DIFFERENTIAL EXPRESSION OF IFN-GAMMA, IL-4, IL-10, AND IL-1-BETA MESSENGER-RNAS IN DECALCIFIED TISSUE-SECTIONS OF MOUSE LIPOPOLYSACCHARIDE-INDUCED PERIODONTITIS MANDIBLES ASSESSED BY IN-SITU HYBRIDIZATION

To examine the role of T cell subgroups, Th1 and Th2, in the developme nt of periodontitis, the expression of various cytokines was investiga ted in a mouse model of alveolar bone resorption using in situ hybridi zation (ISH) with digoxigenin-labeled oligonucleotides. When mice rece ived repetitive injections with Escherichia coli lipopolysaccharide in to the gingiva every 48 h, alveolar bone resorption was detectable aft er the fourth injection, reaching a maximum after the 13th injection. For the best performance of ISH, we first had to choose a decalcificat ion protocol. Among various decalcification protocols, 10% EDTA (4 deg rees C, 5-6 days) was the best for 28S rRNA staining. Positive cells f or transcripts of interferon-gamma (Th1 product) were detected after t he fourth injection, reaching a maximum after the tenth injection. A s imilar pattern was obtained for interleukin (IL)-10 mRNA (Th2 product) and IL-1 beta, while the positive cell number reached a maximum after the 13th and 10th injections, respectively. The number of IL-4 mRNA ( Th2 product)-positive cells remained low till the tenth injection, but increased thereafter. Consequently, we found that the population chan ge from Th1 to Th2 in the inflammation site correlated with the transi tion from gingivitis to periodontitis, indicating differential roles o f T cell subgroups in the development of periodontitis.