The role of fractalkine and its receptor expression in adenoid tissue in development of chronic otitis media with effusion

Otitis media with effusion (OME) is defined as a collection of serous or mucous character fluid in the middle ear cavity without signs or symptoms of acute ear infection. OME is referred as choronic if effusion is prolonged more than 3 months. The etiology of OME is multi-factorial but immature function of the immune system and dysfunction of the Eustachian tube are the most important etiologic factors. The other important factors include upper respiratory tract infections, bacterial or viral middle ear infections, allergies, adenoid vegetation, craniofacial abnormalities, gender, age, socioeconomic status, familial predisposition, lack of breastfeeding, lasting baby bottle feeding, parental smoking, seasonal factors and day care or school attandance. Adenoid hypertrophy (AH) has been considered to be one of the possible causes of OME. Mechanical obstruction of the Eustachian tube by hypertrophic adenoid tissue can develop effusion. Not all children with AH have otitis media with effusion. This supports the hypothesis that states adenoid tissue can provoke an inflammatory reaction in the Eustachian tube and middle ear mucosa by releasing inflammatory mediators and this can be the cause of OME. Fractalkine/CX3CL1 and its receptor are members of the chemokine family which is involved in many inflammatory processes in the body. The aim of this study is to reveal the relationship between the expression levels of fractalkine and its receptor in adenoid tissue and Crohnic serous otitis media development. The study was conducted at Başkent University Departments of Otorhinolaryngology and Medical Genetics. It is designed as a prospective, non-randomized, controlled clinical study. Local ethics committee approved the study, and informed consents were obtained from all of the participiants and their family. Adenoid tissue samples are collected from forty-four patients who have AH with OME and fourty-seven patients who have adenoid hypertrophy without OME. The m RNA derived from adenoid tissue converted to c DNA with using Real Time Polymerase Chain Reaction (RT-PCR) technique and the expression of Fractalkine/CX3CL1 and its receptor was determined. Results were compared between the two groups. Blood samples were taken from all patients three days before surgery to determine white blood cells, neutrophil, lymphocyte, eosinophil MPV count, and NLR. All parents whose children included in the study filled out questionnaires about the number of upper respiratory tract infections (URI), acute otitis media in the last year, and duration of breastfeeding, duration of baby bottle, parental smoking, day care or school attandance, and number of siblings. The patients who have immunodeficiency, malignancy, ciliary dysfunction, cystic fibrosis, allergies and previous ear surgery or adenoidectomy history, any active infection, and use of antibiotics, antihistamines or systemic steroids, and nasal steroids in the last two weeks are excluded from the study. There was no statistically significant difference in the expression of fractalkine and its receptor expression levels in adenoid tissue between the OME+ AH and only AH groups (p>0,05). The number of acute otitis media episodes in last one year found statistically significantly higher at OME +AH group (p<0,05). There was no significant difference between the groups in URI episodes, duration of breastfeeding, duration of baby bottle, parental smoking, day care or school attandance, number of siblings (p>0.05). Similarly there was no significant difference at NLR and MPV counts (p>0.05). We divided all patients into two groups according to age and compared the adenoid tissue samples between under 48 months and older than 48 months. Despite no significant difference was detected in the expression of CX3CL1 in adenoid tissue samples, expression of CX3CR1 was significantly higher on children over the age of 48 months (p=0,016). Consequently expression of fractalkine and its receptor that's responsible for inflammation on hypertrophic adenoid tissue were not seen associated with Crohnic OME development. Increased expression of CX3CR1 in adenoid tissue in children over four years may be associated with Crohnic inflammation in adenoid tissue Acute otitis media episodes are found as predisposing factor for otitis media with effusion. MPV and NLR counts which are indicators for choronic inflamation are not affected by local inflammation in the middle ear. These findings are suggesting that the role of the adenoid tissue with development of effusion in middle ear may be associated with Crohnic inflammatory mechanism such as allergy, bacterial colonization, Crohnic adenoiditis rather than obstructive effect. Further studies are needed to investigate relationship between expression of fractalkine and its receptor on adenoid tisue and Crohnic OME development.