturating lymphocytes of hyperplasic tonsil and to check the influence of respiratory allergies in this process. Leukocytes of peripheral blood (PL) and hyperplasic tonsils of children were immunostained for CysLTR1, CysLTR2, CD3 (T cells), and CD19 (B cells) and read in flow cytometer. Lymphocyte of tonsils were divided in differentiating small cells (SC) and mitotic large cells (LC); percentage of B and T cells expressing CysLTRs was determined, and comparison was done using ANOVA and Tukey's tests. Data were analyzed as a whole and categorizing patients according the presence of allergies. Sixty children were enrolled in this study. There was a large expression of CysLTR1 and 2 in CD3+ LC, and such expression decreased progressively in SC and PL. In B cells, the highest expression of CysLTR1 and 2 was found in PL while SC showed the lowest and LC showed the intermediate expression. This pattern kept unchanged in groups of allergic and non-allergic individuals. CysLTRs seem to be involved in lymphocyte maturation that occurs in tonsils, without influence of allergies. New studies aiming the clinic treatment of tonsil hyperplasia must be targeted to the development of drugs capable of blocking both CysLTR1 and 2.

Urine cysteinyl leukotriene levels in children with sleep disordered breathing before and after adenotonsillectomy

OBJECTIVES

Obstructive sleep apnea (OSA) is a common problem in children and is associated with increased cardiovascular, neurobehavioral and somatic growth consequences. Cysteinyl leukotrienes (CysLTs) play a major role with local and systemic relations to the pathophysiology of OSA. The level of CysLTs in urine, blood, exhaled breath and adenotonsillar tissue of OSA children are increased. However it remains unclear whether inflammatory marker levels are alleviated after adenotonsillectomy. Therefore, we compare the urine leukotriene E4 (uLTE4) levels in children before and after adenotonsillectomy and evaluate clinical outcomes on resolution of OSA.

METHODS

Children under 15 years who suspected OSA with planned adenotonsillectomy were recruited. Sleep questionnaires, quality of life assessment by OSA-18, physical examination, lateral neck radiographs, overnight SpO₂ monitoring and uLTE4 levels were collected. 4 ± 2 weeks post-surgery, OSA-18 was reevaluated and urine was collected again.

RESULTS

Thirty-three children with sleep disordered breathing (SDB) were included (mean age 8.1 ± 2.8 years). After adenotonsillectomy, the uLTE₄ levels decreased from 961.9 (684.8-1438.2) to 708.6 (538.2-1038.8) pg/mg Cr (P = 0.009). The post-surgery score from sleep questionnaire, OSA-18 questionnaire were significant improved (P < 0.001). Obese children demonstrated an improved quality of life post-surgery, but results were poorer than normal-weight children (P = 0.01). The uLTE4 no obvious improved in obese children.

CONCLUSIONS

Adenotonsillectomy remains an effective treatment for SDB children that not only alleviated the severity of SDB and improved quality of life; it also decreased levels of the systemic inflammatory marker, uLTE4. However, benefits were more obvious in non-obese children.

Expression of cysteinyl leukotriene receptor 1 and 2 (CysLTR1 and CysLTR2) in the lymphocytes of hyperplastic tonsils: comparison between allergic and nonallergic snoring children

BACKGROUND

Cysteinyl leukotriene receptor 1 and 2 (CysLTR1 and CysLTR2) are involved in allergic processes and play a role in adenotonsillar hyperplasia (AH). Clinically, only CysLTR1 may be blocked by montelukast. Our objective was to compare the expression of CysLTR1 and CysLTR2 in the B and T cells of hyperplasic tonsils of sensitized (SE) and control (NS) snoring children.

METHODS

Sixty children, 5 to 10 years of age, referred for adenotonsillectomy, were divided into SE and NS groups, according to their responses to the skin-prick test. Cells from the removed tissues were stained for CysLTR1, CysLTR2, CD19, and CD3 and counted via flow cytometry. messenger RNA (mRNA) expression of the CysLTRs genes was measured real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR).

RESULTS

The SE group showed reduced expression of the small CD3+/CysLTR1+ lymphocytes (4.6 ± 2.2 vs 6.5 ± 5.0; p = 0.04). Regarding the large lymphocytes, the SE group showed lower expression of CD3+/CysLTR1+ (40.9 ± 14.5 vs 47.6 ± 11.7; p = 0.05), CD19+/CysLTR1+ (44.6 ± 16.9 vs 54.1 ± 12.4; p = 0.01), and CD19+/CysLTR2+ (55.3 ± 11.3 vs 61.5 ± 12.6; p = 0.05) lymphocytes. Considering the total number of lymphocytes, the SE group had fewer CD3+/CysLTR1+ lymphocytes (11.1 ± 5.5 vs 13.7 ± 6.2; p = 0.04). All other cell populations exhibited reduced expression in the SE group without statistical significance. The expression of CysLTR2 was significantly higher (p < 0.05) than CysLTR1 in most studied cell populations. The mRNA expression did not show significant differences between the groups.

CONCLUSION

The expression of CysLTR is higher in the lymphocytes of the NS children, and CysLTR2 shows greater expression than CysLTR1 Respiratory allergies do not appear to be a stimulus for AH occurrence. Newer drugs capable of blocking both CysLTRs warrant further study.

Paediatric obstructive sleep apnoea syndrome (OSAS) is associated with tonsil colonisation by Streptococcus pyogenes

The involvement of pathogenic bacteria in obstructive sleep apnoea syndrome (OSAS) has yet to be elucidated. We investigated the possible role of group A streptococcus (GAS) in OSAS pathogenesis. In 40 tonsillectomized patients affected by OSAS and 80 healthy controls, significant (p < 0.0001) association of GAS with paediatric OSAS was found. Supernatant from streptolysin O (SLO)-producing GAS induced production of cysteinyl leukotrienes (CysLTs) in tonsil mononuclear cells (TMCs). CysLTs-treated TMCs showed significant (p < 0.05) proliferation of CD4+ T, CD19+ and CD19+CD27+CD38+ B lymphocytes. We discovered a SLO-dependent activation of CysLTs production through a pathway involving TOLL-like receptor 4 (TLR4), TIR-domain-containing adapter-inducing interferon-β (TRIF), Myeloid differentiation primary response gene 88 (MyD88), and p38 MAP Kinase. In conclusion, we hypothesise that GAS may contribute to paediatric tonsillar hyperplasia through CysLTs production induced by SLO, and this might explain its association with OSAS.

Sleep Disordered Breathing in Children

Sleep-disordered breathing (SDB) refers to a group of disorders characterized by abnormalities of respiration or ventilation during sleep. It encompasses obstructive sleep apnea (OSA), central sleep apnea (CSA) syndromes, sleep-related hypoventilation and sleep-related hypoxemia disorders. This review will concentrate on the disorder most prevalent in pediatrics, i.e., OSA, highlighting the most recent developments in our understanding of the etiology, pathophysiology and treatment options of this condition. OSA morbidities primarily involve the neurocognitive, cardiovascular and metabolic systems. However, there can be significant phenotypic variation in terms of end organ morbidity for the same OSA severity. This is likely due to the interplay between genetic and environmental factors; recent developments in the fields of genomics and proteomics have the potential to shed light on these complex pathological cascades. As we enter the era of personalized medicine, phenotyping patients to enable clinicians to tailor bespoke clinical management plans will be of crucial importance.

Atopy does not affect the frequency of adenotonsillar hypertrophy and sleep apnoea in children who snore

AIM

Viral respiratory infections and atopy have been implicated in the pathogenesis of adenotonsillar hypertrophy and obstructive sleep apnoea (OSA), but the role of atopy is controversial. We aimed to test our hypothesis that atopy, expressed as physician-diagnosed eczema, was associated with adenotonsillar hypertrophy and OSA among children who snored.

METHODS

Data on children who snored and were referred for polysomnography were reviewed. The primary outcome measures were adenotonsillar hypertrophy and OSA.

RESULTS

We analysed data on 855 children with a mean age (±standard deviation) of 6.3 (±2.5) years and median obstructive apnoea-hypopnea index of 2.1 episodes per hour. Of the 855 subjects, 133 (15.6%) had physician-diagnosed eczema, 591 (69.1%) had adenoidal hypertrophy, 605 (70.8%) had tonsillar hypertrophy, 219 (25.6%) were obese and 470 (55%) had OSA. Eczema was not related to adenoidal or tonsillar hypertrophy after adjustment for gender and age, with odds ratios (OR) of 1.00 (95% confidence interval 0.67-1.49; p = 0.98) and 0.88 (95% confidence interval 0.59-1.32; p = 0.54), respectively. Similarly, eczema did not affect OSA frequency after adjustment for adenoidal and tonsillar hypertrophy, obesity, gender and age, with an adjusted OR of 0.82 (0.56-1.21; p = 0.32).

CONCLUSIONS

Atopy was not related to adenotonsillar hypertrophy or OSA in children who snore.

Update on leukotriene, lipoxin and oxoeicosanoid receptors: IUPHAR Review 7

The endogenous ligands for the LT, lipoxin (LX) and oxoeicosanoid receptors are bioactive products produced by the action of the lipoxygenase family of enzymes. The LT receptors BLT1 and BLT2 , are activated by LTB4 and the CysLT1 and CysLT2 receptors are activated by the cysteinyl-LTs, whereas oxoeicosanoids exert their action through the OXE receptor. In contrast to these pro-inflammatory mediators, LXA4 transduces responses associated with the resolution of inflammation through the receptor FPR2/ALX (ALX/FPR2). The aim of the present review is to give a state of the field on these receptors, with focus on recent important findings. For example, BLT1 receptor signalling in cancer and the dual role of the BLT2 receptor in pro- and anti-inflammatory actions have added more complexity to lipid mediator signalling. Furthermore, a cross-talk between the CysLT and P2Y receptor systems has been described, and also the presence of novel receptors for cysteinyl-LTs, such as GPR17 and GPR99. Finally, lipoxygenase metabolites derived from ω-3 essential polyunsaturated acids, the resolvins, activate the receptors GPR32 and ChemR23. In conclusion, the receptors for the lipoxygenase products make up a sophisticated and tightly controlled system of endogenous pro- and anti-inflammatory signalling in physiology and pathology.

Family history of adenotonsillectomy as a risk factor for tonsillar hypertrophy and snoring in childhood

OBJECTIVE

Accumulating evidence supports a role for familial predisposition in the pathogenesis of OSA. In this study, it was hypothesized that parental history of adenoidectomy and/or tonsillectomy (AT), which is the standard treatment for pediatric OSA is a risk factor for tonsillar hypertrophy and habitual snoring (>3 nights/week) in the offspring.

METHODS

Children were recruited from the emergency department and the pediatric pulmonology clinic. Paternal or maternal history of AT (explanatory variables) and habitual snoring (outcome) were recorded and presence of tonsillar hypertrophy (outcome) was assessed.

RESULTS

Two hundred ninety-two children (2-14 y.o.) were recruited; 37 (12.7%) of them had paternal history of AT, 39 (13.4%) maternal history of AT, 60 (20.5%) tonsillar hypertrophy, and 48 (16.4%) habitual snoring. Maternal and paternal history of AT were significantly associated with the presence of tonsillar hypertrophy even after adjustment for age, gender, obesity, passive smoking, and physician-diagnosed wheezing requiring treatment with inhaled medications over the past year [odds ratios (95% confidence interval): 3.52 (1.54-8.06); P < 0.01 and 4.70 (2.13-10.36); P < 0.01, respectively]. Only maternal history of AT predicted history of snoring [4.12 (1.86-9.12); P < 0.01]. When entered in the same multivariate logistic regression analysis model, tonsillar hypertrophy was a stronger predictor of habitual snoring than maternal history of AT [4.00 (1.97-8.14) vs. 2.73 (1.20-6.20)].

CONCLUSIONS

Children with parental history of AT have more frequently tonsillar hypertrophy than those without such history. Tonsillar hypertrophy mediates at least in part the association between maternal history of AT and habitual snoring in childhood.

The promise of translational and personalised approaches for paediatric obstructive sleep apnoea: an 'Omics' perspective

Obstructive sleep apnoea (OSA) can result in significant morbidities including the cardiovascular, metabolic and neurocognitive systems. These effects are purportedly mediated via activation of inflammatory cascades and the induction of oxidative stress, ultimately resulting in cellular injury and dysfunction. While great advances have been made in sleep medicine research in the past decades, there are still wide gaps in our knowledge concerning the exact underlying pathophysiological mechanisms of OSA and consequences. Without resolving these issues, the reasons why patients with a similar severity of OSA can have markedly different clinical presentation and end-organ morbidity, that is, phenotype, will continue to remain elusive. This review aims to highlight the recent exciting discoveries in genotype-phenotype interactions, epigenetics, genomics and proteomics related to OSA. Just as PCR revolutionised the field of genetics, the potential power of 'Omics' promises to transform the field of sleep medicine, and provide critical insights into the downstream pathological cascades inherent to OSA, thereby enabling personalised diagnosis and management for this highly prevalent sleep disorder.

Antileukotriene agents for the treatment of lung disease

Leukotrienes (LTs) C4, D4, and E4, collectively termed cysteinyl LTs (cysLTs), are lipid mediators formed by the 5-lipoxygenase (5-LO) pathway of arachidonic acid metabolism. Originally recognized for their potent bronchoconstrictor actions, they were subsequently determined also to promote inflammation, microvascular permeability, and mucus secretion. These actions that are so central to asthma pathophysiology are mediated to a significant extent by ligation of the cysLT receptor 1 (CysLT1). Antagonism of CysLT1 and inhibition of 5-LO have both been shown to have clinical use in the management of asthma, but substantial interindividual heterogeneity is observed in the response to these agents. In this article, we review the biologic actions of LTs, their biosynthetic pathways and cognate receptors, the pharmacology of available anti-LT agents, and the clinical evidence for the use of anti-LT agents as monotherapy and combination therapy in asthma. We also consider heterogeneity of response, the possible roles of cysLT receptors other than CysLT1, the role of another class of LT, LTB4, and the potential role of LTs in lung diseases other than asthma.

Low morning serum cortisol levels in children with tonsillar hypertrophy and moderate-to-severe OSA

BACKGROUND

Hypertrophic tonsillar tissue in children with obstructive sleep apnea (OSA) has enhanced expression of glucocorticoid receptors, which may reflect low endogenous cortisol levels. We have evaluated the effect of the interaction between tonsillar hypertrophy and OSA severity on morning serum cortisol levels.

METHODS

Children with and without snoring underwent polysomnography, tonsillar size grading, and measurement of morning serum cortisol.

RESULTS

Seventy children (2-13 years old) were recruited: 30 with moderate-to-severe OSA (apnea-hypopnea index [AHI] > 5 episodes/h), 26 with mild OSA (AHI > 1 and ≤ 5), and 14 controls (no snoring; AHI ≤ 1). Tonsillar hypertrophy was present in 56.7%, 53.8%, and 42.9% of participants in each group, respectively. Application of a general linear model demonstrated a significant effect of the interaction between severity of OSA and tonsillar hypertrophy on cortisol levels (P = 0.04), after adjustment for obesity, gender, and age. Among children with tonsillar hypertrophy, subjects with moderate-to-severe OSA (n = 17; AHI 14.7 ± 10.6), mild OSA (n = 14; AHI 2.3 ± 1.2), and control participants (n = 6; AHI 0.7 ± 0.2) were significantly different regarding cortisol levels (P = 0.02). Subjects with moderate-to-severe OSA had lower cortisol (16.9 ± 8.7 mcg/dL) than those with mild OSA (23.3 ± 4.2; P = 0.01) and those without OSA (controls) (23.6 ± 5.3 mcg/dL; P = 0.04). In contrast, children with normal-size tonsils and moderate-to-severe OSA, mild OSA, and controls did not differ in cortisol levels.

CONCLUSIONS

Children with moderate-to-severe obstructive sleep apnea and the phenotype of hypertrophic tonsils have reduced morning serum cortisol levels and potentially decreased glucocorticoid inhibitory effects on tonsillar growth.

Are GPCRs Still a Source of New Targets?

G-protein–coupled receptors (GPCRs) still offer enormous scope for new therapeutic targets. Currently marketed agents are dominated by those with activity at aminergic receptors and yet they account for only ~10% of the family. Progress up until now with other subfamilies, notably orphans, Family A/peptide, Family A/lipid, Family B, Family C, and Family F, has been, at best, patchy. This may be attributable to the heterogeneous nature of GPCRs, their endogenous ligands, and consequently their binding sites. Our appreciation of receptor similarity has arguably been too simplistic, and screening collections have not necessarily been well suited to identifying leads in new areas. Despite the relative shortage of high-quality tool molecules in a number of cases, there is an emerging, and increasingly substantial, body of evidence associating many as yet “undrugged” receptors with a very wide range of diseases. Significant advances in our understanding of receptor pharmacology and technical advances in screening, protein X-ray crystallography, and ligand design methods are paving the way for new successes in the area. Exploitation of allosteric mechanisms; alternative signaling pathways such as G12/13, Gβγ, and β-arrestin; the discovery of “biased” ligands; and the emergence of GPCR-protein complexes as potential drug targets offer scope for new and much improved drugs.

Genotype-phenotype interactions in pediatric obstructive sleep apnea

Pediatric sleep disordered breathing (PSDB) is not only a very frequent condition affecting 2-4% of all children, but is also associated with an increased risk for a variety of manifestations underlying end-organ injury and dysfunction that impose both immediate and potentially long-term morbidities and corresponding inherent elevations in healthcare costs. One of the major problems with the creation of valid algorithms aiming to stratify diagnostic and treatment prioritization lies in our current inability to predict and identify those children who are most at-risk for PSDB-induced adverse consequences. Thus, improved our understanding of the mechanisms governing phenotype variance in PSDB is essential. Here, we examine some of the potential underpinnings of phenotypic variability in PSDB, and further propose a conceptual framework aimed at facilitating the process of advancing knowledge in this frequent disorder.

Novel pharmacological approaches for treatment of obstructive sleep apnea in children

INTRODUCTION

The lymphadenoid tissues in the upper airway are sparse and organized lympho-epithelial structures playing an important role against foreign pathogens, with the palatine tonsils being the major components of the lymphoid tissues contained in the Waldeyer's ring. Obstructive sleep apnea (OSA) has emerged as a very frequent condition in the pediatric age range that is associated with substantial neurobehavioral, cardiovascular and metabolic morbidities. Adenotonsillar hypertrophy is the major pathophysiological contributor to OSA occurrence in children.

AREAS COVERED

Here, the authors provide a systematic review and summary of some of the known histological and pathological features of human lymphadenoid tissues and their fundamental immunological functions, provide insights into the pathophysiology of pediatric OSA, particularly focusing on inflammatory pathways and the available outcomes associated with targeting such pathways with compounds such as corticosteroids and leukotriene modifiers. Furthermore, they present findings from an unbiased approach to discovery of therapeutic targets and formulate constructs toward putative future interventional approaches for this highly prevalent condition.

EXPERT OPINION

Surgical approaches for pediatric OSA may not be as effective as previously anticipated. Accordingly, expanded use of existing systemic or topical anti-inflammatory agents or development of novel compounds targeting selected immune cell populations underlying pathophysiological determinants of OSA is needed.