Role of IL-22 on the genesis and progression of periapical lesions experimentally induced in teeth of wild type and knockout mice

Abstract

The aim of the present study is to characterize the formation and progression of periapical lesions experimentally induced in the teeth of interleukin 22 knockout (IL-22 KO) mice compared to wild-type (WT) mice. Periapical lesions will be induced in the lower first molars of 28 WT and 27 TLR2 KO mice. After 7, 21 and 42 of periapical lesion induction, the animals will be euthanized in a CO2 chamber, and the mandibles will be removed and subjected to histotechnical processing. Representative histological sections will be stained with hematoxylin and eosin (HE) for description of the features of the pulp tissue and the apical and periapical regions under conventional optical microscopy, and for determination of the size of the periapical lesions under fluorescence microscopy. Sequential specimens will be evaluated by: TRAP histo-enzymology for identification de osteoclasts; Brown & Brenn staining for localization of bacteria; and immunohistochemistry for caracterization of inflamation cells (neutrophils, macrophages, and linphocytes T and B), cytokines expression (IL-1±, TNF-±, INF-³, IL-4, IL-10, and IL-22), and identification of osteoclastogenesis markers (RANK, RANKL, OPG). Data from the morphometric evaluation of the size of periapical lesions and the number of osteoclasts will be subjected to statistical analysis depending the data, using the SAS (Statistical Analysis System) software for Windows version 9.1.3. A significance level of 5% will be set for all analyses. Data from the Brown & Brenn staining and immunohistochemical analysis will be displayed qualitatively. (AU)