Expression of Innate Immunity Genes in Epithelial Cells of Hypertrophic Adenoids with and without Pediatric Chronic Rhinosinusitis: A Preliminary Report

IL-17C expression and its correlation with pediatric adenoids: a preliminary study

Objective: Interleukin-17 (IL-17) C is a cytokine expressed by epithelial cells in response to bacterial stimulation. In contrast to other members of the IL-17 family of cytokines, IL-17C is upregulated early during infection, maintains integrity of the epithelial layer barrier, and mediates the innate immune response. We investigated the expression profile of IL-17C in pediatric adenoids. Methods: Pediatric adenoid tissues and lavage fluids were collected from a total of 38 subjects. The Limulus amebocyte lysate test and real-time PCR using Staphylococcus aureus primers were performed to evaluate bacterial contents in adenoids. Expression of IL-17RE in adenoids was analyzed using real-time polymerase chain reaction and western blot. The expression of IL-17C was evaluated by western blot and immunohistochemistry and compared between allergic rhinitis (AR) and control subjects. The levels of Hsp27, Hsp70, and IL-17C in adenoid lavage fluids were evaluated by enzyme-linked immunosorbent assay, and the correlation between these molecules was statistically analyzed. Results: The pediatric adenoids were found to be exposed to bacteria and had a normal flora comprising both gram-negative and -positive bacteria. IL-17RE, an IL-17C specific receptor, was highly expressed in the epithelium of adenoids. IL-17C was expressed in all evaluated adenoid tissue samples, irrespective of the allergic status of the patient. IL-17C secretion was detected in half of the adenoid lavage fluid samples and was associated with Hsp70 level. Conclusion: Our findings indicate the possible role of pediatric adenoids in innate immunity modulation via an innate immunity-associated cytokine.

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.

Adenoidal Disease and Chronic Rhinosinusitis in Children-Is there a Link?

Adenoid hypertrophy (AH) is an extremely common condition in the pediatric and adolescent populations that can lead to various medical conditions, including acute rhinosusitis, with a percentage of these progressing to chronic rhinosinusitis (CRS). The relationship between AH and pediatric CRS has been extensively studied over the past few years and clinical consensus on the treatment has now been reached, allowing this treatment to become the preferred clinical practice. The purpose of this study is to review existing literature and data on the relationship between AH and CRS and the options for treatment. A systematic literature review was performed using a search line for "(Adenoiditis or Adenoid Hypertrophy) and Sinusitis and (Pediatric or Children)". At the end of the evaluation, 36 complete texts were analyzed, 17 of which were considered eligible for the final study, dating from 1997 to 2018. The total population of children assessed in the various studies was of 2371. The studies were categorized as surgical-observational, microbiological, genetic-immunological, and radiological. The analysis of the studies confirms the relationship between AH and CRS and supports the existing consensus on medical and surgical therapy. Furthermore, these studies underline the necessity to adapt medical and surgical treatment considering age, comorbidities including asthma and, if present, the Computed Tomography (CT) score.

Innate immunity gene expression by epithelial cells of upper respiratory tract in children with adenoid hypertrophy

BACKGROUND

A major role of the innate immunity in the defence of mucosal tissue is well established. However, a balance between the main components of the immunity such as toll-like receptors (TLRs) and defensins in the pathology of upper respiratory tract in children has not been addressed yet. Our aim was to investigate the gene expression of some TLRs as well as alpha and beta-defensins in children suffered from adenoid hyperthrophy in comparison with healthy children.

METHODS

Samples (nasal epithelium and adenoids) from patients with hypertrophic adenoids (n = 77) and control group (n = 33) were investigated. Quantification of HBD-1 and 2 mRNA, alpha-defensin-HNP1 and toll-like receptors (TLR) 2, 4 and 9 mRNA expression was performed by real-time polymerase chain reaction (PCR). The detection of TLR4 and TLR9 was performed by immunohistochemistry.

RESULTS

The main finding of the study is a dramatic up-regulation of TLR2 and TLR4 expression (but down-regulation of TLR9) along with a significant reduction in the expression of the defensins in children with adenoid hyperthrophy.

CONCLUSION

The data suggest that one of the mechanisms of mucosal involvement in the pathogenesis of upper respiratory tract infection might by a disbalance between TLRs and defensins revealed in our study.

Adenoidectomy in Children: What Is the Evidence and What Is its Role?

Purpose of Review

Review the current state of the adenoidectomy procedure in the pediatric population with up-to-date indications for surgery, operative techniques, adverse events, non-surgical management of adenoid hypertrophy, and future directions.

Recent Findings

Adenoidectomy is indicated in children for the treatment of sleep-disordered breathing, nasal airway obstruction, recurrent acute otitis media, and chronic rhinosinusitis. A new recommendation was released in 2016, not supporting adenoidectomy for a primary indication of otitis media in children under 4 years old, including those with prior tympanostomy tubes, unless a distinct indication exists such as nasal obstruction or chronic adenoiditis. Although adenotonsillectomy is the mainstay of treatment for obstructive sleep apnea (OSA), recent studies have identified that non-obese patients with moderate OSA and small tonsils have comparable benefits with adenoidectomy alone with less complications. While conventional approaches such as indirect mirror-assisted curette and suction coagulation are still utilized, direct transnasal endoscope-assisted removal of the adenoids has proven to be a safe technique, with good short- and long-term outcomes. Novel non-surgical therapies including immunotherapy have been evaluated.

Summary

Adenoidectomy is a safe procedure in the pediatric population and leads to excellent outcomes. Adverse events are rare, and hospitalization is uncommon. Children with sleep disturbance from nasal airway obstruction, ear disease, or chronic rhinosinusitis are the best operative candidates for this procedure.