A mixed cell culture model for assessment of proliferation in tonsillar tissues from children with obstructive sleep apnea or recurrent tonsillitis

A rat model of adenoid hypertrophy constructed by using ovalbumin and lipopolysaccharides to induce allergy, chronic inflammation, and chronic intermittent hypoxia

BACKGROUND

Adenoid hypertrophy (AH) is a common pediatric disease that significantly impacts the growth and quality of life of children. However, there is no replicable and valid model for AH.

METHODS

An AH rat model was developed via comprehensive allergic sensitization, chronic inflammation induction, and chronic intermittent hypoxia (CIH). The modeling process involved three steps: female Sprague-Dawley rats (aged 4-5 weeks) were used for modeling. Allergen sensitization was induced via intraperitoneal administration and intranasal provocation using ovalbumin (OVA); chronic nasal inflammation was induced through intranasal lipopolysaccharide (LPS) administration for sustained nasal irritation; CIH akin to obstructive sleep apnea/hypopnea syndrome was induced using an animal hypoxia chamber. Postmodel establishment, behaviors, and histological changes in nasopharynx-associated lymphoid tissue (NALT) and nasal mucosa were assessed. Arterial blood gas analysis and quantification of serum and tissue levels of (interleukin) IL-4 and IL-13, OVA-specific immunoglobulin E (sIgE), eosinophil cationic protein (ECP), tumor necrosis factor (TNF-α), IL-17, and transforming growth factor (TGF)-β were conducted for assessment. The treatment group received a combination of mometasone furoate and montelukast sodium for a week and then was evaluated.

RESULTS

Rats exhibited notable nasal symptoms and hypoxia after modeling. Histopathological analysis revealed NALT follicle hypertrophy and nasal mucosa inflammatory cell infiltration. Elevated IL-4, IL-13, IL-17, OVA-sIgE, ECP, and TNF-α levels and reduced TGF-β levels were observed in the serum and tissue of model-group rats. After a week of treatment, the treatment group exhibited symptom and inflammatory factor improvement.

CONCLUSION

The model effectively simulates AH symptoms and pathological changes. But it should be further validated for genetic, immunological, and hormonal backgrounds in the currently used and other strains and species.

Tumor necrosis factor alpha and palmitate simulate bovine fatty liver disease in vitro when using abattoir-derived primary bovine hepatocytes isolated by a novel nonperfusion method

Hepatic lipidosis (i.e., fatty liver) is a common periparturient disease in high-producing dairy cattle affecting nearly 50% of cows to some degree and costing an estimated 60 million dollars annually. Large animal studies are costly, labor intensive, and are not well suited to mechanistic studies. Traditionally, mechanistic studies employ in vitro methodologies, utilizing established cell lines or primary cell culture methods. However, with dairy cattle, established hepatic cell lines do not exist, and methods for primary cell culture studies typically involve complicated procedures that often utilize very young animals (typically bull calves). Several previously published papers have used abattoir-derived tissues as a source of primary cells; however, a simple method utilizing simple culture media has yet to be presented. In addition, we sought to develop a way to replicate the syndrome of fatty liver disease "in a dish" using adult cattle that should more closely represent the physiology of the periparturient dairy cow. Herein we present a non-perfusion-based method that results in robust growth and proliferation of abattoir-derived bovine hepatocytes that demonstrate lipid loading, elevated lactate dehydrogenase leakage, and cytotoxicity as demonstrated by elevated caspase 3/7 expression consistent with in vivo physiology of the periparturient dairy cow with fatty liver disease.

Possible mechanism of CHI3L1 promoting tonsil lymphocytes proliferation in children with obstructive sleep apnea syndrome

BACKGROUND

The typical characteristic of pediatric obstructive sleep apnea syndrome (OSAS) is systemic inflammation and adenotonsillar hypertrophy (ATH), but the inflammatory markers and mechanism of adenotonsillar proliferation are unclear.

METHODS

IHC, qPCR, and western blotting were used to identify the expression of CHI3L1 in the tonsils of children with OSAS. The primary tonsil lymphocytes (PTLCs) from children with OSAS were cultured and recombinant human CHI3L1 protein was added to culture media. After the stimulation with CHI3L1 protein of different concentrations and time points, lymphocyte proliferation was assessed by CCK-8 kits and flow cytometry. The activation of ERK1/2 and the effects on the proliferation of PTLCs were observed by western blotting.

RESULTS

The expression of CHI3L1 was higher in the OSAS group than in the PS group. CHI3L1 (100 ng/mmol for 24 h) resulted in a significant increase in the proliferation rate. The ERK1/2 activator (PMA) promoted the proliferation of PTLCs and inhibitor AG126 significantly inhibited proliferation.

CONCLUSIONS

CHI3L1 can promote the proliferation of tonsil lymphocytes via ERK1/2 pathways. This result indicates that CHI3L1 may play an important role in the pathogenesis of OSAS in children. Inhibition of CHI3L1 or ERK1/2 may be potential therapeutic targets for CHI3L1-induced proliferation in childhood OSAS.

IMPACT

CHI3L1 may be an inflammatory marker in childhood OSAS. CHI3L1 can promote the proliferation of PTLCs in a concentration and time-dependent condition. CHI3L1 can promote the proliferation of tonsil lymphocytes via ERK1/2 pathways.

Simple hypertrophic tonsils have more active innate immune and inflammatory responses than hypertrophic tonsils with recurrent inflammation in children

Background

Tonsil hypertrophy has negative impact on children’s health, but its pathogenesis remains obscure despite the fact that numerous bacteriological studies have been carried out. Understanding the innate immune and inflammatory states of hypertrophic tonsils with different clinical manifestations is of great significance for defining the pathogenesis of tonsil hypertrophy and establishing treatment strategies. The present study was undertaken to examine the characteristics of innate immunity and inflammation in children with hypertrophic palatine tonsils and different clinical manifestations.

Methods

Tonsil tissues were surgically removed from the patients and classified based on the patients’ clinical manifestations. The patients were divided into three groups: 1) Control group; 2) Tonsil Hypertrophy (TH) group; and 3) Tonsil Hypertrophy combined with Recurrent Infection (TH + RI) group. The immune and inflammatory statuses of these tissues were characterized using qRT-PCR and ELISA methods.

Results

Viral protein 1 (VP1) was highly expressed in TH group, but not in TH + RI group. In TH group, elevated expression was observed in the innate immune mediators, including retinoic acid-inducible gene I (RIG-I), interferon alpha (IFN-α), mitochondrial antiviral-signaling protein (MAVS), NLR family pyrin domain containing 3 (NLRP3), toll-like receptor (TLR) 4 and TLR7. Consistent with the innate immune profile, the expression of inflammatory markers (IL-1β, NF-κB and IL-7) was also significantly elevated in TH group. Meanwhile, the COX-2/PGE2/EP4 signaling pathway was found to be involved in the inflammatory response and the formation of fibroblasts.

Conclusions

Innate immune and inflammatory responses are more active in simple hypertrophic tonsils, rather than hypertrophic tonsils with recurrent inflammation. A local relative immune deficiency in the hypertrophic tonsils may be a causative factor for recurrent tonsillitis in TH + RI. These differences, together with the patient’s clinical manifestations, suggest that tonsillar hypertrophy might be regulated by diverse immune and/or inflammatory mechanism through which novel therapeutic strategies might be created.

Impact of adenotonsillectomy on the evolution of inflammatory markers

BACKGROUND

Tonsils are first-line host defence organs against pathogenic agents and participate in local and systemic immunity. Persistent increases in systemic inflammatory responses may contribute to associated morbidity. The aim of this study was to verify the short- and long-term impact of adenotonsillectomy on the evolution of inflammatory markers in 3- to 9-year-old children.

METHODS

A prospective and longitudinal study was conducted over 1 year in 29 children who underwent tonsillectomy due to either chronic tonsillitis or adenotonsillar hypertrophy. Measurements of high-sensitivity C-reactive protein (hs-CRP) levels were taken. Levels of Th1-type cytokines [interleukin-1, interferon-γ, and tumor necrosis factor-α (TNF-α)] and anti-inflammatory Th2-type cytokines [interleukin-4, -5, -6, -10 and -13] were measured. Levels of transforming growth factor-beta (TGF-β) and intercellular adhesion molecule-1 (ICAM-1) were also determined. The results were compared to those of 29 control children.

RESULTS

At baseline, children with surgery indications presented with higher levels of hs-CRP, interleukin-1 and -10, interferon-γ, TNF-α and ICAM-1, whereas values of interleukin-4 were significantly lower than in control children. Children with severe tonsillar obstruction had higher values of interleukin-1, -4, and -5 and lower values of interleukin-10 compared with children with recurrent tonsillitis. One year after surgery, the levels except IL-4 did not show a significant difference from those obtained in the control group. The levels of hs-CRP and TNF-α decreased significantly in the first month.

CONCLUSION

Children with chronic tonsillitis and/or adenotonsillar hypertrophy have significantly elevated levels of proinflammatory cytokines. Adenotonsillectomy restores the normal values of these parameters 1 year after surgery.

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.

Gluten-free diet may improve obstructive sleep apnea-related symptoms in children with celiac disease

Background

Enlarged tonsils and adenoids are the major etiology of obstructive sleep apnea (OSA) in children. Lymphatic hyperplasia is common to both OSA and celiac disease. We aimed to investigate the effect of a gluten-free diet on OSA symptoms in children with celiac disease.

Methods

Children with celiac disease aged 2–18 years were prospectively recruited before the initiation of a gluten-free diet. Children with negative celiac serology who underwent gastrointestinal endoscopies for other indications served as controls. All participants completed a validated OSA-related symptoms questionnaire and the pediatric sleep questionnaire (PSQ) at baseline and 6 months later.

Results

Thirty-four children with celiac disease (mean age 6.6 ± 3.5 years) and 24 controls (mean age 7.3 ± 4.6 years, P = 0.5) were recruited. There were no significant differences in gender, body mass index or season at recruitment between the two groups. The rate of positive PSQ scores was higher (more OSA-related symptoms) in the control group compared to the celiac group, both at recruitment and at the 6-month follow-up (33.3% vs. 11.8%, P = 0.046, and 16.7% vs. 0, P = 0.014, respectively). PSQ scores improved significantly in both groups at the 6-month follow-up (P < 0.001 for both). Improvement was significantly higher in the celiac group compared to controls (0.1 ± 0.09 vs.0.06 ± 0.06, respectively, P = 0.04).

Conclusions

Children with celiac disease had fewer OSA-related symptoms than controls, but the degree of improvement following the initiation of a gluten-free diet was significantly higher. These findings suggest that a gluten-free diet may improve OSA-related symptoms in children with celiac disease.

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.

Substance P and neurokinin 1 receptors as potential therapeutic targets in children with OSA

BACKGROUND

Increased substance P (SP) levels and abundant expression of neurokinin (NK) 1 receptor in adenotonsillar tissues of children with OSA but not recurrent tonsillar infection (RI) suggest that NK1 antagonists could be useful in treating OSA.

METHODS

The effects of SP and the NK1 antagonist GR-82334 were examined on mixed cell cultures prepared from dissociated tonsils harvested intraoperatively from children with OSA and RI. Proliferation was assessed by [3H]-thymidine or 5-ethynyl-2'-deoxyuridine incorporation, and inflammatory cytokine production (tumor necrosis factor [TNF]-α, IL-6, IL-1β) was assessed in supernatants by enzyme-linked immunosorbent assay.

RESULTS

SP elicited dose-dependent increases in tonsillar cell proliferation in mixed cell cultures from children with OSA but not with RI (P &lt; .0001). The NK1 antagonist exhibited dose-dependent reductions in cellular proliferative rates in OSA-derived cell cultures but not in RI-derived mixed cell cultures (P &lt; .00001). SP treatment was associated with increased TNF-α and IL-6 production, and GR-82334 abrogated SP effects, as well as reduced basal cytokine release (P &lt; .0001).

CONCLUSIONS

SP pathways appear to underlie intrinsic proliferative and inflammatory signaling pathways in tonsillar tissues from children with OSA but not with RI. Selective disruption of these pathways may provide nonsurgical alternatives for prevention and treatment of pediatric OSA.

Obstructive sleep apnea in children: a critical update

Obstructive sleep apnea (OSA) in children is a highly prevalent disorder caused by a conglomeration of complex pathophysiological processes, leading to recurrent upper airway dysfunction during sleep. The clinical relevance of OSA resides in its association with significant morbidities that affect the cardiovascular, neurocognitive, and metabolic systems. The American Academy of Pediatrics recently reiterated its recommendations that children with symptoms and signs suggestive of OSA should be investigated with polysomnography (PSG), and treated accordingly. However, treatment decisions should not only be guided by PSG results, but should also integrate the magnitude of symptoms and the presence or absence of risk factors and signs of OSA morbidity. The first-line therapy in children with adenotonsillar hypertrophy is adenotonsillectomy, although there is increasing evidence that medical therapy, in the form of intranasal steroids or montelukast, may be considered in mild OSA. In this review, we delineate the major concepts regarding the pathophysiology of OSA, its morbidity, diagnosis, and treatment.

Alterations in circulating T-cell lymphocyte populations in children with obstructive sleep apnea

STUDY OBJECTIVES

Changes in lymphocyte phenotype and functionality have been described in adult patients with obstructive sleep apnea (OSA). We hypothesized that OSA is associated with T lymphocyte alterations in children, particularly in T regulatory lymphocytes (T regs), and aimed to characterize circulating T lymphocyte subsets in children with OSA.

DESIGN

Cross-sectional.

SETTING

Kosair Children's Hospital (Louisville, KY, USA) and Comer Children's Hospital (Chicago, IL, USA).

PARTICIPANTS

Consecutively recruited children being evaluated for habitual snoring.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Overnight polysomnography (PSG) was performed and a fasting blood sample was obtained from the patients. Flow cytometry was performed on peripheral blood mononuclear cells stained for CD3, CD4, CD8, CD25, FOXP3, interleukin-4 (IL-4), interferon-γ (IFN-γ), and IL-17. Patients were divided into three groups based on their PSG: controls (apnea-hypopnea indices [AHI] < 1/h total sleep time [TST]), mild OSA (1 ≤ AHI < 5/hTST), moderate-severe OSA (AHI ≥ 5/h TST). The percentage of CD4+ and T reg lymphocytes differed across groups. Children with moderate-severe OSA had significantly reduced T reg than control children (median [interquartile range] 4.8 [3.8-5.7% CD4+] versus 7.8 [7.0-9.2% CD4+]; P < 0.001). There were also significant differences in the percentage of T helper 1 (Th1) lymphocytes and in Th1:Th2 ratios between groups. Children with moderate-severe OSA had increased Th1 cells (P = 0.001) and Th1:Th2 ratios (P = 0.0026) compared with children with mild OSA and control children. Associations between AHI and T reg (P = 0.0003; r = -0.46), CD4+ lymphocytes (P = 0.0047; r = -0.37), and Th1:Th2 ratios (P = 0.0009; r = 0.43) emerged. In addition, the percentage of T reg was inversely correlated with Th1:Th2 ratios (P = 0.029; r = -0.29).

CONCLUSIONS

Pediatric OSA is associated with reduced T reg population and altered Th1:Th2 balance toward Th1 predominance, suggesting a shift to a proinflammatory state. The changes in lymphocytic phenotypes associated with OSA may contribute to the variance in systemic inflammation and downstream morbidities associated with this condition.

Tissue fatty acid composition in obstructive sleep apnea and recurrent tonsillitis

OBJECTIVE

Tonsillar hypertrophy cells appear to have an altered lipid metabolism as evidenced by modulated inflammatory cytokines that affect tissue lipid metabolism. The aim of this study was to investigate differences in tissue fat composition between obstructive sleep apnea (OSA) and recurrent infective tonsillitis (RT) in children.

METHODS

Tonsillar tissues were collected from 114 patients with OSA and 92 patients with RT, aged 4-10 years, during tonsillectomy. The tissue lipid extracts were analyzed by gas liquid chromatography for a comprehensive fatty acid profile.

RESULTS

In the tonsillitis tissue, the levels of palmitoleic acid (16:1n-7; P=0.002) and oleic acid (18:1n-9; P=0.003) were higher, and the level of stearic acid (18:0; P=0.004) was lower than that in the hyperplastic tonsillar tissue. Overall, tonsillar tissue of patients with RT had a significant increase in the total monounsaturated fatty acids (+9.9%; P<0.001) and the fatty acid desaturation index (+20.5%; P<0.001). Furthermore, oleic acid content of tonsillar tissue was positively correlated with BMI (r=0.20, P=0.004), snoring (r=0.16, P=0.022) and hypertrophy grade (r=0.18, P=0.023), which remain significant in the subgroup analysis by hypertrophy type.

CONCLUSIONS

The change in the fatty acid composition may be regarded as an indicator of altered lipid metabolism occurring in vivo during human tonsillar hypertrophy, which might be linked to the severity or type of the tissue damage.

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.

Circulating phospholipase-A2 activity in obstructive sleep apnea and recurrent tonsillitis

OBJECTIVE

Phospholipase A2 (PLA2) plays a major part in growth regulation, differentiation and inflammation. It has been proposed as an evaluating marker for infection and inflammation. The aim of this study was to investigate activity of serum type II secretory PLA2 (sPLA2 IIa) in obstructive sleep apnea (OSA) and recurrent infective tonsillitis (RT) in children.

METHODS

Activity of serum sPLA2 IIa was determined in children who underwent tonsillectomy, including OSA in 126 cases and RT in 60. Serum enzyme activities were measured using the standard assay with Diheptanoyl Thio-Phosphatidylcholin as substrate.

RESULTS

The sPLA2 IIa activity of serum was significantly higher in RT than in OSA (P<0.01). Serum sPLA2 IIa activity in the RT patients was positively correlated with BMI (r=0.26; P=0.02), which was not apparent in OSA (r=0.14; P=0.09).

CONCLUSION

This study suggests that serum sPLA2 IIa activity may be considered as a supportive diagnostic marker in suspected or clinically unclear cases of RT children.

Treatment of adenotonsillar hypertrophy: A prospective randomized trial comparing azithromycin vs. fluticasone

BACKGROUND

The aim of this study was to compare the efficacy of azithromycin vs. fluticasone in treatment of adenotonsillar hypertrophy (AH).

METHODS

In a clinical trial, 39 AH patients were selected using a convenient time-based sequential sampling method. The subjects were randomized into two treatment groups. Patients in group A (fluticasone) and B (azithromycin) were respectively treated with fluticasone spray and azithromycin suspension for a 6-week period. Data regarding the grade of obstruction (based on tonsillar size), level of adenotonsillar hypertrophy, and obstructive sleep apnea (OSA) symptoms (including mouth breathing, snoring, hyponasal speech, and sleep apnea) were collected by a self-administrated questionnaire before treatment, as well as 1 week and 8 weeks after treatment.

RESULTS

Twenty AH patients in group A and 19 AH patients in group B were studied. AH related symptoms, including mouth breathing, snoring, hyponasal speech and sleep apnea, improved significantly in both groups (p < 0.05). We also found a statistically significant reduced grade of obstruction among patients in both groups. However, fluticasone was not effective on adenotonsillar hypertrophy. One week after treatment, outcomes related to apnea and hyponasal speech were better in group B than group A. Decreases in mouth breathing and snoring were not significantly different between group A and B.

CONCLUSIONS

It could explain that though both of the improved and mentioned symptoms comparing within initial status, Azithromycin seems to be more effective than fluticasone in improving AH-related symptoms. Short term efficacy of the antibiotic is much significant than its long term effect.

Obstructive sleep apnea syndrome in children

The clinical syndrome of obstructive sleep apnea (OSAS) in children is a distinct, yet somewhat overlapping disorder with the condition that occurs in adults, such that the clinical manifestations, polysomnographic findings, diagnostic criteria and treatment approaches need to be considered in an age-specific manner. Childhood OSAS has now become widely recognized as a frequent disorder and as a major public health problem. Pediatric OSAS, particularly when obesity is concurrently present, is associated with substantial end-organ morbidities and increased healthcare utilization. Although adenotonsillectomy (T&A) remains the first line of treatment, evidence in recent years suggests that the outcomes of this surgical procedure may not be as favorable as expected, such that post-T&A polysomnographic evaluation may be needed, especially in high-risk patient groups. In addition, incorporation of nonsurgical approaches for milder forms of the disorder and for residual OSAS after T&A is now being investigated.

Transcriptomic analysis identifies phosphatases as novel targets for adenotonsillar hypertrophy of pediatric obstructive sleep apnea

RATIONALE

Obstructive sleep apnea (OSA) is a highly prevalent disorder in children, in which enlarged adenotonsillar tissues (AT) play a major pathophysiologic role. Mechanisms leading to the proliferation and hypertrophy of AT in children who subsequently develop OSA remain unknown, and surgical extirpation of AT is associated with potential morbidity and mortality.

OBJECTIVES

We hypothesized that a computationally based analysis of gene expression in tonsils from children with OSA and children with recurrent tonsillitis without OSA can identify putative mechanistic pathways associated with tonsillar proliferation and hypertrophy in OSA.

METHODS

Palatine tonsils from children with either polysomnographically documented OSA or recurrent infectious tonsillitis were subjected to whole-genome microarray and functional enrichment analyses followed by significance score ranking based on gene interaction networks. The latter enabled identification and confirmation of a candidate list of tonsil-proliferative genes in OSA.

MEASUREMENTS AND MAIN RESULTS

In vitro studies using a mixed tonsil cell culture system targeting one of these candidates, phosphoserine phosphatase, revealed that it was more abundantly expressed in tonsils of children with OSA, and that pharmacological inhibition of phosphoserine phosphatase led to marked reductions in T- and B-lymphocyte cell proliferation and increased apoptosis.

CONCLUSIONS

A systems biology approach revealed a restricted set of candidate genes potentially underlying the heightened proliferative properties of AT in children with OSA. Furthermore, functional studies confirm a novel role for protein phosphatases in AT hypertrophy, and may provide a promising strategy for discovery of novel, nonsurgical therapeutic targets in pediatric OSA.

Leukotriene pathways and in vitro adenotonsillar cell proliferation in children with obstructive sleep apnea

INTRODUCTION

The abundant expression of leukotrienes (LTs) and their receptors in adenotonsillar tissues of children with obstructive sleep apnea (OSA) suggest that LT antagonists could be useful in treating OSA.

METHODS

The effects of LTD4 and of LT receptor antagonists zileuton, montelukast, and BAY u9773 were examined on mixed cell cultures prepared from dissociated tonsils or adenoids harvested intraoperatively from children with polysomnographically diagnosed OSA. Proliferation was assessed by (3)[H]-thymidine incorporation, and inflammatory cytokine production (tumor necrosis factor [TNF]-alpha, interleukin [IL]-6, IL-8, IL-10, and IL-12) was assessed in supernatants using enzyme-linked immunosorbent assay.

RESULTS

LTD4 elicited dose-dependent increases in adenotonsillar cell proliferation (p < 0.001; n = 12). All LT antagonists exhibited dose-dependent reductions in adenotonsillar cellular proliferation rates, with montelukast more than BAY u9773 more than zileuton (n = 14/group; p < 0.001). However, BAY u9773 showed partial agonist effects and increased cellular proliferation at higher concentrations (10(-4) mmol/L; p < 0.01; n = 12). LTD4 effects were partially blocked by montelukast and BAY u9773 but not by zileuton. All three antagonists reduced TNF-alpha, IL-6, and IL-12 concentrations, with selective changes in IL-8 and no effects on IL-10 levels.

CONCLUSIONS

LT pathways mediate intrinsic proliferative and inflammatory signaling pathways in adenotonsillar tissues from children with OSA, and targeted pharmacologic disruption of these pathways may provide nonsurgical alternatives for prevention and treatment of this disease.