A comparative analysis of the demographic and pathophysiological factors influencing cellular immunity in chronic otitis media-prone children

Otitis media (OM) is a childhood illness that is caused when viral and bacterial commensals ascend the Eustacian tube to enter the middle ear space, where they cause infection, pain, inflammation, and possible effusion. Host determinants including anatomy, physiology, demography and immunity; microbial factors of nasopharyngeal colonisation, inter-microbial and microbial-host relationships; and environmental factors all impact on the risk of developing OM, and the burden caused by the disease. How each of these factors contributes to the disease aetiology is well defined, yet the relationships between these factors and how such relationships contribute to OM are less clearly understood. Host tolerance to microbial colonisation at mucosal sites, including Streptococcus pneumoniae colonisation of the nasopharynx, has been associated with regulatory T (Treg) lymphocytes and suppression of pro-inflammatory responses. What is not known, however, is the association of the Treg lymphocyte population with Moraxella catarrhalis and non-typeable Haemophilus influenzae (NTHi), or with other otopathogen commensal colonisation at the nasopharynx. Nationally, OM in children from regional Queensland on the eastern coast of Australia has not been investigated until now. Herein, a study cohort of 40 children between 2 and 7 years of age from regional Queensland, who were either chronic OM (COM) prone or non-COM prone were included. For each child, the study has assessed multiple factors of demographic, environmental, nasopharyngeal bacterial carriage, lymphocyte subset proportions from the adenoids and blood, and salivary and plasma pneumococcal-specific antibody titres.