Proinflammatory and immunoregulatory cytokines in the middle ear effusions

The recognition of inflammatory mediators in middle ear effusions and their correlation with clinical parameters may allow better understanding of many complex events leading to development of permanent sequelae of otitis media and hopefully help to develop future interventions. The aim of the study was to evaluate the presence and level of proinflammatory interleukin (IL) 1beta, IL-6 and immunoregulatory IL-10 in the middle ear effusions, their mutual correlation and relationship with age, duration of the illness, number of episodes of acute otitis media, and presence of retraction pockets.

The study included 25 children (41 ears), who had been scheduled for myringotomy with the insertion of tympanostomy tubes due to otitis media with effusion. The interview (duration of the illness, number of episodes of acute otitis media), clinical and audiological examination was conducted according to the developed examination check list. Middle ear effusions (MEE) were collected aseptically, the samples centrifuged and supernatant frozen at a temperature of -80 degrees C. The IL-1beta, IL-6 and IL-10 were assayed using enzyme-linked immunosorbent assay (ELISA) kits incorporating monoclonal antibodies and the ETI system reader. The nonparametric Mann-Whitney U test was used for statistical analysis and Pearson's linear correlation coefficient was calculated.

IL-1beta was detected in 80% of examined effusions, IL-6 in 78%, and IL-10 in 88%. There was a strong statistical correlation between IL-1beta and IL-6 concentrations (r=0.627, P=0.000), as well as IL-6 and IL-10 (r=0.66, P=0.000) No statistically significant correlation was found between levels of cytokines and clinical parameters.

Proinflammatory and immunoregulatory cytokines participate in middle ear inflammatory response. The lack of direct correlation between IL-1beta and IL-10 may be responsible for chronic character of the disease. As no correlation between the levels of cytokines and clinical parameters was found it seems that the time of duration of inflammation rather than its intensity measured by levels of cytokines is the main factor in development of middle ear mucosa pathology.