A retrospective study of changes of histopathology of nasal polyps in adult Chinese in central China.

BACKGROUND: The factors contributing to the eosinophilic inflammation in chronic rhinosinusitis with nasal polyps (CRSwNP) remain elusive. This study was designed to investigate the inflammatory patterns and tissue remodeling of CRSwNP in patients from central China at two time points over 14 years apart and the influence of age. METHODS: One hundred and eight CRSwNP patients enrolled in 2000 and 2001 (group A), and 134 CRSwNP patients enrolled in 2014 and 2015 (group B) were retrospectively studied. Hematoxylin-eosin stained tissue sections were used to study characteristics of inflammation and tissue remodeling. Immunohistochemistry was used to further evaluate the cells positive for eosinophil cationic protein (ECP), IL-5, IgE, tryptase or myeloperoxidase (MPO). Time- and age-related difference was analyzed. RESULTS: The number of eosinophils and proportion of eosinophilic CRSwNP were increased, whereas the numbers of total inflammatory cells and lymphocytes were decreased in group B as compared with group A. Group B had severer epithelial squamous metaplasia and basement membrane thickening, and a lower number of mucosal glands than group A. Higher numbers of ECP plus, IL-5 plus and IgE plus cells were detected in group B than those in group A. The elderly (60 yrs or older) and non-elderly (less than 60 yrs) had a comparable number of eosinophils and ratio of eosinophilic CRSwNP. CONCLUSION: Eosinophilic inflammation has been significantly augmented over time, which is associated with increased Th2 response and IgE production, and accompanied by exaggerated epithelium remodeling in CRSwNP patients from central China. Age has no significant influence on eosinophilic inflammation.