Copy number variation, gene expression and histological localization of human beta-defensin 2 in patients with adeno-tonsillar hypertrophy

Both bacterial infections and innate oral immunity response participate in development of adeno-tonsillar hypertrophy (ATH). ATH can lead to obstructive sleep apnea. We investigated the beta-defensin 2 (hBD-2) encoding gene, DEFB4, by analyzing the copy number variations (CNVs) of the defensin gene cluster in patients with ATH and by correlating CNV with DEFB4 gene expression. We enrolled 79 patients with ATH, 21 of whom presented with only adenoid hypertrophy, while 58 exhibited hypertrophy of both adenoid and tonsil. CNVs of the defensin gene cluster, DEFB4 mRNA, and hBD-2 protein expression were assessed. Also, beta-defensin 2 was localized histologically using immunohistochemistry. The distribution of defensin gene cluster CNV was similar among the 79 subjects. DEFB4 expression analysis exhibited considerable inter-individual variability, but with neither specific differences among subjects nor correlation with the CNV number. Immunohistochemistry enabled localization of hBD-2 in the tonsil and adenoid epithelium. No differences in localization between the two ATH presentations were found. Inducible antimicrobial defensin peptides exhibited great inter-individual variability in terms of both CNV and gene expression, but no correlation with presentation of ATH was found.